Science.gov

Sample records for hydrothermal direct heat

  1. Hydrothermal industrialization: direct heat development. Final report

    SciTech Connect

    Not Available

    1982-05-01

    A description of hydrothermal resources suitable for direct applications, their associated temperatures, geographic distribution and developable capacity are given. An overview of the hydrothermal direct-heat development infrastructure is presented. Development activity is highlighted by examining known and planned geothermal direct-use applications. Underlying assumptions and results for three studies conducted to determine direct-use market penetration of geothermal energy are discussed.

  2. Geothermal hydrothermal direct heat use: US market size and market penetration estimates

    SciTech Connect

    El Sawy, A.H.; Entingh, D.J.

    1980-09-01

    This study estimates the future regional and national market penetration path of hydrothermal geothermal direct heat applications in the United States. A Technology Substitution Model (MARPEN) is developed and used to estimate the energy market shares captured by low-temperature (50 to 150/sup 0/C) hydrothermal geothermal energy systems over the period 1985 to 2020. The sensitivity of hydrothermal direct heat market shares to various government hydrothermal commercialization policies is examined. Several substantive recommendations to help accelerate commercialization of geothermal direct heat utilization in the United States are indicated and possible additional analyses are discussed.

  3. Hydrothermal research and development assessment. Task Force report: projections for direct-heat applications

    SciTech Connect

    Not Available

    1982-04-01

    Low and moderate temperature hydrothermal resources suitable for direct-heat applications have been identified in 37 states. The extent to which three resources might be used over the next 20 years were evaluated and the probable impact of Federal programs on hydrothermal resource utilization was assessed. The use types that comprise the bulk of the market were determined. Representative firms and municipalities were interviewed to determine their willingness to use hydrothermal energy, and to determine the investment decision criteria that would influence their actions. (MHR)

  4. Direct Measurements of Hydrothermal Heat Output at Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Germanovich, L. N.; di Iorio, D.; Genc, G.; Hurt, R. S.; Lowell, R. P.; Holden, J. F.; Butterfield, D. A.; Olson, E. J.

    2009-12-01

    Heat output and fluid flow are key parameters for characterizing seafloor hydrothermal systems at oceanic spreading centers. In particular, they are essential for examining partition of heat and geochemical fluxes between discrete and diffuse flow components. Hydrothermal heat output also constrains permeability of young oceanic crust and thickness of the conductive boundary layer separating hydrothermal circulation from the underlying magmatic heat source. Over the past several years, we have deployed a number of relatively simple devices to make direct measurements of focused and diffuse flow. Most recently, we have used cup anemometer and turbine flow meters to measure fluid flow and heat flux at individual high-temperature vents and diffuse flow sites. The turbine flow meter (Figure 1) includes a titanium rotor assembly housed within a stainless steel tube and supported by sapphire bearings. The device can be used at different seafloor settings for measurements of both diffuse and focused flow. The spin of the rotor blades is videotaped to acquire the angular velocity, which is a function of the flow rate determined through calibration. We report data obtained during four cruises to the Main Endeavor and High Rise vent fields, Juan de Fuca Ridge (JdFR), between 2007 and 2009. Overall more than 50 successful measurements of heat flow have been made on a variety of high-, medium-, and low-temperature hydrothermal sites on the Endeavor, Mothra, and High Rise structures. For example, the velocity of diffuse flow at Endeavor ranged from ~1 to ~10 cm/sec. The flow velocity from black smokers varied from ~10 cm/sec to ~1 m/sec, which appears to be similar to EPR 9°N. Typical measurements of heat flux obtained at JdFR ranged from ~1 kW for diffuse flow to ~1 MW for black smokers. Although it is difficult to extrapolate the data and obtain the integrated heat output for a vent field on JdFR, the data are used to characterize the heat fluxes from individual vent

  5. A multidimensional model of direct-stream heating of newspaper and municipal solid waste in a hydrothermal reactor

    SciTech Connect

    Thorsness, C.B.

    1995-09-28

    Hydrothermal treatment (reaction in a water medium at elevated temperatures) can transform many municipal solid waste (MSW) constituents into a synthetic coal material which is more amenable for use as a fuel or chemical feedstock than the raw MSW. One means of heating the MSW is to use direct high temperature steam injection into a closed reactor and allow the latent heat of the steam to raise the MSW to the desired temperature and at the same time build the pressure necessary to maintain a water phase. This report describes a computer model which can be used to look at details of the steam flow, water evaporation/condensation, thermal evolution, and MSW decomposition in a direct-steam heated MSW hydrothermal reactor. The model treats the system as a packed bed using a Darcy`s law formulation for computing gas flow rates. The model has been applied to a pilot and a commercial scale system. Computations take between 1-6 hours on a HP-9000/730. Initial computations performed with the model indicate that pressure drop and velocities on a pilot scale systems will be small. On the other hand, they indicate that gas velocities inside a commercial scale reactor can reach levels at which entrainment of liquid or solids could occur. In addition, on the commercial scale, model results indicate that in the absence of liquid water flow the thermal coupling between vessel contents and heavy reactor walls should be small thus minimizing unwanted heat loss.

  6. Hydrothermal heat discharge in the Cascade Range, northwestern United States

    USGS Publications Warehouse

    Ingebritsen, S.E.; Mariner, R.H.

    2010-01-01

    Hydrothermal heat discharge in the Cascade Range includes the heat discharged by thermal springs, by "slightly thermal" springs that are only a few degrees warmer than ambient temperature, and by fumaroles. Thermal-spring heat discharge is calculated on the basis of chloride-flux measurements and geothermometer temperatures and totals ~ 240 MW in the U.S. part of the Cascade Range, excluding the transient post-1980 discharge at Mount St. Helens (~80 MW as of 2004-5). Heat discharge from "slightly thermal" springs is based on the degree of geothermal warming (after correction for gravitational potential energy effects) and totals ~. 660. MW. Fumarolic heat discharge is calculated by a variety of indirect and direct methods and totals ~160 MW, excluding the transient mid-1970s discharge at Mount Baker (~80 MW) and transient post-1980 discharge at Mount St. Helens (>. 230. MW as of 2005). Other than the pronounced transients at Mount St. Helens and Mount Baker, hydrothermal heat discharge in the Cascade Range appears to be fairly steady over a ~25-year period of measurement. Of the total of ~. 1050. MW of "steady" hydrothermal heat discharge identified in the U.S. part of the Cascade Range, less than 50. MW occurs north of latitude 45??15' N (~0.1 MW per km arc length from 45??15' to 49??N). Much greater rates of hydrothermal heat discharge south of 45??15'N (~1.7 MW per km arc length from 40?? to 45??15'N) may reflect the influence of Basin and Range-style extensional tectonics (faulting) that impinges on the Cascades as far north as Mount Jefferson but is not evident farther north. ?? 2010.

  7. Direct fired heat exchanger

    DOEpatents

    Reimann, Robert C.; Root, Richard A.

    1986-01-01

    A gas-to-liquid heat exchanger system which transfers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine, to a liquid, generally an absorbent solution. The heat exchanger system is in a counterflow fluid arrangement which creates a more efficient heat transfer.

  8. Enhanced heat transfer in partially-saturated hydrothermal systems

    SciTech Connect

    Bixler, N.E.; Carrigan, C.R.

    1986-01-01

    The role of capillarity is potentially important for determining heat transfer in hydrothermal regions. Capillarity allows mixing of phases in liquid/vapor systems and results in enhanced two-phase convection. Comparisons involving a numerical model with capillarity and analytical models without indicate that heat transfer can be enhanced by about an order of magnitude. Whether capillarity can be important for a particular hydrothermal region will depend on the nature of mineral precipitation as well as pore and fracture size distributions.

  9. Heat and mass transfer in volcano-hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Scott, S. W.

    2015-12-01

    Hydrothermal systems re-distribute heat and mass derived from subsurface magma bodies over large temporal and spatial scales. Numerical models of fluid flow and heat transfer provide a quantitative basis for understanding the thermo-hydrological structure and transient behavior of volcano-hydrothermal systems. At the brittle-ductile transition around a magma body, the rate of conductive heat transfer from the impermeable intrusion is balanced by the rate of advective heat transfer by the fluid. Using the Complex Systems Modeling Platform (CSMP++) to model fluid flow up to near-magmatic conditions, we examine the effect of geologic factors such as host rock permeability, magma emplacement depth, the temperature conditions of the brittle-ductile transition, and rock/magma thermal conductivity on the rates of heat and mass transfer around magma bodies. Additionally, we investigate the role of these factors on the thermo-hydrological structure of the hydrothermal system, including patterns of phase separation, gravity-driven phase segregation, and fluid mixing. Passive tracers are included in the fluid flow models to simulate the input of magmatic volatiles into hydrothermal fluids and their fractionation between the liquid and vapor phases. Ultimately, we compare our model results against measured heat and gas fluxes from volcano-hydrothermal systems to help inform the interpreation of these measurements.

  10. Hydrothermal pretreatment of coal. [Heat and hydrothermal treatment at 350 degrees C

    SciTech Connect

    Ross, D.S.

    1990-05-30

    We recently examined Argonne supplied Wyodak coal under both thermal (no added water, under N{sub 2}) and hydrothermal (liquid water present, under N{sub 2}) conditions at 350{degrees}C for periods of 30 min. and 5 hr. We found that the coal produces a tar that is deposited on the reactor insert walls solely at hydrothermal conditions. The shift from 30 min. to 5 hr. yields a tar that is more volatile and has a slightly increased molecular weight. The coals recovered from thermal and hydrothermal treatments are different by pyrolysis-field ionization mass spectrometry (py-FIMS). Specifically, the hydrothermal condition yields py-FIMS volatiles with a higher weight average molecular weight and greater volatility. They are thus less polar, a conclusion consistent with other py-FIMS data showing that the volatiles from the hydrothermally treated coal are lower in phenolics. Our results show that the phenols and catechols in the coal behave very differently. Our data are consistent with a scheme in which the catechol units in the coal engage in condensation at thermal conditions, probably through a catalyzed process related to acidic sites on the mineral matter. The phenols in contrast are unreactive. At hydrothermal conditions, on the other hand, both are released hydrolytically. Thus it appears that the presence of added water decreases or eliminates thermally promoted crosslinking tied to catechol condensation. Unexpectedly, we see acetone and other simple ketones in the Wyodak pyrolysate from both the thermal and hydrothermal treatment. Acetone in some cases is the single most prominent product. These ketones are not seen, however, in the unconfined py-FIMS heating. The difference between confined and unconfined heating suggest that water evolved from the coal itself in confined heating acts in some hydrolytic fashion to liberate the ketones.

  11. Progress in direct heat applications projects

    SciTech Connect

    Childs, F.W.; Jones, K.W.; Nelson, L.B.; Strawn, J.A.; Tucker, M.K.

    1980-09-09

    The development of hydrothermal energy for direct heat applications is being aided by twenty-two demonstration projects that are funded on a cost-sharing basis by the US Department of Energy, Division of Geothermal Energy. These projects are designed to demonstrate the technical and economic feasibility of the direct use of geothermal heat in the United States. Twelve of these projects are administered by the DOE-Idaho Operations Office with technical support from EG and G Idaho, Inc. Engineering and economic data for these projects are summarized in this paper. The data and experience being generated by these projects will be an important basis for future geothermal direct use projects.

  12. Continuous Hydrothermal Synthesis of Inorganic Nanoparticles: Applications and Future Directions.

    PubMed

    Darr, Jawwad A; Zhang, Jingyi; Makwana, Neel M; Weng, Xiaole

    2017-09-13

    Nanomaterials are at the leading edge of the emerging field of nanotechnology. Their unique and tunable size-dependent properties (in the range 1-100 nm) make these materials indispensable in many modern technological applications. In this Review, we summarize the state-of-art in the manufacture and applications of inorganic nanoparticles made using continuous hydrothermal flow synthesis (CHFS) processes. First, we introduce ideal requirements of any flow process for nanoceramics production, outline different approaches to CHFS, and introduce the pertinent properties of supercritical water and issues around mixing in flow, to generate nanoparticles. This Review then gives comprehensive coverage of the current application space for CHFS-made nanomaterials including optical, healthcare, electronics (including sensors, information, and communication technologies), catalysis, devices (including energy harvesting/conversion/fuels), and energy storage applications. Thereafter, topics of precursor chemistry and products, as well as materials or structures, are discussed (surface-functionalized hybrids, nanocomposites, nanograined coatings and monoliths, and metal-organic frameworks). Later, this Review focuses on some of the key apparatus innovations in the field, such as in situ flow/rapid heating systems (to investigate kinetics and mechanisms), approaches to high throughput flow syntheses (for nanomaterials discovery), as well as recent developments in scale-up of hydrothermal flow processes. Finally, this Review covers environmental considerations, future directions and capabilities, along with the conclusions and outlook.

  13. Direct use of hydrothermal energy: a review of environmental aspects

    SciTech Connect

    O'Banion, K.; Layton, D.

    1981-08-28

    The potential environmental impacts of the exploration, development, and production of hydrothermal geothermal energy for direct use applications are reviewed and evaluated. Mitigation strategies and research and development needs are included. (MHR)

  14. Heat of reaction measurements for hydrothermal carbonization of biomass.

    PubMed

    Funke, Axel; Ziegler, Felix

    2011-08-01

    This paper presents a set of calorimetric measurements with the aim of better understanding the calorific nature of hydrothermal carbonization. Presented values so far show an inadequately high scatter to do so, preventing a well funded assessment of the energetic feasibility of this process. The heat released during hydrothermal carbonization at 240°C measured with the applied differential calorimetry setup is -1.06MJ/kg(glucose,daf) with a standard deviation of 14%, -1.07MJ/kg(cellulose,daf) with a standard deviation of 9%, and -0.76MJ/kg(wood,daf) with a standard deviation of 32%. These results are in good agreement with the theoretically derived maximum heat release. Despite the comparably high experimental standard deviation of these results, their accuracy is considerably higher than previously published results.

  15. Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

    NASA Technical Reports Server (NTRS)

    Stein, Carol A.; Stein, Seth

    1994-01-01

    A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by hydrothermal flow. Approximately 30% of the hydrothermal heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These hydrothermal heat flux estimates are upper bounds, because heat flow measurements require sediment at the site and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting

  16. Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

    NASA Technical Reports Server (NTRS)

    Stein, Carol A.; Stein, Seth

    1994-01-01

    A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by hydrothermal flow. Approximately 30% of the hydrothermal heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These hydrothermal heat flux estimates are upper bounds, because heat flow measurements require sediment at the site and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting

  17. Helium, heat, and the generation of hydrothermal event plumes at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Lupton, John E.; Baker, Edward T.; Massoth, Gary J.

    1999-09-01

    Hydrothermal event plumes are unique water-column features observed over mid-ocean ridges, presumably generated by the sudden release of large volumes of hot, buoyant fluid. Although the specifics of event plume generation are unknown, event plumes have been attributed to the rapid emptying of a hydrothermal reservoir or to rapid heat extraction from a recently emplaced dike or seafloor lava flows. The chemical and thermal signatures of event plumes as compared to the underlying steady-state plumes offer important clues to the generation of event plumes. Event plumes have low 3He/heat ratios of ˜0.4 × 10-17 mol J-1, similar to vent fluids from mature hydrothermal systems. In contrast, the steady-state plumes found beneath the event plumes have elevated and variable 3He/heat ratios of 2 to 5 × 10-17 mol J-1. Fluids collected directly over fresh lava flows have even higher 3He/heat ratios of 2 to 8 × 10-17 mol J-1, up to 30 times the event plume values. These disparate 3He/heat ratios place strong constraints on models of event plume generation, especially models which rely on heat extraction from seafloor eruptions. Published by Elsevier Science B.V.

  18. Measuring fluid flow and heat output in seafloor hydrothermal environments

    NASA Astrophysics Data System (ADS)

    Germanovich, Leonid N.; Hurt, Robert S.; Smith, Joshua E.; Genc, Gence; Lowell, Robert P.

    2015-12-01

    We review techniques for measuring fluid flow and advective heat output from seafloor hydrothermal systems and describe new anemometer and turbine flowmeter devices we have designed, built, calibrated, and tested. These devices allow measuring fluid velocity at high- and low-temperature focused and diffuse discharge sites at oceanic spreading centers. The devices perform at ocean floor depths and black smoker temperatures and can be used to measure flow rates ranging over 2 orders of magnitude. Flow velocity is determined from the rotation rate of the rotor blades or paddle assembly. These devices have an open bearing design that eliminates clogging by particles or chemical precipitates as the fluid passes by the rotors. The devices are compact and lightweight enough for deployment from either an occupied or remotely operated submersible. The measured flow rates can be used in conjunction with vent temperature or geochemical measurements to obtain heat outputs or geochemical fluxes from both vent chimneys and diffuse flow regions. The devices have been tested on 30 Alvin dives on the Juan de Fuca Ridge and 3 Jason dives on the East Pacific Rise (EPR). We measured an anomalously low entrainment coefficient (0.064) and report 104 new measurements over a wide range of discharge temperatures (5°-363°C), velocities (2-199 cm/s), and depths (1517-2511 m). These include the first advective heat output measurements at the High Rise vent field and the first direct fluid flow measurement at Middle Valley. Our data suggest that black smoker heat output at the Main Endeavour vent field may have declined since 1994 and that after the 2005-2006 eruption, the high-temperature advective flow at the EPR 9°50'N field may have become more channelized, predominately discharging through the Bio 9 structure. We also report 16 measurements on 10 Alvin dives and 2 Jason dives with flow meters that predate devices described in this work and were used in the process of their development

  19. Hydrothermal fluxes of solutes, carbon, and heat to Himalayan rivers

    NASA Astrophysics Data System (ADS)

    Evans, Matthew Jared

    Hot springs flow along the base of the Himalayan front in the Narayani river basin of central Nepal. The springs flow near the Main Central Thrust (MCT), in a zone characterized by active uplift and high incision and erosion rates. Water-rock interaction at depth results in hydrothermal fluids with high solute loads. Himalayan rivers flowing through the zones of geothermal activity are enriched in cations, chloride, radiogenic strontium, and germanium. We use a comprehensive sample set of hot spring and river waters to asses the impact of the springs on the chemistry of the Narayani, and to investigate subsurface processes which control the hydrothermal fluid chemistry. Quantification of the hydrothermal fluxes of solutes, carbon dioxide, and heat to the surface depends on hot spring discharge. A chemical mass balance estimate using the high germanium concentrations in the springs yields hot spring discharge near 0.5% of the river discharge. The chemistry of the springs indicates that 12 to 100% of the total alkalinity in the springs is derived from silicates, and hot springs collectively deliver 20% of the silicate alkalinity in the Narayani. High germanium-silicon ratios in the springs can be modeled as a combination of thermodynamic equilibrium effects and Rayleigh fractionation during quartz precipitation. Active degassing and high dissolved carbon dioxide concentrations indicate that the springs are a source of CO2. High delta 13C values in the springs can be modeled with a metamorphic source and extensive sub-surface degassing. CO2 released during metamorphic decarbonation reactions is entrained in the meteoric water of the hydrothermal system. The CO2 flux from the springs is comparable to the total uptake of CO2 by silicate weathering in the Narayani drainage, which suggests that the Himalayan orogen may be a net source of CO2 to the atmosphere. Hydrothermal heat loss is near 745 +/- 313 megawatts. The high heat flux is the result of tectonic

  20. Heat-insulating aerogel composites for a hydrothermal reactor

    NASA Astrophysics Data System (ADS)

    Vedenin, A. D.; Vityaz', P. A.; Galinovskii, A. L.; Ivanova, I. S.; Mazalov, Yu. A.; Pustovgar, A. P.; Sudnik, L. V.

    2016-12-01

    The SiO2-TiO2 aerogel composites used in the heat insulation of a hydrothermal reactor and the method of their fabrication using a liquid glass technology are analyzed. The process of fabrication of the composite material includes the following stages: the ion exchange of sodium liquid glass with the formation of silica hydrosol; the concentration of hydrosol; the formation of hydrogel and its maturing; the formation of alcogel of an SiO2-TiO2 composite material; surface modification; subcritical drying of alcogel with the formation of SiO2-TiO2 composite ambigel; and its heat treatment, granulation, and classification. The influence of infrared absorber (titanium dioxide) and the temperature of heat treatment of an SiO2-TiO2 aerogel composite material on its structural and thermal characteristics is studied.

  1. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the hydrothermal plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the hydrothermal plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  2. Geothermal direct heat applications program summary

    SciTech Connect

    1980-04-01

    The use of geothermal energy for direct heat purposes by the private sector within the US has been quite limited to date. However, there is a large potential market for thermal energy in such areas as industrial processing, agribusiness, and space/water heating of commercial and residential buildings. Technical and economic information is needed to assist in identifying prospective direct heat users and to match their energy needs to specific geothermal reservoirs. Technological uncertainties and associated economic risks can influence the user's perception of profitability to the point of limiting private investment in geothermal direct applications. To stimulate development in the direct heat area, the Department of Energy, Division of Geothermal Energy, issued two Program Opportunity Notices (PON's). These solicitations are part of DOE's national geothermal energy program plan, which has as its goal the near-term commercialization by the private sector of hydrothermal resources. Encouragement is being given to the private sector by DOE cost-sharing a portion of the front-end financial risk in a limited number of demonstration projects. The twenty-two projects summarized herein are direct results of the PON solicitations.

  3. The first measurements of hydrothermal heat output at 9°50‧N, East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Ramondenc, Pierre; Germanovich, Leonid N.; Von Damm, Karen L.; Lowell, Robert P.

    2006-05-01

    Despite the importance of the heat output of seafloor hydrothermal systems for the Earth's energy budget, hydrothermal heat output measurements have been very limited. In this paper, we report the first measurements of hydrothermal heat output at the RIDGE 2000 Integrated Study Site on the East Pacific Rise. We focused our work on the Bio 9 complex, situated at 9°50'N, where there has been an extensive measurement and sampling program since 1991. This site is located along the eruptive fissure of the 1991/1992 event and the site of the 1995 earthquake swarm. We made direct measurements of advective heat output at several individual vents and at one site of diffuse flow (Tica). Although these data do not describe the complete heat flux picture at this vent field, the data yield a total hydrothermal heat output of ˜ 325 ± 160 MW with ˜ 42 ± 21 MW coming from high-temperature vents along this 2 km segment of ridge. This result assumes a diffuse flux similar to that measured at Tica occurs at each high-temperature vent site. Our initial measurements thus suggest that the heat output of the low-temperature diffuse venting is approximately 10 times that of the high-temperature vents, but may also be one or two orders of magnitude greater.

  4. Hydrothermal circulation at slow spreading ridges: Analysis of heat sources and heat transfer processes

    NASA Astrophysics Data System (ADS)

    Lowell, Robert P.

    Hydrothermal processes on slow spreading ridges exhibit several features that distinguish them from their counterparts at fast and intermediate rate spreading centers. These differences may reflect differences in magma supply rates, type of host rock, and the interplay between magmatism and tectonic extension. As a result, the heat sources and driving mechanisms for hydrothermal circulation at slow spreading ridges may differ from those on fast and intermediate spreading ridges. This paper reviews various heat sources and heat transfer processes at slow spreading ridges, including mantle heat flux, mining of crustal heat, the role of exothermic chemical reactions, and magmatic heat sources. The analyses suggest that for high-temperature, high-output systems such as TAG, Rainbow, and Lucky Strike on the Mid-Atlantic Ridge and Kairei on the Central Indian Ridge, heat transfer from convecting, an actively replenished subaxial magma chamber is required to maintain these systems on decadal time scales. Low-temperature off-axis systems such as Lost City are likely driven by heat extraction from the crust, perhaps in conjunction with downward fluid migration in reactivated faults. Serpentinization reactions appear to play a smaller role. Broken Spur is a relatively low heat output system that is likely driven by magma, but it may be in a waning phase.

  5. Heat flux from magmatic hydrothermal systems related to availability of fluid recharge

    USGS Publications Warehouse

    Harvey, M. C.; Rowland, J.V.; Chiodini, G.; Rissmann, C.F.; Bloomberg, S.; Hernandez, P.A.; Mazot, A.; Viveiros, F.; Werner, Cynthia A.

    2015-01-01

    Magmatic hydrothermal systems are of increasing interest as a renewable energy source. Surface heat flux indicates system resource potential, and can be inferred from soil CO2 flux measurements and fumarole gas chemistry. Here we compile and reanalyze results from previous CO2 flux surveys worldwide to compare heat flux from a variety of magma-hydrothermal areas. We infer that availability of water to recharge magmatic hydrothermal systems is correlated with heat flux. Recharge availability is in turn governed by permeability, structure, lithology, rainfall, topography, and perhaps unsurprisingly, proximity to a large supply of water such as the ocean. The relationship between recharge and heat flux interpreted by this study is consistent with recent numerical modeling that relates hydrothermal system heat output to rainfall catchment area. This result highlights the importance of recharge as a consideration when evaluating hydrothermal systems for electricity generation, and the utility of CO2 flux as a resource evaluation tool.

  6. Direct synthesis of thermochromic VO{sub 2} through hydrothermal reaction

    SciTech Connect

    Alie, David; Gedvilas, Lynn; Wang, Zhiwei; Tenent, Robert; Engtrakul, Chaiwat; Yan, Yanfa; Shaheen, Sean E.; Dillon, Anne C.; Ban, Chunmei

    2014-04-01

    Thermochromic VO{sub 2} was directly synthesized using hydrothermal techniques. The effects of formation conditions on the structure and morphology of the final product were studied through X-ray diffraction (XRD), and scanning electron microscopy (SEM). Unique hollow sphere morphology was observed for the synthesized VO{sub 2} powders. Ex-situ XRD studies after heat treatment confirmed the thermal stability of the VO{sub 2} structure. Thermochromic properties, as a consequence of the reversible structural transformation between monoclinic VO{sub 2} and tetragonal phases, were observed by Fourier transform infrared spectroscopy (FTIR). - Graphical abstract: Thermochromic VO{sub 2} crystals with hollow spherical and asterisk shape were directly synthesized using hydrothermal techniques. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies confirmed the thermal stability and the reversible thermochromic properties of the VO{sub 2} structure. - Highlights: • One-step synthesis of thermochromic VO{sub 2} monoclinic phase, and VO{sub 2} (A and B phases) using hydrothermal technique. VO{sub 2} (A), VO{sub 2} (B). • Identification of the relationship between synthesis conditions and the morphology/structure of the final products. • Formation of VO{sub 2} monoclinic phase with an interesting hollow sphere shape. • Demonstration of superior thermal stability of the VO{sub 2} monoclinic phase. • Characterizing the thermochromic properties of VO{sub 2} monoclinic phase.

  7. Heat stress dictates microbial lipid composition in hydrothermal marine sediments

    NASA Astrophysics Data System (ADS)

    Sollich, M.; Yoshinaga, M. Y.; Häusler, S.; Hinrichs, K. U.; Bühring, S. I.

    2016-02-01

    Abundant and diverse microbial communities inhabit hydrothermal marine sediments. Since ion permeability of membranes increases with temperature archaea and bacteria that use proton/sodium as coupling ions for bioenergetics must constantly adjust their cytoplasmic membrane permeability, which in turn is mostly controlled by the lipid composition. Here, we investigated a thermal gradient across a marine sediment field (ranging from 18 to over 100°C) and tested the concept that membrane lipids provide a major biochemical basis for cellular bioenergetics of archaea and bacteria under stressful conditions. Reflecting the lower ion permeability of the ether-linked isoprenoidal lipids, we found that archaea dominate over bacteria in sediments of >50 °C. Moreover, a detailed examination of the molecular lipid species revealed a quandary: low membrane permeability concomitantly with increased fluidity is required for energy conservation of both archaea and bacteria under heat stress. For instance, bacterial fatty acids were found to increase chain length in concert with a higher degree of unsaturation at elevated sediment temperatures while archaeal tetraethers were observed to show a higher degree of bulking (e.g. methylation and H-shaped) and fluidity (i.e. cyclization) under elevated temperatures. In addition, our data indicate that strong intermolecular hydrogen bonding at the headgroup level of archaeal glycolipids and bacterial sphingolipids may provide ideal membrane stability to attain the required balance between low permeability and a more fluidized configuration. For example, sphingolipids may stabilize bacterial phospholipids into lipid domains, enabling bacteria to thrive in heated sediments under unfavorable thermodynamic conditions. The scientific marriage of lipidomics and bioenergetics described here provides a new dimension for understanding microbial life in natural environments.

  8. Availability of Heat to Drive Hydrothermal Systems in Large Martian Impact Craters

    NASA Technical Reports Server (NTRS)

    Thorsos, I. E.; Newsom, H. E.; Davies, A. G.

    2001-01-01

    The central uplift in large craters on Mars can provide a substantial source of heat, equivalent to heat produced by the impact melt sheet. The heat generated in large impacts could play a significant role in hydrothermal systems on Mars. Additional information is contained in the original extended abstract.

  9. Hydrothermal heat flux through aged oceanic crust: where does the heat escape?

    NASA Astrophysics Data System (ADS)

    Villinger, Heinrich; Grevemeyer, Ingo; Kaul, Norbert; Hauschild, Jan; Pfender, Marion

    2002-08-01

    Recent publications suggest that most of the fluid flow in the upper oceanic crust is channelized through small volumes of rock and vented into the ocean. This implies that at flanks of generally thinly sedimented mid-ocean ridges, focused discharge at the seafloor should be concentrated most likely at outcrops, high-angle normal faults or seamounts. These vents should be associated with a significant heat flow signature. However, only few observations worldwide support this assumption up to now. On our quest for focused fluid exchange between young oceanic crust and the ocean we surveyed a 720 km long and 40-90 km wide off-axis portion of seafloor intersecting the East Pacific Rise near 14°14'S. A wealth of geophysical methods including high-resolution swath mapping bathymetry, single channel seismics, sediment echo sounding, magnetics and heat flow determinations were used. Heat flow data in the tectonic corridor cover crustal ages of 0.3-9.3 Ma. With respect to the conductive plate cooling model the data show the well-known pattern of low values close to the ridge, associated with vigorous hydrothermal circulation of cold seawater through the young upper crust, and a fast recovery to almost lithospheric conductive cooling values at a surprisingly young crustal age of 9.3 Ma. Although the sediment cover is fairly thin, measurements with a 3.6 m violin bow type heat probe were possible almost everywhere within the investigated area. A detailed survey between two large seamounts at 4.5 Ma revealed localized extremely high values of up to 618 mW/m 2 (275% of the expected heat flow) at the foot of the seamount. This is interpreted as a clear indication of focused discharge of hydrothermal fluid. If we, however, relate heat flow normalized by the expected conductive heat loss to the character of igneous basement, heat flow is highest in areas with an almost flat and sedimented basement, and lowest within ˜10-20 km of seamounts and other rough basement relief. We

  10. Variable heat-flow patterns and hydrothermal processes near the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Lucazeau, Francis

    2014-05-01

    Oceanic heat-flow is commonly affected by water circulation. The primary mechanism was identified by Lister (1972) near the Juan de Fuca ridge (NE Pacific) and attributed to hydrothermal flow within the oceanic basement: sea-water recharges at certain seamounts, flows within the high-permeability basement below the sediments and discharges at other seamounts. As a result, the heat-flow measured at the ocean bottom is significantly lower than expected for a conductively cooling lithosphere, as long as the fluid is not in equilibrium with the host rock. But this is not the only mechanism for low heat-flow values in the oceanic lithosphere: near the Mid-Atlantic ridge, Langseth et al (1992) have identified the process of sea-water drawdown into the sediments. Here we present results from a recent heat-flow survey (OCEANOGRAFLU, June 2013) on the Mid-Atlantic Ridge flanks at about 35°N, close to the Oceanographer fracture zone, where we have observed similar evidences that sea-water can flow directly into the surficial sediments. Where the heat-flow is lower than the conductive cooling values, the temperature-depth profiles are systematically non-linear, showing sigmoid shapes or negative gradients, and the sediment porewaters have compositions close to that of sea-water. No clear evidence for basement recharge or discharge is observed, which differs significantly from the results of a previous study 400 km North, where the heat-flow pattern was more consistent with water flowing into the oceanic basement rather than into the sediment (Lucazeau et al, 2006). We will present the relevant observations and examine the possible causes for the different processes affecting the heat-flow in the Mid-Atlantic Ridge flanks.

  11. Heat Source for Active Venting at the Lost City Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

    2014-12-01

    Located at the inside corner high of the Mid-Atlantic Ridge (MAR), 30°N and the Atlantis Transform Fault (ATF), the Atlantis Massif has been uplifted over the past ~2 my. The Southern Ridge of this massif hosts the Lost City Hydrothermal Field (LCHF), an off-axis hydrothermal vent field with carbonate chimney ages surpassing 120,000 yrs. The fluids discharging at LCHF carry geochemical signals that show a direct interaction with serpentinites. However, mineralogical evidence suggests that peridotite hydration began early in the formation of oceanic core complexes and previous modeling results indicate that serpentinization is unlikely to generate the heat necessary to maintain current levels of discharge at LCHF. This work develops a model for the LCHF venting based on the evidence of tectonic strain, detachment faulting, serpentinization, and convective fluid flow. We constrain fluid flow at the LCHF by vent geochemistry, vent temperature, seismically inferred faulting, and expected geothermal gradient ≈100°C/km. Present understanding of tectonic processes at the intersection of MAR and ATF suggests that unroofing of the footwall and crustal flexing of the massif induced normal faults, which run parallel to the MAR, throughout the Southern Ridge. In the absence of the evidence of magmatism, we test the feasibility of the geothermal gradient to cause fluid circulation in the high-permeability, sub-vertical fault zone. Fluid circulation in the fault zone is complemented by the bulk porous flow driven through the Southern Ridge by the lateral temperature gradient between the cold water on the steep face along the ATF side and the hot interior of the massif. In this scenario, the high pH hydrothermal fluids pass through the serpentinized zone before discharging as both high-temperature focused flow (40°-91°C) and low-temperature (≈15°C) diffuse flow at the LCHF.

  12. An Assessment of Magma-Hydrothermal Heat Output at the Costa Rica Rift

    NASA Astrophysics Data System (ADS)

    Lowell, R. P.; Morales Maqueda, M. A.; Banyte, D.; Zhang, L.; Tong, V.; Hobbs, R. W.; Harris, R. N.

    2016-12-01

    A joint geophysical/physical oceanographic investigation of the Costa Rica Ridge as part of the OSCAR (Oceanographic and Seismic Characterization of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge) research program enables us to estimate hydrothermal heat output and its likely link to a sub-axial magma lens (AML). In December 2014, a number of tow-yo casts were made along and near the ridge axis where seismic reflection data collected in 1994 showed the presence of seismic reflector interpreted to be an AML at a depth of about 2800 m below the seafloor. A decline in beam transmission in a ≈ 200 m thick region located approximately 800 to 900 meters above the seafloor indicated the presence of a hydrothermal plume. CTD data collected above the ridge yielded a weighted average buoyancy frequency of approximately 19.3 x 10-8 s-2. Assuming a mean hydrothermal vent temperature of 350°C, buoyant plume theory yields a heat output between 400 and 600 MW. Application of the single-pass modeling approach to the hydrothermal system, yields an estimated mass flow between 210 and 337 kg/s, and the mean product of crustal permeability x discharge area ranges between 6 and 10 x 10-9 m4. A multichannel seismic profile collected in 2015 indicates the presence of a reflector 5 km along-axis and < 100 m wide, in approximately the same location as the 1994 survey, suggesting that magma-driven hydrothermal heat output may have exhibited stability on a decadal time scale. The relatively small size of the inferred AML, when coupled to the heat output estimate and the single-pass model, suggests that the conductive boundary layer at the top the AML is 2m thick and that the AML must be frequently replenished to maintain stable heat output. Assuming the hydrothermal system is driven by magmatic latent heat, a 100 m thick AML could have powered a 100 MW hydrothermal system for 20 years, while inputting 5 x 107 m3 of melt into the axis. These results indicate

  13. Direct Hydrothermal Synthesis of Carbonaceous Silver Nanocables for Electrocatalytic Applications.

    PubMed

    Chen, Chuyang; Suryanto, Bryan Harry Rahmat; Zhao, Chuan; Jiang, Xuchuan; Yu, Aibing

    2015-08-05

    This study demonstrates a facile but efficient hydrothermal method for the direct synthesis of both carbonaceous silver (Ag@C core-shell) nanocables and carbonaceous nanotubes under mild conditions (<180 °C). The carbonaceous tubes can be formed by removal of the silver cores via an etching process under temperature control (60-140 °C). The structure and composition are characterized using various advanced microscopic and spectroscopic techniques. The pertinent variables such as temperature, reaction time, and surfactants that can affect the formation and growth of the nanocables and nanotubes are investigated and optimized. It is found that cetyltrimethylammonium bromide plays multiple roles in the formation of Ag@C nanocables and carbonaceous nanotubes including: a shape controller for metallic Ag wires and Ag@C cables, a source of Br(-) ions to form insoluble AgBr and then Ag crystals, an etching agent of silver cores to form carbonaceous tubes, and an inducer to refill silver particles into the carbonaceous tubes to form core-shell structures. The formation mechanism of carbonaceous silver nanostructures depending upon temperature is also discussed. Finally, the electrocatalytic performance of the as-prepared Ag@C nanocables is assessed for the oxidation reduction reaction and found to be very active but much less costly than the commonly used platinum catalysts. The findings should be useful for designing and constructing carbonaceous-metal nanostructures with potential applications in conductive materials, catalysts, and biosensors.

  14. Mapping Ground Temperature and Radiant Hydrothermal Heat Flux on Mammoth Mountain, CA

    NASA Astrophysics Data System (ADS)

    Lewis, A. J.; Lewicki, J. L.; Hilley, G. E.

    2014-12-01

    Quantifying the spatial and temporal variability of ground temperatures and hydrothermal heat fluxes in volcanic and geothermal systems is important for monitoring volcanic activity, monitoring the impacts of geothermal development, and assessing resources. We used ground based thermal infrared (TIR) imaging combined with Structure-from-Motion (SfM) photogrammetry to produce high-resolution (cm scale) DEMs over which images of ground temperature and radiant hydrothermal heat flux were draped. We apply this methodology to two hydrothermal areas (Mammoth Mountain and South Side fumaroles) on Mammoth Mountain, CA, allowing us to image the detailed topography, map the thermal features at each area and assess the spatial relationships between the two efficiently and at high resolution. Mammoth Mountain is a lava-dome complex located on the southwestern rim of Long Valley caldera, CA. Unrest at Mammoth Mountain is currently manifested by seismic swarms, ground deformation, elevated 3He/4He ratios in gases at the Mammoth Mountain fumarole, and large changes in diffuse magmatic CO2 emissions from the five tree kill areas on the volcano flanks. We augment the extensive dataset collected at this site over the previous decades by quantifying ground temperatures and hydrothermal heat fluxes at the Mammoth Mountain and South Side fumarole sites. This was accomplished using a hand-held FLIR T650sc camera that simultaneously acquires visible and TIR images of the study site. Daytime and nighttime co-located visible and TIR images were acquired over each study area, and image processing was used to orthorectify and mosaic visible and TIR images, calculate radiant hydrothermal heat fluxes, construct 3D imagery of ground surface, overlay maps of ground temperatures and heat fluxes, and establish spatial relationships between topography and heat flow.

  15. Constraints on the Lost City Hydrothermal System from borehole thermal data; 3-D models of heat flow and hydrothermal circulation in an oceanic core complex.

    NASA Astrophysics Data System (ADS)

    Titarenko, S.; McCaig, A. M.

    2014-12-01

    A perennial problem in near-ridge hydrothermal circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local hydrothermal flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain hydrothermal circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City Hydrothermal Field (LCHF) is located only 5km to the south. We have modelled hydrothermal circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent site in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography

  16. Directional control of radiant heat

    NASA Technical Reports Server (NTRS)

    Howell, J. R.; Perlmutter, M.

    1970-01-01

    Surface with grooves having flat bases gives directional emissivities and absorptivities that can be made to approximate a perfect directional surface. Radiant energy can then be transferred in desired directions.

  17. Finite element analysis of heat transport in a hydrothermal zone

    SciTech Connect

    Bixler, N.E.; Carrigan, C.R.

    1987-01-01

    Two-phase heat transport in the vicinity of a heated, subsurface zone is important for evaluation of nuclear waste repository design and estimation of geothermal energy recovery, as well as prediction of magma solidification rates. Finite element analyses of steady, two-phase, heat and mass transport have been performed to determine the relative importance of conduction and convection in a permeable medium adjacent to a hot, impermeable, vertical surface. The model includes the effects of liquid flow due to capillarity and buoyancy and vapor flow due to pressure gradients. Change of phase, with its associated latent heat effects, is also modeled. The mechanism of capillarity allows for the presence of two-phase zones, where both liquid and vapor can coexist, which has not been considered in previous investigations. The numerical method employs the standard Galerkin/finite element method, using eight-node, subparametric or isoparametric quadrilateral elements. In order to handle the extreme nonlinearities inherent in two-phase, nonisothermal, porous-flow problems, steady-state results are computed by integrating transients out to a long time (a method that is highly robust).

  18. OSCAR - Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge

    NASA Astrophysics Data System (ADS)

    Hobbs, R. W.

    2016-12-01

    The cooling of oceanic crust is the principal physical process responsible for removing heat from the solid Earth to the hydrosphere. The nature of the heat flow process has a significant effect on the creation and ageing of oceanic crust. Close to the ridge-axis seismic velocity and density increase rapidly as the permeability of recently accreted crust is reduced by chemical alteration and mineral deposition through hydrothermal circulation. The maximum depth of this circulation is poorly constrained though, especially at ridges that do not host significant axial magma chambers, which in turn has implications for crustal formation processes. In the oceans, the processes and regions involved in the heating of the cold abyssal water, necessary to close the global thermohaline circulation cycle, are in dispute. Models of ocean circulation which include spatially varying heat flux based on crustal age show that geothermal heating is an important process. Although small compared to solar heating of the ocean's surface, geothermal heating of the abyssal ocean is unidirectional and directly heats the bottom boundary layer. A combined geophysical and oceanographic experiment has been conducted in the Panama basin to constrain the effects of heat and mass flux through young ocean crust to the ocean. At a full spreading rate of 66 mm/yr, the ridge system is classed as intermediate to fast and the Carnegie and Cocos ridges form a contained basin where the heat gain by the ocean can be determined. Based on a simple cooling curve,the OSCAR data show that the geothermal contribution is over 70% to the abyssal water upwelling. This is the largest contribution yet observed in abyssal basins and is in line with a growing number of studies arguing that geothermal heating plays a significant role in this upwelling.

  19. Time-series measurement of hydrothermal heat flux at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Xu, Guangyu; Jackson, Darrell R.; Bemis, Karen G.; Rona, Peter A.

    2014-10-01

    Continuous time-series observations are key to understanding the temporal evolution of a seafloor hydrothermal system and its interplay with thermal and chemical processes in the ocean and Earth interior. In this paper, we present a 26-month time series of the heat flux driving a hydrothermal plume on the Endeavour Segment of the Juan de Fuca Ridge obtained using the Cabled Observatory Vent Imaging Sonar (COVIS). Since 2010, COVIS has been connected to the North East Pacific Time-series Underwater Networked Experiment (NEPTUNE) observatory that provides power and real-time data transmission. The heat flux time series has a mean value of 18.10 MW and a standard deviation of 6.44 MW. The time series has no significant global trend, suggesting the hydrothermal heat source remained steady during the observation period. The steadiness of the hydrothermal heat source coincides with reduced seismic activity at Endeavour observed in the seismic data recorded by an ocean bottom seismometer from 2011 to 2013. Furthermore, first-order estimation of heat flux based on the temperature measurements made by the Benthic and Resistivity Sensors (BARS) at a neighboring vent also supports the steadiness of the hydrothermal heat source.

  20. Radiant heat transfer between nongray directional surfaces.

    NASA Technical Reports Server (NTRS)

    Fischer, W. D.; Hering, R. G.

    1972-01-01

    Real surface property effects on local and overall heat transfer are studied for a simple system of interacting opaque surfaces. Wavelength, temperature and directional dependence of surface properties is included in the analysis for equal and unequal temperature specularly reflecting surfaces. Tungsten is employed as a representative metal and Roberts' model is used to describe the wavelength and temperature dependence of its optical parameters. The relationships of electromagnetic theory are employed to describe the directional dependence of spectral properties. Numerical results establish that gray direction independent property analysis adequately predicts the general trends of real surface analysis. The results also establish that spectral and temperature dependence of surface properties influences radiant heat transfer to a greater degree than does directional dependence of properties. Property models which adequately account for the nongray character of engineering surfaces while neglecting directional dependence of properties can provide heat transfer results of acceptable engineering accuracy.

  1. Hydrothermal carbonization of sugarcane bagasse via wet torrefaction in association with microwave heating.

    PubMed

    Chen, Wei-Hsin; Ye, Song-Ching; Sheen, Herng-Kuang

    2012-08-01

    Hydrothermal carbonization of sugarcane bagasse using wet torrefaction is studied. The biomass is torrefied in water or dilute sulfuric acid solution and microwaves are employed to heat the solutions where the reaction temperature is fixed at 180 °C. The effects of acid concentration, heating time and solid-to-liquid ratio on the performance of wet torrefaction are investigated. It is found that the addition of sulfuric acid and increasing heating time are conducive to carbonizing bagasse. The calorific value of bagasse can be increased up to 20.3% from wet torrefaction. With the same improvement in calorific value, the temperature of wet torrefaction is lower than that of dry torrefaction around 100 °C, revealing that wet torrefaction is a promising method to upgrade biomass as fuel. The calorific value of torrefied biomass can be predicted well based on proximate, elemental or fiber analysis, and the last one gives the best estimation.

  2. Hydrothermal flow regime and magmatic heat source of the Cerro Prieto geothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Schiffman, P.; Williams, A.E.

    1984-01-01

    This detailed three-dimensional model of the natural flow regime of the Cerro Prieto geothermal field, before steam production began, is based on patterns of hydrothermal mineral zones and light stable isotopic ratios observed in rock samples from more than 50 deep wells, together with temperature gradients, wireline logs and other data. At the level so far penetrated by drilling, this hydrothermal system was heated by a thermal plume of water close to boiling, inclined at 45/sup 0/, rising from the northeast and discharging to the west. To the east a zone of cold water recharge overlies the inclined thermal plume. Fission track annealing studies show the reservoir reached 170/sup 0/C only 10/sup 4/ years ago. Oxygen isotope exchange data indicate that a 12 km/sup 3/ volume of rock subsequently reacted with three times its volume of water hotter than 200/sup 0/C. Averaged over the duration of the heating event this would require a flow velocity through a typical cross-section of the reservoir of about 6 m/year. The heat in storage in that part of the reservoir hotter than 200/sup 0/C and shallower than 3 km depth is equivalent to that which would be released by the cooling of about 1 or 2 km/sup 3/ of basalt or gabbro magma.

  3. Dual-scale hydrothermal circulation inferred from detailed heat flow measurements in the Suiyo Seamount Hydrothermal System, Izu-Bonin Arc

    NASA Astrophysics Data System (ADS)

    Gomado, M.; Kinoshita, M.

    2002-12-01

    Hydrothermal activity within the caldera of Suiyo Seamount was investigated in detail using manned or remotely-operated submersibles, and by deep-tow imagery and seismic surveys. Hydrothermal regime in the Suiyo-seamount is characterized by a geochemically uniform fluid, shallow reservoir depth, very permeable seafloor, and venting without creating big chimneys. Detailed heat flow surveys were carried out through four research cruises conducted in 2001-2002. Geothermal probes, called SAHF (Stand-Alone Heat Flow) meter, are 1m in length, and five thermistors are installed at 11-12 cm intervals. Heat flow is highest (> 10 W/m2) within the active area. These values were obtained close to black smokers, thus are affected by the venting or very shallow reservoirs. To the east, heat flow is uniform around 4 W/m2. Since there were no indications of discharge, this area is dominated by thermal conduction, and its heat source would be a hydrothermal reservoir capped by some impermeable layer. To the west, we detected very low heat flow values of less than 0.3 W/m2, only several tens of meters away from the active area. A similar heat flow anomaly was detected in the TAG hyudrothermal mound of the Mid-Atlantic Ridge (Becker et al., 1996). We penetrated at 1-2 m away from two isolated active sulfide mounds. At both sites subbottom temperatures were about 40 degC at 10-20 cm depth, then they decreased to about 20 degC at 30-40cm. The temperature reversals suggest a meter-scale hydrothermal circulation, where a hot fluid discharges as a branch flow from the main vent to the mound. An impermeable structure of the mound and a permeable sediment surrounding the mound would make this very local circulation possible. We suggest a dual scale hydrothermal circulation system, one with several meters scale, and the other with few tens of meters scale. The former would be driven by a suction created by discrete venting of high temperature fluid, and the latter is a regional

  4. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    SciTech Connect

    Stein, J.S.; Fisher, A.T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  5. Direct expansion solar collector and heat pump

    NASA Astrophysics Data System (ADS)

    1982-05-01

    A hybrid heat pump/solar collector combination in which solar collectors replace the outside air heat exchanger found in conventional air-to-air heat pump systems is discussed. The solar panels ordinarily operate at or below ambient temperature, eliminating the need to install the collector panels in a glazed and insulated enclosure. The collectors simply consist of a flat plate with a centrally located tube running longitudinally. Solar energy absorbed by exposed panels directly vaporizes the refrigerant fluid. The resulting vapor is compressed to higher temperature and pressure; then, it is condensed to release the heat absorbed during the vaporization process. Control and monitoring of the demonstration system are addressed, and the tests conducted with the demonstration system are described. The entire heat pump system is modelled, including predicted performance and costs, and economic comparisons are made with conventional flat-plate collector systems.

  6. Direct-Interface, Fusible Heat Sink

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis; Webbon, Bruce

    1992-01-01

    Nonventing, regenerable, and self-contained heat sink absorbs heat in melting of ice by direct contact with forced flow of warm water. Elastic bladder contains water and ice. Connectors designed to prevent leaks easily connectable and disconnectable. Female portions embedded in wall of heat sink. After water frozen, male portions inserted and flow of warm water initiated. Water melts ice in and around female connectors, then flow passes between ice and bladder from inlet to outlet. Component of low-power portable refrigerator to operate for short time in picnic or camp setting.

  7. Rheological and stability aspects of dry and hydrothermally heat treated aleurone-rich wheat milling fraction.

    PubMed

    Bucsella, Blanka; Takács, Ágnes; von Reding, Walter; Schwendener, Urs; Kálmán, Franka; Tömösközi, Sándor

    2017-04-01

    Novel aleurone-rich wheat milling fraction developed and produced on industry scale is investigated. The special composition of the novel flour with high protein, dietary fiber and fat content results in a unique combination of the mixing and viscosity properties. Due to the high lipid concentration, the fraction is exposed to fast rancidity. Dry heat (100°C for 12min) and hydrothermal treatment processes (96°C for 6min with 0-20 L/h steam) were applied on the aleurone-rich flour to modify the technological properties. The chemical, structural changes; the extractability of protein, carbohydrate and phenolic components and the rheological characteristics of the flours were evaluated. The dry treated flour decreased protein and carbohydrate extractability, shortened dough development time, reduced gel strength and enhanced the gelling ability. Hydrothermal treatment caused changes in the phenolic content improved the dough stability and -resistance. Heat treatment processes were able to extend the stability of the flour. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3

    USGS Publications Warehouse

    Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.

    2008-01-01

    The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined

  9. Heat Flow and Hydrothermal Circulation of the Lucky Strike Segment, Mid Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Bonneville, A.; Escartin, J.; Lucazeau, F.; Cannat, M.; Gouze, P.; von Herzen, R. P.; Adam, C.; Le Bars, M.; Monoury, E.; Vidal, V.

    2003-12-01

    In June 2003, expedition Luckyflux aboard the R/V Poseidon conducted a heat flow survey of a zone centred on the Lucky Strike segment of the Mid Atlantic ridge south of the Azores between ˜35° N and 39° N. Using a 5 m-long lance with 7 outrigger thermal probes, about 150 successful thermal gradient measurements were obtained, 140 of these with in-situ thermal conductivity. Measurements were made at ˜1 mile intervals along several profiles, where adequately sedimented sites were identified using 6-channel and 3.5 kHz seismic data from the previous Sudazores'98 cruise. We conducted heat flow measurements in two areas: a near axis region within the V-shaped ridge of overthickened crust that emanated from the Azores hotspot between ˜14 and 4 Ma, and an off-axis region East of the V-shaped ridge. The off-axis region is characterized by an homogeneous sediment cover, 300-400 m thick, and crustal ages varying between ˜6 and >10 Ma. Long wavelength (tens of km) low heat flow anomalies can be identified but the mean of 160 mWm-2 is comparable to the conductive heat flow expected for a crust of that age. Along two 80-km profiles perpendicular to the ridge, we observed coherent but different patterns. On the first profile, low heat flow values of 20-50 mWm-2 are observed at the base of the V-shaped ridge. These values are 100 mWm-2 below the profile average, showing that hydrothermal circulations can also affect oceanic crust beneath a thick and relatively impermeable sediment cover. On the other profile, heat flow generally decreases from west to east. On both profiles, higher than average values of heat flow are also present, associated on one of them with a nearly outcropping basement elevation. These contrasting overall heat flow patterns in similar geological context indicate that the likely pattern of hydrothermal circulations is mainly 3D, and not driven only by the presence of basement outcrops. In the near-axis region, where the tectonic structure is more

  10. Tuning the Electronic Conductivity in Hydrothermally Grown Rutile TiO₂ Nanowires: Effect of Heat Treatment in Different Environments.

    PubMed

    Folger, Alena; Kalb, Julian; Schmidt-Mende, Lukas; Scheu, Christina

    2017-09-23

    Hydrothermally grown rutile TiO₂ nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that allows control of the distribution of these defects inside the nanowire, and thus gives direct access to tuning of the properties of rutile TiO₂ nanowires. A detailed transmission electron microscopy study is used to analyze the structural changes inside the nanowires which are correlated to the measured optical and electrical properties. The highly defective as-grown nanowire arrays have a white appearance and show typical semiconducting properties with n-type conductivity, which is related to the high density of oxygen vacancies. Heat treatment in air atmosphere leads to a vacancy condensation and results in nanowires which possess insulating properties, whereas heat treatment in N₂ atmosphere leads to nanowire arrays that appear black and show almost metal-like conductivity. We link this high conductivity to a TiO2-x shell which forms during the annealing process due to the slightly reducing N₂ environment.

  11. Compact Directional Microwave Antenna for Localized Heating

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W.; Lin, Gregory Y.; Chu, Andrew W.; Dobbins, Justin A.; Arndt, G. Dickey; Ngo, Phong

    2008-01-01

    A directional, catheter-sized cylindrical antenna has been developed for localized delivery of microwave radiation for heating (and thus killing) diseased tissue without excessively heating nearby healthy tissue. By "localized" is meant that the antenna radiates much more in a selected azimuthal direction than in the opposite radial direction, so that it heats tissue much more on one side than it does on the opposite side. This antenna can be inserted using either a catheter or a syringe. A 2.4-mm prototype was tested, although smaller antennas are possible. Prior compact, cylindrical antennas designed for therapeutic localized hyperthermia do not exhibit such directionality; that is, they radiate in approximately axisymmetric patterns. Prior directional antennas designed for the same purpose have been, variously, (1) too large to fit within catheters or (2) too large, after deployment from catheters, to fit within the confines of most human organs. In contrast, the present antenna offers a high degree of directionality and is compact enough to be useable as a catheter in some applications.

  12. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    NASA Astrophysics Data System (ADS)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2017-04-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  13. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    NASA Astrophysics Data System (ADS)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2016-12-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  14. Direct formation of single crystal VO 2(R) nanorods by one-step hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Ji, Shidong; Zhao, Yangang; Zhang, Feng; Jin, Ping

    2010-01-01

    Pure phase VO 2(R) nanorods were directly synthesized via the reduction of V 2O 5 by oxalic acid during one-step hydrothermal treatment. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, FT-IR and UV-vis spectroscopy. By adding a proper amount of H 2SO 4 as morphology control agent, monodispersed single crystal VO 2(R) nanorods were obtained from the hydrothermal solution for the first time at relatively lower temperature (260 °C) and even shorter time (4 h). The prepared nanorods showed very excellent thermochromic property with narrower hysteresis and lower phase transformation temperature compared with bulk materials.

  15. Living with the Heat. Submarine Ring of Fire--Grades 5-6. Hydrothermal Vent Ecology.

    ERIC Educational Resources Information Center

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    This activity is designed to teach about hydrothermal vent ecology. Students are expected to describe how hydrothermal vents are formed and characterize the physical conditions at these sites, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in hydrothermal vent…

  16. Evaluation of microbial community in hydrothermal field by direct DNA sequencing

    NASA Astrophysics Data System (ADS)

    Kawarabayasi, Y.; Maruyama, A.

    2002-12-01

    Many extremophiles have been discovered from terrestrial and marine hydrothermal fields. Some thermophiles can grow beyond 90°C in culture, while direct microscopic analysis occasionally indicates that microbes may survive in much hotter hydrothermal fluids. However, it is very difficult to isolate and cultivate such microbes from the environments, i.e., over 99% of total microbes remains undiscovered. Based on experiences of entire microbial genome analysis (Y.K.) and microbial community analysis (A.M.), we started to find out unique microbes/genes in hydrothermal fields through direct sequencing of environmental DNA fragments. At first, shotgun plasmid libraries were directly constructed with the DNA molecules prepared from mixed microbes collected by an in situ filtration system from low-temperature fluids at RM24 in the Southern East Pacific Rise (S-EPR). A gene amplification (PCR) technique was not used for preventing mutation in the process. The nucleotide sequences of 285 clones indicated that no sequence had identical data in public databases. Among 27 clones determined entire sequences, no ORF was identified on 14 clones like intron in Eukaryote. On four clones, tetra-nucleotide-long multiple tandem repetitive sequences were identified. This type of sequence was identified in some familiar disease in human. The result indicates that living/dead materials with eukaryotic features may exist in this low temperature field. Secondly, shotgun plasmid libraries were constructed from the environmental DNA prepared from Beppu hot springs. In randomly-selected 143 clones used for sequencing, no known sequence was identified. Unlike the clones in S-EPR library, clear ORFs were identified on all nine clones determined the entire sequence. It was found that one clone, H4052, contained the complete Aspartyl-tRNA synthetase. Phylogenetic analysis using amino acid sequences of this gene indicated that this gene was separated from other Euryarchaea before the

  17. Does Hydrothermal Circulation Matter?

    NASA Astrophysics Data System (ADS)

    Stein, C. A.; Stein, S.; von Herzen, R. P.; Fisher, A. T.

    2006-05-01

    Determining Earth's energy budget and the sources and mechanisms for heat transfer within it depends largely on assumptions of the heat loss from the formation and cooling of oceanic lithosphere, which covers about 60% of Earth's surface. Recently Hofmeister and Criss (2005) have suggested that the total global heat flow is about 30 TW, about 25% less than previously estimated by Pollack et al. (1993). The main difference between the two estimates is whether the effects of heat transfer by hydrothermal circulation are included. Thermal models describe the evolution of the lithosphere by the conductive cooling of hot material as it moves away from spreading centers. The frequently used half-space (boundary layer) and "plate" models generally successfully represent heat flow, depth, and geoid values with age, and depth-dependent properties such as flexural thickness, maximum depth of intraplate earthquakes, and lithospheric thickness. However, such models overpredict the measured heat flow from ridge crest to about 65 Myr crust. This difference is generally assumed to reflect water flow in the crust transporting heat, as shown by the spectacular hot springs at midocean ridges. If so, the observed heat flow is lower than the model's predictions, which assume that all heat is transferred by conduction. Because hydrothermal heat transport is hard to quantify, heat flow is about 50% larger than directly measured. This estimate is consistent with observations of hydrothermal circulation which indicate that the discrepancy is largely a result of the water fluxing along the oceanic basement and upwelling at isolated basement highs and outcrops. Detailed studies at such areas often show high heat flow near these outcrops and low heat flow in the surrounding areas. Hence isolated measurements are biased towards lower values and underpredict the total heat flow.

  18. Direct solar heating for Space Station application

    NASA Technical Reports Server (NTRS)

    Simon, W. E.

    1985-01-01

    Early investigations have shown that a large percentage of the power generated on the Space Station will be needed in the form of high-temperature thermal energy. The most efficient method of satisfying this requirement is through direct utilization of available solar energy. A system concept for the direct use of solar energy on the Space Station, including its benefits to customers, technologists, and designers of the station, is described. After a brief discussion of energy requirements and some possible applications, results of selective tradeoff studies are discussed, showing area reduction benefits and some possible configurations for the practical use of direct solar heating. Following this is a description of system elements and required technologies. Finally, an assessment of available contributive technologies is presented, and a Space Shuttle Orbiter flight experiment is proposed.

  19. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

    1987-02-02

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  20. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, David; Wilde, Stephen B.

    1991-01-01

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic fields which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  1. Use of radiogenic heat for demarcation of hydrothermal alteration zones in the Pernambuco-Brazil

    NASA Astrophysics Data System (ADS)

    Cunha, Leandro O.; Dutra, Alanna C.; Costa, Alexandre B.

    2017-10-01

    In this paper, we identify hydrothermal alteration zones that are located at the eastern extreme of Borborema Province, Pernambuco State, using radiogenic heat, in combination with magnetic and radioelement data collected both from the air and on the ground. The use of these methods enabled the mapping of geological lineaments based on total magnetic intensity maps, radioelement concentration maps, ternary maps and the F factor, as well as physical properties provided by ground data (thermal conductivity, density, and magnetic susceptibility). The data integration was based on low values of radiogenic heat and high K concentrations, as well as high F factors, amplitudes of the analytic signal, and K/eTh and eU/eTh values. These characteristics occur within the Pernambuco lineament and within other features to the southeast, a short distance south of the lineaments, which are made up of units including a migmatitic gneiss complex, as well as the Modern, Itaporanga and Sierra Passira Intrusive Suites. In these areas, elongated sources that are consistent with lineaments were identified. These sources were assigned depths of up to 3 km and are 5-10 km long, with the most significant extending SE-NW. These areas are favorable for the mineralization of iron, titanium and nickel. As the results are satisfactory, such areas can be studied in detail in the future.

  2. Direct hydrothermal synthesis of hierarchically porous siliceous zeolite by using alkoxysilylated nonionic surfactant.

    PubMed

    Mukti, Rino R; Hirahara, Hirotomo; Sugawara, Ayae; Shimojima, Atsushi; Okubo, Tatsuya

    2010-02-16

    A hierarchically porous siliceous MFI zeolite (silicalite-1) with narrow mesoporosity has been hydrothermally synthesized by using trialkoxysilylated alkyl poly(oxyethylene ether) as mesopore-directing agent. A mesostructured silica-surfactant composite was formed at the early stage of the reaction, and zeolite crystallization proceeded during subsequent hydrothermal treatment. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations of the crystallized products showed that micro- and mesopores were hierarchically assembled in unique particle morphology with rugged surfaces. Solid-state (29)Si and (13)C NMR revealed that the covalent bonds between the zeolite framework and mesopore-directing agent were present in the products before calcination. The use of nonsilylated alkyl poly(oxyethylene ether) or a silylated alkytrimethyl-ammonium-type cationic surfactant for the synthesis of silicalite-1 resulted in a mixture of mesoporous silica and zeolite as the final product, which suggests that the covalent interaction and nonelectrostatic charge matching interaction favor the formation of hierarchically mesoporous siliceous zeolite. This alkoxysilylated nonionic surfactant can also be extended to synthesize aluminosilicate MFI zeolite (ZSM-5).

  3. Fast wave direct electron heating in TFTR

    SciTech Connect

    Murakami, M.; Jaeger, E.F.; Rimini, F.G.; Rasmussen, D.A.; Stevens, J.E.; Wilson, J.R.; Batchelor, D.B.; Bell, M.; Budny, R.; Fredrickson, E.; Goldfinger, R.C.; Hammett, G.; Hoffman, D.J.; Hosea, J.C.; Janos, A.; Majeski, R.; Mansfield, D.; Phillips, C.K.; Rogers, J.H.; Schilling, G.; Taylor, G.; Zarnstorff, M.C.

    1993-05-01

    Direct electron heating experiments were carried out in two regimes: B{sub T} = 4.6 T with D{sup +} supershots; and B{sub T} = 2.3 T with {sup 3}He majority. The electron power deposition profiles measured with modulation of RF power are found to be strongly peaked in the core with the total volume-integrated power of up to 80% of the modulated power. The magnitude and profile shape agree well with those predicted by a full-wave code.

  4. Ongoing hydrothermal heat loss from the 1912 ash-flow sheet, Valley of Ten Thousand Smokes, Alaska

    USGS Publications Warehouse

    Hogeweg, N.; Keith, T.E.C.; Colvard, E.M.; Ingebritsen, S.E.

    2005-01-01

    The June 1912 eruption of Novarupta filled nearby glacial valleys on the Alaska Peninsula with ash-flow tuff (ignimbrite), and post-eruption observations of thousands of steaming fumaroles led to the name 'Valley of Ten Thousand Smokes' (VTTS). By the late 1980s most fumarolic activity had ceased, but the discovery of thermal springs in mid-valley in 1987 suggested continued cooling of the ash-flow sheet. Data collected at the mid-valley springs between 1987 and 2001 show a statistically significant correlation between maximum observed chloride (Cl) concentration and temperature. These data also show a statistically significant decline in the maximum Cl concentration. The observed variation in stream chemistry across the sheet strongly implies that most solutes, including Cl, originate within the area of the VTTS occupied by the 1912 deposits. Numerous measurements of Cl flux in the Ukak River just below the ash-flow sheet suggest an ongoing heat loss of ???250 MW. This represents one of the largest hydrothermal heat discharges in North America. Other hydrothermal discharges of comparable magnitude are related to heat obtained from silicic magma bodies at depth, and are quasi-steady on a multidecadal time scale. However, the VTTS hydrothermal flux is not obviously related to a magma body and is clearly declining. Available data provide reasonable boundary and initial conditions for simple transient modeling. Both an analytical, conduction-only model and a numerical model predict large rates of heat loss from the sheet 90 years after deposition.

  5. Sensitivity of hydrothermal wave instability of Marangoni convection to the interfacial heat transfer in long liquid bridges of high Prandtl number fluids

    NASA Astrophysics Data System (ADS)

    Yano, T.; Nishino, K.; Ueno, I.; Matsumoto, S.; Kamotani, Y.

    2017-04-01

    This paper reports the sensitivity of hydrothermal wave (HTW) instability of Marangoni convection to the interfacial heat transfer in liquid bridges (LBs) of high Prandtl number fluids (Pr = 67, 112, and 207) formed under the microgravity environment on the International Space Station. The data for instability are collected for a wide range of AR and for TC = 15 and 20 °C, where AR is the aspect ratio (=height/diameter) of the LB and TC is the cooled disk temperature. A significant decrease in critical oscillation frequency as well as an appreciable decrease in the critical Marangoni number is observed for AR > 1.25. This drastic change of instability mechanisms is associated with the reversal of axial traveling direction of HTWs and roll-structures as reported previously. It is found that this reversal is closely related to the interfacial heat transfer, which is evaluated numerically through accounting for both convective and radiative components. A heat transfer ratio, QI/QH, is introduced as a dimensionless parameter for interfacial heat transfer, where QI and QH are the heat transfer rates at the LB-gas and LB-heated disk interfaces, respectively. It is found that HTWs travel in the same direction as the surface flow for QI/QH > 0 (heat-loss condition) while in the opposite direction for QI/QH < 0 (heat-gain condition) in the present microgravity experiment. It is shown that the heat-transfer condition alters slightly but appreciably the basic temperature and flow field, the alteration that is not accounted for in the previous linear stability analyses for an infinite LB.

  6. Estimating the Heat and Mass Flux at the ASHES Hydrothermal Vent Field with the Sentry Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Kinsey, J. C.; Crone, T. J.; Mittelstaedt, E. L.; Medagoda, L.; Fourie, D.; Nakamura, K.

    2014-12-01

    Hydrothermal venting influences ocean chemistry, the thermal and chemical structure of the oceanic crust, the style of accretion at mid-ocean ridges, and the evolution of unique and diverse chemosynthetic ecosystems. Surprisingly, only a few studies have attempted to constrain the volume and heat flux of entire hydrothermal vent fields given that axially-hosted hydrothermal systems are estimated to be responsible for ~20-25% of the total heat flux out of the Earth's interior, as well as potentially playing a large role in global and local biogeochemical cycles. However, same-site estimates can vary greatly, such as at the Lucky Strike Field where estimates range from 100 MW to 3800 MW. We report a July 2014 field program with the Sentry AUV that obtains the water velocity and heat measurements necessary to estimate the total heat and mass flux emanating from the ASHES hydrothermal vent field. We equipped Sentry with a Nortek acoustic Doppler velocimeter (ADV) with an inertial measurement unit attached, two acoustic Doppler current profilers (ADCPs), and two SBE3 temperature probes, to measure the temperature and water velocity. This sensing suite provided more accurate measurements than previous AUV based studies. A control volume approach was employed in which Sentry was pre-programmed to survey a 150m by 150m box centered over the vent field flying a "mowing the lawn" pattern at 5m trackline spacing followed by a survey of the perimeter. During a 40 hour survey, the pattern was repeated 9 times allowing us to obtain observations over multiple tidal cycles. Concurrent lowered ADCP (LADCP) measurements were also obtained. Water velocity data obtained with Sentry was corrected for platform motion and then combined with the temperature measurements to estimate heat flux. Analysis of this data is on-going, however these experiments permit us to quantify the heat and mass exiting the control volume, and potentially provide the most accurate and highest resolution heat

  7. The Response of Two-Phase Hydrothermal Systems to Changing Magmatic Heat Input at Mid Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Choi, J.; Lowell, R. P.

    2012-12-01

    Hydrothermal processes at oceanic spreading centers are largely influenced by changing magmatic heat input. We use the two-phase NaCl-H2O FISHES code to investigate the evolution of surface temperature and salinity as a function of time-varying heat flux at the base of the hydrothermal system. We consider a two-dimensional rectangular box that is 1.5 km deep and 2 km long with homogeneous permeability of 10-13 m2. Temperature and pressure at top boundary correspond to seafloor conditions of 10°C, 25MPa respectively. Upstream conditions are applied at the top so temperature and salinity of fluids exiting the surface is set equal to that at one cell below the top boundary. Impermeable, insulated conditions are imposed on the left and right hand boundaries. To simulate time-varying heat flux from a sub-axial magma chamber of 500 m long half-width, we considered a variety of basal boundary conditions: (1) a sinusoidal heat flux with a period of 6 years and an amplitude ranging between 100 and 50 W/m2; (2) step function, random function, and exponential function between 200 and 15 W/m2; and (3) an analytical function of temporally decaying heat flux resulting from a simulated cooling, crystallizing magmatic sill. As a result of the investigation we find: (1) changes in bottom temperature and salinity closely follow the temporal variations in magmatic heat inputs; (2) the surface temperature response is severely damped and high frequency variations in heat flow are not detected; (3) in regions where phase separation occurs, surface salinity variations may be recorded in response to changing conditions at depth, but these are smaller in amplitude than the changes at depth. These simulations represent an important forward toward understanding time-dependent behavior of coupled magma-hydrothermal processes at oceanic spreading centers.

  8. Preliminary Hydrothermal Heat Flow Measurements at the 9-10º N East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Ramondenc, P.; Germanovich, L. N.; von Damm, K. L.; Lowell, R. P.

    2004-12-01

    The March 2004 expedition at 9-10° N East Pacific Rise, part of the RIDGE 2000 program, allowed amongst other things to pursue the monitoring and sampling of a number of vents after the volcanic eruptions that occurred in 1991/2. Earlier observations have shown that the chemical composition and the temperature have not yet stabilized at many of the vents. This expedition also gave us the opportunity to test an experimental device to estimate the velocity of diffuse flow and heat transport at a couple of vents. These experiments represent the first such attempts to measure these parameters for the 9-10° N hydrothermal system. The idea was to focus the fluid flow through an opening and videotape the motion of particles composing the fluid. Though crude, this method should provide an upper estimate of the fluid velocity and the mass flux of the underlying upflow zone. This operation was also done at the same vents just with a scale maintained close to the flow. This approach yields a lower estimate of the velocity. These tests were run on three dives achieved with the deep submergence vehicle Alvin (dives # 3987, 3990 and 3992, respectively at M-vent, TICA-vent, Bio9, Bio9' and Bio9''). Typical results obtained for the total heat flux ranged from Q = 10^5 W to Q = 10^7 W. This experience has provided insight into a new design based on the temperature measurement at different regions in the stream. We hope to develop this new device in the coming months and deploy it in 2005.

  9. Geothermal Direct Heat Applications Program Summary

    SciTech Connect

    1981-09-25

    Because of the undefined risk in the development and use of geothermal energy as a thermal energy source, the Department of Energy Division of Geothermal Energy solicited competitive proposals for field experiments in the direct use of geothermal energy. Twenty-two proposals were selected for cost-shared funding with one additional project co-funded by the State of New Mexico. As expected, the critical parameter was developing a viable resource. So far, of the twenty resources drilled, fourteen have proved to be useful resources. These are: Boise, Idaho; Elko heating Company in Nevada; Pagosa Springs, Colorado; Philip School, Philip, South Dakota; St. Mary's Hospital, Pierre, South Dakota; Utah Roses near Salt Lake City; Utah State Prison, Utah; Warm Springs State Hospital, Montana; T-H-S Hospital, Marlin, Texas; Aquafarms International in the Cochella Valley, California; Klamath County YMCA and Klamath Falls in Oregon; Susanville, California and Monroe, utah. Monroe's 164 F and 600 gpm peak flow was inadequate for the planned project, but is expected to be used in a private development. Three wells encountered a resource insufficient for an economical project. These were Madison County at Rexburg, Idaho; Ore-Ida Foods at Ontario, Oregon and Holly Sugar at Brawley, California. Three projects have yet to confirm their resource. The Navarro College well in Corsicana, Texas is being tested; the Reno, Moana, Nevada well is being drilled and the El Centro, California well is scheduled to be drilled in January 1982. The agribusiness project at Kelly Hot Springs was terminated because a significant archeological find was encountered at the proposed site. The Diamond Ring Ranch in South Dakota, and the additional project, Carrie Tingley Hospital in Truth or Consequences, New Mexico both used existing wells. The projects that encountered viable resources have proceeded to design, construct, and in the most advanced projects, to operate geothermal systems for district

  10. Direct-contact closed-loop heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1984-01-01

    A high temperature heat exchanger with a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

  11. Integrated thermal infrared imaging and structure-from-motion photogrammetry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA, USA

    NASA Astrophysics Data System (ADS)

    Lewis, A.; Hilley, G. E.; Lewicki, J. L.

    2015-09-01

    This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the structure-from-motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 °C and 450 W m- 2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

  12. Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA USA

    USGS Publications Warehouse

    Lewis, Aaron; George Hilley,; Lewicki, Jennifer L.

    2015-01-01

    This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

  13. Model of the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1982-08-10

    Earlier studies at Cerro Prieto by UCR have led to the development of a qualitative model for field flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modelling of heat and mass transfer in the system in this undisturbed state. A two-dimensional model assumes that the heat sources were a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compiling various information on the physical properties of the reservoir, the enthalpy contained in two 1cm thick section across the reservoir orthogonal to each other was calculated. Next various shapes, sizes and depths for the intrusion as initial conditions and boundary conditions for the calculation of heat transfer were considered. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4km wide emplaced at a depth of 5km some 30,000 to 50,000 years ago, providing heat to the geothermal system. Numerical modelling is still in progress. Although none of the models so far computed may be a perfect match for the thermal history of the reservoir, they all indicate that the intrusive heat source is young, close and large.

  14. Microscopic Investigation of Electrochemical Gradients and Directed Transport in a Simulated Alkaline Hydrothermal Vent

    NASA Astrophysics Data System (ADS)

    Möller, F. M.; Braun, D.; Kieß, M.; Keil, L.

    2016-12-01

    A prerequisite for the emergence of life on early earth are strong and sustained far-from-equilibrium conditions. Alkaline hydrothermal vent systems provide rich (geo-)chemical and physical gradients with striking resemblance to modern biology. Serpentinization reactions within the earth's crust led to strong gradients of pH, temperature, ionic composition and redox potential at the interface between the Hadean ocean and the hydrothermal effluent. Precipitation reactions further provided natural barriers of catalytic Fe(Ni)S minerals. The strong redox potential between the CO2-rich Hadean ocean and the H2-bearing vent effluent across the catalytic precipitate has been hypothesized to trigger the first carbon-fixation reactions. However, only steep pH gradients make this reaction thermodynamically favorable. Here, we use a microfluidic replicate of a vent to access the steepness and stability of the pH gradient experimentally, and to investigate on the effect of the inorganic barrier. Using ratiometric fluorescence microscopy we find that the steepness and stability of the pH gradient is strongly enhanced by the ongoing precipitation. The pH gradient only relaxes when the flow of resources ceases. Furthermore, the ionic gradients are found to trigger the directed transport of colloids by diffusiophoresis, leading to interesting effects such as exclusion zone formation at the barrier and strong accumulation of colloids. The coupling of physical transport phenomena has been shown to invoke intricate feedback situations. In a series of experimental studies, we succeeded in implementing the accumulation, replication and selection of molecules by a thermal gradient across a micropore. These effects are essential requirements for the onset of early Darwinian evolution. The coupling of the effects observed in thermal and electrochemical gradients within our microscale laboratory experiments can yield insight into evolutionary scenarios for the earliest energy and carbon

  15. Model for the heat source of the Cerro Prieto magma-hydrothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.; Cox, B.

    1981-01-01

    Earlier studies at Cerro Prieto led to the development of a qualitative model for fluid flow in the geothermal system before it was drilled and perturbed by production. Current efforts are directed towards numerical modeling of heat and mass transfer in the system in this undisturbed state. This one-dimensional model assumes that the heat source was a single basalt/gabbro intrusion which provided heat to the system as it cooled. After compilation of various information of the physical properties of the reservoir, the enthalpy contained in two 1 cm thick sections across the reservoir orthogonal to each other was calculated. Various shapes, sizes and depths for the intrusion were considered as initial conditions and boundary conditions for the calculations of heat transfer. A family of numerical models which so far gives the best matches to the conditions observed in the field today have in common a funnel-shaped intrusion with a top 4 km wide emplaced at a depth of 5 km some 30,000 to 50,000 years ago, providing heat to the geothermal system.

  16. Heat transfer through the sediments of the mounds hydrothermal area, Galapagos Spreading Center at 86 /sup 0/W

    SciTech Connect

    Becker, K.; Von Herzen, R.P.

    1983-02-10

    Heat transfer processes at the mounds area of the Galapagos Spreading Center at 86 /sup 0/W are revealed by temperatures measured at roughly-equal10-m intervals in the 30 +- 10 m sediment at each of 12 holes at DSDP Leg 70 Sites 506--509 and by temperatures of up to five thermistors on eleven 8--12 m long piston cores. The 325 needle-probe values show a significant linear increase of thermal conductivity with depth in each core. About half of the temperature-thermal resistance profiles are nonlinear and are fit to a steady state, vertical pore water advection model. Results indicate high and variable total heat flow and localized hydrothermal discharge at roughly-equal10/sup -8/ m/s, associated with individual mounds. Recharge is indicated at similar rates in the low heat flow belt roughly-equal5 km south of the mounds and is suggested at slower rates in the intermediate heat flow (0.17--0.42 W/m/sup 2/) belt surrounding the mounds heat flow high. Possible slow entrained recharge within roughly-equal100 m of discharging mounds is suggested. Also suggested is strong local discharge along the major fault bounding the mounds crustal block to the north. About 95 km north of the spreading axis, at DSDP Site 510, temperatures in the 114-m sediment cover on 2.7-m.y. crust are linear, consistent with the suggestion that the hydraulic resistance of this layer is sufficient to seal off free hydrothermal exchange between basement and bottom water. The combination of heat flow data and the physical properties data of Karato and Becker (this issue) suggests that roughly-equal50 m of sediment may be a threshold thickness for sealing of hydrothermal circulation within basement, where the topography is smooth. We suggest that the formation of mounds may be associated with the forced localization of hydrothermal discharge through the sediment, as its thickness approaches this threshold value.

  17. Direct contact heat recovery from molten salt

    NASA Astrophysics Data System (ADS)

    Technological deficiencies associated with efficient and economical retrieval of heat energy from molten salt systems are addressed. The large latent heat of fusion stored in molten salt hydrates and other candidate phase change materials (PCM) is removed by internal boiling of a volatile heat transfer fluid (HTF). This procedure eliminates the conventional use of submerged heat exchangers which are costly and, in crystallizing salts, ineffective. The thermochemical conditions and material properties that are critical for application of this concept in environments that yield significant energy savings are investigated and defined.

  18. Geothermal direct-heat utilization assistance

    NASA Astrophysics Data System (ADS)

    1993-11-01

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on compilation of data on low temperature resources and evaluation of groundwater versus ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  19. Hydrothermal-flow regime and magmatic heat source of the Cerro Prieto geothermal system, Baja California, Mexico

    SciTech Connect

    Elders, W.A.; Bird, D.K.; Williams, A.E.; Schiffman, P.

    1982-01-01

    This detailed three-dimensional model of the natural flow regime of the Cerro Prieto geothermal field, before steam production began, is based on patterns of hydrothermal mineral zones and light stable isotopic ratios observed in rock samples from more than fifty deep wells, together with temperature gradients, wireline logs and other data. At the level so far penetrated by drilling, this hydrothermal system was heated by a thermal plume of water close to boiling, inclined at 45/sup 0/, rising from the northeast and discharging to the west. To the east a zone of cold water recharge overlies the inclined thermal plume. Fission track annealing studies shows that the reservoir reached 170/sup 0/C only 10/sup 4/ years ago. Oxygen isotope exchange data indicate that a 12 km/sup 3/ volume of rock subsequently reacted with three times its volume of water hotter than 200/sup 0/C. Averaged over the duration of the heating event this would require a flow velocity of about 6 m/year through the pores of a typical cross section of the reservoir having an average porosity of 10%. Although this is an extensional tectonic environment of leaky transform faulting in which repeated intrusions of basalt magma are likely, for simplicity of computation possible heat sources were modelled as simple two dimensional basalt intrusions of various sizes, shapes and locations. We have calculated a series of two-dimensional convective heat transfer models, with different heat sources and permeability distributions. The models which produce the best fit for the temperature distributions observed in the field today have in common a heat source which is a funnel-shaped basalt intrusion, 4 km wide at the top, emplaced at a depth of 5 km to 6 km about 40,000 to 50,000 years ago.

  20. Heat Pumps With Direct Expansion Solar Collectors

    NASA Astrophysics Data System (ADS)

    Ito, Sadasuke

    In this paper, the studies of heat pump systems using solar collectors as the evaporators, which have been done so far by reserchers, are reviwed. Usually, a solar collector without any cover is preferable to one with ac over because of the necessity of absorbing heat from the ambient air when the intensity of the solar energy on the collector is not enough. The performance of the collector depends on its area and the intensity of the convective heat transfer on the surface. Fins are fixed on the backside of the collector-surface or on the tube in which the refrigerant flows in order to increase the convective heat transfer. For the purpose of using a heat pump efficiently throughout year, a compressor with variable capacity is applied. The solar assisted heat pump can be used for air conditioning at night during the summer. Only a few groups of people have studied cooling by using solar assisted heat pump systems. In Japan, a kind of system for hot water supply has been produced commercially in a company and a kind of system for air conditioning has been installed in buildings commercially by another company.

  1. Geothermal direct heat use: Market potential/penetration analysis for Federal Region 9

    NASA Technical Reports Server (NTRS)

    Powell, W. (Editor); Tang, K. (Editor)

    1980-01-01

    A preliminary study was made of the potential for geothermal direct heat use in Arizona, California, Hawaii, and Nevada (Federal Region 9). An analysis was made of each state to: (1) define the resource, based on the latest available data; (2) assess the potential market growth for geothermal energy; and (3) estimate the market penetration, projected to 2020. Findings of the study include the following: (1) Potentially economical hydrothermal resources exist in all four states of the Region: however, the resource data base is largely incomplete, particularly for low to moderate temperature resources. (2) In terms of beneficial heat, the total hydrothermal resource identified so far for the four states is on the order of 43 Quads, including an estimated 34 Quads of high temperature resources which are suitable for direct as well as electrical applications. (3) In California, Hawaii, and Nevada, the industrial market sector has somewhat greater potential for penetration than the residential/commercial sector. In Arizona, however, the situation is reversed, due to the collocation of two major metropolitan areas (Phoenix and Tucson) with potential geothermal resources.

  2. Hydrothermal Heat Transport within an Abruptly Formed Permeable Slot: An Application to Heat Flow Peaks Observed at the Japan Trench Offshore of Sanriku

    NASA Astrophysics Data System (ADS)

    Kawada, Y.; Yamano, M.

    2015-12-01

    Anomalous heat flow has been observed within 150 km seaward of the trench axis at the Japan Trench offshore of Sanriku, northeast Japan [Yamano et al., 2008, 2014]. The average heat flow is ~70 mW/m2 (50 mW/m2 is expected for the plate age), and small-scale (2 to 3 km) variations, whose peak value is >100 mW/m2, are embedded. In the area of high heat flow, a high Vp/Vs layer in the oceanic crust has been detected [Fujie et al., 2013]. The layer thickness is increased toward the trench axis. Fujie et al.[2013] interpreted this layer as a result of fracturing due to bending of the subducting plate. This layer may work as an aquifer in which heat is transported by fluid circulation. In a previous study [Kawada et al., 2014], we constructed a model for aquifer thickening in order to explain the observed anomalous heat flow: a 500-m-thick aquifer 150 km seaward of the trench axis is gradually thickened to 3000 m toward the trench axis. We found that hydrothermal circulation within the thickening aquifer mines heat beneath its underlying part, and heat flow is elevated accordingly. Although the model can explain the observed high heat flow in an average sense, the origin of the small-scale heat flow variations remains to be solved. This study expands the previous model by incorporating abrupt thickening of the aquifer to account for the small-scale heat flow. Typically, we consider a situation in which a permeable slot of 2000 m wide and 3000 m deep suddenly appears. This model results in a high heat flow peak of 100 mW/m2 above the permeable slot, which persists over hundreds of thousand years. Heat outside the slot is transported horizontally toward the slot by thermal conduction and then is transported vertically due to hydrothermal circulation within the slot. Because the volume of the permeable slot is smaller than its surrounding region, high heat flow above the slot lasts for a long time.

  3. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions

    USGS Publications Warehouse

    Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.

    2009-01-01

    Hydrothermal explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments from source craters that range from a few meters up to more than 2 km in diameter; associated breccia can be emplaced as much as 3 to 4 km from the largest craters. Hydrothermal explosions occur where shallow interconnected reservoirs of steam- and liquid-saturated fluids with temperatures at or near the boiling curve underlie thermal fields. Sudden reduction in confi ning pressure causes fluids to fl ash to steam, resulting in signifi cant expansion, rock fragmentation, and debris ejection. In Yellowstone, hydrothermal explosions are a potentially signifi cant hazard for visitors and facilities and can damage or even destroy thermal features. The breccia deposits and associated craters formed from hydrothermal explosions are mapped as mostly Holocene (the Mary Bay deposit is older) units throughout Yellowstone National Park (YNP) and are spatially related to within the 0.64-Ma Yellowstone caldera and along the active Norris-Mammoth tectonic corridor. In Yellowstone, at least 20 large (>100 m in diameter) hydrothermal explosion craters have been identifi ed; the scale of the individual associated events dwarfs similar features in geothermal areas elsewhere in the world. Large hydrothermal explosions in Yellowstone have occurred over the past 16 ka averaging ??1 every 700 yr; similar events are likely in the future. Our studies of large hydrothermal explosion events indicate: (1) none are directly associated with eruptive volcanic or shallow intrusive events; (2) several historical explosions have been triggered by seismic events; (3) lithic clasts and comingled matrix material that form hydrothermal explosion deposits are extensively altered, indicating that explosions occur in areas subjected to intense hydrothermal processes; (4) many lithic clasts contained in explosion breccia deposits preserve evidence of repeated fracturing

  4. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    USGS Publications Warehouse

    Beeler, Nicholas M.; Hickman, Stephen H.

    2015-01-01

    Earthquake recurrence requires interseismic fault restrengthening which results from solid state deformation in room-temperature friction and indentation experiments. In contrast exhumed fault zones show solution-transport processes such as pressure solution and contact overgrowths influence fault zone properties . In the absence of fluid flow, overgrowths are driven by gradients in surface curvature where material is dissolved, diffuses, and precipitates at the contact without convergence normal to the contact. To determine the rate of overgrowth for quartz, we conducted single contact experiments in an externally heated pressure vessel. Convergence was continuously monitored using reflected-light interferometry through a long-working-distance microscope. Contact normal force was constant with an initial effective normal stress of 1.7 MPa, temperature was between 350 and 530{degree sign}C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425{degree sign}C and one bi-material (sapphire) at 425{degree sign}C and 150 MPa water pressure. No contact growth or convergence was observed in the controls. For wet single-phase contacts, growth was initially rapid and then decreased with time. No convergence was observed. Fluid inclusions indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth. The apparent activation energy is ~125 kJ/mol. Extrapolation predicts rates of contact area increase orders of magnitude faster than in dry, room-temperature and hydrothermal friction experiments, suggesting that natural strength recovery near the base of the seismogenic zone could be dominated by contact overgrowth.

  5. Results from the DCH-1 (Direct Containment Heating) experiment. [Pressurized melt ejection and direct containment heating

    SciTech Connect

    Tarbell, W.W.; Brockmann, J.E.; Pilch, M.; Ross, J.E.; Oliver, M.S.; Lucero, D.A.; Kerley, T.E.; Arellano, F.E.; Gomez, R.D.

    1987-05-01

    The DCH-1 (Direct Containment Heating) test was the first experiment performed in the Surtsey Direct Heating Test Facility. The test involved 20 kg of molten core debris simulant ejected into a 1:10 scale model of the Zion reactor cavity. The melt was produced by a metallothermic reaction of iron oxide and aluminum powders to yield molten iron and alumina. The cavity model was placed so that the emerging debris propagated directly upwards along the vertical centerline of the chamber. Results from the experiment showed that the molten material was ejected from the caviity as a cloud of particles and aerosol. The dispersed debris caused a rapid pressurization of the 103-m/sup 3/ chamber atmosphere. Peak pressure from the six transducers ranged from 0.09 to 0.13 MPa (13.4 to 19.4 psig) above the initial value in the chamber. Posttest debris collection yielded 11.6 kg of material outside the cavity, of which approximately 1.6 kg was attributed to the uptake of oxygen by the iron particles. Mechanical sieving of the recovered debris showed a lognormal size distribution with a mass mean size of 0.55 mm. Aerosol measurements indicated a subsantial portion (2 to 16%) of the ejected mass was in the size range less than 10 m aerodynamic equivalent diameter.

  6. Direct-contact closed-loop heat exchanger

    DOEpatents

    Berry, G.F.; Minkov, V.; Petrick, M.

    1981-11-02

    A high temperature heat exchanger is disclosed which has a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

  7. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1982-03-01

    Direct contact heat exchange offers the potential for increased efficiency and lower heat transfer costs in a variety of thermal energy storage systems. SERI models of direct contact heat transfer based on literature information identified dispersed phase drop size, the mechanism of heat transfer within the drop, and dispersed phase holdup as the parameters controlling direct contact system performance. Tests were defined and equipment constructed to provide independent determination of drop size, heat transfer mechanism, and hold up. Further experiments are needed to conclusively determine whether the salt in a salt hydrate melt acts to block internal circulation. The potential of low temperature oil/salt hydrate latent heat storage systems is being evaluated in the laboratory.

  8. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1980-11-01

    Direct contact heat exchange offers the potential for increased efficiency and lower heat transfer costs in a variety of thermal energy storage systems. Models of direct contact heat transfer based on literature information identified dispersed phase drop size, the mechanism of heat transfer within the drop, and dispersed phase holdup as the parameters controlling direct contact system performance. Tests were defined and equipment constructed to provide independent determination of drop size, heat transfer mechanism, and hold up. Experiments with heptane dispersed in water are described. The velocity at which drop formation changes from dropwise to jetting was overpredicted by all literature correlations. Further experiments are needed to conclusively determine whether the salt in a salt hydrate melt acts to block internal circulation. In addition, the potential of low temperature oil/salt hydrate latent heat storage systems is evaluated in the laboratory.

  9. Directional heat transport through thermal reflection meta-device

    NASA Astrophysics Data System (ADS)

    Hu, Run; Zhou, Shuling; Shu, Weicheng; Xie, Bin; Ma, Yupu; Luo, Xiaobing

    2016-12-01

    Directional heat transfer may be hard to realize due to the fact that heat transfer is diffusive. In this paper, we try to take one step forward based on the transformation thermodynamics. A special structure and meta-device is proposed to "reflect" the heat flow directionally-just like the mirror to the light beam, in which the heat flow just one-time changes the direction rather than gradually changing the directions in isotropic materials. The benefits of such thermal reflection meta-device are discussed by comparing the corresponding thermal resistance with the same structures of isotropic materials. The proposed meta-device is verified to possess the low thermal resistance and high heat transfer ability with least energy loss, and can be made by nature-existing isotropic materials with specific structures.

  10. Semiconductor junction formation by directed heat

    DOEpatents

    Campbell, Robert B.

    1988-03-24

    The process of the invention includes applying precursors 6 with N- and P-type dopants therein to a silicon web 2, with the web 2 then being baked in an oven 10 to drive off excessive solvents, and the web 2 is then heated using a pulsed high intensity light in a mechanism 12 at 1100.degree.-1150.degree. C. for about 10 seconds to simultaneously form semiconductor junctions in both faces of the web.

  11. Encapsulation of metal clusters within MFI via interzeolite transformations and direct hydrothermal syntheses and catalytic consequences of their confinement.

    PubMed

    Goel, Sarika; Zones, Stacey I; Iglesia, Enrique

    2014-10-29

    The encapsulation of metal clusters (Pt, Ru, Rh) within MFI was achieved by exchanging cationic metal precursors into a parent zeolite (BEA, FAU), reducing them with H2 to form metal clusters, and transforming these zeolites into daughter structures of higher framework density (MFI) under hydrothermal conditions. These transformations required MFI seeds or organic templates for FAU parent zeolites, but not for BEA, and occurred with the retention of encapsulated clusters. Clusters uniform in size (1.3-1.7 nm) and exposing clean and accessible surfaces formed in BEA and FAU zeolites; their size remained essentially unchanged upon transformation into MFI. Encapsulation selectivities, determined from the relative hydrogenation rates of small (toluene) and large (alkyl arenes) molecules and defined as the ratio of the surface areas of all the clusters in the sample to that of external clusters, were very high (8.1-40.9) for both parent and daughter zeolites. Encapsulation into MFI via direct hydrothermal syntheses was unsuccessful because metal precursors precipitated prematurely at the pH and temperatures required for MFI synthesis. Delayed introduction of metal precursors and F(-) (instead of OH(-)) as the mineralizing agent in hydrothermal syntheses increased encapsulation selectivities, but they remained lower than those achieved via interzeolite transformations. These interconversions provide a general and robust strategy for encapsulation of metals when precursors can be introduced via exchange into a zeolite that can be transformed into target daughter zeolites with higher framework densities, whether spontaneously or by using seeds or structure-directing agents (SDA).

  12. Combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass feedstocks

    DOEpatents

    Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.

    2017-09-12

    A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

  13. Direct heating of imploded plasma in the fast ignition

    NASA Astrophysics Data System (ADS)

    Sunahara, Atsushi; Johzaki, Tomoyuki; Nagatomo, Hideo; Mima, Kunioki; Shiraga, Hiroyuki; Azechi, Hiroshi; Mori, Yohitaga; Kitagawa, Yoneyoshi

    2016-03-01

    We propose the direct heating of an imploded plasma core by ultra-intense lasers in inertial confinement fusion, to increase the heating coupling efficiency. In this scheme, both fast-electrons and fast-ions heat the plasma core. Experiments using this direct heating scheme has been carried out at GXII and LFEX laser facility at Osaka Univeristy. To model this direct heating scheme, we developed the 1D simulation model and carried out simulations using the experimental conditions. Comparison between results of the simulation and the experimental observations validates the simulation model. We show that even in the unoptimized experimental conditions used in simulations, our calculations show that the maximum temperature, 1.6 keV, of the CD plasma.

  14. Hydrothermal organic synthesis experiments

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Ways in which heat is useful in organic synthesis experiments are described, and experiments on the hydrothermal destruction and synthesis of organic compounds are discussed. It is pointed out that, if heat can overcome kinetic barriers to the formation of metastable states from reduced or oxidized starting materials, abiotic synthesis under hydrothermal conditions is a distinct possibility. However, carefully controlled experiments which replicate the descriptive variables of natural hydrothermal systems have not yet been conducted with the aim of testing the hypothesis of hydrothermal organic systems.

  15. Direct contact droplet heat exchangers for thermal management in space

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Hertzberg, A.

    1982-01-01

    A liquid droplet heat exchanger for space applications is described which transfers heat between a gas and a liquid metal dispersed into droplets. The ability of the droplet heat exchanger to transfer heat between two media in direct contact over a wide temperature range circumvents many of the material limitations of conventional tube-type heat exchangers and does away with complicated plumbing systems and their tendency toward single point failure. Droplet heat exchangers offer large surface to volume ratios in a compact geometry, very low gas pressure drop, and high effectiveness. The application of the droplet heat exchanger in a high temperature Brayton cycle is discussed to illustrate its performance and operational characteristics.

  16. Hydrogeologic controls on saturation profiles in heat-pipe-like hydrothermal systems: numerical study

    NASA Astrophysics Data System (ADS)

    Pervin, Mollika; Ghergut, Iulia; Graf, Thomas; Peche, Aaron

    2016-04-01

    work, we explore some mechanisms and geologic controls that can lead to the formation of extensive vapor-dominated zones within a two-phase system. In particular, we investigate the effect of vertical heterogeneity of permeability (stratified reservoir, containing a permeability barrier) on the liquid water saturation profile within a modified HP model. Though in field observations liquid water has been directly encountered only within the condensation zone at reservoir top, it was speculated that large amounts of liquid water might also exist below the condensation zone. This is of great practical significance to the exploitation of vapor-dominated reservoirs, as their longevity depends on the fluid reserves in place. Within this work, we demonstrate by numerical simulations of a modified HP model that high values of liquid water saturation (>0.8) can prevail even far below the condensation zone. Such findings are useful as a baseline for future calculations regarding the economic exploitation of vapor-dominated systems, where premature productivity drop (or dry-out) is the main issue of concern. References: Eastman, G. Y:, 1968: The heat pipe. Scientific American, 218(5):38-46. Preuss, K. A., 1985: A quantitative model of vapor-dominated geothermal reservoirs as heat pipes in fractured porous rock, Transactions, Geothermal Resources. Council, 9(2), 353-361. Truesdell, A. H., and White, D.E. 1973: Production of superheated Steam from Vapor- dominated geothermal reservoirs. Geothermics, 2(3-4), 154-173

  17. Surface heat flow and CO2 emissions within the Ohaaki hydrothermal field, Taupo Volcanic Zone, New Zealand

    USGS Publications Warehouse

    Rissmann, C.; Christenson, B.; Werner, C.; Leybourne, M.; Cole, J.; Gravley, D.

    2012-01-01

    Carbon dioxide emissions and heat flow have been determined from the Ohaaki hydrothermal field, Taupo Volcanic Zone (TVZ), New Zealand following 20a of production (116MW e). Soil CO2 degassing was quantified with 2663 CO2 flux measurements using the accumulation chamber method, and 2563 soil temperatures were measured and converted to equivalent heat flow (Wm -2) using published soil temperature heat flow functions. Both CO2 flux and heat flow were analysed statistically and then modelled using 500 sequential Gaussian simulations. Forty subsoil CO 2 gas samples were also analysed for stable C isotopes. Following 20a of production, current CO2 emissions equated to 111??6.7T/d. Observed heat flow was 70??6.4MW, compared with a pre-production value of 122MW. This 52MW reduction in surface heat flow is due to production-induced drying up of all alkali-Cl outflows (61.5MW) and steam-heated pools (8.6MW) within the Ohaaki West thermal area (OHW). The drying up of all alkali-Cl outflows at Ohaaki means that the soil zone is now the major natural pathway of heat release from the high-temperature reservoir. On the other hand, a net gain in thermal ground heat flow of 18MW (from 25MW to 43.3??5MW) at OHW is associated with permeability increases resulting from surface unit fracturing by production-induced ground subsidence. The Ohaaki East (OHE) thermal area showed no change in distribution of shallow and deep soil temperature contours despite 20a of production, with an observed heat flow of 26.7??3MW and a CO 2 emission rate of 39??3T/d. The negligible change in the thermal status of the OHE thermal area is attributed to the low permeability of the reservoir beneath this area, which has limited production (mass extraction) and sheltered the area from the pressure decline within the main reservoir. Chemistry suggests that although alkali-Cl outflows once contributed significantly to the natural surface heat flow (~50%) they contributed little (<1%) to pre-production CO 2

  18. Investigation of direct expansion in ground source heat pumps

    NASA Astrophysics Data System (ADS)

    Kalman, M. D.

    A fully instrumented subscale ground coupled heat pump system was developed, and built, and used to test and obtain data on three different earth heat exchanger configurations under heating conditions (ground cooling). Various refrigerant flow control and compressor protection devices were tested for their applicability to the direct expansion system. Undistributed Earth temperature data were acquired at various depths. The problem of oil return at low evaporator temperatures and low refrigerant velocities was addressed. An analysis was performed to theoretically determine what evaporator temperature can be expected with an isolated ground pipe configuration with given length, pipe size, soil conditions and constant heat load. Technical accomplishments to data are summarized.

  19. Reconciling Volatile Outputs with Heat Flow and Magma Intrusion Rates at the Yellowstone Magma-Hydrothermal System

    NASA Astrophysics Data System (ADS)

    Lowenstern, J. B.; Hurwitz, S.

    2012-12-01

    The Yellowstone hydrothermal system releases hundreds of millions of liters of water on a daily basis. Gigawatts of heat and kilotons of magmatic volatiles (CO2, S, Cl, F and He) are discharged by these waters. By quantifying the relative contributions of crustal, meteoric, and mantle-derived components, we can estimate the rate at which magma is fed to the crust from below (1). Combining isotopic studies with mass discharge rates of geothermal gases and aqueous dissolved solids, we recognize that over 20,000 tons of CO2 is released from basaltic magmas ponding beneath any silicic magma reservoir in the mid to shallow crust (1,2). In contrast, silicic magma provides significantly less volatiles than what emerges from the hydrothermal system. Estimates of heat flow range from ~3 to 8 GW (1,3,4), derived from satellite, surface geophysics and geochemical methods. Such values, combined with estimates from gas flux, imply prolific basalt intrusion rates between 0.05 and 0.3 cubic kilometers per year (1). Over the history of the Yellowstone Plateau Volcanic Field, a picture emerges where the lower crust is converted from Precambrian metasediments and silicic intrusions into a thick gabbroic batholith similar to that envisioned by some to reside beneath the Snake River Plain along the ancestral track of the Yellowstone Hot Spot (5). (1) Lowenstern and Hurwitz, 2008, Elements 4: 35-40. (2) Werner and Brantley, 2003, G-Cubed 4;7: 1061 (3) Vaughan and others, 2012, JVGR 233-234: 72-89. (4) Hurwitz and others, in press, JGR (5) Shervais and others, 2006, Geology 34:365-368.

  20. Potential industrial applications for direct contact waste heat recuperator systems

    NASA Astrophysics Data System (ADS)

    Semler, T. T.

    1981-02-01

    Four potential applications were chosen for economic analysis. They are: stack gas from diesel electric generation, boiler stack gas, waste heat stream from the hydraulic cement dry process dryer, and stack gas from the fire polishing of glass. The waste heat streams studied ranged from 175 to 7500 F. A physical analogue of the direct contact waste heat recuperator system was devised and used for costing purposes. Payback calculations were performed for these applications. Only the stack gas from the fire polishing of glass failed to show significant economic promise. A waste heat stream regime of greater than 10,000 cfm and between 400 and 7500 F was identified as most economically promising for direct contact waste heat recuperation and hot process water delivery.

  1. Absorption type water chiller fired directly by waste heat

    NASA Astrophysics Data System (ADS)

    Sauer, K. L.; Kalwar, K.

    1982-08-01

    The direct use of waste heat as heating element in a water chiller of the absorption type was studied. The chilled water is used as cooling element in the industrial process, producing the waste heat or for conditioning the workplace or further located places. The heat source is gaseous or liquid. The cooling capacity is in the range from 10 to 120 kW. After reviewing the different absorption systems, LiBr/H20 proved to be the most suitable. The process retained for experimenting was the manufacturing of synthetic materials polymer industry and was tested in two different factories. It is proved that the use of absorption type water chillers is practicable with an efficiency of 10% to 25% of the waste heat energy, but that the existing chillers need extensive conversion for obtaining economical operation when using a low temperature heating source.

  2. Direct Hydrothermal Precipitation of Pyrochlore-Type Tungsten Trioxide Hemihydrate from Alkaline Sodium Tungstate Solution

    NASA Astrophysics Data System (ADS)

    Li, Xiaobin; Li, Jianpu; Zhou, Qiusheng; Peng, Zhihong; Liu, Guihua; Qi, Tiangui

    2012-04-01

    Pyrochlore-type tungsten trioxide hemihydrate (WO3·0.5H2O) powder with the average particle size of 0.5 μm was prepared successfully from the weak alkaline sodium tungstate solution by using organic substances of sucrose or cisbutenedioic acid as the acidification agent. The influences of solution pH and acidification agents on the precipitation process were investigated. The results showed that organic acidification agents such as sucrose and cisbutenedioic acid could improve the precipitation of pyrochlore WO3·0.5H2O greatly from sodium tungstate solution compared with the traditional acidification agent of hydrochloric acid. In addition, the pH value of the hydrothermal system played a critical role in the precipitation process of WO3·0.5H2O, and WO3·0.5H2O precipitation mainly occured in the pH range of 7.0 to 8.5. The precipitation rate of tungsten species in the sodium tungstate solution could reach up to 98 pct under the optimized hydrothermal conditions. This article proposed also the hydrothermal precipitation mechanism of WO3·0.5H2O from the weak alkaline sodium tungstate solution. The novel method reported in this study has a great potential to improve the efficiency of advanced tungsten trioxide-based functional material preparation, as well as for the pollution-reducing and energy-saving tungsten extractive metallurgy.

  3. Hydrothermal Processes

    NASA Astrophysics Data System (ADS)

    German, C. R.; von Damm, K. L.

    2003-12-01

    What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater

  4. Influence of Heat Treatment on Photocatalytic Performance of BiVO4 Synthesized by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Shen, Yi; Wang, Xiaomin; Zuo, Guifu; Li, Fengfeng; Meng, Yanzhi

    2016-10-01

    Monoclinic BiVO4 photocatalyst was successfully synthesized by hydrothermal method under appropriate temperature. The photocatalytic performance of BiVO4 was improved by calcining at appropriate temperature. The structural and morphological properties of the synthesized BiVO4 photocatalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. It is confirmed that the photocatalytic activity of the prepared catalysts was evaluated by the photodegradation of RhB under visible-light irradiation. BiVO4 calcined under appropriate temperature exhibited higher photocatalytic activity than uncalcined BiVO4 under visible light irradiation because calcination might effectively increases the purity of monoclinic bismuth vanadate.

  5. One-step hydrothermal synthesis of nitrogen-doped nanocarbons: albumine directing the carbonization of glucose.

    PubMed

    Baccile, Niki; Antonietti, Markus; Titirici, Maria-Magdalena

    2010-02-22

    We present a simple and green one-step pathway towards nitrogen-doped carbon nanostructures with controlled mesoporosity through hydrothermal treatment of glucose in the presence of model proteins. Performing the reaction with different amounts of egg white ovalbumin protein (OvA), carbonaceous nanoparticles or continuous nanosponges with high specific surface areas can be efficiently produced. The nitrogen content of the structures is rather high (up to 8 wt%) and can be kept constant up to 950 degrees C, while oxygen elimination and graphitization of the carbon material occurs. We demonstrate here that sustainable natural resources can be efficiently used in the synthesis of pure high-potential nanomaterials.

  6. OSCAR - Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge

    NASA Astrophysics Data System (ADS)

    Hobbs, Richard

    2017-04-01

    of 0.25°C combined with a decrease of 0.01 psu in salinity. Evidence of hydrothermally driven plumes were also detected along the CRR but exact locations of their sources were not found. Our best estimate from the OSCAR data show that the geothermal contribution is over 70% to the abyssal water upwelling. This is the largest contribution yet observed in abyssal basins and is in line with a growing number of studies arguing that geothermal heating plays a significant role in driving the abyssal and global circulation.

  7. Direct synthesis of silver/polymer/carbon nanocables via a simple hydrothermal route

    SciTech Connect

    Jin Mingshang; Kuang Qin Jiang Zhiyuan; Xu Tao; Xie Zhaoxiong Zheng Lansun

    2008-09-15

    High-yield silver/polymer/carbon nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. High-resolution TEM and element mapping proved that as-prepared nanocables consist of a silver nanowire core, a polymer inner shell, and a graphitic carbon outer shell. A three-step growth mechanism was proposed to explain the growth of such three-layer nanocables, i.e. the formation of silver nanowires, the glycosidation of glucose molecules on silver nanowire surface and the carbonization of the outmost glycosidation layer. We believe that reaction temperature plays the key role in the polymerization of glucose and sequent surface-carbonization. - Graphical abstract: High-yield silver/polymer/carbon coaxial nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. Our experiments indicate that such novel nanostructures formed through the growth mechanism that the silver nanowires grow first, and then glycosidation of glucose occurs on the silver nanowire surfaces, and finally the partial carbonization occurs on the outmost surface of the polymer layer.

  8. Heat flow along the Costa Rica Seismogenesis Project drilling transect: Implications for hydrothermal and seismic processes

    NASA Astrophysics Data System (ADS)

    Hass, Bridget; Harris, Robert N.

    2016-06-01

    Heat flow analysis of the Costa Rica convergent margin is carried out for seven sites drilled during Integrated Ocean Drilling Program (IODP) Expeditions 334 and 344 as part of the Costa Rica Seismogenesis Project (CRISP). These expeditions are designed to better understand erosional subduction zones. Heat flow measurements were made to improve estimates of the thermal structure of this erosive margin and are located on the incoming plate, toe, lower, middle, and upper slopes of the margin. Heat flow values corrected for the effects of seafloor bathymetry and sedimentation are on average 15% higher than uncorrected values and range from approximately 158-200 mW/m2 on the incoming plate to values of approximately 50 mW/m2 on the middle and upper slopes of the margin. These values are consistent with previous estimates of heat flow showing a landward decrease in heat flow consistent with subduction of the Cocos plate. Preferred thermal models of the shallow subduction zone successfully predicting observed values of heat flow incorporate fluid flow within the upper oceanic aquifer have an uppermost permeability of 10-9.5 m2 and a plate boundary effective coefficient of friction of 0.06. These models suggest that temperatures on the subduction thrust reach 100°C at distances between 30 and 35 km landward of the deformation front. The updip limit of seismicity, as defined by aftershocks events of ML 1-4 recorded following the Mw 6.9 Quepos earthquake, occurs at 25 km landward of the deformation front at temperatures cooler than the 100-150°C typically predicted.

  9. Comparison of microwaves to fluidized sand baths for heating tubular reactors for hydrothermal and dilute acid batch pretreatment of corn stover.

    PubMed

    Shi, Jian; Pu, Yunqiao; Yang, Bin; Ragauskas, Arthur; Wyman, Charles E

    2011-05-01

    Heating of batch tubular reactors with fluidized sand baths and with microwaves resulted in distinctive sugar yield profiles from pretreatment and subsequent enzymatic hydrolysis of corn stover at the same time, temperature, and dilute sulfuric acid concentration combinations and hydrothermal pretreatment conditions. Microwave heated pretreatment led to faster xylan, lignin, and acetyl removal as well as earlier xylan degradation than sand baths, but maximum sugar recoveries were similar. Solid state CP/MAS NMR revealed that microwave heating was more effective in altering cellulose structural features especially in breakdown of amorphous regions of corn stover than sand bath heating. Enzymatic hydrolysis of pretreated corn stover was improved by microwave heating compared to sand bath heating. Mechanisms were proposed to explain the differences in results for the two systems and provide new insights into pretreatment that can help advance this technology. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Geothermal direct-heat study: Imperial County, California

    SciTech Connect

    Not Available

    1983-05-01

    Potential applications of geothermal energy which would be compatible with the agricultural activities in the county were identified and a plan to attract potential users to the area was developed. The intent of the first effort was to identify general classifications of industries which could utilize geothermal heat in production processes. Two levels of analyses were utilized for this effort. Initially, activities relying on previously developed engineering and industrial concepts were investigated to determine capital costs, employment, and potential energy savings. Second, innovative concepts not yet fully developed were investigated to determine their potential applicability to the agricultural base of the county. These investigations indicated that the major potential applications of geothermal heat would involve industries related to food processing or other direct agriculture-related uses of raw materials produced or imported to the county. An implementation plan which can be utilized by the county to market direct heat applications was developed. A socioeconomics analysis examined the potential effects on the county from development of direct heat projects. The county's planning and permitting requirements for dirct heat projects were also examined.

  11. Thermal performance of direct contact heat exchangers for mixed hydrocarbons

    SciTech Connect

    Sharpe, L. Jr.; Coswami, D.Y.; Demuth, O.J.; Mines, G.

    1985-01-01

    This paper describes a physical and a mathematical model for evaluating the tray efficiencies for a direct contact heat exchanger (DCHX). The model is then used to determine the efficiencies for tests conducted on a 60kW sieve tray DCHX as heat is transferred from a geofluid (brine) to a working fluid (mixed hydrocarbons). It is assumed that there are three distinct regions in the column based on the state of the working fluid, as follows: Region I - Preheating with no vaporization; Region II - Preheating with moderate vaporization; and Region III - Major vaporization. The boundaries of these regions can be determined from the experimental data. In the model, mass balance and energy balance is written for a tray ''N'' in each of these regions. Finally, the ''tray efficiency'' or ''heat transfer'' effectiveness of the tray is calculated based on the definition that it is the ratio of the actual heat transfer to the maximum possible, thermodynamically.

  12. Direct electronic measurement of Peltier cooling and heating in graphene.

    PubMed

    Vera-Marun, I J; van den Berg, J J; Dejene, F K; van Wees, B J

    2016-05-10

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials.

  13. Direct electronic measurement of Peltier cooling and heating in graphene

    NASA Astrophysics Data System (ADS)

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-05-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials.

  14. Direct electronic measurement of Peltier cooling and heating in graphene

    PubMed Central

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-01-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials. PMID:27161186

  15. Decontamination of drinking water by direct heating in solar panels.

    PubMed

    Fjendbo Jørgensen, A J; Nøhr, K; Sørensen, H; Boisen, F

    1998-09-01

    A device was developed for direct heating of water by solar radiation in a flow-through system of copper pipes. An adjustable thermostat valve prevents water below the chosen temperature from being withdrawn. The results show that it is possible to eliminate coliform and thermotolerant coliform bacteria from naturally contaminated river water by heating to temperatures of 65 degrees C or above. Artificial additions of Salmonella typhimurium, Streptococcus faecalis and Escherichia coli to contaminated river water were also inactivated after heating to 65 degrees C and above. The total viable count could be reduced by a factor of 1000. The heat-resistant bacteria isolated from the Mlalakuva River (Tanzania) were spore-forming bacteria which exhibited greater heat resistance than commonly used test bacteria originating from countries with colder climates. To provide a good safety margin it is recommended that an outlet water temperature of 75 degrees C be used. At that temperature the daily production was about 501 of decontaminated water per m2 of solar panel, an amount that could be doubled by using a heat exchanger to recycle the heat.

  16. 10 CFR 429.22 - Direct heating equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Direct heating equipment. 429.22 Section 429.22 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION, COMPLIANCE, AND ENFORCEMENT FOR CONSUMER PRODUCTS AND... efficiency or other measure of energy consumption of a basic model for which consumers would favor...

  17. 10 CFR 429.22 - Direct heating equipment.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Direct heating equipment. 429.22 Section 429.22 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION, COMPLIANCE, AND ENFORCEMENT FOR CONSUMER PRODUCTS AND... efficiency or other measure of energy consumption of a basic model for which consumers would favor...

  18. 10 CFR 429.22 - Direct heating equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Direct heating equipment. 429.22 Section 429.22 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION, COMPLIANCE, AND ENFORCEMENT FOR CONSUMER PRODUCTS AND... efficiency or other measure of energy consumption of a basic model for which consumers would favor...

  19. Exterior direct view of (nonoriginal), solar heating panels, and top ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior direct view of (non-original), solar heating panels, and top of typical rectangular trash-dump tower at roof of Building 6, looking north - North Beach Place, 401 Bay Street, 500 Francisco Street, 401 Bay Street, 500 Francisco Street, San Francisco, San Francisco County, CA

  20. Thermal performance of a geofluid direct-contact heat exchanger

    SciTech Connect

    Wiggins, D.J.; Mines, G.L.; Wahl, E.

    1983-01-01

    A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280/sup 0/F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ratios which produced different boiling conditions. In this paper, the results of these experiments are analyzed on the basis of thermal performance. The flow ratio, the geofluid outlet temperature, the working fluid inlet temperature, the amount of working fluid dissolved or entrained in geofluid, and tray efficiency are varied and preheating temperature profiles are calculated. These are compared with the experimentally obtained temperature profiles and the relative effects of the variables are evaluated. From this, it was determined that the approach temperature difference was on the order of .1/sup 0/ after 17 preheating trays, and the tray efficiencies, which appear to be about the same for all trays, reached approx. 70%. It was also determined that entrainment has a negligible effect on column thermal performance. The thermal performance of this column compares favorably with a spray-tower direct-contact heat exchanger and a shell-and-tube heat exchanger in terms of overall heat-transfer coefficient. Distributor tray and boiling tray behavior are discussed. These is some discussion of operations and thermal hydraulics as well.

  1. Formation of hydrothermal pits and the role of seamounts in the Guatemala Basin (Equatorial East Pacific) from heat flow, seismic, and core studies

    NASA Astrophysics Data System (ADS)

    Villinger, H. W.; Pichler, T.; Kaul, N.; Stephan, S.; Pälike, H.; Stephan, F.

    2017-01-01

    We acquired seismic and heat flow data and collected sediment cores in three areas in the Guatemala Basin (Cocos Plate, Eastern Pacific) to investigate the process by which depressions (pits) in the sedimentary cover on young oceanic crust were formed. Median heat flow of 55 mW/m2 for the three areas is about half of the expected conductive cooling value. The heat deficit is caused by massive recharge of cold seawater into the upper crust through seamounts which is inferred from depressed heat flow in the vicinity of seamounts. Heat flow inside of pits is always elevated, in some cases up to three times (max. 300 mW/m2) relative to background. None of the geochemical pore water profiles from cores inside and outside of the pits show any evidence of active fluid flow inside the pits. All three areas originated within the high productivity equatorial zone and moved northwest over the past 15 to 18 Ma. Pits found in the working areas are likely relict dissolution structures formed by diffuse hydrothermal venting in a zone of high biogenic carbonate production which were sealed when they moved north. It is likely that these pits were discharge sites of "hydrothermal siphons" where recharging seamounts could feed cold seawater via the upper crust to several discharging pits. Probably pit density on the whole Cocos Plate is similar to the three working areas and which may explain the huge heat deficit of the Cocos Plate.

  2. Directional melting of alumina via polarized microwave heating

    NASA Astrophysics Data System (ADS)

    Hu, Yuan; Nakano, Aiichiro; Wang, Joseph

    2017-01-01

    Dynamical instabilities and melting of crystals upon heating are fundamental problems in physics and materials science. Using molecular dynamics simulations, we found that drastically different melting temperatures and behaviors can be achieved in α-alumina using microwave heating, where the electric field is aligned with different crystallographic orientations. Namely, alumina melts much earlier at lower temperatures when the electric field is parallel to the c-axis. The atomistic mechanism was identified as selective liberation of the Al sublattice due to the shear instability along the c-axis. This directional melting concept may be used for triggering distinct dynamical instabilities and melting of dielectric crystals using polarized microwave fields.

  3. Geothermal Frontier: Penetrate a boundary between hydrothermal convection and heat conduction zones to create 'Beyond Brittle Geothermal Reservoir'

    NASA Astrophysics Data System (ADS)

    Tsuchiya, N.; Asanuma, H.; Sakaguchi, K.; Okamoto, A.; Hirano, N.; Watanabe, N.; Kizaki, A.

    2013-12-01

    EGS has been highlightened as a most promising method of geothermal development recently because of applicability to sites which have been considered to be unsuitable for geothermal development. Meanwhile, some critical problems have been experimentally identified, such as low recovery of injected water, difficulties to establish universal design/development methodology, and occurrence of large induced seismicity. Future geothermal target is supercritical and superheated geothermal fluids in and around ductile rock bodies under high temperatures. Ductile regime which is estimated beyond brittle zone is target region for future geothermal development due to high enthalpy fluids and relatively weak water-rock interaction. It is very difficult to determine exact depth of Brittle-Ductile boundary due to strong dependence of temperature (geotherm) and strain rate, however, ductile zone is considered to be developed above 400C and below 3 km in geothermal fields in Tohoku District. Hydrothermal experiments associated with additional advanced technology will be conducting to understand ';Beyond brittle World' and to develop deeper and hotter geothermal reservoir. We propose a new concept of the engineered geothermal development where reservoirs are created in ductile basement, expecting the following advantages: (a)simpler design and control the reservoir, (b)nearly full recovery of injected water, (c)sustainable production, (d)cost reduction by development of relatively shallower ductile zone in compression tectonic zones, (e)large quantity of energy extraction from widely distributed ductile zones, (f)establishment of universal and conceptual design/development methodology, and (g) suppression of felt earthquakes from/around the reservoirs. In ductile regime, Mesh-like fracture cloud has great potential for heat extraction between injection and production wells in spite of single and simple mega-fracture. Based on field observation and high performance hydrothermal

  4. Heat flow control and segregation in directional solidification

    NASA Technical Reports Server (NTRS)

    Witt, A. F.; Rohsenow, W. M.; Houpt, P. K.

    1982-01-01

    Optimization of the vertical Bridgman technique for growth of electronic materials in single crystal form was investigated. The limitations of the crystal growth configuration were experimentally determined and heat transfer related deficiencies identified. Design of an alternate system was based on the use of heat pipes separated by a gradient region. Heat transfer analyses based on one and two dimensional models indicated the necessity of a flexible gradient zone configuration. Directional melting of binary systems as encountered during seeding in melt growth was analysed for concurrent compositional changes at the crystal-metal interface, and the theoretical treatment numerically applied to HgCdTe and Ga doped germanium. A theoretical and experimental study of the thermal effects associated with current flow was conducted. It was found that experimental measurements of dc induced growth during crystal pulling can be used for the precise determination of the Peltier coefficient.

  5. Countercurrent direct contact heat exchange process and system

    DOEpatents

    Wahl, III, Edward F.; Boucher, Frederic B.

    1979-01-01

    Recovery of energy from geothermal brines and other hot water sources by direct contact heat exchange with a working fluid, such as a hydrocarbon working fluid, e.g. isobutane. The process and system consists of a plurality of stages, each stage including mixing and settling units. In the first stage, hot brine and arm working fluid are intimately mixed and passed into a settler wherein the brine settles to the bottom of the settler and the hot working fluid rises to the top. The hot working fluid is passed to a heat engine or turbine to produce work and the working fluid is then recycled back into the system. The system is comprised of a series of stages each containing a settler and mixer, and wherein the working fluid and the brine flow in a countercurrent manner through the stages to recover the heat from the brine in increments and raise the temperature of the working fluid in increments.

  6. Heat flow control and segregation in directional solidification

    NASA Technical Reports Server (NTRS)

    Witt, A. F.; Rohsenow, W. M.; Houpt, P. K.

    1982-01-01

    Optimization of the vertical Bridgman technique for growth of electronic materials in single crystal form was investigated. The limitations of the crystal growth configuration were experimentally determined and heat transfer related deficiencies identified. Design of an alternate system was based on the use of heat pipes separated by a gradient region. Heat transfer analyses based on one and two dimensional models indicated the necessity of a flexible gradient zone configuration. Directional melting of binary systems as encountered during seeding in melt growth was analysed for concurrent compositional changes at the crystal-metal interface, and the theoretical treatment numerically applied to HgCdTe and Ga doped germanium. A theoretical and experimental study of the thermal effects associated with current flow was conducted. It was found that experimental measurements of dc induced growth during crystal pulling can be used for the precise determination of the Peltier coefficient.

  7. Seismic Reflection Imaging of the Heat Source of an Ultramafic-Hosted Hydrothermal System (Rainbow, Mid-Atlantic Ridge 36° 10-17'N)

    NASA Astrophysics Data System (ADS)

    Canales, J. P.; Dunn, R. A.; Sohn, R. A.; Horning, G.; Arai, R.; Paulatto, M.

    2015-12-01

    Most of our understanding of hydrothermal systems and the nature of their heat sources comes from models and observations at fast and intermediate spreading ridges. In these settings, hydrothermal systems are mainly located within the axial zone of a spreading segment, hosted in basaltic rock, and primarily driven by heat extracted from crystallization of crustal melt sills. In contrast, hydrothermal systems at slow-spreading ridges like the Mid-Atlantic Ridge (MAR) show a great variety of venting styles and host-rock lithology, and are located in diverse tectonic settings like axial volcanic ridges, non-transform discontinuities (NTDs), the foot of ridge valley walls, and off-axis inside corner highs. Among MAR systems, the Rainbow hydrothermal field (RHF) stands out as an end-member of this diversity: an ultramafic-hosted system emitting H2 and CH4-rich fluids at high temperatures and high flow rates, which suggests a magmatic heat source despite the lack of evidence for recent volcanism and its location within an NTD with presumably low magma budget. We present 2D multichannel seismic reflection images across the Rainbow massif from the NSF-funded MARINER multidisciplinary geophysical study that reveal, for the first time, the magmatic system driving hydrothermal circulation in an ultramafic setting. Data were acquired in 2013 onboard the RV M. Langseth with an 8-km-long hydrophone streamer. The images have been obtained from pre-stack depth migrations using a regional 3D P-wave velocity model from a coincident controlled-source seismic tomography experiment using ocean bottom seismometers. Our images show a complex magmatic system centered beneath the RHF occupying an areal extent of ~3.7x6 km2, with partially molten sills ranging in depth between ~3.4 km and ~6.9 km below the seafloor. Our data also image high-amplitude dipping reflections within the massif coincident with strong lateral velocity gradients that may arise from detachment fault planes

  8. Induced Seismicity Related to Hydrothermal Operation of Geothermal Projects in Southern Germany - Observations and Future Directions

    NASA Astrophysics Data System (ADS)

    Megies, T.; Kraft, T.; Wassermann, J. M.

    2015-12-01

    Geothermal power plants in Southern Germany are operated hydrothermally and at low injection pressures in a seismically inactive region considered very low seismic hazard. For that reason, permit authorities initially enforced no monitoring requirements on the operating companies. After a series of events perceived by local residents, a scientific monitoring survey was conducted over several years, revealing several hundred induced earthquakes at one project site.We summarize results from monitoring at this site, including absolute locations in a local 3D velocity model, relocations using double-difference and master-event methods and focal mechanism determinations that show a clear association with fault structures in the reservoir which extend down into the underlying crystalline basement. To better constrain the shear wave velocity models that have a strong influence on hypocentral depth estimates, several different approaches to estimate layered vp/vs models are employed.Results from these studies have prompted permit authorities to start imposing minimal monitoring requirements. Since in some cases these geothermal projects are only separated by a few kilometers, we investigate the capabilities of an optimized network combining the monitoring resources of six neighboring well doublets in a joint network. Optimization is taking into account the -- on this local scale, urban environment -- highly heterogeneous background noise conditions and the feasibility of potential monitoring sites, removing non-viable sites before the optimization procedure. First results from the actual network realization show good detection capabilities for small microearthquakes despite the minimum instrumentational effort, demonstrating the benefits of good coordination of monitoring efforts.

  9. Shrinking of Solid-state Nanopores by Direct Thermal Heating.

    PubMed

    Asghar, Waseem; Ilyas, Azhar; Billo, Joseph Anthony; Iqbal, Samir Muzaffar

    2011-05-04

    Solid-state nanopores have emerged as useful single-molecule sensors for DNA and proteins. A novel and simple technique for solid-state nanopore fabrication is reported here. The process involves direct thermal heating of 100 to 300 nm nanopores, made by focused ion beam (FIB) milling in free-standing membranes. Direct heating results in shrinking of the silicon dioxide nanopores. The free-standing silicon dioxide membrane is softened and adatoms diffuse to a lower surface free energy. The model predicts the dynamics of the shrinking process as validated by experiments. The method described herein, can process many samples at one time. The inbuilt stress in the oxide film is also reduced due to annealing. The surface composition of the pore walls remains the same during the shrinking process. The linear shrinkage rate gives a reproducible way to control the diameter of a pore with nanometer precision.

  10. Geothermal Direct-Heat Utilization Assistance - Final Report

    SciTech Connect

    J. W. Lund

    1999-07-14

    The Geo-Heat Center provided (1) direct-use technical assistance, (2) research, and (3) information dissemination on geothermal energy over an 8 1/2 year period. The center published a quarterly bulletin, developed a web site and maintained a technical library. Staff members made 145 oral presentations, published 170 technical papers, completed 28 applied research projects, and gave 108 tours of local geothermal installations to 500 persons.

  11. ON THE DIRECT IMAGING OF TIDALLY HEATED EXOMOONS

    SciTech Connect

    Peters, Mary Anne; Turner, Edwin L.

    2013-06-01

    We demonstrate the ability of existing and planned telescopes, on the ground and in space, to directly image tidally heated exomoons orbiting gas-giant exoplanets. Tidally heated exomoons can plausibly be far more luminous than their host exoplanet and as much as 0.1% as bright as the system's stellar primary if it is a low mass star. Because emission from exomoons can be powered by tidal forces, they can shine brightly at arbitrarily large separations from the system's stellar primary with temperatures of several hundreds degrees Kelvin or even higher in extreme cases. Furthermore, these high temperatures can occur in systems that are billions of years old. Tidally heated exomoons may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected separation (typically at least tens of AU) from their primary to be accessible to current generation direct imaging studies. For example, the (warm) Spitzer Space Telescope and the next generation of ground based instruments could detect an exomoon roughly the size of the Earth at a temperature Almost-Equal-To 600 K and a distance Almost-Equal-To 5 pc in the K, L, and M bands at the 5{sigma} confidence level with a one hour exposure; in more favorable but still plausible cases, detection at distances of tens of parsecs is feasible. Future mid-infrared space telescopes, such as James Webb Space Telescope and SPICA, will be capable of directly imaging tidally heated exomoons around the nearest two dozen stars with a brightness temperature {>=}300 K and R {>=} 1 R{sub Circled-Plus} orbiting at {>=}12 AU from the primary star at a 5{sigma} confidence level in a 10{sup 4} s integration. In addition it is possible that some of the exoplanets which have already been directly imaged are actually tidally heated exomoons or blends of such objects with hot young planets. If such exomoons exist and are sufficiently common (i.e., nearby), it may well be far easier to

  12. Direct contact liquid-liquid heat exchanger for solar heated and cooled buildings

    NASA Astrophysics Data System (ADS)

    Karaki, S.; Brothers, P.

    1980-06-01

    The technical and economic feasibility of using a direct contract liquid-liquid heat exchanger (DCLLHE) storage unit in a solar heating and cooling system is established. Experimental performance data were obtained from the CSU Solar House I using a DCLLHE for both heating and cooling functions. A simulation model for the system was developed. The model was validated using the experimental data and applied in five different climatic regions of the country for a complete year. The life-cycle cost of the system was estimated for each application. The results are compared to a conventional solar system, using a standard shell-and-tube heat exchanger. It is concluded that while there is a performance advantage with a DCLLHE system over a conventional solar system, the advantage is not sufficiently large to overcome slightly higher capital and operating costs for the DCLLHE system.

  13. Directly Measured Heating Rates of a Tropical Subvisible Cirrus Cloud

    NASA Technical Reports Server (NTRS)

    Bucholtz, Anthongy; Hlavka, Dennis L.; McGill, Matthew J.; Schmidt, K. Sebastian; Pilewskie, Peter; Davis, Sean M.; Reid, Elizabeth A.; Walker, Annette L.

    2010-01-01

    We present the first direct measurements of the infrared and solar heating rates of a tropical subvisible cirrus (SVC) cloud sampled off the east coast of Nicaragua on 25 July 2007 by the NASA ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4). On this day a persistent thin cirrus layer, with mostly clear skies underneath, was detected in real time by the cloud lidar on the ER-2, and the aircraft was directed to profile down through the SVC. Measurements of the net broadband infrared irradiance and spectrally integrated solar irradiance above, below, and through the SVC are used to determine the infrared and solar heating rates of the cloud. The lidar measurements show that the variable SVC layer was located between approximately 13 and 15 km. Its midvisible optical depth varied from 0.01 to 0.10 with a mean of 0.034 +/- 0.033. Its depolarization ratio was approximately 0.4, indicative of ice clouds. From the divergence of the measured net irradiances the infrared heating rate of the SVC was determined to be approximately 2.50 - 3.24 K/d and the solar heating rate was found to be negligible. These values are consistent with previous indirect observations of other SVC and with model-generated heating rates of SVC with similar optical depths. This study illustrates the utility and potential of the profiling sampling strategy employed here. A more fully instrumented high-altitude aircraft that also included in situ cloud and aerosol probes would provide a comprehensive data set for characterizing both the radiative and microphysical properties of these ubiquitous tropical clouds

  14. Use of ASTER and MODIS thermal infrared data to quantify heat flow and hydrothermal change at Yellowstone National Park

    USGS Publications Warehouse

    Vaughan, R. Greg; Keszthelyi, Laszlo P.; Lowenstern, Jacob B.; Jaworowski, Cheryl; Heasler, Henry

    2012-01-01

    The overarching aim of this study was to use satellite thermal infrared (TIR) remote sensing to monitor geothermal activity within the Yellowstone geothermal area to meet the missions of both the U.S. Geological Survey and the Yellowstone National Park Geology Program. Specific goals were to: 1) address the challenges of monitoring the surface thermal characteristics of the > 10,000 spatially and temporally dynamic thermal features in the Park (including hot springs, pools, geysers, fumaroles, and mud pots) that are spread out over ~ 5000 km2, by using satellite TIR remote sensing tools (e.g., ASTER and MODIS), 2) to estimate the radiant geothermal heat flux (GHF) for Yellowstone's thermal areas, and 3) to identify normal, background thermal changes so that significant, abnormal changes can be recognized, should they ever occur (e.g., changes related to tectonic, hydrothermal, impending volcanic processes, or human activities, such as nearby geothermal development). ASTER TIR data (90-m pixels) were used to estimate the radiant GHF from all of Yellowstone's thermal features and update maps of thermal areas. MODIS TIR data (1-km pixels) were used to record background thermal radiance variations from March 2000 through December 2010 and establish thermal change detection limits. A lower limit for the radiant GHF estimated from ASTER TIR temperature data was established at ~ 2.0 GW, which is ~ 30–45% of the heat flux estimated through geochemical thermometry. Also, about 5 km2 of thermal areas was added to the geodatabase of mapped thermal areas. A decade-long time-series of MODIS TIR radiance data was dominated by seasonal cycles. A background subtraction technique was used in an attempt to isolate variations due to geothermal changes. Several statistically significant perturbations were noted in the time-series from Norris Geyser Basin, however many of these did not correspond to documented thermal disturbances. This study provides concrete examples of the

  15. Use of ASTER and MODIS thermal infrared data to quantify heat flow and hydrothermal change at Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Vaughan, R. Greg; Keszthelyi, Laszlo P.; Lowenstern, Jacob B.; Jaworowski, Cheryl; Heasler, Henry

    2012-07-01

    The overarching aim of this study was to use satellite thermal infrared (TIR) remote sensing to monitor geothermal activity within the Yellowstone geothermal area to meet the missions of both the U.S. Geological Survey and the Yellowstone National Park Geology Program. Specific goals were to: 1) address the challenges of monitoring the surface thermal characteristics of the > 10,000 spatially and temporally dynamic thermal features in the Park (including hot springs, pools, geysers, fumaroles, and mud pots) that are spread out over ~ 5000 km2, by using satellite TIR remote sensing tools (e.g., ASTER and MODIS), 2) to estimate the radiant geothermal heat flux (GHF) for Yellowstone's thermal areas, and 3) to identify normal, background thermal changes so that significant, abnormal changes can be recognized, should they ever occur (e.g., changes related to tectonic, hydrothermal, impending volcanic processes, or human activities, such as nearby geothermal development). ASTER TIR data (90-m pixels) were used to estimate the radiant GHF from all of Yellowstone's thermal features and update maps of thermal areas. MODIS TIR data (1-km pixels) were used to record background thermal radiance variations from March 2000 through December 2010 and establish thermal change detection limits. A lower limit for the radiant GHF estimated from ASTER TIR temperature data was established at ~ 2.0 GW, which is ~ 30-45% of the heat flux estimated through geochemical thermometry. Also, about 5 km2 of thermal areas was added to the geodatabase of mapped thermal areas. A decade-long time-series of MODIS TIR radiance data was dominated by seasonal cycles. A background subtraction technique was used in an attempt to isolate variations due to geothermal changes. Several statistically significant perturbations were noted in the time-series from Norris Geyser Basin, however many of these did not correspond to documented thermal disturbances. This study provides concrete examples of the strengths

  16. Chemical environments of submarine hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

  17. A direct-interface, fusible heat sink for astronaut cooling

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis; Webbon, B. W.

    1990-01-01

    Astronaut cooling during extravehicular activity is a critical design issue in developing a portable life support system that meets the requirements of a space station mission. Some of the requirements are that the cooling device can be easily regenerable and nonventing during operation. In response to this, a direct-interface, fusible heat sink prototype with freezable quick-disconnects was developed. A proof-of-concept prototype was constructed and tested that consists of an elastic container filled with normal tap water and having two quick-disconnects embedded in a wall. These quick-disconnects are designed so that they may be frozen with the ice and yet still be joined to the cooling system, allowing an immediate flow path. The inherent difficulties in a direct-interface heat sink have been overcome, i.e., (1) establishing an initial flow path; (2) avoiding low-flow freeze-up; and (3) achieving adequate heat-transfer rates at the end of the melting process. The requirements, design, fabrication, and testing are discussed.

  18. A direct-interface fusible heat sink for astronaut cooling

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis; Webbon, B. W.

    1990-01-01

    Astronaut cooling during extravehicular activity is a critical design issue in developing a portable life support system that meets the requirements of a space station mission. Some the requirements are that the cooling device can be easily regenerable and nonventing during operation. In response to this, a direct-interface, fusible heat sink prototpye with freezable quick-disconnects was developed. A proof-of-concept prototype was constructed and tested that consists of an elastic container filled with normal tap water and having two quick-disconnects embedded in a wall. These quick-disconnects are designed so that they may be frozen with the ice and yet still be joined to the cooling system, allowing an immediate flow path. The inherent difficulties in a direct-interface heat sink have been overcome, i.e., (1) establishing an initial flow path; (2) avoiding low-flow freeze-up; and (3) achieving adequate heat-transfer rates at the end of the melting process. The requirements, design, fabrication, and testing are discussed.

  19. Direct containment heating models in the CONTAIN code

    SciTech Connect

    Washington, K.E.; Williams, D.C.

    1995-08-01

    The potential exists in a nuclear reactor core melt severe accident for molten core debris to be dispersed under high pressure into the containment building. If this occurs, the set of phenomena that result in the transfer of energy to the containment atmosphere and its surroundings is referred to as direct containment heating (DCH). Because of the potential for DCH to lead to early containment failure, the U.S. Nuclear Regulatory Commission (USNRC) has sponsored an extensive research program consisting of experimental, analytical, and risk integration components. An important element of the analytical research has been the development and assessment of direct containment heating models in the CONTAIN code. This report documents the DCH models in the CONTAIN code. DCH models in CONTAIN for representing debris transport, trapping, chemical reactions, and heat transfer from debris to the containment atmosphere and surroundings are described. The descriptions include the governing equations and input instructions in CONTAIN unique to performing DCH calculations. Modifications made to the combustion models in CONTAIN for representing the combustion of DCH-produced and pre-existing hydrogen under DCH conditions are also described. Input table options for representing the discharge of debris from the RPV and the entrainment phase of the DCH process are also described. A sample calculation is presented to demonstrate the functionality of the models. The results show that reasonable behavior is obtained when the models are used to predict the sixth Zion geometry integral effects test at 1/10th scale.

  20. Heat Flow on the Incoming Plate Offshore Nicoya, Costa Rica margin: Implications for Hydrothermal Circulation and the Thermal State of the Subducting Plate

    NASA Astrophysics Data System (ADS)

    Fisher, A. T.; Harris, R. N.; Stein, C.; Wang, K.; Hutnak, M.; Cherkaoui, A.; Pfender, M.; Cleary, R.; Silver, E.; Wheat, C. G.; Bodzin, R.; Underwood, M.; Moser, C.; Kelly, R.; Friedmann, P.; Stewart, Y.; Jones, K.

    2001-12-01

    The TicoFlux I expedition was intended to determine the nature of hydrothermal activity and its influence on subduction processes offshore of the Nicoya Peninsula, Costa Rica margin, on 20-25 Ma lithosphere. Prior coverage in this region was sparse, but suggested that heat flow from crust created at the East Pacific Rise (EPR) as generally lower (by 50-70%) than expected for seafloor of 20-25 Ma. In contrast, heat flow through similarly-aged seafloor created at the Cocos-Nazca Ridge was at or greater than values predicted by standard lithospheric cooling models. One goal of our expedition was to confirm this overall pattern through collection of modern data at higher resolution along a series of transects coinciding with newly-acquired seismic profiles. A second goal was to determine the cause for the difference in heat flow, through evaluation of the lateral scale of the transition between higher and lower values. If the difference in heat flow is caused by variations in heat input at the base of the plate, the transition should be broad and gradual, with a wavelength that scales with plate thickness. If the difference in seafloor heat flow results from advective mining of heat from EPR-generated lithosphere, the transition should be abrupt, with a wavelength that scales with the depth of hydrothermal cooling. We crossed the transition in three places and in each case, the change from normal to anomalously-low heat flow values occurred over a distance of just a few kilometers, consistent with a shallow, fluid flow explanation. In addition, the survey identified an area of anomalously high heat flow (640 mW/m2) immediately above a deep, low-angle reflection that may be a crust-penetrating fault. High heat flow in this area may result from fluid circulation along the fault, carrying heat from depth. The heat flow survey also demonstrated that a low-heat flow area identified during an earlier survey, and drilled during ODP Leg 170, is surrounded on three sides by

  1. Hawaiian direct-heat grants encourage geothermal creativity

    SciTech Connect

    Beck, A.G. )

    1988-12-01

    The Hawaiian Community Geothermal Technology Program is unique. Under its auspices, heat and other by-products of Hawaii's high-temperature HGP-A geothermal well and power plant are not wasted. Instead, they form the backbone of a direct-heat grant program that reaches into the local community and encourages community members to develop creative uses for geothermal energy. A by-product of this approach is a broadened local base of support for geothermal energy development. With the experimental and precommercial work completed, most of the original grantees are looking for ways to continue their projects on a commercial scale by studying the economics of using geothermal heat in a full-scale business and researching potential markets. A geothermal mini-park may be built near the research center. In 1988, a second round of projects was funded under the program. The five new projects are: Geothermal Aquaculture Project - an experiment with low-cost propagation of catfish species in geothermally heated tanks with a biofilter; Media Steam Sterilization and Drying - an application of raw geothermal steam to shredded, locally-available materials such as coconut husks, which would be used as certified nursery growing media; Bottom-Heating System Using Geothermal Power for Propagation - a continuation of Leilani Foliage's project from the first round of grants, focusing on new species of ornamental palms; Silica Bronze - the use of geothermal silica as a refractory material in casting bronze artwork; and Electro-deposition of Minerals in Geothermal Brine - the nature and possible utility of minerals deposited from the hot fluid.

  2. The effect of heating direction on flow boiling heat transfer of R134a in micro-channels

    NASA Astrophysics Data System (ADS)

    Xu, Mingchen; Jia, Li; Dang, Chao; Peng, Qi

    2017-04-01

    This paper presents effects of heating directions on heat transfer performance of R134a flow boiling in micro- channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500μm width 500μm depth and 30mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm2 and 373.3 to 1244.4 kg/m2s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 kW/m2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified correlation was provided to predict heat transfer of top heating.

  3. Metal bead crystals for easy heating by direct current.

    PubMed

    Voigtländer, Bert; Cherepanov, Vasily; Elsaesser, Christa; Linke, Udo

    2008-03-01

    The preparation of metal bead crystals with two wires attached to the crystal is described. These crystals allow for a very easy and efficient method to heat metal single crystals by direct current heating through the connecting wires of the bead crystal. This heating of the bead crystal is sufficient to clean metal surfaces such as the surfaces of Pt and Au as confirmed by Auger spectroscopy and scanning tunneling microscopy (STM). There is no need for any ion sputtering which is conventionally used to clean metal single crystal surfaces. The bead crystals with two leads fabricated from a wide range metals and metal alloys such as Cu, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Ir, Pt, Au, PtPd, PtRh, AuAg, and PtIr can be used as general purpose metal substrates for surface science studies and other applications. Additionally, these bead crystals can be used to reshape STM tips by indentation of the tip into the soft metal in order to recover atomic resolution imaging on hard substrates.

  4. Wind energy for direct water heating. Final report

    SciTech Connect

    Gunkel, W.W.; Lacey, D.R.; Neyeloff, So.; Porter, T.G.

    1981-05-01

    Results of the research project Wind Energy Substitution at Dairy Milking Centers are presented. Described in detail is the development of an energy conversion unit for direct conversion of shaft power to heat. Design procedures are presented to aid in design of a fluid agitator type energy conversion system that will be matched to the power output characteristics of any specific wind turbine. A prototype wind driven heating system was assembled including a commercial wind turbine - the Pinson Cycloturbine - and monitored continuously for twelve months. The excellent compatibility of the wind turbine and the fluid agitator was verified through field testing. The turbine operated near its maximum power coefficient with no speed control other than the loading of the agitator unit through winds of up to 25 m/s (52 mph). Results of this one year field test are presented including: (1) wind speed spectrum and power density at the site; (2) daily record of system energy output; and (3) operating time. Mechanical repair and maintenance experience are included, providing a complete record of operation of the prototype wind energy heating system.

  5. Experiment and analysis of directional effects on radiant heat transfer.

    NASA Technical Reports Server (NTRS)

    Toor, J. S.; Viskanta, R.

    1972-01-01

    Critical examination of the validity of the commonly used simplified models for predicting local and overall radiant heat interchange among real surfaces. The spectral local irradiation was measured at wavelengths of 3.08 and 4.51 microns in a configuration consisting of three plane parallel surfaces of finite extent. The test surfaces were gold with mechanical roughness and temperature varying from 0.02 to 7.1 microns and 77 to 760 K, respectively. Comparisons between experimental data and predictions for six different models ranging from the simple diffuse to the most detailed diffuse-plus-specular-directional-property model with specular component calculated according to Beckmann are presented. It is shown that the calculation of the overall irradiation using appropriate constant-property models agrees well with the experimental data to within combined experimental and analytical uncertainty. In general, it is concluded that for accurate prediction of local irradiation the directional characteristics of the surfaces must be considered.

  6. Time Series Measurements of Diffuse Hydrothermal Flow at the ASHES Vent Field Reveal Tidally Modulated Heat and Volume Flux

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E. L.; Fornari, D. J.; Crone, T. J.

    2015-12-01

    Existing time-series measurements of temperature and velocity of diffuse hydrothermal fluids exhibit variability over a range of periods from seconds to days. Frequency analysis of these measurements reveals differences between studies and field locations including nearly white spectra, as well as spectra with peaks at tidal and inertial periods. Based upon these results, previous authors have suggested several processes that may control diffuse flow rates, including tidally induced currents and 'tidal pumping', and have also suggested that there are no systematic controls. To further investigate the processes that control variability in diffuse flow, we use data from a new, deep-sea camera and temperature measurement system, the Diffuse Effluent Measurement System (DEMS), deployed during the July, 2014 cruise of the R/V Atlantis. The DEMS was deployed with DSV Alvin above a fracture network at the Phoenix vent within the ASHES vent field (Axial Seamount, 1541 mbsl). The system collected 20 seconds of imagery at 20 Hz and 24 seconds of temperature measurements at 1 Hz each hour over the period between July 22 and August 2nd. Velocities of the upwelling fluids were calculated using Diffuse Fluid Velocimetry (DFV; Mittelstaedt et al., 2010). DFV is a cross correlation technique that tracks moving index of refraction anomalies (i.e., hot parcels of fluid) through time. Over the ~12 day deployment, median flow rates ranged from 0.5 cm/s to 6 cm/s and mean fluid temperature anomalies from 0°C up to ~6.5°C, yielding an average heat flux density of 0.23 MW/m2. Spectral analysis of both the measured temperatures and calculated velocities yield a peak in normalized power at the semi-diurnal lunar period (M2, 12.4hrs), but no other spectral peaks above the 95% confidence level. Here, we present these results and discuss their implications for the tidal current and tidal pressure models of diffuse flow variability at the ASHES vent field.

  7. Hydrothermal Processing

    SciTech Connect

    Elliott, Douglas C.

    2011-03-11

    This chapter is a contribution to a book on Thermochemical Conversion of Biomass being edited by Prof. Robert Brown of Iowa State University. It describes both hydrothermal liquefaction and hydrothermal gasification of biomass to fuels.

  8. Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the lower crust along fast-spreading Mid-Ocean Ridges?

    NASA Astrophysics Data System (ADS)

    Fontaine, Fabrice J.; Rabinowicz, M.; Cannat, M.

    2017-05-01

    We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper crust and magmatic flow in the lower crust. In an end-member category of models corresponding to effective viscosities μM lower than 1013 Pa.s in a melt-rich lower crustal along-axis corridor and permeability k not exceeding ˜10-16 m2 in the upper crust, the hot, melt-rich, gabbroic lower crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1-2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8-10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and South-East Pacific Rise (SEPR). The lower crustal plumes deliver melt locally at the top of the magmatic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent ˜100 MW vents fields. Our models also contribute to current discussions on how the lower crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the lower crust.

  9. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Beeler, N. M.; Hickman, S. H.

    2008-12-01

    Room-temperature friction and indentation experiments suggest fault strengthening during the interseismic period results from increases in asperity contact area due to solid-state deformation. However, field observations on exhumed fault zones indicate that solution-transport processes, pressure solution, crack healing and contact overgrowth, influence fault zone rheology near the base of the seismogenic zone. Contact overgrowths result from gradients in surface curvature, where material is dissolved from the pore walls, diffuses through the fluid and precipitates at the contact between two asperities, cementing the asperities together without convergence normal to the contact. To determine the mechanisms and kinetics of asperity cementation, we conducted laboratory experiments in which convex and flat lenses prepared from quartz single crystals were pressed together in an externally heated pressure vessel equipped with an optical observation port. Convergence between the two lenses and contact morphology were continuously monitored during these experiments using reflected-light interferometry through a long-working-distance microscope. Contact normal force is constant with an initial effective normal stress of 1.7 MPa. Four single-phase experiments were conducted at temperatures between 350 and 530C at 150 MPa water pressure, along with two controls: one single phase, dry at 425C and one bimaterial (qtz/sapphire) at 425C and 150 MPa water pressure. No contact growth or convergence was observed in either of the controls. For wet single-phase contacts, however, growth was initially rapid and then decreased with time following an inverse squared dependence of contact radius on aperture. No convergence was observed over the duration of these experiments, suggesting that neither significant pressure solution nor crystal plasticity occurred at these stresses and temperatures. The formation of fluid inclusions between the lenses indicate that the contact is not uniformly

  10. Experimental investigation of direct contact three phase boiling heat transfer

    SciTech Connect

    Bruce, W.D.

    1981-01-01

    The system which was studied in the present work consisted of one liquid undergoing vaporization by contact with a hotter immiscible liquid. The liquids and vapor were contacted in a counterflow spray column with only differential increases in vapor quality. Experiments yielded vertical temperature profiles, flow rates of the phases, liquid holdups, pressure drops, and a characterization of flow patterns. A micro-computer was utilized for measuring temperatures in the column at the rate of 1500 to 1600 times per second at several depths. Analysis of the experimental data indicate that the maximum temperature difference between the phases is 0.5F/sup 0/, and that a temperature crossover occurs at the lower end of the column. The heat transfer fluid undergoes flash vaporization at its inlet at the top of the column, and much of its sensible heat is tranferred to the dispersed phase near the top of the column. Temperature profiles along the length of the boiler are nearly flat, and very little heat transfer occurs in the lower part of the boiler. A chemical method was developed for measuring effective interfacial area in a direct contact boiler. The theoretical basis of the method is discussed, and physico-chemical data necessary for application of the technique are reported. Water solubility of methyl salicylate was measured as a function of temperature, and the second order reaction rate coefficient for saponification of methyl salicylate by sodium hydroxide was determined from sodium hydroxide concentration versus time data and a computer model of a well-mixed semibatch reactor. The activation energy for the reaction was found to be 9.58 kilocalories per gram mole.

  11. Market penetration analysis for direct heat geothermal energy applications

    SciTech Connect

    Thomas, R.J.; Nelson, R.A.

    1981-06-01

    This study is concerned with the estimation of the National geothermal market potential and penetration in direct heat applications for residences and certain industry segments. An important aspect of this study is that the analysis considers both known and anticipated goethermal resources. This allows for an estimation of the longer-range potential for geothermal applications. Thus the approach and results of this study provide new insights and valuable information not obtained from more limited, site-specific types of analyses. Estimates made in this study track geothermal market potential and projected penetration from the present to the year 2020. Private sector commercialization of geothermal energy over this period requires assistance in the identification of markets and market sizes, potential users, and appropriate technical applications.

  12. A directed matched filtering algorithm (DMF) for discriminating hydrothermal alteration zones using the ASTER remote sensing data

    NASA Astrophysics Data System (ADS)

    Fereydooni, H.; Mojeddifar, S.

    2017-09-01

    This study introduced a different procedure to implement matched filtering algorithm (MF) on the ASTER images to obtain the distribution map of alteration minerals in the northwestern part of the Kerman Cenozoic Magmatic Arc (KCMA). This region contains many areas with porphyry copper mineralization such as Meiduk, Abdar, Kader, Godekolvari, Iju, Serenu, Chahfiroozeh and Parkam. Also argillization, sericitization and propylitization are the most common types of hydrothermal alteration in the area. Matched filtering results were provided for alteration minerals with a matched filtering score, called MF image. To identify the pixels which contain only one material (endmember), an appropriate threshold value should be used to the MF image. The chosen threshold classifies a MF image into background and target pixels. This article argues that the current thresholding process (the choice of a threshold) shows misclassification for MF image. To address the issue, this paper introduced the directed matched filtering (DMF) algorithm in which a spectral signature-based filter (SSF) was used instead of the thresholding process. SSF is a user-defined rule package which contains numeral descriptions about the spectral reflectance of alteration minerals. On the other hand, the spectral bands are defined by an upper and lower limit in SSF filter for each alteration minerals. SSF was developed for chlorite, kaolinite, alunite, and muscovite minerals to map alteration zones. The validation proved that, at first: selecting a contiguous range of MF values could not identify desirable results, second: unexpectedly, considerable frequency of pure pixels was observed in the MF scores less than threshold value. Also, the comparison between DMF results and field studies showed an accuracy of 88.51%.

  13. Diffuse venting at the ASHES hydrothermal field: Heat flux and tidally modulated flow variability derived from in situ time-series measurements

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; Fornari, Daniel J.; Crone, Timothy J.; Kinsey, James; Kelley, Deborah; Elend, Mitch

    2016-04-01

    Time-series measurements of diffuse exit-fluid temperature and velocity collected with a new, deep-sea camera, and temperature measurement system, the Diffuse Effluent Measurement System (DEMS), were examined from a fracture network within the ASHES hydrothermal field located in the caldera of Axial Seamount, Juan de Fuca Ridge. The DEMS was installed using the HOV Alvin above a fracture near the Phoenix vent. The system collected 20 s of 20 Hz video imagery and 24 s of 1 Hz temperature measurements each hour between 22 July and 2 August 2014. Fluid velocities were calculated using the Diffuse Fluid Velocimetry (DFV) technique. Over the ˜12 day deployment, median upwelling rates and mean fluid temperature anomalies ranged from 0.5 to 6 cm/s and 0°C to ˜6.5°C above ambient, yielding a heat flux of 0.29 ± 0.22 MW m-2 and heat output of 3.1± 2.5 kW. Using a photo mosaic to measure fracture dimensions, the total diffuse heat output from cracks across ASHES field is estimated to be 2.05 ± 1.95 MW. Variability in temperatures and velocities are strongest at semidiurnal periods and show significant coherence with tidal height variations. These data indicate that periodic variability near Phoenix vent is modulated both by tidally controlled bottom currents and seafloor pressure, with seafloor pressures being the dominant influence. These results emphasize the importance of local permeability on diffuse hydrothermal venting at mid-ocean ridges and the need to better quantify heat flux associated with young oceanic crust.

  14. New directions for district heating in the United States

    NASA Astrophysics Data System (ADS)

    Olszewski, M.; Karnitz, M. A.

    A description is given of the status of major US district heating projects and the potential impact of the newly implemented US National District Heating plan. Five major district heating projects moving into the construction and demonstration phase are described. Although all have hot water distribution systems, a variety of heat sources are utilized. These include geothermal water, industrial reject heat, and utility cogeneration using coal-fired power plants.

  15. Age alters the cardiovascular response to direct passive heating

    NASA Technical Reports Server (NTRS)

    Minson, C. T.; Wladkowski, S. L.; Cardell, A. F.; Pawelczyk, J. A.; Kenney, W. L.

    1998-01-01

    During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Qc) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 +/- 1 yr) and seven older (O; 70 +/- 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Qc (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Qc was significantly lower in the older than in the young men (11.1 +/- 0.7 and 7.4 +/- 0.2 l/min in Y and O, respectively, at the limit of thermal tolerance; P < 0. 05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 +/- 7 and 68 +/- 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Qc observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 +/- 3 and 75 +/- 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 +/- 80 and 720 +/- 100 ml/min in Y and O, respectively, P < 0. 05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to

  16. Age alters the cardiovascular response to direct passive heating

    NASA Technical Reports Server (NTRS)

    Minson, C. T.; Wladkowski, S. L.; Cardell, A. F.; Pawelczyk, J. A.; Kenney, W. L.

    1998-01-01

    During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Qc) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 +/- 1 yr) and seven older (O; 70 +/- 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Qc (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Qc was significantly lower in the older than in the young men (11.1 +/- 0.7 and 7.4 +/- 0.2 l/min in Y and O, respectively, at the limit of thermal tolerance; P < 0. 05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 +/- 7 and 68 +/- 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Qc observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 +/- 3 and 75 +/- 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 +/- 80 and 720 +/- 100 ml/min in Y and O, respectively, P < 0. 05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to

  17. Direct formation of gold nanoparticles on substrates using a novel ZnO sacrificial templated-growth hydrothermal approach and their properties in organic memory device.

    PubMed

    Goh, Lean Poh; Razak, Khairunisak Abdul; Ridhuan, Nur Syafinaz; Cheong, Kuan Yew; Ooi, Poh Choon; Aw, Kean Chin

    2012-10-10

    This study describes a novel fabrication technique to grow gold nanoparticles (AuNPs) directly on seeded ZnO sacrificial template/polymethylsilsesquioxanes (PMSSQ)/Si using low-temperature hydrothermal reaction at 80°C for 4 h. The effect of non-annealing and various annealing temperatures, 200°C, 300°C, and 400°C, of the ZnO-seeded template on AuNP size and distribution was systematically studied. Another PMMSQ layer was spin-coated on AuNPs to study the memory properties of organic insulator-embedded AuNPs. Well-distributed and controllable AuNP sizes were successfully grown directly on the substrate, as observed using a field emission scanning electron microscope followed by an elemental analysis study. A phase analysis study confirmed that the ZnO sacrificial template was eliminated during the hydrothermal reaction. The AuNP formation mechanism using this hydrothermal reaction approach was proposed. In this study, the AuNPs were charge-trapped sites and showed excellent memory effects when embedded in PMSSQ. Optimum memory properties of PMMSQ-embedded AuNPs were obtained for AuNPs synthesized on a seeded ZnO template annealed at 300°C, with 54 electrons trapped per AuNP and excellent current-voltage response between an erased and programmed device.

  18. Hydrothermal waves under microgravity in a differentially heated long liquid bridge with aspect ratio near the Rayleigh-limit

    NASA Astrophysics Data System (ADS)

    Schwabe, D.

    2005-08-01

    A liquid bridge of 15.0 mm length L and 3.0 mm radius r (aspect ratio A = L/r = 5) from 2 cSt silicone oil (Pr = 28) was established under microgravity during the flight of the sounding rocket MAXUS-4. Four different temperature differences ΔT = 7K, 9K, 10K, 12K have been applied between the ends, each for sufficient time to reach steady state thermocapillary flow conditions. The aim of the experiment - to observe the onset of hydrothermal waves and to measure their features like the waves phase speed and the angle between the wave vector and the applied temperature gradient - was reached. We used microgravity in this experiment in a twofold manner; (1) a liquid bridge with A = 5 can be established only under microgravity; (2) it was possible to study hydrothermal waves without the influence of gravity and without the aspect ratio restrictions at normal gravity.

  19. Persistent Directional Current at Equilibrium in Nonreciprocal Many-Body Near Field Electromagnetic Heat Transfer

    NASA Astrophysics Data System (ADS)

    Zhu, Linxiao; Fan, Shanhui

    2016-09-01

    We consider the consequence of nonreciprocity in near-field heat transfer by studying systems consisting of magneto-optical nanoparticles. We demonstrate that, in thermal equilibrium, a nonreciprocal many-body system in heat transfer can support a persistent directional heat current, without violating the second law of thermodynamics. Such a persistent directional heat current cannot occur in reciprocal systems, and can only arise in many-body systems in heat transfer. The use of nonreciprocity therefore points to a new regime of near-field heat transfer for the control of heat flow in the nanoscale.

  20. High Temperature Hydrothermal Components in the Sediment Cover of the Saldanha Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Dias, A.; Frueh-Green, G. L.; Bernasconi, S. M.; Mills, R. A.; Taylor, R. N.; Barriga, F. J.

    2006-12-01

    sediment core imply much higher temperatures of mineral precipitation (up to 260° C ) than those measured directly at the vent orifices in 2001 (9° C).Hydrothermal minerals are precipitated subsurface, preserving minerals from oxidizing conditions. The high temperature of mineral precipitation suggested by our data requires a significant heat input to this system, raising the question of the heat source of this system and the role of serpentinization processes, as no magmatic heat source has yet been found.

  1. Metal Hydride Heat Storage Technology for Directed Energy Weapon Systems

    DTIC Science & Technology

    2007-11-16

    over time after the pulse operation. A compressor -driven metal hydride heat storage system was developed for efficient, compact heat storage and...principle and heat storage performance results of the compressor -driven metal hydride heat storage system through system modeling and prototype testing. The...hyd/m³] Subscripts A Metal hydride reactor B Hydrogen container C Hydrogen compressor s Hydrogen solid phase in hydride f Hydrogen fluid phase

  2. Influence Of Subsurface Biosphere On Geochemical Fluxes From Diffuse Hydrothermal Fluids: Direct Measurement Of Subsurface Hydrogen Oxidation

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Germanovich, L. N.; Lilley, M. D.; Genc, G.; DiPerna, C. J.; Bradley, A. S.; Olson, E. J.; Girguis, P. R.

    2011-12-01

    After decades of research on hydrothermal vent biogeochemistry, quantification of low-temperature diffusive geochemical fluxes remains elusive and limits our ability to place constraints on their role in global geochemical cycles. Quantifying the relative differences in geochemical composition, in particular of energy-rich compounds such as H2 and CH4, between focused high-temperature and diffuse low-temperature hydrothermal fluids can allow the estimation of metabolic rates in the underlying subsurface biosphere. Towards shortening the gap in our understanding of geochemical and microbial dynamics of the subsurface biosphere, we deployed an in situ mass spectrometer (ISMS) and low flow meter to quantify biologically relevant volatiles in a wide range of flow regimes and temperatures. Here we present coupled in situ chemical analyses and flow measurements that enable quantification of geochemical fluxes from a diversity of diffuse and focused vents along the Juan de Fuca Ridge hydrothermal system. We show that geochemical flux from diffuse vents can equal or exceed that emanating from hot, focused vents. Notably, hydrogen concentrations in fluids emerging from diffuse vents are 50% to 80% lower than predicted. We attribute the loss of hydrogen in diffuse vent fluids to microbial consumption in the subsurface, and suggest that subsurface microbial communities can significantly influence hydrothermal geochemical fluxes to the deep ocean.

  3. State of technology of direct contact heat exchanging

    SciTech Connect

    Vallario, R.W.; DeBellis, D.E.

    1984-05-01

    Specific objectives of this study were to assess the state of technology development and to identify and evaluate the constraints to wider use of direct contact heat exchanger (DCHE) technology in the U.S. The scope of this study is relatively broad; it includes many types of generic systems and end-use applications, both current and future. Domestic and foreign experience with DCHE technology are compared, although the primary focus is on domestic experience. Twenty-two distinct applications of DCHE technology were identified in this study and are examined in this report. The general format is to describe each system, explore its potential applications, discuss current and past research activities and identify major implementation barriers. Finally, as a result of discussions with principal users of DCHE systems and with other knowledgeable sources, generic and specific R and D needs to overcome specific implementation barriers have been identified. The following list of DCHE systems/concepts has been classified into four major end-uses; there is also a category for specialized (other) applications.

  4. Geothermal direct-heat utilization assistance: Quarterly project progress report, January--March 1995

    SciTech Connect

    1995-05-01

    The report summarizes geothermal activities of the Geo-Heat Center at Oregon Institute of Technology for the second quarter of FY-95. It describes 92 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, resources and equipment. Research activities are summarized on geothermal energy cost evaluation, low temperature resource assessment and ground-source heat pump case studies and utility programs. Outreach activities include the publication of a geothermal direct heat Bulletin, dissemination of information, geothermal library, and progress monitor reports on geothermal resources and utilization.

  5. The Lassen hydrothermal system

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.

    2016-01-01

    The active Lassen hydrothermal system includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest hydrothermal system in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen system accounts for a full 1/3 of the total high-temperature hydrothermal heat discharge in the U.S. Cascades (140/400 MW). Hydrothermal heat discharge of ~140 MW can be supported by crystallization and cooling of silicic magma at a rate of ~2400 km3/Ma, and the ongoing rates of heat and magmatic CO2 discharge are broadly consistent with a petrologic model for basalt-driven magmatic evolution. The clustering of observed seismicity at ~4–5 km depth may define zones of thermal cracking where the hydrothermal system mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length <50 m. Observational records of hydrothermal discharge are likely too short to document long-term transients, whether they are intrinsic to the system or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent hydrothermal measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic system, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.

  6. Direct use of sunflower oil as a heating oil

    SciTech Connect

    Karaosmanoglu, F.; Kurt, G.

    1998-11-01

    Vegetable oils in particular have exceptional importance since they can be used as a fuel oil (heating oil type) alternative. In this research evaluation, the possibilities of sunflower oil as a heating oil candidate have been investigated. The fuel oil property tests of sunflower oil were performed according to standard methods. An overall evaluation of data indicates that sunflower oil can be proposed as a possible substitute for heating oil.

  7. Magnetic carbon composites with a hierarchical structure for adsorption of tetracycline, prepared from sugarcane bagasse via hydrothermal carbonization coupled with simple heat treatment process.

    PubMed

    Rattanachueskul, Natthanan; Saning, Amonrada; Kaowphong, Sulawan; Chumha, Nawapong; Chuenchom, Laemthong

    2017-02-01

    Sugarcane bagasse, an agricultural waste, was successfully converted into novel magnetic carbon composites by low temperature hydrothermal carbonization at 230°C for 24h, followed by heat treatment at 400°C for only 1h in air. Effects of NaOH and iron loading on the chemical properties of the composites were studied. In addition, various techniques were employed to investigate the physicochemical properties of the composites. Adsorption kinetics and isotherms were investigated with tetracycline (TC) for the magnetic composites. The magnetic carbon composite exhibited 48.35mg/g maximum adsorption capacity and was highly stable chemically and mechanically, with also good magnetic properties. The adsorption of TC by the magnetic adsorbent was mainly attributed to H-bonds and π-π interactions. The results indicate that waste sugarcane bagasse from the sugar industries can be efficiently transformed to a magnetic adsorbent for TC removal via a facile environmentally friendly method.

  8. Strong bonding strength between HA and (NH4)2S2O8-treated carbon/carbon composite by hydrothermal treatment and induction heating.

    PubMed

    Xiong, Xin-bo; Zeng, Xie-rong; Zou, Chun-li; Zhou, Ji-Zhao

    2009-06-01

    Carbon/carbon composite with hydroxyapatite (HA) coating is an attractive material in the dental and orthopedic fields, but the reported bonding strength between them was very poor. In this study, a compact crystalline HA coating on (NH(4))(2)S(2)O(8)-treated C/C substrate about 10 microm in width was obtained by hydrothermal treatment and induction heating. The microstructure, composition and morphologies of the as-prepared coatings were identified by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. A strong shear strength averaging 74.2 MPa between C/C substrate and HA was achieved and adhesion failures were observed more frequently than cohesion failures. The coating adhesion measured using a scratch test was 23 N and the reasons for this are discussed.

  9. Numerical analysis of magnetic field effects on hydro-thermal behavior of a magnetic nanofluid in a double pipe heat exchanger

    NASA Astrophysics Data System (ADS)

    Shakiba, Ali; Vahedi, Khodadad

    2016-03-01

    This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% Fe3O4) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Reff=50 is between Mn=1.33×106 and Mn=2.37×106. So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

  10. Environmental Assessment: geothermal direct heat project, Marlin, Texas

    SciTech Connect

    Not Available

    1980-08-01

    The Federal action addressed by this Environmental Assessment (EA) is joint funding the retrofitting of a heating and hot water system in a hospital at Marlin, Texas, with a geothermal preheat system. The project will be located within the existing hospital boiler room. One supply well was drilled in an existing adjacent parking lot. It was necessary to drill the well prior to completion of this environmental assessment in order to confirm the reservoir and to obtain fluids for analysis in order to assess the environmental effects of fluid disposal. Fluid from operation will be disposed of by discharging it directly into existing street drains, which will carry the fluid to Park Lake and eventually the Brazos River. Fluid disposal activities are regulated by the Texas Railroad Commission. The local geology is determined by past displacements in the East Texas Basin. Boundaries are marked by the Balcones and the Mexia-Talco fault systems. All important water-bearing formations are in the cretaceous sedimentary rocks and are slightly to highly saline. Geothermal fluids are produced from the Trinity Group; they range from approximately 3600 to 4000 ppM TDS. Temperatures are expected to be above 64/sup 0/C (147/sup 0/F). Surface water flows southeastward as a part of the Brazos River Basin. The nearest perennial stream is the Brazos River 5.6 km (3.5 miles) away, to which surface fluids will eventually discharge. Environmental impacts of construction were small because of the existing structures and paved areas. Construction run-off and geothermal flow-test fluid passed through a small pond in the city park, lowering its water quality, at least temporarily. Construction noise was not out of character with existing noises around the hospital.

  11. Hydrothermal Activity on ultraslow Spreading Ridge: new hydrothermal fields found on the Southwest Indian ridge

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.

    2014-12-01

    Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that hydrothermal activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active hydrothermal field found on the ultraslow spreading ridge. In recent years, over 10 hydrothermal fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities. In 2014, CC 30thdiscovered five hydrothermal fields and several hydrothermal anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A hydrothermal anomaly area, centered at 49.66°E,37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several hydrothermal fields and controlled by a NW fault. New discovery of hydrothermal fields. From January to April 2014, five hydrothermal fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon

  12. 76 FR 63211 - Energy Efficiency Program: Test Procedures for Residential Water Heaters, Direct Heating...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-12

    ... Heating Equipment, and Pool Heaters AGENCY: Office of Energy Efficiency and Renewable Energy, Department... amendments to DOE's test procedures for residential water heaters, direct heating equipment, and pool heaters... heating equipment test procedures as applied to vented hearth heaters, and coverage of electric...

  13. Benefit-cost analysis of DOE's Current Federal Program to increase hydrothermal resource utilization. Final report

    SciTech Connect

    Not Available

    1981-12-10

    The impact of DOE's Current Federal Program on the commercialization of hydrothermal resources between 1980 and 2000 is analyzed. The hydrothermal resources of the United States and the types of DOE activities used to stimulate the development of these resources for both electric power and direct heat use are described briefly. The No Federal Program and the Current Federal Program are then described in terms of funding levels and the resultant market penetration estimates through 2000. These market penetration estimates are also compared to other geothermal utilization forecasts. The direct benefits of the Current Federal Program are next presented for electric power and direct heat use applications. An analysis of the external impacts associated with the additional hydrothermal resource development resulting from the Current Federal Program is also provided. Included are environmental effects, national security/balance-of-payments improvements, socioeconomic impacts and materials requirements. A summary of the analysis integrating the direct benefits, external impacts and DOE program costs concludes the report.

  14. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1992-01-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) to determine the effect of H[sub 2]S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H[sub 2]S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10[degrees] or greater. Size limitations restrict applications to 100 gpm and/or 200 ft[sup 2] heat transfer surface area.

  15. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1993-02-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) in order to determine the effect of H[sub 2]S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H[sub 2]S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10[degree] or greater. Size limitations restrict applications to 100 gpm and/or 200 ft[sup 2] heat transfer surface area.

  16. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1993-02-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) in order to determine the effect of H{sub 2}S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H{sub 2}S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10{degree} or greater. Size limitations restrict applications to 100 gpm and/or 200 ft{sup 2} heat transfer surface area.

  17. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1992-12-31

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) to determine the effect of H{sub 2}S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H{sub 2}S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10{degrees} or greater. Size limitations restrict applications to 100 gpm and/or 200 ft{sup 2} heat transfer surface area.

  18. Geothermal direct-heat utilization assistance. Quarterly project progress report, January--March 1996

    SciTech Connect

    1996-05-01

    This report summarizes geothermal technical assistance, R&D, and technology transfer activities of the Geo-Heat Center. It describes 95 contacts with parties during this period related to technical assistance with goethermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics, and resources. Research activities are summarized on geothermal district heating system cost evaluation and silica waste utilization project. Outreach activities include publication of a geothermal direct use Bulletin, dissemination of information, goethermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

  19. Geothermal direct-heat utilization assistance. Quarterly project progress report, July 1995--September 1995

    SciTech Connect

    Lienau, P.

    1995-12-01

    The report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the fourth quarter of FY-95. It describes 80 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment and resources. Research activities are summarized on low-temperature resource assessment, geothermal energy cost evaluation and marketing strategy for geothermal district heating. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

  20. Thermal effects on hydrothermal biomass liquefaction.

    PubMed

    Zhang, Bo; von Keitz, Marc; Valentas, Kenneth

    2008-03-01

    Batch pressure vessels commonly used for hydrothermal liquefaction have typical heating times in the range of 30 to 60 min. Thermodynamically, the complex set of reactions are path dependent, so that the heating rate can possibly affect yields and the composition of the resultant liquid products. It is postulated that the mode of heat transfer becomes an uncontrolled variable in kinetic studies and can seriously impact scale-up. To confirm this hypothesis and minimize these heat-transfer-related artifacts, we designed a batch pressure vessel equipped with an induction heating system, which allows the reduction of heat-up times by about two orders of magnitude to several seconds, compared to tens of minutes with standard pressure reactors. This system was used to study the direct liquefaction of corn stover and aspen wood with a pretreatment. The heating rate was found to have no significant effect on the composition of the liquid products. However, the liquid yields are dependent on the heating rate. Varying the cooling rate does not show obvious effects. The results confirm that the heating rate, as governed by the mode of heat transfer, is an important factor that needs to be considered during scale-up.

  1. Thermoelectric Devices, Being Blown Through with a Substance in the Direction of Heat Flow

    DTIC Science & Technology

    1974-04-06

    thermoelectric devices being blown through with a substance in the direction of heat flow are described. A battery of this kind of thermoelements can be use in...capillaries. A battery of these thermoelements can serve for utilizing the heat of combustion products produced in some heat-using facility. Tne...consumption of the heat carrier and its temperature ahead of the battery will be specified. If we know the geometrical characteristics of thermoelements

  2. Geothermal direct-heat utilization assistance. Quarterly project progress report, July 1994--September 1994

    SciTech Connect

    Not Available

    1994-10-01

    This paper is a third quarter 1994 report of activities of the Geo-Heat Center of Oregon Institute of Technology. It describes contacts with parties during this period related to assistance with geothermal direct heat applications. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, resources, and equipment. Research is also being conducted on failures of vertical lineshaft turbines in geothermal wells.

  3. DIRECT MEASUREMENT OF HEAT FLUX FROM COOLING LAKE THERMAL IMAGERY

    SciTech Connect

    Garrett, A; Eliel Villa-Aleman, E; Robert Kurzeja, R; Malcolm Pendergast, M; Timothy Brown, T; Saleem Salaymeh, S

    2007-12-19

    Laboratory experiments show a linear relationship between the total heat flux from a water surface to air and the standard deviation of the surface temperature field, {sigma}, derived from thermal images of the water surface over a range of heat fluxes from 400 to 1800 Wm{sup -2}. Thermal imagery and surface data were collected at two power plant cooling lakes to determine if the laboratory relationship between heat flux and {sigma} exists in large heated bodies of water. The heat fluxes computed from the cooling lake data range from 200 to 1400 Wm{sup -2}. The linear relationship between {sigma} and Q is evident in the cooling lake data, but it is necessary to apply band pass filtering to the thermal imagery to remove camera artifacts and non-convective thermal gradients. The correlation between {sigma} and Q is improved if a correction to the measured {sigma} is made that accounts for wind speed effects on the thermal convection. Based on more than a thousand cooling lake images, the correlation coefficients between {sigma} and Q ranged from about 0.8 to 0.9.

  4. 78 FR 63410 - Energy Conservation Program for Consumer Products: Test Procedures for Direct Heating Equipment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ...The U.S. Department of Energy (DOE) proposes to revise its test procedures for direct heating equipment and pool heaters established under the Energy Policy and Conservation Act. This rulemaking will fulfill DOE's statutory obligation to review its test procedures for covered products at least once every seven years. For direct heating equipment, the proposed amendments would add provisions......

  5. Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.

    2005-01-01

    We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

  6. Heat pump systems with direct expansion ground coils

    NASA Astrophysics Data System (ADS)

    Svec, O. J.; Baxter, V. D.

    This paper is a summary of an International research project organized within the framework of the International Energy Agency (IEA), Implementing Agreement on Heat Pumps. This cooperative project, based on a task sharing principle, was proposed by the Canadian team and joined by the national teams of the United States of America, Japan and Austria. The Institute for Research in Construction (IRC) of the National Research Council of Canada (NRCC), has been acting as the Operating Agent for this project, known as Annex XV. The need for this research work is based on the recognition of the state-of-the-art of Ground Source Heat Pump (GSHP) technology, which can simply be described by the following two statements: (1) GSHP technology is the most successful among all renewable technologies in North American and northern European countries; and (2) installation cost of GSHP systems is currently too high for a meaningful worldwide penetration into the heating/cooling market.

  7. Template-directed preparation of two-layer porous NiO film via hydrothermal synthesis for lithium ion batteries

    SciTech Connect

    Chen, Z.; Xiao, A.; Chen, Y.; Zuo, C.; Zhou, S.; Li, L.

    2012-08-15

    Graphical abstract: A two-layer porous NiO film is prepared via hydrothermal synthesis method based on monolayer polystyrene sphere template and shows noticeable Li battery performance with good cycle life and high capacity. Highlights: ► Two-layer porous NiO film is prepared via monolayer polystyrene spheres template. ► NiO film with high capacity as anode material for lithium ion batteries. ► Two-layer porous structure is favorable for fast lithium ion and electron transfer. -- Abstract: A two-layer porous NiO film is prepared by hydrothermal synthesis method through self-assembled monolayer polystyrene spheres template. The substructure of the NiO film is composed of ordered close-packed hollow-sphere array and the superstructure is made up of randomly NiO nanoflakes. The electrochemical properties are measured by galvanostatic charge/discharge tests and cyclic voltammetric analysis (CV). As anode material for lithium ion batteries, the two-layer porous NiO film exhibits high initial coulombic efficiency of 75%, high reversible capacity and rather good cycling performance. The discharge capacity of the two-layer porous NiO film is 501 mAh g{sup −1} at 0.5 C after 50 cycles. The two-layer porous architecture is responsible for the enhancement of electrochemical properties.

  8. Direct formation of new, phase-stable, and photoactive anatase-type Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} solid solution nanoparticles by hydrothermal method

    SciTech Connect

    Hirano, Masanori Ito, Takaharu

    2008-08-04

    A new anatase phase of photoactive Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} (X = 0-0.2) solid solutions was directly formed as nanoparticles from precursor solutions of TiOSO{sub 4}, NbCl{sub 5}, and Sc(NO{sub 3}){sub 3} under mild hydrothermal conditions at 180 deg. C for 5 h using the hydrolysis of urea. With the increase of the content of niobium and scandium from X = 0 to 0.2, the lattice parameters a{sub 0} and c{sub 0}, the crystallite size, and the optical band gap of anatase gradually increased. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The anatase-type Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} (X = 0.05) showed approximately two times and three times as high photocatalytic activity as those of the hydrothermal anatase-type pure TiO{sub 2} and commercially available reference pure TiO{sub 2} (ST-01), respectively. The anatase phase of Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} (X = 0-0.2) existed stably up to 900 deg. C during heat treatment in air. New rutile-type Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} solid solutions are formed through the phase transformation. The starting temperature of anatase-to-rutile phase transformation for Ti{sub 1-2X}Nb{sub X}Sc{sub X}O{sub 2} (X = 0-0.2) solid solutions was delayed but its completing temperature was accelerated.

  9. Synthesis of single-crystal PbS nanorods via a simple hydrothermal process using PEO-PPO-PEO triblock copolymer as a structure-directing agent

    NASA Astrophysics Data System (ADS)

    Bu, Junfu; Nie, Chageng; Liang, Jinxia; Sun, Lan; Xie, Zhaoxiong; Wu, Qi; Lin, Changjian

    2011-03-01

    Single-crystal PbS nanorods were successfully synthesized through a simple hydrothermal route using PEO-PPO-PEO triblock copolymer (P123) as a structure-directing agent. The XRD pattern indicates that the crystal structure of the nanorods is face-centre-cubic rocksalt. A SEM image shows that the nanorods have a diameter of 40-70 nm and a length of 200-600 nm, and both tips exhibit taper-like structures. HRTEM and SAED images reveal the single-crystalline nature of the nanorods with the growth along the lang111rang direction. The experimental results indicated that the P123 concentration and reaction temperature played important roles in controlling the morphology of the PbS nanostructures. The optical property of PbS nanorods was investigated by UV-Vis absorption spectroscopy and the band structure was calculated by the B3LYP hybrid density functional theory.

  10. Thermal stratification in direct gain passive heating systems with variable heating of the floor and one vertical wall

    NASA Astrophysics Data System (ADS)

    Anderson, R. S.; Fisher, E. M.; Bohn, M. S.

    1985-09-01

    This paper reports the results of an experimental study that used a 1/4-scale, water-filled test cell to examine the effect of the natural convection flows created by horizontal and vertical heated surfaces upon thermal stratification in a single-zone enclosure. The study covered the range from pure floor heating to pure wall heating, including various levels of combined floor and wall heating. The presence of a cold window or thermal storage surface was simulated by cooling the wall directly opposite the heated vertical wall. Flow visualization studies were carried out to determine the structure of the flow in the test cell. Correlations are reported for heat transfer, temperature distributions, and thermal stratification as a function of the relative amount of heating that was provided to the floor and wall of the test cell. The results of the study can be used to predict the flow patterns, energy transfer, and levels of thermal stratification that occur in direct gain solar systems that are dominated by natural convection.

  11. Genesis and preservation of a uranium-rich paleozoic epithermal system with a surface expression (Northern Flinders Ranges, South Australia): radiogenic heat driving regional hydrothermal circulation over geological timescales.

    PubMed

    Brugger, Joël; Wülser, Pierre-Alain; Foden, John

    2011-01-01

    The surface expressions of hydrothermal systems are prime targets for astrobiological exploration, and fossil systems on Earth provide an analogue to guide this endeavor. The Paleozoic Mt. Gee-Mt. Painter system (MGPS) in the Northern Flinders Ranges of South Australia is exceptionally well preserved and displays both a subsurface quartz sinter (boiling horizon) and remnants of aerial sinter pools that lie in near-original position. The energy source for the MGPS is not related to volcanism but to radiogenic heat produced by U-Th-K-rich host rocks. This radiogenic heat source drove hydrothermal circulation over a long period of time (hundreds of millions of years, from Permian to present), with peaks in hydrothermal activity during periods of uplift and high water supply. This process is reflected by ongoing hot spring activity along a nearby fault. The exceptional preservation of the MGPS resulted from the lack of proximal volcanism, coupled with tectonics driven by an oscillating far-field stress that resulted in episodic basement uplift. Hydrothermal activity caused the remobilization of U and rare earth elements (REE) in host rocks into (sub)economic concentrations. Radiogenic-heat-driven systems are attractive analogues for environments that can sustain life over geological times; the MGPS preserves evidence of episodic fluid flow for the past ∼300 million years. During periods of reduced hydrothermal activity (e.g., limited water supply, quiet tectonics), radiolytic H(2) production has the potential to support an ecosystem indefinitely. Remote exploration for deposits similar to those at the MGPS systems can be achieved by combining hyperspectral and gamma-ray spectroscopy. © Mary Ann Liebert, Inc.

  12. Hierarchical rutile TiO2 flower cluster-based high efficiency dye-sensitized solar cells via direct hydrothermal growth on conducting substrates.

    PubMed

    Ye, Meidan; Liu, Hsiang-Yu; Lin, Changjian; Lin, Zhiqun

    2013-01-28

    Dye-sensitized solar cells (DSSCs) based on hierarchical rutile TiO(2) flower clusters prepared by a facile, one-pot hydrothermal process exhibit a high efficiency. Complex yet appealing rutile TiO(2) flower films are, for the first time, directly hydrothermally grown on a transparent conducting fluorine-doped tin oxide (FTO) substrate. The thickness and density of as-grown flower clusters can be readily tuned by tailoring growth parameters, such as growth time, the addition of cations of different valence and size, initial concentrations of precursor and cation, growth temperature, and acidity. Notably, the small lattice mismatch between the FTO substrate and rutile TiO(2) renders the epitaxial growth of a compact rutile TiO(2) layer on the FTO glass. Intriguingly, these TiO(2) flower clusters can then be exploited as photoanodes to produce DSSCs, yielding a power conversion efficiency of 2.94% despite their rutile nature, which is further increased to 4.07% upon the TiCl(4) treatment.

  13. Controls on the physics and chemistry of seafloor hydrothermal circulation

    NASA Astrophysics Data System (ADS)

    Schultz, A.; Elderfield, H.

    Low temperature diffuse hydrothermal circulation is a natural consequence of the cooling of the oceanic lithosphere. Diffuse flow is expected to be ubiquitous, and will be present both within mid-ocean ridge crest axial zones of young age (0-1 Ma), and also on the older ridge crest flanks and limbs. If underlying thermal models are correct, hydrothermal circulation should persist for oceanic lithosphere of age 0-65 Ma, and is present over half the total area of the ocean basins. By using numerical models of hydrothermal circulation in cracked permeable media, we show qualitatively how diffuse flow is an intrinsic feature of high temperature axial (0-1 Ma) hydrothermal systems, and is not restricted to older (more than 1 Ma) lithosphere. This is in agreement with our field observations which suggest that in such high temperature vent fields the greatest part of the heat and volume flux is due to lower temperature diffuse flow, rather than high temperature black smoker venting. By combining direct measurements of the physical properties of diffusely flowing effluent within axial hydrothermal systems with concurrent sampling of the chemical properties of that effluent, and by considering also the chemistry of unmixed black smoker endmember fluids from the same hydrothermal systems, the processes of mineral deposition and dissolution can be studied directly. By referring to the present-day lithology of such areas, it is possible to examine the balance between concurrent mineral deposition and dissolution processes, and the retention rate of specific mineral assemblages integrated over the history of the hydrothermal system. Thus details of the episodicity of hydrothermal venting within the system may be revealed. An example of this method of combining a variety of direct measurements of diffuse and high temperature effluent properties is given from the TAG hydrothermal field, Mid-Atlantic Ridge. Long time series observations of the physical properties of diffuse and

  14. The effects of parent-body hydrothermal heating on amino acid abundances in CI-like chondrites

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; Grunsfeld, Sarah; Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

    2014-09-01

    We determined the amino acid abundances and enantiomeric compositions of the Antarctic CI1 carbonaceous chondrites Yamato (Y)-86029 and Y-980115, as well as the Ivuna and Orgueil CI1 carbonaceous chondrites by liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Y-86029 and Y-980115 both show evidence of parent-body heating (500-600 °C) in addition to aqueous alteration, while Ivuna and Orgueil only show evidence for aqueous alteration. In contrast to Ivuna and Orgueil, which each contain ˜70 nmol/g of amino acids in acid-hydrolyzed, water extracts, both heated Yamato CI meteorites contain only low levels of amino acids that were primarily L-enantiomers of proteinogenic amino acids, indicating that they are likely to be terrestrial in origin. Because indigenous amino acids have been found in meteorites that have experienced metamorphic temperatures of >1000 °C with only minimal aqueous alteration, heating alone is not sufficient to explain the lack of amino acids in Y-86029 and Y-980115. Rather, our data suggest that the combination of heating and aqueous alteration has a profound destructive effect on amino acids in meteorites. This finding has implications for the origins of amino acids and other molecules in the early evolution of our solar system.

  15. Seismic identification of along-axis hydrothermal flow on the East Pacific Rise.

    PubMed

    Tolstoy, M; Waldhauser, F; Bohnenstiehl, D R; Weekly, R T; Kim, W-Y

    2008-01-10

    Hydrothermal circulation at the axis of mid-ocean ridges affects the chemistry of the lithosphere and overlying ocean, supports chemosynthetic biological communities and is responsible for significant heat transfer from the lithosphere to the ocean. It is commonly thought that flow in these systems is oriented across the ridge axis, with recharge occurring along off-axis faults, but the structure and scale of hydrothermal systems are usually inferred from thermal and geochemical models constrained by the geophysical setting, rather than direct observations. The presence of microearthquakes may shed light on hydrothermal pathways by revealing zones of thermal cracking where cold sea water extracts heat from hot crustal rocks, as well as regions where magmatic and tectonic stresses create fractures that increase porosity and permeability. Here we show that hypocentres beneath a well-studied hydrothermal vent field on the East Pacific Rise cluster in a vertical pipe-like zone near a small axial discontinuity, and in a band that lies directly above the axial magma chamber. The location of the shallow pipe-like cluster relative to the distribution and temperature of hydrothermal vents along this section of the ridge suggests that hydrothermal recharge may be concentrated there as a consequence of the permeability generated by tectonic fracturing. Furthermore, we interpret the band of seismicity above the magma chamber as a zone of hydrothermal cracking, which suggests that hydrothermal circulation may be strongly aligned along the ridge axis. We conclude that models that suggest that hydrothermal cells are oriented across-axis, with diffuse off-axis recharge zones, may not apply to the fast-spreading East Pacific Rise.

  16. Geothermal direct-heat utilization assistance. Quarterly report, October--December 1996

    SciTech Connect

    1996-12-31

    This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the first quarter of FY-97. It describes 174 contracts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on greenhouse peaking. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

  17. Geothermal direct-heat utilization assistance. Quarterly project progress report, January--March 1994

    SciTech Connect

    Not Available

    1994-05-01

    The Geo-Heat Center provides technical assistance on geothermal direct heat applications to developers, consultants and the public which could include: data and information on low-temperature (< 1500 C) resources, space and district heating, geothermal heat pumps, greenhouses, aquaculture, industrial processes and other technologies. This assistance could include preliminary engineering feasibility studies, review of direct-use project plans, assistance in project material and equipment selection, analysis and solutions of project operating problems, and information on resources and utilization. The following are brief descriptions of technical assistance provided during the second quarter of the program.

  18. Induction heating vs conventional heating for the hydrothermal treatment of nitinol and its subsequent 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate coating by surface-initiated atom transfer radical polymerization.

    PubMed

    Devillers, S; Barthélémy, B; Delhalle, J; Mekhalif, Z

    2011-10-01

    Nitinol is an alloy of great interest in general and especially in the biomedical field where many researches are aimed to improve both its corrosion resistance and its biocompatibility. In this work, we report on the advantage of an induction heating treatment in pure water compared to a conventional hydrothermal procedure. Both treatments lead to a hydroxylation of the surface, a decrease of the nickel amount in the outer part of the oxide layer, and a drastically decreased corrosion current density. However, the amount of surface hydroxyl groups is higher in the case of the induction heating treatment, which in turn leads to a denser grafting of atom transfer radical polymerization initiators and ultimately to a thicker 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC) polymer layer than in the case of conventional heating treatments. X-ray photoelectron spectroscopy (XPS), static contact angle, and polarization curves measurements as well as scanning electron microscopy (SEM) have been used to characterize the obtained modified surfaces. © 2011 American Chemical Society

  19. Hydrothermal processes at seafloor spreading centers,

    SciTech Connect

    Rona, P.A.; Bostrom, K.; Laubier, L.; Smith, K.L.

    1983-01-01

    This book examines research on the description and interpretation of hydrothermal and associated phenomena at seafloor spreading centers. An interdisciplinary overview of the subject is presented, including geological, geophysical, geochemical, and biological discoveries. The implications of the discoveries for understanding the earth's heat transfer, geochemical mass balances and cycles, mineralization, and biological adaptation are discussed. Topics considered include geologic setting (e.g., the four dimensions of the spreading axis, geological processes of the mid-ocean ridge), hydrothermal convection (e.g., oxygen and hydrogen isotope studies, the basic physics of water penetration into hot rock), Iceland and oceanic ridges (e.g., chemical evidence from Icelandic geothermal systems, the physical environment of hydrothermal systems), mass balances and cycles (e.g., reduced gases and bacteria in hydrothermal fluids, the effects of hydrothermal activity on sedimentary organic matter), ferromanganese deposits, hydrothermal mineralization, and the biology of hydrothermal vents.

  20. Direct contact liquid-liquid heat exchanger for solar-heated and cooled buildings

    NASA Astrophysics Data System (ADS)

    Karaki, S.; Brothers, P.

    1980-06-01

    The procedure used was to obtain experimental performance data from a solar system using a DCLLHE for both heating and cooling functions, develop a simulation model for the system, validate the model using the data, apply the model in five different climatic regions of the country for a complete year, and estimate the life-cycle cost of the system for each application. The results are compared to a conventional solar system, using a standard shell-and-tube heat exchanger.

  1. Comparative catalytic reduction of 4-nitrophenol by polyacrylamide-gold nanocomposite synthesized by hydrothermal autoclaving and conventional heating routes

    NASA Astrophysics Data System (ADS)

    Salaheldin, Hosam I.

    2017-12-01

    Gold nanoparticles (AuNPs) in polymeric polyacrylamide (PAAm) matrix were synthesized using conventional heating and autoclaving thermal techniques. The synthesized Au/PAAm nanocomposite was characterized using UV-vis spectroscopy and high-resolution transmission electron microscopy. The size of the synthesized particles was approximately 6.37 nm and 8.19 nm with the conventional heating and autoclaving thermal techniques, respectively. Electron diffraction x-ray spectroscopy and the Fourier transformation infrared spectroscopy were used for the composition and elemental studies, which confirmed that the Au metallic atoms were synthesized and embedded within a PAAm matrix via a coordination bond between the carbonyl (-CONH2) group and the metallic NPs. X-ray diffraction confirmed the crystalline nature of the fabricated AuNPs with face centered cubic of nanocrystals. The catalytic activity of the as-prepared Au/PAAm nanocomposite for the reduction of 4-nitrophenol to 4-aminophenol was studied in the presence of sodium borohydrate. The synthesized AuNPs had an effective catalytic activity; the smaller NPs synthesized NPs with the conventional heating technique had a higher reaction kinetic rate in comparation with those synthesized with the autoclaving technique. Therefore, the Au/PAAm nanocomposite can be widely used as an eco-friendly, non-toxic, a fast and cost-effective product to remove versatile organic pollutants such as aromatic nitro compounds.

  2. Enceladus: Starting Hydrothermal Activity

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

  3. Enceladus: Starting Hydrothermal Activity

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

  4. Regenerative heat exchanger with a periodic change in the airflow direction for room ventilation

    NASA Astrophysics Data System (ADS)

    Nizovtsev, M. I.; Borodulin, V. Yu.; Letushko, V. N.

    2015-11-01

    This paper presents the results of experimental research of heat transfer in air-to-air regenerative heat exchanger with periodic change of flow direction. The temperatures of the airflow and the material of regenerative packing in different sections have been obtained. The temperature efficiency of the heat exchanger has been determined at different flow rates. The developed mathematical model of the regenerative heat exchanger is described. It is shown that the model fairly well describes the experimental results. Based on numerical studies the dependence of thermal efficiency of the heat exchanger on the airflow rate is determined. It is shown that changing the ratio of the oppositely directed flow rates, it is possible to regulate the temperature of the air flowing into the room. The possibility of using the model for optimizing the operational and design parameters of heat exchanger is demonstrated.

  5. Geothermal technology transfer for direct heat applications: Final report, 1983--1988

    SciTech Connect

    Lienau, P.J.; Culver, G.

    1988-01-01

    This report describes a geothermal technology transfer program, performed by Oregon Institute of Technology's Geo-Heat Center, used to aid in the development of geothermal energy for direct heat applications. It provides a summary of 88 technical assistance projects performed in 10 states for space heating, district heating, green-houses, aquaculture, industrial processing, small scale binary electric power generation and heat pump applications. It describes an inventory compiled for over 100 direct heat projects that contains information on project site, resource and engineering data. An overview of information services is provided to users of the program which includes; advisory, referrals, literature distribution, geothermal technology library, quarterly Bulletin, training programs, presentations and tours, and reporting of activities for the USDOE Geothermal Progress Monitor.

  6. Basic Research on a Latent Heat Thermal Energy Storage by Direct Contact Melting and Soldification

    NASA Astrophysics Data System (ADS)

    Saito, Akihiro; Saito, Akio; Utaka, Yoshio; Okuda, Kenichi; Katayama, Kozo

    A basic experimental research on a latent heat thermal energy storage system , utilizing a simple and effective heat exchange mechanism by a direct contact between the phase change material (PCM) and the heat transfer fluid (HTF), was shown. Discharging experiments on direct contact latent heat thermal energy reservoir using n-Eicosane as the PCM and water as the HTF, were performed, based on the conditions obtained in previous report. Then, operating conditions for suitable discharging process were searched from the experimental results (outlet water temperature response and local temperature response in the reservoir). Moreover, solidification mechanisms of PCM, which had been presumed in previous report, were confirmed from these experimental results, and the simple physical model on direct contact heat exchange in the reservoir was proposed. Then, the outlet water temperature response by this model was compared with the experimental results.

  7. Basic Research on a Latent Heat Thermal Energy Storage by Direct Contact Melting and Solidification

    NASA Astrophysics Data System (ADS)

    Saito, Akihiro; Saito, Akio; Utaka, Yoshio; Okuda, Kenichi; Katayama, Kozo

    A basic experimental research on a latent heat thermal energy storage system, utilizing a simple and effective heat exchange mechanism by a direct contact between the phase change material (PCM) and the heat transfer fluid (HTF) , was shown. In this report, authors proposed the direct contact latent heat thermal energy storage system using industrial paraffin and n-Eicosane as the PCM, and using water as the HTF. The observations were performed concerning the HTF separation from the solid PCM in the solidification process (heat discharging process), and concerning the water pass formation within the solid PCM. Then, it was confirmed that the system worked effectively by using n-Eicosane as the PCM. And authors discussed the mechanism of direct contact solidification process from experimental results.

  8. Direct synthesis of Al-SBA-15 containing aluminosilicate species plugs in an acid-free medium and structural adjustment by hydrothermal post-treatment

    SciTech Connect

    Shi, Lei; Xu, Yan; Zhang, Na; Lin, Sen; Li, Xiangping; Guo, Peng; Li, Xuebing

    2013-07-15

    A series of Al-SBA-15 with controllable aluminosilicate plug structures inside straight mesopores has been hydrothermally synthesized in a one-step synthesis in an environmentally friendly acid-free medium, using triblock copolymer Pluronic P123 as a structure-directing agent, water as solvent, tetraethyl orthosilicate (TEOS) and aluminum nitrate (Al(NO){sub 3}·9H{sub 2}O) as silica and aluminum sources, respectively. The effects of the P123/Si molar ratio in the initial solution and aging temperature on the structural properties of the resulting materials were investigated by powder X-ray diffraction (XRD), nitrogen adsorption–desorption at 77 K, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric (TG), FT-IR spectra and inductively coupled plasma (ICP) analyses. The nature of the Al species and the acidity of the resultant samples were studied by solid state {sup 27}Al MAS NMR and pyridine adsorption measurements. The specific surface area (935–755 m{sup 2}g{sup −1}), pore volume (1.03–0.56 cm{sup 3}g{sup −1}) and especially the concentration and distribution of open type mesopores (0–68% to the total pores) of the synthesized Al-SBA-15 can be controlled by a simple adjustment of the P123/Si molar ratio in the initial solution. Moreover, increasing the aging temperature higher than 363 K can remarkably decrease the formation of plug structures to obtain “open” form mesopores. The observation by TEM of alternate defined gray and white areas inside the mesopores gives the strong evidence of isolated microporous aluminosilicate plugs inside the channels. In addition, a moderate hydrothermal post-treatment can finely modify the mesostructures through the partial or complete dissolution of the aluminosilicate plugs. - Graphical abstract: The plugs-containing structures can be interpreted as the distribution of individual isolated plugs along the mesoporous channel. - Highlights: • Al-SBA-15 with controllable

  9. Economic assessment of geothermal direct heat technology: A review of five DOE demonstration projects

    SciTech Connect

    Hederman, William F. Jr.; Cohen, Laura A.

    1981-06-01

    In this report the cost of using low temperature geothermal energy resources for direct heating applications is compared to the costs associated with conventional heating fuels. The projects compared all involved replacing conventional fuels (e.g., natural gas and fuel oils) with geothermal energy in existing heating systems. The cost of using geothermal energy in existing systems was also compared with the cost of new coal-fired equipment.

  10. Effect of the magnetic field direction on forced convection heat transfer enhancements in ferrofluids

    NASA Astrophysics Data System (ADS)

    Cherief, Wahid; Avenas, Yvan; Ferrouillat, Sébastien; Kedous-Lebouc, Afef; Jossic, Laurent; Berard, Jean; Petit, Mickael

    2015-07-01

    Applying a magnetic field on a ferrofluid flow induces a large increase of the convective heat transfer coefficient. In this paper, the thermal-hydraulic behaviors of two commercial ferrofluids are compared. The variations of both the pressure drop and the heat transfer coefficient due to the magnetic field are measured in the following conditions: square duct, laminar flow and uniform wall heat flux. The square section with two insulated walls allows for the characterization of the effect of the magnetic field direction. The experimental results show that the heat transfer is better enhanced when the magnetic field is perpendicular to the heat flux. In the best case, the local heat transfer coefficient increase is about 75%. On the contrary, another experimental setup shows no enhancement of thermal conductivity when the magnetic field is perpendicular to the heat flux. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  11. Contribution of direct heating, thermal conduction and perfusion during radiofrequency and microwave ablation.

    PubMed

    Schramm, W; Yang, D; Haemmerich, D

    2006-01-01

    Heat based tumor ablation methods such as radiofrequency (RF) and microwave (MW) ablation are increasingly accepted treatment methods for tumors not treatable by traditional surgery. Typically, an interstitial applicator is introduced under imaging guidance into the tumor, and tissue is destroyed by heating to above approximately 50 degrees C, with maximum tissue temperatures over 100 degrees C. Since high thermal gradients occur during the procedure, thermal conduction contributes significantly towards tissue heating. We created finite element method (FEM) computer models of RF and MW applicators, and determined the thermal conduction term, the resistive (for RF) or dielectric (for MW) loss term, and perfusion term. We integrated these terms over the heating period to obtain relative contribution towards tissue temperature rise (in degrees C) as a function of distance from the applicator. We performed simulations without and with perfusion, where perfusion was assumed to stop above 50 degrees C. During the first 6 minutes, direct heating by RF and MW were dominating throughout the tissue. Over the treatment period (12 min for RF, and 6 min for MW), thermal conduction was dominating at distances between than 12 and 19 mm from the RF electrode, while for MW ablation direct heating dominated everywhere. Even though thermal conduction significantly contributes towards tissue heating during ablative therapies, direct heating by RF or MW is dominating throughout most of the tissue volume. Tissue cooling due to perfusion is more significant during RF heating, in part due to the longer treatment times.

  12. High-resolution near-bottom vector magnetic anomalies over Raven Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; Johnson, H. Paul; Salmi, Marie S.; Hutnak, Michael

    2014-10-01

    High-resolution, near-bottom vector magnetic data were collected by remotely operated vehicle Jason over the Raven hydrothermal vent field (47°57.3'N 129°5.75'W) located north of Main Endeavour vent field on the Endeavour segment of the Juan de Fuca Ridge. The survey was part of a comprehensive heat flow study of the Raven site using innovative thermal blanket technology to map the heat flux and crustal fluid pathways around a solitary hydrothermal vent field. Raven hydrothermal activity is presently located along the western axial valley wall, while additional inactive hydrothermal deposits are found to the NW on the upper rift valley wall. Magnetic inversion results show discrete areas of reduced magnetization associated with both active and inactive hydrothermal vent deposits that also show high conductive heat flow. Higher spatial variability in the heat flow patterns compared to the magnetization is consistent with the heat flow reflecting the currently active but ephemeral thermal environment of fluid flow, while crustal magnetization is representative of the static time-averaged effect of hydrothermal alteration. A general NW to SE trend in reduced magnetization across the Raven area correlates closely with the distribution of hydrothermal deposits and heat flux patterns and suggests that the fluid circulation system at depth is likely controlled by local crustal structure and magma chamber geometry. Magnetic gradient tensor components computed from vector magnetic data improve the resolution of the magnetic anomaly source and indicate that the hydrothermally altered zone directly beneath the Raven site is approximately 15 × 106 m3 in volume.

  13. Geology and hydrothermal evolution of the Mothra Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Glickson, Deborah A.; Kelley, Deborah S.; Delaney, John R.

    2007-06-01

    Detailed characterization of the Mothra Hydrothermal Field, the most southern and spatially extensive field on the Endeavour Segment of the Juan de Fuca Ridge, provides new insights into its geologic and hydrothermal development. Meter-scale bathymetry, side-scan sonar imagery, and direct dive observations show that Mothra is composed of six actively venting sulfide clusters spaced 40-200 m apart. Chimneys within each cluster have similar morphology and venting characteristics, and all clusters host a combination of active and extinct sulfide structures. Black smoker chimneys venting fluids above 300°C are rare, while more common lower-temperature, diffusely venting chimneys support dense colonies of macrofauna and bacterial mat. Hydrothermal sediment and extinct sulfide debris cover 10-15 m of the seafloor surrounding each vent cluster, obscuring the underlying basaltic substrate of light to moderately sedimented pillow, lobate, sheet, and chaotic flows, basalt talus, and collapse terrain. Extinct sulfide chimneys and debris between the clusters indicate that hydrothermal flow was once more widespread and that it has shifted spatially over time. The most prominent structural features in the axial valley at Mothra are regional (020°) trending faults and fissures and north-south trending collapse basins. The location of actively venting clusters within the field is controlled by (1) localization of fluid upflow along the western boundary fault zone, and diversion of these fluids by antithetic faults to feed vent clusters near the western valley wall, and (2) tapping of residual magmatic heat in the central part of the axial valley, which drives flow beneath vent clusters directly adjacent to the collapse basins 70-90 m east of the western valley wall. These processes form the basis for a model of axial valley and hydrothermal system development at Mothra, in which the field is initiated by an eruptive-diking episode and sustained through intense microseismicity

  14. Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

    NASA Astrophysics Data System (ADS)

    Zhao, Qinfu; Wang, Tianyi; Wang, Jing; Zheng, Li; Jiang, Tongying; Cheng, Gang; Wang, Siling

    2011-09-01

    In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.

  15. Mechanisms of direct detonation initiation via thermal explosion of radiatively heated gas-particles layer

    NASA Astrophysics Data System (ADS)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    Conceptual approach of detonation wave direct initiation by external radiative heating of microparticles locally suspended in flammable gaseous mixture is proposed. Combustion waves and detonation initiation mechanisms in the congestion regions of microparticles heated by radiation are studied numerically. Necessary criteria on geometrical scales of gas-particles layer and spatial uniformity of particles distribution for successful detonation initiation are formulated.

  16. COVIS Detects Interconnections Between Atmospheric, Oceanic and Geologic systems at a Deep Sea Hydrothermal Vent

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Xu, G.; Lee, R.

    2015-12-01

    COVIS (Cabled Observatory Vent Imaging Sonar) is an innovative sonar system designed to quantitatively monitor focused and diffuse flows from deep-sea hydrothermal vent clusters. From 9/2010 to 9/2015, COVIS was connected to the NEPTUNE observatory at Grotto vent in the Main Endeavour Field, JdFR. COVIS monitored plumes and diffuse discharge by transmitting high-frequency (200-400 kHz), pulsed acoustic waves and recording the backscattered signals to yield time series of plume heat and volume transports, plume bending, and diffuse flow area. Temporal variations indicate the rate of hydrothermal plume mixing with the ambient seawater increases with the magnitude of ocean currents. Such current-driven entrainment links the dynamics of a deep-sea hydrothermal plume with oceanic and atmospheric processes. We estimate the direction and relative amplitude of the local bottom currents from the bending angles of the plumes. A comparison with currents from an ADCP (~80 m south of Grotto) reveals significant complexity in the mean bottom flow structure within a hydrothermal vent field. Diffuse flow area, temperature, and faunal densities vary periodically reflecting some combination of tidal pressure and current interactions. The heat transport time series suggests the heat source driving the plume remained relatively steady for 41 months. Local seismic data reveals that increased heat transport in 2000 followed seismic events in 1999 and 2000 and the steady heat flux from 10/2011 to 2/2015 coincided with quiescent seismicity. Such a correlation points to the close linkage of a seafloor hydrothermal system with geological processes. These findings demonstrate the intimate interconnections of seafloor hydrothermal systems with processes spanning the Earth's interior to the sea surface. Further, they (and the time-series acquired by COVIS) testify to the effectiveness and robustness of employing an acoustic-imaging sonar for long-term monitoring of a seafloor hydrothermal

  17. Skin and muscle components of forearm blood flow in directly heated resting man.

    NASA Technical Reports Server (NTRS)

    Detry, J.-M. R.; Brengelmann, G. L.; Rowell, L. B.; Wyss, C.

    1972-01-01

    Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

  18. Skin and muscle components of forearm blood flow in directly heated resting man.

    NASA Technical Reports Server (NTRS)

    Detry, J.-M. R.; Brengelmann, G. L.; Rowell, L. B.; Wyss, C.

    1972-01-01

    Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

  19. A comparison of microwave versus direct solar heating for lunar brick production

    NASA Technical Reports Server (NTRS)

    Yankee, S. J.; Strenski, D. G.; Pletka, B. J.; Patil, D. S.; Mutsuddy, B. C.

    1990-01-01

    Two processing techniques considered suitable for producing bricks from lunar regolith are examined: direct solar heating and microwave heating. An analysis was performed to compare the two processes in terms of the amount of power and time required to fabricate bricks of various sizes. Microwave heating was shown to be significantly faster than solar heating for rapid production of realistic-size bricks. However, the relative simplicity of the solar collector(s) used for the solar furnace compared to the equipment necessary for microwave generation may present an economic tradeoff.

  20. Geothermal direct-heat utilization assistance. Quarterly report, January - March 1997

    SciTech Connect

    Lienau, P.

    1997-04-01

    This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the second quarter of FY-97. It describes 176 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on well pumping in commercial groundwater heat pump systems. A memorandum of understanding between the GHC and EIA is described. Work accomplishments on the Guidebook are discussed. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

  1. Geothermal direct-heat utilization assistance. Quarterly project progress report, July--September 1997

    SciTech Connect

    1997-10-01

    This report summarizes geothermal technical assistance, R and D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the fourth quarter of FY-97 (July--September 1997). It describes 213 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include requests for general information including maps, geothermal heat pumps, resource and well data, space heating and cooling, greenhouses, acquaculture, equipment, district heating, resorts and spas, and industrial applications. Research activities include the completion of a Comprehensive Greenhouse Developer Package. Work accomplished on the revision of the Geothermal Direct Use Engineering and Design Guidebook are discussed. Outreach activities include the publication of the Quarterly Bulletin (Vol. 18, No. 3), dissemination of information mainly through mailings of publications, geothermal library acquisition and use, participation in workshops, short courses, and technical meetings by the staff, and progress monitor reports on geothermal activities.

  2. Direct synthesis of Al-SBA-15 containing aluminosilicate species plugs in an acid-free medium and structural adjustment by hydrothermal post-treatment

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Xu, Yan; Zhang, Na; Lin, Sen; Li, Xiangping; Guo, Peng; Li, Xuebing

    2013-07-01

    A series of Al-SBA-15 with controllable aluminosilicate plug structures inside straight mesopores has been hydrothermally synthesized in a one-step synthesis in an environmentally friendly acid-free medium, using triblock copolymer Pluronic P123 as a structure-directing agent, water as solvent, tetraethyl orthosilicate (TEOS) and aluminum nitrate (Al(NO)3·9H2O) as silica and aluminum sources, respectively. The effects of the P123/Si molar ratio in the initial solution and aging temperature on the structural properties of the resulting materials were investigated by powder X-ray diffraction (XRD), nitrogen adsorption-desorption at 77 K, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric (TG), FT-IR spectra and inductively coupled plasma (ICP) analyses. The nature of the Al species and the acidity of the resultant samples were studied by solid state 27Al MAS NMR and pyridine adsorption measurements. The specific surface area (935-755 m2g-1), pore volume (1.03-0.56 cm3g-1) and especially the concentration and distribution of open type mesopores (0-68% to the total pores) of the synthesized Al-SBA-15 can be controlled by a simple adjustment of the P123/Si molar ratio in the initial solution. Moreover, increasing the aging temperature higher than 363 K can remarkably decrease the formation of plug structures to obtain “open” form mesopores. The observation by TEM of alternate defined gray and white areas inside the mesopores gives the strong evidence of isolated microporous aluminosilicate plugs inside the channels. In addition, a moderate hydrothermal post-treatment can finely modify the mesostructures through the partial or complete dissolution of the aluminosilicate plugs.

  3. Experimental analysis of direct-expansion ground-coupled heat pump systems

    NASA Astrophysics Data System (ADS)

    Mei, V. C.; Baxter, V. D.

    1991-09-01

    Direct-expansion ground-coil-coupled (DXGC) heat pump systems have certain energy efficiency advantages over conventional ground-coupled heat pump (GCHP) systems. Principal among these advantages are that the secondary heat transfer fluid heat exchanger and circulating pump are eliminated. While the DXGC concept can produce higher efficiencies, it also produces more system design and environmental problems (e.g., compressor starting, oil return, possible ground pollution, and more refrigerant charging). Furthermore, general design guidelines for DXGC systems are not well documented. A two-pronged approach was adopted for this study: (1) a literature survey, and (2) a laboratory study of a DXGC heat pump system with R-22 as the refrigerant, for both heating and cooling mode tests done in parallel and series tube connections. The results of each task are described in this paper. A set of general design guidelines was derived from the test results and is also presented.

  4. Sustainability and dynamics of outcrop-to-outcrop hydrothermal circulation.

    PubMed

    Winslow, Dustin M; Fisher, Andrew T

    2015-06-26

    Most seafloor hydrothermal circulation occurs far from the magmatic influence of mid-ocean ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge flanks. Here we create three-dimensional simulations of ridge-flank hydrothermal circulation, flowing between and through seamounts, to determine what controls hydrogeological sustainability, flow rate and preferred flow direction in these systems. We find that sustaining flow between outcrops that penetrate less-permeable sediment depends on a contrast in transmittance (the product of outcrop permeability and the area of outcrop exposure) between recharging and discharging sites, with discharge favoured through less-transmissive outcrops. Many simulations include local discharge through outcrops at the recharge end of an outcrop-to-outcrop system. Both of these characteristics are observed in the field. In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which may help to explain how so much lithospheric heat is extracted globally by this process.

  5. Sustainability and dynamics of outcrop-to-outcrop hydrothermal circulation

    PubMed Central

    Winslow, Dustin M.; Fisher, Andrew T.

    2015-01-01

    Most seafloor hydrothermal circulation occurs far from the magmatic influence of mid-ocean ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge flanks. Here we create three-dimensional simulations of ridge–flank hydrothermal circulation, flowing between and through seamounts, to determine what controls hydrogeological sustainability, flow rate and preferred flow direction in these systems. We find that sustaining flow between outcrops that penetrate less-permeable sediment depends on a contrast in transmittance (the product of outcrop permeability and the area of outcrop exposure) between recharging and discharging sites, with discharge favoured through less-transmissive outcrops. Many simulations include local discharge through outcrops at the recharge end of an outcrop-to-outcrop system. Both of these characteristics are observed in the field. In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which may help to explain how so much lithospheric heat is extracted globally by this process. PMID:26113260

  6. A comparison of direct heating during radiofrequency and microwave ablation in ex vivo liver

    PubMed Central

    Andreano, Anita; Brace, Christopher L

    2012-01-01

    Purpose To determine the magnitude and spatial distribution of temperature elevations when using 480 kHz RF and 2.45 GHz microwave energy in ex vivo liver models. Materials and Methods A total of sixty heating cycles (20 s at 90 W) were performed in normal, RF ablated and microwave ablated liver tissues (n=10 RF and n=10 microwave in each tissue type). Heating cycles were performed using a 480 kHz generator and 3 cm cooled-tip electrode (RF) or a 2.45 GHz generator and 14-gauge monopole (microwave) and designed to isolate direct heating from each energy type. Tissue temperatures were measured using fiberoptic thermosensors 5, 10 and 15 mm radially from the ablation applicator at the depth of maximal heating. Power delivered, sensor location, heating rates and maximal temperatures were compared using mixed effects regression models. Results No significant differences were noted in mean power delivered or thermosensor locations between RF and microwave heating groups (P>0.05). Microwaves produced significantly more rapid heating than RF at 5, 10 and 15mm in normal tissue (3.0 vs. 0.73, 0.85 vs. 0.21 and 0.17 vs. 0.09 °C/s; P<.05); and at 5 and 10mm in ablated tissues (2.3 ± 1.4 vs. 0.7 ± 0.3, 0.5 ± 0.3 vs. 0.2 ± 0.0 C/s, P<.05). The radial depth of heating was approximately 5mm greater for microwaves than RF. Conclusions Direct heating obtained with 2.45 GHz microwave energy using a single needle-like applicator is faster and covers a larger volume of tissue than 480 kHz RF energy. Keywords: microwave ablation, direct heating, thermal ablation PMID:22572764

  7. The effect of direct heating and cooling of heat regulation centers on body temperature

    NASA Technical Reports Server (NTRS)

    Barbour, H. G.

    1978-01-01

    Experiments were done on 28 rabbits in which puncture instruments were left in the brain for 1-2 days until the calori-puncture hyperthermia had passed and the body temperature was again normal. The instrument remaining in the brain was then used as a galvanic electrode and a second fever was produced, this time due to the electrical stimulus. It was concluded that heat is a centrally acting antipyretic and that cold is a centrally acting stimulus which produces hyperpyrexia cold-induced fever.

  8. Comparison of Direct Solar Energy to Resistance Heating for Carbothermal Reduction of Regolith

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.; Gustafson, Robert J.

    2011-01-01

    A comparison of two methods of delivering thermal energy to regolith for the carbo thermal reduction process has been performed. The comparison concludes that electrical resistance heating is superior to direct solar energy via solar concentrators for the following reasons: (1) the resistance heating method can process approximately 12 times as much regolith using the same amount of thermal energy as the direct solar energy method because of superior thermal insulation; (2) the resistance heating method is more adaptable to nearer-term robotic exploration precursor missions because it does not require a solar concentrator system; (3) crucible-based methods are more easily adapted to separation of iron metal and glass by-products than direct solar energy because the melt can be poured directly after processing instead of being remelted; and (4) even with projected improvements in the mass of solar concentrators, projected photovoltaic system masses are expected to be even lower.

  9. The computer model Hydrotherm, a three-dimensional finite-difference model to simulate ground-water flow and heat transport in the temperature range of 0 to 1,200 degrees C

    USGS Publications Warehouse

    Hayba, D.O.; Ingebritsen, S.E.

    1994-01-01

    Quantitative modeling of the deep parts of magmatic- hydrothermal systems has been limited by the lack of publicly available, documented computer models for multiphase, high-temperature flow. This report documents HYDROTHERM, a finite-difference model for three-dimensional, multiphase flow of pure water and heat over a temperature range of 0 to 1,200 degrees Celsius and a pressure range of 0.5 *0 10,000 bars.HYDROTHEP*M is an extension of multiphase geothermal models developed by the U.S. Geological Survey in the 1970's. It solves numerical approximations to mass- and energy-balance equations that are posed in terms of pressure and enthalpy. Major assumptions are that the rock matrix can be treated as a porous medium; that water and rock are in thermal equilibrium; and that capillary pressure is negligible.

  10. Analytical model of an irrigated packed-bed direct-contact heat exchanger at high temperature

    SciTech Connect

    Bohn, M S

    1986-11-01

    This paper presents an analytical model of direct-contact heat exchange (DCHX) in an irrigated packed bed at high temperatures. The specific application is heat exchange between molten salt and air where the molten salt is a sensible heat storage medium and high temperature air is required for an end process. The model defines several heat transfer mechanisms between the three components in the bed - the liquid, the gas, and the packing. It also includes the effect of conduction in the packing. Correlations found in the literature are used to calculate the associated heat transfer coefficients. The model is restricted to liquids that wet the packing material and to gas/liquid flow rates below the loading point. Three dimensionless equations describe the heat balance between the three bed components. The resulting dimensionless parameters reveal that for commercial DCHX systems, radiation heat transfer is unimportant relative to the convective heat transfer, which is consistent with previous experimental results for air/mercury and nitrogen/molten lead systems. The model also predicts volumetric heat transfer coefficients of about 10,000 W/m/sup 3/K, which is consistent with experimental work.

  11. Stability analysis of direct contact heat exchangers subject to system perturbations. Final report, Task 2

    SciTech Connect

    Jacobs, H.R.

    1985-01-01

    This report includes a project summary, copies of two papers resulting from the work and the Ph.D. Dissertation of Dr. Mehdi Golafshani entitled, ''Stability of a Direct Contact Heat Exchanger''. Specifically, the work deals with the operational stability of a spray column type heat exchanger subject to disturbances typical of those which can occur for geothermal applications. A computer program was developed to solve the one-dimensional transient two-phase flow problem and it was applied to the design of a spray column. The operation and design of the East Mesa 500kW/sub e/ direct contactor was assessed. It is shown that the heat transfer is governed by the internal resistance of the dispersed phase. In fact, the performance is well-represented by diffusion of heat within the drops. 5 refs.

  12. Heat waves and morbidity: current knowledge and further direction-a comprehensive literature review.

    PubMed

    Li, Mengmeng; Gu, Shaohua; Bi, Peng; Yang, Jun; Liu, Qiyong

    2015-05-18

    In the past few decades, several devastating heat wave events have significantly challenged public health. As these events are projected to increase in both severity and frequency in the future, it is important to assess the relationship between heat waves and the health indicators that can be used in the early warning systems to guide the public health response. Yet there is a knowledge gap in the impact of heat waves on morbidity. In this study, a comprehensive review was conducted to assess the relationship between heat waves and different morbidity indicators, and to identify the vulnerable populations. The PubMed and ScienceDirect database were used to retrieve published literature in English from 1985 to 2014 on the relationship between heat waves and morbidity, and the following MeSH terms and keywords were used: heat wave, heat wave, morbidity, hospital admission, hospitalization, emergency call, emergency medical services, and outpatient visit. Thirty-three studies were included in the final analysis. Most studies found a short-term negative health impact of heat waves on morbidity. The elderly, children, and males were more vulnerable during heat waves, and the medical care demand increased for those with existing chronic diseases. Some social factors, such as lower socioeconomic status, can contribute to heat-susceptibility. In terms of study methods and heat wave definitions, there remain inconsistencies and uncertainties. Relevant policies and guidelines need to be developed to protect vulnerable populations. Morbidity indicators should be adopted in heat wave early warning systems in order to guide the effective implementation of public health actions.

  13. Heat Waves and Morbidity: Current Knowledge and Further Direction-A Comprehensive Literature Review

    PubMed Central

    Li, Mengmeng; Gu, Shaohua; Bi, Peng; Yang, Jun; Liu, Qiyong

    2015-01-01

    In the past few decades, several devastating heat wave events have significantly challenged public health. As these events are projected to increase in both severity and frequency in the future, it is important to assess the relationship between heat waves and the health indicators that can be used in the early warning systems to guide the public health response. Yet there is a knowledge gap in the impact of heat waves on morbidity. In this study, a comprehensive review was conducted to assess the relationship between heat waves and different morbidity indicators, and to identify the vulnerable populations. The PubMed and ScienceDirect database were used to retrieve published literature in English from 1985 to 2014 on the relationship between heat waves and morbidity, and the following MeSH terms and keywords were used: heat wave, heat wave, morbidity, hospital admission, hospitalization, emergency call, emergency medical services, and outpatient visit. Thirty-three studies were included in the final analysis. Most studies found a short-term negative health impact of heat waves on morbidity. The elderly, children, and males were more vulnerable during heat waves, and the medical care demand increased for those with existing chronic diseases. Some social factors, such as lower socioeconomic status, can contribute to heat-susceptibility. In terms of study methods and heat wave definitions, there remain inconsistencies and uncertainties. Relevant policies and guidelines need to be developed to protect vulnerable populations. Morbidity indicators should be adopted in heat wave early warning systems in order to guide the effective implementation of public health actions. PMID:25993103

  14. Development of a Direct Contact Heat Exchanger, Phase 1 Study Report

    NASA Technical Reports Server (NTRS)

    Manvi, R.

    1978-01-01

    Electric power generation from geothermal brine requires, first, bringing the hot brine to the surface and then converting the heat to electric power. Binary conversion schemes were proposed, with the heat transfer between the brine and the working organic fluid taking place in a conventional tube and shell heat exchanger. If the brine is heavily laden with dissolved solids, however, solids buildup on the heat exchanger surfaces leads to a considerable degree of fouling and an accompanying drop in performance is experienced. A possible solution to this problem is the use of a direct contact exchanger with the secondary fluid power cycle. The proposed concept involves the formation of fluid sheets and bells as heat angles. Results of a study concerning the fluid mechanics of such surfaces are given.

  15. Apparatus development for measuring heat flux in a direct coal-liquefaction preheater

    NASA Astrophysics Data System (ADS)

    Kornosky, R. M.; Perlmutter, M.; Fuchs, W.; Ruether, J. A.

    1982-04-01

    A device is evaluated for determining heat flux in a direct coal liquefaction preheater. The heat fluxmeter determines heat flux from measurements of temperature difference across the preheater tube wall at a given plane perpendicular to the tube axis. Six fluxmeters were installed in a 5.08 m length of nominal 1 1/2 inch diameter, schedule XX pipe enclosed in stacked electric furnaces. Heat flux to a heat transfer fluid flowing through the pipe was measured and compared to values predicted by the fluxmeters. Fair agreement was observed, and the method can be used as an empirical calibration procedure for fluxmeters. A number of apparatus improvements were identified that will be incorporated in the planned experimental program.

  16. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  17. The direct heat measurement of mechanical energy storage metal-organic frameworks.

    PubMed

    Rodriguez, Julien; Beurroies, Isabelle; Loiseau, Thierry; Denoyel, Renaud; Llewellyn, Philip L

    2015-04-07

    In any process, the heat exchanged is an essential property required in its development. Whilst the work related to structural transitions of some flexible metal-organic frameworks (MOFs) has been quantified and linked with potential applications such as molecular springs or shock absorbers, the heat related to such transitions has never been directly measured. This has now been carried out with MIL-53(Al) using specifically devised calorimetry experiments. We project the importance of these heats in devices such as molecular springs or dampers.

  18. Description and operation of Haakon School geothermal-heating system

    SciTech Connect

    Childs, F.W.; Kirol, L.D.; Sanders, R.D.; McLatchy, M.J.

    1983-10-01

    To encourage the development of hydrothermal energy, twenty-three demonstration projects were funded. The Haakon School project is one of twelve such projects. The geothermal direct-use heating system at the Haakon School complex in Philip, South Dakota is described and information gained during approximately three heating seasons of operation is presented.

  19. The Lost City hydrothermal system: Constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E.; Pester, Nicholas J.; Tutolo, Benjamin M.; Ding, Kang

    2015-08-01

    Since the first reported discovery of the Lost City hydrothermal system in 2001, it was recognized that seawater alteration of ultramafic rocks plays a key role in the composition of the coexisting vent fluids. The unusually high pH and high concentrations of H2 and CH4 provide compelling evidence for this. Here we report the chemistry of hydrothermal fluids sampled from two vent structures (Beehive: ∼90-116 °C, and M6: ∼75 °C) at Lost City in 2008 during cruise KNOX18RR using ROV Jason 2 and R/V Revelle assets. The vent fluid chemistry at both sites reveals considerable overlap in concentrations of dissolved gases (H2, CH4), trace elements (Cs, Rb, Li, B and Sr), and major elements (SO4, Ca, K, Na, Cl), including a surprising decrease in dissolved Cl, suggesting a common source fluid is feeding both sites. The absence of Mg and relatively high concentrations of Ca and sulfate suggest solubility control by serpentine-diopside-anhydrite, while trace alkali concentrations, especially Rb and Cs, are high, assuming a depleted mantle protolith. In both cases, but especially for Beehive vent fluid, the silica concentrations are well in excess of those expected for peridotite alteration and the coexistence of serpentine-brucite at all reasonable temperatures. However, both the measured pH and silica values are in better agreement with serpentine-diopside-tremolite-equilibria. Geochemical modeling demonstrates that reaction of plagioclase with serpentinized peridotite can shift the chemical system away from brucite and into the tremolite stability field. This is consistent with the complex intermingling of peridotite and gabbroic bodies commonly observed within the Atlantis Massif. We speculate the existence of such plagioclase bearing peridotite may also account for the highly enriched trace alkali (Cs, Rb) concentrations in the Lost City vent fluids. Additionally, reactive transport modeling taking explicit account of temperature dependent rates of mineral

  20. Cold energy release characteristics of an ice/air direct contact heat exchanger

    SciTech Connect

    Ohira, Akiyoshi; Yanadori, Michio; Iwabuchi, Kunihiko; Kimura, Toshikatsu; Tsubota, Yuji

    1998-12-31

    This paper deals with the cold energy release characteristics of an ice/air direct contact heat exchanger in a refined cold energy conveyance system. Characteristics of the outlet temperature, the humidity, and time history of released heat are examined when the initial height of the ice-cube-packed bed in the heat exchanger is changed. The following are the results obtained in these experiments: (1) Inlet air of 30 C is lowered to about 0 C by passing the air through the heat exchanger, and absolute humidity of the outlet air is reduced to about a quarter of that of the inlet air. (2) There is an optimum height of the ice-cube-packed bed for maximizing the amount of cold energy released. (3) This heat exchange method can supply about twice the amount of cold energy released by an ordinary fin-tube-type heat exchanger even if the air velocity in the heat exchanger is reduced to about 0.38 times that of the fin-tube-type heat exchanger.

  1. Research and Development of Information on Geothermal Direct Heat Application Projects

    SciTech Connect

    Hederman, William F., Jr.; Cohen, Laura A.

    1981-10-01

    This is the first annual report of ICF's geothermal R&D project for the Department of Energy's Idaho Operations Office. The overall objective of this project is to compile, analyze, and report on data from geothermal direct heat application projects. Ultimately, this research should convey the information developed through DOE's and Program Opportunity Notice (PON) activities as well as through other pioneering geothermal direct heat application projects to audiences which can use the early results in new, independent initiatives. A key audience is potential geothermal investors.

  2. A Comparison of Direct Heating During Radiofrequency and Microwave Ablation in Ex Vivo Liver

    SciTech Connect

    Andreano, Anita; Brace, Christopher L.

    2013-04-15

    This study was designed to determine the magnitude and spatial distribution of temperature elevations when using 480 kHz RF and 2.45 GHz microwave energy in ex vivo liver models. A total of 60 heating cycles (20 s at 90 W) were performed in normal, RF-ablated, and microwave-ablated liver tissues (n = 10 RF and n = 10 microwave in each tissue type). Heating cycles were performed using a 480-kHz generator and 3-cm cooled-tip electrode (RF) or a 2.45-GHz generator and 14-gauge monopole (microwave) and were designed to isolate direct heating from each energy type. Tissue temperatures were measured by using fiberoptic thermosensors 5, 10, and 15 mm radially from the ablation applicator at the depth of maximal heating. Power delivered, sensor location, heating rates, and maximal temperatures were compared using mixed effects regression models. No significant differences were noted in mean power delivered or thermosensor locations between RF and microwave heating groups (P > 0.05). Microwaves produced significantly more rapid heating than RF at 5, 10, and 15 mm in normal tissue (3.0 vs. 0.73, 0.85 vs. 0.21, and 0.17 vs. 0.09 Degree-Sign C/s; P < 0.05); and at 5 and 10 mm in ablated tissues (2.3 {+-} 1.4 vs. 0.7 {+-} 0.3, 0.5 {+-} 0.3 vs. 0.2 {+-} 0 Degree-Sign C/s, P < 0.05). The radial depth of heating was {approx}5 mm greater for microwaves than RF. Direct heating obtained with 2.45-GHz microwave energy using a single needle-like applicator is faster and covers a larger volume of tissue than 480-kHz RF energy.

  3. Distribution, structure and temporal variability of hydrothermal outflow at a slow-spreading hydrothermal field from seafloor image mosaics.

    NASA Astrophysics Data System (ADS)

    Barreyre, Thibaut; Escartin, Javier; Cannat, Mathilde; Garcia, Rafael; Science Party, Momar'08; Science Party, Bathyluck'09

    2010-05-01

    The Lucky Strike hydrothermal site, located South of the Azores along the Mid-Atlantic Ridge, is one of the largest and best-known active hydrothermal fields along the ridge system. This site within the MoMAR area is also the target for the installation in 2010 of a pilot deep-sea observatory with direct telemetry to land, to be part of the European Seafloor Observatory Network (ESONET). The Lucky Strike hydrothermal site has seen extensive high-resolution, near-bottom geophysical surveys in 1996 (Lustre'96), 2006 (Momareto06), 2008 (MOMAR08) and 2009 (Bathyluck09). Vertically acquired black-and-white electronic still camera images have been projected and georeferenced to obtain 3 image mosaics covering the zone of active venting, extending ~ 700x800 m2, and with full image resolution (~10 mm pixels). These data allow us to study how hydrothermal outflow is structured, including the relationships between the zones of active high-temperature venting, areas of diffuse outflow, and the geological structure (nature of the substrate, faults and fissures, sediments, etc.). Hydrothermal outflow is systematically associated with bacterial mats that are easily identified in the imagery, allowing us to study temporal variability at two different scales. Over the 13-year period we can potentially track changes in both the geometry and intensity of hydrothermal activity throughout the system; our preliminary study of the Eiffel Tower, White Castle and Mt Segur indicate that activity has been sustained in recent times, with small changes in the detailed geometry of the diffuse outflow and its intensity. At longer times scales (hundreds to 1000 years?) imagery also shows evidence of areas of venting that are no longer active, often associated with the active structures. In combination with the high-resolution bathymetry, the imagery data thus allow us to characterize the shallow structure of hydrothermal outflow at depth, the structural and volcanic control, and ultimately

  4. Geothermal direct-heat utilization assistance. Quarterly project progress report, October--December 1997

    SciTech Connect

    1997-01-01

    This report summarizes geothermal technical assistance, R and D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the first quarter of FY-98 (October--December 1997). It describes 216 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include requests for general information including maps and material for high school debates, and material on geothermal heat pumps, resource and well data, space heating and cooling, greenhouses, aquaculture, equipment, district heating, resorts and spas, industrial applications, electric power and snow melting. Research activities include work on model construction specifications of lineshaft submersible pumps and plate heat exchangers, a comprehensive aquaculture developer package and revisions to the Geothermal Direct Use Engineering and Design Guidebook. Outreach activities include the publication of the Quarterly Bulletin (Vol. 18, No. 4) which was devoted entirely to geothermal activities in South Dakota, dissemination of information mainly through mailings of publications, tours of local geothermal uses, geothermal library acquisition and use, participation in workshops, short courses and technical meetings by the staff, and progress monitor reports on geothermal activities.

  5. Indirect Versus Direct Heating of Sheet Materials: Superplastic Forming and Diffusion Bonding Using Lasers

    NASA Astrophysics Data System (ADS)

    Jocelyn, Alan; Kar, Aravinda; Fanourakis, Alexander; Flower, Terence; Ackerman, Mike; Keevil, Allen; Way, Jerome

    2010-06-01

    Many from within manufacturing industry consider superplastic forming (SPF) to be ‘high tech’, but it is often criticized as too complicated, expensive, slow and, in general, an unstable process when compared to other methods of manipulating sheet materials. Perhaps, the fundamental cause of this negative perception of SPF, and also of diffusion bonding (DB), is the fact that the current process of SPF/DB relies on indirect sources of heating to produce the conditions necessary for the material to be formed. Thus, heat is usually derived from the electrically heated platens of hydraulic presses, to a lesser extent from within furnaces and, sometimes, from heaters imbedded in ceramic moulds. Recent evaluations of these isothermal methods suggest they are slow, thermally inefficient and inappropriate for the process. In contrast, direct heating of only the material to be formed by modern, electrically efficient, lasers could transform SPF/DB into the first choice of designers in aerospace, automotive, marine, medical, architecture and leisure industries. Furthermore, ‘variable temperature’ direct heating which, in theory, is possible with a laser beam(s) may provide a means to control material thickness distribution, a goal of enormous importance as fuel efficient, lightweight structures for transportation systems are universally sought. This paper compares, and contrasts, the two systems and suggests how a change to laser heating might be achieved.

  6. A direct heating model to overcome the edge effect in microplates.

    PubMed

    Lau, Chun Yat; Zahidi, Alifa Afiah Ahmad; Liew, Oi Wah; Ng, Tuck Wah

    2015-01-01

    Array-based tests in a microplate format are complicated by the regional variation in results of the outer against the inner wells of the plate. Analysis of the evaporation mechanics of sessile drops showed that evaporation rate increase with temperature was due to changes in the heat of vaporization, density and diffusion coefficient. In simulations of direct bottom heating of standard microplates, considerable heat transfer via conduction from the side walls was found to be responsible for lower temperatures in the liquid in wells close to the edge. Applying a two temperature heating mode, 304 K at the side compared to 310 K at the bottom, allowed for a more uniform temperature distribution. Transparency microplates were found to inherently possess immunity to the edge effect problem due to the presence of air between the liquid and solid wall. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Direct Observation of a Majorana Quasiparticle Heat Capacity in 3He

    NASA Astrophysics Data System (ADS)

    Bunkov, Y. M.

    2014-04-01

    The Majorana fermion, which acts as its own antiparticle, was suggested by Majorana in 1937 (Nuovo Cimento 14:171). While no stable particle with Majorana properties has yet been observed, Majorana quasiparticles (QP) may exist at the boundaries of topological insulators. Here we report the preliminary results of direct observation of Majorana QPs by a precise measurements of superfluid 3He heat capacity. The bulk superfluid 3He heat capacity falls exponentially with cooling at the temperatures significantly below the energy gap. Owing to the zero energy gap mode the Majorana heat capacity falls in a power law. The Majorana heat capacity can be larger than bulk one at some temperature, which depends on surface to volume ratio of the experimental cell. Some times ago we developed the Dark matter particles detector (DMD) on a basis of superfluid 3He which is working at the frontier of extremely low temperatures (Winkelmann et al., Nucl. Instrum. Meth. A 559:384-386, 2006). Here we report the observation of zero gap mode of Majorana, follows from the new analyses of DMD heat capacity, published early. We have found a 10 % deviation from the bulk superfluid 3He heat capacity at the temperature of 135 μK. This deviation corresponds well to the theoretical value for Majorana heat capacity at such low temperature. (Note, there were no fitting parameters).

  8. Geothermal direct-heat utilization assistance. Federal Assistance Program, Quarterly project progress report, October--December 1994

    SciTech Connect

    Not Available

    1994-12-31

    The report summarizes activities of the Geo-Heat Center (GHC) at Oregon Institute of Technology for the first quarter of Fiscal Year 1995. It describes contacts with parties during this period related to assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, resources and equipment. Research is also being conducted on geothermal energy cost evaluation, low-temperature geothermal resource assessment, use of silica waste from the Cerro Prieto geothermal field as construction materials and geothermal heat pumps. Outreach activities include the publication of a quarterly Bulletin on direct heat applications and dissemination of information on low-temperature geothermal resources and utilization.

  9. U.S. Heat Demand by Sector for Potential Application of Direct Use Geothermal

    DOE Data Explorer

    Katherine Young

    2016-06-23

    This dataset includes heat demand for potential application of direct use geothermal broken down into 4 sectors: agricultural, commercial, manufacturing and residential. The data for each sector are organized by county, were disaggregated specifically to assess the market demand for geothermal direct use, and were derived using methodologies customized for each sector based on the availability of data and other sector-specific factors. This dataset also includes a paper containing a full explanation of the methodologies used.

  10. Direct heating of a laser-imploded core by ultraintense laser-driven ions.

    PubMed

    Kitagawa, Y; Mori, Y; Komeda, O; Ishii, K; Hanayama, R; Fujita, K; Okihara, S; Sekine, T; Satoh, N; Kurita, T; Takagi, M; Watari, T; Kawashima, T; Kan, H; Nishimura, Y; Sunahara, A; Sentoku, Y; Nakamura, N; Kondo, T; Fujine, M; Azuma, H; Motohiro, T; Hioki, T; Kakeno, M; Miura, E; Arikawa, Y; Nagai, T; Abe, Y; Ozaki, S; Noda, A

    2015-05-15

    A novel direct core heating fusion process is introduced, in which a preimploded core is predominantly heated by energetic ions driven by LFEX, an extremely energetic ultrashort pulse laser. Consequently, we have observed the D(d,n)^{3}He-reacted neutrons (DD beam-fusion neutrons) with the yield of 5×10^{8} n/4π sr. Examination of the beam-fusion neutrons verified that the ions directly collide with the core plasma. While the hot electrons heat the whole core volume, the energetic ions deposit their energies locally in the core, forming hot spots for fuel ignition. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with the yield of 6×10^{7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. A one-dimensional hydrocode STAR 1D explains the shell implosion dynamics including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions. A two-dimensional collisional particle-in-cell code predicts the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions, which could be an additional heating source when they reach the core. Since the core density is limited to 2 g/cm^{3} in the current experiment, neither hot electrons nor fast ions can efficiently deposit their energy and the neutron yield remains low. In future work, we will achieve the higher core density (>10 g/cm^{3}); then hot electrons could contribute more to the core heating via drag heating. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high gain fusion.

  11. 76 FR 43941 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY 10 CFR Part 430 RIN 1904-AC56 Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment AGENCY: Office of Energy Efficiency and Renewable Energy, Department of Energy. ACTION: Notice...

  12. Energy efficiency analysis of reactor for torrefaction of biomass with direct heating

    NASA Astrophysics Data System (ADS)

    Kuzmina, J. S.; Director, L. B.; Shevchenko, A. L.; Zaichenko, V. M.

    2016-11-01

    Paper presents energy analysis of reactor for torrefaction with direct heating of granulated biomass by exhaust gases. Various schemes of gas flow through the reactor zones are presented. Performed is a comparative evaluation of the specific energy consumption for the considered schemes. It has been shown that one of the most expensive processes of torrefaction technology is recycling of pyrolysis gases.

  13. Geothermic analysis of high temperature hydrothermal activities area in Western plateau of Sichuan province, China

    NASA Astrophysics Data System (ADS)

    Zhang, J.

    2016-12-01

    There is a high temperature hydrothermal activity area in the western plateau of Sichuan. More than 200 hot springs points have been found in the region, including 11 hot spring water temperature above local boiling point. Most of these distribute along Jinshajjiang fracture, Dege-Xiangcheng fracture, Ganzi-Litang fracture as well as Xianshuihe fracture, and form three high-temperature hydrothermal activity strips in the NW-SE direction. Using gravity, magnetic, seismic and helium isotope data, this paper analyzed the crust-mantle heat flow structure, crustal heat source distribution and water heating system. The results show that the geothermal activity mainly controlled by the "hot" crust. The ratio of crustal heat flow and surface heat flow is higher than 60%. In the high temperature hydrothermal activities area, there is lower S wave velocity zone with Vs<3.2 km/s in 15 30 km depth in middle and lower crust. Basing on the S wave velocity inversion temperature of crust-mantle, it has been found that there is a high temperature layer with 850 1000 ° in 20 40 km depth. It is the main heat source of high temperature hydrothermal activity area of western Sichuan. Our argument is that atmospheric precipitation, surface water infiltrated along the fault fracture into the crustal deep, heating by crustal hot source, and circulation to surface become high temperature hot water. Geothermal water mainly reserve in the Triassic strata of the containing water good carbonate rocks, and in the intrusive granite which is along the fault zone. The thermal energy of Surface heat thermal activities mainly comes from the high-temperature hot source which is located in the middle and lower crust. Being in the deep crustal fracture, the groundwater infiltrated to the deep crust and absorbed heat, then, quickly got back to the surface and formed high hot springs.

  14. On-board Direct Eddy Flux Measurements of Heat, Water Vapor and Co2

    NASA Astrophysics Data System (ADS)

    Tsukamoto, O.; Takahashi, S.; Kono, T.; Yamashita, E.; Ishida, H.

    Direct eddy fluxes of heat(sensible and latent), water vapor and CO2 were measuted with on-board eddy flux system over the Pacific. Present authors are continueing direct eddy flux measurement on R/V MIRAI(JAMSTEC) cruising the Pacific. I addition to these routine heat flux evaluation, direct CO2 flux measurements were applied with LI- 7500 (Licor) and Kaijo sonic anemometer. The eddy flux system including CO2 sensor worked very well even in the moving ship. Small amplitude of turbulent fluctuations of CO2 were measured and it is found that CO2 was transported downward to sea surface during a month(Nov-Dec 2001) around 2N,138E. CO2 concentrations in the air and sea water were also measured and they also confirmed the CO2 sink. The automated real-time eddy flux system including ship motion correction has started and this can be applied to other cruising ships.

  15. Transient volumetric heat transfer coefficient prediction of a three-phase direct contact condenser

    NASA Astrophysics Data System (ADS)

    Mahood, Hameed B.; Sharif, Adel O.; Thorpe, Rex B.

    2015-02-01

    An experimental investigation for the time dependent volumetric heat transfer coefficient of the bubbles type, three-phase direct contact condenser has been carried out utilising a short column (70 cm in total height and 4 cm inner diameter). A 47 cm active height was chosen with five different mass flow rate ratios and three different initial dispersed phase temperatures. Vapour pentane and constant temperature tap water as dispersed and continuous phases were implemented. The results showed that the volumetric heat transfer coefficient decreases with increased time until it almost reaches its steady state conditions. A sharp decrease in the volumetric heat transfer coefficient was found at the beginning of the operation and, diminished over a short time interval. Furthermore, a positive effect of the mass flow rate ratios on the volumetric heat transfer coefficient was noted and this was more pronounced at the beginning of the operation. On the other hand, the volumetric heat transfer coefficient decreased with an increase in the continuous phase mass flow rate and there was no considerable effect of the initial dispersed phase temperatures, which confirms that latent heat transfer is dominant in the process.

  16. The direct simulation of high-speed mixing-layers without and with chemical heat release

    NASA Technical Reports Server (NTRS)

    Sekar, B.; Mukunda, H. S.; Carpenter, M. H.

    1991-01-01

    A direct numerical simulation of high speed reacting and non-reacting flows for H2-air systems is presented. The calculations are made for a convective Mach number of 0.38 with hyperbolic tangent initial profile and finite rate chemical reactions. A higher-order numerical method is used in time accurate mode to time advance the solution to a statistical steady state. About 600 time slices of all the variables are then stored for statistical analysis. It is shown that most of the problems of high-speed combustion with air are characterized by relatively weak heat release. The present study shows that: (1) the convective speed is reduced by heat release by about 10 percent at this convective Mach number M(sub c) = 0.38; (2) the variation of the mean and rms fluctuation of temperature can be explained on the basis of temperature fluctuation between the flame temperature and the ambient; (3) the growth rate with heat release is reduced by 7 percent; and (4) the entrainment is reduced by 25 percent with heat release. These differences are small in comparison with incompressible flow dynamics, and are argued to be due to the reduced importance of heat release in comparison with the large enthalpy gradients resulting from the large-scale vortex dynamics. It is finally suggested that the problems of reduced mixing in high-speed flows are not severely complicated by heat release.

  17. Approach to ignition conditions in a two fluid spheromak with direct ion heating

    NASA Astrophysics Data System (ADS)

    Mayo, R. M.

    1996-12-01

    The spheromak, as a compact toroidal magnetic fusion device, offers substantial advantages as a fusion reactor concept over larger, more complicated, and more costly devices such as the tokamak. The very definite advantages associated with the simply closed geometry, minimized external coil requirements and the possibility of ohmic ignition in the spheromak, represent a substantial improvement over conventional magnetic fusion reactor designs. Furthermore, recent successes in improving confinement parameters (Te~400 eV, Ti~1 keV, ne~5*1014 cm-3, B~1 T) have renewed interest in advancing this concept to a proof of principle, reactor prototype stage. Herein, the initial work by Fowler et al. (Comments Plasma Phys. Control. Fusion 16 (1994) 91), indicating the possibility of ohmic ignition in spheromaks, is extended to a two fluid model that includes direct ion heating. Non-ohmic magnetic dissipation, contributing to direct ion heating, and confinement scaling are quantified through comparison with the latest results from the gun driven Compact Torus Experiment (CTX) spheromak (Phys. Fluids B 2 (1990) 1342). Excellent agreement is demonstrated between experimentally measured plasma parameters and our model predictions. Extrapolation to ignition experiments and reactor relevant conditions is discussed, indicating the possibility of reaching these conditions by gun driven ohmic heating alone and illustrating the merits of direct ion heating. Conservative to pessimistic confinement estimates are used throughout so as to ensure that the promise offered by this concept does not presume unrealizable improvements in energy containment

  18. The hydrothermal power of oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Grose, C. J.; Afonso, J. C.

    2015-03-01

    We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (<1 Ma) is about 50% of the total, significantly higher than previous estimates. This low hydrothermal power estimate originates from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (yielding lower heat flow), and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and convective mantle.

  19. Modeling of hydrothermal circulation applied to active volcanic areas. The case of Vulcano (Italy)

    SciTech Connect

    Todesco, M.

    1995-03-01

    Modeling of fluid and heat flows through porous media has been diffusely applied up to date to the study of geothermal reservoirs. Much less has been done to apply the same methodology to the study of active volcanoes and of the associated volcanic hazard. Hydrothermal systems provide direct information on dormant eruptive centers and significant insights on their state of activity and current evolution. For this reason, the evaluation of volcanic hazard is also based on monitoring of hydrothermal activity. Such monitoring, however, provides measurements of surface parameters, such as fluid temperature or composition, that often are only representative of the shallower portion of the system. The interpretation of these data in terms of global functioning of the hydrothermal circulation can therefore be highly misleading. Numerical modeling of hydrothermal activity provides a physical approach to the description of fluid circulation and can contribute to its understanding and to the interpretation of monitoring data. In this work, the TOUGH2 simulator has been applied to study the hydrothermal activity at Vulcano (Italy). Simulations involved an axisymmetric domain heated from below, and focused on the effects of permeability distribution and carbon dioxide. Results are consistent with the present knowledge of the volcanic system and suggest that permeability distribution plays a major role in the evolution of fluid circulation. This parameter should be considered in the interpretation of monitoring data and in the evaluation of volcanic hazard at Vulcano.

  20. Direct numerical simulations of fluid flow, heat transfer and phase changes

    NASA Technical Reports Server (NTRS)

    Juric, D.; Tryggvason, G.; Han, J.

    1997-01-01

    Direct numerical simulations of fluid flow, heat transfer, and phase changes are presented. The simulations are made possible by a recently developed finite difference/front tracking method based on the one-field formulation of the governing equations where a single set of conservation equations is written for all the phases involved. The conservation equations are solved on a fixed rectangular grid, but the phase boundaries are kept sharp by tracking them explicitly by a moving grid of lower dimension. The method is discussed and applications to boiling heat transfer and the solidification of drops colliding with a wall are shown.

  1. Femtosecond laser direct-writing of waveguide Bragg gratings in a quasi cumulative heating regime.

    PubMed

    Miese, Christopher; Withford, Michael J; Fuerbach, Alexander

    2011-09-26

    Waveguide Bragg gratings (WBGs) were directly inscribed into Alkaline Earth Boro-Aluminosilicate glass samples in a single process step at high fabrication speeds. We utilized a 5.1 MHz femtosecond oscillator to exploit high repetition rate heat accumulation effects. The pulse energy was modulated using a Pockels cell in order to fabricate waveguides that contain a periodic array of nano-structures inside their core. We have demonstrated, for the first time, that the transient build-up of heat accumulation within the sample can lead to the formation of a permanent nano-void. This effect can be exploited to fabricate WBGs at high speeds.

  2. Hydrothermal Fluxes at the Turtle Pits Vent Site, southern MAR

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Walter, M.; Mertens, C.; Sültenfuß, J.; Rhein, M.

    2009-04-01

    The Turtle Pits vent fields are located in a north-south orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5oS. The site consists of three known hydrothermal fields: Turtle Pits, Comfortless Cove, and Red Lion. Data collected during a Meteor cruise in May 2006 and a L' Atalante cruise in January 2008 are used to calculate the total emission of volume, heat, and helium of the site. The data sets consist of vertical profiles and towed transsects of temperature, salinity, and turbidity, as well as direct velocity measurements with a lowered acoustic Doppler current profiler (LADCP) and water samples for Helium isotope analysis. Vent fluid samples for noble gas analysis where taken with an ROV. The particle plume is confined to the rift valley since the depth of the valley exceeds the rise height of the plume. Therefore the fluxes of heat and volume can be estimated from the helium fluxes at the vent sites in comparison with the horizontal helium transport in the valley. The comparison of the 3He concentration measured south of the hydrothermal vents with the 3He signal north of the hydrothermal vents suggests a rather strong northward flow. This is confirmed by the tide corrected velocities observed with the LADCP during the Meteor cruise. The northward volume transport has been calculated using the local bathymetry and tide corrected velocities from the Meteor cruise. In combination with the 3He concentrations and an average 3He end member concentration a flux of 900 l/s is estimated, which corresponds to a heat flux of 450 MW. The rise height of the particle plume estimated from the turbidity data combined with the known background stratification yields an estimate of the total flux of the hydrothermal vents which is one order of magnitude lower.

  3. Efficiencies of Power Plants Using Hydrothermal Oxidation

    NASA Astrophysics Data System (ADS)

    Hirosaka, Kazuma; Yuvamitra, Korakot; Ishikawa, Akira; Hasegawa, Tatsuya

    Wet biomass is hard to handle as a fuel for power plants because it contains high moisture and its drying process needs more energy input than it produces. Hydrothermal oxidation could be one of the promising technologies to overcome this problem because this process does not need drying process at all. We focus on recovery of thermal energy produced by hydrothermal oxidation of wet biomass. Two kinds of power plant are investigated, a direct type and an indirect type. In the direct type power plant, reactant is oxidized in a reactor and directly flowed into a turbine. In the indirect type power plant, reactant is oxidized in a reactor and the reaction heat is conveyed to the main water, which is flowed into a turbine. The amount of electric power and the energy conversion efficiency are calculated by using ethanol, glucose and peat solutions as reactants. In both type of power plant, one steam turbine is employed for generating electricity with the maximum turbine inlet temperature of 650 °C. As ethanol concentration increased, the amount of electric power and the energy conversion efficiency become higher. The maximum efficiency for the direct type power plant using ethanol solution is about 26.4 % for 17.6 wt% at the reactor pressure of 10 MPa. The efficiency of the indirect type power plant is much lower than that of the direct type, but by pressurizing main water up to 4 MPa, the efficiency becomes higher up to 20.9 %. For glucose solution, the maximum efficiency for the direct type is about 25.5 % for 34.5 wt% at the reactor pressure of 5 MPa. The maximum efficiency of the indirect type at the main water pressure of 4 MPa is about 21.1 % for 40.7 wt%. For peat solution, only the indirect type is investigated. The maximum efficiency at the main water pressure of 4 MPa is about 20.8 % for 36.8 wt%.

  4. Diurnal heat storage in direct-gain passive-solar buildings

    SciTech Connect

    Balcomb, J.D.; Neeper, D.A.

    1983-01-01

    This paper presents a simplified method for predicting temperature swings in direct-gain buildings. It is called the DHC method due to the use of a diurnal heat capacity (DHC). Diurnal heat capacity is a measure of the effective amount of heat stored during a sunny day and then released at night - the typical 24-hour diurnal cycle. This enables prediction of the maximum temperature swings experienced in the building and can be calculated using a single 24-hour harmonic. The advantage is that closed-form analytic solutions can be obtained for a variety of simple and layered-wall configurations. Higher harmonic components are accounted for by a correction factor. The method is suitable for us by hand or on a programmable calculator.

  5. Arctic Ocean: hydrothermal activity on Gakkel Ridge.

    PubMed

    Jean-Baptiste, Philippe; Fourré, Elise

    2004-03-04

    In the hydrothermal circulation at mid-ocean ridges, sea water penetrates the fractured crust, becomes heated by its proximity to the hot magma, and returns to the sea floor as hot fluids enriched in various chemical elements. In contradiction to earlier results that predict diminishing hydrothermal activity with decreasing spreading rate, a survey of the ultra-slowly spreading Gakkel Ridge (Arctic Ocean) by Edmonds et al. and Michael et al. suggests that, instead of being rare, the hydrothermal activity is abundant--exceeding by at least a factor of two to three what would be expected by extrapolation from observation on faster spreading ridges. Here we use helium-3 (3He), a hydrothermal tracer, to show that this abundance of venting sites does not translate, as would be expected, into an anomalous hydrothermal 3He output from the ridge. Because of the wide implications of the submarine hydrothermal processes for mantle heat and mass fluxes to the ocean, these conflicting results call for clarification of the link between hydrothermal activity and crustal production at mid-ocean ridges.

  6. What Defines a Separate Hydrothermal System

    SciTech Connect

    Lawless, J.V.; Bogie, I.; Bignall, G.

    1995-01-01

    Separate hydrothermal systems can be defined in a variety of ways. Criteria which have been applied include separation of heat source, upflow, economic resource and geophysical anomaly. Alternatively, connections have been defined by the effects of withdrawal of economically useful fluid and subsidence, effects of reinjection, changes in thermal features, or by a hydrological connection of groundwaters. It is proposed here that: ''A separate hydrothermal system is one that is fed by a separate convective upflow of fluid, at a depth above the brittle-ductile transition for the host rocks, while acknowledging that separate hydrothermal systems can be hydrologically interconnected at shallower levels''.

  7. Novel metallic alloys as phase change materials for heat storage in direct steam generation applications

    NASA Astrophysics Data System (ADS)

    Nieto-Maestre, J.; Iparraguirre-Torres, I.; Velasco, Z. Amondarain; Kaltzakorta, I.; Zubieta, M. Merchan

    2016-05-01

    Concentrating Solar Power (CSP) is one of the key electricity production renewable energy technologies with a clear distinguishing advantage: the possibility to store the heat generated during the sunny periods, turning it into a dispatchable technology. Current CSP Plants use an intermediate Heat Transfer Fluid (HTF), thermal oil or inorganic salt, to transfer heat from the Solar Field (SF) either to the heat exchanger (HX) unit to produce high pressure steam that can be leaded to a turbine for electricity production, or to the Thermal Energy Storage (TES) system. In recent years, a novel CSP technology is attracting great interest: Direct Steam Generation (DSG). The direct use of water/steam as HTF would lead to lower investment costs for CSP Plants by the suppression of the HX unit. Moreover, water is more environmentally friendly than thermal oils or salts, not flammable and compatible with container materials (pipes, tanks). However, this technology also has some important challenges, being one of the major the need for optimized TES systems. In DSG, from the exergy point of view, optimized TES systems based on two sensible heat TES systems (for preheating of water and superheating vapour) and a latent heat TES system for the evaporation of water (around the 70% of energy) is the preferred solution. This concept has been extensively tested [1, 2, 3] using mainly NaNO3 as latent heat storage medium. Its interesting melting temperature (Tm) of 306°C, considering a driving temperature difference of 10°C, means TES charging steam conditions of 107 bar at 316°C and discharging conditions of 81bar at 296°C. The average value for the heat of fusion (ΔHf) of NaNO3 from literature data is 178 J/g [4]. The main disadvantage of inorganic salts is their very low thermal conductivity (0.5 W/m.K) requiring sophisticated heat exchanging designs. The use of high thermal conductivity eutectic metal alloys has been recently proposed [5, 6, 7] as a feasible alternative. Tms

  8. Design Options for Polar-Direct-Drive Targets: From Alpha Heating to Ignition

    NASA Astrophysics Data System (ADS)

    Collins, T. J. B.; Marozas, J. A.; McKenty, P. W.; Skupsky, S.

    2015-11-01

    Polar direct drive (PDD) makes it possible to perform direct-drive-ignition experiments at the National Ignition Facility while the facility is configured for x-ray drive. We present the first PDD ignition-relevant target designs to include the physical effects of cross-beam energy transfer (CBET) and nonlocal heat transport, both of which substantially affect the target drive. These effects are complementary: CBET reduces target drive, while nonlocal heat transport increases the drive (relative to flux-limited models). Previous ignition designs incorporated these processes in only an approximate way through use of an ad-hoc flux limiter applied to the classical expression for heat conduction. In the PDD configuration, a multiwavelength detuning strategy was found to be effective in mitigating the loss of coupling caused by CBET, allowing for implosion speeds comparable to those of previous designs. Target designs are found that span the region from alpha-particle heating to ignition. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  9. A concentrated solar cavity absorber with direct heat transfer through recirculating metallic particles

    SciTech Connect

    Sarker, M. R. I. Saha, Manabendra E-mail: manab04me@gmail.com; Beg, R. A.

    2016-07-12

    A recirculating flow solar particle cavity absorber (receiver) is modeled to investigate the flow behavior and heat transfer characteristics of a novel developing concept. It features a continuous recirculating flow of non-reacting metallic particles (black silicon carbide) with air which are used as a thermal enhancement medium. The aim of the present study is to numerically investigate the thermal behavior and flow characteristics of the proposed concept. The proposed solar particle receiver is modeled using two phase discrete particle model (DPM), RNG k-flow model and discrete ordinate (DO) radiation model. Numerical analysis is carried out considering a solar receiver with only air and the mixture of non-reacting particles and air as a heat transfer as well as heat carrying medium. The parametric investigation is conducted considering the incident solar flux on the receiver aperture and changing air flow rate and recirculation rate inside the receiver. A stand-alone feature of the recirculating flow solar particle receiver concept is that the particles are directly exposed to concentrated solar radiation monotonously through recirculating flow inside the receiver and results in efficient irradiation absorption and convective heat transfer to air that help to achieve high temperature air and consequently increase in thermal efficiency. This paper presents, results from the developed concept and highlights its flow behavior and potential to enhance the heat transfer from metallic particles to air by maximizing heat carrying capacity of the heat transfer medium. The imposed milestones for the present system will be helpful to understand the radiation absorption mechanism of the particles in a recirculating flow based receiver, the thermal transport between the particles, the air and the cavity, and the fluid dynamics of the air and particle in the cavity.

  10. Heat Flux and Wall Temperature Estimates for the NASA Langley HIFiRE Direct Connect Rig

    NASA Technical Reports Server (NTRS)

    Cuda, Vincent, Jr.; Hass, Neal E.

    2010-01-01

    An objective of the Hypersonic International Flight Research Experimentation (HIFiRE) Program Flight 2 is to provide validation data for high enthalpy scramjet prediction tools through a single flight test and accompanying ground tests of the HIFiRE Direct Connect Rig (HDCR) tested in the NASA LaRC Arc Heated Scramjet Test Facility (AHSTF). The HDCR is a full-scale, copper heat sink structure designed to simulate the isolator entrance conditions and isolator, pilot, and combustor section of the HIFiRE flight test experiment flowpath and is fully instrumented to assess combustion performance over a range of operating conditions simulating flight from Mach 5.5 to 8.5 and for various fueling schemes. As part of the instrumentation package, temperature and heat flux sensors were provided along the flowpath surface and also imbedded in the structure. The purpose of this paper is to demonstrate that the surface heat flux and wall temperature of the Zirconia coated copper wall can be obtained with a water-cooled heat flux gage and a sub-surface temperature measurement. An algorithm was developed which used these two measurements to reconstruct the surface conditions along the flowpath. Determinations of the surface conditions of the Zirconia coating were conducted for a variety of conditions.

  11. Titanium metals form direct bonding to bone after alkali and heat treatments.

    PubMed

    Nishiguchi, S; Kato, H; Fujita, H; Oka, M; Kim, H M; Kokubo, T; Nakamura, T

    2001-09-01

    In this article we evaluated the bone-bonding strengths of titanium and titanium alloy implants with and without alkali and heat treatments using the conventional canine femur push-out model. Four kinds of smooth cylindrical implants, made of pure titanium or three titanium alloys, were prepared with and without alkali and heat treatments. The implants were inserted hemitranscortically into canine femora. The bone-bonding shear strengths of the implants were measured using push-out test. At 4 weeks all types of the alkali- and heat-treated implants showed significantly higher bonding strength (2.4-4.5 MPa) than their untreated counterparts (0.3-0.6 MPa). At 12 weeks the bonding strengths of the treated implants showed no further increase, while those of the untreated implants had increased to 0.6-1.2MPa. Histologically, alkali- and heat-treated implants showed direct bonding to bony tissue without intervening fibrous tissue. On the other hand, untreated implants usually had intervening fibrous tissue at the interface between bone and the implant. The early and strong bonding to bone of alkali- and heat-treated titanium and its alloys without intervening fibrous tissue may be useful in establishing cementless stable fixation of orthopedic implants.

  12. Preliminary direct heat geothermal resource assessment of the Tennessee Valley region

    SciTech Connect

    Staub, W.P.

    1980-01-01

    A preliminary appraisal of the direct heat geothermal energy resources of the Tennessee Valley region has been completed. This region includes Kentucky, Tennessee and parts of adjacent states. Intermediate and deep aquifers were selected for study. Basement and Top-of-Knox structure and temperature maps were compiled from oil and gas well data on file at various state geological survey offices. Results of this study indicate that the New Madrid seismic zone is the only area within the region that possesses potential for direct heat utilization. In other areas geothermal energy is either too deep for economical extraction or it will not be able to compete with other local energy resources. The only anomalously high temperature well outside the New Madrid seismic zone was located in the Rome Trough and near the central part of the eastern Kentucky coal basin. Geothermal energy in that region would face strong competition from coal, oil and natural gas.

  13. Direct initiation of gaseous detonation via radiative heating of microparticles volumetrically suspended in the gas

    NASA Astrophysics Data System (ADS)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    2015-11-01

    We propose a new conceptual approach for direct detonation initiation in the gaseous mixtures seeded with micro particles via the radiative heating from the external energy source. The basic mechanisms of energy absorption, ignition and detonation formation are analyzed numerically on the example of hydrogen-oxygen mixture. Obtained data is very promising and allows us to formulate conditions for the source power to ignite detonation in certain system geometry.

  14. Study of hydrothermal channels based on near-bottom magnetic prospecting: Application to Longqi hydrothermal area

    NASA Astrophysics Data System (ADS)

    Tao, W.; Tao, C.; Li, H.; Zhaocai, W.; Jinhui, Z.; Qinzhu, C.; Shili, L.

    2014-12-01

    Mid-ocean ridges, largely present far from the continental plates, are characterized by complex geological structures and numerous hydrothermal systems with complex controlling factors. Exploring seafloor sulfide resources for industrial and scientific applications is a challenge. With the advent of geophysical surveys for seabed investigation, near-bottom magnetic prospecting, which yields shallow geological structure, is an efficient method for investigating active and inactive hydrothermal fields and for researching the structure of hydrothermal systems (Tivey et al., 1993, 1996;German et al., 2008). We collected near-bottom magnetic data in the Longqi hydrothermal area, located in the southwest Indian ridge (49.6° E; Zhu et al., 2010; Tao et al., 2014), using the autonomous benthic explorer, an autonomous underwater vehicle, during the second leg of the Chinese cruise DY115-19 on board R/V DaYangYiHao. Based on the results of the intensity of the spatial differential vector method (Seaman et al., 1993), we outline the hydrothermal alternation zone. By building models, we subsequently infer a fault along the discovered hydrothermal vents; this fault line may be connected to a detachment fault (Zhao et al., 2013). In addition, we discuss the channels of the hydrothermal circulation system (Figure 1), and presume that heat was conducted to the sea subsurface by the detachment fault; the aqueous fluid that infiltrated the fault is heated and conveyed to the seafloor, promoting the circulation of the hydrothermal system.

  15. Influence of heat treatment in air, and subsequent hydrothermal treatment in the liquid phase or water treatment in the liquid phase on a mixed Langmuir-Blodgett film of merocyanine dye-arachidic acid- n-octadecane ternary system

    NASA Astrophysics Data System (ADS)

    Hirano, Yoshiaki; Maio, Ari; Fukuda, Akira; Kitahama, Yasutaka; Ozaki, Yukihiro

    2010-07-01

    We have investigated the influence of heat treatment in air (HT), and subsequent hydrothermal treatment in the liquid phase (HTTL) or water treatment in the liquid phase (WTL) on the H-aggregate of mixed Langmuir-Blodgett (LB) films of merocyanine dye (MS 18)-arachidic acid (C 20)- n-octadecane (AL 18) ternary system by means of polarized visible and IR absorption spectroscopy. The MS 18 monomer is obtained from the first application of HT to the H-aggregate, and the monomer rapidly changes into the J-aggregate upon subsequent HTTL. This demonstrates variation via the monomer for reorganization of the MS 18 chromophore from H- to J-aggregates induced by directly performing HTTL to the H-aggregate in our previous study. While the number of gauche conformers in the MS 18 hydrocarbon chain increases by initial HT, the hydrocarbon chain adopts an all- trans conformation after subsequent HTTL. In addition, the degree of orientation of the MS 18 hydrocarbon chain after HT also approximates to that before HT. The C 20 hexagonal packing after HT turns to orthorhombic one with subsequent HTTL, and the orientation disorder of C 20 hydrocarbon chain caused by HT is renovated as well. The structural changes in the MS 18 and C 20 hydrocarbon chains resulting from latter HTTL arise from the hydrophobic effect in the presence of warm water. Moreover, it has been verified that the AL 18 evaporation strongly relates to the dissociation of H-aggregate, but is not responsible for the variation from the monomer to J-aggregate. Comparing the results obtained upon application of HT/HTTL and HT/WTL, it has been concluded that both large relative permittivity and thermal energy inherent in warm water are quite essential in inducing the rapid reconstitution of MS 18 aggregation state from the monomer to J-aggregate. These also promote the restoration of conformation and orientation changes in the MS 18 hydrocarbon chain, and the modification of subcell packing and orientation disorder in

  16. Hydrothermal Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Shock, E.; Havig, J.; Windman, T.; Meyer-Dombard, D.; Michaud, A.; Hartnett, H.

    2006-12-01

    Life in hot spring ecosystems is confronted with diverse challenges, and the responses to those challenges have dynamic biogeochemical consequences over narrow spatial and temporal scales. Within meters along hot spring outflow channels at Yellowstone, temperatures drop from boiling, and the near-boiling conditions of hot chemolithotrophic communities, to those that permit photosynthesis and on down to conditions where nematodes and insects graze on the edges of photosynthetic mats. Many major and trace element concentrations change only mildly in the water that flows through the entire ecosystem, while concentrations of other dissolved constituents (oxygen, sulfide, ammonia, total organic carbon) increase or decrease dramatically. Concentrations of metals and micronutrients range from toxic to inadequate for enzyme synthesis depending on the choice of hot spring. Precipitation of minerals may provide continuous growth of microbial niches, while dissolution and turbulent flow sweeps them away. Consequently, microbial communities change at the meter scale, and even more abruptly at the photosynthetic fringe. Isotopic compositions of carbon and nitrogen in microbial biomass reflect dramatic and continuous changes in metabolic strategies throughout the system. Chemical energy sources that support chemolithotrophic communities can persist at abundant or useless levels, or change dramatically owing to microbial activity. The rate of temporal change depends on the selection of hot spring systems for study. Some have changed little since our studies began in 1999. Others have shifted by two or more units in pH over several years, with corresponding changes in other chemical constituents. Some go through daily or seasonal desiccation cycles, and still others exhibit pulses of changing temperature (up to 40°C) within minutes. Taken together, hydrothermal ecosystems provide highly manageable opportunities for testing how biogeochemical processes respond to the scale of

  17. Parabolic solar cooker: Cooking with heat pipe vs direct spiral copper tubes

    NASA Astrophysics Data System (ADS)

    Craig, Omotoyosi O.; Dobson, Robert T.

    2016-05-01

    Cooking with solar energy has been seen by many researchers as a solution to the challenges of poverty and hunger in the world. This is no exception in Africa, as solar coking is viewed as an avenue to eliminate the problem of food insecurity, insufficient energy supply for household and industrial cooking. There are several types of solar cookers that have been manufactured and highlighted in literature. The parabolic types of solar cookers are known to reach higher temperatures and therefore cook faster. These cookers are currently being developed for indoor cooking. This technology has however suffered low cooking efficiency and thus leads to underutilization of the high heat energy captured from the sun in the cooking. This has made parabolic solar cookers unable to compete with other conventional types of cookers. Several methods to maximize heat from the sun for indirect cooking has been developed, and the need to improve on them of utmost urgency. This paper investigates how to optimize the heat collected from the concentrating types of cookers by proposing and comparing two types of cooking sections: the spiral hot plate copper tube and the heat pipe plate. The system uses the concentrating solar parabolic dish technology to focus the sun on a conical cavity of copper tubes and the heat is stored inside an insulated tank which acts both as storage and cooking plate. The use of heat pipes to transfer heat between the oil storage and the cooking pot was compared to the use of a direct natural syphon principle which is achieved using copper tubes in spiral form like electric stove. An accurate theoretical analysis for the heat pipe cooker was achieved by solving the boiling and vaporization in the evaporator side and then balancing it with the condensation and liquid-vapour interaction in the condenser part while correct heat transfer, pressure and height balancing was calculated in the second experiment. The results show and compare the cooking time, boiling

  18. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-05

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  19. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, G.F.; Minkov, V.; Petrick, M.

    1981-11-02

    A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  20. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-01

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  1. Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2017-02-01

    The growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east–west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.

  2. Directly connected heat exchanger tube section and coolant-cooled structure

    DOEpatents

    Chainer, Timothy J.; Coico, Patrick A.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2015-09-15

    A method is provided for fabricating a cooling apparatus for cooling an electronics rack, which includes an air-to-liquid heat exchanger, one or more coolant-cooled structures, and a tube. The heat exchanger is associated with the electronics rack and disposed to cool air passing through the rack, includes a plurality of coolant-carrying tube sections, each tube section having a coolant inlet and outlet, one of which is coupled in fluid communication with a coolant loop to facilitate flow of coolant through the tube section. The coolant-cooled structure(s) is in thermal contact with an electronic component(s) of the rack, and facilitates transfer of heat from the component(s) to the coolant. The tube connects in fluid communication one coolant-cooled structure and the other of the coolant inlet or outlet of the one tube section, and facilitates flow of coolant directly between that coolant-carrying tube section of the heat exchanger and the coolant-cooled structure.

  3. Directly connected heat exchanger tube section and coolant-cooled structure

    DOEpatents

    Chainer, Timothy J; Coico, Patrick A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2014-04-01

    A cooling apparatus for an electronics rack is provided which includes an air-to-liquid heat exchanger, one or more coolant-cooled structures and a tube. The heat exchanger, which is associated with the electronics rack and disposed to cool air passing through the rack, includes a plurality of distinct, coolant-carrying tube sections, each tube section having a coolant inlet and a coolant outlet, one of which is coupled in fluid communication with a coolant loop to facilitate flow of coolant through the tube section. The coolant-cooled structure(s) is in thermal contact with an electronic component(s) of the rack, and facilitates transfer of heat from the component(s) to the coolant. The tube connects in fluid communication one coolant-cooled structure and the other of the coolant inlet or outlet of the one tube section, and facilitates flow of coolant directly between that coolant-carrying tube section of the heat exchanger and the coolant-cooled structure.

  4. Converting ultrasonic induction heating deposited monetite coating to Na-doped HA coating on H 2O 2-treated C/C composites by a two-step hydrothermal method

    NASA Astrophysics Data System (ADS)

    Xin-bo, Xiong; Jian-feng, Hung; Xie-rong, Zeng; Cen-cen, Chu

    2011-10-01

    a monetite coating on H 2O 2-treated C/C composites was prepared by ultrasonic induction heating (UIH) technology. Subsequently, this coating was subjected to an ammonia hydrothermal treatment to form a undoped hydroxyapatite (U-HA) coating. Finally, the as-prepared U-HA coating was placed in a NaOH solution and hydrothermally treated to produce the other hydroxyapatite (Na-HA) coating. The structure, morphology and chemical composition of the two HA coatings were characterized by XRD, FTIR, SEM and EDS, the adhesiveness and local mechanical properties, e.g. nanohardness and Young's modulus of the two HA coatings to C/C composites was evaluated by a scratch test and nanoindentation technique respectively. The results showed that the two HA coatings had the alike morphology and crystallization. But, compared with the U-HA coating, the Na-HA coating was doped with Na ions, and gave a Ca/P ratio close to a stoichiometric hydroxyapatite, and thus showed a higher nano-indentation value, Young's modulus, and larger bonding strength. These results verified the strengthened effect of Na ion in hydroxyapatite coating on carbon/carbon (C/C) composities.

  5. Electricity generation from hydrothermal vents

    NASA Astrophysics Data System (ADS)

    Aryadi, Y.; Rizal, I. S.; Fadhli, M. N.

    2016-09-01

    Hydrothermal vent is a kind of manifestation of geothermal energy on seabed. It produces high temperature fluid through a hole which has a diameter in various range between several inches to tens of meters. Hydrothermal vent is mostly found over ocean ridges. There are some 67000 km of ocean ridges, 13000 of them have been already studied discovering more than 280 sites with geothermal vents. Some of them have a thermal power of up to 60 MWt. These big potential resources of energy, which are located over subsea, have a constraint related to environmental impact to the biotas live around when it becomes an object of exploitation. Organic Rankine Cycle (ORC) is a method of exploiting heat energy to become electricity using organic fluid. This paper presents a model of exploitation technology of hydrothermal vent using ORC method. With conservative calculation, it can give result of 15 MWe by exploiting a middle range diameter of hydrothermal vent in deep of 2000 meters below sea level. The technology provided here really has small impact to the environment. With an output energy as huge as mentioned before, the price of constructing this technology is low considering the empty of cost for drilling as what it should be in conventional exploitation. This paper also presents the comparison in several equipment which is more suitable to be installed over subsea.

  6. Direct selective growth of ZnO nanowire arrays from inkjet-printed zinc acetate precursor on a heated substrate

    NASA Astrophysics Data System (ADS)

    Kwon, Jinhyeong; Hong, Sukjoon; Lee, Habeom; Yeo, Junyeob; Lee, Seung S.; Ko, Seung Hwan

    2013-11-01

    Inkjet printing of functional materials has drawn tremendous interest as an alternative to the conventional photolithography-based microelectronics fabrication process development. We introduce direct selective nanowire array growth by inkjet printing of Zn acetate precursor ink patterning and subsequent hydrothermal ZnO local growth without nozzle clogging problem which frequently happens in nanoparticle inkjet printing. The proposed process can directly grow ZnO nanowires in any arbitrary patterned shape, and it is basically very fast, low cost, environmentally benign, and low temperature. Therefore, Zn acetate precursor inkjet printing-based direct nanowire local growth is expected to give extremely high flexibility in nanomaterial patterning for high-performance electronics fabrication especially at the development stage. As a proof of concept of the proposed method, ZnO nanowire network-based field effect transistors and ultraviolet photo-detectors were demonstrated by direct patterned grown ZnO nanowires as active layer.

  7. Direct selective growth of ZnO nanowire arrays from inkjet-printed zinc acetate precursor on a heated substrate

    PubMed Central

    2013-01-01

    Inkjet printing of functional materials has drawn tremendous interest as an alternative to the conventional photolithography-based microelectronics fabrication process development. We introduce direct selective nanowire array growth by inkjet printing of Zn acetate precursor ink patterning and subsequent hydrothermal ZnO local growth without nozzle clogging problem which frequently happens in nanoparticle inkjet printing. The proposed process can directly grow ZnO nanowires in any arbitrary patterned shape, and it is basically very fast, low cost, environmentally benign, and low temperature. Therefore, Zn acetate precursor inkjet printing-based direct nanowire local growth is expected to give extremely high flexibility in nanomaterial patterning for high-performance electronics fabrication especially at the development stage. As a proof of concept of the proposed method, ZnO nanowire network-based field effect transistors and ultraviolet photo-detectors were demonstrated by direct patterned grown ZnO nanowires as active layer. PMID:24252130

  8. Geothermal direct-heat utilization assistance. Quarterly project progress report, July 1996--September 1996. Federal Assistance Program

    SciTech Connect

    Lienau, P.

    1996-11-01

    This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the fourth quarter of FY-96. It describes 152 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on greenhouse peaking. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

  9. Fused silica GRISMs manufactured by hydrophilic direct bonding at moderate heating

    NASA Astrophysics Data System (ADS)

    Kalkowski, G.; Grabowski, K.; Harnisch, G.; Flügel-Paul, T.; Zeitner, U.; Risse, S.

    2017-06-01

    For high-resolution spectroscopy in space, GRISM elements—obtained by patterning gratings onto a prism surface—find increasing applications. We report on GRISM manufacturing by joining the individual functional elements—prisms and gratings—to suitable components by the technology of hydrophilic direct bonding. Fused silica was used as a substrate material and binary gratings were fabricated by standard e-beam lithography and dry etching. Alignment of the grating dispersion direction to the prism angle was realized by passive adjustment on dedicated bonding gear matched to the substrate geometry. Materials adapted bonds of high transmission, stiffness, and strength were obtained after heat treatment at temperatures of about 200 °C in vacuum. Examples for bonding uncoated as well as coated grating surfaces are given. The results illustrate the great potential of hydrophilic glass direct bonding for manufacturing transmission optics to be used in space or other heavy duty applications.

  10. En Echelon Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Ryan, M. P.; Carr, P. M.; Daniels, D. L.; Sutphin, D. M.

    2005-12-01

    -orthogonal, dike-parallel, and 45 degree angles of attack with respect to the major axes of the individual dikes within the en echelon array. Depending on the magnitudes and geometric arrangement of key system attributes, an en echelon hydrothermal system may either act as an efficient thermal radiator, effectively shedding heat to the surroundings, or may it act as an effective heater, thermally enhancing the environment between neighboring dikes in 3-D. Conditions that promote the efficient loss of heat include thin dikes of short length, large dike-to-dike offset, high matrix fluid velocities, and regional flow azimuths that are orthogonal to the individual dikes. Conditions that promote differential heating between the dikes include wide dikes with maximal overlap and minimal offset, low regional flow velocities and "angles of attack" of the regional flow field that provide for maximum hydrodynamic "shelter" for individual dikes within the interior of the en echelon array.

  11. Core conditions for alpha heating attained in direct-drive inertial confinement fusion.

    PubMed

    Bose, A; Woo, K M; Betti, R; Campbell, E M; Mangino, D; Christopherson, A R; McCrory, R L; Nora, R; Regan, S P; Goncharov, V N; Sangster, T C; Forrest, C J; Frenje, J; Gatu Johnson, M; Glebov, V Yu; Knauer, J P; Marshall, F J; Stoeckl, C; Theobald, W

    2016-07-01

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  12. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Bose, A.; Woo, K. M.; Betti, R.; Campbell, E. M.; Mangino, D.; Christopherson, A. R.; McCrory, R. L.; Nora, R.; Regan, S. P.; Goncharov, V. N.; Sangster, T. C.; Forrest, C. J.; Frenje, J.; Gatu Johnson, M.; Glebov, V. Yu; Knauer, J. P.; Marshall, F. J.; Stoeckl, C.; Theobald, W.

    2016-07-01

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016), 10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  13. Design of plate directional heat transmission structure based on layered thermal metamaterials

    SciTech Connect

    Sun, L. K.; Yu, Z. F.; Huang, J.

    2016-02-15

    Invisibility cloaks based on transformation optics are often closed structures; however, such a structure limits the kinds of objects that can be placed in the cloak. In this work, we adopt a transformation thermodynamics approach to design an “open cloak”, called a plate directional heat transmission structure, which is capable of guiding heat fluxes to the flank region of the metamaterial device. The most fascinating and unique feature of the device is that the lower surface can remain at a lower temperature compared with the SiO{sub 2} aerogel thermal insulation material. Our results are expected to markedly enhance capabilities in thermal protection, thermal-energy utilization, and domains beyond. In addition to the theoretical analysis, the present design is demonstrated in numerical simulations based on finite element calculations.

  14. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    SciTech Connect

    Bose, A.; Woo, K. M.; Betti, R.; Campbell, E. M.; Mangino, D.; Christopherson, A. R.; McCrory, R. L.; Nora, R.; Regan, S. P.; Goncharov, V. N.; Sangster, T. C.; Forrest, C. J.; Frenje, J.; Gatu Johnson, M.; Glebov, V. Yu; Knauer, J. P.; Marshall, F. J.; Stoeckl, C.; Theobald, W.

    2016-07-07

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  15. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    DOE PAGES

    Bose, A.; Woo, K. M.; Betti, R.; ...

    2016-07-07

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117,more » 025001 (2016)] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.« less

  16. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    SciTech Connect

    Bose, A.; Woo, K. M.; Betti, R.; Campbell, E. M.; Mangino, D.; Christopherson, A. R.; McCrory, R. L.; Nora, R.; Regan, S. P.; Goncharov, V. N.; Sangster, T. C.; Forrest, C. J.; Frenje, J.; Gatu Johnson, M.; Glebov, V. Yu; Knauer, J. P.; Marshall, F. J.; Stoeckl, C.; Theobald, W.

    2016-07-07

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  17. Dehumidification of Moist Air by Direct Contact Heat and Mass Transfer in Cold Water Solution

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Horibe, Akihiko; Haruki, Naoto; Ishioka, Tohru; Takeuchi, Yoshiyuki

    This paper has dealt with the direct contact heat and mass transfer characteristics of dehumidification of flowing moist air bubbles in a cold water solution (propylene glycoI). The saturated water-vapor humidity of propylene glycol water solution was measured under some conditions of temperature and mass concentration of the water solution. Experiments on dehumidification of air bubbles were performed by ascending air bubbles in the water absorbing solution for various parameters of air temperature, humidity and flow rate etc. The experimental data of air bubble diameter, dehumidification rate and apparent heat transfer coefficient were correlated by means of some experimental parameters such as air temperature, humidity, flow rate and height of water solution layer.

  18. Direct imaging of Joule heating dynamics and temperature profiling inside a carbon nanotube interconnect.

    PubMed

    Costa, Pedro M F J; Gautam, Ujjal K; Bando, Yoshio; Golberg, Dmitri

    2011-08-09

    Understanding resistive (or Joule) heating in fundamental nanoelectronic blocks, such as carbon nanotubes, remains a major challenge, particularly in regard to their structural and thermal variations during prolonged periods of electrical stress. Here we show real-time imaging of the associated effects of Joule heating in the channel of carbon nanotube interconnects. First, electrical contacts to nanotubes entirely filled with a sublimable material are made inside a transmission electron microscope. On exposure to a high current density, resistive hotspots are identified on (or near) the contact points. These later migrate and expand along the carbon nanotube, as indicated by the localized sublimation of the encapsulated material. Using the hotspot edges as markers, it is possible to estimate the internal temperature profiles of the nanotube. Simple and direct, our method provides remarkable spatial and temporal insights into the dynamics of resistive hotspots and millisecond-paced thermal variations occurring inside nanoscaled tubular interconnects.

  19. Simulation of Solar Heat Pump Dryer Directly Driven by Photovoltaic Panels

    NASA Astrophysics Data System (ADS)

    Houhou, H.; Yuan, W.; Wang, G.

    2017-05-01

    This paper investigates a new type of solar heat pump dryer directly driven by photovoltaic panels. In order to design this system, a mathematical model has been established describing the whole drying process, including models of key components and phenomena of heat and mass transfer at the product layer and the air. The results of simulation at different drying air temperatures and velocities have been calculated and it indicate that the temperature of drying air is crucial external parameter compared to the velocity, with the increase of drying temperature from 45°C to 55°C, the product moisture content (Kg water/Kg dry product) decreased from 0.75 Kg/Kg to 0.3 Kg/Kg.

  20. The hydrothermal power of oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Grose, C. J.; Afonso, J. C.

    2015-10-01

    We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of axial hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than most previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (< 1 My old) is about 50 % of the total, significantly higher than previous estimates. These new estimates originate from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (a thermal blanketing effect yielding lower heat flow) and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of ventilated hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and the convective mantle.

  1. Dynamics of the Yellowstone hydrothermal system

    USGS Publications Warehouse

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  2. Dynamics of the Yellowstone hydrothermal system

    NASA Astrophysics Data System (ADS)

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-09-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  3. Direct numerical simulation of viscoelastic-fluid-based nanofluid turbulent channel flow with heat transfer

    NASA Astrophysics Data System (ADS)

    Yang, Juan-Cheng; Li, Feng-Chen; Cai, Wei-Hua; Zhang, Hong-Na; Yu, Bo

    2015-08-01

    Our previous experimental studies have confirmed that viscoelastic-fluid-based nanofluid (VFBN) prepared by suspending nanoparticles in a viscoelastic base fluid (VBF, behaves drag reduction at turbulent flow state) can reduce turbulent flow resistance as compared with water and enhance heat transfer as compared with VBF. Direct numerical simulation (DNS) is performed in this study to explore the mechanisms of heat transfer enhancement (HTE) and flow drag reduction (DR) for the VFBN turbulent flow. The Giesekus model is used as the constitutive equation for VFBN. Our previously proposed thermal dispersion model is adopted to take into account the thermal dispersion effects of nanoparticles in the VFBN turbulent flow. The DNS results show similar behaviors for flow resistance and heat transfer to those obtained in our previous experiments. Detailed analyses are conducted for the turbulent velocity, temperature, and conformation fields obtained by DNSs for different fluid cases, and for the friction factor with viscous, turbulent, and elastic contributions and heat transfer rate with conductive, turbulent and thermal dispersion contributions of nanoparticles, respectively. The mechanisms of HTE and DR of VFBN turbulent flows are then discussed. Based on analogy theory, the ratios of Chilton-Colburn factor to friction factor for different fluid flow cases are investigated, which from another aspect show the significant enhancement in heat transfer performance for some cases of water-based nanofluid and VFBN turbulent flows. Project supported by the National Natural Science Foundation of China (Grant No. 51276046), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20112302110020), the China Postdoctoral Science Foundation (Grant No. 2014M561037), and the President Fund of University of Chinese Academy of Sciences, China (Grant No. Y3510213N00).

  4. EBSD characterization of the growth mechanism of SiC synthesized via direct microwave heating

    SciTech Connect

    Wang, Jigang; Huang, Shan; Liu, Song; Qing, Zhou

    2016-04-15

    Well-crystallized 3C-silicon carbide (SiC) grains/nanowires have been synthesized rapidly and conveniently via direct microwave heating, simply using silicon dioxide powders and artificial graphite as raw materials. The comprehensive characterizations have been employed to investigate the micro-structure of the obtained 3C-SiC products. Results indicated that, different from the classic screw dislocation growth mechanism, the 3C-SiC grains/nanowires synthesized via high-energy vacuum microwave irradiation were achieved through the two-dimension nucleation and laminar growth mechanism. Especially, the electron backscattered diffraction (EBSD) was employed to characterize the crystal planes of the as-grown SiC products. The calculated Euler angles suggested that the fastest-growing crystal planes (211) were overlapped gradually. Through the formation of the (421) transformation plane, (211) finally evolved to (220) which existed as the side face of SiC grains. The most stable crystal planes (111) became the regular hexagonal planes in the end, which could be explained by the Bravais rule. The characterization results of EBSD provided important experimental information for the evolution of crystal planes. - Graphical abstract: The formation of 3C-SiC prepared via direct microwave heating follows the mechanism of two-dimension nucleation and laminar growth. - Highlights: • 3C−SiC grains/nanowires were obtained via direct microwave heating. • 3C−SiC followed the mechanism of two-dimension nucleation and laminar growth. • In-situ EBSD analysis provided the experimental evidences of the growth.

  5. Unsteady heat transfer and direct comparison to steady-state measurements in a rotor-wake experiment

    NASA Technical Reports Server (NTRS)

    Obrien, J. E.; Simoneau, R. J.; Lagraff, J. E.; Morehouse, K. A.

    1986-01-01

    Circumferentially local and time-resolved heat transfer measurements were obtained for a circular cylinder in crossflow located downstream of a rotating spoked wheel wake generator in a steady flow tunnel. The unsteady heat transfer effects were obtained by developing an extension of a thin film gauge technique employed to date exclusively in short-duration facilities. The time-average thin film results and conventional steady-state heat transfer measurements were compared. Time-averaged wake-induced stagnation heat transfer enhancement levels above the nowake case were about 10% for the four cylinder Reynolds numbers. This enhancement level was nearly independent of bar passing frequency and was related directly to the time integral of the heat transfer spikes observed at the bar passing frequency. It is observed that the wake-induced heat transfer spikes have peak magnitudes averaging 30 to 40% above the interwake heat transfer level.

  6. Direct measurements of heating by electromagnetically trapped gold nanoparticles on supported lipid bilayers.

    PubMed

    Bendix, Poul M; Reihani, S Nader S; Oddershede, Lene B

    2010-04-27

    Absorption of electromagnetic irradiation results in significant heating of metallic nanoparticles, an effect which can be advantageously used in biomedical contexts. Also, metallic nanoparticles are presently finding widespread use as handles, contacts, or markers in nanometer scale systems, and for these purposes it is essential that the temperature increase associated with electromagnetic irradiation is not harmful to the environment. Regardless of whether the heating of metallic nanoparticles is desired or not, it is crucial for nanobio assays to know the exact temperature increase associated with electromagnetic irradiation of metallic nanoparticles. We performed direct measurements of the temperature surrounding single gold nanoparticles optically trapped on a lipid bilayer, a biologically relevant matrix. The lipid bilayer had incorporated fluorescent molecules which have a preference for either fluid or gel phases. The heating associated with electromagnetic radiation was measured by visualizing the melted footprint around the irradiated particle. The effect was measured for individual gold nanoparticles of a variety of sizes and for a variety of laser powers. The temperatures were highly dependent on particle size and laser power, with surface temperature increments ranging from a few to hundreds of degrees Celsius. Our results show that by a careful choice of gold nanoparticle size and strength of irradiating electromagnetic field, one can control the exact particle temperature. The method is easily applicable to any type of nanoparticle for which the photothermal effect is sought to be quantified.

  7. Regressed relations for forced convection heat transfer in a direct injection stratified charge rotary engine

    NASA Technical Reports Server (NTRS)

    Lee, Chi M.; Schock, Harold J.

    1988-01-01

    Currently, the heat transfer equation used in the rotary combustion engine (RCE) simulation model is taken from piston engine studies. These relations have been empirically developed by the experimental input coming from piston engines whose geometry differs considerably from that of the RCE. The objective of this work was to derive equations to estimate heat transfer coefficients in the combustion chamber of an RCE. This was accomplished by making detailed temperature and pressure measurements in a direct injection stratified charge (DISC) RCE under a range of conditions. For each specific measurement point, the local gas velocity was assumed equal to the local rotor tip speed. Local physical properties of the fluids were then calculated. Two types of correlation equations were derived and are described in this paper. The first correlation expresses the Nusselt number as a function of the Prandtl number, Reynolds number, and characteristic temperature ratio; the second correlation expresses the forced convection heat transfer coefficient as a function of fluid temperature, pressure and velocity.

  8. Experiments to investigate direct containment heating phenomena with scaled models of the Surry Nuclear Power Plant

    SciTech Connect

    Blanchat, T.K.; Allen, M.D.; Pilch, M.M.; Nichols, R.T.

    1994-06-01

    The Containment Technology Test Facility (CTTF) and the Surtsey Test Facility at Sandia National Laboratories are used to perform scaled experiments that simulate High Pressure Melt Ejection accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effects of direct containment heating (DCH) phenomena on the containment load. High-temperature, chemically reactive melt (thermite) is ejected by high-pressure steam into a scale model of a reactor cavity. Debris is entrained by the steam blowdown into a containment model where specific phenomena, such as the effect of subcompartment structures, prototypic air/steam/hydrogen atmospheres, and hydrogen generation and combustion, can be studied. Four Integral Effects Tests (IETs) have been performed with scale models of the Surry NPP to investigate DCH phenomena. The 1/61{sup th} scale Integral Effects Tests (IET-9, IET-10, and IET-11) were conducted in CTRF, which is a 1/6{sup th} scale model of the Surry reactor containment building (RCB). The 1/10{sup th} scale IET test (IET-12) was performed in the Surtsey vessel, which had been configured as a 1/10{sup th} scale Surry RCB. Scale models were constructed in each of the facilities of the Surry structures, including the reactor pressure vessel, reactor support skirt, control rod drive missile shield, biological shield wall, cavity, instrument tunnel, residual heat removal platform and heat exchangers, seal table room and seal table, operating deck, and crane wall. This report describes these experiments and gives the results.

  9. Continuous enzymatic cooking and liquefaction of starch using the technique of direct resistive heating.

    PubMed

    Varella, V L; Concone, B R; Senise, J T; Doin, P A

    1984-07-01

    Continuous cooker prototypes of very simple design, using electricity as a primary energy source, were developed for the process of cooking and liquefaction of starch suspensions. Previous work on equipment using microwave dielectric heating has already been reported. Results of energy consumption as low as 330 kcal/kg based on starch content were achieved. Considering these results and looking for new solutions or engineering concepts, the authors have been investigating the possibility of using electric energy at 60 Hz for direct resistive heating, in which the starch suspension is the proper "resistor."The most important results of energetic yield obtained until now, working in a continuous process of cooking-liquefaction, are not larger than 235 kcal (272 Wh)/kg based on starch content. These results were obtained using a commercial grade alpha-amylase from B. subtillis, working with temperatures ranging from 70 to 75 degrees C, and with residence times in the reactor not greater than 1.5 min. The experiments of saccharification and fermentation accomplished as a test for the efficiency of this heating technique gave good results (as with a conventional technique) and thus enabled us to proceed with the studies.

  10. Conceptual design study for the HCRF direct contact heat exchanger modification

    SciTech Connect

    Wahl, E. F.

    1984-06-01

    The conceptual design of sieve trays for modifying the HCRF direct contact heat exchanger was developed as follows. The models of the prior work, EG&G subcontract No. K-7752, were extended and modified so the predicted heat transfer coincided with the experimental data of the 60 KW Raft River tests conducted by EG&G. Using these models, a hole diameter of 0.25 inches and a hole velocity of 1.3 ft/sec or greater was selected to accomplish the required heat transfer while minimizing mass transferred to the geothermal fluid. Using the above information, a conceptual design for a sieve tray column was developed. It was determined that the column should operate as a working fluid filled, working fluid dispersed column. This is accomplished by level control of the geothermal fluid below the bottom tray. The dimensions and configuration of the trays and downcomers, and the number of holes and their diameters is summarized in Wahl Company drawings 84144001 and 84144003 submitted with this report. The performance of this design is expected to be 12,000 lbs/hr of geothermal fluid for single component fluids and 11,800 to 12,000 lbs/hr for mixed fluids at a working fluid flow rate of 71% of the geothermal fluid flow rate. The flow rate limit of the geothermal fluid will vary from 9800 to 13,000 lbs/hr as the ratio varies from 83% to 62%.

  11. CONTAIN code analyses of direct containment heating (DCH) experiments: Model assessment and phenomenological interpretation

    SciTech Connect

    Williams, D.C.; Griffith, R.O.; Tadios, E.L.; Washington, K.E.

    1995-05-12

    Models for direct containment heating (DCH) in the CONTAIN code for severe accident analysis have been reviewed and a standard input prescription for their use has been defined. The code has been exercised against a large subset of the available DCH data base. Generally good agreement with the experimental results for containment pressurization ({Delta}P) and hydrogen generation has been obtained. Extensive sensitivity studies have been performed which permit assessment of many of the strengths and weaknesses of specific model features. These include models for debris transport and trapping, DCH heat transfer and chemistry, atmosphere-structure heat transfer, interactions between nonairborne debris and blowdown steam, potential effects of debris-water interactions, and hydrogen combustion under DCH conditions. Containment compartmentalization is an important DCH mitigator in the calculations, in agreement with experimental results. The CONTAIN model includes partially parametric treatments for some processes that are not well understood. The importance of the associated uncertainties depends upon the details of the DCH scenario being analyzed. Recommended sensitivity studies are summarized that allow the user to obtain a reasonable estimate of the uncertainties in the calculated results.

  12. Analysis of conditional statistics of a supersonic jet flame in heated coflow via direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Jin, Tai; Luo, Kun; Lu, Shuqiang; Fan, Jianren

    2017-05-01

    Direct numerical simulation of a three-dimensional spatially-developing supersonic turbulent round jet flame in heated coflow has been conducted. The lifted flame is auto-ignited and stabilized with a flame base. The flame surface presents to be quite corrugated due to interactions with turbulence. The mean heat release rate conditioned on curvature of the flame surface presents to be larger for positive than negative. The supersonic jet spreads slower than subsonic case. The mean center line velocity increases slightly far field due to heat release, which is definitely different from the non-reacting flows where the velocity decays monotonously. The large fluctuations of the species mass fraction and temperature in the mixture fraction space result in large discrepancy when using the first order CMC closure where the fluctuations neglected. Correction of the reaction source terms using conditional PDF approach based on doubly condition moment closure is proved to be effective, however the accuracy of the singly conditioned chemical source terms depends to a large extent on accurate assumption for the pdf of progress variable. The Beta pdf performs better in the far field of the jet flame, while very poor in the region near the nozzle.

  13. Numerical modeling of heat transfer in molten silicon during directional solidification process

    SciTech Connect

    Srinivasan, M.; Ramasamy, P.

    2015-06-24

    Numerical investigation is performed for some of the thermal and fluid flow properties of silicon melt during directional solidification by numerical modeling. Dimensionless numbers are extremely useful to understand the heat and mass transfer of fluid flow on Si melt and control the flow patterns during crystal growth processes. The average grain size of whole crystal would increase when the melt flow is laminar. In the silicon growth process, the melt flow is mainly driven by the buoyancy force resulting from the horizontal temperature gradient. The thermal and flow pattern influences the quality of the crystal through the convective heat and mass transport. The computations are carried out in a 2D axisymmetric model using the finite-element technique. The buoyancy effect is observed in the melt domain for a constant Rayleigh number and for different Prandtl numbers. The convective heat flux and Reynolds numbers are studied in the five parallel horizontal cross section of melt silicon region. And also, velocity field is simulated for whole melt domain with limited thermal boundaries. The results indicate that buoyancy forces have a dramatic effect on the most of melt region except central part.

  14. Direct utilization of geothermal energy for space and water heating at Marlin, Texas. Final report

    SciTech Connect

    Conover, M.F.; Green, T.F.; Keeney, R.C.; Ellis, P.F. II; Davis, R.J.; Wallace, R.C.; Blood, F.B.

    1983-05-01

    The Torbett-Hutchings-Smith Memorial Hospital geothermal heating project, which is one of nineteen direct-use geothermal projects funded principally by DOE, is documented. The five-year project encompassed a broad range of technical, institutional, and economic activities including: resource and environmental assessments; well drilling and completion; system design, construction, and monitoring; economic analyses; public awareness programs; materials testing; and environmental monitoring. Some of the project conclusions are that: (1) the 155/sup 0/F Central Texas geothermal resource can support additional geothermal development; (2) private-sector economic incentives currently exist, especially for profit-making organizations, to develop and use this geothermal resource; (3) potential uses for this geothermal resource include water and space heating, poultry dressing, natural cheese making, fruit and vegetable dehydrating, soft-drink bottling, synthetic-rubber manufacturing, and furniture manufacturing; (4) high maintenance costs arising from the geofluid's scaling and corrosion tendencies can be avoided through proper analysis and design; (5) a production system which uses a variable-frequency drive system to control production rate is an attractive means of conserving parasitic pumping power, controlling production rate to match heating demand, conserving the geothermal resource, and minimizing environmental impacts.

  15. Regressed relations for forced convection heat transfer in a direct injection stratified charge rotary engine

    NASA Technical Reports Server (NTRS)

    Lee, Chi M.; Schock, Harold J.

    1988-01-01

    Currently, the heat transfer equation used in the rotary combustion engine (RCE) simulation model is taken from piston engine studies. These relations have been empirically developed by the experimental input coming from piston engines whose geometry differs considerably from that of the RCE. The objective of this work was to derive equations to estimate heat transfer coefficients in the combustion chamber of an RCE. This was accomplished by making detailed temperature and pressure measurements in a direct injection stratified charge (DISC) RCE under a range of conditions. For each specific measurement point, the local gas velocity was assumed equal to the local rotor tip speed. Local physical properties of the fluids were then calculated. Two types of correlation equations were derived and are described in this paper. The first correlation expresses the Nusselt number as a function of the Prandtl number, Reynolds number, and characteristic temperature ratio; the second correlation expresses the forced convection heat transfer coefficient as a function of fluid temperature, pressure and velocity.

  16. A direct approach to finding unknown boundary conditions in steady heat conduction

    NASA Technical Reports Server (NTRS)

    Martin, Thomas J.; Dulikravich, George S.

    1993-01-01

    The capability of the boundary element method (BEM) in determining thermal boundary conditions on surfaces of a conducting solid where such quantities are unknown was demonstrated. The method uses a non-iterative direct approach in solving what is usually called the inverse heat conduction problem (IHCP). Given any over-specified thermal boundary conditions such as a combination of temperature and heat flux on a surface where such data is readily available, the algorithm computes the temperature field within the object and any unknown thermal boundary conditions on surfaces where thermal boundary values are unavailable. A two-dimensional, steady-state BEM program was developed and was tested on several simple geometries where the analytic solution was known. Results obtained with the BEM were in excellent agreement with the analytic values. The algorithm is highly flexible in treating complex geometries, mixed thermal boundary conditions, and temperature-dependent material properties and is presently being extended to three-dimensional and unsteady heat conduction problems. The accuracy and reliability of this technique was very good but tended to deteriorate when the known surface conditions were only slightly over-specified and far from the inaccessible surface.

  17. Research of energy efficiency direct-heating systems with sequential connection of space heaters with different methods of heat consumption regulation

    NASA Astrophysics Data System (ADS)

    Morozov, Maxim N.; Strizhak, Pavel A.

    2015-01-01

    A model of the building heating system, consisting of energy source, a distributed automatic control system, elements of individual heating unit and heating system is designed. Application Simulink of mathematical package Matlab is selected as a platform for the model. There are the specialized application Simscape libraries in aggregate with a wide range of Matlab mathematical tools allow to apply the "acausal" modeling concept. The conducted research of single-pipe heating system configuration and automatic control system allowed comparing the integral parameters of the systems with local and individual regulation. The results of research of thermal condition premises, situated in the extreme movement direction of the coolant are given. The conclusions about the possibility of increasing the operational efficiency of single-pipe heating system configuration in the implementation of distributed control systems are presented.

  18. A Chebyshev Collocation Method for Moving Boundaries, Heat Transfer, and Convection During Directional Solidification

    NASA Technical Reports Server (NTRS)

    Zhang, Yiqiang; Alexander, J. I. D.; Ouazzani, J.

    1994-01-01

    Free and moving boundary problems require the simultaneous solution of unknown field variables and the boundaries of the domains on which these variables are defined. There are many technologically important processes that lead to moving boundary problems associated with fluid surfaces and solid-fluid boundaries. These include crystal growth, metal alloy and glass solidification, melting and name propagation. The directional solidification of semi-conductor crystals by the Bridgman-Stockbarger method is a typical example of such a complex process. A numerical model of this growth method must solve the appropriate heat, mass and momentum transfer equations and determine the location of the melt-solid interface. In this work, a Chebyshev pseudospectra collocation method is adapted to the problem of directional solidification. Implementation involves a solution algorithm that combines domain decomposition, finite-difference preconditioned conjugate minimum residual method and a Picard type iterative scheme.

  19. Novel Direct Steelmaking by Combining Microwave, Electric Arc, and Exothermal Heating Technologies

    SciTech Connect

    Dr. Xiaodi Huang; Dr. J. Y. Hwang

    2005-03-28

    Steel is a basic material broadly used by perhaps every industry and individual. It is critical to our nation's economy and national security. Unfortunately, the American steel industry is losing competitiveness in the world steel production field. There is an urgent need to develop the next generation of steelmaking technology for the American steel industry. Direct steelmaking through the combination of microwave, electric arc, and exothermal heating is a revolutionary change from current steelmaking technology. This technology can produce molten steel directly from a shippable agglomerate, consisting of iron oxide fines, powdered coal, and ground limestone. This technology is projected to eliminate many current intermediate steelmaking steps including coking, pellet sintering, blast furnace (BF) ironmaking, and basic oxygen furnace (BOF) steelmaking. This technology has the potential to (a) save up to 45% of the energy consumed by conventional steelmaking; (b) dramatically reduce the emission of CO{sub 2}, SO{sub 2}, NO{sub x}, VOCs, fine particulates, and air toxics; (c) substantially reduce waste and emission control costs; (d) greatly lower capital cost; and (e) considerably reduce steel production costs. This technology is based on the unique capability of microwaves to rapidly heat steelmaking raw materials to elevated temperature, then rapidly reduce iron oxides to metal by volumetric heating. Microwave heating, augmented with electric arc and exothermal reactions, is capable of producing molten steel. This technology has the components necessary to establish the ''future'' domestic steel industry as a technology leader with a strong economically competitive position in world markets. The project goals were to assess the utilization of a new steelmaking technology for its potential to achieve better overall energy efficiency, minimize pollutants and wastes, lower capital and operating costs, and increase the competitiveness of the U.S. steel industry. The

  20. Direct heating of a laser-imploded core using ultraintense laser LFEX

    NASA Astrophysics Data System (ADS)

    Kitagawa, Y.; Mori, Y.; Ishii, K.; Hanayama, R.; Nishimura, Y.; Okihara, S.; Nakayama, S.; Sekine, T.; Takagi, M.; Watari, T.; Satoh, N.; Kawashima, T.; Komeda, O.; Hioki, T.; Motohiro, T.; Azuma, H.; Sunahara, A.; Sentoku, Y.; Arikawa, Y.; Abe, Y.; Miura, E.; Ozaki, T.

    2017-07-01

    A CD shell was preimploded by two counter-propagating green beams from the GEKKO laser system GXII (based at the Institute of Laser Engineering, Osaka University), forming a dense core. The core was predominantly heated by energetic ions driven by the laser for fast-ignition-fusion experiment, an extremely energetic ultrashort pulse laser, that is illuminated perpendicularly to the GXII axis. Consequently, we observed the D(d, n)3 He-reacted neutrons (DD beam-fusion neutrons) at a yield of 5× {{10}8} n/4π sr. The beam-fusion neutrons verified that the ions directly collided with the core plasma. Whereas the hot electrons heated the whole core volume, the energetic ions deposited their energies locally in the core. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with a yield of 6× {{10}7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. The shell-implosion dynamics (including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions) can be explained by the one-dimensional hydrocode STAR 1D. Meanwhile, the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions were well-predicted by the two-dimensional collisional particle-in-cell code. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high-gain fusion.

  1. The direct application of geothermal energy to provide process heat in Guatemala

    SciTech Connect

    Altseimer, J.H.; Edeskuty, F.J.

    1987-09-01

    One part of an energy and resource development program in Central America is a geothermal process heat project in Guatemala. The feasibility of the direct heat application depends upon the production characteristics and reliability of the geothermal source. Other factors are the distance from the heat source, quantity of use, and capacity factor of the use facilities. Favorable conditions would be distances of under 5 km, heat requirements approximately equal to the well capacity, and high capacity factors (say 60% or higher) in the industrial plants. Depending upon the values of these factors, energy costs of less than $1.00/million Btus to greater than $5.00/million Btus have been estimated. This can be compared to about $5.00/million Btus for petroleum-based fuels in Guatemala in mid 1987. A survey was made of existing industries in the Amatitlan and Zunil geothermal areas. In both Amatitlan and Zunil the existing industries are spread out over an area too large to be called an optimum. The most promising situation for an industrial park development is at Amatitlan, except that proven production wells are not yet available. At Zunil, production wells exist, but a diverse nearby industrial base does not. However, both of these two areas are sufficiently promising to merit further development. Consequently, a demonstration project is underway aimed at the ultimate establishment of an agricultural processing center at Zunil. This center would have the capability to process agricultural products by dehydration, freezing, and cold storage. 2 refs., 4 figs., 2 tabs.

  2. Achievement of Core Conditions for Alpha Heating in Direct-Drive Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Bose, A.; Woo, K. M.; Betti, R.; Mangino, D.; Christopherson, A. R.; Theobald, W.; Campbell, E. M.; McCrory, R. L.; Regan, S. P.; Goncharov, V. N.; Sangster, T. C.; Forrest, C. J.; Glebov, V. Yu.; Knauer, J. P.; Marshall, F. J.; Stoeckl, C.; Nora, R.; Frenje, J. A.; Gatu Johnson, M.; Shvarts, D.

    2016-10-01

    It is shown for the first time that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available at the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion extrapolated to a 1.9-MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions. This conclusion is reached using an analytic scaling as well as direct numerical simulations of energy-scaled targets. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  3. Direct Numerical Simulation of Turbulent Heat Transfer Behind a Rectangular Orifice

    NASA Astrophysics Data System (ADS)

    Makino, Soihiro; Iwamoto, Kaoru; Kawamura, Hiroshi

    Direct numerical simulation of turbulent heat transfer with a rectangular orifice has been performed for Reτ0(=uτ0δ⁄ν) = 300, where uτ0 is the friction velocity calculated from the mean pressure gradient imposed to drive the flow, δ the channel half width and ν the kinematic viscosity. The Prandtl number is 0.71. The ratio of slit height to channel height is assumed to be β=0.3,0.4,0.5,0.6 and 0.7. For β=0.3-0.6, the mean flow becomes asymmetric in the wall-normal direction by the Coanda effect behind the orifice. In the case of β=0.7, however, the mean flow is symmetry. The Nusselt number profiles over the bottom and top walls are different significantly for the asymmetric cases. Large-scale Kelvin-Helmholtz(K-H) vortices are generated at the orifice edges. An entrainment process is observed in the temperature field around these vortices. Subsequently, these K-H vortices become deformed and break up into disordered small-scale structures in the shear layers behind the orifice. In this scenario, the turbulent transport is promoted in the temperature field. In addition, the separation, the reattachment and also the contraction effects are discussed on the profiles of the mean temperature, the temperature variance and the turbulent heat fluxes.

  4. Dirac fermion heating, current scaling, and direct insulator-quantum Hall transition in multilayer epitaxial graphene.

    PubMed

    Liu, Fan-Hung; Hsu, Chang-Shun; Chuang, Chiashain; Woo, Tak-Pong; Huang, Lung-I; Lo, Shun-Tsung; Fukuyama, Yasuhiro; Yang, Yanfei; Elmquist, Randolph E; Liang, Chi-Te

    2013-08-22

    We have performed magnetotransport measurements on multilayer epitaxial graphene. By increasing the driving current I through our graphene devices while keeping the bath temperature fixed, we are able to study Dirac fermion heating and current scaling in such devices. Using zero-field resistivity as a self thermometer, we are able to determine the effective Dirac fermion temperature (TDF) at various driving currents. At zero field, it is found that TDF ∝ I≈1/2. Such results are consistent with electron heating in conventional two-dimensional systems in the plateau-plateau transition regime. With increasing magnetic field B, we observe an I-independent point in the measured longitudinal resistivity ρxx which is equivalent to the direct insulator-quantum Hall (I-QH) transition characterized by a temperature-independent point in ρxx. Together with recent experimental evidence for direct I-QH transition, our new data suggest that such a transition is a universal effect in graphene, albeit further studies are required to obtain a thorough understanding of such an effect.

  5. Manual for the thermal and hdyraulic design of direct contract spray columns for use in extracting heat from geothermal brines

    NASA Astrophysics Data System (ADS)

    Jacobs, H. R.

    1985-06-01

    This report outlines the current methods being used in the thermal and hydraulic design of spray column type, direct contact heat exchangers. It provides appropriate referenced equations for both preliminary design and detailed performance. The design methods are primarily empirical and are applicable for use in the design of such units for geothermal application and for application with solar ponds. Methods for design, for both preheater and boiler sections of the primary heat exchangers, for direct contact binary powers plants are included.

  6. Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

    NASA Astrophysics Data System (ADS)

    Morita, Shin-ichi; Hayamizu, Yasutaka; Horibe, Akihiko; Haruki, Naoto; Inaba, Hideo

    2013-04-01

    Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ˜ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

  7. Heating mode transition in a hybrid direct current/dual-frequency capacitively coupled CF{sub 4} discharge

    SciTech Connect

    Zhang, Quan-Zhi; Wang, You-Nian; Bogaerts, Annemie

    2014-06-14

    Computer simulations based on the particle-in-cell/Monte Carlo collision method are performed to study the plasma characteristics and especially the transition in electron heating mechanisms in a hybrid direct current (dc)/dual-frequency (DF) capacitively coupled CF{sub 4} discharge. When applying a superposed dc voltage, the plasma density first increases, then decreases, and finally increases again, which is in good agreement with experiments. This trend can be explained by the transition between the four main heating modes, i.e., DF coupling, dc and DF coupling, dc source dominant heating, and secondary electron dominant heating.

  8. Geothermal direct-heat utilization assistance: Federal assistance program. Quarterly project progress report, October--December 1995

    SciTech Connect

    1996-02-01

    The report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the first quarter of FY-96. It describes 90 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment and resources. Research activities are summarized on low-temperature resource assessment, geothermal district heating system cost evaluation and silica waste utilization project. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, development of a webpage, and progress monitor reports on geothermal resources and utilization.

  9. Discovery of a Novel Alginate Lyase from Nitratiruptor sp. SB155-2 Thriving at Deep-sea Hydrothermal Vents and Identification of the Residues Responsible for Its Heat Stability.

    PubMed

    Inoue, Akira; Anraku, Moe; Nakagawa, Satoshi; Ojima, Takao

    2016-07-22

    Extremophiles are expected to represent a source of enzymes having unique functional properties. The hypothetical protein NIS_0185, termed NitAly in this study, was identified as an alginate lyase-homolog protein in the genomic database of ϵ-Proteobacteria Nitratiruptor sp. SB155-2, which was isolated from deep-sea hydrothermal vents at a water depth of 1,000 m. Among the characterized alginate lyases in the polysaccharide lyase family 7 (PL-7), the amino acid sequence of NitAly showed the highest identity (39%) with that of red alga Pyropia yezoensis alginate lyase PyAly. Recombinant NitAly (rNitAly) was successfully expressed in Escherichia coli Purified rNitAly degraded alginate in an endolytic manner. Among alginate block types, polyM was preferable to polyG and polyMG as a substrate, and its end degradation products were mainly tri-, tetra-, and penta-saccharides. The optimum temperature and pH values were 70 °C and around 6, respectively. A high concentration of NaCl (0.8-1.4 m) was required for maximum activity. In addition, a 50% loss of activity was observed after incubation at 67 °C for 30 min. Heat stability was decreased in the presence of 5 mm DTT, and Cys-80 and Cys-232 were identified as the residues responsible for heat stability but not lyase activity. Introducing two cysteines into PyAly based on homology modeling using Pseudomonas aeruginosa alginate lyase PA1167 as the template enhanced its heat stability. Thus, NitAly is a functional alginate lyase, with its unique optimum conditions adapted to its environment. These insights into the heat stability of NitAly could be applied to improve that of other PL-7 alginate lyases.

  10. Effects of latent heating on driving atmospheric circulation of brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Latent heating from condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal atmospheric conditions of BDs (hot and thus with relatively short radiative timescale), latent heating alone by silicate vapor is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with relatively long radiative timescale, which may be the case for cooler bodies, tend to maintain an active hydrological cycle and develop zonal jets. Once condensation happens, storms driven by

  11. Serpentinization-assisted deformation processes and characterization of hydrothermal fluxes at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Genc, Gence

    Seafloor hydrothermal systems play a significantly important role in Earth’s energy and geochemical budgets and support the existence and development of complex biological ecosystems by providing nutrient and energy to microbial and macrafaunal ecosystems through geochemical fluxes. Heat output and fluid flow are key parameters which characterize hydrothermal systems at oceanic spreading centers by constraining models of hydrothermal circulation. Although integrated measurements of heat flux in plumes are critically important as well, quantification of heat flux at discrete sources (vent orifices versus patches of seafloor shimmering diffuse flow) from direct measurements is particularly essential for examining the partitioning of heat flow into focused and diffuse components of venting and determining geochemical fluxes from these two modes of flow. Hydrothermal heat output also constrains the permeability of young oceanic crust and thickness of the conductive boundary layer that separates magmatic heat source from overlying hydrothermal circulation. This dissertation will be fundamentally focused on three main inter-connected topics: (1) the design and development of direct high- or low-temperature heat flow measuring devices for hydrothermal systems, (2) the collection of new heat output results on four cruises between 2008 and 2010 at several distinct hydrothermal sites along mid-ocean ridges (MORs) to estimate total heat output from individual vent structures such as Dante, Hulk or the whole vent field (e.g., Main Endeavour Vent Field (MEF)), the partitioning between focused and diffuse hydrothermal venting in MEF, and determination of initial estimates of geochemical flux from diffuse hydrothermal fluids which may be influenced by the activity in subsurface biosphere and finally (3) the deformation and uplift associated with serpentinization at MORs and subduction zones. Despite extensive efforts spent for the last couple of decades on heat flow measurement

  12. Hydrothermal systems in small ocean planets.

    PubMed

    Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

    2007-12-01

    We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).

  13. Dynamic behavior of Kilauea Volcano and its relation to hydrothermal systems and geothermal energy

    USGS Publications Warehouse

    Kauhikaua, Jim; Moore, R.B.; ,

    1993-01-01

    Exploitation of hydrothermal systems on active basaltic volcanoes poses some unique questions about the role of volcanism and hydrothermal system evolution. Volcanic activity creates and maintains hydrothermal systems while earthquakes create permeable fractures that, at least temporarily, enhance circulation. Magma and water, possibly hydrothermal water, can interact violently to produce explosive eruptions. Finally, we speculate on whether volcanic behavior can be affected by high rates of heat extraction.

  14. Assessing the effect of wind speed/direction changes on urban heat island intensity of Istanbul.

    NASA Astrophysics Data System (ADS)

    Perim Temizoz, Huriye; Unal, Yurdanur S.

    2017-04-01

    Assessing the effect of wind speed/direction changes on urban heat island intensity of Istanbul. Perim Temizöz, Deniz H. Diren, Cemre Yürük and Yurdanur S. Ünal Istanbul Technical University, Department of Meteorological Engineering, Maslak, Istanbul, Turkey City or metropolitan areas are significantly warmer than the outlying rural areas since the urban fabrics and artificial surfaces which have different radiative, thermal and aerodynamic features alter the surface energy balance, interact with the regional circulation and introduce anthropogenic sensible heat and moisture into the atmosphere. The temperature contrast between urban and rural areas is most prominent during nighttime since heat is absorbed by day and emitted by night. The intensity of the urban heat island (UHI) vary considerably depending on the prevailent meteorological conditions and the characteristics of the region. Even though urban areas cover a small fraction of Earth, their climate has greater impact on the world's population. Over half of the world population lives in the cities and it is expected to rise within the coming decades. Today almost one fifth of the Turkey's population resides in Istanbul with the percentage expected to increase due to the greater job opportunities compared to the other cities. Its population has been increased from 2 millions to 14 millions since 1960s. Eventually, the city has been expanded tremendously within the last half century, shifting the landscape from vegetation to built up areas. The observations of the last fifty years over Istanbul show that the UHI is most pronounced during summer season. The seasonal temperature differences between urban and suburban sites reach up to 3 K and roughly haft degree increase in UHI intensity is observed after 2000. In this study, we explore the possible range of heat load and distribution over Istanbul for different prevailing wind conditions by using the non-hydrostatic MUKLIMO3 model developed by DWD

  15. Integrated simulations of implosion, electron transport, and heating for direct-drive fast-ignition targets

    SciTech Connect

    Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2009-05-15

    A thorough understanding of future integrated fast-ignition experiments combining compression and heating of high-density thermonuclear fuel requires hybrid (fluid+particle) simulations of the implosion and ignition process. Different spatial and temporal scales need to be resolved to model the entire fast-ignition experiment. The two-dimensional (2D) axisymmetric hydrocode DRACO[P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] and the 2D/three-dimensional hybrid particle-in-cell code LSP[D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] have been integrated to simulate the implosion and heating of direct-drive, fast-ignition fusion targets. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. The results from integrated simulations of cone-in-shell CD targets designed for fast-ignition experiments on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); C. Stoeckl et al., Fusion Sci. Technol. 49, 367 (2006)] are presented. Target heating and neutron yields are computed. The results from LSP simulations of electron transport in solid-density plastic targets are also presented. They confirm an increase in the electron divergence angle with the laser intensity in the current experiments. The self-generated resistive magnetic field is found to collimate the hot-electron beam and increase the coupling efficiency of hot electrons with the target. Resistive filamentation of the hot-electron beam is also observed.

  16. Integrated Simulations of Implosion, Electron Transport, and Heating for Direct-Drive Fast-Ignition Targets

    SciTech Connect

    Solodov, A.A.; Anderson, K.S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J.A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

    2009-04-28

    A thorough understanding of future integrated fast-ignition experiments combining compression and heating of high-density thermonuclear fuel requires hybrid (fluid+particle) simulations of the implosion and ignition process. Different spatial and temporal scales need to be resolved to model the entire fast-ignition experiment. The two-dimensional (2D) axisymmetric hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] and the 2D/three-dimensional hybrid particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] have been integrated to simulate the implosion and heating of direct-drive, fast-ignition fusion targets. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. The results from integrated simulations of cone-in-shell CD targets designed for fast-ignition experiments on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); C. Stoeckl et al., Fusion Sci. Technol. 49, 367 (2006)] are presented. Target heating and neutron yields are computed. The results from LSP simulations of electron transport in solid-density plastic targets are also presented. They confirm an increase in the electron divergence angle with the laser intensity in the current experiments. The self-generated resistive magnetic field is found to collimate the hot-electron beam and increase the coupling efficiency of hot electrons with the target. Resistive filamentation of the hot-electron beam is also observed.

  17. Physical factors determining the fraction of stored energy recoverable from hydrothermal convection systems and conduction-dominated areas

    USGS Publications Warehouse

    Nathenson, Manuel

    1975-01-01

    This report contains background analyses for the estimates of Nathenson and Muffler (1975) of geothermal resources in hydrothermal convection systems and conduction-dominated areas. The first section discusses heat and fluid recharge potential of geothermal reservoirs. The second section analyzes the physical factors that determine the fraction of stored energy obtainable at the surface from a geothermal reservoir. Conversion of heat to electricity and the use of geothermal energy for direct-heating applications are discussed in the last two sections. Nathenson, Manuel, and Muffler, L.J.P., 1975, Geothermal resources in hydrothermal convection systems and conduction dominated areas, in White, D.E., and Williams, D.L., eds., Assessment of the Geothermal Resources of the United States--1975: U.S. Geological Survey Circular 726, p. 104-121, available at http://pubs.er.usgs.gov/usgspubs/cir/cir726

  18. Powering hydrothermal activity on Enceladus

    NASA Astrophysics Data System (ADS)

    Tobie, Gabriel; Choblet, Gael; Sotin, Christophe; Behounkova, Marie; Cadek, Ondrej; Postberg, Frank; Soucek, Ondrej

    2017-04-01

    A series of evidence gathered by the Cassini spacecraft indicates that the intense activity at the South Pole of Saturn's moon Enceladus is related to a subsurface salty water reservoir associated with seafloor hydrothermal activity (Hsu et al. 2015, Waite et al. 2017). The observation of an elevated libration implies that this reservoir is global with a thin ice shell (20-25 km in average (Thomas et al. 2016) and < 5 km in the South Polar Terrain, SPT (Cadek et al. 2016)). Such a structure requires a huge heat power and a mechanism to focus the release of heat in the SPT, unexplained by previous models. Here we investigate heat generation by tidal friction in the porous core and simulate heat transport by water flow for core porosities consistent with Cassini gravity data (Iess et al. 2014). We demonstrate that, for effective viscosity and permeability values typical of water-saturated terrestrial rock analogues, more than 20 GW can be generated in the core, which can maintain a global liquid ocean and power hydrothermal activity at the seafloor. By performing 3D simulations of water flow in a tidally-heated porous rock matrix, we show that heat is extracted from the core in the form of focused outflows of hot water (> 90 °C) mostly in the polar regions, explaining strongly localized ice shell thinning. Owing to strong dissipation in Saturn (Lainey et al. 2017), we show that circulation of hot waters in the core may last at least 20-25 million years and that 10 to 100% of the oceanic volume may be processed in the core at temperature higher than 90°C on this timescale. Whether this has been sufficient for the emergence of life can be explored by future spacecraft missions (Mitri et al., this meeting; Lunine et al. 2017).

  19. Heat transfer and pressure drop in a compact pin-fin heat exchanger with pin orientation at 18 deg to the flow direction

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1991-01-01

    The heat transfer and pressure drop characteristics of a novel, compact heat exchanger in helium gas were measured at 3.5 MPa and Reynolds numbers of 450 to 12,000. The pin-fin specimen consisted of pins, 0.51 mm high and spaced 2.03 mm on centers, spanning a channel through which the helium flows; the angle of the row of pins to the flow direction was 18 deg. The specimen was radiatively heated on the top side at heat fluxes up to 74 W/sq cm and insulated on the back side. Correlations were developed for the friction factor and Nusselt number. The Nusselt number compares favorably to those of past studies of staggered pin-fins, when the measured temperatures are extrapolated to the temperature of the wall-fluid interface.

  20. Direct contact liquid-liquid heat exchanger for solar heated and cooled buildings. Final report, January 1, 1979-May 30, 1980

    SciTech Connect

    Karaki, S.; Brothers, P.

    1980-06-01

    The technical and economic feasibility of using a direct contact liquid-liquid heat exchanger (DCLLHE) storage unit in a solar heating and cooling system is established. Experimental performance data were obtained from the CSU Solar House I using a DCLLHE for both heating and cooling functions. A simulation model for the system was developed. The model was validated using the experimental data and applied in five different climatic regions of the country for a complete year. The life-cycle cost of the system was estimated for each application. The results are compared to a conventional solar system, using a standard shell-and-tube heat exchanger. It is concluded that while thare is a performance advantage with a DCLLHE system over a conventional solar system, the advantage is not sufficiently large to overcome slightly higher capital and operating costs for the DCLLHE system.

  1. Investigation on microwave heating for direct leaching of chalcopyrite ores and concentrates

    NASA Astrophysics Data System (ADS)

    Onol, Kubra; Saridede, Muhlis Nezihi

    2013-03-01

    The use of microwave energy in materials processing is a relatively new development presenting numerous advantages because of the rapid heating feature. Microwave technology has great potential to improve the extraction efficiency of metals in terms of both a reduction in required leaching time and an increase in the recovery of valuable metals. This method is especially pertinent in view of the increased demand for environment-friendly processes. In the present study, the influence of microwave heating on the direct leaching of chalcopyrite ores and concentrates were investigated. The results of microwave leaching experiments were compared with those obtained under conventional conditions. During these processes, parameters such as leaching media, temperature, and time have been worked to determine the optimum conditions for proper copper dissolution. Experimental results show that microwave leaching is more efficient than conventional leaching. The optimum leaching conditions for microwave leaching are the solid-to-liquid ratio of 1:100 g/mL, the temperature of 140°C, the solution of 0.5 M H2SO4 + 0.05 M Fe2(SO4)3, and the time of 1 h.

  2. The probability of containment failure by direct containment heating in surry

    SciTech Connect

    Pilch, M.M.; Allen, M.D.; Bergeron, K.D.; Tadios, E.L.; Stamps, D.W.; Spencer, B.W.; Quick, K.S.; Knudson, D.L.

    1995-05-01

    In a light-water reactor core melt accident, if the reactor pressure vessel (RPV) fails while the reactor coolant system (RCS) at high pressure, the expulsion of molten core debris may pressurize the reactor containment building (RCB) beyond its failure pressure. A failure in the bottom head of the RPV, followed by melt expulsion and blowdown of the RCS, will entrain molten core debris in the high-velocity steam blowdown gas. This chain of events is called a high-pressure melt ejection (HPME). Four mechanisms may cause a rapid increase in pressure and temperature in the reactor containment: (1) blowdown of the RCS, (2) efficient debris-to-gas heat transfer, (3) exothermic metal-steam and metal-oxygen reactions, and (4) hydrogen combustion. These processes, which lead to increased loads on the containment building, are collectively referred to as direct containment heating (DCH). It is necessary to understand factors that enhance or mitigate DCH because the pressure load imposed on the RCB may lead to early failure of the containment.

  3. Heat of supersaturation-limited amyloid burst directly monitored by isothermal titration calorimetry

    PubMed Central

    Ikenoue, Tatsuya; Lee, Young-Ho; Kardos, József; Yagi, Hisashi; Ikegami, Takahisa; Naiki, Hironobu; Goto, Yuji

    2014-01-01

    Amyloid fibrils form in supersaturated solutions via a nucleation and growth mechanism. Although the structural features of amyloid fibrils have become increasingly clearer, knowledge on the thermodynamics of fibrillation is limited. Furthermore, protein aggregation is not a target of calorimetry, one of the most powerful approaches used to study proteins. Here, with β2-microglobulin, a protein responsible for dialysis-related amyloidosis, we show direct heat measurements of the formation of amyloid fibrils using isothermal titration calorimetry (ITC). The spontaneous fibrillation after a lag phase was accompanied by exothermic heat. The thermodynamic parameters of fibrillation obtained under various protein concentrations and temperatures were consistent with the main-chain dominated structural model of fibrils, in which overall packing was less than that of the native structures. We also characterized the thermodynamics of amorphous aggregation, enabling the comparison of protein folding, amyloid fibrillation, and amorphous aggregation. These results indicate that ITC will become a promising approach for clarifying comprehensively the thermodynamics of protein folding and misfolding. PMID:24753579

  4. Direct numerical simulation of heat transfer in a spatially developing turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Li, Dong; Luo, Kun; Fan, Jianren

    2016-10-01

    Direct numerical simulation has been performed to investigate heat transfer in a zero-pressure-gradient spatially developing turbulent boundary layer with realistic thermal inflow boundary conditions. The temperature is considered as a passive scalar and the molecular Prandtl number is set to be 0.71. The turbulence statistics for both the velocity and temperature fields show good agreement with previous numerical and experimental data in the literature. The present study provides a valuable database for the spatially developing turbulent thermal boundary layer over a wide range of Reynolds numbers from Reθ = 1100 to 1940. The simulation results indicate that both the peak value and peak location of the streamwise velocity fluctuation grow slightly with increasing Reynolds number, same as those of the temperature fluctuation. The relationship between the streamwise velocity and temperature fluctuations has been examined and a strong correlation is observed in the vicinity of the wall. With increasing distance from the wall, however, the degree of correlation significantly decreases. In addition, the difference between the turbulent velocity and temperature fields is also analysed by investigating the mechanisms of heat and momentum transport in boundary layer flow.

  5. Review of tokamak experiments on direct electron heating and current drive with fast waves

    SciTech Connect

    Pinsker, R.I.

    1993-12-01

    Results from tokamak experiments on direct electron interaction with the compressional Alfven wave ({open_quote}fast wave{close_quote}) are reviewed. Experiments aimed at electron heating as well as those in which fast wave electron current drive was investigated are discussed. A distinction is drawn between experiments employing the lower hybrid range of frequencies, where both the lower hybrid wave ({open_quote}slow wave{close_quote}) and the fast wave can propagate in much of the plasma, and those experiments using the fast wave in the range of moderate to high ion cyclotron harmonics, where only the fast wave can penetrate to the plasma core. Most of the early tokamak experiments were in the lower hybrid frequency regime, and the observed electron interaction appeared to be very similar to that obtained with the slow wave at the same frequency. In particular, electron interaction with the fast wave was observed only below a density limit nearly the same as the well known slow wave density limit. In the more recent lower frequency fast wave experiments, electron interaction (heating and current drive) is observed at the center of the discharge, where slow waves are not present.

  6. METEORIC-HYDROTHERMAL SYSTEMS.

    USGS Publications Warehouse

    Criss, Robert E.; Taylor, Hugh P.

    1986-01-01

    This paper summarizes the salient characteristics of meteoric-hydrothermal systems, emphasing the isotopic systematics. Discussions of permeable-medium fluid dynamics and the geology and geochemistry of modern geothermal systems are also provided, because they are essential to any understanding of hydrothermal circulation. The main focus of the paper is on regions of ancient meteoric-hydrothermal activity, which give us information about the presently inaccessible, deep-level parts of modern geothermal systems. It is shown oxygen and hydrogen isotopes provide a powerful method to discover and map fossil hydrothermal systems and to investigate diverse associated aspects of rock alteration and ore deposition.

  7. Direct use of geothermal energy, Elko, Nevada district heating. Final report

    SciTech Connect

    Lattin, M.W.; Hoppe, R.D.

    1983-06-01

    In early 1978 the US Department of Energy, under its Project Opportunity Notice program, granted financial assistance for a project to demonstrate the direct use application of geothermal energy in Elko, Nevada. The project is to provide geothermal energy to three different types of users: a commercial office building, a commercial laundry and a hotel/casino complex, all located in downtown Elko. The project included assessment of the geothermal resource potential, resource exploration drilling, production well drilling, installation of an energy distribution system, spent fluid disposal facility, and connection of the end users buildings. The project was completed in November 1982 and the three end users were brought online in December 1982. Elko Heat Company has been providing continuous service since this time.

  8. Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

    DOEpatents

    Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

    1987-10-16

    A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs

  9. Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

    DOEpatents

    Leung, Ka-Ngo; Gordon, Keith C.; Kippenham, Dean O.; Purgalis, Peter; Moussa, David; Williams, Malcom D.; Wilde, Stephen B.; West, Mark W.

    1989-01-01

    A large area directly heated lanthanum hexaboride (LaB.sub.6) cathode system (10) is disclosed. The system comprises a LaB.sub.6 cathode element (11) generally circular in shape about a central axis. The cathode element (11) has a head (21) with an upper substantially planar emission surface (23), and a lower downwardly and an intermediate body portion (26) which diminishes in cross-section from the head (21) towards the base (22) of the cathode element (11). A central rod (14) is connected to the base (22) of the cathode element (11) and extends along the central axis. Plural upstanding spring fingers (37) are urged against an outer peripheral contact surface (24) of the head end (21) to provide a mechanical and electrical connection to the cathode element (11).

  10. Progress in understanding of direct containment heating phenomena in pressurized light water reactors

    SciTech Connect

    Ginsberg, T.; Tutu, N.K.

    1988-01-01

    Progress is described in development of a mechanistic understanding of direct containment heating phemonena arising during high-pressure melt ejection accidents in pressurized water reactor systems. The experimental data base is discussed which forms the basis for current assessments of containment pressure response using current lumped-parameter containment analysis methods. The deficiencies in available methods and supporting data base required to describe major phenomena occurring in the reactor cavity, intermediate subcompartments and containment dome are highlighted. Code calculation results presented in the literature are cited which demonstrate that the progress in understanding of DCH phenomena has also resulted in current predictions of containment pressure loadings which are significantly lower than are predicted by idealized, thermodynamic equilibrium calculations. Current methods are, nonetheless, still predicting containment-threatening loadings for large participating melt masses under high-pressure ejection conditions. Recommendations for future research are discussed. 36 refs., 5 figs., 1 tab.

  11. Charge and Heat Transfer Mechanism in Directly Coupled CdSe-Metal Nanohybrids

    NASA Astrophysics Data System (ADS)

    Augustine, Anju K.; Girijavallabhan, C. P.; Nampoori, V. P. N.; Kailasnath, M.

    2015-10-01

    The charge and heat energy transfer dynamics of directly coupled mixtures of CdSe quantum dots with metal nanoparticles have been studied using thermal lens and photoluminescence (PL) techniques, respectively. The PL of such nanohybrids is found to be quenched dramatically at a particular threshold. Fluorescence decay curves of the Au-CdSe nanohybrids and Ag-CdSe nanohybrids show distinct decay channels with the fastest one associated with transfer of electrons from the CdSe portion to the metal portion. A study on the influence of this charge transfer on the thermal diffusivity with respect to the emission wavelength of quantum dots has been carried out, which could lead to the design of modern photocatalysts and solar cells constructed from nanoscale metal-semiconductor hybrids.

  12. Direct observation of resistive heating at graphene wrinkles and grain boundaries

    SciTech Connect

    Grosse, Kyle L.; Dorgan, Vincent E.; Estrada, David; Wood, Joshua D.; Vlassiouk, Ivan V; Eres, Gyula; Lyding, Joseph W; King, William P.; Pop, Eric

    2014-01-01

    We directly measure the nanometer-scale temperature rise at wrinkles and grain boundaries (GBs) in functioning graphene devices by scanning Joule expansion microscopy with 50 nm spatial and 0.2K temperature resolution. We observe a small temperature increase at select wrinkles and a large (100 K) temperature increase at GBs between coalesced hexagonal grains. Comparisons of measurements with device simulations estimate the GB resistivity (8 150 X lm) among the lowest reported for graphene grown by chemical vapor deposition. An analytical model is developed, showing that GBs can experience highly localized resistive heating and temperature rise, most likely affecting the reliability of graphene devices. Our studies provide an unprecedented view of thermal effects surrounding nanoscale defects in nanomaterials such as graphene.

  13. Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

    2014-12-01

    Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the

  14. Effect of heat treatment on the fracture behaviour of directionally solidified (gamma/gamma-prime)-alpha alloy

    NASA Technical Reports Server (NTRS)

    Sriramamurthy, A. M.; Tewari, S. N.

    1987-01-01

    An investigation is conducted into the influence of various heat treatments on the work of fracture and its relation to microstructure for a directionally solidified Ni-33Mo-5.7Al (wt pct) (gamma/gamma-prime)-alpha alloy. The jagged crack propagation observed is due to delamination of the ligaments and associated plastic deformation. Fracture behavior is examined with respect to alloy microstructures and load-deflection curves. The four heat-treatment conditions considered are: (1) as-directionally solidified, (2) solutionized, (3) directionally solidified and thermally cycled, and (4) solutionized and thermally cycled.

  15. 230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Yang, Weifang; Tao, Chunhui; Li, Huaiming; Liang, Jin; Liao, Shili; Long, Jiangping; Ma, Zhibang; Wang, Lisheng

    2017-06-01

    Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28'E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230Th/238U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is <0.02 mm/yr. This study is the first to estimate the growth rate of chimneys in the SWIR. The maximum age of the relict chimney in Duanqiao hydrothermal filed is close to that of the chimneys from Mt. Jourdanne (70 kyrs). The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

  16. 230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Yang, Weifang; Tao, Chunhui; Li, Huaiming; Liang, Jin; Liao, Shili; Long, Jiangping; Ma, Zhibang; Wang, Lisheng

    2016-11-01

    Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28'E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230Th/238U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is <0.02 mm/yr. This study is the first to estimate the growth rate of chimneys in the SWIR. The maximum age of the relict chimney in Duanqiao hydrothermal filed is close to that of the chimneys from Mt. Jourdanne (70 kyrs). The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

  17. Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe) including direct flow observation

    NASA Astrophysics Data System (ADS)

    Andros, F. E.

    1980-12-01

    The two phase closed thermosyphon is a heat transfer device capable of transferring large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. For small and intermediate fill quantities, four basic flow regimes were observed in the evaporator section of the thermosyphon during steady state operation with Freon 113 and ethanol: (1) a smooth continuous film with surface evaporation; (2) the breakdown of the smooth continuous film into a series of rivulets; (3) a wavy film with unstable rivulets; and (4) a wavy film with bubble nucleation occurring in the unstable rivulets. A fifth condition which was observed with all fluids was a dry out (heat transfer limit) where some portion of the evaporator ceases to be cooled effectively by the falling film and rivulets, resulting in a wall temperature excursion or critical condition. Three types of dry out were observed. In addition to the visual device used, a stainless steel tubular opaque device was fabricated and is heat transfer characteristics evaluated using Freon 113 as a working fluid.

  18. Thermal stress models for hydrothermal circulation, and relation to microseismicity near 9 degrees 50'N along the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Godfrey, Karen E.

    2011-12-01

    Hydrothermal circulation at mid-ocean ridges plays an important role in the interaction between oceanic lithosphere and the overlying ocean. Changes in fluid flux within hydrothermal systems may directly impact ocean circulation, temperature, and chemistry, and hence the lives of biological organisms in hydrothermal vent environments. The permeability structure within a hydrothermal environment is an important control on fluid flow throughout the system. Common suggestions for mechanisms that might increase permeability within the system include thermal cracking due to contraction of the hot rock from interaction with cold seawater, fluid pressure of the water moving through the rock, tectonics, or tidal forces. Additional factors such as mineral precipitation can decrease permeability in the system, further complicating the permeability structure. Though there are many factors to consider within a hydrothermal system, few quantitative studies of these cracking mechanisms exist. This study examines the role of thermal cracking near hydrothermal vents via a numerical model created in Matlab. Flow was modeled using the Laplace equation, and the heat transfer equation was used to determine temperature differences in the rock, which lead to thermal cracking. The numerical results were compared with microearthquakes observed by Tolstoy et al. (2008) near a hydrothermal vent field along the East Pacific Rise. The model suggests that thermal cracking does occur, and this cracking occurs within the area of microearthquakes observed. Though thermal cracking is important for increasing permeability within the system, there are no obvious spatial or temporal trends within the earthquake data that support a direct relation between the modeled thermal cracking and observed earthquakes. It is likely that the observed earthquakes are due to a combination of cracking mechanisms, such as cracking due to fluid pressure, tectonics, or tides, in addition to the modeled thermal

  19. Overview of direct use R&D at the Geo-Heat Center

    SciTech Connect

    Lienau, P.J.

    1997-12-31

    Geo-Heat Center research, during the past year, on geothermal district heating and greenhouse projects is intended to improve the design and cost effectiveness of these systems. The largest geothermal district heating system in the U.S., proposed at Reno, is describe and is one of 271 collocated sites in western states could benefit from the research. The geothermal district heating research investigated a variety of factors that could reduce development cost for residential areas. Many greenhouse operators prefer the {open_quotes}bare tube{close_quotes} type heating system. As facilities using these types of heating systems expand they could benefit from peaking with fossil fuels. It is possible to design a geothermal heating system for only 60% of the peak heat loss of a greenhouse and still meet over 90% of the annual heat energy needs of the structure. The design and cost effectiveness of this novel approach is summarized.

  20. Nuclear reactor melt-retention structure to mitigate direct containment heating

    DOEpatents

    Tutu, Narinder K.; Ginsberg, Theodore; Klages, John R.

    1991-01-01

    A light water nuclear reactor melt-retention structure to mitigate the extent of direct containment heating of the reactor containment building. The structure includes a retention chamber for retaining molten core material away from the upper regions of the reactor containment building when a severe accident causes the bottom of the pressure vessel of the reactor to fail and discharge such molten material under high pressure through the reactor cavity into the retention chamber. In combination with the melt-retention chamber there is provided a passageway that includes molten core droplet deflector vanes and has gas vent means in its upper surface, which means are operable to deflect molten core droplets into the retention chamber while allowing high pressure steam and gases to be vented into the upper regions of the containment building. A plurality of platforms are mounted within the passageway and the melt-retention structure to direct the flow of molten core material and help retain it within the melt-retention chamber. In addition, ribs are mounted at spaced positions on the floor of the melt-retention chamber, and grid means are positioned at the entrance side of the retention chamber. The grid means develop gas back pressure that helps separate the molten core droplets from discharged high pressure steam and gases, thereby forcing the steam and gases to vent into the upper regions of the reactor containment building.

  1. Heat transfer and pressure drop measurements in an air/molten salt direct-contact heat exchanger

    SciTech Connect

    Bohn, M.S.

    1988-11-01

    This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610-mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440{degree}C and air inlet temperatures of approximately 230{degree}C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/m{sup 2} s air flow and 6 to 18 kg/m{sup 2} s salt flow, the data agree with the model within 22% standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18% standard deviation over the range of column pressure drop from 40 to 1250 Pa/m. 25 refs., 7 figs., 2 tabs.

  2. Heat flow in the Kenya rift zone

    NASA Astrophysics Data System (ADS)

    Wheildon, J.; Morgan, Paul; Williamson, K. H.; Evans, T. R.; Swanberg, C. A.

    1994-09-01

    An understanding of the processes of continental rifting is fundamental to understanding the evolution of the continents. Considerable evidence exists to suggest that continental rift zones are associated with high heat flow and elevated lithospheric geotherms, but direct heat-flow measurements from young rifts do not clearly define surface heat-flow anomalies associated with deep-seated thermal processes in these rifts. The first detailed compilation of heat-flow data from the Neogene Kenya rift is presented here. Heat-flow data are presented from traditional heat-flow determinations in water drill-holes, from bottom-hole-temperature measurements in oil wells, and from heat-flow estimates from groundwater silica data. These data define generally low heat flow on the flanks of the Kenya rift, with high, but variable heat flow on the rift floor. There is a spatial association among high heat-flow values, Quaternary volcanism and faulting, and hydrothermal manifestations on the rift floor. We interpret these results to suggest that any deep-seated thermal anomaly associated with the Kenya rift has not yet been conducted to the surface. The high heat-flow values are interpreted to result from heat advected into the axial rift zone with local redistribution of this heat by hydrothermal convection. Normal to moderately high heat flow was measured in eastern Kenya between the rift zone and the coast. The regional heat flow in eastern Kenya is interpreted to be normal, with local shallow modification by groundwater flow eastward from the Kenya dome. These interpretations support a model of relatively young evolution of the asthenospheric anomaly beneath the Kenya rift zone, with the age of heating of the mantle at the Mono no older than about 10 Ma.

  3. Magnetic Structure of Backarc Spreading Axis with Hydrothermal Vents; the Southern Mariana Trough

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Okino, K.; Mochizuki, N.; Honsho, C.; Szitkar, F.; Dyment, J.; Nakamura, K.

    2012-12-01

    Seafloor hydrothermal systems are important in relation to global heat and chemical fluxes as well as habitat of microbial communities. The substantial variation of hydrothermal systems in various tectonic settings has important implications for the magnetic structure of oceanic crust. It has been very difficult to detect the geophysical signature of hydrothermal systems from sea-surface data because the small scale of hydrothermal systems is below the limit of resolution. The advance of near-bottom survey methods using a submersible, deep-tow, ROV and AUV has made possible high-resolution geophysical mapping around hydrothermal areas. Near-bottom magnetic surveys can provide direct information on the magnetization of the shallower oceanic crust, implying hydrothermal alteration both in active and fossil vent sites. Near-bottom three component magnetic measurements on submersible Shinkai 6500 were carried out at hydrothermal fields in the Southern Mariana Trough, a slow spreading backarc basin. Fourteen dive surveys were conducted during cruises YK11-10 and YK10-11. We investigated the magnetic structure of four hydrothermal systems located at on- and off-axis to clarify how the geophysical and geological setting controls the fluid circulation at small scale. Recent researches at slow spreading ridges showed a relationship between crustal magnetic structure and host rock around hydrothermal vents (e.g. Tivey and Dyment, 2010), but no observation at backarc spreading axis has been reported so far. We carefully corrected the effects of induced and permanent magnetizations of the submersible by applying the method of Isezaki [1986] with dumped least-square method (Honsho et al., 2009). After subtracting the IGRF from the corrected observed data, we obtained geomagnetic vector anomalies in geographical coordinate. For three transects of the axis, we applied three methods; 2D inversion technique (Parker and Huestis, 1972), 2D forward modeling technique (Honsho et al

  4. The probability of containment failure by direct containment heating in Zion

    SciTech Connect

    Pilch, M.M.; Yan, H.; Theofanous, T.G.

    1994-12-01

    This report is the first step in the resolution of the Direct Containment Heating (DCH) issue for the Zion Nuclear Power Plant using the Risk Oriented Accident Analysis Methodology (ROAAM). This report includes the definition of a probabilistic framework that decomposes the DCH problem into three probability density functions that reflect the most uncertain initial conditions (UO{sub 2} mass, zirconium oxidation fraction, and steel mass). Uncertainties in the initial conditions are significant, but our quantification approach is based on establishing reasonable bounds that are not unnecessarily conservative. To this end, we also make use of the ROAAM ideas of enveloping scenarios and ``splintering.`` Two causal relations (CRs) are used in this framework: CR1 is a model that calculates the peak pressure in the containment as a function of the initial conditions, and CR2 is a model that returns the frequency of containment failure as a function of pressure within the containment. Uncertainty in CR1 is accounted for by the use of two independently developed phenomenological models, the Convection Limited Containment Heating (CLCH) model and the Two-Cell Equilibrium (TCE) model, and by probabilistically distributing the key parameter in both, which is the ratio of the melt entrainment time to the system blowdown time constant. The two phenomenological models have been compared with an extensive database including recent integral simulations at two different physical scales. The containment load distributions do not intersect the containment strength (fragility) curve in any significant way, resulting in containment failure probabilities less than 10{sup {minus}3} for all scenarios considered. Sensitivity analyses did not show any areas of large sensitivity.

  5. Trace element diffusion and incorporation in quartz during heating experiments

    NASA Astrophysics Data System (ADS)

    Rottier, B.; Rezeau, H.; Casanova, V.; Kouzmanov, K.; Moritz, R.; Schlöglova, K.; Wälle, M.; Fontboté, L.

    2017-04-01

    Heating of quartz crystals in order to study melt and high-temperature fluid inclusions is a common practice to constrain major physical and chemical parameters of magmatic and hydrothermal processes. Diffusion and modification of trace element content in quartz and its hosted melt inclusions have been investigated through step-heating experiments of both matrix-free quartz crystals and quartz crystals associated with sulfides and other minerals using a Linkam TS1500 stage. Magmatic and hydrothermal quartz were successively analyzed after each heating step for Cu, Al, and Ti using electron probe micro-analyzer. After the last heating step, quartz crystals and their hosted melt inclusions were analyzed by laser ablation inductively coupled plasma mass spectrometry and compared to unheated samples. Heated samples reveal modification of Cu, Li, Na, and B contents in quartz and modification of Cu, Li, Ag, and K concentrations in melt inclusions. Our results show that different mechanisms of Cu, Li, and Na incorporation occur in magmatic and hydrothermal quartz. Heated magmatic quartz records only small, up to a few ppm, enrichment in Cu and Na, mostly substituting for Li. By contrast, heated hydrothermal quartz shows enrichment up to several hundreds of ppm in Cu, Li, and Na, which substitute for originally present H. This study reveals that the composition of both quartz and its hosted melt inclusions may be significantly modified upon heating experiments, leading to erroneous quantification of elemental concentrations. In addition, each quartz crystal also becomes significantly enriched in Cu in the sub-surface layer during heating. We propose that sub-surface Cu enrichment is a direct indication of Cu diffusion in quartz externally sourced from both the surrounding sulfides as well as the copper pins belonging to the heating device. Our study shows that the chemical compositions of both heated quartz and its hosted inclusions must be interpreted with great caution

  6. Heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe) including direct flow observation

    NASA Astrophysics Data System (ADS)

    Andros, F. E.; Florschuetz, L. W.

    1980-04-01

    A visual study of an annular two phase closed thermosyphon is reported. For small and intermediate liquid fill quantities, four flow regimes were observed in the evaporation section, in addition to nucleate boiling in the liquid pool: (1) a smooth continuous film with surface evaporation; (2) breakdown of the film into stable rivulets; (3) a wavy film with unstable rivulets; and (4) a wavy film with bubble nucleation in the unstable rivulets. Three different types of dry-out conditions were also observed and are reported in detail. Results obtained for a stainless steel tubular opaque device with Freon-113 as a working fluid are reported. Both steady state heat transfer characteristics and heat transfer limits are reported in detail. Results from the visual and opaque devices are compared and discussed.

  7. Hierarchical macro-mesoporous structures in the system TiO{sub 2}-Al{sub 2}O{sub 3}, obtained by hydrothermal synthesis using Tween-20 as a directing agent

    SciTech Connect

    Garcia-Benjume, M.L.; Espitia-Cabrera, M.I.; Contreras-Garcia, M.E.

    2009-12-15

    Macro-mesoporous powders of titania, alumina, and mixed titania-20%alumina systems were obtained by hydrothermal synthesis employing surfactant Tween-20 as structural directing agent in order to promote the textural properties of titania. The effect of the alumina in the titania phase and on textural properties was analyzed. The obtained powders presented a macroporous channel structure that was characterized by X-ray diffractometry, scanning and transmission electron microscopy, N{sub 2} adsorption-desorption analysis, pore size distribution, Fourier transform infrared spectrometry, and thermogravimetric analysis. It was found that alumina content retarded the anatase phase crystallization and increased the Brunauer-Emmet-Teller surface area from 136 to 210 m{sup 2}/g. The powders calcined at 400 deg. C are thermally stable and possess an interconnected macro-mesoporous hierarchical structure; the results indicate that this synthesis can be employed to prepare mixed titania-alumina with good textural properties.

  8. Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules.

    PubMed

    Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

    2016-01-08

    We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (R air/R gas = 12.8) compared to that (R air/R gas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

  9. Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

    NASA Astrophysics Data System (ADS)

    Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

    2016-01-01

    We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

  10. Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

    PubMed Central

    Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

    2016-01-01

    We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors. PMID:26743814

  11. A bi-directional two-phase/two-phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Ottenstein, Laura

    1993-01-01

    This paper describes the design and test of a heat exchanger that transfers heat from one two-phase thermal loop to another with very small drops in temperature and pressure. The heat exchanger condenses the vapor in one loop while evaporating the liquid in the other without mixing of the condensing and evaporating fluids. The heat exchanger is bidirectional in that it can transfer heat in reverse, condensing on the normally evaporating side and vice versa. It is fully compatible with capillary pumped loops and mechanically pumped loops. Test results verified that performance of the heat exchanger met the design requirements. It demonstrated a heat transfer rate of 6800 watts in the normal mode of operation and 1000 watts in the reverse mode with temperature drops of less than 5 C between two thermal loops.

  12. Targeting the molecular chaperone heat shock protein 90 (HSP90): lessons learned and future directions.

    PubMed

    Hong, David S; Banerji, Udai; Tavana, Bahareh; George, Goldy C; Aaron, Joann; Kurzrock, Razelle

    2013-06-01

    Due to the critical role of heat shock protein 90 (HSP90) in regulating the stability, activity and intracellular sorting of its client proteins involved in multiple oncogenic processes, HSP90 inhibitors are promising therapeutic agents for cancer treatment. In cancer cells, HSP90 client proteins play a major role in oncogenic signal transduction (i.e., mutant epidermal growth factor receptor), angiogenesis (i.e., vascular endothelial growth factor), anti-apoptosis (i.e., AKT), and metastasis (i.e., matrix metalloproteinase 2 and CD91), processes central to maintaining the cancer phenotype. Thus, HSP90 has emerged as a viable target for antitumor drug development, and several HSP90 inhibitors have transitioned to clinical trials. HSP90 inhibitors include geldanamycin and its derivatives (i.e., tanespimycin, alvespimycin, IPI-504), synthetic and small molecule inhibitors (i.e., AUY922, AT13387, STA9090, MPC3100), other inhibitors of HSP90 and its isoforms (i.e., shepherdin and 5'-N-ethylcarboxamideadenosine). With more than 200 "client" proteins, many of them meta-stable and oncogenic, HSP90 inhibition can affect an array of tumors. Here we review the molecular structure of HSP90, structural features of HSP90 inhibition, pharmacodynamic effects and tumor responses in clinical trials of HSP90 inhibitors. We also discuss lessons learned from completed clinical trials of HSP90 inhibitors, and future directions for these promising therapeutic agents. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Depressurization as an accident management strategy to minimize the consequences of direct containment heating

    SciTech Connect

    Hanson, D.J.; Golden, D.W.; Chambers, R.; Miller, J.D.; Hallbert, B.P.; Dobbe, C.A. )

    1990-10-01

    Probabilistic Risk Assessments (PRAs) have identified severe accidents for nuclear power plants that have the potential to cause failure of the containment through direct containment heating (DCH). Prevention of DCH or mitigation of its effects may be possible using accident management strategies that intentionally depressurize the reactor coolant system (RCS). The effectiveness of intentional depressurization during a station blackout TMLB' sequence was evaluated considering the phenomenological behavior, hardware performance, and operational performance. Phenomenological behavior was calculated using the SCDAP/RELAP5 severe accident analysis code. Two strategies to mitigate DCH by depressurization of the RCS were considered. One strategy, called early depressurization, assumed that the reactor head vent and pressurizer power-operated relief valves (PORVs) were latched open at steam generator dryout. The second strategy, called late depression, assumed that the head vent and PORVs were latched open at a core exit temperature of {approximately}922 K (1200{degree}F). Depressurization of the RCS to a low value that may mitigate DCH was predicted prior to reactor pressure vessel breach for both early and late depressurization. The strategy of late depressurization is preferred over early depressurization because there are greater opportunities to recover plant functions prior to core damage and because failure uncertainties are lessened. 22 refs., 38 figs., 6 tabs.

  14. Characterizing U.S. Heat Demand for Potential Application of Geothermal Direct Use: Preprint

    SciTech Connect

    McCabe, Kevin; Gleason, Michael; Reber, Tim; Young, Katherine R.

    2016-10-01

    In this paper, we assess the U.S. demand for low-temperature thermal energy at the county resolution for four major end-use sectors: residential buildings, commercial buildings, manufacturing facilities, and agricultural facilities. Existing, publicly available data on the U.S. thermal demand market are characterized by coarse spatial resolution, with assessments typically at the state-level or larger. For many uses, these data are sufficient; however, our research was motivated by an interest in assessing the potential demand for direct use (DU) of low-temperature (30 degrees to 150 degrees C) geothermal heat. The availability and quality of geothermal resources for DU applications are highly spatially heterogeneous; therefore, to assess the potential market for these resources, it is necessary to understand the spatial variation in demand for low-temperature resources at a local resolution. This paper presents the datasets and methods we used to develop county-level estimates of the thermal demand for the residential, commercial, manufacturing, and agricultural sectors. Although this analysis was motivated by an interest in geothermal energy deployment, the results are likely to have broader applications throughout the energy industry. The county-resolution thermal demand data developed in this study for four major U.S. sectors may have far-reaching implications for building technologies, industrial processes, and various distributed renewable energy thermal resources (e.g. biomass, solar).

  15. MELCOR 1.8.2 Assessment: IET direct containment heating tests

    SciTech Connect

    Kmetyk, L.N.

    1993-10-01

    MELCOR is a fully integrated, engineering-level computer code, being developed at Sandia National Laboratories for the USNRC, that models the entire spectrum of severe accident phenomena in a unified framework for both BWRs and PWRS. As part of an ongoing assessment program, the MELCOR computer code has been used to analyze several of the IET direct containment heating experiments done at 1:10 linear scale in the Surtsey test facility at Sandia and at 1:40 linear scale in the corium-water thermal interactions (CWTI) COREXIT test facility at Argonne National Laboratory. These MELCOR calculations were done as an open post-test study, with both the experimental data and CONTAIN results available to guide the selection of code input. Basecase MELCOR results are compared to test data in order to evaluate the new HPME DCH model recently added in MELCOR version 1.8.2. The effect of various user-input parameters in the HPME model, which define both the initial debris source and the subsequent debris interaction, were investigated in sensitivity studies. In addition, several other non-default input modelling changes involving other MELCOR code packages were required in our IET assessment analyses in order to reproduce the observed experiment behavior. Several calculations were done to identify whether any numeric effects exist in our DCH IET assessment analyses.

  16. Hydrothermal circulation in fast spread ocean crust - where and how much? Insight from ODP Hole 1256D

    NASA Astrophysics Data System (ADS)

    Harris, M.; Coggon, R. M.; Smith-Duque, C. E.; Teagle, D. A. H.

    2014-12-01

    Understanding and quantifying hydrothermal circulation is critical to testing models of the accretion of lower ocean crust and quantifying global geochemical cycles. However, our understanding is principally limited by a lack of direct observations from intact ocean crust. Key questions remain about the magnitude of hydrothermal fluid fluxes, the nature and distribution of fluid pathways and their global variability. ODP Hole 1256D in the eastern equatorial Pacific samples a complete section of 15 Myr old upper ocean crust down to the dike/gabbro transition zone. A high spatial resolution Sr isotope profile is integrated with wireline studies, volcanostratigraphy, petrography and mineral geochemistry to document fluid pathways and develop a model for the evolving hydrothermal system during volcanic construction of the crust. Major off-axis fluid conduits in the volcanic sequence are restricted to the flow margins of two anomalously thick (>25 m) massive flows, indicating that massive flows act as a permeability barrier for fluid flow. Dike margins are pathways for both recharge and discharge hydrothermal fluids. Sub-horizontal channeling of high temperature fluids at the dike/gabbro boundary is a common attribute of most cartoons of mid ocean ridge hydrothermal systems. Hole 1256D provides the first in situ observations of the dike/gabbro transition zone and records lateral fluid transport along intrusive boundaries. The time-integrated fluid flux in the sheeted dikes of Hole 1256D calculated using Sr isotope mass balance is ~1.8 x 106 kg/m2. This is similar to fluid fluxes from other studies (Hole 504B, Pito Deep, Hess Deep) despite large variations in the thickness and Sr isotope profiles of the sheeted dike complexes, suggesting that hydrothermal fluid fluxes are remarkably uniform and independent of the local structure of the crust. This fluid flux is not large enough to completely remove the heat flux from crystallizing and cooling the lower crust and requires

  17. Seismic evidence that black smoker heat flux is influenced by localized magma replenishment and associated increases in crustal permeability

    NASA Astrophysics Data System (ADS)

    Arnoux, Gillean M.; Toomey, Douglas R.; Hooft, Emilie E. E.; Wilcock, William S. D.; Morgan, Joanna; Warner, Mike; VanderBeek, Brandon P.

    2017-02-01

    Hydrothermal circulation at mid-ocean ridges is responsible for 25% of Earth's heat flux and controls the thermal and chemical evolution of young oceanic crust. The heat flux of black smoker hydrothermal systems is thought to be primarily controlled by localized magma supply and crustal permeability. Nevertheless, magma chamber characteristics and the nature of crustal permeability beneath such systems remain unclear. Here we apply three-dimensional full-waveform inversion to seismic data from the hydrothermally active Endeavour segment of the Juan de Fuca Ridge to image the upper crust in high resolution. We resolve velocity variations directly above the axial magma chamber that correlate with variations in seismicity, black smoker heat flux, and the depth of the axial magmatic system. We conclude that localized magma recharge to the axial magma lens, along with induced seismogenic cracking and increased permeability, influences black smoker heat flux.

  18. Geothermal direct-heat utilization assistance. Federal Assistance Program quarterly project progress report, April 1--June 30, 1998

    SciTech Connect

    1998-07-01

    This report summarizes geothermal technical assistance, R and D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the third quarter of FY98 (April--June, 1998). It describes 231 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with included requests for general information including material for high school and university students, and material on geothermal heat pumps, resource and well data, spacing heating and cooling, greenhouses, aquaculture, equipment, district heating, resorts and spas, industrial applications, snow melting and electric power. Research activities include work on model construction specifications for line shaft submersible pumps and plate heat exchangers, and a comprehensive aquaculture developers package. A brochure on Geothermal Energy in Klamath County was developed for state and local tourism use. Outreach activities include the publication of the Quarterly Bulletin (Vol. 19, No. 2) with articles on research at the Geo-Heat Center, sustainability of geothermal resources, injection well drilling in Boise, ID and a greenhouse project in the Azores. Other outreach activities include dissemination of information mainly through mailings of publications, tours of local geothermal uses, geothermal library acquisitions and use, participation in workshops, short courses and technical meetings by the staff, and progress monitor reports on geothermal activities.

  19. Coupled electrochemical and heat/mass transport characteristics in passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Chen, Rong

    methanol concentrations are obtained. It was further revealed that the improved performance with higher methanol concentrations is due primarily to the increased operating temperature resulting from the exothermic reaction between the permeated methanol and oxygen on the cathode. In addition, to further reflect the effect of two-phase heat and mass transport on the performance of the passive DMFC, we then developed a two-phase two-dimensional thermal model. With this model, the effects of methanol concentration, open ratio and channel and rib width on cell performance were investigated. It was found that although the larger open ratio and smaller channel and rib width exhibit the lower cell operating temperature as a result of the lower heat generation rate, the cell performance is still higher as a result of the increased mass transfer rate on both the anode and cathode. Keywords: Passive Direct Methanol Fuel Cell; Cell Performance; Thermal Effect; Open-circuit Condition; Methanol Concentration; Cell Orientation; Metal Foam, Effective Thermal Conductivity; Oxygen Transport; Mass Transfer Resistance; Two-phase Transport; Open Ratio; Channel and Rib Width.

  20. Temperature structures in Galactic center clouds. Direct evidence for gas heating via turbulence

    NASA Astrophysics Data System (ADS)

    Immer, K.; Kauffmann, J.; Pillai, T.; Ginsburg, A.; Menten, K. M.

    2016-11-01

    The central molecular zone at the center of our Galaxy is the best template to study star formation processes under extreme conditions, similar to those in high-redshift galaxies. We observed on-the-fly maps of para-H2CO transitions at 218 GHz and 291 GHz towards seven Galactic center clouds. From the temperature-sensitive integrated intensity line ratios of H2CO(32,1 -22,0)/H2CO(30,3 -20,2) and H2CO(42,2 -32,1)/H2CO(40,4 -30,3) in combination with radiative transfer models, we produce gas temperature maps of our targets. These transitions are sensitive to gas with densities of 105 cm-3 and temperatures <150 K. The measured gas temperatures in our sources are all higher (>40 K) than their dust temperatures ( 25 K). Our targets have a complex velocity structure that requires a careful disentanglement of the different components. We produce temperature maps for each of the velocity components and show that the temperatures of the components differ, revealing temperature gradients in the clouds. Combining the temperature measurements with the integrated intensity line ratio of H2CO(40,4 -30,3)/H2CO(30,3 -20,2), we constrain the density of this warm gas to 104 -106 cm-3. We find a positive correlation between the line width of the main H2CO lines and the temperature of the gas, direct evidence for gas heating via turbulence. Our data is consistent with a turbulence heating model with a density of n = 105 cm-3. Integrated intensity maps of the H2CO lines (Figs. E.1-E.7), ratio and uncertainty maps (Figs. F.1-F.7), and temperature and uncertainty maps (Figs. H.1-H.7) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A94

  1. Geothermal direct-heat utilization assistance. Quarterly project progress report, October--December 1993

    SciTech Connect

    Not Available

    1993-12-31

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on (1) compilation of data on low-temperature resources and (2) evaluation of groundwater vs. ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  2. A novel approach to determine the heat transfer coefficient in directional solidification furnaces

    NASA Technical Reports Server (NTRS)

    Banan, Mohsen; Gray, Ross T.; Wilcox, William R.

    1990-01-01

    The heat transfer coefficient between a molten charge and its surroundings in a Bridgman furnace was determined using an approach utilizing in-situ temperature measurement. The ampoule containing an isothermal melt was suddenly moved from a higher temperature zone to a lower temperature zone. The temperature-time history was used in a lumped-capacity cooling model to evaluate the heat transfer coefficient between the charge and the furnace. The experimentally determined heat transfer coefficient was of the same order of magnitude as the value estimated by standard heat transfer calculations.

  3. Enceladus Hydrothermal Activity

    NASA Image and Video Library

    2017-04-13

    This graphic illustrates how scientists on NASA's Cassini mission think water interacts with rock at the bottom of the ocean of Saturn's icy moon Enceladus, producing hydrogen gas (H2). The Cassini spacecraft detected the hydrogen in the plume of gas and icy material spraying from Enceladus during its deepest and last dive through the plume on Oct. 28, 2015. Cassini also sampled the plume's composition during previous flybys, earlier in the mission. From these observations scientists have determined that nearly 98 percent of the gas in the plume is water vapor, about 1 percent is hydrogen, and the rest is a mixture of other molecules including carbon dioxide, methane and ammonia. The graphic shows water from the ocean circulating through the seafloor, where it is heated and interacts chemically with the rock. This warm water, laden with minerals and dissolved gases (including hydrogen and possibly methane) then pours into the ocean creating chimney-like vents. The hydrogen measurements were made using Cassini's Ion and Neutral Mass Spectrometer, or INMS, instrument, which sniffs gases to determine their composition. The finding is an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean. Previous results from Cassini's Cosmic Dust Analyzer instrument, published in March 2015, suggested hot water is interacting with rock beneath the ocean; the new findings support that conclusion and indicate that the rock is reduced in its geochemistry. With the discovery of hydrogen gas, scientists can now conclude that there is a source of chemical free energy in Enceladus' ocean. https://photojournal.jpl.nasa.gov/catalog/PIA21442

  4. Numerical Modeling for Large Scale Hydrothermal System

    NASA Astrophysics Data System (ADS)

    Sohrabi, Reza; Jansen, Gunnar; Malvoisin, Benjamin; Mazzini, Adriano; Miller, Stephen A.

    2017-04-01

    Moderate-to-high enthalpy systems are driven by multiphase and multicomponent processes, fluid and rock mechanics, and heat transport processes, all of which present challenges in developing realistic numerical models of the underlying physics. The objective of this work is to present an approach, and some initial results, for modeling and understanding dynamics of the birth of large scale hydrothermal systems. Numerical modeling of such complex systems must take into account a variety of coupled thermal, hydraulic, mechanical and chemical processes, which is numerically challenging. To provide first estimates of the behavior of this deep complex systems, geological structures must be constrained, and the fluid dynamics, mechanics and the heat transport need to be investigated in three dimensions. Modeling these processes numerically at adequate resolution and reasonable computation times requires a suite of tools that we are developing and/or utilizing to investigate such systems. Our long-term goal is to develop 3D numerical models, based on a geological models, which couples mechanics with the hydraulics and thermal processes driving hydrothermal system. Our first results from the Lusi hydrothermal system in East Java, Indonesia provide a basis for more sophisticated studies, eventually in 3D, and we introduce a workflow necessary to achieve these objectives. Future work focuses with the aim and parallelization suitable for High Performance Computing (HPC). Such developments are necessary to achieve high-resolution simulations to more fully understand the complex dynamics of hydrothermal systems.

  5. The Guaymas Basin Hiking Guide to Hydrothermal Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface Hydrothermal Circulation.

    PubMed

    Teske, Andreas; de Beer, Dirk; McKay, Luke J; Tivey, Margaret K; Biddle, Jennifer F; Hoer, Daniel; Lloyd, Karen G; Lever, Mark A; Røy, Hans; Albert, Daniel B; Mendlovitz, Howard P; MacGregor, Barbara J

    2016-01-01

    The hydrothermal mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview, we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region.

  6. The Guaymas Basin Hiking Guide to Hydrothermal Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface Hydrothermal Circulation

    PubMed Central

    Teske, Andreas; de Beer, Dirk; McKay, Luke J.; Tivey, Margaret K.; Biddle, Jennifer F.; Hoer, Daniel; Lloyd, Karen G.; Lever, Mark A.; Røy, Hans; Albert, Daniel B.; Mendlovitz, Howard P.; MacGregor, Barbara J.

    2016-01-01

    The hydrothermal mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview, we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region. PMID:26925032

  7. Geothermal potential for commercial and industrial direct heat applications in Salida, Colorado. Final report

    SciTech Connect

    Coe, B.A.; Dick, J.D.; Galloway, M.J.; Gross, J.T.; Meyer, R.T.; Raskin, R.; Zocholl, J.R.

    1982-10-01

    The Salida Geothermal Prospect (Poncha Hot Springs) was evaluated for industrial and commercial direct heat applications at Salida, Colorado, which is located approximately five miles east of Poncha Hot Springs. Chaffee Geothermal, Ltd., holds the geothermal leases on the prospect and the right-of-way for the main pipeline to Salida. The Poncha Hot Springs are located at the intersection of two major structural trends, immediately between the Upper Arkansas graben and the Sangre de Cristo uplift. Prominent east-west faulting occurs at the actual location of the hot springs. Preliminary exploration indicates that 1600 gpm of geothermal fluid as hot as 250/sup 0/F is likely to be found at around 1500 feet in depth. The prospective existing endusers were estimated to require 5.02 x 10/sup 10/ Btu per year, but the total annual amount of geothermal energy available for existing and future endusers is 28.14 x 10/sup 10/ Btu. The engineering design for the study assumed that the 1600 gpm would be fully utilized. Some users would be cascaded and the spent fluid would be cooled and discharged to nearby rivers. The economic analysis assumes that two separate businesses, the energy producer and the energy distributor, are participants in the geothermal project. The producer would be an existing limited partnership, with Chaffee Geothermal, Ltd. as one of the partners; the distributor would be a new Colorado corporation without additional income sources. Economic evaluations were performed in full for four cases: the Base Case and three alternate scenarios. Alternate 1 assumes a three-year delay in realizing full production relative to the Base Case; Alternate 2 assumes that the geothermal reservoir is of a higher quality than is assumed for the Base Case; and Alternate 3 assumes a lower quality reservoir. 11 refs., 34 figs., 40 tabs.

  8. Direct containment heating experiments in Zion Nuclear Power Plant geometry using prototypic materials

    SciTech Connect

    Binder, J.L.; McUmber, L.M.; Spencer, B.W.

    1993-12-31

    Direct Containment Heating (DCH) experiments have been completed which utilize prototypic core materials. The experiments reported on here are a continuation of the Integral Effects Testing (IET) DCH program. The experiments incorporated a 1/40 scale model of the Zion Nuclear Power Plant containment structures. The model included representations of the primary system volume, RPV lower head, cavity and instrument tunnel, and the lower containment structures. The experiments were steam driven. Iron-alumina thermite with chromium was used as a core melt stimulant in the earlier IET experiments. These earlier IET experiments at Argonne National Laboratory (ANL) and Sandia National Laboratories (SNL) provided useful data on the effect of scale on DCH phenomena; however, a significant question concerns the potential experiment distortions introduced by the use of non-prototypic iron/alumina thermite. Therefore, further testing with prototypic materials has been carried out at ANL. Three tests have been completed, DCH-U1A, U1B and U2. DCH-U1A and U1B employed an inerted containment atmosphere and are counterpart to the IET-1RR test with iron/alumina thermite. DCH-U2 employed nominally the same atmosphere composition of its counterpart iron/alumina test, IET-6. All tests, with prototypic material, have produced lower peak containment pressure rises; 45, 111 and 185 kPa in U1A, U1B and U2, compared to 150 and 250 kPa IET-1RR and 6. Hydrogen production, due to metal-steam reactions, was 33% larger in U1B and U2 compared to IET-1RR and IET-6. The pressurization efficiency was consistently lower for the corium tests compared to the IET tests.

  9. Estimation of heat transfer coefficients for biomass particles by direct numerical simulation using microstructured particle models in the Laminar regime

    SciTech Connect

    Pecha, M. Brennan; Garcia-Perez, Manuel; Foust, Thomas D.; Ciesielski, Peter N.

    2016-11-08

    Here, direct numerical simulation of convective heat transfer from hot gas to isolated biomass particle models with realistic morphology and explicit microstructure was performed over a range of conditions with laminar flow of hot gas (500 degrees C). Steady-state results demonstrated that convective interfacial heat transfer is dependent on the wood species. The computed heat transfer coefficients were shown to vary between the pine and aspen models by nearly 20%. These differences are attributed to the species-specific variations in the exterior surface morphology of the biomass particles. We also quantify variations in heat transfer experienced by the particle when positioned in different orientations with respect to the direction of fluid flow. These results are compared to previously reported heat transfer coefficient correlations in the range of 0.1 < Pr < 1.5 and 10 < Re < 500. Comparison of these simulation results to correlations commonly used in the literature (Gunn, Ranz-Marshall, and Bird-Stewart-Lightfoot) shows that the Ranz-Marshall (sphere) correlation gave the closest h values to our steady-state simulations for both wood species, though no existing correlation was within 20% of both species at all conditions studied. In general, this work exemplifies the fact that all biomass feedstocks are not created equal, and that their species-specific characteristics must be appreciated in order to facilitate accurate simulations of conversion processes.

  10. Estimation of heat transfer coefficients for biomass particles by direct numerical simulation using microstructured particle models in the Laminar regime

    DOE PAGES

    Pecha, M. Brennan; Garcia-Perez, Manuel; Foust, Thomas D.; ...

    2016-11-08

    Here, direct numerical simulation of convective heat transfer from hot gas to isolated biomass particle models with realistic morphology and explicit microstructure was performed over a range of conditions with laminar flow of hot gas (500 degrees C). Steady-state results demonstrated that convective interfacial heat transfer is dependent on the wood species. The computed heat transfer coefficients were shown to vary between the pine and aspen models by nearly 20%. These differences are attributed to the species-specific variations in the exterior surface morphology of the biomass particles. We also quantify variations in heat transfer experienced by the particle when positionedmore » in different orientations with respect to the direction of fluid flow. These results are compared to previously reported heat transfer coefficient correlations in the range of 0.1 < Pr < 1.5 and 10 < Re < 500. Comparison of these simulation results to correlations commonly used in the literature (Gunn, Ranz-Marshall, and Bird-Stewart-Lightfoot) shows that the Ranz-Marshall (sphere) correlation gave the closest h values to our steady-state simulations for both wood species, though no existing correlation was within 20% of both species at all conditions studied. In general, this work exemplifies the fact that all biomass feedstocks are not created equal, and that their species-specific characteristics must be appreciated in order to facilitate accurate simulations of conversion processes.« less

  11. Heat Transfer Model of Directional Solidification by LMC Process for Superalloy Casting Based on Finite Element Method

    NASA Astrophysics Data System (ADS)

    Cao, Liu; Liao, Dunming; Lu, Yuzhang; Chen, Tao

    2016-09-01

    With the rapid development of the aviation industry, the turbine blade, a critical component of the aeronautical engine, has come to be widely produced by liquid-metal cooling (LMC) process. A temperature- and time-dependent heat transfer coefficient was used to represent the heat convection between the shell and the cooling liquid, and an improved Monte Carlo ray-tracing approach was adopted to handle the boundary of radiation heat transfer. Unstructured mesh was used to fit the irregular shell boundary, and the heat transfer model of directional solidification by LMC process based on finite element method (FEM) was established. The concept of local matrix was here proposed to guarantee computational efficiency. The pouring experiments of directional solidification by LMC process were carried out, then simulation and experimental results were compared here. The accuracy of the heat transfer model was validated by the cooling curves and grain morphology, and the maximum relative error between simulation and experimental cooling curve was 2 pct. The withdrawal rate showed an important influence on the shape of solidification interface, and stray grain is liable to be generated on the bottom of platform at an excessive withdrawal rate.

  12. Hydrothermal mineralization at seafloor spreading centers

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.

    1984-01-01

    The recent recognition that metallic mineral deposits are concentrated by hydrothermal processes at seafloor spreading centers constitutes a scientific breakthrough that opens active sites at seafloor spreading centers as natural laboratories to investigate ore-forming processes of such economically useful deposits as massive sulfides in volcanogenic rocks on land, and that enhances the metallic mineral potential of oceanic crust covering two-thirds of the Earth both beneath ocean basins and exposed on land in ophiolite belts. This paper reviews our knowledge of processes of hydrothermal mineralization and the occurrence and distribution of hydrothermal mineral deposits at the global oceanic ridge-rift system. Sub-seafloor hydrothermal convection involving circulation of seawater through fractured rocks of oceanic crust driven by heat supplied by generation of new lithosphere is nearly ubiquitous at seafloor spreading centers. However, ore-forming hydrothermal systems are extremely localized where conditions of anomalously high thermal gradients and permeability increase hydrothermal activity from the ubiquitous low-intensity background level (⩽ 200°C) to high-intensity characterized by high temperatures ( > 200-c.400°C), and a rate and volume of flow sufficient to sustain chemical reactions that produce acid, reducing, metal-rich primary hydrothermal solutions. A series of mineral phases with sulfides and oxides as high- and low-temperature end members, respectively, are precipitated along the upwelling limb and in the discharge zone of single-phase systems as a function of increasing admixture of normal seawater. The occurrence of hydrothermal mineral deposits is considered in terms of spatial and temporal frames of reference. Spatial frames of reference comprise structural features along-axis (linear sections that are the loci of seafloor spreading alternating with transform faults) and perpendicular to axis (axial zone of volcanic extrusion and marginal

  13. Fast wave direct electron heating in advanced inductive and ITER baseline scenario discharges in DIII-D

    NASA Astrophysics Data System (ADS)

    Pinsker, R. I.; Austin, M. E.; Diem, S. J.; Doyle, E. J.; Grierson, B. A.; Hosea, J. C.; Jackson, G. L.; Kaufman, M. C.; Luce, T. C.; Maggiora, R.; Milanesio, D.; Nagy, A.; Perkins, R.; Politzer, P. A.; Porkolab, M.; Ryan, P. M.; Solomon, W. M.; Taylor, G.; Turco, F.; Zeng, L.

    2014-02-01

    Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ˜2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedly strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. The AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.

  14. Fast wave direct electron heating in advanced inductive and ITER baseline scenario discharges in DIII-D

    DOE PAGES

    Pinsker, R. I.; Austin, M. E.; Diem, S. J.; ...

    2014-02-12

    Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ~2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedlymore » strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. As a result, the AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.« less

  15. Fast wave direct electron heating in advanced inductive and ITER baseline scenario discharges in DIII-D

    SciTech Connect

    Pinsker, R. I.; Austin, M. E.; Diem, S. J.; Doyle, E. J.; Grierson, B. A.; Hosea, J. C.; Jackson, G. L.; Kaufman, M. C.; Luce, T. C.; Maggiora, R.; Milanesio, D.; Nagy, A.; Perkins, R.; Politzer, P. A.; Porkolab, M.; Ryan, P. M.; Solomon, W. M.; Taylor, G.; Turco, F.; Zeng, L.

    2014-02-12

    Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ~2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedly strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. As a result, the AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.

  16. Fast wave direct electron heating in advanced inductive and ITER baseline scenario discharges in DIII-D

    SciTech Connect

    Pinsker, R. I.; Jackson, G. L.; Luce, T. C.; Politzer, P. A.; Austin, M. E.; Diem, S. J.; Kaufman, M. C.; Ryan, P. M.; Doyle, E. J.; Zeng, L.; Grierson, B. A.; Hosea, J. C.; Nagy, A.; Perkins, R.; Solomon, W. M.; Taylor, G.; Maggiora, R.; Milanesio, D.; Porkolab, M.; Turco, F.

    2014-02-12

    Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ∼2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedly strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. The AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.

  17. Direct link between metabolic regulation and the heat-shock response through the transcriptional regulator PGC-1α.

    PubMed

    Minsky, Neri; Roeder, Robert G

    2015-10-20

    In recent years an extensive effort has been made to elucidate the molecular pathways involved in metabolic signaling in health and disease. Here we show, surprisingly, that metabolic regulation and the heat-shock/stress response are directly linked. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a critical transcriptional coactivator of metabolic genes, acts as a direct transcriptional repressor of heat-shock factor 1 (HSF1), a key regulator of the heat-shock/stress response. Our findings reveal that heat-shock protein (HSP) gene expression is suppressed during fasting in mouse liver and in primary hepatocytes dependent on PGC-1α. HSF1 and PGC-1α associate physically and are colocalized on several HSP promoters. These observations are extended to several cancer cell lines in which PGC-1α is shown to repress the ability of HSF1 to activate gene-expression programs necessary for cancer survival. Our study reveals a surprising direct link between two major cellular transcriptional networks, highlighting a previously unrecognized facet of the activity of the central metabolic regulator PGC-1α beyond its well-established ability to boost metabolic genes via its interactions with nuclear hormone receptors and nuclear respiratory factors. Our data point to PGC-1α as a critical repressor of HSF1-mediated transcriptional programs, a finding with possible implications both for our understanding of the full scope of metabolically regulated target genes in vivo and, conceivably, for therapeutics.

  18. Direct link between metabolic regulation and the heat-shock response through the transcriptional regulator PGC-1α

    PubMed Central

    Minsky, Neri; Roeder, Robert G.

    2015-01-01

    In recent years an extensive effort has been made to elucidate the molecular pathways involved in metabolic signaling in health and disease. Here we show, surprisingly, that metabolic regulation and the heat-shock/stress response are directly linked. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a critical transcriptional coactivator of metabolic genes, acts as a direct transcriptional repressor of heat-shock factor 1 (HSF1), a key regulator of the heat-shock/stress response. Our findings reveal that heat-shock protein (HSP) gene expression is suppressed during fasting in mouse liver and in primary hepatocytes dependent on PGC-1α. HSF1 and PGC-1α associate physically and are colocalized on several HSP promoters. These observations are extended to several cancer cell lines in which PGC-1α is shown to repress the ability of HSF1 to activate gene-expression programs necessary for cancer survival. Our study reveals a surprising direct link between two major cellular transcriptional networks, highlighting a previously unrecognized facet of the activity of the central metabolic regulator PGC-1α beyond its well-established ability to boost metabolic genes via its interactions with nuclear hormone receptors and nuclear respiratory factors. Our data point to PGC-1α as a critical repressor of HSF1-mediated transcriptional programs, a finding with possible implications both for our understanding of the full scope of metabolically regulated target genes in vivo and, conceivably, for therapeutics. PMID:26438876

  19. Theoretical constraints of physical and chemical properties of hydrothermal fluids on variations in chemolithotrophic microbial communities in seafloor hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Nakamura, Kentaro; Takai, Ken

    2014-12-01

    . Particularly in H2-rich ultramafic rock-hosted hydrothermal systems, anaerobic and aerobic hydrogenotrophy is more energetically significant than thiotrophy. The CH4 concentration also has a considerable impact on organisms with aerobic and anaerobic methanotrophic metabolisms, particularly in sediment-associated hydrothermal systems. Recently clarified patterns and functions of existing microbial communities and their metabolisms are generally consistent with the results of our thermodynamic modeling of the hydrothermal mixing zones. These relationships provide important directions for future research addressing the origin and early evolution of life on Earth as well as for the search for extraterrestrial life.

  20. The direction of turbulent heat flux by a direct measurement was opposite to an indirect estimation over calm oceans in summer

    NASA Astrophysics Data System (ADS)

    Ando, Y.; Tachibana, Y.; Konda, M.; Maekawa, Y.; Nakamura, T.; Okada, K.

    2016-12-01

    In order to understand the air-sea interaction in the climate system, a direct measurement of turbulent flux (the eddy covariance method) is necessary as well as an indirect estimate of that, for example, the bulk method. However, it is rarely experienced due to many difficulties over a long period. The most of the difficulties comes from the moving platform, which is not fixed as over land because the anemometer moves with the platform as the ship moves. The ship motion correction for the wind velocity is a very difficult issue. On the top of the foremast of the training ship SEISUIMARU (Mie University, Japan), the developed on-board eddy covariance system was installed in 2009. The training ship SEISUIMARU cruises the northwest Pacific Ocean, especially the coast of Japan every year. This system is routinely operating in her whole cruises. When these kind of continuous measurements are integrated in these areas, reliable direct measurement of turbulent flux database can be established.We compared the turbulent heat fluxes using the bulk method and those of the eddy covariance method using this database. The results were some differences in certain conditions. In some cases, the direction of the turbulent heat fluxes was opposite. This might be caused by the sea surface temperatures (SSTs) using the bulk method were temperatures at the depth of 3 meter instead of the surface temperatures. SSTs are warmer than bulk 3 meter temperatures in high-level solar radiation and low-wind conditions, as expected due to the sea surface warming effects over calm oceans in summer. The difference of the turbulent heat fluxes using the eddy covariance method and those of the bulk method was positively correlated with the solar radiation. Moreover, the difference was negatively correlated with the surface wind speed. These results were more clear in the sensible heat fluxes than that of the latent heat fluxes. These results suggest one of difference of the turbulent heat fluxes

  1. Geothermal direct-heat utilization assistance. Quarterly progress report, April--June 1993

    SciTech Connect

    Not Available

    1993-08-01

    Progress is reported on the following R&D activities: evaluation of lineshaft turbine pump problems, geothermal district heating marketing strategy, and greenhouse peaking analysis. Other activities are reported on technical assistance, technology transfer, and the geothermal progress monitor.

  2. Future directions in two-phase flow and heat transfer in space

    NASA Technical Reports Server (NTRS)

    Bankoff, S. George

    1994-01-01

    Some areas of opportunity for future research in microgravity two-phase flow and heat transfer are pointed out. These satisfy the dual requirements of relevance to current and future needs, and scientific/engineering interest.

  3. Direct evidence of strongly inhomogeneous energy deposition in target heating with laser-produced ion beams

    SciTech Connect

    Brambrink, E.; Audebert, P.; Schlegel, T.; Malka, G.; Aleonard, M. M.; Claverie, G.; Gerbaux, M.; Gobet, F.; Hannachi, F.; Scheurer, J. N.; Tarisien, M.; Amthor, K. U.; Meot, V.; Morel, P.

    2007-06-15

    We report on strong nonuniformities in target heating with intense, laser-produced proton beams. The observed inhomogeneity in energy deposition can strongly perturb equation of state (EOS) measurements with laser-accelerated ions which are planned in several laboratories. Interferometric measurements of the target expansion show different expansion velocities on the front and rear surfaces, indicating a strong difference in local temperature. The nonuniformity indicates at an additional heating mechanism, which seems to originate from electrons in the keV range.

  4. Direct evidence of strongly inhomogeneous energy deposition in target heating with laser-produced ion beams.

    PubMed

    Brambrink, E; Schlegel, T; Malka, G; Amthor, K U; Aléonard, M M; Claverie, G; Gerbaux, M; Gobet, F; Hannachi, F; Méot, V; Morel, P; Nicolai, P; Scheurer, J N; Tarisien, M; Tikhonchuk, V; Audebert, P

    2007-06-01

    We report on strong nonuniformities in target heating with intense, laser-produced proton beams. The observed inhomogeneity in energy deposition can strongly perturb equation of state (EOS) measurements with laser-accelerated ions which are planned in several laboratories. Interferometric measurements of the target expansion show different expansion velocities on the front and rear surfaces, indicating a strong difference in local temperature. The nonuniformity indicates at an additional heating mechanism, which seems to originate from electrons in the keV range.

  5. Hydrothermal Preparation of Apatite Composite with Magnetite or Anatase

    SciTech Connect

    Murakami, Setsuaki; Ishida, Emile H.; Ioku, Koji

    2006-05-15

    Microstructure designed porous hydroxyapatite (Ca10(PO4)6(OH)2) composites with magnetite (Fe3O4) particles or anatase (TiO2) dispersion were prepared by hydrothermal treatment. These composites had micro-pores of about 0.1-0.5 {mu}m in size. Magnetite / Hydroxyapatite composites should be suitable for medical treatment of cancer, especially in bones, because HA can bond to bones directly and magnetite can generate heat. They must be used for hyperthermia therapies of cancer in bones. Meanwhile, anatase / Hydroxyapatite composite should be suitable for environmental purification, because HA rod-shape particles expose the specific crystal face, which adsorbs organic contaminants and so on.

  6. Integration of Heat Treatment with Shot Peening of 17-4 Stainless Steel Fabricated by Direct Metal Laser Sintering

    NASA Astrophysics Data System (ADS)

    AlMangour, Bandar; Yang, Jenn-Ming

    2017-08-01

    Direct metal laser sintering (DMLS) is a promising powder-based additive manufacturing process for fabrication of near-net-shape parts. However, the typically poor fatigue performance of DMLS parts must be addressed for use in demanding industrial applications. Post-treatment can be applied to enhance the performance of such components. Earlier attempts at inducing grain refinement through severe plastic deformation of part surfaces using shot peening improved the physical and mechanical properties of metals without chemical alteration. However, heat treatment can modify the surface-hardening effects attained by shot peening. Hence, we examined the feasibility of applying shot peening combined with heat treatment to improve the performance of DMLS-fabricated 17-4 stainless steel parts through microstructural evolution studies and hardness measurements. Compared to a specimen treated only by shot peening, the sample exposed to additional heat treatment showed increased hardness due to aging of the dominant phase.

  7. Effect of solar irradiation on forced convective heat transfer through a nanofluid based direct absorption solar collector

    NASA Astrophysics Data System (ADS)

    Parvin, Salma; Ahmed, Sajid; Chowdhury, Raju

    2017-06-01

    The present work investigates numerically the convective and radiative heat transfer performance and entropy generation of forced convection through a direct absorption solar collector (DASC). Four different fluids; Cu-water nanofluid, Al2O3-waternanofluid, TiO2-water nanofluid and pure water are used as the working fluid. Entropy production has been taken into account in addition to the collector efficiency and heat transfer enhancement. Penalty finite element method with Galerkin's weighted residual technique is used to solve the governing non-linear partial differential equations. Numerical simulations are performed for the variation of solar irradiation (I). The outcomes are presented in the form of isotherms, average output temperature, the average Nusselt number, collector efficiency, average entropy generation and Bejan number. The results present that the rate of heat transfer and collector efficiency enhance significantly for raising the values of I upto a certain range.

  8. Direct numerical simulation of transitional and turbulent flow over a heated flat plate using finite-difference schemes

    NASA Technical Reports Server (NTRS)

    Madavan, Nateri K.

    1995-01-01

    This report deals with the direct numerical simulation of transitional and turbulent flow at low Mach numbers using high-order-accurate finite-difference techniques. A computation of transition to turbulence of the spatially-evolving boundary layer on a heated flat plate in the presence of relatively high freestream turbulence was performed. The geometry and flow conditions were chosen to match earlier experiments. The development of the momentum and thermal boundary layers was documented. Velocity and temperature profiles, as well as distributions of skin friction, surface heat transfer rate, Reynolds shear stress, and turbulent heat flux, were shown to compare well with experiment. The results indicate that the essential features of the transition process have been captured. The numerical method used here can be applied to complex geometries in a straightforward manner.

  9. Direct Numerical Simulation of Transitional and Turbulent Flow Over a Heated Flat Plate Using Finite-Difference Schemes

    NASA Technical Reports Server (NTRS)

    Madavan, Nateri K.

    1995-01-01

    The work in this report was conducted at NASA Ames Research Center during the period from August 1993 to January 1995 deals with the direct numerical simulation of transitional and turbulent flow at low Mach numbers using high-order-accurate finite-difference techniques. A computation of transition to turbulence of the spatially-evolving boundary layer on a heated flat plate in the presence of relatively high freestream turbulence was performed. The geometry and flow conditions were chosen to match earlier experiments. The development of the momentum and thermal boundary layers was documented. Velocity and temperature profiles, as well as distributions of skin friction, surface heat transfer rate, Reynolds shear stress, and turbulent heat flux were shown to compare well with experiment. The numerical method used here can be applied to complex geometries in a straightforward manner.

  10. Pyrite Recrystallization Experiments With Circulating Hydrothermal Solution

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Abe, A.; Tanaka, K.

    2007-12-01

    Pyrite is one of the most common sulfide minerals found in hydrothermal deposits and sea-floor sediments from hydrothermal fumaroles. Hydrothermal fluid flow plays an important role in crystallization of sulfide minerals. In this study, we tried to reproduce pyrite crystallization with one-way flowing hydrothermal fluid. We designed a circuit circulating hydrothermal fluid by thermal convection. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubes with 5 mm in inner diameter was used as a reaction vessel. In the circuit, pyrite dissolves to acidic fluid in upstream region. Then, pyrite will crystallize again in downstream region as temperature decreases. The rectangular plane was held to be 20 degrees inclination to generate thermal convection. One of the long sides of the rectangular was heated by an electric furnace. Starting materials were put in a tube to be heated. Upper half, approximately 20 cm, of the tube was filled with quartz sand. Next quarter was filled with equivalent mass mixture of quartz sand and powdered pyrite crystals. The lowest quarter was filled with mixture of quartz sand, pyrite, anhydrite and sulfur, those mass are equivalent. The solution was a mixture of 0.5mol/l HCl and 3.0mol/l NaCl. Maximum temperature was controlled to approximately 350°C at the center of the heated tube. Experimental durations were up to 9 days. Fluid pressure increased to approximately 6 MPa as heating. After the experiments, the run products were fixed with resin in a sample tube, and vertical sections were observed by SEM. In the run products, pyrite dissolved at the lower part of the starting material. In the upper half of the sample tube, pyrite crystals precipitated on quartz surface. Crystallization density depends on temperature gradient of the fluid. Predominant morphology of the pyrite crystals consists (100) plains. Tiny framboidal aggregates and crystals with (210) plains also occur. In the run products of longer than 3 days run durations

  11. Hyperbaric Hydrothermal Atomic Force Microscope

    DOEpatents

    Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

    2003-07-01

    A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

  12. Hydrothermal carbonization of lignocellulosic biomass.

    PubMed

    Xiao, Ling-Ping; Shi, Zheng-Jun; Xu, Feng; Sun, Run-Cang

    2012-08-01

    Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4 MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography-mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery.

  13. Hyperbaric hydrothermal atomic force microscope

    DOEpatents

    Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

    2002-01-01

    A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

  14. Rapid assessment of multi-directional 3D-flow fields using active heat pulse sensing in the streambed

    NASA Astrophysics Data System (ADS)

    Banks, Eddie W.; Shanafield, Margaret; McCallum, James; Noorduijn, Saskia; Lewandowski, Jorg; Batelaan, Okke

    2017-04-01

    Application of heat as a tracer to hydrological studies has rapidly progressed in the last few decades driven by the simplicity of the methodology and low cost of sensor technology. Vertical temperature profiles using the 1D analytical solution are now widely used to determine hyporheic flow patterns and hydraulic dynamics within the shallow streambed sediment. One of the challenges in using a limited number of measurements to characterize processes that are not entirely vertical has been the determination of the horizontal or lateral flow component and how these components vary spatially and also their relative magnitude in 3D space. This study used a homemade portable 56 sensor, 3D temperature array with 3 heat pulse sources (the hot rod) to measure the flow direction and magnitude up to 230 mm below the water-sediment interface at a scale of a few centimetres in a range of sedimentary environments from fine silt to coarse gravels. Short heat pulses, typically 1 minute in duration were injected into the stream sediment and the response was monitored over a period of 20-30 minutes. Breakthrough curves from each of the temperature sensors was analysed using a version of the heat transport equation and a calibration objective function was used to estimate the x, y and z flow vector to determine the dominant direction and magnitude at the point of observation. A GUI in Python was developed to provide a user-friendly interface for processing the field data. The robust design of the hot rod and use of short duration heat pulses provides a rapid assessment technique for different heterogeneous stream environments and conditions which are crucial to determining dynamic and multi-directional flow patterns and understanding biogeochemical processes at the water-streambed interface.

  15. Catalytic Hydrothermal Gasification

    SciTech Connect

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  16. TamiR159 Directed Wheat TaGAMYB Cleavage and Its Involvement in Anther Development and Heat Response

    PubMed Central

    Cao, Hua; Peng, Huiru; Ni, Zhongfu; Sun, Qixin; Yao, Yingyin

    2012-01-01

    In Arabidopsis and rice, miR159-regulated GAMYB-like family transcription factors function in flower development and gibberellin (GA) signaling in cereal aleurone cells. In this study, the involvement of miR159 in the regulation of its putative target TaGAMYB and its relationship to wheat development were investigated. First, we demonstrated that cleavage of TaGAMYB1 and TaGAMYB2 was directed by miR159 using 5′-RACE and a transient expression system. Second, we overexpressed TamiR159, TaGAMYB1 and mTaGAMYB1 (impaired in the miR159 binding site) in transgenic rice, revealing that the accumulation in rice of mature miR159 derived from the precursor of wheat resulted in delayed heading time and male sterility. In addition, the number of tillers and primary branches in rice overexpressing mTaGAMYB1 increased relative to the wild type. Our previous study reported that TamiR159 was downregulated after two hours of heat stress treatment in wheat (Triticum aestivum L.). Most notably, the TamiR159 overexpression rice lines were more sensitive to heat stress relative to the wild type, indicating that the downregulation of TamiR159 in wheat after heat stress might participate in a heat stress-related signaling pathway, in turn contributing to heat stress tolerance. PMID:23133634

  17. Geothermal direct-heat utilization assistance. Quarterly progress report, January--March 1993

    SciTech Connect

    Lienau, P.

    1993-03-30

    CHC (Geo-Heated Center) staff provided assistance to 103 requests from 26 states, and from Canada, Egypt, Mexico, China, Poland and Greece. A breakdown of the requests according to application include: space and district heating (19), geothermal heat pumps (24), greenhouses (10), aquaculture (4), industrial (4), equipment (3), resources (27), electric power (2) and other (20). Progress is reported on: (1) evaluation of lineshaft turbine pump problems, (2) pilot fruit drier and (3) geothermal district heating marketing tools and equipment investigation. Four presentations and two tours were conducted during the quarter, GHC Quarterly Bulletin Vol. 14, No. 4 was prepared, 14 volumes were added to the library and information was disseminated to 45 requests. Progress reports are on: (1) GHP Teleconference 93, (2) California Energy Buys Glass Mountain Prospect from Unocal and Makes Deal for Newberry Caldera, (3) New Power Plant Planned, (4) Vale to Get Power Plant, (5) BPA Approves Geothermal Project, (6) Update: San Bernardino Reservoir Study, (7) Twenty-nine Palms Geothermal Resources, (8) Geo-Ag Heat Center, Lake County, and (9) Update: Geothermal Wells at Alturas.

  18. Hydrothermal processes at Mount Rainier, Washington

    SciTech Connect

    Frank, D.G.

    1985-01-01

    Field studies and thermal-infrared mapping at Mount Rainier indicate areas of active hydrothermal alteration where excess surface heat flux is about 9 megawatts. Three representative settings include: (1) An extensive area (greater than 12,000 m/sup 2/) of heated ground and slightly acidic boiling-point fumaroles at 76-82/sup 0/C at East and West Craters on the volcano's summit; (2) A small area (less than 500 m/sup 2/) of heated ground and sub-boiling-point fumaroles at 55-60/sup 0/C on the upper flank at Disappointment Cleaver, and other probably similar areas at Willis Wall, Sunset Amphitheater, and the South Tahoma and Kautz headwalls; (3) Sulfate and carbon dioxide enriched thermal springs at 9-24/sup 0/C on the lower flank of the volcano in valley walls beside the Winthrop and Paradise Glaciers. In addition, chloride- and carbon dioxide-enriched thermal springs issue from thin sediments that overlie Tertiary rocks at, or somewhat beyond, the base of the volcanic edifice in valley bottoms of the Nisqually and Ohanapecosh Rivers where maximum spring temperatures are 19-25/sup 0/C, respectively, and where extensive travertine deposits have developed. The heat flow, distribution of thermal activity, and nature of alteration products indicate that a narrow, central hydrothermal system exists within Mount Rainier forming steam-heated snowmelt at the summit craters and localized leakage of steam-heated fluids within 2 kilometers of the summit. The lateral extent of the hydrothermal system is limited in that only sparse, neutral sulfate-enriched thermal water issues from the lower flank of the cone. Simulations of geochemical mass transfer suggest that the thermal springs may be derived from an acid sulfate-chloride parent fluid which has been neutralized by reaction with andesite and highly diluted with shallow ground water.

  19. Biomass-to-biocrude on a chip via hydrothermal liquefaction of algae.

    PubMed

    Cheng, Xiang; Ooms, Matthew D; Sinton, David

    2016-01-21

    Hydrothermal liquefaction uses high temperatures and pressures to break organic compounds into smaller fractions, and is considered the most promising method to convert wet microalgae feedstock to biofuel. Although, hydrothermal liquefaction of microalgae has received much attention, the specific roles of temperature, pressure, heating rate and reaction time remain unclear. We present a microfluidic screening platform to precisely control and observe reaction conditions at high temperature and pressure. In situ observation using fluorescence enables direct, real-time monitoring of this process. A strong shift in the fluorescence signature from the algal slurry at 675 nm (chlorophyll peak) to a post-HTL stream at 510 nm is observed for reaction temperatures at 260 °C, 280 °C, 300 °C and 320 °C (P = 12 MPa), and occurs over a timescale on the order of 10 min. Biocrude formation and separation from the aqueous phase into immiscible droplets is directly observed and occurs over the same timescale. The higher heating values for the sample are observed to increase over shorter timescales on the order of minutes. After only 1 minute at 300 °C, the higher heating value increases from an initial value of 21.97 MJ kg(-1) to 33.63 MJ kg(-1). The microfluidic platform provides unprecedented control and insight into this otherwise opaque process, with resolution that will guide the design of large scale reactors and processes.

  20. Core Cracking and Hydrothermal Circulation Profoundly Affect Ceres' Geophysical Evolution

    NASA Astrophysics Data System (ADS)

    Neveu, Marc; Desch, Steven J.; Castillo-Rogez, Julie C.

    2014-11-01

    The dwarf planet (1)Ceres is about to be visited by the Dawn spacecraft [1]. In addition to a recent report of water vapor emission [2], observations and models of Ceres suggest that its evolution was shaped by interactions between liquid water and silicate rock [3,4].Hydrothermal processes in a heated core require both fractured rock and liquid. Using a new core cracking model coupled to a thermal evolution code [5], we find volumes of fractured rock always large enough for significant interaction to occur. Therefore, liquid persistence is key. It is favored by antifreezes such as ammonia [4], by silicate dehydration which releases liquid, and by hydrothermal circulation itself, which enhances heat transport into the hydrosphere. The heating effect from silicate hydration seems minor. Hydrothermal circulation can profoundly affect Ceres' evolution: it prevents core dehydration via “temperature resets”, global cooling events lasting ~50 Myr, followed by ~1 Gyr periods during which Ceres' interior is nearly isothermal and its hydrosphere largely liquid. Whether Ceres has experienced such extensive hydrothermalism may be determined through examination of its present-day structure. A large, fully hydrated core (radius 420 km) suggests that extensive hydrothermal circulation prevented core dehydration. A small, dry core (radius 350 km) suggests early dehydration from short-lived radionuclides, with shallow hydrothermalism at best. Intermediate structures with a partially dehydrated core seem ambiguous, compatible both with late partial dehydration without hydrothermal circulation, and with early dehydration with extensive hydrothermal circulation. Thus, gravity measurements by the Dawn orbiter [1] could help discriminate between scenarios for Ceres' evolution.References:[1] Russell C. T. & Raymond C. A. (2011) Sp. Sci. Rev. 163, 3-23.[2] Küppers M. et al. (2014) Nature 505, 525-527.[3] Rivkin A. et al. (2011) Sp. Sci. Rev. 163, 95-116.[4] Castillo-Rogez J. C. & Mc

  1. Anhydrite precipitation in seafloor hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

  2. Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

    DTIC Science & Technology

    1983-01-01

    hhEEE|hhEE 1H ; 11:j28 111125 . mm 11111 II ll1 111 .8 MICROCOPY RESOLUTION TESI CHART I fJC ’RL_-SCI-475l I( .-cmon Numters: 1.5.1. 3.1.4, 3.2.1,.3.3...the high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multi- plication and method of...high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multiplication and method of

  3. Garnet phosphors prepared via hydrothermal synthesis

    SciTech Connect

    Phillips, M.L.F.; Walko, R.J.; Shea, L.E.

    1996-05-01

    This project studied hydrothermal synthesis as a route to producing green-emitting cathodoluminescent phosphorus isostructural with yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, or YAG). Aqueous precipitation of Y, Gd, Al, Ga, and Tb salts produced amorphous gels, which were heated with water at 600 C and 3,200 bar to produce crystalline YAG:Tb, Y{sub 3}Ga{sub 5}O{sub 12}:Tb, Y{sub 3}Al{sub 3}Ga{sub 2}O{sub 12}:Tb, and Gd{sub 3}Ga{sub 5}O{sub 12}:Tb powders. Process parameters were identified that yielded submicron YAG:Tb and Y{sub 3}Ga{sub 5}O{sub 12}:Tb powders without grinding. Cathodoluminescent efficiencies were measured as functions of power density at 600 V, using both the hydrothermal garnets and identical phosphor compositions synthesized at high temperatures. Saturation behavior was independent of synthetic technique, however, the hydrothermal phosphorus were less susceptible to damage (irreversible efficiency loss) at very high power densities (up to 0.1 W/cm{sup 2}). The fine grain sizes available with hydrothermal synthesis make it an attractive method for preparing garnet phosphorus for field emission, projection, and head-up displays.

  4. A porous media-based transport model for hydrothermal growth

    NASA Astrophysics Data System (ADS)

    Chen, Q. S.; Prasad, V.; Chatterjee, A.; Larkin, J.

    1999-03-01

    A hydrothermal crystal growth system usually consists of a porous bed of polycrystalline charge, predetermined volume of a solvent, suitably oriented seeds, etc. For preliminary study of flow and heat transfer, the convective system for hydrothermal growth can be considered as a composite fluid and porous layer and the flow in the nutrient bed can be modeled using the Darcy-Brinkman-Forchheimer formulation. A three-dimensional algorithm has been developed to examine the flow and heat transfer in a typical autoclave system, which is partially heated on the vertical wall and adiabatic at the top and bottom. The study presents, for the first time, a transport model for hydrothermal growth and the possible flow structure in an autoclave. The temperature and flow fields are analyzed for a few selected cases.

  5. Ecology of deep-sea hydrothermal vent communities: A review

    SciTech Connect

    Lutz, R.A.; Kennish, M.J. )

    1993-08-01

    The present article reviews studies of the past 15 years of active and inactive hydrothermal vents. The focus of the discussion is on the ecology of the biological communities inhabiting hydrothermal vents. These communities exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. The authors attempt to relate the biology of hydrothermal vent systems to geology. Future directions for hydrothermal vent research are suggested. Since many vent populations are dependent on hydrothermal fluids and are consequently unstable, both short- and long-term aspects of the ecology of the vent organisms and the influence of chemical and geological factors on the biology of vent systems need to be established. 200 refs., 28 figs.

  6. Aqueous geochemistry of the Thermopolis hydrothermal system, southern Bighorn Basin, Wyoming, U.S.A.

    SciTech Connect

    Kaszuba, John P.; Sims, Kenneth W.W.; Pluda, Allison R.

    2014-06-01

    The Thermopolis hydrothermal system is located in the southern portion of the Bighorn Basin, in and around the town of Thermopolis, Wyoming. It is the largest hydrothermal system in Wyoming outside of Yellowstone National Park. The system includes hot springs, travertine deposits, and thermal wells; published models for the hydrothermal system propose the Owl Creek Mountains as the recharge zone, simple conductive heating at depth, and resurfacing of thermal waters up the Thermopolis Anticline.

  7. Aqueous geochemistry of the Thermopolis hydrothermal system, southern Bighorn Basin, Wyoming, U.S.A.

    DOE PAGES

    Kaszuba, John P.; Sims, Kenneth W.W.; Pluda, Allison R.

    2014-06-01

    The Thermopolis hydrothermal system is located in the southern portion of the Bighorn Basin, in and around the town of Thermopolis, Wyoming. It is the largest hydrothermal system in Wyoming outside of Yellowstone National Park. The system includes hot springs, travertine deposits, and thermal wells; published models for the hydrothermal system propose the Owl Creek Mountains as the recharge zone, simple conductive heating at depth, and resurfacing of thermal waters up the Thermopolis Anticline.

  8. Human immune response directed against Plasmodium falciparum heat shock-related proteins.

    PubMed Central

    Kumar, N; Zhao, Y; Graves, P; Perez Folgar, J; Maloy, L; Zheng, H

    1990-01-01

    Heat shock-related stress proteins present in all eucaryotes and procaryotes have been shown to be immune targets in a broad range of infections. We have analyzed sera from people exposed primarily to Plasmodium falciparum for specific antibodies against two heat shock-related proteins (proteins similar to the heat shock protein with a molecular weight of 75,000 [Pfhsp] and a glucose-regulated protein with a molecular weight of 72,000 [Pfgrp]). In an immunoprecipitation analysis with metabolically labeled parasites and synthetic peptides in an enzyme-linked immunosorbent assay, specific antibodies against Pfhsp and Pfgrp were detected in the sera of these individuals. Sera from people exposed to a different human malarial parasite, Plasmodium vivax, did not react with the peptides in an enzyme-linked immunosorbent assay. Southern blot analysis with DNA isolated from P. falciparum from different geographical locations showed a conservation of genes for these stress proteins; thus, they are likely to be immune targets in various endemic areas. Lymphocytes from two tested immune donors responded in proliferation assays to purified Pfhsp and Pfgrp and purified recombinant proteins. However, a similar response was also seen in lymphocytes from nonimmune individuals and has raised questions pertaining to a generalized responsiveness of lymphocytes to some common determinants present in heat shock-related proteins in various pathogens. Images PMID:1691147

  9. [Hygienic evaluation of direct heating of the air delivered to the shaft].

    PubMed

    Velichkovskiĭ, B T; Malikov, Iu K; Troitskaia, N A; Belen'kaia, M A; Sergeeva, N V; Shirokova, O V; Kashanskiĭ, S V; Slyshkina, T V; Simonova, O V; Zykova, V A

    2011-01-01

    The paper gives the results of exploring a test pre-heating system for the air (APHS) delivered to the shaft. The system has been first used in the Urals. The supply air is heated by burning natural gas in the air current. The APHS system with a RG air heater (000 "Gas-Engineering") is equipped in addition to the existing heaters to enhance heat supply reliability in northern conditions. The data of the studies show that in all periods of the heating season (interseason, moderate frosts, the coldest month), the concentrations of hazardous substances, such as nitric oxides, nitric dioxide, sulfur dioxide, carbon dioxide, benz(a)pyrene, solid aerosol in the shaft-delivered air, do not exceed those given in the existing regulation provided that the design operating conditions are met. With the maximum gas consumption, the coldest month only was marked by the nitric dioxide content being greater than the standard values, causing the maximum projected natural gas consumption to be lower in the APHS system. The air level of nitric dioxide proved to be a major hygiene indicator while using this air heater.

  10. 76 FR 71835 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-18

    ... viewing pane) or a sealed system, they do not provide the same heating function as gas fireplaces, gas fireplace inserts, and gas stoves, which are constructed as enclosed systems. Due to these differences, DOE...) ANSI Z21.50-2007 (CSA 2.22-2007), (``ANSI Z21.50''), ``Vented Gas Fireplaces,'' Approved February 22...

  11. Soil heat flux variability influenced by row direction in irrigated cotton

    USDA-ARS?s Scientific Manuscript database

    In applications of micrometeorological techniques for surface energy balance estimation, most often the least attention and effort has been devoted to determining the area-average soil heat flux (G). Although spatial and temporal variability in G under sparse/clumped vegetation conditions is signif...

  12. Direct-use geothermal district heating projects in the US. A summary

    SciTech Connect

    Fornes, A.O.

    1981-10-01

    Brief summaries of geothermal district heating projects are presented for the following: Boise, Idaho; Elko, Nevada; Ephrata, Washington; Hawthorne, Nevada; Klamath Falls, Oregon; Lakeview, Oregon; Madison County, Idaho; North Bonneville, Washington; Pagosa Springs, Colorado; Preston, Idaho; Reno, Nevada; Susanville, California; Thermopolis, Wyoming; and Utah State Prison, Utah. (MHR)

  13. Super eruption environments make for "super" hydrothermal explosions: Extreme hydrothermal explosions in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Morgan, L. A.; Shanks, W. P.; Pierce, K. L.

    2006-12-01

    Hydrothermal explosions are violent events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments over areas that range from a few meters in diameter up to several kilometers in diameter. Hydrothermal explosions occur where shallow interconnected reservoirs of steam-saturated fluids underlie thermal fields. Sudden reduction in pressure causes the fluids to flash to steam resulting in significant expansion, rock fragmentation, and debris ejection. In Yellowstone, at least 20 large (>100 meters in diameter) hydrothermal explosions have been identified, and the scale of the individual events dwarfs similar features in other hydrothermal and geothermal areas of the world. Large explosions in Yellowstone have occurred over the past 16 ka at an interval of ~1 per every 700 yrs and similar events are likely to occur in the future. Our studies of hydrothermal explosive events indicate: 1) none are associated with magmatic or volcanic events; 2) several have been triggered by seismic events coupled with other processes; 3) lithic clasts and matrix from explosion deposits are extensively altered, indicating long-term, extensive hydrothermal mineralization in areas that were incorporated into the explosion deposit; 4) many lithic clasts in explosion breccia deposits contain evidence of repeated fracturing and cementation; and 4) dimensions of many documented large hydrothermal explosion craters in Yellowstone are similar to the dimensions of currently active geyser basins or thermal areas in Yellowstone. The vast majority of active thermal areas in Yellowstone are characterized by 1) high-temperature hot-water systems in areas of high heat-flow, 2) extensive systems of hot springs, fumaroles, geysers, sinter terraces, mud pots, and, in places, small hydrothermal explosion craters, 3) widespread alteration of host rocks, 4) large areal dimensions (>several 100 m) and 5) intermittent but long-lived activity (40,000 to 300,000 years). Critical

  14. Insights From Magnesium Isotopic Compositions on the Oceanic Hydrothermal Circulation: Is Seamount Weathering the Solution?

    NASA Astrophysics Data System (ADS)

    Galy, A.; Carder, E.; Elderfield, H.

    2006-12-01

    It has been long recognised that the input of Mg in the ocean by river is removed by precipitation of Mg-rich bearing phases, either directly from the ocean such as dolomite or through hydrothermal circulation in the oceanic crust. The sampling of hydrothermal fluids demonstrated the efficiency of Mg consumption by the alteration of the oceanic crust, even at temperatures as low as 15°. For high-temperature fluids vented through black or white smokers in the vicinity of the ridge, the Mg concentration is up to 50 time lower than in seawater, and the close relationship between chlorine and Mg led to the idea that seawater was feeding the hydrothermal system and that Mg is quantitatively removed from it during high-T° alteration, the so called zero Mg hypothesis. Despite some hint for a non zero Mg hydrothermal end-member for a handful sites, the low concentration of Mg in oceanic hydrothermal fluids (around 1 mmol/l) has been mainly attributed to contamination by seawater during the sampling. Here we present Mg isotopic composition of 14 seawater samples from the Atlantic, Pacific and Indian Oceans and the Mediterranean and Red Seas and covering a range of depth of almost 5km and 26 hydrothermal fluids from 7 sites in the Atlantic and Pacific Oceans with temperature from 15° to 380°C. We find the magnesium isotope composition of seawater to be constant, with a δ^{26}Mg = -0.82±0.10 ‰ relative to the DSM3 standard. This value is consistent with a long residence time for Mg in seawater. In addition, out of the 26 hydrothermal fluids studied, more than 58% differ from seawater for their Mg isotopic composition by more than 2σ. This number rises up to 88% at 2σmean level and the shift is systematic with the fluids being either indistinguishable from seawater or enriched in light isotopes by up to 2.4‰ in δ^{26}Mg. This clearly demonstrates that fluids having low Mg concentrations are not solely bearing Mg added by contamination during sampling. The isotopic

  15. Reconstruction of Ancestral Hydrothermal Systems on Mount Rainier Using Hydrothermally Altered Rocks in Holocene Debris Flows and Tephras

    NASA Astrophysics Data System (ADS)

    John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.

    2005-12-01

    Mount Rainier is the result of episodic stages of edifice growth during periods of high eruptive activity and edifice destruction during periods of relative magmatic quiescence over the past 500 kyr. Edifice destruction occurred both by slow erosion and by catastrophic collapses, some of which were strongly influenced by hydrothermal alteration. Several large-volume Holocene debris-flow deposits contain abundant clasts of hydrothermally altered rocks, most notably the 4-km3 clay-rich Osceola Mudflow which formed by collapse of the northeast side and upper 1000+ m of the edifice about 5600 ya and flowed >120 km downstream into Puget Sound. Mineral assemblages and stable isotope data of hydrothermal alteration products in Holocene debris-flow deposits indicate formation in distinct hydrothermal environments, including magmatic-hydrothermal, steam-heated (including a large fumarolic component), magmatic steam (including a possible fumarolic component), and supergene. The Osceola Mudflow and phreatic components of coeval tephras contain the highest-temperature and inferred most deeply formed alteration minerals; assemblages include magmatic-hydrothermal quartz-alunite, quartz-topaz, quartz-pyrophyllite and quartz-illite (all +pyrite), in addition to steam-heated opal-alunite-kaolinite and abundant smectite-pyrite. In contrast, the Paradise lahar, which formed by a collapse of the surficial upper south side of the edifice, contains only steam-heated assemblages including those formed largely above the water table from condensation of fumarolic vapor (opal-alunite-jarosite). Younger debris-flow deposits on the west side of the volcano (Round Pass lahar and Electron Mudflow) contain only smectite-pyrite alteration, whereas an early 20th century rock avalanche on Tahoma Glacier also contains magmatic-hydrothermal alteration that is exposed in the avalanche headwall of Sunset Amphitheater. Mineralogy and isotopic composition of the alteration phases, geologic and

  16. Direct observation of phase transformations in the simulated heat-affected zone of a 9Cr martensitic steel

    SciTech Connect

    Mayr, Peter; Palmer, T. A.; Elmer, J. W.; Specht, Eliot D

    2008-01-01

    An experimental test melt of a boron alloyed 9Cr-3W-3Co-V,Nb steel for high temperature applications in the thermal power generation industry was produced by vacuum induction melting. This grade of steel typically displays a homogeneous tempered martensitic microstructure in the as-received condition. However, after welding, this microstructure is significantly altered, resulting in a loss of its desired properties. The phase transformations during simulated thermal cycles typical of those experienced in the weld heat-affected zone (HAZ) were directly observed by in situ X-ray diffraction experiments using synchrotron radiation. Heating rates of 10 C s-1 and 100 C s-1 up to a peak temperature of 1300 C are investigated here. The final microstructures observed after both simulated weld thermal cycles are primarily composed of martensite with approximately 4% retained delta ferrite and 4% retained austenite, by volume. With the temporal resolution of the in situ X-ray diffraction technique, phase transformations from tempered martensite to austenite to delta ferrite during heating and to martensite during cooling were monitored. With this technique, the evolution of the final microstructure through both heating and cooling is monitored, providing additional context to the microstructural observations.

  17. Hydrothermal Reactivity of Amines

    NASA Astrophysics Data System (ADS)

    Robinson, K.; Shock, E.; Hartnett, H. E.; Williams, L. B.; Gould, I.

    2013-12-01

    The reactivity of aqueous amines depends on temperature, pH, and redox state [1], all of which are highly variable in hydrothermal systems. Temperature and pH affect the ratio of protonated to unprotonated amines (R-NH2 + H+ = R-NH3+), which act as nucleophiles and electrophiles, respectively. We hypothesize that this dual nature can explain the pH dependence of reaction rates, and predict that rates will approach a maximum at pH = pKa where the ratio of protonated and unprotonated amines approaches one and the two compounds are poised to react with one another. Higher temperatures in hydrothermal systems allow for more rapid reaction rates, readily reversible reactions, and unique carbon-nitrogen chemistry in which water acts as a reagent in addition to being the solvent. In this study, aqueous benzylamine was used as a model compound to explore the reaction mechanisms, kinetics, and equilibria of amines under hydrothermal conditions. Experiments were carried out in anoxic silica glass tubes at 250°C (Psat) using phosphate-buffered solutions to observe changes in reaction rates and product distributions as a function of pH. The rate of decomposition of benzylamine was much faster at pH 4 than at pH 9, consistent with the prediction that benzylamine acts as both nucleophile and an electrophile, and our estimate that the pKa of benzylamine is ~5 at 250°C and Psat. Accordingly, dibenzylamine is the primary product of the reaction of two benzylamine molecules, and this reaction is readily reversible under hydrothermal conditions. Extremely acidic or basic pH can be used to suppress dibenzylamine production, which also suppresses the formation of all other major products, including toluene, benzyl alcohol, dibenzylimine, and tribenzylamine. This suggests that dibenzylamine is the lone primary product that then itself reacts as a precursor to produce the above compounds. Analog experiments performed with ring-substituted benzylamine derivatives and chiral

  18. Geothermal direct-heat utilization assistance. Quarterly project progress report, April--June 1993

    SciTech Connect

    Lienau, P.

    1993-06-01

    Technical assistance was provided to 60 requests from 19 states. R&D progress is reported on: evaluation of lineshaft turbine pump problems, geothermal district heating marketing strategy, and greenhouse peaking analysis. Two presentations and one tour were conducted, and three technical papers were prepared. The Geothermal Progress Monitor reported: USGS Forum on Mineral Resources, Renewable Energy Tax Credits Not Working as Congress Intended, Geothermal Industry Tells House Panel, Newberry Pilot Project, and Low-Temperature Geothermal Resources in Nevada.

  19. Direct Electricity from Heat: A Solution to Assist Aircraft Power Demands

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2010-01-01

    A thermionic device produces an electrical current with the application of a thermal gradient whereby the temperature at one electrode provides enough thermal energy to eject electrons. The system is totally predicated on the thermal gradient and the work function of the electrode collector relative to the emitter electrode. Combined with a standard thermoelectric device high efficiencies may result, capable of providing electrical energy from the waste heat of gas turbine engines.

  20. Demand Controlled Economizer Cycles: A Direct Digital Control Scheme for Heating, Ventilating, and Air Conditioning Systems,

    DTIC Science & Technology

    1984-05-01

    includes a heating coil and thermostatic control to maintain the air in this path at an elevated temperature, typically around 80 degrees Farenheit (80 F...1238 Aug 1 1236 1237 52 1074 1126 50 1033 1083 Sep 8 8 5W 862 7T 600 678 75 603 7r Oct 51 400 451 119 204 323 115 207 322 ov 64 123 287 187 71 258

  1. Dynamic m6A mRNA methylation directs translational control of heat shock response

    PubMed Central

    Zhou, Jun; Wan, Ji; Gao, Xiangwei; Zhang, Xingqian; Qian, Shu-Bing

    2015-01-01

    The most abundant mRNA post-transcriptional modification is N6-methyladenosine (m6A) that has broad roles in RNA biology1-5. In mammalian cells, the asymmetric distribution of m6A along mRNAs leaves relatively less methylation in the 5′ untranslated region (5′UTR) compared to other regions6,7. However, whether and how 5′UTR methylation is regulated is poorly understood. Despite the crucial role of the 5′UTR in translation initiation, very little is known whether m6A modification influences mRNA translation. Here we show that in response to heat shock stress, m6A is preferentially deposited to the 5′UTR of newly transcribed mRNAs. We found that the dynamic 5′UTR methylation is a result of stress-induced nuclear localization of YTHDF2, a well characterized m6A “reader”. Upon heat shock stress, the nuclear YTHDF2 preserves 5′UTR methylation of stress-induced transcripts by limiting the m6A “eraser” FTO from demethylation. Remarkably, the increased 5′UTR methylation in the form of m6A promotes cap-independent translation initiation, providing a mechanism for selective mRNA translation under heat shock stress. Using Hsp70 mRNA as an example, we demonstrate that a single site m6A modification in the 5′UTR enables translation initiation independent of the 5′ end m7G cap. The elucidation of the dynamic feature of 5′UTR methylation and its critical role in cap-independent translation not only expands the breadth of physiological roles of m6A, but also uncovers a previously unappreciated translational control mechanism in heat shock response. PMID:26458103

  2. Direct estimate of water, heat, and salt transport through the Strait of Otranto

    NASA Astrophysics Data System (ADS)

    Yari, Sadegh; Kovačević, Vedrana; Cardin, Vanessa; Gačić, Miroslav; Bryden, Harry L.

    2012-09-01

    The transport of water volume, salt and heat was calculated using continuous measurements of currents in the Otranto Strait for a one-year period in 1994-95. Temperature and salinity data sets, available from five hydrographic surveys, were used to obtain the seasonal temperature and salinity distributions at the Otranto transect. The Variational Inverse Method (VIM) was applied to reconstruct spatial distributions of the de-tided low-pass inflowing current component, salinity and temperature. Errors associated with estimates of transports are influenced by the data coverage: the higher the spatial resolution, the smaller the error and vice versa. Volume transport reaches a maximum in winter and spring and attains its minimum in summer. The obtained volume transport [˜1 Sv (106 m3s-1)] should be considered a lower limit value since in that period the Adriatic was producing relatively small quantities of deep water due to the inflow of low-salinity (high buoyancy) waters and relatively mild winters. Comparing the mean advective heat input and the air-sea heat loss, the same order of magnitude between the two has been obtained which is satisfactory considering the possible errors of the two approaches. The relative importance of the eddy heat transport to the total transport is estimated to be only about 5% and thus it can be neglected in a first approximation. The salt transport estimates show a net input, suggesting a salinity increase during the period of study; this was confirmed from the long-term salinity data in the Southern Adriatic.

  3. Particle concentrating and sorting under a rotating electric field by direct optical-liquid heating in a microfluidics chip.

    PubMed

    Chen, Yu-Liang; Jiang, Hong-Ren

    2017-05-01

    We demonstrate a functional rotating electrothermal technique for rapidly concentrating and sorting a large number of particles on a microchip by the combination of particle dielectrophoresis (DEP) and inward rotating electrothermal (RET) flows. Different kinds of particles can be attracted (positive DEP) to or repelled (negative DEP) from electrode edges, and then the n-DEP responsive particles are further concentrated in the heated region by RET flows. The RET flows arise from the spatial inhomogeneous electric properties of fluid caused by direct infrared laser (1470 nm) heating of solution in a rotating electric field. The direction of the RET flows is radially inward to the heated region with a co-field (the same as the rotating electric field) rotation. Moreover, the velocity of the RET flows is proportional to the laser power and the square of the electric field strength. The RET flows are significant over a frequency range from 200 kHz to 5 MHz. The RET flows are generated by the simultaneous application of the infrared laser and the rotating electric field. Therefore, the location of particle concentrating can be controlled within the rotating electric field depending on the position of the laser spot. This multi-field technique can be operated in salt solutions and at higher frequency without external flow pressure, and thus it can avoid electrokinetic phenomena at low frequency to improve the manipulation accuracy for lab-on-chip applications.

  4. A portable direct-PV thermoelectric vaccine refrigerator with ice storage through heat pipes

    NASA Astrophysics Data System (ADS)

    Jiajitsawat, Somchai

    The objective of this research work was to develop a portable solar refrigeration system capable of maintaining vaccine temperatures between 2 °C and 8 °C. The main system under this study consisted of thermoelectric modules as cooling generators with latent heat energy storage (LHES) using water as cooling backup along with heat pipes as passive temperature controllers to avoid freezing the vaccines. The system was fabricated and tested. The results showed that the system can maintain the vaccine storage temperature at 2 °C and 8 °C under ambient temperature up to 30 °C with minimum power consumption of 30 Watt. The proposed heat pipes to maintain the vaccine storage temperature satisfied the design criteria. However, the energy consumption of the TEM was higher than anticipated. A small vapor compressor system was tested and shows promise to replace the TEM for cooling. Inserting the aluminum matrix in the ice chamber not only decreased the charging time but also decreased the discharging time since less phase change material was available for energy storage. Three models of the system were developed under different assumptions. The lumped model was adequate to predict the system performance during charging process. The other distributed models were able to predict the melting and cooling time more accurately than that of the lumped model and provided more detailed on the temperature distribution and change of the water phase in the ice chamber.

  5. Hydrothermal minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Indonesia

    USGS Publications Warehouse

    Moore, Diane E.; Hickman, S.; Lockner, D.A.; Dobson, P.F.

    2001-01-01

    Detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike-slip Great Sumatran fault zone near Silangkitang, North Sumatra, supports a model for enhanced hydrothermal circulation adjacent to this major plate-boundary fault. Two wells (A and C) were drilled nearly vertically ??1 km southwest of the eastern (i.e., the principal) fault trace, and the third, directional well (B) was drilled eastward from the site of well A to within ??100 m of the principal fault trace. The examined core samples come from depths of 1650-2120 m at measured well temperatures of 180-320 ??C. The samples collected near the principal fault trace have the highest temperatures, the largest amount of secondary pore space that correlates with high secondary permeability, and the most extensive hydrothermal mineral development. Secondary permeability and the degree of hydrothermal alteration decrease toward the southwestern margin of the fault zone. These features indicate episodic, localized flow of hot, possibly CO2-rich fluids within the fault zone. The microstructure populations identified in the core samples correlate to the subsidiary fault patterns typical of strike-slip faults. The geothermal reservoir appears to be centered on the fault zone, with the principal fault strands and adjoining, highly fractured and hydrothermally altered rock serving as the main conduits for vertical fluid flow and advective heat transport from deeper magmatic sources.

  6. Heat treatment of whole milk by the direct joule effect--experimental and numerical approaches to fouling mechanisms.

    PubMed

    Fillaudeau, L; Winterton, P; Leuliet, J C; Tissier, J P; Maury, V; Semet, F; Debreyne, P; Berthou, M; Chopard, F

    2006-12-01

    The development of alternative technologies such as the direct Joule effect to pasteurize and sterilize food products is of great scientific and industrial interest. Our objective was 1) to gain insight into the ability to ensure ultra-high-temperature treatment of milk and 2) to investigate the links among thermal, hydraulic, and electrical phenomena in relation to fouling in a direct Joule effect heater. The ohmic heater [OH; E perpendicular to v (where E is the electrical field and v is the velocity); P (power) = 15 kW] was composed of 5 flat rectangular cells [e (space between the plate and electrode) = 15 mm, w (wall) = 76 mm, and L (length of the plate in plate heat exchanger or electrode) = 246 mm]--3 active cells to ensure heating and 2 (at the extremities) for electrical insulation and the recovery of leakage currents. In the first step, the thermal performance of the OH was investigated vs. the flow regimen [50 < Re (Reynolds number) < 5,000], supplied power (0 < P < 15 kW), and electrical conductivity of fluids (0.1 < sigma(20 degrees C) < 2 S/m) under clean conditions with model fluids. This protocol enabled a global thermal approach (thermal and electrical balance, modeling of the temperature profile of a fluid) and local analysis of the wall temperature of the electrode. An empirical correlation was established to estimate the temperature gradient, T(w)-T(b) (where T(w) is the wall temperature and T(b) is the product temperature) under clean conditions (without fouling) and was used to define operating conditions for pure-volume and direct-resistance heating. In the second step, the ability of OH to ensure the ultra-high-temperature treatment of whole milk was investigated and compared with a plate heat exchanger. Special care was taken to investigate the heat transfer phenomena occurring over a range of temperatures from 105 to 138 degrees C. This temperature range corresponds to the part of the process made critical by protein and mineral fouling

  7. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    NASA Astrophysics Data System (ADS)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2017-01-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  8. The Hydrothermal System at the Grand Canyon of the Yellowstone River: Exposed and Hidden

    NASA Astrophysics Data System (ADS)

    Jaworowski, C.; Heasler, H. P.; Susong, D. D.; Neale, C. M.; Sivarajan, S.; Masih, A.

    2012-12-01

    Combining calibrated and corrected night-time, airborne thermal infrared imaging with field information from the 2008 drilling of the Canyon borehole strainmeter (B206) in Yellowstone National Park emphasizes the extensive nature of Yellowstone's hydrothermal system. Both studies contributed to an understanding of the vertical and horizontal flow of heat and fluids through the bedrock in this area. Night-time, airborne thermal infrared imagery, corrected for emissivity and atmosphere clearly shows north-trending faults and fractures transmitting heat and fluids through the rhyolitic bedrock and into the overlying glacial sediments near the Canyon borehole. Along the Grand Canyon of the Yellowstone, the Clear Lake hydrothermal area is an example of hydrothermal alteration at the ground surface. The numerous hydrothermal features exposed in the nearby Grand Canyon of the Yellowstone River and its hydrothermally altered walls are clear evidence of the exposed hydrothermal system. The bedrock geology, geologic processes, and hydrothermal activity combined to form the dramatic Grand Canyon of the Yellowstone. The night-time thermal infrared imagery provides a new view of this exposed hydrothermal system for scientists and visitors. Scientists and Yellowstone Park managers carefully sited the Canyon borehole strainmeter in a green, grassy meadow to insure successful completion of the borehole in a non-hydrothermal area. The closest hydrothermal feature to the drilling site was about 2.5 km to the east. Although excellent exposures of hydrothermal altered bedrock are present about 1.5 km east at the Lower Falls and the Grand Canyon of the Yellowstone River, the connection between exposed hydrothermal areas and the borehole site was not obvious. After drilling through 9 m of brown-gray muds and 113 m of rock, a bottom hole temperature of 81.2 degrees Celsius precluded drilling the hole any deeper than 122 m. The post-drilling data collected from B206 and the airborne

  9. CO2 Step-heating of Feldspar Crystals: A New Technique to Derive Paleomagnetic Directional and Paleointensity Data

    NASA Astrophysics Data System (ADS)

    Cottrell, R. D.; Tarduno, J. A.

    2003-12-01

    Feldspar grains can contain minute magnetic inclusions (50-300 nm in size) that have been shown to faithfully record the modern magnetic field. Here we explore the possibility of using step heating techniques with a CO2 laser to extract direction and paleointensity information from such crystals. Test samples were chosen from lavas recovered at Nintoku Seamount (Ocean Drilling Program Leg 197, Site 1205). Samples from lava units that displayed stable behavior during thermal demagnetization (Tarduno et al., 2003) were chosen for the experiments. Basalt groundmass was carefully etched away from thin sections so that only feldspar grains free of visible inclusions remained. Neither the rock chip used to make the thin section, nor the epoxy needed to hold the chip to the microscope slide required heating during the curing process, reducing the chance of the acquisition of spurious magnetizations. A mark was etched into the glass slide to maintain sample orientation. Slides were trimmed so that a single feldspar grain could be heated with a CO2 laser inside a field free space (provided by shields). The feldspar grains examined ranged in size from 1 mm to several mm (all were approximately 1 mm thick). All remanence measurements were made with a 2G Enterprises SQUID magnetometer, with high resolution sensing coils. In initial experiments, an oriented feldspar grain was given an isothermal remanent magnetization (IRM). Step heating was carried out with a CO2 laser with wattage calibrated against a similar sample attached to a thermocouple. The demagnetization of the IRM showed a simple decay to the origin in orthogonal vector plots. Preliminary experiments to investigate natural remanent magnetizations held by the Site 1205 feldspar grains show directions similar to those of the whole rock from which they were extracted.

  10. A MEMS-based heating holder for the direct imaging of simultaneous in-situ heating and biasing experiments in scanning/transmission electron microscopes.

    PubMed

    Mele, Luigi; Konings, Stan; Dona, Pleun; Evertz, Francis; Mitterbauer, Christoph; Faber, Pybe; Schampers, Ruud; Jinschek, Joerg R

    2016-04-01

    The introduction of scanning/transmission electron microscopes (S/TEM) with sub-Angstrom resolution as well as fast and sensitive detection solutions support direct observation of dynamic phenomena in-situ at the atomic scale. Thereby, in-situ specimen holders play a crucial role: accurate control of the applied in-situ stimulus on the nanostructure combined with the overall system stability to assure atomic resolution are paramount for a successful in-situ S/TEM experiment. For those reasons, MEMS-based TEM sample holders are becoming one of the preferred choices, also enabling a high precision in measurements of the in-situ parameter for more reproducible data. A newly developed MEMS-based microheater is presented in combination with the new NanoEx™-i/v TEM sample holder. The concept is built on a four-point probe temperature measurement approach allowing active, accurate local temperature control as well as calorimetry. In this paper, it is shown that it provides high temperature stability up to 1,300°C with a peak temperature of 1,500°C (also working accurately in gaseous environments), high temperature measurement accuracy (<4%) and uniform temperature distribution over the heated specimen area (<1%), enabling not only in-situ S/TEM imaging experiments, but also elemental mapping at elevated temperatures using energy-dispersive X-ray spectroscopy (EDS). Moreover, it has the unique capability to enable simultaneous heating and biasing experiments.

  11. Non-Newtonian unconfined flow and heat transfer over a heated cylinder using the direct-forcing immersed boundary-thermal lattice Boltzmann method.

    PubMed

    Amiri Delouei, A; Nazari, M; Kayhani, M H; Succi, S

    2014-05-01

    In this study, the immersed boundary-thermal lattice Boltzmann method has been used to simulate non-Newtonian fluid flow over a heated circular cylinder. The direct-forcing algorithm has been employed to couple the off-lattice obstacles and on-lattice fluid nodes. To investigate the effect of boundary sharpness, two different diffuse interface schemes are considered to interpolate the velocity and temperature between the boundary and computational grid points. The lattice Boltzmann equation with split-forcing term is applied to consider the effects of the discrete lattice and the body force to the momentum flux, simultaneously. A method for calculating the Nusselt number based on diffuse interface schemes is developed. The rheological and thermal properties of non-Newtonian fluids are investigated under the different power-law indices and Reynolds numbers. The effect of numerical parameters on the accuracy of the proposed method has been investigated in detail. Results show that the rheological and thermal properties of non-Newtonian fluids in the presence of a heated immersed body can be suitably captured using the immersed boundary thermal lattice Boltzmann method.

  12. The Hydrothermal Circulation of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Kjellsson, J.; Doos, K.; Laliberté, F. B.; Zika, J. D.

    2012-12-01

    The atmospheric circulation maintains the energy balance between the warm/moist regions and the colder/drier regions of the Earth. A well-studied aspect of the atmospheric circulation is the time-averaged zonal-mean meridional overturning circulation. The meridional overturning describes the Hadley, Ferrel and Polar Cells in each hemisphere. However, in isobaric coordinates, the zonal average is unable to capture zonally asymmetric features such as the Walker circulation and transient exchanges of heat and moisture. The Walker Circulation is restricted to equatorial regions, and is commonly studied using a meridional mean over a limited region with ill-defined latitudinal boundaries. The Walker Circulation is thus neither mass-conserving nor uniquely defined. To overtcome these limitations, the Walker circulation is often diagnosed using vertical velocity. As a consequence, it is difficult to distinguish between the zonal-mean circulation (Hadley Circulation) and the zonal asymmetries (Walker Circulation). Global mass and energy transport is here investigated using a moisture-heat perspective. A hydrothermal streamfunction is defined where latent heat and dry static energy act as coordinates. Because the hydrothermal streamfunction resides in purely thermodynamical space, it does not differentiate between zonal, meridional, or vertical transports. The hydrothermal streamfunction shows the global overturning circulation as a unified cycle. It describes a cycle with three branches: i) a convective branch where latent heat is converted into sensible heat along moist adiabats, ii) a cooling branch where dry air loses energy due to radiative damping and iii) a return branch where cold, dry air is heated and moistened following the Clausius-Clapeyron relationship. These three branches form a single cell of more than 400 Sv with at least 100 Sv due to zonal motions such as the Walker Circulation. The cell is also found fairly stationary on seasonal and inter

  13. Direct retrieval of ocean surface evaporation and latent heat flux from the spacebased observations

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Tang, W.

    2000-01-01

    The Tropical Rain Measuring Mission (TRMM) provides the opportunity to improve the spacebased estimation of evaporation. An algorithm for retrieving evaporation directly from the radiances observed by the TRMM Microwave Imager and its validation results are described.

  14. Photon-Noise Limited Direct Detector Based on Disorder-Controlled Electron Heating

    NASA Technical Reports Server (NTRS)

    Karasik, B.; McGrath, W.; Gershenson, M.; Sergeev, A.

    1999-01-01

    We present a new concept for a hot-electron direct detector (HEDD) capable of counting single millimeter-wave photons. The detector is based on a transition edge sensor (1-meu size bridge) made form a disordered superconducting film.

  15. Photon-Noise Limited Direct Detector Based on Disorder-Controlled Electron Heating

    NASA Technical Reports Server (NTRS)

    Karasik, B.; McGrath, W.; Gershenson, M.; Sergeev, A.

    1999-01-01

    We present a new concept for a hot-electron direct detector (HEDD) capable of counting single millimeter-wave photons. The detector is based on a transition edge sensor (1-meu size bridge) made form a disordered superconducting film.

  16. Hydrothermal activity at the Trans-Atlantic Geotraverse Hydrothermal Field, Mid-Atlantic Ridge crest at 26°N

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Thompson, G.; Mottl, M. J.; Karson, J. A.; Jenkins, W. J.; Graham, D.; Mallette, M.; von Damm, K.; Edmond, J. M.

    1984-12-01

    The first submersible observations of the only known active submarine hydrothermal field on a slow-spreading oceanic ridge are incorporated with results of 10 prior years of investigation to derive an understanding of periodicity, duration, and varying intensity of hydrothermal activity at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge crest near latitude 26°N. Hydrothermal activity has persisted at this location for at least 1×106 years based on the distribution of hydrothermal and hydrogenous mineralization with respect to crustal age. The hydrothermal activity has been cyclic, multistage, and episodic. Prior high-temperature hydrothermal venting stages with a periodicity of the order of 1×104 years and duration of the order of 101 years are deduced from the estimated ages of discrete sedimentary layers anomalously enriched in Cu, Fe, and Zn and correspond with the independently determined periodicity of volcanic eruptive cycles on the Mid-Atlantic Ridge. The most recent episode of high-temperature venting is inferred to have ceased in the recent past based on metal enrichment (Cu, Fe, Zn) in the surficial sediment layer. Low-temperature hydrothermal venting stages with a duration of the order of 1×104 years intervene between the short high-temperature stages and produce stratiform deposits of layered and earthy manganese oxide, iron oxide, hydroxide, and silicate. Bivalve-like forms with the characteristics of vent clams in various stages of dissolution are identified on bottom photographs. The fresh appearance of intact tubules composed of iron hydroxide that acted as vents on relict deposits, conductive heat flow anomalies in the sediment column, and the record of temperature anomalies and excess 3He in the near-bottom water column, suggest that the low-temperature hydrothermal discharge is intermittent at individual vents on a time scale of years.

  17. Direct-drive Energetics of laser-Heated Foam Liners for Hohlraums

    NASA Astrophysics Data System (ADS)

    Moore, Alastair; Thomas, Cliff; Baker, Kevin; Morton, John; Baumann, Ted; Biener, Monika; Bhandarkar, Suhas; Hinkel, Denise; Jones, Oggie; Meezan, Nathan; Moody, John; Nikroo, Abbas; Rosen, Mordy; Hsing, Warren

    2016-10-01

    Lining the walls of a high-Z hohlraum cavity with a low-density foam is predicted to mitigate the challenge presented by hohlraum wall expansion. Once heated, wall material quickly fills the cavity and can impede laser beam propagation. To avoid this, ignition hohlraums are typically filled with a gas or irradiated with a short (< 10 ns) laser pulse. A gas-fill has the disadvantage that it can cause laser plasma instabilities (LPI), while a short laser pulse limits the design space to reach low-adiabat implosions. Foam-liners offer a potential route to reduce wall motion in a low gas-fill hohlraum with little LPI. Results from quasi 1-D experiments performed at the NIF are presented These characterize the x-ray conversion efficiency, backscattered laser energy and heat propagation in a 250 μm thick Ta2O5 or ZnO foam-liners spanning a range of densities from underdense to overdense, when irradiated at up to 4.9 x 1014 W/cm2 is incident on a planar foam sample, backed by a Au foil and generates a radiation temperature of up to 240eV - conditions equivalent to a single outer cone beam-spot in an ignition hohlraum. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation.

    PubMed

    Morales-Torres, Sergio; Silva, Tânia L S; Pastrana-Martínez, Luisa M; Brandão, Ana T S C; Figueiredo, José L; Silva, Adrián M T

    2014-06-28

    A specific methodology based on nitric acid hydrothermal oxidation was used to control the surface chemistry of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes (CNTs) with different lengths, and this methodology was adapted to the use of sulphuric acid containing ammonium persulfate as an oxidizing agent. The amount of oxygen-containing surface groups depends on the number and length of the graphene layers of the CNTs, thicker and shorter CNTs having more reactive sites for surface functionalization. In particular, the oxidation of MWCNTs was more pronounced than that of short SWCNTs and less surface groups were introduced into long SWCNTs, regardless of the acid used at any fixed concentration. It was also possible to tailor the surface chemistry of both SWCNTs and MWCNTs by using the adopted methodologies, and the amount of both oxygen- and sulphur-containing functional groups was correlated with the concentration of each oxidizing agent used. Mathematical functions that allow precise control of the amount and type of the surface groups introduced into carbon nanotubes were obtained. Buckypapers were also prepared over a polytetrafluoroethylene commercial membrane. These membranes were tested in direct contact membrane distillation and, under salinity conditions, the membrane prepared using oxidized MWCNTs (instead of SWCNTs) was the most efficient, the permeate flux of the commercial membrane significantly increasing in the presence of these CNTs, while completely rejecting chloride ions. In addition, the permeate flux was precisely correlated with the amount of oxygenated functional surface groups (as well as with the pH of point of zero charge) of the oxidized MWCNTs.

  19. Direct observation of spinodal decomposition phenomena in InAlN alloys during in-situ STEM heating

    NASA Astrophysics Data System (ADS)

    Palisaitis, J.; Hsiao, C.-L.; Hultman, L.; Birch, J.; Persson, P. O. Å.

    2017-03-01

    The spinodal decomposition and thermal stability of thin In0.72Al0.28N layers and In0.72Al0.28N/AlN superlattices with AlN(0001) templates on Al2O3(0001) substrates was investigated by in-situ heating up to 900 °C. The thermally activated structural and chemical evolution was investigated in both plan-view and cross-sectional geometries by scanning transmission electron microscopy in combination with valence electron energy loss spectroscopy. The plan-view observations demonstrate evidence for spinodal decomposition of metastable In0.72Al0.28N after heating at 600 °C for 1 h. During heating compositional modulations in the range of 2-3 nm-size domains are formed, which coarsen with applied thermal budgets. Cross-sectional observations reveal that spinodal decomposition begin at interfaces and column boundaries, indicating that the spinodal decomposition has a surface-directed component.

  20. MRI temperature map reconstruction directly from k-space with compensation for heating-induced geometric distortions

    NASA Astrophysics Data System (ADS)

    Gaur, Pooja; Grissom, William A.

    2017-03-01

    Proton resonance frequency (PRF) change is used to measure tissue heating, but also distorts the image and causes geometric distortions in temperature estimates in the same manner as other chemical shift distortions if left uncompensated. We propose an algorithm that produces PRF temperature maps free of these distortions by fitting a signal model directly to acquired k-space data that accounts for PRF-induced phase both up to and during the readout. We also introduce a faster method compatible with Cartesian data that corrects distortions from image-domain temperature maps. Gel heating experiments show the proposed CS compensation algorithms correct magnitude image artifacts and hotspot distortions. Without CS compensation, thermal dose values are overestimated in spiral data, and are spatially offset in 2DFT and EPI data. Compensating for heat-induced CS distortions improves the accuracy of temperature change and thermal dose measurements, and can have a significant positive impact on clinical and research applications of PRF-shift thermometry.

  1. Direct observation of spinodal decomposition phenomena in InAlN alloys during in-situ STEM heating

    PubMed Central

    Palisaitis, J.; Hsiao, C.-L.; Hultman, L.; Birch, J.; Persson, P. O. Å.

    2017-01-01

    The spinodal decomposition and thermal stability of thin In0.72Al0.28N layers and In0.72Al0.28N/AlN superlattices with AlN(0001) templates on Al2O3(0001) substrates was investigated by in-situ heating up to 900 °C. The thermally activated structural and chemical evolution was investigated in both plan-view and cross-sectional geometries by scanning transmission electron microscopy in combination with valence electron energy loss spectroscopy. The plan-view observations demonstrate evidence for spinodal decomposition of metastable In0.72Al0.28N after heating at 600 °C for 1 h. During heating compositional modulations in the range of 2–3 nm-size domains are formed, which coarsen with applied thermal budgets. Cross-sectional observations reveal that spinodal decomposition begin at interfaces and column boundaries, indicating that the spinodal decomposition has a surface-directed component. PMID:28290508

  2. Organic thermoelectric materials: emerging green energy materials converting heat to electricity directly and efficiently.

    PubMed

    Zhang, Qian; Sun, Yimeng; Xu, Wei; Zhu, Daoben

    2014-10-29

    The abundance of solar thermal energy and the widespread demands for waste heat recovery make thermoelectric generators (TEGs) very attractive in harvesting low-cost energy resources. Meanwhile, thermoelectric refrigeration is promising for local cooling and niche applications. In this context there is currently a growing interest in developing organic thermoelectric materials which are flexible, cost-effective, eco-friendly and potentially energy-efficient. In particular, the past several years have witnessed remarkable progress in organic thermoelectric materials and devices. In this review, thermoelectric properties of conducting polymers and small molecules are summarized, with recent progresses in materials, measurements and devices highlighted. Prospects and suggestions for future research efforts are also presented. The organic thermoelectric materials are emerging candidates for green energy conversion.

  3. A direct-measurement thin-film heat flux sensor array

    NASA Astrophysics Data System (ADS)

    Ewing, Jerrod; Gifford, Andrew; Hubble, David; Vlachos, Pavlos; Wicks, Alfred; Diller, Thomas

    2010-10-01

    A new thin-film heat flux array (HFA) was designed and fabricated using a series of nickel/copper differential thermocouples deposited onto a thin Kapton® polyimide film. A special bank of amplifiers was designed and built to measure the signal from the HFA. Calibrations were performed to determine the gage's sensitivity and temporal response. The HFA produced signals of 42 µV (W cm-2)-1 with a measured first-order response time of 32 ms. The apparent thermal conductivity of the Kapton used was larger than what is usually reported. The design methodology, construction techniques, steady-state and transient calibrations, and a test case are all discussed.

  4. Direct electric field heating and acceleration of electrons in solar flares

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Benka, Stephen G.

    1992-01-01

    We show that the observed properties of solar flare X-ray and microwave emission can be explained through the Joule heating and electric field acceleration of runaway electrons in current channels. The global properties of the flaring region required for this are presented. We have fit a hybrid thermal/nonthermal electron distribution, consisting of hot, isothermal electrons with a nonthermal tail of runaway electrons, to high-resolution hard X-ray and microwave spectra and have obtained excellent fits to both. The hybrid model relaxes the electron number and energy flux requirements for the hard X-ray emission over those of a purely nonthermal model. The model also provides explanations for several previously unexplained aspects of the high-resolution microwave spectra. The fit parameters can be related to physical properties (such as the electric field strength in the current channels) of the acceleration region.

  5. Geochemistry of hydrothermal plume in the Suiyo Seamount Caldera.

    NASA Astrophysics Data System (ADS)

    Shitashima, K.; Maeda, Y.

    2002-12-01

    Chemical compounds of the hot basalt origin are discharged into the deep ocean via hydrothermal plume by the deep-sea hydrothermal activity. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the hydrothermal plume are important to comprehend the oceanic geochemical cycles. Recently, it has been clarified that the variation of hydrothermal activity is greatly controlled in the tidal current. Not only geochemical observation but also physical observation, such as water current measurement, are necessary for the understanding of the deep-sea hydrothermal systems including the behavior of hydrothermal plume. In order to observe the diffusion process of hydrothermal plumes, sampling and chemical mapping of the hydrothermal plume and measurement of water current were carried out at the Suiyo Seamount Caldera during research cruises under the ?Archaean Park? project funded by MEXT. The three-dimensional acoustic current meters were moored at the height of 13m and 125m above the bottom in the Suiyo Seamount Caldera. At the 13m height, average water current speed and current direction were 10.46 cm/second and 228.1 degrees, respectively, and maximum water current speed was over 40.46 cm/second. On the other hand, average water current speed and current direction at the 125m height were 3.87 cm/second and 57.8 degrees, respectively. The strong water current of the southwest direction in 24 hours periods existed near bottom of the caldera. In addition, downward current and water temperature depreciation were observed, when there was the strong current in 24 hours periods. These results suggest that the low-temperature ocean water around the Suiyo Seamount flows toward the bottom of caldera periodically. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles and the in-situ pH sensor were installed on the ROV or manned submersible. The hydrothermal plume

  6. Potential biomass in deep-sea hydrothermal vent ecosystem

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Takai, K.

    2012-12-01

    Since the first discovery of black smoker vents hosting chemosynthetic macrofaunal communities (Spiess et al., 1980), submarine hydrothermal systems and associated biota have attracted interest of many researchers (e.g., Humphris et al., 1995; Van Dover, 2000; Wilcock et al., 2004). In the past couple of decades, particular attention has been paid to chemolithoautotrophic microorganisms that sustain the hydrothermal vent-endemic animal communities as the primary producer. This type of microorganisms obtains energy from inorganic substances (e.g., sulfur, hydrogen, and methane) derived from hydrothermal vent fluids, and is often considered as an important modern analogue to the early ecosystems of the Earth as well as the extraterrestrial life in other planets and moons (e.g., Jannasch and Mottl, 1985; Nealson et al., 2005; Takai et al., 2006). Even today, however, the size of this type of chemosynthetic deep-sea hydrothermal vent ecosystem is largely unknown. Here, we present geophysical and geochemical constraints on potential biomass in the deep-sea hydrothermal vent ecosystem. The estimation of the potential biomass in the deep-sea hydrothermal vent ecosystem is based on hydrothermal fluid flux calculated from heat flux (Elderfield and Schltz, 1996), maximum chemical energy available from metabolic reactions during mixing between hydrothermal vent fluids and seawater (McCollom, 2007), and maintenance energy requirements of the chemolithoautotrophic microorganisms (Hoehler, 2004). The result shows that the most of metabolic energy sustaining the deep-sea hydrothermal vent ecosystem is produced by oxidation reaction of reduced sulfur, although some parts of the energy are derived from hydrogenotrophic and methanotrophic reactions. The overall total of the potential biomass in deep-sea hydrothermal vent ecosystem is calculated to be much smaller than that in terrestrial ecosystems including terrestrial plants. The big difference in biomass between the

  7. Monte Carlo direct view factor and generalized radiative heat transfer programs

    NASA Technical Reports Server (NTRS)

    Mc Williams, J. L.; Scates, J. H.

    1969-01-01

    Computer programs find the direct view factor from one surface segment to another using the Monte carlo technique, and the radioactive-transfer coefficients between surface segments. An advantage of the programs is the great generality of problems treatable and rapidity of solution from problem conception to receipt of results.

  8. Hydrothermal reactivity of saponite.

    USGS Publications Warehouse

    Whitney, G.

    1983-01-01

    The nature and extent of the reactions of synthetic Fe-free saponite have been investigated under experimental hydrothermal conditions as a first step towards understanding saponite reactivity under relatively simple conditions. Saponite crystallizes from amorphous gel of ideal saponite composition within 7 days at 300o-550oC under P = 1 kbar. Reactions subsequent to this initial crystallization depend on reaction T and interlayer cations. Saponite is found to react hydrothermally, over a period of 200 days, at T down to 400oC, at least 150oC lower than previously reported, but showed no signs of reaction below 400oC. At 450oC, a mixture of talc/saponite and saponite/phlogopite clays forms from K-saponite via intracrystalline layer transformations, while above 450oC the initial K-saponite dissolves, with talc and phlogopite forming as discrete phases. After 200 days reactions at 400-450oC were not complete, so that given sufficient time to reach equilibrium, a lower hydrothermal stability limit for saponite is possible. Further study of the Fe-bearing saponite system will be required before experimental results can be applied to natural systems.-D.F.B.

  9. The kinetics of inhibitor production resulting from hydrothermal deconstruction of wheat straw studied using a pressurised microwave reactor

    PubMed Central

    2014-01-01

    Background The use of a microwave synthesis reactor has allowed kinetic data for the hydrothermal reactions of straw biomass to be established from short times, avoiding corrections required for slow heating in conventional reactors, or two-step heating. Access to realistic kinetic data is important for predictions of optimal reaction conditions for the pretreatment of biomass for bioethanol processes, which is required to minimise production of inhibitory compounds and to maximise sugar and ethanol yields. Results The gravimetric loss through solubilisation of straw provided a global measure of the extent of hydrothermal deconstruction. The kinetic profiles of furan and lignin-derived inhibitors were determined in the hydrothermal hydrolysates by UV analysis, with concentrations of formic and acetic acid determined by HPLC. Kinetic analyses were either carried out by direct fitting to simple first order equations or by numerical integration of sequential reactions. Conclusions A classical Arrhenius activation energy of 148 kJmol−1 has been determined for primary solubilisation, which is higher than the activation energy associated with historical measures of reaction severity. The gravimetric loss is primarily due to depolymerisation of the hemicellulose component of straw, but a minor proportion of lignin is solubilised at the same rate and hence may be associated with the more hydrophilic lignin-hemicellulose interface. Acetic acid is liberated primarily from hydrolysis of pendant acetate groups on hemicellulose, although this occurs at a rate that is too slow to provide catalytic enhancement to the primary solubilisation reactions. However, the increase in protons may enhance secondary reactions leading to the production of furans and formic acid. The work has suggested that formic acid may be formed under these hydrothermal conditions via direct reaction of sugar end groups rather than furan breakdown. However, furan degradation is found to be significant

  10. Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution

    NASA Astrophysics Data System (ADS)

    Neveu, Marc; Desch, Steven J.; Castillo-Rogez, Julie C.

    2015-02-01

    Observations and models of Ceres suggest that its evolution was shaped by interactions between liquid water and silicate rock. Hydrothermal processes in a heated core require both fractured rock and liquid. Using a new core cracking model coupled to a thermal evolution code, we find volumes of fractured rock always large enough for significant interaction to occur. Therefore, liquid persistence is key. It is favored by antifreezes such as ammonia, by silicate dehydration which releases liquid, and by hydrothermal circulation itself, which enhances heat transport into the hydrosphere. The effect of heating from silicate hydration seems minor. Hydrothermal circulation can profoundly affect Ceres' evolution: it prevents core dehydration via "temperature resets," core cooling events lasting ˜50 Myr during which Ceres' interior temperature profile becomes very shallow and its hydrosphere is largely liquid. Whether Ceres has experienced such extensive hydrothermalism may be determined through examination of its present-day structure. A large, fully hydrated core (radius 420 km) would suggest that extensive hydrothermal circulation prevented core dehydration. A small, dry core (radius 350 km) suggests early dehydration from short-lived radionuclides, with shallow hydrothermalism at best. Intermediate structures with a partially dehydrated core seem ambiguous, compatible both with late partial dehydration without hydrothermal circulation, and with early dehydration with extensive hydrothermal circulation. Thus, gravity measurements by the Dawn orbiter, whose arrival at Ceres is imminent, could help discriminate between scenarios for Ceres' evolution.

  11. Dike controlled low-temperature hydrothermal activity in far off-axis regions of NW Iceland

    NASA Astrophysics Data System (ADS)

    Palgan, Dominik; Devey, Colin

    2015-04-01

    Iceland provides a unique opportunity to make direct observations of the volcano-tectonic settings of active hydrothermal systems both on- and off-axis at slow-spreading ridges. High-temperature systems are associated with active volcanism and rifting of neo-volcanic zones, in a way similar to that known from the seafloor. However, a great majority of geothermal activity in Iceland is represented by low-temperature systems confined to off-axis Quaternary and Tertiary formations (>3.3 M.y). Despite extensive study of these systems, one general model explaining their geological framework has not yet to be presented. However, theoretical calculations indicate that existence and heat output of low-temperature systems is controlled by the temperature and stress conditions in the crust, in particular the local stress field, which controls whether fractures and crack are available for the heat-mining process and how fast these fractures can migrate downward. In seismically active regions of Iceland, geothermal activity focuses along active faults and resulting ruptures where seismicity is the shallowest (<5 km), indicating that repetitive earthquakes likely continuously control geothermal activity and that fluid circulation may be relatively shallow. Results obtained during fieldwork from autumn 2013 in far off-axis regions of Iceland (Westfjords Peninsula) show a significant correlation between low-temperature hot-springs locations and the presence of basaltic dikes cross-cutting the sub-horizontal lava sequence, with 88% of all hydrothermal manifestations occurring in the direct vicinity of a dike or occupying related secondary fractures. There is very little seismic activity in the Westfjords and this, together with the field research suggests that faults there are no longer active and so cannot support fluids migration; instead, only dikes provide open, permeable and deep circulation pathways. Relatively high-temperature secondary mineralization (e.g. chlorite and

  12. Using low-temperature thermochronology and numerical models to quantify the history of hydrothermal activity in Beowawe, Nevada

    NASA Astrophysics Data System (ADS)

    Louis, Sarah; Luijendijk, Elco; Dunkl, István; Person, Mark

    2017-04-01

    The history of hydrothermal systems and hot springs is difficult to quantify because hydrothermal mineral deposits are often difficult to date at sufficient resolution. Quantifying hydrothermal activity is important for gaining insights on how geological processes such as earth quakes and faulting mechanisms interact with fluid flow. Here we combine high-density apatite (U-Th)/He data with numerical models of heat flow to determine the history of an active hydrothermal system. We determined Apatite-Helium (AHe) ages of surface rock samples collected around a hydrothermally active normal fault in Beowawe (Nevada,USA). AHe ages in the vicinity of the hot springs along the fault showed significant thermal overprint. Samples located at a distance of 50m were unaffected by hydrothermal activity and showed AHe ages that were equal to the U-Pb age of the volcanic host rock of 15.2 M.y. The observed thermal overprint is caused by high temperatures ( 95 C) of the hydrothermal fluids along the Malpais fault that have heated the adjacent rocks over long timescales. The size of the thermally affected area depends on the duration of hydrothermal activity; the longer the system is active the larger the thermal aureole around the fault. We used a numerical model of advective and conductive heat flow to calibrate the duration of hydrothermal activity using the AHe data. Combining low-temperature thermochronology with a thermal model can therefore be used as a tool to quantify hydrothermal activity over geological time scales.

  13. Thermohydrodynamic model: Hydrothermal system, shallowly seated magma chamber

    NASA Astrophysics Data System (ADS)

    Kiryukhin, A. V.

    1985-02-01

    The results of numerical modeling of heat exchange in the Hawaiian geothermal reservoir demonstrate the possibility of appearance of a hydrothermal system over a magma chamber. This matter was investigated in hydrothermal system. The equations for the conservation of mass and energy are discussed. Two possible variants of interaction between the magma chamber and the hydrothermal system were computated stationary dry magma chamber and dry magma chamber changing volume in dependence on the discharge of magma and taking into account heat exchange with the surrounding rocks. It is shown that the thermal supplying of the hydrothermal system can be ensured by the extraction of heat from a magma chamber which lies at a depth of 3 km and is melted out due to receipt of 40 cubic km of basalt melt with a temperature of 1,300 C. The initial data correspond with computations made with the model to the temperature values in the geothermal reservoir and a natural heat transfer comparable with the actually observed values.

  14. The potential for prebiotic synthesis in hydrothermal systems. [Abstract only

    NASA Technical Reports Server (NTRS)

    Ferris, James P.

    1994-01-01

    Contemporary hydrothermal systems provide a reducing environment where organic compounds are formed and may react to generate the molecules used in the first living systems. The organic compounds percolate through mineral assemblages at a variety of temperatures so the proposed synthetic reactions are driven by heat and catalyzed by minerals (Ferris, 1992). Some examples of potential prebiotic reactions are discussed.

  15. Direct numerical simulation of fluid-particle mass, momentum, and heat tranfers in reactive systems.

    NASA Astrophysics Data System (ADS)

    Hammouti, Abdelkader; Wachs, Anthony

    2015-11-01

    Many industrial processes like coal combustion, catalytic cracking, gas phase polymerization reactors and more recently biomass gasification and chemical looping involve two-phase reactive flows in which the continuous phase is a fluid and the dispersed phase consists of rigid particles. Improving both the design and the operating conditions of these processes represents a major scientific and industrial challenge in a context of markedly rising energy cost and sustainable development. Thus, it is above all important to better understand the coupling of hydrodynamic, chemical and thermal phenomena in those flows in order to be able to predict them reliably. The aim of our work is to build up a multi-scale modelling approach of reactive particulate flows and at first to focus on the development of a microscopic-scale including heat and mass transfers and chemical reactions for the prediction of particle-laden flows in dense and dilute regimes. A first step is the upgrading and the validation of our numerical tools via analytical solutions or empirical correlations when it is feasible. These couplings are implemented in a massively parallel numerical code that already enable to take a step towards the enhanced design of semi-industrial processes.

  16. Seafloor hydrothermal clay alteration at Jade in the back-arc Okinawa trough: Mineralogy, geochemistry and isotope characteristics

    NASA Astrophysics Data System (ADS)

    Marumo, Katsumi; Hattori, Kéiko H.

    1999-09-01

    Seafloor hydrothermal activity at Jade has resulted in extensive alteration of the host epiclastic sediments and pumiceous tuffs, forming mica, kaolins (kaolinite and halloysite), Mg-rich chlorite, talc, montmorillonite, and a mixed-layer mineral of dioctahedral chlorite and montmorillonite (Chl/Mont). Clay mineral assemblages show a vertical variation, which reflects variable amounts of cold seawater incorporated into hot hydrothermal fluids in subsurface sediments and tuff. However, mixing alone cannot explain the occurrence of abundant kaolin minerals at Jade. The formation of kaolin minerals requires much more acidic fluid than expected from simple mixing of hydrothermal fluids and cold seawater. Low pH values are likely attained by oxidation of H 2S either dissolved in the hydrothermal fluid or released from the fluid during decompression. The fluid reaching the seafloor is discharged into cold seawater, which caused precipitation of sulfides close to vents and native sulfur and barite at the margins of the vent areas. Halloysite, barite and anhydrite show Sr isotope compositions similar to marine Sr, indicating the derivation of marine Sr directly from seawater or by the dissolution of calcareous nannoplanktons. The isotopic compositions of kaolinite (δ 18O = +7.4‰, δD = -23‰), Chl/Mont (δ 18O = +7.0‰, δD = -32‰), and mica (δ 18O = +5.4 to +9.9‰, δD = -30 to -26‰) suggest fluids of a heated seawater origin. The O isotopic data yielded formation temperatures of 170°C for kaolinite, 61 to 110°C for halloysite, and 145 to 238°C for mica. Barite δ 34S values (+21.0 to +22.5‰) are very similar to the marine sulfate value, confirming that the barite formation took place due to mixing of Ba-bearing hydrothermal fluids and sulfate-rich seawater. Native sulfur shows a large variation in δ 34S in one hand specimen probably because of rapid disequilibrium precipitation of S during fluid exhalation on the seafloor. Sulfur in hydrothermal fluids

  17. Organic matter in hydrothermal metal ores and hydrothermal fluids

    USGS Publications Warehouse

    Orem, W.H.; Spiker, E. C.; Kotra, R.K.

    1990-01-01

    Massive polymetallic sulfides are currently being deposited around active submarine hydrothermal vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine hydrothermal activity. Thus, there is a significant potential for organic matter/metal interactions in these systems. We have studied modern and ancient hydrothermal metal ores and modern hydrothermal fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient hydrothermal systems were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered hydrothermal systems had higher organic C values than those from modern and ancient hydrothermal systems lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in hydrothermal metal ores from sediment covered vents probably arises from complex sedimentary organic matter by hydrothermal pyrolysis. The dissolved organic C concentrations of hydrothermal fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from hydrothermal fluids by biological activity or by co-precipitation with metal ores. ?? 1990.

  18. Diffuse flow from hydrothermal vents. Doctoral thesis

    SciTech Connect

    Trivett, D.A.

    1991-08-01

    The effluent from a collection of diffuse hydrothermal vents was modelled to determine the fate of the source of flow under typical environmental conditions at seafloor spreading centers. A laboratory simulation was conducted to test an analytic model of diffuse plume rise. The results showed that diffuse plumes are likely to remain near the seafloor, with their maximum rise height scaled with the diameter of the source of diffuse flow. The entrainment of ambient seawater into these plumes is limited by the proximity to the seafloor, thus slowing the rate of dilution. The model of diffuse plume behaviour was used to guide the design and implementation of a scheme for monitoring the flow from diffuse hydrothermal vents in the ocean. A deployment of an array at the Southern Juan de Fuca Ridge yielded measurements of a variety of diffuse plume properties, including total heat output. Two distinct sources of hydrothermal flow were detected during the field deployment. The larger source was 1-1.5km north of the instrument array, and its energy output was 450 + or - 270MW. A smaller source was located 100m east of one instrument in the array. The energy output of the source was 12 + or - 8MW. The rise heights of the centerlines of these plumes were 45m and 10m, respectively.

  19. Numerical simulation of magmatic hydrothermal systems

    USGS Publications Warehouse

    Ingebritsen, S.E.; Geiger, S.; Hurwitz, S.; Driesner, T.

    2010-01-01

    The dynamic behavior of magmatic hydrothermal systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The past 2 decades have seen steady growth of computational power and the development of numerical models that have eliminated or minimized the need for various simplifying assumptions. Considerable heuristic insight has been gained from process-oriented numerical modeling. Recent modeling efforts employing relatively complete EOS and accurate transport calculations have revealed dynamic behavior that was damped by linearized, less accurate models, including fluid property control of hydrothermal plume temperatures and three-dimensional geometries. Other recent modeling results have further elucidated the controlling role of permeability structure and revealed the potential for significant hydrothermally driven deformation. Key areas for future reSearch include incorporation of accurate EOS for the complete H2O-NaCl-CO2 system, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons. Copyright 2010 by the American Geophysical Union.

  20. Aerosol Climatology at Pune, Western India: Implications to Direct Radiative Forcing and Heating Rates

    NASA Astrophysics Data System (ADS)

    Pandithurai, G.; Pinker, R. T.; Devara, P. C.; Raj, P. E.; Jayarao, Y.; Dani, K. K.; Maheskumar, R. S.; Sonbawne, S. M.; Saha, S. K.; Bhawar, R.; Shinde, U. P.

    2005-12-01

    Extensive aerosol observations were carried out at Indian Institute of Tropical Meteorology (IITM), Pune, an urban site in the western part of the country, using a Prede (Model POM-01L) sun/sky radiometer and a bi-static Argon ion lidar since December 2000 and October 1986, respectively. The sun/sky radiometer was operated daily at every 15 minute interval during day-time to derive column aerosol optical parameters such as aerosol optical depth (AOD), single scattering albedo (SSA), asymmetry parameter (ASY) while the lidar was operated weekly in the early-night period to derive vertical distributions of aerosol number density. The sun/sky radiance data collected during the above period have been analysed by using the radiative transfer model SkyRadPack version 3.0 (Nakajima et al. 1996) to retrieve AOD, SSA and ASY. AOD and SSA retrieved at 15-minutes interval were averaged to get monthly means. On every year from 2000 to 2005, monthly means of AOD show gradual increase of aerosol loading from December to April and Angstrom exponent decreases from March due to local as well as transported dust from African / Arabian regions through Arabian Sea. Monthly means of SSA show decrease from December to April and the wavelength dependence also indicate the abundance of dust from March to May. Lidar-derived vertical distributions yield minimum during the monsoon months, gradually builds up during the post-monsoon and winter months, and finally peaks during the pre-monsoon months in every year (Devara et al., 2002). The aerosol climatology of optical/radiative parameters and their vertical distribution are used for estimating aerosol radiative forcing (ARF) and atmospheric heating rates by using a discrete-ordinate radiative transfer model (Ricchiazzi et al., 1998, Pandithurai et al. 2004). Details of the experimental methods, data, results of aerosol climatology and implications to radiative forcing and associated heating rates will be presented. References Devara, P

  1. Hydrothermal synthesis of bismuth germanium oxide

    DOEpatents

    Boyle, Timothy J.

    2016-12-13

    A method for the hydrothermal synthesis of bismuth germanium oxide comprises dissolving a bismuth precursor (e.g., bismuth nitrate pentahydrate) and a germanium precursor (e.g., germanium dioxide) in water and heating the aqueous solution to an elevated reaction temperature for a length of time sufficient to produce the eulytite phase of bismuth germanium oxide (E-BGO) with high yield. The E-BGO produced can be used as a scintillator material. For example, the air stability and radioluminescence response suggest that the E-BGO can be employed for medical applications.

  2. Methane and radioactive isotopes in submarine hydrothermal systems

    SciTech Connect

    Kim, K.R.

    1983-01-01

    This thesis consists of two parts: 1) methane and 2) radioactive isotopes, especially radon, in submarine hydrothermal systems. Both parts deal with the use of these gases as tracers for mapping hydrothermal vents at sea, and with their relationships to other sensitive tracers such as helium, manganese, and temperature. Hydrothermal methane was used as a real-time tracer for locating new submarine hydrothermal systems along spreading axes, discovering new hydrothermal systems at two locations in Pacific Ocean: 1) 20/sup 0/S on East Pacific Rise, and 2) Mariana Trough Back-arc Basin. Methane shows good correlations with helium-3 and temperature with similar ratios in various hydrothermal systems, 3 to 42 x 10/sup 6/ for the methane to helium-3 ratio, and 3 to 19 ..mu.. cc/kg/sup 0/C for the methane to temperature anomaly. These similar ratios from different areas provide evidence for chemical homogeneity of submarine hydrothermal waters. A good correlation between methane and manganese appears to be associated only with high-temperature hydrothermal systems. Radioisotopes in the vent waters of 21/sup 0/N high-temperature hydrothermal system have end-member concentrations of 7.5 to 40 dpm/kg for Ra-226, 360 dpm/kg for Rn 222, 62 dpm/kg for Pb-210, and 19 dpm/kg for Po-210. The radon activity for this system is one order of magnitude lower, and the Pb-210 activity is one order or magnitude higher, than those a the low temperature Galapagos system. All these observations suggest that the high radon, and low Pb-210 activity observed in Galapagos system may originate from the extensive subsurface mixing and water-rock interaction in this system (direct injection of radon and scavenging of Pb-210).

  3. Hydrothermal Liquefaction of Biomass

    SciTech Connect

    Elliott, Douglas C.

    2010-12-10

    Hydrothermal liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. HydroThermal Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the HydroThermal Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, 'HydroThermal Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. HydroThermal Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international collaboration with

  4. The influence of ultra-pasteurization by indirect heating versus direct steam injection on skim and 2% fat milks.

    PubMed

    Lee, A P; Barbano, D M; Drake, M A

    2017-03-01

    Fluid milk is traditionally pasteurized by high temperature, short time (HTST) pasteurization, which requires heating to at least 72°C for 15 s. Ultra-pasteurization (UP) extends milk shelf life and is defined as heating to at least 138°C for 2 s. The UP process can be done by indirect heating (IND) or by direct steam injection (DSI). The influence of these 2 UP methods on milk flavor has not been widely investigated. The objective of this study was to compare the effect of HTST, IND-UP, and DSI-UP on sensory perception of fluid milk. Raw skim and standardized 2% milks were pasteurized at 140°C for 2.3 s by IND or DSI or by HTST (78°C, 15 s) and homogenized at 20.7 MPa. The processed milks were stored in light-shielded opaque high-density polyethylene containers at 4°C and examined by descriptive analysis and microbial analysis on d 3, 7, and 14. Furosine and serum protein denaturation analyses were performed on d 0 and 14 as an indicator of heat treatment. Last, consumer acceptance testing was conducted at d 10, with adults (n = 250) and children (ages 8 to13 y, n = 100) who were self-reported consumers of skim or 2% milk; consumers only received samples for either skim or 2% milk. The entire experiment was repeated in triplicate. Milks treated by HTST had lower cooked flavor than either UP milk. Milks heated by DSI-UP were characterized by sulfur or eggy and cooked flavors, whereas IND-UP milks had higher sweet aromatic and sweet taste compared with DSI-UP milk. Aromatic flavor intensities of all milks decreased across 14 d of storage. Furosine concentrations and serum protein denaturation were highest for the IND treatments, followed by DSI and HTST. Furosine content in both skim and 2% milk increased with time, but the increase was faster in IND-UP skim milk. Adult and child consumers preferred HTST milk over either UP milk, regardless of fat content. Ultra-pasteurization by IND or DSI did not affect consumer acceptance at 10 d postprocessing, but

  5. Sulfur Lakes and Sulfur-rich Volcanic Hydrothermal Systems on the Mariana Arc

    NASA Astrophysics Data System (ADS)

    Butterfield, D. A.; Resing, J. A.; Chadwick, W. W.; Embley, R. W.; Lupton, J. E.; Nakamura, K.; Lilley, M. D.; Huber, J. A.

    2007-12-01

    During the Submarine Ring of Fire expeditions in 2004 and 2006, and the Natsushima NT-05-18 expedition in 2005 we investigated and sampled hydrothermal systems on ten submarine volcanoes in the Mariana arc between 13.5 and 23.1 degrees N. The high volatile content of the volcanic arc environment is evident in the CO2 and SO2 dominated fluids sampled and differentiates volcanic arc hydrothermal chemistry from more rock- buffered mid-ocean ridge systems. Sulfur-dominated sites appear to be common on submarine arc volcanoes at water depths shallower than 700 meters. At NW Rota-1 volcano, there is clear evidence of ongoing eruptive activity producing clouds of particulate and molten sulfur as well as mm to m-size glassy volcanic ejecta. The hydrothermal system at NW Rota-1 represents a direct connection to a sub-seafloor magma body, and is one of the only known sites in the world where we can directly sample the solid, liquid and gaseous products of a submarine magmatic hydrothermal system. Fluids (30 to 260 deg C) sampled directly from an eruptive vent have pH as low as 1.0, with a high content of particulate sulfur, excess sulfurous and sulfuric acid, and very low H2S content. Fluids percolating through volcaniclastic sand adjacent to the vent reached 100 deg C and had higher silica, slightly higher pH, and millimolar levels of H2S. The chemistry of both types of fluids is indicative of input of volcanic SO2 and incomplete disproportionation into sulfuric acid and either H2S (in volcaniclastic sands) or elemental sulfur (in the eruptive vent). Highly acidic aqueous fluids attack the basaltic substrate, and carry high levels of iron and aluminum. Daikoku (21.3°N) and Nikko (23.1°N) submarine volcanoes both host active molten sulfur ponds and a wide variety of sulfur flows and deposits. The remarkable molten sulfur pools (~180-200°C) occur without widespread focused venting of hot water and may be maintained by active magmatic degassing of hot CO2/SO2-rich gases

  6. Heat pumps

    NASA Astrophysics Data System (ADS)

    Gilli, P. V.

    1982-11-01

    Heat pumps for residential/commercial space heating and hot tap water make use of free energy o