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. Acidization of a Direct Heat Hydrothermal Well and its Potential in Developing Additional Direct Heat Projects

    SciTech Connect

    Dolenc, M.R.; Strawn, J. A.; Prestwich, S.M.

    1981-01-01

    A matrix acid treatment on a limestone formation in a low temperature hydrothermal production well in South Dakota has resulted in a 40% increase in heat (BTU) available for use in space heating a hospital. The results of this experimental treatment on the Madison Limestone suggest a significant potential may exist for similar applications, particularly throughout the western United States. This paper presents the results of the acid treatment, suggests other possible areas for similar application, and analyzes the economics for successful treatments.

  4. 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)

  5. 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

  6. A direct steam heat option for hydrothermal treatment of municipal solid waste

    SciTech Connect

    Thorsness, C.B.

    1995-04-12

    A conceptual process for producing a gasifiable slurry from raw municipal solid waste (MSW) using direct steam heating is outlined. The process is based on the hydrothermal decomposition of the organic matter in the MSW, which requires the MSW to be heated to 300-350{degrees}C in the presence of water. A process model is developed and it is shown, based on preliminary estimates of the hydrothermal reaction stoichiometry, that a process using multiple pressure vessels, which allows recovery of waste heat, results in a process capable of producing a product slurry having a 40 wt % solids content with no waste water emissions. Results for a variety of process options and process parameters are presented. It is shown that the addition of auxiliary feedstock to the gasifier, along with the MSW derived slurry, results in more efficient gasification. It is estimated that 2.6 kmol/s of hydrogen can be produced from 30 kg/s (2600 tonne/day) of MSW and 16 kg/s of heavy oil. Without the additional feedstock, heavy oil in this case, only 0.49 kmol/s of hydrogen would be produced.

  7. Direct synthesis of thermochromic VO2 through hydrothermal reaction

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Thermochromic VO2 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 VO2 powders. Ex-situ XRD studies after heat treatment confirmed the thermal stability of the VO2 structure. Thermochromic properties, as a consequence of the reversible structural transformation between monoclinic VO2 and tetragonal phases, were observed by Fourier transform infrared spectroscopy (FTIR).

  8. 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.

  9. 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.

  10. 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)

  11. Direct heating surface combustor

    NASA Technical Reports Server (NTRS)

    Beremand, D. G.; Shire, L. I.; Mroz, T. S. (Inventor)

    1978-01-01

    The combustor utilizes a non-adiabatic flame to provide low-emission combustion for gas turbines. A fuel-air mixture is directed through a porous wall, the other side of which serves as a combustion surface. A radiant heat sink disposed adjacent to and spaced from the combustion surface controls the combustor flame temperature in order to prevent the formation of oxides of nitrogen. A secondary air flow cools the heat sink. Additionally, up to 100% of secondary air flow is mixed with the combustion products at the direct heating surface combustor to dilute such products thereby reducing exit temperature. However, if less than 100% secondary air is mixed to the combustor, the remainder may be added to the combustion products further downstream.

  12. Heat extraction modeling of the Stanford hydrothermal reservoir model

    SciTech Connect

    Hunsbedt, A.; Lam, S.T.; Kruger, P.; Pruess, K.

    1982-01-01

    Three heat extraction experiments using a known-geometry rock loading and a calibration cooldown experiment for this rock loading yielded a set of useful hydrothermal reservoir production data covering a range of cooldown rates. The one-dimensional sweep model being developed for early use in hydrothermal reservoirs shows good agreement with the experimental data. A numerical model of the experimental system is under development and early predictions indicate reasonable agreement between numerical model output and experimental results. Future efforts will concentrate on improving details of the model particularly those related to experimental system heat loss characteristics. Once completed, a more detailed evaluation of the rock heat transfer process and appropriate simplified modeling approaches for use in the one-dimensional sweep model can be made.

  13. 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

  14. 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

  15. 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).

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  19. 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.

  20. Effect of hydrothermal heat treatment on magnetic properties of copper zinc ferrite rf sputtered films

    NASA Astrophysics Data System (ADS)

    Kaur, Jasmeet; Gadipelly, Thirupathi; Singh, R.

    2016-05-01

    The hydrothermal treatment to the nano-structured films can overcome the destruction of the films. The Cu-Zn Ferrite films were fabricated by RF-sputtering on quartz substrates. Subsequently, the as deposited films were heat treated using hydrothermal process. The X-ray diffraction pattern of the as-deposited and hydrothermal treated films indicate nano-crystalline cubic spinel structure. The amorphous nature of the films is removed after hydrothermal treatment with decreased crystallite size. The field emission scanning electron micrographs showed merged columnar growth for as deposited films, which changes to well define columns after hydrothermal heating. The homogeneous cluster distribution is observed in surface view of the hydrothermal treated films. Hydrothermal treated films show merging of in-plane and out of plane magnetization plots (M(H)) whereas the M(H) plots of as deposited films show angular dependence. The strong angular dependence is observed in the FMR spectra due to the presence of a uniaxial anisotropy in the films. The ferromagnetic interactions decrease in hydrothermal heated films due to the reduced shape anisotropy and crystallite size.

  1. 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.

  2. 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

  3. 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.

  4. Droplet heat transfer and chemical reactions during direct containment heating

    SciTech Connect

    Baker, L. Jr.

    1986-01-01

    A simplified model of heat transfer and chemical reaction has been adapted to evaluate the expected behavior of droplets containing unreacted Zircaloy and stainless steel moving through the containment atmosphere during postulated accidents involving direct containment heating. The model includes internal and external diffusive resistances to reaction. The results indicate that reactions will be incomplete for many conditions characteristic of direct containment heating sequences.

  5. Geothermal direct-heat utilization assistance

    NASA Astrophysics Data System (ADS)

    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.

  6. 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).

  7. The Coupling of the Numerical Heat Transfer Model of the Pauzhetka Hydrothermal System (Kamchatka, USSR) with Hydroisotopic Data

    SciTech Connect

    Kiryukhin, A.V.; Sugrobov, V.M.

    1986-01-21

    The application of the two-dimensional numerical heat-transfer model to the Pauzhetka hydrothermal system allowed us to establish that: (1) a shallow magma body with the anomalous temperature of 700-1000 C and with a volume of 20-30 km{sup 3} may be a heat source for the formation of the Pauzhetka hydrothermal system. (2) The water feeding source of the Pauzhetka hydrothermal system may be meteoric waters which are infiltrated at an average rate of 5-10 kg/s {center_dot} km{sup 2}. The coupling of the numerical heat-transfer model with hydroisotopic data (D,T,{sup 18}O) obtained from the results of testing of exploitation wells, rivers and springs is the basis to understand more clearly the position of recharge areas and the structure of water flows in the hydrothermal system.

  8. Direct computation of the sensible heat flux.

    USGS Publications Warehouse

    Watson, K.

    1980-01-01

    An algorithm to determine the sensible heat flux from simple field measurements (wind speed, air and ground temperatures) has been developed. It provides a direct solution, in parametric form, which can be displayed graphically or tabularly. -from Author

  9. Hydrothermally synthesized titanate nanostructures: impact of heat treatment on particle characteristics and photocatalytic properties.

    PubMed

    Kiatkittipong, Kunlanan; Scott, Jason; Amal, Rose

    2011-10-01

    The role titanate particle structure plays in governing its characteristics upon calcining and their ensuing influence on photocatalytic performance was investigated. Titanate nanotubes and nanoribbons were prepared by hydrothermal treatment of Aeroxide P25 and then calcined at temperatures in the range 200 - 800 °C. Heat treatment directly transformed the nanotubes to anatase while nanoribbon transformation to anatase occurred via a TiO(2)(B) intermediate phase. The nanoribbon structure also provided an increased resistance to sintering, allowing for retention of the original {010} facet of the titanate nanosheets up to 800 °C. The changing material properties with calcining were found to influence the capacity of the particles to photodegrade oxalic acid and methanol. The nanotubes provided an optimum photoactivity following calcination at 500 °C with this point representing a transition between the relative dominance of crystal phase and surface area on performance. The comparatively smaller initial surface area of the nanoribbons consigned this characteristic to a secondary role in influencing photoactivity with the changes to crystal phase dominating the continually improving performance with calcination up to 800 °C. The structural stability imparted by the nanoribbon architecture during calcination, in particular its retention of the {010} facet at temperatures >700 °C, advanced its photocatalytic performance compared with the nanotubes. This was especially the case for methanol photooxidation whose primary degradation mechanism relies on hydroxyl radical attack and was facilitated by the {010} facet. The effect was not as pronounced for oxalic acid due to its higher adsorption on TiO(2) and therefore greater susceptibility to oxidation by photogenerated holes. This study demonstrates that, apart from modulating sintering effects and changes to crystal phase, the titanate nanostructure influences particle crystallography which can be beneficial for

  10. 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.

  11. 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. PMID:22705524

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Heat source for an amagmatic hydrothermal system, Noto Peninsula, Central Japan

    NASA Astrophysics Data System (ADS)

    Umeda, Koji; Ninomiya, Atusi; Negi, Tateyuki

    2009-01-01

    Although there is no evidence of volcanism in the Noto Peninsula since the late Miocene, the peninsula has long been known to be unusual and atypical of non-volcanic regions, as indicated by high-temperature hot springs and a geothermal gradient greater than 50 K/km. In order to provide geochemical constraints on the heat source for amagmatic hydrothermal activity, the chemical and isotopic compositions of 14 gas and water samples from hot springs were measured. The observed 3He/4He ratios of most hot spring gases range from 0.03 to 1.2 RA (RA denotes the atmospheric 3He/4He ratio of 1.4 × 10-6). In these samples, mantle helium composes less than 10% of the total helium, indicating an insignificant contribution of mantle-derived volatiles from, for example, newly ascending magma and/or aqueous fluid generated by dehydration of the subducting slab. The Noto Peninsula mainly consists of Neogene volcaniclastic and sedimentary rocks overlying Paleozoic to Mesozoic basement rocks associated with uranium-bearing granite pegmatite containing elevated concentrations of heat generating elements such as uranium, thorium, and potassium. A plausible heat source for the amagmatic hydrothermal activity can be attributed to this distinctive geological environment where high heat producing granitic rocks are buried under Neogene sedimentary rocks with low thermal conductivities that act as thermal blankets. Most Noto Peninsula hot springs are found in areas of active faulting, where stress concentrations since the late Miocene could open an existing fault pathway because the fluid pressure is close to the lithostatic pressure. Meteoric waters circulating through hot basement rock come to the surface along these permeable conduits with minimal mixing with shallow groundwater, resulting in emanation of high-temperature hot springs with low 3He/4He ratio gases along active fault zones.

  17. 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.

  18. 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

  19. The scale of hydrothermal circulation of the Iheya-North field inferred from intensive heat flow measurements and ocean drilling

    NASA Astrophysics Data System (ADS)

    Masaki, Y.; Kinoshita, M.; Yamamoto, H.; Nakajima, R.; Kumagai, H.; Takai, K.

    2014-12-01

    Iheya-North hydrothermal field situated in the middle Okinawa trough backarc basin is one of the largest ongoing Kuroko deposits in the world. Active chimneys as well as diffuse ventings (maximum fluid temperature 311 °C) have been located and studied in detail through various geological and geophysical surveys. To clarify the spatial scale of the hydrothermal circulation system, intensive heat flow measurements were carried out and ~100 heat flow data in and around the field from 2002 to 2014. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 was carried out, and subbottom temperature data were obtained around the hydrothermal sites. During the JAMSTEC R/V Kaiyo cruise, KY14-01 in 2014, Iheya-North "Natsu" and "Aki" hydrothermal fields were newly found. The Iheya-Noth "Natsu" and "Aki" sites are located 1.2 km and 2.6 km south from the Iheya-North original site, respectively, and the maximum venting fluid temperature was 317 °C. We obtained one heat flow data at the "Aki" site. The value was 17 W/m2. Currently, the relationship between these hydrothermal sites are not well known. Three distinct zones are identified by heat flow values within 3 km from the active hydrothermal field. They are high-heat flow zone (>1 W/m2; HHZ), moderate-heat-flow zone (1-0.1 W/m2; MHZ); and low-heat-flow zone (<0.1 W/m2; LHZ). With increasing distance east of the HHZ, heat flow gradually decreases towards MHZ and LHZ. In the LHZ, temperature at 37m below the seafloor (mbsf) was 6 °C, that is consistent with the surface low heat flow suggesting the recharge of seawater. However, between 70 and 90 mbsf, the coarser sediments were cored, and temperature increased from 25 °C to 40°C. The temperature was 905°C at 151 mbsf, which was measured with thermoseal strips. The low thermal gradient in the upper 40 m suggests downward fluid flow. We infer that a hydrothermal circulation in the scale of ~1.5 km horizontal vs. ~a few hundred meters vertical.

  20. Conductive heat flow at the TAG Active Hydrothermal Mound: Results from 1993-1995 submersible surveys

    NASA Astrophysics Data System (ADS)

    Becker, K.; Von Herzen, R.; Kirklin, J.; Evans, R.; Kadko, D.; Kinoshita, M.; Matsubayashi, O.; Mills, R.; Schultz, A.; Rona, P.

    We report 70 measurements of conductive heat flow at the 50-m-high, 200-m-diameter TAG active hydrothermal mound, made during submersible surveys with Alvin in 1993 and 1995 and Shinkai 6500 in 1994. The stations were all measured with 5-thermistor, 0.6- or 1-m-long Alvin heat flow probes, which are capable of determining both gradient and thermal conductivity, and were transponder-navigated to an estimated accuracy of ±5-10 m relative to the 10-m-diameter central complex of black smokers. Within 20 m of this complex, conductive heat flow values are extremely variable (0.1- > 100 W/m²), which can only be due to local spatial and possible temporal variability in the immediate vicinity of the vigorous discharge sites. A similar local variability is suggested in the “Kremlin” area of white smokers to the southeast of the black smoker complex. On the south and southeast side of the mound, there is very high heat flow (3.7- > 25 W/m²) on the sedimented terraces that slope down from the Kremlin area. Heat flow is also high (0.3-3 W/m²) in the pelagic carbonate sediments on the surrounding seafloor within a few tens of meters of the southwest, northwest, and northeast sides of the mound. On the west side of the sulfide rubble plateau that surrounds the central black smoker peak, there is a coherent belt of very low heat flow (<20 mW/m²) 20-50 m west of the smokers, suggestive of local, shallow recharge of bottom water. The three submersible surveys spanned nearly two years, but showed no indication of any temporal variability in conductive heat flow over this time scale, whether natural or induced by ODP drilling in 1994.

  1. The analysis of repository-heat-driven hydrothermal flow at Yucca Mountain

    SciTech Connect

    Buscheck, T.A.; Nitao, J.J.

    1993-01-01

    To safely and permanently store high-level nuclear waste, the potential Yucca Mountain repository site must mitigate the release and transport of radionuclides for tens of thousands of years. In the failure scenario of greatest concern, water would contact the waste package (WP), accelerate its failure rate, and eventually transport radionuclides to the water table. In a concept called the ``extended-dry repository,`` decay heat arising from radioactive waste extends the time before liquid water can contact a WP. Recent modeling and theoretical advances in nonisothermal, multiphase fracture-matrix flow have demonstrated (1) the critical importance of capillary pressure disequilibrium between fracture and matrix flow, and (2) that radioactive decay heat plays a dominant role in the ability of the engineered and natural barriers to contain and isolate radionuclides. Our analyses indicate that the thermo-hydrological performance of both the unsaturated zone (UZ) and saturated zone (SZ) will be dominated by repository-heat-driven hydrothermal flow for tens of thousands of years. For thermal loads resulting in extended-dry repository conditions, UZ performance is primarily sensitive to the thermal properties and thermal loading conditions and much less sensitive to the highly spatially and temporally variable ambient hydrologic properties and conditions. The magnitude of repository-heat-driven buoyancy flow in the SZ is far more dependent on the total mass of emplaced spent nuclear fuel (SNF) than on the details of SNF emplacement, such as the Areal Power Density [(APD) expressed in kill/acre] or SNF age.

  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). PMID:19817366

  3. 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…

  4. Direct hydrothermal synthesis of ternary Li-Mn-O oxide ion-sieves.

    PubMed

    Zhang, Qin-Hui; Sun, Shu-Ying; Li, Shao-Peng; Yin, Xian-Sheng; Yu, Jian-Guo

    2009-04-01

    Spinel-type ternary LiMn(2)O(4) oxide precursor was synthesized by direct hydrothermal synthesis of Mn(NO(3))(2), LiOH, and H(2)O(2) at 383 K for 8 h, a better technique for controlling the nanocrystalline structure with well-defined pore size distribution and high surface area than the traditional solid state reaction method. The final low-dimensional MnO(2) nanorod ion-sieve with a lithium ion selective adsorption property was further prepared by an acid treatment process to completely extract lithium ions from the Li-Mn-O lattice. The effects of hydrothermal reaction conditions on the nanostructure, chemical stability, and ion-exchange property of the LiMn(2)O(4) precursor and MnO(2) ion-sieve were systematically examined via powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and lithium ion selective adsorption measurements. The results show that this new kind of low-dimensional MnO(2) nanorod can be used for lithium extraction from aqueous environments, including brine, seawater, and waste water. PMID:19426343

  5. 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.

  6. 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.

  7. 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.

  8. Heat transfer through the sediments of the Mounds Hydrothermal Area, Galapagos Spreading Center at 86°W

    NASA Astrophysics Data System (ADS)

    Becker, Keir; von Herzen, Richard P.

    1983-01-01

    Heat transfer processes at the mounds area of the Galapagos Spreading Center at 86°W are revealed by temperatures measured at ≈ 10-m intervals in the 30±10m 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 ≈ 10-8 m/s, associated with individual mounds. Recharge is indicated at similar rates in the low heat flow belt ≈ 5 km south of the mounds and is suggested at slower rates in the intermediate heat flow (0.17-0.42 W/m2) belt surrounding the mounds heat flow high. Possible slow entrained recharge within ≈ 100 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 ≈ 50 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.

  9. 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.; Zamstorff, M.C. )

    1994-10-15

    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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

    Aaron Lewis; 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.

  16. 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.

  17. 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.

  18. 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.

  19. Multiple-scale hydrothermal circulation in 135 Ma oceanic crust of the Japan Trench outer rise: Numerical models constrained with heat flow observations

    NASA Astrophysics Data System (ADS)

    Ray, Labani; Kawada, Yoshifumi; Hamamoto, Hideki; Yamano, Makoto

    2015-09-01

    Anomalous high heat flow is observed within 150 km seaward of the trench axis at the Japan Trench offshore of Sanriku, where the old Pacific Plate (˜135 Ma) is subducting. Individual heat flow values range between 42 and 114 mW m-2, with an average of ˜70 mW m-2. These values are higher than those expected from the seafloor age based on thermal models of the oceanic plate, i.e., ˜50 mW m-2. The heat flow exhibits spatial variations at multiple scales: regional high average heat flow (˜100 km) and smaller-scale heat flow peaks (˜1 km). We found that hydrothermal mining of heat from depth due to gradual thickening of an aquifer in the oceanic crust toward the trench axis can yield elevated heat flow of the spatial scale of ˜100 km. Topographic effects combined with hydrothermal circulation may account for the observed smaller-scale heat flow variations. Hydrothermal circulation in high-permeability faults may result in heat flow peaks of a subkilometer spatial scale. Volcanic intrusions are unlikely to be a major source of heat flow variations at any scale because of limited occurrence of young volcanoes in the study area. Hydrothermal heat transport may work at various scales on outer rises of other subduction zones as well, since fractures and faults have been well developed due to bending of the incoming plate.

  20. Hydrothermal mineral deposits and fossil biota from a young (0.1 Ma) abyssal hill on the flank of the fast spreading East Pacific Rise: Evidence for pulsed hydrothermal flow and tectonic tapping of axial heat and fluids

    NASA Astrophysics Data System (ADS)

    Benjamin, Sara B.; Haymon, Rachel M.

    2006-05-01

    Heat flow data indicate that most hydrothermal heat loss from ocean lithosphere occurs on the flanks of the mid-ocean ridge, but few ridge flank hydrothermal sites are known. We describe the first nonseamount, abyssal hill hydrothermal mineral deposits to be recovered from the fast spreading East Pacific Rise (EPR) flanks. Deposits were sampled at two sites on an abyssal hill ˜5 km east of the EPR axis, just north of Clipperton Fracture Zone at 10°20'N, on ˜0.1 Ma lithosphere. "Tevnia Site" is on the axis-facing fault scarp of the hill, and "Ochre Site" is located ˜950 m farther east near the base of the outward-facing slope. Clusters of fragile, biodegradable Tevnia worm tubes at both sites indicate that hydrothermal fluids carried sufficient H2S to sustain Tevnia worms, and that fluid flow waned too recently to allow time for tube destruction. Presence of microbial mats and other biota also are consistent with recent waning of flow. The deposits are mineralogically zoned, from nontronite-celadonite to hydrous Fe-oxide+opaline silica to Mn-oxide (birnessite and todorokite). This places them into a distinctive class of Fe-Si-Mn hydrothermal deposits found along tectonic cracks and faults in young oceanic crust, and suggests that (1) deposits precipitated along an O2 gradient between ambient seawater and hydrothermal fluid; (2) fluid temperatures were <150°C and (3) undiluted fluids were Mg-depleted, and Fe-, K-, Si- and Mn-enriched. These fluids may derive from high temperature seawater-basalt interaction ± phase separation proximal to the axial melt zone, and lose Cu and Zn before venting due to conductive cooling and/or pH increase. Ochre Site samples are purely hydrothermal; however, Tevnia Site samples incorporate volcanic, sedimentary, and fossil components, and exhibit at least three generations of fracturing and hydrothermal cementation. The Tevnia Site breccias accumulated on the exposed fault scarp, possibly during multiple slip events and

  1. Geothermal direct heat applications program summary

    SciTech Connect

    1982-08-01

    In 1978, the Department of Energy Division of Geothermal and Hydropower Technologies initiated a program to accelerate the direct use of geothermal energy, in which 23 projects were selected. The projects, all in the western part of the US, cover the use of geothermal energy for space conditioning (heating and cooling) and agriculture (aquaculture and greenhouses). Initially, two projects were slated for industrial processing; however, because of lack of geothermal resources, these projects were terminated. Of the 23 projects, seven were successfully completed, ten are scheduled for completion by the end of 1983, and six were terminated for lack of resources. Each of the projects is being documented from its inception through planning, drilling, and resource confirmation, design, construction, and one year of monitoring. The information is being collected, evaluated, and will be reported. Several reports will be produced, including detailed topical reports on economics, institutional and regulatory problems, engineering, and a summary final report. To monitor progress and provide a forum for exchange of information while the program is progressing, semiannual or annual review meetings have been held with all project directors and lead engineers for the past four years. This is the sixth meeting in that series. Several of the projects which have been terminated are not included this year. Overall, the program has been very successful. Valuable information has been gathered. problems have been encountered and resolved concerning technical, regulatory, and institutional constraints. Most projects have been proven to be economical with acceptable pay-back periods. Although some technical problems have emerged, they were resolved with existing off-the-shelf technologies and equipment. The risks involved in drilling for the resource, the regulatory constraints, the high cost of finance, and large front-end cost remain the key obstacles to the broad development of

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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°C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425°C and one bimaterial (sapphire) at 425°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.

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

    USGS Publications Warehouse

    Morgan, L.A.; Shanks, W.C. Pat, III; 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

  7. Modeling Heat Transfer, Fluid Circulation and Permeability Alteration in Hydrothermal Systems with Loose Coupling to Magmatic Intrusion Modeling in the Lower Crust

    NASA Astrophysics Data System (ADS)

    Taron, J.; Karakas, O.; Mangan, M.; Dufek, J.; Ingebritsen, S.; Hickman, S. H.; Williams, C. F.

    2014-12-01

    The evolution of large scale hydrothermal systems entails spatially and temporally evolving permeability fields. During hydrothermal circulation, thermo-elastic stress and fluid pressure changes act upon partially open or hydrothermally altered fracture sets to modify permeability within the system, thereby shifting the patterns of circulation. To explore these interactions we are developing a thermo-hydromechanical (THM) simulator capable of coupling the dominant physics of the hydrothermal system and allowing flexibility in the use of monolithic or staggered numerical schemes. Permeability is allowed to evolve under several constitutive models tailored to both porous media and fractures, considering the influence of thermo-hydromechanical stress, creep, and elasto-plastic shear and dilation in a ubiquitously fractured medium. To expand our understanding of the long-term evolution of these systems, simulations incorporate information gleaned from the modeling of magmatic processes in the lower crust, where characteristics of the heat source are crucial in defining hydrothermal evolution. Results of a stochastic dike intrusion model are fed into the hydrothermal simulator to explore sensitivity relative to characteristics of the magmatic source. This is a first step to examining feedback mechanisms between heat transfer within geothermal fields and heat supply from the lower crust in a rigorous manner. We compare several simulations that elucidate the relative importance of magma intrusion rate and spatial distribution on overall heat transfer characteristics.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Implication for horizontally-elongated fluid flow inferred from heat flow measurements in the Iheya-North hydrothermal field, Okinawa Trough back-arc basin

    NASA Astrophysics Data System (ADS)

    Masaki, Yuka; Kinoshita, Masataka; Kawada, Yoshifumi

    2010-05-01

    The Okinawa Trough is a back-arc basin located in the southwestern part of Japan. It is considered to be in the initial stage of rifting of continental crust, and the activity generates volcanic edifices in this area, accompanied by hydrothermal circulation. The Iheya-North is one of the most active hydrothermal fields among them. As a proposed drilling site for the Integrated ocean Drilling Program, extensive geophysical surveys have been carried out including single-channel seismic imaging, and precise side-scan sonar imaging by using autonomous underwater vehicle 'Urashima' of Japan Agency for Marine-Science and Technology. In the recent few years, we have measured heat flow in and around the Iheya-North hydrothermal field to understand the spatial of hydrothermal circulation in detail. 78 measurements show that heat flow is higher than 10 W/m2 with in 0.5 km of the hydrothermal vent complex, that it gradually decrease eastward to < 1 W/m2, and that very low heat flow around 0.01 W/m2 is observed at 1.5 km east from the hydrothermal field. The average heat flow outside of Iheya-North is ~0.1 W/m2. The low heat flow to the east is most likely caused by an inward flow of seawater into the formation. Seismic and side-scan sonar images as well as piston core samples suggest an impermeable sediment layer to a few hundreds meters below the seafloor in this area. This sediment layer should work as a hydrological barrier to suppress flow through the seafloor, whereas seawater can penetrate into the formation at 1.5 km east of the hydrothermal field, where sidescan images suggest coars sediments on the seafloor. We infer that the hydrothermal circulation within the Iheya-North involves one with a horizontally-elongated scale (~1.5 km horizontal vs. ~a few hundreds meters vertical). We performed numerical calculations of fluid flow and heat transportation to give constraints on the depth of hydrothermal circulation, the magnitude of darcy velocity, and the permeability at

  13. 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.

  14. Mechanical properties of anodic titanium films containing ions of Ca and P submitted to heat and hydrothermal treatment.

    PubMed

    de Lima, Gabriel G; de Souza, Gelson B; Lepienski, Carlos M; Kuromoto, Neide K

    2016-12-01

    Anodic oxidation is a technique widely used to improve the bioactivity of Ti surface. In this study, micro-arc oxidation (MAO) was used to obtain an anodic film incorporating Ca and P ions to evaluate the effect of heat and hydrothermal treatment on the mechanical and in vitro bioactivity properties of these new layers. The MAO process was carried out using (CH3COO)2Ca·H2O and NaH2PO4·2H2O electrolytes under galvanostatic mode (150mA/cm(2)). The thermal treatments were made at 400°C and 600°C in air atmosphere while hydrothermal treatment was made in an alkaline water solution at 130°C. These surfaces presented desired mechanical properties for biomedical applications owing to the rutile and anatase phases in the anodic film that are more crystalline after thermal treatments; which provided an increase in hardness values and lower elastic modulus. The dry sliding wear resistance increased by performing thermal treatments on the surfaces with one condition still maintaining the film after the test. Bioactivity was investigated by immersion in simulated body fluid during 21 days and hydroxyapatite was formed on all samples. Finally, lower values of contact angle were obtained for heat treated samples. PMID:27479891

  15. 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.

  16. The response of two-phase hydrothermal systems to changing magmatic heat input at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Choi, Jaewoon; Lowell, Robert P.

    2015-11-01

    We develop numerical simulations of two-phase flow in a NaCl-H2O fluid subject to time varying basal heat flux boundary conditions in order to understand the response of hydrothermal vent temperature and salinity to changing magmatic heat input. The results show that periodic changes in basal heat input on a time scale of several years will not be detected in a continuous time series record of temperature measurements. Fluctuations in vent salinity may be recorded, however. For models with monotonic decay of the magmatic heat flux, a decline in vent temperature may not be observed for several years; however, once single phase conditions are established at the base of the system, a pulse of brine-derived fluid is expected to appear at the surface, followed by a gradual decline of salinity to the seawater value. The pulse of brine salinity is expected to occur before an observed decline in vent temperature. Observed rapid changes in vent temperature and salinity associated with either eruptive or non-eruptive magmatic events are not likely a result of changes in basal heat flux.

  17. First evidence for high-temperature off-axis venting of deep crustal/mantle heat: The Nibelungen hydrothermal field, southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Melchert, B.; Devey, C. W.; German, C. R.; Lackschewitz, K. S.; Seifert, R.; Walter, M.; Mertens, C.; Yoerger, D. R.; Baker, E. T.; Paulick, H.; Nakamura, K.

    2008-10-01

    During segment-scale studies of the southern Mid-Atlantic Ridge (MAR), 7-12° S, we found evidence in the water column for high-temperature hydrothermal activity, off-axis, east of Ascension Island. Extensive water column and seafloor work using both standard CTD and deep submergence AUV and ROV deployments led to the discovery and sampling of the "Drachenschlund" ("Dragon Throat") black smoker vent at 8°17.87' S/13°30.45' W in 2915 m water depth. The vent is flanked by several inactive chimney structures in a field we have named "Nibelungen". The site is located 6 km south of a non-transform offset between two adjacent 2nd-order ridge-segments and 9 km east of the presently-active, northward-propagating A2 ridge-segment, on a prominent outward-facing fault scarp. Both vent-fluid compositions and host-rock analyses show this site to be an ultramafic-hosted system, the first of its kind to be found on the southern MAR. The thermal output of this single vent, based on plume rise-height information, is estimated to be 60 ± 15 MW. This value is high for a single "black smoker" vent but small for an entire field. The tectonic setting and low He content of the vent fluids imply that high-temperature off-axis venting at "Drachenschlund" is driven not by magmatic processes, as at the majority of on-axis hydrothermal systems, but by residual heat "mined" from the deeper lithosphere. Whether this heat is being extracted from high-temperature mantle peridotites or deep crustal cumulates formed at the "duelling" non-transfrom offset is unclear, in either case the Drachenschlund vent provides the first direct observations of how cooling of deeper parts of the lithosphere, at least at slow-spreading ridges, may be occurring.

  18. Heat Flow and Segregation in Directional Solidification

    NASA Technical Reports Server (NTRS)

    Witt, A. F.

    1985-01-01

    This research is composed of three major components: (1) development of interface morphology control for automated Bridgman growth of semiconductor systems; (2) comparative analysis of segregation during crystal growth in a reduced gravity environment and in the presence of magnetic fields; and (3) consequences of seeding by meltback in Bridgman growth under reduced gravity conditions. In attempts to optimize furnace design for crystal growth in a reduced gravity environment, an analytical approach to heat transfer was developed. It was thus found that charge confining crucibles diminish the ability to control the growth interface morphology through its position within the gradient zone. A heat pipe hot zone system for Bridgman growth, in reduced gravity environment, of crystal with diameters up to 16 mm was developed. For growth of Ga-doped germanium in the multipurpose (ASTP) furnace, it was found that the application of transverse magnetic fields (up to 36 kg) does not substantially increase the effective distribution coefficient; i.e., diffusion-controlled segregation observed in reduced gravity environment cannot be reached nor approached by magnetic field induced melt stabilization.

  19. 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.

  20. 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

  1. Hydrothermal synthesis of anatase nanoleaves and size dependence of anatase-rutile transformation upon heating

    NASA Astrophysics Data System (ADS)

    Lisnycha, T. V.; Kirillov, S. A.; Potapenko, A. V.; Terikovska, T. E.; Kosilov, V. V.; Vyshnevskiy, O. A.

    2016-01-01

    Amorphous TiO2 obtained by adding TiCl4 to an alkaline medium crystallizes slowly and upon 3 years ageing transforms to nanosized anatase containing an admixture of brookite. The hydrothermal treatment of this sample in solutions of lithium hydroxide leads to anatase nanoleaves, and the more concentrated LiOH solution, the greater the nanoleaves and the smaller their specific surface area. The thermal treatment of nanoleaves leads to the bulk rutile, and the greater the specific surface area of anatase nanoleaves, the lower the anatase-rutile transition temperature. This is in line with conclusions based on the thermodynamic stability of nanosized anatase over the bulk rutile.

  2. 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

  3. 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.

  4. A facile vapor-phase hydrothermal method for direct growth of titanate nanotubes on a titanium substrate via a distinctive nanosheet roll-up mechanism.

    PubMed

    Liu, Porun; Zhang, Haimin; Liu, Hongwei; Wang, Yun; Yao, Xiangdong; Zhu, Guangshan; Zhang, Shanqing; Zhao, Huijun

    2011-11-30

    We present a facile vapor-phase hydrothermal approach for direct growth of vertically aligned titanate nanotubes on a titanium foil substrate. The resultant nanotubes display external diameters of 50-80 nm and walls with an average thickness of 10 nm that consist of more than 10 titanate layers. This is in strong contrast to the titanate nanotubes obtained from alkaline liquid-phase hydrothermal methods, which are generally smaller than 12 nm in external diameter and have walls consisting of less than five titanate layers. Importantly, the investigation confirmed that under vapor-phase hydrothermal conditions, the nanotubes were formed via a distinctive nanosheet roll-up mechanism that differs remarkably from those of conventional liquid-phase hydrothermal processes. For the first time, a coaxial circular cylinder crystal structure of the resultant nanotubes was confirmed. PMID:22035232

  5. 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.

  6. 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.

  7. A Galerkin, finite-element analysis of steady-state flow and heat transport in the shallow hydrothermal system in the East Mesa area, Imperial Valley, California

    USGS Publications Warehouse

    Miller, R.E.

    1977-01-01

    A steady-state simulation model was applied to the shallow hydrothermal system in the East Mesa area of Imperial Valley, Calif. The steady-state equations of flow and heat transport were solved by use of a Galerkin, finite-element method. A solution was obtained by iterating between the temperature and pressure equations, using updated densities and viscosities. Temperature and pressure were obtained for each node, and corresponding head values were calculated. The simulated temperature and pressure patterns correlated well with the observed patterns. Additional data, mainly from test drilling, would be required for construction of a similar model of the deep hydrothermal system.

  8. Direct contact melting process on a porous heating wall

    SciTech Connect

    Oka, M.; Hasegawa, E.

    1995-12-31

    Direct contact melting process takes place in many natural and technological processes. One of the important application of this process is thermal storage system. Phase change material (PCM) is stored in a small capsule. It melts by heating peripherally. This paper presents a theoretical study of direct contact melting process in a capsule. Inner wall surface of the capsule is made of porous material. In this melting process, melting rate is important factor for the efficiency of the system. In this paper, the authors propose utilization of porous material as a heating wall. This is one of the effective way to accelerate melting rate. Melted liquid goes through into the porous heating wall. As a result, the solid PCM can reach closer to the heating wall. The authors also discussed conductivity of the porous wall.

  9. Boundary Layer Flow, Heat, and Chemical Transfer near Vertical Heated Boreholes in Water-Saturated Rock: A Mechanism for Developing a Large Scale Underground Hydrothermal Experiment (DUSEL)

    NASA Astrophysics Data System (ADS)

    Mullally, D. M.; Lowell, R. P.

    2012-12-01

    We investigate a means of developing a large-scale hydrothermal experiment at the DUSEL site in the Homestake Mine, South Dakota, or elsewhere, by considering boundary layer flow, heat, and chemical transfer near an internally heated vertical borehole or borehole array emplaced in a water-saturated porous medium with homogeneous permeability. We use scale analysis to determine the relationships between vertical fluid velocity u, boundary layer thickness δ and the Rayleigh number Ra for both a single borehole maintained at constant temperature and a linear array of boreholes maintained at constant heat flux. For a single borehole, u ~ (a/y)Ra and δ ~ yRa^-1/2, whereas for the borehole array u ~(a/y) Ra^-1/3 and δ ~ yRa^-1/3, where y is the borehole height and a is the thermal diffusivity. We find that for y = 100 m, optimum initial permeability lies between ~ 10^-10 -10^-12 m^2 and the optimum heat flux is ~ 60 W/m^2. We also use scale analysis to determine the permeability change resulting from thermoelastic stresses generated by heating the rock near the boreholes and find that these stresses do not significantly impact the permeability so long as the initial porosity is ~ 5%, or the initial crack aspect ratios are less than or equal to 10^-2. Finally, we use scale analysis to investigate mineral dissolution within the boundary layer flow adjacent to the boreholes. Using the above velocity scaling and assuming linear reaction kinetics, and a crustal porosity of 5%, thermodynamic equilibrium may be obtained at the top of a 100 m high borehole provided reaction rate constants are in the range of ~ 10^-7 - 10^-8 s-1.

  10. Direct contact heat exchange interfacial phenomena for liquid metal reactors : Part I - heat transfer.

    SciTech Connect

    Cho, D.H.; Page, R.J.; Hurtault, D.; Abdulla, S.; Liu, X.; Anderson, M.H.; Bonazza, R.; Corradini, M.

    2002-02-26

    Experiments on direct-contact heat exchange between molten metal and water for steam production were conducted. These experiments involved the injection of water into molten lead-bismuth eutectic for heat transfer measurements in a 1-D geometry. Based on the initial results of the experiments, the effects of the water flow rate and the molten metal superheat (temperature difference between molten metal and saturated water) on the volumetric heat transfer coefficient were discussed.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

    2016-01-01

    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

  18. Consolidation of lunar regolith: Microwave versus direct solar heating

    NASA Technical Reports Server (NTRS)

    Kunitzer, J.; Strenski, D. G.; Yankee, S. J.; Pletka, B. J.

    1991-01-01

    The production of construction materials on the lunar surface will require an appropriate fabrication technique. Two processing methods considered as being suitable for producing dense, consolidated products such as bricks are 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 size. The regolith was considered to be a mare basalt with an overall density of 60 pct. of theoretical. Densification was assumed to take place by vitrification since this process requires moderate amounts of energy and time while still producing dense products. Microwave heating was shown to be significantly faster compared to solar furnace heating for rapid production of realistic-size bricks.

  19. Direct heating of compressed core by ultra-intense laser

    NASA Astrophysics Data System (ADS)

    Sunahara, A.; Johzaki, T.; Sakagami, H.; Nagatomo, H.; Mima, K.; Abe, Y.; Arikawa, Y.; Fujioka, S.; Shiraga, H.; Azechi, H.; Mori, Y.; Sentoku, Y.; Kitagawa, Y.

    2016-05-01

    We propose a new scheme for heating an imploded core in the fast-ignition scheme. In this method, a heating laser irradiates an imploded core plasma directly. The accelerated fast-ions as well as fast-electrons heat the core. Two-dimensional particle in cell (PIC) simulation confirmed that carbon C6+ and deuteron D+ ions were accelerated as well as fast electrons when ultra-intense laser irradiates the CD plasma. In order to estimate the temperature scaling of the heated core in this scheme, we conducted transport simulations in the one-dimensional conical geometry. Our results show that 5 keV of ignition temperature can be achieved at the intensity of 1021 W/cm2, and 1.5 ps pulse for the compressed CD plasma with 10g/cm3 density.

  20. 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... annual operating cost, energy consumption or other measure of energy consumption of a basic model...

  1. 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... annual operating cost, energy consumption or other measure of energy consumption of a basic model...

  2. 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... annual operating cost, energy consumption or other measure of energy consumption of a basic model...

  3. 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

  4. 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. PMID:9750274

  5. 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

  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. 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.

  8. Depth-dependent permeability of hydrothermal discharge zones: measurements through tidal modulation and implications for mid-ocean ridge heat budgets

    NASA Astrophysics Data System (ADS)

    Barreyre, T.; Crone, T. J.; Olive, J. A. L.

    2015-12-01

    The efficiency of hydrothermal circulation as a heat and mass exchanger is strongly modulated by the permeability structure of newly formed oceanic crust, which is known to vary spatially and temporally. Here we use the modulation of discharge temperatures by oscillatory tidal loading to estimate permeability vs. depth profiles beneath hydrothermal discharge zones at three basalt-hosted hydrothermal fields. Phase lags between fluctuations in discharge temperature and seafloor tidal loading have previously been inverted for the permeability of the underlying discharge zone using the poroelastic modulation model of Jupp and Schulz [2004]. This has yielded a wide range of permeability estimates ranging from 10-13­-10-9 m2. Here we extend the model to a stratified medium comprising a top layer (2A) of permeability k2A overlying a bottom layer (2B) of permeability k2B. We apply it to three basalt-hosted hydrothermal fields on a slow- (Lucky Strike), intermediate- (Main Endeavour Field), and fast-spreading (East Pacific Rise, EPR-9ºN) ridge, where stratification is well known from seismic studies. We estimate a layer 2A permeability of ~10-10 m2 at Lucky Strike, in sharp contrast with EPR-9ºN, where k2A ~ 10-13 m2. At the Main Endeavour field, two different sites located above different distinct discharge zones (as indicated by magnetic studies) yield a high and a low permeability. The permeability of layer 2B is not as well constrained as that of layer 2A, with possible values ranging from 10-14-10-12 m2. We note, however, that the variability in measured phase lags across hydrothermal fields is compatible with a uniform layer 2B permeability of ~10-13 m2. Using theoretical scalings for high-Rayleigh porous convection, we demonstrate that the permeability of layer 2B sets the "effective permeability" of the entire convective system, and therefore the efficiency of heat extraction through young oceanic crust. A uniform layer 2B permeability would thus reconcile the

  9. 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

  10. Measuring and Monitoring Heat Flow and Hydrothermal Changes in the Yellowstone Geothermal System using ASTER and MODIS Thermal Infrared Data

    NASA Astrophysics Data System (ADS)

    Vaughan, R. G.; Keszthelyi, L. P.; Lowenstern, J. B.; Heasler, H.; Jaworowski, C.

    2011-12-01

    The aim of this study was to use satellite thermal infrared (TIR) remote sensing to monitor geothermal activity within Yellowstone geothermal area (YGA) to meet the missions of both the U.S. Geological Survey and the National Park Service. 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 YGA (including hot springs, pools, geysers, fumaroles, and mud pots), by using satellite TIR remote sensing tools (e.g., ASTER and MODIS), 2) to estimate the radiant geothermal heat flux for individual thermal areas and for the entire YGA, and 3) to identify normal, background thermal changes so that significant, abnormal changes can be recognized, should they ever occur (e.g., thermal changes related to tectonic or hydrothermal activity, volcanic unrest, or geothermal development). Frequent, low-spatial resolution night time TIR observations from the MODIS instrument (1-km pixels) were used to quantify the background thermal flux of the whole YGA and all individual thermal areas. The MODIS Terra archive covering the previous decade (2000-2010) was analyzed and a background subtraction method was developed to automatically remove seasonal variations and extract TIR spectral radiance values. It was determined that the thermal change detection limit was equivalent to a 3-5 °C change over the entire (3x3 pixel) measured area, which is equivalent to a 9-17 °C change over a 29% fraction of the area (the sub-pixel fraction occupied by the thermal area). Alternatively, an area of static warm temperature (e.g., 93 °C) would have to increase from 100 to 36,500 m2 (11 to 216 m-diameter) to be clearly detected above scatter in the data. All of the thermal areas have been relatively stable within these limits for the last decade, although there are some thermal variations, near the limits of detection, which may reflect thermal disturbances that occur episodically in

  11. 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

  12. 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.

  13. Incremental cooling load determination for passive direct gain heating systems

    SciTech Connect

    Sullivan, P.W.; Mahone, D.; Fuller, W.; Gruber, J.; Kammerud, R.; Place, W.; Andersson, B.

    1981-05-01

    This paper examines the applicability of the National Association of Home Builders (NAHB) full load compressor hour method for predicting the cooling load increase in a residence, attributable to direct gain passive heating systems. The NAHB method predictions are compared with the results of 200 hour-by-hour simulations using BLAST and the two methods show reasonable agreement. The degree of agreement and the limitations of the NAHB method are discussed.

  14. 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

  15. Heat-flow and hydrothermal circulation at the ocean-continent transition of the eastern gulf of Aden

    NASA Astrophysics Data System (ADS)

    Lucazeau, Francis; Leroy, Sylvie; Rolandone, Frédérique; d'Acremont, Elia; Watremez, Louise; Bonneville, Alain; Goutorbe, Bruno; Düsünur, Doga

    2010-07-01

    In order to investigate the importance of fluid circulation associated with the formation of ocean-continent transitions (OCT), we examine 162 new heat-flow (HF) measurements in the eastern Gulf of Aden, obtained at close locations along eight seismic profiles and with multi-beam bathymetry. The average HF values in the OCT and in the oceanic domain (~ 18 m.y.) are very close to the predictions of cooling models, showing that the overall importance of fluids remains small at the present time compared to oceanic ridge flanks of the same age. However, local HF anomalies are observed, although not systematically, in the vicinity of the unsedimented basement and are interpreted by the thermal effect of meteoric fluids flowing laterally. We propose a possible interpretation of hydrothermal paths based on the shape of HF anomalies and on the surface morphology: fluids can circulate either along-dip or along-strike, but are apparently focussed in narrow "pipes". In several locations in the OCT, there is no detectable HF anomaly while the seismic velocity structure suggests serpentinization and therefore past circulation. We relate the existence of the present day fluid circulation in the eastern Gulf of Aden to the presence of unsedimented basement and to the local extensional stress in the vicinity of the Socotra-Hadbeen fault zone. At the scale of rifted-margins, fluid circulation is probably not as important as in the oceanic domain because it can be inhibited rapidly with high sedimentation rates, serpentinization and stress release after the break-up.

  16. 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

  17. 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

  18. 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

  19. Detectability of Tidally Heated Exomoons Using Direct Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Peters, Mary Anne; Turner, E. L.

    2013-01-01

    We determine the capability of ground and space-based observatories, both existing and planned, to directly image tidally heated exomoons orbiting exoplanets. Tidally heated exomoons, or THEMs, can conceivably be much more luminous than their host exoplanet and as little as 1000 times dimmer than the system's primary star. Tidal forces can heat THEMs at arbitrarily large angular separations from the host star, in both young and old star systems, to temperatures of hundreds or even thousands of degrees Kelvin. THEMs may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected angular separation from their host star to be imaged with existing high contrast instrumentation. Current instruments are capable of detecting nearby THEMs with Teff ≥ 600K and R ≥ Rearth in K-band. Future mid-infrared space telescopes, such as JWST and SPICA, will be capable of directly imaging THEMs around ~25 nearby stars with Teff ≥ 300K and R≥Rearth orbiting at angular separations ≥ 12AU at a 5σ confidence level in a 10,000 second integration. It is feasible that previously imaged exoplanets are actually THEMs or blends of such objects with hot young planets; we speculate that Fomalhaut b could be such a case. If THEMs exist and are common (i.e., nearby), it may be far easier to directly image a THEM with surface conditions that allow for liquid water than it will be to image an Earth-like planet in the classical Habitable Zone of its primary star.

  20. 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.

  1. 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.

  2. 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.

  3. Performance of direct contact latent heat storage unit

    SciTech Connect

    Farid, M.; Yacoub, K. )

    1989-01-01

    The performance of direct contact latent heat storage unit has been investigated in a glass column having an inside diameter and length of 0.2 m and 1.5 m respectively. Kerosene, as a heat transfer fluid, was bubbled through the continuous phase which was a solution of one of the hydrated salts: Na{sub 2}CO{sub 3}{center dot}10H{sub 2}O, Na{sub 2}SO{sub 4}{center dot}10H{sub 2}O, and Na{sub 2}HPO{sub 4}{center dot}12H{sub 2}O. The continuous phase temperature at different heights together with the kerosene inlet and outlet temperatures were measured with time during both heat charge and discharge. Theoretical prediction of the performance of the unit has been achieved employing the model for drop with internal circulation which was used to evaluate the transfer efficiency. Thermal efficiency of the nit was found to increase with the larger column. A sharp decrease in the magnitude of the heat transfer coefficient was observed soon after crystallization started. The coefficient increased significantly at higher kerosene flow rates due to the information of smaller bubbles.

  4. 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.

  5. 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.

  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. Direct heating rates associated with gravity wave saturation

    NASA Astrophysics Data System (ADS)

    Becker, Erich

    2004-04-01

    Analysis of filtering out subscale motions is applied for internal gravity waves. This leads to a new perspective of the planetary-scale sensible heat budget of the upper mesosphere/lower thermosphere. In line with previous results of Becker and Schmitz, the present paper recapitulates that the dissipation of gravity wave kinetic energy and the local adiabatic conversion of mean enthalpy into gravity wave kinetic energy cannot be neglected, and that the net effect of both cools the upper mesosphere/lower thermosphere. In addition, the importance of the wave entropy flux-an effect which is ignored in customary gravity wave parameterizations for global circulation models-is stressed. We show that, when evaluated on the basis of Lindzen's saturation assumption, the wave entropy flux convergence behaves like a vertical diffusion of the mean stratification, where the wave-induced diffusion coefficient is involved with a Prandtl number of 2. This result imposes an upper bound of 2 for the effective Prandtl number which scales the combined entropy flux owing to turbulence and gravity waves. The direct heating rates generated by gravity wave saturation are assessed quantitatively, using an idealized general circulation model completed by a Lindzen-type gravity wave parameterization.

  8. 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.

  9. 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.

  10. 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

  11. Age alters the cardiovascular response to direct passive heating.

    PubMed

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

    1998-04-01

    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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  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. 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.

  7. Numerical Analysis of Lead-Bismuth-Water Direct Contact Boiling Heat Transfer

    NASA Astrophysics Data System (ADS)

    Yamada, Yumi; Takahashi, Minoru

    Direct contact boiling heat transfer of sub-cooled water with lead-bismuth eutectic (Pb-Bi) was investigated for the evaluation of the performance of steam generation in direct contact of feed water with primary Pb-Bi coolant in upper plenum above the core in Pb-Bi-cooled direct contact boiling water fast reactor. An analytical two-fluid model was developed to estimate the heat transfer numerically. Numerical results were compared with experimental ones for verification of the model. The overall volumetric heat transfer coefficient was calculated from heat exchange rate in the chimney. It was confirmed that the calculated results agreed well with the experimental result.

  8. 76 FR 71835 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-18

    ... definitions and energy conservation standards for vented gas hearth direct heating equipment. 75 FR 20112. \\1... are excluded from DOE's regulations.'' 75 FR 20112, 20234 (April 16, 2010). In this final rule, DOE is... energy conservation standards for direct heating equipment manufactured on or after April 16, 2013. 75...

  9. Direct Electron Heating at Moderate Harmonic Number for Compact Ignition Devices

    SciTech Connect

    R. Majeski

    1999-07-01

    Direct electron heating of compact ignition devices by radio-frequency power in the 300-400 MHz,range is discussed. The possible advantage of this approach to heating an ignition device, as opposed to resonant heating of an ion population, is the insensitivity to the exact value of the magnitude field. Heating with central power deposition during a toroidal field ramp is therefore possible.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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. PMID:21774682

  15. Hydrothermal pretreatment of coal

    SciTech Connect

    Loo, Bock; Ross, D.S.

    1990-08-14

    We are examining the effects on composition and behavior of Argonne-supplied Wyodak coal under both thermal (no added water/N{sub 2}) and hydrothermal (liquid water/N{sub 2}) conditions at 350{degree}C for periods of 30 min and 5 hr, with emphasis during this period on the longer treatment. Field ionization mass spectrometry (FIMS) of the untreated, thermally treated, and hydrothermally treated coals is conducted at conditions where the samples are heated from ambient to 500{degree}C at 2.5{degree}/min. In the 5 hr work the volatilities of the coals are 24%, 16%, and 25% respectively. Solvent swelling studies with the recovered coals do not demonstrate the expected lower degree of crosslinking in the hydrothermal case. Both the thermal and hydrothermal treatments yield products with a decreased swelling ratio, but the ratio for the product from the aqueous treatment is slightly lower than that from thermal treatment. At present we cannot reconcile this result with our other data. 4 refs., 6 figs.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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

  2. Heat transfer enhancement and vortex flow structure over a heated cylinder oscillating in the crossflow direction

    SciTech Connect

    Gau, C.; Wu, J.M.; Liang, C.Y.

    1999-11-01

    Experiments are performed to study the flow structure and heat transfer over a heated oscillating cylinder. Both flow visualization using a smoke wire and local heat transfer measurements around the cylinder were made. The excitation frequencies of the cylinder are selected at F{sub e}/F{sub n} = 0, 0.5, 1, 1.5, 2, 2.5, and 3. These include excitations at harmonic, subharmonic, superharmonic, and non harmonic frequencies. Synchronization of vortex shedding with the cylinder excitation occurs not only at F{sub e}/F{sub n} = 1 but also at F{sub e}/F{sub n} = 3, which can greatly enhance the heat transfer. The simultaneous enhancement of heat transfer at the stagnation point, its downstream region, and the wake region of the flow suggests that different modes of instabilities occurring in the shear layer of the near wake are actually initiated and amplified far upstream in the stagnation point, which were suppressed in the accelerated flow region and re-amplified in the decelerated flow region. As long as the dominant mode of the instability is amplified by the excitation of cylinder, enhancement of heat transfer can be obtained. During the experiments, the Reynolds numbers vary from 1,600 to 4,800, the ratios of oscillation amplitude to diameter of the cylinder from 0.064 to 0.016.

  3. 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.

  4. Direct Resistance Joule Heating of Al-10 pct Si-Coated Press Hardening Steel

    NASA Astrophysics Data System (ADS)

    Lee, Chang Wook; Choi, Won Seok; Cho, Yeol Rae; De Cooman, Bruno C.

    2016-06-01

    Various rapid heating methods have been developed to increase the productivity of press hardening steel. One of these methods is direct resistance Joule heating. This heating method results in the melting of the surface coating and the formation of a persistent liquid trail as a result of the high thermal conductivity and low melting temperature of the Al-10 pct Si alloy coating. This can be addressed by an alloying preheating treatment prior to the press hardening process.

  5. 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.

  6. Direct Resistance Joule Heating of Al-10 pct Si-Coated Press Hardening Steel

    NASA Astrophysics Data System (ADS)

    Lee, Chang Wook; Choi, Won Seok; Cho, Yeol Rae; De Cooman, Bruno C.

    2016-03-01

    Various rapid heating methods have been developed to increase the productivity of press hardening steel. One of these methods is direct resistance Joule heating. This heating method results in the melting of the surface coating and the formation of a persistent liquid trail as a result of the high thermal conductivity and low melting temperature of the Al-10 pct Si alloy coating. This can be addressed by an alloying preheating treatment prior to the press hardening process.

  7. 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

  8. Field-structured composites for efficient, directed heat transfer

    NASA Astrophysics Data System (ADS)

    Martin, James E.; Gulley, G.

    2009-10-01

    Thermally conductive composites are needed for a variety of applications, especially as thermal interface materials. Unfortunately, the addition of even highly conductive particles to a polymer raises its conductivity only slightly and incurs a commensurate increase in the viscosity of the prepolymer resin. Meaningful increases in the thermal conductivity of the final composite require a filled resin that has the rheology of a typical paste. In this paper, we report on the use of uniaxial, biaxial, and triaxial ac magnetic fields to organize thermally conductive magnetic particles into structures that conduct heat more efficiently. Experimental results are compared to an extension of the Maxwell-Eucken theory that takes into account spatial correlations between particles. Both theory and experiment show that the thermal conductivity of field-structured composites increases essentially linearly with particle loading, and that the enhancement is significantly greater than that of unstructured composites. The measured conductivity enhancements are found to be comparable to the enhancements in magnetic permeability of these composites and are far less than the enhancements in the electrical conductivity. These results indicate the value of field structuring in enhancing the performance of a thermal interface material and show that particle percolation is not a critical factor in achieving high performance.

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

    NASA Astrophysics Data System (ADS)

    Winslow, Dustin M.; Fisher, Andrew T.

    2015-06-01

    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.

  10. 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

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

    PubMed

    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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  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. 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.

  1. Chemical and biochemical transformations in hydrothermal plumes

    NASA Astrophysics Data System (ADS)

    Lilley, Marvin D.; Feely, Richard A.; Trefry, John H.

    Hydrothermal plumes integrate the heat and mass flux originating at seafloor hydrothermal vents thereby providing both a means of detecting hydrothermal activity and estimating hydrothermal fluxes. Many chemical species are introduced into the deep sea via hydrothermal plumes (Figure 1) in concentrations many orders of magnitude higher than that existing in background seawater (e.g. H2, CH4 3He, Mn, Fe) while others are scavenged from seawater by hydrothermal particles (e.g. PO4-3, V, As, rare earth elements, Th). Dilution by entrainment of background seawater in the buoyant portion of the plume is very rapid (see chapters by Lupton and McDuff, this volume) such that the hydrothermal component in the near-field portion of the neutrally buoyant plume represents only about 0.01% of the mixture. Nevertheless, chemical tracers such as 3He, CH4, and Mn are widely utilized in addition to temperature, salinity, and light transmission anomalies to detect hydrothermal venting and to draw inferences about the nature of the underlying geochemistry of the hydrothermal system. Many other chemical tracers can be utilized during plume studies to provide additional information about the nature of the venting. These include particles, H2, Al, and radioisotopes, among others.

  2. 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.

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

    PubMed

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

    2015-05-01

    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

  4. 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

  5. Fluid flow rate, temperature and heat flux at Mohns Ridge vent fields: evidence from isosampler measurements for phase separated hydrothermal circulation along the arctic ridge system

    NASA Astrophysics Data System (ADS)

    Schultz, A.; Pedersen, R. B.; Thorseth, I. H.; Taylor, P.; Flynn, M.

    2005-12-01

    An expedition to the Mohns Ridge in the Norwegian-Greenland sea was carried out in July-August 2005 as part of BIODEEP, lead by University of Bergen (UoB). UoB had previously detected water column methane along this very slow spreading ridge. Previous ROV observations along the ridge (71 deg 18'N, 5 deg 47'W, 605 mbsl) near Jan Mayen had uncovered a broad area of ferric hydroxide-rich bacterial/mineral assemblages, comprising large populations of gallionella bacteria. This area was revisted in 2005. Characteristic of sections of this area ("Gallionella Garden") are chimney-like structures standing ~15 cm tall, often topped by a sea lily (heliometra glacialis). The interior of the structures comprised quasi-concentric bands with vertically-oriented channels. The Oregon State University/Cardiff University Isosampler sensor determined that some of these assemblages support fluid flow through their interior. The outflow from the chimney structures was typically +0.5 deg C, against background temperatures of -0.3 deg C. Flow anomalies were also identified atop extensive bacterial mats. Gallionella Gardens is several km in extent with active, albeit extremely low temperature hydrothermal flow. A field of active high temperature smoker chimney structures was located near Gallionella Garden at 540 mbsl. This field extends ~500 m along a scarp wall, with hydrothermal mounds extending along faults running perpendicular to the scarp, each of which has multiple smoker vents and areas of diffuse flow. There was evidence for phase separation, with a negatively buoyant fluid phase exiting some vent orifices and descending along the vent wall; and evidence for gas phase condensing after leaving some vent orifices. Gas bubble emissions were not uncommon. Isosampler sensors were available that were configured for lower temperature measurements at Gallionella Garden. While capable of detecting variations in effluent at the 4 millidegree level, the temperature ceiling for the sensor

  6. Performance of direct contact latent heat storage units with two hydrated salts

    SciTech Connect

    Farid, M.M. ); Khalaf, A.N. )

    1994-02-01

    The performance of a direct contact latent heat storage unit, that consists of two columns with different hydrated salts, has been investigated. Na[sub 2]CO[sub 3]-10H[sub 2]O (sodium carbonate decahydrate) and Na[sub 2]S[sub 2]O[sub 3][center dot]5H[sub 2]O (sodium thiosulphate pentahydrate) were contained in separate columns both having an inside diameter and total length of 0.184 m and 1.0 m, respectively. During heat charge, the hot keresone as a heat transfer fluid was bubbled through the sodium thiosulfate solution first. The partially cooled kerosene was then pumped to the second column containing the sodium thiosulfate solution first. The partially cooled kerosene was then pumped to the second column containing the sodium carbonate solution, discharging most of its heat content. Flow direction was reversed during heat discharge. The continuous phase temperature in the two columns, as well as kerosene inlet and outlet temperatures, were measured continuously. Results showed significant improvement in heat transfer rates by using two separate columns containing similar or different salts. The use of a combination of two different salts, having different crystallization temperatures, and contained in different columns connected in series, may provide better means of heat storage by allowing the system to operate as a phase change storage for longer periods of operation. This is particularly suitable for solar energy applications in which the collector temperature may vary significantly during the day.

  7. Introduction to Atlantic Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.; Thompson, Geoffrey

    1993-06-01

    Seafloor hydrothermal research has advanced rapidly from local to global scope through a sequence of discoveries. Hydrothermal research at seafloor spreading centers began in the mid-1960s with the discovery of hot metalliferous brines and sediments ponded in deeps along the slow spreading (half rate 1 cm yr-1) axis of the Red Sea [Chamock, 1964; Miller, 1964; Swallow and Crease, 1965; Miller et al., 1966; Hunt et al., 1967; Bischoff, 1969]. At the same time a hydrothermal metalliferous component was identified in sediments of the East Pacific Rise [Skomyakova, 1965; Arrhenins and Bonatti, 1965; Boström and Peterson, 1966]. Geophysicists recognized that heat flow measurements at spreading centers could only be explained by convective cooling of the crust with circulating seawater [Elder, 1967; Lister, 1972].

  8. 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.

  9. 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.

  10. 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.

  11. A method for quantitatively estimating diffuse and discrete hydrothermal discharge

    NASA Astrophysics Data System (ADS)

    Baker, Edward T.; Massoth, Gary J.; Walker, Sharon L.; Embley, Robert W.

    1993-07-01

    Submarine hydrothermal fluids discharge as undiluted, high-temperature jets and as diffuse, highly diluted, low-temperature percolation. Estimates of the relative contribution of each discharge type, which are important for the accurate determination of local and global hydrothermal budgets, are difficult to obtain directly. In this paper we describe a new method of using measurements of hydrothermal tracers such as Fe/Mn, Fe/heat, and Mn/heat in high-temperature fluids, low-temperature fluids, and the neutrally buoyant plume to deduce the relative contribution of each discharge type. We sampled vent fluids from the north Cleft vent field on the Juan de Fuca Ridge in 1988, 1989 and 1991, and plume samples every year from 1986 to 1991. The tracers were, on average, 3 to 90 times greater in high-temperature than in low-temperature fluids, with plume values intermediate. A mixing model calculates that high-temperature fluids contribute only ˜ 3% of the fluid mass flux but > 90% of the hydrothermal Fe and > 60% of the hydrothermal Mn to the overlying plume. Three years of extensive camera-CTD sled tows through the vent field show that diffuse venting is restricted to a narrow fissure zone extending for 18 km along the axial strike. Linear plume theory applied to the temperature plumes detected when the sled crossed this zone yields a maximum likelihood estimate for the diffuse heat flux of8.9 × 10 4 W/m, for a total flux of 534 MW, considering that diffuse venting is active along only one-third of the fissure system. For mean low- and high-temperature discharge of 25°C and 319°C, respectively, the discrete heat flux must be 266 MW to satisfy the mass flux partitioning. If the north Cleft vent field is globally representative, the assumption that high-temperature discharge dominates the mass flux in axial vent fields leads to an overestimation of the flux of many non-conservative hydrothermal species by about an order of magnitude.

  12. Heat exchange model in absorption chamber of water-direct-absorption-typed laser energy meter

    NASA Astrophysics Data System (ADS)

    Feng Wei, Ji; Qun Sun, Li; Zhang, Kai; Hu, XiaoYang; Zhou, Shan

    2015-04-01

    The interaction between laser and water flow is very complicated in the absorption chamber of a high energy laser (HEL) energy meter which directly uses water as an absorbing medium. Therefore, the heat exchange model cannot be studied through traditional methods, but it is the most important factor to improve heat exchange efficiency in the absorption chamber. After the exchanges of heat and mass were deeply analyzed, experimental study and numerical fitting were brought out. The original testing data of laser power and water flow temperature at one moment were utilized to calculate those at the next moment, and then the calculated temperature curve was compared with the measured one. If the two curves matched well, the corresponding coefficient was obtained. Meanwhile, numerous experiments were performed to study the effects of laser power, duration, focal spot scale, and water flow rate on heat exchange coefficient. In addition, the relationship between water phase change and heat exchange was analyzed. The heat exchange coefficient was increased by optimizing the construction of the absorption chamber or increasing water flow rate. The results provide the reference for design of water-direct-absorption-typed HEL energy meters, as well as for analysis of the interaction between other similar lasers and water flow.

  13. 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.

  14. 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.

  15. Direct numerical simulation of particulate flows with heat transfer in a rotating cylindrical cavity.

    PubMed

    Schmidt, Robin; Nikrityuk, Petr A

    2011-06-28

    The purpose of this work was the direct numerical simulation of heat and fluid flow by granular mixing in a horizontal rotating kiln. To model particle behaviour and the heat and fluid flow in the drum, we solve the mass conservation, momentum and energy conservation equations directly on a fixed Eulerian grid for the whole domain including particles. At the same time the particle dynamics and their collisions are solved on a Lagrangian grid for each particle. To calculate the heat transfer inside the particles we use two models: the first is the direct solution of the energy conservation equation in the Lagrangian and Eulerian space, and the second is our so-called linear model that assumes homogeneous distribution of the temperature inside each particle. Numerical simulations showed that, if the thermal diffusivity of the gas phase significantly exceeds the same parameter of the particles, the linear model overpredicts the heating rate of the particles. The influence of the particle size and the angular velocity of the drum on the heating rates of particles is studied and discussed. PMID:21576173

  16. 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.

  17. 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. PMID:25289516

  18. 76 FR 43941 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ... number of product offerings. 75 FR 20112, 20231 (April 16, 2010). In order to comply with the energy... found at: http://www.regulations.gov/#!docketDetail ;dct=FR+PR+N+O+SR+PS;rpp=250;so=DESC;sb=postedDate... vented gas hearth direct heating equipment. 75 FR 20112. \\1\\ For editorial reasons, upon codification...

  19. 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).

  20. 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. PMID:26024175

  1. Probing Hydrothermal Organic Reaction Mechanisms with Hydrothermal Photochemistry

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Gould, I.; Shock, E.

    2013-12-01

    In most hydrothermal organic experiments the emphasis is on reaction product distributions and kinetic measurements, with mechanistic information or the direct evidence of proposed reaction intermediates rare or lacking. We believe that greater mechanistic insight will yield greater predictive power. Previously, we studied the reactions of a model ketone, dibenzylketone (DBK) in aqueous media at 300°C and 700 bars for durations up to several days [1], and found that many of the reaction products arise from coupling of benzyl and related radicals generated through homolytic bond cleavage of DBK. In the present work, we find that in situ photochemical generation of the radicals can provide independent evidence for radical intermediates in the hydrothermal reaction of DBK, yielding valuable insights into the thermal reactions. Hydrothermal photochemical experiments of DBK were conducted in water in sealed fused silica glass tubes at 300°C and 86 bars under UV irradiation for minutes. The short timescale of the experiments allows the primary radical coupling products of DBK to be generated and identified, and their follow-up reactions to be monitored directly. The primary hydrothermal photolysis products include toluene, bibenzyl, a three-benzene-ring product (with isomers), and two four-benzene-ring products (with isomers), which represent a much simpler version of the products obtained through thermal reactions under similar conversions. Most of the observed photolysis products were identical to the ones in the thermal reactions, and those not observed in thermal reactions were found to be the short-lived precursors of the thermal products. As an example, the transformation of one four-ring product to the other was attained and monitored by experiments in which hydrothermal photolysis of DBK was followed by thermolysis at 300°C for a further few hours. The transformation steps included dehydration and isomerization, which were known to be thermodynamically

  2. 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.

  3. 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.

  4. 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''.

  5. Heat-Transfer Measurements in the Primary Cooling Phase of the Direct-Chill Casting Process

    NASA Astrophysics Data System (ADS)

    Caron, Etienne J. F. R.; Baserinia, Amir R.; Ng, Harry; Wells, Mary A.; Weckman, David C.

    2012-10-01

    Thermal modeling of the direct-chill casting process requires accurate knowledge of (1) the different boundary conditions in the primary mold and secondary direct water-spray cooling regimes and (2) their variability with respect to process parameters. In this study, heat transfer in the primary cooling zone was investigated by using temperature measurements made with subsurface thermocouples in the mold as input to an inverse heat conduction algorithm. Laboratory-scale experiments were performed to investigate the primary cooling of AA3003 and AA4045 aluminum alloy ingots cast at speeds ranging between 1.58 and 2.10 mm/s. The average heat flux values were calculated for the steady-state phase of the casting process, and an effective heat-transfer coefficient for the global primary cooling process was derived that included convection at the mold surfaces and conduction through the mold wall. Effective heat-transfer coefficients were evaluated at different points along the mold height and compared with values from a previously derived computational fluid dynamics model of the direct-chill casting process that were based on predictions of the air gap thickness between the mold and ingot. The current experimental results closely matched the values previously predicted by the air gap models. The effective heat-transfer coefficient for primary cooling was also found to increase slightly with the casting speed and was higher near the mold top (up to 824 W/m2·K) where the molten aluminum first comes in contact with the mold than near the bottom (as low as 242 W/m2·K) where an air gap forms between the ingot and mold because of thermal contraction of the ingot. These results are consistent with previous studies.

  6. Direct numerical simulation of turbulent heat transfer in a fluid-porous domain

    NASA Astrophysics Data System (ADS)

    Chandesris, M.; D'Hueppe, A.; Mathieu, B.; Jamet, D.; Goyeau, B.

    2013-12-01

    Turbulent heat transfer in a channel partially filled by a porous medium is investigated using a direct numerical simulation of an incompressible flow. The porous medium consists of a three-dimensional Cartesian grid of cubes, which has a relatively high permeability. The energy equation is not solved in the cubes. Three different heating configurations are studied. The simulation is performed for a bulk Reynolds number Reb = 5500 and a Prandtl number Pr = 0.1. The turbulent flow quantities are compared with the results of Breugem and Boersma ["Direct numerical simulations of turbulent flow over a permeable wall using a direct and a continuum approach," Phys. Fluids 17, 025103 (2005)] to validate the numerical approach and macroscopic turbulent quantities are analyzed. Regarding the temperature fields, original results are obtained. The temperature fields show an enhanced turbulent heat transfer just above the porous region compared to the solid top wall, which can be related to the large vortical structures that develop in this region. Furthermore, these large structures induce pressure waves inside the porous domain which are responsible of large temperature fluctuations deep inside the porous region where the flow is laminar. Finally, macroscopic turbulent quantities are computed to get reference results for the development of macroscopic turbulent heat transfer models in fluid-porous domain.

  7. A RECIPROCATING SOLAR HEATED ENGINE UTILIZING DIRECT ABSORPTION BY SMALL PARTICLES

    SciTech Connect

    Hull, Patricia G.; Hunt, Arlon J.

    1981-05-01

    A new type of reciprocating solar engine utilizing small particles to absorb concentrated sunlight directly within the cylinders is described. The engine operates by drawing an air particle mixture into the cylinder, compressing the mixture, opening an optical valve to allow concentrated sunlight to enter through a window in the top of the cylinder head, absorbing the solar flux with the particles, and converting the heat trapped by the air-particle mixture into mechanical energy with the downward stroke of piston. It differs from other gas driven heat engines using solar energy in three main respects. First, the radiant flux is deposited directly in the working fluid inside the cylinder; second, the heat is directed to the appropriate cylinder by controlling the solar flux by an optical system; third, the gas is heated during a significant portion of the compression stroke. The thermodynamic efficiency of the engine is calculated using an analytical model and is compared to several other engine cycles of interest.

  8. 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.

  9. 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.

  10. A consistent direct discretization scheme on Cartesian grids for convective and conjugate heat transfer

    NASA Astrophysics Data System (ADS)

    Sato, Norikazu; Takeuchi, Shintaro; Kajishima, Takeo; Inagaki, Masahide; Horinouchi, Nariaki

    2016-09-01

    A new discretization scheme on Cartesian grids, namely, a "consistent direct discretization scheme", is proposed for solving incompressible flows with convective and conjugate heat transfer around a solid object. The Navier-Stokes and the pressure Poisson equations are discretized directly even in the immediate vicinity of a solid boundary with the aid of the consistency between the face-velocity and the pressure gradient. From verifications in fundamental flow problems, the present method is found to significantly improve the accuracy of the velocity and the wall shear stress. It is also confirmed that the numerical results are less sensitive to the Courant number owing to the consistency between the velocity and pressure fields. The concept of the consistent direct discretization scheme is also explored for the thermal field; the energy equations for the fluid and solid phases are discretized directly while satisfying the thermal relations that should be valid at their interface. It takes different forms depending on the thermal boundary conditions: Dirichlet (isothermal) and Neumann (adiabatic/iso-heat-flux) boundary conditions for convective heat transfer and a fluid-solid thermal interaction for conjugate heat transfer. The validity of these discretizations is assessed by comparing the simulated results with analytical solutions for the respective thermal boundary conditions, and it is confirmed that the present schemes also show high accuracy for the thermal field. A significant improvement for the conjugate heat transfer problems is that the second-order spatial accuracy and numerical stability are maintained even under severe conditions of near-practical physical properties for the fluid and solid phases.

  11. Petawatt-laser direct heating of uniformly imploded deuterated-polystyrene shell target.

    PubMed

    Kitagawa, Yoneyoshi; Sentoku, Yasuhiko; Akamatsu, Shin; Sakamoto, Wataru; Tanaka, Kazuo A; Kodama, Ryosuke; Nishimura, Hiroaki; Inubushi, Yuichi; Nakai, Mitsuo; Watari, Takeshi; Norimatsu, Takayoshi; Sunahara, Atsushi

    2005-01-01

    A uniformly imploded deuterated polystyrene (CD) shell target is fast-heated by a Petawatt (PW) laser without cone guide. The best illumination timing is found to be in a narrow region around 80+/-20 picoseconds from the onset of the stagnation phase, where thermal neutrons are enhanced four to five times by the PW laser of energy less than 10% of the implosion laser. The timing agrees with the timings of enhancement of the x-ray emission from the core and reduction of the bremsstrahlung radiation from scattered hot electrons. The PW laser, focused to the critical density point, generates the energetic electrons within as narrow an angle as 30 degrees , which then heats the imploded CD shell to enhance thermal neutrons. These results first demonstrate that the PW laser directly heats the imploded core without any conelike laser guide. PMID:15697731

  12. Direct numerical simulations of a reacting mixing layer with chemical heat release

    NASA Technical Reports Server (NTRS)

    Mcmurtry, P. A.; Jou, W.-H.; Metcalfe, R. W.; Riley, J. J.

    1985-01-01

    In order to study the coupling between chemical heat release and fluid dynamics, direct numerical simulations of a chemically reacting mixing layer with heat release are performed. The fully compressible equations as well as an approximate set of equations that is asymptotically valid for low-Mach-number flows are treated. These latter equations have the computational advantage that high-frequency acoustic waves have been filtered out, allowing much larger time steps to be taken in the numerical solution procedure. A detailed derivation of these equations along with an outline of the numerical solution technique is given. Simulation results indicate that the rate of chemical product formed, the thickness of the mixing layer, and the amount of mass entrained into the layer all decrease with increasing rates of heat release.

  13. 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

  14. 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.

  15. Heat transfer in an industrial directional solidification furnace with multi-heaters for silicon ingots

    NASA Astrophysics Data System (ADS)

    Li, Zaoyang; Liu, Lijun; Liu, Xin; Zhang, Yunfeng; Xiong, Jingfeng

    2014-01-01

    We carried out transient global simulations of melting, growing and annealing processes in an industrial directional solidification furnace with a top and side heater. The power distribution between the two heaters was set to 3:7, 5:5 and 7:3 to investigate its effect on global heat transfer and silicon crystal growth. Quantitative comparisons of temperature distributions are presented. Increasing the top heating power slightly increases the melting time and changes the melting sequence. In the crystal growth process, adjusting the power distribution from 3:7 to 7:3 can lead to an 8-12 K change in axial temperature difference in the silicon domain. Both the intensity and pattern of the silicon melt flow are influenced by the change in power distribution. The melt-crystal interface is less convex to the melt with an increase in top heating power, especially at the final stage of solidification. In the annealing process, the ingot temperature decreases to approximately 1600 K to reduce the thermal stress and dislocation density. Isotherm shapes are different at this stage and may lead to different thermal stress and dislocation density distributions in the silicon ingot. The numerical results provide a basic understanding of the heat transfer characteristics due to power distribution in an industrial multi-heater directional solidification furnace.

  16. 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.

  17. 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.

  18. Direct Actuation of Small-Scale Motions for Enhanced Heat Transfer in a Straight Channel

    NASA Astrophysics Data System (ADS)

    Hidalgo, Pablo; Glezer, Ari

    2010-11-01

    Heat transfer enhancement by small-scale flow interactions that are induced within the core flow of a heated, high-aspect ratio straight channel are investigated experimentally. Direct actuation of small scale motions is provided by streamwise-embedded piezoelectrically-driven cantilevered reeds that span the entire channel height. Deliberate interactions between the reeds and a given core flow lead to the formation of time-periodic vorticity concentrations over a range of vibration frequencies that are advected with the core flow and induce small-scale motions near the channel's surfaces. Heat transfer measurements are obtained using novel, microfabricated heaters with integrated temperature sensors that are deposited on a silicon substrate. It is shown that the actuation disrupts the thermal boundary layers and result in a significant enhancement of the local and global heat transfer along the channel compared to the baseline (unactuated) flow. The interactions between the reed-induced motions and the channel internal surfaces and mixing within the core flow are investigated in detail using high resolution particle image velocimetry (PIV) with emphasis on local and global heat transfer across the channel boundaries.

  19. 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.

  20. Direct Measurement of the Adsorbed Film Volume for Estimating Heats of Adsorption

    NASA Astrophysics Data System (ADS)

    Gillespie, Andrew; Dohnke, Elmar; Rash, Tyler; Stalla, David; Knight, Ernest; Seydel, Florian; Sweany, Mark; Pfeifer, Peter

    Compressed hydrogen and methane require extremely high pressures or low temperatures in order to compete with the energy density of conventional fossil fuels. Adsorbent materials provide a means to increase the energy density of these gasses up to 6 times that of compressed gas at the same temperature and pressure. One major concern in engineering adsorbed gas systems is thermal management during charging and discharging. Adsorption is an exothermic process, releasing heat during charging and absorbing heat during discharging. To estimate the heat of adsorption, it is common to analyze excess adsorption isotherms by converting to absolute adsorption and employ the Clausius Clapeyron relation. However, this method requires an assumed volume of the adsorbed state. It is common for researchers to assume that the adsorbed film occupies the entire pore volume of the adsorbent material. However, the adsorbed film only occupies a fraction of the total pore volume. This yields heats of adsorption that are underestimated by as much as 10kJ/mol at high coverage. In this talk, we present a method to directly measure the adsorbed film volume as a function of temperature and present the resulting heats of adsorption for both methane and hydrogen.

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

    NASA Astrophysics Data System (ADS)

    Sarker, M. R. I.; Saha, Manabendra; Beg, R. A.

    2016-07-01

    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.

  2. Direct electron heating and current drive with fast waves in DIII-D

    SciTech Connect

    Pinsker, R.I.; Petty, C.C.; Callis, R.W.; Cary, W.P.; Chiu, S.C.; Freeman, R.L.; deGrassie, J.S.; Harvey, R.W.; Luce, T.C.; Mayberry, M.J.; Prater, R.; Porkolab, M.; Bonoli, P.T.; Baity, F.W.; Goulding, R.H.; Hoffmann, D.J.; James, R.A.; Kawashima, H.

    1992-09-01

    Experiments on the DIII-D tokamak have been performed to evaluate noninductive current drive with direct electron absorption of the fast Alfven wave (FW) in the ion cyclotron range of frequencies. These experiments have employed a 2 MW 60 NM transmitter connected to a four-element toroidally phased array of loop antennas located at the outside midplane of the DIII-D vacuum vessel. Efficient direct electron heating was obtained with (0, {pi}, 0, {pi}) antenna phasing; H-mode confinement was obtained with direct electron absorption of the fast wave as the sole source of auxiliary heating. Current drive experiments were performed with (0,{pi}/2,{pi},3{pi}/2) antenna phasing at fast wave power levels up to 1.2 MW. Preheating with 60 GHz ECH was used to increase the single-pass absorption of the fast wave with a directive spectrum. When the fast wave is lunched in the direction that aids the inductively driven current (co-current drive), up to 40% of the 0.4 MA plasma current is sustained noninductively. Counter-current drive strongly affects the sawtoothing behavior, and results in highly peaked electron temperature profiles (T{sub e}(0) {approx_lt} 6 keV) but much smaller driven currents.

  3. Direct electron heating and current drive with fast waves in DIII-D

    SciTech Connect

    Pinsker, R.I.; Petty, C.C.; Callis, R.W.; Cary, W.P.; Chiu, S.C.; Freeman, R.L.; deGrassie, J.S.; Harvey, R.W.; Luce, T.C.; Mayberry, M.J.; Prater, R. ); Porkolab, M.; Bonoli, P.T. ); Baity, F.W.; Goulding, R.H.; Hoffmann, D.J. ); James, R.A. (Lawrence Livermor

    1992-09-01

    Experiments on the DIII-D tokamak have been performed to evaluate noninductive current drive with direct electron absorption of the fast Alfven wave (FW) in the ion cyclotron range of frequencies. These experiments have employed a 2 MW 60 NM transmitter connected to a four-element toroidally phased array of loop antennas located at the outside midplane of the DIII-D vacuum vessel. Efficient direct electron heating was obtained with (0, [pi], 0, [pi]) antenna phasing; H-mode confinement was obtained with direct electron absorption of the fast wave as the sole source of auxiliary heating. Current drive experiments were performed with (0,[pi]/2,[pi],3[pi]/2) antenna phasing at fast wave power levels up to 1.2 MW. Preheating with 60 GHz ECH was used to increase the single-pass absorption of the fast wave with a directive spectrum. When the fast wave is lunched in the direction that aids the inductively driven current (co-current drive), up to 40% of the 0.4 MA plasma current is sustained noninductively. Counter-current drive strongly affects the sawtoothing behavior, and results in highly peaked electron temperature profiles (T[sub e](0) [approx lt] 6 keV) but much smaller driven currents.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Direct electron heating by 60 MHz fast waves on DIII-D

    SciTech Connect

    Petty, C.C.; Pinsker, R.I.; Mayberry, M.J.; Chiu, S.C.; Luce, T.C.; Prater, R. ); Porkolab, M.; Bonoli, P.T. . Plasma Fusion Center); de Haas, J.C.M.; James, R.A. ); Baity, F.W.; Goulding, R.H.; Hoffman, D.J. (Oak Ridge National Lab., TN (United St

    1991-10-01

    Efficient direct electron heating by fast waves has been observed on the DIII-D tokamak. A four strap antenna with (0,{pi},0,{pi}) phasing launched up to 1.6 MW of fast wave power with {vert bar}n{sub {parallel}}{vert bar} {approx} 11. This {vert bar}n{sub {parallel}}{vert bar} is suitable for strong electron interaction in ohmic target plasmas (T{sub e} {le} 2 keV). Ion cyclotron absorption was minimized by keeping the hydrogen fraction low ({lt}3%) in deuterium discharges and by operating at high ion cyclotron harmonics ({omega} = 4{Omega}{sub H} = 8{Omega}{sub D} at 1T). The fast wave electron heating was weak for central electron temperatures below 1 keV, but improved substantially with increasing T{sub e}. Although linear theory predicts a strong inverse magnetic field scaling of the first pass absorption, the measured fast-wave heating efficiency was independent of magnetic field. Multiple pass absorption of the fast waves appears to be occurring since at 2.1 T nearly 100% efficient plasma heating is observed while the calculated first pass absorption is 6% to 8%. The central electron temperature during fast wave heating also increased with magnetic field. The improved electron heating at higher magnetic fields may be due in part to a peaking of the ohmic plasma current and the ohmic electron temperature profiles. Centrally peaked deposition profiles were measured by modulating the fast wave power at 10 Hz and observing the local electron temperature response across the plasma. 11 refs., 10 figs.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Hydrothermal Redox Dynamics in the Central Crater at White Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Win, N. A.; Oze, C.

    2014-12-01

    The White Island stratovolcano of New Zealand has an active shallow S-rich hydrothermal system present in the Central Crater. In this hydrothermal system, subsurface Fe-rich mineralization is prevalent in the unconsolidated volcaniclastic sediments. Development of these laterally coherent Fe-rich layers may alter the fluid and gas flow and mineralization dynamics of the hydrothermal system. Here we assess the redox chemistry and pathways leading to the formation of the subsurface Fe-rich layer(s). Based on fluid chemistry, mineralogical analyses and geochemical modeling, the subsurface Fe-rich layers are mainly composed of jarosite and goethite and form at the interface between the atmospheric (O2-rich) and hydrothermal (reduced) systems. Cyclic mixing of volcanically-related fluid/gas pulses and precipitation is conducive to both jarosite and goethite forming in the same layer. Macroscopically, the formation of these Fe-rich layers decreases the permeability and porosity in the crater fill directly affecting fluid and gas flux and heat released throughout sections of the crater. Microbial communities are present in the Fe-rich layers, but how and to what extent microbial activity is interacting within these layers requires further investigation. Overall, the subsurface Fe-rich layers present at White Island represent a confined and small scale version (a few centimeters) of a redox interface potentially applicable to larger hydrothermal and ore forming systems.

  15. 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.

  16. 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.

  17. Reaction of thermal laminar boundary layer to stepwise change in heat conduction and specific heat of the wall in the direction of flow

    SciTech Connect

    Sapelkin, V.A.; Sergeev, Yu.V.

    1988-03-01

    The conjugate problem of nonsteady heat transfer between a laminar boundary layer with a pressure gradient and a wall with stepwise change in its thermophysical properties (heat conduction and volume specific heat) in the longitudinal direction is solved by the finite-difference method for an incompressible liquid and a wall whose internal surface is heat insulated. The results of the calculations show that the reaction of the thermal boundary layer to discontinuity in the thermophysical properties of the wall is nonunique and multi-parametric. Since these parameters determine the thickness of the thermal boundary layer it may be concluded that thin thermal boundary layers react more strongly than thick layers.

  18. 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.

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

    DOE PAGESBeta

    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.; et al

    2016-07-07

    Here, 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.more » 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.« less

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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 SiO2 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.

  1. 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.

  2. Reactive transport modeling of hydrothermal circulation in oceanic crust: effect of anhydrite precipitation on the dynamics of submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Yang, J.

    2009-12-01

    Hydrothermal fluid circulation represents an extremely efficient mechanism for the exchange of heat and matter between seawater and oceanic crust. Precipitation and dissolution of minerals associated with hydrothermal flow at ridge axes can alter the crustal porosity and permeability and hence influence the dynamics of hydrothermal systems. In this study, a fully coupled fluid flow, heat transfer and reactive mass transport model was developed using TOUGHREACT to evaluate the role of mineral precipitation and dissolution on the evolution of hydrothermal flow systems, with a particular attention focused on anhydrite precipitation upon heating of seawater in recharge zones and the resultant change in the crustal porosity and permeability. A series of numerical case studies were carried out to assess the effect of temperature and aqueous phase inflow concentrations on the reactive geochemical system. The impact of chemically induced porosity and permeability changes on the dynamics of hydrothermal systems was also addressed.

  3. Experimental investigation of single carbon compounds under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Seewald, Jeffrey S.; Zolotov, Mikhail Yu.; McCollom, Thomas

    2006-01-01

    The speciation of carbon in subseafloor hydrothermal systems has direct implications for the maintenance of life in present-day vent ecosystems and possibly the origin of life on early Earth. Carbon monoxide is of particular interest because it represents a key reactant during the abiotic synthesis of reduced carbon compounds via Fischer-Tropsch-type processes. Laboratory experiments were conducted to constrain reactions that regulate the speciation of aqueous single carbon species under hydrothermal conditions and determine kinetic parameters for the oxidation of CO according to the water water-gas shift reaction (CO 2 + H 2 = CO + H 2O). Aqueous fluids containing added CO 2, CO, HCOOH, NaHCO 3, NaHCOO, and H 2 were heated at 150, 200, and 300 °C and 350 bar in flexible-cell hydrothermal apparatus, and the abundances of carbon compounds was monitored as a function of time. Variations in fluid chemistry suggest that the reduction of CO 2 to CH 3OH under aqueous conditions occurs via a stepwise process that involves the formation of HCOOH, CO, and possibly CH 2O, as reaction intermediaries. Kinetic barriers that inhibit the reduction of CH 3OH to CH 4 allow the accumulation of reaction intermediaries in solution at high concentrations regulated by metastable thermodynamic equilibrium. Reaction of CO 2 to CO involves a two-step process in which CO 2 initially undergoes a reduction step to HCOOH which subsequently dehydrates to form CO. Both reactions proceed readily in either direction. A preexponential factor of 1.35 × 10 6 s -1 and an activation energy of 102 kJ/mol were retrieved from the experimental results for the oxidation of CO to CO 2. Reaction rates amongst single carbon compounds during the experiments suggest that ΣCO 2 (CO 2 + HCO 3- + CO 32-), CO, ΣHCOOH (HCOOH + HCOO -), and CH 3OH may reach states of redox-dependent metastable thermodynamic equilibrium in subseafloor and other hydrothermal systems. The abundance of CO under equilibrium conditions

  4. Direct numerical simulation of flow and heat transfer in a turbine cascade with incoming wakes

    NASA Astrophysics Data System (ADS)

    Wissink, Jan G.; Rodi, Wolfgang

    2006-12-01

    Direct numerical simulations (DNS) of flow in a turbine cascade with heat transfer have been performed. The set-up of the simulations was chosen in close accordance with previous experiments. Three of the experimental situations were simulated: one without free-stream turbulence and two with periodically incoming wakes of different frequency and with different levels of background fluctuation. Hence, the calculations allow us to study the influence of impinging wakes and background fluctuations on the development of the boundary layers and the local Nusselt number along the surfaces of the heated blade. Along the suction side, the pressure gradient is first favourable and then turns adverse near the trailing edge and the boundary layer remains laminar for the case without free-stream turbulence with the Nusselt number showing the typical decay from the leading to the trailing edge. With periodic wakes and background turbulence, transition occurs when the pressure gradient turns adverse, but intermittency persists so that the boundary layer is not fully turbulent when the trailing edge is reached. In this region, the heat transfer is increased significantly by an amount comparable to that found in the experiments. In the pre-transitional region with favourable pressure gradient, the flow acceleration stretches the free-stream vortices, aligning their axis with the flow direction, thereby forming streamwise vortical structures. These increase the laminar heat transfer in this region by 20 30%, which is, however, much less than observed in the experiments. On the pressure side, the pressure gradient is favourable along the entire blade so that the boundary layer remains laminar. Here, the wakes, through their impingement, also generate streamwise vortical structures which, because of the low convection speed on this side, have a very long lifetime compared to the structures along the suction side. Also these structures increase the laminar heat transfer by about 30

  5. 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).

  6. Direct observation of heat dissipation in individual suspended carbon nanotubes using a two-laser technique

    NASA Astrophysics Data System (ADS)

    Hsu, I.-Kai; Pettes, Michael T.; Aykol, Mehmet; Chang, Chia-Chi; Hung, Wei-Hsuan; Theiss, Jesse; Shi, Li; Cronin, Stephen B.

    2011-08-01

    A two-laser technique is used to investigate heat spreading along individual single walled carbon nanotube (SWCNT) bundles in vacuum and air environments. A 532 nm laser focused on the center of a suspended SWCNT bundle is used as a local heat source, and a 633 nm laser is used to measure the spatial temperature profile along the SWCNT bundle by monitoring the G band downshifts in the Raman spectra. A constant temperature gradient is observed when the SWCNT bundle is irradiated in vacuum, giving direct evidence of diffusive transport of the phonons probed by the Raman laser. In air, however, we observe an exponentially decaying temperature profile with a decay length of about 7 μm, due to heat dissipation from the SWCNT bundle to the surrounding gas molecules. The thermal conductivity of the suspended carbon nanotube (CNT) is determined from its electrical heating temperature profile as measured in vacuum and the nanotube bundle diameter measured via transmission electron microscopy. Based on the exponential decay curves measured in three different CNTs in air, the heat transfer coefficient between the SWCNTs and the surrounding air molecules is found to range from 1.5 × 103 to 7.9 × 104 W/m2 K, which is smaller than the 1 × 105 W/m2 K thermal boundary conductance value calculated using the kinetic theory of gases. This measurement is insensitive to the thermal contact resistance, as no temperature drops occur at the ends of the nanotube. It is also insensitive to errors in the calibration of the G band temperature coefficient. The optical absorption is also obtained from these results and is on the order of 10-5.

  7. 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.

  8. 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.

  9. 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.

  10. 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.