Science.gov

Sample records for heat energy flow

  1. Heat transfer and flow in solar energy and bioenergy systems

    NASA Astrophysics Data System (ADS)

    Xu, Ben

    The demand for clean and environmentally benign energy resources has been a great concern in the last two decades. To alleviate the associated environmental problems, reduction of the use of fossil fuels by developing more cost-effective renewable energy technologies becomes more and more significant. Among various types of renewable energy sources, solar energy and bioenergy take a great proportion. This dissertation focuses on the heat transfer and flow in solar energy and bioenergy systems, specifically for Thermal Energy Storage (TES) systems in Concentrated Solar Power (CSP) plants and open-channel algal culture raceways for biofuel production. The first part of this dissertation is the discussion about mathematical modeling, numerical simulation and experimental investigation of solar TES system. First of all, in order to accurately and efficiently simulate the conjugate heat transfer between Heat Transfer Fluid (HTF) and filler material in four different solid-fluid TES configurations, formulas of an e?ective heat transfer coe?cient were theoretically developed and presented by extending the validity of Lumped Capacitance Method (LCM) to large Biot number, as well as verifications/validations to this simplified model. Secondly, to provide design guidelines for TES system in CSP plant using Phase Change Materials (PCM), a general storage tank volume sizing strategy and an energy storage startup strategy were proposed using the enthalpy-based 1D transient model. Then experimental investigations were conducted to explore a novel thermal storage material. The thermal storage performances were also compared between this novel storage material and concrete at a temperature range from 400 °C to 500 °C. It is recommended to apply this novel thermal storage material to replace concrete at high operating temperatures in sensible heat TES systems. The second part of this dissertation mainly focuses on the numerical and experimental study of an open-channel algae

  2. A Variable Refrigerant Flow Heat Pump Computer Model in EnergyPlus

    SciTech Connect

    Raustad, Richard A.

    2013-01-01

    This paper provides an overview of the variable refrigerant flow heat pump computer model included with the Department of Energy's EnergyPlusTM whole-building energy simulation software. The mathematical model for a variable refrigerant flow heat pump operating in cooling or heating mode, and a detailed model for the variable refrigerant flow direct-expansion (DX) cooling coil are described in detail.

  3. Energy deposition, heat flow, and rapid solidification during laser and electron beam irradiation of materials

    SciTech Connect

    White, C.W.; Aziz, M.J.

    1985-10-01

    The fundamentals of energy deposition, heat flow, and rapid solidification during energy deposition from lasers and electron beams is reviewed. Emphasis is placed on the deposition of energy from pulsed sources (10 to 100 ns pulse duration time) in order to achieve high heating and cooling rates (10/sup 8/ to 10/sup 10/ /sup 0/C/s) in the near surface region. The response of both metals and semiconductors to pulsed energy deposition is considered. Guidelines are presented for the choice of energy source, wavelength, and pulse duration time.

  4. Inter-phase heat transfer and energy coupling in turbulent dispersed multiphase flows

    NASA Astrophysics Data System (ADS)

    Ling, Y.; Balachandar, S.; Parmar, M.

    2016-03-01

    The present paper addresses important fundamental issues of inter-phase heat transfer and energy coupling in turbulent dispersed multiphase flows through scaling analysis. In typical point-particle or two-fluid approaches, the fluid motion and convective heat transfer at the particle scale are not resolved and the momentum and energy coupling between fluid and particles are provided by proper closure models. By examining the kinetic energy transfer due to the coupling forces from the macroscale to microscale fluid motion, closure models are obtained for the contributions of the coupling forces to the energy coupling. Due to the inviscid origin of the added-mass force, its contribution to the microscale kinetic energy does not contribute to dissipative transfer to fluid internal energy as was done by the quasi-steady force. Time scale analysis shows that when the particle is larger than a critical diameter, the diffusive-unsteady kernel decays at a time scale that is smaller than the Kolmogorov time scale. As a result, the computationally costly Basset-like integral form of diffusive-unsteady heat transfer can be simplified to a non-integral form. Conventionally, the fluid-to-particle volumetric heat capacity ratio is used to evaluate the relative importance of the unsteady heat transfer to the energy balance of the particles. Therefore, for gas-particle flows, where the fluid-to-particle volumetric heat capacity ratio is small, unsteady heat transfer is usually ignored. However, the present scaling analysis shows that for small fluid-to-particle volumetric heat capacity ratio, the importance of the unsteady heat transfer actually depends on the ratio between the particle size and the Kolmogorov scale. Furthermore, the particle mass loading multiplied by the heat capacity ratio is usually used to estimate the importance of the thermal two-way coupling effect. Through scaling argument, improved estimates are established for the energy coupling parameters of each

  5. Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems

    SciTech Connect

    Hong, Tainzhen; Liu, Xaiobing

    2009-11-01

    With the current movement toward net zero energy buildings, many technologies are promoted with emphasis on their superior energy efficiency. The variable refrigerant flow (VRF) and ground source heat pump (GSHP) systems are probably the most competitive technologies among these. However, there are few studies reporting the energy efficiency of VRF systems compared with GSHP systems. In this article, a preliminary comparison of energy efficiency between the air-source VRF and GSHP systems is presented. The computer simulation results show that GSHP system is more energy efficient than the air-source VRF system for conditioning a small office building in two selected US climates. In general, GSHP system is more energy efficient than the air-source VRV system, especially when the building has significant heating loads. For buildings with less heating loads, the GSHP system could still perform better than the air-source VRF system in terms of energy efficiency, but the resulting energy savings may be marginal.

  6. Vortex shedding induced energy harvesting from piezoelectric materials in heating, ventilation and air conditioning flows

    NASA Astrophysics Data System (ADS)

    Weinstein, L. A.; Cacan, M. R.; So, P. M.; Wright, P. K.

    2012-04-01

    A cantilevered piezoelectric beam is excited in a heating, ventilation and air conditioning (HVAC) flow. This excitation is amplified by the interactions between (a) an aerodynamic fin attached at the end of the piezoelectric cantilever and (b) the vortex shedding downstream from a bluff body placed in the air flow ahead of the fin/cantilever assembly. The positioning of small weights along the fin enables tuning of the energy harvester to operate at resonance for flow velocities from 2 to 5 m s-1, which are characteristic of HVAC ducts. In a 15 cm diameter air duct, power generation of 200 μW for a flow speed of 2.5 m s-1 and power generation of 3 mW for a flow speed of 5 m s-1 was achieved. These power outputs are sufficient to power a wireless sensor node for HVAC monitoring systems or other sensors for smart building technology.

  7. Nanofluid heat transfer under mixed convection flow in a tube for solar thermal energy applications.

    PubMed

    Sekhar, Y Raja; Sharma, K V; Kamal, Subhash

    2016-05-01

    The solar flat plate collector operating under different convective modes has low efficiency for energy conversion. The energy absorbed by the working fluid in the collector system and its heat transfer characteristics vary with solar insolation and mass flow rate. The performance of the system is improved by reducing the losses from the collector. Various passive methods have been devised to aid energy absorption by the working fluid. Also, working fluids are modified using nanoparticles to improve the thermal properties of the fluid. In the present work, simulation and experimental studies are undertaken for pipe flow at constant heat flux boundary condition in the mixed convection mode. The working fluid at low Reynolds number in the mixed laminar flow range is undertaken with water in thermosyphon mode for different inclination angles of the tube. Local and average coefficients are determined experimentally and compared with theoretical values for water-based Al2O3 nanofluids. The results show an enhancement in heat transfer in the experimental range with Rayleigh number at higher inclinations of the collector tube for water and nanofluids.

  8. Magnetic Heat Pump Containing Flow Diverters

    NASA Technical Reports Server (NTRS)

    Howard, Frank S.

    1995-01-01

    Proposed magnetic heat pump contains flow diverters for suppression of undesired flows. If left unchecked, undesired flows mix substantial amounts of partially heated and partially cooled portions of working fluid, effectively causing leakage of heat from heated side to cooled side. By reducing leakage of heat, flow diverters increase energy efficiency of magnetic heat pump, potentially offering efficiency greater than compressor-driven refrigerator.

  9. Impact of Groundwater Flow and Energy Load on Multiple Borehole Heat Exchangers.

    PubMed

    Dehkordi, S Emad; Schincariol, Robert A; Olofsson, Bo

    2015-01-01

    The effect of array configuration, that is, number, layout, and spacing, on the performance of multiple borehole heat exchangers (BHEs) is generally known under the assumption of fully conductive transport. The effect of groundwater flow on BHE performance is also well established, but most commonly for single BHEs. In multiple-BHE systems the effect of groundwater advection can be more complicated due to the induced thermal interference between the boreholes. To ascertain the influence of groundwater flow and borehole arrangement, this study investigates single- and multi-BHE systems of various configurations. Moreover, the influence of energy load balance is also examined. The results from corresponding cases with and without groundwater flow as well as balanced and unbalanced energy loads are cross-compared. The groundwater flux value, 10(-7) m/s, is chosen based on the findings of previous studies on groundwater flow interaction with BHEs and thermal response tests. It is observed that multi-BHE systems with balanced loads are less sensitive to array configuration attributes and groundwater flow, in the long-term. Conversely, multi-BHE systems with unbalanced loads are influenced by borehole array configuration as well as groundwater flow; these effects become more pronounced with time, unlike when the load is balanced. Groundwater flow has more influence on stabilizing loop temperatures, compared to array characteristics. Although borehole thermal energy storage (BTES) systems have a balanced energy load function, preliminary investigation on their efficiency shows a negative impact by groundwater which is due to their dependency on high temperature gradients between the boreholes and surroundings.

  10. A Thermally-Regenerative Ammonia-Based Flow Battery for Electrical Energy Recovery from Waste Heat.

    PubMed

    Zhu, Xiuping; Rahimi, Mohammad; Gorski, Christopher A; Logan, Bruce

    2016-04-21

    Large amounts of low-grade waste heat (temperatures <130 °C) are released during many industrial, geothermal, and solar-based processes. Using thermally-regenerative ammonia solutions, low-grade thermal energy can be converted to electricity in battery systems. To improve reactor efficiency, a compact, ammonia-based flow battery (AFB) was developed and tested at different solution concentrations, flow rates, cell pairs, and circuit connections. The AFB achieved a maximum power density of 45 W m(-2) (15 kW m(-3) ) and an energy density of 1260 Wh manolyte (-3) , with a thermal energy efficiency of 0.7 % (5 % relative to the Carnot efficiency). The power and energy densities of the AFB were greater than those previously reported for thermoelectrochemical and salinity-gradient technologies, and the voltage or current could be increased using stacked cells. These results demonstrated that an ammonia-based flow battery is a promising technology to convert low-grade thermal energy to electricity.

  11. Heat and Mass Transfer in Unsteady Rotating Fluid Flow with Binary Chemical Reaction and Activation Energy

    PubMed Central

    Awad, Faiz G.; Motsa, Sandile; Khumalo, Melusi

    2014-01-01

    In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous fluid in presence of binary chemical reaction and Arrhenius activation energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations. PMID:25250830

  12. Modeling of dissociation and energy transfer in shock-heated nitrogen flows

    NASA Astrophysics Data System (ADS)

    Munafò, A.; Liu, Y.; Panesi, M.

    2015-12-01

    This work addresses the modeling of dissociation and energy transfer processes in shock heated nitrogen flows by means of the maximum entropy linear model and a newly proposed hybrid bin vibrational collisional model. Both models aim at overcoming two of the main limitations of the state of the art non-equilibrium models: (i) the assumption of equilibrium between rotational and translational energy modes of the molecules and (ii) the reliance on the quasi-steady-state distribution for the description of the population of the internal levels. The formulation of the coarse-grained models is based on grouping the energy levels into bins, where the population is assumed to follow a Maxwell-Boltzmann distribution at its own temperature. Different grouping strategies are investigated. Following the maximum entropy principle, the governing equations are obtained by taking the zeroth and first-order moments of the rovibrational master equations. The accuracy of the proposed models is tested against the rovibrational master equation solution for both flow quantities and population distributions. Calculations performed for free-stream velocities ranging from 5 km/s to 10 km/s demonstrate that dissociation can be accurately predicted by using only 2-3 bins. It is also shown that a multi-temperature approach leads to an under-prediction of dissociation, due to the inability of the former to account for the faster excitation of high-lying vibrational states.

  13. Modeling of dissociation and energy transfer in shock-heated nitrogen flows

    SciTech Connect

    Munafò, A.; Liu, Y.; Panesi, M.

    2015-12-15

    This work addresses the modeling of dissociation and energy transfer processes in shock heated nitrogen flows by means of the maximum entropy linear model and a newly proposed hybrid bin vibrational collisional model. Both models aim at overcoming two of the main limitations of the state of the art non-equilibrium models: (i) the assumption of equilibrium between rotational and translational energy modes of the molecules and (ii) the reliance on the quasi-steady-state distribution for the description of the population of the internal levels. The formulation of the coarse-grained models is based on grouping the energy levels into bins, where the population is assumed to follow a Maxwell-Boltzmann distribution at its own temperature. Different grouping strategies are investigated. Following the maximum entropy principle, the governing equations are obtained by taking the zeroth and first-order moments of the rovibrational master equations. The accuracy of the proposed models is tested against the rovibrational master equation solution for both flow quantities and population distributions. Calculations performed for free-stream velocities ranging from 5 km/s to 10 km/s demonstrate that dissociation can be accurately predicted by using only 2-3 bins. It is also shown that a multi-temperature approach leads to an under-prediction of dissociation, due to the inability of the former to account for the faster excitation of high-lying vibrational states.

  14. Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump and Heat Recovery Equipment in EnergyPlus

    SciTech Connect

    Raustad, Richard; Nigusse, Bereket; Domitrovic, Ron

    2013-09-30

    The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow heat pump (VRF HP) manufacturers, provided a detailed computer model for a VRF HP system in the United States Department of Energy's (U.S. DOE) EnergyPlus? building energy simulation tool. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance to both the manufacturer's data and that predicted by the use of this new model through computer simulation. The project goal was to investigate the complex interactions of VRF HP systems from an HVAC system perspective, and explore the operational characteristics of this HVAC system type within a laboratory and real world building environment. Detailed laboratory testing of this advanced HVAC system provided invaluable performance information which does not currently exist in the form required for proper analysis and modeling. This information will also be useful for developing and/or supporting test standards for VRF HP systems. Field testing VRF HP systems also provided performance and operational information pertaining to installation, system configuration, and operational controls. Information collected from both laboratory and field tests were then used to create and validate the VRF HP system computer model which, in turn, provides architects, engineers, and building owners the confidence necessary to accurately and reliably perform building energy simulations. This new VRF HP model is available in the current public release version of DOE?s EnergyPlus software and can be used to investigate building energy use in both new and existing building stock. The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air enthalpy method

  15. Compare Energy Use in Variable Refrigerant Flow Heat Pumps Field Demonstration and Computer Model

    SciTech Connect

    Sharma, Chandan; Raustad, Richard

    2013-07-01

    Variable Refrigerant Flow (VRF) heat pumps are often regarded as energy efficient air-conditioning systems which offer electricity savings as well as reduction in peak electric demand while providing improved individual zone setpoint control. One of the key advantages of VRF systems is minimal duct losses which provide significant reduction in energy use and duct space. However, there is limited data available to show their actual performance in the field. Since VRF systems are increasingly gaining market share in the US, it is highly desirable to have more actual field performance data of these systems. An effort was made in this direction to monitor VRF system performance over an extended period of time in a US national lab test facility. Due to increasing demand by the energy modeling community, an empirical model to simulate VRF systems was implemented in the building simulation program EnergyPlus. This paper presents the comparison of energy consumption as measured in the national lab and as predicted by the program. For increased accuracy in the comparison, a customized weather file was created by using measured outdoor temperature and relative humidity at the test facility. Other inputs to the model included building construction, VRF system model based on lab measured performance, occupancy of the building, lighting/plug loads, and thermostat set-points etc. Infiltration model inputs were adjusted in the beginning to tune the computer model and then subsequent field measurements were compared to the simulation results. Differences between the computer model results and actual field measurements are discussed. The computer generated VRF performance closely resembled the field measurements.

  16. Planetary heat flow measurements.

    PubMed

    Hagermann, Axel

    2005-12-15

    The year 2005 marks the 35th anniversary of the Apollo 13 mission, probably the most successful failure in the history of manned spaceflight. Naturally, Apollo 13's scientific payload is far less known than the spectacular accident and subsequent rescue of its crew. Among other instruments, it carried the first instrument designed to measure the flux of heat on a planetary body other than Earth. The year 2005 also should have marked the launch of the Japanese LUNAR-A mission, and ESA's Rosetta mission is slowly approaching comet Churyumov-Gerasimenko. Both missions carry penetrators to study the heat flow from their target bodies. What is so interesting about planetary heat flow? What can we learn from it and how do we measure it?Not only the Sun, but all planets in the Solar System are essentially heat engines. Various heat sources or heat reservoirs drive intrinsic and surface processes, causing 'dead balls of rock, ice or gas' to evolve dynamically over time, driving convection that powers tectonic processes and spawns magnetic fields. The heat flow constrains models of the thermal evolution of a planet and also its composition because it provides an upper limit for the bulk abundance of radioactive elements. On Earth, the global variation of heat flow also reflects the tectonic activity: heat flow increases towards the young ocean ridges, whereas it is rather low on the old continental shields. It is not surprising that surface heat flow measurements, or even estimates, where performed, contributed greatly to our understanding of what happens inside the planets. In this article, I will review the results and the methods used in past heat flow measurements and speculate on the targets and design of future experiments.

  17. Heat flow in Oklahoma

    NASA Astrophysics Data System (ADS)

    Cranganu, Constantin

    Twenty new heat flow values are incorporated, along with 40 previously published data, into a heat flow map of Oklahoma. The new heat flow data were estimated using previous temperature measurements in boreholes made by American Petroleum Institute researchers and 1,498 thermal conductivity measurements on drill cuttings. The mean of 20 average thermal gradients is 30.50sp°C/km. In general, thermal gradients increase from SW (14.11sp°C/km) to NE (42.24sp°C/km). The range of 1,498 in situ thermal conductivity measurements (after corrections for anisotropy, in situ temperature, and porosity) is 0.90-6.1 W/m-K; the average is 1.68 W/m-K. Estimated near-surface heat flow (±20%) at 20 new sites in Oklahoma varies between 22 ± 4 mW/msp2 and 86 ± 17 mW/msp2; the average is 50 mW/msp2. Twenty-seven new heat-generation estimates, along with 22 previously published data, are used to create a heat generation map of Oklahoma. The range of heat production estimates is 1.1-3.5 muW/msp3, with an average of 2.5 muW/msp3. The heat flow regime in Oklahoma is primarily conductive in nature, except for a zone in northeast. Transient effects due to sedimentary processes and metamorphic/igneous activity, as well as past climatic changes, do not significantly influence the thermal state of the Oklahoma crust. Heat flow near the margins of the Arkoma and Anadarko Basins may be depressed or elevated by 5-13 mW/msp2 by refraction of heat from sedimentary rocks of relatively low thermal conductivity (1-2 W/m-K) into crystalline basement rocks of relatively high thermal conductivity (˜3-4 W/m-K). The heat generation-heat flow relationship shows a modest correlation. The relatively high heat flow (˜70-80 mW/msp2) in part of northeastern Oklahoma suggests that the thermal regime there may be perturbed by regional groundwater flow originating in the fractured outcrops of the Arbuckle-Simpson aquifer in the Arbuckle Mountains.

  18. A stock-flow consistent input-output model with applications to energy price shocks, interest rates, and heat emissions

    NASA Astrophysics Data System (ADS)

    Berg, Matthew; Hartley, Brian; Richters, Oliver

    2015-01-01

    By synthesizing stock-flow consistent models, input-output models, and aspects of ecological macroeconomics, a method is developed to simultaneously model monetary flows through the financial system, flows of produced goods and services through the real economy, and flows of physical materials through the natural environment. This paper highlights the linkages between the physical environment and the economic system by emphasizing the role of the energy industry. A conceptual model is developed in general form with an arbitrary number of sectors, while emphasizing connections with the agent-based, econophysics, and complexity economics literature. First, we use the model to challenge claims that 0% interest rates are a necessary condition for a stationary economy and conduct a stability analysis within the parameter space of interest rates and consumption parameters of an economy in stock-flow equilibrium. Second, we analyze the role of energy price shocks in contributing to recessions, incorporating several propagation and amplification mechanisms. Third, implied heat emissions from energy conversion and the effect of anthropogenic heat flux on climate change are considered in light of a minimal single-layer atmosphere climate model, although the model is only implicitly, not explicitly, linked to the economic model.

  19. Cafeteria diet induce changes in blood flow that are more related with heat dissipation than energy accretion

    PubMed Central

    Sabater, David; Agnelli, Silvia; Arriarán, Sofía; Romero, María del Mar; Fernández-López, José Antonio; Alemany, Marià

    2016-01-01

    Background. A “cafeteria” diet is a self-selected high-fat diet, providing an excess of energy, which can induce obesity. Excess of lipids in the diet hampers glucose utilization eliciting insulin resistance, which, further limits amino acid oxidation for energy. Methods. Male Wistar rats were exposed for a month to “cafeteria” diet. Rats were cannulated and fluorescent microspheres were used to determine blood flow. Results. Exposure to the cafeteria diet did not change cardiac output, but there was a marked shift in organ irrigation. Skin blood flow decreased to compensate increases in lungs and heart. Blood flow through adipose tissue tended to increase in relation to controls, but was considerably increased in brown adipose tissue (on a weight basis). Discussion. The results suggest that the cafeteria diet-induced changes were related to heat transfer and disposal. PMID:27547590

  20. Experimental Analysis of Heat Flux to a Blunt Body in Hypersonic Flow with Upstream Laser Energy Deposition — Preliminary Results

    NASA Astrophysics Data System (ADS)

    Salvador, I. I.; Minucci, M. A. S.; Toro, P. G. P.; Oliveira, A. C.; Channes, J. B.; Myrabo, L. N.; Nagamatsu, H. T.

    2006-05-01

    Due to high heat transfer rates in hypersonic flight and its consequent necessity of prohibitively massive thermal protection system, new methods of flow control are required to enable flight in such regimes. Here arises the Direct Energy Air Spike concept, where electromagnetic energy (laser/microwaves) is focalized upstream of the model causing the breakdown of the air and the generation of a Laser Supported Detonation wave which diverts the incoming stream parabolically. In this preliminary work, the heat transfer rates to the surface of a blunt body, downstream the laser induced shock wave, were qualitatively measured and compared with the results without the DEAS. These measurements were conducted with the use of fast response coaxial thermocouples and piezoelectric pressure transducers installed on the surface of the model in the 0.30m IEAv's T2 Hypersonic Shock Tunnel. The laser energy was supplied by a CO2 TEA Laser.

  1. Venus Heat Flow Instrument Development

    NASA Astrophysics Data System (ADS)

    Pauken, M.; Smith, K.; Sujittosakul, S.; Li, B.; Firdosy, S.; Smrekar, S.; Morgan, P.

    2016-10-01

    A heat flux measurement instrument is being developed to determine the heat flow through the Venus surface. Heat flow measurement provides data for distinguishing between various hypotheses of planetary evolution.

  2. Enceladus' Enigmatic Heat Flow

    NASA Astrophysics Data System (ADS)

    Howett, C.; Spencer, J. R.; Spencer, D.; Verbiscer, A.; Hurford, T.; Segura, M.

    2013-12-01

    Accurate knowledge of Enceladus' heat flow is important because it provides a vital constraint on Enceladus' tidal dissipation mechanisms, orbital evolution, and the physical processes that generate the plumes. In 2011 we published an estimate of the current heat flow from Enceladus' active south polar terrain: 15.8 +/- 3.1 GW (Howett et al., 2011). This value was calculated by first estimating by modeling, and then removing, the passive component from 17 to 1000 micron observations made of the entire south polar terrain by Cassini's Composite Infrared Spectrometer (CIRS). The heat flow was then directly calculated from the residual, assumed endogenic, component. The derived heat flow of 15.8 GW was surprisingly high, about 10 times greater than that predicted by steady-state tidal heating (Meyer and Wisdom, 2007). CIRS has also returned high spatial resolution observations of Enceladus' active south polar terrain. Two separate observations are used: 9 to 16 micron observations taken over nearly the complete south polar terrain and a single 17 to 1000 micron scan over Damascus, Baghdad and Cairo. The shorter wavelength observations are only sensitive to high temperature emission (>70 K), and so longer wavelength observations are required (despite their limited spatial coverage) to estimate the low temperature emission from the stripes. Analysis of these higher resolution observations tells a different story of Enceladus' endogenic heat flow: the preliminary estimate of the heat flow from the active tiger stripes using these observations is 4.2 GW. An additional 0.5 GW must be added to this number to account for the latent heat release by the plumes (Ingersoll and Pankine 2009), giving a total preliminary estimate of 4.9 GW. The discrepancy in these two numbers is significant and we are currently investigating the cause. One possible reason is that there is significantly higher endogenic emission from the regions between the tiger stripes than we currently estimate

  3. Convective heat flow probe

    DOEpatents

    Dunn, J.C.; Hardee, H.C.; Striker, R.P.

    1984-01-09

    A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packet-type seals are provided along the probe above and below the heater pads.

  4. Heat Flow Measurement

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Heat gauges are used to measure heat flow in industrial activities. They must periodically be certified by instruments designed to provide a heat flux measurement standard. CSTAR, a NASA CCDS, and REMTECH have developed a portable heat flux checker/calibrator. The Q-CHEC can be carried to the heat gauge for certification, reducing out of service time for the gauge and eliminating the need for a replacement gauge during certification. It can provide an "end-to-end" check of the instrumentation measurement system or be used as a standalone calibrator. Because Q-CHEC offers on-site capability to detect and eliminate measurement errors, measurements do not have to be repeated, and money is saved.

  5. Lunar heat-flow experiment

    NASA Technical Reports Server (NTRS)

    Langseth, M. G.

    1977-01-01

    The principal components of the experiment were probes, each with twelve thermometers of exceptional accuracy and stability, that recorded temperature variations at the surface and in the regolith down to 2.5 m. The Apollo 15 experiment and the Apollo 17 probes recorded lunar surface and subsurface temperatures. These data provided a unique and valuable history of the interaction of solar energy with lunar surface and the effects of heat flowing from the deep interior out through the surface of the moon. The interpretation of these data resulted in a clearer definition of the thermal and mechanical properties of the upper two meters of lunar regolith, direct measurements of the gradient in mean temperature due to heat flow from the interior and a determination of the heat flow at the Apollo 15 and Apollo 17 sites.

  6. Heat flow in Oklahoma

    SciTech Connect

    Cranganu, C.; Deming, D.

    1996-12-31

    Oklahoma is one area in which terrestrial heat flow data are sparse. The thermal state of the southern mid-continent, however, is a key to understanding several important geologic problems. These include thermal anomalies associated with Paleozoic fluid migrations and the formation of Mississippi Valley-type lead-zinc deposits, the thermal evolution of the Arkoma and Anadarko sedimentary basins, and the history of hydrocarbon generation and overpressuring in the Anadarko Basin. In the late 1920s, the American Petroleum Institute made a set of equilibrium temperature logs in idle oil wells. These temperature data are generally regarded as being high quality, accurate estimates of rock temperature and they cover the entire central part of Oklahoma. Average thermal gradients in the API survey range from 14 to 43 {sup 0}C/km (average 31.2 {sup 0}C/km) over depth intervals that extend from the surface to a an average depth of 961 m. Geothermal gradients decrease from NNE to SSW. The observed change in thermal gradients could be due to a number of factors. The change in thermal gradients could simply reflect changes in lithology and thermal conductivity. Alternatively, the variation in thermal gradients could be indicative of a change in heat flow related perhaps to variations in the concentration of radioactive heat-producing elements in the crust or heat transport by one or more regional groundwater flow systems. We are proceeding to reduce ambiguity in interpretation by estimating heat flow from thermal conductivity measurements on drill cuttings and heat production from available gamma-ray logs which penetrate basement rocks.

  7. Heat flow in Oklahoma

    SciTech Connect

    Cranganu, C.; Deming, D. )

    1996-01-01

    Oklahoma is one area in which terrestrial heat flow data are sparse. The thermal state of the southern mid-continent, however, is a key to understanding several important geologic problems. These include thermal anomalies associated with Paleozoic fluid migrations and the formation of Mississippi Valley-type lead-zinc deposits, the thermal evolution of the Arkoma and Anadarko sedimentary basins, and the history of hydrocarbon generation and overpressuring in the Anadarko Basin. In the late 1920s, the American Petroleum Institute made a set of equilibrium temperature logs in idle oil wells. These temperature data are generally regarded as being high quality, accurate estimates of rock temperature and they cover the entire central part of Oklahoma. Average thermal gradients in the API survey range from 14 to 43 [sup 0]C/km (average 31.2 [sup 0]C/km) over depth intervals that extend from the surface to a an average depth of 961 m. Geothermal gradients decrease from NNE to SSW. The observed change in thermal gradients could be due to a number of factors. The change in thermal gradients could simply reflect changes in lithology and thermal conductivity. Alternatively, the variation in thermal gradients could be indicative of a change in heat flow related perhaps to variations in the concentration of radioactive heat-producing elements in the crust or heat transport by one or more regional groundwater flow systems. We are proceeding to reduce ambiguity in interpretation by estimating heat flow from thermal conductivity measurements on drill cuttings and heat production from available gamma-ray logs which penetrate basement rocks.

  8. Solar Energy: Home Heating.

    ERIC Educational Resources Information Center

    Knapp, Henry H., III

    This module on home heating is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The module…

  9. Solar Energy: Heat Transfer.

    ERIC Educational Resources Information Center

    Knapp, Henry H., III

    This module on heat transfer is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The…

  10. Solar Energy: Heat Storage.

    ERIC Educational Resources Information Center

    Knapp, Henry H., III

    This module on heat storage is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The module…

  11. Map of Io's volcanic heat flow

    NASA Astrophysics Data System (ADS)

    Davies, Ashley Gerard; Veeder, Glenn J.; Matson, Dennis L.; Johnson, Torrence V.

    2015-12-01

    We present a map of Io's volcanic heat flow. Io's high heat flow is a result of intense tidal heating, which generates widespread volcanic activity. The surface expression of ongoing volcanic activity constrains the location and magnitude of tidal dissipation within Io. Tidal heating models place heating either at relatively shallow (aesthenosphere) levels, or deep in the mantle. It was thought that actual tidal heating could be approximated using a combination of these end-member models. Io's volcanic heat flow has now been mapped in sufficient detail to compare with the models. Our maps show that the distribution of heat flow is not matched by current models of deep nor shallow tidal heating, nor by any combination of these two models. We find relatively low heat flow at sub-jovian (0°W) and anti-jovian (180°W) longitudes, at odds with the pure aesthenospheric heating model. Furthermore, there are large swaths of Io's surface where there is poor correlation between the number of hot spots in an area and the power emitted. We have previously accounted for ≈54% of Io's observed heat flow. We now show that Io's anomalously warm poles, possibly the result of heat flow from deep-mantle heating, would yield the ;missing; energy (48 TW) if the polar surfaces are at temperatures of ∼90 K to ∼95 K and cover latitudes above ∼43° to ∼48° respectively. This possibility implies a ratio of deep to shallow heating of about 1:1. However, explaining regional variations in surface volcanic activity requires more detailed modeling of the location and magnitude of the internal tidal dissipation and the consequences of mantle convection and advection within Io. Future model predictions can be compared to our heat flow map.

  12. Heat Pipe Blocks Return Flow

    NASA Technical Reports Server (NTRS)

    Eninger, J. E.

    1982-01-01

    Metal-foil reed valve in conventional slab-wick heat pipe limits heat flow to one direction only. With sink warmer than source, reed is forced closed and fluid returns to source side through annular transfer wick. When this occurs, wick slab on sink side of valve dries out and heat pipe ceases to conduct heat.

  13. HEATS: Thermal Energy Storage

    SciTech Connect

    2012-01-01

    HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

  14. Magnetic heat pump flow director

    NASA Technical Reports Server (NTRS)

    Howard, Frank S. (Inventor)

    1995-01-01

    A fluid flow director is disclosed. The director comprises a handle body and combed-teeth extending from one side of the body. The body can be formed of a clear plastic such as acrylic. The director can be used with heat exchangers such as a magnetic heat pump and can minimize the undesired mixing of fluid flows. The types of heat exchangers can encompass both heat pumps and refrigerators. The director can adjust the fluid flow of liquid or gas along desired flow directions. A method of applying the flow director within a magnetic heat pump application is also disclosed where the comb-teeth portions of the director are inserted into the fluid flow paths of the heat pump.

  15. Temperature and energy deficit in the ground during operation and recovery phases of closed-loop ground source heat pump system: Effect of the groundwater flow

    NASA Astrophysics Data System (ADS)

    Erol, Selcuk; Francois, Bertrand

    2016-04-01

    The advection/dispersion mechanism of the groundwater flow in the ground has a significant effect on a borehole heat exchanger (BHE) to enhance its thermal performance. However, the amount of energy extracted from the ground never disappears and only shifts with the magnitude of the effective thermal velocity in the infinite domain. In this work, we focus on the temperature and the energy balance of the ground in an advection/dispersion dominated heat transfer system during the operation period of a BHE and the subsequent recovery phase when the system is idle. The problem is treated with single BHE and multi-BHEs systems, for different representative geology and different groundwater flow velocity. In order to assess the thermal energy deficit due to heat extraction from the ground, we used the finite line source analytical model, developed recently (Erol et al., 2015) that provides the temperature distributions around the boreholes for discontinuous heat extraction. The model is developed based on the Green's function, which is the solution of heat conduction/advection/dispersion equation in porous media, for discontinuous heat extraction by analytically convoluting rectangular function or pulses in time domain. The results demonstrate the significant positive impact of the groundwater flow for the recovery in terms of temperature deficit at the location of the borehole. However, the total thermal energy deficit is not affected by the groundwater movement. The energy balance of the ground is the same no matter the prevailing heat transfer system, which can be only conduction or advection/dispersion. In addition, the energy balance of the ground is not based on either the duration of the production period operation or of the recovery phase, but depends on the total amount of heat that is extracted and on the bulk volumetric heat capacity of the ground.

  16. Coronal temperatures, heating, and energy flow in a polar region of the sun at solar maximum

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.; Kohl, J. L.; Weiser, H.; Munro, R. H.

    1985-01-01

    The profiles of resonantly scattered Lyman-alpha coronal radiation have been used to determine the hydrogen kinetic temperature from 1.5 to 4 solar radius from the center of the polar region of the corona observed in 1980 at solar maximum. Hydrogen temperatures derived from the line profiles were found to decrease with height from 1.2 million K at r = 1.5 solar radii to 600,000 K at r = 4 solar radius. Comparison of the measured kinetic temperatures with predictions from a semiempirical two-fluid model showed evidence of a small amount of heating or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 solar radius. The widths of the profiles confirmed an upper limit of 110 + or - 15 km/s on the rms magnitude of the line-of-sight component of velocities between 1.5 and 4 solar radius. Density measurements obtained in situ in the solar wind in the ecliptic were used to locate the sources of low speed and high-speed winds in the polar region. An eclipse photograph of the corona at solar maximum is provided.

  17. Coronal temperatures, heating, and energy flow in a polar region of the sun at solar maximum

    SciTech Connect

    Withbroe, G.L.; Kohl, J.L.; Weiser, H.; Munro, R.H.

    1985-10-01

    The profiles of resonantly scattered Lyman-alpha coronal radiation have been used to determine the hydrogen kinetic temperature from 1.5 to 4 solar radius from the center of the polar region of the corona observed in 1980 at solar maximum. Hydrogen temperatures derived from the line profiles were found to decrease with height from 1.2 million K at r = 1.5 solar radii to 600,000 K at r = 4 solar radius. Comparison of the measured kinetic temperatures with predictions from a semiempirical two-fluid model showed evidence of a small amount of heating or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 solar radius. The widths of the profiles confirmed an upper limit of 110 + or - 15 km/s on the rms magnitude of the line-of-sight component of velocities between 1.5 and 4 solar radius. Density measurements obtained in situ in the solar wind in the ecliptic were used to locate the sources of low speed and high-speed winds in the polar region. An eclipse photograph of the corona at solar maximum is provided. 31 references.

  18. Heat Transfer Correlations for compressible flow in Micro Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Coppola, M. A.; Croce, G.

    2016-09-01

    The paper discusses the definition of dimensionless parameters useful to define a local correlation for convective heat transfer in compressible, micro scale gaseous flows. A combination of static and stagnation temperatures is chosen, as it allows to weight the temperature change related to the heat transfer and that induced by conversion of internal energy into kinetic one. The correlation offers a purely convective local Nusselt number, i.e. correlating the heat flow rate with the local flow parameters and wall surface temperature. The correlation is validated through a series of numerical computations in both counter-current and co-current micro heat exchanger configurations. The numerical computations take into account rarefaction and conjugate heat transfer effects.

  19. Fluid flow and heat transfer in polygonal micro heat pipes

    NASA Astrophysics Data System (ADS)

    Rao, Sai; Wong, Harris

    2015-11-01

    Micro heat pipes have been used to cool microelectronic devices, but their heat transfer coefficients are low compared with those of conventional heat pipes. We model heat and mass transfer in triangular, square, hexagonal, and rectangular micro heat pipes under small imposed temperature differences. A micro heat pipe is a closed microchannel filled with a wetting liquid and a long vapor bubble. When a temperature difference is applied across a micro heat pipe, the equilibrium vapor pressure at the hot end is higher than that at the cold end, and the difference drives a vapor flow. As the vapor moves, the vapor pressure at the hot end drops below the saturation pressure. This pressure drop induces continuous evaporation from the interface. Two dimensionless numbers emerge from the momentum and energy equations: the heat-pipe number H, and the evaporation exponent S. When H >> 1 and S >> 1, vapor-flow heat transfer dominates and a thermal boundary layer appears at the hot end, the thickness of which scales as L/S, where L is the half-length of the pipe. A similar boundary layer exists at the cold end. Outside the boundary layers, the temperature is uniform. We also find a dimensionless optimal pipe length Sm =Sm(H) for maximum evaporative heat transfer. Thus, our model suggests that micro heat pipes should be designed with H >> 1 and S =Sm. We calculate H and S for four published micro-heat-pipe experiments, and find encouraging support for our design criterion.

  20. Energy recovery heat exchanger installation

    SciTech Connect

    Bradshaw, N.F.

    1983-08-16

    An installation is disclosed for energy recovery heat exchangers arranged to transfer heat into or out of air exhausted from an air handling system for paint spray booths. The system includes a collection chamber about which the intakes of a series of exhaust fans are arranged to draw exhaust air into an exhaust stack. Pairs of inclined wetted surface coil sets are mounted in the walls of the enclosures, each in communication with the intake of an exhaust fan so as to receive airflow of each exhaust fan. Each of the enclosures is provided with an access door to enable cleaning and other maintenance chores to be carried out on the coil sets and pivotally mounted blocking panels may be positioned to close off air flow across the coils and bypassing of the exhaust flow through the access doors in the event excessive overspray solids are present in the exhaust flow.

  1. Joule heating in electrokinetic flow.

    PubMed

    Xuan, Xiangchun

    2008-01-01

    Electrokinetic flow is an efficient means to manipulate liquids and samples in lab-on-a-chip devices. It has a number of significant advantages over conventional pressure-driven flow. However, there exists inevitable Joule heating in electrokinetic flow, which is known to cause temperature variations in liquids and draw disturbances to electric, flow and concentration fields via temperature-dependent material properties. Therefore, both the throughput and the resolution of analytic studies performed in microfluidic devices are affected. This article reviews the recent progress on the topic of Joule heating and its effect in electrokinetic flow, particularly the theoretical and experimental accomplishments from the aspects of fluid mechanics and heat/mass transfer. The primary focus is placed on the temperature-induced flow variations and the accompanying phenomena at the whole channel or chip level.

  2. Stress and heat flow

    SciTech Connect

    Lachenbrunch, A.H.; McGarr, A.

    1990-01-01

    As the Pacific plate slides northward past the North American plate along the San Andreas fault, the frictional stress that resists plate motion there is overcome to cause earthquakes. However, the frictional heating predicted for the process has never been detected. Thus, in spite of its importance to an understanding of both plate motion and earthquakes, the size of this frictional stress is still uncertain, even in order of magnitude.

  3. Self-similar flow of a rotating dusty gas behind the shock wave with increasing energy, conduction and radiation heat flux

    NASA Astrophysics Data System (ADS)

    Nath, G.

    2012-01-01

    A self-similar solution is obtained for one dimensional adiabatic flow behind a cylindrical shock wave propagating in a rotating dusty gas in presence of heat conduction and radiation heat flux with increasing energy. The dusty gas is assumed to be a mixture of non-ideal (or perfect) gas and small solid particles, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-condition is maintained and variable energy input is continuously supplied by the piston (or inner expanding surface). The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature only. In order to obtain the similarity solutions the initial density of the ambient medium is assumed to be constant and the angular velocity of the ambient medium is assumed to be decreasing as the distance from the axis increases. The effects of the variation of the heat transfer parameters and non-idealness of the gas in the mixture are investigated. The effects of an increase in (i) the mass concentration of solid particles in the mixture and (ii) the ratio of the density of solid particles to the initial density of the gas on the flow variables are also investigated.

  4. US energy flow, 1991

    SciTech Connect

    Borg, I.Y.; Briggs, C.K.

    1992-06-01

    Trends in energy consumption and assessment of energy sources are discussed. Specific topics discussed include: energy flow charts; comparison of energy use with 1990 and earlier years; supply and demand of fossil fuels (oils, natural gas, coal); electrical supply and demand; and nuclear power.

  5. Coupled flow, thermal and structural analysis of aerodynamically heated panels

    NASA Technical Reports Server (NTRS)

    Thornton, Earl A.; Dechaumphai, Pramote

    1986-01-01

    A finite element approach to coupling flow, thermal and structural analyses of aerodynamically heated panels is presented. The Navier-Stokes equations for laminar compressible flow are solved together with the energy equation and quasi-static structural equations of the panel. Interactions between the flow, panel heat transfer and deformations are studied for thin stainless steel panels aerodynamically heated by Mach 6.6 flow.

  6. Motorcycle waste heat energy harvesting

    NASA Astrophysics Data System (ADS)

    Schlichting, Alexander D.; Anton, Steven R.; Inman, Daniel J.

    2008-03-01

    Environmental concerns coupled with the depletion of fuel sources has led to research on ethanol, fuel cells, and even generating electricity from vibrations. Much of the research in these areas is stalling due to expensive or environmentally contaminating processes, however recent breakthroughs in materials and production has created a surge in research on waste heat energy harvesting devices. The thermoelectric generators (TEGs) used in waste heat energy harvesting are governed by the Thermoelectric, or Seebeck, effect, generating electricity from a temperature gradient. Some research to date has featured platforms such as heavy duty diesel trucks, model airplanes, and automobiles, attempting to either eliminate heavy batteries or the alternator. A motorcycle is another platform that possesses some very promising characteristics for waste heat energy harvesting, mainly because the exhaust pipes are exposed to significant amounts of air flow. A 1995 Kawasaki Ninja 250R was used for these trials. The module used in these experiments, the Melcor HT3-12-30, produced an average of 0.4694 W from an average temperature gradient of 48.73 °C. The mathematical model created from the Thermoelectric effect equation and the mean Seebeck coefficient displayed by the module produced an average error from the experimental data of 1.75%. Although the module proved insufficient to practically eliminate the alternator on a standard motorcycle, the temperature data gathered as well as the examination of a simple, yet accurate, model represent significant steps in the process of creating a TEG capable of doing so.

  7. Exploring Geothermal Energy Potential in Ireland through 3-D Geophysical-Petrological Modelling of Surface Heat-Flow and Crustal and Upper-Mantle Structure

    NASA Astrophysics Data System (ADS)

    Fullea, J.; Muller, M. R.; Jones, A. G.

    2012-04-01

    Little is known of Ireland's deep, low-enthalpy geothermal resources and the potential for space heating and/or electricity generation based on geothermal energy to displace Ireland's significant reliance on carbon-based fuels. IRETHERM (www.iretherm.ie) is a four-and-a-half year, all-island, academic-government-industry collaborative project, initiated in 2011, with the overarching objective of developing a strategic and holistic understanding of Ireland's geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One of the challenges in searching for deep geothermal resources in the relatively unexplored setting of Ireland lies in identifying those areas most likely to support significantly elevated temperatures at depth. Available borehole data, although sparse and clustered around areas of mineral and hydrocarbon interest, suggest a marked regional increase in surface heat-flow across Ireland, from ~40 mW/m2 in the south to >80 mW/m2 in the north. The origins of both the observed regional heat-flow trend and local temperature anomalies have not been investigated and are not currently understood. Although variations in the structure of the crust and lithosphere have been revealed by a number of active-source seismic and teleseismic experiments, their effects on surface heat-flow have not been modelled. Bulk 3-D variation in crustal heat-production across Ireland, which may contribute significantly to the observed regional and local temperature variations, has also not been determined. We investigate the origins of Ireland's regional heat-flow trend and regional and local temperature variations using the software package LitMod. This software combines petrological and geophysical modelling of the lithosphere and sub-lithospheric upper mantle within an internally consistent thermodynamic-geophysical framework, where all relevant properties are functions of temperature, pressure and chemical composition. The major

  8. DEVELOPMENT OF A MULTI-LOOP FLOW AND HEAT TRANSFER FACILITY FOR ADVANCED NUCLEAR REACTOR THERMAL HYDRAULIC AND HYBRID ENERGY SYSTEM STUDIES

    SciTech Connect

    James E. O'Brien; Piyush Sabharwall; SuJong Yoon

    2001-09-01

    A new high-temperature multi-fluid, multi-loop test facility for advanced nuclear applications is under development at the Idaho National Laboratory. The facility will include three flow loops: high-temperature helium, molten salt, and steam/water. Molten salts have been identified as excellent candidate heat transport fluids for primary or secondary coolant loops, supporting advanced high temperature and small modular reactors (SMRs). Details of some of the design aspects and challenges of this facility, which is currently in the conceptual design phase, are discussed. A preliminary design configuration will be presented, with the required characteristics of the various components. The loop will utilize advanced high-temperature compact printed-circuit heat exchangers (PCHEs) operating at prototypic intermediate heat exchanger (IHX) conditions. The initial configuration will include a high-temperature (750°C), high-pressure (7 MPa) helium loop thermally integrated with a molten fluoride salt (KF-ZrF4) flow loop operating at low pressure (0.2 MPa) at a temperature of ~450°C. Experiment design challenges include identification of suitable materials and components that will withstand the required loop operating conditions. Corrosion and high temperature creep behavior are major considerations. The facility will include a thermal energy storage capability designed to support scaled process heat delivery for a variety of hybrid energy systems and grid stabilization strategies. Experimental results obtained from this research will also provide important data for code ve

  9. Energy absorber for sodium-heated heat exchanger

    DOEpatents

    Essebaggers, J.

    1975-12-01

    A heat exchanger is described in which water-carrying tubes are heated by liquid sodium and in which the results of accidental contact between the water and the sodium caused by failure of one or more of the water tubes is minimized. An energy absorbing chamber contains a compressible gas and is connected to the body of flowing sodium by a channel so that, in the event of a sodium-water reaction, products of the reaction will partially fill the energy absorbing chamber to attenuate the rise in pressure within the heat exchanger.

  10. Energy 101: Geothermal Heat Pumps

    ScienceCinema

    None

    2016-07-12

    An energy-efficient heating and cooling alternative, the geothermal heat pump system moves heat from the ground to a building (or from a building to the ground) through a series of flexible pipe "loops" containing water. This edition of Energy 101 explores the benefits Geothermal and the science behind how it all comes together.

  11. Energy 101: Geothermal Heat Pumps

    SciTech Connect

    2011-01-01

    An energy-efficient heating and cooling alternative, the geothermal heat pump system moves heat from the ground to a building (or from a building to the ground) through a series of flexible pipe "loops" containing water. This edition of Energy 101 explores the benefits Geothermal and the science behind how it all comes together.

  12. Enhance of heat transfer on unsteady Hiemenz flow of nanofluid over a porous wedge with heat source/sink due to solar energy radiation with variable stream condition

    NASA Astrophysics Data System (ADS)

    Mohamad, Radiah Bte; Kandasamy, R.; Muhaimin, I.

    2013-09-01

    Nanofluid-based direct solar receivers, where nanoparticles in a liquid medium can scatter and absorb solar radiation, have recently received interest to efficiently distribute and store the thermal energy. The objective of the present work is to investigate theoretically the unsteady homogeneous Hiemenz flow of an incompressible viscous nanofluid past a porous wedge due to solar energy (incident radiation). The conclusion is drawn that the temperature is significantly influenced by magnetic strength, nanoparticle volume fraction, convective radiation and porosity of the wedge sheet.

  13. Polar Heat Flow on Io

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Matson, D. L.; Johnson, T. V.; Davies, A. G.; Blaney, D. L.

    2003-01-01

    Recently, Galileo spacecraft data have revealed Io's polar regions to be much warmer than previously expected. This unexpected development came from Photo-Polarimeter Radiometer (PPR) data which show that the minimum night temperatures are in the range of 90-95 K virtually everywhere on Io. The minimum night temperatures show no dependence upon latitude and, when away from the sunset terminator, they show no dependence upon time of night. This is indeed bizarre behavior for surface units which generally had been assumed to be passive with respect to Io's pervasive volcanism. Night temperatures of 90-95 K at high, polar latitudes are particularly hard to explain. Even assuming infinite thermal inertia, at these latitudes there is insufficient sunlight to support these warm night temperatures. Thus, through the process of elimination of other possibilities, we come to the conclusion that these surfaces are volcanically heated. Taking previously passive units and turning them into new sources of heat flow is a radical departure from previous thermophysical model paradigms. However, the geological interpretation is straight forward. We are simply seeing the effect of old, cool lava flows which cover most of the surface of Io but yet have some heat to radiate. Under these new constraints, we have taken on the challenge of formulating a physical model which quantitatively reproduces all of the observations of Io's thermal emission. In the following we introduce a new parametric model which suffices to identify a previously unrecognized polar component of Io's heat flow.

  14. The Development of an INL Capability for High Temperature Flow, Heat Transfer, and Thermal Energy Storage with Applications in Advanced Small Modular Reactors, High Temperature Heat Exchangers, Hybrid Energy Systems, and Dynamic Grid Energy Storage C

    SciTech Connect

    Sun, Xiaodong; Zhang, Xiaoqin; Kim, Inhun; O'Brien, James; Sabharwall, Piyush

    2014-10-01

    The overall goal of this project is to support Idaho National Laboratory in developing a new advanced high temperature multi fluid multi loop test facility that is aimed at investigating fluid flow and heat transfer, material corrosion, heat exchanger characteristics and instrumentation performance, among others, for nuclear applications. Specifically, preliminary research has been performed at The Ohio State University in the following areas: 1. A review of fluoride molten salts’ characteristics in thermal, corrosive, and compatibility performances. A recommendation for a salt selection is provided. Material candidates for both molten salt and helium flow loop have been identified. 2. A conceptual facility design that satisfies the multi loop (two coolant loops [i.e., fluoride molten salts and helium]) multi purpose (two operation modes [i.e., forced and natural circulation]) requirements. Schematic models are presented. The thermal hydraulic performances in a preliminary printed circuit heat exchanger (PCHE) design have been estimated. 3. An introduction of computational methods and models for pipe heat loss analysis and cases studies. Recommendations on insulation material selection have been provided. 4. An analysis of pipe pressure rating and sizing. Preliminary recommendations on pipe size selection have been provided. 5. A review of molten fluoride salt preparation and chemistry control. An introduction to the experience from the Molten Salt Reactor Experiment at Oak Ridge National Laboratory has been provided. 6. A review of some instruments and components to be used in the facility. Flowmeters and Grayloc connectors have been included. This report primarily presents the conclusions drawn from the extensive review of literatures in material selections and the facility design progress at the current stage. It provides some useful guidelines in insulation material and pipe size selection, as well as an introductory review of facility process and components.

  15. Stability of laser heated flows

    NASA Technical Reports Server (NTRS)

    Wu, P. K. S.; Pirri, A. N.

    1976-01-01

    A local stability analysis is utilized to determine the stability of disturbances generated at each point along a nozzle of variable area ratio for a one-dimensional flow heated by laser radiation entering from the upstream direction. The governing equations for the quasi-one-dimensional flow without viscous dissipation, diffusion, and thermal conduction but including radiative heat transfer are given. The governing equations are combined to yield a relationship which governs the Mach number variation through the nozzle. The complete steady-state solution can be calculated from knowledge of the Mach number profile, the inlet conditions, and the laser power. The local stability analysis permits obtaining contour (or contours) of neutral stability. Solutions have been obtained for various nozzle configurations, but only one set of example calculations is presented. The results obtained indicate that the analysis serves as an important indicator as to where potential absorption wave phenomena may be initiated.

  16. A Numerical Study of Energy Balances and Flow Planforms in Earth's Mantle with Radioactive Heating, the 660 km-depth Phase Boundary and Continents

    NASA Astrophysics Data System (ADS)

    Sinha, Gunjan

    It is well established that the temperature gradients in the interiors of internally-heated mantle convection models are subadiabatic (e.g. Parmentier et al., 1994; Bunge et al., 1997, 2001). The subadiabatic gradients have been explained to arise due to a balance between vertical advection and internal heating, however, a detailed analysis of the energy balance in the subadiabatic regions has not been undertaken. In this research, I examine in detail the energy balance in a suite of two-dimensional convection calculations with mixed internal and basal heating, depth-dependent viscosity and continents. I find that there are three causes of subadiabatic gradients. One is the above-mentioned balance, which becomes significant when the ratio of internal heating to surface heat flux is large. The second mechanism involves the growth of the overshoot (maximum and minimum temperatures along a geotherm) of the geotherm near the lower boundary where the dominant balance is between vertical and horizontal advection. The latter mechanism is significant even in relatively weakly internally heated calculations. For time-dependent calculations, I find that local secular cooling can be a dominant term in the energy equation and can lead to subadiabaticity. However, it does not show its signature on the shape of the time-averaged geotherm. I also compare the basal heat flux with parameterized calculations based on the temperature drop at the core-mantle boundary, calculated both with and without taking the subadiabatic gradient into account and I find a significantly improved fit with its inclusion. I also explore a wide range of parameter space to investigate the dynamical interaction between effects due to surface boundary conditions representing continental and oceanic lithosphere and the endothermic phase boundary at 660 km-depth in two-dimensional Cartesian coordinate convection calculations. I find that phase boundary induced mantle layering is strongly affected by the

  17. Double Stage Heat Transformer Controlled by Flow Ratio

    NASA Astrophysics Data System (ADS)

    Silva-Sotelo, S.; Romero, R. J.; Rodríguez – Martínez, A.

    this paper shows the values of Flow ratio (FR) for control of an absorption double stage heat transformer. The main parameters for the heat pump system are defined as COP, FR and GTL. The control of the entire system is based in a new definition of FR. The heat balance of the Double Stage Heat Transformer (DSHT) is used for the control. The mass flow is calculated for a HPVEE program and a second program control the mass flow. The mass flow is controlled by gear pumps connected to LabView program. The results show an increment in the fraction of the recovery energy. An example of oil distillation is used for the calculation. The waste heat energy is added at the system at 70 °C. Water ™ - Carrol mixture is used in the DSHT. The recover energy is obtained in a second absorber at 128 °C with two scenarios.

  18. Heat flow diagnostics for helicon plasmas.

    PubMed

    Berisford, Daniel F; Bengtson, Roger D; Raja, Laxminarayan L; Cassady, Leonard D; Chancery, William J

    2008-10-01

    We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10 kW VASIMR VX-50 experiment and the University of Texas at Austin 1 kW helicon experiment. Power losses downstream from the antenna are measured using thermocouples and probes. The heating of the dielectric tube increases with decreasing magnetic fields, higher gas flow rates, and higher molecular mass of the gas. These preliminary results suggest that cross-field particle diffusion contributes a significant proportion of the energy flux to the wall.

  19. Heat flow diagnostics for helicon plasmasa)

    NASA Astrophysics Data System (ADS)

    Berisford, Daniel F.; Bengtson, Roger D.; Raja, Laxminarayan L.; Cassady, Leonard D.; Chancery, William J.

    2008-10-01

    We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10kW VASIMR VX-50 experiment and the University of Texas at Austin 1kW helicon experiment. Power losses downstream from the antenna are measured using thermocouples and probes. The heating of the dielectric tube increases with decreasing magnetic fields, higher gas flow rates, and higher molecular mass of the gas. These preliminary results suggest that cross-field particle diffusion contributes a significant proportion of the energy flux to the wall.

  20. Heat flow diagnostics for helicon plasmas

    SciTech Connect

    Berisford, Daniel F.; Bengtson, Roger D.; Raja, Laxminarayan L.; Cassady, Leonard D.; Chancery, William J.

    2008-10-15

    We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10 kW VASIMR VX-50 experiment and the University of Texas at Austin 1 kW helicon experiment. Power losses downstream from the antenna are measured using thermocouples and probes. The heating of the dielectric tube increases with decreasing magnetic fields, higher gas flow rates, and higher molecular mass of the gas. These preliminary results suggest that cross-field particle diffusion contributes a significant proportion of the energy flux to the wall.

  1. Comparisons of Earthward Poynting flux and the kinetic energy flux of up-flowing transversely heated ions from the Polar spacecraft on cusp magnetic field lines

    NASA Astrophysics Data System (ADS)

    Tian, S.; Wygant, J. R.; Cattell, C. A.; Scudder, J. D.; Mozer, F.; Russell, C. T.

    2013-12-01

    This paper presents estimates of the Poynting flux flowing along magnetic field lines in the Earth's cusp region over altitudes from 0.8 Re to 7 Re using measurements during several passes from the Polar spacecraft. The Poynting flux is calculated from measurements of electric fields from the University of California, Berkeley double probe electric field instrument, and from magnetic field measurements from the U.C.L.A. fluxgate magnetometer. The estimates of Poynting flux are of special interest because the high altitude mapping of the cusp magnetic flux tubes may connect to newly reconnected field lines and the low altitude mapping of these field lines is the scene of powerful acceleration processes, most notably transverse heating and outflow of ions. The data show that the Poynting flux is predominantly downward over the frequency range from 1 mHz to 1 Hz . This frequency range includes the Poynting flux due to steady state convection and field-aligned current systems, Alfven waves, and kinetic Alfven waves. Measurement of transversely heated ions over the energy ranges from 10 eV to several keV and their associated ion kinetic energy flux are presented from the University of Iowa Hydra instrument and compared to the values of the downward Poynting flux. Generally the downward Poynting flux exceeds the upward kinetic energy flux of the ions.

  2. Constraints on Crustal Heat Production from Heat Flow Data

    NASA Astrophysics Data System (ADS)

    Jaupart, C.; Mareschal, J.-C.

    2003-12-01

    The continental crust is an important repository of highly incompatible elements such as uranium and thorium. Exactly how much it contains is a key issue for the thermal regime of continents and for understanding how the Earth's mantle has evolved through geological time due to crust extraction. Recent estimates of the average uranium, thorium, and potassium concentrations in the continental crust vary by almost a factor of 2 (Wedepohl, 1995;Rudnick and Fountain, 1995; Taylor and McLennan, 1995; see also Chapter 3.01). These estimates are based on different assumptions regarding crustal structure and rely on different types of crustal samples, ranging from xenoliths to shales. They require an extrapolation in scale from tiny specimens to the whole crust of a geological province. Uranium and thorium tend to be located in accessory minerals and on grain boundaries, which are not related simply to bulk chemical composition. Thus, their concentrations vary on the scale of a petrological thin section, a hand sample, an outcrop, and a whole massif. In a geological province, abundant rocks such as gneisses and metasedimentary rocks are usually under-studied because of their complex origin and metamorphic history. A final difficulty is to evaluate the composition of intermediate and lower crustal levels, which are as heterogeneous as the shallow ones (e.g., Fountain and Salisbury, 1981; Clowes et al., 1992).Independent estimates of the amount of uranium and thorium in the continental crust can be obtained from heat flow data. The energy produced by the decay of these radioactive elements accounts for a large fraction of the heat flow at the surface of continents (Birch, 1954; Wasserburg et al., 1964; Clark and Ringwood, 1964; Sclater et al., 1980; Taylor and McLennan, 1995). This may be the only case where geophysical data bear directly on geochemical budgets. Since the mid-1970s, there has been much progress in our understanding of continental heat flow. The relationship

  3. Subsurface heat flow in an urban environment

    NASA Astrophysics Data System (ADS)

    Ferguson, Grant; Woodbury, Allan D.

    2004-02-01

    The subsurface temperature field beneath Winnipeg, Canada, is significantly different from that of the surrounding rural areas. Downward heat flow to depths as great as 130 m has been noted in some areas beneath the city and groundwater temperatures in a regional aquifer have risen by as much as 5°C in some areas. Numerical simulation of heat transport supports the conjecture that these temperature changes can be largely attributed to heat loss from buildings and the temperature at any given point is sensitive to the distance from and the age of any buildings. The effect is most noticable when buildings are closely spaced, which is typical of urban areas. Temperature measurements in areas more than a few hundred meters away from any heated structure were only a few tenths of a degree Celsius greater than those observed outside the city, suggesting that other reasons for increases in subsurface temperature, such as changes in surface cover or climate change, may be responsible for some of the some of the observed increase in temperatures. These sources of additional heat to the subsurface make it difficult to resolve information on past climates from temperatures measured in boreholes and monitoring wells. In some areas, the temperature increases may also have an impact on geothermal energy resources. This impact might be in the form of an increase in heat pump efficiency or in the case of the Winnipeg area, a decrease in the efficiency of direct use of groundwater for cooling.

  4. Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

    DOEpatents

    Koplow, Jeffrey P.

    2016-02-16

    Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

  5. US energy flow, 1981

    SciTech Connect

    Briggs, C.K.; Borg, I.Y.

    1982-10-01

    Flow diagrams to describe the US energy situation have been prepared since 1972 by the Lawrence Livermore National Laboratory. In 1981 the energy consumption was 73 quads (or 73 x 10/sup 15/ Btu) - down from 75 quads in 1980. Oil continues to dominate the picture as it comprises 45% of the total energy used. Net oil use (exclusive of oil purchased for the Strategic Petroleum Reserve and exports) fell 8%; oil imports declined 14%. In contrast to oil, use of natural gas and coal remained at 1980 levels. Decreased use of residual oils, principally for electric power generation, account for much of the drop in oil use. Increased use of coal and nuclear energy for power generation almost compensated for the decrease in use of oil in that end-use. Transmitted power remained at 1980 levels. The remainder of the drop in energy usage is attributed to price-driven conservation, increased efficiencies in end-use and the recession that prevailed during most of the year. The share of the energy drop attributable to the recession is estimated by various analysts to be on the order of 40 to 50%. The fact that for a given dollar of US GNP, oil consumption has declined faster than overall energy consumption attests to the role factors other than the economic slow-down have had on decreased energy consumption. Gasoline consumption remained at 1980 levels and the total transportation end-use sector increased its energy consumption by a modest 3%.

  6. Behaviour: Seeing heat saves energy

    NASA Astrophysics Data System (ADS)

    Steg, Linda

    2016-01-01

    Household energy conservation can help to significantly lower energy consumption. Visual cues provided by thermal imaging of heat loss in buildings are now shown to increase energy conserving behaviours and implementations among homeowners more effectively than just performing carbon footprint audits.

  7. Heat transfer measurements of the 1983 kilauea lava flow.

    PubMed

    Hardee, H C

    1983-10-07

    Convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of Kilauea volcano in Hawaii. Eight field measurements of induced natural convection were made, giving heat flux values that ranged from 1.78 to 8.09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees Celsius, respectively. These field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace-melted samples of molten lava, and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy.

  8. Heat-transfer measurements of the 1983 Kilauea lava flow

    SciTech Connect

    Hardee, H.C.

    1983-10-07

    Convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of Kilauea volcano in Hawaii. Eight field measurements of induced natural convection were made, giving heat flux values that ranged from 1.78 to 8.09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees Celsius, respectively. These field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace-melted samples of molten lava, and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy.

  9. Heat flow meter for the diagnostics of pipelines

    NASA Astrophysics Data System (ADS)

    Nussupbekov, Bekbolat R.; Karabekova, Dana Zh.; Khassenov, Ayanbergen K.; Zhirnova, Oxana; Zyska, Tomasz

    2016-09-01

    Thermal methods of nondestructive testing are widely used for the analysis of the thermal insulation of underground pipelines. In heat methadone nondestructive testing, the thermal energy is distributed in the test object. Temperature field of the object's surface is a source of information on the characteristics of heat transfer. This article describes the modifications we have developed some of the heat flux sensors. A common element of these devices is the battery thermoelectric sensor special design, acting as a thermoelectric converter heat flow.

  10. Electron temperature and heat flow in the nightside Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.; Brace, L. H.; Theis, R. F.; Mayr, H. G.

    1980-01-01

    A steady-state two-dimensional heat balance model is used to analyze the night side Venusian ionospheric electron temperatures given by the Pioneer Venus orbiter electron temperature probe. The energy calculation includes the solar EUV heating at the terminator, electron cooling to ions and neutrals, and heat conduction within the ionospheric plasma. An optimum magnetic field is derived by solving for the heat flux directions which force energy conservation while constrained by the observed temperatures within the range of 80-170 deg solar zenith angle and 160-170 km. The heat flux vectors indicate a magnetic field that connects the lower night side ionosphere to the day side ionosphere, and connects the upper ionosphere to the ionosheath. The lower ionosphere is heated through conduction of heat from the dayside, and the upper ionosphere is heated by the solar wind in the ionosheath with heat flowing downward and from the nightside to the day side.

  11. Exhaust bypass flow control for exhaust heat recovery

    DOEpatents

    Reynolds, Michael G.

    2015-09-22

    An exhaust system for an engine comprises an exhaust heat recovery apparatus configured to receive exhaust gas from the engine and comprises a first flow passage in fluid communication with the exhaust gas and a second flow passage in fluid communication with the exhaust gas. A heat exchanger/energy recovery unit is disposed in the second flow passage and has a working fluid circulating therethrough for exchange of heat from the exhaust gas to the working fluid. A control valve is disposed downstream of the first and the second flow passages in a low temperature region of the exhaust heat recovery apparatus to direct exhaust gas through the first flow passage or the second flow passage.

  12. Molecular vibrational energy flow

    NASA Astrophysics Data System (ADS)

    Gruebele, M.; Bigwood, R.

    This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.

  13. Heat flow and convection demonstration (Apollo 14)

    NASA Technical Reports Server (NTRS)

    Bannister, T. C.

    1973-01-01

    Apollo 14 Astronaut Stuart A. Roosa conducted a group of experiments during the lunar flyback on February 7, 1971, to obtain information on heat flow and convection in gases and liquids in an environment of less than 0.000001 g. Flow observations and thermal data have shown that: (1) as expected, there are convective motions caused by surface tension gradients in a plane liquid layer with a free upper surface; (2) heat flow in enclosed liquids and gases occurs mainly by diffusive heat conduction; and (3) some convective processes, whose characteristics are not fully known, add to the heat transfer. The raw data are presented, and the analysis approach is given.

  14. Analysis of Heat Transfers inside Counterflow Plate Heat Exchanger Augmented by an Auxiliary Fluid Flow

    PubMed Central

    Khaled, A.-R. A.

    2014-01-01

    Enhancement of heat transfers in counterflow plate heat exchanger due to presence of an intermediate auxiliary fluid flow is investigated. The intermediate auxiliary channel is supported by transverse conducting pins. The momentum and energy equations for the primary fluids are solved numerically and validated against a derived approximate analytical solution. A parametric study including the effect of the various plate heat exchanger, and auxiliary channel dimensionless parameters is conducted. Different enhancement performance indicators are computed. The various trends of parameters that can better enhance heat transfer rates above those for the conventional plate heat exchanger are identified. Large enhancement factors are obtained under fully developed flow conditions. The maximum enhancement factors can be increased by above 8.0- and 5.0-fold for the step and exponential distributions of the pins, respectively. Finally, counterflow plate heat exchangers with auxiliary fluid flows are recommended over the typical ones if these flows can be provided with the least cost. PMID:24719572

  15. Analysis of heat transfers inside counterflow plate heat exchanger augmented by an auxiliary fluid flow.

    PubMed

    Khaled, A-R A

    2014-01-01

    Enhancement of heat transfers in counterflow plate heat exchanger due to presence of an intermediate auxiliary fluid flow is investigated. The intermediate auxiliary channel is supported by transverse conducting pins. The momentum and energy equations for the primary fluids are solved numerically and validated against a derived approximate analytical solution. A parametric study including the effect of the various plate heat exchanger, and auxiliary channel dimensionless parameters is conducted. Different enhancement performance indicators are computed. The various trends of parameters that can better enhance heat transfer rates above those for the conventional plate heat exchanger are identified. Large enhancement factors are obtained under fully developed flow conditions. The maximum enhancement factors can be increased by above 8.0- and 5.0-fold for the step and exponential distributions of the pins, respectively. Finally, counterflow plate heat exchangers with auxiliary fluid flows are recommended over the typical ones if these flows can be provided with the least cost.

  16. Has Northern Hemisphere Heat Flow Been Underestimated?

    NASA Astrophysics Data System (ADS)

    Gosnold, W. D.; Majorowicz, J.; Safanda, J.; Szewczyk, J.

    2005-05-01

    We present three lines of evidence to suggest the hypothesis that heat flow in the northern hemisphere may have been underestimated by 15 to 60 percent in shallow wells due to a large post-glacial warming signal. First, temperature vs. depth (T-z) measurements in parts of Europe and North America show a systematic increase in heat flow with depth. This phenomenon is best recognized in analyses of deep (greater than 2km) boreholes in non-tectonic regions with normal to low background heat flow. In Europe, the increase in heat flow with depth has been observed by analysis of more than 1500 deep boreholes located throughout the Fennoscandian Shield, East European Platform, Danish Basin, Germany, Czech Republic, and Poland. There are significantly fewer deep boreholes in North America, but the increase in heat flow with depth appears in a suite of 759 sites in the IHFC Global Heat Flow Database for the region east of the Rocky Mountains and north of latitude 40 N. Second, surface heat flow values in southern hemisphere shields average approximately 50 mWm-2, but surface heat flow values in northern hemisphere shields average 33 mWm-2. Unless crustal radioactivity or mantle heat flow or both factors are greater in southern hemisphere continents, there is no reason for the northern and southern shield areas having similar ages to have different heat flow values. Third, two recently published surface heat flow maps show anomalously low heat flow in the Canadian Shield in a pattern that is coincident with the Wisconsinan ice sheet. The coincidence of low heat flow and ice accumulation has no geophysical basis, thus the coincidence may suggest the existence of a transient signal caused by a warming event. Recent studies of heat flow in North America indicate that in several sites, the ice base temperature was close to the pressure melting point. We hypothesize that there may have been cold ice-free periods during the Pleistocene that would account for the apparent colder

  17. Free Energy and Heat Capacity

    SciTech Connect

    Kurata, Masaki; Devanathan, Ramaswami

    2015-10-13

    Free energy and heat capacity of actinide elements and compounds are important properties for the evaluation of the safety and reliable performance of nuclear fuel. They are essential inputs for models that describe complex phenomena that govern the behaviour of actinide compounds during nuclear fuel fabrication and irradiation. This chapter introduces various experimental methods to measure free energy and heat capacity to serve as inputs for models and to validate computer simulations. This is followed by a discussion of computer simulation of these properties, and recent simulations of thermophysical properties of nuclear fuel are briefly reviewed.

  18. Heat flow in the postquasistatic approximation

    SciTech Connect

    Rodriguez-Mueller, B.; Peralta, C.; Barreto, W.; Rosales, L.

    2010-08-15

    We apply the postquasistatic approximation to study the evolution of spherically symmetric fluid distributions undergoing dissipation in the form of radial heat flow. For a model that corresponds to an incompressible fluid departing from the static equilibrium, it is not possible to go far from the initial state after the emission of a small amount of energy. Initially collapsing distributions of matter are not permitted. Emission of energy can be considered as a mechanism to avoid the collapse. If the distribution collapses initially and emits one hundredth of the initial mass only the outermost layers evolve. For a model that corresponds to a highly compressed Fermi gas, only the outermost shell can evolve with a shorter hydrodynamic time scale.

  19. New Map of Io's Volcanic Heat Flow

    NASA Astrophysics Data System (ADS)

    Davies, A. G.; Veeder, G. J.; Matson, D.; Johnson, T. V.

    2014-12-01

    We have created a global map of Io's volcanic heat flow from 245 thermal sources indicative of ongoing or recent volcanic activity, and 8 additional outbursts [1,2]. We incorporate data from both spacecraft and ground-based instruments that have observed Io primarily at infrared wavelengths. This map provides a snapshot of Io's volcanic activity and distribution during the Galileo epoch. Io's volcanic activity, in terms of thermal emission from individual eruptive centres, spans nearly six orders of magnitude, from Surt in 2001 (78 TW) [3] to a faint hot spot in patera P197 (0.2 GW) [1]. We account for ≈54% of Io's yearly volcanic heat flow, which emanates from ≈2% of Io's surface [1]. Averaged heat flow from the non-active surface is 1 ± 0.2 W m2. This quantification of volcanic heat flow map provides constraints for modelling the magnitude and location of the internal heating of Io by tidal dissipation. The observed heat flow distribution is the result of interior heating and volcanic advection, the delivery of magma to the surface regardless of its depth of origin. As noted previously [1, 2] the distribution of heat flow is not uniform, which is not unexpected. The volcanic heat flow does not match the expected distributions from end-member models for both the deep-seated (mantle) heating model (which predicts enhanced polar heating) and the shallow (aesthenospheric) heating model, which predicts enhanced thermal emission at sub-jovian and anti-jovian longitudes. Intriguingly, heat flow curves using a bin size of 30 degrees show a longitudinal offset from the shallow heating model prediction of some tens of degrees [2], suggesting a more complex mixture of deep and shallow heating. Future work includes refinement of thermal emission by including temporal variability of thermal emission at individual volcanoes, and comparing the heat flow map with the Io Geological Map [4] and global topography [5]. We thank the NASA OPR Program for support. Part of this

  20. Io: Heat flow from dark volcanic fields

    NASA Astrophysics Data System (ADS)

    Veeder, Glenn J.; Davies, Ashley Gerard; Matson, Dennis L.; Johnson, Torrence V.

    2009-11-01

    Dark flow fields on the jovian satellite Io are evidence of current or recent volcanic activity. We have examined the darkest volcanic fields and quantified their thermal emission in order to assess their contribution to Io's total heat flow. Loki Patera, the largest single source of heat flow on Io, is a convenient point of reference. We find that dark volcanic fields are more common in the hemisphere opposite Loki Patera and this large scale concentration is manifested as a maximum in the longitudinal distribution (near ˜200 °W), consistent with USGS global geologic mapping results. In spite of their relatively cool temperatures, dark volcanic fields contribute almost as much to Io's heat flow as Loki Patera itself because of their larger areal extent. As a group, dark volcanic fields provide an asymmetric component of ˜5% of Io's global heat flow or ˜5 × 10 12 W.

  1. Pneumatic Proboscis Heat-Flow Probe

    NASA Technical Reports Server (NTRS)

    Zacny, Kris; Hedlund, Magnus; Mumm, Eric; Shasho, Jeffrey; Chu, Philip; Kumar, Nishant

    2013-01-01

    Heat flow is a fundamental property of a planet, and provides significant constraints on the abundance of radiogenic isotopes, the thermal evolution and differentiation history, and the mechanical properties of the lithosphere. Heat-flow measurements are also essential in achieving at least four of the goals set out by the National Research Council for future lunar exploration. The heat-flow probe therefore directly addresses the goal of the Lunar Geophysical Network, which is to understand the interior structure and composition of the Moon. A key challenge for heat flow measurement is to install thermal sensors to the depths approximately equal to 3 m that are not influenced by the diurnal, annual, and longer-term fluctuations of the surface thermal environment. In addition, once deployed, the heat flow probe should cause little disturbance to the thermal regime of the surrounding regolith. A heat-flow probe system was developed that has two novel features: (1) it utilizes a pneumatic (gas) approach, excavates a hole by lofting the lunar soil out of the hole, and (2) deploys the heat flow probe, which utilizes a coiled up tape as a thermal probe to reach greater than 3-meter depth. The system is a game-changer for small lunar landers as it exhibits extremely low mass, volume, and simple deployment. The pneumatic system takes advantage of the helium gas used for pressurizing liquid propellant of the lander. Normally, helium is vented once the lander is on the surface, but it can be utilized for powering pneumatic systems. Should sufficient helium not be available, a simple gas delivery system may be taken specifically for the heat flow probe. Either way, the pneumatic heat flow probe system would be much lighter than other systems that entirely rely on the electrical power of the lander.

  2. Heat-flow mapping at the Geysers Geothermal Field

    SciTech Connect

    Thomas, R.P.

    1986-10-31

    Pertinent data were compiled for 187 temperature-gradient holes in the vicinity of The Geysers Geothermal field. Terrain-correction techniques were applied to most of the temperature-gradient data, and a temperature-gradient map was constructed. Cutting samples from 16, deep, production wells were analyzed for thermal conductivity. From these samples, the mean thermal conductivities were determined for serpentinized ultramafic rock, greenstone, and graywacke. Then, a heat flow map was made. The temperature-gradient and heat-flow maps show that The Geysers Geothermal field is part of a very large, northwesterly-trending, thermal anomaly; the commercially productive portion of the field may be 100 km/sup 2/ in area. The rate that heat energy flows through the surface by thermal conduction is estimated at 1.79 x 10/sup 9/MJ per year. The net heat energy loss from commercial production for 1983 is estimated at 180.14 x 10/sup 9/MJ.

  3. Experimental Investigation of A Heat Pipe-Assisted Latent Heat Thermal Energy Storage System

    NASA Astrophysics Data System (ADS)

    Tiari, Saeed; Mahdavi, Mahboobe; Qiu, Songgang

    2016-11-01

    In the present work, different operation modes of a latent heat thermal energy storage system assisted by a heat pipe network were studied experimentally. Rubitherm RT55 enclosed by a vertical cylindrical container was used as the Phase Change Material (PCM). The embedded heat pipe network consisting of a primary heat pipe and an array of four secondary heat pipes were employed to transfer heat to the PCM. The primary heat pipe transports heat from the heat source to the heat sink. The secondary heat pipes transfer the extra heat from the heat source to PCM during charging process or retrieve thermal energy from PCM during discharging process. The effects of heat transfer fluid (HTF) flow rate and temperature on the thermal performance of the system were investigated for both charging and discharging processes. It was found that the HTF flow rate has a significant effect on the total charging time of the system. Increasing the HTF flow rate results in a remarkable increase in the system input thermal power. The results also showed that the discharging process is hardly affected by the HTF flow rate but HTF temperature plays an important role in both charging and discharging processes. The authors would like to acknowledge the financial supports by Temple University for the project.

  4. Energy Corner: Heat Reclamation Rescues Wasted Heat.

    ERIC Educational Resources Information Center

    Daugherty, Thomas

    1982-01-01

    Heat reclamation systems added to pre-existing central heating systems provide maximum savings at minimum cost. The benefits of a particular appliance marketed under the brand name "Energizer" are discussed. (Author/MLF)

  5. Earth tides, global heat flow, and tectonics

    USGS Publications Warehouse

    Shaw, H.R.

    1970-01-01

    The power of a heat engine ignited by tidal energy can account for geologically reasonable rates of average magma production and sea floor spreading. These rates control similarity of heat flux over continents and oceans because of an inverse relationship between respective depth intervals for mass transfer and consequent distributions of radiogenic heat production.

  6. Earth tides, global heat flow, and tectonics.

    PubMed

    Shaw, H R

    1970-05-29

    The power of a heat engine ignited by tidal energy can account for geologically reasonable rates of average magma production and sea floor spreading. These rates control similarity of heat flux over continents and oceans because of an inverse relationship between respective depth intervals for mass transfer and consequent distributions of radiogenic heat production.

  7. Flow and heat transfer enhancement in tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Sayed Ahmed, Sayed Ahmed E.; Mesalhy, Osama M.; Abdelatief, Mohamed A.

    2015-11-01

    The performance of heat exchangers can be improved to perform a certain heat-transfer duty by heat transfer enhancement techniques. Enhancement techniques can be divided into two categories: passive and active. Active methods require external power, such as electric or acoustic field, mechanical devices, or surface vibration, whereas passive methods do not require external power but make use of a special surface geometry or fluid additive which cause heat transfer enhancement. The majority of commercially interesting enhancement techniques are passive ones. This paper presents a review of published works on the characteristics of heat transfer and flow in finned tube heat exchangers of the existing patterns. The review considers plain, louvered, slit, wavy, annular, longitudinal, and serrated fins. This review can be indicated by the status of the research in this area which is important. The comparison of finned tubes heat exchangers shows that those with slit, plain, and wavy finned tubes have the highest values of area goodness factor while the heat exchanger with annular fin shows the lowest. A better heat transfer coefficient ha is found for a heat exchanger with louvered finned and thus should be regarded as the most efficient one, at fixed pumping power per heat transfer area. This study points out that although numerous studies have been conducted on the characteristics of flow and heat transfer in round, elliptical, and flat tubes, studies on some types of streamlined-tubes shapes are limited, especially on wing-shaped tubes (Sayed Ahmed et al. in Heat Mass Transf 50: 1091-1102, 2014; in Heat Mass Transf 51: 1001-1016, 2015). It is recommended that further detailed studies via numerical simulations and/or experimental investigations should be carried out, in the future, to put further insight to these fin designs.

  8. Io: Heat Flow from Dark Volcanic Fields

    NASA Astrophysics Data System (ADS)

    Veeder, G. J.; Matson, D. L.; Davies, A. G.; Johnson, T. V.

    2008-03-01

    We focus on the heat flow contribution from dark volcanic fields on Io. These are concentrated in the anti-Loki hemisphere. We use the areas and estimated effective temperatures of dark flucti to derive their total power.

  9. Heat flow from the West African shield

    SciTech Connect

    Brigaud, F.; Lucazeau, F.; Ly, S.; Sauvage, J.F.

    1985-09-01

    The heat flow over Precambrian shields is generally lower than over other continental provinces. Previous observations at 9 sites of the West African shield have shown that heat flow ranges from 20 mW m/sup -2/ in Niger to 38-42 mW m/sup -2/ in Liberia, Ghana and Nigeria. Since some of these values are lower than expected for Precambrian shields, it is important to find out whether or not they are representative of the entire shield before trying to derive its thermal structure. In this paper, we present new heat flow determinations from seven sites of the West African shield. These indicate that the surface heat flow is comparable with that of other Precambrian shields in the world.

  10. Using simultaneous particle and field observations on a low-altitude satellite to estimate Joule heat energy flow into the high-latitude ionosphere

    SciTech Connect

    Rich, F.J.; Gussenhoven, M.S.; Greenspan, M.E.

    1987-06-01

    This report describes the background, the algorithm for calculating, and the early results of a survey of the Joule heat deposited in the high-latitude ionosphere. The algorithm is based upon data obtained with the polar-orbiting DMSP/F7 spacecraft. A significant portion of the energy input to the high-latitude ionosphere and thermosphere is transmitted from the magnetosphere to the ionosphere via precipitation of electrons and ions and via Joule heat. Several earlier spacecraft of the Defense Meteorological Satellite Program (DMSP) have carried sensors to measure the particle contribution to the energy low. The contribution from the precipitating particles has been extensively surveyed and reported. The DMSP/F7 is the first spacecraft of this series to carry sensors that allow the measurement of parameters which can be used to calculate the Joule heat input. This report is the beginning of a survey of the Joule heat.

  11. Io: Heat flow from dark paterae

    NASA Astrophysics Data System (ADS)

    Veeder, Glenn J.; Davies, Ashley Gerard; Williams, David A.; Matson, Dennis L.; Johnson, Torrence V.; Radebaugh, Jani

    2011-03-01

    Dark paterae on the jovian satellite Io are evidence of recent volcanic activity. Some paterae appear to be entirely filled with dark volcanic material, while others have only partially darkened floors. Dark paterae have area and heat flow longitudinal distributions that are bimodal as well as anti-correlated with the longitudinal distribution of mountains on Io at a global scale. As part of our study of Io’s total heat flow, we have examined the darkest paterae and quantified their thermal emission in order to assess their contribution. This is the first time that the areas of the dark material in these paterae have been measured with such precision and correlated with their thermal emission. Dark paterae yield a significantly larger contribution to Io’s heat flow than dark volcanic fields. Dark paterae (including Loki Patera) yield at least ∼4 × 1013 W or ∼40% of Io’s total heat flow. In comparison, dark flow fields yield ∼1013 W or ∼10% of Io’s total heat flow. Of the total heat loss from dark paterae, Loki Patera alone yields ∼1013 W or ∼10% of Io’s total thermal emission.

  12. Heat Flow of the Norwegian Continental Shelf

    NASA Astrophysics Data System (ADS)

    Pascal, C.

    2015-12-01

    Terrestrial heat flow determination is of prime interest for oil industry because it impacts directly maturation histories and economic potential of oil fields. Published systematic heat flow determinations from major oil provinces are however seldom. Robust heat flow determinations in drillholes require logging of undisturbed temperatures and intensive sampling of core material for petrophysical measurements. Temperature logging in exploration drillholes is traditionally conducted during drill breaks or shortly after drilling, resulting in temperatures severely disturbed by mud circulation and coring is restricted to selected intervals. Alternatively, test temperatures, information from electric logs and lithological descriptions of drill cuttings can be used to overcome these limitations. The present contribution introduces new heat flow determinations based on 63 exploration drillholes from the Norwegian North Sea, the Mid Norway Margin and the Barents Shelf. Our analyses are based on released DST temperatures, precise lithological descriptions of drill cuttings, previously measured rock matrix thermal conductivities and established porosity laws. For the sake of comparison, we carefully review previous heat flow studies carried out both onshore and offshore Norway. Our results suggest median heat flow values of 64 mW/m2, 65 mW/m2 and 72 mW/m2 for the North Sea, the Mid Norway Margin (mainly the Trøndelag Platform) and the SW Barents Shelf respectively. In detail, heat flow increases by ~ 10 mW/m2 from the southern Norwegian North Sea towards the Mid Norway Margin. This result appears to be in very good agreement with seismic tomographic studies suggesting northward thinning of the underlying mantle lithosphere. Our results together with published marine heat flow data from the Mid Norway Margin suggest a gradual decrease in heat flow levels from both the North Sea and the Trøndelag Platform towards the centres of the deep Møre and Vøring basins. This latter

  13. Energy-conserving heat pump-boiler systems for district heating

    SciTech Connect

    Taniguchi, H.; Giedt, W.H.; Kasahara, K.; Kawamura, K.; Kudo, K.; Ohta, J.

    1983-08-01

    The energy saving potential of a proposed heat pump-boiler system for district heating is analyzed. Fuel is supplied to a boiler which generates steam to drive a turbine. The turbine output is used to power a heat pump which takes energy from the environment. Introduction of a screw type expander in place of the throttling valve in the heat pump cycle is planned to increase the system performance. District heating is provided by hot water which is heated as it flows through the condensers in the heat pump and turbine cycles. Both series and parallel connected condenser arrangements are considered. Results show that the heat supplied to the water for district heating can be as high as 200 percent of the heating that would be provided by use of the fuel supplied to a conventional boiler system with a thermal efficiency of 90 percent.

  14. Heat flow and heat generation in greenstone belts

    NASA Technical Reports Server (NTRS)

    Drury, M. J.

    1986-01-01

    Heat flow has been measured in Precambrian shields in both greenstone belts and crystalline terrains. Values are generally low, reflecting the great age and tectonic stability of the shields; they range typically between 30 and 50 mW/sq m, although extreme values of 18 and 79 mW/sq m have been reported. For large areas of the Earth's surface that are assumed to have been subjected to a common thermotectonic event, plots of heat flow against heat generation appear to be linear, although there may be considerable scatter in the data. The relationship is expressed as: Q = Q sub o + D A sub o in which Q is the observed heat flow, A sub o is the measured heat generation at the surface, Q sub o is the reduced heat flow from the lower crust and mantle, and D, which has the dimension of length, represents a scale depth for the distribution of radiogenic elements. Most authors have not used data from greenstone belts in attempting to define the relationship within shields, considering them unrepresentative and preferring to use data from relatively homogeneous crystalline rocks. A discussion follows.

  15. 2007 Estimated International Energy Flows

    SciTech Connect

    Smith, C A; Belles, R D; Simon, A J

    2011-03-10

    An energy flow chart or 'atlas' for 136 countries has been constructed from data maintained by the International Energy Agency (IEA) and estimates of energy use patterns for the year 2007. Approximately 490 exajoules (460 quadrillion BTU) of primary energy are used in aggregate by these countries each year. While the basic structure of the energy system is consistent from country to country, patterns of resource use and consumption vary. Energy can be visualized as it flows from resources (i.e. coal, petroleum, natural gas) through transformations such as electricity generation to end uses (i.e. residential, commercial, industrial, transportation). These flow patterns are visualized in this atlas of 136 country-level energy flow charts.

  16. Heat flow of the Norwegian continental shelf

    NASA Astrophysics Data System (ADS)

    Pascal, Christophe

    2015-04-01

    Terrestrial heat flow influences a large collection of geological processes. Its determination is a requirement to assess the economic potential of deep sedimentary basins. Published heat flow calculations from e.g. major oil provinces are however seldom. Robust heat flow determinations in drillholes require logging of undisturbed temperatures and intensive sampling of core material for petrophysical measurements. Temperature logging in exploration drillholes is traditionally conducted during drill breaks or shortly after drilling, resulting in temperatures severely disturbed by mud circulation and coring is restricted to selected intervals. Alternatively, test temperatures, information from electric logs and lithological descriptions of drill cuttings can be used to overcome these limitations. The present contribution introduces new heat flow determinations based on 63 exploration drillholes from the Norwegian North Sea, the Mid Norway Margin and the Barents Shelf. Our analyses are based on released DST temperatures, precise lithological descriptions of drill cuttings, previously measured rock matrix thermal conductivities and established porosity laws. Our results suggest median heat flow values of 64 mW/m2, 65 mW/m2 and 72 mW/m2 for the North Sea, the Mid Norway Margin (mainly the Trøndelag Platform) and the SW Barents Shelf respectively. The Barents Shelf shows significantly high heat flow, suggesting lateral transfer of heat from the mantle of the adjacent young ocean. In detail, heat flow increases by ~ 10 mW/m2 from the southern Norwegian North Sea towards the Mid Norway Margin. This result appears to be in very good agreement with seismic tomographic studies suggesting northward thinning of the underlying mantle lithosphere. Our results together with published marine heat flow data from the Mid Norway Margin suggest a gradual decrease in heat flow levels from both the North Sea and the Trøndelag Platform towards the centres of the deep Møre and V

  17. Coupling of volatile transport and internal heat flow on Triton

    NASA Technical Reports Server (NTRS)

    Brown, Robert H.; Kirk, Randolph L.

    1994-01-01

    Recently Brown et al. (1991) showed that Triton's internal heat source could amount to 5-20% of the absorbed insolation on Triton, thus significantly affecting volatile transport and atmospheric pressure. Subsequently, Kirk and Brown (1991a) used simple analytical models of the effect of internal heat on the distribution of volatiles on Triton's surface, confirming the speculation of Brown et al. that Triton's internal heat flow could strongly couple to the surface volatile distribution. To further explore this idea, we present numerical models of the permanent distribution of nitrogen ice on Triton that include the effects of sunlight, the two-dimensional distribution of internal heat flow, the coupling of internal heat flow to the surface distribution of nitrogen ice, and the finite viscosity of nitrogen ice. From these models we conclude that: (1) The strong vertical thermal gradient induced in Triton's polar caps by internal heat-flow facilitates viscous spreading to lower latitudes, thus opposing the poleward transport of volatiles by sunlight, and, for plausible viscosities and nitrogen inventories, producing permanent caps of considerable latitudinal extent; (2) It is probable that there is a strong coupling between the surface distribution of nitrogen ice on Triton and internal heat flow; (3) Asymmetries in the spatial distribution of Triton's heat flow, possibly driven by large-scale, volcanic activity or convection in Triton's interior, can result in permanent polar caps of unequal latitudinal extent, including the case of only one permanent polar cap; (4) Melting at the base of a permanent polar cap on Triton caused by internal heat flow can significantly enhance viscous spreading, and, as an alternative to the solid-state greenhouse mechanism proposed by Brown et al. (1990), could provide the necessary energy, fluids, and/or gases to drive Triton's geyser-like plumes; (5) The atmospheric collapse predicted to occur on Triton in the next 20 years

  18. Azimuthal Stress and Heat Flux In Radiatively Inefficient Accretion Flows

    NASA Astrophysics Data System (ADS)

    Devlen, Ebru

    2016-07-01

    Radiatively Inefficient Accretion Flows (RIAFs) have low radiative efficiencies and/or low accretion rates. The accreting gas may retain most of its binding energy in the form of heat. This lost energy for hot RIAFs is one of the problems heavily worked on in the literature. RIAF observations on the accretion to super massive black holes (e.g., Sagittarius A* in the center of our Galaxy) have shown that the observational data are not consistent with either advection-dominated accretion flow (ADAF) or Bondi models. For this reason, it is very important to theoretically comprehend the physical properties of RIAFs derived from observations with a new disk/flow model. One of the most probable candidates for definition of mass accretion and the source of excess heat energy in RIAFs is the gyroviscous modified magnetorotational instability (GvMRI). Dispersion relation is derived by using MHD equations containing heat flux term based on viscosity in the energy equation. Numerical solutions of the disk equations are done and the growth rates of the instability are calculated. This additional heat flux plays an important role in dissipation of energy. The rates of the angular momentum and heat flux which are obtained from numerical calculations of the turbulence brought about by the GVMRI are also discussed.

  19. Aerodynamic heating in hypersonic flows

    NASA Technical Reports Server (NTRS)

    Reddy, C. Subba

    1993-01-01

    Aerodynamic heating in hypersonic space vehicles is an important factor to be considered in their design. Therefore the designers of such vehicles need reliable heat transfer data in this respect for a successful design. Such data is usually produced by testing the models of hypersonic surfaces in wind tunnels. Most of the hypersonic test facilities at present are conventional blow-down tunnels whose run times are of the order of several seconds. The surface temperatures on such models are obtained using standard techniques such as thin-film resistance gages, thin-skin transient calorimeter gages and coaxial thermocouple or video acquisition systems such as phosphor thermography and infrared thermography. The data are usually reduced assuming that the model behaves like a semi-infinite solid (SIS) with constant properties and that heat transfer is by one-dimensional conduction only. This simplifying assumption may be valid in cases where models are thick, run-times short, and thermal diffusivities small. In many instances, however, when these conditions are not met, the assumption may lead to significant errors in the heat transfer results. The purpose of the present paper is to investigate this aspect. Specifically, the objectives are as follows: (1) to determine the limiting conditions under which a model can be considered a semi-infinite body; (2) to estimate the extent of errors involved in the reduction of the data if the models violate the assumption; and (3) to come up with correlation factors which when multiplied by the results obtained under the SIS assumption will provide the results under the actual conditions.

  20. Temperature-gated thermal rectifier for active heat flow control.

    PubMed

    Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

    2014-08-13

    Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage.

  1. Joule heating effects on electroosmotic entry flow.

    PubMed

    Prabhakaran, Rama Aravind; Zhou, Yilong; Patel, Saurin; Kale, Akshay; Song, Yongxin; Hu, Guoqing; Xuan, Xiangchun

    2017-03-01

    Electroosmotic flow is the transport method of choice in microfluidic devices over traditional pressure-driven flow. To date, however, studies on electroosmotic flow have been almost entirely limited to inside microchannels. This work presents the first experimental study of Joule heating effects on electroosmotic fluid entry from the inlet reservoir (i.e., the well that supplies fluids and samples) to the microchannel in a polymer-based microfluidic chip. Electrothermal fluid circulations are observed at the reservoir-microchannel junction, which grow in size and strength with the increasing alternating current to direct current voltage ratio. Moreover, a 2D depth-averaged numerical model is developed to understand the effects of Joule heating on fluid temperature and flow fields in electrokinetic microfluidic chips. This model overcomes the problems encountered in previous unrealistic 2D and costly 3D models, and is able to predict the observed electroosmotic entry flow patterns with a good agreement.

  2. Numerical methods and calculations for droplet flow, heating and ignition

    NASA Technical Reports Server (NTRS)

    Dwyer, H. A.; Sanders, B. R.; Dandy, D.

    1982-01-01

    A numerical method was devised and employed to solve a variety of problems related to liquid droplet combustion. The basic transport equations of mass, momentum and energy were formulated in terms of generalized nonorthogonal coordinates, which allows for adaptive griding and arbitrary particle shape. Example problems are solved for internal droplet heating, droplet ignition and high Reynolds number flow over a droplet.

  3. Method for identifying anomalous terrestrial heat flows

    DOEpatents

    Del Grande, Nancy Kerr

    1977-01-25

    A method for locating and mapping the magnitude and extent of terrestrial heat-flow anomalies from 5 to 50 times average with a tenfold improved sensitivity over orthodox applications of aerial temperature-sensing surveys as used for geothermal reconnaissance. The method remotely senses surface temperature anomalies such as occur from geothermal resources or oxidizing ore bodies by: measuring the spectral, spatial, statistical, thermal, and temporal features characterizing infrared radiation emitted by natural terrestrial surfaces; deriving from these measurements the true surface temperature with uncertainties as small as 0.05 to 0.5 K; removing effects related to natural temperature variations of topographic, hydrologic, or meteoric origin, the surface composition, detector noise, and atmospheric conditions; factoring out the ambient normal-surface temperature for non-thermally enhanced areas surveyed under otherwise identical environmental conditions; distinguishing significant residual temperature enhancements characteristic of anomalous heat flows and mapping the extent and magnitude of anomalous heat flows where they occur.

  4. Energy dissipation in sheared granular flows

    SciTech Connect

    Karion, A.; Hunt, M.L.

    1999-11-01

    Granular material flows describe flows of solid particles in which the interstitial fluid plays a negligible role in the flow mechanics. Examples include the transport of coal, food products, detergents, pharmaceutical tablets, and toner particles in high-speed printers. Using a two-dimensional discrete element computer simulation of a bounded, gravity-free Couette flow of particles, the heat dissipation rate per unit area is calculated as a function of position in the flow as well as overall solid fraction. The computation results compare favorably with the kinetic theory analysis for rough disks. The heat dissipation rate is also measured for binary mixtures of particles for different small to large solid fraction ratios, and for diameter ratios of ten, five, and two. The dissipation rates increase significantly with overall solid fraction as well as local strain rates and granular temperatures. The thermal energy equation is solved for a Couette flow with one adiabatic wall and one at constant temperature. Solutions use the simulation measurements of the heat dissipation rate, solid fraction, and granular temperature to show that the thermodynamic temperature increases with solid fraction and decreases with particle conductivity. In mixtures, both the dissipation rate and the thermodynamic temperature increase with size ratio and with decreasing ratio of small to large particles.

  5. Colorado Heat Flow Data from IHFC

    DOE Data Explorer

    Zehner, Richard E.

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Originator: The International Heat Flow Commission (IHFC) Publication Date: 2012 Title: Colorado IHFC Data Edition: First Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: Abstract: This layer contains the heat flow sites and data of the State of Colorado compiled from the International Heat Flow Commission (IHFC) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI) global heat flow database (www.heatflow.und.edu/index2.html). The data include different items: Item number, descriptive code, name of site, latitude and longitude, elevation, depth interval, number of temperature data, temperature gradient, number of conductivity measurement, average conductivity, number of heat generation measurements, average heat production, heat flow, number of individual sites, references, and date of publication. Spatial Domain: Extent: Top: 4522121.800672 m Left: 165356.134075 m Right: 621836.776246 m Bottom: 4097833.419676 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude Of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System 1984 (WGS ’1984) Prime Meridian: Greenwich

  6. A Numerical Method for Incompressible Flow with Heat Transfer

    NASA Technical Reports Server (NTRS)

    Sa, Jong-Youb; Kwak, Dochan

    1997-01-01

    A numerical method for the convective heat transfer problem is developed for low speed flow at mild temperatures. A simplified energy equation is added to the incompressible Navier-Stokes formulation by using Boussinesq approximation to account for the buoyancy force. A pseudocompressibility method is used to solve the resulting set of equations for steady-state solutions in conjunction with an approximate factorization scheme. A Neumann-type pressure boundary condition is devised to account for the interaction between pressure and temperature terms, especially near a heated or cooled solid boundary. It is shown that the present method is capable of predicting the temperature field in an incompressible flow.

  7. Heat transfer mechanisms in microgravity flow boiling.

    PubMed

    Ohta, Haruhiko

    2002-10-01

    The objective of this paper is to clarify the mechanisms of heat transfer and dryout phenomena in flow boiling under microgravity conditions. Liquid-vapor behavior in annular flow, encountered in the moderate quality region, has extreme significance for practical application in space. To clarify the gravity effect on the heat transfer observed for an upward flow in a tube, the research described here started from the measurement of pressure drop for binary gas-liquid mixture under various gravity conditions. The shear stress acting on the surface of the annular liquid film was correlated by an empirical method. Gravity effects on the heat transfer due to two-phase forced convection were investigated by the analysis of velocity and temperature profiles in the film. The results reproduce well the trends of heat transfer coefficients varying with the gravity level, quality, and mass velocity. Dryout phenomena in the moderate quality region were observed in detail by the introduction of a transparent heated tube. At heat fluxes just lower and higher than CHF value, a transition of the heat transfer coefficient was calculated from oscillating wall temperature, where a series of opposing heat transfer trends--the enhancement due to the quenching of dried areas or evaporation from thin liquid films and the deterioration due to the extension of dry patches--were observed between the passage of disturbance waves. The CHF condition that resulted from the insufficient decrease of wall temperature in the period of enhanced heat transfer was overcome by a temperature increase in the deterioration period. No clear effect of gravity on the mechanisms of dryout was observed within the range of experiments.

  8. Performance of parallel flow HeII heat exchangers

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Chang, Y.; Witt, R. J.; Van Sciver, S. W.

    Previous studies of HeII heat exchangers have focused on tube-in-shell designs. The present paper examines the properties of a parallel flow HeII heat exchanger formed from two 254 mm lengths of copper channel having nominal rectangular dimensions 2 mm × 4 mm. Heaters positioned at the inlets and outlets of both channels permit the simulation of a variety of physically plausible boundary conditions. An iterative numerical method, based on one-dimensional energy balances in each channel with coupling through a heat transfer term, is presented and agrees well with the experimental results. As with tube-in-shell designs, parallel flow HeII heat exchangers may exhibit unusual temperature profiles.

  9. Solar Energy for Space Heating & Hot Water.

    ERIC Educational Resources Information Center

    Energy Research and Development Administration, Washington, DC. Div. of Solar Energy.

    This pamphlet reviews the direct transfer of solar energy into heat, particularly for the purpose of providing space and hot water heating needs. Owners of buildings and homes are provided with a basic understanding of solar heating and hot water systems: what they are, how they perform, the energy savings possible, and the cost factors involved.…

  10. ENERGY STAR Certified Geothermal Heat Pumps

    EPA Pesticide Factsheets

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Geothermal Heat Pumps that are effective as of January 1, 2012. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=geo_heat.pr_crit_geo_heat_pumps

  11. Hot Topics! Heat Pumps and Geothermal Energy

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2009-01-01

    The recent rapid rises in the cost of energy has significantly increased interest in alternative energy sources. The author discusses the underlying principles of heat pumps and geothermal energy. Related activities for technology education students are included.

  12. Energy and material flows of megacities

    PubMed Central

    Kennedy, Christopher A.; Stewart, Iain; Facchini, Angelo; Cersosimo, Igor; Mele, Renata; Chen, Bin; Uda, Mariko; Kansal, Arun; Chiu, Anthony; Kim, Kwi-gon; Dubeux, Carolina; Lebre La Rovere, Emilio; Cunha, Bruno; Pincetl, Stephanie; Keirstead, James; Barles, Sabine; Pusaka, Semerdanta; Gunawan, Juniati; Adegbile, Michael; Nazariha, Mehrdad; Hoque, Shamsul; Marcotullio, Peter J.; González Otharán, Florencia; Genena, Tarek; Ibrahim, Nadine; Farooqui, Rizwan; Cervantes, Gemma; Sahin, Ahmet Duran

    2015-01-01

    Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world’s 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001–2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth. PMID:25918371

  13. Energy and material flows of megacities.

    PubMed

    Kennedy, Christopher A; Stewart, Iain; Facchini, Angelo; Cersosimo, Igor; Mele, Renata; Chen, Bin; Uda, Mariko; Kansal, Arun; Chiu, Anthony; Kim, Kwi-Gon; Dubeux, Carolina; Lebre La Rovere, Emilio; Cunha, Bruno; Pincetl, Stephanie; Keirstead, James; Barles, Sabine; Pusaka, Semerdanta; Gunawan, Juniati; Adegbile, Michael; Nazariha, Mehrdad; Hoque, Shamsul; Marcotullio, Peter J; González Otharán, Florencia; Genena, Tarek; Ibrahim, Nadine; Farooqui, Rizwan; Cervantes, Gemma; Sahin, Ahmet Duran

    2015-05-12

    Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world's 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001-2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.

  14. Optimization of Transient Heat Exchanger Performance for Improved Energy Efficiency

    NASA Astrophysics Data System (ADS)

    Bran Anleu, Gabriela; Kavehpour, Pirouz; Lavine, Adrienne; Wirz, Richard

    2014-11-01

    Heat exchangers are used in a multitude of applications within systems for energy generation, energy conversion, or energy storage. Many of these systems (e.g. solar power plants) function under transient conditions, but the design of the heat exchangers is typically optimized assuming steady state conditions. There is a potential for significant energy savings if the transient behavior of the heat exchanger is taken into account in designing the heat exchanger by optimizing its operating conditions in relation to the transient behavior of the overall system. The physics of the transient behavior of a heat exchanger needs to be understood to provide design parameters for transient heat exchangers to deliver energy savings. A numerical model was used to determine the optimized mass flow rates thermal properties for a thermal energy storage system. The transient behavior is strongly linked to the dimensionless parameters relating fluid properties, the mass flow rates, and the temperature of the fluids at the inlet of each stream. Smart metals, or advanced heat exchanger surface geometries and methods of construction will be used to meet the three goals mentioned before: 1) energy and cost reduction, 2) size reduction, and 3) optimal performance for all modes of operation.

  15. Heat flow-heat production relationship not found: what drives heat flow variability of the Western Canadian foreland basin?

    NASA Astrophysics Data System (ADS)

    Majorowicz, Jacek A.

    2016-06-01

    Heat flow high -80 ± 10 mW/m2 in the northern western parts of the Western Canadian foreland basin is in large contrast to low heat flow to the south and east (50 ± 7 mW/m2) of the same basin with the same old 2E09 year's Precambrian basement and some 200-km-thick lithosphere. Over-thrusted and flat-laying sedimentary units are heated from below by heat flow from the old craton' crust and low 15 ± 5 mW/m2 mantle contribution. The heat flow vs. radiogenic heat production statistical relationship is not found for this area. To account for this large heat flow contrast and to have 200-km-thick lithosphere, we would need to assume that high heat production layer of the upper crust varies in thickness as much as factor of 2 and/or that the measured heat production at top of Precambrian basement is not representative for deeper rocks. The other explanation proposed before that heat in the basin is redistributed by the regional fluid flow systems driven from high hydraulic head areas close to the foothills of the Rocky Mountains toward low elevation areas to the east and north cannot be explained by observed low Darcy fluid velocities and the geometry of the basin.

  16. Numberical Solution to Transient Heat Flow Problems

    ERIC Educational Resources Information Center

    Kobiske, Ronald A.; Hock, Jeffrey L.

    1973-01-01

    Discusses the reduction of the one- and three-dimensional diffusion equation to the difference equation and its stability, convergence, and heat-flow applications under different boundary conditions. Indicates the usefulness of this presentation for beginning students of physics and engineering as well as college teachers. (CC)

  17. Improved Heat-of-Fusion Energy Storage

    NASA Technical Reports Server (NTRS)

    Chen, K. H.; Manvi, R.

    1982-01-01

    Alkali metal/alkali-halide mixtures proposed for preventing solid buildup during energy recovery. When mixture melts (by absorption of heat of fusion), it forms two immiscible liquids. Salt-rich phase is heavier and has higher melting/recrysallization temperature; so during energy recovery salt crystallizes in this phase first. Since heat exchanger for energy recovery is in lighter metal-rich phase, solids do not form and there is no reduction of heat-recovery efficiency.

  18. Heat flow and energetics of the San Andreas fault zone.

    USGS Publications Warehouse

    Lachenbruch, A.H.; Sass, J.H.

    1980-01-01

    Approximately 100 heat flow measurements in the San Andreas fault zone indicate 1) there is no evidence for local frictional heating of the main fault trace at any latitude over a 1000-km length from Cape Mendocino to San Bernardino, 2) average heat flow is high (ca.2 HFU, ca.80 mW m-2) throughout the 550-km segment of the Coast Ranges that encloses the San Andreas fault zone in central California; this broad anomaly falls off rapidly toward the Great Valley to the east, and over a 200-km distance toward the Mendocino Triple Junction to the northwest. As others have pointed out, a local conductive heat flow anomaly would be detectable unless the frictional resistance allocated to heat production on the main trace were less than 100 bars. Frictional work allocated to surface energy of new fractures is probably unimportant, and hydrologic convection is not likely to invalidate the conduction assumption, since the heat discharge by thermal springs near the fault is negligible. -Authors

  19. Turbulent Heat Transfer in Ribbed Pipe Flow

    NASA Astrophysics Data System (ADS)

    Kang, Changwoo; Yang, Kyung-Soo

    2012-11-01

    From the view point of heat transfer control, surface roughness is one of the popular ways adopted for enhancing heat transfer in turbulent pipe flow. Such a surface roughness is often modeled with a rib. In the current investigation, Large Eddy Simulation has been performed for turbulent flow in a pipe with periodically-mounted ribs at Reτ=700, Pr=0.71, and p / k =2, 4, and 8. Here, p and k represent the pitch and rib height, respectively. The rib height is fixed as one tenth of the pipe radius. The profiles of mean velocity components, mean temperature, root-mean-squares (rms) of temperature fluctuation are presented at the selected streamwise locations. In comparison with the smooth-pipe case at the same Re and Pr, the effects of the ribs are clearly identified, leading to overall enhancement of turbulent heat transfer in terms of Nu. The budget of temperature variance is presented in the form of contours. The results of an Octant analysis are also given to elucidate the dominant events. Our LES results shed light on a complete understanding of the heat-transfer mechanisms in turbulent ribbed-pipe flow which has numerous applications in engineering. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2012013019).

  20. Triaxial thermopile array geo-heat-flow sensor

    DOEpatents

    Carrigan, C.R.; Hardee, H.C.; Reynolds, G.D.; Steinfort, T.D.

    1990-01-01

    A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings. 6 figs.

  1. Triaxial thermopile array geo-heat-flow sensor

    DOEpatents

    Carrigan, Charles R.; Hardee, Harry C.; Reynolds, Gerald D.; Steinfort, Terry D.

    1992-01-01

    A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers arranged in a vertical string. The transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings.

  2. Hot dry rock heat mining: An alternative energy progress report

    SciTech Connect

    Duchane, D.V.

    1991-01-01

    Mining Heat from the hot dry rock (HDR) resource that lies beneath the earth's crust may provide an almost inexhaustible supply of energy for mankind with minimal environmental effects. In the heat mining process, water is pumped down an injection well into a mass of hydraulically fractured hot rock. As the water flows under high pressure through the opened rock joints, it becomes heated by the rock. It is returned to the surface through a production well (or wells) located some distance from the injector where its thermal energy is recovered by a heat exchanger. The same water is then recirculated through the system to extract more thermal energy. In this closed-loop process, nothing but heat is released to the environment during normal operation. The technical feasibility of HDR heat mining already has been proven by field testing. A long-term flow test is scheduled to begin in 1991 at the world's largest HDR heat mine in New Mexico, USA, to demonstrate that energy can be produced from HDR on a continuous basis over an extended time period. Significant HDR programs are also underway in several other countries. The paper describes the HDR resource, the heat mining concept, environmental characteristics, economics, developments at Los Alamos to date, and HDR development outside the US. 15 refs., 5 figs., 2 tabs.

  3. Calibrated Heat Flow Model for Determining the Heat Conduction Losses in Laser Cutting of CFRP

    NASA Astrophysics Data System (ADS)

    Mucha, P.; Weber, R.; Speker, N.; Berger, P.; Sommer, B.; Graf, T.

    Laser machining has great potential regarding automation in fabrication of CFRP (carbon-fiber-reinforced plastics) parts, due to the nearly force and tool-wear free processing at high process speeds. The high vaporization temperatures and the large heat conductivity of the carbon fibers lead to a large heat transport into the sample. This causes the formation of a heat-affected zone and a decrease of the process speed. In the present paper,an analytical heat flow model was adapted in order to understand and investigate the heat conduction losses. Thermal sensors were embedded in samples at different distances from the kerf to fit the calculated to the measured temperatures. Heat conduction losses of up to 30% of the laser power were determined. Furthermore, the energy not absorbed by the sample, the energy for sublimating the composite material in the kerf, the energy for the formation of the HAZ, and the residual heat in the sample are compared in an energy balance.

  4. Transient behavior of heat pipe with thermal energy storage under pulse heat loads

    NASA Astrophysics Data System (ADS)

    Chang, Ming-, Jr.

    1991-02-01

    Future space missions will require thermal transport devices with the ability to handle transient pulse heat loads. A novel design of a high-temperature axially grooved heat pipe (HP) which incorporates thermal energy storage (TES) to migrate pulse heat loads was presented. A phase-change material (PCM) which is encapsulated in cylindrical containers was used for the thermal energy storage. The transient response of the HP/TES system under two different types of pulse heat loads was studied analytically. The first type is pulse heat loads applied at the heat pipe evaporator, the second type is reversed-pulse heat loads applied at the condenser. In this research, a new three-dimensional alternating-direction-implicit (ADI) method was developed to model the heat conduction through the heat pipe wall and wicks, including the liquid flow in grooves. A very important characteristic of this new ADI method is that it is consistent with physical considerations. Compared with the well-known Brian's and Douglas's ADI methods, this new ADI method had higher accuracy and requires less computer storage. In the numerical solution of heat transfer problems with phase change (Stefan-type problem), a modified Pham's method which includes features from enthalpy and heat capacity methods was used to simulate the melting and solidification processes of the PCG. The vapor flow was assumed quasi-steady and one-dimensional, and was coupled with the evaporation and condensation on the heat pipe inside wall surface and the surfaces of the PCM containers. The transient responses of three different HP/TES configurations were compared: (1) a heat pipe with a large empty cylinder installed in the vapor core, (2) a heat pipe with a large PCM cylinder, and (3) a heat pipe with six small PCM cylinders. From the numerical results, it was found that the PCM is very effective in mitigrating the adverse effect of pulse heat loads. The six small PCM cylinders are more efficient than the large PCM

  5. The Energy Impacts of Solar Heating.

    ERIC Educational Resources Information Center

    Whipple, Chris

    1980-01-01

    The energy required to build and install solar space- and water-heating equipment is compared to the energy saved under two solar growth paths corresponding to high and low rates of solar technology implementation. (Author/RE)

  6. The energy impacts of solar heating.

    PubMed

    Whipple, C

    1980-04-18

    The energy required to build and install solar space- and water-heating equipment is compared to the energy it saves under two solar growth paths corresponding to high and low rates of implementation projected by the Domestic Policy Review of Solar Energy. For the rapid growth case, the cumulative energy invested to the year 2000 is calculated to be (1/2) to 1(1/2) times the amount saved. An impact of rapid solar heating implementation is to shift energy demand from premium heating fuels (natural gas and oil) to coal and nuclear power use in the industries that provide materials for solar equipment.

  7. Critical heat flux in subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Hall, David Douglas

    The critical heat flux (CHF) phenomenon was investigated for water flow in tubes with particular emphasis on the development of methods for predicting CHF in the subcooled flow boiling regime. The Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) CHF database for water flow in a uniformly heated tube was compiled from the world literature dating back to 1949 and represents the largest CHF database ever assembled with 32,544 data points from over 100 sources. The superiority of this database was proven via a detailed examination of previous databases. The PU-BTPFL CHF database is an invaluable tool for the development of CHF correlations and mechanistic models that are superior to existing ones developed with smaller, less comprehensive CHF databases. In response to the many inaccurate and inordinately complex correlations, two nondimensional, subcooled CHF correlations were formulated, containing only five adjustable constants and whose unique functional forms were determined without using a statistical analysis but rather using the parametric trends observed in less than 10% of the subcooled CHF data. The correlation based on inlet conditions (diameter, heated length, mass velocity, pressure, inlet quality) was by far the most accurate of all known subcooled CHF correlations, having mean absolute and root-mean-square (RMS) errors of 10.3% and 14.3%, respectively. The outlet (local) conditions correlation was the most accurate correlation based on local CHF conditions (diameter, mass velocity, pressure, outlet quality) and may be used with a nonuniform axial heat flux. Both correlations proved more accurate than a recent CHF look-up table commonly employed in nuclear reactor thermal hydraulic computer codes. An interfacial lift-off, subcooled CHF model was developed from a consideration of the instability of the vapor-liquid interface and the fraction of heat required for liquid-vapor conversion as opposed to that for bulk liquid heating. Severe

  8. Energy-efficient water heating

    SciTech Connect

    1995-01-01

    This fact sheet describes how to reduce the amount of hot water used in faucets and showers, automatic dishwashers, and washing machines; how to increase water-heating system efficiency by lowering the water heater thermostat, installing a timer and heat traps, and insulating hot water pipes and the storage tank; and how to use off-peak power to heat water. A resource list for further information is included.

  9. Solar energy for industrial process heat

    NASA Technical Reports Server (NTRS)

    Barbieri, R. H.; Pivirotto, D. L.

    1979-01-01

    Findings of study of potential use for solar energy utilization by California dairy industry, prove that applicable solar energy system furnish much of heat needed for milk processing with large savings in expenditures for oil and gas and ensurance of adequate readily available sources of process heat.

  10. Fluid flow nozzle energy harvesters

    NASA Astrophysics Data System (ADS)

    Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Winn, Tyler; Tosi, Luis Phillipe; Colonius, Tim

    2015-04-01

    Power generation schemes that could be used downhole in an oil well to produce about 1 Watt average power with long-life (decades) are actively being developed. A variety of proposed energy harvesting schemes could be used to extract energy from this environment but each of these has their own limitations that limit their practical use. Since vibrating piezoelectric structures are solid state and can be driven below their fatigue limit, harvesters based on these structures are capable of operating for very long lifetimes (decades); thereby, possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. An initial survey [1] identified that spline nozzle configurations can be used to excite a vibrating piezoelectric structure in such a way as to convert the abundant flow energy into useful amounts of electrical power. This paper presents current flow energy harvesting designs and experimental results of specific spline nozzle/ bimorph design configurations which have generated suitable power per nozzle at or above well production analogous flow rates. Theoretical models for non-dimensional analysis and constitutive electromechanical model are also presented in this paper to optimize the flow harvesting system.

  11. On the self-heating phenomenon in nonmodal shear flow

    SciTech Connect

    Li, J.W.; Chen, Y.; Li, Z.Y.

    2006-04-15

    In this article, the nonmodal self-heating phenomenon of linear shear flow [A. D. Rogava, Astrophys. Space Sci. 293, 189 (2004)] is investigated with an initially excited Alfvenic perturbation focusing on the factors determining the efficiency of the heating process. It is found that to get an efficient self-heating process, the initial Alfven wave must be at least partially transformed into the fast mode. This is because only the fast mode, among the three types of magnetohydrodynamic modes, can get amplified significantly by the shear flow. This requires the initial wave number along the shear to be positive so that the Spatial Fourier Harmonics can pass through the degeneration region, and also puts constraints on the plasma parameter {beta} [{beta}=C{sub S}{sup 2}/V{sub A}{sup 2}, where C{sub S} (V{sub A}) is the sound (Alfvenic) velocity]. It is shown that the self-heating function, which represents the total energy dissipated at a certain time, decreases monotonically with increasing {beta}. In addition, to get efficient heating the viscous coefficient should be in an appropriate range. A smaller viscosity results in an insufficient thermalization of the perturbation energy, while a larger one corresponds to a suppressed nonmodal amplification.

  12. High Energy Antimatter Telescope (HEAT) Balloon Experiment

    NASA Technical Reports Server (NTRS)

    Beatty, J. J.

    1995-01-01

    This grant supported our work on the High Energy Antimatter Telescope(HEAT) balloon experiment. The HEAT payload is designed to perform a series of experiments focusing on the cosmic ray positron, electron, and antiprotons. Thus far two flights of the HEAT -e+/- configuration have taken place. During the period of this grant major accomplishments included the following: (1) Publication of the first results of the 1994 HEAT-e+/- flight in Physical Review Letters; (2) Successful reflight of the HEAT-e+/- payload from Lynn Lake in August 1995; (3) Repair and refurbishment of the elements of the HEAT payload damaged during the landing following the 1995 flight; and (4) Upgrade of the ground support equipment for future flights of the HEAT payload.

  13. Mass and energy flow near sunspots

    NASA Technical Reports Server (NTRS)

    Nye, Alan; Bruning, David; Labonte, Barry J.

    1988-01-01

    Sunspots block the flow of energy to the solar surface. The blocked energy heats the volume beneath the spot, producing a pressure excess which drives an outflow of mass. Linear numerical models of the mass and energy flow around spots were constructed to estimate the predictions of this physical picture against the observed properties of sunspot bright rings and moat flows. The width of the bright ring and moat are predicted to be proportional to the depth of the spot penumbra, in conflict with the observed proportionality of the moat width to the spot diameter. Postulating that spot depths are proportional to spot diameters would bury the moat flow too deeply to be observed, because the radial velocity at the surface is found to be inversely proportional to the depth of the spot penumbra. The radial velocity at the surface is of order a few hundred meters per second after 1 day, in agreement with the observed excess of moat velocities over supergranule velocities.

  14. Geomechanical Fracturing with Flow and Heat

    SciTech Connect

    2009-01-01

    The GeoFracFH model is a particle-based discrete element model (DEM) that has been coupled with fluid flow and heat conduction/convection. In this model, the rock matrix material is represented by a network of DEM particles connected by mechanical bonds (elastic beams in this case, see Figure 1, gray particles connected by beams). During the simulation process, the mechanical bonds that have been stretched or bent beyond a critical strain (both tensile and shear failures are simulated) are broken and removed from the network in a progressive manner. Bonds can be removed from the network with rates or probabilities that depend on their stress or strain, or the properties of the discrete elements and bonds can be varied continuously to represent phenomena such as creep, strain hardening, and chemical degradation. The coupling of a DEM geomechanical model with models for Darcy flow and heat transport is also illustrated in Figure 1. Darcy flow and heat transport equations are solved on an underlying fixed finite difference grid with evolving porosity and permeability for each grid cell that depends on the local structure of the discrete element network (such as the DEM particle density). The fluid pressure gradient exerts forces on individual elements of the DEM network, which then deforms and fractures the rock matrix. The deformation/fracturing in turn changes the permeability which again changes the evolution of fluid pressure, coupling the two phenomena. The intimate coupling between fracturing, fluid flow, and thermal transport makes the GeoFracFH model, rather than conventional continuum mechanical models, necessary for coupled hydro-thermal-mechanical problems in the subsurface.

  15. New and classical applications of heat flow studies

    NASA Astrophysics Data System (ADS)

    Clauser, C.

    2005-12-01

    become widely recognized as a valuable supplement to established climate proxies. In contrast to these, GST is directly linked to climate-related temperature variations. It is based in a straightforward manner on heat transport and thermal physics and, in contrast to climate proxies, does not require transfer functions for relating temperature-sensitive phenomena to temperature.The second new application makes use of the signature of heat advection to identify and quantify flow in the deep subsurface. Based on high-quality data of sufficient number and distribution, the method's detection limit is far below that of any other technique. These are but two examples where, under a new perspective, noise has turned into signal. Last but not least, the potential of geothermal energy to supply low-pollution, low-carbon-dioxide electric power and heat has been recognized and exploited for more than 100 years, primarily in tectonically active regions with natural steam reservoirs. However, the ever-increasing price of fossil fuels and their exhaust of greenhouse gases have turned geothermal energy into an attractive option, even in geothermally less favourable regions. In this more demanding situation, understanding different heat transport processes requires more refined techniques for data correction, parameter identification and numerical simulation. This special issue comprises a selection of 11 papers which emerged from this meeting. Corresponding to the scope of the meeting, four papers address paleoclimatic topics, four papers deal with topics related to subsurface flow, and five papers discuss various aspects related directly or indirectly to geothermal energy. Thus, this special issue reflects exciting trends in current geothermal research. It illustrates that today geothermal research comprises new and challenging fields, with applications in environmental sciences, reservoir engineering, and climate and energy research.

  16. A coupled heat and water flow apparatus

    SciTech Connect

    Mohamed, A.M.O.; Caporouscio, F.; Yong, R.N. ); Cheung, C.H. ); Kjartanson, B.H. )

    1993-03-01

    Safe and permanent disposal of radioactive waste requires isolation of a number of diverse chemical elements form the environment. The Canadian Nuclear Fuel Waste Management Program is assessing the concept of disposing of waste in a vault excavated at a depth of 500 to 1000 m below the ground surface in plutonic rock of the Canadian Shield. The temperatures and hydraulic potential in the buffer and back fill material were investigated. To study the performance of a compacted buffer material under thermal and isothermal conditions, a coupled heat and water flow apparatus is designed and presented. In the preliminary design, a one-dimensional flow of heat and water was not achieved. however, control of temperature gradient, existence of one-dimensional flow, and uniformity of temperature and volumetric water content distributions at any cross section within the specimen are achieved in the modified design. Experimental results have shown that the temperature stabilizes very rapidly after a period of approximately 0. 107 days. The moisture moves away from the hot end along the longitudinal direction of the specimen due to imposed thermal gradient. The time required for moisture to stabilize is in order of days. 17 refs., 17 figs., 3 tabs.

  17. Heat energy of various ignition sparks

    NASA Technical Reports Server (NTRS)

    Silsbee, F B; Loeb, L B; Fonseca, E L

    1920-01-01

    This report describes a method developed at the Bureau of Standards for measuring the total energy liberated as heat in a spark gap by an ignition system. Since this heat energy is obtained from the electromagnetic energy stored in the windings of the magneto or coil, it is a measure of the effectiveness of the device as an electric generator. Part 2 gives the results of measurements in absolute units of the total heat supplied to a spark gap by ignition systems of different types operating at various speeds, under conditions substantially equivalent to those in the cylinder of a high-compression aviation engine.

  18. Flow Visualization and Heat Transfer Characteristics of Liquid Jet Impingement

    NASA Astrophysics Data System (ADS)

    Jafar, Farial A.; Thorpe, Graham R.; Turan, Özden F.

    2012-07-01

    Equipment used to cool horticultural produce often involves three-phase porous media. The flow field and heat transfer processes that occur in such equipment are generally quantified by means of empirical relationships amongst dimensionless groups. This work represents a first step towards the goal of harnessing the power of computational fluid dynamics (CFD) to better understand the heat transfer processes that occur in beds of irrigated horticultural produce. The primary objective of the present study is to use numerical predictions towards reducing the energy and cooling water requirement in cooling horticultural produce. In this paper, flow and heat transfer predictions are presented of a single slot liquid jet impinging on flat and curved surfaces using a CFD code (FLUENT) for 2D configurations. The effects of Reynolds number, nozzle to plate spacing, nozzle width, and target surface configuration have been studied. Reynolds numbers of 250, 375, 500, 700, 1000, 1500, 1800, and 1900 are studied where the liquid medium is water. Here, the Reynolds number is defined in terms of the hydraulic nozzle diameter, inlet jet velocity, and fluid kinematic viscosity. The results show that Reynolds numbers, nozzle to plate spacing, and nozzle width have a significant effect on the flow field and heat transfer characteristics, whereas the target surface configuration at the stagnation area has no substantial impact. The use of a numerical tool has resulted in a detailed investigation of these characteristics, which has not been available in the literature previously.

  19. Capture of Heat Energy from Diesel Engine Exhaust

    SciTech Connect

    Chuen-Sen Lin

    2008-12-31

    Diesel generators produce waste heat as well as electrical power. About one-third of the fuel energy is released from the exhaust manifolds of the diesel engines and normally is not captured for useful applications. This project studied different waste heat applications that may effectively use the heat released from exhaust of Alaskan village diesel generators, selected the most desirable application, designed and fabricated a prototype for performance measurements, and evaluated the feasibility and economic impact of the selected application. Exhaust flow rate, composition, and temperature may affect the heat recovery system design and the amount of heat that is recoverable. In comparison with the other two parameters, the effect of exhaust composition may be less important due to the large air/fuel ratio for diesel engines. This project also compared heat content and qualities (i.e., temperatures) of exhaust for three types of fuel: conventional diesel, a synthetic diesel, and conventional diesel with a small amount of hydrogen. Another task of this project was the development of a computer-aided design tool for the economic analysis of selected exhaust heat recovery applications to any Alaskan village diesel generator set. The exhaust heat recovery application selected from this study was for heating. An exhaust heat recovery system was fabricated, and 350 hours of testing was conducted. Based on testing data, the exhaust heat recovery heating system showed insignificant effects on engine performance and maintenance requirements. From measurements, it was determined that the amount of heat recovered from the system was about 50% of the heat energy contained in the exhaust (heat contained in exhaust was evaluated based on environment temperature). The estimated payback time for 100% use of recovered heat would be less than 3 years at a fuel price of $3.50 per gallon, an interest rate of 10%, and an engine operation of 8 hours per day. Based on experimental data

  20. Electroosmotic flow and Joule heating in preparative continuous annular electrochromatography.

    PubMed

    Laskowski, René; Bart, Hans-Jörg

    2015-09-01

    An openFOAM "computational fluid dynamic" simulation model was developed for the description of local interaction of hydrodynamics and Joule heating in annular electrochromatography. A local decline of electrical conductivity of the background eluent is caused by an electrokinetic migration of ions resulting in higher Joule heat generation. The model equations consider the Navier-Stokes equation for incompressible fluids, the energy equation for stationary temperature fields, and the mass transfer equation for the electrokinetic flow. The simulations were embedded in commercial ANSYS Fluent software and in open-source environment openFOAM. The annular gap (1 mm width) contained an inorganic C8 reverse-phase monolith as stationary phase prepared by an in situ sol-gel process. The process temperature generated by Joule heating was determined by thermal camera system. The local hydrodynamics in the prototype was detected by a gravimetric contact-free measurement method and experimental and simulated values matched quite well.

  1. Thaw flow control for liquid heat transport systems

    DOEpatents

    Kirpich, Aaron S.

    1989-01-01

    In a liquid metal heat transport system including a source of thaw heat for use in a space reactor power system, the thaw flow throttle or control comprises a fluid passage having forward and reverse flow sections and a partition having a plurality of bleed holes therein to enable fluid flow between the forward and reverse sections. The flow throttle is positioned in the system relatively far from the source of thaw heat.

  2. Simulation of Rocket-Grade Kerosene Flowing in an Electrically Heated Experimental Apparatus

    DTIC Science & Technology

    2015-07-01

    fluid, heat and electricity in an experimental apparatus designed to test fuel thermal stability. A numerical simulation is performed for the purposes...dimensional combined flow of fluid, heat and electricity in an experimental apparatus designed to test fuel thermal stability. A numerical simulation is...Service  Excellence Simulation of Rocket-Grade Kerosene Flowing in an Electrically Heated Apparatus Propulsion and Energy Forum 27-29 July 2015

  3. Evaluation of heat flow and its geological implications on Mt. St. Helens

    SciTech Connect

    Grady, T.; Adams, E.; Brown, R.L.; Sato, A.

    1982-04-01

    A study to determine the heat flux pattern in the vicinity of Mt. St. Helens was undertaken as part of a program to evaluate the effects of the eruption on future snowpack conditions in the area. Subsurface temperature and low energy refraction seismic studies were made during the early spring in 1981 to determine both the heat flux in the area of pyroclastic deposition and its potential source. In addition, samples were collected for later laboratory determination of thermal conductivity and diffusivity. Results indicate that the heat flow values in the area of pyroclastic deposition are as large as forty times greater than the heat flow values measured on Mt. Adams and Mt. Hood during the same period. The highest heat flow values appear to coincide with a pumice flow unit on the north side of the mountain.. Comparison with work done on the eruption of Mt. Komagatake indicates that the large heat flow values continue for several years.

  4. Geothermal Heat Pump Profitability in Energy Services

    SciTech Connect

    1997-11-01

    If geothermal heat pumps (GHPs) are to make a significant mark in the market, we believe that it will be through energy service pricing contracts offered by retailcos. The benefits of GHPs are ideally suited to energy service pricing (ESP) contractual arrangements; however, few retailcos are thoroughly familiar with the benefits of GHPs. Many of the same barriers that have prevented GHPs from reaching their full potential in the current market environment remain in place for retailcos. A lack of awareness, concerns over the actual efficiencies of GHPs, perceptions of extremely high first costs, unknown records for maintenance costs, etc. have all contributed to limited adoption of GHP technology. These same factors are of concern to retailcos as they contemplate long term customer contracts. The central focus of this project was the creation of models, using actual GHP operating data and the experience of seasoned professionals, to simulate the financial performance of GHPs in long-term ESP contracts versus the outcome using alternative equipment. We have chosen two case studies, which may be most indicative of target markets in the competitive marketplace: A new 37,000 square foot office building in Toronto, Ontario; we also modeled a similar building under the weather conditions of Orlando, Florida. An aggregated residential energy services project using the mass conversion of over 4,000 residential units at Ft. Polk, Louisiana. Our method of analyses involved estimating equipment and energy costs for both the base case and the GHP buildings. These costs are input in to a cash flow analysis financial model which calculates an after-tax cost for the base and GHP case. For each case study customers were assumed to receive a 5% savings over their base case utility bill. A sensitivity analysis was then conducted to determine how key variables affect the attractiveness of a GHP investment.

  5. Heat flow and energetics of the San Andreas Fault Zone

    NASA Astrophysics Data System (ADS)

    Lachenbruch, Arthur H.; Sass, J. H.

    1980-11-01

    Approximately 100 heat flow measurements in the San Andreas fault zone indicate (1) there is no evidence for local factional heating of the main fault trace at any latitude over a 1000-km length from Cape Mendocino to San Bernardino, (2) average heat flow is high (˜2 HFU, ˜80 mW m-2) throughout the 550-km segment of the Coast Ranges that encloses the San Andreas fault zone in central California; this broad anomaly falls off rapidly toward the Great Valley to the east, and over a 200-km distance toward the Mendocino Triple Junction to the northwest. As others have pointed out, a local conductive heat flow anomaly would be detectable unless the frictional resistance allocated to heat production on the main trace were ≲100 bars. Frictional work allocated to surface energy of new fractures is probably unimportant, and hydrologic convection is not likely to invalidate the conduction assumption, since the heat discharge by thermal springs near the fault is negligible. Explanations for the low dynamic friction fall into two intergradational classes: those in which the fault is weak all of the time and those in which it is weak only during earthquakes (possibly just large ones). The first class includes faults containing anomalously weak gouge materials and faults containing materials with normal frictional properties under near-lithostatic steady state fluid pressures. In the second class, weakening is caused by the event (for example, a thermally induced increase in fluid pressure, dehydration of clay minerals, or acoustic fluidization). In this class, unlike the first, the average strength and ambient tectonic shear stress may be large, ˜1 kbar, but the stress allocated to elastic radiation (the apparent stress) must be of similar magnitude, an apparent contradiction with seismic estimates. Unless seismic radiation is underestimated for large earthquakes, it is difficult to justify average tectonic stresses on the main trace of the San Andreas fault in excess of

  6. Energy Conservation: Heating Navy Hangars

    DTIC Science & Technology

    1984-07-01

    8217,. Unclassified SECURITY CLASSIFICATION OF THIS PAGE(I"I... Del* £E.ledJ 20. Continued rates versus hangar size and climatic conditions and design ... Design criteria providing hangar air infiltration rates versus hangar size and climatic conditions and design criteria for hangar destratifiers were...of destratifiers, vehicle access doors, door seals, vinyl strip doors, and radiant heating) were evaluated and are discussed. Design criteria

  7. Heat Recovery and Energy Conservation in Petroleum Refining.

    NASA Astrophysics Data System (ADS)

    Larsen, William Gale

    1990-01-01

    The focus of the analysis presented here is improved recovery (and use) of waste heat at existing petroleum refineries. The major energy-conservation opportunities associated with waste heat are systematically examined both physically and in terms of cost. The opportunities at the Study Refinery are systematically examined in detail. The presentation begins with an overview of the processes carried out in contemporary petroleum refineries including discussion of typical energy use. There follows a brief thermodynamic description of refinery energy flows with an emphasis on heat and on energy-efficiency analysis. The heart of the thesis is Chapters 3-5 describing heat recovery opportunities involving, respectively: extraction and use of heat from combustion gases being discharged through stacks, the exchange of heat between product streams, and uses for low-temperature waste heat. In Chapter 6, a unifying economic concept is introduced (with details in the Appendix): a "supply curve" for saved energy. This describes the potential rate of energy savings in barrels of oil-equivalent per year (in analogy with production capacity of oil or gas fields), as a function of the cost of saved energy in dollars per barrel (in analogy with the production cost of energy). The nature of the distribution is, of course, for the cost of saved energy to increase with increasing energy savings. In this chapter, estimates are presented for the energy conservation opportunities other than waste heat at the Study Refinery. All the opportunities are then summarized in a single supply curve. The extraordinary result in a cost-effective opportunity to reduce refinery energy use by some 26% at 1984 prices. This translates into roughly a 1 energy-cost reduction per 42-gallon barrel of petroleum input. Of course, investments are required; the net benefit would be about 1.5 cents per gallon of product. This would be a major benefit in relation to typical refinery earnings. The concluding

  8. Present-day heat flow model of Mars.

    PubMed

    Parro, Laura M; Jiménez-Díaz, Alberto; Mansilla, Federico; Ruiz, Javier

    2017-04-03

    Until the acquisition of in-situ measurements, the study of the present-day heat flow of Mars must rely on indirect methods, mainly based on the relation between the thermal state of the lithosphere and its mechanical strength, or on theoretical models of internal evolution. Here, we present a first-order global model for the present-day surface heat flow for Mars, based on the radiogenic heat production of the crust and mantle, on scaling of heat flow variations arising from crustal thickness and topography variations, and on the heat flow derived from the effective elastic thickness of the lithosphere beneath the North Polar Region. Our preferred model finds heat flows varying between 14 and 25 mW m(-2), with an average value of 19 mW m(-2). Similar results (although about ten percent higher) are obtained if we use heat flow based on the lithospheric strength of the South Polar Region. Moreover, expressing our results in terms of the Urey ratio (the ratio between total internal heat production and total heat loss through the surface), we estimate values close to 0.7-0.75, which indicates a moderate contribution of secular cooling to the heat flow of Mars (consistent with the low heat flow values deduced from lithosphere strength), unless heat-producing elements abundances for Mars are subchondritic.

  9. Present-day heat flow model of Mars

    PubMed Central

    Parro, Laura M.; Jiménez-Díaz, Alberto; Mansilla, Federico; Ruiz, Javier

    2017-01-01

    Until the acquisition of in-situ measurements, the study of the present-day heat flow of Mars must rely on indirect methods, mainly based on the relation between the thermal state of the lithosphere and its mechanical strength, or on theoretical models of internal evolution. Here, we present a first-order global model for the present-day surface heat flow for Mars, based on the radiogenic heat production of the crust and mantle, on scaling of heat flow variations arising from crustal thickness and topography variations, and on the heat flow derived from the effective elastic thickness of the lithosphere beneath the North Polar Region. Our preferred model finds heat flows varying between 14 and 25 mW m−2, with an average value of 19 mW m−2. Similar results (although about ten percent higher) are obtained if we use heat flow based on the lithospheric strength of the South Polar Region. Moreover, expressing our results in terms of the Urey ratio (the ratio between total internal heat production and total heat loss through the surface), we estimate values close to 0.7–0.75, which indicates a moderate contribution of secular cooling to the heat flow of Mars (consistent with the low heat flow values deduced from lithosphere strength), unless heat-producing elements abundances for Mars are subchondritic. PMID:28367996

  10. Large deviations in stochastic heat-conduction processes provide a gradient-flow structure for heat conduction

    SciTech Connect

    Peletier, Mark A.; Redig, Frank; Vafayi, Kiamars

    2014-09-01

    We consider three one-dimensional continuous-time Markov processes on a lattice, each of which models the conduction of heat: the family of Brownian Energy Processes with parameter m (BEP(m)), a Generalized Brownian Energy Process, and the Kipnis-Marchioro-Presutti (KMP) process. The hydrodynamic limit of each of these three processes is a parabolic equation, the linear heat equation in the case of the BEP(m) and the KMP, and a nonlinear heat equation for the Generalized Brownian Energy Process with parameter a (GBEP(a)). We prove the hydrodynamic limit rigorously for the BEP(m), and give a formal derivation for the GBEP(a). We then formally derive the pathwise large-deviation rate functional for the empirical measure of the three processes. These rate functionals imply gradient-flow structures for the limiting linear and nonlinear heat equations. We contrast these gradient-flow structures with those for processes describing the diffusion of mass, most importantly the class of Wasserstein gradient-flow systems. The linear and nonlinear heat-equation gradient-flow structures are each driven by entropy terms of the form -log ρ; they involve dissipation or mobility terms of order ρ² for the linear heat equation, and a nonlinear function of ρ for the nonlinear heat equation.

  11. Energy Integrated Lighting-Heating-Cooling System.

    ERIC Educational Resources Information Center

    Meckler, Gershon; And Others

    1964-01-01

    Energy balance problems in the design of office buildings are analyzed. Through the use of integrated systems utilizing dual purpose products, a controlled environment with minimum expenditure of energy, equipment and space can be provided. Contents include--(1) office building occupancy loads, (2) office building heating load analysis, (3) office…

  12. Energy efficient continuous flow ash lockhopper

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor); Suitor, Jerry W. (Inventor); Dubis, David (Inventor)

    1989-01-01

    The invention relates to an energy efficient continuous flow ash lockhopper, or other lockhopper for reactor product or byproduct. The invention includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control fluid supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The main novelty resides in the use of a control chamber to so control pressure under the lockhopper that gases will not exit from the reactor vessel, and to also regulate the ash flow rate. There is also novelty in the design of the ash lockhopper shown in two figures. The novelty there is the use of annular passages of progressively greater diameter, and rotating the center parts on a shaft, with the center part of each slightly offset from adjacent ones to better assure ash flow through the opening.

  13. Meteorological insights from planetary heat flow measurements

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.

    2015-04-01

    Planetary heat flow measurements are made with a series of high-precision temperature sensors deployed in a column of regolith to determine the geothermal gradient. Such sensors may, however, be susceptible to other influences, especially on worlds with atmospheres. First, pressure fluctuations at the surface may pump air in and out of pore space leading to observable, and otherwise unexpected, temperature fluctuations at depth. Such pumping is important in subsurface radon and methane transport on Earth: evidence of such pumping may inform understanding of methane or water vapor transport on Mars. Second, the subsurface profile contains a muted record of surface temperature history, and such measurements on other worlds may help constrain the extent to which Earth's Little Ice Age was directly solar-forced, versus volcanic-driven and/or amplified by climate feedbacks.

  14. CERES Detects Earth's Heat and Energy

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Clouds and the Earth's Radiant Energy System, CERES, monitors solar energy reflected from the Earth and heat energy emitted from the Earth. In this image, heat energy radiated from the earth is shown in varying shades of yellow, red, blue and white. The brightest yellow areas, such as the Sahara Desert and Arabian Peninsula, are emitting the most energy out to space, while the dark blue polar regions and bright white clouds are the coldest areas on Earth, and are emitting the least energy. The animation (1.5MB) (high-res (4MB)) shows roughly a week of CERES data. For more information: CERES images through Visible Earth. CERES web site Image courtesy of the CERES instrument team

  15. Analysis of the transient compressible vapor flow in heat pipe

    NASA Technical Reports Server (NTRS)

    Jang, Jong Hoon; Faghri, Amir; Chang, Won Soon

    1989-01-01

    The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.

  16. Enhancing flow boiling heat transfer in microchannels for thermal management with monolithically-integrated silicon nanowires.

    PubMed

    Li, D; Wu, G S; Wang, W; Wang, Y D; Liu, Dong; Zhang, D C; Chen, Y F; Peterson, G P; Yang, Ronggui

    2012-07-11

    Thermal management has become a critical issue for high heat flux electronics and energy systems. Integrated two-phase microchannel liquid-cooling technology has been envisioned as a promising solution, but with great challenges in flow instability. In this work, silicon nanowires were synthesized in situ in parallel silicon microchannel arrays for the first time to suppress the flow instability and to augment flow boiling heat transfer. Significant enhancement in flow boiling heat transfer performance was demonstrated for the nanowire-coated microchannel heat sink, such as an early onset of nucleate boiling, a delayed onset of flow oscillation, suppressed oscillating amplitudes of temperature and pressure drop, and an increased heat transfer coefficient.

  17. District Heating Systems Performance Analyses. Heat Energy Tariff

    NASA Astrophysics Data System (ADS)

    Ziemele, Jelena; Vigants, Girts; Vitolins, Valdis; Blumberga, Dagnija; Veidenbergs, Ivars

    2014-12-01

    The paper addresses an important element of the European energy sector: the evaluation of district heating (DH) system operations from the standpoint of increasing energy efficiency and increasing the use of renewable energy resources. This has been done by developing a new methodology for the evaluation of the heat tariff. The paper presents an algorithm of this methodology, which includes not only a data base and calculation equation systems, but also an integrated multi-criteria analysis module using MADM/MCDM (Multi-Attribute Decision Making / Multi-Criteria Decision Making) based on TOPSIS (Technique for Order Performance by Similarity to Ideal Solution). The results of the multi-criteria analysis are used to set the tariff benchmarks. The evaluation methodology has been tested for Latvian heat tariffs, and the obtained results show that only half of heating companies reach a benchmark value equal to 0.5 for the efficiency closeness to the ideal solution indicator. This means that the proposed evaluation methodology would not only allow companies to determine how they perform with regard to the proposed benchmark, but also to identify their need to restructure so that they may reach the level of a low-carbon business.

  18. Heat flow and temperature-depth curves throughout Alaska: finding regions for future geothermal exploration

    NASA Astrophysics Data System (ADS)

    Batir, Joseph F.; Blackwell, David D.; Richards, Maria C.

    2016-06-01

    The objective of this research is to contribute to the understanding of the thermal regime of Alaska and its relationship to geology, regional tectonics, and to suggest potential sites for future geothermal energy production. New heat flow data were collected and are combined with existing published and unpublished data, although large sections of Alaska still lack data. Fault traces were implemented into the heat flow contouring as an additional gridding constraint, to incorporate both heat flow measurements and geology. New heat flow data supported the use of geologic trends in the heat flow mapping procedure, and a heat flow map of Alaska was produced with this added constraint. The multi-input contouring strategy allows production of a map with a regional interpretation of heat flow, in addition to site-specific heat flow and thermal model interpretations in areas with sufficient data density. Utilizing the new heat flow map, temperature-at-depth curves were created for example areas. Temperature-at-depth curves are calculated to 10 km depth for the areas of Anchorage, Fairbanks, Juneau, the Alaska Peninsula, Bristol Bay, and the Copper River Basin. The temperatures-at-depth predicted near the population centers of Anchorage and Juneau are relatively low, limiting the geothermal resource potential. The Fairbanks area temperature estimates are near conventional power production temperatures (150 °C) between 3.5 and 4 km. All data areas, except at Juneau, have temperatures sufficient for low temperature geothermal applications (40 °C) by 2 km. A high heat flow region exists within the Aleutian Volcanic Arc, although new data show heat flow variations from 59 to 120 mW m-2, so individual geothermal resources within the arc will be irregularly located.

  19. Cycle of waste heat energy transformation

    NASA Astrophysics Data System (ADS)

    Bormann, H.; Voneynatten, C.; Krause, R.; Rudolph, W.; Gneuss, G.; Groesche, F.

    1983-08-01

    Transformation of industrial waste heat with temperatures up to 300 C into mechanical or electrical energy using organic Rankine cycles technique is considered. Behavior of working fluid was studied and plant components were optimized. A pilot plant (generated power 30 kW) was installed under industrial operating conditions. The working fluid is a fluorochlorohydrocarbon; the expansion machine is a piston type steam engine. The results of the pilot plant were used for the planning and building of a prototype plant (120 kW) with an additional power heat coupling for preheating the boiler heat water. The waste heat source is a calciner process. The predicted results are obtained although full working load is not reached due to reduced available waste heat of the calciner process.

  20. A New Determination of Io's Heat Flow Using Diurnal Heat Balance Constraints

    NASA Technical Reports Server (NTRS)

    Spencer, J. R.; Rathbun, J. A.; McEwen, A. S.; Pearl, J. C.; Bastos, A.; Andrade, J.; Correia, M.; Barros, S.

    2002-01-01

    We use heat balance arguments to obtain a new estimate of Io's heat flow that does not depend on assumptions about the temperatures of its thermal anomalies. Our estimated heat flow is somewhat less than 2.2 +/- 0.9 W/sq m. Additional information is contained in the original extended abstract.

  1. Specific heat of multifractal energy spectra

    NASA Astrophysics Data System (ADS)

    da Silva, L. R.; Vallejos, R. O.; Tsallis, C.; Mendes, R. S.; Roux, S.

    2001-07-01

    Motivated by the self-similar character of energy spectra demonstrated for quasicrystals, we investigate the case of multifractal energy spectra, and compute the specific heat associated with simple archetypal forms of multifractal sets as generated by iterated maps. We considered the logistic map and the circle map at their threshold to chaos. Both examples show nontrivial structures associated with the scaling properties of their respective chaotic attractors. The specific heat displays generically log-periodic oscillations around a value that characterizes a single exponent, the ``fractal dimension,'' of the distribution of energy levels close to the minimum value set to 0. It is shown that when the fractal dimension and the frequency of log oscillations of the density of states are large, the amplitude of the resulting log oscillation in the specific heat becomes much smaller than the log-periodic oscillation measured on the density of states.

  2. Heat transfer research on supercritical water flow upward in tube

    SciTech Connect

    Li, H. B.; Yang, J.; Gu, H. Y.; Zhao, M.; Lu, D. H.; Zhang, J. M.; Wang, F.; Zhang, Y.

    2012-07-01

    The experimental research of heat transfer on supercritical water has been carried out on the supercritical water multipurpose test loop with a 7.6 mm upright tube. The experimental data of heat transfer is obtained. The experimental results of thermal-hydraulic parameters on flow and heat transfer of supercritical water show that: Heat transfer enhancement occurs when the fluid temperature reaches pseudo-critical point with low mass flow velocity, and peters out when the mass flow velocity increases. The heat transfer coefficient and Nusselt number decrease with the heat flux or system pressure increases, and increase with the increasing of mass flow velocity. The wall temperature increases when the mass flow velocity decreases or the system pressure increases. (authors)

  3. Working fluid flow visualization in gravity heat pipe

    NASA Astrophysics Data System (ADS)

    Nemec, Patrik; Malcho, Milan

    2016-03-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. The article deal about gravity heat pipe construction and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm) and filled with water. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  4. Distributed energy storage: Time-dependent tree flow design

    NASA Astrophysics Data System (ADS)

    Bejan, A.; Ziaei, S.; Lorente, S.

    2016-05-01

    This article proposes "distributed energy storage" as a basic design problem of distributing energy storage material on an area. The energy flows by fluid flow from a concentrated source to points (users) distributed equidistantly on the area. The flow is time-dependent. Several scenarios are analyzed: sensible-heat storage, latent-heat storage, exergy storage vs energy storage, and the distribution of a finite supply of heat transfer surface between the source fluid and the distributed storage material. The chief conclusion is that the finite amount of storage material should be distributed proportionally with the distribution of the flow rate of heating agent arriving on the area. The total time needed by the source stream to "invade" the area is cumulative (the sum of the storage times required at each storage site) and depends on the energy distribution paths and the sequence in which the users are served by the source stream. Directions for future designs of distributed storage and retrieval are outlined in the concluding section.

  5. Snow distribution and heat flow in the taiga

    SciTech Connect

    Sturm, M. )

    1992-05-01

    The trees of the taiga intercept falling snow and cause it to become distributed in an uneven fashion. Around aspen and birch, cone-shaped accumulations form. Beneath large spruce trees, the snow cover is depleted, forming a bowl-shaped depression called a tree well. Small spruce trees become covered with snow, creating cavities that funnel cold air to the snow/ground interface. The depletion of snow under large spruce trees results in greater heat loss from the ground. A finite difference model suggests that heat flow from tree wells can be more than twice that of undisturbed snow. In forested watersheds, this increase can be a significant percentage of the total winter energy exchange.

  6. Heat flow calorimeter. [measures output of Ni-Cd batteries

    NASA Technical Reports Server (NTRS)

    Fletcher, J. C.; Johnston, W. V. (Inventor)

    1974-01-01

    Heat flow calorimeter devices are used to measure heat liberated from or absorbed by an object. This device is capable of measuring the thermal output of sealed nickel-cadmium batteries or cells during charge-discharge cycles. An elongated metal heat conducting rod is coupled between the calorimeter vessel and a heat sink, thus providing the only heat exchange path from the calorimeter vessel itself.

  7. California energy flow in 1994

    SciTech Connect

    Borg, I.Y.; Mui, N.

    1996-09-01

    California energy consumption increased in 1994 in keeping with a recovery from the previous mild recession years. Although unemployment remained above the national average, other indicators pointed to improved economic health. Increased energy use was registered principally in the residential/commercial and transportation end-use sectors. A cooler-than-usual winter and spring was reflected in increased consumption of natural gas, the principal space-heating fuel in the state. Because of low water levels behind state dams, utilities turned to natural gas for electrical generation and to increased imports from out-of- state sources to meet demand. Other factors, such as smaller output from geothermal, biomass, and cogenerators, contributed to the need for the large increase in electrical supply from these two sources. Nonetheless, petroleum dominated the supply side of the energy equation of the state in which transportation requirements comprise more than one-third of total energy demand. About half of the oil consumed derived from California production. Onshore production has been in slow decline; however, in 1994 the decrease was compensated for by increases from federal offshore fields. Until 1994 production had been limited by regulatory restrictions relating to the movement of the crude oil to onshore refineries. State natural gas production remained at 1993 levels. The increased demand was met by larger imports from Canada through the recent expansion of Pacific Transmission Company`s 804 mile pipeline. Deregulation of the state`s utilities moved ahead in 1994 when the California Public Utilities Commission issued its proposal on how to restructure the industry. Public hearings were conducted in which the chief issues were recovery of the utilities` capital investments, conflicts with the Public Utilities Policies Act, management of power transactions between new suppliers and former utility customers, and preservation of energy conservation programs

  8. In situ determination of heat flow in unconsolidated sediments

    USGS Publications Warehouse

    Sass, J.H.; Kennelly, J.P.; Wendt, W.E.; Moses, T.H.; Ziagos, J.P.

    1979-01-01

    Subsurface thermal measurements are the most effective, least ambiguous tools for identifying and delineating possible geothernml resources. Measurements of thermal gradient in the upper few tens of meters generally are sufficient to outline the major anomalies, but it is always desirable to combine these gradients with reliable estimates of thermal conductivity to provide data on the energy flux and to constrain models for the heat sources responsible for the observed, near-surface thermal anomalies. The major problems associated with heat-flow measurements in the geothermal exploration mode are concerned with the economics of casing and/or grouting holes, the repeated site visits necessary to obtain equilibrium temperature values, the possible legal liability associated with the disturbance of underground aquifers, the surface hazards presented by pipes protruding from the ground, and the security problems associated with leaving cased holes open for periods of weeks to months. We have developed a technique which provides reliable 'real-time' determinations of temperature, thermal conductivity, and hence, of heat flow during the drilling operation in unconsolidated sediments. A combined temperature, gradient, and thermal conductivity experiment can be carried out, by driving a thin probe through the bit about 1.5 meters into the formation in the time that would otherwise be required for a coring trip. Two or three such experiments over the depth range of, say, 50 to 150 meters provide a high-quality heat-flow determination at costs comparable to those associated with a standard cased 'gradient hole' to comparable depths. The hole can be backfilled and abandoned upon cessation of drilling, thereby eliminating the need for casing, grouting, or repeated site visits.

  9. Planetary heat flow from shallow subsurface measurements: Mars

    NASA Astrophysics Data System (ADS)

    Cornwall, Marc; Hagermann, Axel

    2016-10-01

    Planetary heat flow probes measure heat flow (depth-resolved temperature and thermal conductivity) to provide insight into the internal state of a planet. The probes have been utilized extensively on Earth, twice on the Moon, and once on the Surface of comet 67P-CG. Mars is an important target for heat flow measurement as heat flow is a critical parameter in Martian thermal history models. Earlier studies indicate that Martian planetary heat flow can be accessed at 5 m below the surface in dry regolith monitored over at least one Martian year. A one Martian year monitoring period is necessary because, in the shallow subsurface, heat flow from the interior is superposed with time varying heat flow contributions, primarily due to insolation. Given that a heat flow probe may not achieve its target depth or monitoring period, this study investigates how the depth (2-5 m), duration (0-1 Martian year) and quality of measurements influence the accuracy of planetary heat flow. An inverse model is used to show that, in the preceding scenarios, the accuracy of planetary heat flow directly estimated from depth-dependent thermal conductivity with 10-20% precision errors, temperatures with 50-100 mK precision errors and modelling uncertainties up to 500 mK, can, on average, be improved by a factor of 27 with optimization to 13%. Accuracies increase with sensor penetration depth and regolith monitoring period. Heat flow optimized from instantaneous measurements or those with the shortest regolith monitoring periods have increased accuracy where the frequency and amplitude of the temperature variation are lowest. The inverse model is based on the Function Specification Inversion method. This study demonstrates that a solution subspace can be identified within a space of uncertainties modelled for the temperature measurements and planetary heat flow: the subspace is defined by a constant log-ratio of their respective standard deviations. Optimized heat flow estimates display

  10. The silica heat flow interpretation technique: application to continental Australia

    NASA Astrophysics Data System (ADS)

    Pirlo, M. C.

    2002-06-01

    The silica heat flow interpretation technique [Swanberg, C.A. and Morgan, P., J. Geophys. Res. 117 (1979) 227-241; J. Geophys. Res. 85 (1980) 7206-7214] has been applied and tested in mainland Australia, using a database of approximately 41 000 Australian groundwater analyses. The silica geotemperature of the groundwaters was obtained by substituting the dissolved silica content of a groundwater into the quartz geothermometer equation of Truesdell [(1976) Proceedings of the Second United Nations Symposium on the Development and Use of Geothermal Resources. San Francisco, CA, USA, 20-29 May, 1975, Vol. 1]. The average silica geotemperature value for 1×1° (latitude×longitude) grid cells has been calculated and the results plotted against published traditional heat flow values for those grid cells [Cull, J.P. (1982) BMR J. Aust. Geol. Geophys. 7, 11-21], to form silica heat flow estimation models. Data exclusion criteria, based upon data quantity and statistical spread have been applied to both the groundwater data and the traditional heat flow data. This was done in order to exclude areas that were poorly categorized in terms of data quality and quantity. For the remaining data, a significant linear relationship between the groundwater geotemperature estimates and traditional heat flow measurements has been identified for four of the models with a t-test on the correlation coefficient. Estimates of regional heat flow were then made by applying the calibration models in areas with no traditional heat flow measurements but adequate groundwater data. A silica heat flow map has been constructed using one of the models and the differences between it and the traditional heat flow map evaluated. Good correlations exist between the silica heat flow map and the traditional heat flow map, except for the northwest Yilgarn, of WA, Australia, where silica heat flow data give significantly higher values than traditional data. The silica heat flow map identifies areas of high

  11. Modeling of heat transfer and fluid flow for decaying swirl flow in a circular pipe

    SciTech Connect

    Bali, T.

    1998-04-01

    The economic benefits of energy and material savings have prompted and received greatest attention in order to increase convective heat transfer rates in the process equipment. In the present study, a propeller type swirl generator was developed, and its effects on heat transfer and fluid flow were investigated numerically and experimentally for air flow in a pipe. In the numerical study, for axisymmetrically, incompressible turbulent swirl flows, the Navier-Stokes equations were solved using the {kappa}-{var_epsilon} turbulent model. So that a computer program in Fortran was constructed using the SIMPLEC Algorithm. In experimental work, axial and tangential velocity distributions behind the swirl generator were measured by using hot-wire anemometry. Experimental and numerical axial and tangential velocity distributions along the pipe were compared, and good agreement was found. Axial velocity profile showed a decrement in the central portion of the pipe and an increased axial velocity was seen in near the wall. Tangential velocity profiles had a maximum value and its location moved in radially with distance. The effects of swirl flow on the heat transfer and pressure drop were also investigated experimentally.

  12. Steady-state heat transfer in transversely heated porous media with application to focused solar energy collectors

    NASA Technical Reports Server (NTRS)

    Nichols, L. D.

    1976-01-01

    A fluid flowing in a porous medium heated transversely to the fluid flow is considered. This configuration is applicable to a focused solar energy collector for use in an electric power generating system. A fluidized bed can be regarded as a porous medium with special properties. The solutions presented are valid for describing the effectiveness of such a fluidized bed for collecting concentrated solar energy to heat the working fluid of a heat engine. Results indicate the advantage of high thermal conductivity in the transverse direction and high operating temperature of the porous medium.

  13. California energy flow in 1992

    SciTech Connect

    Borg, I.Y.; Briggs, C.K.

    1994-04-01

    For the past 16 years energy flow diagrams for the State of California have been prepared from available data by members of the Lawrence Livermore National Laboratory. They have proven to be useful tools in graphically expressing energy supply and use in the State as well as illustrating the difference between particular years and between the State and the US as a whole. As far as is possible, similar data sources have been used to prepare the diagrams from year to year and identical assumptions{sup la-le} concerning conversion efficiencies have been made in order to minimize inconsistencies in the data and analyses. Sources of data used in this report are given in Appendix B and C; unavoidably the sources used over the 1976--1993 period have varied as some data bases are no longer available. In addition, we continue to see differences in specific data reported by different agencies for a given year. In particular, reported data on supply and usage in industrial/commercial/residential end-use categories have shown variability amongst the data gathering agencies, which bars detailed comparisons from year to year. Nonetheless, taken overall, valid generalizations can be made concerning gross trends and changes.

  14. Martian surface heat production and crustal heat flow from Mars Odyssey Gamma-Ray spectrometry

    NASA Astrophysics Data System (ADS)

    Hahn, B. C.; McLennan, S. M.; Klein, E. C.

    2011-07-01

    Martian thermal state and evolution depend principally on the radiogenic heat-producing element (HPE) distributions in the planet's crust and mantle. The Gamma-Ray Spectrometer (GRS) on the 2001 Mars Odyssey spacecraft has mapped the surface abundances of HPEs across Mars. From these data, we produce the first models of global and regional surface heat production and crustal heat flow. As previous studies have suggested that the crust is a repository for approximately 50% of the radiogenic elements on Mars, these models provide important, directly measurable constraints on Martian heat generation. Our calculations show considerable geographic and temporal variations in crustal heat flow, and demonstrate the existence of anomalous heat flow provinces. We calculate a present day average surface heat production of 4.9 ± 0.3 × 10-11 W · kg-1. We also calculate the average crustal component of heat flow of 6.4 ± 0.4 mW · m-2. The crustal component of radiogenically produced heat flow ranges from <1 mW · m-2 in the Hellas Basin and Utopia Planitia regions to ˜13 mW · m-2 in the Sirenum Fossae region. These heat production and crustal heat flow values from geochemical measurements support previous heat flow estimates produced by different methodologies.

  15. Energy-Efficient, Continuous-Flow Ash Lockhopper

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.; Suitor, Jerry W.; Dubis, David

    1989-01-01

    Pressure balance in control gas prevents loss of reactor gas. Energy efficiency of continuous-flow ash lockhopper increased by preventing hot gases from flowing out of reactor vessel through ash-hopper outlet and carrying away heat energy. Stopping loss of reactor gases also important for reasons other than energy efficiency; desired reaction product toxic or contained to prevent pollution. In improved continuous-flow ash lockhopper, pressure-driven loss of hot gas from reactor vessel through ash-hopper outlet prevented by using control gas in fluidic flow-control device to equalize pressure in reactor vessel. Also enables reactor to attain highest possible product yield with continuous processing while permitting controllable, continuous flow of ash.

  16. Flow instability and flow reversal in heated annular multichannels with initial downward flow

    SciTech Connect

    Guerrero, H.N.; Hart, C.M.

    1992-12-31

    Experimental and theoretical results are presented regarding the stability of initial downward flow of single phase water in parallel annular channels of the Savannah River Site (SRS) fuel assembly. The test was performed on an electrically heated prototypic mockup of a Mark-22 fuel assembly. The test conditions consisted of mass fluxes, from 98--294 kg/m{sup 2}-sec, and inlet water temperatures of 25{degrees}C and 40{degrees}C. With increased power to the heaters, flow instability was detected, characterized by flow fluctuations and flow redistribution among subchannels of the outer flow channel. With increased power, a condition was observed indicating local subchannel flow reversals where certain subchannel fluid temperatures were high at the inlet and low at the exit. With additional power increased, a critical heat flux condition was observed indicating local subchannel flow reversals where certain subchannel fluid temperatures were high at the inlet and low at the exit. With additional power increases, a critical heat flux condition was reached in the outer channel.

  17. Flow instability and flow reversal in heated annular multichannels with initial downward flow

    SciTech Connect

    Guerrero, H.N.; Hart, C.M.

    1992-01-01

    Experimental and theoretical results are presented regarding the stability of initial downward flow of single phase water in parallel annular channels of the Savannah River Site (SRS) fuel assembly. The test was performed on an electrically heated prototypic mockup of a Mark-22 fuel assembly. The test conditions consisted of mass fluxes, from 98--294 kg/m[sup 2]-sec, and inlet water temperatures of 25[degrees]C and 40[degrees]C. With increased power to the heaters, flow instability was detected, characterized by flow fluctuations and flow redistribution among subchannels of the outer flow channel. With increased power, a condition was observed indicating local subchannel flow reversals where certain subchannel fluid temperatures were high at the inlet and low at the exit. With additional power increased, a critical heat flux condition was observed indicating local subchannel flow reversals where certain subchannel fluid temperatures were high at the inlet and low at the exit. With additional power increases, a critical heat flux condition was reached in the outer channel.

  18. A Prototype Flux-Plate Heat-Flow Sensor for Venus Surface Heat-Flow Determinations

    NASA Technical Reports Server (NTRS)

    Morgan, Paul; Reyes, Celso; Smrekar, Suzanne E.

    2005-01-01

    Venus is the most Earth-like planet in the Solar System in terms of size, and the densities of the two planets are almost identical when selfcompression of the two planets is taken into account. Venus is the closest planet to Earth, and the simplest interpretation of their similar densities is that their bulk compositions are almost identical. Models of the thermal evolution of Venus predict interior temperatures very similar to those indicated for the regions of Earth subject to solid-state convection, but even global analyses of the coarse Pioneer Venus elevation data suggest Venus does not lose heat by the same primary heat loss mechanism as Earth, i.e., seafloor spreading. The comparative paucity of impact craters on Venus has been interpreted as evidence for relatively recent resurfacing of the planet associated with widespread volcanic and tectonic activity. The difference in the gross tectonic styles of Venus and Earth, and the origins of some of the enigmatic volcano-tectonic features on Venus, such as the coronae, appear to be intrinsically related to Venus heat loss mechanism(s). An important parameter in understanding Venus geological evolution, therefore, is its present surface heat flow. Before the complications of survival in the hostile Venus surface environment were tackled, a prototype fluxplate heat-flow sensor was built and tested for use under synthetic stable terrestrial surface conditions. The design parameters for this prototype were that it should operate on a conforming (sand) surface, with a small, self-contained power and recording system, capable of operating without servicing for at least several days. The precision and accuracy of the system should be < 5 mW/sq m. Additional information is included in the original extended abstract.

  19. Air-side flow and heat transfer in compact heat exchangers: A discussion of enhancement mechanisms

    SciTech Connect

    Jacobi, A.M.; Shah, R.K.

    1998-10-01

    The behavior of air flows in complex heat exchanger passages is reviewed with a focus on the heat transfer effects of boundary-layer development, turbulence, spanwise and streamwise vortices, and wake management. Each of these flow features is discussed for the plain, wavy, and interrupted passages found in contemporary compact heat exchanger designs. Results from the literature are used to help explain the role of these mechanisms in heat transfer enhancement strategies.

  20. Birch's Crustal Heat Production-Heat Flow Law: Key to Quantifying Mantle Heat Flow as a function of time

    NASA Astrophysics Data System (ADS)

    Blackwell, D. D.; Thakur, M.

    2007-12-01

    Birch (1968) first showed the linear correlation of surface heat flow and radioactive heat production (Qs = Qo + bAs ) in granites in New England, USA and discussed implications to the vertical scale of radioactive heat generation in the crust. Subsequently similar relationships have been found worldwide and numerous papers written describing more details and expanding the implications of Birch's Law. The results are a powerful contribution from heat flow research to the understanding of the lithosphere and its evolution. Models are both well constrained experimentally and simple in implications. However, there still exist thermal models of the crust and lithosphere that do not have the same firm foundation and involve unnecessary ad hoc assumptions. A main point of confusion has been that the several of the original relationships were so low in error as to be considered by some to be "fortuitous". Interestingly a "similar" relationship has been proposed based on regional scale averaging of Qs -As data. A second point of confusion is that one admissible crustal radioactivity distribution model (the constant heat generation to depth b) has been criticized as unrealistic for a number of reasons, including the effect of erosion. However, it is appropriate to refer to the Qs -As relationship as a law because in fact the relationship holds as long as the vertical distribution is "geologically realistic." as will be demonstrated in this paper. All geologic and geophysical models of the continental crust imply decreasing heat production as a function of depth (i.e. the seismic layering for example) except in very special cases. This general decrease with depth is the only condition required for the existence of a "linear" Qs -As relationship. A comparison of all the Qs -As relationships proposed for terrains not affected by thermal events over the last 150 to 200 Ma shows a remarkably uniformity in slope (10 ± 3 km) and intercept value (30 ± 5 mWm-2 ). Therefore these

  1. Unsteady Flow in a Supersonic Turbine with Variable Specific Heats

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)

    2001-01-01

    Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier

  2. Cryogenic Heat Exchanger with Turbulent Flows

    ERIC Educational Resources Information Center

    Amrit, Jay; Douay, Christelle; Dubois, Francis; Defresne, Gerard

    2012-01-01

    An evaporator-type cryogenic heat exchanger is designed and built for introducing fluid-solid heat exchange phenomena to undergraduates in a practical and efficient way. The heat exchanger functions at liquid nitrogen temperature and enables cooling of N[subscript 2] and He gases from room temperatures. We present first the experimental results of…

  3. Radiant energy receiver having improved coolant flow control means

    DOEpatents

    Hinterberger, H.

    1980-10-29

    An improved coolant flow control for use in radiant energy receivers of the type having parallel flow paths is disclosed. A coolant performs as a temperature dependent valve means, increasing flow in the warmer flow paths of the receiver, and impeding flow in the cooler paths of the receiver. The coolant has a negative temperature coefficient of viscosity which is high enough such that only an insignificant flow through the receiver is experienced at the minimum operating temperature of the receiver, and such that a maximum flow is experienced at the maximum operating temperature of the receiver. The valving is accomplished by changes in viscosity of the coolant in response to the coolant being heated and cooled. No remotely operated valves, comparators or the like are needed.

  4. Heat transfer in internal turbulent flows using the PDF method

    SciTech Connect

    Mazumder, S.; Modest, M.F.

    1996-12-31

    One of the strengths of the velocity-composition joint probability density function (PDF) method lies in its ability to predict scalar fields for reactive turbulent flows. The application of PDF methods to internal flows necessitates appropriate description of near-wall effects, namely, molecular transport, production of turbulence by inhomogeneities, and dissipation of the scalar fluctuations by viscosity. A Lagrangian transport equation has been derived for transport of energy, whereby convection is treated exactly. The temperature fluctuations are modeled by a modified version of a deterministic model, which was originally developed for homogeneous turbulence. The thermal wall-functions were used to incorporate these modifications. The resultant modeled Lagrangian energy transport equation is solved simultaneously with the hydrodynamic equations, for the test case of a thermally developing two-dimensional channel flow (parallel plate geometry). The model has been tested for both constant temperature and constant heat flux boundary conditions. Results obtained have been compared to {kappa}-{epsilon} and algebraic Reynolds stress model (ARSM) finite-volume calculations. Apart from the differences due to turbulence models, it was observed that the finite-volume calculations suffered numerical diffusion, which was completely eliminated in the Lagrangian PDF approach.

  5. Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers

    NASA Astrophysics Data System (ADS)

    Chen, Wang-Yi; Juang, Yow-Jer; Hsieh, Jung-Yu; Tsai, Perng-Jy; Chen, Chen-Peng

    2017-01-01

    International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection ( C res) and evaporation ( E res) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the C res for Taiwanese workers by approximately 3 % and underestimated the E res by 8 %. The C res approximation in the PHS model closely predicted the convective RHF, while the E res approximation over-predicted by 11 %. Linear regressions provided better fit in C res approximation ( R 2 = 0.96) than in E res approximation ( R 2 ≤ 0.85) in both models. The predicted C res deviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.

  6. Effects of flow maldistribution on the thermal performance of cross-flow micro heat exchangers

    NASA Astrophysics Data System (ADS)

    Nonino, C.; Savino, S.

    2016-09-01

    The combined effect of viscosity- and geometry-induced flow maldistribution on the thermal performance of cross-flow micro heat exchangers is investigated with reference to two microchannel cross-sectional geometries, three solid materials, three mass flow rates and three flow nonuniformity models. A FEM procedure, specifically developed for the analysis of the heat transfer between incompressible fluids in cross-flow micro heat exchangers, is used for the numerical simulations. The computed results indicate that flow maldistribution has limited effects on microchannel bulk temperatures, at least for the considered range of operating conditions.

  7. Magnetic energy flow in the solar wind.

    NASA Technical Reports Server (NTRS)

    Modisette, J. L.

    1972-01-01

    Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

  8. Heat transfer and flow characteristics on a gas turbine shroud.

    PubMed

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions.

  9. Electron heat flow in the auroral ionosphere inferred from EISCAT-VHF observations

    SciTech Connect

    Blelly, P.L.; Alcayde, D.

    1994-07-01

    This paper discusses heat flows into electrons in auroral regions. Two different altitude regions are considered, one coincident with the F2 region, and one coincident with the upper ionosphere. Energy input comes from solar extreme ultraviolet radiation, and coupling of magnetospheric energy sources. The authors present a method to take advantage of EISCAT VHF radar observations to study these processes. They observe daily and seasonal variations in the heat inputs.

  10. Reprint of : Thermoelectricity without absorbing energy from the heat sources

    NASA Astrophysics Data System (ADS)

    Whitney, Robert S.; Sánchez, Rafael; Haupt, Federica; Splettstoesser, Janine

    2016-08-01

    We analyze the power output of a quantum dot machine coupled to two electronic reservoirs via thermoelectric contacts, and to two thermal reservoirs - one hot and one cold. This machine is a nanoscale analogue of a conventional thermocouple heat-engine, in which the active region being heated is unavoidably also exchanging heat with its cold environment. Heat exchange between the dot and the thermal reservoirs is treated as a capacitive coupling to electronic fluctuations in localized levels, modeled as two additional quantum dots. The resulting multiple-dot setup is described using a master equation approach. We observe an "exotic" power generation, which remains finite even when the heat absorbed from the thermal reservoirs is zero (in other words the heat coming from the hot reservoir all escapes into the cold environment). This effect can be understood in terms of a non-local effect in which the heat flow from heat source to the cold environment generates power via a mechanism which we refer to as Coulomb heat drag. It relies on the fact that there is no relaxation in the quantum dot system, so electrons within it have a non-thermal energy distribution. More poetically, one can say that we find a spatial separation of the first-law of thermodynamics (heat to work conversion) from the second-law of thermodynamics (generation of entropy). We present circumstances in which this non-thermal system can generate more power than any conventional macroscopic thermocouple (with local thermalization), even when the latter works with Carnot efficiency.

  11. Numerical prediction of turbulent oscillating flow and associated heat transfer

    NASA Technical Reports Server (NTRS)

    Koehler, W. J.; Patankar, S. V.; Ibele, W. E.

    1991-01-01

    A crucial point for further development of engines is the optimization of its heat exchangers which operate under oscillatory flow conditions. It has been found that the most important thermodynamic uncertainties in the Stirling engine designs for space power are in the heat transfer between gas and metal in all engine components and in the pressure drop across the heat exchanger components. So far, performance codes cannot predict the power output of a Stirling engine reasonably enough if used for a wide variety of engines. Thus, there is a strong need for better performance codes. However, a performance code is not concerned with the details of the flow. This information must be provided externally. While analytical relationships exist for laminar oscillating flow, there has been hardly any information about transitional and turbulent oscillating flow, which could be introduced into the performance codes. In 1986, a survey by Seume and Simon revealed that most Stirling engine heat exchangers operate in the transitional and turbulent regime. Consequently, research has since focused on the unresolved issue of transitional and turbulent oscillating flow and heat transfer. Since 1988, the University of Minnesota oscillating flow facility has obtained experimental data about transitional and turbulent oscillating flow. However, since the experiments in this field are extremely difficult, lengthy, and expensive, it is advantageous to numerically simulate the flow and heat transfer accurately from first principles. Work done at the University of Minnesota on the development of such a numerical simulation is summarized.

  12. Application of heat flow models to SOI current mirrors

    NASA Astrophysics Data System (ADS)

    Yu, Feixia; Cheng, Ming-C.

    2004-11-01

    An analytical heat flow model for SOI circuits is presented. The model is able to account for heat exchanges among devices and heat loss from the silicon film and interconnects to the substrate through the buried oxide. The developed model can accurately and efficiently predict the temperature distribution in the interconnect/poly-lines and SOI devices. The model is applied to SOI current mirrors to study heat flow in different layout designs. The results from the developed model are verified with those from Raphael, a 3D numerical simulator that can provide the detailed 3D temperature distribution in interconnect/poly-lines.

  13. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart (Inventor); Walkemeyer, Phillip E. (Inventor); Hall, Jeffrey L. (Inventor); Lee, Hyeong Jae (Inventor); Colonius, Tim (Inventor); Tosi, Phillipe (Inventor); Kim, Namhyo (Inventor); Sun, Kai (Inventor); Corbett, Thomas Gary (Inventor); Arrazola, Alvaro Jose (Inventor)

    2016-01-01

    A flow energy harvesting device having a harvester pipe includes a flow inlet that receives flow from a primary pipe, a flow outlet that returns the flow into the primary pipe, and a flow diverter within the harvester pipe having an inlet section coupled to the flow inlet, a flow constriction section coupled to the inlet section and positioned at a midpoint of the harvester pipe and having a spline shape with a substantially reduced flow opening size at a constriction point along the spline shape, and an outlet section coupled to the constriction section. The harvester pipe may further include a piezoelectric structure extending from the inlet section through the constriction section and point such that the fluid flow past the constriction point results in oscillatory pressure amplitude inducing vibrations in the piezoelectric structure sufficient to cause a direct piezoelectric effect and to generate electrical power for harvesting.

  14. Heat and mass transfer and hydrodynamics in swirling flows (review)

    NASA Astrophysics Data System (ADS)

    Leont'ev, A. I.; Kuzma-Kichta, Yu. A.; Popov, I. A.

    2017-02-01

    Research results of Russian and foreign scientists of heat and mass transfer in whirling flows, swirling effect, superficial vortex generators, thermodynamics and hydrodynamics at micro- and nanoscales, burning at swirl of the flow, and technologies and apparatuses with the use of whirling currents for industry and power generation were presented and discussed at the "Heat and Mass Transfer in Whirling Currents" 5th International Conference. The choice of rational forms of the equipment flow parts when using whirling and swirling flows to increase efficiency of the heat-power equipment and of flow regimes and burning on the basis of deep study of the flow and heat transfer local parameters was set as the main research prospect. In this regard, there is noticeable progress in research methods of whirling and swirling flows. The number of computational treatments of swirling flows' local parameters has been increased. Development and advancement of the up to date computing models and national productivity software are very important for this process. All experimental works are carried out with up to date research methods of the local thermoshydraulic parameters, which enable one to reveal physical mechanisms of processes: PIV and LIV visualization techniques, high-speed and infrared photography, high speed registration of parameters of high-speed processes, etc. There is a problem of improvement of researchers' professional skills in the field of fluid mechanics to set adequately mathematics and physics problems of aerohydrodynamics for whirling and swirling flows and numerical and pilot investigations. It has been pointed out that issues of improvement of the cooling system and thermal protection effectiveness of heat-power and heat-transfer equipment units are still actual. It can be solved successfully using whirling and swirling flows as simple low power consumption exposing on the flow method and heat transfer augmentation.

  15. Prediction of heat transfer to a thin liquid film in plane and radially spreading flows

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.; Swanson, T. D.

    1990-01-01

    The energy equation is incorporated in the solution algorithm of Rahman et al. (1990) to compute the heat transfer to a thin film in the presence or absence of gravity. For a plane flow under zero gravity, it is found that, for both isothermal and uniformly heated walls, the heat transfer coefficient gradually decreases downstream, with Nu-asterisk (the Nusselt number in terms of film height) remaining approximately constant except for regions very close to the entrance. In the case of radial flow under zero gravity, Nu-asterisk is found to decrease monotonically when the plane is uniformly heated. Two different flow regimes are identified in the presence of gravity for both plane and radial flows. The results of the study may be applicable to the design of space-based cooling systems.

  16. Critical heat flux of subcooled flow boiling with water for high heat flux application

    NASA Astrophysics Data System (ADS)

    Inasaka, Fujio; Nariai, Hideki

    1993-11-01

    Subcooled flow boiling in water is thought to be advantageous in removing high heat load of more than 10 MW/m2. Characteristics of the critical heat flux (CHF), which determines the upper limit of heat removal, are very important for the design of cooling systems. In this paper, studies on subcooled flow boiling CHF, which have been conducted by the authors, are reported. Experiments were conducted using direct current heating of stainless steel tube. For uniform heating conditions, CHF increment in small diameter tubes (1 - 3 mm inside diameter) and the CHF characteristics in tubes with internal twisted tapes were investigated, and also the existing CHF correlations for ordinary tubes (more than 3 mm inside diameter) were evaluated. For peripherally non-uniform heating conditions using the tube, whose wall thickness was partly reduced, the CHF for swirl flow was higher than the CHF under uniform heating conditions with an increase of the non-uniformity factor.

  17. The surface heat flow of the Arabian Shield in Jordan

    NASA Astrophysics Data System (ADS)

    Förster, A.; Förster, H.-J.; Masarweh, R.; Masri, A.; Tarawneh, K.; Desert Group

    2007-04-01

    Surface heat flow in southern Jordan (western part of the Arabian Plate) was determined in a dense cluster of five, up to 900-m-deep boreholes that have encountered sedimentary rocks of Paleozoic (Ordovician and Silurian) age. These rocks are underlain by an igneous and metamorphic basement, which has been studied for its radiogenic heat production, along the eastern margin of the Dead Sea Transform (DST) fault system. The heat flow, calculated from continuous temperature logs and laboratory-measured thermal conductivity of drillcores and surface samples, averages to 60.3 ± 3.4 mW m -2 and contrasts the common view of the late Proterozoic-consolidated Arabian Shield constituting a low heat-flow province of ⩽45 mW m -2. Although only characterizing an area of about 300 km 2, this average is unlikely representing a positive local anomaly caused by voluminous HHP granites/rhyolites at shallow depths. Instead, a heat flow of 60 mW m -2 is considered a robust estimate of the Phanerozoic conductive surface heat flow not only for Jordan, but for the Arabian Shield in areas unaffected by younger reactivation. The large variation in conductive heat flow (36-88 mW m -2) previously observed in Jordan, southern Syria, and Saudi Arabia is irreconcilable with their broad similarity in lithosphere structure and composition and rather reflects a combination of factors including low-quality temperature data and insufficient knowledge on thermal rock properties.

  18. Conjugate Compressible Fluid Flow and Heat Transfer in Ducts

    NASA Technical Reports Server (NTRS)

    Cross, M. F.

    2011-01-01

    A computational approach to modeling transient, compressible fluid flow with heat transfer in long, narrow ducts is presented. The primary application of the model is for analyzing fluid flow and heat transfer in solid propellant rocket motor nozzle joints during motor start-up, but the approach is relevant to a wide range of analyses involving rapid pressurization and filling of ducts. Fluid flow is modeled through solution of the spatially one-dimensional, transient Euler equations. Source terms are included in the governing equations to account for the effects of wall friction and heat transfer. The equation solver is fully-implicit, thus providing greater flexibility than an explicit solver. This approach allows for resolution of pressure wave effects on the flow as well as for fast calculation of the steady-state solution when a quasi-steady approach is sufficient. Solution of the one-dimensional Euler equations with source terms significantly reduces computational run times compared to general purpose computational fluid dynamics packages solving the Navier-Stokes equations with resolved boundary layers. In addition, conjugate heat transfer is more readily implemented using the approach described in this paper than with most general purpose computational fluid dynamics packages. The compressible flow code has been integrated with a transient heat transfer solver to analyze heat transfer between the fluid and surrounding structure. Conjugate fluid flow and heat transfer solutions are presented. The author is unaware of any previous work available in the open literature which uses the same approach described in this paper.

  19. Heat flow and near-surface radioactivity in the Australian continental crust

    USGS Publications Warehouse

    Sass, J.H.; Jaeger, J.C.; Munroe, Robert J.

    1976-01-01

    be related to thermal transients associated with Late Tertiary and younger volcanic and tectonic activity, even though the relation between heat-flow values and the age of volcanism is not a simple one. Parts of the high heat-flow area in the southeast might be exploitable for geothermal energy.

  20. 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

  1. Utilizing thermal isostasy to estimate sub-lithospheric heat flow and anomalous crustal radioactivity

    NASA Astrophysics Data System (ADS)

    Hasterok, D.; Gard, M.

    2016-09-01

    While surface heat flow relates to the heat loss through the lithosphere, it can be difficult to quantify and separate the heat produced internally through radiogenic decay from the heat transferred across the base of the lithosphere by mantle convection. In this study, we apply a thermo-isostatic analysis to Australia and estimate the sub-lithospheric and radiogenic heat flow components by employing a simple 1-D conservation of energy model. We estimate an anomalous radiogenic heat production across much of eastern Australia generally accounting for >50 mW m-2, while western Australia appears to have high crustal compositionally corrected elevation, possibly related to chemical buoyancy of the mantle lithosphere. A moderately high sub-lithospheric heat flow (∼40 mW m-2) along the eastern and southeastern coast, including Tasmania, is coincident with locations of Cenozoic volcanism and supports an edge-driven convection hypothesis. However, the pattern of sub-lithospheric heat flow along the margin does not support the existence of hotspot tracks. Thermo-isostatic models such as these improve our ability to identify and quantify crustal from mantle sources of heat loss and add valuable constraints on tectonic and geodynamic models of the continental lithosphere's physical state and evolution.

  2. Enhanced two phase flow in heat transfer systems

    DOEpatents

    Tegrotenhuis, Ward E; Humble, Paul H; Lavender, Curt A; Caldwell, Dustin D

    2013-12-03

    A family of structures and designs for use in devices such as heat exchangers so as to allow for enhanced performance in heat exchangers smaller and lighter weight than other existing devices. These structures provide flow paths for liquid and vapor and are generally open. In some embodiments of the invention, these structures can also provide secondary heat transfer as well. In an evaporate heat exchanger, the inclusion of these structures and devices enhance the heat transfer coefficient of the evaporation phase change process with comparable or lower pressure drop.

  3. Modeling Io's Heat Flow: Constraints from Galileo PPR Data

    NASA Technical Reports Server (NTRS)

    Rathbun, J. A.; Spencer, J. R.; Tamppari, L. K.

    2000-01-01

    We attempt to improve on previous Io heat flow estimates by using higher resolution data from Galileo Photopolarimeter Radiometer (PPR) and improved thermophysical models of the surface, including finite thermal inertia, the pedestal effect, and disk-resolved radiance.

  4. Heat flow measurements on the southeast coast of Australia

    USGS Publications Warehouse

    Hyndman, R.D.; Jaeger, J.C.; Sass, J.H.

    1969-01-01

    Three boreholes have been drilled for the Australian National University near the southeast coast of New South Wales, Australia. The heat flows found are 1.1, 1.0, and 1.3 ??cal/cm2sec. The errors resulting from the proximity of the sea and a lake, surface temperature change, conductivity structure and water flow have been examined. The radioactive heat production in some of the intrusive rocks of the area have also been measured. The heat flows are much lower than the values of about 2.0 found elsewhere in south eastern Australia. The lower values appear to be part of a distinct heat flow province in eastern Australia. ?? 1969.

  5. Oregon Cascades Play Fairway Analysis: Faults and Heat Flow maps

    SciTech Connect

    Adam Brandt

    2015-11-15

    This submission includes a fault map of the Oregon Cascades and backarc, a probability map of heat flow, and a fault density probability layer. More extensive metadata can be found within each zip file.

  6. On the relation between coronal heating, flux tube divergence, and the solar wind proton flux and flow speed

    NASA Technical Reports Server (NTRS)

    Sandbaek, Onulf; Leer, Egil; Hansteen, Viggo H.

    1994-01-01

    A one-fluid solar wind model is used to investigate some relations between coronal heating, the flux tube divergence near the Sun, and the solar wind proton flux and flow speed. The effects of energy addition to the supersonic region of the flow are also studied. We allow for a mechanical energy flux that heats the corona, and an Alfven wave energy flux that adds energy, mainly to the supersonic flow, both as momentum and as heat. We find that the mechanical energy flux determines the solar wind mass flux, and in order to keep an almost constant proton flux at the orbit of Earth with changing flow geometry, that the mechanical energy flux must vary linearly with the magnetic field in the inner corona. This thermally driven wind generally has a low asymptotic flow speed. When Alfven waves are added to the thermally driven flow, the asymptotic flow speed is increased and is determined by the ratio of the Alfven wave and the mechanical energy fluxes at the coronal base. Flow speeds characteristic of recurrent high-speed solar wind streams can be obtained only when the Alfven wave energy flux, deposited in the supersonic flow, is larger than the mechanical energy flux heating the corona.

  7. Heat flow studies in Wyoming: 1979 to 1981

    SciTech Connect

    Heasler, H.P.; Decker, E.R.; Buelow, K.L.; Ruscetta, C.A.

    1982-05-01

    Heat flow values and updated maps of flux in Wyoming, northern Colorado, and southern Montana are presented. It is concluded that most of the heat flow values in the Wyoming Basin-Southern Rocky Mountains region in Southern Wyoming are low or normal, excluding the Saratoga Valley; that the regional flux in the Owl Creek Mountains area is above normal; and that the Meadow Creek Basin area is in a zone of high flux. (MJF)

  8. Heat flow vs. atmospheric greenhouse on early Mars

    NASA Technical Reports Server (NTRS)

    Fanale, F. P.; Postawko, S. E.

    1991-01-01

    Researchers derived a quantitative relationship between the effectiveness of an atmospheric greenhouse and internal heat flow in producing the morphological differences between earlier and later Martian terrains. The derivation is based on relationships previously derived by other researchers. The reasoning may be stated as follows: the CO2 mean residence time in the Martian atmosphere is almost certainly much shorter than the total time span over which early climate differences are thought to have been sustained. Therefore, recycling of previously degassed CO2 quickly becomes more important than the ongoing supply of juvenile CO2. If so, then the atmospheric CO2 pressure, and thereby the surface temperature, may be approximated mathematically as a function of the total degassed CO2 in the atmosphere plus buried material and the ratio of the atmospheric and regolith mean residence times. The latter ratio can also be expressed as a function of heat flow. Hence, it follows that the surface temperature may be expressed as a function of heat flow and the total amount of available CO2. However, the depth to the water table can simultaneously be expressed as a function of heat flow and the surface temperature (the boundary condition). Therefore, for any given values of total available CO2 and regolith conductivity, there exist coupled independent equations which relate heat flow, surface temperature, and the depth to the water table. This means we can now derive simultaneous values of surface temperature and the depth of the water table for any value of the heat flow. The derived relationship is used to evaluate the relative importance of the atmospheric greenhouse effect and the internal regolith thermal gradient in producing morphological changes for any value of the heat flow, and to assess the absolute importance of each of the values of the heat flow which are thought to be reasonable on independent geophysical grounds.

  9. Study on the Heat-Flow Controllable Heat Exchanger-3rd report

    NASA Astrophysics Data System (ADS)

    Ishikawa, Osamu; Hamano, Masayoshi; Yanadori, Michio

    The heat-flow controllable heat exchanger for the purpose of heat recovery through the waste hot water at the bathroom and the washing room has been developed. The system is especially available at the house of cold area and the recovery heat is used to warm the suction air conducted from ventilation device. As the result of field test, it is clarified that the heat recovery rate by the system is very large. Also, the exchanger is possible to control the amount of recorery heat. Therefore, it is considered that the exchanger is applicable in the ventilation systems used the waste hot water.

  10. New computer program solves wide variety of heat flow problems

    NASA Technical Reports Server (NTRS)

    Almond, J. C.

    1966-01-01

    Boeing Engineering Thermal Analyzer /BETA/ computer program uses numerical methods to provide accurate heat transfer solutions to a wide variety of heat flow problems. The program solves steady-state and transient problems in almost any situation that can be represented by a resistance-capacitance network.

  11. Natural Regulation of Energy Flow in a Green Quantum Photocell.

    PubMed

    Arp, Trevor B; Barlas, Yafis; Aji, Vivek; Gabor, Nathaniel M

    2016-12-14

    Manipulating the flow of energy in nanoscale and molecular photonic devices is of both fundamental interest and central importance for applications in light energy harvesting optoelectronics. Under erratic solar irradiance conditions, unregulated power fluctuations in a light-harvesting photocell lead to inefficient energy storage in conventional solar cells and potentially fatal oxidative damage in photosynthesis. Here, we compare the theoretical minimum energy fluctuations in nanoscale quantum heat engine photocells that incorporate one or two photon-absorbing channels and show that fluctuations are naturally suppressed in the two-channel photocell. This intrinsic suppression acts as a passive regulation mechanism that enables the efficient conversion of varying incident solar power into a steady output for absorption over a broad range of the solar spectrum on Earth. Remarkably, absorption in the green portion of the spectrum provides no inherent regulatory benefit, indicating that green light should be rejected in a photocell whose primary role is the regulation of energy flow.

  12. Capture of Geothermal Heat as Chemical Energy

    DOE PAGES

    Jody, Bassam J.; Petchsingto, Tawatchai; Doctor, Richard D.; ...

    2015-12-11

    In this paper, fluids that undergo endothermic reactions were evaluated as potential chemical energy carriers of heat from geothermal reservoirs for power generation. Their performance was compared with that of H2O and CO2. The results show that (a) chemical energy carriers can produce more power from geothermal reservoirs than water and CO2 and (b) working fluids should not be selected solely on the basis of their specific thermo-physical properties but rather on the basis of the rate of exergy (ideal power) they can deliver. Finally, this article discusses the results of the evaluation of two chemical energy carrier systems: ammoniamore » and methanol/water mixtures.« less

  13. Capture of Geothermal Heat as Chemical Energy

    SciTech Connect

    Jody, Bassam J.; Petchsingto, Tawatchai; Doctor, Richard D.; Snyder, Seth W.

    2015-12-11

    In this paper, fluids that undergo endothermic reactions were evaluated as potential chemical energy carriers of heat from geothermal reservoirs for power generation. Their performance was compared with that of H2O and CO2. The results show that (a) chemical energy carriers can produce more power from geothermal reservoirs than water and CO2 and (b) working fluids should not be selected solely on the basis of their specific thermo-physical properties but rather on the basis of the rate of exergy (ideal power) they can deliver. Finally, this article discusses the results of the evaluation of two chemical energy carrier systems: ammonia and methanol/water mixtures.

  14. Electroosmotic Entry Flow with Joule Heating Effects

    NASA Astrophysics Data System (ADS)

    Prabhakaran, Rama; Kale, Akshay; Xuan, Xiangchun

    Electrokinetic flow, which transports liquids by electroosmosis and samples by electrophoresis, is the transport method of choice in microfluidic chips over traditional pressure-driven flows. Studies on electrokinetic flows have so far been almost entirely limited to inside microchannels. Very little work has been done on the electroosmotic fluid entry from a reservoir to a microchannel, which is the origin of all fluid and sample motions in microchips. We demonstrate in this talk that strong vortices of opposite circulating directions can be generated in electroosmotic entry flows. We also develop a two-dimensional depth-averaged numerical model of the entire microchip to predict and understand the fluid temperature and flow fields at the reservoir-microchannel junction.

  15. Numerical model for swirl flow cooling in high-heat-flux particle beam targets and the design of a swirl-flow-based plasma limiter

    SciTech Connect

    Milora, S.L.; Combs, S.K.; Foster, C.A.

    1984-11-01

    An unsteady, two-dimensional heat conduction code has been used to study the performance of swirl-flow-based neutral particle beam targets. The model includes the effects of two-phase heat transfer and asymmetric heating of tubular elements. The calorimeter installed in the Medium Energy Test Facility, which has been subjected to 30-s neutral beam pulses with incident heat flux intensities of greater than or equal to 5 kW/cm/sup 2/, has been modeled. The numerical results indicate that local heat fluxes in excess of 7 kW/cm/sup 2/ occur at the water-cooled surface on the side exposed to the beam. This exceeds critical heat flux limits for uniformly heated tubes wih straight flow by approximately a factor of 5. The design of a plasma limiter based on swirl flow heat transfer is presented.

  16. Energy density and energy flow of magnetoplasmonic waves on graphene

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2017-03-01

    By means the linearized magnetohydrodynamic theory, expressions for energy density and energy flow are derived for the p-polarized surface magnetoplasmon polaritons on graphene in the Voigt configuration, where a static magnetic field is normal to the graphene surface. Numerical results show that the external magnetic field has significant impact on the energy density and energy transport velocity of magnetoplasmon waves in the long-wavelength region, while total power flow vary only weakly with magnetostatic field. The velocity of energy propagation is proved to be identical with group velocity of the surface waves.

  17. Heat flow analysis in connection with thermoplastic filament winding

    NASA Astrophysics Data System (ADS)

    Brage, Anders; Lamrell, Charles

    1988-04-01

    In thermoplastic filament winding the calculated rate of cooling is found to be in the order of 100000 degr.C/second at the bonding interface. Short range heat flow phenomena are analyzed, and the result provides a simple rule of thumb for practice, together with a winding speed dependant correction for glass and carbon fiber composites. This enables an easy method to calculate the lower temperature limits for the process of continuous welding, as well as the upper temperature limit where resin starved laminates result from excessive resin flow due to heat buildup. The applied model of heat transfer is given in analytical expressions. Calculated results are given in several graphs.

  18. A heat-flow reconnaissance of southeastern Alaska.

    USGS Publications Warehouse

    Sass, J.H.; Lawver, L.A.; Munroe, R.J.

    1985-01-01

    Heat flow was measured at nine sites in crystalline and sedimentary rocks of SE Alaska. Seven of the sites, located between 115 and 155 km landward of the Queen Charlotte-Fairweather transform fault, have heat flows significantly higher than the mean in the coastal provinces between Cape Mendocino and the Queen Charlotte Islands, and lower than the mean for 81 values within 100 km of the San Andreas transform fault, even further S. There is no evidence for heat sources that might be associated with late Cainozoic thermal events.-P.Br.

  19. Topographically driven groundwater flow and the San Andreas heat flow paradox revisited

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.; Hickman, S.

    2003-01-01

    Evidence for a weak San Andreas Fault includes (1) borehole heat flow measurements that show no evidence for a frictionally generated heat flow anomaly and (2) the inferred orientation of ??1 nearly perpendicular to the fault trace. Interpretations of the stress orientation data remain controversial, at least in close proximity to the fault, leading some researchers to hypothesize that the San Andreas Fault is, in fact, strong and that its thermal signature may be removed or redistributed by topographically driven groundwater flow in areas of rugged topography, such as typify the San Andreas Fault system. To evaluate this scenario, we use a steady state, two-dimensional model of coupled heat and fluid flow within cross sections oriented perpendicular to the fault and to the primary regional topography. Our results show that existing heat flow data near Parkfield, California, do not readily discriminate between the expected thermal signature of a strong fault and that of a weak fault. In contrast, for a wide range of groundwater flow scenarios in the Mojave Desert, models that include frictional heat generation along a strong fault are inconsistent with existing heat flow data, suggesting that the San Andreas Fault at this location is indeed weak. In both areas, comparison of modeling results and heat flow data suggest that advective redistribution of heat is minimal. The robust results for the Mojave region demonstrate that topographically driven groundwater flow, at least in two dimensions, is inadequate to obscure the frictionally generated heat flow anomaly from a strong fault. However, our results do not preclude the possibility of transient advective heat transport associated with earthquakes.

  20. Use of a turboexpander in steam power units for heat energy recovery in heat supply systems

    NASA Astrophysics Data System (ADS)

    Sadykov, R. A.; Daminov, A. Z.; Solomin, I. N.; Futin, V. A.

    2016-05-01

    A method for raising the efficiency of a boiler plant by installing a unit operating by the organic Rankine cycle is presented. Such units allow one to generate electricity to cover the auxiliaries of a heat source at a heat-transfer fluid temperature of no more than 130°C. The results of commissioning tests of boilers revealed that their efficiency is maximized under a load that is close or corresponds to the nominal one. If this load is maintained constantly, excess heat energy is produced. This excess may be used to generate electric energy in a steam power unit with a turboexpander. A way to insert this unit into the flow diagram of a boiler plant is proposed. The results of analysis of turbine types (turboexpanders included) with various capacities are presented, and the optimum type for the proposed flow diagram is chosen. The methodology for the design of turboexpanders and compressors used in the oil and gas industry and their operational data were applied in the analysis of a turboexpander. The results of the thermogasdynamic analysis of a turboexpander and the engineered shape of an axial-radial impeller are presented. Halocarbon R245fa is chosen as the working medium based on its calorimetric properties.

  1. Oscillating flow loss test results in Stirling engine heat exchangers

    NASA Technical Reports Server (NTRS)

    Koester, G.; Howell, S.; Wood, G.; Miller, E.; Gedeon, D.

    1990-01-01

    The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

  2. Numerical computations of Orbiter flow fields and heating rates

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Li, C. P.; Houston, C. K.; Chiu, P.; Olmedo, L.

    1976-01-01

    Numerical computations of flow fields around an analytical description of the Space Shuttle Orbiter windward surface, including the root of the wing leading edge, are presented to illustrate the sensitivity of these calculations to several flow field modeling assumptions. Results of parametric flow field and boundary layer computations using the axisymmetric analogue concept to obtain three-dimensional heating rates, in conjunction with exact three-dimensional inviscid floe field solutions and two-dimensional boundary layer analysis - show the sensitivity of boundary layer edge conditions and heating rates to considerations of the inviscid flow field entropy layer, equilibrium air versus chemically and vibrationally frozen flow, and nonsimilar terms in the boundary layer computations. A cursory comparison between flow field predictions obtained from these methods and current Orbiter design methods has established a benchmark for selecting and adjusting these and future design methodologies.

  3. Electrochemical systems configured to harvest heat energy

    DOEpatents

    Lee, Seok Woo; Yang, Yuan; Ghasemi, Hadi; Chen, Gang; Cui, Yi

    2017-01-31

    Electrochemical systems for harvesting heat energy, and associated electrochemical cells and methods, are generally described. The electrochemical cells can be configured, in certain cases, such that at least a portion of the regeneration of the first electrochemically active material is driven by a change in temperature of the electrochemical cell. The electrochemical cells can be configured to include a first electrochemically active material and a second electrochemically active material, and, in some cases, the absolute value of the difference between the first thermogalvanic coefficient of the first electrochemically active material and the second thermogalvanic coefficient of the second electrochemically active material is at least about 0.5 millivolts/Kelvin.

  4. Chaotic advection and heat transfer in two similar 2-D periodic flows and in their corresponding 3-D periodic flows

    NASA Astrophysics Data System (ADS)

    Vinsard, G.; Dufour, S.; Saatdjian, E.; Mota, J. P. B.

    2016-03-01

    Chaotic advection can effectively enhance the heat transfer rate between a boundary and fluids with high Prandtl number. These fluids are usually highly viscous and thus turbulent agitation is not a viable solution since the energy required to mix the fluid would be prohibitive. Here, we analyze previously obtained results on chaotic advection and heat transfer in two similar 2-D periodic flows and on their corresponding 3-D periodic flows when an axial velocity component is superposed. The two flows studied are the flow between eccentric rotating cylinders and the flow between confocal ellipses. For both of these flows the analysis is simplified because the Stokes equations can be solved analytically to obtain a closed form solution. For both 2-D periodic flows, we show that chaotic heat transfer is enhanced by the displacement of the saddle point location during one period. Furthermore, the enhancement by chaotic advection in the elliptical geometry is approximately double that obtained in the cylindrical geometry because there are two saddle points instead of one. We also explain why, for high eccentricity ratios, there is no heat transfer enhancement in the cylindrical geometry. When an axial velocity component is added to both of these flows so that they become 3-D, previous work has shown that there is an optimum modulation frequency for which chaotic advection and heat transfer enhancement is a maximum. Here we show that the optimum modulation frequency can be derived from results without an axial flow. We also explain by physical arguments other previously unanswered questions in the published data.

  5. Heat flow map of the western Mediterranean basins

    SciTech Connect

    Foucher, J.P.; Burrus, J.; Vedova, B.D.

    1988-08-01

    More than 400 terrestrial heat flow determinations have been carried our in the western Mediterranean basins. These include results of detailed surveys in the Ligurian Sea and in the Gulf of Lions and Tyrrhenian basins, as well as sparse measurements in the Gulf of Valencia and the Algerian basin. Most of the measurements are surficial, obtained from the temperatures sensed by outrigged thermistors mounted on weight-driven probes penetrating the sediment to 3 to 10 m. Thermal conductivity was measured either on cores or in situ. The authors present a heat flow map of the western Mediterranean basins based on the available geothermal results. Mean regional heat flow values range from 55 to 105 mW m/sup /minus/2/ in the Lugiran and Gulf of Lions basin and from 50 to 200 m mW m/sup /minus/2/ in the Tyrrhenian Sea. In the latter basin, high heat flow characterizes areas of recent intensive thinning of the continental crust and associated incipient oceanic crust formation. In the former basins, heat flow tends to increase from the Provencal coast of France to the Corsican and Sardinian margins, which may reflect on increasing heat contribution from the mantle.

  6. Transient fluid flow and heat transfer in petroleum production systems

    NASA Astrophysics Data System (ADS)

    Lin, Dongqing

    Heat transfer is an important phenomenon in both wellbore and reservoir. The pertinent temperature distribution can provide a valuable perspective in analyzing and optimizing the oil production. In this work, two kinds of co-production, production fluid through the annulus and tubing, and through two independent tubings, have been modeled using steady state analysis. The fluid temperatures in the production string and annulus have been solved analytically in both cases. Furthermore, we extended the theory of steady state energy transport to remedy asphaltene deposition problem by circulating the cooling fluid in the annulus. Due to the complex nature of two-phase flow in the oil/gas production, more reliable mechanistic modeling approaches have been developed since early 1980's. Rooted in Hasan-Kabir model, we have developed a wellbore/reservoir coupling simulator for the transient non-Darcy two-phase flow in the flow-after-flow well test. The entire historical flow behavior has been modeled using superposition method and validated with field data. Our second simulation is for the investigation of a blowout well, which is a great concern in the oil field. When the pressure in the wellbore is sufficiently high, the fluids will attain sonic velocity at the wellhead. We presented a computational algorithm to estimate the blowout rate in a given wellbore/reservoir system and examined four major parameters, such as formation permeability, Gas-Oil-Ratio (GOR), reservoir pressure and tubing diameter. The transient nature of this approach also illustrates the evolution process of a blowout. We have also developed a transient simulator to determine the location and severity of a blockage in a gas pipeline based on the theory of two-phase flow and pressure transient analysis. The presence of a sizeable blockage will affect the outlet gas pressure response by decreasing the available pipe volume and increasing the friction loss of the fluid flow. The simulator solves for the

  7. Numerical simulation of transitional flows with heat transfer

    NASA Astrophysics Data System (ADS)

    Kožíšek, Martin; Příhoda, Jaromír; Fürst, Jiří; Straka, Petr

    2016-06-01

    The contribution deals with simulation of internal flows with the laminar/turbulent transition and heat transfer. The numerical modeling of incompressible flow on a heated flat plate was carried out partly by the k-kL-ω model of Walters and Cokljat [1] and partly by the algebraic transition model of Straka and Příhoda [2] connected with the EARSM turbulence model of Hellsten [3]. Transition models were tested by means of the skin friction and the Stanton number distribution. Used models of turbulent heat transfer were compared with the simplest model based on the constant turbulent Prandtl number. The k-kL-ω model is applied for the simulation of compressible flow through the VKI turbine blade cascade with heat transfer.

  8. Lunar heat flow: Regional prospective of the Apollo landing sites

    NASA Astrophysics Data System (ADS)

    Siegler, M. A.; Smrekar, S. E.

    2014-01-01

    reexamine the Apollo Heat Flow Experiment in light of new orbital data. Using three-dimensional thermal conduction models, we examine effects of crustal thickness, density, and radiogenic abundance on measured heat flow values at the Apollo 15 and 17 sites. These models show the importance of regional context on heat flux measurements. We find that measured heat flux can be greatly altered by deep subsurface radiogenic content and crustal density. However, total crustal thickness and the presence of a near-surface radiogenic-rich ejecta provide less leverage, representing only minor (<1.5 mW m-2) perturbations on surface heat flux. Using models of the crust implied by Gravity Recovery and Interior Laboratory results, we found that a roughly 9-13 mW m-2 mantle heat flux best approximate the observed heat flux. This equates to a total mantle heat production of 2.8-4.1 × 1011 W. These heat flow values could imply that the lunar interior is slightly less radiogenic than the Earth's mantle, perhaps implying that a considerable fraction of terrestrial mantle material was incorporated at the time of formation. These results may also imply that heat flux at the crust-mantle boundary beneath the Procellarum potassium, rare earth element, and phosphorus (KREEP) Terrane (PKT) is anomalously elevated compared to the rest of the Moon. These results also suggest that a limited KREEP-rich layer exists beneath the PKT crust. If a subcrustal KREEP-rich layer extends below the Apollo 17 landing site, required mantle heat flux can drop to roughly 7 mW m-2, underlining the need for future heat flux measurements outside of the radiogenic-rich PKT region.

  9. Heat to electricity conversion by cold carrier emissive energy harvesters

    SciTech Connect

    Strandberg, Rune

    2015-12-07

    This paper suggests a method to convert heat to electricity by the use of devices called cold carrier emissive energy harvesters (cold carrier EEHs). The working principle of such converters is explained and theoretical power densities and efficiencies are calculated for ideal devices. Cold carrier EEHs are based on the same device structure as hot carrier solar cells, but works in an opposite way. Whereas a hot carrier solar cell receives net radiation from the sun and converts some of this radiative heat flow into electricity, a cold carrier EEH sustains a net outflux of radiation to the surroundings while converting some of the energy supplied to it into electricity. It is shown that the most basic type of cold carrier EEHs have the same theoretical efficiency as the ideal emissive energy harvesters described earlier by Byrnes et al. In the present work, it is also shown that if the emission from the cold carrier EEH originates from electron transitions across an energy gap where a difference in the chemical potential of the electrons above and below the energy gap is sustained, power densities slightly higher than those given by Byrnes et al. can be achieved.

  10. Instability of flow of liquid film over a heated surface

    SciTech Connect

    Sha, W.T.; Soo, S.L.

    1994-08-01

    Fundamental concepts and basic equations of a flowing thin liquid film cooling a heated surfaced by its vaporization and the effect of dry patches were treated. Stable film flow prior to the appearance of dry patches on the heated surface is maintained by a balance of various forces due to surface tension, shear stress, heat and mass transfer, and gravity. Film splitting at a critical film thickness produces dry patches due to perturbation by waves on a perfect surface, and often by surface imperfection and uneven heating. This work is primarily motivated by the design of next-generation nuclear reactors, which employ many novel passive heat-removal systems via natural circulation. These systems are design to prevent damage to the reactor core and containment without action by the reactor operators during or after a design basis accident such as a loss of coolant accident (LOCA) or a main steam-line break (MSLB) accident.

  11. Recent trends in energy flows through the Arctic climate system

    NASA Astrophysics Data System (ADS)

    Mayer, Michael; Haimberger, Leo

    2016-04-01

    While Arctic climate change can be diagnosed in many parameters, a comprehensive assessment of long-term changes and low frequency variability in the coupled Arctic energy budget still remains challenging due to the complex physical processes involved and the lack of observations. Here we draw on strongly improved observational capabilities of the past 15 years and employ observed radiative fluxes from CERES along with state-of-the-art atmospheric as well as coupled ocean-ice reanalyses to explore recent changes in energy flows through the Arctic climate system. Various estimates of ice volume and ocean heat content trends imply that the energy imbalance of the Arctic climate system was >1 Wm-2 during the 2000-2015 period, where most of the extra heat warmed the ocean and a comparatively small fraction was used to melt sea ice. The energy imbalance was partly fed by enhanced oceanic heat transports into the Arctic, especially in the mid 2000s. Seasonal trends of net radiation show a very clear signal of the ice-albedo feedback. Stronger radiative energy input during summer means increased seasonal oceanic heat uptake and accelerated sea ice melt. In return, lower minimum sea ice extent and higher SSTs lead to enhanced heat release from the ocean during fall season. These results are consistent with modeling studies finding an enhancement of the annual cycle of surface energy exchanges in a warming Arctic. Moreover, stronger heat fluxes from the ocean to the atmosphere in fall tend to warm the arctic boundary layer and reduce meridional temperature gradients, thereby reducing atmospheric energy transports into the polar cap. Although the observed results are a robust finding, extended high-quality datasets are needed to reliably separate trends from low frequency variability.

  12. A novel compact heat exchanger using gap flow mechanism

    NASA Astrophysics Data System (ADS)

    Liang, J. S.; Zhang, Y.; Wang, D. Z.; Luo, T. P.; Ren, T. Q.

    2015-02-01

    A novel, compact gap-flow heat exchanger (GFHE) using heat-transfer fluid (HTF) was developed in this paper. The detail design of the GFHE coaxial structure which forms the annular gap passage for HTF is presented. Computational fluid dynamics simulations were introduced into the design to determine the impacts of the gap width and the HTF flow rate on the GFHE performance. A comparative study on the GFHE heating rate, with the gap widths ranged from 0.1 to 1.0 mm and the HTF flow rates ranged from 100 to 500 ml/min, was carried out. Results show that a narrower gap passage and a higher HTF flow rate can yield a higher average heating rate in GFHE. However, considering the compromise between the GFHE heating rate and the HTF pressure drop along the gap, a 0.4 mm gap width is preferred. A testing loop was also set up to experimentally evaluate the GFHE capability. The testing results show that, by using 0.4 mm gap width and 500 ml/min HTF flow rate, the maximum heating rate in the working chamber of the as-made GFHE can reach 18 °C/min, and the average temperature change rates in the heating and cooling processes of the thermal cycle test were recorded as 6.5 and 5.4 °C/min, respectively. These temperature change rates can well satisfy the standard of IEC 60068-2-14:2009 and show that the GFHE developed in this work has sufficient heat exchange capacity and can be used as an ideal compact heat exchanger in small volume desktop thermal fatigue test apparatus.

  13. A novel compact heat exchanger using gap flow mechanism.

    PubMed

    Liang, J S; Zhang, Y; Wang, D Z; Luo, T P; Ren, T Q

    2015-02-01

    A novel, compact gap-flow heat exchanger (GFHE) using heat-transfer fluid (HTF) was developed in this paper. The detail design of the GFHE coaxial structure which forms the annular gap passage for HTF is presented. Computational fluid dynamics simulations were introduced into the design to determine the impacts of the gap width and the HTF flow rate on the GFHE performance. A comparative study on the GFHE heating rate, with the gap widths ranged from 0.1 to 1.0 mm and the HTF flow rates ranged from 100 to 500 ml/min, was carried out. Results show that a narrower gap passage and a higher HTF flow rate can yield a higher average heating rate in GFHE. However, considering the compromise between the GFHE heating rate and the HTF pressure drop along the gap, a 0.4 mm gap width is preferred. A testing loop was also set up to experimentally evaluate the GFHE capability. The testing results show that, by using 0.4 mm gap width and 500 ml/min HTF flow rate, the maximum heating rate in the working chamber of the as-made GFHE can reach 18 °C/min, and the average temperature change rates in the heating and cooling processes of the thermal cycle test were recorded as 6.5 and 5.4 °C/min, respectively. These temperature change rates can well satisfy the standard of IEC 60068-2-14:2009 and show that the GFHE developed in this work has sufficient heat exchange capacity and can be used as an ideal compact heat exchanger in small volume desktop thermal fatigue test apparatus.

  14. A survey of oscillating flow in Stirling engine heat exchangers

    NASA Technical Reports Server (NTRS)

    Simon, Terrence W.; Seume, Jorge R.

    1988-01-01

    Similarity parameters for characterizing the effect of flow oscillation on wall shear stress, viscous dissipation, pressure drop and heat transfer rates are proposed. They are based on physical agruments and are derived by normalizing the governing equations. The literature on oscillating duct flows, regenerator and porous media flows is surveyed. The operating characteristics of the heat exchanger of eleven Stirling engines are discribed in terms of the similarity parameters. Previous experimental and analytical results are discussed in terms of these parameters and used to estimate the nature of the oscillating flow under engine operating conditions. The operating points for many of the modern Stirling engines are in or near the laminar to turbulent transition region. In several engines, working fluid does not pass entirely through heat exchangers during a cycle. Questions that need to be addressed by further research are identified.

  15. Energy flows, metabolism and translation

    PubMed Central

    Pascal, Robert; Boiteau, Laurent

    2011-01-01

    Thermodynamics provides an essential approach to understanding how living organisms survive in an organized state despite the second law. Exchanges with the environment constantly produce large amounts of entropy compensating for their own organized state. In addition to this constraint on self-organization, the free energy delivered to the system, in terms of potential, is essential to understand how a complex chemistry based on carbon has emerged. Accordingly, the amount of free energy brought about through discrete events must reach the strength needed to induce chemical changes in which covalent bonds are reorganized. The consequence of this constraint was scrutinized in relation to both the development of a carbon metabolism and that of translation. Amino acyl adenylates involved as aminoacylation intermediates of the latter process reach one of the higher free energy levels found in biochemistry, which may be informative on the range in which energy was exchanged in essential early biochemical processes. The consistency of this range with the amount of energy needed to weaken covalent bonds involving carbon may not be accidental but the consequence of the abovementioned thermodynamic constraints. This could be useful in building scenarios for the emergence and early development of translation. PMID:21930587

  16. Energy flows, metabolism and translation.

    PubMed

    Pascal, Robert; Boiteau, Laurent

    2011-10-27

    Thermodynamics provides an essential approach to understanding how living organisms survive in an organized state despite the second law. Exchanges with the environment constantly produce large amounts of entropy compensating for their own organized state. In addition to this constraint on self-organization, the free energy delivered to the system, in terms of potential, is essential to understand how a complex chemistry based on carbon has emerged. Accordingly, the amount of free energy brought about through discrete events must reach the strength needed to induce chemical changes in which covalent bonds are reorganized. The consequence of this constraint was scrutinized in relation to both the development of a carbon metabolism and that of translation. Amino acyl adenylates involved as aminoacylation intermediates of the latter process reach one of the higher free energy levels found in biochemistry, which may be informative on the range in which energy was exchanged in essential early biochemical processes. The consistency of this range with the amount of energy needed to weaken covalent bonds involving carbon may not be accidental but the consequence of the above mentioned thermodynamic constraints. This could be useful in building scenarios for the emergence and early development of translation.

  17. Relations between heat flow, topography and Moho depth for Europe

    NASA Astrophysics Data System (ADS)

    Polkowski, Marcin; Majorowicz, Jacek; Grad, Marek

    2013-04-01

    The relation between heat flow, topography and Moho depth for recent maps of Europe is presented. New heat flow map of Europe (Majorowicz and Wybraniec, 2010) is based on updated database of uncorrected heat flow values to which paleoclimatic correction is applied across the continental Europe. Correction is depth dependent due to a diffusive thermal transfer of the surface temperature forcing of which glacial-interglacial history has the largest impact. This explains some very low uncorrected heat flow values 20-30 mW/m2 in the shields, shallow basin areas of the cratons, and in other areas including orogenic belts were heat flow was likely underestimated. New integrated map of the European Moho depth (Grad et al., 2009) is the first high resolution digital map for European plate understand as an area from Ural Mountains in the east to mid-Atlantic ridge in the west, and Mediterranean Sea in the south to Spitsbergen and Barents Sea in Arctic in the north. For correlation we used: onshore heat flow density data with palaeoclimatic correction (5318 locations), topography map (30 x 30 arc seconds; Danielson and Gesch, 2011) and Moho map (longitude, latitude and Moho depth, each 0.1 degree). Analysis was done in areas where data from all three datasets were available. Continental Europe area could be divided into two large domains related with Precambrian East European craton and Palaeozoic Platform. Next two smaller areas correspond to Scandinavian Caledonides and Anatolia. Presented results show different correlations between Moho depth, elevation and heat flow for all discussed regions. For each region more detailed analysis of these relation in different elevation ranges is presented. In general it is observed that Moho depth is more significant to HF then elevation. Depending on region and elevation range HF value in mW/m2 is up to two times larger than Moho depth in km, while HF relation to elevation varies much more.

  18. Heat flow anomalies in oil- and gas-bearing structures

    SciTech Connect

    Sergiyenko, S.I.

    1988-02-01

    The main features of the distribution of heat flow values in oil, gas and gas-condensate fields on the continents have been discussed by Makarenko and Sergiyenko. The method of analysis used made it possible to establish that the presence of hydrocarbons in formations leads to high heat-flow, regardless of the age of folding of the potentially oil- and gas-bearing zones. Only in regions adjacent to marginal Cenozoic folded mountain structures and in zones of Cenozoic volcanism is the world average higher, by 2.5 to 10%, than in the oil- and gas-bearing structures in those regions. The earlier analysis of the distribution of heat flow values in oil and gas structures was based on 403 measurements. The author now has nearly doubled the sample population, enabling him substantially to revise the ideas on the distribution of heat flow values and the development of the thermal regime of local oil and gas structures. He notes that the method previously used, comparing heat flow values on young continental platforms with values in local oil and gas structures, makes it possible to estimate the thermal effect of the presence of oil and gas. This conclusion stems from the fact that the overwhelming majority of heat flow measurements were made on various kinds of positive structural forms, and distortions of the thermal field caused by thermal anisotropy phenomena are equally characteristic of both productive and nonproductive structures. As a result, for the first time a continuous time series of heat flow measurements over oil and gas structures in various tectonic regions, with ages of consolidation ranging from the Precambrian to the Cenozoic, was established. 26 references.

  19. Distributed energy tapestry for heating the landscape

    NASA Astrophysics Data System (ADS)

    Rocha, L. A. O.; Lorente, S.; Bejan, A.

    2010-12-01

    Here we show that the production and use of heating on an area must be distributed in clusters organized such that the losses associated with centers of production are balanced by the losses associated with distribution lines. The energy needs increase in time because the population density and the individual need increase. We consider only the increase in the individual need in time. We illustrate the "distributed energy systems" concept with the production and distribution of hot water on an area. Four classes of designs are analyzed and compared: (0) individual, i.e., one water heater for one user, (r) radial, i.e., N users supplied via radial pipes from a central heater, (2) dendritic network constructed by pairing N users around a central heating, and (4) dendritic network constructed by quadrupling the elemental areas occupied by the users. We show that there is an optimal cluster size (N) as a tradeoff between central losses and distributed losses. We also discover that several distinct (abrupt) design "transitions" must exist: the recommended design changes through designs 0, r, 2, and 4, as the amount of water used by each individual increases in time with the standard of living.

  20. Heat Flow Pattern and Thermal Resistance Modeling of Anisotropic Heat Spreaders

    NASA Astrophysics Data System (ADS)

    Falakzaadeh, F.; Mehryar, R.

    2017-01-01

    To ensure safe operating temperatures of the ever smaller heat generating electronic devices, drastic measures should be taken. Heat spreaders are used to increase surface area, by spreading the heat without necessarily transferring it to the ambient in the first place. The heat flow pattern is investigated in heat spreaders and the fundamental differences regarding how heat conducts in different materials is addressed. Isotropic materials are compared with anisotropic ones having a specifically higher in-plane thermal conductivity than through plane direction. Thermal resistance models are proposed for anisotropic and isotropic heat spreaders in compliance with the order of magnitude of dimensions used in electronics packaging. After establishing thermal resistance models for both the isotropic and anisotropic cases, numerical results are used to find a correlation for predicting thermal resistance in anisotropic heat spreaders with high anisotropy ratios.

  1. Heat transfer intensification by increasing vapor flow rate in flat heat pipes

    NASA Astrophysics Data System (ADS)

    Sprinceana, Silviu; Mihai, Ioan; Beniuga, Marius; Suciu, Cornel

    2015-02-01

    Flat heat pipes have various technical applications, one of the most important being the cooling of electronic components[9]. Their continuous development is due to the fact that these devices permit heat transfer without external energetic contribution. The practical exploitation of flat heat pipes however is limited by the fact that dissipated power can only reach a few hundred watts. The present paper aims to advance a new method for the intensification of convective heat transfer. A centrifugal mini impeller, driven by a turntable which incorporates four permanent magnets was designed. These magnets are put in motion by another rotor, which in its turn includes two permanent magnets and is driven by a mini electrical motor. Rotation of the centrifugal blades generates speed and pressure increase of the cooling agent brought to vapor state within the flat micro heat pipe. It's well known that the liquid suffers biphasic transformations during heat transfer inside the heat pipe. Over the hotspot (the heat source being the electronic component) generated at one end of the heat pipe, convective heat transfer occurs, leading to sudden vaporization of the liquid. Pressures generated by newly formed vapors push them towards the opposite end of the flat heat pipe, where a finned mini heat sink is usually placed. The mini-heat exchanger is air-cooled, thus creating a cold spot, where vapors condensate. The proposed method contributes to vapor flow intensification by increasing their transport speed and thus leading to more intense cooling of the heat pipe.

  2. Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia.

    PubMed

    Birkelund, Yngve; Jacobsen, Svein; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2009-07-07

    This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom-made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 x 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid set-up monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for the improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network.

  3. Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia

    PubMed Central

    Birkelund, Yngve; Jacobsen, Svein; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2009-01-01

    This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 × 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid setup monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network. PMID:19494426

  4. Heat production in an Archean crustal profile and implications for heat flow and mobilization of heat-producing elements

    NASA Technical Reports Server (NTRS)

    Ashwal, L. D.; Morgan, P.; Kelley, S. A.; Percival, J. A.

    1987-01-01

    Concentrations of heat producing elements (Th, U, and K) in 58 samples representative of the main lithologies in a 100-km transect of the Superior Province of the Canadian Shield have been obtained. The relatively large variation in heat production found among the silicic plutonic rocks is shown to correlate with modal abundances of accessory minerals, and these variations are interpreted as premetamorphic. The present data suggest fundamental differences in crustal radioactivity distributions between granitic and more mafic terrains, and indicate that a previously determined apparently linear heat flow-heat production relationship for the Kapuskasing area does not relate to the distribution of heat production with depth.

  5. Basic data for some recent Australian heat-flow measurements

    USGS Publications Warehouse

    Munroe, Robert J.; Sass, J.H.; Milburn, G.T.; Jaeger, J.C.; Tammemagi, H.Y.

    1975-01-01

    This report has been compiled to provide background information and detailed temperature and thermal conductivity data for the heat-flow values reported in Sass, Jaeger, and Munroe (in press). The data were collected as part of a joint heat-flow study by the Australian National University (ANU) and the U.S. Geological Survey (USGS) under the direction of J. C. Jaeger (ANU) and J. H. Sass (USGS). The format is similar to that used for basic data from United States heat-flow determinations (Sass and Munroe, 1974). Each section contains a state map showing the geographic distribution of heat-flow data followed by tables which list individual temperatures, thermal conductivities, and radiogenic heat production values. A companion volume (Bunker and others, 1975) gives details of the heat-production measurements together with individual radioelement concentrations. Localities are arranged in alphabetical order within each state. The methods and techniques of measurements have been described by Sass and others (1971a, b). Unusual methods or procedures which differ markedly from these techniques are noted and described in the comments sections of the tables.

  6. Energy storage: Redox flow batteries go organic

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Sprenkle, Vince

    2016-03-01

    The use of renewable resources as providers to the electrical grid is hampered by the intermittent and irregular nature in which they generate energy. Electrical energy storage technology could provide a solution and now, by using an iterative design process, a promising anolyte for use in redox flow batteries has been developed.

  7. Supersonic flow with feeding of energy

    NASA Technical Reports Server (NTRS)

    Zaremba, W.

    1985-01-01

    The present work discusses the results of some experimental studies on the possibility of attenuating shock waves in a supersonic flow. The shock waves were formed by an external source of electrical energy. An electromechanical method is described that permits partial recovery of the expended energy.

  8. Joule Heating Effects on Electrokinetic Flow Instabilities in Ferrofluids

    NASA Astrophysics Data System (ADS)

    Brumme, Christian; Shaw, Ryan; Zhou, Yilong; Prabhakaran, Rama; Xuan, Xiangchun

    We have demonstrated in our earlier work that the application of a tangential electric field can draw fluid instabilities at the interface of a ferrofluid/water co-flow. These electrokinetic flow instabilities are produced primarily by the mismatch of electric conductivities of the two fluids. We demonstrate in this talk that the Joule heating induced fluid temperature rises and gradients can significantly suppress the electrokinetic flow instabilities. We also develop a two-dimensional depth-averaged numerical model to predict the fluid temperature, flow and concentration fields in the two-fluid system with the goal to understand the Joule heating effects on electric field-driven ferrofluid flow instabilities. This work was supported by the Honors and Creative Inquiry programs at Clemson University.

  9. Heat flow through the sea bottom around the Yucatan Peninsula

    NASA Astrophysics Data System (ADS)

    Khutorskoy, M. D.; Fernandez, R.; Kononov, V. I.; Polyak, B. G.; Matveev, V. G.; Rot, A. A.

    1990-02-01

    Heat flow studies were conducted in January-February 1987, off the Atlantic Coast of Mexico on board the R/V Akademik Nikolai Strakhov. Two areas were surveyed, one transecting the Salt Dome Province and the Campeche Canyon, in the Gulf of Mexico, and the other, on the eastern flank of the Yucatan Peninsula. Conductive heat flow through the bottom sediments was determined as the product of vertical temperature gradient and in situ thermal conductivity, measured with a thermal probe using a multithermistor array and real-time processing capabilities. Forward two-dimensional modeling allows us to estimate heat flow variations at both sites from local disturbances and to obtain average heat flow values of 51 mW/m2 for the transect within the Gulf of Mexico and 38 and 69 mW/m2 for two basins within the Yucatan area. Sea bottom relief has a predominant effect over other environmental factors in the scatter of heat flow determination in the Gulf of Mexico.

  10. Percussive and Proboscis Based Lunar Heat Flow Probes

    NASA Astrophysics Data System (ADS)

    Mumm, E.; Zacny, K.; Kumar, N.

    2009-12-01

    The subsurface temperature of the Moon is strongly influenced by the diurnal, annual, and precession fluctuations of the insolation. Therefore, to measure the heat flow, the probe has to be inserted to a depth of at least 3m. There are a number of ways the heat flow probe can be deployed. These methods differ in many ways such as simplicity and mass of the deployment system, power required to deploy it, extent of thermal isolation between temperature sensors and between sensors themselves and surface system (deployment system, lander, electronics box etc), thermal sensor placement within the hole (radiative as opposed to conducive coupling), and methods of deployment. The percussive based heat flow probe utilizes a percussive approach to drive a small diameter (20mm) cone penetrometer to >3 meter depths, deploying ring-like thermal sensors every 30 cm. It leaves only small sensors in the borehole, maximizing measurement sensitivity by minimizing thermal coupling from the lander to the electrical tether. The proboscis based heat flow probe utilizes a pneumatic (gas) approach to lower the heat flow probe, a lenticular tape, to 3 meters. The system offers extremely low mass, volume, and simple deployment.

  11. Heat flow through the sea bottom around the Yucatan Peninsula

    SciTech Connect

    Khutorskoy, M.D.; Kononov, V.I.; Polyak, B.G. ); Fernandez, R. ); Matveev, V.G.; Rot, A.A. )

    1990-02-10

    Heat flow studies were conducted in January-February 1987, off the Atlantic Coast of Mexico on board the R/V Akademik Nikolai Strakhov. Two areas were surveyed, one transecting the Salt Dome Province and the Campeche Canyon, in the Gulf of Mexico, and the other, on the eastern flank of the Yucatan Peninsula. Conductive heat flow through the bottom sediments was determined as the product of vertical temperature gradient and in situ thermal conductivity, measured with a thermal probe using a multithermistor array and real-time processing capabilities. Forward two-dimensional modeling allows one to estimate heat flow variations at both sites from local disturbances and to obtain average heat flow values of 51 mW/m{sup 2} for the transect within the Gulf of Mexico and 38 and 69 mW/m{sup 2} for two basins within the Yucatan area. Sea bottom relief has a predominant effect over other environmental factors in the scatter of heat flow determination in the Gulf of Mexico.

  12. California energy flow in 1993

    SciTech Connect

    Borg, I.Y.; Briggs, C.K.

    1995-04-01

    Energy consumption in the state of California decreased about 3% in 1993 reflecting continuation of the recession that was manifest in a moribund construction industry and a high state unemployment that ran counter to national recovery trends. Residential/commercial use decreased slightly reflecting a mild winter in the populous southern portion of the state, a decrease that was offset to some extent by an increase in the state population. Industrial consumption of purchased energy declined substantially as did production of self-generated electricity for in-house use. Consumption in the transportation sector decreased slightly. The amount of power transmitted by the utilities was at 1992 levels; however a smaller proportion was produced by the utilities themselves. Generation of electricity by nonutilities, primarily cogenerators and small power producers, was the largest of any state in the US. The growth in the number of private power producers combined with increased amounts of electricity sold to the public utilities set the stage for the sweeping proposals before the California Public Utility Commission to permit direct sales from the nonutilities to retail customers. California production of both oil and natural gas declined; however, to meet demand only the imports of natural gas increased. A break in the decade-long drought during the 1992--1993 season resulted in a substantial increase in the amount of hydroelectricity generated during the year. Geothermal energy`s contribution increased substantially because of the development of new resources by small power producers. Decline in steam production continued at The Geysers, the state`s largest field, principally owned and managed by a public utility. Increases in windpower constituted 1--1/2% of the total electric supply--up slightly from 1992. Several solar photo voltaic demonstration plants were in operation, but their contribution remained small.

  13. Energy fluxes in turbulent separated flows

    NASA Astrophysics Data System (ADS)

    Mollicone, J.-P.; Battista, F.; Gualtieri, P.; Casciola, C. M.

    2016-10-01

    Turbulent separation in channel flow containing a curved wall is studied using a generalised form of Kolmogorov equation. The equation successfully accounts for inhomogeneous effects in both the physical and separation spaces. We investigate the scale-by-scale energy dynamics in turbulent separated flow induced by a curved wall. The scale and spatial fluxes are highly dependent on the shear layer dynamics and the recirculation bubble forming behind the lower curved wall. The intense energy produced in the shear layer is transferred to the recirculation region, sustaining the turbulent velocity fluctuations. The energy dynamics radically changes depending on the physical position inside the domain, resembling planar turbulent channel dynamics downstream.

  14. Brine flow in heated geologic salt.

    SciTech Connect

    Kuhlman, Kristopher L.; Malama, Bwalya

    2013-03-01

    This report is a summary of the physical processes, primary governing equations, solution approaches, and historic testing related to brine migration in geologic salt. Although most information presented in this report is not new, we synthesize a large amount of material scattered across dozens of laboratory reports, journal papers, conference proceedings, and textbooks. We present a mathematical description of the governing brine flow mechanisms in geologic salt. We outline the general coupled thermal, multi-phase hydrologic, and mechanical processes. We derive these processes governing equations, which can be used to predict brine flow. These equations are valid under a wide variety of conditions applicable to radioactive waste disposal in rooms and boreholes excavated into geologic salt.

  15. A heat transfer model for slug flow boiling within microchannels

    NASA Astrophysics Data System (ADS)

    Magnini, Mirco; Thome, John

    2016-11-01

    We propose a novel physics-based model for the fluid mechanics and heat transfer associated with slug flow boiling in horizontal circular microchannels, to update the widely used three-zone model for the design of multi-microchannel evaporators. The flow is modelled as the cyclic passage of a liquid slug, an elongated bubble which traps a thin liquid film against the channel wall, and a dry vapor plug. The capillary flow theory, extended to incorporate evaporation effects, is applied to estimate the bubble velocity along the channel. A liquid film thickness prediction method considering bubble proximity effects, which may limit the radial extension of the film, is included. Theoretical heat transfer models accounting for the thermal inertia of the liquid film and for the recirculating flow within the liquid slug are utilized. The heat transfer model is compared to experimental data taken from three independent studies: 833 slug flow boiling data points covering R134a, R245fa and R236fa and channel diameters from 0.4 mm to 1 mm. The new model predicts more than 80% of the database to within +/- 30 % and it represents an important step toward a complete physics-based modelling of bubble dynamics and heat transfer within microchannels under evaporating flow conditions.

  16. Neutron radigoraphy of fluid flow for geothermal energy research

    SciTech Connect

    Bingham, Philip R.; Polsky, Yarom; Anovitz, L.; Carmichael, Justin R.; Bilheux, Hassina Z; Jacobson, David; Hussey, Dan

    2015-01-01

    Enhanced geothermal systems seek to expand the potential for geothermal energy by engineering heat exchange systems within the earth. A neutron radiography imaging method has been developed for the study of fluid flow through rock under environmental conditions found in enhanced geothermal energy systems. For this method, a pressure vessel suitable for neutron radiography was designed and fabricated, modifications to imaging instrument setups were tested, multiple contrast agents were tested, and algorithms developed for tracking of flow. The method has shown success for tracking of single phase flow through a manufactured crack in a 3.81 cm (1.5 inch) diameter core within a pressure vessel capable of confinement up to 69 MPa (10,000 psi) using a particle tracking approach with bubbles of fluorocarbon-based fluid as the “particles” and imaging with 10 ms exposures.

  17. Vibrational Energy Transfer of Diatomic Gases in Hypersonic Expanding Flows.

    NASA Astrophysics Data System (ADS)

    Ruffin, Stephen Merrick

    In high temperature flows related to vehicles at hypersonic speeds significant excitation of the vibrational energy modes of the gas can occur. Accurate predictions of the vibrational state of the gas and the rates of vibrational energy transfer are essential to achieve optimum engine performance, for design of heat shields, and for studies of ground based hypersonic test facilities. The Landau -Teller relaxation model is widely used because it has been shown to give accurate predictions in vibrationally heating flows such as behind forebody shocks. However, a number of experiments in nozzles have indicated that it fails to accurately predict the rate of energy transfer in expanding, or cooling, flow regions and fails to predict the distribution of energy in the vibrational quantum levels. The present study examines the range of applicability of the Landau -Teller model in expanding flows and develops techniques which provide accurate predictions in expanding flows. In the present study, detailed calculations of the vibrational relaxation process of N_2 and CO in cooling flows are conducted. A coupled set of vibrational transition rate equations and quasi one-dimensional fluid dynamic equations is solved. Rapid anharmonic Vibration-Translation transition rates and Vibration -Vibration exchange collisions are found to be responsible for vibrational relaxation acceleration in situations of high vibrational temperature and low translational temperature. The predictions of the detailed master equation solver are in excellent agreement with experimental results. The exact degree of acceleration is cataloged in this study for N_2 and is found to be a function of both the translational temperature (T) and the ratio of vibrational to translational temperatures (T_{vib}/T). Non-Boltzmann population distributions are observed for values of T _{vib}/T as low as 2.0. The local energy transfer rate is shown to be an order of magnitude or more faster than the Landau-Teller model

  18. Arc-heated gas flow experiments for hypersonic propulsion applications

    NASA Astrophysics Data System (ADS)

    Roseberry, Christopher Matthew

    Although hydrogen is an attractive fuel for a hypersonic air-breathing vehicle in terms of reaction rate, flame temperature, and energy content per unit mass, the substantial tank volume required to store hydrogen imposes a drag penalty to performance that tends to offset these advantages. An alternative approach is to carry a hydrocarbon fuel and convert it on-board into a hydrogen-rich gas mixture to be injected into the engine combustors. To investigate this approach, the UTA Arc-Heated Wind Tunnel facility was modified to run on methane rather than the normally used nitrogen. Previously, this facility was extensively developed for the purpose of eventually performing experiments simulating scramjet engine flow along a single expansion ramp nozzle (SERN) in addition to more generalized applications. This formidable development process, which involved modifications to every existing subsystem along with the incorporation of new subsystems, is described in detail. Fortunately, only a minor plumbing reconfiguration was required to prepare the facility for the fuel reformation research. After a failure of the arc heater power supply, a 5.6 kW plasma-cutting torch was modified in order to continue the arc pyrolysis experiments. The outlet gas flow from the plasma torch was sampled and subsequently analyzed using gas chromatography. The experimental apparatus converted the methane feedstock almost completely into carbon, hydrogen and acetylene. A high yield of hydrogen, consisting of a product mole fraction of roughly 0.7, was consistently obtained. Unfortunately, the energy consumption of the apparatus was too excessive to be feasible for a flight vehicle. However, other researchers have pyrolyzed hydrocarbons using electric arcs with much less power input per unit mass.

  19. Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1997

    SciTech Connect

    Dr. Ronald D. Boyd

    2000-07-01

    The Thermal Science Research Center (TSRC) at Prairie View A&M University is involved in an international fusion reactor technology development program aimed at demonstrating the technical feasibility of magnetic fusion energy. This report highlights: (1) Recent accomplishments and pinpoints thermal hydraulic problem areas of immediate concern to the development of plasma-facing components, and (2) Next generation thermal hydraulic problems which must be addressed to insure safety and reliability in component operation. More specifically, the near-term thermal hydraulic problem entails: (1) generating an appropriate data base to insure the development of single-side heat flux correlations, and (2) evaluating previously developed single-side/uniform heated transformations and correlations to determine which can be used to relate the vast two-phase heat transfer and critical heat flux (CHF) technical literature for uniformly heated flow channels to single-side heated channels.

  20. Eddy diffusivity of heat for drag reducing turbulent pipe flows

    NASA Astrophysics Data System (ADS)

    Yoon, Hyung K.; Ghajar, Afshin J.

    1987-06-01

    Experiments were conducted to verify the assumptions and general applicability of a new semiempirical equation for eddy diffusivity of heat proposed previously for viscoelastic turbulent pipe flows. The experiments were performed for Separan AP-273 and Polyox WSR-301 solutions with concentrations ranging from 10 to 1000 ppm and Separan AP-30 with concentration of 3000 ppm in thermally fully developed turbulent flow in pipes with diameters of 1.11 and 1.88 cm I.D. under constant wall heat flux. The experiments verified the assumptions made in regard to the universality of the minimum asymptotes for friction and heat transfer. The prediction of heat transfer coefficients with the use of the proposed equation for all of the experimental data is within a maximum deviation of 30 percent.

  1. Heat transfer from cylinders in subsonic slip flows

    NASA Technical Reports Server (NTRS)

    Nagabushana, K. A.; Stainback, P. C.

    1992-01-01

    The heat transfer in heated wires was measured using a constant temperature anemometer over a Mach number range from 0.05 to 0.4 and pressures from 0.5 to 8.0 atmospheres. The total temperature ranged from 80 to 120 F and the wire diameters were 0.00015, 0.00032, and 0.00050 inch. The heat transfer data is presented in the form of a corrected Nusselt number. Based on suggested criteria, much of the data was obtained in the slip flow regime. Therefore, the data is compared with data having comparable flow conditions. The possible application of the heat transfer data to hot wire anemometry is discussed. To this end, the sensitivity of the wires to velocity, density, and total temperature is computed and compared using two different types of correlations.

  2. Heat transfer during intermittent/slug flow in horizontal tubes

    SciTech Connect

    Shoham, O.; Dukler, A.E.; Taitel, Y.

    1982-08-01

    Heat transfer characteristics for two-phase gas-liquid slug flow in a horizontal pipe have been measured. The time variation of temperature, heat transfer coefficients, and heat flux is reported for the different zones of slug flow: the mixing region at the nose, the body of the slug, the liquid film, and the gas bubble behind the slug. Substantial differences in heat transfer coefficient exist between the bottom and top of the slug. This results from the fact that each slug is effectively a thermally developing entry region caused by the presence of a hot upper wall just upstream of each slug. A qualitative theory is presented which explains this behavior. 18 refs.

  3. The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

    NASA Astrophysics Data System (ADS)

    Imura, Hideaki; Takeshita, Kazuhiro; Doi, Kyoji; Noda, Ken-Ichi

    A two-phase loop thermosyphon is used as a heat transfer device in an energy-saving heat transportation system and so forth, because it transports thermal energy without any external power supply such as a pump under a body force field. We previously performed a fundamental study on the flow and heat transfer characteristics in a two-phase loop thermosyphon installed with a single heated tube evaporator both experimentally and theoretically which was made under the condition of near saturation temperature of liquid in a reservoir. In the present study, the effects of liquid subcooling and the heat input on the circulation mass flow rates, pressure and temperature distributions, and heat transfer coefficients in the evaporator were examined experimentally using water, ethanol, benzene and Freon 113 as the working fluids. On the other hand, the circulation mass flow rates, pressure and temperature distributions were theoretically calculated and compared with the experimental results.

  4. Geothermal energy: clean power from the Earth's heat

    USGS Publications Warehouse

    Duffield, Wendell A.; Sass, John H.

    2003-01-01

    Societies in the 21st century require enormous amounts of energy to drive the machines of commerce and to sustain the lifestyles that many people have come to expect. Today, most of this energy is derived from oil, natural gas, and coal, supplemented by nuclear power. Local exceptions exist, but oil is by far the most common source of energy worldwide. Oil resources, however, are nonrenewable and concentrated in only a few places around the globe, creating uncertainty in long-term supply for many nations. At the time of the Middle East oil embargo of the 1970s, about a third of the United States oil supply was imported, mostly from that region. An interruption in the flow of this import disrupted nearly every citizen’s daily life, as well as the Nation’s economy. In response, the Federal Government launched substantial programs to accelerate development of means to increasingly harness “alternative energies”—primarily biomass, geothermal, solar, and wind. The new emphasis on simultaneously pursuing development of several sources of energy recognized the timeless wisdom found in the proverb of “not putting all eggs in one basket.” This book helps explain the role that geothermal resources can play in helping promote such diversity and in satisfying our Nation’s vast energy needs as we enter a new millennium. For centuries, people have enjoyed the benefits of geothermal energy available at hot springs, but it is only through technological advances made during the 20th century that we can tap this energy source in the subsurface and use it in a variety of ways, including the generation of electricity. Geothermal resources are simply exploitable concentrations of the Earth’s natural heat (thermal energy). The Earth is a bountiful source of thermal energy, continuously producing heat at depth, primarily by the decay of naturally occurring radioactive isotopes—principally of uranium, thorium, and potassium—that occur in small amounts in all rocks

  5. A PCM/forced convection conjugate transient analysis of energy storage systems with annular and countercurrent flows

    NASA Technical Reports Server (NTRS)

    Cao, Y.; Faghri, A.; Juhasz, A.

    1991-01-01

    Latent heat energy storage systems with both annular and countercurrent flows are modeled numerically. The change of phase of the phase-change material (PCM) and the transient forced convective heat transfer for the transfer fluid are solved simultaneously as a conjugate problem. A parametric study and a system optimization are conducted. It is found that the energy storage system with the countercurrent flow is an efficient way to absorb heat energy in a short period for pulsed power load space applications.

  6. Numerical and Experimental Approaches Toward Understanding Lava Flow Heat Transfer

    NASA Astrophysics Data System (ADS)

    Rumpf, M.; Fagents, S. A.; Hamilton, C.; Crawford, I. A.

    2013-12-01

    We have performed numerical modeling and experimental studies to quantify the heat transfer from a lava flow into an underlying particulate substrate. This project was initially motivated by a desire to understand the transfer of heat from a lava flow into the lunar regolith. Ancient regolith deposits that have been protected by a lava flow may contain ancient solar wind, solar flare, and galactic cosmic ray products that can give insight into the history of our solar system, provided the records were not heated and destroyed by the overlying lava flow. In addition, lava-substrate interaction is an important aspect of lava fluid dynamics that requires consideration in lava emplacement models Our numerical model determines the depth to which the heat pulse will penetrate beneath a lava flow into the underlying substrate. Rigorous treatment of the temperature dependence of lava and substrate thermal conductivity and specific heat capacity, density, and latent heat release are imperative to an accurate model. Experiments were conducted to verify the numerical model. Experimental containers with interior dimensions of 20 x 20 x 25 cm were constructed from 1 inch thick calcium silicate sheeting. For initial experiments, boxes were packed with lunar regolith simulant (GSC-1) to a depth of 15 cm with thermocouples embedded at regular intervals. Basalt collected at Kilauea Volcano, HI, was melted in a gas forge and poured directly onto the simulant. Initial lava temperatures ranged from ~1200 to 1300 °C. The system was allowed to cool while internal temperatures were monitored by a thermocouple array and external temperatures were monitored by a Forward Looking Infrared (FLIR) video camera. Numerical simulations of the experiments elucidate the details of lava latent heat release and constrain the temperature-dependence of the thermal conductivity of the particulate substrate. The temperature-dependence of thermal conductivity of particulate material is not well known

  7. Heat flow and subsurface temperature distributions in central and western New York. Volume 2

    SciTech Connect

    Hodge, D.S.; Fromm, K.A.

    1982-08-01

    Existing data in western and central New York indicates the possibility of a low-temperature, direct-use geothermal resource. This report evaluates the heat flow and provides a representation of temperatures at depth in this area. This has been done by: (1) analyzing known temperature distributions, (2) measuring the thermal conductivity of sedimentary rock units. Based on this information, areas of higher-than-normal heat flow and temperatures in possible geothermal source reservoirs are described to aid in targeting areas for the exploitation of geothermal energy in New York.

  8. Analysis of laminar flow heat transfer in uniform temperature circular tubes with tape inserts

    NASA Astrophysics Data System (ADS)

    Manglik, R. M.; Bergles, A. E.

    1986-05-01

    Constant property, laminar flow heat transfer in a semicircular tube with uniform wall temperature has been analyzed to define the lower bound of heat transfer augmentation in circular tubes with twisted-tape inserts. Two thermal boundary conditions, which correspond to the two extremes of the fin effect of twisted tapes encountered in practical applications, are considered. Numerical solutions, employing finite-difference formulations for the governing momentum and energy equations were carried out for the thermal entrance region and for fully developed flow.

  9. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramadas K.

    2006-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  10. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramdas K.

    2007-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  11. Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

    2013-12-01

    Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the

  12. Heat flow and geothermal studies in the state of Washington

    SciTech Connect

    Blackwell, D.D.; Steele, J.L.; Kelley, S.A.

    1985-08-01

    Existing geothermal gradient and heat flow data for the state of Washington are summarized. In addition, information on mean-annual ground surface temperatures is included. The data consist of accurate, detailed temperature-depth measurements in selected available holes throughout the state of Washington made between 1979 and 1982. Measurements of thermal conductivity on selected rock samples from these drill holes and ancillary information required to assess the significance of the data and calculate heat flow values were obtained as well. Information is presented on the mean-annual ground-surface temperatures throughout the state of Washington. 32 refs., 15 figs., 4 tabs.

  13. Prediction of strongly-heated internal gas flows

    SciTech Connect

    McEligot, D.M. ||; Shehata, A.M.; Kunugi, Tomoaki |

    1997-12-31

    The purposes of the present article are to remind practitioners why the usual textbook approaches may not be appropriate for treating gas flows heated from the surface with large heat fluxes and to review the successes of some recent applications of turbulence models to this case. Simulations from various turbulence models have been assessed by comparison to the measurements of internal mean velocity and temperature distributions by Shehata for turbulent, laminarizing and intermediate flows with significant gas property variation. Of about fifteen models considered, five were judged to provide adequate predictions.

  14. Convective heat flow in space cryogenics plugs - Critical and moderate He II heat flux densities

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1990-01-01

    Plug flow rates of entropy, heat and normal fluid in phase separators and in zero net mass flow systems are, to some extent, quite similar. A simplified analysis of critical conditions is presented in agreement with data trends. A critical temperature gradient arises on the basis of the He II two-fluid model at the stability limit constraining the thermohydrodynamics of the system. Thus, the question of critical thermodynamic fluctuations associated with nucleation versus the possibility of critical gradients in externally imposed parameters is answered in favor of the latter route toward turbulence. Furthermore, a similarity equation is presented which incorporates size dependent rates for moderate heat flow densities observed in experiments.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  16. High energy density redox flow device

    SciTech Connect

    Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa

    2014-05-13

    Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.

  17. Thermal heat-balance mode flow-to-frequency converter

    NASA Astrophysics Data System (ADS)

    Pawlowski, Eligiusz

    2016-11-01

    This paper presents new type of thermal flow converter with the pulse frequency output. The integrating properties of the temperature sensor have been used, which allowed for realization of pulse frequency modulator with thermal feedback loop, stabilizing temperature of sensor placed in the flowing medium. The system assures balancing of heat amount supplied in impulses to the sensor and heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output impulses is proportional to the heat transfer coefficient from sensor to environment. According to the King's law, the frequency of those impulses is a function of medium flow velocity around the sensor. The special feature of presented solution is total integration of thermal sensor with the measurement signal conditioning system. Sensor and conditioning system are not the separate elements of the measurement circuit, but constitute a whole in form of thermal heat-balance mode flow-to-frequency converter. The advantage of such system is easiness of converting the frequency signal to the digital form, without using any additional analogue-to-digital converters. The frequency signal from the converter may be directly connected to the microprocessor input, which with use of standard built-in counters may convert the frequency into numerical value of high precision. Moreover, the frequency signal has higher resistance to interference than the voltage signal and may be transmitted to remote locations without the information loss.

  18. A Conceptual Change Model for Teaching Heat Energy, Heat Transfer and Insulation

    ERIC Educational Resources Information Center

    Lee, C. K.

    2014-01-01

    This study examines the existing knowledge that pre-service elementary teachers (PSETs) have regarding heat energy, heat transfer and insulation. The PSETs' knowledge of heat energy was initially assessed by using an activity: determining which container would be best to keep hot water warm for the longest period of time. Results showed that PSETs…

  19. Incorporation of Condensation Heat Transfer in a Flow Network Code

    NASA Technical Reports Server (NTRS)

    Anthony, Miranda; Majumdar, Alok; McConnaughey, Paul K. (Technical Monitor)

    2001-01-01

    In this paper we have investigated the condensation of water vapor in a short tube. A numerical model of condensation heat transfer was incorporated in a flow network code. The flow network code that we have used in this paper is Generalized Fluid System Simulation Program (GFSSP). GFSSP is a finite volume based flow network code. Four different condensation models were presented in the paper. Soliman's correlation has been found to be the most stable in low flow rates which is of particular interest in this application. Another highlight of this investigation is conjugate or coupled heat transfer between solid or fluid. This work was done in support of NASA's International Space Station program.

  20. Marangoni mixed convection flow with Joule heating and nonlinear radiation

    SciTech Connect

    Hayat, Tasawar; Shaheen, Uzma; Shafiq, Anum; Alsaedi, Ahmed; Asghar, Saleem

    2015-07-15

    Marangoni mixed convective flow of Casson fluid in a thermally stratified medium is addressed. Flow analysis has been carried out in presence of inclined magnetic field. Heat transfer analysis is discussed in the presence of viscous dissipation, Joule heating and nonlinear thermal radiation. The governing nonlinear partial differential equations are first converted into ordinary differential systems and then developed the convergent series solutions. Flow pattern with the influence of pertinent parameters namely the magnetic parameter, Casson fluid parameter, temperature ratio parameter, stratification parameter, Prandtl number, Eckert number and radiation parameter is investigated. Expression of local Nusselt number is computed and analyzed. It is found that the Nusselt number decreases by increasing magnetic parameter, temperature ratio parameter, angle of inclination and stratification parameter. Moreover the effect of buoyancy parameter on the velocity distribution is opposite in both the opposing and assisting flow phenomena. Thermal field and associated layer thickness are enhanced for larger radiation parameter.

  1. MHD Casson nanofluid flow past a wedge with Newtonian heating

    NASA Astrophysics Data System (ADS)

    Ahmad, Kartini; Hanouf, Zahir; Ishak, Anuar

    2017-02-01

    The problem of steady Casson nanofluid flow past a wedge is studied in this paper. The presence of magnetic field along with Newtonian heating at the surface is considered. The governing partial differential equations are first transformed into a set of nonlinear ordinary differential equations by similarity transformations, before being solved numerically using the Keller-box method. The effects of the wedge angle Ω from 0° (horizontal plate) to 180° (vertical plate) as well as of as the magnetic parameter M on the non-Newtonian fluid flow and heat transfer characteristics are investigated. It is found that the surface temperature is slightly higher for the flow over a horizontal plate compared to that over a vertical plate. It is also found that the magnetic field decreases the surface temperature but increases the skin friction. The flow of a Newtonian fluid is found to give higher skin friction as compared to that of Casson fluid.

  2. Snowmass 2001: Jet energy flow project

    SciTech Connect

    C. F. Berger et al.

    2002-12-05

    Conventional cone jet algorithms arose from heuristic considerations of LO hard scattering coupled to independent showering. These algorithms implicitly assume that the final states of individual events can be mapped onto a unique set of jets that are in turn associated with a unique set of underlying hard scattering partons. Thus each final state hadron is assigned to a unique underlying parton. The Jet Energy Flow (JEF) analysis described here does not make such assumptions. The final states of individual events are instead described in terms of flow distributions of hadronic energy. Quantities of physical interest are constructed from the energy flow distribution summed over all events. The resulting analysis is less sensitive to higher order perturbative corrections and the impact of showering and hadronization than the standard cone algorithms.

  3. Heat flux measurement in a high enthalpy plasma flow

    NASA Astrophysics Data System (ADS)

    Löhle, Stefan; Battaglia, Jean-Luc; Gardarein, Jean-Laurent; Jullien, Pierre; van Ootegem, Bruno

    2008-11-01

    It is a widely used approach to measure heat flux in harsh environments like high enthalpy plasma flows, fusion plasma and rocket motor combustion chambers based on solving the inverse heat conduction problem in a semi-infinite environment. This approach strongly depends on model parameters and geometrical aspects of the sensor design. In this work the surface heat flux is determined by solving the inverse heat conduction problem using an identified system as a direct model. The identification of the system is performed using calibration measurements with modern laser technique and advanced data handling. The results of the identified thermo-physical system show that a non-integer model appears most adapted to this particular problem. It is concluded that the new method improves the heat flux sensor significantly and furthermore extend its application to very short measurement times.

  4. Friction-Induced Fluid Heating in Nanoscale Helium Flows

    SciTech Connect

    Li Zhigang

    2010-05-21

    We investigate the mechanism of friction-induced fluid heating in nanoconfinements. Molecular dynamics simulations are used to study the temperature variations of liquid helium in nanoscale Poiseuille flows. It is found that the fluid heating is dominated by different sources of friction as the external driving force is changed. For small external force, the fluid heating is mainly caused by the internal viscous friction in the fluid. When the external force is large and causes fluid slip at the surfaces of channel walls, the friction at the fluid-solid interface dominates over the internal friction in the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force.

  5. Enhanced Phase Synchronization of Blood Flow Oscillations between Heated and Adjacent Non-heated Sacral Skin

    PubMed Central

    Liao, Fuyuan; Jan, Yih-Kuen

    2012-01-01

    The study of skin microcirculation may be used to assess risk for pressure ulcers. It is observed that local heating not only causes an increase in blood flow of the heated skin but also in the adjacent non-heated skin. The underlying physiological mechanism of this indirect vasodilation of the non-heated skin remains unclear. We hypothesized that blood flow oscillations (BFO) in the adjacent non-heated skin area synchronize with BFO in the heated skin, thus inducing a vasodilatory response. We investigated BFO in the heated and adjacent non-heated skin (12.1±1.2 cm distance) on the sacrum in 12 healthy participants. The ensemble empirical mode decomposition (EEMD) was used to decompose blood flow signals into a set of intrinsic mode functions (IMFs), and the IMFs with power spectra over the frequency range of 0.0095–0.02 Hz, 0.02–0.05 Hz, and 0.05–0.15 Hz were chosen as the characteristic components corresponding to metabolic, neurogenic, and myogenic regulations, respectively. Then, the instantaneous phase of the characteristic components was calculated using the Hilbert transform. From the time series of phase difference between a pair of characteristic components, the epochs of phase synchronization were detected. The results showed that myogenic and neurogenic BFO exhibit self-phase synchronization during the slower vasodilation of the heated skin. In the non-heated skin, the degree of synchronization of BFO is associated with the changes in blood flow. PMID:22936012

  6. Gas flow environmental and heat transfer nonrotating 3D program

    NASA Technical Reports Server (NTRS)

    Geil, T.; Steinhoff, J.

    1983-01-01

    A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is being compiled. These data will be used to evaluate and verify three dimensional internal viscous flow models and computational codes. The analytical objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated.

  7. Understanding heat and fluid flow in linear GTA welds

    SciTech Connect

    Zacharia, T.; David, S.A.; Vitek, J.M.

    1992-12-31

    A transient heat flow and fluid flow model was used to predict the development of gas tungsten arc (GTA) weld pools in 1.5 mm thick AISI 304 SS. The welding parameters were chosen so as to correspond to an earlier experimental study which produced high-resolution surface temperature maps. The motivation of the present study was to verify the predictive capability of the computational model. Comparison of the numerical predictions and experimental observations indicate good agreement.

  8. Understanding heat and fluid flow in linear GTA welds

    SciTech Connect

    Zacharia, T.; David, S.A.; Vitek, J.M.

    1992-01-01

    A transient heat flow and fluid flow model was used to predict the development of gas tungsten arc (GTA) weld pools in 1.5 mm thick AISI 304 SS. The welding parameters were chosen so as to correspond to an earlier experimental study which produced high-resolution surface temperature maps. The motivation of the present study was to verify the predictive capability of the computational model. Comparison of the numerical predictions and experimental observations indicate good agreement.

  9. Modeling Heat Flow In a Calorimeter Equipped With a Textured Solar Collector

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Allen, Bradley J.

    2001-01-01

    Heat engines are being considered for generating electric power for minisatellite applications, particularly for those missions in high radiation threat orbits. To achieve this objective, solar energy must be collected and transported to the hot side of the heat engine. A solar collector is needed having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity. To test candidate solar collector concepts, a simple calorimeter was designed, manufactured, and installed in a bench top vacuum chamber to measure heat flow. In addition, a finite element analysis model of the collector/calorimeter combination was made to model this heat flow. The model was tuned based on observations from the as-manufactured collector/calorimeter combination. In addition, the model was exercised to examine other collector concepts, properties, and scale up issues.

  10. A temperature-profile method for estimating flow in geologic heat pipes.

    PubMed

    Birkholzer, Jens T

    2006-05-30

    Above-boiling temperature conditions, as encountered, for example, in geothermal reservoirs and in geologic repositories for the storage of heat-producing radioactive wastes, may induce strong liquid and gas flow processes in porous subsurface environments. The magnitude of these flow processes is extremely hard to measure in the field. We therefore propose a simple temperature-profile method that uses high-resolution temperature data for deriving such information. The energy that is transmitted with the vapor and water flow creates a nearly isothermal zone maintained at about the boiling temperature, referred to as a heat pipe. Characteristic features of measured temperature profiles, such as the differences in the gradients inside and outside of the heat-pipe regions, are used to derive the approximate magnitude of the liquid and gas fluxes in the subsurface.

  11. A Temperature-Profile Method for Estimating Flow Processes in Geologic Heat Pipes

    SciTech Connect

    J.T. Birkholzer

    2005-01-21

    Above-boiling temperature conditions, as encountered, for example, in geothermal reservoirs and in geologic repositories for the storage of heat-producing nuclear wastes, may give rise to strongly altered liquid and gas flow processes in porous subsurface environments. The magnitude of such flow perturbation is extremely hard to measure in the field. We therefore propose a simple temperature-profile method that uses high-resolution temperature data for deriving such information. The energy that is transmitted with the vapor and water flow creates a nearly isothermal zone maintained at about the boiling temperature, referred to as a heat pipe. Characteristic features of measured temperature profiles, such as the differences in the gradients inside and outside of the heat pipe regions, are used to derive the approximate magnitude of the liquid and gas fluxes in the subsurface, for both steady-state and transient conditions.

  12. Relaminarization of turbulent flow on a flat plate by localized surface heating

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio; Nagabushana, K. A.

    1989-01-01

    Relaminarization of a turbulent boundary layer in air on a flat plate is demonstrated experimentally using localized surface heating. Localized heating is achieved by electrically heating a wire embedded in a thermally insulated substrate (Space Shuttle Tile) on the surface. The stability of the flow downstream of the applied control point increases with decreasing stream temperature in the flow direction. The mean and perturbation velocity profiles without control show that the flow is turbulent. With control, these profiles sequentially change from intermittently turbulent to a fully laminar state. In the relaminarization stage, the turbulent energy is dissipated by molecular transport due to viscous and conductivity mechanisms. The new profile adjusts to a lower Reynolds number based on the momentum thickness than that of the previous turbulent state.

  13. A temperature-profile method for estimating flow in geologic heat pipes

    NASA Astrophysics Data System (ADS)

    Birkholzer, Jens T.

    2006-05-01

    Above-boiling temperature conditions, as encountered, for example, in geothermal reservoirs and in geologic repositories for the storage of heat-producing radioactive wastes, may induce strong liquid and gas flow processes in porous subsurface environments. The magnitude of these flow processes is extremely hard to measure in the field. We therefore propose a simple temperature-profile method that uses high-resolution temperature data for deriving such information. The energy that is transmitted with the vapor and water flow creates a nearly isothermal zone maintained at about the boiling temperature, referred to as a heat pipe. Characteristic features of measured temperature profiles, such as the differences in the gradients inside and outside of the heat-pipe regions, are used to derive the approximate magnitude of the liquid and gas fluxes in the subsurface.

  14. Saint Paul Energy Park: the potential for district heating

    SciTech Connect

    Lee, C.; Kron, R.; Davis, H.

    1980-03-01

    The results of ANL's study of the energy and economic aspects of using district heating in the St. Paul Energy Park are summarized. The Energy Park is a 6 million ft/sup 2/ residential, commercial office, and light industrial complex to be built in the midway area of St. Paul, Minnesota. Space heating and cooling design loads for the park were calculated assuming that the ASHRAE's 90-75 energy-conserving construction standards would be used in constructing the park's buildings. Based in part on this assumption, ANL estimated the costs and energy use characteristics of six possible energy system options for supplying Energy Park's space heating, space cooling, and domestic hot water heating needs. The results indicate that in today's economy, a central heating and cooling plant with natural gas boilers and electrically driven centrifugal chillers with thermal storage has good potential for energy and economic savings and clearly merits further consideration.

  15. Thermal energy storage for industrial waste heat recovery

    NASA Technical Reports Server (NTRS)

    Hoffman, H. W.; Kedl, R. J.; Duscha, R. A.

    1978-01-01

    Thermal energy storage systems designed for energy conservation through the recovery, storage, and reuse of industrial process waste heat are reviewed. Consideration is given to systems developed for primary aluminum, cement, the food processing industry, paper and pulp, and primary iron and steel. Projected waste-heat recovery and energy savings are listed for each category.

  16. Phlegethon flow: A proposed origin for spicules and coronal heating

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Mayr, Hans G.

    1986-01-01

    A model was develped for the mass, energy, and magnetic field transport into the corona. The focus is on the flow below the photosphere which allows the energy to pass into, and be dissipated within, the solar atmosphere. The high flow velocities observed in spicules are explained. A treatment following the work of Bailyn et al. (1985) is examined. It was concluded that within the framework of the model, energy may dissipate at a temperature comparable to the temperature where the waves originated, allowing for an equipartition solution of atmospheric flow, departing the sun at velocities approaching the maximum Alfven speed.

  17. Oscillatory/Chaotic Thermocapillary Flow Induced by Radiant Heating

    NASA Technical Reports Server (NTRS)

    DeWitt, Kenneth J.

    1998-01-01

    There is a continuing need to understand the fluid physics occurring under low gravity conditions in processes such as crystal growth, materials processing, and the movement of bubbles or droplets. The fluid flow in such situations is often caused by a gradient in interfacial tension. If a temperature gradient is created due to a heat source, the resulting flow is called thermocapillary flow, a special case of Marangoni Convection. In this study, an experimental investigation was conducted using silicone oil in cylindrical containers with a laser heat source at the free surface. It was desired to determine the conditions under which steady, axisymmetrical thermocapillary flow becomes unstable and oscillatory three-dimensional flow states develop. The critical Marangoni number for each observed oscillatory state was measured as a function of the container aspect ratio and the dynamic Bond number, a measure of buoyant force versus ii thermocapillary force. Various oscillatory modes were observed during three- dimensional convection, and chaotic flow was reached in one test condition. The critical Marangoni numbers are compared with those measured in previous studies, and the power spectra and phase trajectories of the instantaneous surface temperature distributions are used to characterize the routes of transitions to the chaotic flow state. Results show that only superharmonic modes appear in the routes to chaos while infinite number of subharmonic modes occur in flow transitions for pure Rayleigh convection.

  18. Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins

    NASA Astrophysics Data System (ADS)

    Onstad, Andrew J.

    Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves fundamental flow and heat transfer experimentation to explore two new heat exchange systems: in Part I, large arrays of impinging jets with local extraction and in Part II, metal foams used as fins. Jet impingement cooling is widely used in applications ranging from paper manufacturing to the cooling of gas turbine blades because of the very high local heat transfer coefficients that are possible. While the use of single jet impingement results in non-uniform cooling, increased and more uniform mean heat transfer coefficients may be attained by dividing the total cooling flow among an array of smaller jets. Unfortunately, when the spent fluid from the array's central jets interact with the outer jets, the overall mean heat transfer coefficient is reduced. This problem can be alleviated by locally extracting the spent fluid before it is able to interact with the surrounding jets. An experimental investigation was carried out on a compact impingement array (Xn/Djet = 2.34) utilizing local extraction of the spent fluid (Aspent/Ajet = 2.23) from the jet exit plane. Spatially resolved measurements of the mean velocity field within the array were carried out at jet Reynolds numbers of 2300 and 5300 by magnetic resonance velocimetry, MRV. The geometry provided for a smooth transition from the jet to the target surface and out through the extraction holes without obvious flow recirculation. Mean Nusselt number measurements were also carried out for a Reynolds number range of 2000 to 10,000. The Nusselt number was found to increase with the

  19. Dark energy domination in the Virgocentric flow

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Karachentsev, I. D.; Nasonova, O. G.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2010-09-01

    Context. The standard ΛCDM cosmological model implies that all celestial bodies are embedded in a perfectly uniform dark energy background, represented by Einstein's cosmological constant, and experience its repulsive antigravity action. Aims: Can dark energy have strong dynamical effects on small cosmic scales as well as globally? Continuing our efforts to clarify this question, we now focus on the Virgo Cluster and the flow of expansion around it. Methods: We interpret the Hubble diagram from a new database of velocities and distances of galaxies in the cluster and its environment, using a nonlinear analytical model, which incorporates the antigravity force in terms of Newtonian mechanics. The key parameter is the zero-gravity radius, the distance at which gravity and antigravity are in balance. Results: 1. The interplay between the gravity of the cluster and the antigravity of the dark energy background determines the kinematical structure of the system and controls its evolution. 2. The gravity dominates the quasi-stationary bound cluster, while the antigravity controls the Virgocentric flow, bringing order and regularity to the flow, which reaches linearity and the global Hubble rate at distances ⪆15 Mpc. 3. The cluster and the flow form a system similar to the Local Group and its outflow. In the velocity-distance diagram, the cluster-flow structure reproduces the group-flow structure with a scaling factor of about 10; the zero-gravity radius for the cluster system is also 10 times larger. Conclusions: The phase and dynamical similarity of the systems on the scales of 1-30 Mpc suggests that a two-component pattern may be universal for groups and clusters: a quasi-stationary bound central component and an expanding outflow around it, caused by the nonlinear gravity-antigravity interplay with the dark energy dominating in the flow component.

  20. Thermal energy storage systems using fluidized bed heat exchangers

    NASA Technical Reports Server (NTRS)

    Weast, T.; Shannon, L.

    1980-01-01

    A rotary cement kiln and an electric arc furnace were chosen for evaluation to determine the applicability of a fluid bed heat exchanger (FBHX) for thermal energy storage (TES). Multistage shallow bed FBHX's operating with high temperature differences were identified as the most suitable for TES applications. Analysis of the two selected conceptual systems included establishing a plant process flow configuration, an operational scenario, a preliminary FBHX/TES design, and parametric analysis. A computer model was developed to determine the effects of the number of stages, gas temperatures, gas flows, bed materials, charge and discharge time, and parasitic power required for operation. The maximum national energy conservation potential of the cement plant application with TES is 15.4 million barrels of oil or 3.9 million tons of coal per year. For the electric arc furnance application the maximum national conservation potential with TES is 4.5 million barrels of oil or 1.1 million tons of coal per year. Present time of day utility rates are near the breakeven point required for the TES system. Escalation of on-peak energy due to critical fuel shortages could make the FBHX/TES applications economically attractive in the future.

  1. Coherent control of Forster energy transfer in nanoparticle molecules: energy nanogates and plasmonic heat pulses

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. M.; West, R. G.

    2011-10-01

    We study how Forster energy transfer from a semiconductor quantum dot to a metallic nanoparticle can be gated using quantum coherence in quantum dots. We show this allows us to use a laser field to open the flow of the energy transfer for a given period of time (on-state) before it is switched off to about zero. Utilizing such an energy gating process it is shown that quantum-dot-metallic-nanoparticle systems (meta-molecules) can act as functional nanoheaters capable of generating heat pulses with temporal widths determined by their environmental and physical parameters. We discuss the physics behind the energy nanogates using molecular states of such meta-molecules and the resonance fluorescence of the quantum dots.

  2. Heat transfer in thin, compact heat exchangers with circular, rectangular, or pin-fin flow passages

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1992-01-01

    Heat transfer and pressure drop have been measured of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up to 77 W/sq cm. Correlations were developed for the isothermal friction factor as a function of Reynolds number, and for the Nusselt number as a function of Reynolds number and the ratio of wall temperature to fluid temperature. The specimen with the pin fin internal geometry had significantly better heat transfer than the other specimens, but it also had higher pressure drop. For certain conditions of helium flow and heating, the temperature more than doubled from the inlet to the outlet of the specimens, producing large changes in gas velocity, density, viscosity, and thermal conductivity. These changes in properties did not affect the correlations for friction factor and Nusselt number in turbulent flow.

  3. Single phase channel flow forced convection heat transfer

    SciTech Connect

    Hartnett, J.P.

    1999-04-01

    A review of the current knowledge of single phase forced convection channel flow of liquids (Pr > 5) is presented. Two basic channel geometries are considered, the circular tube and the rectangular duct. Both laminar flow and turbulent flow are covered. The review begins with a brief overview of the heat transfer behavior of Newtonian fluids followed by a more detailed presentation of the behavior of purely viscous and viscoelastic Non-Newtonian fluids. Recent developments dealing with aqueous solutions of high molecular weight polymers and aqueous solutions of surfactants are discussed. The review concludes by citing a number of challenging research opportunities.

  4. Computational heat transfer analysis for oscillatory channel flows

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir; Kannapareddy, Mohan

    1993-01-01

    An accurate finite-difference scheme has been utilized to investigate oscillatory, laminar and incompressible flow between two-parallel-plates and in circular tubes. The two-parallel-plates simulate the regenerator of a free-piston Stirling engine (foil type regenerator) and the channel wall was included in the analysis (conjugate heat transfer problem). The circular tubes simulate the cooler and heater of the engine with an isothermal wall. The study conducted covered a wide range for the maximum Reynolds number (from 75 to 60,000), Valensi number (from 2.5 to 700), and relative amplitude of fluid displacement (0.714 and 1.34). The computational results indicate a complex nature of the heat flux distribution with time and axial location in the channel. At the channel mid-plane we observed two thermal cycles (out of phase with the flow) per each flow cycle. At this axial location the wall heat flux mean value, amplitude and phase shift with the flow are dependent upon the maximum Reynolds number, Valensi number and relative amplitude of fluid displacement. At other axial locations, the wall heat flux distribution is more complex.

  5. Terrestrial heat flow and its role in petroleum geology

    NASA Astrophysics Data System (ADS)

    Osipova, E. N.; Ivanov, I. V.; Smirnov, V. A.; Abramova, R. N.

    2015-11-01

    This paper describes an overview of mineral resources exploration survey by geothermal method based on the studies of terrestrial heat flow, anomalies varying in strike, in depth, physical behavior and in time. Applying geothermometry in oil-gas deposit exploration, based on paleotemperature modeling of sedimentation sequences was illustrated.

  6. Heat transfer coefficient for flow boiling in an annular mini gap

    NASA Astrophysics Data System (ADS)

    Hożejowska, Sylwia; Musiał, Tomasz; Piasecka, Magdalena

    2016-03-01

    The aim of this paper was to present the concept of mathematical models of heat transfer in flow boiling in an annular mini gap between the metal pipe with enhanced exterior surface and the external glass pipe. The one- and two-dimensional mathematical models were proposed to describe stationary heat transfer in the gap. A set of experimental data governed both the form of energy equations in cylindrical coordinates and the boundary conditions. The models were formulated to minimize the number of experimentally determined constants. Known temperature distributions in the enhanced surface and in the fluid helped to determine, from the Robin condition, the local heat transfer coefficients at the enhanced surface - fluid contact. The Trefftz method was used to find two-dimensional temperature distributions for the thermal conductive filler layer, enhanced surface and flowing fluid. The method of temperature calculation depended on whether the area of single-phase convection ended with boiling incipience in the gap or the two-phase flow region prevailed, with either fully developed bubbly flow or bubbly-slug flow. In the two-phase flow, the fluid temperature was calculated by Trefftz method. Trefftz functions for the Laplace equation and for the energy equation were used in the calculations.

  7. A review of the heat flow data of NE Morocco

    NASA Astrophysics Data System (ADS)

    Chiozzi, Paolo; Barkaoui, Alae-Eddine; Rimi, Abdelkrim; Verdoya, Massimo; Zarhloule, Yassine

    2016-04-01

    The Atlas chain is characterised by a SW-NE trending volcanic belt roughly extending from the Atlantic to the Mediterranean Sea and showing activity that spans in age mainly from Middle Miocene to Quaternary (14.6-0.3 Ma). The geochemical features of volcanism are mostly intraplate and alkaline with the exception of the northeastern termination of the belt where calc-alkaline series crop out. Lithospheric thermal and density models so far proposed, constrained by heat flow, gravity anomalies, geoid, and topography data, show that the Atlas chain is not supported isostatically by a thickened crust and a thin, hot and low-density lithosphere explains the high topography. One of the possible explanations for lithospheric mantle thinning, possibly in relation with the observed alkaline volcanism, is thermal erosion produced by either small-scale convection or activation of a small mantle plume, forming part of a hot and deep mantle reservoir system extending from the Canary Islands. This paper focuses on the several geothermal data available in the northeastern sector of the volcanic belt. The occurrence of an extensive, often artesian, carbonatic reservoir hosting moderately hot groundwater might boost the temperature gradient in the overlying impermeable cover, and consequently mask the deep thermal regime. We therefore revised the available dataset and investigated the contribution of advection. Temperature data available from water and oil wells were reprocessed and analysed in combination with thermal conductivity measurements on a wide set of lithotypes. Data were filtered according to rigid selection criteria, and, in the deeper boreholes, the heat flow was inferred by taking into account the porosity variation with depth and the temperature effect on the matrix and pore-filling fluid conductivity. Moreover, the possible effect of advection was evaluated with simple analytical models which envisage the carbonatic layers as confined aquifers heated by the

  8. Metal cooldown, flow instability, and heat transfer in two-phase hydrogen flow

    NASA Technical Reports Server (NTRS)

    Manson, L.; Miller, W. S.

    1970-01-01

    Studies of the properties of five metals with varying tube-wall thickness, with or without and internal coating of trifluorochloroethylene polymer, show that wall characteristics influence flow stability, affect heat transfer coefficients, and influence the transition point from dry- to wet-wall flow.

  9. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields.

  10. Convection flows driven by laser heating of a liquid layer

    NASA Astrophysics Data System (ADS)

    Rivière, David; Selva, Bertrand; Chraibi, Hamza; Delabre, Ulysse; Delville, Jean-Pierre

    2016-02-01

    When a fluid is heated by the absorption of a continuous laser wave, the fluid density decreases in the heated area. This induces a pressure gradient that generates internal motion of the fluid. Due to mass conservation, convection eddies emerge in the sample. To investigate these laser-driven bulk flows at the microscopic scale, we built a setup to perform temperature measurements with a fluorescent-sensitive dye on the one hand, and measured the flow pattern at different beam powers, using a particle image velocimetry technique on the other hand. Temperature measurements were also used in numerical simulations in order to compare predictions to the experimental velocity profiles. The combination of our numerical and experimental approaches allows a detailed description of the convection flows induced by the absorption of light, which reveals a transition between a thin and a thick liquid layer regime. This supports the basis of optothermal approaches for microfluidic applications.

  11. Combination solar photovoltaic heat engine energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  12. Fluid flow and heat transfer in an air-to-water double-pipe heat exchanger

    NASA Astrophysics Data System (ADS)

    Sheikholeslami, M.; Gorji-Bandpy, M.; Ganji, D. D.

    2015-11-01

    This paper reports experimental and numerical investigations on flow and heat transfer in an air-to-water double-pipe heat exchanger. The working fluids are air and water. To achieve fully developed conditions, the heat exchanger was built with additional lengths before and after the test section. The inner and outer tube was made from copper and Plexiglas, respectively. The experiments are conducted in the range of air flow Reynolds number for various cases with different water flow rate and water inlet temperature. Correlations for the Nusselt number and friction factor are presented according to experimental data. Also the commercial code ANSYS 15 is used for numerical simulation. Results show that the Nusselt number is an increasing function of Reynolds number and Prandtl number which are calculated at bulk temperature.

  13. Plasma Heating and Flow in an Auroral Arc

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Chandler, M. O.; Pollock, C. J.; Reasoner, D. L.; Arnoldy, R. L.; Austin, B.; Kintner, P. M.; Bonnell, J.

    1996-01-01

    We report direct observations of the three-dimensional velocity distribution of selected topside ionospheric ion species in an auroral context between 500 and 550 km altitude. We find heating transverse to the local magnetic field in the core plasma, with significant heating of 0(+), He(+), and H(+), as well as tail heating events that occur independently of the core heating. The 0(+) velocity distribution departs from bi-Maxwellian, at one point exhibiting an apparent ring-like shape. However, these observations are shown to be aliased within the auroral arc by temporal variations that arc not well-resolved by the core plasma instrument. The dc electric field measurements reveal superthermal plasma drifts that are consistent with passage of the payload through a series of vortex structures or a larger scale circularly polarized hydromagnetic wave structure within the auroral arc. The dc electric field also shows that impulsive solitary structures, with a frequency spectrum in the ion cyclotron frequency range, occur in close correlation with the tail heating events. The drift and core heating observations lend support to the idea that core ion heating is driven at low altitudes by rapid convective motions imposed by the magnetosphere. Plasma wave emissions at ion frequencies and parallel heating of the low-energy electron plasma are observed in conjunction with this auroral form; however, the conditions are much more complex than those typically invoked in previous theoretical treatments of superthermal frictional heating. The observed ion heating within the arc clearly exceeds that expected from frictional heating for the light ion species H(+) and He(+), and the core distributions also contain hot transverse tails, indicating an anomalous transverse heat source.

  14. Io: Volcanic thermal sources and global heat flow

    NASA Astrophysics Data System (ADS)

    Veeder, Glenn J.; Davies, Ashley Gerard; Matson, Dennis L.; Johnson, Torrence V.; Williams, David A.; Radebaugh, Jani

    2012-06-01

    We have examined thermal emission from 240 active or recently-active volcanic features on Io and quantified the magnitude and distribution of their volcanic heat flow during the Galileo epoch. We use spacecraft data and a geological map of Io to derive an estimate of the maximum possible contribution from small dark areas not detected as thermally active but which nevertheless appear to be sites of recent volcanic activity. We utilize a trend analysis to extrapolate from the smallest detectable volcanic heat sources to these smallest mapped dark areas. Including the additional heat from estimates for "outburst" eruptions and for a multitude of very small ("myriad") hot spots, we account for ˜62 × 1012 W (˜59 ± 7% of Io's total thermal emission). Loki Patera contributes, on average, 9.6 × 1012 W (˜9.1 ± 1%). All dark paterae contribute 45.3 × 1012 W (˜43 ± 5%). Although dark flow fields cover a much larger area than dark paterae, they contribute only 5.6 × 1012 W (˜5.3 ± 0.6%). Bright paterae contribute ˜2.6 × 1012 W (˜2.5 ± 0.3%). Outburst eruption phases and very small hot spots contribute no more than ˜4% of Io's total thermal emission: this is probably a maximum value. About 50% of Io's volcanic heat flow emanates from only 1.2% of Io's surface. Of Io's heat flow, 41 ± 7.0% remains unaccounted for in terms of identified sources. Globally, volcanic heat flow is not uniformly distributed. Power output per unit surface area is slightly biased towards mid-latitudes, although there is a stronger bias toward the northern hemisphere when Loki Patera is included. There is a slight favoring of the northern hemisphere for outbursts where locations were well constrained. Globally, we find peaks in thermal emission at ˜315°W and ˜105°W (using 30° bins). There is a minimum in thermal emission at around 200°W (almost at the anti-jovian longitude) which is a significant regional difference. These peaks and troughs suggest a shift to the east from

  15. An engineering aerodynamic heating method for hypersonic flow

    NASA Technical Reports Server (NTRS)

    Riley, Christopher J.; Dejarnette, Fred R.

    1992-01-01

    A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

  16. An Engineering Aerodynamic Heating Method for Hypersonic Flow

    NASA Technical Reports Server (NTRS)

    Riley, Christopher J.; DeJarnette, Fred R.

    1992-01-01

    A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

  17. Hiemenz flow and heat transfer of a third grade fluid

    NASA Astrophysics Data System (ADS)

    Sahoo, Bikash

    2009-03-01

    The laminar flow and heat transfer of an incompressible, third grade, electrically conducting fluid impinging normal to a plane in the presence of a uniform magnetic field is investigated. The heat transfer analysis has been carried out for two heating processes, namely, (i) with prescribed surface temperature (PST-case) and (ii) prescribed surface heat flux (PHF-case). By means of the similarity transformation, the governing non-linear partial differential equations are reduced to a system of non-linear ordinary differential equations and are solved by a second-order numerical technique. Effects of various non-Newtonian fluid parameters, magnetic parameter, Prandtl number on the velocity and temperature fields have been investigated in detail and shown graphically. It is found that the velocity gradient at the wall decreases as the third grade fluid parameter increases.

  18. Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1993

    SciTech Connect

    Dr. Ronald D. Boyd

    2000-07-01

    Subcooled flow boiling in heated coolant channels is an important heat transfer enhancement technique in the development of fusion reactor components, where high heat fluxes must be accommodated. As energy fluxes increase in magnitude, additional emphasis must be devoted to enhancing techniques such as sub cooling and enhanced surfaces. In addition to subcooling, other high heat flux alternatives such as high velocity helium and liquid metal cooling have been considered as serious contenders. Each technique has its advantages and disadvantages [1], which must be weighed as to reliability and reduced cost of fusion reactor components. Previous studies [2] have set the stage for the present work, which will concentrate on fundamental thermal hydraulic issues associated with the h-international Thermonuclear Experimental Reactor (ITER) and the Engineering Design Activity (EDA). This proposed work is intended to increase our understanding of high heat flux removal alternatives as well as our present capabilities by: (1) including single-side heating effects in models for local predictions of heat transfer and critical heat flux; (2) inspection of the US, Japanese, and other possible data sources for single-side heating, with the aim of exploring possible correlations for both CHF and local heat transfer; and (3) assessing the viability of various high heat flux removal techniques. The latter task includes: (a) sub-cooled water flow boiling with enhancements such as twisted tapes, and hypervapotrons, (b) high velocity helium cooling, and (c) other potential techniques such as liquid metal cooling. This assessment will increase our understanding of: (1) hypervapotron heat transfer via fins, flow recirculation, and flow oscillation, and (2) swirl flow. This progress report contains selective examples of ongoing work. Section II contains an extended abstract, which is part of and evolving technical paper on single-side f heating. Section III describes additional details

  19. Two-phase Flow Ejector as Water Refrigerant by Using Waste Heat

    NASA Astrophysics Data System (ADS)

    Yamanaka, H.; Nakagawa, M.

    2013-04-01

    Energy saving and the use of clean energy sources have recently become significant issues. It is expected that clean energy sources such as solar panels and fuel cells will be installed in many private dwellings. However, when electrical power is generated, exhaust heat is simultaneously produced. Especially for the summer season, the development of refrigeration systems that can use this waste heat is highly desirable. One approach is an ejector that can reduce the mechanical compression work required in a normal refrigeration cycle. We focus on the use of water as a refrigerant, since this can be safely implemented in private dwellings. Although the energy conversion efficiency is low, it is promising because it can use heat that would otherwise be discarded. However, a steam ejector refrigeration cycle requires a large amount of energy to change saturated water into vapour. Thus, we propose a more efficient two-phase flow ejector cycle. Experiments were carried out in which the quality of the two-phase flow from a tank was varied, and the efficiency of the ejector and nozzle was determined. The results show that a vacuum state can be achieved and suction exerted with a two-phase flow state at the ejector nozzle inlet.

  20. Piezoelectric Energy Harvesting in Internal Fluid Flow

    PubMed Central

    Lee, Hyeong Jae; Sherrit, Stewart; Tosi, Luis Phillipe; Walkemeyer, Phillip; Colonius, Tim

    2015-01-01

    We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two designs were considered for the electromechanical coupling: first; the cantilever itself is a piezoelectric bimorph; second; the cantilever is mounted on a pair of flextensional actuators. We experimentally investigated varying the geometry of the flow passage and the flow rate. Experimental results revealed that the power generated from both designs was similar; producing as much as 20 mW at a flow rate of 20 L/min. The bimorph designs were prone to failure at the extremes of flow rates tested. Finite element analysis (FEA) showed fatigue failure was imminent due to stress concentrations near the bimorph’s clamped region; and that robustness could be improved with a stepped-joint mounting design. A similar FEA model showed the flextensional-based harvester had a resonant frequency of around 375 Hz and an electromechanical coupling of 0.23 between the cantilever and flextensional actuators in a vacuum. These values; along with the power levels demonstrated; are significant steps toward building a system design that can eventually deliver power in the Watts range to devices down within a well. PMID:26473879

  1. Heat transfer and pressure drop of supercritical carbon dioxide flowing in several printed circuit heat exchanger channel patterns

    SciTech Connect

    Carlson, M.; Kruizenga, A.; Anderson, M.; Corradini, M.

    2012-07-01

    Closed-loop Brayton cycles using supercritical carbon dioxide (SCO{sub 2}) show potential for use in high-temperature power generation applications including High Temperature Gas Reactors (HTGR) and Sodium-Cooled Fast Reactors (SFR). Compared to Rankine cycles SCO{sub 2} Brayton cycles offer similar or improved efficiency and the potential for decreased capital costs due to a reduction in equipment size and complexity. Compact printed-circuit heat exchangers (PCHE) are being considered as part of several SCO{sub 2} Brayton designs to further reduce equipment size with increased energy density. Several designs plan to use a gas cooler operating near the pseudo-critical point of carbon dioxide to benefit from large variations in thermophysical properties, but further work is needed to validate correlations for heat transfer and pressure-drop characteristics of SCO{sub 2} flows in candidate PCHE channel designs for a variety of operating conditions. This paper presents work on experimental measurements of the heat transfer and pressure drop behavior of miniature channels using carbon dioxide at supercritical pressure. Results from several plate geometries tested in horizontal cooling-mode flow are presented, including a straight semi-circular channel, zigzag channel with a bend angle of 80 degrees, and a channel with a staggered array of extruded airfoil pillars modeled after a NACA 0020 airfoil with an 8.1 mm chord length facing into the flow. Heat transfer coefficients and bulk temperatures are calculated from measured local wall temperatures and local heat fluxes. The experimental results are compared to several methods for estimating the friction factor and Nusselt number of cooling-mode flows at supercritical pressures in millimeter-scale channels. (authors)

  2. Energy-Storage Modules for Active Solar Heating and Cooling

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1982-01-01

    34 page report describes a melting salt hydrate that stores 12 times as much heat as rocks and other heavy materials. Energy is stored mostly as latent heat; that is, heat that can be stored and recovered without any significant change in temperature. Report also describes development, evaluation and testing of permanently sealed modules containing salt hydrate mixture.

  3. United States Department of Energy Thermally Activated Heat Pump Program

    SciTech Connect

    Fiskum, R.J.; Adcock, P.W.; DeVault, R.C.

    1996-06-01

    The US Department of Energy (DOE) is working with partners from the gas heating and cooling industry to improve energy efficiency using advance absorption technologies, to eliminate chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), to reduce global warming through more efficient combustion of natural gas, and to impact electric peak demand of air conditioning. To assist industry in developing these gas heating and cooling absorption technologies, the US DOE sponsors the Thermally Activated Heat Pump Program. It is divided into five key activities, addressing residential gas absorption heat pumps, large commercial chillers, advanced absorption fluids, computer-aided design, and advanced ``Hi-Cool`` heat pumps.

  4. Observing and modeling Earths energy flows

    SciTech Connect

    Stevens B.; Schwartz S.

    2012-05-11

    This article reviews, from the authors perspective, progress in observing and modeling energy flows in Earth's climate system. Emphasis is placed on the state of understanding of Earth's energy flows and their susceptibility to perturbations, with particular emphasis on the roles of clouds and aerosols. More accurate measurements of the total solar irradiance and the rate of change of ocean enthalpy help constrain individual components of the energy budget at the top of the atmosphere to within {+-}2 W m{sup -2}. The measurements demonstrate that Earth reflects substantially less solar radiation and emits more terrestrial radiation than was believed even a decade ago. Active remote sensing is helping to constrain the surface energy budget, but new estimates of downwelling surface irradiance that benefit from such methods are proving difficult to reconcile with existing precipitation climatologies. Overall, the energy budget at the surface is much more uncertain than at the top of the atmosphere. A decade of high-precision measurements of the energy budget at the top of the atmosphere is providing new opportunities to track Earth's energy flows on timescales ranging from days to years, and at very high spatial resolution. The measurements show that the principal limitation in the estimate of secular trends now lies in the natural variability of the Earth system itself. The forcing-feedback-response framework, which has developed to understand how changes in Earth's energy flows affect surface temperature, is reviewed in light of recent work that shows fast responses (adjustments) of the system are central to the definition of the effective forcing that results from a change in atmospheric composition. In many cases, the adjustment, rather than the characterization of the compositional perturbation (associated, for instance, with changing greenhouse gas concentrations, or aerosol burdens), limits accurate determination of the radiative forcing. Changes in clouds

  5. Observing and Modeling Earth's Energy Flows

    NASA Astrophysics Data System (ADS)

    Stevens, Bjorn; Schwartz, Stephen E.

    2012-07-01

    This article reviews, from the authors' perspective, progress in observing and modeling energy flows in Earth's climate system. Emphasis is placed on the state of understanding of Earth's energy flows and their susceptibility to perturbations, with particular emphasis on the roles of clouds and aerosols. More accurate measurements of the total solar irradiance and the rate of change of ocean enthalpy help constrain individual components of the energy budget at the top of the atmosphere to within ±2 W m-2. The measurements demonstrate that Earth reflects substantially less solar radiation and emits more terrestrial radiation than was believed even a decade ago. Active remote sensing is helping to constrain the surface energy budget, but new estimates of downwelling surface irradiance that benefit from such methods are proving difficult to reconcile with existing precipitation climatologies. Overall, the energy budget at the surface is much more uncertain than at the top of the atmosphere. A decade of high-precision measurements of the energy budget at the top of the atmosphere is providing new opportunities to track Earth's energy flows on timescales ranging from days to years, and at very high spatial resolution. The measurements show that the principal limitation in the estimate of secular trends now lies in the natural variability of the Earth system itself. The forcing-feedback-response framework, which has developed to understand how changes in Earth's energy flows affect surface temperature, is reviewed in light of recent work that shows fast responses (adjustments) of the system are central to the definition of the effective forcing that results from a change in atmospheric composition. In many cases, the adjustment, rather than the characterization of the compositional perturbation (associated, for instance, with changing greenhouse gas concentrations, or aerosol burdens), limits accurate determination of the radiative forcing. Changes in clouds contribute

  6. Two-dimensional vapor flow analysis in heat pipes

    SciTech Connect

    Prenger, F.C.; Busse, C.A.

    1984-01-01

    The computer code AGATHE is intended to evaluate axially symmetric heat pipes with compressible vapor flow at Mach numbers up to 1 and at all radial Reynolds numbers. The code can be used to evaluate empirical factors describing turbulence. Furthermore, heat input and output are modeled by describing liquid heat transfer loops. This method leads to nonuniform heating and cooling rates typical of actual heat pipes. Presently the code is adapted to evaluate heat pipes in tubular geometry composed of a series of heat transfer and adiabatic zones of cylindrical or conical shape. In this analysis the two-dimensional mathematical problem was reduced to a number of ordinary differential equations, which are integrated by a Runge-Kutta scheme. The reduction was achieved, first, by starting from the Navier-Stokes equation using the boundary layer approximation; this approximation introduces the main limitation of the code, restricting its use to the calculation of vapor ducts with large length-to-diameter ratios. Second, the velocity profile was simulated by a power series. The n coefficients of this series were determined such that at each axial position the radial pressure gradient was approximately zero, as specified by the boundary layer approximation.

  7. Energy flow and energy dissipation in a free surface.

    NASA Astrophysics Data System (ADS)

    Goldburg, Walter; Cressman, John

    2005-11-01

    Turbulent flows on a free surface are strongly compressible [1] and do not conserve energy in the absence of viscosity as bulk fluids do. Despite violation of assumptions essential to Kolmogorov's theory of 1941 (K41) [2, 3], surface flows show strong agreement with Kolmogorov scaling, though intermittency is larger there. Steady state turbulence is generated in a tank of water, and the spatially averaged energy flux is measured from the four-fifth's law at each instant of time. Likewise, the energy dissipation rate as measured from velocity gradients is also a random variable in this experiment. The energy flux - dissipation rate cross-correlation is measured to be correlated in incompressible bulk flows, but strongly anti-correlated on the surface. We argue that the reason for this discrepancy between surface and bulk flows is due to compressible effects present on the surface. [1] J. R. Cressman, J. Davoudi, W. I. Goldburg, and J. Schumacher, New Journal of Physics, 6, 53, 2004. [2] U. Frisch. Turbulence: The legacy of A. N. Kolmogorov, Cambridge University Press, Cambridge, 1995. [3] A. N. Kolmogorov, Doklady Akad. Nauk SSSR, 32, 16, 1941.

  8. Ion Heating Experiments in a Supersonic Plasma Flow for an Advanced Plasma Thruster

    NASA Astrophysics Data System (ADS)

    Ando, Akira; Hosokawa, Yohei; Hatanaka, Motoi; Yagai, Tsuyoshi; Tobari, Hiroyuki; Hattori, Kunihiko; Inutake, Masaaki

    2003-10-01

    In the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) project in NASA, the combined system of the ion cyclotron heating and the magnetic nozzle is proposed to control a ratio od specific impulse to thrust at constant power. By now, few attempt of a direct ion heating for fast flowing plasma by waves has been done. Ion heating in a fast flowing plasma might be difficult because of the short transit time for ions to pass through a heating region only once and the modification of ion cyclotron resonance due to the effect of Doppler shift. Ion heating experiments are performed in a fast flowing plasma produced by Magneto-Plasma-Dynamic Arcjet (MPDA) operated with an externally-applied magnetic field. RF waves with an ion cyclotron range of frequency is excited by a pair of loop antennas or a helical antenna. An increase of plasma stored energy measured by a diamagnetic loop coil is observed when the waves are excited with various azimuthal mode numbers in several magnetic nozzle configurations. It is most effective to heat ions to excite the waves with an azimuthal mode number of m=±1. Dispersion relations of the propagating wave are obtained and compared with theoretical ones.

  9. Heat flow and continental breakup: The Gulf of Elat (Aqaba)

    NASA Technical Reports Server (NTRS)

    Ben-Avraham, Z.; Vonherzen, R. P.

    1985-01-01

    Heat flow measurements were made in the major basins of the Gulf of Elat (Aqaba), northern Red Sea. The gulf is located at the southern portion of the Dead Sea rift which is a transform plate boundary. Gradient measurements at each site were made with a probe which allows multiple penetration of the bottom during a single deployment of the instrument. Thermal conductivity was determined by needle probe measurements on sedimentary cores. The mean heat flux, about 80 mWm(-2), is significantly above the continental mean, and probably also above that from the adjacent Sinai and Arabian continental blocks. The heat flow appears to increase from north to south. Such an increase may be related to the more advanced rifting stage of the Red Sea immediately to the south, which presently includes creation of an oceanic crust. This trend also corresponds to the general trend of the deep crustal structure in the gulf. Evidence from various geophysical fields suggest a gradual thinning of the crust towards the direction of the Red Sea where a normal oceanic crust exists. The heat flow data, together with other geophysical data, indicate a propagation of mature rifting activity from the Red Sea into the Gulf of Elat. This process is acting simultaneously with the transform motion along the Dead Sea rift.

  10. A high performance cocurrent-flow heat pipe for heat recovery applications

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.; Hartl, J. C.

    1980-01-01

    By the introduction of a plate-and-tube separator assembly into a heat pipe vapor core, it has been demonstrated that axial transport capacity in reflux mode can be improved by up to a factor of 10. This improvement is largely the result of eliminating the countercurrent shear that commonly limits reflux heat pipe axial capacity. With benzene, axial heat fluxes up to 1800 W/sq cm were obtained in the temperature range 40 to 80 C, while heat flux densities up to 3000 W/sq cm were obtained with R-11 over the temperature range 40 to 80 C. These very high axial capacities compare favorably with liquid metal limits; the sonic limit for liquid sodium, for example, is 3000 W/sq cm at 657 C. Computational models developed for these cocurrent flow heat pipes agreed with experimental data within + or - 25%.

  11. Heat Transfer Over the Circumference of a Heated Cylinder in Transverse Flow

    NASA Technical Reports Server (NTRS)

    Schmidt, Ernst; Wenner, Karl

    1943-01-01

    A method for recording the local heat-transfer coefficients on bodies in flow was developed. The cylinder surface was kept at constant temperature by the condensation of vapor except for a narrow strip which is heated separately to the same temperature by electricity. The heat-transfer coefficient at each point was determined from the electric heat output and the temperature increase. The distribution of the heat transfer along the circumference of cylinders was recorded over a range of Reynolds numbers of from 5000 to 426,000. The pressure distribution was measured at the same time. At Reynolds numbers up to around 100,000 high maximums of the heat transfer occurred in the forward stagnation point at and on the rear side at 180C, while at around 80 the heat-transfer coefficient on both sides of the cylinder behind the forward stagnation point manifested distinct minimums. Two other maximums occurred at around 115 C behind the forward stagnation point between 170,000 and 426,000. At 426,000 the heat transfer at the location of those maximums was almost twice as great as in the forward stagnation point, and the rear half of the cylinder diffused about 60 percent of the entire heat, The tests are compared with the results of other experimental and theoretical investigations.

  12. Use of solar energy to produce process heat for industry

    NASA Astrophysics Data System (ADS)

    Brown, K.

    1980-04-01

    The role of solar energy in supplying heat and hot water to residential and commerical buildings is familiar. On the other hand, the role that solar energy may play in displacing imported energy supplies in the industrial and utility sectors often goes unrecognized. The versatility of solar technology lends itself well to applications in industry; particulary to the supplemental supply for process heat. The status of solar thermal technology for industrial process heat applications, including a description of current costs and operating histories is surveyed. The most important objectives to be met in improving system performance, reducing cost, and identifying markets for solar industrial process heat are outlined.

  13. Gravity-driven flow over heated, porous, wavy surfaces

    NASA Astrophysics Data System (ADS)

    Ogden, K. A.; D'Alessio, S. J. D.; Pascal, J. P.

    2011-12-01

    The method of weighted residuals for thin film flow down an inclined plane is extended to include the effects of bottom waviness, heating, and permeability in this study. A bottom slip condition is used to account for permeability and a constant temperature bottom boundary condition is applied. A weighted residual model (WRM) is derived and used to predict the combined effects of bottom waviness, heating, and permeability on the stability of the flow. In the absence of bottom topography, the results are compared to theoretical predictions from the corresponding Benney equation and also to existing Orr-Sommerfeld predictions. The excellent agreement found indicates that the model does faithfully predict the theoretical critical Reynolds number, which accounts for heating and permeability, and these effects are found to destabilize the flow. Floquet theory is used to investigate how bottom waviness influences the stability of the flow. Finally, numerical simulations of the model equations are also conducted and compared with numerical solutions of the full Navier-Stokes equations for the case with bottom permeability. These results are also found to agree well, which suggests that the WRM remains valid even when permeability is included.

  14. Predicting Turbulent Convective Heat Transfer in Fully Developed Duct Flows

    NASA Technical Reports Server (NTRS)

    Rokni, Masoud; Gatski, Thomas B.

    2001-01-01

    The performance of an explicit algebraic stress model (EASM) is assessed in predicting the turbulent flow and forced heat transfer in both straight and wavy ducts, with rectangular, trapezoidal and triangular cross-sections, under fully developed conditions. A comparison of secondary flow patterns. including velocity vectors and velocity and temperature contours, are shown in order to study the effect of waviness on flow dynamics, and comparisons between the hydraulic parameters. Fanning friction factor and Nusselt number, are also presented. In all cases. isothermal conditions are imposed on the duct walls, and the turbulent heat fluxes are modeled using gradient-diffusion type models. The formulation is valid for Reynolds numbers up to 10(exp 5) and this minimizes the need for wall functions that have been used with mixed success in previous studies of complex duct flows. In addition, the present formulation imposes minimal demand on the number of grid points without any convergence or stability problems. Criteria in terms of heat transfer and friction factor needed to choose the optimal wavy duct cross-section for industrial applications among the ones considered are discussed.

  15. Local heat transfer for subcooled flow boiling with water

    SciTech Connect

    Boyd, R.D.; Meng, X. )

    1992-12-01

    In this paper, local heat transfer coefficients are predicted for turbulent water subcooled flow boiling through uniformly heated circular tubes. Correlations by Petukhov and by Shah are modified slightly. however, the correlation suggested by Kandlikar is improved significantly by requiring that it approach more accurate limits near the onset of fully developed boiling and the onset of nucleate boiling for subcooled flow. Excellent agreement is obtained with data corresponding to conditions of high inlet subcooling (183[degrees]C), high mass velocity (4.4 to 31.5 Mg/m[sup 2][center dot]s), and a large ratio of the axial coordinate to the diameter (95.5). The exit subcooling varies from 53.0 to 81.5[degrees]C. For smaller ratios ([lt]50.0), the accuracy decreases. In all cases, the local film temperature is the characteristic temperature. When the associated critical heat flux (CHF) data are examined in a Stanton number-Peclet number space, St [lt] 0.0065 and Pe [gt] 10[sup 5] in all cases. Comparisons with the Saha-Zuber criterion for bubble detachment show that moderately subcooled and high-velocity flows re characterized by a multiboundary layer phenomenon that includes an attached bubble layer. These results show that the bubble layer's existence can now be documented for a wide variety of fluids and conditions without flow visualizations.

  16. Energy resource requirements of a solar heating system

    NASA Astrophysics Data System (ADS)

    Rogers, D. W. O.

    1980-01-01

    The paper addresses the question of the total energy resource use of a solar hot water and space heating system compared to the traditional oil, gas and electric heating options. The methods of energy analysis have been applied to a liquid-based, short-term storage solar space and water heating system for a dwelling in Toronto, and the results indicate that the indirect use of energy resources does not have a major impact on the overall energy conservation characteristics of the system which, being in many respects a worst case, takes 1.0-3.5 years of operation to conserve the energy resources, required to build, operate and maintain the system. Over the assumed 20-year lifetime the solar heating system, sized to provide 50% of the heating requirement to a house, uses between 53 and 62% as many energy resources as a conventional system, heating the same house. The energy-conservation characteristics of the system can be completely negated by the use of thermally generated electricity as backup in a 50% solar heating system which replaces oil or gas heating. The collectors and annual operating energy for the pumps were found to be the two most significant factors in the analysis.

  17. Measuring Heat Flow on the Moon and Mars- The Heat Flow and Physical Properties Package HP-cubed

    NASA Astrophysics Data System (ADS)

    Spohn, T.; Grott, M.; Ho, T.; van Zoest, T.; Kargl, G.; Smrekar, S. E.; Hudson, T. L.

    2010-12-01

    With only two successful heat flow measurements performed on the surface of the Moon to date, the thermal state of the Moon remains poorly constrained. Furthermore, measurements were taken close to the boundary of the Procellarum KREEP terraine, and the obtained values may not be representative for the bulk of the planet. For Mars, no heat flow measurement is yet available. Here we will present the Heat Flow and Physical Properties Package HP-cubed a self-penetrating, robotic heat flow probe. The instrument consists of electrical and temperature sensors that will be emplaced into the lunar subsurface by means of an electro-mechanical hammering mechanism. The instruement is foreseen to penetrate 3-5 m into the planet’s soil and will perform depth resolved measurements, from which the surface planetary heat flow can be directly deduced. The instrument has been pre-developed in two ESA funded precursor studies and has been further developed in the framework of ESA’s ExoMars mission. The current readiness level of the instrument is TRL 5.62 (ESA PDR Apr. 2009) which has been achieved with several Breadboards developed and tested between 2004 and 2009. As no drilling is required to achieve soil penetration, HP-cubed is a relatively lightweight heat flow probe, weighting less than 1800 g. It has been further studied as parts of the discovery proposals Lunette and GEMS and for the proposed Japanese lunar mission SELENE 2 The instrument consists of an electro-mechanic mole, a pay-load compartment, and a tether equipped with temperature sensors. The latter can be actively heated for thermal conductivity measurements. A tiltmeter and acceleraometer will help to track the path of the mole. The payload compartment has room for sensors such as a permittivity probe, a bore-hole camera, and/or a masspectrometer. Following deployment of the instrument, instrument operations will be split into two phases: During the penetration phase soil intrusion is achieved by means of the

  18. A New Model for Heat Flow in Extensional Basins: Estimating Radiogenic Heat Production

    SciTech Connect

    Waples, Douglas W.

    2002-06-15

    Radiogenic heat production (RHP) represents a significant fraction of surface heat flow, both on cratons and in sedimentary basins. RHP within continental crust-especially the upper crust-is high. RHP at any depth within the crust can be estimated as a function of crustal age. Mantle RHP, in contrast, is always low, contributing at most 1 to 2 mW/m{sup 2} to total heat flow. Radiogenic heat from any noncrystalline basement that may be present also contributes to total heat flow. RHP from metamorphic rocks is similar to or slightly lower than that from their precursor sedimentary rocks. When extension of the lithosphere occurs-as for example during rifting-the radiogenic contribution of each layer of the lithosphere and noncrystalline basement diminishes in direct proportion to the degree of extension of that layer. Lithospheric RHP today is somewhat less than in the distant past, as a result of radioactive decay. In modeling, RHP can be varied through time by considering the half lives of uranium, thorium, and potassium, and the proportional contribution of each of those elements to total RHP from basement. RHP from sedimentary rocks ranges from low for most evaporites to high for some shales, especially those rich in organic matter. The contribution to total heat flow of radiogenic heat from sediments depends strongly on total sediment thickness, and thus differs through time as subsidence and basin filling occur. RHP can be high for thick clastic sections. RHP in sediments can be calculated using ordinary or spectral gamma-ray logs, or it can be estimated from the lithology.

  19. Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels

    NASA Astrophysics Data System (ADS)

    Mikielewicz, Dariusz; Andrzejczyk, Rafał; Jakubowska, Blanka; Mikielewicz, Jarosław

    2014-09-01

    In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.

  20. An approximate substitution principle for viscous heat conducting flows

    NASA Astrophysics Data System (ADS)

    Greitzer, E. M.; Paterson, R. W.; Tan, C. S.

    1985-09-01

    A new, approximate substitution principle is presented for a class of steady flows in which both heat transfer and momentum interchange by viscous stresses are significant. The principle, which has important implications for the design and scaling of mixing experiments, can be regarded as an extension of the Munk and Prim substitution principle (for steady isentropic flows) to nonisentropic flows (Munk and Prim, 1947). The concepts that are developed explain the scaling and distribution of various fluid dynamic properties observed in several different types of flow mixing experiments. Calculations are done to indicate the expected regimes of applicability of the approximate principle and comparison with experiment is made to show its utility in practical situations.

  1. Bubbly flow velocity measurements near a heated cylindrical conductor

    SciTech Connect

    Canaan, R.E.; Hassan, Y.A. )

    1990-01-01

    The objective of this study is to apply recent advances and improvements in the digital pulsed laser velocimetry (DPLV) technique to the analysis of two-phase bubbly flow about a cylindrical conductor emitting a constant heat flux within a transparent rectangular enclosure. Pulsed laser velocimetry is a rapidly advancing fluid flow visualization technique that determines full-field instantaneous velocity vectors of a quantitative nature such that the flow field remains undisturbed by the measurement. The DPLV method offers several significant advantages over more traditional fluid velocity measurement techniques such as hot wire/film anemometry and laser Doppler anemometry because reliable instantaneous velocity data may be acquired over substantial flow areas in a single experiment.

  2. LavaSIM: the effect of heat transfer in 3D on lava flow characteristics (Invited)

    NASA Astrophysics Data System (ADS)

    Fujita, E.

    2013-12-01

    Characteristics of lava flow are governed by many parameters like lava viscosity, effusion rate, ground topography, etc. The accuracy and applicability of lava flow simulation code is evaluated whether the numerical simulation can reproduce these features quantitatively, which is important from both strategic and scientific points of views. Many lava flow simulation codes are so far proposed, and they are classified into two categories, i.e., the deterministic and the probabilistic models. LavaSIM is one of the former category models, and has a disadvantage of time consuming. But LavaSIM can solves the equations of continuity, motion, energy by step and has an advantage in the calculation of three-dimensional analysis with solid-liquid two phase flow, including the heat transfer between lava, solidified crust, air, water and ground, and three-dimensional convection in liquid lava. In other word, we can check the detailed structure of lava flow by LavaSIM. Therefore, this code can produce both channeled and fan-dispersive flows. The margin of the flow is solidified by cooling and these solidified crusts control the behavior of successive lava flow. In case of a channel flow, the solidified margin supports the stable central main flow and elongates the lava flow distance. The cross section of lava flow shows that the liquid lava flows between solidified crusts. As for the lava extrusion flow rate, LavaSIM can include the time function as well as the location of the vents. In some cases, some parts of the solidified wall may be broken by the pressure of successive flow and/or re-melting. These mechanisms could characterize complex features of the observed lava flows at many volcanoes in the world. To apply LavaSIM to the benchmark tests organized by V-hub is important to improve the lava flow evaluation technique.

  3. Thermal energy storage heat exchanger: Molten salt heat exchanger design for utility power plants

    NASA Technical Reports Server (NTRS)

    Ferarra, A.; Yenetchi, G.; Haslett, R.; Kosson, R.

    1977-01-01

    Sizing procedures are presented for latent heat thermal energy storage systems that can be used for electric utility off-peak energy storage, solar power plants and other preliminary design applications.

  4. Unsteady Flow of Radiating and Chemically Reacting MHD Micropolar Fluid in Slip-Flow Regime with Heat Generation

    NASA Astrophysics Data System (ADS)

    Abo-Dahab, S. M.; Mohamed, R. A.

    2013-11-01

    An analytical study of the problem of unsteady free convection with thermal radiation and heat generation on MHD micropolar fluid flow through a porous medium bounded by a semi-infinite vertical plate in a slip-flow regime has been presented. The Rosseland diffusion approximation is used to describe the radiation heat flux in the energy equation. The homogeneous chemical reaction of first order is accounted for in the mass diffusion equation. A uniform magnetic field acts perpendicular on the porous surface absorbing micropolar fluid with a suction velocity varying with time. A perturbation technique is applied to obtain the expressions for the velocity, microrotation, temperature, and concentration distributions. Expressions for the skin-friction, Nusselt number, and Sherwood number are also obtained. The results are discussed graphically for different values of the parameters entered into the equations of the problem.

  5. Heat Transfer Characteristics of Slush Nitrogen in Turbulent Pipe Flows

    NASA Astrophysics Data System (ADS)

    Ohira, K.; Ishimoto, J.; Nozawa, M.; Kura, T.; Takahashi, N.

    2008-03-01

    Slush fluids, such as slush hydrogen and slush nitrogen, are two-phase (solid-liquid) single-component cryogenic fluids containing solid particles in a liquid, and consequently their density and refrigerant capacity are greater than for liquid state fluid alone. This paper reports on the experimental results of the forced convection heat transfer characteristics of slush nitrogen flowing in a pipe. Heat was supplied to slush nitrogen by a heater wound around the copper pipe wall. The local heat transfer coefficient was measured in conjunction with changes in the velocity and the solid fraction. The differences in heat transfer characteristics between two-phase slush and single phase liquid nitrogen were obtained, and the decrease in heat transfer to slush nitrogen caused by the previously observed pressure drop reduction was confirmed by this study. Furthermore, for the purpose of establishing the thermal design criteria for slush nitrogen in the case of pressure drop reduction, the heat transfer correlation between the experimental results and the Sieder-Tate Equation was obtained.

  6. Water flow energy harvesters for autonomous flowmeters

    NASA Astrophysics Data System (ADS)

    Boisseau, Sebastien; Duret, Alexandre-Benoit; Perez, Matthias; Jallas, Emmanuel; Jallas, Eric

    2016-11-01

    This paper reports on a water flow energy harvester exploiting a horizontal axis turbine with distributed magnets of alternate polarities at the rotor periphery and air coils outside the pipe. The energy harvester operates down to 1.2L/min with an inlet section of 20mm of diameter and up to 25.2mW are provided at 20L/min in a 2.4V NiMH battery through a BQ25504 power management circuit. The pressure loss induced by the insertion of the energy harvester in the hydraulic circuit and by the extraction of energy has been limited to 0.05bars at 30L/min, corresponding to a minor loss coefficient of KEH=3.94.

  7. 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

  8. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high-speed flowfields.

  9. Melting of nanoparticle-enhanced phase change material inside an enclosure heated by laminar heat transfer fluid flow

    NASA Astrophysics Data System (ADS)

    Elbahjaoui, Radouane; El Qarnia, Hamid; El Ganaoui, Mohammed

    2016-05-01

    The proposed work presents a numerical investigation of the melting of a phase change material (PCM: Paraffin wax P116) dispersed with nanoparticles (Al2O3) in a latent heat storage unit (LHSU). The latter is composed of a number of vertical and identical slabs of nano-enhanced phase change material (NEPCM) separated by rectangular channels through which passes heat transfer fluid (HTF: water). A mathematical model based on the conservation equations of mass, momentum and energy has been developed. The resulting equations are discretized using the finite volume approach. The numerical model has been validated by experimental and numerical results published in literature. Numerical investigations have been conducted to evaluate the effects of the volumetric fraction of nanoparticles, HTF mass flow rate and inlet temperature on the latent heat storage unit's thermal behaviour and performance. Modelling results show that the volumetric fraction, HTF mass flow rate and inlet temperature need to be designed to achieve a significant improvement in thermal performance. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  10. Graphene plasmonic lens for manipulating energy flow

    PubMed Central

    Wang, Guoxi; Liu, Xueming; Lu, Hua; Zeng, Chao

    2014-01-01

    Manipulating the energy flow of light is at the heart of modern information and communication technologies. Because photons are uncharged, it is still difficult to effectively control them by electrical means. Here, we propose a graphene plasmonic (GP) lens to efficiently manipulate energy flow by elaborately designing the thickness of the dielectric spacer beneath the graphene sheet. Different from traditional metal-based lenses, the proposed graphene plasmonic lens possesses the advantages of tunability and excellent confinement of surface plasmons. It is found that the proposed lens can be utilized to focus and collimate the GP waves propagating along the graphene sheet. Particularly, the lens is dispersionless over a wide frequency range and the performance of lens can be flexibly tuned by adjusting the bias voltage. As an application of such a lens, the image transfer of two point sources with a separation of λ0/30 is demonstrated. PMID:24517981

  11. Energy Flow Analysis of Coupled Beams

    NASA Astrophysics Data System (ADS)

    Cho, P. E.; Bernhard, R. J.

    1998-04-01

    Energy flow analysis (EFA) is an analytical tool for prediction of the frequency-averaged vibrational response of built-up structures at high audible frequencies. The procedure is based on two developments; first, the derivation of the partial differential equations that govern the propagation of energy-related quantities in simple structural elements such as rods, beams, plates, and acoustic cavities; and second, the derivation of coupling relationships in terms of energy-related quantities that describe the transfer of energy for various joints (e.g., beam-to-beam, rod-to-beam, plate-to-plate, structure-to-acoustic field coupling). In this investigation, the energy flow coupling relationships at these joints for rods and beams are derived. EFA is used to predict the frequency-averaged vibrational response of a frame structure with a three-dimensional joint, where four wave types propagate in the structure. The predicted results of EFA are shown to be a good approximation of the frequency-averaged “exact” energetics, which are computed from classical displacement solutions.

  12. Heat flow and heat generation estimates for the Churchill basement of the Western Canadian Basin in Alberta, Canada

    SciTech Connect

    Beach, R.D.W.; Jones, F.W.; Majorowicz, J.A.

    1987-01-01

    Heat flow through the sediments and temperatures of the Churchill province basement under the sedimentary cover are determined for 24 locations in the central part of the Prairies basin in Alberta where the vertical heat flux is approximately constant from the base of the sediments to the surface. The contribution to heat flow from heat generation in the sediments is also considered. The average heat flow through the sediments is found to be 71 mWm/sup -2/ +- 12mWm/sup -2/ which is about 30 mWm/sup -2/ higher than in the neighbouring shield area of the Churchill province, and the contribution from heat generation in the sediments to the surface heat flow is only approximately 2.5 mWm/sup -2/. The relationship between basement heat generation and heat flow is investigated, and it is found that the platform heat flow/heat generation values are in general higher than those from the Churchill province of the shield found by Drury (1985). Although for the platform and shield data, the reduced heat flow is about 40 mWm/sup -2/ and the slope is about 8km, it is apparent that the platform data alone are not good enough to establish a precise relationship.

  13. Heat Pump Water Heating Modeling in EnergyPlus

    SciTech Connect

    Wilson, Eric; Christensen, Craig

    2012-03-01

    This presentation summarizes NREL's development of a HPWH model for use in hourly building energy simulation programs, such as BEopt; this presentation was given at the Building America Stakeholder meeting on March 1, 2012, in Austin, Texas.

  14. Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator

    NASA Astrophysics Data System (ADS)

    Muszyński, Tomasz; Kozieł, Sławomir Marcin

    2016-09-01

    Two-dimensional numerical investigations of the fluid flow and heat transfer have been carried out for the laminar flow of the louvered fin-plate heat exchanger, designed to work as an air-source heat pump evaporator. The transferred heat and the pressure drop predicted by simulation have been compared with the corresponding experimental data taken from the literature. Two dimensional analyses of the louvered fins with varying geometry have been conducted. Simulations have been performed for different geometries with varying louver pitch, louver angle and different louver blade number. Constant inlet air temperature and varying velocity ranging from 2 to 8 m/s was assumed in the numerical experiments. The air-side performance is evaluated by calculating the temperature and the pressure drop ratio. Efficiency curves are obtained that can be used to select optimum louver geometry for the selected inlet parameters. A total of 363 different cases of various fin geometry for 7 different air velocities were investigated. The maximum heat transfer improvement interpreted in terms of the maximum efficiency has been obtained for the louver angle of 16 ° and the louver pitch of 1.35 mm. The presented results indicate that varying louver geometry might be a convenient way of enhancing performance of heat exchangers.

  15. Study on Absorption Heat Pump Using Untapped Energy Resource

    NASA Astrophysics Data System (ADS)

    Okamoto, Hiroaki; Hihara, Eiji; Bando, Shigeru; Oka, Masahiro; Ichikawa, Toru; Kojima, Hiroshi

    The spread of absorption heat pump is considered an effective strategy to reduce the emission of greenhouse gases andthe heat island impact. However, its large volume and low efficiency as compare to vapor-compression system haverestricted its application area. In order to develop a compact and high-efficiency absorption heat pump, we propose a newtype of system which adopting triple effect cycle at cooling, while double effect at heating. In addition, unused energy,such as sewage water, is used in this system to improve the COP furthermore. System performances were evaluated by discussing the COP, highest pressure, highest temperature, strongest solutionconcentration, and energy consumption at part-load operation. By using sewage water as heat source, COP increaseswhile the highest pressure, highest temperature and strongest solution concentration decrease. From a standpointofperformance at heating and energy consumption, it is found that the proposed system works well and more effective thanthe existing system.

  16. Energy and Exergy Analysis of an Annular Thermoelectric Heat Pump

    NASA Astrophysics Data System (ADS)

    Kaushik, S. C.; Manikandan, S.; Hans, Ranjana

    2016-07-01

    In this paper, the concept of an annular thermoelectric heat pump (ATEHP) has been introduced. An exoreversible thermodynamic model of the ATEHP considering the Thomson effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for dimensionless heating power, optimum current at the maximum energy, exergy efficiency conditions and dimensionless irreversibilities in the ATEHP are derived. The results show that the heating power, energy and exergy efficiency of the ATEHP are lower than the flat-plate thermoelectric heat pump. The effects of annular shape parameter ( S r = r 2 /r 1), dimensionless temperature ratio ( θ = T h /T c) and the electrical contact resistances on the heating power, energy/exergy efficiency of an ATEHP have been studied. This study will help in the designing of actual ATEHP systems.

  17. 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.

  18. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Lee, Hyeong Jae; Kim, Namhyo; Sun, Kai; Corbett, Gary; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffery L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro

    2014-01-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  19. Flow energy piezoelectric bimorph nozzle harvester

    NASA Astrophysics Data System (ADS)

    Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffrey L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro; Kim, Namhyo; Sun, Kai; Corbett, Gary

    2014-04-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  20. Restoration of the Apollo Heat Flow Experiments Metadata

    NASA Technical Reports Server (NTRS)

    Nagihara, S.; Stephens, M. K.; Taylor, P. T.; Williams, D. R.; Hills, H. K.; Nakamura, Y.

    2015-01-01

    Geothermal heat flow probes were deployed on the Apollo 15 and 17 missions as part of the Apollo Lunar Surface Experiments Package (ALSEP). At each landing site, the astronauts drilled 2 holes, 10-m apart, and installed a probe in each. The holes were 1- and 1.5-m deep at the Apollo 15 site and 2.5-m deep at the Apollo 17 sites. The probes monitored surface temperature and subsurface temperatures at different depths. At the Apollo 15 site, the monitoring continued from July 1971 to January 1977. At the Apollo 17 site, it did from December 1972 to September 1977. Based on the observations made through December 1974, Marcus Langseth, the principal investigator of the heat flow experiments (HFE), determined the thermal conductivity of the lunar regolith by mathematically modeling how the seasonal temperature fluctuation propagated down through the regolith. He also determined the temperature unaffected by diurnal and seasonal thermal waves of the regolith at different depths, which yielded the geothermal gradient. By multiplying the thermal gradient and the thermal conductivity, Langseth obtained the endogenic heat flow of the Moon as 21 mW/m(exp 2) at Site 15 and 16 mW/m(exp 2) at Site 17.

  1. Heat exchange at laminar flow in rectangular channels

    NASA Astrophysics Data System (ADS)

    Valueva, E. P.; Purdin, M. S.

    2016-11-01

    Numerical modeling of heat exchange at a laminar stationary and pulsatile flow in rectangular channels with different aspect ratios of side lengths γ has been carried out by a finite difference method for two boundary conditions: a constant wall temperature and a constant heat flux density on the wall. For the boundary condition of the first kind, the similarity of distributions of the heat flux density and shear stress on the walls over the channel perimeter has been established. The reasons for a nonmonotonous dependence of the initial thermal interval length on γ are discussed. For the boundary condition of the second kind, the difference of the Nusselt number averaged over the perimeter at γ → 0 from its value for a flow in a flat channel has been explained. An increase in the Nusselt number averaged over the perimeter and the period of oscillations has been revealed for a pulsatile flow in the quasi-stationary regime at large amplitudes of the oscillations of the velocity averaged over the cross section.

  2. Attachment-Line Heating in a Compressible Flow

    NASA Astrophysics Data System (ADS)

    Reed, Helen; Saric, William

    2011-11-01

    The attachment-line boundary layer on a swept wing can be subject to either an instability or contamination by wing-root turbulence. A model of the attachment-line boundary layer is first developed including compressibility and wall heating in a Falkner-Skan-Cooke class of 3-D boundary layers with Hartree parameter of 1.0. For cases otherwise subcritical to either contamination or instability, the destabilizing effect of leading-edge heating under a variety of sweep angles and flight conditions is demonstrated. The results correlate with the attachment-line Reynolds number. Because the required heating levels are reasonable and achievable to trip the flow over the wing to turbulent, one possible application of this work is in the establishing of a baseline turbulent flow (on demand) for the calibration of a laminar-flow-control health monitoring system. *Portion based on work under Framework Agreement between Airbus Americas and NIA, and opinions, findings, conclusions do not necessarily reflect views of Airbus or NIA. Support from AFOSR/NASA National Center for Hypersonic Research in Laminar-Turbulent Transition through Grant FA9550-09-1-0341 gratefully acknowledged.

  3. Nonclassical Symmetry Analysis of Heated Two-Dimensional Flow Problems

    NASA Astrophysics Data System (ADS)

    Naeem, Imran; Naz, Rehana; Khan, Muhammad Danish

    2015-12-01

    This article analyses the nonclassical symmetries and group invariant solution of boundary layer equations for two-dimensional heated flows. First, we derive the nonclassical symmetry determining equations with the aid of the computer package SADE. We solve these equations directly to obtain nonclassical symmetries. We follow standard procedure of computing nonclassical symmetries and consider two different scenarios, ξ1≠0 and ξ1=0, ξ2≠0. Several nonclassical symmetries are reported for both scenarios. Furthermore, numerous group invariant solutions for nonclassical symmetries are derived. The similarity variables associated with each nonclassical symmetry are computed. The similarity variables reduce the system of partial differential equations (PDEs) to a system of ordinary differential equations (ODEs) in terms of similarity variables. The reduced system of ODEs are solved to obtain group invariant solution for governing boundary layer equations for two-dimensional heated flow problems. We successfully formulate a physical problem of heat transfer analysis for fluid flow over a linearly stretching porous plat and, with suitable boundary conditions, we solve this problem.

  4. Finite Element Modelling of the Apollo Heat Flow Experiments

    NASA Astrophysics Data System (ADS)

    Platt, J.; Siegler, M. A.; Williams, J.

    2013-12-01

    The heat flow experiments sent on Apollo missions 15 and 17 were designed to measure the temperature gradient of the lunar regolith in order to determine the heat flux of the moon. Major problems in these experiments arose from the fact that the astronauts were not able to insert the probes below the thermal skin depth. Compounding the problem, anomalies in the data have prevented scientists from conclusively determining the temperature dependent conductivity of the soil, which enters as a linear function into the heat flow calculation, thus stymieing them in their primary goal of constraining the global heat production of the Moon. Different methods of determining the thermal conductivity have yielded vastly different results resulting in downward corrections of up to 50% in some cases from the original calculations. Along with problems determining the conductivity, the data was inconsistent with theoretical predictions of the temperature variation over time, leading some to suspect that the Apollo experiment itself changed the thermal properties of the localised area surrounding the probe. The average temperature of the regolith, according to the data, increased over time, a phenomenon that makes calculating the thermal conductivity of the soil and heat flux impossible without knowing the source of error and accounting for it. The changes, possibly resulting from as varied sources as the imprint of the Astronauts boots on the lunar surface, compacted soil around the bore stem of the probe or even heat radiating down the inside of the tube, have convinced many people that the recorded data is unusable. In order to shed some light on the possible causes of this temperature rise, we implemented a finite element model of the probe using the program COMSOL Multi-physics as well as Matlab. Once the cause of the temperature rise is known then steps can be taken to account for the failings of the experiment and increase the data's utility.

  5. Fundamental flow and heat transfer results relevant to oscillating flow regenerators

    SciTech Connect

    Hutchinson, R.A.; Ross, B.A.

    1987-08-01

    Complete understanding of the operation of Stirling and other heat engine regenerators has evaded engineers working on engine development because making measurements in or near such a regenerator is so difficult. Some illumination of the physics that may be involved, however, can be found by studying fundamental experimental results in the literature, results that were examined for other applications in addition to Stirling. Preliminary reviews of literature on the subjects of oscillating flows, periodic flows and porous media have brought to light interesting papers presenting a number of phenomena that may be of importance in heat engine regenerators. Some are also relevant to flows in other Stirling heat exchangers. These topics include heat transfer during compression and expansion, enhanced conduction in oscillating laminar flows, approaches to analysis of nonuniform porous media, and heat transfer enhancement mechanisms in porous media. Each topic is briefly described and discussed in this paper, and a summary of physical phenomena that may affect regenerator performance is presented. 27 refs., 3 figs., 1 tab.

  6. Energy flow analysis of coupled structures

    NASA Astrophysics Data System (ADS)

    Cho, Phillip Eung-Ho

    1993-01-01

    Energy flow analysis (EFA) is an analytical tool for prediction of the frequency-averaged vibrational response of built-up structures at high audible frequencies. The procedure is based on two developments; firstly, the derivation of the partial differential equations that govern the propagation of energy-related quantities in simple structural elements such as rods, beams, plates, and acoustic cavities; secondly, the derivation of coupling relationships in terms of energy-related quantities that describe the transfer of energy for various joints (e.g., beam-to-beam, plate-to-plate, and structure-to acoustic field couplings). In this investigation, EFA is used to predict the vibrational response of various coupled structures. In the process of predicting the vibrational response of the coupled structures, the energy flow coupling relationships at the joints of these structures are derived. In addition, the finite element formulation of the governing energy equations are developed. Because the energy density is discontinuous at the joint, a special global assembly procedure is developed to assemble the finite element matrix equations into global matrix equations. The global matrix assembly procedure is predicated on the development of joint element matrix equations using energy flow coupling relationships for various structural joints. The results predicted by EFA for a frame structure with a three-dimensional joint, where four wave types propagate in the structure, are shown to be a reasonable approximation of the frequency-averaged 'exact' energetics, which are computed from classical displacement solutions. The accuracy of the results predicted by EFA increased with high mode count and modal overlap factor or high non-dimensional wavenumber band and non-dimensional damped wavenumber band in the frequency band of interest. An experimental investigation of vibrational response of a light truck frame structure was performed to verify the results of EFA when applied

  7. 76 FR 71835 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-18

    ... viewing pane) or a sealed system, they do not provide the same heating function as gas fireplaces, gas... Conservation Standards for Direct Heating Equipment; Final Rule #0;#0;Federal Register / Vol. 76 , No. 223...-AC56 Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment...

  8. Testing of SLA-561V in NASA-Ames' Turbulent Flow Duct with Augmented Radiative Heating

    NASA Technical Reports Server (NTRS)

    Sepka, Steven A.; Kornienko, Robert S.; Radbourne, Chris A.

    2010-01-01

    As part of Mars Science Laboratory s (MSL) heatshield development program, SLA-561 was tested in NASA Ames Turbulent Flow Duct (TFD) Facility. For these tests, the TFD facility was modified to include a ceramic plate located in the wall opposite to the test model. Normally the TFD wall opposite to the test model is water-cooled steel. Installing a noncooled ceramic plate allows the ceramic to absorb convective heating and radiate the energy back to the test model as the plate heats up. This work was an effort to increase the severity of TFD test conditions. Presented here are the results from these tests.

  9. Flow and heat transfer for gas flowing in microchannels: a review

    NASA Astrophysics Data System (ADS)

    Rostami, A. A.; Mujumdar, A. S.; Saniei, N.

    Microchannels are currently being used in many areas and have high potential for applications in many other areas, which are considered realistic by experts. The application areas include medicine, biotechnology, avionics, consumer electronics, telecommunications, metrology, computer technology, office equipment and home appliances, safety technology, process engineering, robotics, automotive engineering and environmental protection. A number of these applications are introduced in this paper, followed by a critical review of the works on the flow and heat transfer for gas flowing in microchannels. The results show that the flow and heat transfer characteristics of a gas flowing in microchannels can not be adequately predicted by the theories and correlations developed for conventional sized channels. The results of theoretical and experimental works are discussed and summarized along with suggestions for future research directions.

  10. Strong ocean tidal flow and heating on moons of the outer planets.

    PubMed

    Tyler, Robert H

    2008-12-11

    Data from recent space missions have added strong support for the idea that there are liquid oceans on several moons of the outer planets, with Jupiter's moon Europa having received the most attention. But given the extremely cold surface temperatures and meagre radiogenic heat sources of these moons, it is still unclear how these oceans remain liquid. The prevailing conjecture is that these oceans are heated by tidal forces that flex the solid moon (rock plus ice) during its eccentric orbit, and that this heat entering the ocean does not rapidly escape because of the insulating layer of ice over the ocean surface. Here, however, I describe strong tidal dissipation (and heating) in the liquid oceans; I show that a subdominant and previously unconsidered tidal force due to obliquity (axial tilt of the moon with respect to its orbital plane) has the right form and frequency to resonantly excite large-amplitude Rossby waves in these oceans. In the specific case of Europa, the minimum kinetic energy of the flow associated with this resonance (7.3 x 10(18) J) is two thousand times larger than that of the flow excited by the dominant tidal forces, and dissipation of this energy seems large enough to be a primary ocean heat source.

  11. Geothermal Well and Heat Flow Data for the United States (Southern Methodist University (SMU) Geothermal Laboratory)

    DOE Data Explorer

    Blackwell, D.D. and others

    Southern Methodist University makes two databases and several detailed maps available. The Regional Heat Flow Database for the United States contains information on primarily regional or background wells that determine the heat flow for the United States; temperature gradients and conductivity are used to generate heat flow measurements. Information on geology of the location, porosity, thermal conductivity, water table depth, etc. are also included when known. There are usually three data files for each state or region. The first files were generated in 1989 for the data base creating the Decade of North America Geology (DNAG) Geothermal Map. The second set is from 1996 when the data base was officially updated for the Department of Energy. The third set is from 1999 when the Western U.S. High Temperature Geothermal data base was completed. As new data is received, the files continue to be updated. The second major resource is the Western Geothermal Areas Database, a database of over 5000 wells in primarily high temperature geothermal areas from the Rockies to the Pacific Ocean. The majority of the data are from company documents, well logs, and publications with drilling dates ranging from 1960 to 2000. Many of the wells were not previously accessible to the public. Users will need to register, but will then have free, open access to the databases. The contents of each database can be viewed and downloaded as Excel spreadsheets. See also the heat flow maps at http://www.smu.edu/geothermal/heatflow/heatflow.htm

  12. Study of flow control by localized volume heating in hypersonic boundary layers

    NASA Astrophysics Data System (ADS)

    Keller, M. A.; Kloker, M. J.; Kirilovskiy, S. V.; Polivanov, P. A.; Sidorenko, A. A.; Maslov, A. A.

    2014-12-01

    Boundary-layer flow control is a prerequisite for a safe and efficient operation of future hypersonic transport systems. Here, the influence of an electric discharge—modeled by a heat-source term in the energy equation—on laminar boundary-layer flows over a flat plate with zero pressure gradient at Mach 3, 5, and 7 is investigated numerically. The aim was to appraise the potential of electro-gasdynamic devices for an application as turbulence generators in the super- and hypersonic flow regime. The results with localized heat-source elements in boundary layers are compared to cases with roughness elements serving as classical passive trips. The numerical simulations are performed using the commercial code ANSYS FLUENT (by ITAM) and the high-order finite-difference DNS code NS3D (by IAG), the latter allowing for the detailed analysis of laminar flow instability. For the investigated setups with steady heating, transition to turbulence is not observed, due to the Reynolds-number lowering effect of heating.

  13. Effect of the load size on the efficiency of microwave heating under stop flow and continuous flow conditions.

    PubMed

    Patil, Narendra G; Rebrov, Evgeny V; Eränen, Kari; Benaskar, Faysal; Meuldijk, Jan; Mikkola, Jyri-Pekka; Hessel, Volker; Hulshof, Lumbertus A; Murzin, Dmitry Yu; Schouten, Jaap C

    2012-01-01

    A novel heating efficiency analysis of the microwave heated stop-flow (i.e. stagnant liquid) and continuous-flow reactors has been presented. The thermal losses to the surrounding air by natural convection have been taken into account for heating efficiency calculation of the microwave heating process. The effect of the load diameter in the range of 4-29 mm on the heating efficiency of ethylene glycol was studied in a single mode microwave cavity under continuous flow and stop-flow conditions. The variation of the microwave absorbing properties of the load with temperature was estimated. Under stop-flow conditions, the heating efficiency depends on the load diameter. The highest heating efficiency has been observed at the load diameter close to the half wavelength of the electromagnetic field in the corresponding medium. Under continuous-flow conditions, the heating efficiency increased linearly. However, microwave leakage above the propagation diameter restricted further experimentation at higher load diameters. Contrary to the stop-flow conditions, the load temperature did not raise monotonously from the inlet to outlet under continuous-flow conditions. This was due to the combined effect of lagging convective heat fluxes in comparison to volumetric heating. This severely disturbs the uniformity of the electromagnetic field in the axial direction and creates areas of high and low field intensity along the load Length decreasing the heating efficiency as compared to stop-flow conditions.

  14. Experimental and Numerical Analysis of Air Flow, Heat Transfer and Thermal Comfort in Buildings with Different Heating Systems

    NASA Astrophysics Data System (ADS)

    Sabanskis, A.; Virbulis, J.

    2016-04-01

    Monitoring of temperature, humidity and air flow velocity is performed in 5 experimental buildings with the inner size of 3×3×3 m3 located in Riga, Latvia. The buildings are equipped with different heating systems, such as an air-air heat pump, air-water heat pump, capillary heating mat on the ceiling and electric heater. Numerical simulation of air flow and heat transfer by convection, conduction and radiation is carried out using OpenFOAM software and compared with experimental data. Results are analysed regarding the temperature and air flow distribution as well as thermal comfort.

  15. SUPERSONIC AND HYPERSONIC INTERFERENCE FLOW FIELDS AND HEATING

    NASA Technical Reports Server (NTRS)

    Morris, D. J.

    1994-01-01

    Small areas of high heat transfer and pressure can occur on a vehicle surface due to the influence of an impinging shock on the local flow. A method was needed to determine peak pressure and heating of these areas. This package is a system of computer programs designed to calculate two-dimensional shock interference patterns for six types of interference flows. Results also include properties of the inviscid flow field and the inviscid-viscous interaction at the surface along with peak pressure and peak heating at the impingement point. The six types of interference flow patterns considered are: 1) Type I interference patterns, occurring when two weak shocks of opposite families, BS (bow shock) and IS (impingment shock), intersect when the flow upstream of the impingement point is supersonic, or in the case of a blunt body, takes place well below the sonic point. 2) Type II interference pattern occurs when two shocks of opposite families (bow shock and impinging shock) intersect. Both shocks are weak as in type I, but are of such strength that in order to turn the flow, a Mach reflection must exist in the center of the flow field with an embedded subsonic region occurring between the intersection points (A & B) and the accompanying shear layers. Type II interference occurs on a blunt body when the impinging shock intersects the bow shock near the sonic point. 3) Type III shock interference pattern occurs when a weak impinging shock intersects a strong detached bow shock. On a blunt body the shock intersection occurs near or above the lower sonic point. 4) Type IV interference can occur when the impinging shock intersects a strong bow shock ahead of a subsonic flow region. On a blunt body this shock intersection is located between the lower sonic point and just above the body axis. The impinging shock causes a displacement of the bow shock and the formation of a supersonic jet that is embedded in the subsonic region. A jet bow shock is produced when the jet impinges

  16. Flow and heat transfer of ferrofluids over a flat plate with uniform heat flux

    NASA Astrophysics Data System (ADS)

    Khan, W. A.; Khan, Z. H.; Haq, R. U.

    2015-04-01

    The present work is dedicated to analyze the flow and heat transport of ferrofluids along a flat plate subjected to uniform heat flux and slip velocity. A magnetic field is applied in the transverse direction to the plate. Moreover, three different kinds of magnetic nanoparticles (Fe3O4, CoFe2O4, Mn-ZnFe2O4 are incorporated within the base fluid. We have considered two different kinds of base fluids (kerosene and water) having poor thermal conductivity as compared to solid magnetic nanoparticles. Self-similar solutions are obtained and are compared with the available data for special cases. A simulation is performed for each ferrofluid mixture by considering the dominant effects of slip and uniform heat flux. It is found that the present results are in an excellent agreement with the existing literature. The variation of skin friction and heat transfer is also performed at the surface of the plate and then the better heat transfer and of each mixture is analyzed. Kerosene-based magnetite Fe3O4 provides the higher heat transfer rate at the wall as compared to the kerosene-based cobalt ferrite and Mn-Zn ferrite. It is also concluded that the primary effect of the magnetic field is to accelerate the dimensionless velocity and to reduce the dimensionless surface temperature as compared to the hydrodynamic case, thereby increasing the skin friction and the heat transfer rate of ferrofluids.

  17. Heat transfer analysis of two-phase dispersed swirl flow

    SciTech Connect

    Chang Ching.

    1991-01-01

    A thermodynamic nonequilibrium model was developed for a two-phase, vapor and liquid droplet, dispersed swirl flow in a vertical tube with a twisted-tape insert. It takes account of the heat transfer phenomena between two phases, and each phase with solid boundary where a variable heat flux along axial direction is imposed. A numerical method is developed to solve the system of nonlinear differential equations. The local equilibrium conditions of the fluid at the point of critical heat flux (CHF) are chosen as the initial conditions to start the numerical integration to the downstream. Wall temperature, superheat vapor temperature, heat transfer rate from two phases, and velocity distributions of two phases were predicted and analyzed, which were then verified by comparing them with the low wall-superheat heat exchanger experimental data of water-steam in the range of 900.0 {le} G {le} 1,900.0, 2.51 {le} y {le} 7.53, X{sub CHF} {ge} 0.444. Additional parametric studies of the CHF quality, mass flux, and tape-twist ratio are presented. It is found that higher mass flux, lower tape-twist ratio, and low wall-superheat will give a stronger direct wall-droplet interaction and less superheating of vapor.

  18. Visualization of heat transfer for impinging swirl flow

    SciTech Connect

    Bakirci, K.; Bilen, K.

    2007-10-15

    The objective of the experimental study was to visualize the temperature distribution and evaluate heat transfer rate on the impingement surface kept at a constant wall temperature boundary condition for the swirling (SIJ), multi-channel (MCIJ) and conventional impinging jet (CIJ) using liquid crystal technique. The swirling jet assembly consisted of a housing tube and a solid swirl generator insert which had four narrow slots machined on its surface. The swirl angle, {theta}, was set as 0 , 22.5 , 41 , 50 to change the direction and strength of the swirl in the air flow exiting the housing tube. The local Nusselt numbers of the MCIJ ({theta} = 0 ) were generally much higher than those of CIJ and SIJs. As the swirl angle increased, the radial uniformity of the heat transfer was seen compared to MCIJ and SIJ; the best results were for {theta} = 50 and the jet-to-surface distance of H/D = 14. The location of the distance of the maximum heat transfer for the swirl angles of {theta} = 41 and 50 was shifted away from the stagnation point in a radial distance of nearly r/D = 2.5. Increasing Reynolds number for same swirler angle increased the heat transfer rate on the entire surface, and increased saddle shape heat transfer distribution on the surface, but had no significant effect on the position of the individual impingement regions, but increased saddle shape heat transfer distribution on the surface. The lower Reynolds number (Re = 10 000) and the highest H/D = 14 gave much more uniform local and average heat transfer distribution on the surface, but decreased their values on the entire surface. (author)

  19. Heat transfer and flow friction correlations for perforated plate matrix heat exchangers

    NASA Astrophysics Data System (ADS)

    Ratna Raju, L.; Kumar, S. Sunil; Chowdhury, K.; Nandi, T. K.

    2017-02-01

    Perforated plate matrix heat exchangers (MHE) are constructed of high conductivity perforated plates stacked alternately with low conductivity spacers. They are being increasingly used in many cryogenic applications including Claude cycle or Reversed Brayton cycle cryo-refrigerators and liquefiers. Design of high NTU (number of (heat) transfer unit) cryogenic MHEs requires accurate heat transfer coefficient and flow friction factor. Thermo-hydraulic behaviour of perforated plates strongly depends on the geometrical parameters. Existing correlations, however, are mostly expressed as functions of Reynolds number only. This causes, for a given configuration, significant variations in coefficients from one correlation to the other. In this paper we present heat transfer and flow friction correlations as functions of all geometrical and other controlling variables. A FluentTM based numerical model has been developed for heat transfer and pressure drop studies over a stack of alternately arranged perforated plates and spacers. The model is validated with the data from literature. Generalized correlations are obtained through regression analysis over a large number of computed data.

  20. Optimal energy growth in swept Hiemenz flow

    NASA Astrophysics Data System (ADS)

    Guegan, Alan; Huerre, Patrick; Schmid, Peter

    2006-11-01

    It has been shown in Gu'egan, Schmid & Huerre 2006 that the kinetic energy of optimal G"ortler-H"ammerlin (GH) perturbations in swept Hiemenz flow can be transiently amplified by two orders of magnitude at Reynolds numbers ranging from 400 to 1000 and spanwise wavenumbers from 0.1 to 0.5. In this configuration an array of counter-rotating chordwise vortices is compressed by the spanwise shear, as in the well-known Orr mechanism. We show that stronger transient growth can be achieved when the GH assumption is relaxed. In this case the optimal initial perturbation consists in vorticity sheets stacked in the chordwise direction, at a small angle from the symmetry plane of the base flow. Although the spatial structure of the GH perturbations is lost, wall-normal-spanwise plane cuts show that the amplification mechanism is mostly unchanged. The GH assumption thus provides a reasonably good estimate for transient energy amplification levels in swept Hiemenz flow. Extension of this analysis to the spatial growth problem is under way and preliminary results will be shown.

  1. Harvesting energy from water flow over graphene?

    PubMed

    Yin, Jun; Zhang, Zhuhua; Li, Xuemei; Zhou, Jianxin; Guo, Wanlin

    2012-03-14

    It is reported excitingly in a previous letter (Nano Lett. 2011, 11, 3123) that a small piece of graphene sheet about 30 × 16 μm(2) immersed in flowing water with 0.6 M hydrochloric acid can produce voltage ~20 mV. Here we find that no measurable voltage can be induced by the flow over mono-, bi- and trilayered graphene samples of ~1 × 1.5 cm(2) in size in the same solution once the electrodes on graphene are isolated from interacting with the solution, mainly because the H(3)O(+) cations in the water adsorb onto graphene by strong covalent bonds as revealed by our first-principles calculations. When both the graphene and its metal electrodes are exposed to the solution as in the previous work, water flow over the graphene-electrode system can induce voltages from a few to over a hundred millivolts. In this situation, the graphene mainly behaves as a load connecting between the electrodes. Therefore, the harvested energy is not from the immersed carbon nanomaterials themselves in ionic water flow but dominated by the exposed electrodes.

  2. Put the Heat on Cutting Energy Costs.

    ERIC Educational Resources Information Center

    Steller, Arthur W.; Pell, Carroll J.

    1985-01-01

    The school board establishes a commitment to efficient energy management through its policies and budget priorities. Such a policy should include a statement of purpose, assign accountability for improving energy efficiency, and ensure that mandated standards are maintained. To permanently prevent energy waste, a gradual change to a comprehensive…

  3. Influence of flow rate and heating power in effective thermal conductivity applied in borehole heat exchangers

    NASA Astrophysics Data System (ADS)

    Śliwa, T.; Sapińska-Śliwa, A.; Wiśniowski, R.; Piechówka, Z.; Krzemień, M.; Pycha, D.; Jaszczur, M.

    2016-09-01

    In borehole heat exchanging systems one of the most important parameters necessary to estimate its efficiency is the effective thermal conductivity. One of the methods for determining it is thermal response test. Such a test may be performed with respect to various parameters. The most important ones include flow rate and heating power. The article summarizes the results of TRT research in Palecznica village, Poland which was performed in boreholes located there in the already operating installation. It presents the established methodology. Also, there is an attempt to determine the relation between the mentioned parameters and the effective thermal conductivity. The research indicates the dependence of the conductivity with the test parameters.

  4. 76 FR 43941 - Energy Conservation Program: Energy Conservation Standards for Direct Heating Equipment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

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

  5. Effect of flow oscillations on axial energy transport in a porous material

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1987-01-01

    The effects of flow oscillations on axial energy diffusion in a porous medium, in which the flow is continuously disrupted by the irregularities of the porous structure, are analyzed. The formulation employs an internal heat transfer coefficient that couples the fluid and solid temperatures. The final relationship shows that the axial energy transport per unit cross-sectional area and time is directly proportional to the axial temperature gradient and the square of the maximum fluid displacement.

  6. Determination of forced convective heat transfer coefficients for subsonic flows over heated asymmetric NANA 4412 airfoil

    NASA Astrophysics Data System (ADS)

    Dag, Yusuf

    Forced convection over traditional surfaces such as flat plate, cylinder and sphere have been well researched and documented. Data on forced convection over airfoil surfaces, however, remain very scanty in literature. High altitude vehicles that employ airfoils as lifting surfaces often suffer leading edge ice accretions which have tremendous negative consequences on the lifting capabilities and stability of the vehicle. One of the ways of mitigating the effect of ice accretion involves judicious leading edge convective cooling technique which in turn depends on the accuracy of convective heat transfer coefficient used in the analysis. In this study empirical investigation of convective heat transfer measurements on asymmetric airfoil is presented at different angle of attacks ranging from 0° to 20° under subsonic flow regime. The top and bottom surface temperatures are measured at given points using Senflex hot film sensors (Tao System Inc.) and used to determine heat transfer characteristics of the airfoils. The model surfaces are subjected to constant heat fluxes using KP Kapton flexible heating pads. The monitored temperature data are then utilized to determine the heat convection coefficients modelled empirically as the Nusselt Number on the surface of the airfoil. The experimental work is conducted in an open circuit-Eiffel type wind tunnel, powered by a 37 kW electrical motor that is able to generate subsonic air velocities up to around 41 m/s in the 24 square-inch test section. The heat transfer experiments have been carried out under constant heat flux supply to the asymmetric airfoil. The convective heat transfer coefficients are determined from measured surface temperature and free stream temperature and investigated in the form of Nusselt number. The variation of Nusselt number is shown with Reynolds number at various angles of attacks. It is concluded that Nusselt number increases with increasing Reynolds number and increase in angle of attack from 0

  7. A Numerical Study of a Double Pipe Latent Heat Thermal Energy Storage System

    NASA Astrophysics Data System (ADS)

    Tabassum, Tonny

    Solar energy is an intermittent supply source of energy. To efficiently utilize this free renewable energy source some form of thermal energy storage devices are necessary. Phase change materials (PCMs), because of their high energy density storage capacity and near isothermal phase change characteristics, have proven to be promising candidates for latent heat thermal energy storage (LHTES) devices. Among the various LHTES devices for low temperature residential heating and cooling applications, the shell-and-tube type heat exchanging devices are the most simple to operate and can be easily fabricated. This work numerically investigates the buoyancy driven heat transfer process during melting (charging) of a commercial paraffin wax as PCM filling the annulus of a horizontal double pipe heat exchanger. The heated working fluid (water) is passing through the central tube of the annulus at a sufficiently high flow-rate and thereby maintaining an almost isothermal wall temperature at the inner pipe which is higher than the melting temperature of the PCM. The transient, two-dimensional coupled laminar momentum and energy equations for the model are suitably non-dimensionalized and are solved numerically using the enthalpy-porosity approach. Time-wise evolutions of the flow patterns and temperature distributions are presented through velocity vector fields and isotherm plots. In this study, two types of PCM filled annuli, a plain annulus and a strategically placed longitudinal finned annulus, are studied. The total energy stored, the total liquid fraction and the energy efficiency at different melting times are evaluated for three different operating conditions and the results are compared between the plain and finned annuli. The present study will provide guidelines for system thermal performance and design optimization of the shell-and-tube LHTES devices. .

  8. Energy flow for electric power system deregulation

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Hung

    Over the past few years, the electric power utility industry in North America and other countries has experienced a strong drive towards deregulation. People have considered the necessity of deregulation of electric utilities for higher energy efficiency and energy saving. The vertically integrated monopolistic industry is being transferred into a horizontally integrated competitive structure in some countries. Wheeling charges are a current high priority problem throughout the power industry, for independent power producers, as well as regulators. Nevertheless the present transmission pricing mechanism fails to be adjusted by a customer loading condition. Customer loading is dynamic, but the present wheeling charge method is fixed, not real-time. A real-time wheeling charge method is developed in this dissertation. This dissertation introduces a concept of a power flow network which can be used for the calculation of power contribution factors in a network. The contribution factor is defined as the ratio of the power contributed by a particular source to a line flow or bus load to the total output of the source. Generation, transmission, and distribution companies can employ contribution factors for the calculation of energy cost, wheeling charges, and loss compensation. Based on the concept of contribution factors, a proposed loss allocation method is developed in this dissertation. Besides, counterflow condition will be given a credit in the proposed loss allocation method. A simple 22-bus example was used for evaluating the contribution factors, proposed wheeling charge method, and loss allocation method.

  9. Heat and mass transfer in turbulent flows with several recirculated flow eddies

    NASA Astrophysics Data System (ADS)

    Baake, E.; Nacke, B.; Jakovics, A.; Umbrashko, A.

    2001-06-01

    Numerical modeling of the concentration and temperature distribution in axial symmetrical systems with several recirculated flow eddies, which is based on various 2D stationary k-ɛ models and commercial codes, e.g. ANSYS and FLUENT, leads to results, which are significantly different from experimental data. Therefore additional user-defined subroutines were included in the commercial program code to improve the turbulent heat and mass transfer in the zone between the recirculated flow eddies. In addition transient 3D calculations were performed to investigate scientifically the flow dynamics. Figs 9, Refs 8.

  10. Computer Modeling VRF Heat Pumps in Commercial Buildings using EnergyPlus

    SciTech Connect

    Raustad, Richard

    2013-07-01

    Variable Refrigerant Flow (VRF) heat pumps are increasingly used in commercial buildings in the United States. Monitored energy use of field installations have shown, in some cases, savings exceeding 30% compared to conventional heating, ventilating, and air-conditioning (HVAC) systems. A simulation study was conducted to identify the installation or operational characteristics that lead to energy savings for VRF systems. The study used the Department of Energy EnergyPlus? building simulation software and four reference building models. Computer simulations were performed in eight U.S. climate zones. The baseline reference HVAC system incorporated packaged single-zone direct-expansion cooling with gas heating (PSZ-AC) or variable-air-volume systems (VAV with reheat). An alternate baseline HVAC system using a heat pump (PSZ-HP) was included for some buildings to directly compare gas and electric heating results. These baseline systems were compared to a VRF heat pump model to identify differences in energy use. VRF systems combine multiple indoor units with one or more outdoor unit(s). These systems move refrigerant between the outdoor and indoor units which eliminates the need for duct work in most cases. Since many applications install duct work in unconditioned spaces, this leads to installation differences between VRF systems and conventional HVAC systems. To characterize installation differences, a duct heat gain model was included to identify the energy impacts of installing ducts in unconditioned spaces. The configuration of variable refrigerant flow heat pumps will ultimately eliminate or significantly reduce energy use due to duct heat transfer. Fan energy is also studied to identify savings associated with non-ducted VRF terminal units. VRF systems incorporate a variable-speed compressor which may lead to operational differences compared to single-speed compression systems. To characterize operational differences, the computer model performance curves used

  11. Pluto's Polygonal Terrain Places Lower Limit on Planetary Heat Flow

    NASA Astrophysics Data System (ADS)

    Trowbridge, A.; Steckloff, J. K.; Melosh, H., IV; Freed, A. M.

    2015-12-01

    During its recent flyby of Pluto, New Horizons imaged an icy plains region (Sputnik Planum) whose surface is divided into polygonal blocks, ca. 20-30 km across, bordered by what appear to be shallow troughs. The lack of craters within these plains suggests they are relatively young, implying that the underlying material is recently active. The scale of these features argues against an origin by cooling and contraction. Here we investigate the alternative scenario that they are the surface manifestation of shallow convection in a thick layer of nitrogen ice. Typical Rayleigh-Bernard convective cells are approximately three times wider than the depth of the convecting layer, implying a layer depth of ca. 7-10 km. Our convection hypothesis requires that the Rayleigh number exceed a minimum of about 1000 in the nitrogen ice layer. We coupled a parameterized convection model with a temperature dependent rheology of nitrogen ice (Yamashita, 2008), finding a Rayleigh number 1500 to 7500 times critical for a plausible range of heat flows for Pluto's interior. The computed range of heat flow (3.5-5.2 mW/m2) is consistent with the radiogenic heat generated by a carbonaceous chondrite (CC) core implied by Pluto's bulk density. The minimum heat flow at the critical Rayleigh number is 0.13 mW/m2. Our model implies a core temperature of 44 K in the interior of the convecting layer. This is very close to the exothermic β-α phase transition in nitrogen ice at 35.6 K (for pure N2 ice; dissolved CO can increase this, depending on its concentration), suggesting that the warm cores of the rising convective cells may be β phase, whereas the cooler sinking limbs may be α phase. This transition may thus be observable due to the large difference in their spectral signature. Further applying our model to Pluto's putative water ice mantle, the heat flow from CC is consistent with convection in Pluto's mantle and the activity observed on its surface.

  12. Efficient Solar-Thermal Energy Harvest Driven by Interfacial Plasmonic Heating-Assisted Evaporation.

    PubMed

    Chang, Chao; Yang, Chao; Liu, Yanming; Tao, Peng; Song, Chengyi; Shang, Wen; Wu, Jianbo; Deng, Tao

    2016-09-07

    The plasmonic heating effect of noble nanoparticles has recently received tremendous attention for various important applications. Herein, we report the utilization of interfacial plasmonic heating-assisted evaporation for efficient and facile solar-thermal energy harvest. An airlaid paper-supported gold nanoparticle thin film was placed at the thermal energy conversion region within a sealed chamber to convert solar energy into thermal energy. The generated thermal energy instantly vaporizes the water underneath into hot vapors that quickly diffuse to the thermal energy release region of the chamber to condense into liquids and release the collected thermal energy. The condensed water automatically flows back to the thermal energy conversion region under the capillary force from the hydrophilic copper mesh. Such an approach simultaneously realizes efficient solar-to-thermal energy conversion and rapid transportation of converted thermal energy to target application terminals. Compared to conventional external photothermal conversion design, the solar-thermal harvesting device driven by the internal plasmonic heating effect has reduced the overall thermal resistance by more than 50% and has demonstrated more than 25% improvement of solar water heating efficiency.

  13. Improved simulations of heat transfer in liquid metal flows.

    SciTech Connect

    Tzanos, C.

    2011-04-01

    In liquid-metal flows, the predictions of the Nusselt number (heat transfer) by Reynolds-averaged Navier-Stokes models of turbulence that use the assumption of a constant turbulent Prandtl number can be significantly off. Heat transfer analyses were performed with a number of turbulence models for flows in a triangular rod bundle and in a pipe, and model predictions were compared with experimental data. Emphasis was placed on the low Reynolds (low-Re) number k-{var_epsilon} model that resolves the boundary layer and does not use 'logarithmic wall functions.' The high Reynolds (high-Re) number k-{var_epsilon} model underpredicts the Nusselt number up to 30%, while the low-Re number model overpredicts it up to 34%. For high Peclet number values, the low-Re number model provides better predictions than the high-Re number model. For Peclet numbers higher than 1500, the predictions of the Reynolds stress model (RSM) are in very good agreement with experimental measurements, but for lower Peclet number values its predictions are significantly off. A relationship was developed that expresses the turbulent Prandtl number as a function of the ratio of the turbulent viscosity to the molecular viscosity. With this modified turbulent Prandtl number, for the flow in the rod bundle the predictions of the low-Re number model are well within the spread of the experimental measurements. For pipe flow, the model predictions are not as sensitive to the correction of the turbulent Prandtl number as they are in the case of the flow in a bundle. The modified low-Re number model underpredicts the limited experimental data by 4%.

  14. World Energy Projection System Plus Model Documentation: District Heat Model

    EIA Publications

    2017-01-01

    This report documents the objectives, analytical approach and development of the World Energy Projection System Plus (WEPS ) District Heat Model. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  15. Simulation of Reynolds number influence on heat exchange in turbulent flow of medium slurry

    NASA Astrophysics Data System (ADS)

    Bartosik, A.

    2016-10-01

    The paper deals with the numerical simulation of mass and heat exchange in turbulent flow of solid-liquid mixture in the range of averaged solid particle diameter from 0.10mm to 0.80mm, named further as the medium slurry. Physical model assumes that dispersed phase is fully suspended and a turbulent flow is hydro-dynamically, and thermally developed in a straight horizontal pipeline. Taking into account the aforementioned assumptions the slurry is treated as a single-phase flow with increased density, while viscosity is equals to a carrier liquid viscosity. The mathematical model constitutes time averaged momentum equation in which the turbulent stress tensor was designated using a two-equation turbulence model, which makes use of the Boussinesq eddy-viscosity hypothesis. Turbulence damping function in the turbulence model was especially designed for the medium slurry. In addition, an energy equation has been used in which a convective term was determined from the energy balance acting on a unit pipe length, assuming linear changes of temperature in main flow direction. Finally, the mathematical model of non-isothermal medium slurry flow comprises four partial differential equations, namely momentum and energy equations, equations of kinetic energy of turbulence and its dissipation rate. Four partial differential equations were solved by a finite difference scheme using own computer code. The objective of the paper is to examine the influence of Reynolds number on temperature profiles and Nusselt number in turbulent flow of medium slurry in the range of solids concentration from 0% to 30% by volume. The effect of influential factors on heat transfer between the pipe and slurry is analysed. The paper demonstrates substantial impact of Reynolds number and solids volume fraction on the Nusselt number. The results of numerical simulation are reviewed.

  16. [Energy flow in arctic aquatic ecosystems

    SciTech Connect

    Schell, D.M.

    1985-01-01

    This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

  17. [Energy flow in arctic aquatic ecosystems

    SciTech Connect

    Schell, D.M.

    1985-12-31

    This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

  18. High heat flux engineering in solar energy applications

    SciTech Connect

    Cameron, C.P.

    1993-07-01

    Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m{sup 2}. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.

  19. Solar energy and heat pumps: Can this marriage be saved

    NASA Astrophysics Data System (ADS)

    Andrews, J. W.

    Work on systems for building space and water heating and space cooling which combine vapor compression heat pumps with the use of solar energy led to promising system configurations which portend reasonable cost and beneficial impact on utility load profiles in addition to conserving energy. A historical perspective on this work are presented. The ranges of system possibilities are elucidated and two promising systems are described.

  20. Heat pipe solar receiver with thermal energy storage

    NASA Technical Reports Server (NTRS)

    Zimmerman, W. F.

    1981-01-01

    An HPSR Stirling engine generator system featuring latent heat thermal energy storge, excellent thermal stability and self regulating, effective thermal transport at low system delta T is described. The system was supported by component technology testing of heat pipes and of thermal storage and energy transport models which define the expected performance of the system. Preliminary and detailed design efforts were completed and manufacturing of HPSR components has begun.

  1. System for thermal energy storage, space heating and cooling and power conversion

    DOEpatents

    Gruen, Dieter M.; Fields, Paul R.

    1981-04-21

    An integrated system for storing thermal energy, for space heating and cong and for power conversion is described which utilizes the reversible thermal decomposition characteristics of two hydrides having different decomposition pressures at the same temperature for energy storage and space conditioning and the expansion of high-pressure hydrogen for power conversion. The system consists of a plurality of reaction vessels, at least one containing each of the different hydrides, three loops of circulating heat transfer fluid which can be selectively coupled to the vessels for supplying the heat of decomposition from any appropriate source of thermal energy from the outside ambient environment or from the spaces to be cooled and for removing the heat of reaction to the outside ambient environment or to the spaces to be heated, and a hydrogen loop for directing the flow of hydrogen gas between the vessels. When used for power conversion, at least two vessels contain the same hydride and the hydrogen loop contains an expansion engine. The system is particularly suitable for the utilization of thermal energy supplied by solar collectors and concentrators, but may be used with any source of heat, including a source of low-grade heat.

  2. Large deviations of heat flow in harmonic chains

    NASA Astrophysics Data System (ADS)

    Kundu, Anupam; Sabhapandit, Sanjib; Dhar, Abhishek

    2011-03-01

    We consider heat transport across a harmonic chain connected at its two ends to white-noise Langevin reservoirs at different temperatures. In the steady state of this system the heat Q flowing from one reservoir into the system in a finite time τ has a distribution P(Q, τ). We study the large time form of the corresponding moment generating function lange - λQrang ~ g(λ)eτμ(λ). Exact formal expressions, in terms of phonon Green's functions, are obtained for both μ(λ) and also the lowest order correction g(λ). We point out that, in general, a knowledge of both μ(λ) and g(λ) is required for finding the large deviation function associated with P(Q, τ). The function μ(λ) is known to be the largest eigenvector of an appropriate Fokker-Planck type operator and our method also gives the corresponding eigenvector exactly.

  3. Local swirl chamber heat transfer and flow structure at different Reynolds numbers

    SciTech Connect

    Hedlung, C.R.; Ligrani, P.M.

    2000-04-01

    Local flow behavior and heat transfer results are presented from two swirl chambers, which model passages used to cool the leading edges of turbine blades in gas turbine engines. Flow results are obtained in an isothermal swirl chamber. Surface Nusselt number distributions are measured in a second swirl chamber (with a constant wall heat flux boundary condition) using infrared thermography in conjunction with thermocouples, energy balances, and in situ calibration procedures. In both cases, Reynolds numbers Re based on inlet duct characteristics range from 6,000 to about 20,000. Bulk helical flow is produced in each chamber by two inlets, which are tangent to the swirl chamber circumference. Important changes to local and globally averaged surface Nusselt numbers, instantaneous flow structure from flow visualizations, and distributions of static pressure, total pressure, and circumferential velocity are observed throughout the swirl chambers as the Reynolds number increases. Of particular importance are increases of local surface Nusselt numbers (as well as ones globally averaged over the entire swirl chamber surface) with increasing Reynolds number. These are tied to increased advection, as well as important changes to vortex characteristics near the concave surfaces of the swirl chambers. Higher Re also give larger axial components of velocity, and increased turning of the flow from each inlet, which gives Goertler vortex pair trajectories greater skewness as they are advected downstream of each inlet.

  4. Cryogenic two-phase flow during chilldown: Flow transition and nucleate boiling heat transfer

    NASA Astrophysics Data System (ADS)

    Jackson, Jelliffe Kevin

    The recent interest in space exploration has placed a renewed focus on rocket propulsion technology. Cryogenic propellants are the preferred fuel for rocket propulsion since they are more energetic and environmentally friendly compared with other storable fuels. Voracious evaporation occurs while transferring these fluids through a pipeline that is initially in thermal equilibrium with the environment. This phenomenon is referred to as line chilldown. Large temperature differences, rapid transients, pressure fluctuations and the transition from the film boiling to the nucleate boiling regime characterize the chilldown process. Although the existence of the chilldown phenomenon has been known for decades, the process is not well understood. Attempts have been made to model the chilldown process; however the results have been fair at best. A major shortcoming of these models is the use of correlations that were developed for steady, non-cryogenic flows. The development of reliable correlations for cryogenic chilldown has been hindered by the lack of experimental data. An experimental facility was constructed that allows the flow structure, the temperature history and the pressure history to be recorded during the line chilldown process. The temperature history is then utilized in conjunction with an inverse heat conduction procedure that was developed, which allows the unsteady heat transfer coefficient on the interior of the pipe wall to be extracted. This database is used to evaluate present predictive models and correlations for flow regime transition and nucleate boiling heat transfer. It is found that by calibrating the transition between the stratified-wavy and the intermittent/annular regimes of the Taitel and Dukler flow regime map, satisfactory predictions are obtained. It is also found that by utilizing a simple model that includes the effect of flow structure and incorporating the enhancement provided by the local heat flux, significant improvement in the

  5. Theoretical investigation on thermal performance of heat pipe flat plate solar collector with cross flow heat exchanger

    NASA Astrophysics Data System (ADS)

    Xiao, Lan; Wu, Shuang-Ying; Zhang, Qiao-Ling; Li, You-Rong

    2012-07-01

    Based on the heat transfer characteristics of absorber plate and the heat transfer effectiveness-number of heat transfer unit method of heat exchanger, a new theoretical method of analyzing the thermal performance of heat pipe flat plate solar collector with cross flow heat exchanger has been put forward and validated by comparisons with the experimental and numerical results in pre-existing literature. The proposed theoretical method can be used to analyze and discuss the influence of relevant parameters on the thermal performance of heat pipe flat plate solar collector.

  6. Seasonal storage of energy in solar heating

    NASA Astrophysics Data System (ADS)

    Braun, J. E.; Klein, S. A.; Mitchell, J. W.

    1981-01-01

    This paper focuses on several aspects of seasonal storage for space heating using water as the storage medium. The interrelationships between collector area, storage volume, and system performance are investigated using the transient simulation program TRNSYS. The situations for which seasonal storage is most promising are presented. Particular emphasis is placed upon design of seasonal storage systems. A design method is presented which is applicable for storage capacities ranging from a few days to seasonal storage. This design method, coupled with cost information, should be useful in assessing the economic viability of seasonal storage systems. Also investigated are the importance of the load heat exchanger size, tank insulation, collector slope, and year-to-year weather variations in system design.

  7. Local entropy production in turbulent shear flows: A tool for evaluating heat transfer performance

    NASA Astrophysics Data System (ADS)

    Herwig, H.; Kock, F.

    2006-06-01

    Performance evaluation of heat transfer devices can be based on the overall entropy production in these devices. In our study we therefore provide equations for the systematic and detailed determination of local entropy production due to dissipation of mechanical energy and due to heat conduction, both in turbulent flows. After turbulence modeling has been incorporated for the fluctuating parts the overall entropy production can be determined by integration with respect to the whole flow domain. Since, however, entropy production rates show very steep gradients close to the wall, numerical solutions are far more effective with wall functions for the entropy production terms. These wall functions are mandatory when high Reynolds number turbulence models are used. For turbulent flow in a pipe with an inserted twisted tape as heat transfer promoter it is shown that based on the overall entropy production rate a clear statement from a thermodynamic point of view is possible. For a certain range of twist strength there is a decrease in overall entropy production compared to the case without insert. Also, the optimum twist strength can be determined. This information is unavailable when only pressure drop and heat transfer data are given.

  8. Heat Transfer Within a Fluid Filled Deformable Permeable Spherical Shell in Slow Viscous Flow

    NASA Astrophysics Data System (ADS)

    Mohais, R.

    2006-12-01

    Forced convective heat transfer is studied in a system of a fluid filled hollow permeable spherical shell set within a slow viscous flow of small Reynolds number, Re. The free fluid regions within and outside of the shell obey Stokesian flow theory while the fluid filled permeable region is governed by Darcy's law. The external surface of the shell is made deformable so that solutions can also be obtained for systems whose surfaces approach real bodies not possessing a spherical external surface. The well-known Beavers-Joseph slip boundary conditions are applied both to the internal and external surfaces of the shell to determine the analytical solutions for the fluid flow within the three regions. The further application of the energy equation to the system and the use of inhomogeneous mixed thermal boundary conditions on the two surfaces allow for analytic expressions to be obtained for the heat transfer up to O(PrRe), for small Re and Prandtl number, Pr of O(1). This study allows for the investigation of geothermal transport systems such as exists in certain ignimbrite terrains where ground water of meteoric origin is trapped and becomes superheated in underground systems. This water travels via cracks and faults to neighboring permeable structures with deformable surface layers and filters to a hollow core. Heat is transported not only by thermal conduction but by the convecting liquid as well. Analytic solutions such as the one presented here attest to the enhancement of heat transfer by permeable bodies.

  9. Comment on ``Long-Term Global Heating From Energy Use''

    NASA Astrophysics Data System (ADS)

    Fleming, James R.

    2008-12-01

    In a prominent article published in Tellus in 1969, Mikhail I. Budyko, with the Main Geophysical Observatory, Leningrad, Soviet Union, wrote that ``all the energy used by man is transformed into heat, the main portion of this energy being an additional source of heat as compared to the present radiation gain'' [Budyko, 1969, p. 618]. He pointed out that this heating was over and above any climate forcing from anthropogenic greenhouse gases and-since energy use was growing geometrically-it was likely to result in the retreat of the cryosphere, accompanied by excessive and potentially damaging global warming, perhaps in 200 years or less. Eric J. Chaisson, in Eos (``Long-Term Global Heating From Energy Use,'' 89(28), 253-254, 2008), does not acknowledge Budyko's research. Chaisson cites cosmic history and the history of the human species, but he provides no references to the conceptual history of the idea that human energy use could result in global heating. Budyko first published on the Earth's heat budget in 1948 and in 1998 received the Blue Planet Prize, sponsored by the Asahi Glass Foundation, for his lifetime accomplishments in quantitative climatology. His work on the energy budget of the Earth and anthropogenic influences really should have been cited (see a selection of key articles in the online National Science Digital Library, at http://wiki.nsdl.org/index.php/PALE:ClassicArticles/GlobalWarming).

  10. Heating surface material’s effect on subcooled flow boiling heat transfer of R134a

    SciTech Connect

    Ling Zou; Barclay G. Jones

    2012-11-01

    In this study, subcooled flow boiling of R134a on copper (Cu) and stainless steel (SS) heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. By utilizing a high-speed digital camera, bubble growth rate, bubble departure size, and nucleation site density, were able to be observed and analyzed from the microscopic point of view. Macroscopic characteristics of the subcooled flow boiling, such as heat transfer coefficient, were able to be measured as well. Experimental results showed that there are no obvious difference between the copper and the stainless surface with respect to bubble dynamics, such as contact angle, growth rate and departure size. On the contrary, the results clearly showed a trend that the copper surface had a better performance than the stainless steel surface in terms of heat transfer coefficient. It was also observed that wall heat fluxes on both surfaces were found highly correlated with nucleation site density, as bubble hydrodynamics are similar on these two surfaces. The difference between these two surfaces was concluded as results of different surface thermal conductivities.

  11. Pressure Drop and Heat Transfer of Water Flowing Shell-Side of Multitube Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Ohashi, Yukio; Hashizume, Kenichi

    Experimental studies on heat transfer augmentation in water-flowing shell sides of counter flow multitube exchangers are presented. Various kinds of augmented tube bundles have been examined to obtain the characteristics of pressure drop and heat transfer. Data for a smooth tube bundle were a little different from those for the tube side. The pressure drop in the shell side depended on Re-0.4 and deviated from the tube side pressure drop to within +30%, while the shell side heat transfer coefficient depended on Re0.8 but about 35%. larger than that of the tube side. Furthermore the augmented tube bundles have been evaluated and compared using 21 evaluation criteria. Enhanced tube bundles, low-finned tube bundles and those with twisted tapes inserted had especially good performances. The ratios of increase in heat transfer were larger than those in pressure drop. In case of low-finned tube bundles, there seem to exist an optimum fin-pitch and an optimum relation between the fin-pitch and the pitch of twisted tapes inserted.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  13. Newtonian heating effect in nanofluid flow by a permeable cylinder

    NASA Astrophysics Data System (ADS)

    Hayat, T.; Khan, M. Ijaz; Waqas, M.; Alsaedi, A.

    Here characteristics of Newtonian heating in permeable stretched flow of viscous nanomaterial are investigated. Adopted nanomaterial model incorporates the phenomena of Brownian motion and thermophoresis. Concept of boundary layer is employed for the formulation procedure. Convergent homotopic solutions are established for the nonlinear systems. Velocity, thermal and nanoparticles fields for nonlinear boundary value problems are computed and discussed. The velocity, temperature and concentration gradients are also evaluated. It is noticed that impacts of curvature and suction/injection parameters on skin friction coefficient are qualitatively similar. Moreover temperature distribution enhances for larger thermophoresis and Brownian motion parameters.

  14. Injected power and entropy flow in a heated granular gas

    NASA Astrophysics Data System (ADS)

    Visco, P.; Puglisi, A.; Barrat, A.; Trizac, E.; van Wijland, F.

    2005-10-01

    Our interest goes to the power injected in a heated granular gas and to the possibility to interpret it in terms of entropy flow. We numerically determine the distribution of the injected power by means of Monte Carlo simulations. Then, we provide a kinetic-theory approach to the computation of such a distribution function. Finally, after showing why the injected power does not satisfy a fluctuation relation à la Gallavotti-Cohen, we put forward a new quantity which does fulfill such a relation, and is not only applicable in a variety of frameworks outside the granular world, but also experimentally accessible.

  15. Mineral balance in milk heated using microwave energy.

    PubMed

    de la Fuente, Miguel Angel; Olano, Agustín; Juárez, Manuela

    2002-04-10

    Milk heated to 75 and 85 degrees C in a water bath or in a microwave oven was assayed for changes in salt partitioning after cooling to room temperature. To properly to assess differences and draw valid comparisons, the two heating methods used in the experiment were applied to samples for identical exposure times, and the samples were heated to attain the same final temperatures. Although the soluble Ca and P(i) contents were lower in the heated milk samples, no significant differences in salt partitioning were found between microwave and conventional heating. Ionic calcium levels in the milk samples pasteurized using microwave energy were very close to the levels in the samples heated in a conventional water bath (approximately 90% of the level in the untreated milk samples). The microwave heating-induced changes were completely reversed after storage at 20 degrees C for 24 h. The coagulation properties of the heated milk samples were also examined, and the coagulation time was longer and the curd formation rate slower in the microwave-heated milk than in the raw milk. Still, the experimental results demonstrated that microwave heating was no more detrimental to the milk than conventional heating and could thus be used for pasteurization purposes.

  16. Chemical heat pump and chemical energy storage system

    DOEpatents

    Clark, Edward C.; Huxtable, Douglas D.

    1985-08-06

    A chemical heat pump and storage system employs sulfuric acid and water. In one form, the system includes a generator and condenser, an evaporator and absorber, aqueous acid solution storage and water storage. During a charging cycle, heat is provided to the generator from a heat source to concentrate the acid solution while heat is removed from the condenser to condense the water vapor produced in the generator. Water is then stored in the storage tank. Heat is thus stored in the form of chemical energy in the concentrated acid. The heat removed from the water vapor can be supplied to a heat load of proper temperature or can be rejected. During a discharge cycle, water in the evaporator is supplied with heat to generate water vapor, which is transmitted to the absorber where it is condensed and absorbed into the concentrated acid. Both heats of dilution and condensation of water are removed from the thus diluted acid. During the discharge cycle the system functions as a heat pump in which heat is added to the system at a low temperature and removed from the system at a high temperature. The diluted acid is stored in an acid storage tank or is routed directly to the generator for reconcentration. The generator, condenser, evaporator, and absorber all are operated under pressure conditions specified by the desired temperature levels for a given application. The storage tanks, however, can be maintained at or near ambient pressure conditions. In another form, the heat pump system is employed to provide usable heat from waste process heat by upgrading the temperature of the waste heat.

  17. Metal-halide mixtures for latent heat energy storage

    NASA Technical Reports Server (NTRS)

    Chen, K.; Manvi, R.

    1981-01-01

    Some candidates for alkali metal and alkali halide mixtures suitable for thermal energy storage at temperatures 600 C are identified. A solar thermal system application which offer advantages such as precipitation of salt crystals away from heat transfer surfaces, increased thermal conductivity of phase change materials, corrosion inhibition, and a constant monotectic temperature, independent of mixture concentrations. By using the lighters, metal rich phase as a heat transfer medium and the denser, salt rich phase as a phase change material for latent heat storage, undesirable solidification on the heat transfer surface may be prevented, is presented.

  18. Simulation and evaluation of latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Sigmon, T. W.

    1980-01-01

    The relative value of thermal energy storage (TES) for heat pump storage (heating and cooling) as a function of storage temperature, mode of storage (hotside or coldside), geographic locations, and utility time of use rate structures were derived. Computer models used to simulate the performance of a number of TES/heat pump configurations are described. The models are based on existing performance data of heat pump components, available building thermal load computational procedures, and generalized TES subsystem design. Life cycle costs computed for each site, configuration, and rate structure are discussed.

  19. An improved algorithm for the modeling of vapor flow in heat pipes

    NASA Technical Reports Server (NTRS)

    Tower, Leonard K.; Hainley, Donald C.

    1989-01-01

    A heat pipe vapor flow algorithm suitable for use in codes on microcomputers is presented. The incompressible heat pipe vapor flow studies of Busse are extended to incorporate compressibility effects. The Busse velocity profile factor is treated as a function of temperature and pressure. The assumption of a uniform saturated vapor temperature determined by the local pressure at each cross section of the pipe is not made. Instead, a mean vapor temperature, defined by an energy integral, is determined in the course of the solution in addition to the pressure, saturation temperature at the wall, and the Busse velocity profile factor. For alkali metal working fluids, local species equilibrium is assumed. Temperature and pressure profiles are presented for several cases involving sodium heat pipes. An example for a heat pipe with an adiabatic section and two evaporators in sequence illustrates the ability to handle axially varying heat input. A sonic limit plot for a short evaporator falls between curves for the Busse and Levy inviscid sonic limits.

  20. Flow regimes and heat transfer in vertical narrow annuli

    SciTech Connect

    Ulke, A.; Goldberg, I.

    1993-11-01

    In shell side boiling heat exchangers narrow crevices that are formed between the tubes and the tube support structure provide areas for local thermal-hydraulic conditions which differ significantly from bulk fluid conditions. Understanding of the processes of boiling and dryout in flow restricted crevices can help in designing of tube support geometries to minimize the likelihood of tube support plate and tube corrosion observed in commercial power plant steam generators. This paper describes a one dimensional thermal-hydraulic model of a vertical crevice between a tube and a support plate with cylindrical holes. The annulus formed by the support plate hole and an eccentrically located tube has been represented by vertical strips. The formation, growth and collapse of a steam bubble in each strip has been determined. Based on the bubble history, and flow regimes characterized by ``isolated`` bubbles, ``coalesced`` bubbles and liquid deficient regions have been defined.

  1. Reattachment heating upstream of short compression ramps in hypersonic flow

    NASA Astrophysics Data System (ADS)

    Estruch-Samper, David

    2016-05-01

    Hypersonic shock-wave/boundary-layer interactions with separation induce unsteady thermal loads of particularly high intensity in flow reattachment regions. Building on earlier semi-empirical correlations, the maximum heat transfer rates upstream of short compression ramp obstacles of angles 15° ⩽ θ ⩽ 135° are here discretised based on time-dependent experimental measurements to develop insight into their transient nature (Me = 8.2-12.3, Re_h= 0.17× 105-0.47× 105). Interactions with an incoming laminar boundary layer experience transition at separation, with heat transfer oscillating between laminar and turbulent levels exceeding slightly those in fully turbulent interactions. Peak heat transfer rates are strongly influenced by the stagnation of the flow upon reattachment close ahead of obstacles and increase with ramp angle all the way up to θ =135°, whereby rates well over two orders of magnitude above the undisturbed laminar levels are intermittently measured (q'_max>10^2q_{u,L}). Bearing in mind the varying degrees of strength in the competing effect between the inviscid and viscous terms—namely the square of the hypersonic similarity parameter (Mθ )^2 for strong interactions and the viscous interaction parameter bar{χ } (primarily a function of Re and M)—the two physical factors that appear to most globally encompass the effects of peak heating for blunt ramps (θ ⩾ 45°) are deflection angle and stagnation heat transfer, so that this may be fundamentally expressed as q'_max∝ {q_{o,2D}} θ ^2 with further parameters in turn influencing the interaction to a lesser extent. The dominant effect of deflection angle is restricted to short obstacle heights, where the rapid expansion at the top edge of the obstacle influences the relaxation region just downstream of reattachment and leads to an upstream displacement of the separation front. The extreme heating rates result from the strengthening of the reattaching shear layer with the increase in

  2. Non-linear heat and mass transfer in a MHD Homann nanofluid flow through a porous medium with chemical reaction, heat generation and uniform inflow

    NASA Astrophysics Data System (ADS)

    EL-Dabe, N. T.; Attia, H. A.; Essawy, M. A. I.; Ramadan, A. A.; Abdel-Hamid, A. H.

    2016-11-01

    The steady MHD axisymmetric flow of an incompressible viscous electrically conducting nanofluid impinging on a permeable plate is investigated with heat and mass transfer. An external uniform magnetic field as well as a uniform inflow, in the presence of either suction or injection, are applied normal to the plate. The effects of heat (generation/absorption) and chemical reaction have been accentuated. This study indicates the incorporated influence of both the thermophoresis phenomenon and the Brownian behavior. Numerical solutions for the governing non-linear momentum, energy and nanoparticle equations have been obtained. The rates of heat and mass transfer are presented and discussed.

  3. Dark Energy Domination In The Virgocentric Flow

    NASA Astrophysics Data System (ADS)

    Byrd, Gene; Chernin, A. D.; Karachentsev, I. D.; Teerikorpi, P.; Valtonen, M.; Dolgachev, V. P.; Domozhilova, L. M.

    2011-04-01

    Dark energy (DE) was first observationally detected at large Gpc distances. If it is a vacuum energy formulated as Einstein's cosmological constant, Λ, DE should also have dynamical effects at much smaller scales. Previously, we found its effects on much smaller Mpc scales in our Local Group (LG) as well as in other nearby groups. We used new HST observations of member 3D distances from the group centers and Doppler shifts. We find each group's gravity dominates a bound central system of galaxies but DE antigravity results in a radial recession increasing with distance from the group center of the outer members. Here we focus on the much larger (but still cosmologically local) Virgo Cluster and systems around it using new observations of velocities and distances. We propose an analytic model whose key parameter is the zero-gravity radius (ZGR) from the cluster center where gravity and DE antigravity balance. DE brings regularity to the Virgocentric flow. Beyond Virgo's 10 Mpc ZGR, the flow curves to approach a linear global Hubble law at larger distances. The Virgo cluster and its outer flow are similar to the Local Group and its local outflow with a scaling factor of about 10; the ZGR for Virgo is 10 times larger than that of the LG. The similarity of the two systems on the scales of 1 to 30 Mpc suggests that a quasi-stationary bound central component and an expanding outflow applies to a wide range of groups and clusters due to small scale action of DE as well as gravity. Chernin, et al 2009 Astronomy and Astrophysics 507, 1271 http://arxiv.org/abs/1006.0066 http://arxiv.org/abs/1006.0555

  4. Joule heating effects on electroosmotic flow in insulator-based dielectrophoresis.

    PubMed

    Sridharan, Sriram; Zhu, Junjie; Hu, Guoqing; Xuan, Xiangchun

    2011-09-01

    Insulator-based dielectrophoresis (iDEP) is an emerging technology that has been successfully used to manipulate a variety of particles in microfluidic devices. However, due to the locally amplified electric field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb the electroosmotic flow and affect the particle motion. This work presents the first experimental study of Joule heating effects on electroosmotic flow in a typical iDEP device, e.g., a constriction microchannel, under DC-biased AC voltages. A numerical model is also developed to simulate the observed flow pattern by solving the coupled electric, energy, and fluid equations in a simplified two-dimensional geometry. It is observed that depending on the magnitude of the DC voltage, a pair of counter-rotating fluid circulations can occur at either the downstream end alone or each end of the channel constriction. Moreover, the pair at the downstream end appears larger in size than that at the upstream end due to DC electroosmotic flow. These fluid circulations, which are reasonably simulated by the numerical model, form as a result of the action of the electric field on Joule heating-induced fluid inhomogeneities in the constriction region.

  5. Radiation effect on viscous flow of a nanofluid and heat transfer over a nonlinearly stretching sheet

    PubMed Central

    2012-01-01

    In this work, we study the flow and heat transfer characteristics of a viscous nanofluid over a nonlinearly stretching sheet in the presence of thermal radiation, included in the energy equation, and variable wall temperature. A similarity transformation was used to transform the governing partial differential equations to a system of nonlinear ordinary differential equations. An efficient numerical shooting technique with a fourth-order Runge-Kutta scheme was used to obtain the solution of the boundary value problem. The variations of dimensionless surface temperature, as well as flow and heat-transfer characteristics with the governing dimensionless parameters of the problem, which include the nanoparticle volume fraction ϕ, the nonlinearly stretching sheet parameter n, the thermal radiation parameter NR, and the viscous dissipation parameter Ec, were graphed and tabulated. Excellent validation of the present numerical results has been achieved with the earlier nonlinearly stretching sheet problem of Cortell for local Nusselt number without taking the effect of nanoparticles. PMID:22520273

  6. Energy Conversion Advanced Heat Transport Loop and Power Cycle

    SciTech Connect

    Oh, C. H.

    2006-08-01

    The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various

  7. Energy Factor Analysis for Gas Heat Pump Water Heaters

    SciTech Connect

    Gluesenkamp, Kyle R

    2016-01-01

    Gas heat pump water heaters (HPWHs) can improve water heating efficiency with zero GWP and zero ODP working fluids. The energy factor (EF) of a gas HPWH is sensitive to several factors. In this work, expressions are derived for EF of gas HPWHs, as a function of heat pump cycle COP, tank heat losses, burner efficiency, electrical draw, and effectiveness of supplemental heat exchangers. The expressions are used to investigate the sensitivity of EF to each parameter. EF is evaluated on a site energy basis (as used by the US DOE for rating water heater EF), and a primary energy-basis energy factor (PEF) is also defined and included. Typical ranges of values for the six parameters are given. For gas HPWHs, using typical ranges for component performance, EF will be 59 80% of the heat pump cycle thermal COP (for example, a COP of 1.60 may result in an EF of 0.94 1.28). Most of the reduction in COP is due to burner efficiency and tank heat losses. Gas-fired HPWHs are theoretically be capable of an EF of up to 1.7 (PEF of 1.6); while an EF of 1.1 1.3 (PEF of 1.0 1.1) is expected from an early market entry.

  8. Heat flow and thermal history of the Anadarko basin, Oklahoma

    USGS Publications Warehouse

    Carter, L.S.; Kelley, S.A.; Blackwell, D.D.; Naeser, N.D.

    1998-01-01

    New heat-flow values for seven sites in the Anadarko basin, Oklahoma, were determined using high-precision temperature logs and thermal conductivity measurements from nearly 300 core plugs. Three of the sites are on the northern shelf, three sites are in the deep basin, and one site is in the frontal fault zone of the northern Wichita Mountains. The heat flow decreased from 55 to 64 mW/m2 in the north, and from 39 to 54 mW/m2 in the south, due to a decrease in heat generation in the underlying basement rock toward the south. Lateral lithologic changes in the basin, combined with the change in heat flow across the basin, resulted in an unusual pattern of thermal maturity. The vitrinite reflectance values of the Upper Devonian-Lower Mississippian Woodford formation are highest 30-40 km north-northwest of the deepest part of the basin. The offset in highest reflectance values is due to the contrast in thermal conductivity between the Pennsylvanian "granite wash" section adjacent to the Wichita uplift and the Pennsylvanian shale section to the north. The geothermal gradient in the low-conductivity shale section is elevated relative to the geothermal gradient in the high-conductivity "granite wash" section, thus displacing the highest temperatures to the north of the deepest part of the basin. Apatite fission-track, vitrinite reflectance, and heat-flow data were used to constrain regional aspects of the burial history of the Anadarko basin. By combining these data sets, we infer that at least 1.5 km of denudation has occurred at two sites in the deep Anadarko basin since the early to middle Cenozoic (40 ?? 10 m.y.). The timing of the onset of denudation in the southern Anadarko basin coincides with the period of late Eocene erosion observed in the southern Rocky Mountains and in the northern Great Plains. Burial history models for two wells from the deep Anadarko basin predict that shales of the Woodford formation passed through the hydrocarbon maturity window by the

  9. Volcanic eruptions on Io: Heat flow, resurfacing, and lava composition

    NASA Technical Reports Server (NTRS)

    Blaney, Diana L.; Johnson, Torrence V.; Matson, Dennis L.; Veeder, Glenn J.

    1995-01-01

    We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.5 x 10(exp 5)/sq m and cooled from 1225 to 555 K over the 2.583-hr period of observation. The inferred effusion rate of 3 x 10(exp 5) cu m/sec for this eruption is very high, but is not unprece- dented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur approxi- mately 6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 10(exp 14) W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992; Veeder et al. 1994) can be accounted for by a series of silicate lava flows in various stages of cooling. We propose that the whole suite of Io's currently observed thermal anomalies was produced by multiple, high-eruptive-rate silicate flows within the past century.

  10. Rapid charging of thermal energy storage materials through plasmonic heating.

    PubMed

    Wang, Zhongyong; Tao, Peng; Liu, Yang; Xu, Hao; Ye, Qinxian; Hu, Hang; Song, Chengyi; Chen, Zhaoping; Shang, Wen; Deng, Tao

    2014-09-01

    Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites.

  11. Rapid Charging of Thermal Energy Storage Materials through Plasmonic Heating

    PubMed Central

    Wang, Zhongyong; Tao, Peng; Liu, Yang; Xu, Hao; Ye, Qinxian; Hu, Hang; Song, Chengyi; Chen, Zhaoping; Shang, Wen; Deng, Tao

    2014-01-01

    Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites. PMID:25175717

  12. National need for utilizing nuclear energy for process heat generation

    SciTech Connect

    Gambill, W.R.; Kasten, P.R.

    1984-01-01

    Nuclear reactors are potential sources for generating process heat, and their applications for such use economically competitive. They help satisfy national needs by helping conserve and extend oil and natural gas resources, thus reducing energy imports and easing future international energy concerns. Several reactor types can be utilized for generating nuclear process heat; those considered here are light water reactors (LWRs), heavy water reactors (HWRs), gas-cooled reactors (GCRs), and liquid metal reactors (LMRs). LWRs and HWRs can generate process heat up to 280/sup 0/C, LMRs up to 540/sup 0/C, and GCRs up to 950/sup 0/C. Based on the studies considered here, the estimated process heat markets and the associated energy markets which would be supplied by the various reactor types are summarized.

  13. Experimental investigation on drag and heat flux reduction in supersonic/hypersonic flows: A survey

    NASA Astrophysics Data System (ADS)

    Wang, Zhen-guo; Sun, Xi-wan; Huang, Wei; Li, Shi-bin; Yan, Li

    2016-12-01

    The drag and heat reduction problem of hypersonic vehicles has always attracted the attention worldwide, and the experimental test approach is the basis of theoretical analysis and numerical simulation. In the current study, research progress of experimental investigations on drag and heat reduction are summarized by several kinds of mechanism, namely the forward-facing cavity, the opposing jet, the aerospike, the energy deposition and their combinational configurations, and the combinational configurations include the combinational opposing jet and forward-facing cavity concept and the combinational opposing jet and aerospike concept. The geometric models and flow conditions are emphasized, especially for the basic principle for the drag and heat flux reduction of each device. The measurement results of aerodynamic and aerothermodynamic are compared and analyzed as well, which can be a reference for assessing the accuracy of numerical results.

  14. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1982-03-01

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

  15. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1980-11-01

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

  16. U.S. energy flow - 1993

    SciTech Connect

    Borg, I.Y.; Briggs, C.K.

    1994-10-01

    With continued improvement in the economic health of the nation, energy consumption in 1993 increased by almost 2.5%. Use of energy in all major end-use sectors increased, with the largest gains registered in the residential/commercial sector. In this sector, substantial increase in the use of natural gas reflected a harsh 1993-1994 winter as well as broader availability of the fuel for space heating. Crude oil imports rose 8% but stood below the all-time high set in 1977. About half of the increase reflected declining domestic oil production. Imports of natural gas, principally from Canada, increased as they have every year since 1986. They comprise 11% of supply and supplement domestic production, which has similarly risen over the same time span. Increased demand for natural gas is evident in most sectors but especially in the industrial sector, where a growing number of cogenerators of electricity burn natural gas. Although coal consumption in the United States rose 3% in 1993, domestic coal production declined by a greater margin due to a coal strike. Because of increased international competition, exports fell 27%. Electricity transmitted by the utilities again increased, following a decade-long trend interrupted only in 1992 by the national economic recession. The provisions of the Energy Policy Act of 1992 dealing with transport of nonutility-generated electricity by the public utilities began to be implemented in 1993. The provisions of the Energy Policy Act as well as those of the Public Utility Regulatory Policies Act of 1978 are setting the stage for increased competition for customers and for what promises to be a restructuring of the historically monopolistic industry. Nuclear power from the United States`s 109 operable reactors constituted 21% of utility-generated electricity. With the continued retirement of outmoded and flawed reactors, nuclear capacity factors attained 71 in 1993, up from 56% a decade earlier.

  17. High frequency electromagnetism, heat transfer and fluid flow coupling in ANSYS multiphysics.

    PubMed

    Sabliov, Cristina M; Salvi, Deepti A; Boldor, Dorin

    2007-01-01

    The goal of this study was to numerically predict the temperature of a liquid product heated in a continuous-flow focused microwave system by coupling high frequency electromagnetism, heat transfer, and fluid flow in ANSYS Multiphysics. The developed model was used to determine the temperature change in water processed in a 915 MHz microwave unit, under steady-state conditions. The influence of the flow rates on the temperature distribution in the liquid was assessed. Results showed that the average temperature of water increased from 25 degrees C to 34 degrees C at 2 l/min, and to 42 degrees C at 1 l/min. The highest temperature regions were found in the liquid near the center of the tube, followed by progressively lower temperature regions as the radial distance from the center increased, and finally followed by a slightly higher temperature region near the tube's wall corresponding to the energy distribution given by the Mathieu function. The energy distribution resulted in a similar temperature pattern, with the highest temperatures close to the center of the tube and lower at the walls. The presented ANSYS Multiphysics model can be easily improved to account for complex boundary conditions, phase change, temperature dependent properties, and non-Newtonian flows, which makes for an objective of future studies.

  18. Energy Integrated Design of Lighting, Heating, and Cooling Systems, and Its Effect on Building Energy Requirements.

    ERIC Educational Resources Information Center

    Meckler, Gershon

    Comments on the need for integrated design of lighting, heating, and cooling systems. In order to eliminate the penalty of refrigerating the lighting heat, minimize the building non-usable space, and optimize the total energy input, a "systems approach" is recommended. This system would employ heat-recovery techniques based on the ability of the…

  19. Flow Dynamics and Plasma Heating of Spheromaks in SSX

    NASA Astrophysics Data System (ADS)

    Brown, M. R.; Cothran, C. D.; Cohen, D. H.; Horwitz, J.; Chaplin, V.

    2008-06-01

    We report several new experimental results related to flow dynamics and heating from single dipole-trapped spheromaks and spheromak merging studies at SSX. Single spheromaks (stabilized with a pair of external coils, see Brown, Phys. Plasmas 13 102503 (2006)) and merged FRC-like configurations (see Brown, Phys. Plasmas 13, 056503 (2006)) are trapped in our prolate ( R = 0.2 m, L = 0.6 m) copper flux conserver. Local spheromak flow is studied with two Mach probes ( r 1 ≤ ρ i , r 2 ≥ ρ i ) calibrated by time-of-flight with a fast set of magnetic probes at the edge of the device. Both Mach probes feature six ion collectors housed in a boron nitride sheath. The larger Mach probe will ultimately be used in the MST reversed field pinch. Line averaged flow is measured by ion Doppler spectroscopy (IDS) at the midplane. The SSX IDS instrument measures with 1 μ s or better time resolution the width and Doppler shift of the C III impurity (H plasma) 229.7 nm line to determine the temperature and line-averaged flow velocity (see Cothran, RSI 77, 063504 (2006)). We find axial flows up to 100 km/s during formation of the dipole trapped spheromak. Flow returns at the wall to form a large vortex. Recent high-resolution IDS velocity measurements during spheromak merging show bi-directional outflow jets at ±40 km/s (nearly the Alfvén speed). We also measure T i ≥ 80 eV and T e ≥ 20 eV during spheromak merging events after all plasma facing surfaces are cleaned with helium glow discharge conditioning. Transient electron heating is inferred from bursts on a four-channel soft x-ray array. The spheromaks are also characterized by a suite of magnetic probe arrays for magnetic structure B(r,t), and interferometry for n e . Finally, we are designing a new oblate, trapezoidal flux conserver for FRC studies. Equilibrium and dynamical simulations suggest that a tilt-stable, oblate FRC can be formed by spheromak merging in the new flux conserver.

  20. Computational analysis of heat flow in computer casing

    NASA Astrophysics Data System (ADS)

    Nor Azwadi, C. S.; Goh, C. K.; Afiq Witri, M. Y.

    2012-06-01

    Reliability of a computer system is directly related to thermal management system. This is due to the fact that poor thermal management led to high temperature distribution throughout hardware components and resulting poor performance and reducing fatigue life of the package. Therefore, good cooling solutions (heat sink, fan) and proper form factor design (expandability, interchangeable of parts) is necessary to provide good thermal management in computer system. The performance of Advanced Technology Extended (ATX) and its purposed successor, Balanced Technology Extended (BTX) were compared to investigate the aforementioned factors. Simulations were conducted by using ANSYS software. Results obtained from simulations were compared with values in the datasheet obtained from manufacturers for validation purposes and it was discovered that there are more chaos region in the flow profile for ATX form factor. In contrast, BTX form factor yields a straighter flow profile. Based on the result, we can conclude that BTX form factor has better cooling capability compared to its predecessor, ATX due to the improvement of layout made in the BTX form factor. With this change, it enabled BTX form factor to be used with more advanced components which dissipate more amount of heat and also improves the acoustic performance of BTX by reducing the number of fan needed to just one unit for BTX.

  1. Heat Loss Experiments: Teach Energy Savings with Cardboard "House"

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2011-01-01

    Using two cardboard boxes, a light bulb socket, light bulbs of varying wattage, a thermometer, and some insulation, students can learn some interesting lessons about how heat loss occurs in homes. This article describes practical experiments that work well on units related to energy, sustainable energy, renewables, engineering, and construction.…

  2. Heating, Ventilating, and Air Conditioning. Energy Technology Series.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This course in heating, ventilating, and air conditioning is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

  3. Flow of Supercritical Hydrogen in a Uniformly Heated Circular Tube

    NASA Technical Reports Server (NTRS)

    Youn, B.; Mills, A. F.

    1993-01-01

    Turbulent flow of supercritical hydrogen through a uniformly heated circular tube has been investigated using numerical methods, for the range of 4 x 10(exp 5) less than Re less than 3 x 10(exp 6), 5 less than or equal to q(sub W) less than or equal to 10 MW/sq m, 30 less than or equal to T(sub in) less than or equal to 90 K, and 5 less than or equal to P(sub in) less than or equal to 15 MPa. The purpose is to validate a turbulence model and calculation method for the design of active cooling systems of hydrogen-fueled hypersonic aircraft, where the hydrogen fuel a used as coolant. The PHOENICS software package was used for the computations, which required special provision for evaluation of the thermophysical properties of the supercritical hydrogen, and a low Reynolds number form of the k-epsilon turbulence model. Pressure drop and heat transfer data were compared with experiment and existing correlations and good agreement was demonstrated. For the pressure range considered here a "thermal spike" was observed and shown to be due to the secondary peak in specific heat, rather than the primary peak.

  4. Hydrodynamics and heat transfer for pulsating laminar flow in channels

    NASA Astrophysics Data System (ADS)

    Valueva, E. P.; Purdin, M. S.

    2015-09-01

    The problem about laminar pulsating flow and heat transfer with high pulsation amplitudes of average cross-section velocity in a round tube and in a flat channel is solved using the finite element method. The difference scheme's optimal parameters are determined. Data on the pulsation amplitude and phase are obtained for the hydraulic friction coefficient, tangential stress on the wall, liquid temperature, heat flux on the wall q w (at ϑw = const), and wall temperature ϑw (at q w = const) are obtained. Two characteristic modes, namely, quasi steady-state and high-frequency ones are separated based on the value of dimensionless pulsation frequency. During operation in the quasi steady-state mode, the values of all hydrodynamic and thermal quantities correspond to the values of time-average velocity at the given time instant. For operation in the high-frequency mode, it is shown that the dependences of the pulsating components of hydrodynamic and thermal quantities on the dimensionless pulsation frequency have the same pattern for rectilinear channels having different shapes of their cross section. It is found that certain nodal points exist on the distribution of thermal characteristics along the tube (liquid temperature, heat flux density on the wall at ϑw = const, and wall temperature at q w = const) in which the values of these quantities remain unchanged. The distances between the nodal points decrease with increasing the pulsation frequency. The pulsations of thermal quantities decay over the tube length.

  5. Surface Energy Heat Fluxes Using Remotely Sensed Parameters

    NASA Technical Reports Server (NTRS)

    Toll, David L.; Vukovich, Fred M.; Pontikes, Elizabeth G.

    1997-01-01

    Realistic estimates of surface energy heat fluxes are needed for the study of water and energy interactions between the land and atmosphere. The primary objective of this work is to study the estimation of surface heat energy fluxes using remote sensing derived parameters under different spatial and temporal conditions. Surface energy fluxes and remote sensing derived data from two sources were analyzed. First, we used surface heat flux, remote sensing, and ancillary data from the International Satellite Land Surface Climatology Project (ISLSCP), mapped at a 1 deg. x 1 deg. grid. Second, we used NOAA AVHRR (1 km), weather station, and ancillary data to derive estimates of surface latent and sensible heat energy fluxes over a 100 sq kilometers area for three test sites: 1) First ISLSCP Field Experiment (FIFE) grassland site, Konza Prairie, Kansas; 2) Howland, Maine Forest Ecosystem Dynamics Site; and 3) Walnut Gulch, scrubland site, surrounding Tombstone, Arizona. Satellite derived estimates of land surface temperature, surface albedo, and spectral vegetation index are used in selected models to provide estimates of surface heat fluxes. Analysis of results from the 1 deg. x 1 deg. grid for North America indicated there were similar, overall correlations between sensible and latent heat energy fluxes versus remotely sensed vegetation index and ground temperature during dry and wet year conditions. However, there were significant differences in correlations between years when stratified by land cover class. Analysis of 100 km x 100 km data (1 km resolution) indicated partitioning the areas in to primary versus secondary cover, with the secondary cover comprising less than 5% of the area, significantly improved surface heat energy flux estimates.

  6. Aquifer thermal energy (heat and chill) storage

    SciTech Connect

    Jenne, E.A.

    1992-11-01

    As part of the 1992 Intersociety Conversion Engineering Conference, held in San Diego, California, August 3--7, 1992, the Seasonal Thermal Energy Storage Program coordinated five sessions dealing specifically with aquifer thermal energy storage technologies (ATES). Researchers from Sweden, The Netherlands, Germany, Switzerland, Denmark, Canada, and the United States presented papers on a variety of ATES related topics. With special permission from the Society of Automotive Engineers, host society for the 1992 IECEC, these papers are being republished here as a standalone summary of ATES technology status. Individual papers are indexed separately.

  7. Development of Compact, Modular Lunar Heat Flow Probes

    NASA Technical Reports Server (NTRS)

    Nagihara, S.; Zacny, K.; Hedlund, M.; Taylor, P. T.

    2014-01-01

    Geothermal heat flow measurements are a high priority for the future lunar geophysical network missions recommended by the latest Decadal Survey and previously the International Lunar Network. Because the lander for such a mission will be relatively small, the heat flow instrumentation must be a low-mass and low-power system. The instrument needs to measure both thermal gradient and thermal conductivity of the regolith penetrated. It also needs to be capable of excavating a deep enough hole (approx. 3 m) to avoid the effect of potential long-term changes of the surface thermal environment. The recently developed pneumatic excavation system can largely meet the low-power, low-mass, and the depth requirements. The system utilizes a stem which winds out of a pneumatically driven reel and pushes its conical tip into the regolith. Simultaneously, gas jets, emitted from the cone tip, loosen and blow away the soil. The thermal sensors consist of resistance temperature detectors (RTDs) embedded on the stem and an insitu thermal conductivity probe attached to the cone tip. The thermal conductivity probe consists of a short 'needle' (2.4-mm diam. and 15- to 20-mm length) that contains a platinum RTD wrapped in a coil of heater wire. During a deployment, when the penetrating cone reaches a desired depth, it stops blowing gas, and the stem pushes the needle into the yet-to-be excavated, undisturbed bottom soil. Then, it begins heating and monitors the temperature. Thermal conductivity of the soil can determined from the rate of temperature increase with time. When the measurement is complete, the system resumes excavation until it reaches the next targeted depth.

  8. Flow regimes and mechanistic modeling of critical heat flux under subcooled flow boiling conditions

    NASA Astrophysics Data System (ADS)

    Le Corre, Jean-Marie

    Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types of CHF flow regimes were identified (bubbly, vapor clot and slug flow regime) and a CHF flow regime map was developed, based on a dimensional analysis of the phenomena and available data. It was found that for similar geometric characteristics and pressure, a Weber number (We)/thermodynamic quality (x) map can be used to predict the CHF flow regime. Based on the experimental observations and the review of the available CHF mechanistic models under subcooled flow boiling conditions, hypothetical CHF mechanisms were selected for each CHF flow regime, all based on a concept of wall dry spot overheating, rewetting prevention and subsequent dry spot spreading. It is postulated that a high local wall superheat occurs locally in a dry area of the heated wall, due to a cyclical event inherent to the considered CHF two-phase flow regime, preventing rewetting (Leidenfrost effect). The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow. A numerical model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. In this type of CHF two-phase flow regime, the high local wall superheat occurs underneath a nucleating bubble at the time of bubble departure. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. The model has also the potential to evaluate

  9. Turning up the heat on energy performance.

    PubMed

    Holme, Chris

    2008-09-01

    Chris Holme, principal engineer, Gateway Review and Estates and Facilities Division, Department of Health (DH), discusses what a new requirement for those running large publicly-owned buildings to display, publicly, information on their site's energy consumption will mean for the NHS when it comes into force on 1 October.

  10. Energy coupling and plume dynamics during high power laser heating of metals

    SciTech Connect

    Jeong, S. |

    1997-05-01

    High power laser heating of metals was studied utilizing experimental and numerical methods with an emphasis on the laser energy coupling with a target and on the dynamics of the laser generated vapor flow. Rigorous theoretical modeling of the heating, melting, and evaporation of metals due to laser radiation with a power density below the plasma shielding threshold was carried out. Experimentally, the probe beam deflection technique was utilized to measure the propagation of a laser induced shock wave. The effects of a cylindrical cavity in a metal surface on the laser energy coupling with a solid were investigated utilizing photothermal deflection measurements. A numerical calculation of target temperature and photothermal deflection was performed to compare with the measured results. Reflection of the heating laser beam inside the cavity was found to increase the photothermal deflection amplitude significantly and to enhance the overall energy coupling between a heating laser beam and a solid. Next, unsteady vaporization of metals due to nanosecond pulsed laser heating with an ambient gas at finite pressure was analyzed with a one dimensional thermal evaporation model for target heating and one dimensional compressible flow equations for inviscid fluid for the vapor flow. Lastly, the propagation of a shock wave during excimer laser heating of aluminum was measured with the probe beam deflection technique. The transit time of the shock wave was measured at the elevation of the probe beam above the target surface; these results were compared with the predicted behavior using ideal blast wave theory. The propagation of a gaseous material plume was also observed from the deflection of the probe beam at later times.

  11. Flow and heat transfer model for a rotating cryogenic motor

    SciTech Connect

    Dykhuizen, R.C.; Baca, R.G.; Bickel, T.C.

    1993-08-01

    Development of a high-temperature, superconducting, synchronous motor for large applications (>1000 HP) could offer significant electrical power savings for industrial users. Presently 60% of all electric power generated in the United States is converted by electric motors. A large part of two power is utilized by motors 1000 HP or larger. The use of high-temperature superconducting materials with critical temperatures above that of liquid nitrogen (77 K) in the field winding would reduce the losses in these motors significantly, and therefore, would have a definite impact on the electrical power usage in the US. These motors will be 1/3 to 1/2 the size of conventional motors of similar power and, thus, offer potential savings in materials and floor space. The cooling of the superconducting materials in the field windings of the rotor presents a unique application of cryogenic engineering. The rotational velocity results in significant radial pressure gradients that affect the flow distribution of the cryogen. The internal pressure fields can result in significant nonuniformities in the two-phase flow of the coolant. Due to the variable speed design, the flow distribution has the potential to change during operation. A multiphase-flow computer model of the cryogenic cooling is developed to calculate the boiling heat transfer and phase distribution of the nitrogen coolant in the motor. The model accounts for unequal phase velocities and nonuniform cooling requirements of the rotor. The unequal radial pressure gradients in the inlet and outlet headers result in a larger driving force for flow in the outer cooling channels. The effect of this must be accounted for in the design of the motor. Continuing improvements of the model will allow the investigation of the transient thermal issues associated with localized quenching of the superconducting components of the motor.

  12. Flow and heat transfer model for a rotating cryogenic motor

    NASA Astrophysics Data System (ADS)

    Dykhuizen, R. C.; Baca, R. G.; Bickel, T. C.

    1993-08-01

    Development of a high-temperature, superconducting, synchronous motor for large applications (greater than 1000 HP) could offer significant electrical power savings for industrial users. Presently 60% of all electric power generated in the United States is converted by electric motors. A large part of this power is utilized by motors 1000 HP or larger. The use of high-temperature superconducting materials with critical temperatures above that of liquid nitrogen (77 K) in the field winding would reduce the losses in these motors significantly, and therefore, would have a definite impact on the electrical power usage in the U.S. These motors will be 1/3 to 1/2 the size of conventional motors of similar power and, thus, offer potential savings in materials and floor space. The cooling of the superconducting materials in the field windings of the rotor presents a unique application of cryogenic engineering. The rotational velocity results in significant radial pressure gradients that affect the flow distribution of the cryogen. The internal pressure fields can result in significant nonuniformities in the two-phase flow of the coolant. Due to the variable speed design, the flow distribution has the potential to change during operation. A multiphase-flow computer model of the cryogenic cooling is developed to calculate the boiling heat transfer and phase distribution of the nitrogen coolant in the motor. The model accounts for unequal phase velocities and nonuniform cooling requirements of the rotor. The unequal radial pressure gradients in the inlet and outlet headers result in a larger driving force for flow in the outer cooling channels. The effect of this must be accounted for in the design of the motor. Continuing improvements of the model will allow the investigation of the transient thermal issues associated with localized quenching of the superconducting components of the motor.

  13. Visualization techniques to experimentally model flow and heat transfer in turbine and aircraft flow passages

    NASA Technical Reports Server (NTRS)

    Russell, Louis M.; Hippensteele, Steven A.

    1991-01-01

    Increased attention to fuel economy and increased thrust requirements have increased the demand for higher aircraft gas turbine engine efficiency through the use of higher turbine inlet temperatures. These higher temperatures increase the importance of understanding the heat transfer patterns which occur throughout the turbine passages. It is often necessary to use a special coating or some form of cooling to maintain metal temperatures at a level which the metal can withstand for long periods of time. Effective cooling schemes can result in significant fuel savings through higher allowable turbine inlet temperatures and can increase engine life. Before proceeding with the development of any new turbine it is economically desirable to create both mathematical and experimental models to study and predict flow characteristics and temperature distributions. Some of the methods are described used to physically model heat transfer patterns, cooling schemes, and other complex flow patterns associated with turbine and aircraft passages.

  14. Energy flow in an arctic aquatic ecosystem

    SciTech Connect

    Schell, D.M.

    1993-01-01

    This project has been using natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. We are processing samples collected at the R4D intensive site over the past three years and are comparing these data with similar samples collected from the coastal plain. Our approach is to determine if carbon is accumulating in upland and coastal tundra; to determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers.

  15. Energy flow in an arctic aquatic ecosystem

    SciTech Connect

    Schell, D.M.

    1993-05-01

    This project has been using natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. We are processing samples collected at the R4D intensive site over the past three years and are comparing these data with similar samples collected from the coastal plain. Our approach is to determine if carbon is accumulating in upland and coastal tundra; to determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers.

  16. Modeling fluid flow and heat transfer at Basin and Range faults: preliminary results for Leach hot springs, Nevada

    USGS Publications Warehouse

    López, Dina L.; Smith, Leslie; Storey, Michael L.; Nielson, Dennis L.

    1994-01-01

    The hydrothermal systems of the Basin and Range Province are often located at or near major range bounding normal faults. The flow of fluid and energy at these faults is affected by the advective transfer of heat and fluid from an to the adjacent mountain ranges and valleys, This paper addresses the effect of the exchange of fluid and energy between the country rock, the valley fill sediments, and the fault zone, on the fluid and heat flow regimes at the fault plane. For comparative purposes, the conditions simulated are patterned on Leach Hot Springs in southern Grass Valley, Nevada. Our simulations indicated that convection can exist at the fault plane even when the fault is exchanging significant heat and fluid with the surrounding country rock and valley fill sediments. The temperature at the base of the fault decreased with increasing permeability of the country rock. Higher groundwater discharge from the fault and lower temperatures at the base of the fault are favored by high country rock permabilities and fault transmissivities. Preliminary results suggest that basal temperatures and flow rates for Leach Hot Springs can not be simulated with a fault 3 km deep and an average regional heat flow of 150 mW/m2 because the basal temperature and mass discharge rates are too low. A fault permeable to greater depths or a higher regional heat flow may be indicated for these springs.

  17. A note on drillhole depths required for reliable heat flow determinations

    USGS Publications Warehouse

    Chapman, D.S.; Howell, J.; Sass, J.H.

    1984-01-01

    In general, there is a limiting depth in a drillhole above which the reliability of a single determination of heat flow decreases rapidly with decreasing depth and below which the statistical uncertainty of a heat flow determination does not change perceptibly with increasing depth. This feature has been established empirically for a test case comprising a group of twelve heat flow sites in the Republic of Zambia. The technique consists of constructing heat flow versus depth curves for individual sites by progressively discarding data from the lower part of the hole and recomputing heat flow from the remaining data. For the Zambian test case, the curves converge towards a uniform value of 67 ?? 3 mW m-2 when all available data are used, but values of heat flow calculated for shallow(< 100 m) parts of the same holes range from 45 to 95 mW m-2. The heat flow versus depth curves are enclosed by a perturbation envelope which has an amplitude of 40 mW m-2 at the surface and decreases linearly to the noise level at 190 m. For the test region of Zambia a depth of 170 m is needed to guarantee a heat flow measurement within ?? 10% of the background regional value. It is reasonable to expect that this depth will be shallower in some regions and deeper in others. Features of heat flow perturbation envelopes can be used as quantitative reliability indices for heat flow studies. ?? 1984.

  18. Nonequilibrium gaseous heat transfer in pressure-driven plane Poiseuille flow.

    PubMed

    John, Benzi; Gu, Xiao-Jun; Emerson, David R

    2013-07-01

    Nonequilibrium heat and mass transfer in a pressure-driven plane Poiseuille flow is investigated using the direct simulation Monte Carlo method from the early slip to the free molecular regime. Our investigations reveal several nonintuitive, nonequilibrium thermal flow patterns, including expansion cooling near the walls, a nonconstant pressure profile, and counter-gradient heat transfer along the channel center-line. A bimodal trend in the tangential heat flux is found in the slip and the early transition regime. In the upper transition and free molecular regime, the net heat flow in the entire channel is largely unidirectional and in the opposite direction of mass flow. However, in the slip and the early transition regime, a two-way heat flow is observed in the channel as the normal heat flux profile plays a key role in determining the net gaseous heat flow direction. Moreover, the heat flow rate profile exhibits a maximum value at an intermediate value of Knudsen number. The effects of incomplete surface accommodation on nonequilibrium heat flow are also investigated in this work. It is shown that for very low values of the accommodation coefficient, the gaseous heat flow direction is reversed and is consistently in the direction of mass flow.

  19. Study of thermal energy storage using fluidized bed heat exchangers

    NASA Technical Reports Server (NTRS)

    Weast, T. E.; Shannon, L. J.; Ananth, K. P.

    1980-01-01

    The technical and economic feasibility of fluid bed heat exchangers (FBHX) for thermal energy storage (TES) in waste heat recovery applications is assessed by analysis of two selected conceptual systems, the rotary cement kiln and the electric arc furnace. It is shown that the inclusion of TES in the energy recovery system requires that the difference in off-peak and on-peak energy rates be large enough so that the value of the recovered energy exceeds the value of the stored energy by a wide enough margin to offset parasitic power and thermal losses. Escalation of on-peak energy rates due to fuel shortages could make the FBHX/TES applications economically attractive in the future.

  20. Heat Exchange Between a Liquid Flowing in a Tube and an External Flow Around it with Intense Stirring

    NASA Astrophysics Data System (ADS)

    Moshinskii, A. I.

    2014-11-01

    A mathematical model of heat exchange between a tube (a coil) with a liquid flowing inside it and an external flow around it is considered. Limiting equations of the process with intense stirring are derived. Some solutions of the proposed equations are obtained that can be used in modeling the processes occurring in heat exchangers.

  1. Laminar and turbulent incompressible fluid flow analysis with heat transfer by the finite element method

    SciTech Connect

    Cochran, R.J.

    1992-01-01

    A study of the finite element method applied to two-dimensional incompressible fluid flow analysis with heat transfer is performed using a mixed Galerkin finite element method with the primitive variable form of the model equations. Four biquadratic, quadrilateral elements are compared in this study--the serendipity biquadratic element with bilinear continuous pressure interpolation (Q2(8)-Q1) and the Lagrangian biquadratic element with bilinear continuous pressure interpolation (Q2-Q1) of the Taylor-Hood form. A modified form of the Q2-Q1 element is also studied. The pressure interpolation is augmented by a discontinuous constant shape function for pressure (Q2-Q1+). The discontinuous pressure element formulation makes use of biquadratic shape functions and a discontinuous linear interpolation of the pressure (Q2-P1(3)). Laminar flow solutions, with heat transfer, are compared to analytical and computational benchmarks for flat channel, backward-facing step and buoyancy driven flow in a square cavity. It is shown that the discontinuous pressure elements provide superior solution characteristics over the continuous pressure elements. Highly accurate heat transfer solutions are obtained and the Q2-P1(3) element is chosen for extension to turbulent flow simulations. Turbulent flow solutions are presented for both low turbulence Reynolds number and high Reynolds number formulations of two-equation turbulence models. The following three forms of the length scale transport equation are studied; the turbulence energy dissipation rate ([var epsilon]), the turbulence frequency ([omega]) and the turbulence time scale (tau). It is shown that the low turbulence Reynolds number model consisting of the K - [tau] transport equations, coupled with the damping functions of Shih and Hsu, provides an optimal combination of numerical stability and solution accuracy for the flat channel flow.

  2. Heat flow, deep formation temperature and thermal structure of the Tarim Basin, northwest China

    NASA Astrophysics Data System (ADS)

    Liu, Shaowen; Lei, Xiao; Feng, Changge; Li, Xianglan

    2016-04-01

    depth are the favorable conditions for hydrocarbon generation and preservation. As far as heat budget of the Tarim Basin is concerned, the radiogenic heat from the sedimentary cover accounts only for 20 percent of the surface heat flow (~9 mW/m2), while the mantle heat flow is estimated to be low as 6~15 mW/m2; this indicates the dominant contribution of crustal radiogenic heat to the observed heat flow. Any variations in surface heat flow for the Tarim Basin can be due only to changes in crustal heat production. Thermal contrast between the Tarim Basin and Tibet Plateau, represented by a difference in surface heat flow and deep crustal temperature, is remarkable. This inherited thermal contrast can be traced as far as before the India-Asia collision. Moreover, the lithosphere beneath the Tarim Basin is sufficiently strong to resist the gravitational potential energy difference and tectonic forces from Tibet. The observed thermal and rheological contrast accounts for the differential Cenozoic deformation in the Tarim Basin and adjacent areas.

  3. Flow visualization study of inverted annular flow of post dryout heat transfer region. [PWR; BWR

    SciTech Connect

    Ishii, M.; De Jarlais, G.

    1985-01-01

    The inverted annular flow is important in the area of LWR accident analysis in terms of the maximum cladding temperature and effectiveness of the emergency core cooling. However, the inverted annular flow thermal-hydraulics is not well understood due to its special heat transfer condition of film boiling. The review of existing data indicates further research is needed in the areas of basic hydrodynamics related to liquid core disintegration mechanisms, slug and droplet formation, entrainment, and droplet size distributions. In view of this, the inverted flow is studied in detail experimentally. A new experimental apparatus has been constructed in which film boiling heat transfer can be established in a transparent test section. The test section consists of two coaxial quartz tubes. The annular gap between these two tubes is filled with a hot, clear fluid (syltherm 800) so as to maintain film boiling temperatures and heat transfer rates at the inner quartz tube wall. Data on liquid core stability, core break-up mechanism, and dispersed-core liquid slug and droplet sizes are obtained using F 113 as a test fluid. Both high speed movies and flash photographs (3 ..mu..sec) are used.

  4. LRO Diviner Radiometer and the Apollo 15 Heat Flow Experiment

    NASA Astrophysics Data System (ADS)

    Siegler, M. A.; Keihm, S. J.; Paige, D. A.; Vasavada, A. R.; Ghent, R. R.; Bandfield, J. L.; Snook, K.

    2009-12-01

    A synergistic relationship has grown out of incoming data from the Diviner infrared radiometer aboard LRO, and measurements from the Apollo 15 and 17 heat flow experiments. Here we look at the 3.5 year surface and subsurface temperatures from the Apollo 15 mission as both a calibration point for Diviner and as a guide for extending surface thermal properties models into the subsurface. Whereas Diviner’s strength is in global surface properties, the Apollo 15 data (from NSSDC: PSPG-00752) recorded subsurface temperatures within the top 2 meters of the regolith. The goal is to use an Apollo-based conductivity and density model as a base for global lunar regolith conditions. A model confirmed both with surface and subsurface temperatures from Apollo 15 will be a reliable calibration point for Diviner. Thermal variations at other locations can be fixed to specific changes in the local subsurface regolith structure and associated thermal properties. Here we examine the current radiometric surface temperatures at the Apollo 15 landing site derived from Diviner data, then apply our thermal model to USGS topography data sets (10m and 50m resolution; Rosiek, 2009) to correlate measured temperatures with near surface thermal properties. This same model will be illuminated using ephemeris conditions appropriate to the 1971-74 Apollo 15 heat flow experiment. Beginning with previously published thermal property models (Vasavada et al 1999, Keihm and Langseth 1975, Langseth and Keihm 1976, Keihm 1984), we will model the regolith and thermal probe to recreate seasonal, diurnal and other transient thermal behavior measured by the Apollo heat flow experiment. This model should allow for more confidence in using surface temperatures measured by Diviner to infer regolith structure at depth. Ray tracing thermal models developed for Diviner can include effects of topography and orbital cycles that have led some to challenge the validity of conclusions drawn from the Apollo data sets

  5. Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

    NASA Astrophysics Data System (ADS)

    Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

    2016-06-01

    In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

  6. Heat storage in forest biomass improves energy balance closure

    NASA Astrophysics Data System (ADS)

    Lindroth, A.; Mölder, M.; Lagergren, F.

    2010-01-01

    Temperature measurements in trunks and branches in a mature ca. 100 years-old mixed pine and spruce forest in central Sweden were used to estimate the heat storage in the tree biomass. The estimated heat flux in the sample trees and data on biomass distributions were used to scale up to stand level biomass heat fluxes. The rate of change of sensible and latent heat storage in the air layer below the level of the flux measurements was estimated from air temperature and humidity profile measurements and soil heat flux was estimated from heat flux plates and soil temperature measurements. The fluxes of sensible and latent heat from the forest were measured with an eddy covariance system in a tower. The analysis was made for a two-month period in summer of 1995. The tree biomass heat flux was the largest of the estimated storage components and varied between 40 and -35 W m-2 on summer days with nice weather. Averaged over two months the diurnal maximum of total heat storage was 45 W m-2 and the minimum was -35 W m-2. The soil heat flux and the sensible heat storage in air were out of phase with the biomass flux and they reached maximum values that were about 75% of the maximum of the tree biomass heat storage. The energy balance closure improved significantly when the total heat storage was added to the turbulent fluxes. The slope of a regression line with sum of fluxes and storage as independent and net radiation as dependent variable, increased from 0.86 to 0.95 for half-hourly data and the scatter was also reduced. The most significant finding was, however, that during nights with strongly stable conditions when the sensible heat flux dropped to nearly zero, the total storage matched the net radiation very well. Another interesting result was that the mean energy imbalance started to increase when the Richardson number became more negative than ca. -0.1. In fact, the largest energy deficit occurred at maximum instability. Our conclusion is that eddy covariance

  7. Energy flow in an arctic aquatic ecosystem

    SciTech Connect

    Schell, D.M.

    1988-01-01

    Natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. Our overall goals are to a determine if carbon is accumulating in upland and coastal tundra; determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers. Past work on fishes, birds, and the prey species of insects and aquatic crustaceans has shown that peat carbon is very important in the energy supply supporting the food webs over the course of the year. Obligate freshwater fishes from the coastal lakes and Colville River have been shown to contain up to 60 percent peat carbon at the end of the winter season. In contrast, migratory shorebirds and passerines contained much smaller radiocarbon abundances in summer, indicating a major shift to recent in situ primary production in pond and stream ecosystems in summer months. For the past two years, we have narrowed our focus to the processes supplying carbon to the beaded stream system at MS-117 and have concentrated on determining the transfer and accumulation rates of carbon in the watershed.

  8. Energy flow in an arctic aquatic ecosystem

    SciTech Connect

    Schell, D.M.

    1988-12-31

    Natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. Our overall goals are to a determine if carbon is accumulating in upland and coastal tundra; determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers. Past work on fishes, birds, and the prey species of insects and aquatic crustaceans has shown that peat carbon is very important in the energy supply supporting the food webs over the course of the year. Obligate freshwater fishes from the coastal lakes and Colville River have been shown to contain up to 60 percent peat carbon at the end of the winter season. In contrast, migratory shorebirds and passerines contained much smaller radiocarbon abundances in summer, indicating a major shift to recent in situ primary production in pond and stream ecosystems in summer months. For the past two years, we have narrowed our focus to the processes supplying carbon to the beaded stream system at MS-117 and have concentrated on determining the transfer and accumulation rates of carbon in the watershed.

  9. Energy Flow: Flow Charts Illustrating United States Energy Resources and Usage, from Lawrence Livermore National Laboratory

    DOE Data Explorer

    Decision makers have long recognized the importance of visualizing energy and material flows in a way that distinguishes between resources, transformations and services. Research priorities can be defined in terms of changes to the flows, and the consequences of policy or technology shifts can be traced both upstream and downstream. The usefulness of this top-down view is limited by the level of detail that can be conveyed in a single image. We use two techniques to balance information content with readability. First we employe visualization techniques, such as those embodied in the energy Sankey diagram below (Figure 1), to display both qualitative (relative line weight) and quantitative (listed values) information in a reader-friendly package. The second method is to augment static images with dynamic, scalable digital content containing multiple layers (e.g. energy, carbon and economic data). This transitions the audience from that of a passive reader to an active user of the information. When used in conjunction these approaches enable relatively large, interconnected processes to be described and analyzed efficiently. [copied from the description at http://en.openei.org/wiki/LLNL_Energy_Flow_Charts#cite_note-1

  10. Gas Flow, Particle Acceleration, and Heat Transfer in Cold Spray: A review

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Meyer, Morten; Li, Wenya; Liao, Hanlin; Lupoi, Rocco

    2016-06-01

    Cold spraying is increasingly attracting attentions from both scientific and industrial communities due to its unique `low-temperature' coating build-up process and its potential applications in the additive manufacturing across a variety of industries. The existing studies mainly focused on the following subjects: particle acceleration and heating, coating build-up, coating formation mechanism, coating properties, and coating applications, among which particle acceleration and heating can be regarded as the premise of the other subjects because it directly determines whether particles have sufficient energy to deposit and form the coating. Investigations on particle acceleration and heating behavior in cold spraying have been widely conducted both numerically and experimentally over decades, where many valuable conclusions were drawn. However, existing literature on this topic is vast; a systematical summery and review work is still lack so far. Besides, some curtail issues involved in modeling and experiments are still not quite clear, which needs to be further clarified. Hence, a comprehensive summary and review of the literature are very necessary. In this paper, the gas flow, particle acceleration, and heat transfer behavior in the cold spray process are systematically reviewed. Firstly, a brief introduction is given to introduce the early analytical models for predicting the gas flow and particle velocity in cold spraying. Subsequently, special attention is directed towards the application of computational fluid dynamics technique for cold spray modeling. Finally, the experimental observations and measurements in cold spraying are summarized.

  11. Diabatic heating fields and the generation of available potential energy during FGGE

    NASA Technical Reports Server (NTRS)

    Salstein, David A.; Rosen, Richard D.; Baker, Wayman E.; Kalnay, Eugenia

    1986-01-01

    Global diabatic heating is estimated using fields of directly computed heating components, in particular those due to shortwave radiation, longwave radiation, sensible heating, and latent heating produced every 6 hours. The role of average fields of diabatic heating in the generation of available potential energy is examined. It is observed that latent heating is most significant in generating available potential energy.

  12. Thermionic Power Cell To Harness Heat Energies for Geothermal Applications

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Mojarradi, Mohammad; Greer, Harold F.

    2011-01-01

    A unit thermionic power cell (TPC) concept has been developed that converts natural heat found in high-temperature environments (460 to 700 C) into electrical power for in situ instruments and electronics. Thermionic emission of electrons occurs when an emitter filament is heated to gwhite hot h temperatures (>1,000 C) allowing electrons to overcome the potential barrier and emit into the vacuum. These electrons are then collected by an anode, and transported to the external circuit for energy storage.

  13. Decomposition of radiation energy into work and heat

    NASA Astrophysics Data System (ADS)

    Yuge, Tatsuro; Yamaguchi, Makoto; Ogawa, Tetsuo

    2017-02-01

    We investigate energy transfer by the radiation from a cavity quantum electrodynamics system in the context of quantum thermodynamics. We propose a method of decomposing it into work and heat within the framework of quantum master equations. We find that the work and heat correspond, respectively, to the coherent and incoherent parts of the radiation. In the derivation of the method, it is crucial to investigate the dynamics of the system that receives the radiation from the cavity.

  14. Heat transfer and energy analysis of a solar air collector with smooth plate

    NASA Astrophysics Data System (ADS)

    Chabane, Foued; Moummi, Noureddine

    2014-04-01

    The heat transfer and thermal performance of a single pass solar air heater a smooth plate was investigated experimentally. In the present paper, energy and heat transfer analysis of a solar air collector with smooth plate, this technique is used to determine the optimal thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different mass flow rate varying in the array 0.0108-0.0202 kg/s with five values, solar intensity; tilt angle and ambient temperature. We discuss the thermal behavior of this type of collector with new design and with my proper construction. An experimental study was carried out on a prototype installed on the experimental tests platform within the University of Biskra in the Algeria. The effects of air mass flow rate, emissivity of channel plates and wind heat transfer coefficient on the accuracy of the criterion are also investigated.

  15. Observation of Ion Cyclotron Heating in a Fast-flowing Plasma for an Advanced Plasma Thruster

    NASA Astrophysics Data System (ADS)

    Ando, Akira; Hatanaka, Motoi; Shibata, Masaki; Tobari, Hiroyuki; Hattori, Kunihiko; Inutake, Masaaki

    2004-11-01

    In the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) project in NASA, the combined system of the ion cyclotron heating and the magnetic nozzle is proposed to control a ratio of specific impulse to thrust at constant power. In order to establish the advanced plasma thruster, experiments of an ion heating and plasma acceleration by a magnetic nozzle are performed in a fast-flowing plasma in the HITOP device. A fast-flowing He plasma is produced by Magneto-Plasma-Dynamic Arcjet (MPDA) operated with an externally-applied magnetic field up to 1kG. RF waves with an ion cyclotron range of frequency (f=20-300kHz) is excited by a helically-wound antenna located downstream of the MPDA. Increases of an ion temperature and plasma stored energy measured by a diamagnetic coil clearly observed during the RF pulse. The heating efficiency is compared for various magnetic field configurations and strengths. There appears no indication of cyclotron resonance in a high density plasma where the ratio of ion cyclotron frequency to ion-ion collision one is below unity, because an ion-ion collisional effect is dominant. When the density becomes low and the ratio of ion cyclotron frequency to ion-ion collision one becomes high, features of ion cyclotron resonance are clearly appeared. The optimum magnetic field strength for the ion heating is slightly lower than that of the cyclotron resonance, which is caused by the Doppler effect due to the fast-flowing plasma. An ion energy distribution function is measured at a magnetic nozzle region by an electrostatic analyzer and increase of the parallel velocity is also observed.

  16. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Knowles, G. R.; Mathur, A. K.; Budimir, J.

    1979-01-01

    Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out.

  17. ELECTRON HEATING BY THE ION CYCLOTRON INSTABILITY IN COLLISIONLESS ACCRETION FLOWS. II. ELECTRON HEATING EFFICIENCY AS A FUNCTION OF FLOW CONDITIONS

    SciTech Connect

    Sironi, Lorenzo

    2015-02-20

    In the innermost regions of low-luminosity accretion flows, including Sgr A* at the center of our Galaxy, the frequency of Coulomb collisions is so low that the plasma has two temperatures, with the ions substantially hotter than the electrons. This paradigm assumes that Coulomb collisions are the only channel for transferring the ion energy to the electrons. In this work, the second of a series, we assess the efficiency of electron heating by ion velocity-space instabilities in collisionless accretion flows. The instabilities are seeded by the pressure anisotropy induced by magnetic field amplification, coupled to the adiabatic invariance of the particle magnetic moments. Using two-dimensional particle-in-cell (PIC) simulations, we showed in Paper I that if the electron-to-ion temperature ratio is T {sub 0e}/T {sub 0i} ≲ 0.2, the ion cyclotron instability is the dominant mode for ion betas β{sub 0i} ∼ 5-30 (here, β{sub 0i} is the ratio of ion thermal pressure to magnetic pressure), as appropriate for the midplane of low-luminosity accretion flows. In this work, we employ analytical theory and one-dimensional PIC simulations (with the box aligned with the fastest-growing wave vector of the ion cyclotron mode) to fully characterize how the electron heating efficiency during the growth of the ion cyclotron instability depends on the electron-to-proton temperature ratio, the plasma beta, the Alfvén speed, the amplification rate of the mean field (in units of the ion Larmor frequency), and the proton-to-electron mass ratio. Our findings can be incorporated as a physically grounded subgrid model into global fluid simulations of low-luminosity accretion flows, thus helping to assess the validity of the two-temperature assumption.

  18. Long-Term Global Heating From Energy Usage

    NASA Astrophysics Data System (ADS)

    Chaisson, Eric J.

    2008-07-01

    Even if civilization on Earth stops polluting the biosphere with greenhouse gases, humanity could eventually be awash in too much heat, namely, the dissipated heat by-product generated by any nonrenewable energy source. Apart from the Sun's natural aging-which causes an approximately 1% luminosity rise for each 108 years and thus about 1°C increase in Earth's surface temperature-well within 1000 years our technological society could find itself up against a fundamental limit to growth: an unavoidable global heating of roughly 3°C dictated solely by the second law of thermodynamics, a biogeophysical effect often ignored when estimating future planetary warming scenarios.

  19. Dimensional Analysis of Ocean Thermal Energy Conversion Heat Exchangers

    DTIC Science & Technology

    1977-06-30

    8217thIJt4IiTY CLASSIFICATION OF TWI4S PAG(E ona Dola t ern.r) 20. (continued) c-a• of factors having significance in OTEC (Ocean Thermal Energy Conversion...heat exchangers. Certain of these groups are then evaluated for a model and prototype OTEC -Type heat exchanger using the same working fluid and ex...Development Administration, and the U. S. Navy are brought out. Chapter II investigates the scaling problems of heat ex- changers in OTEC (Ocean Thermal

  20. Experimental study of laminar flow forced-convection heat transfer in air flowing through offset plates heated by radiation heat flux

    SciTech Connect

    Ali, A.H.H.; Kishinami, Koki; Hanaoka, Yutaka; Suzuki, Jun

    1998-04-01

    An experimental study of the steady state laminar flow forced-convection heat transfer of air flowing through offset plates located between two parallel plates and heated by radiation heat flux was carried out. The ranges of parameters tested were incident radiation heat fluxes of 500, 700, and 1,000 W/m{sup 2}. With Re ranging from 650 to 2,560, the inlet air bulk temperatures changed from 18.2 to 70 C and the tilting angle of the unit with the horizontal ranged from 0 to 90{degree} respectively. The results show that the rate of the increase in the local Nusselt number was observed to be proportional with Re up to 1,900, while it became less sensitive over Re range of 1,900--2,500. Also, in this range of Re, with the inlet air temperature of 20 C, the angle of inclination of the unit has no effect on the local Nusselt number. Increasing the incident radiation heat flux in the case of higher values of Re leads to a slight decrease in the value of the local Nusselt number. The effect of the inlet air bulk temperature on the forced-convection heat transfer coefficient shows, in the case of the horizontal position, an increase in the inlet air bulk temperature leads to slight decreases in the value of the average Nusselt number, while it leads to significant decreases in the value of the average Nusselt number as the tilting angle increases up to the vertical position. This effect is clearer in the case of Re = 650 rather than Re = 2,550. This work has application to solar collectors.

  1. Energy flows in rock mass under tidal deformation

    NASA Astrophysics Data System (ADS)

    Klishin, SV; Revuzhenko, AF

    2017-02-01

    Under analysis is the stress state of an elliptical domain under varying loading conditions. The energy flow lines are plotted. The paper demonstrates the effect of the boundary conditions on the shape of the flow lines.

  2. Experimental investigation on the heat transfer characteristics and flow pattern in vertical narrow channels heated from one side

    NASA Astrophysics Data System (ADS)

    Huang, Lihao; Li, Gang; Tao, Leren

    2016-07-01

    Experimental investigation for the flow boiling of water in a vertical rectangular channel was conducted to reveal the boiling heat transfer mechanism and flow patterns map aspects. The onset of nucleate boiling went upward with the increasing of the working fluid mass flow rate or the decreasing of the inlet working fluid temperature. As the vapour quality was increased, the local heat transfer coefficient increased first, then decreased, followed by various flow patterns. The test data from other researchers had a similar pattern transition for the bubble-slug flow and the slug-annular flow. Flow pattern transition model analysis was performed to make the comparison with current test data. The slug-annular and churn-annular transition models showed a close trend with current data except that the vapor phase superficial velocity of flow pattern transition was much higher than that of experimental data.

  3. Free Magnetic Energy and Coronal Heating

    NASA Technical Reports Server (NTRS)

    Winebarger, Amy; Moore, Ron; Falconer, David

    2012-01-01

    Previous work has shown that the coronal X-ray luminosity of an active region increases roughly in direct proportion to the total photospheric flux of the active region's magnetic field (Fisher et al. 1998). It is also observed, however, that the coronal luminosity of active regions of nearly the same flux content can differ by an order of magnitude. In this presentation, we analyze 10 active regions with roughly the same total magnetic flux. We first determine several coronal properties, such as X-ray luminosity (calculated using Hinode XRT), peak temperature (calculated using Hinode EIS), and total Fe XVIII emission (calculated using SDO AIA). We present the dependence of these properties on a proxy of the free magnetic energy of the active region

  4. Applications of thermal energy storage to waste heat recovery in the food processing industry

    NASA Astrophysics Data System (ADS)

    Trebilcox, G. J.; Lundberg, W. L.

    1981-03-01

    The canning segment of the food processing industry is a major energy user within that industry. Most of its energy demand is met by hot water and steam and those fluids, in addition to product cooling water, eventually flow from the processes as warm waste water. To minimize the possibility of product contamination, a large percentage of that waste water is sent directly to factory drains and sewer systems without being recycled and in many cases the thermal energy contained by the waste streams also goes unreclaimed and is lost from further use. Waste heat recovery in canning facilities can be performed economically using systems that employ thermal energy storage (TES). A project was proposed in which a demonstration waste heat recovery system, including a TES feature, would be designed, installed and operated.

  5. A CFD technique to investigate the chocked flow and heat transfer characteristic in a micro-channel heat sink

    NASA Astrophysics Data System (ADS)

    Azari, Ahmad; Bahraini, Abdorrasoul; Marhamati, Saeideh

    2015-04-01

    In this research, a Computational Fluid Dynamics (CFD) technique was used to investigate the effect of choking on the flow and heat transfer characteristics of a typical micro-channel heat sink. Numerical simulations have been carried out using Spalart-Allmaras model. Comparison of the numerical results for the heat transfer rate, mass flow rate and Stanton number with the experimental data were conducted. Relatively good agreement was achieved with maximum relative error 16%, and 8% for heat transfer and mass flow rate, respectively. Also, average relative error 9.2% was obtained for the Stanton number in comparison with the experimental values. Although, the results show that the majority of heat was transferred in the entrance region of the channel, but the heat transfer in micro-channels can also be affected by choking at channel exit. Moreover, the results clearly show that, the location where the flow is choked (at the vicinity of the channel exit) is especially important in determining the heat transfer phenomena. It was found that Spalart-Allmaras model is capable to capture the main features of the choked flow. Also, the effects of choking on the main characteristics of the flow was presented and discussed.

  6. Asymmetric energy flow in liquid alkylbenzenes: A computational study

    SciTech Connect

    Leitner, David M.; Pandey, Hari Datt

    2015-10-14

    Ultrafast IR-Raman experiments on substituted benzenes [B. C. Pein et al., J. Phys. Chem. B 117, 10898–10904 (2013)] reveal that energy can flow more efficiently in one direction along a molecule than in others. We carry out a computational study of energy flow in the three alkyl benzenes, toluene, isopropylbenzene, and t-butylbenzene, studied in these experiments, and find an asymmetry in the flow of vibrational energy between the two chemical groups of the molecule due to quantum mechanical vibrational relaxation bottlenecks, which give rise to a preferred direction of energy flow. We compare energy flow computed for all modes of the three alkylbenzenes over the relaxation time into the liquid with energy flow through the subset of modes monitored in the time-resolved Raman experiments and find qualitatively similar results when using the subset compared to all the modes.

  7. An Integrated Approach on Groundwater Flow and Heat/Solute Transport for Sustainable Groundwater Source Heat Pump (GWHP) System Operation

    NASA Astrophysics Data System (ADS)

    Park, D. K.; Bae, G. O.; Joun, W.; Park, B. H.; Park, J.; Park, I.; Lee, K. K.

    2015-12-01

    The GWHP system uses a stable temperature of groundwater for cooling and heating in buildings and thus has been known as one of the most energy-saving and cost-efficient renewable energy techniques. A GWHP facility was installed at an island located at the confluence of North Han and South Han rivers, Korea. Because of well-developed alluvium, the aquifer is suitable for application of this system, extracting and injecting a large amount of groundwater. However, the numerical experiments under various operational conditions showed that it could be vulnerable to thermal interference due to the highly permeable gravel layer, as a preferential path of thermal plume migration, and limited space for well installation. Thus, regional groundwater flow must be an important factor of consideration for the efficient operation under these conditions but was found to be not simple in this site. While the groundwater level in this site totally depends on the river stage control of Paldang dam, the direction and velocity of the regional groundwater flow, observed using the colloidal borescope, have been changed hour by hour with the combined flows of both the rivers. During the pumping and injection tests, the water discharges in Cheongpyeong dam affected their respective results. Moreover, the measured NO3-N concentrations might imply the effect of agricultural activities around the facility on the groundwater quality along the regional flow. It is obvious that the extraction and injection of groundwater during the facility operation will affect the fate of the agricultural contaminants. Particularly, the gravel layer must also be a main path for contaminant migration. The simulations for contaminant transport during the facility operation showed that the operation strategy for only thermal efficiency could be unsafe and unstable in respect of groundwater quality. All these results concluded that the integrated approach on groundwater flow and heat/solute transport is necessary

  8. Building heating and cooling applications thermal energy storage program overview

    NASA Technical Reports Server (NTRS)

    Eissenberg, D. M.

    1980-01-01

    Thermal energy storage technology and development of building heating and cooling applications in the residential and commercial sectors is outlined. Three elements are identified to undergo an applications assessment, technology development, and demonstration. Emphasis is given to utility load management thermal energy system application where the stress is on the 'customer side of the meter'. Thermal storage subsystems for space conditioning and conservation means of increased thermal mass within the building envelope and by means of low-grade waste heat recovery are covered.

  9. Thermal energy storage technologies for heating and cooling applications

    NASA Astrophysics Data System (ADS)

    Tomlinson, John J.

    1990-12-01

    Recent results from selected thermal energy storage (TES) research activities in Germany and Sweden are discussed. In addition, several new technologies for heating and cooling of buildings and automobiles were reviewed and found to benefit similar efforts in the United states. Details of a meeting with Didier-Werke AG, a leading German ceramics manufacturer who will provide TES media necessary for the United States to complete field tests of an advanced high temperature latent heat storage material, are presented. Finally, an overview of the December 1990 International Energy Agency (IEA) Executive Committee deliberations on TES is presented.

  10. An energy-efficient self-regulating heater for flow-through applications.

    PubMed

    Dasgupta, Purnendu K; Loree, Ellis L; Li, Jianzhong; Genfa, Zhang

    2003-08-01

    In many experiments, a flow-through heating arrangement is needed to reduce reaction time. Often the reaction conditions require inertness of the wetted material. Heated reactors based on polymeric tubing, notably PTFE, are the most common, and such reactors are typically used in a manner in which they are put in a heated bath or an otherwise thermally conductive potting in which a heater and a temperature sensor are embedded for heating and temperature control. Polymeric tubes are poor conductors of heat; as such, most reactors of this type have very poor energy utilization. We describe here heated flow-through reactors where a wire runs through the entire length of the tubular reactor and where the wire is directly electrically heated. The wire may or may not be electrically insulated. If the exterior of the tube is well insulated, the energy efficiency of such a reactor in heating the fluid of interest is nearly unity. This makes it most suitable for battery-powered applications. If an appropriate wire with a significant temperature coefficient of resistance is chosen, monitoring the current through the device at constant applied voltage indicates the effective mean temperature of the device and thus allows effective temperature control without an additional sensor/controller with essentially instantaneous response. Temperature control within +/- 0.4 degrees C at a mean temperature of 65 degrees C and within +/- 0.9 degrees C at 87 degrees C have been achieved.

  11. Near-Field Heat Flow Between Two Quantum Oscillators

    NASA Astrophysics Data System (ADS)

    Barton, Gabriel

    2016-12-01

    We calculate the exact steady-state heat flow P between two Ohmically damped quantum oscillators 1 and 2, with natural frequency ω 0, interacting through their near-field dipole-dipole potential V. To keep them at nominally constant temperatures T1, T2 respectively, they have to be coupled to thermostats functioning in a way one must specify explicitly unless one assumes local thermal equilibrium, which would, inadequately as a rule, restrict the calculation to leading order in V. Here the thermostats are modelled as stretched strings, one end attached to the oscillator, and the other to an infinitely distant device ensuring that the string carries thermal noise appropriate to T1 or T2 in addition to whatever motion is enforced by the oscillator. Aiming at insight rather than numerics, we focus mainly on simple approximations by powers of T1 and T2 for weak damping in the essentially quantum low-temperature regime where kBT_{1,2}≪ ω 0. From P it is easy to find the heat flux between two insulating Drude-modelled half-spaces.

  12. Heat transfer measurements on biconics at incidence in hypersonic high enthalpy air and nitrogen flows

    NASA Technical Reports Server (NTRS)

    Gai, S. L.; Cain, T.; Joe, W. S.; Sandeman, R. J.; Miller, C. G.

    1988-01-01

    Heat transfer rate measurements have been obtained at 0, 5, 15, and 21 deg angles-of-attack for a straight biconic scale model of an aeroassisted orbital vehicle proposed for planetary probe missions. Heat-transfer distributions were measured using palladium thin-film resistance gauges deposited on a glass-ceramic substrate. The windward heat transfer correlations were based on equilibrium flow in the shock layer of the model, although the flow may depart from equilibrium in the flow-field.

  13. Heat Transfer from Cylinders in Transition From Slip Flow to Free-Molecule Flow

    NASA Technical Reports Server (NTRS)

    Cybulski, Ronald J.; Baldwin, Lionel V.

    1959-01-01

    Over 600 measured heat-transfer coefficients in the transition from slip to free-molecule flow have been correlated by using the Nusselt number Nu as a function of the Knudsen Kn and Reynolds Re (or Mach M) numbers. The experimental range for these heat-transfer data from transverse cylinders in air corresponds to the following dimensionless groups: M, 0.10 to 0.90; Re, 0.03 to 11.5; Kn, 0.10 to 5.0. The total air temperature T(sub t) was maintained constant at 80 F, but wire temperature was Varied from 150 to 580 F. At Kn=0.10, Nu extrapolates smoothly into slip-flow empirical curves that show Nu as a function of Re and M or Kn. The correlation gradually changes from the square root of Re(sub t) dependence characteristic of continuum flow to first-power Re dependence as Kn increases (decreasing Re). At the experimental limit Kn ft 5.0, the Nu data correlate with a mean fractional error of 413 percent by the prediction of free-molecule-flow theory. In comparing experimental results with theory, an accommodation coefficient of 0.57+/-0.07 was inferred from the heat-transfer data, which were obtained with etched tungsten wire in air. The wire recovery temperature T(sub e) was measured and compared with existing data and theory in terms of a ratio eta(equivalent to T(sub e)/T(sub t). The results can be divided into three groups by Kn criteria: For Kn less than 2.01, eta is independent of Kn, and eta decreases from 1.0 to 0.97 as M increases from 0 to 0.90; for 2.0 less than Kn less than 5.0, eta is a function of both Kn and M in this transition region to fully developed free-molecule flow; and for Kn greater than 5.0, eta predicted by free-molecule-flow theory is observed and increases from 1.0 to 1.08 as M increases from 0 to 0.90, again independent of Kn. Therefore, these T(sub e) data provide a guide to the boundary of fully developed free-molecule flow, which is.inferred from this research to exist for Kn greater than 5.0. This boundary criterion is substantiated

  14. Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows

    NASA Astrophysics Data System (ADS)

    Liu, Caixi; Tang, Shuai; Shen, Lian; Dong, Yuhong

    2017-03-01

    The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in conjunction with heat transfer enhancement in particle-laden turbulent flows. The effects of particles on momentum and heat transfer are analyzed, and the possibility of drag reduction in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed. We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow, which shows the heat transfer reduction when large inertial particles with low specific heat capacity are added to the flow. However, we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved. The present results show that particles, which are active agents, interact not only with the velocity field, but also the temperature field and can cause a dissimilarity in momentum and heat transport. This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of particles with different thermal properties.

  15. Heat flow increase following the rise of mantle isotherms and crustal thinning

    NASA Technical Reports Server (NTRS)

    Mareschal, J. C.; Bergantz, G.

    1985-01-01

    Heat flow measurements in the western United States define a zone of high heat flow which coincides with the Basin and Range Province where extension has taken place recently. In this region, the average reduced heat flow is approx 30 mW sq. meters higher than in stable continental provinces; locally (e.g., Battle Mountain High), the heat flow anomaly can be more than 100 mW/sq meters above average. Estimates of the amount of extension range between 30% and 100% for the past 30 Ma. In the Colorado Plateau, which has been uplifted without major tectonic deformation, the heat flow is only slightly above average. Analytical calculations show that an abrupt change in heat flow at the base of the lithosphere 30 Ma ago would not affect the surface significantly. Uplift would proceed at a slow rate. A thermal perturbation at the base of a 40 km thick crust, however, would reach the surface faster and, after 30 Ma, the increase in surface heat flow would be about 75% of the amplitude of the heat flow anomaly. The number of volcanic rocks in the Basin and Range suggests that magma intrusions may provide an effective heat transfer mechanism. It can be show that if the source of the intrusions is at the base of the lithosphere, the response time will be much longer than 30 Ma, and most ot the heat transferred from the asthenosphere will be absorbed in the lithosphere.

  16. MHD stagnation point flow over a stretching cylinder with variable thermal conductivity and joule heating

    NASA Astrophysics Data System (ADS)

    Jahan, Shah; Sakidin, Hamzah; Nazar, Roslinda Mohd

    2016-11-01

    The behavior of magnetohydrodynamics (MHD) flow of viscous fluid near the stagnation point over a stretching cylinder with variable thermal conductivity is analyzed. Thermal conductivity is assumed to be linearly related with temperature. The joule heating effects due to magnetic field is also encountered here. Analytical solutions are developed for both momentum and energy equations by using the homotopy analysis method (HAM). The variations of different parameters on the velocity and temperature distributions along with the skin friction coefficient and local Nusselt number are displayed graphically. Numerical values for the skin friction coefficient are calculated and discussed

  17. Pulsatile flow with heat transfer of dusty magnetohydrodynamic Ree-Eyring fluid through a channel

    NASA Astrophysics Data System (ADS)

    Shawky, Hameda Mohammed

    2009-08-01

    The flow due to the pulsatile pressure gradient of dusty non-Newtonian fluid with heat transfer in a channel is considered. The system is stressed by an external magnetic field. The non-Newtonian fluid under consideration is obeying the rheological equation of state due to Ree-Eyring’s stress-strain relation. The equations of momentum and energy have been solved by using Lightill method. The velocity and temperature distributions of the two phase of the dusty fluid are obtained. The effects of various physical parameters of distributions the problem on these distributions are discussed and illustrated graphically through a set of figure.

  18. Three-dimensional flow of Powell-Eyring nanofluid with heat and mass flux boundary conditions

    NASA Astrophysics Data System (ADS)

    Tasawar, Hayat; Ikram, Ullah; Taseer, Muhammad; Ahmed, Alsaedi; Sabir, Ali Shehzad

    2016-07-01

    This article investigates the three-dimensional flow of Powell-Eyring nanofluid with thermophoresis and Brownian motion effects. The energy equation is considered in the presence of thermal radiation. The heat and mass flux conditions are taken into account. Mathematical formulation is carried out through the boundary layer approach. The governing partial differential equations are transformed into the nonlinear ordinary differential equations through suitable variables. The resulting nonlinear ordinary differential equations have been solved for the series solutions. Effects of emerging physical parameters on the temperature and nanoparticles concentration are plotted and discussed. Numerical values of local Nusselt and Sherwood numbers are computed and examined.

  19. Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

    SciTech Connect

    Reis, Chuck; Nelson, Eric; Armer, James; Johnson, Tim; Hirsch, Adam; Doebber, Ian

    2015-03-01

    The purpose of this playbook and accompanying spreadsheets is to generalize the detailed CBP analysis and to put tools in the hands of experienced refrigeration designers to evaluate multiple applications of refrigeration waste heat reclaim across the United States. Supermarkets with large portfolios of similar buildings can use these tools to assess the impact of large-scale implementation of heat reclaim systems. In addition, the playbook provides best practices for implementing heat reclaim systems to achieve the best long-term performance possible. It includes guidance on operations and maintenance as well as measurement and verification.

  20. Constraints on lithospheric thermal structure for the Indian Ocean from depth and heat flow data

    NASA Technical Reports Server (NTRS)

    Shoberg, Tom; Stein, Carol A.; Stein, Seth

    1993-01-01

    Models for the thermal evolution of oceanic lithosphere are primarily constrained by variations in seafloor depth and heat flow with age. These models have been largely based on data from the Pacific and Atlantic Ocean basins. We construct seafloor age relations for the Indian Ocean which we combine with bathymetric, sediment isopach and heat flow data to derive curves for depth and heat flow versus age. Comparison of these curves with predictions from three thermal models shows that they are better fit by the shallower depths and higher heat flow for the GDH1 model, which is characterized by a thinner and hotter lithosphere than previous models.