Sample records for scraped heat exchanger

  1. Scraped Surface Heat Exchangers

    Microsoft Academic Search

    Chetan S. Rao; Richard W. Hartel

    2006-01-01

    Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable

  2. Tempering of Chocolate in a Scraped Surface Heat Exchanger

    Microsoft Academic Search

    C. LOISEL; G. KELLER; G. LECQ; B. LAUNAY; M. OLLIVON

    1997-01-01

    Crystallization of dark chocolate during different tempering processes has been studied in-situ in a lab-scale Scraped Surface Heat Exchanger. The linear relationship between torque and viscosity made possible the control of chocolate crystallization during tempering by following torque variations vs. time and converting them to equivalent viscosity values. These variations of equivalent viscosity of chocolate observed during tempering were correlated

  3. Nest scrape design and clutch heat loss in Pectoral Sandpipers (Calidris melanotos)

    Microsoft Academic Search

    J. M. Reid; W. Cresswell; S. Holt; R. J. Mellanby; D. P. Whitfield; G. D. Ruxton

    2002-01-01

    Summary 1. The reasons why birds construct nest scrapes, and the extent to which scrape designs reflect functional optima, are poorly understood. Working on Pectoral Sandpipers (Calidris melanotos, Vieillot), we investigated whether scrapes function to insulate clutches and are efficiently designed to reduce heat loss rates. 2. Excavating a scrape and using lining material reduced the rate at which an

  4. Heat exchanger

    DOEpatents

    Brackenbury, P.J.

    1983-12-08

    A heat exchanger comparising a shell attached at its open end to one side of a tube sheet and a detachable head connected to the other side of said tube sheet. The head is divided into a first and second chamber in fluid communication with a nozzle inlet and nozzle outlet, respectively, formed in said tube sheet. A tube bundle is mounted within said shell and is provided with inlets and outlets formed in said tube sheet in communication with said first and second chambers, respectively.

  5. Microtube strip heat exchanger

    SciTech Connect

    Doty, F.D.

    1991-07-08

    During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchanger. DSI completed a heat exchanger stress analysis of the ten-module heat exchanger bank; and, performed a shell-side flow inhomogeneity analysis of the three-module heat exchanger bank. The company produced 50 tubestrips using an in-house CNC milling machine and began pressing them onto tube arrays. DSI revised some of the tooling required to encapsulate a tube array and press tubestrips into the array to improve some of the prototype tooling. 2 refs., 4 figs.

  6. Optimization of Heat Exchangers

    SciTech Connect

    Ivan Catton

    2010-10-01

    The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics )pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger disign.

  7. Nature's Heat Exchangers.

    ERIC Educational Resources Information Center

    Barnes, George

    1991-01-01

    Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)

  8. Active microchannel heat exchanger

    DOEpatents

    Tonkovich, Anna Lee Y. (Pasco, WA) [Pasco, WA; Roberts, Gary L. (West Richland, WA) [West Richland, WA; Call, Charles J. (Pasco, WA) [Pasco, WA; Wegeng, Robert S. (Richland, WA) [Richland, WA; Wang, Yong (Richland, WA) [Richland, WA

    2001-01-01

    The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction exhaust through the exhaust chamber and by conduction through a containment wall to the working fluid in the heat exchanger chamber thereby raising a temperature of the working fluid. The invention is particularly useful as a liquid fuel vaporizer and/or a steam generator for fuel cell power systems, and as a heat source for sustaining endothermic chemical reactions and initiating exothermic reactions.

  9. Thermoelectric heat exchange element

    DOEpatents

    Callas, James J. (Peoria, IL); Taher, Mahmoud A. (Peoria, IL)

    2007-08-14

    A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

  10. Vacuum powered heat exchanger

    SciTech Connect

    Ruffolo, R.F.

    1986-06-24

    In an internal combustion engine including an oil lubrication system, a liquid cooling system, and an improved air intake system is described. The improved air intake system comprises: a housing including a first opening in one end, which opening is open to the atmosphere and a second opening comprising an air outlet opening in the other end open to the air intake manifold of the engine, a heat exchanger positioned in the first opening. The heat exchanger consists of a series of coils positioned in the flow path of the atmospheric air as it enters the housing, the heat exchanger being fluidly connected to either the engine lubrication system or the cooling system to provide a warm heat source for the incoming air to the housing, acceleration means positioned in the housing downstream of the heat exchanger, the acceleration means comprising a honeycomb structure positioned across the air intake flow path. The honey-comb structure includes a multitude of honey combed mini-venturi cells through which the heated air flows in an accelerated mode, a removable air filter positioned between the heat exchanger and the acceleration means and a single opening provided in the housing through which the air filter can be passed and removed, and additional openings in the housing positioned downstream of the heat exchanger and upstream of the air filter, the additional openings including removable flaps for opening and closing the openings to control the temperature of the air flowing through the housing.

  11. Microtube strip heat exchanger

    NASA Astrophysics Data System (ADS)

    Doty, F. D.

    1990-12-01

    Doty Scientific (DSI) believes their microtube-strip heat exchanger will contribute significantly to the following: (1) the closed Brayton cycles being pursued at MIT, NASA, and elsewhere; (2) reverse Brayton cycle cryocoolers, currently being investigated by NASA for space missions, being applied to MRI superconducting magnets; and (3) high-efficiency cryogenic gas separation schemes for CO2 removal from exhaust stacks. The goal of this current study is to show the potential for substantial progress in high-effectiveness, low-cost, gas-to-gas heat exchangers for diverse applications at temperatures from below 100 K to above 1000 K. To date, the highest effectiveness measured is about 98 percent and relative pressure drops below 0.1 percent with a specific conductance of about 45 W/kgK are reported. During the pre-award period DSI built and tested a 3-module heat exchanger bank using 103-tube microtube strip (MTS) modules. To add to their analytical capabilities, DSI has acquired computational fluid dynamics (CFD) software. This report describes the pre-award work and the status of the ten tasks of the current project, which are: analyze flow distribution and thermal stresses within individual modules; design a heat exchanger bank of ten modules with 400 microtube per module; obtain production quality tubestrip die and AISI 304 tubestrips; obtain production quality microtubing; construct revised MTS heat exchanger; construct dies and fixtures for prototype heat exchanger; construct 100 MTS modules; assemble 8 to 10 prototype MTS heat exchangers; test prototype MTS heat exchanger; and verify test through independent means.

  12. Microtube Strip Heat Exchanger

    SciTech Connect

    Doty, F.D.

    1990-12-27

    Doty Scientific (DSI) believes their Microtube-Strip Heat Exchanger will contribute significantly to (a) the closed Brayton cycles being pursued at MIT, NASA, and elsewhere; (b) reverse Brayton cycle cryocoolers, currently being investigated by NASA for space missions, being applied to MRI superconducting magnets; and (c) high-efficiency cryogenic gas separation schemes for CO{sub 2} removal from exhaust stacks. The goal of this current study is to show the potential for substantial progress in high-effectiveness, low-cost, gas-to-gas heat exchangers for diverse applications at temperatures from below 100 K to above 1000 K. To date, the highest effectiveness measured is about 98%, and relative pressure drops below 0.1% with a specific conductance of about 45 W/kgK are reported. During the pre-award period DSI built and tested a 3-module heat exchanger bank using 103-tube microtube strip (MTS) modules. To add to their analytical capabilities, DSI has acquired computational fluid dynamics (CFD) software. This report describes the pre-award work and the status of the ten tasks of the current project, which are: analyze flow distribution and thermal stresses within individual modules; design a heat exchanger bank of ten modules with 400 microtube per module; obtain production quality tubestrip die and AISI 304 tubestrips; obtain production quality microtubing; construct revised MTS heat exchanger; construct dies and fixtures for prototype heat exchanger; construct 100 MTS modules; assemble 8-10 prototype MTS heat exchangers; test prototype MTS heat exchanger; and verify test through independent means. 7 refs., 9 figs. 1 tab. (CK)

  13. DHE (Downhole Heat Exchangers)

    Microsoft Academic Search

    G. Culver

    1990-01-01

    The use of downhole heat exchangers (DHE) for residential or commercial space and domestic water heating and other applications has several desirable features. Systems are nearly or completely passive -- that is, no or very little geothermal water or steam is produced from the well either reducing or completely eliminating surface environmental concerns and the need for disposal systems or

  14. Particle and heat balance analysis in scrape-off and divertor regions of the JFT-2M tokamak

    Microsoft Academic Search

    K. Nagashima; T. Shoji; H. Tamai; Y. Miura; H. Takenaga; H. Maeda

    1995-01-01

    Particle and heat balance in the scrape-off layer and the divertor region were studied in the JFT-2M tokamak. Using particle and energy conservation laws, particle and heat diffusivities perpendicular to the flux surface were evaluated just outside the magnetic separatrix. It was found that the particle diffusivity decreases with increasing electron density in the scrape-off layer and decreases by a

  15. Monogroove liquid heat exchanger

    NASA Technical Reports Server (NTRS)

    Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)

    1990-01-01

    A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).

  16. Chimney heat exchanger

    SciTech Connect

    Whiteley, I.C.

    1981-09-01

    A heat exchanger for installation on the top of a chimney of a building includes a housing having a lower end receiving the top of the chimney and an upper end with openings permitting the escape of effluent from the chimney and a heat exchanger assembly disposed in the housing including a central chamber and a spirally arranged duct network defining an effluent spiral path between the top of the chimney and the central chamber and a fresh air spiral path between an inlet disposed at the lower end of the housing and the central chamber, the effluent and fresh air spiral paths being in heat exchange relationship such that air passing through the fresh air spiral path is heated by hot effluent gases passing upward through the chimney and the effluent spiral path for use in heating the building. A pollution trap can be disposed in the central chamber of the heat exchanger assembly for removing pollutants from the effluent, the pollution trap including a rotating cage carrying pumice stones for absorbing pollutants from the effluent with the surface of the pumice gradually ground off to reveal fresh stone as the cage rotates.

  17. Heat pipe heat exchanger design considerations

    Microsoft Academic Search

    K. T. Feldman; D. C. Lu

    1976-01-01

    Typical heat pipe heat exchangers (HPHX) are described, along with their advantages, uses, and some problems in HPHX design, and a computer HPHX analysis program is discussed with required input data. The computer program is being developed for analysis of heat exchange performance by finned-tube HPHX and thread-puddle-artery heat pipes. Copper-water heat pipes and carbon steel-Dowtherm A heat pipes are

  18. Lightweight Long Life Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Moore, E. K.

    1976-01-01

    A shuttle orbiter flight configuration aluminum heat exchanger was designed, fabricated, and tested. The heat exchanger utilized aluminum clad titanium composite parting sheets for protection against parting sheet pin hole corrosion. The heat exchanger, which is fully interchangeable with the shuttle condensing heat exchanger, includes slurpers (a means for removing condensed water from the downstream face of the heat exchanger), and both the core air passes and slurpers were hydrophilic coated to enhance wettability. The test program included performance tests which demonstrated the adequacy of the design and confirmed the predicted weight savings.

  19. Optimization of Heat Exchanger Cleaning 

    E-print Network

    Siegell, J. H.

    1986-01-01

    The performance of heat integration systems is quantified in terms of the amount of heat that is recovered. This decreases with time due to increased fouling of the heat exchange surface. Using the "Total Fouling Related Expenses (TFRE)" approach...

  20. The liquid droplet heat exchanger

    Microsoft Academic Search

    A. P. Bruckner

    1982-01-01

    Direct contact heat exchange between a gas and a molten metal dispersed into droplets offers an attractive new approach to increasing the efficiency and decreasing the specific weight of thermal power cycles for space applications. The ability of a droplet heat exchanger to transfer heat directly from a liquid metal to a working gas over a wide temperature range circumvents

  1. Heat exchange system for recycling waste heat

    Microsoft Academic Search

    A. A. Giuffre; A. F. Giuffre

    1982-01-01

    Design of heat exchange system for recycling waste heat, such as that leaving a building stack or flue, to supply heat where needed, such as to incoming fresh air or to tempered stored water of the building water storage system, wherein the building has a source of heat at a constant temperature (such as a furnace, a cooking facility, or

  2. Gyrokinetic Magnetic Fluctuations in an ELM Heat Pulse Scrape-Off-Layer Test Problem

    NASA Astrophysics Data System (ADS)

    Hammett, G. W.; Hakim, A. H.; Shi, E. L.; Abel, I. G.; Stoltzfus-Dueck, T.

    2014-10-01

    We have applied an electromagnetic gyrokinetic-based model to simulate parallel plasma transport in the scrape-off layer (SOL) to a divertor plate, employing the Discontinuous-Galerkin code Gkeyll. We focus on a test problem that has been studied previously, using parameters chosen to approximate a heat pulse driven by an edge localized mode (ELM) in JET. With the use of the gyrokinetic quasineutrality equation and logical sheath boundary conditions, spatial and temporal resolution requirements are no longer set by the electron Debye length and plasma frequency. This test problem also helps illustrate some of the physics contained in the Hamiltonian form of the gyrokinetic equations and some of the numerical challenges in developing an edge gyrokinetic code. In particular, we will describe some of the special techniques needed to handle magnetic fluctuations in this nonlinear gyrokinetic problem. Supported by DOE Contract DE-AC02-09CH11466.

  3. Plate heat exchanger design theory

    Microsoft Academic Search

    R. K. Shah; A. S. Wanniarachchi

    1991-01-01

    Plate heat exchangers are commonly used in hygienic applications as well as in chemical processing and other industrial applications. Pertinent information on plate exchangers from a designer's point of view is summarized to provide a basic insight into performance behavior of chevron plates. Basic design methods are presented and a method of coupling between heat transfer and pressure drop is

  4. High Temperature Heat Exchanger Project

    SciTech Connect

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  5. Ceramic heat pipe heat exchangers

    Microsoft Academic Search

    W. A. Ranken

    1976-01-01

    High-temperature strength, resistance to corrosive atmospheres, and moderate cost combine to make ceramic materials an obvious choice for construction of high-temperature thermal energy recuperator systems. Despite these advantages, ceramic recuperators are steadily being replaced by metallic units at considerable sacrifice in maximum air or fuel preheat temperatures and hence in recovery efficiency. By constructing a recuperator from ceramic heat pipes,

  6. Dual mode heat exchanger

    NASA Astrophysics Data System (ADS)

    Altoz, F. E.

    1985-12-01

    The invention comprises a compact, light weight, dual mode heat transfer device. The dual mode heat transfer device provides for air cooling of heat dissipating electronic components at moderate aircraft speeds and when available ambient air is below a preselected temperature. At elevated aircraft speeds when the ambient air temperature is above the preselected temperature a coolant liquid is converted to steam or vapor in order to cool the heat dissipating electronic components. A preferred embodiment of the invention includes a cold plate for conducting heat away from the heat dissipating components and radiator fins for dissipating cold plate heat to a air cooling flow.

  7. DHE (downhole heat exchangers). [Downhole Heat Exchangers (DHE)

    Microsoft Academic Search

    Culver

    1990-01-01

    The use of downhole heat exchangers (DHE) for residential or commercial space and domestic water heating and other applications has several desirable features. Systems are nearly or completely passive -- that is, no or very little geothermal water or steam is produced from the well either reducing or completely eliminating surface environmental concerns and the need for disposal systems or

  8. The heat pipe heat exchangers: Design, technology and applications

    Microsoft Academic Search

    S. Chadourne

    1991-01-01

    The Heat Pipe Heat Exchanger (HPHE) is a relatively new and very attractice heat exchanger type. For a good understanding of this very special heat exchanger, a minimum knowledge of the heat pipes is required. The heat pipe and thermosyphon basic theory (including the calculation of the thermal limits) is summarized. Some information concerning the heat pipe technological aspects is

  9. Improve heat exchanger leak detection

    SciTech Connect

    Pugh, T. (Amoco Production Co., Houston, TX (United States)); York, B.; Laxton, G.; Simpson, G.D. (Unichem International, Inc., The Woodlands, TX (United States))

    1993-11-01

    A quick and easy method identifies exchangers that leak hydrocarbons into cooling water. A portable, explosion-proof flame ionization detector (FID) measures volatile hydrocarbons off-gassing from an exchanger's cooling water. Now, a hydrocarbon processing industry (HPI) facility can perform a leak detection survey on heat exchangers on a routine schedule. Suspected leakers are identified earlier than with conventional leak-detection methods such as chlorine consumption and cooling water turbidity. Greater sensitivity to hydrocarbons enables a facility to be proactive -- not reactive -- on exchanger maintenance.

  10. Microchannel heat exchanger optimization

    Microsoft Academic Search

    G. M. Harpole; J. E. Eninger

    1991-01-01

    A complete two-dimensional flow\\/thermal model of the micro-channel cooler is developed. Optimization of the design parameters with this model is demonstrated for the case of a 1 kW\\/cm2 heat flux with the top surface at 25°C. For this case, pure water could be used as the coolant, or 92% water\\/8% methanol (-5°C freezing point) if the heat is to be

  11. Waste heat recovery using heat pipe heat exchanger for heating automobile using exhaust gas

    Microsoft Academic Search

    Feng Yang; Xiugan Yuan; Guiping Lin

    2003-01-01

    The feasibility of using heat pipe heat exchangers for heating applying automotive exhaust gas is studied and the calculation method is developed. Practical heat pipe heat exchanger is set up for heating HS663, a large bus. Simple experiments are carried out to examine the performance of the heat exchanger. It is shown that the experimental results, which indicate the benefit

  12. Reduced model simulations of the scrape-off-layer heat-flux width and comparison with experiment

    DOE PAGESBeta

    Myra, J. R.; Russell, D. A.; D'Ippolito, D. A.; Ahn, J- W; Maingi, R.; Maqueda, R. J.; Lundberg, D. P.; Stotler, D. P.; Zweben, S. J.; Boedo, J.; et al

    2011-01-10

    Reduced model simulations of turbulence in the edge and scrape-off-layer (SOL) region of a spherical torus or tokamak plasma are employed to address the physics of the scrape-off-layer heat flux width. The simulation model is an electrostatic two-dimensional fluid turbulence model, applied in the plane perpendicular to the magnetic field at the outboard midplane of the torus. The model contains curvature-driven-interchange modes, sheath losses, and both perpendicular turbulent diffusive and convective (blob) transport. These transport processes compete with classical parallel transport to set the SOL width. Midplane SOL profiles of density, temperature and parallel heat flux are obtained from themore »simulation and compared with experimental results from the National Spherical Torus Experiment (NSTX) [S. M. Kaye, et al., Phys. Plasmas 8, 1977 (2001)] to study the scaling of the heat flux width with power and plasma current. It is concluded that midplane turbulence is the main contributor to the SOL heat flux width for the low power H-mode discharges studied, while additional physics is required to explain the plasma current scaling of the SOL heat flux width observed experimentally in higher power discharges. Intermittent separatrix spanning convective cells are found to be the main mechanism that sets the near-SOL width in the simulations. The roles of sheared flows and blob trapping vs. emission are discussed.« less

  13. Acceptance criteria for heat exchanger head staybolts

    Microsoft Academic Search

    R. L. Sindelar; P. S. Lam; D. M. Barnes; A. Placr; J. M. Morrison

    1991-01-01

    Each of the six primary coolant loop systems of the Savannah River Site production reactors contains two parallel single-pass heat exchangers to transfer heat from the primary coolant (DâO) to the secondary cooling water (HâO). The configuration of the heat exchangers includes a plenary space defined by the heat exchanger tubesheet and the heat exchanger head at both the heat

  14. Heat exchanger demonstration expert system

    NASA Astrophysics Data System (ADS)

    Bagby, D. G.; Cormier, R. A.

    1988-05-01

    A real-time expert system intended for detecting and diagnosing faults in a 20 kW microwave transmitter heat exchanger is described. The expert system was developed on a LISP machine, Incorporated (LMI), Lambda Plus computer using Process Intelligent Control (PICON) software. The Heat Exhanger Expert System was tested and debugged. Future applications and extensions of the expert system to transmitters, masers, and antenna subassemblies are discussed.

  15. Optimum design of double pipe heat exchanger

    Microsoft Academic Search

    Prabhata K. Swamee; Nitin Aggarwal; Vijay Aggarwal

    2008-01-01

    Heat exchangers are used in industrial processes to recover heat between two process fluids. Although the necessary equations for heat transfer and the pressure drop in a double pipe heat exchanger are available, using these equations the optimization of the system cost is laborious. In this paper the optimal design of the exchanger has been formulated as a geometric programming

  16. Lightweight long life heat exchanger

    NASA Technical Reports Server (NTRS)

    Moore, E. K.

    1975-01-01

    The design, fabrication, and evaluation of a full scale shuttle-type condensing heat exchanger constructed of aluminum and utilizing aluminum clad titanium parting sheets is described. A long term salt spray test of candidate parting sheet specimens is described. The results of an investigation into an alternate method of making composite sheet material are discussed.

  17. Geothermal direct contact heat exchange

    Microsoft Academic Search

    A. V. Sims

    1977-01-01

    A glass direct contact heat exchange column was operated in the laboratory. The column was operated at atmospheric pressure using hot water and normal hexane. Column internals testing included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1 C for

  18. Extended area ceramic heat exchanger

    Microsoft Academic Search

    R. A. Clyde

    1978-01-01

    A ceramic sponge heat exchanger with an extended area can now be made. It consists of a ceramic with random holes, holding rods of silicon carbide. The method of manufacture results in the SiC being held firmly so the brittleness factor is overcome. The ceramic will withstand high temperatures and can be coated with metals. It can be used in

  19. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J. (inventor); Blosser, Max L. (inventor); Camarda, Charles J. (inventor)

    1992-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators, or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  20. EXPERIMENTAL COMPARISON OF FOUR BOREHOLE HEAT EXCHANGERS

    Microsoft Academic Search

    J. ACUÑA; B. PALM

    2008-01-01

    The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a closed U-pipe loop in a vertical borehole. This fluid transports the heat from the rock to the ground source heat pump evaporator. The quality of the heat exchange with the ground and the necessary pumping power to

  1. Second Law Optimization of Heat Exchangers 

    E-print Network

    Witte, L. C.

    1985-01-01

    A new method for optimizing heat exchangers is developed in this paper. It is based on second law efficiency relationships rather than on the traditional heat exchanger effectiveness concept. The cost of energy is based on its availability level...

  2. Heat exchangers: Selection, rating, and thermal design

    SciTech Connect

    Kakac, S.; Liu, H.

    1998-01-01

    This book takes a systematic approach to the subject, focusing on the selection, design, rating, and operational challenges of various types of heat exchangers. Written by well-known authors in the field of heat transfer, this book covers all the most commonly used types of heat exchangers, including condensers and evaporators. The text begins with the classification of the different types of heat exchangers and discusses methods for their sizing and rating. Single phase forced convection correlations in ducts and pressure drop and pumping power analysis are also covered. A chapter is devoted to the special problem of fouling. Thermal design methods and processes, including designs for condensers and evaporators, complete this thorough introduction to the subject. The appendix provides information on the thermophysical properties of fluids, including the new refrigerants. Every topic features worked examples to illustrate the methods and procedures presented, and additional problems are included at the end of each chapter, with examples to be used as a student design project. An instructor's manual is available, including complete solutions to selected problems in the text. The contents include: classification of heat exchangers; basic design methods of heat exchangers; forced convection correlations for single-phase side of heat exchangers; heat exchanger pressure drop and pumping power; fouling of heat exchangers; double-pipe heat exchangers; design correlations for condensers and evaporators; shell-and-tube heat exchangers; compact heat exchangers; gasketed-plate heat exchangers; and condensers and evaporators.

  3. Pressurized bellows flat contact heat exchanger interface

    NASA Technical Reports Server (NTRS)

    Voss, Fred E. (inventor); Howell, Harold R. (inventor); Winkler, Roger V. (inventor)

    1990-01-01

    Disclosed is an interdigitated plate-type heat exchanger interface. The interface includes a modular interconnect to thermally connect a pair or pairs of plate-type heat exchangers to a second single or multiple plate-type heat exchanger. The modular interconnect comprises a series of parallel, plate-type heat exchangers arranged in pairs to form a slot therebetween. The plate-type heat exchangers of the second heat exchanger insert into the slots of the modular interconnect. Bellows are provided between the pairs of fins of the modular interconnect so that when the bellows are pressurized, they drive the plate-type heat exchangers of the modular interconnect toward one another, thus closing upon the second heat exchanger plates. Each end of the bellows has a part thereof a thin, membrane diaphragm which readily conforms to the contours of the heat exchanger plates of the modular interconnect when the bellows is pressurized. This ensures an even distribution of pressure on the heat exchangers of the modular interconnect thus creating substantially planar contact between the two heat exchangers. The effect of the interface of the present invention is to provide a dry connection between two heat exchangers whereby the rate of heat transfer can be varied by varying the pressure within the bellows.

  4. Towards a new generation heat exchanger models

    Microsoft Academic Search

    Geert W. Haarlemmer; Jérôme Pigourier

    2008-01-01

    In the quest for more dependable process models, attending to small detail and integrating increasing their internal complexity will improve dynamic behavior and simulation accuracy. Although detailed heat exchanger models in dedicated steady state design programs are common, steady state process models and dynamic simulations have been based largely on shorteut heat exchanger calculations. However, detailed heat exchanger models can

  5. 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…

  6. Analysis and application of the heat pipe heat exchanger

    Microsoft Academic Search

    T. H. Sun; R. C. Prager

    1978-01-01

    Heat pipe heat exchangers offer many advantages over more conventional heat exchangers, particularly for gas-to-gas application. Proper application of these devices depends on the conditions imposed by the process from which waste heat is to be recovered, and some of the more common constraints are analyzed. The overall operation of heat pipe heat exchangers is best studied using effectiveness-NTU calculations,

  7. DHE (downhole heat exchangers). [Downhole Heat Exchangers (DHE)

    SciTech Connect

    Culver, G.

    1990-11-01

    The use of downhole heat exchangers (DHE) for residential or commercial space and domestic water heating and other applications has several desirable features. Systems are nearly or completely passive -- that is, no or very little geothermal water or steam is produced from the well either reducing or completely eliminating surface environmental concerns and the need for disposal systems or injection wells. Initial cost of pumps and installation are eliminated or reduced along with pumping power costs and maintenance costs associated with pumping often corrosive geothermal fluids. Many residential and small commercial systems do not require circulating pumps because the density difference in the incoming and outgoing sides of the loop are sufficient to overcome circulating friction losses in the entire system. The major disadvantage of DHEs is their dependence on natural heat flow. In areas where geological conditions provide high permeability and a natural hydraulic gradient, DHEs can provide a substantial quantity of heat. A single 500-ft (152 m) well in Klamath Falls, Oregon, supplies over one megawatt thermal and output is apparently limited by the surface area of pipe that can be installed in the well bore. In contrast, DHEs used in conjunction with heat pumps may supply less than 8 KW from a well of similar depth. Here output is limited by conductive heat flow with perhaps a small contribution from convection near the well bore. The highest capacity DHE reported to date, in Turkey, supplies 6 MW thermal from an 820-ft (250 m) well. There were two main goals for this project. The first was to gather, disseminate and exchange internationally information on DHES. The second was to perform experiments that would provide insight into well bore/aquifer interaction and thereby provide more information on which to base DHE designs. 27 refs., 31 figs., 3 tabs.

  8. Improved Ceramic for Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Herbell, T. P.; Rauch, H. W.; Mccreeght, L. R.

    1982-01-01

    Most promising composition developed in investigation consisted of mixed oxides described generically as ZrMAS. Has been commercially designated as GE-7808. Material was obtained from low-cost clay/talc mixture. Overall assessment of ZrMAS indicates it is a viable candidate for heat-exchanger application in automotive gas-turbine engines and possibly other areas that require dielectric materials of moderate refractoriness, good corrosion resistance, and excellent thermal-shock resistance.

  9. Heat exchanger expert system logic

    NASA Technical Reports Server (NTRS)

    Cormier, R.

    1988-01-01

    The reduction is described of the operation and fault diagnostics of a Deep Space Network heat exchanger to a rule base by the application of propositional calculus to a set of logic statements. The value of this approach lies in the ease of converting the logic and subsequently implementing it on a computer as an expert system. The rule base was written in Process Intelligent Control software.

  10. Heat pipe heat exchangers as energy recovery devices

    Microsoft Academic Search

    Ruch

    1976-01-01

    Counterflow heat exchangers comprised of a bundle of heat pipes with secondary finned surfaces attached offer attractive advantages as energy recovery units. With no moving parts and wide design flexibility, these heat pipe heat exchangers are finding ever increasing usage in air-to-air heat recovery. Three general classes of applications can be identified: using energy recovery from process exhaust to regenerate

  11. IMPLEMENTING GROUND SOURCE HEAT PUMP AND GROUND LOOP HEAT EXCHANGER

    E-print Network

    IMPLEMENTING GROUND SOURCE HEAT PUMP AND GROUND LOOP HEAT EXCHANGER MODELS IN THE ENERGYPLUS #12;ii IMPLEMENTING GROUND SOURCE HEAT PUMP AND GROUND LOOP HEAT EXCHANGER MODELS IN THE ENERGYPLUS............................................................... 2 1.3. Overview of the Parameter Estimation Water-to-Water Heat Pump Model ........... 5 1

  12. Use of the exergy concept for design improvement of heat exchangers and heat exchanger networks

    Microsoft Academic Search

    Ranasinghe

    1989-01-01

    The second law of thermodynamics, through the exergy concept, allows us to quantify and rationally coat the consumption of exergy (irreversibility) used to drive the heat exchange process and the effluent losses of exergy in a heat exchanger. For systems with a network of heat exchangers, the exergy concept recognizes that properly integrated heat pumps reduce the heat transfer irreversibility;

  13. Heat exchanger for solar water heaters

    NASA Technical Reports Server (NTRS)

    Cash, M.; Krupnick, A. C.

    1977-01-01

    Proposed efficient double-walled heat exchanger prevents contamination of domestic water supply lines and indicates leakage automatically in solar as well as nonsolar heat sources using water as heat transfer medium.

  14. Heat-Exchanger Method of Crystal Growth

    NASA Technical Reports Server (NTRS)

    Khattak, C. P.; Schmid, F.

    1982-01-01

    Large crystals of silicon are grown from melt, in either vacuum or pressurized atmosphere, without moving crucible, furnace, or anything else. Seed crystal is mounted on helium-cooled heat exchanger, which prevents seed from melting when furnace melts rest of silicon material in crucible; heat exchanger draws off heat from melt so that a solid ingot grows outward from seed in a regular crystal structure. Bottom of crucible is insulated so that heat exchanger cools only seed.

  15. Heat transfer in SiC compact heat exchanger

    Microsoft Academic Search

    Y. Takeuchi; K. Noborio; Y. Yamamoto; S. Konishi

    2010-01-01

    For development of a compact SiC heat exchanger, numerical heat transfer analysis was conducted to investigate its performance for a wide range of thermal media, liquid LiPb and helium gas, flow rates. The numerical model used was based on the heat exchanger test module developed by the authors. Within the authors’ experimental range, the heat quantity transferred from high temperature

  16. FEM analysis of multifluid heat exchangers

    Microsoft Academic Search

    K. N. Seetharamu; G. A. Quadir; Z. A. Zainal; G. M. Krishnan

    2004-01-01

    Heat exchangers are devices for exchanging energy between two or more fluids. They find applications in various industries like power, process, electronics, refining, cryogenics, chemicals, metals and manufacturing sector. Even though heat exchanger designs have been reported quite extensively, they are generally limited to steady-state performance, single phase fluids, a few of the many possible flow arrangements and only two

  17. Mathematical simulation of heat exchanger working conditions

    NASA Astrophysics Data System (ADS)

    Gavlas, Stanislav; ?ur?anský, Peter; Lenhard, Richard; Janda?ka, Jozef

    2015-05-01

    One of the When designing a new heat exchanger it is necessary to consider all the conditions imposed on the exchanger and its desired properties. Most often the investigation of heat transfer is to find heat surface. When applying exchanger for proposed hot air engine, it will be a counter-flow heat exchanger of gas - gas type. Gas, which transfers the heat will be exhaust gas from the combustion of biomass. An important step in the design and verification is to analyze exchanger designed using numerical methods, the verification of the correctness of design and verification of boundary conditions which include temperatures, flow rates and pressure drops. Due to the fact that the heat transfer in the heat exchanger is a three-dimensional plot and timeindependent, the system is described by partial differential equations that need to be solved by numerical methods.

  18. Testing and analysis of immersed heat exchangers

    SciTech Connect

    Farrington, R.B.; Bingham, C.E.

    1986-08-01

    The objectives were to determine the performance of four immersed, ''supply-side'' heat exchangers used in solar domestic-hot-water systems; to examine the effects of flow rate, temperature difference, and coil configuration on performance; and to develop a simple model to predict the performance of immersed heat exchangers. We tested four immersed heat exchangers: a smooth coil, a finned spiral, a single-wall bayonet, and a double-wall bayonet. We developed two analyticl models and a simple finite difference model. We experimentally verified that the performance of these heat exchangers depends on the flow rate through them; we also showed that the temperature difference between the heat exchanger's inlet and the storage tank can strongly affect a heat exchanger's performance. We also compared the effects of the heat exchanger's configuration and correlated Nusselt and Rayleigh numbers for each heat exchanger tested. The smooth coil had a higher effectiveness than the others, while the double-wall bayonet had a very low effectiveness. We still do not know the long-term effectiveness of heat exchangers regarding scale accumulation, nor do we know the effects of very low flow rates on a heat exchanger's performance.

  19. PS1 satellite refrigerator heat exchanger: Failure of the LN2 heat exchanger to low pressure helium

    Microsoft Academic Search

    B. Squires

    1992-01-01

    The PS1 heat exchanger is one of three prototype heat exchangers built in support of a contract for Satellite Refrigerator Heat Exchanger components. This heat exchanger was first put into operation in Jul. 1983. In Nov. 1991, this heat exchanger experienced a failure in the shell of heat exchanger 1 causing nitrogen to contaminate the helium in the refrigerator. The

  20. Heat exchangers: Selection, rating, and thermal design

    Microsoft Academic Search

    S. Kakac; H. Liu

    1998-01-01

    This book takes a systematic approach to the subject, focusing on the selection, design, rating, and operational challenges of various types of heat exchangers. Written by well-known authors in the field of heat transfer, this book covers all the most commonly used types of heat exchangers, including condensers and evaporators. The text begins with the classification of the different types

  1. Thermal performances of heat exchangers applicable to waste-heat recovery systems

    Microsoft Academic Search

    Shou-Shing Hsieh; Chihng-Tsung Liauh; Wen-Sun Han

    1988-01-01

    Results are presented and discussed for the quantitative evaluation of the heat exchangers applied to waste-heat recovery systems for two types of conventional heat exchangers: compact cross-flow heat exchangers, and heat-pipe heat exchangers. The effects of the different alignments on the heat transfer rate of heat pipe heat exchangers are also studied.

  2. Scrape-off layer modeling of radiative divertor and high heat flux experiments on DIII-D

    NASA Astrophysics Data System (ADS)

    Campbell, R. B.; Petrie, T. W.; Hill, D. N.

    1992-12-01

    We use a new multispecies 1D fluid code, NEWT-ID, to model DIII-D scrape-off layer (SOL) behavior during radiative divertor and high heat flux experiments. The separatrix location and the width of the SOL are uncertain, and affect the comparison of the data in important ways. The model agrees with many of the experimental measurements for a particular prescription for the separatrix location. The model cannot explain the recent data on the separatrix Ti with a conventional picture of ion and electron power flows across the separatrix. Radial transport of particles and heat in some form is required to explain the peak heat flux data before and after gas puffing. For argon puffing in the private flux region, entrainment is poor in the steady state. The calculations suggest that strike point argon puffing in a slot divertor geometry results in substantially better entrainment. Self-consistent, steady-state solutions with radiated powers up to 80% of the SOL power input are obtained in 1D. We discuss significant radial effects which warrant the development of a code which can treat strongly radiating impurities in 2D geometries.

  3. Scrape-off layer modeling of radiative divertor and high heat flux experiments on D3-D

    NASA Astrophysics Data System (ADS)

    Campbell, R. B.; Petrie, T. W.; Hill, D. N.

    1992-03-01

    We use a new multispecies 1-D fluid code, NEWT-1D, to model DIII-D scrape-off layer (SOL) behavior during radiative divertor and high heat flux experiments. The separatrix location and the width of the SOL are uncertain, and affect the comparison of the data in important ways. The model agrees with many of the experimental measurements for a particular prescription for the separatrix location. The model cannot explain the recent data on the separatrix T(sub i) with a conventional picture of ion and electron power flows across the separatrix. Radial transport of particles and heat in some form is required to explain the peak heat flux data before and after gas puffing. For argon puffing in the private flux region, entrainment is poor in the steady state. The calculations suggest that strike point argon puffing in a slot divertor geometry results in substantially better entrainment. Self-consistent, steady-state solutions with radiated powers up to 80 percent of the SOL power input are obtained in 1-D. We discuss significant radial effects which warrant the development of a code which can treat strongly radiating impurities in 2-D geometries.

  4. Oxidizer heat exchanger component testing

    NASA Technical Reports Server (NTRS)

    Kmiec, T.; Kanic, P.

    1986-01-01

    As part of the RL10 Rocket Engine Product Improvement Program, Oxidizer Heat Exchanger (OHE) stages 1, 2, and 3 were designed and fabricated during late 1983 and early 1984. The purpose of the OHE is to provide gaseous oxygen to the propellant injector for stable engine operation at tank head idle and pumped idle operating modes. This report summarizes the OHE stages 1 and 3 rig testing, and includes the separation of the stage 1-and-2 assembly and the remanifolding of stage 1. The OHE performance analysis and analytical model modifications for both stages are also presented. The flow tests were accomplished during the time period from 9 October 1984 to 12 November 1984.

  5. Probe Measures Fouling As In Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Marner, Wilbur J.; Macdavid, Kenton S.

    1990-01-01

    Combustion deposits reduce transfer of heat. Instrument measures fouling like that on gas side of heat exchanger in direct-fired boiler or heat-recovery system. Heat-flux probe includes tube with embedded meter in outer shell. Combustion gases flow over probe, and fouling accumulates on it, just as fouling would on heat exchanger. Embedded heat-flow meter is sandwich structure in which thin Chromel layers and middle alloy form thermopile. Users determine when fouling approaches unacceptable levels so they schedule cleaning and avoid decreased transfer of heat and increased drop in pressure fouling causes. Avoids cost of premature, unnecessary maintenance.

  6. Fluid circulation system for heat exchangers

    Microsoft Academic Search

    Mangus

    1982-01-01

    A fluid circulation system for heat exchangers has two groups of tubes through which primary and secondary fluids flow, the tubes of one group being interdigitated with the tubes of the other group, and a heat transfer material interposed between the two groups of tubes, whereby heat is transferred from the primary fluid through the heat transfer material to the

  7. Stability analysis of heat exchanger dynamics

    Microsoft Academic Search

    Tiejun Zhang; John T. Wen; Juan Catano; Rongliang Zhou

    2009-01-01

    In the study of vapor compression cycle, momentum balance equation is often ignored in the heat exchanger model. In this paper, we investigate the effect of the momentum balance through a systematic study of the open loop stability of a heat exchanger. We consider 1-D fluid flow in a pipe in four cases of increasing complexity the most general case

  8. Modeling of Heat Transfer in Geothermal Heat Exchangers

    E-print Network

    Cui, P.; Man, Y.; Fang, Z.

    2006-01-01

    Ground-coupled heat pump (GCHP) systems have been gaining increasing popularity for space conditioning in residential and commercial buildings. The geothermal heat exchanger (GHE) is devised for extraction or injection of thermal energy from...

  9. Modeling of Heat Transfer in Geothermal Heat Exchangers 

    E-print Network

    Cui, P.; Man, Y.; Fang, Z.

    2006-01-01

    Ground-coupled heat pump (GCHP) systems have been gaining increasing popularity for space conditioning in residential and commercial buildings. The geothermal heat exchanger (GHE) is devised for extraction or injection of thermal energy from...

  10. Fuel delivery system including heat exchanger means

    NASA Technical Reports Server (NTRS)

    Coffinberry, G. A. (inventor)

    1978-01-01

    A fuel delivery system is presented wherein first and second heat exchanger means are each adapted to provide the transfer of heat between the fuel and a second fluid such as lubricating oil associated with the gas turbine engine. Valve means are included which are operative in a first mode to provide for flow of the second fluid through both first and second heat exchange means and further operative in a second mode for bypassing the second fluid around the second heat exchanger means.

  11. Heat exchanger device and method for heat removal or transfer

    DOEpatents

    Koplow, Jeffrey P

    2013-12-10

    Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

  12. Heat exchanger and method of making

    NASA Technical Reports Server (NTRS)

    Fortini, A.; Kazaroff, J. M. (inventors)

    1981-01-01

    A heat exchanger of increased effectiveness is disclosed. A porous metal matrix is disposed in a metal chamber or between walls through which a heat transfer fluid is directed. The porous metal matrix has internal bonds and is bonded to the chamber in order to remove all thermal contact resistance within the composite structure. Utilization of the invention in a rocket chamber is disclosed as a specific use. Also disclosed is a method of constructing the heat exchanger.

  13. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Exhaust heat exchangers. 25.1125 Section 25... Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  14. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Exhaust heat exchangers. 29.1125 Section 29... Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  15. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 true Heat exchange systems provisions. 63.1328...IV Polymers and Resins § 63.1328 Heat exchange systems provisions. ...subpart. (h) The compliance date for heat exchange systems subject to the...

  16. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Exhaust heat exchangers. 29.1125 Section 29... Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  17. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240 Section 870... § 870.4240 Cardiopulmonary bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of...

  18. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Heat exchange system requirements. 63.104...Chemical Manufacturing Industry § 63.104 Heat exchange system requirements. ...subject to this subpart shall monitor each heat exchange system used to cool...

  19. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Exhaust heat exchangers. 23.1125 Section 23... Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  20. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Exhaust heat exchangers. 25.1125 Section 25... Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  1. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Exhaust heat exchangers. 23.1125 Section 23... Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine...following apply: (a) Each exhaust heat exchanger must be constructed and...

  2. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240 Section 870... § 870.4240 Cardiopulmonary bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of...

  3. Heat exchanger, head and shell acceptance criteria

    SciTech Connect

    Lam, P.S.; Sindelar, R.L.

    1992-09-01

    Instability of postulated flaws in the head component of the heat exchanger could not produce a large break, equivalent to a DEGB in the PWS piping, due to the configuration of the head and restraint provided by the staybolts. Rather, leakage from throughwall flaws in the head would increase with flaw length with finite leakage areas that are bounded by a post-instability flaw configuration. Postulated flaws at instability in the shell of the heat exchanger or in the cooling water nozzles could produce a large break in the Cooling Water System (CWS) pressure boundary. An initial analysis of flaw stability for postulated flaws in the heat exchanger head was performed in January 1992. This present report updates that analysis and, additionally, provides acceptable flaw configurations to maintain defined structural or safety margins against flaw instability of the external pressure boundary components of the heat exchanger, namely the head, shell, and cooling water nozzles. Structural and flaw stability analyses of the heat exchanger tubes, the internal pressure boundary of the heat exchangers or interface boundary between the PWS and CWS, were previously completed in February 1992 as part of the heat exchanger restart evaluation and are not covered in this report.

  4. Brayton-cycle heat exchanger technology program

    Microsoft Academic Search

    J. J. Killackey; M. G. Coombs; R. F. Graves; C. J. Morse

    1976-01-01

    The following five tasks designed to advance this development of heat exchanger systems for close loop Brayton cycle power systems are presented: (1) heat transfer and pressure drop data for a finned tubular heat transfer matrix. The tubes are arranged in a triangular array with copper stainless steel laminate strips helically wound on the tubes to form a disk fin

  5. Analysis of a Flooded Heat Exchanger

    ERIC Educational Resources Information Center

    Fink, Aaron H.; Luyben, William L.

    2015-01-01

    Flooded heat exchangers are often used in industry to reduce the required heat-transfer area and the size of utility control valves. These units involve a condensing vapor on the hot side that accumulates as a liquid phase in the lower part of the vessel. The heat transfer occurs mostly in the vapor space, but the condensate becomes somewhat…

  6. Design study of plastic film heat exchanger

    NASA Astrophysics Data System (ADS)

    Guyer, E. C.; Brownell, D. L.

    1986-02-01

    This report presents the results of an effort to develop and design a unique thermoplastic film heat exchanger for use in an industrial heat pump evaporator system and other energy recovery applications. The concept for the exchanger is that of individual heat exchange elements formed by two adjoining and freely hanging plastic films. Liquid flows downward in a regulated fashion between the films due to the balance of hydrostatic and frictional forces. The fluid stream on the outside of film may be a free-falling liquid film, a condensing gas, or a noncondensing gas. The flow and structural principles are similar to those embodied in an earlier heat exchange system developed for use in waste water treatment systems (Sanderson). The design allows for high heat transfer rates while working within the thermal and structural limitations of thermoplastic materials. The potential of this new heat exchanger design lies in the relatively low cost of plastic film and the high inherent corrosion and fouling resistance. This report addresses the selection of materials, the potential heat transf er performance, the mechanical design and operation of a unit applied in a low pressure steam recovery system, and the expected selling price in comparison to conventional metallic shell and tube heat exchangers.

  7. Heat transfer coefficients of shell and coiled tube heat exchangers

    Microsoft Academic Search

    M. R. Salimpour

    2009-01-01

    In the present study, the heat transfer coefficients of shell and helically coiled tube heat exchangers were investigated experimentally. Three heat exchangers with different coil pitches were selected as test section for both parallel-flow and counter-flow configurations. All the required parameters like inlet and outlet temperatures of tube-side and shell-side fluids, flow rate of fluids, etc. were measured using appropriate

  8. SAFE Reactor Brayton Cycle Primary Heat Exchangers

    SciTech Connect

    Reid, Robert S.; Houts, Michael G. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)

    2002-07-01

    Gas cooling of power-dense nuclear reactor cores can produce large thermal and stress gradients through sensible temperature changes in the coolant. In-core heat pipes remove heat isothermally and reduce the severity of these gradients. The modular SAFE reactor concept consists of numerous heat pipes that permit core re-assembly during test and preflight integration. The redundancy inherent in the modular heat pipe-based design enhances reactor reliability. The SAFE reactor is designed to operate for extended periods near full power even if several fuel pins or modules fail. Los Alamos National Laboratory and Marshall Space Flight Center are jointly developing two modular heat pipe heat exchangers, collectively named FIGMENT (Fission Inert Gas Metal Exchanger for Non-nuclear Testing). The FIGMENT heat exchangers are designed to transfer power from the SAFE nuclear reactor cores to gas turbine energy converters. A stainless steel prototype heat exchanger will be built in preparation for the construction of a larger refractory metal version. Several promising FIGMENT stainless steel heat exchanger concepts are reviewed here. (authors)

  9. Waste heat recovery using heat pipe heat exchanger (HPHE) for surgery rooms in hospitals

    Microsoft Academic Search

    S. H. Noie-Baghban; G. R. Majideian

    2000-01-01

    Research has been carried out on the theory, design and construction of heat pipes, especially their use in heat pipe heat exchangers for energy recovery, reduction of air pollution and environmental conservation. A heat pipe heat exchanger has been designed and constructed for heat recovery in hospital and laboratories, where the air must be changed up to 40 times per

  10. Acceptance criteria for heat exchanger head staybolts

    SciTech Connect

    Sindelar, R.L.; Lam, P.S.; Barnes, D.M.; Placr, A.; Morrison, J.M.

    1991-12-31

    Each of the six primary coolant loop systems of the Savannah River Site production reactors contains two parallel single-pass heat exchangers to transfer heat from the primary coolant (D{sub 2}O) to the secondary cooling water (H{sub 2}O). The configuration of the heat exchangers includes a plenary space defined by the heat exchanger tubesheet and the heat exchanger head at both the heat exchanger inlet and outlet to the primary piping. The primary restraint of the heat exchanger head (Type 304 stainless steel) is provided by 84 staybolts (Type 303 stainless steel) which attach to the tubesheet. The staybolts were cap seal-welded in the mid-1960`s and are immersed in moderator. Access to inspect the staybolts is limited to a recently-developed ultrasonic technique shooting a beam through the staybolt assembly. Acceptance Criteria to allow disposition of flaws detected by UT inspection have been developed. The structural adequacy to protect against collapse loading of the head is demonstrated by finite element analysis of the head assembly and fracture analysis of flaw postulates in the staybolts. Both normal operation and normal operation plus seismic loading conditions were considered. Several bounding cases containing various configurations of nonactive (exceeding critical flaw size) staybolts were analyzed. The model of the head assembly can be applied to evaluate any active staybolt configurations based on the results from future inspections. 9 refs.

  11. Acceptance criteria for heat exchanger head staybolts

    SciTech Connect

    Sindelar, R.L.; Lam, P.S.; Barnes, D.M.; Placr, A.; Morrison, J.M.

    1991-01-01

    Each of the six primary coolant loop systems of the Savannah River Site production reactors contains two parallel single-pass heat exchangers to transfer heat from the primary coolant (D{sub 2}O) to the secondary cooling water (H{sub 2}O). The configuration of the heat exchangers includes a plenary space defined by the heat exchanger tubesheet and the heat exchanger head at both the heat exchanger inlet and outlet to the primary piping. The primary restraint of the heat exchanger head (Type 304 stainless steel) is provided by 84 staybolts (Type 303 stainless steel) which attach to the tubesheet. The staybolts were cap seal-welded in the mid-1960's and are immersed in moderator. Access to inspect the staybolts is limited to a recently-developed ultrasonic technique shooting a beam through the staybolt assembly. Acceptance Criteria to allow disposition of flaws detected by UT inspection have been developed. The structural adequacy to protect against collapse loading of the head is demonstrated by finite element analysis of the head assembly and fracture analysis of flaw postulates in the staybolts. Both normal operation and normal operation plus seismic loading conditions were considered. Several bounding cases containing various configurations of nonactive (exceeding critical flaw size) staybolts were analyzed. The model of the head assembly can be applied to evaluate any active staybolt configurations based on the results from future inspections. 9 refs.

  12. Design and fabrication of a cross flow micro heat exchanger

    Microsoft Academic Search

    Chad Harris; Mircea Despa; Kevin Kelly

    2000-01-01

    A cross flow micro heat exchanger was designed to maximize heat transfer from a liquid (water-glycol) to a gas (air) for a given frontal area while holding pressure drop across the heat exchanger of each fluid to values characteristic of conventional scale heat exchangers. The predicted performance for these plastic, ceramic, and aluminum micro heat exchangers are compared with each

  13. Fatigue Testing of Heat-Exchanger Tubes

    NASA Technical Reports Server (NTRS)

    Ackerman, P.

    1984-01-01

    Acclerated fatigue-life testing of heat-exchanger tubes simplified by technique that substitutes mechanical side load for thermally-generated axisymmetric stress. Load amplitudes adjusted to produce strains equivalent to those produced by anticipated thermal stress.

  14. Dealing with Uncertainties During Heat Exchanger Design

    E-print Network

    Polley, G. T.; Pugh, S. J.

    the specification of fouling resistance (the allowance made for the thermal resistance presented by dirt layers deposited on the heat exchanger tubes). In most instances there is little science or understanding behind the specification of these resistances...

  15. Condensing Heat Exchangers Optimize Steam Boilers 

    E-print Network

    Sullivan, B.; Sullivan, P. A.

    1983-01-01

    The development of fluorocarbon resin covered tubes has advanced to the point where full scale marketing in connection with condensing heat exchangers has begun. Field installations show simple paybacks of one to one and a half years with resulting...

  16. Foam Heat Exchangers: A Technology Assessment

    Microsoft Academic Search

    Arun Muley; Carl Kiser; Bengt Sundén; Ramesh K. Shah

    2012-01-01

    Open-cell porous metal foams have received attention for use in compact heat exchangers due to their increasing availability and improved thermal performance. In recent years, considerable research has been conducted on use of metallic and non-metallic foams to further improve performance of state-of-the-art heat exchangers. In this paper, we report preliminary results from fabrication development and experimental investigation of thermal-hydraulic

  17. Joule-Thomson expander and heat exchanger

    NASA Technical Reports Server (NTRS)

    Norman, R. H.

    1976-01-01

    The Joule-Thomson Expander and Heat Exchanger Program was initiated to develop an assembly (JTX) which consists of an inlet filter, counterflow heat exchanger, Joule-Thomson expansion device, and a low pressure jacket. The program objective was to develop a JTX which, when coupled to an open cycle supercritical helium refrigerating system (storage vessel), would supply superfluid helium (He II) at 2 K or less for cooling infrared detectors.

  18. Modelling and simulation of a heat exchanger

    NASA Technical Reports Server (NTRS)

    Xia, Lei; Deabreu-Garcia, J. Alex; Hartley, Tom T.

    1991-01-01

    Two models for two different control systems are developed for a parallel heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these to obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.

  19. Integrated Approach to Revamping Heat Exchangers Networks

    E-print Network

    Glass, K. E.; Dhole, V.; Wang, Y.

    geometry configurations for a given set of process conditions. Develop simulation model (in Aspen Plus) incorporating rigorous heat exchanger (Aspen Hetran) models for the 1) Validate existing preheat train performance & evaluate the existing and de...-bottlenecked cases de-bottlenecked performance Initiate pinch analysis (using Aspen Pinch) directly 2) Determine feasible energy saving from (Aspen Plus) simulation results Heat exchanger network pinch analysis (using Aspen Pinch) incorporating rigorous (Aspen...

  20. Brayton-cycle heat exchanger technology program

    NASA Technical Reports Server (NTRS)

    Killackey, J. J.; Coombs, M. G.; Graves, R. F.; Morse, C. J.

    1976-01-01

    The following five tasks designed to advance this development of heat exchanger systems for close loop Brayton cycle power systems are presented: (1) heat transfer and pressure drop data for a finned tubular heat transfer matrix. The tubes are arranged in a triangular array with copper stainless steel laminate strips helically wound on the tubes to form a disk fin geometry; (2) the development of a modularized waste heat exchanger. Means to provide verified double containment are described; (3) the design, fabrication, and test of compact plate fin heat exchangers representative of full scale Brayton cycle recuperators; (4) the analysis and design of bellows suitable for operation at 1600 F and 200 psia for 1,000 cycles and 50,000 hours creep life; and (5) screening tests used to select a low cost braze alloy with the desirable attributes of a gold base alloy. A total of 22 different alloys were investigated; the final selection was Nicrobraz 30.

  1. Finned-Tube Heat Exchanger Optimization Methodology

    Microsoft Academic Search

    Susan W. Stewart; Sam V. Shelton; Kristinn A. Aspelund

    2005-01-01

    Heat exchangers play a dominant role in the performance of most energy systems; however, optimization of these components is a complex task due to the coupled nature of the design parameters involved. Anytime the heat transfer coefficient is increased in these components, there is a corresponding increase in frictional pressure drop; therefore, a delicate balance is required between these two

  2. Microchannel Heat Exchangers with Carbon Dioxide

    Microsoft Academic Search

    Y. Zhao; M. M. Ohadi; R. Radermacher

    2001-01-01

    The objective of the present study was to determine the performance of COâ microchannel evaporators and gas coolers in operational conditions representing those of residential heat pumps. A set of breadboard prototype microchannel evaporators and gas coolers was developed and tested. The refrigerant in the heat exchangers followed a counter cross-flow path with respect to the airflow direction. The test

  3. Observer-based monitoring of heat exchangers.

    PubMed

    Astorga-Zaragoza, Carlos-Manuel; Alvarado-Martínez, Víctor-Manuel; Zavala-Río, Arturo; Méndez-Ocaña, Rafael-Maxim; Guerrero-Ramírez, Gerardo-Vicente

    2008-01-01

    The goal of this work is to provide a method for monitoring performance degradation in counter-flow double-pipe heat exchangers. The overall heat transfer coefficient is estimated by an adaptive observer and monitored in order to infer when the heat exchanger needs preventive or corrective maintenance. A simplified mathematical model is used to synthesize the adaptive observer and a more complex model is used for simulation. The reliability of the proposed method was demonstrated via numerical simulations and laboratory experiments with a bench-scale pilot plant. PMID:17706652

  4. Thermal\\/mechanical heat exchange design: Karl Gardner Memorial Session

    Microsoft Academic Search

    K. P. Singh; S. M. Shenkman

    1986-01-01

    This book presents the papers given at a conference on heat exchangers. Topics considered at the conference included uncertainty analysis of heat exchanger thermal-hydraulic designs, stress analysis, the mechanical design and fabrication of shell and tube heat exchangers in the US, and expert systems for design integration using an application to the total design of shell and tube heat exchangers

  5. Pressurized-Flat-Interface Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Voss, F. E.; Howell, H. R.; Winkler, R. V.

    1990-01-01

    High thermal conductance obtained without leakage between loops. Heat-exchanger interface enables efficient transfer of heat between two working fluids without allowing fluids to intermingle. Interface thin, flat, and easy to integrate into thermal system. Possible application in chemical or pharmaceutical manufacturing when even trace contamination of process stream with water or other coolant ruins product. Reduces costs when highly corrosive fluids must be cooled or heated.

  6. Heat exchanger with auxiliary cooling system

    DOEpatents

    Coleman, John H. (Salem Township, Westmoreland County, PA)

    1980-01-01

    A heat exchanger with an auxiliary cooling system capable of cooling a nuclear reactor should the normal cooling mechanism become inoperable. A cooling coil is disposed around vertical heat transfer tubes that carry secondary coolant therethrough and is located in a downward flow of primary coolant that passes in heat transfer relationship with both the cooling coil and the vertical heat transfer tubes. A third coolant is pumped through the cooling coil which absorbs heat from the primary coolant which increases the downward flow of the primary coolant thereby increasing the natural circulation of the primary coolant through the nuclear reactor.

  7. Vibration damping in multispan heat exchanger tubes

    SciTech Connect

    Taylor, C.E.; Pettigrew, M.J. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada). Chalk River Labs.; Dickinson, T.J.; Currie, I.G. [Univ. of Toronto, Ontario (Canada). Dept. of Mechanical Engineering; Vidalou, P. [National Conservatory of Arts and Trades, Paris (France)

    1998-08-01

    Heat exchanger tubes can be damaged or fail if subjected to excessive flow-induced vibration, either from fatigue or fretting-wear. Good heat exchanger design requires that the designer understands and accounts for the vibration mechanisms that might occur, such as vortex shedding, turbulent excitation or fluidelastic instability. To incorporate these phenomena into a flow-induced vibration analysis of a heat exchanger requires information about damping. Damping in multispan heat exchanger tubes largely consists of three components: viscous damping along the tube, and friction and squeeze-film damping at the supports. Unlike viscous damping, squeeze-film damping and friction damage are poorly understood and difficult to measure. In addition, the effect of temperature-dependent fluid viscosity on tube damping has not been verified. To investigate these problems, a single vertical heat exchanger tube with multiple spans was excited by random vibration. Tests were conducted in air and in water at three different temperatures (25, 60, and 90 C). At room temperature, tests were carried out at five different preloads. Frequency response spectra and resonant peak-fitted damping ratios were calculated for all tests. Energy dissipation rates at the supports and the rate of excitation energy input were also measured. Results indicate that damping does not change over the range of temperatures tested and friction damping is very dependent on preload.

  8. Heat Transfer Characteristics of a Generalized Divided Flow Heat Exchanger

    E-print Network

    Singh, K. P.

    1979-01-01

    The concept of a "Divided-flow" heat exchanger is generalized by locating the shell inlet (or outlet) nozzle off-center such that the two shell sub-streams are unequal and traverse unequal flow paths. The governing equations for heat transfer...

  9. Modular tube bundle heat exchanger and geothermal heat pump system

    SciTech Connect

    Galiyano, M.J.; Wiggs, B.R.; Aspacher, J.T.

    1993-07-06

    An improved ground source heat pump system is described, comprising: an in-ground heat exchanger and a building heat exchanger coupled via conduits for refrigerant to at least one compressor and at least one expander, the compressor having at least one intake line and at least one discharge line, the compressor and the expander being coupled to the conduits such that the refrigerant is circulated in the conduits through pressure changes and corresponding temperature changes in the refrigerant, the in-ground heat exchanger comprising at least one modular tube bundle comprising a plurality of substantially horizontally oriented subterranean tubes, buried in a substantially planar vertical array for installation along substantially vertical walls of at least one that is backfilled for setting the array in thermal engagement with the earth, said at least one bundle having a top and bottom displaced vertically from one another, and the refrigerant being subjected to phase change in the conduits.

  10. Heat exchanger for coal gasification process

    DOEpatents

    Blasiole, George A. (Greensburg, PA)

    1984-06-19

    This invention provides a heat exchanger, particularly useful for systems requiring cooling of hot particulate solids, such as the separated fines from the product gas of a carbonaceous material gasification system. The invention allows effective cooling of a hot particulate in a particle stream (made up of hot particulate and a gas), using gravity as the motive source of the hot particulate. In a preferred form, the invention substitutes a tube structure for the single wall tube of a heat exchanger. The tube structure comprises a tube with a core disposed within, forming a cavity between the tube and the core, and vanes in the cavity which form a flow path through which the hot particulate falls. The outside of the tube is in contact with the cooling fluid of the heat exchanger.

  11. Heat exchanger containing a component capable of discontinuous movement

    DOEpatents

    Wilson, David Gordon

    2001-04-17

    Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

  12. Heat exchanger containing a component capable of discontinuous movement

    DOEpatents

    Wilson, David Gordon (Winchester, MA)

    2002-01-01

    Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

  13. Carbon nanotube heat-exchange systems

    DOEpatents

    Hendricks, Terry Joseph (Arvada, CO); Heben, Michael J. (Denver, CO)

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  14. Hybrid cycle power plant with heat accumulator for storing heat exchange fluid transferring heat between cycles

    Microsoft Academic Search

    Pacault

    1976-01-01

    An installation for producing motive power, operating on a hybrid cycle of gas and vapor such as steam is described. The installation has a heat accumulator for storing a heat-exchange fluid which can also act as a fluid fuel for a heat source adapted to heat the fluid of the heat accumulator. Heat can be drawn from the accumulator in

  15. Comparative analysis of compact heat exchangers for application as the intermediate heat exchanger for advanced nuclear reactors

    DOE PAGESBeta

    Bartel, N.; Chen, M.; Utgikar, V. P.; Sun, X.; Kim, I. H.; Christensen, R.; Sabharwall, P.

    2015-07-01

    A comparative evaluation of alternative compact heat exchanger designs for use as the intermediate heat exchanger in advanced nuclear reactor systems is presented in this article. Candidate heat exchangers investigated included the Printed circuit heat exchanger (PCHE) and offset strip-fin heat exchanger (OSFHE). Both these heat exchangers offer high surface area to volume ratio (a measure of compactness [m2/m3]), high thermal effectiveness, and overall low pressure drop. Helium–helium heat exchanger designs for different heat exchanger types were developed for a 600 MW thermal advanced nuclear reactor. The wavy channel PCHE with a 15° pitch angle was found to offer optimummore »combination of heat transfer coefficient, compactness and pressure drop as compared to other alternatives. The principles of the comparative analysis presented here will be useful for heat exchanger evaluations in other applications as well.« less

  16. MGCR HEAT EXCHANGER TEST PROGRAM. Final Report

    Microsoft Academic Search

    Paulson; H. C. II

    1961-01-01

    The Maritime Gas-cooled Reactor (MGCR) project has conipleted the study ;\\u000a and design of a closed-cycle gasturbine propulsion plant utilizing a helium-;\\u000a cooled nuclear reactor as the heat source. The cycle employs a counterflow shell-;\\u000a and-tube regenerator to attain a high thermodynamic cycle efficiency. A heat ;\\u000a exchanger test program was conducted to compile and correlate sufficient ;\\u000a experimental data

  17. Heat exchanger saves $400,000 in waste heat recovery

    SciTech Connect

    Confer, L.; Kramer, K.L.

    1987-08-01

    A condensing type heat exchanger operating at Henkel Corporation's plant in Kankakee, IL, has enabled the plant to save $400,000 in energy costs within the first 22 months of operation, recouping the initial capital investment for the unit within that time frame. The heat exchanger enables the plant to accomplish what historically was considered taboo - to cool boiler stack gas down to 130/sup 0/F, below the dew point, and thus recover both sensible and latent heat from the gas. Traditionally, moisture could not be squeezed out of stack gas below the recommended temperature of 250/sup 0/F because the stack gas close to the heat exchanger tubes would approach the dew point, condense and attack metal surfaces. The condensing type heat exchanger can withstand corrosive conditions, however, because all wetted surfaces on the flue side of the shell and copper-nickel tube design are protected with an extruded Teflon fluorocarbon resin covering (not coating). The waste heat recovery system was installed over a two-month period in 1985. Performance has been above expectations with greater energy savings than originally projected. The amount of operator attention required is minimal.

  18. Compact heat exchangers - History, technological advancement and mechanical design problems

    Microsoft Academic Search

    R. K. Shah; C. F. McDonald; C. P. Howard

    1980-01-01

    A history of compact heat exchangers is presented, along with recent advances in Japan, other developments in the field, and a review of boiling, condensing, and other aspects of two-phase flow in plate-fin heat exchangers. Specific attention is devoted to prediction of heat and water vapor exchanger performance, wound parallel plate exchangers for air-conditioning applications, a new plate heat exchanger

  19. Foundation Heat Exchanger Model and Design Tool Development and Validation

    E-print Network

    . Feasibility of foundation heat exchangers in ground source heat pump systems in the United States. ASHRAE Heat Exchangers for Residential Ground Source Heat Pump Systems - Numerical Modeling and Experimental. Fisher, J. Shonder, P. Im. 2010. Residential Ground Source Heat Pump Systems Utilizing Foundation Heat

  20. Effectiveness enchancement of heat exchanger by using nanofluids

    Microsoft Academic Search

    M. Hasanuzzamana; R. Saidur; N. A. Rahim

    2011-01-01

    Heat exchanger is the almost common equipment for the industrial process heating. Heat is transferred from one fluid to other fluids by convection and conduction through the wall of the heat exchanger. Effectiveness of heat exchanger depends on the convection heat transfer coefficient of the fluid. Convective heat transfer coefficient of water, Cu-water, AI-water, Al203-water and Ti02-water of 2% nanoparticle

  1. The role of parallel heat transport in the relation between upstream scrape-off layer widths and target heat flux width in H-mode plasmas of NSTX.

    SciTech Connect

    Ahn, J W; Boedo, J A; Maingi, R; Soukhanovskii, V A

    2009-01-05

    The physics of parallel heat transport was tested in the Scrape-off Layer (SOL) plasma of the National Spherical Torus Experiment (NSTX) [M. Ono, et al., Nucl. Fusion 40, 557 (2000) and S. M. Kaye, et al., Nucl. Fusion 45, S168 (2005)] tokamak by comparing the upstream electron temperature (T{sub e}) and density (n{sub e}) profiles measured by the mid-plane reciprocating probe to the heat flux (q{sub {perpendicular}}) profile at the divertor plate measured by an infrared (IR) camera. It is found that electron conduction explains the near SOL width data reasonably well while the far SOL, which is in the sheath limited regime, requires an ion heat flux profile broader than the electron one to be consistent with the experimental data. The measured plasma parameters indicate that the SOL energy transport should be in the conduction-limited regime for R-R{sub sep} (radial distance from the separatrix location) < 2-3 cm. The SOL energy transport should transition to the sheath-limited regime for R-R{sub sep} > 2-3cm. The T{sub e}, n{sub e}, and q{sub {perpendicular}} profiles are better described by an offset exponential function instead of a simple exponential. The conventional relation between mid plane electron temperature decay length ({lambda}{sub Te}) and target heat flux decay length ({lambda}{sub q}) is {lambda}{sub Te} = 7/2{lambda}{sub q}, whereas the newly-derived relation, assuming offset exponential functional forms, implies {lambda}{sub Te} = (2-2.5){lambda}{sub q}. The measured values of {lambda}{sub Te}/{lambda}{sub q} differ from the new prediction by 25-30%. The measured {lambda}{sub q} values in the far SOL (R-R{sub sep} > 2-3cm) are 9-10cm, while the expected values are 2.7 < {lambda}{sub q} < 4.9 cm (for sheath-limited regime). We propose that the ion heat flux profile is substantially broader than the electron heat flux profile as an explanation for this discrepancy in the far SOL.

  2. SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS

    Microsoft Academic Search

    D. R. DENNIS NAGLE; D. R. DAJIE ZHANG

    2009-01-01

    Silicon carbide (SiC) materials are prime candidates for high temperature heat exchangers for next generation nuclear reactors due to their refractory nature and high thermal conductivity at elevated temperatures. This research has focused on demonstrating the potential of liquid silicon infiltration (LSI) for making SiC to achieve this goal. The major advantage of this method over other ceramic processing techniques

  3. Heat Exchange in Air, Water, and Soil

    NSDL National Science Digital Library

    John Eichinger

    2009-05-30

    The Earth is composed, at least at the surface, of soil/rock, water, and air. How do the heat exchange properties of these three very different substances compare, and what effect, if any, do they have on climate and weather? This activity represents a so

  4. Modelling heat exchangers for thermoelectric generators

    Microsoft Academic Search

    J. Esarte; G. Min; D. M. Rowe

    2001-01-01

    In order to further studies on thermoelectric generators, an analysis of the influence of fluid flow rate, heat exchanger geometry, fluid properties and inlet temperatures on the power supplied by the thermoelectric generator has been done. Different expressions and graphs showing this influence are shown in this paper, in order to give some practical guidelines for the thermoelectric generators design.

  5. Optimization of heat exchangers for solar concentrators

    Microsoft Academic Search

    P. R. Damshala; J. R. Williams

    1978-01-01

    A parametric study is done on heat exchangers to be used for cylindrical fixed mirror concentrators. The operational parameters, such as inlet fluid temperature, solar insolation, fluid flow rate, ambient temperature and wind velocities, are varied. The geometrical parameters, the absorber plate width and the diameter of the embedded copper tubes are also varied. The results of variation of these

  6. Low heat transfer oxidizer heat exchanger design and analysis

    NASA Technical Reports Server (NTRS)

    Kanic, P. G.; Kmiec, T. D.; Peckham, R. J.

    1987-01-01

    The RL10-IIB engine, a derivative of the RLIO, is capable of multi-mode thrust operation. This engine operates at two low thrust levels: tank head idle (THI), which is approximately 1 to 2 percent of full thrust, and pumped idle (PI), which is 10 percent of full thrust. Operation at THI provides vehicle propellant settling thrust and efficient engine thermal conditioning; PI operation provides vehicle tank pre-pressurization and maneuver thrust for log-g deployment. Stable combustion of the RL10-IIB engine at THI and PI thrust levels can be accomplished by providing gaseous oxygen at the propellant injector. Using gaseous hydrogen from the thrust chamber jacket as an energy source, a heat exchanger can be used to vaporize liquid oxygen without creating flow instability. This report summarizes the design and analysis of a United Aircraft Products (UAP) low-rate heat transfer heat exchanger concept for the RL10-IIB rocket engine. The design represents a second iteration of the RL10-IIB heat exchanger investigation program. The design and analysis of the first heat exchanger effort is presented in more detail in NASA CR-174857. Testing of the previous design is detailed in NASA CR-179487.

  7. Design, construction and testing of a thermosyphon heat exchanger for medium temperature heat recovery in bakeries

    Microsoft Academic Search

    A. R. Lukitobudi; A. Akbarzadeh; P. W. Johnson; P. Hendy

    1995-01-01

    Using water as the working fluid, air-to-air heat exchangers using thermosyphon heat pipes were designed, constructed and tested under medium temperature (below 300°C) operating conditions. A heat exchanger test rig has been constructed and developed wherein the heated air is recycled to the counterflow heat exchanger. The lengths of both the evaporator section and the condenser section of the heat

  8. Experimental Investigation on Heat Transfer Characteristics of a Gas-to-Gas Counterflow Microchannel Heat Exchanger

    Microsoft Academic Search

    K. Koyama; Y. Asako

    2010-01-01

    Heat transfer characteristics of a gas-to-gas counterflow microchannel heat exchanger have been experimentally investigated. Temperatures and pressures at inlets and outlets of the heat exchanger have been measured to obtain heat transfer rates and pressure drops. The heat transfer and the pressure drop characteristics are discussed. Since the partition wall of the heat exchanger is thick compared with the microchannel

  9. Fabrication and testing of microchannel heat exchangers

    NASA Astrophysics Data System (ADS)

    Cuta, Judith M.; Bennett, Wendy D.; McDonald, Carolyn E.; Ravigururajan, T. S.

    1995-09-01

    Micro-channel heat-exchanger test articles were fabricated and performance tested. The heat exchangers are being developed for innovative applications, and have been shown to be capable of handling heat loads of up to 100 W/cm2. The test articles were fabricated to represent two different designs for the micro-channel portion of the heat exchanger. One design consists of 166 micro-channels etched in silicon substrate, and a second design consists of 54 micro-channels machined in copper substrate. The devices were tested in an experimental loop designed for performance testing in single- and two-phase flow with water and R124. Pressure and liquid subcooling can be regulated over the range of interest, and a secondary heat removal loop provides stable loop performance for steady-state tests. The selected operating pressures are approximately 0.344 MPa for distilled water and 0.689 MPa for R124. The temperature ranges are 15.5 to 138 C for distilled water and 15.5 to 46 C for R-124. The mass flow range 7.6 X 10-8 to 7.6 X 10MIN5 kg/min for both distilled water and R124.

  10. Heat exchangers and the performance of heat pumps – Analysis of a heat pump database

    Microsoft Academic Search

    D. S. Kim; I. Moretti; M. Monsberger

    2011-01-01

    Heat pumping is a highly energy-efficient technology that could help reduce energy and environmental problems. The efficiency of a heat pump greatly depends on the individual and integral performance of the components inside. In this study, heat pump performance is investigated with a special focus on heat exchangers. Experimental data obtained from comprehensive heat pump measurements performed at the Austrian

  11. Heating system with vapour compressor heat pump and vertical U-tube ground heat exchanger

    NASA Astrophysics Data System (ADS)

    Hanuszkiewicz-Drapa?a, Ma?gorzata; Sk?adzie?, Jan

    2010-10-01

    In the paper a heating system with a vapour compressor heat pump and vertical U-tube ground heat exchanger for small residential house is considered. A mathematical model of the system: heated object - vapour compressor heat pump - ground heat exchanger is presented shortly. The system investigated is equipped, apart from the heat pump, with the additional conventional source of heat. The processes taking place in the analyzed system are of unsteady character. The model consists of three elements; the first containing the calculation model of the space to be heated, the second - the vertical U-tube ground heat exchanger with the adjoining area of the ground. The equations for the elements of vapour compressor heat pump form the third element of the general model. The period of one heating season is taken into consideration. The results of calculations for two variants of the ground heat exchanger are presented and compared. These results concern variable in time parameters at particular points of the system and energy consumption during the heating season. This paper presents the mutual influence of the ground heat exchanger subsystem, elements of vapour compressor heat pump and heated space.

  12. Compact Ceramic Heat Exchangers for Corrosive Waste Gas Applications

    E-print Network

    Laws, W. R.; Reed, G. R.

    1982-01-01

    The development of large ceramic heat exchangers is described and performance data given for units installed on steel industry soaking pits in the U.K. Operational experience since 1973 confirms that ceramic heat exchangers capable of operating...

  13. Preliminary SP-100/Stirling heat exchanger designs

    SciTech Connect

    Schmitz, P.; Tower, L. [Sverdrup Technology, Inc., Brook Park, OH (United States). Lewis Research Center Group; Dawson, R. [Aerospace Design and Fabrication Inc., Brook Park, OH (United States); Blue, B.; Dunn, P. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

    1994-09-01

    Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC`s are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems.

  14. Mechanism of failure of heat exchangers in cement furnaces

    Microsoft Academic Search

    M. A. Tylkin; B. N. Bogomolov; A. M. Sharkova

    1977-01-01

    Conclusions 1.Failure of heat exchangers made of steels Kh23N18 and Kh24N12SL results from carburizing and sulfur-alkali corrosion in the presence of compounds of vanadium forming a low-melting eutectic preferentially in austenite grain boundaries.2.The corrosion rate of heat exchangers in mazout furnaces is three times the corrosion rate of heat exchangers in gas furnaces.3.In heat exchangers that increase the gas flow

  15. BEHAVIOR OF EMERGENCY HEAT EXCHANGERS AND ISOLATION CONDENSERS

    Microsoft Academic Search

    K. Nelson; José N. Reyes

    This paper presents an overview of the present state of knowledge on emergency heat exchanger and isolation condenser operation. The key phenomena affecting their performance and reliability are described and predictive models are presented. 1.0 PASSIVE RESIDUAL HEAT EXCHANGER In some advanced Pressurized Water Reactors (PWR) a Passive Residual Heat Exchanger (PRHR), as shown in Figure 1, will be used

  16. Brazed aluminum, Plate-fin heat exchangers for OTEC

    Microsoft Academic Search

    Foust

    1980-01-01

    Brazed aluminum plate-fin heat exchangers have been available for special applications for over thirty years. The performance, compactness, versatility, and low cost of these heat exchangers has been unequaled by other heat exchanger configuration. The application of brazed aluminum has been highly limited because of necessary restrictions for clean non-corrosive atmospheres. Air and gas separation have provided ideal conditions for

  17. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 true Heat exchanger provisions. 63.1435 Section...Polyether Polyols Production § 63.1435 Heat exchanger provisions. (a) The owner...with the requirements of § 63.104 for heat exchange systems, with the...

  18. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Heat exchanger provisions. 63.1435 Section...Polyether Polyols Production § 63.1435 Heat exchanger provisions. (a) The owner...with the requirements of § 63.104 for heat exchange systems, with the...

  19. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Heat exchange systems. 63.654 Section...From Petroleum Refineries § 63.654 Heat exchange systems. (a) Except as...this section, the owner or operator of a heat exchange system that meets the...

  20. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Heat exchange system provisions. 63.1409...Amino/Phenolic Resins § 63.1409 Heat exchange system provisions. (a...subject to this subpart shall monitor each heat exchange system used to cool...

  1. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Heat exchange systems. 63.654 Section...From Petroleum Refineries § 63.654 Heat exchange systems. Link to an amendment...this section, the owner or operator of a heat exchange system that meets the...

  2. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Heat exchange systems provisions. 63.1328...IV Polymers and Resins § 63.1328 Heat exchange systems provisions. (a...subpart. (h) The compliance date for heat exchange systems subject to the...

  3. Plating Patches On Heat-Exchanger Jackets

    NASA Technical Reports Server (NTRS)

    Loureiro, Henry; Kubik, Frank

    1989-01-01

    Permanent repairs made without welding. Technique used to repair nickel-alloy nozzle jacket of Space Shuttle main engine. Applicable to other metal heat-exchanger jackets with similar configurations. Does not require welding, brazing, soldering, or other operations involving high temperatures and consequent damage to surrounding areas. Portion of jacket around damaged area removed by grinding and polishing out to edges adjacent to tube/jacket braze bonds. Spaces between tubes filled with wax preventing contamination of spaces during subsequent plating.

  4. Geothermal direct contact heat exchange. Final report

    Microsoft Academic Search

    Sims

    1977-01-01

    A glass direct contact heat exchange column was operated in the laboratory. The column was operated at atmospheric pressure using hot water and normal hexane. Column internals testing included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1°C for packing

  5. Heat flux and plasma flow in the scrape off layer on the spherical tokamak QUEST with inboard poloidal field null configuration

    NASA Astrophysics Data System (ADS)

    Onchi, Takumi; Zushi, Hideki; Mishra, Kishore; Hanada, Kazuaki; Idei, Hiroshi; Nakamura, Kazuo; Fujisawa, Akihide; Nagashima, Yoshihiko; Hasegawa, Makoto; Kuzmin, Arseny; Nagaoka, Kenichi; QUEST Team

    2014-10-01

    Heat flux and plasma flow in the scrape off layer (SOL) are examined in the inboard poloidal null (IPN) configuration on the spherical tokamak (ST) QUEST. In the ST, trapped energetic electrons on the low field side are widely excursed from the last closed flux surface to SOL so that significant heat loss occurs. Interestingly, plasma flows in the core and the SOL are also observed in IPN though no inductive force like ohmic heating is applied. High heat flux (>1 MW/m2) and sonic flow (M > 1) in far-SOL arise in current ramp-up phase. In quasi-steady state, sawtooth-like oscillation of plasma current with 20 Hz has been observed. Heat flux and subsonic plasma flow in far-SOL are well correlated to plasma current oscillation. The toroidal Mach number largely increases from M? ~ 0.1 to ~ 0.5 and drops although the amplitude of plasma current is about 10% of that. Note that such flow modification occurs before plasma current crash, there may be some possibility that phenomena in the SOL or the edge trigger reactions in the core plasma. This work is supported by Grants-in-aid for Scientific Research (S24226020), NIFS Collaboration Research Program (NIFS12KUTR081), and the Collaborative Research Program of Research Institute for Applied Mechanics, Kyushu University.

  6. Effects of heating power on divertor in-out asymmetry and scrape-off layer flow in reversed field on Experimental Advanced Superconducting Tokamak

    NASA Astrophysics Data System (ADS)

    Liu, S. C.; Guo, H. Y.; Wang, L.; Wang, H. Q.; Gan, K. F.; Xia, T. Y.; Xu, G. S.; Xu, X. Q.; Liu, Z. X.; Chen, L.; Yan, N.; Zhang, W.; Chen, R.; Shao, L. M.; Ding, S.; Hu, G. H.; Liu, Y. L.; Zhao, N.; Li, Y. L.; Gong, X. Z.; Gao, X.

    2014-12-01

    The dependence of divertor asymmetry and scrape-off layer (SOL) flow on heating power has been investigated in the Experimental Advanced Superconducting Tokamak (EAST). Divertor plasma exhibits an outboard-enhanced in-out asymmetry in heat flux in lower single null configuration for in reversed (ion ? B drift direction toward the upper X-point) field directions. Upper single null exhibits an inboard-favored asymmetry in low heating power condition, while exhibits an outboard-favored asymmetry when increasing the heating power. Double null has the strongest in-out asymmetry in heat flux, favoring the outer divertor. The in-out asymmetry ratios of q t , out / q t , in and P out / P total increase with the power across the separatrix P loss , which is probably induced by the enhanced radial particle transport due to a large pressure gradient. The characteristics of the measured SOL parallel flow under various discharge conditions are consistent with the Pfirsch-Schlüter (PS) flow with the parallel Mach number M ? decreasing with the line averaged density but increasing with P loss , in the same direction as the PS flow. The contributions of both poloidal E × B drift and parallel flow on poloidal particle transport in SOL on EAST are also assessed.

  7. Graphite Foam Heat Exchangers for Thermal Management

    SciTech Connect

    Klett, J.W.

    2004-06-07

    Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S-bond{reg_sign}, but still better than the standard heat sinks. Next, work with evaporative cooling techniques, such as heat pipes, demonstrated some unique behavior with the foam that is not seen with standard wick materials. This was that as the thickness of the foam increased, the performance got better, where with standard wick materials, as the thickness increases, the performance decreases. This is yet to be completely explained. Last, the designs from the thermal model were used to fabricate a series of cold plates with the graphite foam and compare them to similar designs using high performance folded fin aluminum sinks (considered standard in the industry). It was shown that by corrugating the foam parallel to fluid flow, the pressure drop can be reduced significantly while maintaining the same heat transfer as that in the folded fin heat sink. In fact, the results show that the graphite foam heat sink can utilized 5% the pumping power as that required with the folded fin aluminum heat sink, yet remove the same amount of heat.

  8. Turbulent heat exchanger {Delta}T and {Delta}P

    SciTech Connect

    Steinmeyer, D. [Monsanto Co., St. Louis, MO (United States)

    1996-12-31

    Optimum pressure drop ({Delta}P) and temperature difference ({Delta}T) in turbulent flow heat exchangers are presented in three frameworks: as quantitatively defined by fluid properties, the value of energy and the cost of heat exchange surface (with a little help from a relationship between [power/mass] and heat transfer); as the energy cost for heat recovery (with the {Delta}T cost being about equal to the heat exchanger cost and the {Delta}P cost being about 1/3 as great); and as the second law lost work inherent in heat exchange (with the {Delta}T loss being {approximately}3 times the {Delta}T loss).

  9. CONJUGATED HEAT TRANSFER IN COCURRENT FLOW MULTISTREAM HEAT EXCHANGERS

    Microsoft Academic Search

    Ryoichi Chiba

    2010-01-01

    Considering the cross-sectional velocity profile to be piecewise-constant in each stream of a multi-stream heat exchanger for cocurrent thermally developing flow, this study analytically solves the related conjugated Graetz problem by using an integral transform method. Further, it obtains an analytical solution in an explicit form to the fluid temperatures that vary two-dimensionally. A numerical example is provided for the

  10. Optimization of cross flow heat exchangers for thermoelectric waste heat recovery

    Microsoft Academic Search

    Douglas T. Crane; Gregory S. Jackson

    2004-01-01

    Thermoelectric waste heat recovery is investigated for current thermoelectric materials with advanced heat exchangers. Numerical heat exchanger models integrated with models for Bi2Te3 thermoelectric modules are validated against experimental data from previous cross flow heat exchanger studies as well as experiments using thermoelectrics between counterflow hot water and cooling air flow channels. The models are used in optimization studies of

  11. A microchannel experimental apparatus for heat exchanging: design and analysis

    Microsoft Academic Search

    WeiDong Wang; JianYuan Jia; ZhiWu Li; ChangQi Fan

    2005-01-01

    An experimental apparatus is developed for testing the heat-exchange performance of microchannel structures. This system mainly consists of microchannel heat exchangers, a simulated heat source, a micro-pump; a few of pipes, some three-way pipes and other test devices. The heat exchange coefficients and the fluid resistant in microchannels can be obtained by testing temperature, pressure and flow rate. The fluid

  12. Auxiliary heat-exchanger flow-distribution test

    Microsoft Academic Search

    J. S. Kaufman; M. M. Bressler

    1983-01-01

    The auxiliary heat exchanger flow distribution test was the first part of a test program to develop a water-cooled (tube-side), compact heat exchanger for removing heat from the circulating gas in a High-Temperature Gas-Cooled Reactor (HTGR). The function of this heat exchanger is to provide emergency cooldown for the HTGR. It is designed to operate over a wide range of

  13. DESIGN OF A COMPACT HEAT EXCHANGER FOR HEAT RECUPERATION FROM A HIGH TEMPERATURE ELECTROLYSIS SYSTEM

    Microsoft Academic Search

    G. K. Housley; J. E. OBrien; G. L. Hawkes

    2008-01-01

    Design details of a compact heat exchanger and supporting hardware for heat recuperation in a high-temperature electrolysis application are presented. The recuperative heat exchanger uses a vacuum-brazed plate-fin design and operates between 300 and 800°C. It includes corrugated inserts for enhancement of heat transfer coefficients and extended heat transfer surface area. Two recuperative heat exchangers are required per each four-stack

  14. Geothermal application of heat exchanger design for desalination plants

    Microsoft Academic Search

    E. A. Fritzler; G. E. Coury

    1980-01-01

    Heat exchangers can be a very costly part of modern geothermal plants for either electric or direct heat applications. To make maximum use of technology transfer from other industries, and to minimize as much as possible the need to duplicate previous work, this report has been prepared to provide an analytical review of the very extensive literature on heat exchangers

  15. A structured approach to heat exchanger network retrofit design

    Microsoft Academic Search

    J. L. B. Van Reisen

    2008-01-01

    Process plants have high energy consumption. Much energy can be saved by a proper design of the heat exchanger network, which contains the main heat transferring equipment of the plant. Existing plants can often be made more energy-efficient by a retrofit: the (physical) modification of the equipment and piping in the heat exchanger network. This also allows application of new

  16. Efficiency of short heat exchangers for helium vapor cooling

    Microsoft Academic Search

    D. Steffensrud; J. Bahis; E. Christenson; K. Fassnacht; E. Guckel; D. Harriman; S. Nahn; P. Vu; J. Zhang

    1991-01-01

    The heat transfer efficiency of short heat exchangers along the vent tube of a helium cryostat and the temperature profile of the helium vapor along the vent tube are both measured. The results of the measurements show that the heat exchangers are in some cases considerably more efficient than indicated by simple model calculations. With a flow rate of 0.0044

  17. Heat exchanger fouling model and preventive maintenance scheduling tool

    Microsoft Academic Search

    V. R. Radhakrishnan; M. Ramasamy; H. Zabiri; V. Do Thanh; N. M. Tahir; H. Mukhtar; M. R. Hamdi; N. Ramli

    2007-01-01

    The crude preheat train (CPT) in a petroleum refinery consists of a set of large heat exchangers which recovers the waste heat from product streams to preheat the crude oil. In these exchangers the overall heat transfer coefficient reduces significantly during operation due to fouling. The rate of fouling is highly dependent on the properties of the crude blends being

  18. Control of heat exchangers using Model Predictive Controller

    Microsoft Academic Search

    Krishna V Vinaya; K. Ramkumar; V Alagesan

    2012-01-01

    The objective of this paper is to develop a Model Predictive Control (MPC) for a Shell and Tube Heat Exchanger. Since the heat exchanger is a highly non linear system, the operating zone of the system is divided into different zones. For each zone, a model is developed. Even though PID controllers are widely used for the control of heat

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

    Microsoft Academic Search

    D. A. Olson

    1992-01-01

    The authors have measured heat transfer and pressure drop 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

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

    Microsoft Academic Search

    D. A. Olson

    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

  1. Limitations of Using Uniform Heat Flux Assumptions in Sizing Vertical Borehole Heat Exchanger Fields

    E-print Network

    of ground heat exchangers (GHE) used with ground source heat pump (GSHP) systems. These models can account approach with a parametric study. Keywords - Ground Source Heat Pumps; Borehole Heat Exchangers; Finite Line Source Theory; g-functions 1. Introduction Ground source heat pump (GSHP) systems are a widely

  2. Applications of the Strong Heat Transformation by Pulse Flow in the Shell and Tube Heat Exchanger 

    E-print Network

    Chen, Y.; Zhao, J.

    2006-01-01

    This article deals with the heat exchange coefficient varied with pulse frequency in the pulsation tube with different flow forms. The findings show that heat can be exchanged coefficient with the pulse frequency, and it has an optimal frequency...

  3. Automatic Tube Cleaning Systems for Condensers and Heat Exchangers 

    E-print Network

    Someah, K.

    1991-01-01

    The on-line Automatic Tube Cleaning Systems (ATCS) for condensers and heat exchangers provide a positive means for automatic cleaning on a continuous basis, while the exchanger or condenser remains "on stream" and at its full operating potential...

  4. Automatic Tube Cleaning Systems for Condensers & Heat Exchangers 

    E-print Network

    Someah, K.

    1993-01-01

    plant operating and maintenance cost savings from these systems. The on-line Automatic Tube Cleaning Systems (ATCS) for condensers and heat exchangers provide a positive means for automatic cleaning on a continuous basis, while the exchanger or condenser...

  5. Performance of multiple mini-tube heat exchangers as an internal heat exchanger of a vapor-injection cycle heat pump

    NASA Astrophysics Data System (ADS)

    Jang, Jin Yong; Jeong, Ji Hwan

    2015-05-01

    A multiple mini-tube (MMT) heat exchanger was considered as an internal heat exchanger of vapor-injection cycle heat pump. Heat transfer and pressure drop in multiple mini-tube heat exchangers were numerically and experimentally investigated. Results show that the best performance of the MMT heat exchanger can be obtained when the intermediate-pressure two-phase refrigerant is supplied to the shell-side and this refrigerant reaches a saturated vapor state at the exit of the heat exchanger.

  6. Heat transfer with phase change in plate-fin heat exchangers

    NASA Astrophysics Data System (ADS)

    Panchal, C. B.

    1984-08-01

    A theoretical and experimental study was conducted for convective evaporation and condensation in plate-fin compact heat exchangers. The overall performance of a brazed-aluminum heat exchanger in the evaporation mode with ammonia and in the condensation mode with both ammonia and refrigerant R-22 as working fluids. The heat exchanger has straight perforated fins on the working-fluid side and extruded rectangular channels on the single-phase (water) side. The two-phase flow in narrow channels of the heat exchanger is modeled using a triangular relationship between pressure gradient, liquid film flow rate, and film thickness. The overall performance of the heat exchanger is calculated by employing local heat-transfer analysis and integrating mass- and heat-balance equations along the heat-exchanger length. Theoretical predictions are found to agree favorably with experimental results for a prototypical heat exchanger unit.

  7. Heat Pump Cycle with Solution Circuit and Internal Heat Exchange

    E-print Network

    Radermacher, R.

    when a two-stage version fed into the same compressor. While ammonia of this cycl e is used. In this paper. another evaporate s out of an ammonia-water sol ution on C version of such cycles will be discussed which the composition. X. of this solution... somewhat. This is indicated in Figure 1 by ~e been calculated and the results are presented. elongated heat exchanger C. spanning a tempe~ature interval. The sol ution remaining in C is Pted by INTRODUCTION means of a solution pump through a liquid...

  8. Heat-transfer and friction factor design data for all-metal compact heat exchangers

    Microsoft Academic Search

    Christina L. Cain

    1989-01-01

    To improve system life, an effort was undertaken to develop all-metal compact heat exchangers to replace existing heat exchangers which contain organic materials. Eliminating organic materials increases system life because outgassing organics can contaminate the helium working fluid and reduce system life. Perforated plate heat exchangers were found to have inherently low axial conduction and are therefore excellent candidates for

  9. Foundation heat exchangers for residential ground source heat pump systems—Numerical modeling and experimental validation

    Microsoft Academic Search

    Lu Xing; James R. Cullin; Jeffrey D. Spitler; Piljae Im; Daniel E. Fisher

    2011-01-01

    A new type of ground heat exchanger that utilizes the excavation often made for basements or foundations has been proposed as an alternative to conventional ground heat exchangers. This article describes a numerical model that can be used to size these foundation heat exchanger (FHX) systems. The numerical model is a two-dimensional finite-volume model that considers a wide variety of

  10. Heat exchanger development at Reaction Engines Ltd.

    NASA Astrophysics Data System (ADS)

    Varvill, Richard

    2010-05-01

    The SABRE engine for SKYLON has a sophisticated thermodynamic cycle with heat transfer between the fluid streams. The intake airflow is cooled in an efficient counterflow precooler, consisting of many thousand small bore thin wall tubes. Precooler manufacturing technology has been under investigation at REL for a number of years with the result that flightweight matrix modules can now be produced. A major difficulty with cooling the airflow to sub-zero temperatures at low altitude is the problem of frost formation. Frost control technology has been developed which enables steady state operation. The helium loop requires a top cycle heat exchanger (HX3) to deliver a constant inlet temperature to the main turbine. This is constructed in silicon carbide and the feasibility of manufacturing various matrix geometries has been investigated along with suitable joining techniques. A demonstration precooler will be made to run in front of a Viper jet engine at REL's B9 test facility in 2011. This precooler will incorporate full frost control and be built from full size SABRE engine modules. The facility will incorporate a high pressure helium loop that rejects the absorbed heat to a bath of liquid nitrogen.

  11. High resolution scrape-off layer profile measurements in limited and diverted plasmas in C-Mod - investigation of heat flux channel width physics

    NASA Astrophysics Data System (ADS)

    Labombard, B.; Terry, J. L.; Brunner, D.; Edlund, E.; Golfinopoulos, T.; Hughes, J. W.; Theiler, C.; Walk, J.; Wolfe, S.; Whyte, D.

    2014-10-01

    Narrow scrape-off layer (SOL) heat flux channel widths (?q) are seen on many tokamaks, both in inner-wall limited (IWL) and diverted discharges. These observations have important consequences for ITER and reactors, impacting the design of inner limiter tiles for heat load during startup and pushing the limits of dissipative divertor operation and control. A dominant ~ 1/Ip scaling for ?q is seen in a wide range of cases (IWL, H-mode and L-mode diverted [at low density]), suggestive of a poloidal ion gyroradius effect. It is troubling that ?q does not appear to scale with major radius - a challenge for reactors. The latter observation contrasts with H-mode pedestal widths that increase with machine size, implying that the physics that sets the local gradient scale lengths in pedestal and SOL may be different. We have recently implemented a scanning ``Mirror Langmuir Probe'' diagnostic on C-Mod with the idea of exploring this critical interface with very high resolution. Narrow ?q ``features'' in IWL discharges have been mapped out in detail, exhibiting a ~ 1/Ip scaling with some evidence of a break-in-slope feature at the LCFS. We will report on these findings and on L and H-mode experiments in progress, in which divertor conditions are varied (low recycling, high-recycling, detached). Supported by DE-FC02-99ER54512.

  12. Development of residential gas-fired furnaces using heat pipe heat exchangers. Final report, July 1988February 1992

    Microsoft Academic Search

    P. M. Dussinger; J. R. Hartenstine

    1992-01-01

    The principal objective of the heat pipe heat exchanger development program was to design, fabricate, and demonstrate the performance of heat pipe heat exchangers for gas-fired residential furnaces that improved upon the previously marketed heat pipe furnace.

  13. Test results of a Stirling engine utilizing heat exchanger modules with an integral heat pipe

    Microsoft Academic Search

    Robert C. Skupinski; Leonard K. Tower; Frank J. Madi; Kevin D. Brusk

    1993-01-01

    The Heat Pipe Stirling Engine (HP-1000), a free-piston Stirling engine incorporating three heat exchanger modules, each having a sodium filled heat pipe, has been tested at the NASA-Lewis Research Center as part of the Civil Space Technology Initiative (CSTI). The heat exchanger modules were designed to reduce the number of potential flow leak paths in the heat exchanger assembly and

  14. 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

    The use of thermal energy storage (TES) in the latent heat of molten salts as a means of conserving fossil fuels and lowering the cost of electric power was evaluated. Public utility systems provided electric power on demand. This demand is generally maximum during late weekday afternoons, with considerably lower overnight and weekend loads. Typically, the average demand is only 60% to 80% of peak load. As peak load increases, the present practice is to purchase power from other grid facilities or to bring older less efficient fossil-fuel plants on line which increase the cost of electric power. The widespread use of oil-fired boilers, gas turbine and diesel equipment to meet peaking loads depletes our oil-based energy resources. Heat exchangers utilizing molten salts can be used to level the energy consumption curve. The study begins with a demand analysis and the consideration of several existing modern fossil-fuel and nuclear power plants for use as models. Salts are evaluated for thermodynamic, economic, corrosive, and safety characteristics. Heat exchanger concepts are explored and heat exchanger designs are conceived. Finally, the economics of TES conversions in existing plants and new construction is analyzed. The study concluded that TES is feasible in electric power generation. Substantial data are presented for TES design, and reference material for further investigation of techniques is included.

  15. The LUX prototype detector: Heat exchanger development

    NASA Astrophysics Data System (ADS)

    Akerib, D. S.; Bai, X.; Bedikian, S.; Bernstein, A.; Bolozdynya, A.; Bradley, A.; Cahn, S. B.; Carr, D.; Chapman, J. J.; Clark, K.; Classen, T.; Curioni, A.; Dahl, C. E.; Dazeley, S.; de Viveiros, L.; Dragowsky, M.; Druszkiewicz, E.; Fiorucci, S.; Gaitskell, R. J.; Hall, C.; Faham, C.; Holbrook, B.; Kastens, L.; Kazkaz, K.; Kwong, J.; Lander, R.; Leonard, D.; Malling, D.; Mannino, R.; McKinsey, D. N.; Mei, D.; Mock, J.; Morii, M.; Nikkel, J. A.; Phelps, P.; Shutt, T.; Skulski, W.; Sorensen, P.; Spaans, J.; Steigler, T.; Svoboda, R.; Sweany, M.; Thomson, J.; Tripathi, M.; Walsh, N.; Webb, R.; White, J.; Wolfs, F. L. H.; Woods, M.; Zhang, C.

    2013-05-01

    The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP-nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large (>1 ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 m to be achieved in approximately 2 days and sustained for the duration of the testing period.

  16. Advanced heat exchanger development for molten salts

    DOE PAGESBeta

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet materialmore »in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically « less

  17. Evaluation of porous media heat exchangers for fusion applications

    Microsoft Academic Search

    J. H. Rosenfeld; J. E. Lindemuth; M. T. North; R. D. Watson; D. L. Youchison; R. H. Goulding

    1996-01-01

    Several types of porous media heat exchangers are being evaluated for use in fusion applications. Broadly, these devices can be classified as capillary-pumped (heat pipes) or mechanically-pumped heat exchangers. Monel\\/water thermosyphon heat pipes with a porous metal wick are being evaluated for use in Faraday shields. A subscale prototype has been fabricated, and initial tests at Oak Ridge National Laboratory

  18. Heat Transfer Characteristics of a Quadratic Koch Island Fractal Heat Exchanger

    Microsoft Academic Search

    Josua P. Meyer; Hilde van der Vyver

    2005-01-01

    Heat exchangers are widely used in the air conditioning and refrigeration industries, and any increase in their efficiency will have a positive effect on the industry as well. A new design of heat exchanger is proposed that will increase the heat transfer area significantly. The heat transfer area was increased by the use of fractals. Three techniques were used to

  19. Preliminary evaluation of a heat pipe heat exchanger on a regenerative turbofan

    Microsoft Academic Search

    Kraft

    1975-01-01

    A preliminary evaluation was made of a regenerative turbofan engine using a heat pipe heat exchanger. The heat exchanger had an effectiveness of 0.70, a pressure drop of 3 percent on each side, and used sodium for the working fluid in the stainless steel heat pipes. The engine was compared to a reference turbofan engine originally designed for service in

  20. The design and fabrication of a Stirling engine heat exchanger module with an integral heat pipe

    Microsoft Academic Search

    Jeffrey G. Schreiber

    1988-01-01

    The conceptual design of a free-piston Stirling Space Engine (SSE) intended for space power applications has been generated. The engine was designed to produce 25 kW of electric power with heat supplied by a nuclear reactor. A novel heat exchanger module was designed to reduce the number of critical joints in the heat exchanger assembly while also incorporating a heat

  1. Heat transfer in a compact tubular heat exchanger with helium gas at 3.5 MPa

    Microsoft Academic Search

    Douglas A. Olson; Michael P. Glover

    1990-01-01

    A compact heat exchanger was constructed consisting of circular tubes in parallel brazed to a grooved base plate. This tube specimen heat exchanger was tested in an apparatus which radiatively heated the specimen on one side at a heat flux of up to 54 W\\/sq cm, and cooled the specimen with helium gas at 3.5 MPa and Reynolds numbers of

  2. On the thermoeconomical optimization of heat pipe heat exchanger HPHE for waste heat recovery

    Microsoft Academic Search

    M. S Söylemez

    2003-01-01

    A thermoeconomic optimization analysis is presented yielding a simple algebraic formula for estimating the optimum HPHE effectiveness for energy recovery applications. The P1–P2 method is used in the present study, together with the ?–NTU method, for thermoeconomic analysis of a heat pipe heat exchanger, HPHE, of a noncondensing fluid type, i.e. employing water and air.

  3. Boundary geometric control of a counter-current heat exchanger

    Microsoft Academic Search

    Ahmed Maidi; Moussa Diaf; Jean-Pierre Corriou

    2009-01-01

    The present article deals with the boundary geometric control of a counter-current heat exchanger whose control is designed considering a model based on two partial derivative equations describing the variations of internal and external temperatures. The objective consists in controlling the internal fluid temperature, at the heat exchanger outlet, by manipulating the jacket temperature at its inlet boundary in spite

  4. Evaluation and design of downhole heat exchangers for direct application

    Microsoft Academic Search

    Gene Culver; Gordon M. Reistad

    1974-01-01

    Over 400 wells with downhole heat exchangers are in use in Klamath Falls, Oregon. Some have been in use for nearly 30 years. Despite the large number and the long experience, the exact nature of the mechanism of heat exchange and, therefore, the maximum output was not known, except that it had been theorized that convection cells were established in

  5. Failure analysis of heat exchanger tubes of four gas coolers

    Microsoft Academic Search

    S. R. Allahkaram; P. Zakersafaee; S. A. M. Haghgoo

    2011-01-01

    A Number of leaks occurred on four heat exchangers used on an off-shore platform in the south of Iran. As a result heat exchanger tubes made of Inconel 625 failed after only two years in operation. The failure was caused by pitting corrosion in two contact regions, tubes and baffles as well as in tube sheet and shell contact regions

  6. Ceramic heat exchangers for gas turbines or turbojets

    NASA Astrophysics Data System (ADS)

    Boudigues, S.; Fabri, J.

    The required performance goals and several proposed designs for SiC heat exchangers for aerospace turbines are presented. Ceramic materials are explored as a means for achieving higher operating temperatures while controlling the weight and cost of the heat exchangers. Thermodynamic analyses and model tests by ONERA have demonstrated the efficacy of introducing a recooling cycle and placing the heat exchangers between stages of the turbine. Sample applications are discussed for small general aviation aircraft and subsonic missiles equipped with single-flux exchangers. A double-flux exchanger is considered for an aircraft capable of Mach 0.8 speed and at least 11 km altitude for cruise. Finally, the results of initial attempts to manufacture SiC honeycomb heat exchangers are detailed.

  7. Test results of a Stirling engine utilizing heat exchanger modules with an integral heat pipe

    SciTech Connect

    Skupinski, R.C.; Tower, L.K.; Madi, F.J.; Brusk, K.D.

    1993-04-01

    The Heat Pipe Stirling Engine (HP-1000), a free-piston Stirling engine incorporating three heat exchanger modules, each having a sodium filled heat pipe, has been tested at the NASA-Lewis Research Center as part of the Civil Space Technology Initiative (CSTI). The heat exchanger modules were designed to reduce the number of potential flow leak paths in the heat exchanger assembly and incorporate a heat pipe as the link between the heat source and the engine. An existing RE-1000 free-piston Stirling engine was modified to operate using the heat exchanger modules. This paper describes heat exchanger module and engine performance during baseline testing. Condenser temperature profiles, brake power, and efficiency are presented and discussed.

  8. Method of pressure pulse cleaning heat exchanger tubes, upper tube support plates and other areas in a nuclear steam generator and other tube bundle heat exchangers

    Microsoft Academic Search

    T. D. Scharton; G. B. Taylor

    1987-01-01

    This patent describes the art of removing corrosive deposits from locations within a heat exchanger in which the heat exchanger is characterized by an enclosed tank containing heat exchanger tubes which are closely packed together and support plates arranged transverse to and sequentially spaced along the longitudinal axis of the heat exchanger tubes and forming junctions therewith, where the support

  9. Peltier cooling system utilizing liquid heat exchanger combined with pump

    Microsoft Academic Search

    H. Nishihata; O. Kido; T. Ueno

    2002-01-01

    Peltier cooling systems utilizing liquid heat transfer directly with thermoelectric modules are adopted in fridges for hotel-use, home-bar and so forth. This paper reports the development of a highly efficient, high capacity liquid heat exchanger in which a thermoelectric module is installed to minimize electric power consumption and reduce cost. In the heat exchanger, a highly efficient 62-mm diameter round

  10. Heat exchanger and method of making. [rocket lining

    NASA Technical Reports Server (NTRS)

    Fortini, A.; Kazaroff, J. M. (inventors)

    1980-01-01

    A heat exchange of increased effectiveness is disclosed. A porous metal matrix is disposed in a metal chamber or between walls through which a heat-transfer fluid is directed. The porous metal matrix has internal bonds and is bonded to the chamber in order to remove all thermal contact resistance within the composite structure. Utilization of the invention in a rocket chamber is disclosed as a specific use. Also disclosed is a method of constructing the heat exchanger.

  11. Design and testing of heat exchangers with liquid metal heat pipes for Stirling engines

    NASA Astrophysics Data System (ADS)

    Gonnov, I. V.; Ivanovskii, M. N.; Loktionov, I. V.; Loginov, N. I.; Stoliarov, S. P.; Tchulkov, B. A.

    The main results of an experimental study of Stirling engine (SE) heat supply systems with regard to the experience of working with heat pipes and liquid metal alkaline heat transfer agents are presented. The major functions of heat pipes, the equalization of temperature on the heating surface and the provision of predetermined heat flows and heat transfer, are realized. The investigations of heat exchangers reveal their serviceability in SE and their high efficiency.

  12. Method for making heat exchange tubes

    SciTech Connect

    Cunningham, J.L.; Campbell, B.J.

    1987-09-15

    This patent describes a method of making a heat exchange tube from difficult to work materials such as titanium and stainless steel in a single finning pass. It consists of inserting a mandrel having at least a first larger diameter portion and a second smaller diameter portion inside a plain tube. Then move the axes of a rotating disc carrying finning arbors toward the tube so that first and second sets of discs on the arbors, which are separated from each other by a spacer member, will sequentially force portions of the tube toward the first and second portions of the mandrel. The first set of discs serve to initially form the fins on the tube to at least approximately their final outside diameter and the second set of discs, whose discs are axially spaced so as to have a greater pitch than the discs of the first set, serve to reduce the root diameter of the fins previously formed by the first set of discs without substantially changing the outer diameter of the fins formed by the first set of discs. The greater pitch of the second set of discs causes an elongation of the tube and reduces its tendency to twist during finning.

  13. Modeling and optimization of isolated heat pipe heat exchange system based on Matlab

    Microsoft Academic Search

    Yuanfang Zhu; Ruihua Wang; Yating Zhang

    2010-01-01

    In order to reduce air-conditioning energy consumption of original computer room, an isolated heat exchange system is added to Beijing Unicom computer room. The steady-state model of the heat exchange system is built using mechanism modeling method according to actual operating data and the basic principles of heat transfer process. The optimal operating point of the system is obtained with

  14. Error Analysis of Heat Transfer for Finned-Tube Heat-Exchanger Text-Board 

    E-print Network

    Chen, Y.; Zhang, J.

    2006-01-01

    In order to reduce the measurement error of heat transfer in water and air side for finned-tube heat-exchanger as little as possible, and design a heat-exchanger test-board measurement system economically, based on the principle of test-board system...

  15. Error Analysis of Heat Transfer for Finned-Tube Heat-Exchanger Text-Board

    E-print Network

    Chen, Y.; Zhang, J.

    2006-01-01

    In order to reduce the measurement error of heat transfer in water and air side for finned-tube heat-exchanger as little as possible, and design a heat-exchanger test-board measurement system economically, based on the principle of test-board system...

  16. Intensification of heat-transfer and mixing in multifunctional heat exchangers by artificially generated streamwise vorticity

    Microsoft Academic Search

    S. Ferrouillat; P. Tochon; C. Garnier; H. Peerhossaini

    2006-01-01

    Compact heat exchangers are well known for their ability to transfer a large amount of heat while retaining low volume and weight. The purpose of this paper is to study the potential of using this device as a mixer as well as a chemical reactor, generally called a multifunctional heat exchanger (MHE). Indeed, the question arises: can these geometries combine

  17. 40 CFR 63.1085 - What are the general requirements for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...false What are the general requirements for heat exchange systems? 63.1085 Section 63...Standards for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Heat Exchange System Requirements § 63.1085...

  18. 40 CFR 63.1083 - Does this subpart apply to my heat exchange system?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Does this subpart apply to my heat exchange system? 63.1083 Section...for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1083 Does...

  19. 40 CFR 63.502 - Equipment leak and heat exchange system provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Equipment leak and heat exchange system provisions. 63.502...Resins § 63.502 Equipment leak and heat exchange system provisions. (a) Equipment...the purposes of this subpart. (n) Heat exchange system provisions. The...

  20. 40 CFR 63.1085 - What are the general requirements for heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...false What are the general requirements for heat exchange systems? 63.1085 Section 63...Standards for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Heat Exchange System Requirements § 63.1085...

  1. 40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...standards and compliance requirements for heat exchange systems? 63.11499 Section...standards and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat exchange system is equal to or...

  2. 40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...standards and compliance requirements for heat exchange systems? 63.11499 Section...standards and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat exchange system is equal to or...

  3. 40 CFR 63.502 - Equipment leak and heat exchange system provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Equipment leak and heat exchange system provisions. 63.502...Resins § 63.502 Equipment leak and heat exchange system provisions. (a) Equipment...the purposes of this subpart. (n) Heat exchange system provisions. The...

  4. 40 CFR 63.1083 - Does this subpart apply to my heat exchange system?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Does this subpart apply to my heat exchange system? 63.1083 Section...for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1083 Does...

  5. Subterranean heat exchanger for refrigeration air conditioning equipment

    Microsoft Academic Search

    Rothwell

    1980-01-01

    Heat exchanger apparatus for use with refrigeration cycle heating and cooling equipment is disclosed. In the preferred embodiment, it cooperates with and modifies refrigeration equipment including a compressor, an expansion valve, an evaporator coil and a closed loop for cycling refrigerant. This apparatus is a sealed container adapted to be placed in a well extending into artesian (Relatively heated or

  6. Microchannel crossflow fluid heat exchanger and method for its fabrication

    DOEpatents

    Swift, G.W.; Migliori, A.; Wheatley, J.C.

    1985-05-14

    A microchannel crossflow fluid heat exchanger and a method for its fabrication are disclosed. The heat exchanger is formed from a stack of thin metal sheets which are bonded together. The stack consists of alternating slotted and unslotted sheets. Each of the slotted sheets includes multiple parallel slots which form fluid flow channels when sandwiched between the unslotted sheets. Successive slotted sheets in the stack are rotated ninety degrees with respect to one another so as to form two sets of orthogonally extending fluid flow channels which are arranged in a crossflow configuration. The heat exchanger has a high surface to volume ratio, a small dead volume, a high heat transfer coefficient, and is suitable for use with fluids under high pressures. The heat exchanger has particular application in a Stirling engine that utilizes a liquid as the working substance. 9 figs.

  7. Microchannel crossflow fluid heat exchanger and method for its fabrication

    DOEpatents

    Swift, G.W.; Migliori, A.; Wheatley, J.C.

    1982-08-31

    A microchannel crossflow fluid heat exchanger and a method for its fabrication are disclosed. The heat exchanger is formed from a stack of thin metal sheets which are bonded together. The stack consists of alternating slotted and unslotted sheets. Each of the slotted sheets includes multiple parallel slots which form fluid flow channels when sandwiched between the unslotted sheets. Successive slotted sheets in the stack are rotated ninety degrees with respect to one another so as to form two sets of orthogonally extending fluid flow channels which are arranged in a crossflow configuration. The heat exchanger has a high surface to volume ratio, a small dead volume, a high heat transfer coefficient, and is suitable for use with fluids under high pressures. The heat exchanger has particular application in a Stirling engine that utilizes a liquid as the working substance.

  8. Microchannel crossflow fluid heat exchanger and method for its fabrication

    DOEpatents

    Swift, Gregory W. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM); Wheatley, John C. (Los Alamos, NM)

    1985-01-01

    A microchannel crossflow fluid heat exchanger and a method for its fabrication are disclosed. The heat exchanger is formed from a stack of thin metal sheets which are bonded together. The stack consists of alternating slotted and unslotted sheets. Each of the slotted sheets includes multiple parallel slots which form fluid flow channels when sandwiched between the unslotted sheets. Successive slotted sheets in the stack are rotated ninety degrees with respect to one another so as to form two sets of orthogonally extending fluid flow channels which are arranged in a crossflow configuration. The heat exchanger has a high surface to volume ratio, a small dead volume, a high heat transfer coefficient, and is suitable for use with fluids under high pressures. The heat exchanger has particular application in a Stirling engine that utilizes a liquid as the working substance.

  9. Heat transfer with phase change in plate-fin heat exchangers

    Microsoft Academic Search

    C. B. Panchal

    1984-01-01

    A theoretical and experimental study was conducted for convective evaporation and condensation in plate-fin compact heat exchangers. The overall performance of a brazed-aluminum heat exchanger in the evaporation mode with ammonia and in the condensation mode with both ammonia and refrigerant R-22 as working fluids. The heat exchanger has straight perforated fins on the working-fluid side and extruded rectangular channels

  10. A simplified model for heat transfer in heat exchangers and stack plates for thermoacoustic devices

    SciTech Connect

    Chen, Y.; Herman, C.

    1999-07-01

    A simplified model of heat transfer in heat exchangers and stack plates of thermoacoustic devices was developed. The model took advantage of previous results regarding the thermal behavior of the thermoacoustic core for investigations of the performance of heat exchangers attached to the core. Geometrical and operational parameters as well as thermophysical properties of the heat exchangers, the plate, and the working medium were organized into dimensionless groups that allowed to account for their impact on the performance of the heat exchangers. Numerical simulations with the model were carried out. Nonlinear temperature distributions and heat fluxes near the edge of the stack plate were observed. Effects of different parameters on the thermal performance of the heat exchangers were investigated.

  11. Experimental determination of correlations for average heat transfer coefficients in heat exchangers on both fluid sides

    NASA Astrophysics Data System (ADS)

    Taler, Dawid

    2013-08-01

    This paper presents an experimental-numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined based on experimental data using a non-linear regression method. Correlation coefficients were determined from the condition that the weighted sum of squared liquid and air temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The uncertainty in estimated parameters was determined using the error propagation rule by Gauss. The outlet temperature of the liquid and air leaving the heat exchanger was calculated using an analytical model of the heat exchanger.

  12. Heat exchanger for reactor core and the like

    DOEpatents

    Kaufman, Jay S. (Del Mar, CA); Kissinger, John A. (Del Mar, CA)

    1986-01-01

    A compact bayonet tube type heat exchanger which finds particular application as an auxiliary heat exchanger for transfer of heat from a reactor gas coolant to a secondary fluid medium. The heat exchanger is supported within a vertical cavity in a reactor vessel intersected by a reactor coolant passage at its upper end and having a reactor coolant return duct spaced below the inlet passage. The heat exchanger includes a plurality of relatively short length bayonet type heat exchange tube assemblies adapted to pass a secondary fluid medium therethrough and supported by primary and secondary tube sheets which are releasibly supported in a manner to facilitate removal and inspection of the bayonet tube assemblies from an access area below the heat exchanger. Inner and outer shrouds extend circumferentially of the tube assemblies and cause the reactor coolant to flow downwardly internally of the shrouds over the tube bundle and exit through the lower end of the inner shroud for passage to the return duct in the reactor vessel.

  13. Evaluation of fluid bed heat exchanger optimization parameters. Final report

    SciTech Connect

    Not Available

    1980-03-01

    Uncertainty in the relationship of specific bed material properties to gas-side heat transfer in fluidized beds has inhibited the search for optimum bed materials and has led to over-conservative assumptions in the design of fluid bed heat exchangers. An experimental program was carried out to isolate the effects of particle density, thermal conductivity, and heat capacitance upon fluid bed heat transfer. A total of 31 tests were run with 18 different bed material loads on 12 material types; particle size variations were tested on several material types. The conceptual design of a fluidized bed evaporator unit was completed for a diesel exhaust heat recovery system. The evaporator heat transfer surface area was substantially reduced while the physical dimensions of the unit increased. Despite the overall increase in unit size, the overall cost was reduced. A study of relative economics associated with bed material selection was conducted. For the fluidized bed evaporator, it was found that zircon sand was the best choice among materials tested in this program, and that the selection of bed material substantially influences the overall system costs. The optimized fluid bed heat exchanger has an estimated cost 19% below a fin augmented tubular heat exchanger; 31% below a commercial design fluid bed heat exchanger; and 50% below a conventional plain tube heat exchanger. The comparisons being made for a 9.6 x 10/sup 6/ Btu/h waste heat boiler. The fluidized bed approach potentially has other advantages such as resistance to fouling. It is recommended that a study be conducted to develop a systematic selection of bed materials for fluidized bed heat exchanger applications, based upon findings of the study reported herein.

  14. SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS

    SciTech Connect

    DR. DENNIS NAGLE; DR. DAJIE ZHANG

    2009-03-26

    Silicon carbide (SiC) materials are prime candidates for high temperature heat exchangers for next generation nuclear reactors due to their refractory nature and high thermal conductivity at elevated temperatures. This research has focused on demonstrating the potential of liquid silicon infiltration (LSI) for making SiC to achieve this goal. The major advantage of this method over other ceramic processing techniques is the enhanced capability of making high dense, high purity SiC materials in complex net shapes. For successful formation of net shape SiC using LSI techniques, the carbon preform reactivity and pore structure must be controlled to allow the complete infiltration of the porous carbon structure which allows complete conversion of the carbon to SiC. We have established a procedure for achieving desirable carbon properties by using carbon precursors consisting of two readily available high purity organic materials, crystalline cellulose and phenolic resin. Phenolic resin yields a glassy carbon with low chemical reactivity and porosity while the cellulose carbon is highly reactive and porous. By adjusting the ratio of these two materials in the precursor mixtures, the properties of the carbons produced can be controlled. We have identified the most favorable carbon precursor composition to be a cellulose resin mass ratio of 6:4 for LSI formation of SiC. The optimum reaction conditions are a temperature of 1800 C, a pressure of 0.5 Torr of argon, and a time of 120 minutes. The fully dense net shape SiC material produced has a density of 2.96 g cm{sup -3} (about 92% of pure SiC) and a SiC volume fraction of over 0.82. Kinetics of the LSI SiC formation process was studied by optical microscopy and quantitative digital image analysis. This study identified six reaction stages and provided important understanding of the process. Although the thermal conductivity of pure SiC at elevated temperatures is very high, thermal conductivities of most commercial SiC materials are much lower due to phonon scattering by impurities (e.g., sintering aids located at the grain boundaries of these materials). The thermal conductivity of our SiC was determined using the laser flash method and it is 214 W/mK at 373 K and 64 W/mK at 1273 K. These values are very close to those of pure SiC and are much higher than those of SiC materials made by industrial processes. This SiC made by our LSI process meets the thermal properties required for use in high temperature heat exchanger. Cellulose and phenolic resin carbons lack the well-defined atomic structures associated with common carbon allotropes. Atomic-scale structure was studied using high resolution transmission electron microscopy (HRTEM), nitrogen gas adsorption and helium gas pycnometry. These studies revealed that cellulose carbon exhibits a very high degree of atomic disorder and angstrom-scale porosity. It has a density of only 93% of that of pure graphite, with primarily sp2 bonding character and a low concentration of graphene clusters. Phenolic resin carbon shows more structural order and substantially less angstrom-scale porosity. Its density is 98% of that of pure graphite, and Fourier transform analysis of its TEM micrographs has revealed high concentrations of sp3 diamond and sp2 graphene nano-clusters. This is the first time that diamond nano-clusters have been observed in carbons produced from phenolic resin. AC and DC electrical measurements were made to follow the thermal conversion of microcrystalline cellulose to carbon. This study identifies five regions of electrical conductivity that can be directly correlated to the chemical decomposition and microstructural evolution during carbonization. In Region I, a decrease in overall AC conductivity occurs due to the initial loss of the polar groups from cellulose molecules. In Region II, the AC conductivity starts to increase with heat treatment temperature due to the formation and growth of conducting carbon clusters. In Region III, a further increase of AC conductivity with increasing heat treatment temperature is obs

  15. A Plastic-Core Compact Heat Exchanger for Energy Conservation 

    E-print Network

    Lazaridis, A.; Rafailidis, E.

    1995-01-01

    capacity rate, in which m is mass flow rate, c p is specific heat capacity at constant pressure, and Equation (2) is the effectiveness of the exchanger given by a function of two parameters, the ratio of the minimum to the maximum heat capacity rates... transfer in a heat exchanger, which in the effectiveness-NTU method takes the fonn of Equation (I) where the subscripts h, c, and i stand for hot, cold, and inlet conditions, respectively, T represents temperature, C min = (mcp)min is the minimum heat...

  16. A Simplified Procedure for Sizing Vertical Ground Coupled Heat Pump Heat Exchangers for Residences in Texas 

    E-print Network

    O'Neal, D. L.; Gonzalez, J. A.; Aldred, W.

    1994-01-01

    , ground thermal properties (density, thermal conductivity, and specific heat), and outdoor weather. A set of sizing charts were developed from the model runs that could provide quick reference on the size of the ground heat exchanger. Corrections...

  17. Heat Transfer of a Multiple Helical Coil Heat Exchanger Using a Microencapsulated Phase Change Material Slurry

    E-print Network

    Gaskill, Travis

    2012-02-14

    The present study has focused on the use of coil heat exchangers (CHEs) with microencapsulated phase change material (MPCM) slurries to understand if CHEs can yield greater rates of heat transfer. An experimental study was conducted using a...

  18. Various methods to improve heat transfer in exchangers

    NASA Astrophysics Data System (ADS)

    Pavel, Zitek; Vaclav, Valenta

    2015-05-01

    The University of West Bohemia in Pilsen (Department of Power System Engineering) is working on the selection of effective heat exchangers. Conventional shell and tube heat exchangers use simple segmental baffles. It can be replaced by helical baffles, which increase the heat transfer efficiency and reduce pressure losses. Their usage is demonstrated in the primary circuit of IV. generation MSR (Molten Salt Reactors). For high-temperature reactors we consider the use of compact desk heat exchangers, which are small, which allows the integral configuration of reactor. We design them from graphite composites, which allow up to 1000°C and are usable as exchangers: salt-salt or salt-acid (e.g. for the hydrogen production). In the paper there are shown thermo-physical properties of salts, material properties and principles of calculations.

  19. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Pollutants From the Synthetic Organic Chemical Manufacturing Industry § 63.104 Heat exchange...cool process equipment in a chemical manufacturing process unit meeting...of this subpart, except for chemical manufacturing process...

  20. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Pollutants From the Synthetic Organic Chemical Manufacturing Industry § 63.104 Heat exchange...cool process equipment in a chemical manufacturing process unit meeting...of this subpart, except for chemical manufacturing process...

  1. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Pollutants From the Synthetic Organic Chemical Manufacturing Industry § 63.104 Heat exchange...cool process equipment in a chemical manufacturing process unit meeting...of this subpart, except for chemical manufacturing process...

  2. Design of cryogenic heat exchangers for a superconducting magnet

    Microsoft Academic Search

    W. A. Chrusciel; B. Y. Tao; S. A. Ventura

    1976-01-01

    Computer programs were written to design and simulate the behavior of three heat exchangers for cooling supercritical helium to approximately 4.3 k at 4 atm. Helium, at 1, 3, or 5 gm\\/sec, is cooled by passing it through 0.635-cm-diam copper tubing immersed in a liquid nitrogen bath, through a copper, concentric tube, countercurrent heat exchanger, and then through 0.635-cm copper

  3. The tribological behavior of tube supports in helium heat exchangers

    Microsoft Academic Search

    M. O. Borel; A. Corthay; H. Fischli; H. W. Fricker

    1984-01-01

    A closed-cycle gas turbine plant for high-temperature gas-cooled reactor application contains a number of heat exchangers for low to medium temperatures (up to 500°C). The tubes of these heat exchangers are held in multiple spacers. Since thermal expansions lead to relative motions between tubes and spacers, a predictable tribological behavior of this sliding pair is important. The search for a

  4. Double-tube coil heat exchangers of cryogenic helium units

    Microsoft Academic Search

    O. K. Krasnikova

    2008-01-01

    A possible way to optimize energy indices of a unit, namely, to reduce irreversible losses in heat exchangers, has been discussed\\u000a with reference to the series-made cryogenic helium unit KGU-150\\/4.5. The refrigeration cycle of the unit with reduced temperature\\u000a differences in the heat exchangers has been calculated. Energy losses in nitrogen, expansion, and throttling stages have been\\u000a analyzed. The effect

  5. Heat Exchanger Network Targeting, Design and Analysis: The MIDAS Package

    E-print Network

    Barton, I.; Jones, D. H.; Smith, G. J.

    HEAT EXCHANGER NETWORK TARGETING, DESIGN AND ANALYSIS: THE MIDAS PACKAGE I. BARTON, D.H. JONES AND G.J. SMITH TENSA Services, Houston, Texas ICI PLC, Wilton England ABSTRACT Recent work to consolidate pinch-based procedures for targeting..., design and analysis of heat exchanger networks (HENs) has focused on the production of powerful, user-friendly software. Advanced optimization techniques, such as mixed integer non linear programming, have been added to established pinch procedures...

  6. Effectiveness of crossflow plate heat exchanger for indirect evaporative cooling

    Microsoft Academic Search

    N. J. Stoitchkov; G. I. Dimitrov

    1998-01-01

    A short-cut method for calculating the effectiveness of wet surface crossflow plate heat exchangers is developed. It introduces a correction for the effectiveness estimated according to the method of Maclaine-cross and Banks. For this purpose a new model with a water film that flows down, corresponding to the real conditions in these heat exchangers, is developed. The method of Maclaine-cross

  7. Design of chemical reactors of the heat exchanger type

    E-print Network

    McBeth, Lloyd Theodore

    1956-01-01

    DESIGN OF CHEMICAL REACTORS OF THE HEAT EXCHANGER TYPE A Thesis By LLOYD THEODORE MCBETH Submitted to the Graduate School of the Agricultural and Mechanical Coliege of 'Texas in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE January 1956 Major Subject. Chemical Engineering LIBRARY S S III CSLLECE Of TEXSS DESIGN OF CHEMICAL REACTORS OF THE HEAT EXCHANGER TYPE A Thesis By LLOYD THEODORE MCBETEI Approved as to style and content by: '8 Chairman o...

  8. Progress in heat pipe and porous heat exchanger technology

    Microsoft Academic Search

    A. V. Luikov; L. L. Vasiliev

    1975-01-01

    This is a review of the papers presented at the 1st International Heat Pipe Conference held in Stuttgart, 15-17 October 1973. The review deals with heat pipe application in different branches of technology, heat- and mass-transfer processes in heat pipes, design of variable-conductance heat pipes, optimization of their parameters, operation of heat pipes under weightlessness and in the field of

  9. Heat transfer in the plate heat exchanger of an ammonia-synthesis column

    Microsoft Academic Search

    Y. G. Obolentsev; M. S. Chus; O. A. Norobchanskii; Y. S. Teplitshi; L. L. Tovazhnyanskii

    1983-01-01

    The planning and construction of high-capacity synthetic ammonia plants requires the development and fabrication of unique, high unit-power equipment with high technical and economic characteristics. In foreign and domestic practice, tubular heat exchangers with relatively low heat-transfer coefficients are used. Plate heat exchangers are a promising alternative. They are compact and have a high heat energy efficiency and a relatively

  10. Advances in Science and Technology of Compact Heat Exchangers

    Microsoft Academic Search

    Ramesh K. Shah

    2006-01-01

    Significant advances have taken place in the theory, analysis, design and optimization, manufacturing, and technology of compact heat exchangers (CHEs) over the last 20–25 years. The objective of this D. Q. Kern Award paper is to summarize and assess (where appropriate) these advances in CHEs related to the following specific areas of CHEs: (1) advances in two-fluid exchanger effectiveness and

  11. The heat pipe heat exchanger: a review of its status and its potential for coolness recovery in tropical buildings

    Microsoft Academic Search

    YH Yau

    2008-01-01

    The heat pipe heat exchanger (HPHX) is a proven device for heat recovery in HVAC systems, and competes effectively with other available systems such as heat recovery wheels and run-around coils. This paper reviews major research work done on heat pipe heat exchangers (HPHXs) installed in HVAC systems since 1970. It reveals that research work on HPHXs for HVAC heat

  12. Brazed aluminum, Plate-fin heat exchangers for OTEC

    SciTech Connect

    Foust, H.D.

    1980-12-01

    Brazed aluminum plate-fin heat exchangers have been available for special applications for over thirty years. The performance, compactness, versatility, and low cost of these heat exchangers has been unequaled by other heat exchanger configuration. The application of brazed aluminum has been highly limited because of necessary restrictions for clean non-corrosive atmospheres. Air and gas separation have provided ideal conditions for accepting brazed aluminum and in turn have benefited by the salient features of these plate-fin heat exchangers. In fact, brazed aluminum and cryogenic gas and air separation have become nearly synonymous. Brazed aluminum in its historic form could not be considered for a seawater atmosphere. However, technology presents a new look of significant importance to OTEC in terms of compactness and cost. The significant technological variation made was to include one-piece hollow extensions for the seawater passages. Crevice corrosion sites are thereby entirely eliminated and pitting corrosion attack will be controlled by an integral and sacrificial layer of a zinc-aluminum alloy. This paper on brazed aluminum plate-fin heat exchangers for OTEC will aquaint the reader with the state-of-art and variations suggested to qualify this form of aluminum for seawater use. In order to verify the desirable cost potential for OTEC, Trane teamed with Westinghouse to perform an OTEC system analysis with this heat exchanger. These results are very promising and reported in detail elsewhere.

  13. Retrofit of heat exchanger networks based on detailed match calculations

    SciTech Connect

    Carlsson, A.; Berntsson, T. [Chalmers Univ. of Technology, Gothenburg (Sweden). Dept. of Heat and Power Technology

    1995-12-31

    Retrofit of heat exchanger networks is an important area of process design, not only as a means of improving the energy efficiency of a process, but also when modifying a process for other purposes, which affect the conditions of the existing network. Several approaches have been developed for the design of heat exchanger networks in grass root systems. However, these methods are not directly applicable in retrofit situations. In retrofitting of heat exchanger networks, the relative importance of various parameters, such as distance between streams, material requirements, and pressure drop costs, differ compared with grass root design and other approaches are necessary. This paper presents a method that takes the above mentioned aspects into account. Its most interesting application is in retrofit of heat exchanger networks. Another important feature of this method is the possibility of calculating the design of each match as optimally as possible concerning pressure drop and heat exchanger area. It is also possible to take into account restrictions concerning pressure drop and free available pressure drops of the streams. A case study is included based on data from a pulp and paper mill to study the impact of the parameters mentioned above. The most important parameters identified was the heat exchanger area and piping costs. Pressure drop costs contributed by about 15% of the total cost.

  14. SAFE Reactor Brayton Cycle Primary Heat Exchangers

    Microsoft Academic Search

    Robert S. Reid; Michael G. Houts

    2002-01-01

    Gas cooling of power-dense nuclear reactor cores can produce large thermal and stress gradients through sensible temperature changes in the coolant. In-core heat pipes remove heat isothermally and reduce the severity of these gradients. The modular SAFE reactor concept consists of numerous heat pipes that permit core re-assembly during test and preflight integration. The redundancy inherent in the modular heat

  15. HEAT EXCHANGER DESIGN STUDIES FOR AN LHC INNER TRIPLET UPGRADE

    SciTech Connect

    Rabehl, R. J.; Huang, Y. [Fermi National Accelerator Laboratory Batavia, Illinois, 60510 (United States)

    2008-03-16

    A luminosity upgrade of the CERN Large Hadron Collider (LHC) is planned to coincide with the expected end of life of the existing inner triplet quadrupole magnets. The upgraded inner triplet will have much larger heat loads to be removed from the magnets by the cryogenics system. A number of cryogenics design studies have been completed under the LHC Accelerator Research Program (LARP), including investigations of required heat exchanger characteristics to transfer this heat from the pressurized He II bath to the saturated He II system. This paper discusses heat exchangers both external to the magnet cold mass and internal to the magnet cold mass. A possible design for a heat exchanger external to the magnet cold mass is also presented.

  16. Design issues of a thermoacoustic refrigerator and its heat exchangers

    SciTech Connect

    Wetzel, M.; Herman, C. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Mechanical Engineering

    1996-12-31

    Thermoacoustic refrigeration is a fast advancing new refrigeration technology. Performance calculations indicate remarkable values for the thermoacoustic core of a thermoacoustic refrigerator. The thermoacoustic core is responsible for pumping heat from a cold to a hot temperature reservoir. However, the systems necessary to support the thermoacoustic core, such as heat exchangers and acoustic drivers are the weak points of this refrigeration technology. Particularly, heat exchangers were designed so far without any optimization. A reason for this is the lack of knowledge of the flow structures and heat transfer phenomena at the interface between the thermoacoustic core and the heat exchangers. For the purpose of gaining better insight, the authors built a thermoacoustic refrigerator model and applied visualization techniques, such as smoke injection and holographic interferometry, to visualize the flow and temperature fields at the interface.

  17. Heat Exchanger Fouling- Prediction, Measurement and Mitigation 

    E-print Network

    Peterson, G. R.

    1989-01-01

    of an industrial gas stream and to derive the fouling thermal resistance. The probe is a hollow metal cylinder capable of measuring the average heat flux along the length of the tube. The local heat flux is also measured by a heat flux meter embedded in the probe...

  18. Fan-less heat exchanger concept for CO 2 heat pump systems

    Microsoft Academic Search

    Petter Nekså; Rune L. Hoggen; Kåre Aflekt; Arne Jakobsen; Geir Skaugen

    2005-01-01

    A novel system for space heating has been developed taking advantage of the favourable characteristics of the transcritical CO2 cycle, where heat is rejected by cooling of supercritical gas at gliding temperature. By a proper design of a counter flow heat exchanger it is possible to heat air to high temperatures and thereby giving the driving force for circulation of

  19. Design Development Analyses in Support of a Heat pipe-Brayton Cycle Heat Exchanger

    Microsoft Academic Search

    Brian E. Steeve; Richard J. Kapernick

    2004-01-01

    One of the power systems under consideration for future space exploration applications, including nuclear electric propulsion or as a planetary surface power source, is a heat pipe-cooled reactor coupled to a Brayton cycle. In this system, power is transferred from the heat pipes to the Brayton gas via a heat exchanger attached to the heat pipes. This paper discusses the

  20. Heat Transfer of a Multiple Helical Coil Heat Exchanger Using a Microencapsulated Phase Change Material Slurry 

    E-print Network

    Gaskill, Travis

    2012-02-14

    sides, respectively. The NTU-effectiveness relationship of the CHE when MPCM fluid is used approaches that of a heat exchanger with a heat capacity ratio of zero. The heat transfer results have shown that when using a MPCM slurry, an increase in heat...

  1. Assessment of ASME code examinations on regenerative, letdown and residual heat removal heat exchangers

    SciTech Connect

    Gosselin, Stephen R.; Cumblidge, Stephen E.; Anderson, Michael T.; Simonen, Fredric A.; Tinsley, G. A.; Lydell, B.; Doctor, Steven R.

    2005-07-01

    Inservice inspection requirements for pressure retaining welds in the regenerative, letdown, and residual heat removal heat exchangers are prescribed in Section XI Articles IWB and IWC of the ASME Boiler and Pressure Vessel Code. Accordingly, volumetric and/or surface examinations are performed on heat exchanger shell, head, nozzle-to-head, and nozzle-to-shell welds. Inspection difficulties associated with the implementation of these Code-required examinations have forced operating nuclear power plants to seek relief from the U.S. Nuclear Regulatory Commission. The nature of these relief requests are generally concerned with metallurgical, geometry, accessibility, and radiation burden. Over 60% of licensee requests to the NRC identify significant radiation exposure burden as the principle reason for relief from the ASME Code examinations on regenerative heat exchangers. For the residual heat removal heat exchangers, 90% of the relief requests are associated with geometry and accessibility concerns. Pacific Northwest National Laboratory was funded by the NRC Office of Nuclear Regulatory Research to review current practice with regard to volumetric and/or surface examinations of shell welds of letdown heat exchangers regenerative heat exchangers and residual (decay) heat removal heat exchangers Design, operating, common preventative maintenance practices, and potential degradation mechanisms are reviewed. A detailed survey of domestic and international PWR-specific operating experience was performed to identify pressure boundary failures (or lack of failures) in each heat exchanger type and NSSS design. The service data survey was based on the PIPExp® database and covers PWR plants worldwide for the period 1970-2004. Finally a risk assessment of the current ASME Code inspection requirements for residual heat removal, letdown, and regenerative heat exchangers is performed. The results are then reviewed to discuss the examinations relative to plant safety and occupational radiation exposures.

  2. Experimental Performance of R-134a-Filled and Water-Filled Loop Heat Pipe Heat Exchangers

    Microsoft Academic Search

    K. S. Ong

    2010-01-01

    Experimental investigations were conducted to determine the thermal performances of an R-134a-filled thermosyphon heat pipe heat exchanger (THPHE) and a water-filled loop heat pipe heat exchanger (LHPHE) for hot and cold energy recovery for air conditioning purposes. For such applications, the heat pipe heat exchangers are operated at low temperatures. Both exchangers were operated in the countercurrent flow mode. This

  3. Self-defrosting recuperative air-to-air heat exchanger

    DOEpatents

    Drake, R.L.

    1993-12-28

    A heat exchanger is described which includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications. 3 figures.

  4. MEE 452: Example 3-2 ShellShell--andand--Tube Heat Exchanger Analysis:Tube Heat Exchanger Analysis

    E-print Network

    Kostic, Milivoje M.

    MEE 452: Example 3-2 ShellShell--andand--Tube Heat Exchanger Analysis:Tube Heat Exchanger Analysis] Counter-flow single-pass: 80 copper tubes 1 in no 18 BWG inCounter-flow, single-pass: 80 copper tubes, 1 tubes along C.L. Shell fluid: 50,000 lbm/hr water @50oF in. Tube (hot) fluid: 66,000 lbm/hr n

  5. TRANSFER OF HEAT FROM HELIUM AT HIGH TEMPERATURES. PHYSICAL CHARACTERISTICS OF CERAMIC HEAT EXCHANGERS

    Microsoft Academic Search

    J. S. Sebastian; S. C. Browning

    1962-01-01

    A laboratory-scale investigation was made concerning the development of ; a ceramic heat exchanger to operate at high temperatures with He. It was found ; that the techical feasibility of using such heat exchangers at high pressures ; depends primarily on development of reliable gas-tight seals and the elimination ; of high thermal stresses. (J.R.D.);

  6. A review of metal foam and metal matrix composites for heat exchangers and heat sinks

    Microsoft Academic Search

    Xiao-hong Han; Qin Wang; Young-Gil Park; Christophe T’Joen; Andrew Sommers; Anthony Jacobi

    2012-01-01

    Recent advances in manufacturing methods open the possibility for broader use of metal foams and metal matrix composites (MMCs) for heat exchangers, and these materials can have tailored material properties. Metal foams in particular combine a number of interesting properties from a heat exchanger's point of view. In this paper, the material properties of metal foams and MMCs are surveyed,

  7. GAS COOLED, MOLTEN SALT HEAT EXCHANGER--DESIGN STUDY

    Microsoft Academic Search

    MacPherson

    1958-01-01

    BS> One of the major problems in the economic evaluation of the ; application of forced circulation, gas cooling to high temperature, molten salt ; power reactor systems is the definition of the required heat transfer equipment, ; its size and operating cost. A design study of the saltto-gas heat exchangers ; for such a gas-cooled system has recently been

  8. Evaluation of porous media heat exchangers for plasma facing components

    Microsoft Academic Search

    J. Rosenfeld; J. Lindemuth

    1993-01-01

    Several types of porous media heat exchangers are being evaluated for use in cooled plasma-facing components. Monel\\/water thermosyphon heat pipes with a porous metal wick are being evaluated for use in Faraday shields. A subscale prototype has been fabricated, and tests at Oak Ridge National Laboratory are being planned. An advanced gyrotron microwave cavity is being developed which uses water

  9. Modeling of Frost Growth on Heat Exchanger Surfaces

    Microsoft Academic Search

    Katrin Prolss; Gerhard Schmitz

    2006-01-01

    A Modelica model to study the frost growth on paral- lel heat exchanger plates is developed. The coupled heat and mass transport phenomena involved in the process are described. A physical model which in- cludes the distributed densification of the frost layer is compared to a simple lumped model approach. The frost structure and thus the resulting properties such as

  10. Heat Exchanger Technologies for Distillation Columns 

    E-print Network

    Polley, G. T.

    2002-01-01

    component rather than the mixture bubble point (assumed with the 'integral' assumption) (Figure 2). ITvapoUT I [./"-------' Where separation occurs, part of the bundle is 'submerged' in condensate. This 'subennergence' can give rise to significant... should be given a downward incline of 3-SO. Intermediate Condensers The extraction of heat from an intermediate point in a distillation column as heat source for a heat pump or for use in an integration scheme can result in significant energy...

  11. Hydraulic and thermal design of a gas microchannel heat exchanger

    NASA Astrophysics Data System (ADS)

    Yang, Yahui; Brandner, Juergen J.; Morini, Gian Luca

    2012-05-01

    In this paper investigations on the design of a gas flow microchannel heat exchanger are described in terms of hydrodynamic and thermal aspects. The optimal choice for thermal conductivity of the solid material is discussed by analysis of its influences on the thermal performance of a micro heat exchanger. Two numerical models are built by means of a commercial CFD code (Fluent). The simulation results provide the distribution of mass flow rate, inlet pressure and pressure loss, outlet pressure and pressure loss, subjected to various feeding pressure values. Based on the thermal and hydrodynamic analysis, a micro heat exchanger made of polymer (PEEK) is designed and manufactured for flow and heat transfer measurements in air flows. Sensors are integrated into the micro heat exchanger in order to measure the local pressure and temperature in an accurate way. Finally, combined with numerical simulation, an operating range is suggested for the present micro heat exchanger in order to guarantee uniform flow distribution and best thermal and hydraulic performances.

  12. Wall mounted heat exchanger characterization. [cryogenic propellant tanks

    NASA Technical Reports Server (NTRS)

    Bullard, B. R.

    1975-01-01

    Analytical models are presented for describing the heat and mass transfer and the energy distribution in the contents of a cryogenic propellant tank, under varying gravity levels. These models are used to analytically evaluate the effectiveness of a wall heat exchanger as a means of controlling the pressure in the tank during flight and during fill operations. Pressure and temperature histories are presented for tanks varying in size from 4 to 22.5 feet in diameter and gravity levels from 0-1. Results from the subscale test program, utilizing both non-cryogenic and cryogenic fluid, designed to evaluate a tank wall heat exchanger are described and compared with the analytical models. Both the model and test results indicate that a passive tank wall heat exchanger can effectively control tank pressure. However, the weight of such a system is considerably higher than that of an active mixer system.

  13. 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

  14. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, P.R.; McLennan, G.A.

    1984-08-30

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  15. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, Paul R. (Western Springs, IL); McLennan, George A. (Downers Grove, IL)

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  16. Fast reactor power plant design having heat pipe heat exchanger

    Microsoft Academic Search

    Paul R. Huebotter; George A. McLennan

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water\\/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the

  17. Fast reactor power plant design having heat pipe heat exchanger

    Microsoft Academic Search

    P. R. Huebotter; G. A. McLennan

    1984-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water\\/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the

  18. Advanced heat-pipe heat exchanger and microprocessor-based modulating burner controls development

    Microsoft Academic Search

    A. Lowenstein; B. Cohen; S. Feldman; M. Spatz; E. Smith

    1986-01-01

    The development of a novel condensing heat exchanger, a modulating gas burner, and a zone-controlled residential warm-air heating system is described. The condensing heat exchanger uses ten thermosyphons which are manifolded at both the condenser and evaporator ends to achieve a compact low-cost design. Initial tests have demonstrated a + 92 percent steady-state efficiency for a conventional clamshell furnace operating

  19. Assessment of ASME code examinations on regenerative, letdown and residual heat removal heat exchangers

    Microsoft Academic Search

    Stephen R. Gosselin; Stephen E. Cumblidge; Michael T. Anderson; Fredric A. Simonen; G. A. Tinsley; B. Lydell; Steven R

    2005-01-01

    Inservice inspection requirements for pressure retaining welds in the regenerative, letdown, and residual heat removal heat exchangers are prescribed in Section XI Articles IWB and IWC of the ASME Boiler and Pressure Vessel Code. Accordingly, volumetric and\\/or surface examinations are performed on heat exchanger shell, head, nozzle-to-head, and nozzle-to-shell welds. Inspection difficulties associated with the implementation of these Code-required examinations

  20. Effect of nanoparticles on heat transfer in mini double-pipe heat exchangers in turbulent flow

    NASA Astrophysics Data System (ADS)

    Aghayari, Reza; Maddah, Heydar; Ashori, Fatemeh; Hakiminejad, Afshin; Aghili, Mehdi

    2015-03-01

    In this work, heat transfer of a fluid containing nanoparticles of aluminum oxide with the water volume fraction (0.1-0.3) percent has been reported. Heat transfer of the fluid containing nano water aluminum oxide with a diameter of about 20 nm in a horizontal double pipe counter flow heat exchanger under turbulent flow conditions was studied. The results showed that the heat transfer of nanofluid in comparison with the heat transfer of fluid is slightly higher than 12 percent.

  1. Dealing with Uncertainties During Heat Exchanger Design 

    E-print Network

    Polley, G. T.; Pugh, S. J.

    2001-01-01

    heat capacity flow rate of 30 kW/K. The cold stream flowing through E I bas a heat capacity flow rate of 55 kW/K and that flowing through E2 a value of 35 kW/K. 123 ESL-IE-01-05-20 Proceedings from the Twenty-third National Industrial Energy...) Flowrate kg}s 100 87.5 Heat capacity Jlkl/:.K 2000 2000 Heat capacity flowrate, CP kW/K 200 175 Inlet Temperature ?C 220 80 Outlet Temperature ?C 180.7 125 Foulinl/: Resistance m 2 KIW 0.0005 0.0001 Min. Vel. '", ":"'~ ," TwesIdeP.o. -Shelside p...

  2. Comparison of Correction Factors for Shell-and-Tube Heat Exchangers with Segmental or Helical Baffles

    Microsoft Academic Search

    P. Stehlík; J. Nemcanský; D. Kral; L. W. Swanson

    1994-01-01

    Heat transfer and pressure drop correction factors based on the Bell-Delaware method have been compared for an optimized segmental baffle heat exchanger and a helical baffle heat exchanger. In general, the results showed that properly designed helical baffles offer a significant improvement in heat transfer while providing a reduced exchanger pressure drop. The enhancement in heat transfer for helical baffles

  3. Light bulb heat exchanger for magnetohydrodynamic generator applications - Preliminary evaluation

    NASA Technical Reports Server (NTRS)

    Smith, J. M.; Hwang, C. C.; Seikel, G. R.

    1974-01-01

    The light-bulb heat-exchanger concept is investigated as a possible means of using a combustion heat source to supply energy to an inert gas MHD power generator system. In this concept, combustion gases flow through a central passage which consists of a duct with transparent walls through which heat is transferred by radiation to a radiation receiver which in turn heats the inert gas by convection. The effects of combustion-gas emissivity, transparent-wall-transmissivity, radiation-receiver emissivity, and the use of fins in the inert gas coolant passage are studied. The results indicate that inert gas outlet temperatures of 2500 K are possible for combustion temperatures of 3200 K and that sufficient energy can be transferred from the combustion gas to reduce its temperature to approximately 2000 K. At this temperature more conventional heat exchangers can be used.

  4. System design package: Maxi-therm S-101 heating module, passive heat exchanger

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This document is the specification which establishes the requirements for the design, installation, and performance of a passive heat exchanger module with auxiliary heaters for use with solar heating systems. It designates the Interim Performance Criteria applicable to the subsystem and defines any deviations. This document also includes the manufacturing instructions and required materials and parts for the Maxitherm S101 Heating Module.

  5. Efficiency of vertical geothermal heat exchangers in the ground source heat pump system

    NASA Astrophysics Data System (ADS)

    Zeng, Heyi; Diao, Nairen; Fang, Zhaohong

    2003-02-01

    Taking the fluid temperature distribution along the borehole depth into account, a new quasi-three-dimensional model for vertical ground heat exchangers has been established, which provides a better understanding of the heat transfer processes in the geothermal heat exchangers. On this basis the efficiency of the borehole has been defined and its analytical expression derived. Comparison with the previous two-dimensional model shows that the quasi-three-dimensional model is more rational and more accurate to depict the practical feature of the conduction of geothermal heat exchanger, and the efficiency notion can be easily used to determine the inlet and outlet temperature of the circulating fluid inside the heat exchanger.

  6. Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Taler, Dawid; Sury, Adam

    2011-12-01

    The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.

  7. Electrically enhanced fluidized bed heat exchanger

    SciTech Connect

    Lessor, D.L.; Robertus, R.J.; Roberts, G.L.

    1994-05-01

    The experiments have shown that a high level of electrical charging can be achieved in a fluidized bed of two resistive particle types; that bed stabilization rather than increased sensible heat transport dominates low frequency electric field effects on heat transfer with most bed loadings; and, hence, that applying an oscillatory potential difference between tubes or rods in a fluidized bed of two mutual contact-charging particle species gives reduced rather than improved heat transfer. Applying an oscillatory potential difference between rods in a bed of quartz particles fluidized alone did give improved heat transfer, however. With no electric field applied, most fluidized mixes were found to give higher heat transfer rates than the average of the values when each of the two species was fluidized alone. The high level of charging observed in some mixed beds may prove of interest for some air cleanup applications; the results show that simultaneous fluidization of pairs of bipolar charging materials of similar particle size is possible without excessive agglomeration. This would be important for air cleanup.

  8. Dynamic tube/support interaction in heat exchanger tubes

    SciTech Connect

    Chen, S.S.

    1991-01-01

    The supports for heat exchanger tubes are usually plates with drilled holes; other types of supports also have been used. To facilitate manufacture and to allow for thermal expansion of the tubes, small clearances are used between tubes and tube supports. The dynamics of tube/support interaction in heat exchangers is fairly complicated. Understanding tube dynamics and its effects is important for heat exchangers. This paper summarizes the current state of the art on this subject and to identify future research needs. Specifically, the following topics are discussed: dynamics of loosely supported tubes, tube/support gap dynamics, tube response in flow, tube damage and wear, design considerations, and future research needs. 55 refs., 1 fig.

  9. Flow-induced vibration of component cooling water heat exchangers

    SciTech Connect

    Yeh, Y.S.; Chen, S.S. (Taiwan Power Co., Taipei (Taiwan). Nuclear Engineering Dept.; Argonne National Lab., IL (USA))

    1990-01-01

    This paper presents an evaluation of flow-induced vibration problems of component cooling water heat exchangers in one of Taipower's nuclear power stations. Specifically, it describes flow-induced vibration phenomena, tests to identify the excitation mechanisms, measurement of response characteristics, analyses to predict tube response and wear, various design alterations, and modifications of the original design. Several unique features associated with the heat exchangers are demonstrated, including energy-trapping modes, existence of tube-support-plate (TSP)-inactive modes, and fluidelastic instability of TSP-active and -inactive modes. On the basis of this evaluation, the difficulties and future research needs for the evaluation of heat exchangers are identified. 11 refs., 19 figs., 3 tabs.

  10. Exergy optimization in a steady moving bed heat exchanger.

    PubMed

    Soria-Verdugo, A; Almendros-Ibáñez, J A; Ruiz-Rivas, U; Santana, D

    2009-04-01

    This work provides an energy and exergy optimization analysis of a moving bed heat exchanger (MBHE). The exchanger is studied as a cross-flow heat exchanger where one of the phases is a moving granular medium. The optimal MBHE dimensions and the optimal particle diameter are obtained for a range of incoming fluid flow rates. The analyses are carried out over operation data of the exchanger obtained in two ways: a numerical simulation of the steady-state problem and an analytical solution of the simplified equations, neglecting the conduction terms. The numerical simulation considers, for the solid, the convection heat transfer to the fluid and the diffusion term in both directions, and for the fluid only the convection heat transfer to the solid. The results are compared with a well-known analytical solution (neglecting conduction effects) for the temperature distribution in the exchanger. Next, the analytical solution is used to derive an expression for the exergy destruction. The optimal length of the MBHE depends mainly on the flow rate and does not depend on particle diameter unless they become very small (thus increasing sharply the pressure drop). The exergy optimal length is always smaller than the thermal one, although the difference is itself small. PMID:19426351

  11. Performance of a Thermoelectric Device with Integrated Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Barry, Matthew M.; Agbim, Kenechi A.; Chyu, Minking K.

    2015-06-01

    Thermoelectric devices (TEDs) convert heat directly into electrical energy, making them well suited for waste heat recovery applications. An integrated thermoelectric device (iTED) is a restructured TED that allows more heat to enter the p-n junctions, thus producing a greater power output . An iTED has heat exchangers incorporated into the hot-side interconnectors with flow channels directing the working fluid through the heat exchangers. The iTED was constructed of p- and n-type bismuth-telluride semiconductors and copper interconnectors and rectangular heat exchangers. The performance of the iTED in terms of , produced voltage and current , heat input and conversion efficiency for various flow rates (), inlet temperatures (C) ) and load resistances () with a constant cold-side temperature ( = 0C) was conducted experimentally. An increase in had a greater effect on the performance than did an increase in . A 3-fold increase in resulted in a 3.2-, 3.1-, 9.7-, 3.5- and 2.8-fold increase in and respectively. For a constant of 50C, a 3-fold increase in from 3300 to 9920 resulted in 1.6-, 1.6-, 2.6-, 1.5- and 1.9-fold increases in , , , and respectively.

  12. DOE/ANL/HTRI heat exchanger tube vibration data bank

    SciTech Connect

    Halle, H.; Chenoweth, J.M.; Wambsganss, M.W.

    1980-02-01

    Development of a new heat exchanger tube vibration data bank at Argonne National Laboratory is described. Comprehensive case histories on heat exchangers that have experienced tube-vibration problems and units that have been trouble-free are accumulated and this information is rendered available for evaluation, improvement, and development of vibration-prediction methods and design guidelines. Discussions include difficulties in generating a data bank, data form development, and solicitation efforts. Also included are 15 case histories upon which the data bank will be built. As new case histories are received, they will be assembled and published as addenda to this report.

  13. Internal dust recirculation system for a fluidized bed heat exchanger

    DOEpatents

    Gamble, Robert L. (Wayne, NJ); Garcia-Mallol, Juan A. (Morristown, NJ)

    1981-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

  14. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    SciTech Connect

    Mittereder, N.; Poerschke, A.

    2013-11-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season. Upon completion of the monitoring phase, measurements revealed that the initial TRNSYS simulated horizontal sub-slab ground loop heat exchanger fluid temperatures and heat transfer rates differed from the measured values. To determine the cause of this discrepancy, an updated model was developed utilizing a new TRNSYS subroutine for simulating sub-slab heat exchangers. Measurements of fluid temperature, soil temperature, and heat transfer were used to validate the updated model.

  15. Design Development Analyses in Support of a Heat pipe-Brayton Cycle Heat Exchanger

    SciTech Connect

    Steeve, Brian E. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Kapernick, Richard J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2004-07-01

    One of the power systems under consideration for future space exploration applications, including nuclear electric propulsion or as a planetary surface power source, is a heat pipe-cooled reactor coupled to a Brayton cycle. In this system, power is transferred from the heat pipes to the Brayton gas via a heat exchanger attached to the heat pipes. This paper discusses the fluid, thermal and structural analyses that were performed in support of the design of the heat exchanger to be tested in the SAFE-100 experimental program at the Marshall Space Flight Center. An important consideration throughout the design development of the heat exchanger was its capability to be utilized for higher power and temperature applications. This paper also discusses this aspect of the design and presents designs for specific applications that are under consideration. (authors)

  16. Most Frequently Used Heat Exchangers from Pioneering Research to Worldwide Applications

    Microsoft Academic Search

    B. I. Master; K. S. Chunangad; A. J. Boxma; D. Kral; P. Stehlík

    2006-01-01

    Heat exchangers contribute significantly to many energy conversion processes. Applications range from power production, petroleum refining and chemicals, paper and pharmaceutical production, to aviation and transportation industries. A large percentage of world market for heat exchangers is served by the industry workhorse, the shell-and-tube heat exchanger. Recent developments in other exchanger geometries have penetrated in various industry applications; however, the

  17. The Direct Contact Heat Exchanger: Experiences on Ice Slurry Production

    Microsoft Academic Search

    Raksit Thitipatanapong; Bundit Limmeechokchai

    An experimental pilot scale of direct contact heat exchanger (DCHE) for ice slurry production was fabricated and evaluated. The study investigated the DCHE of Ø114mm and 1000 mm height using evaporated refrigerant as disperse phase and solidified water as continuous phase. The heat transfer rate across the DCHE was varied between 3.0 and 6.5 kW while the water flow rate

  18. Analysis of ground source heat pumps with horizontal ground heat exchangers for northern Japan

    Microsoft Academic Search

    V. R. Tarnawski; W. H. Leong; T. Momose; Y. Hamada

    2009-01-01

    Computer simulation and analysis of a ground source heat pump system with horizontal ground heat exchangers operating in heating (max 5.5kW) and cooling (max 3.3kW) mode was carried out for a typical residential house, with 200m2 of living space, located in Sapporo (Japan). In spite of high electricity rate, the ground source heat pump system is more beneficial alternative for

  19. Simulation of embedded heat exchangers of solar aided ground source heat pump system

    Microsoft Academic Search

    Fang Wang; Mao-yu Zheng; Jun-peng Shao; Zhong-jian Li

    2008-01-01

    Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established.\\u000a In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored\\u000a in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the

  20. Comparative study of rotating regenerators and heat-pipe heat exchangers

    NASA Astrophysics Data System (ADS)

    MacMichael, D. B. A.; Reay, D. A.; Foster, E. L.

    1980-07-01

    A heat wheel was purchased and installed for air to air heat recovery on a Terylene fiber drying and setting oven at ICI Wilton. At the same time a heat pipe heat exchanger was prepared at IRD and tested under controlled conditions. The heat wheel was then replaced by the heat pipe unit. During this procedure measurements were made regularly to monitor the performance of the oven and the heat exchangers. Neither of the heat exchangers attained their rated conditions. It was concluded that recuperative energy conservation is technically and economically feasible, provided that attention is paid to the problems of air flow control and minimizing installation costs. It was also realized that a good saving could be made by paying attention to stray leaks from the oven and by reducing the exhaust air flow from the setting sections. On the question of comparative performance of the two heat exchangers it is not possible to propose that one type is preferable to the other, although the heat wheel created more problems in respect of maintaining airflow.

  1. Heat transfer and pressure drop characteristics of a plate heat exchanger 

    E-print Network

    Talik, Anthony Charles

    1995-01-01

    -transfer and pressure-drop data for a plate heat exchanger with water and a propylene-glycol/water (95, 5%/4. 5%) mixture as the working fluids. The plate heat exchanger was composed of 31 plates, each with a chevron angle of 30 degrees. All of the water data were... taken in the high Reynolds number range of 1450 to 11, 000 with heat-transfer rates of 6. 6 x 10' to 2. 2 x 10' W. All of the propylene-glycol data were taken in the low Reynolds number range of 10 to 720 with heat-transfer rates of 1. 1 x 10' to 6. 4...

  2. Heat transfer and friction correlations for wavy plate fin-and-tube heat exchangers

    SciTech Connect

    Kim, N.H. [Univ. of Inchon (Korea, Republic of). Dept. of Mechanical Engineering; Youn, J.H. [Korea Academy of Industrial Technology, Seoul (Korea, Republic of); Webb, R.L. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical Engineering

    1996-12-31

    This paper deals with heat exchangers having plate fins of herringbone wave configuration. Correlations are developed to predict the air-side heat transfer coefficient and friction factor as a function of flow conditions and geometric variables of the heat exchanger. Correlations are provided for both staggered and in-line arrays of circular tubes. A multiple regression technique was used to correlate 41 wavy fin geometries by Beecher and Fagan (1987), Wang et al. (1995) and Beecher (1968). For the staggered layout, 92% of the heat transfer data are correlated within {+-}10%, and 91% of the friction data are correlated within {+-}15%.

  3. Heat transfer and pressure drop characteristics of a plate heat exchanger

    E-print Network

    Talik, Anthony Charles

    1995-01-01

    -transfer and pressure-drop data for a plate heat exchanger with water and a propylene-glycol/water (95, 5%/4. 5%) mixture as the working fluids. The plate heat exchanger was composed of 31 plates, each with a chevron angle of 30 degrees. All of the water data were... taken in the high Reynolds number range of 1450 to 11, 000 with heat-transfer rates of 6. 6 x 10' to 2. 2 x 10' W. All of the propylene-glycol data were taken in the low Reynolds number range of 10 to 720 with heat-transfer rates of 1. 1 x 10' to 6. 4...

  4. CACHE: an extended BASIC program which computes the performance of shell and tube heat exchangers. [HTGR

    Microsoft Academic Search

    Tallackson

    1976-01-01

    An extended BASIC program, CACHE, has been written to calculate steady state heat exchange rates in the core auxiliary heat exchangers, (CAHE), designed to remove afterheat from High-Temperature Gas-Cooled Reactors (HTGR). Computationally, these are unbaffled counterflow shell and tube heat exchangers. The computational method is straightforward. The exchanger is subdivided into a user-selected number of lengthwise segments; heat exchange in

  5. 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.

  6. Generator-absorber-heat exchange heat transfer apparatus and method and use thereof in a heat pump

    DOEpatents

    Phillips, B.A.; Zawacki, T.S.

    1998-07-21

    Numerous embodiments and related methods for generator-absorber heat exchange (GAX) are disclosed, particularly for absorption heat pump systems. Such embodiments and related methods use, as the heat transfer medium, the working fluid of the absorption system taken from the generator at a location where the working fluid has a rich liquor concentration. 5 figs.

  7. A synthesis of fluid and thermal transport models for metal foam heat exchangers

    Microsoft Academic Search

    Shadi Mahjoob; Kambiz Vafai

    2008-01-01

    Metal foam heat exchangers have considerable advantages in thermal management and heat recovery over several commercially available heat exchangers. In this work, the effects of micro structural metal foam properties, such as porosity, pore and fiber diameters, tortuosity, pore density, and relative density, on the heat exchanger performance are discussed. The pertinent correlations in the literature for flow and thermal

  8. Use of Algorithm of Changes for Optimal Design of Heat Exchanger

    Microsoft Academic Search

    S. C. Tam; H. K. Tam; C. H. Chio; L. M. Tam

    2010-01-01

    For economic reasons, the optimal design of heat exchanger is required. Design of heat exchanger is usually based on the iterative process. The design conditions, equipment geometries, the heat transfer and friction factor correlations are totally involved in the process. Using the traditional iterative method, many trials are needed for satisfying the compromise between the heat exchange performance and the

  9. Transient response of perforated plate matrix heat exchangers

    Microsoft Academic Search

    P. Ramesh; G. Venkatarathnam

    1998-01-01

    Perforated plate matrix heat exchangers are used in a number of applications such as helium liquefiers, Joule–Thompson cryocoolers operating with pure fluids and mixtures, etc. The time taken for cool down of cryocoolers is very critical in many applications, for example, those used in mobile applications (e.g. missiles). In this paper we study the effect of different parameters on the

  10. A dynamic model for helium core heat exchangers

    Microsoft Academic Search

    W. E. Schiesser; H. J. Shih; D. G. Hartozog; D. M. Herron; D. Nahmias; W. G. Stuber; A. C. Hindmarsh

    1990-01-01

    To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core

  11. Compact heat exchangers technologies for the HTRs recuperator application

    Microsoft Academic Search

    B. Thonon; E. Breuil

    Modern HTR nuclear power plants which are now under development (projects GT-MHR, PBMR) are based on the direct cycle concept. This concept leads to a more important efficiency compared to the steam cycle but requires the use of high performance components such as an helium\\/helium heat exchanger called recuperator to guarantee the cycle efficiency. Using this concept, a net plant

  12. Air Circulation and Heat Exchange under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim; Wheeler, Raymond; Dixon, Mike; Hillhouse, Len; Fowler, Philip

    Low pressure atmospheres were suggested for Space Greenhouses (SG) design to minimize sys-tem construction and re-supply materials, as well as system manufacturing and deployment costs. But rarified atmospheres modify heat exchange mechanisms what finally leads to alter-ations in thermal control for low pressure closed environments. Under low atmospheric pressures (e.g., lower than 25 kPa compare to 101.3 kPa for normal Earth atmosphere), convection is becoming replaced by diffusion and rate of heat exchange reduces significantly. During a period from 2001 to 2009, a series of hypobaric experiments were conducted at Space Life Sciences Lab (SLSLab) NASA's Kennedy Space Center and the Department of Space Studies, University of North Dakota. Findings from these experiments showed: -air circulation rate decreases non-linearly with lowering of total atmospheric pressure; -heat exchange slows down with pressure decrease creating risk of thermal stress (elevated leaf tem-peratures) for plants in closed environments; -low pressure-induced thermal stress could be reduced by either lowering system temperature set point or increasing forced convection rates (circulation fan power) within certain limits; Air circulation is an important constituent of controlled environments and plays crucial role in material and heat exchange. Theoretical schematics and mathematical models are developed from a series of observations. These models can be used to establish optimal control algorithms for low pressure environments, such as a space greenhouse, as well as assist in fundamental design concept developments for these or similar habitable structures.

  13. Failure Pressure Assessment of the Circumferentially Flawed Heat Exchanger Tubes

    Microsoft Academic Search

    Hyun Su Kim; Tae Eun Jin; Yoon Suk Chang; Young Jin Kim; Hong Deok Kim

    2008-01-01

    Since the structural integrity of thin-walled tubes in the heat exchanger is crucial from the viewpoint of safety and reliability, the integrity evaluation for flawed tubes is quite important. Accurate estimation of the failure pressure is a key element of the structural integrity assessment. With regard to the prediction of the failure pressure, most of preceding researches have been focused

  14. Condensing Heat Exchanger for Optimization of Energy Efficiency 

    E-print Network

    Carrigan, J. F.; Johnson, D. W.; DiVitto, J. G.; Schulze, K. H.

    1995-01-01

    Historically, boiler efficiency has been limited due to the minimum temperature allowed at the stack. Heat lost up the stack was in exchange for keeping the flue gas temperature above the water vapor dew point. If water vapor was allowed to condense...

  15. Flexible all-metal gaskets halt heat exchanger leakage

    Microsoft Academic Search

    M. Gambrell; W. P. Stadig

    1985-01-01

    The Oyster Creek site of Texas Operations, Dow Chemical Company in Freeport, TX, was concerned about the potential fire hazard of hydrogen and hot hydrocarbon vapors leaking past the sealing gaskets of two process heat exchangers in the phenol acetone unit. Intermittent process upsets and periodic shutdown of operations for routine maintenance subjected the conventionally gasketed surfaces of the ANSI

  16. Fouling characteristics of compact heat exchangers and enhanced tubes.

    SciTech Connect

    Panchal, C. B.; Rabas, T. J.

    1999-07-15

    Fouling is a complex phenomenon that (1) encompasses formation and transportation of precursors, and (2) attachment and possible removal of foulants. A basic understanding of fouling mechanisms should guide the development of effective mitigation techniques. The literature on fouling in complex flow passages of compact heat exchangers is limited; however, significant progress has been made with enhanced tubes.

  17. Thermodynamic optimal design of heat exchangers for an irreversible refrigerator

    Microsoft Academic Search

    Giuseppe Grazzini; Rinaldo Rinaldi

    2001-01-01

    Thermodynamic optimisation of energy systems is essential in reducing the environmental impact of energy utilisation. Yet, the refrigerators commonly used for this purpose have improvable efficiency levels. Their performance, as shown by the literature, is highly influenced by the size of the heat exchangers and by internal irreversibilities. In this paper the maximum coefficient of performance (COP) is obtained for

  18. Application of direct contact heat exchangers in geothermal systems

    Microsoft Academic Search

    I. Oliker

    1977-01-01

    Two applications of direct-contact heat exchangers (DCHs) used in geothermal systems are examined. The first type of DCH is applied to a binary cycle where a secondary fluid is vaporized in contact with the brine (direct contact evaporator). The second type of DCH is applied to a geothermal power plant operating on water vapor only (direct contact condenser); in this

  19. Potential heat exchange fluids for use in sulfuric acid vaporizers

    Microsoft Academic Search

    D. D. Lawson; G. R. Petersen

    1979-01-01

    A series of perhalocarbons are proposed as candidate heat exchange fluids for service in thermochemical cycles for hydrogen production that involve direct contact of the fluid with sulfuric acid and vaporization of the acid. The required chemical and physical criteria of the liquids are described and the results of some preliminary high temperature test data are presented.

  20. Preliminary evaluation of tubular ceramic heat exchanger materials. Final report

    Microsoft Academic Search

    D. L. Mann; K. H. Styhr

    1977-01-01

    The objective of this program was to identify promising new silicon carbide based materials, commercially available on a small scale, and to perform limited tests to obtain preliminary information on the applicability of these materials in stationary heat exchangers exposed to corrosive, high-temperature environments. Three types of alternate silicon carbide based materials were considered for evaluation: chemically vapor-deposited (CVD) silicon

  1. Polymer Heat Exchangers—History, Opportunities, and Challenges

    Microsoft Academic Search

    Juan Gabriel Cevallos; Arthur E. Bergles; Avram Bar-Cohen; Peter Rodgers; Satyandra K. Gupta

    2012-01-01

    For the past 40 years considerable attention has been devoted to the innovation, characterization, and implementation of polymer heat exchanger technology, driven by the corrosion resistance, low density, low cost, and ease of manufacture of many polymeric materials. Moreover, new polymer composites, with higher impact and yield strengths, higher temperature limits, and higher thermal conductivities, promise to bridge the performance

  2. Preliminary evaluation of tubular ceramic heat exchanger materials

    Microsoft Academic Search

    D. L. Mann; K. H. Styhr

    1977-01-01

    Promising new silicon carbide based materials were identified. Tests to obtain preliminary information on the applicability of these materials in stationary heat exchangers exposed to corrosion, high temperature environments were performed. Three types of alternate silicon carbide based materials were considered for evaluation: chemically vapor-deposited (CVD) silicon carbide (SIC); sintered silicon carbide; and composite carbon fiber reinforced, siliconized silicon carbide

  3. Opportunities for heat exchanger applications in environmental systems

    Microsoft Academic Search

    R. K. Shah; B. Thonon; D. M. Benforado

    2000-01-01

    There is a worldwide interest in using pollution prevention methods to eliminate or lessen air, water, land and thermal pollution problems. Pollution prevention is designing processes that do not create pollution in the first place. Heat exchangers play an essential role in pollution prevention and in the reduction of environmental impact of industrial processes, by reducing energy consumption or recovering

  4. NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger

    Microsoft Academic Search

    Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

    2008-01-01

    One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and\\/or oil retrieval from oil sands and oil shale to

  5. Development of a numerical model to predict heat exchange rates for a ground-source heat pump system

    Microsoft Academic Search

    Yujin Nam; Ryozo Ooka; Suckho Hwang

    2008-01-01

    Ground-source heat pump (GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump (ASHP) systems. For the design of a GSHP system, it is necessary to accurately predict the heat extraction and injection rates of the heat exchanger. Many models that combine ground heat conduction and heat exchangers have been proposed to predict heat extraction\\/injection rates

  6. Brayton heat exchanger unit development program (alternate design)

    NASA Technical Reports Server (NTRS)

    Duncan, J. D.; Gibson, J. C.; Graves, R. F.; Morse, C. J.; Richard, C. E.

    1973-01-01

    A Brayton Heat Exchanger Unit Alternate Design (BHXU-Alternate) consisting of a recuperator, a heat sink heat exchanger, and a gas ducting system, was designed and fabricated. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. Emphasis was on double containment against external leakage and leakage of the organic coolant into the gas stream. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement, including the close-coupled integration of the BHXU-Alternate with the Brayton Rotating Unit (BRU).

  7. Heat-exchange formula for thermometers, which takes into account heat removal and radiation

    Microsoft Academic Search

    N. A. Yaryshev

    1965-01-01

    Special articles and the instructions for measuring temperature examine systematic errors produced in thermOmeters by variations with time of ambient temperature, heat removal along the measuring device, and radiant heat exchange with surrounding bodies. The effect of each of the above factors, even under conditions when the thermoelement is replaced by its simple model, is carried out separately [1-3, 6,

  8. Second-law performance of heat exchangers for waste heat recovery

    Microsoft Academic Search

    J.-Y. San

    2010-01-01

    Exergy change rate in an ideal gas flow or an incompressible flow can be divided into a thermal exergy change rate and a mechanical exergy loss rate. The mechanical exergy loss rates in the two flows were generalized using a pressure-drop factor. For heat exchangers using in waste heat recovery, the consumed mechanical exergy is usually more valuable than the

  9. Computer simulation of borehole ground heat exchangers for geothermal heat pump systems

    Microsoft Academic Search

    C. K. Lee; H. N. Lam

    2008-01-01

    Computer simulation of borehole ground heat exchangers used in geothermal heat pump systems was conducted using three-dimensional implicit finite difference method with rectangular coordinate system. Each borehole was approximated by a square column circumscribed by the borehole radius. Borehole loading profile calculated numerically based on the prescribed borehole temperature profile under quasi-steady state conditions was used to determine the ground

  10. Heat transfer and flow studies of the liquid droplet heat exchanger

    Microsoft Academic Search

    A. P. Bruckner; A. Shariatmadar

    1987-01-01

    This paper describes a lightweight, highly effective liquid droplet heat exchanger (LDHX) concept for thermal management in space. Heat is transferred by direct contact between fine droplets (100 to 300 micron diameter) of a low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the microgravity environment is accomplished by configuring the

  11. A development of a portable air conditioning-heat pump unit using helical coil heat exchanger

    Microsoft Academic Search

    T. Wessapan; T. Borirak; S. Teeksap; N. Somsuk

    2010-01-01

    In the present energy crisis situation, maximization utilization of energy use is vital matter, especially an air conditioning unit which is one of the largest energy use in the home. The objectives of this paper are to: i) design and development of a portable air conditioning:-heat pump unit using helical coil heat exchanger, ii) improve the cooling performance of a

  12. Experimental validation of a ground heat exchanger model in a hybrid ground source heat pump

    Microsoft Academic Search

    Amanda Pertzborn; Scott Hackel; Greg Nellis; Sanford Klein

    2011-01-01

    This article provides an overview of short time-scale validation of the duct storage model (Hellström 1989) for the simulation of ground source heat pump performance using experimental data acquired from two operational systems. The error in the temperature change across the ground heat exchanger in the first system was within measurement error, but it was larger than the measurement error

  13. Development of spiral heat source model for novel pile ground heat exchangers

    Microsoft Academic Search

    Yi Man; Hongxing Yang; Nairen Diao; Ping Cui; Lin Lu; Zhaohong Fang

    2011-01-01

    The extensive application of ground coupled heat pump system (GCHP) is restricted by the installation cost of conventional borehole ground heat exchangers (GHE), which is not only expensive but also requires additional ground area. The idea of combining the GHE with building foundation piles, i.e., the “energy pile,” has arisen in recent years. The novel pile GHEs consisting of vertical

  14. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Mathur, A. K.

    1980-01-01

    Five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants were discussed. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion phase change materials (PCMs) in the temperature range of 250 to 350 C. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. The most attractive major components in the temperature range of 250 to 350 C appeared to be NaNO3, NaNO2, and NaOH. Sketches of the two active heat exchange concepts selected for test are given.

  15. A survey of generalized heat transfer correlations for selected compact heat exchangers

    SciTech Connect

    Carranza, R.G. [Carranza (Richard G.), Lisle, IL (United States)

    1999-11-01

    The following discussion is a survey of generalized heat transfer correlations in the open literature for five selected compact heat exchangers: bare pipe, helically finned pipe, plate finned pipe, spined pipe, and plate heat exchangers. The basis on which the correlations are chosen for presentation is as follows: (1) The correlation must have good accuracy; (2) The correlation must be the latest development; (3) The correlation must possess notable ingenuity; (4) The correlation must be compared to the work of independent investigators; (5) The correlation must be developed from work using good scientific style; and (6) The correlation must be highly regarded by experts in the field of compact heat exchangers. These are the criteria used in choosing a correlation for the survey. Though not all of the correlations meet all of the items in the criteria, the correlation that best satisfies all the criteria is the one chosen. This paper is a continuation of an earlier work done by Carranza (1994). Carranza presents a survey of correlations for pressure drop with respect to the above mentioned five heat exchangers. In Carranza`s paper, Figure 1 and Equations 1, 2, 3, and 6 cover important concepts and definitions concerning the design of compact heat exchangers--items such as maximum velocity, minimum cross-sectional area, transverse pipe spacing, e{sub max}, V{sub 1}, etc. The reader is referred to the work of Carranza (1994) for more details regarding these fundamental quantities.

  16. A Local Heat Flux Measurement Technique for Inclined Heat Exchanger Tubes

    Microsoft Academic Search

    T. Wu; K. Vierow

    2006-01-01

    This article presents the design, fabrication, and calibration of thermocouple pairs for local heat flux measurement. The intended application of the thermocouple pairs is on the tubes of phase-change heat exchangers experiencing heat fluxes on the order of 10 W\\/m. Particular advantages of this technique are that it is accurate even for thin-wall tubes, there are no restrictions on the

  17. Heat transfer between liquid3He and sintered metal heat exchangers

    Microsoft Academic Search

    A. R. Rutherford; J. P. Harrison; M. J. Stott

    1984-01-01

    A new model to explain the unexpectedly large heat transfer between liquid3He and sintered metal heat exchangers is described and evaluated. The heat transfer results from a direct coupling of3He quasiparticles in the pores to vibrational modes of the sintered metal powder. It is proposed that for a range of temperatures below 20 mK the dominant vibrational modes of the

  18. High-heat-flux testing of helium-cooled heat exchangers for fusion applications

    Microsoft Academic Search

    D. L. Youchison; M. G. Izenson; C. B. Baxi; J. H. Rosenfeld

    1996-01-01

    High-heat-flux experiments on three types of helium-cooled divertor mock-ups were performed on the 30-kW electron beam test system and its associated helium flow loop at Sandia National Laboratories. A dispersion-strengthened copper alloy (DSCu) was used in the manufacture of all the mock-ups. The first heat exchanger provides for enhanced heat transfer at relatively low flow rates and much reduced pumping

  19. Primary loop heat exchanger for HTGR plant residual heat removal and auxiliary cooling system

    Microsoft Academic Search

    E. J. Hurn; D. P. Carosella

    1981-01-01

    For several years design studies have been under way in the US on high-temperature process heat and steam applications utilizing a high-temperature gas-cooled reactor (HTGR) plant. Plant designs have incorporated safety-class core auxiliary cooling systems (CACSs). Each CACS primary loop includes an auxiliary helium circulator, a shutoff valve, and a water-cooled core auxiliary heat exchanger (CAHE), which transfers heat from

  20. Heat transfer between liquid 3 He and sintered metal heat exchangers

    Microsoft Academic Search

    A. R. Rutherford; J. P. Harrison; M. J. Stott

    1984-01-01

    A new model to explain the unexpectedly large heat transfer between liquid3He and sintered metal heat exchangers is described and evaluated. The heat transfer results from a direct coupling of3He quasiparticles in the pores to vibrational modes of the sintered metal powder. It is proposed that for a range of temperatures below 20 mK the dominant vibrational modes of the

  1. Performance evaluation of a generator-absorber heat-exchange heat pump

    Microsoft Academic Search

    Srinivas Garimella; Richard N. Christensen; Daryl Lacy

    1996-01-01

    A generator-absorber heat-exchange (GAX) heat pump was modeled in this study using OSU-ABSIM, a modular steady-state simulation program. While the thermodynamics of GAX cycles have been investigated in the past, a comprehensive implementation-related performance evaluation of this cycle is not available. Therefore, in the present study, the complete absorption system was analyzed for the heating and cooling modes, including air-to-hydronic

  2. A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

    PubMed

    de Jong, J A; Wijnant, Y H; de Boer, A

    2014-03-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer. PMID:24606258

  3. The Cost of Heat Exchanger Fouling in the U. S. Industries 

    E-print Network

    Rebello, W. J.; Richlen, S. L.; Childs, F.

    1988-01-01

    Fouling of heat exchangers costs the U.S. industries hundreds of millions of dollars every year in increased equipment costs, maintenance costs, energy losses and losses in production. The designer of heat exchangers usually allows for fouling...

  4. Gas turbine power plant having a heat exchanger

    SciTech Connect

    Huller, J.; Krockow, W.

    1981-12-29

    A gas turbine power plant, such as a gas turbine engine for a motor vehicle, having a gas turbine, a combustor for producing hot gas to drive the turbine, and an air compressor for furnishing compressed air to the combustor are described. A heat exchanger, such as a rotary regenerator or a cross-flow recuperator, is located between the air compressor and the combustor for heating air by exhaust gas from the turbine before the air enters the combustor. The air leaving the exit of the heat exchanger decreases in temperature in a direction from one end of the exit to the other. A plurality of separate ducts conduct air from successive areas along the length of the heat exchanger exit to corresponding successive regions along the length of the combustor, the air temperature being lower in each succeeding duct. The lowest temperature air is conducted to the region containing a forward portion, e.g., the head, of the combustor, and air of progressively higher temperature being ducted to successive regions closer to the exhaust end of the combustor.

  5. Fabrication of Wire Mesh Heat Exchangers for Waste Heat Recovery Using Wire-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Rezaey, R.; Salavati, S.; Pershin, L.; Coyle, T.; Chandra, S.; Mostaghimi, J.

    2014-04-01

    Waste heat can be recovered from hot combustion gases using water-cooled heat exchangers. Adding fins to the external surfaces of the water pipes inserted into the hot gases increases their surface area and enhances heat transfer, increasing the efficiency of heat recovery. A method of increasing the heat transfer surface area has been developed using a twin wire-arc thermal spray system to generate a dense, high-strength coating that bonds wire mesh to the outside surfaces of stainless steel pipes through which water passes. At the optimum spray distance of 150 mm, the oxide content, coating porosity, and the adhesion strength of the coating were measured to be 7%, 2%, and 24 MPa, respectively. Experiments were done in which heat exchangers were placed inside a high-temperature oven with temperature varying from 300 to 900 °C. Several different heat exchanger designs were tested to estimate the total heat transfer in each case. The efficiency of heat transfer was found to depend strongly on the quality of the bond between the wire meshes and pipes and the size of openings in the wire mesh.

  6. Heat exchanger sizing for vertical closed-loop ground-source heat pumps

    SciTech Connect

    Cane, R.L.D.; Clemes, S.B.; Morrison, A. [Caneta Research, Inc., Mississauga, Ontario (Canada); Hughes, P.J. [Oak Ridge National Lab., TN (United States)

    1995-11-01

    A building energy simulation program has been used in conjunction with a ground heat exchanger sizing algorithm to develop general guidelines on how to size vertical ground heat exchangers for closed-loop ground-source heat pump systems in large buildings. The analysis considered three commercial building types of varying size with different internal loads and heat pump efficiencies. Each building variation was simulated in seven cities, three in the United States and four in Canada. The ground heat exchanger sizing algorithm has been previously validated against actual system data. The analysis results showed a strong correlation between heat exchanger length required and annual energy rejected to the ground, if the building was cooling-dominated, or annual energy extracted from the ground, if the building was heating-dominated. The resulting sizing guidelines recommend hour-by-hour energy analysis to determine the energy extracted from and rejected to the building water loop. Using this information the designer will have available easy-to-use, accurate sizing guidelines that should result in more economical installations than those based on previous ``rule of thumb`` guidelines.

  7. Heat exchanger sizing for vertical closed-loop ground-source heat pumps

    SciTech Connect

    Cane, R.L.D.; Clemes, S.B.; Morrison, A. [Caneta Research, Inc., Mississauga, Ontario (Canada); Hughes, P.J. [Oak Ridge National Lab., TN (United States)

    1995-12-31

    A building energy simulation program has been used in conjunction with a ground heat exchanger sizing algorithm to develop general guidelines on how to size vertical ground heat exchangers for closed-loop ground-source heat pump systems in large buildings. The analysis considered three commercial building types of varying size with different internal loads and heat pump efficiencies. Each building variation was simulated in seven cities, three in the US and four in Canada. The ground heat exchanger sizing algorithm has been previously validated against actual system data. The analysis results showed a strong correlation between heat exchanger length required and annual energy rejected to the ground, if the building was cooling-dominated, or annual energy extracted from the ground, if the building was heating-dominated. The resulting sizing guidelines recommend hour-by-hour energy analysis to determine the energy extracted from and rejected to the building water loop. Using this information the designer will have available easy-to-use, accurate sizing guidelines that should result in more economical installations than those based on previous ``rule of thumb`` guidelines.

  8. Heat transfer and pressure drop characteristics of nanofluids in a plate heat exchanger.

    PubMed

    Kwon, Y H; Kim, D; Li, C G; Lee, J K; Hong, D S; Lee, J G; Lee, S H; Cho, Y H; Kim, S H

    2011-07-01

    In this paper, the heat transfer characteristics and pressure drop of the ZnO and Al2O3 nanofluids in a plate heat exchanger were studied. The experimental conditions were 100-500 Reynolds number and the respective volumetric flow rates. The working temperature of the heat exchanger was within 20-40 degrees C. The measured thermophysical properties, such as thermal conductivity and kinematic viscosity, were applied to the calculation of the convective heat transfer coefficient of the plate heat exchanger employing the ZnO and Al2O3 nanofluids made through a two-step method. According to the Reynolds number, the overall heat transfer coefficient for 6 vol% Al2O3 increased to 30% because at the given viscosity and density of the nanofluids, they did not have the same flow rates. At a given volumetric flow rate, however, the performance did not improve. After the nanofluids were placed in the plate heat exchanger, the experimental results pertaining to nanofluid efficiency seemed inauspicious. PMID:22121605

  9. New designs of heat exchangers for natural gas liquefying and separating plants

    Microsoft Academic Search

    O. K. Krasnikova; O. M. Popov; V. N. Udut

    2006-01-01

    The special operational features of heat exchangers of natural gas liquefying and separating plants are shown. A new design\\u000a of coil heat exchanger having tubes finned with round wire with a statically uniform structure is described. The technical\\u000a specifications of heat exchangers finned with wire having annular intensifiers and of conventional coil flat-tube heat exchanger\\u000a are compared.

  10. Development of a compact laminar flow heat exchanger with stainless steel micro-tubes

    Microsoft Academic Search

    N. Saji; S. Nagai; K. Tsuchiya; H. Asakura; M. Obata

    2001-01-01

    The present paper describes the design concept and manufacturing of a new compact laminar flow heat exchanger with stainless-steel micro-tubes for helium refrigerators. In the temperature range of less than 20 K, aluminum plate fin type heat exchangers exhibit a remarkable fall of performance characteristics as a compact heat exchanger.We presented in a previous paper that some compact heat exchangers

  11. Innovative, counterflow gas/fine solids, direct contact heat exchanger: Final report

    SciTech Connect

    Mah, C.S.

    1987-10-01

    The Aerojet Energy Conversion Company has completed the first phase of study for development of a heat exchanger. The heat exchanger, a highly efficient, low cost concept, is a candidate for application in process manufacturing industries such as cement, lime, or glass. The analytical effort was to establish the heat exchanger performance via computer modeling and analysis; the experimental effort was to demonstrate the heat exchanger performance.

  12. Fluidized bed heat exchanger with water cooled air distributor and dust hopper

    DOEpatents

    Jukkola, Walfred W. (Westport, CT); Leon, Albert M. (Mamaroneck, NY); Van Dyk, Jr., Garritt C. (Bethel, CT); McCoy, Daniel E. (Williamsport, PA); Fisher, Barry L. (Montgomery, PA); Saiers, Timothy L. (Williamsport, PA); Karstetter, Marlin E. (Loganton, PA)

    1981-11-24

    A fluidized bed heat exchanger is provided in which air is passed through a bed of particulate material containing fuel. A steam-water natural circulation system is provided for heat exchange and the housing of the heat exchanger has a water-wall type construction. Vertical in-bed heat exchange tubes are provided and the air distributor is water-cooled. A water-cooled dust hopper is provided in the housing to collect particulates from the combustion gases and separate the combustion zone from a volume within said housing in which convection heat exchange tubes are provided to extract heat from the exiting combustion gases.

  13. 46 CFR 54.15-15 - Relief devices for unfired steam boilers, evaporators, and heat exchangers (modifies UG-126).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...unfired steam boilers, evaporators, and heat exchangers (modifies UG-126). 54...unfired steam boilers, evaporators, and heat exchangers (modifies UG-126...above the safety valve setting. (f) A heat exchanger with liquid in the shell...

  14. 46 CFR 54.15-15 - Relief devices for unfired steam boilers, evaporators, and heat exchangers (modifies UG-126).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...unfired steam boilers, evaporators, and heat exchangers (modifies UG-126). 54...unfired steam boilers, evaporators, and heat exchangers (modifies UG-126...above the safety valve setting. (f) A heat exchanger with liquid in the shell...

  15. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false What heat exchange systems are exempt from the requirements...for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What...

  16. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false What heat exchange systems are exempt from the requirements...for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What...

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

    SciTech Connect

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

    1985-01-01

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

  18. Design and optimization of coil finned-tube heat exchangers for cryogenic applications

    Microsoft Academic Search

    Prabhat Kumar Gupta; P. K. Kush; Ashesh Tiwari

    2007-01-01

    Coiled finned-tube heat exchangers have been used in small and medium helium refrigerators\\/liquefiers, miniature J T refrigeration systems for many years. The efficiency of these cryogenic systems strongly depends on the thermal and pressure drop performance of these heat exchangers. A considerable improvement in the performance of heat exchanger is possible by choosing an appropriate geometrical configuration for a given

  19. Thermal hydrodynamic characteristics of coil heat exchangers of the throttle stage of cryogenic helium plants

    Microsoft Academic Search

    V. A. Martynov; O. K. Krasnikova

    1987-01-01

    The authors examine a coil heat exchanger of the throttle stage of cryogenic helium plants made of tubes with wire fins. The coil heat exchanger represents a bundle of tubes with wire fins encased in a shell and is shown. This heat exchanger design offers a pure countercurrent flow to achieve small temperature differences. The coefficient of hydraulic resistance was

  20. Low temperature thermal resistance for a new design of silver sinter heat exchanger

    Microsoft Academic Search

    J. Pollanen; H. Choi; J. P. Davis; B. T. Rolfs; W. P. Halperin

    2009-01-01

    We have developed a novel procedure for constructing high surface area silver sinter heat exchangers. Our recipe incorporates nylon fibers having a diameter of ~50 mum and thin wires of bulk silver in the heat exchanger. In order to increase the thermal conductance of liquid helium within the heat exchanger, prior to sintering, the nylon fibers are dissolved with an

  1. Low temperature thermal resistance for a new design of silver sinter heat exchanger

    Microsoft Academic Search

    J. Pollanen; H. Choi; J. P. Davis; B. T. Rolfs; W. P. Halperin

    2009-01-01

    We have developed a novel procedure for constructing high surface area silver sinter heat exchangers. Our recipe incorporates nylon fibers having a diameter of ?50 ?m and thin wires of bulk silver in the heat exchanger. In order to increase the thermal conductance of liquid helium within the heat exchanger, prior to sintering, the nylon fibers are dissolved with an

  2. A small and light weight heat exchanger for on-board helium refrigerator

    Microsoft Academic Search

    T. Koizumi; M. Takahashi; T. Uchida; Y. Kanazawa; M. Suzuki

    1983-01-01

    A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight

  3. Construction and preliminary testing of perforated-plate heat exchangers for use in helium IIrefrigerators

    Microsoft Academic Search

    François Viargues; Gerard Claudet; Peter Seyfert

    1994-01-01

    Heat exchangers in cryogenic refrigerators must meet conflicting requirements for high thermal efficiency and low frictional pressure drops. This is particularly true in helium II refrigerators where the gas stream leaves the cold source at 15 mbar. Perforated-plate heat exchangers are likely to offer better overall performances for that application than the widely used plate-fin heat exchangers. Through their design

  4. 40 CFR Table 10 to Subpart Ffff of... - Work Practice Standards for Heat Exchange Systems

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2009-07-01 true Work Practice Standards for Heat Exchange Systems 10 Table 10 to Subpart...Part 63—Work Practice Standards for Heat Exchange Systems As required in § 63...the following table that applies to your heat exchange systems: For each . . ....

  5. 40 CFR 63.2490 - What requirements must I meet for heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...true What requirements must I meet for heat exchange systems? 63.2490 Section...2490 What requirements must I meet for heat exchange systems? (a) You must comply...10 to this subpart that applies to your heat exchange systems, except as...

  6. 40 CFR 63.8030 - What requirements apply to my heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false What requirements apply to my heat exchange systems? 63.8030 Section...8030 What requirements apply to my heat exchange systems? (a) You must comply...Table 6 to this subpart that apply to your heat exchange systems, except as...

  7. 40 CFR 63.8030 - What requirements apply to my heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false What requirements apply to my heat exchange systems? 63.8030 Section...8030 What requirements apply to my heat exchange systems? (a) You must comply...Table 6 to this subpart that apply to your heat exchange systems, except as...

  8. 40 CFR Table 6 to Subpart Hhhhh of... - Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Requirements for Heat Exchange Systems 6 Table 6 to Subpart...Subpart HHHHH of Part 63—Requirements for Heat Exchange Systems As required in § 63...the following table that applies to your heat exchange systems. For each . . ....

  9. 40 CFR Table 10 to Subpart Ffff of... - Work Practice Standards for Heat Exchange Systems

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 true Work Practice Standards for Heat Exchange Systems 10 Table 10 to Subpart...Part 63—Work Practice Standards for Heat Exchange Systems As required in § 63...the following table that applies to your heat exchange systems: For each . . ....

  10. 40 CFR Table 6 to Subpart Hhhhh of... - Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Requirements for Heat Exchange Systems 6 Table 6 to Subpart...Subpart HHHHH of Part 63—Requirements for Heat Exchange Systems As required in § 63...the following table that applies to your heat exchange systems. For each . . ....

  11. 40 CFR 63.2490 - What requirements must I meet for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...true What requirements must I meet for heat exchange systems? 63.2490 Section...2490 What requirements must I meet for heat exchange systems? (a) You must comply...10 to this subpart that applies to your heat exchange systems, except as...

  12. LOOP TESTING OF INCONEL, NICKEL, MONEL AND BIMETAL HEAT EXCHANGERS. ANPP CORROSION PROGRAM

    Microsoft Academic Search

    J. McGrew; E. Jules

    1961-01-01

    A description is given of corrosion tests performed on 12 test vessels. ; Two sets of model heat exchangers (a set consists of a steam generator and ; superheater) and eight miniature heat exchangers were tested dynamically in a ; pressurized water loop. One set of model heat exchangers had bimetal tubes ; (stainless steel in the primary, carbon steel

  13. Thermal hydraulic investigations of intermediate heat exchanger in a pool-type fast breeder reactor

    Microsoft Academic Search

    R. Gajapathy; K. Velusamy; P. Selvaraj; P. Chellapandi; S. C. Chetal; T. Sundararajan

    2008-01-01

    Intermediate heat exchanger (IHX) in a pool-type liquid metal cooled fast breeder reactor is an important heat exchanging component as it forms an intermediate boundary between the radioactive primary sodium in the pool and the non-radioactive secondary sodium in the steam generator (SG). The thermal loads during steady state and transient conditions impose thermal stresses on the heat exchanger tubes

  14. Solid-State Additive Manufacturing for Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Norfolk, Mark; Johnson, Hilary

    2015-03-01

    Energy densities in devices are increasing across many industries including power generation, high power electronics, manufacturing, and automotive. Increasingly, there is a need for very high efficiency thermal management devices that can pull heat out of a small area at higher and higher rates. Metal additive manufacturing (AM) technologies have the promise of creating parts with complex internal geometries required for integral thermal management. However, this goal has not been met due to constraints in fusion-based metal 3D printers. This work presents a new strategy for metal AM of heat exchangers using an ultrasonic sheet lamination approach.

  15. Heat exchanger tube fretting wear: review and application to design

    SciTech Connect

    Ko, P.L.

    1985-04-01

    Flow-induced vibration in steam generators and heat exchangers can cause dynamic interactions between tubes and tube supports resulting in fretting-wear. The effects on tube wear of various parameters, such as tube/support interactions, materials, and tube/support clearances have been studied. Techniques to predict the dynamic tube/support interaction and analyze the impact force at the support have been developed. The results of this work are reviewed and discussed in the context of how best they may be applied in the assessment of heat exchanger designs. A new design criterion based on support impact force is also discussed. Finally, a technique to predict long-term tube life is outlined. 15 references, 13 figures, 1 table.

  16. Tritium permeation losses in HYLIFE-II heat exchanger tubes

    SciTech Connect

    Longhurst, G.R.; Dolan, T.J.

    1990-01-01

    Tritium permeation through the intermediate heat exchanger of the HYLIFE-II inertial fusion design concept is evaluated for routine operating conditions. The permeation process is modelled using the Lewis analogy combined with surface recombination. It is demonstrated that at very low driving potentials, permeation becomes proportional to the first power of the driving potential. The model predicts that under anticipated conditions the primary cooling loop will pass about 6% of the tritium entering it to the intermediate coolant. Possible approached to reducing tritium permeation are explored. Permeation is limited by turbulent diffusion transport through the molten salt. Hence, surface barriers with impendance factors typical of present technology can do very little to reduce permeation. Low Flibe viscosity is desirable. An efficient tritium removal system operating on the Flibe before it gets to the intermediate heat exchanger is required. Needs for further research are highlighted. 9 refs., 2 figs., 1 tab.

  17. Optimization techniques for thermoelectric (Peltier) counter-flow heat exchangers

    Microsoft Academic Search

    L. E. Frank

    1983-01-01

    Thermoelectric counter-flow heat exchangers are used for cooling circulating fluids in many aerospace applications such as astro-inertial platforms and electro-optical systems. Their chief advantages are high reliability and compactness. The optimization of thermoelectric cooling systems can be quite complex because of the interaction of various thermal and electrical design factors. A computer program was written to simulate the performance of

  18. Dynamic simulation of Brazed Plate-Fin Heat Exchangers

    Microsoft Academic Search

    D. Averous; K. Hammadi; H. Pingaud; X. Joulia; P. Guittard

    1999-01-01

    In this paper a dynamic simulator of Brazed Plate-Fin Heat Exchangers (PFHEs) ProSec\\\\tm is presented. A rigorous model is used which allows one to represent the very broad range of configurations for this kind of equipment. A DAE solver (DISCo) is used with a sparse direct solver (MA38) to handle the large number of equations. Applications for control and design

  19. Performance of Plate Heat Exchangers for Evaporation of Ammonia

    Microsoft Academic Search

    Dirk Sterner; Bengt Sunden

    2006-01-01

    Measurements on a semi-welded plate heat exchanger (PHE) and on various versions of the nickel-brazed PHE were performed in a large experimental refrigeration rig. Experiments were carried out with the refrigerant ammonia, which was completely evaporated in vertical upward flow in PHEs connected in a U-type manner. A multiple linear regression analysis produced three Nusselt number correlations for the different

  20. Air-to-air heat exchangers and the indoor environment

    Microsoft Academic Search

    E Vine

    1987-01-01

    Air-to-air heat exchangers were installed in 366 energy-efficient homes as part of a demonstration program in the United States. The median incremental cost of AAHX was $1268 ($7.42\\/mS), and it was less expensive (per square meter) to install this equipment in larger houses than in smaller houses. While most occupants did not notice problems with their AAHX, some households did

  1. High pressure ratio cryocooler with integral expander and heat exchanger

    Microsoft Academic Search

    J. A. Crunkleton; J. L. Smith Jr.; Y. Iwasa

    1988-01-01

    A new 1 W, 4.2 K cryocooler is under development that is intended to miniaturize helium temperature refrigeration systems using a high-pressure-ratio Collins-type cycle. The configuration resulted from optimization studies of a saturated vapor compression (SCV) cycle that employs miniature parallel-plate heat exchangers. The basic configuration is a long displacer in a close-fitting, thin-walled cylinder. The displacer-to-cylinder gap is the

  2. Geothermal direct-contact heat exchange. Final report

    Microsoft Academic Search

    Sims

    1976-01-01

    A glass direct contact heat exchange column was operated in the laboratory at atmospheric pressure using hot water and normal hexane. Column internals tested included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1°C for packing to 13°C for the

  3. TEXTURES OF ALUMINUM ALLOY THIN SHEETS FOR HEAT EXCHANGER FINS

    Microsoft Academic Search

    J. Marek; M. Karlík; P. Sláma

    2001-01-01

    Texture analysis of different sheets from Al1.5FeMnSi (AA 8006) and AlFeSi (AA 8011) alloys was carried out in order to compare textures of materials for heat exchangers fabricated by several producers and by different technolo- gies. The textures were determined by X-ray back reflec- tion goniometric method using SIEMENS diffractometer. A majority of samples exhibit recrystallization R-texture, remaining sheets have

  4. Method for manufacturing a disassemblable core heat exchanger

    SciTech Connect

    Sleep, R.E. Jr.

    1986-08-26

    A method is described of manufacturing a dissassemblable core heat exchanger which is interposed between a first and second fluid coupling and of the type including an elongated housing having a first and second flow port and having core tubes positioned within a bore of the housing and a first and second tube retaining plate sealed at opposite ends of the core tubes to enable a first fluid path and a second fluid path within the housing.

  5. Ceramic heat exchangers. (Latest citations from the Patent Bibliographic Database with exemplary claims). Published Search

    SciTech Connect

    Not Available

    1993-09-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains a minimum of 95 citations and includes a subject term index and title list.)

  6. Ceramic heat exchangers. (Latest citations from the Patent Bibliographic database). Published Search

    SciTech Connect

    Not Available

    1993-11-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains a minimum of 96 citations and includes a subject term index and title list.)

  7. Ceramic heat exchangers. (Latest citations from the US Patent Bibliographic file with exemplary claims). Published Search

    SciTech Connect

    Not Available

    1994-11-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains a minimum of 99 citations and includes a subject term index and title list.)

  8. Ceramic heat exchangers. (Latest citations from the U. S. Patent data base). Published Search

    SciTech Connect

    Not Available

    1992-08-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains a minimum of 79 citations and includes a subject term index and title list.)

  9. All-metal, compact heat exchanger for space cryocoolers

    NASA Technical Reports Server (NTRS)

    Swift, Walter L.; Valenzuela, Javier; Sixsmith, Herbert

    1990-01-01

    This report describes the development of a high performance, all metal compact heat exchanger. The device is designed for use in a reverse Brayton cryogenic cooler which provides five watts of refrigeration at 70 K. The heat exchanger consists of a stainless steel tube concentrically assembled within a second stainless steel tube. Approximately 300 pairs of slotted copper disks and matching annular slotted copper plates are positioned along the centerline axis of the concentric tubes. Each of the disks and plates has approximately 1200 precise slots machined by means of a special electric discharge process. Positioning of the disk and plate pairs is accomplished by means of dimples in the surface of the tubes. Mechanical and thermal connections between the tubes and plate/disk pairs are made by solder joints. The heat exchanger assembly is 9 cm in diameter by 50 cm in length and has a mass of 10 kg. The predicted thermal effectiveness is greater than 0.985 at design conditions. Pressure loss at design conditions is less than 5 kPa in both fluid passages. Tests were performed on a subassembly of plates integrally soldered to two end headers. The measured thermal effectiveness of the test article exceeded predicted levels. Pressure losses were negligibly higher than predictions.

  10. Utilization of Porous Media for Condensing Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Tuan, George C.

    2006-01-01

    The use of porous media as a mean of separating liquid condensate from the air stream in condensing heat exchangers has been explored in the past inside small plant growth chambers and in the Apollo Command Module. Both applications used a cooled porous media made of sintered stainless steel to cool and separate condensation from the air stream. However, the main issues with the utilization of porous media in the past have been the deterioration of the porous media over long duration, such as clogging and changes in surface wetting characteristics. In addition, for long duration usage, biofilm growth from microorganisms on the porous medial would also be an issue. In developing Porous Media Condensing Heat Exchangers (PMCHX) for future space applications, different porous materials and microbial growth control methods will need to be explored. This paper explores the work performed at JSC and GRC to evaluate different porous materials and microbial control methods to support the development of a Porous Media Condensing Heat Exchanger. It outlines the basic principles for designing a PMCHX and issues that were encountered and ways to resolve those issues. The PMCHX has potential of mass, volume, and power savings over current CHX and water separator technology and would be beneficial for long duration space missions.

  11. Geometric characteristics of lamellar ribbed heat exchangers with channels of variable section

    Microsoft Academic Search

    A. D. Suslov; N. P. Linevich-Yavorskaya; Yu. D. Frolov

    1991-01-01

    The thermal calculation and design solutions of heat-exchange gear are closely bound up with the temperature conditions of the operation of these devices. In branches of engineering such as cryogenics, power generation, aviation, etc., heat exchangers operate under conditions of considerable change of temperature of the heat carriers. In accordance with the change of temperature of the heat carriers, their

  12. Numerical Study on Characteristics of a Pre-Cooling He II Heat Exchanger

    Microsoft Academic Search

    Y. Ueno; T. Okamura; A. Sato

    2004-01-01

    A numerical analysis has been performed in order to investigate the heat transfer and pressure drop characteristics of a pre-cooling He II heat exchanger. The heat conduction in the pre-cooled helium path in the flow direction was taken into account. Temperature distribution and pressure drop in the heat exchanger have been calculated for various conditions. It was found that a

  13. HEAT EXCHANGE IN RELATION TO BLOOD FLOW BETWEEN THORAX AND ABDOMEN IN BUMBLEBEES

    Microsoft Academic Search

    BERND HEINRICH

    SUMMARY 1. The narrow passage within the petiole between thorax and abdomen is anatomically constructed so that counter-current exchange should retain heat in the thorax despite blood flow to and from the cool abdomen. 2. However, the counter-current heat exchanger can be physiologically circumvented. Exogenously heated bumblebees prevented overheating of the thorax by shunting heat into the abdomen. They also

  14. Measured performance of a solar-ground source heat pump system with vertical double spiral coil ground heat exchanger

    Microsoft Academic Search

    Yuehong Bi; Linger Chen; Chih Wu

    2001-01-01

    The experimental study was performed for a solar-ground source heat pump (SGSHP) system with a vertical double spiral coil (VDSC) ground heat exchanger (GHX). The heating mode of the SGSHP system is alternated between a solar energy source heat pump (SSHP) and a ground source heat pump (GSHP) using a low grade energy utilisation system built by the authors. The

  15. Heat transfer analysis and experimental verification of casted heat exchanger in non-icing and icing conditions in winter

    Microsoft Academic Search

    Jie Yu; Huan Zhang; Shijun You

    Seawater-source heat pump systems (SWHP) are recognized to be outstanding heating, cooling and water heating systems. A large number of SWHP systems have been used in residential and commercial buildings in coastal areas due to the attractive advantages of high efficiency and environmental friendliness. In this paper, two mathematical models that described heat transfer process of casted heat exchanger (CHE)

  16. Water Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Hansen, Scott W.; Sheth, Ribik B.; Atwell, Matt; Cheek, Ann; Agarwal, Muskan; Hong, Steven; Patel, Aashini,; Nguyen, Lisa; Posada, Luciano

    2014-01-01

    In a cyclical heat load environment such as low Lunar orbit, a spacecraft’s radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a “topper” to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. Studies conducted in this paper investigate utilizing water’s high latent heat of formation as a PCM, as opposed to traditional waxes, and corresponding complications surrounding freezing water in an enclosed volume. Work highlighted in this study is primarily visual and includes understanding ice formation, freeze front propagation, and the solidification process of water/ice. Various test coupons were constructed of copper to emulate the interstitial pin configuration (to aid in conduction) of the proposed water PCM HX design. Construction of a prototypic HX was also completed in which a flexible bladder material and interstitial pin configurations were tested. Additionally, a microgravity flight was conducted where three copper test articles were frozen continuously during microgravity and 2-g periods and individual water droplets were frozen during microgravity.

  17. A continuous heat regenerative adsorption refrigerator using spiral plate heat exchanger as adsorbers: improvements

    SciTech Connect

    Wang, R.Z.; Wu, J.Y.; Xu, Y.X. [Shanghai Jiao Tong Univ. (China). Inst. of Refrigeration and Cryogenics

    1999-02-01

    Spiral plate heat exchangers as adsorbers have been proposed, and a prototype heat regenerative adsorption refrigerator using activated carbon-methanol pair has been developed and tested. Various improvements have been made, the authors get a specific cooling power for 2.6 kg-ice/day-kg adsorbent at the condition of generation temperature lower than 100 C. Discussions on the arrangements of thermal cycles and influences of design are shown.

  18. Chaotic advection induced heat transfer enhancement in a chevron-type plate heat exchanger

    NASA Astrophysics Data System (ADS)

    Tohidi, A.; Hosseinalipour, S. M.; Taheri, P.; Nouri, N. M.; Mujumdar, A. S.

    2013-11-01

    The present work examines the role of chaotic mixing as a means of heat transfer enhancement in plate heat exchangers. In order to demonstrate the chaotic behavior, sensitivity to initial conditions and horseshoe maps are visualized. The Nusselt number and the friction factor were computed in the range of reynolds number, 1 < Re < 10. The Nusselt number increases considerably in chaotic models whereas the friction factor increases only marginally.

  19. A Testing and HVAC Design Methodology for Air-to-Air Heat Pipe Heat Exchangers

    Microsoft Academic Search

    Pingbo Guo; Dustin L. Ciepliski; Robert W. Besant

    1998-01-01

    Air-to-air heat pipe heat exchangers were tested using ASHRAE Standard 84-1991 as a guide. Some changes are introduced for the test facility and methods of calculating effectiveness. ASME PTC 19.1-1985 is used as a guide for uncertainty analysis. Tests were done for a range of mass flux [1.574 to 2.912 kg\\/(m·s)], ratios of mass flow rates (0.6 to 1.85), supply

  20. Numerical analysis and experimental validation of heat transfer in ground heat exchangers in alternative operation modes

    Microsoft Academic Search

    P. Cui; H. Yang; Z. Fang

    2008-01-01

    A finite element numerical model has been developed for the simulation of the ground heat exchangers (GHEs) in alternative operation modes over a short time period for ground-coupled heat pump applications. Comparisons between the numerical and analytical results show that the finite line-source model is not capable of modeling the GHEs within a few hours because of the line-source assumption.

  1. High heat transfer oxidizer heat exchanger design and analysis. [RL10-2B engine

    NASA Technical Reports Server (NTRS)

    Kmiec, Thomas D.; Kanic, Paul G.; Peckham, Richard J.

    1987-01-01

    The RL10-2B engine, a derivative of the RL10, is capable of multimode thrust operation. This engine operates at two low thrust levels: tank head idle (THI), which is approximately 1 to 2% of full thrust, and pumped idle (PI), which is 10% of full thrust. Operation at THI provides vehicle propellant settling thrust and efficient engine thermal conditioning; PI operation provides vehicle tank pre-pressurization and maneuver thrust for low-g deployment. Stable combustion of the RL10-2B engine during the low thrust operating modes can be accomplished by using a heat exchanger to supply gaseous oxygen to the propellant injector. The oxidizer heat exchanger (OHE) vaporizes the liquid oxygen using hydrogen as the energy source. The design, concept verification testing and analysis for such a heat exchanger is discussed. The design presented uses a high efficiency compact core to vaporize the oxygen, and in the self-contained unit, attenuates any pressure and flow oscillations which result from unstable boiling in the core. This approach is referred to as the high heat transfer design. An alternative approach which prevents unstable boiling of the oxygen by limiting the heat transfer is referred to as the low heat transfer design and is reported in Pratt & Whitney report FR-19135-2.

  2. Development of an Accordion-type Offset-fin Heat Exchanger for Air-conditioners

    NASA Astrophysics Data System (ADS)

    Itoh, Masaaki; Kogure, Hiroshi; Miyagi, Masahiro; Mochizuki, Sadanari; Yagi, Yoshinao; Kunugi, Yoshifumi

    To reduce the depth of the indoor heat exchanger in room air-conditioners, we studied fin and tube heat exchangers, and found that we could make the heat transfer coefficient of fins 30% higher than of conventional fins by reducing louver width and fin pitch. We also improved water drainage on the surface of the fins by adopting accordion-type offset-fin heat exchangers. We found that the material cost of a heat exchanger was minimized when the heat exchanger had a tube 7 mm in diameter, and we could increase the heat transter coefficient of the refrigerant side by developing a new grooved tube 7 mm in diameter. We succeeded in making the heat exchanger 40% thinner than conventional types.

  3. Design with constructal theory: Steam generators, turbines and heat exchangers

    NASA Astrophysics Data System (ADS)

    Kim, Yong Sung

    This dissertation shows that the architecture of steam generators, steam turbines and heat exchangers for power plants can be predicted on the basis of the constructal law. According to constructal theory, the flow architecture emerges such that it provides progressively greater access to its currents. Each chapter shows how constructal theory guides the generation of designs in pursuit of higher performance. Chapter two shows the tube diameters, the number of riser tubes, the water circulation rate and the rate of steam production are determined by maximizing the heat transfer rate from hot gases to riser tubes and minimizing the global flow resistance under the fixed volume constraint. Chapter three shows how the optimal spacing between adjacent tubes, the number of tubes for the downcomer and the riser and the location of the flow reversal for the continuous steam generator are determined by the intersection of asymptotes method, and by minimizing the flow resistance under the fixed volume constraints. Chapter four shows that the mass inventory for steam turbines can be distributed between high pressure and low pressure turbines such that the global performance of the power plant is maximal under the total mass constraint. Chapter five presents the more general configuration of a two-stream heat exchanger with forced convection of the hot side and natural circulation on the cold side. Chapter six demonstrates that segmenting a tube with condensation on the outer surface leads to a smaller thermal resistance, and generates design criteria for the performance of multi-tube designs.

  4. Evaluation of heat exchange rate of GHE in geothermal heat pump systems

    Microsoft Academic Search

    Liu Jun; Zhang Xu; Gao Jun; Yang Jie

    2009-01-01

    Total thermal resistance of ground heat exchanger (GHE) is comprised of that of the soil and inside the borehole. The thermal resistance of soil can be calculated using the linear source theory and cylindrical source theory, while that inside the borehole is more complicated due to the integrated resistance of fluid convection, and the conduction through pipe and grout. Present

  5. Cleaning and Heat Transfer in Heat Exchanger with Circulating Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Kang, Ho Keun; Ahn, Soo Whan; Choi, Jong Woong; Lee, Byung Chang

    2010-06-01

    Fluidized bed type heat exchangers are known to increase the heat transfer and prevent the fouling. For proper design of circulating fluidized bed heat exchanger it is important to know the effect of design and operating parameters on the bed to the wall heat transfer coefficient. The present experimental and numerical study was conducted to investigate the effects of circulating solid particles on the characteristics of fluid flow, heat transfer and cleaning effect in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which a variety of solid particles such as glass (3 mmF), aluminum (2˜3 mmF), steel (2˜2.5 mmF), copper (2.5 mmF) and sand (2˜4 mmF) were used in the fluidized bed with a smooth tube. Seven different solid particles have the same volume, and the effects of various parameters such as water flow rates, particle diameter, materials and geometry were investigated. The present experimental and numerical results showed that the flow velocity range for collision of particles to the tube wall was higher with heavier density solid particles, and the increase in heat transfer was in the order of sand, copper, steel, aluminum, and glass. This behaviour might be attributed to the parameters such as surface roughness or particle heat capacity. Fouling examination using 25,500 ppm of ferric oxide (Fe2O3) revealed that the tube inside wall is cleaned by a mild and continuous scouring action of fluidized solid particles. The fluidized solid particles not only keep the surface clean, but they also break up the boundary layer improving the heat transfer coefficient even at low fluid velocities.

  6. Continued Water-Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Hansen, Scott; Poynot, Joe

    2014-01-01

    In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a "topper" to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development two full-scale, Orion sized water-based PCM HX's were constructed by Mezzo Technologies. These HX's were designed by applying prior research and experimentation to the full scale design. Design options considered included bladder restraint and clamping mechanisms, bladder manufacturing, tube patterns, fill/drain methods, manifold dimensions, weight optimization, and midplate designs. Design and construction of these HX's led to successful testing of both PCM HX's.

  7. Continued Water-Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Hansen, Scott W.; Sheth, Rubik B.; Poynot, Joe; Giglio, Tony; Ungar, Gene K.

    2015-01-01

    In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to meet the full heat rejection demands. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a "topper" to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HX's do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development two full-scale, Orion sized water-based PCM HX's were constructed by Mezzo Technologies. These HX's were designed by applying prior research on freeze front propagation to a full-scale design. Design options considered included bladder restraint and clamping mechanisms, bladder manufacturing, tube patterns, fill/drain methods, manifold dimensions, weight optimization, and midplate designs. Two units, Units A and B, were constructed and differed only in their midplate design. Both units failed multiple times during testing. This report highlights learning outcomes from these tests and are applied to a final sub-scale PCM HX which is slated to be tested on the ISS in early 2017.

  8. Development of Passive Fuel Cell Thermal Management Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Burke, Kenneth A.; Jakupca, Ian J.; Colozza, Anthony J.

    2010-01-01

    The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates that could conduct the heat, provide a sufficiently uniform temperature heat sink for each cell of the fuel cell stack, and be substantially lighter than the conventional thermal management approach. Tests were run with different materials to evaluate the design approach to a heat exchanger that could interface with the edges of the passive cooling plates. Measurements were made during fuel cell operation to determine the temperature of individual cooling plates and also to determine the temperature uniformity from one cooling plate to another.

  9. Flexible all-metal gaskets halt heat exchanger leakage

    SciTech Connect

    Gambrell, M.; Stadig, W.P.

    1985-11-01

    The Oyster Creek site of Texas Operations, Dow Chemical Company in Freeport, TX, was concerned about the potential fire hazard of hydrogen and hot hydrocarbon vapors leaking past the sealing gaskets of two process heat exchangers in the phenol acetone unit. Intermittent process upsets and periodic shutdown of operations for routine maintenance subjected the conventionally gasketed surfaces of the ANSI B16.5 raised face flanges to severe thermal cycling. To prevent leakage of flammable materials to the atmosphere, it was necessary to retighten the bolts on the heat exchanger heads. Eventually, the units had to be shut down two or three times a year to replace the gaskets. About two years ago, the conventional composite metal gaskets were replaced with flexible all-metal gaskets specially designed for lead-tight sealing under extreme operating conditions. The gasket's basic design is two metal linings formed around a helically wound spring to provide an elastic core. Each coil operates independently during radial compression to maintain pressure contact between the surfaces and to provide optimum spring-back in case of slight flange separation. The gasket linings, in a wide selection of ductile metals and alloys, will plastically deform and fill any faults or voids in the surface to be sealed. The flexible all-metal gaskets prevent leakage of the flammable gases and vapors from the heat exchangers during both normal and severe thermal cyclic conditions, and are now changed out only during annual shutdown for inspection and maintenance. The higher cost of the gaskets is partially offset by the lower frequency of changeout and labor cost, but the biggest payout is elimination of the potential fire hazard.

  10. The effects of outdoor heat exchanger hydrophobic treatment on the performance of an air source heat pump

    E-print Network

    Parker, Brandon DeWayne

    1995-01-01

    compared to tests that utilized coated aluminum outdoor heat exchangers. The overall performance of each test was analyzed. These tests were carried out for cooling and heating mode conditions. The adhesion strength of water droplets to a bare aluminum...

  11. An experimental study on heat transfer characteristics of heat pipe heat exchanger with latent heat storage. Part I: Charging only and discharging only modes

    Microsoft Academic Search

    Zhongliang Liu; Zengyi Wang; Chongfang Ma

    2006-01-01

    A new thermal storage system, a heat pipe heat exchanger with latent heat storage, is reported. The new system may operate in three basic different operation modes, the charging only, the discharging only and the simultaneous charging\\/discharging modes, which makes the system suitable for various time and\\/or weather dependent energy systems. In this part of the paper, the basic structure,

  12. 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.

  13. Permeation Barrier Coatings for the Helical Heat Exchanger

    SciTech Connect

    Korinko, P.S.

    1999-05-26

    A permeation barrier coating was specified for the Helical Heat Exchanger (HHE) to minimize contamination through emissions and/or permeation into the nitrogen system for ALARA reasons. Due to the geometry of the HHE, a special coating practice was needed since the conventional method of high temperature pack aluminization was intractable. A survey of many coating companies was undertaken; their coating capabilities and technologies were assessed and compared to WSRC needs. The processes and limitations to coating the HHE are described. Slurry coating appears to be the most technically sound approach for coating the HHE.

  14. Aging management guideline for commercial nuclear power plants - heat exchangers

    SciTech Connect

    Booker, S.; Lehnert, D.; Daavettila, N.; Palop, E.

    1994-06-01

    This Aging Management Guideline (AMG) describes recommended methods for effective detection and mitigation of age-related degradation mechanisms in commercial nuclear power plant heat exchangers important to license renewal. The intent of this AMG is to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR 54. This AMG is presented in a manner that allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein.

  15. Exchange fluctuation theorem for heat transport between multiterminal harmonic systems

    NASA Astrophysics Data System (ADS)

    Agarwalla, Bijay Kumar; Li, Huanan; Li, Baowen; Wang, Jian-Sheng

    2014-05-01

    We study full counting statistics for transferred heat and entropy production between multiterminal systems in absence of a finite junction. The systems are modeled as collections of coupled harmonic oscillators, which are kept at different equilibrium temperatures and are connected via arbitrary time-dependent couplings. Following consistent quantum framework and two-time measurement concept we obtain analytical expressions for the generalized cumulant generating function. We discuss transient and steady-state fluctuation theorems for the transferred quantities. We also address the effect of coupling strength on the exchange fluctuation theorem.

  16. Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties

    E-print Network

    Hansen, B J; Klebaner, A; 10.1063/1.4706971

    2012-01-01

    Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger ...

  17. The Heuristic Drift Model of the Scrape-Off Layer: Physics Issues and Implications

    NASA Astrophysics Data System (ADS)

    Goldston, Robert

    2013-10-01

    A heuristic drift-based (HD) model has recently been developed for the power scrape-off width in H-mode tokamaks, predicting a SOL width ~ 2(a/R) ?p , i. It agrees both in value and scalings with scrape-off width measurements on ASDEX-U, C-MOD, DIII-D, JET, MAST and NSTX. Even the projected aspect ratio scaling is consistent with the data. The implications for ITER and beyond are daunting, projecting SOLs in the range of 2mm, including additional broadening in the divertor region. As a result, the ITER divertor could operate in the sheath-limited regime at unacceptable power density and target temperature-but realistic upstream pressure-unless a very large fraction of the alpha power is dissipated by radiation and charge-exchange. Using the HD model for the SOL width, it is found that the SOL ballooning stability limit has value and scalings similar to the Greenwald limit. The predicted MHD ? is shown to rise with n/nGW, as observed experimentally. Interestingly, the narrow high-heat-flux regions observed in TEXTOR and JET limiter discharges are in the range of the HD projection, suggesting that the same mechanism could function in L-mode. A heuristic drift-based (HD) model has recently been developed for the power scrape-off width in H-mode tokamaks, predicting a SOL width ~ 2(a/R) ?p , i. It agrees both in value and scalings with scrape-off width measurements on ASDEX-U, C-MOD, DIII-D, JET, MAST and NSTX. Even the projected aspect ratio scaling is consistent with the data. The implications for ITER and beyond are daunting, projecting SOLs in the range of 2mm, including additional broadening in the divertor region. As a result, the ITER divertor could operate in the sheath-limited regime at unacceptable power density and target temperature-but realistic upstream pressure-unless a very large fraction of the alpha power is dissipated by radiation and charge-exchange. Using the HD model for the SOL width, it is found that the SOL ballooning stability limit has value and scalings similar to the Greenwald limit. The predicted MHD ? is shown to rise with n/nGW, as observed experimentally. Interestingly, the narrow high-heat-flux regions observed in TEXTOR and JET limiter discharges are in the range of the HD projection, suggesting that the same mechanism could function in L-mode. Supported by DOE Contract # DE-AC02-09CH11466.

  18. Advanced heat-pipe heat exchanger and microprocessor-based modulating burner controls development. Annual report, January 1985January 1986

    Microsoft Academic Search

    A. Lowenstein; B. Cohen; S. Feldman; M. Spatz; E. Smith

    1986-01-01

    The development of a novel condensing heat exchanger, a modulating gas burner, and a zone-controlled residential warm-air heating system is described. The condensing heat exchanger uses ten thermosyphons manifolded at both the condenser and evaporator ends to achieve a compact low-cost design. Initial tests have demonstrated a +92-% steady-state efficiency for a conventional clamshell furnace operating with the thermosyphon heat

  19. Effects of axial plate heat conduction on the thermal performance of a laminar counterflow flat plate heat exchanger 

    E-print Network

    Demko, Jonathan Alexander

    1980-01-01

    EFFECTS OF AXIAL PLATE HEAT CONDUCTION ON THE THERMAL PERFORMANCE QF A LAMINAR COUNTERFLON FLAT PLATE HEAT EXCHANGER A Thesis by JONATHAN ALZKVRER DEMKO Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE December 1980 Major Subject: Mechanical Engineering EFFECTS OF AXIAL PLATE HEAT CONDUCTION ON THE THERMAL PERFORMANCE OF A SHINAR COUNTERFLOW FLAT PLATE HEAT EXCHANGER A Thesis by JONATHAN ALEXANDER DEMKO...

  20. Two-phase/two-phase heat exchanger simulation analysis

    NASA Technical Reports Server (NTRS)

    Kim, Rhyn H.

    1992-01-01

    The capillary pumped loop (CPL) system is one of the most desirable devices to dissipate heat energy in the radiation environment of the Space Station providing a relatively easy control of the temperature. A condenser, a component of the CPL system, is linked with a buffer evaporator in the form of an annulus section of a double tube heat exchanger arrangement: the concentric core of the double tube is the condenser; the annulus section is used as a buffer between the conditioned space and the radiation surrounding but works as an evaporator. A CPL system with this type of condenser is modeled to simulate its function numerically. Preliminary results for temperature variations of the system are shown and more investigations are suggested for further improvement.

  1. Unglazed selective absorber solar air collector: Heat exchange analysis

    NASA Astrophysics Data System (ADS)

    Njomo, D.

    Unglazed solar air collectors show promise for applications such as ventilation air heating or crop drying. In this paper a mathematical model is developed to analyze the heat exchanges in an unglazed non-porous selective absorber air heater. It is shown that at quasi-steady state the energy balance equations of the components of the collector cascade into a single first order differential equation. The solution of this differential equation is written down as an explicit expression of the local temperature of the fluid flowing in the collector in terms of the time dependent solar intensity. The effect of various parameters such as the inlet fluid temperature, the mass flow rate, and the depth of the air channel on the thermal performances of the unglazed selective absorber collector are also studied. These performances are comparable to those of a conventional two glass covers air collector for low wind speeds.

  2. Optimization of heat exchanger design in a thermoacoustic engine using a second law analysis

    SciTech Connect

    Ishikawa, H.; Hobson, P.A. [Univ. of Queensland, St. Lucia (Australia). Dept. of Mechanical Engineering] [Univ. of Queensland, St. Lucia (Australia). Dept. of Mechanical Engineering

    1996-05-01

    An analysis for the time averaged entropy generation due to both flow and heat transfer losses in the heat exchangers of a thermoacoustic engine has been developed. An expression for the optimum dimensionless heat exchanger area corresponding to minimum entropy generation has been determined in terms of three other dimensionless parameters. Optimum heat exchanger areas were calculated for three thermoacoustic devices. For the prime mover components of the thermoacoustic devices investigated where the temperature differences across the regenerator stacks were high, the analysis developed indicated that the heat exchanger at the hot end of the regenerator stack should be smaller than that at the cold end.

  3. Development of a contact heat exchanger for a constructable radiator system

    NASA Technical Reports Server (NTRS)

    Howell, H. R.

    1983-01-01

    A development program for a contact heat exchanger to be used to transfer heat from a spacecraft coolant loop to a heat pipe radiator is described. The contact heat exchanger provides for a connectable/disconnectable joint which allows for on-orbit assembly of the radiator system and replacement or exchange of radiator panels for repair and maintenance. The contact heat exchanger does not require the transfer of fluid across the joint; the spacecraft coolant loop remains contained in an all welded system with no static or dynamic fluid seals. The contact interface is also "dry' with no conductive grease or interstitial material required.

  4. Interpretive 2-D treatment of scrape-off-layer plasmas

    SciTech Connect

    Umansky, M.; Allen, A.; Daughton, W. [MIT Plasma Fusion Center, Cambridge, MA (United States)] [and others

    1996-12-31

    The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.

  5. Analysis of induced temperature anomalies along borehole heat exchangers

    NASA Astrophysics Data System (ADS)

    Lindner, Michael; Schelenz, Sophie; Stollberg, Reiner; Gossel, Wolfgang; Dietrich, Peter; Vienken, Thomas

    2015-04-01

    Over the last years, the thermal use of the shallow subsurface for heat generation, cooling, and thermal energy storage has increased. However, the injection or extraction of heat potentially drives changes in the subsurface temperature regime; especially in urban areas. The presented case study investigates the intensive use of borehole heat exchangers (BHE) and their potential thermal impacts on subsurface temperatures, as well as thermal interactions between individual BHE's for a residential neighborhood in Cologne, Germany. Based on on-site subsurface parameterization, a 3D subsurface model was designed, using the finite element software FEFLOW (DHI WASY). The model contains five BHE, extracting 8.2 kW, with a maximum BHE depth of 38 m, whereby the thickness of the unsaturated zone is 22 m. The simulated time span is 10 years. This study focusses on two questions: How will different BHE arrangements vary in terms of temperature plume formation and potential system interaction and what is the influence of seasonal subsurface heat storage on soil and ground water temperatures.

  6. Heat-exchanger concepts for neutral-beam calorimeters

    SciTech Connect

    Thompson, C.C.; Polk, D.H.; McFarlin, D.J.; Stone, R.

    1981-10-05

    Advanced cooling concepts that permit the design of water cooled heat exchangers for use as calorimeters and beam dumps for advanced neutral beam injection systems were evaluated. Water cooling techniques ranging from pool boiling to high pressure, high velocity swirl flow were considered. Preliminary performance tests were carried out with copper, inconel and molybdenum tubes ranging in size from 0.19 to 0.50 in. diameter. Coolant flow configurations included (1) smooth tube/straight flow, (2) smooth tube with swirl flow created by tangential injection of the coolant, and (3) axial flow in internally finned tubes. Additionally, the effect of tube L/D was evaluated. A CO/sub 2/ laser was employed to irradiate a sector of the tube exterior wall; the laser power was incrementally increased until burnout (as evidenced by a coolant leak) occurred. Absorbed heat fluxes were calculated by dividing the measured coolant heat load by the area of the burn spot on the tube surface. Two six element thermopiles were used to accurately determine the coolant temperature rise. A maximum burnout heat flux near 14 kW/cm/sup 2/ was obtained for the molybdenum tube swirl flow configuration.

  7. Design of Liquid Metal Phase Change Heat Exchanger for Next-Generation Nuclear Plant Process Heat Application

    Microsoft Academic Search

    Piyush SABHARWALL; Vivek UTGIKAR; Akira TOKUHIRO; Fred GUNNERSON

    2009-01-01

    The Next Generation Nuclear Plant will most likely produce electricity and its reactor heat will be further utilized for the production of hydrogen, oil recovery from tar sands and oil shales, and other process heat applications, that will further the nation's pursuit of energy independence. An intermediate heat exchanger is required to transfer heat from the Next-Generation Nuclear Plant to

  8. SIMULATION OF A DOMESTIC GROUND SOURCE HEAT PUMP SYSTEM USING A TRANSIENT NUMERICAL BOREHOLE HEAT EXCHANGER MODEL

    Microsoft Academic Search

    Miaomiao He; Simon Rees; Li Shao

    Common approaches to the simulation of Borehole Heat Exchangers (BHEs) assume heat transfer in circulating fluid and grout to be in a quasi-steady state and ignore fluctuations in fluid temperature due to transport of the fluid around the loop. However, in domestic ground source heat pump systems, the heat pump and circulating pumps switch on and off during a given

  9. Mathematical Model of the Optimum Heat Pipe Heat Exchanger for a Condenser of Vapor-Compression Refrigeration Cycle

    Microsoft Academic Search

    P. Yeunyongkul; P. Sakulchangsatjatai; P. Terdto

    2010-01-01

    Problem statement: This study theoretically investigated applying heat pipe as a heat exchanger in the condenser of vapor compression refrigeration system for sustainable well-being. Split- type air conditioner for residential propose was co nsidered. To reduce pressure drop and recover heat from the condensing process of the refrigeration cy cle, this investigation tried to use Closed Loop Oscillating Heat Pipe

  10. A self-circulating heat exchanger for use in stirling and thermoacoustic-stirling engines

    Microsoft Academic Search

    S. N. Backhaus; R. S. Reid

    2004-01-01

    A major technical hurdle to the implementation of large Stirling engines or thermoacoustic engines is the reliability, performance, and manufacturability of the hot heat exchanger that brings high-temperature heat into the engine. Unlike power conversion devices that utilize steady flow, the oscillatory nature of the flow in Stirling and thermoacoustic engines restricts the length of a traditional hot heat exchanger

  11. A Self-Circulating Heat Exchanger for Use in Stirling and Thermoacoustic-Stirling Engines

    Microsoft Academic Search

    Scott Backhaus; Robert S. Reid

    2005-01-01

    A major technical hurdle to the implementation of large Stirling engines or thermoacoustic engines is the reliability, performance, and manufacturability of the hot heat exchanger that brings high-temperature heat into the engine. Unlike power conversion devices that utilize steady flow, the oscillatory nature of the flow in Stirling and thermoacoustic engines restricts the length of a traditional hot heat exchanger

  12. Numerical Investigation of Ultra-Rich Combustion in Counter Flow Heat Exchangers

    Microsoft Academic Search

    Ingmar M. Schoegl; Janet L. Ellzey

    2010-01-01

    Recirculation of heat has been used for decades to react mixtures beyond the conventional flammability limits. One means of obtaining this recirculation is through counter-flow heat exchange. In contrast to filtration combustion in which a reaction front propagates through a packed bed, counter-flow heat exchange results in stationary reactions zones. The objective of this study is the numerical investigation of

  13. New design equations for liquid\\/solid fluidized bed heat exchangers

    Microsoft Academic Search

    M. Aghajani; H. Müller-Steinhagen; M. Jamialahmadi

    2005-01-01

    Liquid\\/solid fluidized bed heat exchangers have originally been developed for desalination plants. However, due to their substantial benefits with respect to significantly improved heat transfer and fouling reduction, successful applications also exist in areas such as petrochemical, minerals and food processing as well as in the paper and power industries. The excellent performance of fluidized bed heat exchangers is related

  14. TEMPERATURE CONTROLLABILITY IN CROSS-FLOW HEAT EXCHANGERS AND LONG DUCTS

    E-print Network

    Sen, Mihir

    TEMPERATURE CONTROLLABILITY IN CROSS-FLOW HEAT EXCHANGERS AND LONG DUCTS A Dissertation Submitted in Aerospace and Mechanical Engineering Notre Dame, Indiana June 2003 #12;TEMPERATURE CONTROLLABILITY IN CROSS-FLOW for which conductive- convective systems and cross-flow heat exchangers are examined in detail. In the heat

  15. Porous media heat exchangers for cooling of high-power optical components

    Microsoft Academic Search

    John H. Rosenfeld; Mark T. North

    1995-01-01

    Technologies based on porous media can be used in several classes of heat exchangers that can be used to meet the cooling needs of high heat load optical components as well as other high heat flux applications. These include mechanically pumped single-phase and two-phase porous media heat exchangers, as well as capillary pumped (heat pipe) two-phase designs. A brief overview

  16. Multi-Scale Stress Analysis for Compact Plate-Type Heat Exchangers

    Microsoft Academic Search

    Huang Wensheng; Zhao Haihua; Per F. Peterson

    2006-01-01

    This paper presents thermal mechanical analysis methods and results for compact offset-fin plate-type heat exchangers for high temperature heat transfer. For nuclear hydrogen applications an intermediate heat exchanger (IHX) is required to transfer heat from high temperature high-pressure primary helium to an intermediate heat transfer fluid. In the examples considered here, liquid salt is considered as the intermediate fluid. The

  17. Numerical analysis of heat exchange processes for the ground source heat pump system

    NASA Astrophysics Data System (ADS)

    Saito, H.; Muto, H.; Moritani, S.; Kohgo, Y.; Hamamoto, S.; Takemura, T.; Ohnishi, J.; Komatsu, T.

    2012-12-01

    Ground source heat pump systems (GSHP) use ground or groundwater as a heat source. They can achieve much higher coefficient of performance (COP) than conventional air source heat pump systems because the temperature of the ground is much more stable than that of the air. Heat energy in the ground is then viewed as one of the renewable energy sources. GSHP has been receiving great interests among countries in North America and Western Europe, as well as some developed countries in Asia because it can potentially reduce energy consumption and greenhouse gas emission. While GSHP can inject heat from the buildings to the ground for cooling during the summer, it can pump heat stored in the ground for heating during the winter. As some physical, chemical, and biological properties of the ground and groundwater are temperature dependent, running GSHP can eventually affect groundwater quality. The main objective of this project was to develop a model that allows predicting not only ground and groundwater temperatures but also changes in physical, chemical, and biological properties of ground and groundwater with GSHP under operations. This particular study aims at simulating heat exchange and transfer processes in the ground for a vertical-loop closed GSHP system. In the closed GSHP system, an anti-freezing solution is circulated inside the closed-loop tube, called U-tube, that is buried in the ground. Heat is then transferred to the anti-freezing solution in the U-tube by a heat exchanger. In this study we used HYDRUS to predict temperature of the anti-freezing solution, as well as that of the ground. HYDRUS allows one to simulate variably-saturated water flow and solute and heat transport in porous media numerically in two- and three-dimensional domains with great flexibility in defining boundary conditions. At first changes in anti-freezing solution temperatures measured were predicted in response to Thermal Response Test (TRT) conducted at our study site. Then, heat exchange and transfer processes for the vertical closed-loop GSHP systems were simulated to predict changes in ground and groundwater temperatures using three-dimensional domains.

  18. Failure Pressure Assessment of the Circumferentially Flawed Heat Exchanger Tubes

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Su; Jin, Tae Eun; Chang, Yoon Suk; Kim, Young Jin; Kim, Hong Deok

    Since the structural integrity of thin-walled tubes in the heat exchanger is crucial from the viewpoint of safety and reliability, the integrity evaluation for flawed tubes is quite important. Accurate estimation of the failure pressure is a key element of the structural integrity assessment. With regard to the prediction of the failure pressure, most of preceding researches have been focused on the limit load approach. However, the integrity assessment scheme based on the elastic plastic fracture mechanics concept has not been settled despite of its accuracy and efficiency. In this paper, three-dimensional finite element analyses assuming elastic plastic material behavior are carried out for the thin-walled tubes with various sizes of the circumferential flaws. As for the flaw location, both the top of tube sheet and transition regions are considered. The flaw instability is evaluated by comparing the driving force with the fracture toughness of the tube material. Analysis results show that the elastic plastic fracture mechanics approach accurately predicts the failure pressures compared to the experimental data. Thus, it is thought that the elastic plastic fracture mechanics concept can be applied to the integrity assessment of the heat exchanger tubes with the circumferential through-wall flaws.

  19. Continuation of Studies on Development of ODS Heat Exchanger Tubing

    SciTech Connect

    Lawrence Brown; David Workman; Bimal Kad; Gaylord Smith; Archie Robertson; Ian Wright

    2008-04-15

    The Department of Energy (DOE), National Energy Technology Center (NETL), has initiated a strategic plan for the development of advanced technologies needed to design and build fossil fuel plants with very high efficiency and environmental performance. These plants, referred to as 'Vision 21' and FutureGen programs by DOE, will produce electricity, chemicals, fuels, or a combination of these products, and possibly secondary products such as steam/heat for industrial use. MA956 is a prime candidate material being considered for a high temperature heat exchanger in the 'Vision 21' and FutureGen programs. This material is an oxide dispersion strengthened (ODS) alloy; however, there are some gaps in the data required to commit to the use of these alloys in a full-size plant. To fill the technology gaps for commercial production and use of the material for 'Advanced Power Generation Systems' this project has performed development activity to significant increase in circumferential strength of MA956 as compared to currently available material, investigated bonding technologies for bonding tube-to-tube joints through joining development, and performed tensile, creep and fire-side corrosion tests to validate the use and fabrication processes of MA956 to heat exchanger tubing applications. Development activities within this projected has demonstrated increased circumferential strength of MA956 tubes through flow form processing. Of the six fabrication technologies for bonding tube-to-tube joints, inertia friction welding (IFW) and flash butt welding (FBW) were identified as processes for joining MA956 tubes. Tensile, creep, and fire-side corrosion test data were generated for both base metal and weld joints. The data can be used for design of future systems employing MA956. Based upon the positive development activities, two test probes were designed and fabricated for field exposure testing at 1204 C ({approx}2200 F) flue gas. The probes contained tube portions with FBW and IFW welded MA956. Field testing of the probes and remaining heat exchanger design activity will be performed by Oak Ridge National Laboratory under DOE Contract DE-AC05-00OR22725.

  20. Experimental and theoretical analysis of the local condensation heat transfer in a plate heat exchanger

    NASA Astrophysics Data System (ADS)

    Grabenstein, V.; Kabelac, S.

    2012-11-01

    Plate heat exchanger (PHE) are today widely used in industrial heat transfer applications due to their good thermal performance, modest space requirement, easy accessibility to all areas and their lower capital and operating costs as compared to shell-and-tube heat exchangers. Although authoritative models for the design of PHE used as condensers are missing, the number of applications where a PHE is operating as a condenser increases. On the way to a reliable model based on physical approaches for the prediction of heat transfer and pressure drop during the condensation process inside a PHE, the flow and heat interactions as well as their dependence on the geometrical parameters of the corrugated plates and the operating conditions must be studied in detail. In this work the stepwise procedure for the fundamental construction of such a model is described. An experimental setup was built to analyze the characteristics of the two-phase-flow in PHE. A single gap, consisting of two transparent corrugated plates, was tested with a two-phase flow of air/water and also with boiling refrigerant R365mfc. Flow pattern maps were constructed for plates with corrugation angles of 27 and 63 degrees relative to the direction of flow. Investigations of the local heat transfer coefficients and the pressure drop were done with the same plates. The measurement of the local heat transfer coefficients was carried out by the use of the "Temperature Oscillation InfraRed Thermography" (TOIRT) method. Based on these results three main flow patterns are defined: film flow, bubbly flow and slug flow. For each of the three flow patterns an own model for the heat transfer and pressure drop mechanism are developed and the heat transfer coefficient and the friction factor is calculated with different equations depending on the actual steam quality, mass flow and geometrical parameters by means of a flow pattern map. The theory of the flow pattern based prediction models is proved with own experimental data. The measurements were carried out with an experimental setup in a technical scale. The refrigerant cycle works with R134a as refrigerant and involves two PHEs, used as condenser and evaporator, and a 55 kWel compressor for the compression of the vapor phase. The setup allows the measurement of quasi-local heat transfer coefficients inside the PHEs. Additional heat exchangers assure saturated vapor at the inlet and saturated liquid at the outlet of the condenser.

  1. Method for heat exchanger leak detection in a liquid metal cooled nuclear reactor

    Microsoft Academic Search

    Sayre

    1977-01-01

    An on-line method is described for early detection of a leak through a tube of a liquid metal-to-water tube type heat exchanger in a liquid metal cooled nuclear reactor system. Introducing helium to the heat exchanger feedwater exposes the helium to any heat exchanger leak locations, and the helium will diffuse or flow through the leak location into the liquid

  2. Design and optimization of coil finned-tube heat exchangers for cryogenic applications

    Microsoft Academic Search

    Prabhat Kumar Gupta; P. K. Kush; Ashesh Tiwari

    2007-01-01

    Coiled finned-tube heat exchangers have been used in small and medium helium refrigerators\\/liquefiers, miniature J–T refrigeration systems for many years. The efficiency of these cryogenic systems strongly depends on the thermal and pressure drop performance of these heat exchangers. A considerable improvement in the performance of heat exchanger is possible by choosing an appropriate geometrical configuration for a given process

  3. Development of Design Criteria for Fluid Induced Structural Vibration in Steam Generators and Heat Exchangers

    Microsoft Academic Search

    Ivan Catton; Vijay K. Dhir; O. S. Alquaddoomi; Deepanjan Mitra; Pierangelo Adinolfi

    2004-01-01

    OAK-B135 Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since

  4. Erosion of heat exchanger tubes in fluidized beds

    SciTech Connect

    Johnson, E.K.; Flemmer, R.L.C.

    1991-01-01

    This final report describes the activities of the 3-year project entitled Erosion of Heat Exchanger Tubes In Fluidized Beds.'' which was completed at the end of 1990. Project accomplishments include the collection of a substantial body of wear data In a 24in. [times] 24in. fluidized bed, comparative wear results In a 6in. [times] 6in. fluidized bed, the development of a dragometer and the collection of a comprehensive set of drag force data in the 24in. [times] 24in. bed, Fast Fourier Transform (FFT) analysis of bubble probe data to establish dominant bubble frequencies in the 24in. [times] 24in. bed, the use of a heat flux gauge for measurement of heat transfer coefficients in the 24in. [times] 24in. bed and the modeling of the tube wear in the 24in. [times] 24in. bed. Analysis of the wear data from the 24in. square bed indicates that tube wear increases with increase in superficial velocity, and with increase in tube height. The latter effect is a result of the tubes higher up in the bed seeing greater movement of dense phase than tubes lower down In the bed. In addition, tube wear was found to decrease with increase in particle size, for constant superficial velocity. Three models of tube wear were formulated and provided acceptable prediction of wear when compared with the experimental data.

  5. A small and light weight heat exchanger for on-board helium refrigerator

    NASA Technical Reports Server (NTRS)

    Koizumi, T.; Takahashi, M.; Uchida, T.; Kanazawa, Y.; Suzuki, M.

    1983-01-01

    A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains.

  6. A small and light weight heat exchanger for on-board helium refrigerator

    NASA Astrophysics Data System (ADS)

    Koizumi, T.; Takahashi, M.; Uchida, T.; Kanazawa, Y.; Suzuki, M.

    1983-12-01

    A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains.

  7. Development of Design Criteria for Fluid Induced Structural Vibrations in Steam Generators and Heat Exchangers

    SciTech Connect

    Uvan Catton; Vijay K. Dhir; Deepanjan Mitra; Omar Alquaddoomi; Pierangelo Adinolfi

    2004-04-06

    Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers.

  8. Waste Heat Recovery From Stacks Using Direct-Contact Condensing Heat Exchange

    E-print Network

    Thorn, W. F.

    Similarly, the recuperator can be interfaced with the auxiliary tank, heat exchanger and boiler controls in a In considering multiple boiler installations, the CON variety of ways. Several recuperators, individually installed X recuperator may...-X RECUPERATOR (4) STACK CON?X DIAMETER SELECTEDASA FUNCTION OF THE 15) EXHAUST BLOWER UNDER CLOSED-LOOP USABLE RECOVERED ENERGY. CONTROL WITH BOILER FIRING LEVEL. o CON? X 5 H t VARIANT NO.2 WITH SEPARATE STACK Figure 10. "Bypass" Mounting of a co...

  9. Testing and analysis of load-side immersed heat exchangers for solar domestic hot water systems

    SciTech Connect

    Farrington, R.B.; Bingham, C.E.

    1987-10-01

    This report describes work to determine the performance of load-side heat exchangers for use in residential solar domestic hot water systems. We measured the performance of four heat exchangers: a smooth coil and a finned coil having heat transfer areas of 2.5 m/sup 2/ (26 ft/sup 2/) and those having areas of 1.7 m/sup 2/ (19 ft/sup 2/). A numerical model using the thermal network program MITAS was constructed, and results were compared to the experimental results. Research showed a smooth coil with only 70% of the surface area of a finned coil performed better than the finned coil. Also, load-side heat exchangers can maintain and enhance stratification in storage tanks, permitting the use of control strategies that take advantage of stratified storage tanks to increase system performance. The analytical model, which agreed reasonably well with the experimental results, was used to vary heat exchanger flow rate and area and initial tank temperature for both a smooth- and a finned-coil heat exchanger. Increasing the heat exchanger flow rate and area results in higher heat transfer rates but not necessarily optimal performance. Lower initial tank temperatures resulted in reduced tank stratification. The smooth heat exchanger outperformed the finned heat exchanger with the same outside surface area. 15 refs., 37 figs., 9 tabs.

  10. Application of Hourly Simulation in Designing Vertical U-Pipe Underground Heat Exchanger of Ground Source Heat Pump System

    Microsoft Academic Search

    Hua Su; Xungen Shi

    2010-01-01

    Design of underground heat exchanger is crucial to application of ground source heat pump system. This paper presents the method and self-developed program for designing vertical U-pipe underground heat exchanger using numerical simulation. The program's accuracy was validated by comparison of outlet temperature between field test and simulation: the biases are not more than 1 centi-degree in most cases. This

  11. A microchannel heat exchanger design for microelectronics cooling correlating the heat transfer rate in terms of Brinkman number

    Microsoft Academic Search

    HeeSung Park

    2009-01-01

    Microchannel heat exchangers are a well known device in the application of microelectronics cooling. In this paper, liquid\\u000a microchannel heat exchangers were designed and investigated with varying channel width in order to find the maximum cooling\\u000a efficiency when combined with pumping performance. A recently developed correlation of heat transfer rate in terms of Nusselt\\u000a number and Brinkman number was adopted

  12. Heat transfer characteristics of a temperature-dependent-property fluid in shell and coiled tube heat exchangers

    Microsoft Academic Search

    M. R. Salimpour

    2008-01-01

    An experimental investigation was performed to study the heat transfer characteristics of temperature-dependent-property engine-oil inside shell and coiled tube heat exchangers. For this purpose, a well-instrumented set-up was designed and constructed. Three heat exchangers with different coil pitches were selected as the test section for counter-flow configuration. Engine-oil was circulated inside the inner coiled tube, while coolant water flowed in

  13. Heat exchanger design for thermoelectric electricity generation from low temperature flue gas streams

    E-print Network

    Latcham, Jacob G. (Jacob Greco)

    2009-01-01

    An air-to-oil heat exchanger was modeled and optimized for use in a system utilizing a thermoelectric generator to convert low grade waste heat in flue gas streams to electricity. The NTU-effectiveness method, exergy, and ...

  14. Nonograms for calculation of heat-exchanger lenses

    SciTech Connect

    Esarev, V.I.

    1986-07-01

    The authors attempt to select the most optimum lens dimensions corresponding to a specific operating life. Studies which, on the basis of a large number of experimental investigation, give dependences determining the limit of operating life in the calculation of the lens as a shell in the elastic region. The expression derived from the studies makes it possible to simplify the calculation previously used, with sufficient accuracy for practical purposes, and especially in the case of heat-exchanger lenses, to apply the well-known method of calculation in the elastic region. Nonograms for determination of stresses in lenses and lens strength were constructed. The nonograms constructed make it possible to determine and characterize the stress-deformed state of the lens. Satisfactory agreement was obtained between the data obtained by the calculation using the nonograms and the experimental data.

  15. Thermal self-oscillations in radiative heat exchange

    NASA Astrophysics Data System (ADS)

    Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.

    2015-02-01

    We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO2 and VO2 which exchange heat by thermal radiation in vacuum. The non-linear feedback in the self-oscillating system is provided by metal-insulator transition in VO2. Using the method of fluctuational electrodynamics, we show that under the action of an external laser of a constant power, the temperature of VO2 plate oscillates around its phase transition value. The period and amplitude of oscillations depend on the geometry of the structure. We found that at 500 nm vacuum gap separating bulk SiO2 plate and 50 nm thick VO2 plate, the period of self-oscillations is 2 s and the amplitude is 4 K, which is determined by phase switching at threshold temperatures of phase transition.

  16. Ceramic heat exchangers. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1996-04-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  17. Ceramic heat exchangers. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1997-02-01

    The bibliography contains citations of selected patents concerning the use of ceramic materials in the manufacture of industrial heat exchangers. The focus is on ceramics that display resistance to high temperature corrosion, abrasion, wear, and thermal shock. The design and fabrication of rotary, regenerative, and recuperative heat exchangers are discussed. Ceramic heat exchangers for uses in gas turbines, waste heat recovery equipment, and central heating systems are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  18. Choosing the optimum bed material for a fluidized bed heat exchanger

    SciTech Connect

    Williams, H.W.; Hernandez, R.; Mah, C.S.

    1981-01-01

    Shallow-bed fluidized bed, heat exchangers have been intensively studied for various applications and found to be competitive with conventional heat exchangers. Work has proceeded in studies for waste heat recovery, cooling system for heat pumps, dry cooling towers for power plants, and others. The Aerojet Energy Conversion Company (AECC) in a contract with the Department of Energy (DOE), is currently conducting a program to identify the ideal bed material for a given application. 10 refs.

  19. Combined simulation-optimization of borehole heat exchanger fields

    NASA Astrophysics Data System (ADS)

    Bayer, Peter; Beck, Markus; Hecht-Mendez, Jozsef; de Paly, Michael

    2013-04-01

    Currently, far more than one million ground-source heat pump systems are installed in Europe for space heating of buildings. Most of these are single, closed, vertical systems, with borehole heat exchangers (BHEs) that penetrate shallow aquifers down to a depth of about 100-200 m. Multiple BHE fields that are implemented for large-scale geothermal energy supply of buildings or district heating systems are of increasing importance. In comparison to the straightforward design of single BHE systems, concerted operation of several BHEs is more challenging. Multiple adjacent BHEs can interact and affect each other. Large-scale, non-uniform thermal anomalies are potentially generated in the ground. Mutual interaction among BHEs could have an influence on the overall system's performance and therefore, should be either circumvented or integrated in the operation strategy. However, so far strategic tuning of energy extraction rates of the individual BHEs in space and time has not been considered in practice. In our presentation, a combined simulation-optimization approach is presented to regulate the individual operation of BHEs. The BHE field is simulated analytically, by temporally and spatially superimposed line source equations, as well as in more detail in numerical models. Both conditions with and without horizontal groundwater flow are studied. Groundwater flow means an additional advective energy supply, which is advantageous but also complicates apposite multiple BHE adjustment. The optimization task is formulated in an objective function to minimize the thermal impact in the ground, to avoid extreme temperature anomalies, and by this, enhance heat pump performance. We select linear programming to optimize the time-dependent loads in a computationally efficient way. Evolutionary algorithms are utilized when the BHE positions are adjusted. In different hypothetical applications with given seasonal changing load profiles and variable BHE configurations we show that either individual BHE heat extraction or position optimization is sufficient, and that only little improvement potential exists for joint optimization of both aspects. It is also demonstrated that groundwater flow direction and velocity has substantial influence on the identified ideal BHE operation patterns. Increase of groundwater flow velocity means more energy supply, and thus a better thermal recovery for given energy extraction rates. As a consequence, this mitigates the benefit from optimized BHE operation.

  20. Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow

    PubMed Central

    2011-01-01

    This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration. PMID:21827644

  1. Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow.

    PubMed

    Teng, Tun-Ping; Hung, Yi-Hsuan; Teng, Tun-Chien; Chen, Jyun-Hong

    2011-01-01

    This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration. PMID:21827644

  2. Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow

    NASA Astrophysics Data System (ADS)

    Teng, Tun-Ping; Hung, Yi-Hsuan; Teng, Tun-Chien; Chen, Jyun-Hong

    2011-08-01

    This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration.

  3. Borehole Heat Exchangers: heat transfer simulation in the presence of a groundwater flow

    NASA Astrophysics Data System (ADS)

    Angelotti, A.; Alberti, L.; La Licata, I.; Antelmi, M.

    2014-04-01

    The correct design of the Borehole Heat Exchanger is crucial for the operation and the energy performance of a Ground Source Heat Pump. Most design methods and tools are based on the assumption that the ground is a solid medium where conduction is the only heat transfer mechanism. In turn in regions rich in groundwater the groundwater flow influence has to be assessed, by including the convection effects. In this paper a numerical model of a 100 m U-pipe in a saturated porous medium is presented. The model is created adopting MT3DMS coupled to MODFLOW. A Darcy flow is imposed across the medium. The typical operation of a Borehole Heat Exchanger operating both in winter and in summer is simulated for two years, under different groundwater velocities. The energy injected to and extracted from the ground is derived as a function of the Darcy velocity and compared with the purely conductive case. Temperature fields in the ground at key moments are shown and discussed. From both the energy and the aquifer temperature field points of view, the velocity ranges for respectively negligible and relevant influence of the groundwater flow are identified.

  4. Improved method and case study of thermal response test for borehole heat exchangers of ground source heat pump system

    Microsoft Academic Search

    Huajun Wang; Chengying Qi; Hongpu Du; Jihao Gu

    2010-01-01

    Thermal response test (TRT) is crucial for the determination of the ground thermal conductivity and the evaluation of the thermal performance of borehole heat exchangers (BHEs) of ground source heat pump (GSHP) system. This paper presented a novel constant heating-temperature method (CHTM) for TRT. Further, a type of improved TRT equipment was developed and the mathematical model to deal with

  5. A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2010-01-01

    Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight gas-gas heat exchanger designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat exchanger units into closed cycle gas turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat exchanger effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat exchanger effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat exchanger required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat exchanger volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat exchanger weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/(kg/sec), show the dimensional consistency of overall results.

  6. A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2010-01-01

    Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight gas-gas heat exchanger designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat exchanger units into closed cycle gas turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat exchanger effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat exchanger effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat exchanger required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat exchanger volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat exchanger weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/ (kg/sec), show the dimensional consistency of overall results.

  7. The single-blow transient testing technique for plate–fin heat exchangers

    Microsoft Academic Search

    Xing Luo; Wilfried Roetzel

    2001-01-01

    A new model of the single-blow problem is proposed, considering the lateral heat conduction resistance along the fins, the axial heat conduction along the separating plates and the axial thermal dispersion in the fluid. For plate–fin heat exchangers made up of stainless steel, the effect of the lateral heat conduction resistance along the fins can usually not be neglected. This

  8. Foundation Heat Exchanger Final Report: Demonstration, Measured Performance, and Validated Model and Design Tool

    Microsoft Academic Search

    Patrick Hughes; Piljae Im

    2012-01-01

    Geothermal heat pumps, sometimes called ground-source heat pumps (GSHPs), have been proven capable of significantly reducing energy use and peak demand in buildings. Conventional equipment for controlling the temperature and humidity of a building, or supplying hot water and fresh outdoor air, must exchange energy (or heat) with the building's outdoor environment. Equipment using the ground as a heat source

  9. Solar power converter with pool boiling receiver and integral heat exchanger

    Microsoft Academic Search

    D. B. Osborn; R. L. Pons

    1982-01-01

    A solar converter is disclosed which has particular applicability at the focal point of a parabolic concentrator. The converter absorbs solar thermal radiation in a cavity type receiver and transports the heat via a secondary fluid to a heat exchanger which contains a primary (I.E., working) fluid used for process heating or to power a heat engine employing either stirling,

  10. Numerical Study on Characteristics of a Pre-Cooling He II Heat Exchanger

    SciTech Connect

    Ueno, Y.; Okamura, T. [Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8502 (Japan); Sato, A. [National Institute for Materials Science, Tsukuba, Ibaraki, 305-0047 (Japan)

    2004-06-23

    A numerical analysis has been performed in order to investigate the heat transfer and pressure drop characteristics of a pre-cooling He II heat exchanger. The heat conduction in the pre-cooled helium path in the flow direction was taken into account. Temperature distribution and pressure drop in the heat exchanger have been calculated for various conditions. It was found that a long cooling path is required to pre-cool the helium below the {lambda}-temperature, because of a large value of the He II heat conductivity function. This heat exchanger has an upper limit of mass flow rate. The efficiency of the heat exchanger decreases as the mass flow rate decreases under a small mass flow rate condition.

  11. A theory for heat exchangers with liquid-desiccant-wetted surfaces

    SciTech Connect

    Otterbein, R.T. [Otterbein Engineering, Phoenix, AZ (United States)

    1995-08-01

    The following theory extends the wet surface model of Maclaine-cross and Banks (1981) to include heat exchangers that heat or cool moist air with liquid-desiccant-wetted surfaces. The theory uses a wall boundary condition that forces the moist air to be at an arbitrary relative humidity that is less than totally saturated. The theory defines a new temperature scale (brine-bulb temperature) for which the wet-bulb temperature is a special case. Brine-bulb heat capacitance and heat transfer coefficient are defined. By using an analogy to the dry surface heat exchanger theory, the performance of these heat exchangers can then be estimated from the performance of geometrically identical heat exchangers with a dry surface. Charts to utilize the theory at various elevations are shown.

  12. AN OLD QUALITY LESSON FROM FAILURE OF A NEW HEAT EXCHANGER

    Microsoft Academic Search

    Scott J. Whitlow

    A Gulf Coast manufacturing unit has three heat exchangers in its reaction overhead off-gas system. All the heat exchangers are once-through condensers with carbon steel shells, zirconium tubes and double tube sheets. There are four reaction trains in the manufacturing unit for a total of 12 condensers. All have many years of satisfactory service except the newest condenser which failed

  13. SPECIAL ANALYSIS FOR SLIT TRENCH DISPOSAL OF THE REACTOR PROCESS HEAT EXCHANGERS

    Microsoft Academic Search

    L. Hamm; L. Collard; S. Aleman; M. Gorensek; T. Butcher

    2012-01-01

    The Savannah River National Laboratory (SRNL), in response to a request from Solid Waste Management (SWM), conducted a Special Analysis (SA) to evaluate the performance of nineteen heat exchangers that are to be disposed in the E-Area low level waste facility Slit Trench 9 (ST 9). Although these nineteen heat exchangers were never decontaminated, the majority of the radionuclides in

  14. CFD simulation on inlet configuration of plate-fin heat exchangers

    Microsoft Academic Search

    Zhe Zhang; YanZhong Li

    2003-01-01

    A computational fluid dynamics (CFD) program FLUENT has been used to predict the fluid flow distribution in plate-fin heat exchangers. It is found that the flow maldistribution is very serious in the y direction of header for the conventional header used in industry. The results of flow maldistribution are presented for a plate-fin heat exchanger, which is simulated according to

  15. Characterization of elevated temperature properties of heat exchanger and steam generator alloys

    Microsoft Academic Search

    J. K. Wright; L. J. Carroll; C. J. Cabet; T. Lillo; J. K. Benz; J. A. Simpson; W. R. Lloyd; J. A. Chapman; R. N. Wright

    2010-01-01

    The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800°C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950°C. Although both alloys are

  16. Study of heat exchange during interaction between an electric arc and a longitudinal gas flow

    Microsoft Academic Search

    A. I. Ivliutin; Iu. V. Kurochkin; E. I. Molodykh; A. V. Pustogarov; M. N. Supronenko

    1975-01-01

    An experimental investigation was made of the local heat exchange in a gas flow in a cylindrical electric-arc channel which is insulated from the electrodes. Argon and helium flows were studied, with Reynolds numbers ranging from 50 to 9000. It was found that the nature of the heat exchange in the stabilized arc channel with Re less than 300-500 is

  17. Low-Reynolds-number heat-exchange drag in liquid helium II

    Microsoft Academic Search

    Robert Lynch

    1982-01-01

    Recently the author showed that a calculation of the heat-exchange drag on a sphere given by Springett is incorrect, but offered no alternative result. In this paper a calculation of the normal fluid heat-exchange drag is given which is valid for low (stream) Reynolds number. The basic differential equation of the theory must be solved numerically. However, an approximate result

  18. Thermal analysis of a helical heat exchanger for ground thermal energy storage in arid zones

    Microsoft Academic Search

    Y. Rabin; E. Korin

    1996-01-01

    A mathematical model for thermal analysis of a helical heat exchanger for long-term thermal energy storage in soil for use in arid zones was developed. The helical heat exchanger was modeled as a series of horizontal rings with a constant pitch distance between them. The model was solved by a finite difference method, using a microcomputer, and validated with experimental

  19. Three-dimensional structural analysis of the plate-fin heat exchanger

    Microsoft Academic Search

    T. Nakagawa; T. Sou

    1984-01-01

    The Brazed aluminum plate-fin heat exchanger is a complex structure consisting of a core, headers and nozzles. The core is built of many layers of flat parting sheets and corrugated fins, and is sealed by side bars. Stress patterns in this type of heat exchanger have so far not been accurately analyzed, due to the complexity of the structure. A

  20. Plate-fin heat exchanger performance reduction in special two-phase flow conditions

    Microsoft Academic Search

    T. Müller-Menzel; T. Hecht

    1995-01-01

    This paper discusses the occurrence of various flow patterns of a cold, upflowing two-phase stream in an aluminium plate-fin heat exchanger (PFHE) and their impact on the overall heat exchanger performance. Various flow patterns were observed in a flow visualization rig comprising a single PFHE passage. At high gas mass fluxes both phases flow uniformly upwards. When decreasing the gas

  1. HEAT EXCHANGER WITH AN ELECTROMAGNETIC PUMP FOR APPLICATION IN ENERGY PLANT INSTALLATIONS

    Microsoft Academic Search

    S. Krysko; A. Poznaks; S. Dementjev

    Introduction. A new conceptual solution for the heat exchanging aggregate LIQUID METAL - OIL - WATER in Accelerator-Driven System is presented. The idea of the concept is combination of a heat exchanger with a MHD-pump in one common unit. The advantage of such solution is its compactness and possibility to use the oil loop simultaneously also as a system for

  2. Earth to air heat exchanger conditioning potential in an office building in a continental mediterranean climate

    Microsoft Academic Search

    C. Sanchez-Guevara; N. Urrutia del Campo; J. Neila

    2011-01-01

    This article presents the result performance improvement due to the use of a exchanger of an office building located in Ext The climate in this region is Continental M mild winters and very hot summers. The firs data measures allowed the validation of the si Heating and cooling building loads were ev without earth to air heat exchanger. Also, a

  3. Wellsite verification testing of an advanced geothermal primary heat exchanger (APEX)

    Microsoft Academic Search

    J. F. Addoms; C. M. Gracey

    1977-01-01

    The well-site test phase is described of a research program conducted by Aerojet Liquid Rocket Company to establish the feasibility of using a recirculating solid bed material to eliminate heat exchanger fouling in geothermal service. The concept was directed towards application as the primary heat exchanger in a geothermal power plant which utilizes a binary cycle. The APEX approach was

  4. Problems with Specifying ? T min in the Design of Processes with Heat Exchangers

    Microsoft Academic Search

    Jørgen Bauck Jensen; Sigurd Skogestad

    2008-01-01

    We show in this article that the common method of specifying ¢Tmin for individual heat exchangers may lead to wrong decisions and should be used with care when designing heat exchanger systems. In particular, design with constraints on ¢Tmin may result in operation conditions that are not optimal when the resulting areas are installed. In addition, different U values for

  5. Cost-Effective Bypass Design of Highly Controllable Heat-Exchanger Networks

    E-print Network

    Huang, Yinlun

    Cost-Effective Bypass Design of Highly Controllable Heat-Exchanger Networks Q. Z. Yan, Y. H. Yang 48202 ( )Design of a cost-effecti®e and highly controllable heat-exchanger network HEN has drawn a great undesirable disturbance propagation in a network with minimum cost increment. Design options in this regard

  6. Performance investigation of plain and finned tube evaporatively cooled heat exchangers

    Microsoft Academic Search

    Ala Hasan; Kai Sirén

    2003-01-01

    The performance of two evaporatively cooled heat exchangers is investigated under similar operating conditions of air flow rates and inlet hot water temperatures. The heat exchangers are plain and plate-finned circular tube types which occupy the same volume. Spray water, which is circulated in a closed circuit, is injected onto the exposed surfaces of the tubes and fins. The contact

  7. A Laboratory Exercise Using a Physical Model for Demonstrating Countercurrent Heat Exchange

    ERIC Educational Resources Information Center

    Loudon, Catherine; Davis-Berg, Elizabeth C.; Botz, Jason T.

    2012-01-01

    A physical model was used in a laboratory exercise to teach students about countercurrent exchange mechanisms. Countercurrent exchange is the transport of heat or chemicals between fluids moving in opposite directions separated by a permeable barrier (such as blood within adjacent blood vessels flowing in opposite directions). Greater exchange of…

  8. Fouling reduction characteristics of a no-distributor-fluidized-bed heat exchanger for flue gas heat recovery

    SciTech Connect

    Jun, Y.D.; Lee, K.B.; Islam, S.Z.; Ko, S.B. [Kongju National University, Kong Ju (Republic of Korea). Dept. for Mechanical Engineering

    2008-07-01

    In conventional flue gas heat recovery systems, the fouling by fly ashes and the related problems such as corrosion and cleaning are known to be major drawbacks. To overcome these problems, a single-riser no-distributor-fluidized-bed heat exchanger is devised and studied. Fouling and cleaning tests are performed for a uniquely designed fluidized bed-type heat exchanger to demonstrate the effect of particles on the fouling reduction and heat transfer enhancement. The tested heat exchanger model (1 m high and 54 mm internal diameter) is a gas-to-water type and composed of a main vertical tube and four auxiliary tubes through which particles circulate and transfer heat. Through the present study, the fouling on the heat transfer surface could successfully be simulated by controlling air-to-fuel ratios rather than introducing particles through an external feeder, which produced soft deposit layers with 1 to 1.5 mm thickness on the inside pipe wall. Flue gas temperature at the inlet of heat exchanger was maintained at 450{sup o}C at the gas volume rate of 0.738 to 0.768 CMM (0.0123 to 0.0128 m{sup 3}/sec). From the analyses of the measured data, heat transfer performances of the heat exchanger before and after fouling and with and without particles were evaluated. Results showed that soft deposits were easily removed by introducing glass bead particles, and also heat transfer performance increased two times by the particle circulation. In addition, it was found that this type of heat exchanger had high potential to recover heat of waste gases from furnaces, boilers, and incinerators effectively and to reduce fouling related problems.

  9. A mathematical model for the simulation of closed-loop earth-coupled heat exchangers for a water source heat pump 

    E-print Network

    De Lange, Kevin Jon

    1988-01-01

    Temperature. Pipe and Soil Temperatures. Applications. . Vertical Concentric Heat Exchanger. Horizontal Single Pipe Heat Exchanger. . . . . . Vertical U-tube Heat Exchanger Model Software. Model Parameters. Convective Surface Heat Transfer Coefficients... configurations. . . 53 14. Placement of thermocouple probes for the horizontal single pipe configuration. CHAPTER I INTRODUCTION In recent years there has been an increase in the use of heat pumps for space heating and cooling. In the late 1970's...

  10. Performance Characteristics of Cross-Fin-Tube-Type Heat Exchanger for Air Conditioner

    NASA Astrophysics Data System (ADS)

    Sasaki, Naoe; Kakiyama, Shiro; Sanuki, Noriyoshi

    The effects of enhanced heat transfer tube with ability to control the heat transfer disturbance by mechanical tube expanding were experimentally investigated on the performance characteristics of air-cooled cross-fin-tube-type heat exchanger for air conditioner. Three kinds of the enhanced heat transfer tube were developed and used in the experiment. The enhanced heat transfer tube was a kind of spirally grooved tube and composed with the fins smaller than those of the conventional spirally grooved tube excepting four fins located in orthogonal position on the tube circumference. The optimum groove number to enhance the performance of heat exchanger was also shown.

  11. An Experimental Study of Upward and Downward Flow of Supercritical Carbon Dioxide in a Straight Pipe Heat Exchanger with Constant Wall Heat Flux

    E-print Network

    Umrigar, Eric Dara

    2014-05-01

    An experimental analysis was conducted on a single circular tube heat exchanger using supercritical carbon dioxide as the working fluid. The heat exchanger was operated in two different orientations: vertically upward and downward. The experimental...

  12. Numerical study of heat transfer enhancement of counter nanofluids flow in rectangular microchannel heat exchanger

    NASA Astrophysics Data System (ADS)

    Mohammed, H. A.; Bhaskaran, G.; Shuaib, N. H.; Saidur, R.

    2011-09-01

    This paper reports a numerical analysis of the performance of a counter-flow rectangular shaped microchannel heat exchanger (MCHE) using nanofluids as the working fluids. Finite volume method was used to solve the three-dimensional steady, laminar developing flow and conjugate heat transfer in aluminum MCHE. The nanofluids used were Ag, Al 2O 3, CuO, SiO 2, and TiO 2 and the performance was compared with water. The thermal, flow fields and performance of the MCHE were analyzed using different nanofluids, different Reynolds numbers and different nanoparticle concentrations. Temperature profile, heat transfer coefficient, pressure profile, and wall shear stress were obtained from the simulations and the performance was discussed in terms of heat transfer rate, pumping power, effectiveness, and performance index. Results indicated enhanced performance with the usage of nanofluids, and slight penalty in pressure drop. The increase in Reynolds number caused an increase in the heat transfer rate and a decrease in the overall bulk temperature of the cold fluid. The increase in nanoparticle concentration also yielded better performance at the expense of increased pressure drop.

  13. Performance of multi tubes in tube helically coiled as a compact heat exchanger

    NASA Astrophysics Data System (ADS)

    Nada, S. A.; El Shaer, W. G.; Huzayyin, A. S.

    2014-12-01

    Multi tubes in tube helically coiled heat exchanger is proposed as a compact heat exchanger. Effects of heat exchanger geometric parameters and fluid flow parameters; namely number of inner tubes, annulus hydraulic diameter, Reynolds numbers and input heat flux, on performance of the heat exchanger are experimentally investigated. Different coils with different numbers of inner tubes, namely 1, 3, 4 and 5 tubes, were tested. Results showed that coils with 3 inner tubes have higher values of heat transfer coefficient and compactness parameter (bar{h} Ah ). Pressure drop increases with increasing both of Reynolds number and number of inner tubes. Correlations of average Nusselt number were deduced from experimental data in terms of Reynolds number, Prandtl number, Number of inner coils tubes and coil hydraulic diameter. Correlations prediction was compared with experimental data and the comparison was fair enough.

  14. [Heat exchange between human body and environment (theoretical bases of physiological measurement and evaluation)].

    PubMed

    Pezzagno, G

    1999-01-01

    In the first part of this report the theory of the heat exchange between human body and external environment is developed. In particular, the problems concerning energy expenditure and heat production [metabolic heat] during physical activity, the heat exchange between internal organs and body surface, and its elimination are considered. Proposal of heat exchange equations (in case of conduction, convection, evaporation, radiation transport) are made, and the involved parameters and constants are indicated. Some pages are devoted to heat exchange through the lung and to "perspiratio insensibilis". In the second part the problems concerning the wellbeing and the thermal discomfort are discussed. A description of some widely employed indices of thermal stress, strain and comfort concludes the report [P4SR index, HSI index, ITS index, TTL index, HR index, WBGT index, TE indices]. In the end, the Fanger equations of thermal comfort are presented and discussed. PMID:10771731

  15. Numerical Study of Convective Heat Transfer in Flat Tube Heat Exchangers Operating in Self-Sustained Oscillatory Flow Regimes 

    E-print Network

    Fullerton, Tracy

    2012-02-14

    Laminar, two-dimensional, constant-property numerical simulations of flat tube heat exchanger devices operating in flow regimes in which self-sustained oscillations occur were performed. The unsteady flow regimes were transition flow regimes...

  16. Research for Advanced Heat Exchangers- The U.S. DOE Program

    E-print Network

    Richlen, S. L.

    Programs has made significant contributions to the development of advanced heat exchanger technology to save energy for U.S. industry. Currently the Program is field testing two large ceramic tubular high temperature waste heat recuperators and one... developed. Other areas of research include development of advanced NnE techniques for study of ceramic materials and development of new forming techniques. A new effort of great promise is the study of ceramic composites as a potential heat exchanger...

  17. Numerical modeling of compact high temperature heat exchanger and chemical decomposer for hydrogen production

    Microsoft Academic Search

    Valery Ponyavin; Yitung Chen; Anthony E. Hechanova; Merrill Wilson

    2008-01-01

    The present study addresses fluid flow and heat transfer in a high temperature compact heat exchanger which will be used as\\u000a a chemical decomposer in a hydrogen production plant. The heat exchanger is manufactured using fused ceramic layers that allow\\u000a creation of channels with dimensions below 1 mm. The main purpose of this study is to increase the thermal performance of

  18. Brain emotional learning based intelligent controller applied to neurofuzzy model of micro-heat exchanger

    Microsoft Academic Search

    Hossein Rouhani; Mahdi Jalili; Babak Nadjar Araabi; Wolfgang Eppler; Caro Lucas

    2007-01-01

    In this paper, an intelligent controller is applied to govern the dynamics of electrically heated micro-heat exchanger plant. First, the dynamics of the micro-heat exchanger, which acts as a nonlinear plant, is identified using a neurofuzzy network. To build the neurofuzzy model, a locally linear learning algorithm, namely, locally linear mode tree (LoLiMoT) is used. Then, an intelligent controller based

  19. Winglet-Type Vortex Generators with Common-Flow Configuration for Fin-Tube Heat Exchangers

    Microsoft Academic Search

    A. Jain; G. Biswas; D. Maurya

    2003-01-01

    This investigation stems from the area of augmentation of heat transfer by generating streamwise longitudinal vortices. The vortex generators are arranged in a common-flow-up configuration. Existing air-cooled condensers in geothermal power plants use fin-tube heat exchangers with circular tubes. The heat exchangers are huge, and often the cost of the condensers is more than one-third of the plant cost. The

  20. Heat exchanger and method of making. [bonding rocket chambers with a porous metal matrix

    NASA Technical Reports Server (NTRS)

    Fortini, A.; Kazaroff, J. M. (inventors)

    1978-01-01

    A heat exchanger of increased effectiveness is disclosed. A porous metal matrix is disposed in a metal chamber or between walls through which a heat-transfer fluid is directed. The porous metal matrix has internal bonds and is bonded to the chamber in order to remove all thermal contact resistance within the composite structure. Utilization of the invention in a rocket chamber is disclosed as a specific use. Also disclosed is a method of constructing the heat exchanger.

  1. Optimal allocation of heat-exchanger area for refrigeration and air-conditioning plants

    Microsoft Academic Search

    Lingen Chen; Fengrui Sun; Chih Wu

    2004-01-01

    The performance of the Carnot cycle and a vapor-compression refrigeration cycle can be optimized by the choice of a heat-exchanger area between the evaporator and the condenser. In this paper, the analytical expressions for the optimal allocation of heat-exchanger area for the endoreversible and irreversible Carnot cycles with constant- and variable-temperature heat-reservoirs are derived. The optimal values for real vapor-compression

  2. Effect of inlet and outlet shellside flow and heat transfer on the performance of HTGR straight tube heat exchangers

    Microsoft Academic Search

    Carosella

    1984-01-01

    Since the mid-1970s, various high temperature gas-cooled reactor (HTGR) steam generator, auxiliary heat exchanger (AHE), recuperator, and intermediate heat exchanger (IHX) designs have been proposed that use straight tube configurations. Each of these designs requires 90-deg turns in the helium gas flow at the inlet and\\/or outlet of the tube bundle. To evaluate the effect of these turns on the

  3. Vortex-Generator Pairs for Vortex-Induced Heat-Transfer Enhancement in Heat-Exchanger Channels

    Microsoft Academic Search

    Markus Rütten; Lars Krenkel

    \\u000a The objective of the presented work is to investigate possibilities for increasing the heattransfer in heat-exchanger channels\\u000a for aircraft applications by using flow-manipulating devices. Focal point of the investigation are different arrangements\\u000a of vortex-generator pairs within a generic heat-exchanger channel. The DLR URANS CFD solver THETA has been used to carry out\\u000a numerical simulations of the laminar flow within a

  4. Model of Heat Exchangers for Waste Heat Recovery from Diesel Engine Exhaust for Thermoelectric Power Generation

    NASA Astrophysics Data System (ADS)

    Baker, Chad; Vuppuluri, Prem; Shi, Li; Hall, Matthew

    2012-06-01

    The performance and operating characteristics of a hypothetical thermoelectric generator system designed to extract waste heat from the exhaust of a medium-duty turbocharged diesel engine were modeled. The finite-difference model consisted of two integrated submodels: a heat exchanger model and a thermoelectric device model. The heat exchanger model specified a rectangular cross-sectional geometry with liquid coolant on the cold side, and accounted for the difference between the heat transfer rate from the exhaust and that to the coolant. With the spatial variation of the thermoelectric properties accounted for, the thermoelectric device model calculated the hot-side and cold-side heat flux for the temperature boundary conditions given for the thermoelectric elements, iterating until temperature and heat flux boundary conditions satisfied the convection conditions for both exhaust and coolant, and heat transfer in the thermoelectric device. A downhill simplex method was used to optimize the parameters that affected the electrical power output, including the thermoelectric leg height, thermoelectric n-type to p-type leg area ratio, thermoelectric leg area to void area ratio, load electrical resistance, exhaust duct height, coolant duct height, fin spacing in the exhaust duct, location in the engine exhaust system, and number of flow paths within the constrained package volume. The calculation results showed that the configuration with 32 straight fins was optimal across the 30-cm-wide duct for the case of a single duct with total height of 5.5 cm. In addition, three counterflow parallel ducts or flow paths were found to be an optimum number for the given size constraint of 5.5 cm total height, and parallel ducts with counterflow were a better configuration than serpentine flow. Based on the reported thermoelectric properties of MnSi1.75 and Mg2Si0.5Sn0.5, the maximum net electrical power achieved for the three parallel flow paths in a counterflow arrangement was 1.06 kW for package volume of 16.5 L and exhaust flow enthalpy flux of 122 kW.

  5. Annular flow enhanced two-phase evaporative heat exchanger for space-based systems

    Microsoft Academic Search

    D. Nikanpour

    1991-01-01

    The development of multi-kilowatt space-based systems requires the transport of waste heat loads over long distances in micro-gravity conditions. In this context two-phase heat transport systems are attractive enabling a high rate of heat transport with low pump powers compared to single phase systems. In this context the design of a two-phase heat exchanger to transfer heat from a single-phase

  6. 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.

  7. State of technology of direct contact heat exchanging

    SciTech Connect

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

    1984-05-01

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

  8. Heat transfer in a compact heat exchanger containing rectangular channels and using helium gas

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1991-01-01

    Development of a National Aerospace Plane (NASP), which will fly at hypersonic speeds, require novel cooling techniques to manage the anticipated high heat fluxes on various components. A compact heat exchanger was constructed consisting of 12 parallel, rectangular channels in a flat piece of commercially pure nickel. The channel specimen was radiatively heated on the top side at heat fluxes of up to 77 W/sq cm, insulated on the back side, and cooled with helium gas flowing in the channels at 3.5 to 7.0 MPa and Reynolds numbers of 1400 to 28,000. The measured friction factor was lower than that of the accepted correlation for fully developed turbulent flow, although the uncertainty was high due to uncertainty in the channel height and a high ratio of dynamic pressure to pressure drop. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in channels. Flow nonuniformity from channel-to-channel was as high as 12 pct above and 19 pct below the mean flow.

  9. DEVELOPMENT OF A LOW HEAT LEAK CFRP STAND FOR MIRI COOLER JT HEAT EXCHANGER STAGE

    SciTech Connect

    Makowski, K. P.; Hayashil, B. [Alliance Spacesystems, LLC, Pasadena, CA 91103 (United States); Larson, M. E.; Loc, A. S.; Zhang, B. X.; Leland, R. S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2010-04-09

    A low heat leak stand is being developed for the Heat exchanger Stage Assembly (HSA) of the cryocooler subsystem for the Mid Infra-Red Instrument (MIRI) of the James Webb Space Telescope (JWST). The HSA stand is a hexapod structure supporting the 18 K HSA in a nominal 40 K background environment. Carbon fiber reinforced plastic (CFRP) has been selected for this application to meet the stringent design requirements of a low parasitic heat leak (less than 3.8 mW including both conductive and radiative heat loads for the thermal environment defined above) and a resonance frequency above 120 Hz. A directional lay-up of T300/polycyanate has been chosen for the construction of the hexapod struts. End fittings made of Invar 36 are bonded to the struts to provide structural interfaces. The development effort includes fabricating and testing (including cryogenic thermal cycling) six types of coupons for material characterization, determination of structural degradation due to thermal cycling, and selection of the joint bonding epoxy. Consequently, strut samples are used for final material characterization, performance assessment, and bond joint design evaluation. This paper describes the development process and addresses the challenges in meeting the design requirements. Results of finite element analysis (FEA) for the composite structure and experimental data collected through structural and thermal testing are also presented.

  10. A short time step response factor model for vertical ground loop heat exchangers

    SciTech Connect

    Yavuzturk, C.; Spitler, J.D.

    1999-07-01

    The short-term behavior of ground-coupled heat pump systems is important for design of ground loop heat exchangers, energy analysis of ground source heat pump systems, and design of hybrid ground source systems. This paper describes the development of short time-step temperature response factors for vertical ground loop heat exchangers as used in ground-coupled heat pump systems. The short time-step response factors allow for a direct evaluation of system energy consumption and electrical demand in hourly or shorter time intervals. The development of the temperature response factors is based on an analytically validated, transient two-dimensional implicit finite volume model designed for the simulation of heat transfer over a vertical U-tube ground heat exchanger. The short time-step response factors are implemented as part of a component model for TRNSYS and an example application is provided based on an actual building.

  11. An Experimentally Validated Numerical Modeling Technique for Perforated Plate Heat Exchangers

    PubMed Central

    Nellis, G. F.; Kelin, S. A.; Zhu, W.; Gianchandani, Y.

    2010-01-01

    Cryogenic and high-temperature systems often require compact heat exchangers with a high resistance to axial conduction in order to control the heat transfer induced by axial temperature differences. One attractive design for such applications is a perforated plate heat exchanger that utilizes high conductivity perforated plates to provide the stream-to-stream heat transfer and low conductivity spacers to prevent axial conduction between the perforated plates. This paper presents a numerical model of a perforated plate heat exchanger that accounts for axial conduction, external parasitic heat loads, variable fluid and material properties, and conduction to and from the ends of the heat exchanger. The numerical model is validated by experimentally testing several perforated plate heat exchangers that are fabricated using microelectromechanical systems based manufacturing methods. This type of heat exchanger was investigated for potential use in a cryosurgical probe. One of these heat exchangers included perforated plates with integrated platinum resistance thermometers. These plates provided in situ measurements of the internal temperature distribution in addition to the temperature, pressure, and flow rate measured at the inlet and exit ports of the device. The platinum wires were deposited between the fluid passages on the perforated plate and are used to measure the temperature at the interface between the wall material and the flowing fluid. The experimental testing demonstrates the ability of the numerical model to accurately predict both the overall performance and the internal temperature distribution of perforated plate heat exchangers over a range of geometry and operating conditions. The parameters that were varied include the axial length, temperature range, mass flow rate, and working fluid. PMID:20976021

  12. A study of flow patterns in a thermosyphon for compact heat exchanger applications

    Microsoft Academic Search

    M. H. M. Grooten; Geld van der CWM; Deursen van LGM

    2008-01-01

    Recently, thermosyphons have attracted interest in the design of smaller, lighter and cheaper heat exchangers, be- cause of their compactness, low thermal resistance, high heat recovery effectiveness, safety and reliability. In order to un- derstand the effects of the angle of inclination on heat trans- fer characteristics of a thermosyphon, a dedicated flow visu- alization study of flow patterns in

  13. The optimum fin spacing of circular tube bank fin heat exchanger with vortex generators

    NASA Astrophysics Data System (ADS)

    Hu, Wanling; Su, Mei; Wang, Liangcheng; Zhang, Qiang; Chang, Limin; Liu, Song; Wang, Liangbi

    2013-09-01

    In real application, once the pattern of fin is determined, fin spacing of tube bank fin heat exchanger can be adjusted in a small region, and air flow velocity in the front of the heat exchanger is not all the same. Therefore, the effects of fin spacing on heat transfer performance of such heat exchanger are needed. This paper numerically studied the optimal fin spacing regarding the different front flow velocities of a circular tube bank fin heat exchanger with vortex generators. To screen the optimal fin spacing, an appropriate evaluation criterion JF was used. The results show that when front velocity is 1.75 m/s, the optimal fin spacing is 2.25 mm, when front velocity is 2.5 m/s, the optimal fin spacing is 2 mm, and when front velocity is higher than 2.5 m/s, the optimal fin spacing is 1.75 mm.

  14. Experimental studies on pressure drop characteristics of cryogenic cross-counter flow coiled finned tube heat exchangers

    Microsoft Academic Search

    Prabhat Kumar Gupta; P. K. Kush; Ashesh Tiwari

    2010-01-01

    Cross-counter flow coiled finned tube heat exchangers used in medium capacity helium liquefiers\\/refrigerators were developed in our lab. These heat exchangers were developed using integrated low finned tubes. Experimental studies have been performed to know the pressure drop characteristics of tube side and shell side flow of these heat exchangers. All experiments were performed at room temperature in the Reynolds

  15. Modeling of radiative heat transfer and mass transfer processes in drop-flow-based heat exchangers for spacecraft

    Microsoft Academic Search

    G. V. Konyukhov; A. A. Koroteev; V. V. Novomlinskii; B. N. Baushev

    1998-01-01

    Modeling of radiative heat transfer and mass transfer in drop-flow-based heat exchangers for spacecraft is considered. A Monte\\u000a Carlo-based numerical model is presented. Results obtained with the aid of the model are analyzed and compared with existing\\u000a data.

  16. Prototype solar heated hot water systems and double-walled heat exchangers: A collection of quarterly reports

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The plan schedule and status of multiple objectives to be achieved in the development, manufacture, installation, and maintenance of two solar heated hot water prototype systems and two heat exchangers are reported. A computer program developed to resolve problems and evaluate system performance is described.

  17. Design Method for the Heating/Cooling Coil in the AHU Based on Fuzzy Logic - Part Two: Design of the Minimum Heat-Exchanging Unit

    E-print Network

    Zhang, J.; Chen, Y.; Liang, Z.

    2006-01-01

    Considering a heating/cooling coil with adjustable heat-exchange area, an unequal type is put forward in this paper. Aiming at the application of such heat exchanger in an air-handling unit, restriction conditions are given for the minimum heat...

  18. Process industry demand for more efficient, more cost-effective heat exchanger tubing

    SciTech Connect

    Thors, P.

    1987-01-01

    In the future the process industry will see a bigger selection of enhanced heat transfer tubes, one of the reasons being the continued production of special patented technology involved in making them. Here the author mentions only some of the factors that might influence the increased usage of these enhanced tubes. In using more efficient tubing in a heat exchanger the designer has available the options to increase the total heat duty per unit volume, lower operating costs by reducing the mean temperature difference at a given heat duty, save material, or reduce the size and/or pumping power, among others. This can be achieved, for example, by replacing plain tubes with appropriate enhanced tubes in retubing applications, where old heat exchangers need to be upgraded and total efficiency improved. When a new heat exchanger is to be built, it is easier for the designer to include the more efficient tubing to utilize all the benefits of the increased thermal performance.

  19. Wet surface heat transfer and pressure drop of aluminum parallel flow heat exchangers at different inclination angles

    Microsoft Academic Search

    Nae-Hyun Kim; Do-Young Kim; Jun-Hyun Hwang

    2008-01-01

    The effect of inclination angle on the heat transfer and pressure drop characteristics of brazed aluminum heat exchangers\\u000a was experimentally investigated under wet conditions. Three samples having different fin pitches (1.25, 1.5 and 2.0 mm) were\\u000a tested. Results show that heat transfer coefficients are not affected by the inclination angle. However, friction factors\\u000a increase as the inclination angle increases with

  20. Heat transfer enhancement accompanying pressure-loss reduction with winglet-type vortex generators for fin-tube heat exchangers

    Microsoft Academic Search

    K. Torii; K. M. Kwak; K. Nishino

    2002-01-01

    This paper proposes a novel technique that can augment heat transfer but nevertheless can reduce pressure-loss in a fin-tube heat exchanger with circular tubes in a relatively low Reynolds number flow, by deploying delta winglet-type vortex generators. The winglets are placed with a heretofore-unused orientation for the purpose of augmentation of heat transfer. This orientation is called as “common flow