Science.gov

Sample records for line heat exchanger

  1. In - line determination of heat transfer coefficients in a plate heat exchanger

    NASA Astrophysics Data System (ADS)

    Sotelo, S. Silva; Domínguez, R. J. Romero

    This paper shows an in - line determination of heat transfer coefficients in a plate heat exchanger. Water and aqueous working solution of lithium bromide + ethylene glycol are considered. Heat transfer coefficients are calculated for both fluids. "Type T" thermocouples were used for monitoring the wall temperature in a plate heat exchanger, which is one of the main components in an absorption system. Commercial software Agilent HP Vee Pro 7.5 was used for monitoring the temperatures and for the determination of the heat transfer coefficients. There are not previous works for heat transfer coefficients for the working solution used in this work.

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

    NASA Technical Reports Server (NTRS)

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

    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.

  3. 120. COOLANT LINES TO SIS HEAT EXCHANGER No.1 IN AUXILIARY ...

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

    120. COOLANT LINES TO SIS HEAT EXCHANGER No.1 IN AUXILIARY CHAMBER, NOVEMBER 1, 1976 - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  4. Heat exchanger

    DOEpatents

    Daman, Ernest L.; McCallister, Robert A.

    1979-01-01

    A heat exchanger is provided having first and second fluid chambers for passing primary and secondary fluids. The chambers are spaced apart and have heat pipes extending from inside one chamber to inside the other chamber. A third chamber is provided for passing a purge fluid, and the heat pipe portion between the first and second chambers lies within the third chamber.

  5. HEAT EXCHANGER

    DOEpatents

    Fox, T.H. III; Richey, T. Jr.; Winders, G.R.

    1962-10-23

    A heat exchanger is designed for use in the transfer of heat between a radioactive fiuid and a non-radioactive fiuid. The exchanger employs a removable section containing the non-hazardous fluid extending into the section designed to contain the radioactive fluid. The removable section is provided with a construction to cancel out thermal stresses. The stationary section is pressurized to prevent leakage of the radioactive fiuid and to maintain a safe, desirable level for this fiuid. (AEC)

  6. Heat exchanger

    DOEpatents

    Wolowodiuk, Walter

    1976-01-06

    A heat exchanger of the straight tube type in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration.

  7. Corrosive resistant heat exchanger

    DOEpatents

    Richlen, Scott L.

    1989-01-01

    A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

  8. Heat exchanger

    DOEpatents

    Brackenbury, Phillip J.

    1986-04-01

    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.

  9. Segmented heat exchanger

    DOEpatents

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  10. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C.

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  11. Handbook on heat exchangers

    NASA Astrophysics Data System (ADS)

    Bazhan, Pavel I.; Kanevets, Georgii E.; Seliverstov, Vladimir M.

    Essential data on heat exchange equipment used in ship, locomotive, automotive, and aircraft powerplants are presented in a systematic manner. The data cover the principal types and technical and performance characteristics of heat exchangers, fundamentals of the theory of heat exchange, calculation of heat transfer coefficients for different types of heat exchange apparatus, optimization of heat exchangers, computer-aided design of heat exchange equipment, testing techniques, and test result processing.

  12. Woven heat exchanger

    DOEpatents

    Piscitella, R.R.

    1984-07-16

    This invention relates to a heat exchanger for waste heat recovery from high temperature industrial exhaust streams. In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  13. Woven heat exchanger

    DOEpatents

    Piscitella, Roger R.

    1987-01-01

    In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  14. Woven heat exchanger

    DOEpatents

    Piscitella, Roger R.

    1987-05-05

    In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  15. Industrial heat exchangers

    SciTech Connect

    Hayes, A.J.; Liang, W.W.; Richlen, S.L.; Tabb, E.S.

    1985-01-01

    This book presents the papers given at a symposium on the use of heat exchangers in the industrial plants. Topics considered include the US DOE and GRI research programs, advanced fixed boundary heat exchanger technology, commercial heat exchanger applications, thermo-hydraulic performance of heat-transfer equipment, field tests, the corrosion of heat exchanger materials, economics, cost benefit analysis, payback, and advanced assembly and materials.

  16. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... section. (1) All heat exchangers that are in organic HAP service within the heat exchange system that...., the heat exchange system does not contain any heat exchangers that are in organic HAP service as... exchange system in organic HAP service or from each heat exchanger exit line for each heat exchanger...

  17. Direct fired heat exchanger

    DOEpatents

    Reimann, Robert C.; Root, Richard A.

    1986-01-01

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

  18. Wound tube heat exchanger

    DOEpatents

    Ecker, Amir L.

    1983-01-01

    What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

  19. Laser Processed Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Hansen, Scott

    2017-01-01

    The Laser Processed Heat Exchanger project will investigate the use of laser processed surfaces to reduce mass and volume in liquid/liquid heat exchangers as well as the replacement of the harmful and problematic coatings of the Condensing Heat Exchangers (CHX). For this project, two scale unit test articles will be designed, manufactured, and tested. These two units are a high efficiency liquid/liquid HX and a high reliability CHX.

  20. 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.

  1. Compact, super heat exchanger

    NASA Technical Reports Server (NTRS)

    Fortini, A.; Kazaroff, J. M.

    1980-01-01

    Heat exchanger uses porous media to enhance heat transfer through walls of cooling channels, thereby lowering wall temperature. Porous media within cooling channel increases internal surface area from which heat can be transferred to coolant. Comparison data shows wall has lower temperature and coolant has higher temperature when porous medium is used within heat exchanger. Media can be sintered powedered metal, metal fibers, woven wire layers, or any porous metal having desired permeability and porosity.

  2. Compact, super heat exchanger

    NASA Technical Reports Server (NTRS)

    Fortini, A.; Kazaroff, J. M.

    1980-01-01

    Heat exchanger uses porous media to enhance heat transfer through walls of cooling channels, thereby lowering wall temperature. Porous media within cooling channel increases internal surface area from which heat can be transferred to coolant. Comparison data shows wall has lower temperature and coolant has higher temperature when porous medium is used within heat exchanger. Media can be sintered powedered metal, metal fibers, woven wire layers, or any porous metal having desired permeability and porosity.

  3. 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)

  4. 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)

  5. Active microchannel heat exchanger

    DOEpatents

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

  6. Microscale Regenerative Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

    2006-01-01

    The device described herein is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a "regenerator" in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle.

  7. Heat and mass exchanger

    DOEpatents

    Lowenstein, Andrew [Princeton, NJ; Sibilia, Marc J [Princeton, NJ; Miller, Jeffrey A [Hopewell, NJ; Tonon, Thomas [Princeton, NJ

    2011-06-28

    A mass and heat exchanger includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding gas; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat exchange fluid therethrough, wherein heat transfer occurs between the liquid and the heat exchange fluid.

  8. Thermoelectric heat exchange element

    DOEpatents

    Callas, James J.; Taher, Mahmoud A.

    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.

  9. Modular Heat Exchanger With Integral Heat Pipe

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    1992-01-01

    Modular heat exchanger with integral heat pipe transports heat from source to Stirling engine. Alternative to heat exchangers depending on integrities of thousands of brazed joints, contains only 40 brazed tubes.

  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. A corrosive resistant heat exchanger

    DOEpatents

    Richlen, S.L.

    1987-08-10

    A corrosive and erosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is pumped through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium. 3 figs., 3 tabs.

  12. Greywater heat exchanger

    SciTech Connect

    Holmberg, D.

    1983-11-21

    A kilowatt meter and water meter were installed to monitor pregreywater usage. The design considerations, the heat exchanger construction and installation, and the monitoring of usage levels are described.

  13. 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.

  14. 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)

  15. Radial flow heat exchanger

    DOEpatents

    Valenzuela, Javier

    2001-01-01

    A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

  16. Counterflow Regolith Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Zubrin, Robert; Jonscher, Peter

    2013-01-01

    A problem exists in reducing the total heating power required to extract oxygen from lunar regolith. All such processes require heating a great deal of soil, and the heat energy is wasted if it cannot be recycled from processed material back into new material. The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat exchanger with internal and external augers attached to the inner rotating tube to move the regolith. Hot regolith in the outer tube is moved in one direction by a right-hand - ed auger, and the cool regolith in the inner tube is moved in the opposite direction by a left-handed auger attached to the inside of the rotating tube. In this counterflow arrangement, a large fraction of the heat from the expended regolith is transferred to the new regolith. The spent regolith leaves the heat exchanger close to the temperature of the cold new regolith, and the new regolith is pre-heated close to the initial temperature of the spent regolith. Using the CoRHE can reduce the heating requirement of a lunar ISRU system by 80%, reducing the total power consumption by a factor of two. The unique feature of this system is that it allows for counterflow heat exchange to occur between solids, instead of liquids or gases, as is commonly done. In addition, in variants of this concept, the hydrogen reduction can be made to occur within the counterflow heat exchanger itself, enabling a simplified lunar ISRU (in situ resource utilization) system with excellent energy economy and continuous nonbatch mode operation.

  17. 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).

  18. Microtube strip heat exchanger

    SciTech Connect

    Doty, F.D.

    1992-07-09

    The purpose of this contract has been to explore the limits of miniaturization of heat exchangers with the goals of (1) improving the theoretical understanding of laminar heat exchangers, (2) evaluating various manufacturing difficulties, and (3) identifying major applications for the technology. A low-cost, ultra-compact heat exchanger could have an enormous impact on industry in the areas of cryocoolers and energy conversion. Compact cryocoolers based on the reverse Brayton cycle (RBC) would become practical with the availability of compact heat exchangers. Many experts believe that hardware advances in personal computer technology will rapidly slow down in four to six years unless lowcost, portable cryocoolers suitable for the desktop supercomputer can be developed. Compact refrigeration systems would permit dramatic advances in high-performance computer work stations with conventional'' microprocessors operating at 150 K, and especially with low-cost cryocoolers below 77 K. NASA has also expressed strong interest in our MTS exchanger for space-based RBC cryocoolers for sensor cooling. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

  19. Heat exchanger restart evaluation

    SciTech Connect

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-03-18

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4A was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the identified tube. The leaking tube was removed and examined metallurgically to determine the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summarized.

  20. Heat exchanger restart evaluation

    SciTech Connect

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-02-28

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4kA was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summarized herein.

  1. Heat exchanger restart evaluation

    SciTech Connect

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-03-18

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4A was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the identified tube. The leaking tube was removed and examined metallurgically to determine the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summary herein.

  2. Scraped surface heat exchangers.

    PubMed

    Rao, Chetan S; Hartel, Richard W

    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 food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs.

  3. 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.

  4. Microgravity condensing heat exchanger

    NASA Technical Reports Server (NTRS)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor); North, Andrew (Inventor); Weislogel, Mark M. (Inventor)

    2011-01-01

    A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

  5. Heat exchanger panel

    NASA Technical Reports Server (NTRS)

    Warburton, Robert E. (Inventor); Cuva, William J. (Inventor)

    2005-01-01

    The present invention relates to a heat exchanger panel which has broad utility in high temperature environments. The heat exchanger panel has a first panel, a second panel, and at least one fluid containment device positioned intermediate the first and second panels. At least one of the first panel and the second panel have at least one feature on an interior surface to accommodate the at least one fluid containment device. In a preferred embodiment, each of the first and second panels is formed from a high conductivity, high temperature composite material. Also, in a preferred embodiment, the first and second panels are joined together by one or more composite fasteners.

  6. Microtube strip heat exchanger

    SciTech Connect

    Doty, F.D.

    1991-10-16

    This progress report is for the September--October 1991 quarter. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

  7. Conquer heat exchanger fouling

    SciTech Connect

    Mukherjee, R.

    1996-01-01

    Fouling plays a dominant role in heat exchanger performance. It is extremely important to choose the most appropriate type of heat exchanger for a particular application and adopt proper values for fouling resistance. A design practice for shell-and-tube heat exchangers that will limit fouling to a minimum and thus ensure trouble-free operation is essential. Due to the availability of specialized software, the thermal design of heat exchangers has become precise and scientific. The results occasionally have to be tempered with practical experience and engineering judgment, but generally these computer programs are very reliable and authentic. However, the above is true only for determining heat-transfer coefficients and pressure drop. One important area that cannot possibly be addressed by design software is fouling. While a proper selection of fouling resistance is extremely difficult due to the numerous factors involved, a sound design practice will minimize any errors. However, it is important to first understand the phenomenon of fouling. The paper describes what fouling is, types of fouling, factors affecting fouling, providing a fouling allowance, selecting a fouling resistance, and overcoming fouling through better design.

  8. Heat exchange apparatus

    DOEpatents

    Degtiarenko, Pavel V.

    2003-08-12

    A heat exchange apparatus comprising a coolant conduit or heat sink having attached to its surface a first radial array of spaced-apart parallel plate fins or needles and a second radial array of spaced-apart parallel plate fins or needles thermally coupled to a body to be cooled and meshed with, but not contacting the first radial array of spaced-apart parallel plate fins or needles.

  9. Microtube strip heat exchanger

    NASA Astrophysics Data System (ADS)

    Doty, F. D.

    1991-04-01

    During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchangers. The team has begun a heat exchanger stress analysis; however, they have been concentrating the bulk of their analytical energies on a computational fluid dynmaics (CFD) model to determine the location and magnitude of shell-side flow maldistribution which decreases heat exchanger effectiveness. DSI received 120 fineblanked tubestrips from Southern Fineblanking (SFB) for manufacturing process development. Both SFB and NIST provided inspection reports of the tubestrips. DSI completed the tooling required to encapsulate a tube array and press tubestrips on the array. Pressing the tubestrips on tube arrays showed design deficiencies both in the tubestrip design and the tooling design. DSI has a number of revisions in process to correct these deficiencies. The research effort has identified a more economical fusible alloy for encapsulating the tube array, and determined the parameters required to successfully encapsulate the tube array with the new alloy. A more compact MTS heat exchanger bank was designed.

  10. LIGHTWEIGHT METAL FOIL HEAT EXCHANGERS,

    DTIC Science & Technology

    HEAT EXCHANGERS, FOILS(MATERIALS), AEROSPACE CRAFT, HYDROGEN, TEST METHODS, STRUCTURES, HEAT TRANSFER, NIOBIUM, FLUID FLOW, FRICTION, ALUMINUM ALLOYS, NICKEL ALLOYS, ALUMINUM , TITANIUM ALLOYS, RAMJET ENGINES.

  11. Heat exchanger-accumulator

    DOEpatents

    Ecker, Amir L.

    1980-01-01

    What is disclosed is a heat exchanger-accumulator for vaporizing a refrigerant or the like, characterized by an upright pressure vessel having a top, bottom and side walls; an inlet conduit eccentrically and sealingly penetrating through the top; a tubular overflow chamber disposed within the vessel and sealingly connected with the bottom so as to define an annular outer volumetric chamber for receiving refrigerant; a heat transfer coil disposed in the outer volumetric chamber for vaporizing the liquid refrigerant that accumulates there; the heat transfer coil defining a passageway for circulating an externally supplied heat exchange fluid; transferring heat efficiently from the fluid; and freely allowing vaporized refrigerant to escape upwardly from the liquid refrigerant; and a refrigerant discharge conduit penetrating sealingly through the top and traversing substantially the length of the pressurized vessel downwardly and upwardly such that its inlet is near the top of the pressurized vessel so as to provide a means for transporting refrigerant vapor from the vessel. The refrigerant discharge conduit has metering orifices, or passageways, penetrating laterally through its walls near the bottom, communicating respectively interiorly and exteriorly of the overflow chamber for controllably carrying small amounts of liquid refrigerant and oil to the effluent stream of refrigerant gas.

  12. Heat-Exchanger/Heat-Pipe Interface

    NASA Technical Reports Server (NTRS)

    Snyder, H. J.; Van Hagan, T. H.

    1987-01-01

    Monolithic assembly reliable and light in weight. Heat exchanger and evaporator ends of heat pipes integrated in monolithic halves welded together. Interface assembly connects heat exchanger of furnace, reactor, or other power source with heat pipes carrying heat to radiator or power-consuming system. One of several concepts proposed for nuclear power supplies aboard spacecraft, interface useful on Earth in solar thermal power systems, heat engines, and lightweight cooling systems.

  13. Heat exchanger tube mounts

    DOEpatents

    Wolowodiuk, W.; Anelli, J.; Dawson, B.E.

    1974-01-01

    A heat exchanger in which tubes are secured to a tube sheet by internal bore welding is described. The tubes may be moved into place in preparation for welding with comparatively little trouble. A number of segmented tube support plates are provided which allow a considerable portion of each of the tubes to be moved laterally after the end thereof has been positioned in preparation for internal bore welding to the tube sheet. (auth)

  14. High flux heat exchanger

    NASA Astrophysics Data System (ADS)

    Flynn, Edward M.; Mackowski, Michael J.

    1993-01-01

    This interim report documents the results of the first two phases of a four-phase program to develop a high flux heat exchanger for cooling future high performance aircraft electronics. Phase 1 defines future needs for high flux heat removal in advanced military electronics systems. The results are sorted by broad application categories: (1) commercial digital systems, (2) military data processors, (3) power processors, and (4) radar and optical systems. For applications expected to be fielded in five to ten years, the outlook is for steady state flux levels of 30-50 W/sq cm for digital processors and several hundred W/sq cm for power control applications. In Phase 1, a trade study was conducted on emerging cooling technologies which could remove a steady state chip heat flux of 100 W/sq cm while holding chip junction temperature to 90 C. Constraints imposed on heat exchanger design, in order to reflect operation in a fighter aircraft environment, included a practical lower limit on coolant supply temperature, the preference for a nontoxic, nonflammable, and nonfreezing coolant, the need to minimize weight and volume, and operation in an accelerating environment. The trade study recommended the Compact High Intensity Cooler (CHIC) for design, fabrication, and test in the final two phases of this program.

  15. 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.

  16. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  17. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  18. Triple loop heat exchanger for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    A triple loop heat exchanger for an absorption refrigeration system is disclosed. The triple loop heat exchanger comprises portions of a strong solution line for conducting relatively hot, strong solution from a generator to a solution heat exchanger of the absorption refrigeration system, conduit means for conducting relatively cool, weak solution from the solution heat exchanger to the generator, and a bypass system for conducting strong solution from the generator around the strong solution line and around the solution heat exchanger to an absorber of the refrigeration system when strong solution builds up in the generator to an undesirable level. The strong solution line and the conduit means are in heat exchange relationship with each other in the triple loop heat exchanger so that, during normal operation of the refrigeration system, heat is exchanged between the relatively hot, strong solution flowing through the strong solution line and the relatively cool, weak solution flowing through the conduit means. Also, the strong solution line and the bypass system are in heat exchange relationship in the triple loop heat exchanger so that if the normal flow path of relatively hot, strong solution flowing from the generator to an absorber is blocked, then this relatively, hot strong solution which will then be flowing through the bypass system in the triple loop heat exchanger, is brought into heat exchange relationship with any strong solution which may have solidified in the strong solution line in the triple loop heat exchanger to thereby aid in desolidifying any such solidified strong solution.

  19. Fault-Tolerant Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  20. "Bottle-Brush" Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Tward, E.; Gatewood, J. R.

    1982-01-01

    Heat exchanger consists of a metal tube with wires extending inward from wall. Conduction of heat along wires improves heat transfer to gas or other filling. Fluid is heated throughout the cross section of tube. Suggested applications are refrigerators, heat engines, thermal instrumentation, and heat switches.

  1. Characteristics of model heat exchanger

    NASA Astrophysics Data System (ADS)

    Kolínský, Jan

    2017-09-01

    The aim of this paper is thermal analysis of model water to water heat exchanger at different mass flow rates. Experimental study deals with determination of total heat transfer - power of the heat exchanger. Furthermore the paper deals with analysis of heat exchanger charakcteristic using a definition of thermal efficiency. It is demonstrated that it is advisable to monitor the dependence of thermal efficiency and flow ratio.

  2. Hybrid Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Tu, Jianping Gene; Shih, Wei

    2010-01-01

    A hybrid light-weight heat exchanger concept has been developed that uses high-conductivity carbon-carbon (C-C) composites as the heat-transfer fins and uses conventional high-temperature metals, such as Inconel, nickel, and titanium as the parting sheets to meet leakage and structural requirements. In order to maximize thermal conductivity, the majority of carbon fiber is aligned in the fin direction resulting in 300 W/m.K or higher conductivity in the fin directions. As a result of this fiber orientation, the coefficient of thermal expansion (CTE) of the C-C composite in both non-fiber directions matches well with the CTE of various high-temperature metal alloys. This allows the joining of fins and parting sheets by using high-temperature braze alloys.

  3. Heat exchanger for electrothermal devices

    NASA Technical Reports Server (NTRS)

    Zavesky, Ralph J. (Inventor); Sovey, James S. (Inventor); Mirtich, Michael J. (Inventor); Marinos, Charalampus (Inventor); Penko, Paul F. (Inventor)

    1986-01-01

    An improved electrothermal device is disclosed. An electrothermal thruster utilizes a generally cylindrical heat exchanger chamber to convert electricity to heat which raises the propellant temperature. A textured, high emissivity heat element radiatively transfers heat to the inner wall of this chamber that is ion beam morphologically controlled for high absorptivity. This, in turn, raises the temperature of a porous heat exchanger material in an annular chamber surrounding the cylindrical chamber. Propellant gas flows through the annular chamber and is heated by the heat exchanger material.

  4. Heat exchange assembly

    DOEpatents

    Lowenstein, Andrew; Sibilia, Marc; Miller, Jeffrey; Tonon, Thomas S.

    2004-06-08

    A heat exchange assembly comprises a plurality of plates disposed in a spaced-apart arrangement, each of the plurality of plates includes a plurality of passages extending internally from a first end to a second end for directing flow of a heat transfer fluid in a first plane, a plurality of first end-piece members equaling the number of plates and a plurality of second end-piece members also equaling the number of plates, each of the first and second end-piece members including a recessed region adapted to fluidly connect and couple with the first and second ends of the plate, respectively, and further adapted to be affixed to respective adjacent first and second end-piece members in a stacked formation, and each of the first and second end-piece members further including at least one cavity for enabling entry of the heat transfer fluid into the plate, exit of the heat transfer fluid from the plate, or 180.degree. turning of the fluid within the plate to create a serpentine-like fluid flow path between points of entry and exit of the fluid, and at least two fluid conduits extending through the stacked plurality of first and second end-piece members for providing first fluid connections between the parallel fluid entry points of adjacent plates and a fluid supply inlet, and second fluid connections between the parallel fluid exit points of adjacent plates and a fluid discharge outlet so that the heat transfer fluid travels in parallel paths through each respective plate.

  5. 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

  6. The microtube strip heat exchanger

    SciTech Connect

    Doty, F.D.; Hosford, G.; Spitzmesser, J.B. ); Jones, J.D. . School of Engineering Science)

    1991-01-01

    The advantages of designing heat exchangers in the laminar-flow regime are discussed from a theoretical standpoint. It is argued that laminar-flow designs have the advantages of reducing thermodynamic and hydrodynamic irreversibilities, and hence increasing system efficiency. More concretely, laminar-flow heat exchangers are free from the turbulence-induced vibration common in conventional heat exchangers, and can thus offer longer life and greater reliability. The problems of manufacturing heat exchangers suited to laminar flow are discussed. A method of manufacture is outlined that allows compact, modular design. Experience with this method of manufacture is described. Experimental results with a prototype heat exchanger bank are presented: these results show good agreement with theory at moderate levels of effectiveness (75--85%), but fall below predicted values at higher levels. It is argued that this discrepancy results from flow maldistribution. The problem of fouling and flow maldistribution are briefly discussed, and some possible applications are mentioned.

  7. Aluminum heat exchanger

    SciTech Connect

    Koisuka, M.; Aoki, H.

    1986-11-04

    This patent describes a heat exchanger comprising a flat metal tube for conducting fluid having opposite first and second ends, of metal fins fixed onto outer surfaces of the flat metal tube, first and second header pipes fixedly mounted on the opposite ends of the flat metal tube, respectively, so that the flat metal tube communicates with the interior of the header pipes. Each of the header pipes has a first end that is open and a second end that is closed. An inlet tube is connected to the first end of the first header pipe, and an outlet tube is connected to the first end of the second header pipe. The improvement described here comprises one of the inlet and outlet tubes having an end portion inserted into the first end of the corresponding interconnected header pipe. The end portion has a cut-away portion in the form of a first axial slit extending axially inwardly from an open end at the adjacent end of the one tube. The first axial slit has an axial intermediate portion slightly smaller than the thickness of the flat metal tube, and a tapered portion diverging towards the open end of the first axial slit, and the first end of the flat metal tube extends into the corresponding interconnected header pipe and is closely fitted into the first axial slit.

  8. Modular heat exchanger

    DOEpatents

    Giardina, Angelo R. [Marple Township, Delaware County, PA

    1981-03-03

    A shell and tube heat exchanger having a plurality of individually removable tube bundle modules. A lattice of structural steel forming rectangular openings therein is placed at each end of a cylindrical shell. Longitudinal structural members are placed in the shell between corners of the rectangular openings situated on opposite ends of the shell. Intermediate support members interconnect the longitudinal supports so as to increase the longitudinal supports rigidity. Rectangular parallelpiped tube bundle moldules occupy the space defined by the longitudinal supports and end supports and each include a rectangular tube sheet situated on each end of a plurality of tubes extending therethrough, a plurality of rectangular tube supports located between the tube sheets, and a tube bundle module stiffening structure disposed about the bundle's periphery and being attached to the tube sheets and tube supports. The corners of each tube bundle module have longitudinal framework members which are mateable with and supported by the longitudinal support members. Intermediate support members constitute several lattice, each of which is situate d in a plane between the end support members. The intermediate support members constituting the several lattice extend horizontally and vertically between longitudinal supports of adjacent tube module voids. An alternative embodiment for intermediate support members constitute a series of structural plates situated at the corners of the module voids and having recesses therein for receiving the respective longitudinal support members adjacent thereto, protrusions separating the recesses, and a plurality of struts situated between protrusions of adjacent structural plates.

  9. Modular heat exchanger

    DOEpatents

    Giardina, A.R.

    1981-03-03

    A shell and tube heat exchanger is described having a plurality of individually removable tube bundle modules. A lattice of structural steel forming rectangular openings therein is placed at each end of a cylindrical shell. Longitudinal structural members are placed in the shell between corners of the rectangular openings situated on opposite ends of the shell. Intermediate support members interconnect the longitudinal supports so as to increase the longitudinal supports rigidity. Rectangular parallelepiped tube bundle modules occupy the space defined by the longitudinal supports and end supports and each include a rectangular tube sheet situated on each end of a plurality of tubes extending there through, a plurality of rectangular tube supports located between the tube sheets, and a tube bundle module stiffening structure disposed about the bundle's periphery and being attached to the tube sheets and tube supports. The corners of each tube bundle module have longitudinal framework members which are mateable with and supported by the longitudinal support members. Intermediate support members constitute several lattices, each of which is situated in a plane between the end support members. The intermediate support members constituting the several lattices extend horizontally and vertically between longitudinal supports of adjacent tube module voids. An alternative embodiment for intermediate support members constitute a series of structural plates situated at the corners of the module voids and having recesses therein for receiving the respective longitudinal support members adjacent thereto, protrusions separating the recesses, and a plurality of struts situated between protrusions of adjacent structural plates. 12 figs.

  10. Bayonet heat exchangers in heat-assisted Stirling heat pump

    SciTech Connect

    Yagyu, S.; Fukuyama, Y.; Morikawa, T.; Isshiki, N.; Satoh, I.; Corey, J.; Fellows, C.

    1998-07-01

    The Multi-Temperature Heat Supply System is a research project creating a city energy system with lower environmental load. This system consists of a gas-fueled internal combustion engine and a heat-assisted Stirling heat pump utilizing shaft power and thermal power in a combination of several cylinders. The heat pump is mainly driven by engine shaft power and is partially assisted by thermal power from engine exhaust heat source. Since this heat pump is operated by proportioning the two energy sources to match the characteristics of the driving engine, the system is expected to produce cooling and heating water at high COP. This paper describes heat exchanger development in the project to develop a heat-assisted Stirling heat pump. The heat pump employs the Bayonet type heat exchangers (BHX Type I) for supplying cold and hot water and (BHX Type II) for absorbing exhaust heat from the driving engine. The heat exchanger design concepts are presented and their heat transfer and flow loss characteristics in oscillating gas flow are investigated. The main concern in the BHX Type I is an improvement of gas side heat transfer and the spirally finned tubes were applied to gas side of the heat exchanger. For the BHX Type II, internal heat transfer characteristics are the main concern. Shell-and-tube type heat exchangers are widely used in Stirling machines. However, since brazing is applied to the many tubes for their manufacturing processes, it is very difficult to change flow passages to optimize heat transfer and loss characteristics once they have been made. The challenge was to enhance heat transfer on the gas side to make a highly efficient heat exchanger with fewer parts. It is shown that the Bayonet type heat exchanger can have good performance comparable to conventional heat exchangers.

  11. Heat exchanger using graphite foam

    DOEpatents

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

    A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

  12. The liquid droplet heat exchanger

    NASA Astrophysics Data System (ADS)

    Bruckner, A. P.

    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 many of the material limitations of conventional tube type heat exchangers and does away with complicated plumbing systems and their tendency toward simple point failure. Droplet heat exchangers offer large surface to volume ratios in a compact geometry, very low pressure drop and high effectiveness. In the simplest configuration the molten material is sprayed axially through a counterflowing, high pressure inert working gas in an insulated cylindrical chamber. The droplets transfer heat directly to the gas by convection as they traverse the heat exchanger and are subsequently collected for recycling through the heat source. A number of suitable liquid metals and eutectic alloys having negligibly low vapor pressures in the temperature range of 350-1300 K were identified. Experimental studies of droplet formation with mercury demonstrated that near perfect control of droplet size can be easily achieved.

  13. Phase Change Material Heat Exchangers

    NASA Image and Video Library

    NASA’s Game Changing Development is taking on a technologydevelopment and demonstration effort to design, build, and test the next generation of Phase Change Material Heat Exchangers (PCM HXs) on ...

  14. Numerical simulation of heat exchanger

    SciTech Connect

    Sha, W.T.

    1985-01-01

    Accurate and detailed knowledge of the fluid flow field and thermal distribution inside a heat exchanger becomes invaluable as a large, efficient, and reliable unit is sought. This information is needed to provide proper evaluation of the thermal and structural performance characteristics of a heat exchanger. It is to be noted that an analytical prediction method, when properly validated, will greatly reduce the need for model testing, facilitate interpolating and extrapolating test data, aid in optimizing heat-exchanger design and performance, and provide scaling capability. Thus tremendous savings of cost and time are realized. With the advent of large digital computers and advances in the development of computational fluid mechanics, it has become possible to predict analytically, through numerical solution, the conservation equations of mass, momentum, and energy for both the shellside and tubeside fluids. The numerical modeling technique will be a valuable, cost-effective design tool for development of advanced heat exchangers.

  15. On-Line Monitoring and Diagnostics of the Integrity of Nuclear Plant Steam Generators and Heat Exchangers.

    SciTech Connect

    Belle R. Upadhyaya; J. Wesley Hines

    2004-09-27

    The overall purpose of this Nuclear Engineering Education Research (NEER) project was to integrate new, innovative, and existing technologies to develop a fault diagnostics and characterization system for nuclear plant steam generators (SG) and heat exchangers (HX). Issues related to system level degradation of SG and HX tubing, including tube fouling, performance under reduced heat transfer area, and the damage caused by stress corrosion cracking, are the important factors that influence overall plant operation, maintenance, and economic viability of nuclear power systems. The research at The University of Tennessee focused on the development of techniques for monitoring process and structural integrity of steam generators and heat exchangers. The objectives of the project were accomplished by the completion of the following tasks. All the objectives were accomplished during the project period. This report summarizes the research and development activities, results, and accomplishments during June 2001-September 2004. (1) Development and testing of a high-fidelity nodal model of a U-tube steam generator (UTSG) to simulate the effects of fouling and to generate a database representing normal and degraded process conditions. Application of the group method of data handling (GMDH) method for process variable prediction. (2) Development of a laboratory test module to simulate particulate fouling of HX tubes and its effect on overall thermal resistance. Application of the GMDH technique to predict HX fluid temperatures, and to compare with the calculated thermal resistance. (3) Development of a hybrid modeling technique for process diagnosis and its evaluation using laboratory heat exchanger test data. (4) Development and testing of a sensor suite using piezo-electric devices for monitoring structural integrity of both flat plates (beams) and tubing. Experiments were performed in air, and in water with and without bubbly flow. (5) Development of advanced signal

  16. On-Line Monitoring and Diagnostics of the Integrity of Nuclear Plant Steam Generators and Heat Exchangers, Volumes 1, 2

    SciTech Connect

    Upadhyaya, Belle R.; Hines, J. Wesley; Lu, Baofu

    2005-06-03

    The overall purpose of this Nuclear Engineering Education Research (NEER) project was to integrate new, innovative, and existing technologies to develop a fault diagnostics and characterization system for nuclear plant steam generators (SG) and heat exchangers (HX). Issues related to system level degradation of SG and HX tubing, including tube fouling, performance under reduced heat transfer area, and the damage caused by stress corrosion cracking, are the important factors that influence overall plant operation, maintenance, and economic viability of nuclear power systems. The research at The University of Tennessee focused on the development of techniques for monitoring process and structural integrity of steam generators and heat exchangers. The objectives of the project were accomplished by the completion of the following tasks. All the objectives were accomplished during the project period. This report summarizes the research and development activities, results, and accomplishments during June 2001 September 2004. Development and testing of a high-fidelity nodal model of a U-tube steam generator (UTSG) to simulate the effects of fouling and to generate a database representing normal and degraded process conditions. Application of the group method of data handling (GMDH) method for process variable prediction. Development of a laboratory test module to simulate particulate fouling of HX tubes and its effect on overall thermal resistance. Application of the GMDH technique to predict HX fluid temperatures, and to compare with the calculated thermal resistance.Development of a hybrid modeling technique for process diagnosis and its evaluation using laboratory heat exchanger test data. Development and testing of a sensor suite using piezo-electric devices for monitoring structural integrity of both flat plates (beams) and tubing. Experiments were performed in air, and in water with and without bubbly flow. Development of advanced signal processing methods using

  17. High Flux Heat Exchanger

    DTIC Science & Technology

    1993-01-01

    called an enhancement surfkce) is bonded to the chip. In both cases, the electronics board is immersed in a dielectric coolant . Bare chip cooling...the stocking of a dielectric coolant , which add to complexity and maintenance costs. 4. High performance heat pipe heat spreaders have demonstrated

  18. Heat exchanger and related methods

    DOEpatents

    Turner, Terry D.; McKellar, Michael G.

    2015-12-22

    Heat exchangers include a housing having an inlet and an outlet and forming a portion of a transition chamber. A heating member may form another portion of the transition chamber. The heating member includes a first end having a first opening and a second end having a second opening larger than the first opening. Methods of conveying a fluid include supplying a first fluid into a transition chamber of a heat exchanger, supplying a second fluid into the transition chamber, and altering a state of a portion of the first fluid with the second fluid. Methods of sublimating solid particles include conveying a first fluid comprising a material in a solid state into a transition chamber, heating the material to a gaseous state by directing a second fluid through a heating member and mixing the first fluid and the second fluid.

  19. Bistability in radiative heat exchange

    NASA Astrophysics Data System (ADS)

    Rudakov, V. I.; Ovcharov, V. V.; Prigara, V. P.

    2008-08-01

    The possibility of a bistable regime in systems with radiative heat exchange is theoretically demonstrated for the first time. The transfer characteristics of a radiation-closed stationary system have been calculated, in which the radiator is a blackbody and the absorber is made of a material with the absorptivity sharply increasing in a certain temperature interval. The radiator and absorber are separated by a vacuum gap. The heat exchange between the system and the environment is controlled by varying the flow rate of a heat-transfer agent cooling the absorber. The output parameter of a bistable system is the absorber temperature, while the input parameter can be either the radiator temperature or the heat-transfer agent flow rate. Depending on the choice of the input parameter, the transfer characteristic of the system is either represented by a usual S-like curve or has an inverted shape.

  20. [Biofouling of heat exchange tubes].

    PubMed

    Montero, F; Pintado, J L

    1994-01-01

    We compared the biofouling behavior of different materials (admiralty brass, stainless steel, and titanium) commonly used to construct heat exchangers in thermoelectric plants. The incidence of film formation on the loss of heat during transference was assessed, and analyzed in terms of plant efficiency and corrosion, both general and localized development. Our results showed that the resistance of titanium and stainless steel to corrosion was similar, and much better than that of admiralty brass. Biofouling, however, was higher in the first two materials.

  1. Ceramic heat exchanger

    DOEpatents

    LaHaye, P.G.; Rahman, F.H.; Lebeau, T.P.; Severin, B.K.

    1998-06-16

    A tube containment system is disclosed. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture. 6 figs.

  2. Ceramic heat exchanger

    DOEpatents

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

    A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

  3. 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.

  4. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  5. 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.

  6. Compact Ceramic Microchannel Heat Exchangers

    SciTech Connect

    Lewinsohn, Charles

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  7. Oxidizer heat exchanger component test

    NASA Technical Reports Server (NTRS)

    Kanic, P. G.

    1988-01-01

    The RL10-IIB engine, is capable of multimode thrust operation. The engine operates at two low-thrust levels: tank head idle (THI), approximately 1 to 2 percent of full thrust; and pumped idle, 10 percent of full thrust. Operation at THI provides vehicle propellant settling thrust and efficient thermal conditioning; PI operation provides vehicle tank prepressurization and maneuver thrust for low-g deployment. Stable combustion of the RL10-IIB engine during the low-thrust operating modes can be accomplished by using a heat exchanger to supply gaseous oxygen to the propellant injector. The oxidized heat exchanger (OHE) vaporizes the liquid oxygen using hydrogen as the energy source. This report summarizes the test activity and post-test data analysis for two possible heat exchangers, each of which employs a completely different design philosophy. One design makes use of a low-heat transfer (PHT) approach in combination with a volume to attenuate pressure and flow oscillations. The test data showed that the LHT unit satisfied the oxygen exit quality of 0.95 or greater in both the THI and PI modes while maintaining stability. The HHT unit fulfilled all PI requirements; data for THI satisfactory operation is implied from experimental data that straddle the exact THI operating point.

  8. Method of pressure pulse cleaning a tube bundle heat exchanger

    SciTech Connect

    Scharton, T.D.; Taylor, G.B.

    1987-04-07

    A method is described of removing the products of corrosion, oxidation, sedimentation and comparable chemical reactions collectively known as sludge which settle on the bottom of a tube bundle heat exchange and form a pile of sludge. The tube bundle heat exchanger is characterized by a tube bundle heat exchanger wall and a thick metal plate known as a tube sheet near the lower portion of the tube bundle heat exchanger wall's interior surface. The tube sheet serves to support the lower ends of a multiplicity of heat exchanger tubes within the tube bundle heat exchanger. The tube bundle heat exchange wall further comprises a multiplicity of small holes known as hand holes, manways, drain lines and vents, located around its circumference and above the tube sheet. The method is described of removing the pile of sludge which settles on the tube sheet comprising: a. locating at least one air-gun type pressure pulse shock wave source outside the tube bundle heat exchanger so as to be able to introduce pressure pulse shock waves through one or more of the multiplicity of hand holes, manways, drain lines and vents; and b. filling the tube bundle heat exchanger with a liquid to a level above the pile of sludge.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. SODIUM-WATER HEAT EXCHANGER

    DOEpatents

    Simmons, W.R.; Koch, L.J.

    1962-04-17

    A heat exchanger comprising a tank for hot liquid and a plurality of concentric, double tubes for cool liquid extending vertically through the tank is described. These tubes are bonded throughout most of their length but have an unbonded portion at both ends. The inner tubes extend between headers located above and below the tanmk and the outer tubes are welded into tube sheets forming the top and bottom of the tank at locations in the unbonded portions of the tubes. (AEC)

  15. 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…

  16. 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…

  17. Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes

    DOEpatents

    Talmud, Fred M.; Garcia-Mallol, Juan-Antonio

    1980-01-01

    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 and includes a steam drum disposed adjacent the fluidized bed and a series of tubes connected at one end to the steam drum. A portion of the tubes are connected to a water drum and in the path of the air and the gaseous products of combustion exiting from the bed. Another portion of the tubes pass through the bed and extend at an angle to the upper surface of the bed.

  18. Heat exchangers of gas turbine engines

    NASA Astrophysics Data System (ADS)

    Baranov, Iu. F.; Mitin, B. M.

    1991-07-01

    The papers presented in this volume focus on methods for studying the thermal and hydraulic characteristics of heat exchangers used in gas turbine engines and methods for the analysis and experimental investigation of the dynamic characteristics of heat exchangers with different coolant flow schemes, including cryogenic heat exchangers. In particular, attention is given to the effect of tube bundle parameters on the dimensional and mass characteristics of high-temperature heat exchangers, a numerical method for calculating the dynamic characteristics of a fuel-air heat exchanger with a buffer cavity, and an experimental study of the air drying process in air coolers.

  19. Heat Exchange, Additive Manufacturing, and Neutron Imaging

    ScienceCinema

    Geoghegan, Patrick

    2016-07-12

    Researchers at the Oak Ridge National Laboratory have captured undistorted snapshots of refrigerants flowing through small heat exchangers, helping them to better understand heat transfer in heating, cooling and ventilation systems.

  20. Heat Exchange, Additive Manufacturing, and Neutron Imaging

    SciTech Connect

    Geoghegan, Patrick

    2015-02-23

    Researchers at the Oak Ridge National Laboratory have captured undistorted snapshots of refrigerants flowing through small heat exchangers, helping them to better understand heat transfer in heating, cooling and ventilation systems.

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

    SciTech Connect

    Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

    2008-09-01

    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 help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor - process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rational for considering liquid metals is the potential convective heat transfer is among the highest known. Thus explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. For process heat it is desired that, intermediate heat exchangers (IHX) transfer heat from the NGNP in the most efficient way possible. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet and inlet of the NGNP. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change

  2. Energy recovery heat exchanger installation

    SciTech Connect

    Bradshaw, N.F.

    1983-08-16

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

  3. On-Line Monitoring and Diagnostics of the Integrity of Nuclear Plant Steam Generators and Heat Exchangers

    SciTech Connect

    Belle R. Upadhyaya; J. Wesley Hines

    2004-09-27

    Integrity monitoring and flaw diagnostics of flat beams and tubular structures was investigated in this research task using guided acoustic signals. A piezo-sensor suite was deployed to activate and collect Lamb wave signals that propagate along metallic specimens. The dispersion curves of Lamb waves along plate and tubular structures are generated through numerical analysis. Several advanced techniques were explored to extract representative features from acoustic time series. Among them, the Hilbert-Huang transform (HHT) is a recently developed technique for the analysis of non-linear and transient signals. A moving window method was introduced to generate the local peak characters from acoustic time series, and a zooming window technique was developed to localize the structural flaws. The time-frequency analysis and pattern recognition techniques were combined for classifying structural defects in brass tubes. Several types of flaws in brass tubes were tested, both in the air and in water. The techniques also proved to be effective under background/process noise. A detailed theoretical analysis of Lamb wave propagation was performed and simulations were carried out using the finite element software system ABAQUS. This analytical study confirmed the behavior of the acoustic signals acquired from the experimental studies. The report presents the background the analysis of acoustic signals acquired from piezo-electric transducers for structural defect monitoring. A comparison of the use of time-frequency techniques, including the Hilbert-Huang transform, is presented. The report presents the theoretical study of Lamb wave propagation in flat beams and tubular structures, and the need for mode separation in order to effectively perform defect diagnosis. The results of an extensive experimental study of detection, location, and isolation of structural defects in flat aluminum beams and brass tubes are presented. The results of this research show the feasibility of on-line

  4. 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.

  5. Improved ceramic heat exchange material

    NASA Technical Reports Server (NTRS)

    Mccollister, H. L.

    1977-01-01

    Improved corrosion resistant ceramic materials that are suitable for use as regenerative heat exchangers for vehicular gas turbines is reported. Two glass-ceramic materials, C-144 and C-145, have superior durability towards sulfuric acid and sodium sulfate compared to lithium aluminosilicate (LAS) Corning heat exchange material 9455. Material C-144 is a leached LAS material whose major crystalline phase is silica keatite plus mullite, and C-145 is a LAS keatite solid solution (S.S.) material. In comparison to material 9455, material C-144 is two orders of magnitude better in dimensional stability to sulfuric acid at 300 C, and one order of magnitude better in stability to sodium sulfate at 1000 C. Material C-145 is initially two times better in stability to sulfuric acid, and about one order of magnitude better in stability to sodium sulfate. Both C-144 and C-145 have less than 300 ppm delta L/L thermal expansion from ambient to 1000 C, and good dimensional stability of less than approximately 100 ppm delta L/L after exposure to 1000 C for 100 hours. The glass-ceramic fabrication process produced a hexagonal honeycomb matrix having an 85% open frontal area, 50 micrometer wall thickness, and less than 5% porosity.

  6. 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.

  7. 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.

  8. 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.

  9. Heat exchanger for power generation equipment

    DOEpatents

    Nirmalan, Nirm Velumylm; Bowman, Michael John

    2005-06-14

    A heat exchanger for a turbine is provided wherein the heat exchanger comprises a heat transfer cell comprising a sheet of material having two opposed ends and two opposed sides. In addition, a plurality of concavities are disposed on a surface portion of the sheet of material so as to cause hydrodynamic interactions and affect a heat transfer rate of the turbine between a fluid and the concavities when the fluid is disposed over the concavities.

  10. The constructal size of a heat exchanger

    NASA Astrophysics Data System (ADS)

    Bejan, A.; Lorente, S.; Martins, L.; Meyer, J. P.

    2017-08-01

    The architecture of heat exchangers is a classical subject that has been studied extensively in the past. In this paper, we address the fundamental question of what the size of the heat exchanger should be, in addition to what architectural features it should have. The answer to the size question follows from the tradeoff between (1) the useful power lost because of heat transfer and fluid flow and (2) the power destroyed during transportation, manufacturing, and maintenance. Changes in heat exchanger size induce changes in the opposite sign in the power requirements (1) and (2). This fundamental tradeoff regarding size is illustrated by considering one side of a heat exchanger (one flow passage) in laminar flow and in fully rough turbulent flow, with several duct cross sectional shapes and arrays of channels in parallel. The size tradeoff is present in heat exchanger applications across the board, from vehicles to stationary power plants.

  11. Heat Exchanger Lab for Chemical Engineering Undergraduates

    ERIC Educational Resources Information Center

    Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.

    2015-01-01

    Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…

  12. Heat exchanger with a removable tube section

    DOEpatents

    Wolowodiuk, W.; Anelli, J.

    1975-07-29

    A heat exchanger is described in which the tube sheet is secured against primary liquid pressure, but which allows for easy removal of the tube section. The tube section is supported by a flange which is secured by a number of shear blocks, each of which extends into a slot which is immovable with respect to the outer shell of the heat exchanger. (auth)

  13. Heat Exchanger Lab for Chemical Engineering Undergraduates

    ERIC Educational Resources Information Center

    Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.

    2015-01-01

    Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…

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

    DOEpatents

    Koplow, Jeffrey P [San Ramon, CA

    2012-07-24

    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.

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

    DOEpatents

    Koplow, Jeffrey P.

    2015-12-08

    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.

  16. 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.

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

    DOEpatents

    Koplow, Jeffrey P

    2015-03-24

    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.

  18. 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.

  19. Testing and plugging power plant heat exchangers

    SciTech Connect

    Sutor, F.

    1994-12-31

    Heat Exchanger tubes fail for any number of reasons including but certainly not limited to the cumulative effects of corrosion, erosion, thermal stress and fatigue. This presentation will attempt to identify the most common techniques for determining which tubes are leaking and then introduce the products in use to plug the leaking tubes. For the sake of time I will limit the scope of this presentation to include feedwater heaters and secondary system heat exchangers such as Hydrogen Coolers, Lube Oil Coolers, and nuclear Component Cooling Water, Emergency Cooling Water, Regenerative Heat Recovery heat exchangers.

  20. 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.

  1. Improved ceramic heat exchanger materials

    NASA Technical Reports Server (NTRS)

    Rauch, H. W.

    1980-01-01

    The development and evaluation of materials for potential application as heat exchanger structures in automotive gas turbine engines is discussed. Test specimens in the form of small monolithic bars were evaluated for thermal expansion and dimensional stability before and after exposure to sea salt and sulfuric acid, followed by short and long term cycling at temperatures up to 1200 C. The material finally selected, GE-7808, consists of the oxides, ZrO2-MgO-Al2O3-S1O2, and is described generically as ZrMAS. The original version was based on a commercially available cordierite (MAS) frit. However, a clay/talc mixture was demonstrated to be a satisfactory very low cost source of the cordierite (MAS) phase. Several full size honeycomb regenerator cores, about 10.2 cm thick and 55 cm diameter were fabricated from both the frit and mineral versions of GE-7808. The honeycomb cells in these cores had rectangular dimensions of about 0.5 mm x 2.5 mm and a wall thickness of approximately 0.2 mm. The test data show that GE-7808 is significantly more stable at 1100 C in the presence of sodium than the aluminosilicate reference materials. In addition, thermal exposure up to 1100 C, with and without sodium present, results in essentially no change in thermal expansion of GE-7808.

  2. Heat exchanger and method of making

    NASA Astrophysics Data System (ADS)

    Fortini, A.; Kazaroff, J. M.

    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.

  3. Heat exchanger and method of making

    NASA Astrophysics Data System (ADS)

    Fortini, A.; Kazaroff, J. M.

    1980-04-01

    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.

  4. Phase Change Material Heat Exchanger Life Test

    NASA Technical Reports Server (NTRS)

    Lillibridge, Sean; Stephan, Ryan; Lee, Steve; He, Hung

    2008-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The emitted infrared (IR) heat flux from the lunar surface varies drastically from the light side to the dark side of the moon. Due to the extremely high incident IR flux, especially at low beta angles, a radiator is oftentimes unable to reject the vehicle heat load throughout the entire lunar orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor," storing thermal energy when the radiator is unable to reject the required heat load. The stored energy is then removed from the PCM heat exchanger when the environment is more benign. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration Low Lunar Orbit missions. The Advanced Thermal Control project at JSC is completing a PCM heat exchanger life test to determine whether further technology development is warranted. The life test is being conducted on four nPentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 melt-freeze cycles will be performed and reported in the current document.

  5. Phase Change Material Heat Exchanger Life Test

    NASA Technical Reports Server (NTRS)

    Lillibridge, Sean; Stephan, Ryan; Lee, Steve; He, Hung

    2008-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The emitted infrared (IR) heat flux from the lunar surface varies drastically from the light side to the dark side of the moon. Due to the extremely high incident IR flux, especially at low beta angles, a radiator is oftentimes unable to reject the vehicle heat load throughout the entire lunar orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor," storing thermal energy when the radiator is unable to reject the required heat load. The stored energy is then removed from the PCM heat exchanger when the environment is more benign. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration Low Lunar Orbit missions. The Advanced Thermal Control project at JSC is completing a PCM heat exchanger life test to determine whether further technology development is warranted. The life test is being conducted on four nPentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 melt-freeze cycles will be performed and reported in the current document.

  6. Heat Transfer in Metal Foam Heat Exchangers at High Temperature

    NASA Astrophysics Data System (ADS)

    Hafeez, Pakeeza

    Heat transfer though open-cell metal foam is experimentally studied for heat exchanger and heat shield applications at high temperatures (˜750°C). Nickel foam sheets with pore densities of 10 and 40 pores per linear inch (PPI), have been used to make the heat exchangers and heat shields by using thermal spray coating to deposit an Inconel skin on a foam core. Heat transfer measurements were performed on a test rig capable of generating hot gas up to 1000°C. The heat exchangers were tested by exposing their outer surface to combustion gases at a temperature of 550°C and 750°C while being cooled by air flowing through them at room temperature at velocities up to 5 m/s. The temperature rise of the air, the surface temperature of the heat exchangers and the air temperature inside the heat exchanger were measured. The volumetric heat transfer coefficient and Nusselt number were calculated for different velocities. The heat transfer performance of the 40PPI sample brazed with the foil is found to be the most efficient. Pressure drop measurements were also performed for 10 and 40PPI metal foam. Thermographic measurements were done on 40PPI foam heat exchangers using a high temperature infrared camera. A high power electric heater was used to produce hot air at 300°C that passed over the foam heat exchanger while the cooling air was blown through it. Heat shields were made by depositing porous skins on metal foam and it was observed that a small amount of coolant leaking through the pores notably reduces the heat transfer from the hot gases. An analytical model was developed based assuming local thermal non-equilibrium that accounts for the temperature difference between solid and fluid phase. The experimental results are found to be in good agreement with the predicted values of the model.

  7. 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…

  8. 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…

  9. 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.

  10. Feedwater heater performance evaluation using the heat exchanger workstation

    SciTech Connect

    Ranganathan, K.M.; Singh, G.P.; Tsou, J.L.

    1995-12-01

    A Heat Exchanger Workstation (HEW) has been developed to monitor the condition of heat exchanging equipment power plants. HEW enables engineers to analyze thermal performance and failure events for power plant feedwater heaters. The software provides tools for heat balance calculation and performance analysis. It also contains an expert system that enables performance enhancement. The Operation and Maintenance (O&M) reference module on CD-ROM for HEW will be available by the end of 1995. Future developments of HEW would result in Condenser Expert System (CONES) and Balance of Plant Expert System (BOPES). HEW consists of five tightly integrated applications: A Database system for heat exchanger data storage, a Diagrammer system for creating plant heat exchanger schematics and data display, a Performance Analyst system for analyzing and predicting heat exchanger performance, a Performance Advisor expert system for expertise on improving heat exchanger performance and a Water Calculator system for computing properties of steam and water. In this paper an analysis of a feedwater heater which has been off-line is used to demonstrate how HEW can analyze the performance of the feedwater heater train and provide an economic justification for either replacing or repairing the feedwater heater.

  11. 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.

  12. Heat Exchanger Support Bracket Design Calculations

    SciTech Connect

    Rucinski, Russ; /Fermilab

    1995-01-12

    This engineering note documents the design of the heat exchanger support brackets. The heat exchanger is roughly 40 feet long, 22 inches in diameter and weighs 6750 pounds. It will be mounted on two identical support brackets that are anchored to a concrete wall. The design calculations were done for one bracket supporting the full weight of the heat exchanger, rounded up to 6800 pounds. The design follows the American Institute of Steel Construction (AISC) Manual of steel construction, Eighth edition. All calculated stresses and loads on welds were below allowables.

  13. Heat exchanger with transpired, highly porous fins

    DOEpatents

    Kutscher, Charles F.; Gawlik, Keith

    2002-01-01

    The heat exchanger includes a fin and tube assembly with increased heat transfer surface area positioned within a hollow chamber of a housing to provide effective heat transfer between a gas flowing within the hollow chamber and a fluid flowing in the fin and tube assembly. A fan is included to force a gas, such as air, to flow through the hollow chamber and through the fin and tube assembly. The fin and tube assembly comprises fluid conduits to direct the fluid through the heat exchanger, to prevent mixing with the gas, and to provide a heat transfer surface or pathway between the fluid and the gas. A heat transfer element is provided in the fin and tube assembly to provide extended heat transfer surfaces for the fluid conduits. The heat transfer element is corrugated to form fins between alternating ridges and grooves that define flow channels for directing the gas flow. The fins are fabricated from a thin, heat conductive material containing numerous orifices or pores for transpiring the gas out of the flow channel. The grooves are closed or only partially open so that all or substantially all of the gas is transpired through the fins so that heat is exchanged on the front and back surfaces of the fins and also within the interior of the orifices, thereby significantly increasing the available the heat transfer surface of the heat exchanger. The transpired fins also increase heat transfer effectiveness of the heat exchanger by increasing the heat transfer coefficient by disrupting boundary layer development on the fins and by establishing other beneficial gas flow patterns, all at desirable pressure drops.

  14. Measuring Heat-Exchanger Water Leakage

    NASA Technical Reports Server (NTRS)

    Zampiceni, J.

    1986-01-01

    Water leakage in heat exchanger measured directly with help of electroytic hygrometer. In new technique, flow of nitrogen gas set up in one loop of heat exchanger. Other loop filled with water under pressure. Water concentration produced by leakage of water into nitrogen flow measured by hygrometer. New measurement method determines water concentrations up to 2,000 parts per million with accuracy of +/- 5 percent.

  15. Stirling Engine With Radial Flow Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Vitale, N.; Yarr, George

    1993-01-01

    Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

  16. 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.

  17. Ceramic heat exchangers: Manufacturing techniques and performance

    NASA Astrophysics Data System (ADS)

    Merrigan, M. A.; Sandstrom, D. J.

    1981-05-01

    The objective of the ceramic heat pipe program being conducted at Los Alamos is demonstration of the practical feasibility of this technology for the solution of severe high temperature recuperation functions. Ceramic heat pipe recuperators were theoretically shown to offer distinct advantages over conventional ceramic heat exchangers from the standpoint of efficiency of heat recuperation and economics. The main stumbling block to their widespread utilization is related to the problems of materials for construction and the details of fabrication and assembly. The performance objectives of ceramic heat pipes and some aspects of the materials technology program aimed at solving the problem of economic ceramic heat pipe fabrication are described.

  18. Heat transfer from oriented heat exchange areas

    NASA Astrophysics Data System (ADS)

    Vantuch, Martin; Huzvar, Jozef; Kapjor, Andrej

    2014-03-01

    This paper deals with the transfer of heat-driven heat transfer surface area in relation to the construction of the criterion equation for "n" horizontal pipe one about another. On the bases of theoretical models have been developed for calculating the thermal performance of natural convection by Churilla and Morgan, for various pipe diameters and temperatures. These models were compared with models created in CFD-Fluent Ansys the same boundary conditions. The aim of the analyse of heat and fluxional pipe fields "n" pipes one about another at natural convection is the creation of criterion equation on the basis of which the heat output of heat transfer from pipe oriented areas one above another with given spacing could be quantified. At presence a sum of criterion equations exists for simple geometrical shapes of individual oriented geometrical areas but the criterion equation which would consider interaction of fluxional field generated by free convection from multiple oriented areas is not mentioned in standardly accessible technical literature and other magazine publications.

  19. 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.

  20. Flow and heat transfer enhancement in tube heat exchangers

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  1. Condensing, Two-Phase, Contact Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Cox, R. L.; Oren, J. A.; Sauer, L. W.

    1988-01-01

    Two-phase heat exchanger continuously separates liquid and vapor phases of working fluid and positions liquid phase for efficient heat transfer. Designed for zero gravity. Principle is adapted to other phase-separation applications; for example, in thermodynamic cycles for solar-energy conversion.

  2. Condensing, Two-Phase, Contact Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Cox, R. L.; Oren, J. A.; Sauer, L. W.

    1988-01-01

    Two-phase heat exchanger continuously separates liquid and vapor phases of working fluid and positions liquid phase for efficient heat transfer. Designed for zero gravity. Principle is adapted to other phase-separation applications; for example, in thermodynamic cycles for solar-energy conversion.

  3. High-Differential-Pressure Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Hylin, Edward C.

    1987-01-01

    Heat exchanger accommodates large pressure difference between heat-transfer fluids. Designed so all welded joints inspected with x rays to ensure leak-free operation over many years. Joints between fluids and between each fluid and environment radiographically inspectable. Used in Stirling-cycle engines, including those in proposed nuclear and solar powerplants.

  4. Heat Exchanger With Internal Pin Elements

    DOEpatents

    Gerstmann, Joseph; Hannon, Charles L.

    2004-01-13

    A heat exchanger/heater comprising a tubular member having a fluid inlet end, a fluid outlet end and plurality of pins secured to the interior wall of the tube. Various embodiments additionally comprise a blocking member disposed concentrically inside the pins, such as a core plug or a baffle array. Also disclosed is a vapor generator employing an internally pinned tube, and a fluid-heater/heat-exchanger utilizing an outer jacket tube and fluid-side baffle elements, as well as methods for heating a fluid using an internally pinned tube.

  5. High effectiveness contour matching contact heat exchanger

    NASA Technical Reports Server (NTRS)

    Blakely, Robert L. (Inventor); Roebelen, George J., Jr. (Inventor); Davenport, Arthur K. (Inventor)

    1988-01-01

    There is a need in the art for a heat exchanger design having a flexible core providing contour matching capabilities, which compensates for manufacturing tolerance and distortion buildups, and which accordingly furnishes a relatively uniform thermal contact conductance between the core and external heat sources under essentially all operating conditions. The core of the heat exchanger comprises a top plate and a bottom plate, each having alternate rows of pins attached. Each of the pins fits into corresponding tight-fitting recesses in the opposite plate.

  6. 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.

  7. Phase Change Material Heat Exchanger Life Test

    NASA Technical Reports Server (NTRS)

    Lillibridge, Sean; Stephan, Ryan

    2009-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The IR environment of the space craft varies drastically from the light side to the dark side of the moon. The result is a situation where a radiator sized for the maximal heat load in the most adverse situation is subject to freezing on the dark side of the orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor," storing thermal energy when there is too much being produced by the space craft to reject to space, and then feeding that energy back into the thermal loop when conditions are more favorable. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration LLO missions. In order to validate the performance of PCM Heat Exchangers, a life test is being conducted on four n-Pentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 melt-freeze cycles will be performed.

  8. Phase Change Material Heat Exchanger Life Test

    NASA Technical Reports Server (NTRS)

    Lillibridge, Sean; Stephan, Ryan

    2009-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The IR environment of the space craft varies drastically from the light side to the dark side of the moon. The result is a situation where a radiator sized for the maximal heat load in the most adverse situation is subject to freezing on the dark side of the orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor," storing thermal energy when there is too much being produced by the space craft to reject to space, and then feeding that energy back into the thermal loop when conditions are more favorable. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration LLO missions. In order to validate the performance of PCM Heat Exchangers, a life test is being conducted on four n-Pentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 melt-freeze cycles will be performed.

  9. Heat exchanger with auxiliary cooling system

    DOEpatents

    Coleman, John H.

    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.

  10. 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.

  11. Heat exchanger bypass system for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    A heat exchanger bypass system for an absorption refrigeration system is disclosed. The bypass system operates to pass strong solution from the generator around the heat exchanger to the absorber of the absorption refrigeration system when strong solution builds up in the generator above a selected level indicative of solidification of strong solution in the heat exchanger or other such blockage. The bypass system includes a bypass line with a gooseneck located in the generator for controlling flow of strong solution into the bypass line and for preventing refrigerant vapor in the generator from entering the bypass line during normal operation of the refrigeration system. Also, the bypass line includes a trap section filled with liquid for providing a barrier to maintain the normal pressure difference between the generator and the absorber even when the gooseneck of the bypass line is exposed to refrigerant vapor in the generator. Strong solution, which may accumulate in the trap section of the bypass line, is diluted, to prevent solidification, by supplying weak solution to the trap section from a purge system for the absorption refrigeration system.

  12. Numerical study of heat transfer characteristics in BOG heat exchanger

    NASA Astrophysics Data System (ADS)

    Yan, Yan; Pfotenhauer, John M.; Miller, Franklin; Ni, Zhonghua; Zhi, Xiaoqin

    2016-12-01

    In this study, a numerical study of turbulent flow and the heat transfer process in a boil-off liquefied natural gas (BOG) heat exchanger was performed. Finite volume computational fluid dynamics and the k - ω based shear stress transport model were applied to simulate thermal flow of BOG and ethylene glycol in a full-sized 3D tubular heat exchanger. The simulation model has been validated and compared with the engineering specification data from its supplier. In order to investigate thermal characteristics of the heat exchanger, velocity, temperature, heat flux and thermal response were studied under different mass flowrates in the shell-side. The shell-side flow pattern is mostly determined by viscous forces, which lead to a small velocity and low temperature buffer area in the bottom-right corner of the heat exchanger. Changing the shell-side mass flowrate could result in different distributions of the shell-side flow. However, the distribution in the BOG will remain in a relatively stable pattern. Heat flux increases along with the shell-side mass flowrate, but the increase is not linear. The ratio of increased heat flux to the mass flow interval is superior at lower mass flow conditions, and the threshold mass flow for stable working conditions is defined as greater than 0.41 kg/s.

  13. The classification of the heat exchangers and theory research

    NASA Astrophysics Data System (ADS)

    Liu, Jian

    2017-05-01

    The Heat Exchangers which could transfer the heat from hot fluid to cold fluid is used widely in industry. Article describe the classification of the Heat Exchangers, according to the working principle, can be divided into the hybrid Heat Exchangers, surface Heat Exchangers and regenerative Heat Exchangers three categories. The hybrid Heat Exchangers is through direct mixed the hot and cold fluid to exchange heat. The surface Heat Exchangers uses a wall to separate the cold and hot fluid to exchange heat. The regenerative Heat Exchangers make the cold and hot fluid flow through the same heat transfer surface in turn to exchange heat. At same time, the factors which put effect in turn to performance of Heat Exchanger are illustrated in this paper as well as the evaluating criterion, a new approach for the analysis of the Heat Exchanger performance. Finally the article reviews the domestic research on Heat Exchanger of deficiencies in the process of development, the domestic researches on the Heat Exchanger to put forward some further development prospect.

  14. Microtube strip heat exchanger. Final technical report

    SciTech Connect

    Doty, F.D.

    1992-07-09

    The purpose of this contract has been to explore the limits of miniaturization of heat exchangers with the goals of (1) improving the theoretical understanding of laminar heat exchangers, (2) evaluating various manufacturing difficulties, and (3) identifying major applications for the technology. A low-cost, ultra-compact heat exchanger could have an enormous impact on industry in the areas of cryocoolers and energy conversion. Compact cryocoolers based on the reverse Brayton cycle (RBC) would become practical with the availability of compact heat exchangers. Many experts believe that hardware advances in personal computer technology will rapidly slow down in four to six years unless lowcost, portable cryocoolers suitable for the desktop supercomputer can be developed. Compact refrigeration systems would permit dramatic advances in high-performance computer work stations with ``conventional`` microprocessors operating at 150 K, and especially with low-cost cryocoolers below 77 K. NASA has also expressed strong interest in our MTS exchanger for space-based RBC cryocoolers for sensor cooling. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

  15. Heat exchanger restart evaluation. Revision 1

    SciTech Connect

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-03-18

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4A was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the identified tube. The leaking tube was removed and examined metallurgically to determine the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summary herein.

  16. ETR HEAT EXCHANGER BUILDING, TRA644. WORKERS ARE INSTALLING HEAT EXCHANGER ...

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

    ETR HEAT EXCHANGER BUILDING, TRA-644. WORKERS ARE INSTALLING HEAT EXCHANGER PIPING. INL NEGATIVE NO. 56-3122. Jack L. Anderson, Photographer, 9/21/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  17. Energy absorber for sodium-heated heat exchanger

    DOEpatents

    Essebaggers, J.

    1975-12-01

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

  18. Heat exchanger for coal gasification process

    DOEpatents

    Blasiole, George A.

    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.

  19. 2. SALEMBROSIUS CONTINUOUS GASFIRED HEAT TREATING LINE AT HEAT TREATMENT ...

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

    2. SALEM-BROSIUS CONTINUOUS GAS-FIRED HEAT TREATING LINE AT HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  20. 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.

  1. Heat exchanger containing a component capable of discontinuous movement

    DOEpatents

    Wilson, D.G.

    1993-11-09

    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. 11 figures.

  2. Heat exchanger containing a component capable of discontinuous movement

    DOEpatents

    Wilson, David Gordon

    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.

  3. Heat exchanger containing a component capable of discontinuous movement

    DOEpatents

    Wilson, David G.

    1993-01-01

    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.

  4. Carbon nanotube heat-exchange systems

    DOEpatents

    Hendricks, Terry Joseph; Heben, Michael J.

    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).

  5. Micro-Scale Regenerative Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

    2004-01-01

    A micro-scale regenerative heat exchanger has been designed, optimized and fabricated for use in a micro-Stirling device. Novel design and fabrication techniques enabled the minimization of axial heat conduction losses and pressure drop, while maximizing thermal regenerative performance. The fabricated prototype is comprised of ten separate assembled layers of alternating metal-dielectric composite. Each layer is offset to minimize conduction losses and maximize heat transfer by boundary layer disruption. A grating pattern of 100 micron square non-contiguous flow passages were formed with a nominal 20 micron wall thickness, and an overall assembled ten-layer thickness of 900 microns. Application of the micro heat exchanger is envisioned in the areas of micro-refrigerators/coolers, micropower devices, and micro-fluidic devices.

  6. Multidimensional numerical modeling of heat exchangers

    NASA Astrophysics Data System (ADS)

    Sha, W. T.; Yang, C. I.; Kao, T. T.; Cho, S. M.

    A comprehensive, multidimensional, thermal-hydraulic model is developed for the analysis of shell-and-tube heat exchangers for liquid-metal services. For the shellside fluid, the conservation equations of mass, momentum, and energy for continuum fluids are modified using the concept of porosity, surface permeability and distributed resistance to account for the blockage effects due to the presence of heat-transfer tubes, flow baffles/shrouds, the support plates, etc. On the tubeside, the heat-transfer tubes are connected in parallel between the inlet and outlet plenums, and tubeside flow distribution is calculated based on the plenum-to-plenum pressure difference being equal for all tubes. It is assumed that the fluid remains single-phase on the shell side and may undergo phase-change on the tube side, thereby simulating the conditions of Liquid Metal Fast Breeder Reactor (LMFBR) intermediate heat exchangers (IHX) and steam generators (SG).

  7. Liquid Salt Heat Exchanger Technology for VHTR Based Applications

    SciTech Connect

    Anderson, Mark; Sridhara, Kumar; Allen, Todd; Peterson, Per

    2012-10-11

    The objective of this research is to evaluate performance of liquid salt fluids for use as a heat carrier for transferring high-temperature process heat from the very high-temperature reactor (VHTR) to chemical process plants. Currently, helium is being considered as the heat transfer fluid; however, the tube size requirements and the power associated with pumping helium may not be economical. Recent work on liquid salts has shown tremendous potential to transport high-temperature heat efficiently at low pressures over long distances. This project has two broad objectives: To investigate the compatibility of Incoloy 617 and coated and uncoated SiC ceramic composite with MgCl2-KCl molten salt to determine component lifetimes and aid in the design of heat exchangers and piping; and, To conduct the necessary research on the development of metallic and ceramic heat exchangers, which are needed for both the helium-to-salt side and salt-to-process side, with the goal of making these heat exchangers technologically viable. The research will consist of three separate tasks. The first task deals with material compatibility issues with liquid salt and the development of techniques for on-line measurement of corrosion products, which can be used to measure material loss in heat exchangers. Researchers will examine static corrosion of candidate materials in specific high-temperature heat transfer salt systems and develop an in situ electrochemical probe to measure metallic species concentrations dissolved in the liquid salt. The second task deals with the design of both the intermediate and process side heat exchanger systems. Researchers will optimize heat exchanger design and study issues related to corrosion, fabrication, and thermal stresses using commercial and in-house codes. The third task focuses integral testing of flowing liquid salts in a heat transfer/materials loop to determine potential issues of using the salts and to capture realistic behavior of the salts in a

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

    DOE PAGES

    Bartel, N.; Chen, M.; Utgikar, V. P.; ...

    2015-04-04

    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

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

    SciTech Connect

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

    2015-04-04

    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 optimum 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.

  10. Solidification studies of automotive heat exchanger materials

    NASA Astrophysics Data System (ADS)

    Carlberg, T.; Jaradeh, M.; Kamgou Kamaga, H.

    2006-11-01

    Modifications of the aluminum alloy AA 3003 have been studied to improve and tailorits properties for applications in automotive heat exchangers. Laboratory techniques have been applied to simulate industrial direct-chill casting, and some basic solidification studies have been conducted. The results are coupled to structures observed in industrial-size ingots and discussed in terms of structure-property relations.

  11. Measurement of heat and moisture exchanger efficiency.

    PubMed

    Chandler, M

    2013-09-01

    Deciding between a passive heat and moisture exchanger or active humidification depends upon the level of humidification that either will deliver. Published international standards dictate that active humidifiers should deliver a minimum humidity of 33 mg.l(-1); however, no such requirement exists, for heat and moisture exchangers. Anaesthetists instead have to rely on information provided by manufacturers, which may not allow comparison of different devices and their clinical effectiveness. I suggest that measurement of humidification efficiency, being the percentage moisture returned and determined by measuring the temperature of the respired gases, should be mandated, and report a modification of the standard method that will allow this to be easily measured. In this study, different types of heat and moisture exchangers for adults, children and patients with a tracheostomy were tested. Adult and paediatric models lost between 6.5 mg.l(-1) and 8.5 mg.l(-1) moisture (corresponding to an efficiency of around 80%); however, the models designed for patients with a tracheostomy lost between 16 mg.l(-1) and 18 mg.l(-1) (60% efficiency). I propose that all heat and moisture exchangers should be tested in this manner and percentage efficiency reported to allow an informed choice between different types and models.

  12. 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.

  13. Automatic tube cleaning systems for condensers and heat exchangers

    SciTech Connect

    Wagner, M.J.

    1996-11-01

    Automatic On-Line Tube Cleaning Systems (ATCS) have been proven as a reliably positive means of maximizing heat transfer coefficients (ceterus paribas) in condensers and heat exchangers. The maintenance of maximum heat transfer rates result in the operational improvement of plant heat rate and a consequent reduction in greenhouse gas emissions. In the case of air conditioning machines the ATCS acts to maximize and maintain capacity while minimizing power consumption. It has been estimated that over $300 billion a year is currently wasted in the world`s consumption of energy. Significant reductions in fuel costs, power costs and greenhouse gas emissions can be achieved through the employment of automatic on-line mechanical tube cleaning systems.

  14. Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers

    Treesearch

    Lawrence D. Garrett; Howard Duchacek; Mariafranca Morselli; Frederick M. Laing; Neil K. Huyler; James W. Marvin

    1977-01-01

    A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was similar to syrup produced in conventional systems in flavor and in chemical and physical composition; and (3) Heat...

  15. Optimization of Borehole Heat Exchanger Arrays

    NASA Astrophysics Data System (ADS)

    Schulte, Daniel; Rühaak, Wolfram; Welsch, Bastian; Oladyshkin, Sergey; Sass, Ingo

    2016-04-01

    Arrays of borehole heat exchangers are an increasingly popular source for renewable energy. Furthermore, they can serve as borehole thermal energy storages for seasonally fluctuating heat sources like solar thermal energy or district heating grids. However, the uncertainty of geological parameters and the nonlinear behavior of the complex system make it difficult to simulate and predict the required design of borehole heat exchanger arrays. As a result, the arrays easily turn out to be over or undersized, which compromises the economic feasibility of these systems. Here, we present a novel optimization strategy for the design of borehole thermal energy storages. The arbitrary polynomial chaos expansion method is used to build a proxy model from a set of numerical training simulations, which allows for the consideration of parameter uncertainties. Thus, the resulting proxy model bypasses the problem of excessive computation time for the numerous function calls required for a mathematical optimization. Additionally, we iteratively refine the proxy model during the optimization procedure using additional numerical simulation runs. With the presented solution, many aspects of borehole heat exchanger arrays can be optimized under geological uncertainty.

  16. Heat Exchanger Design in Combined Cycle Engines

    NASA Astrophysics Data System (ADS)

    Webber, H.; Feast, S.; Bond, A.

    Combined cycle engines employing both pre-cooled air-breathing and rocket modes of operation are the most promising propulsion system for achieving single stage to orbit vehicles. The air-breathing phase is purely for augmentation of the mission velocity required in the rocket phase and as such must be mass effective, re-using the components of the rocket cycle, whilst achieving adequate specific impulse. This paper explains how the unique demands placed on the air-breathing cycle results in the need for sophisticated thermodynamics and the use of a series of different heat exchangers to enable precooling and high pressure ratio compression of the air for delivery to the rocket combustion chambers. These major heat exchanger roles are; extracting heat from incoming air in the precooler, topping up cycle flow temperatures to maintain constant turbine operating conditions and extracting rejected heat from the power cycle via regenerator loops for thermal capacity matching. The design solutions of these heat exchangers are discussed.

  17. High Performance Woven Mesh Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Wirtz, Richard A.; Li, Chen; Park, Ji-Wook; Xu, Jun

    2002-07-01

    Simple-to-fabricate woven mesh structures, consisting of bonded laminates of two-dimensional plain-weave conductive screens, or three-dimensional orthogonal weaves are described. Geometric equations show that these porous matrices can be fabricated to have a wide range of porosity and a highly anisotropic thermal conductivity vector. A mathematical model of the thermal performance of such a mesh, deployed as a heat exchange surface, is developed. Measurements of pressure drop and overall heat transfer rate are reported and used with the performance model to develop correlation equations of mesh friction factor and Colburn j-factor as a function of coolant properties, mesh characteristics and flow rate through the mesh. A heat exchanger performance analysis delineates conditions where the two mesh technologies offer superior performance.

  18. Brayton heat exchange unit development program

    NASA Technical Reports Server (NTRS)

    Morse, C. J.; Richard, C. E.; Duncan, J. D.

    1971-01-01

    A Brayton Heat Exchanger Unit (BHXU), consisting of a recuperator, a heat sink heat exchanger and a gas ducting system, was designed, fabricated, and tested. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. 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. Evaluation testing was conducted from which it is estimated that near-design performance can be expected with the use of He-Xe as the working fluid.

  19. ETR HEAT EXCHANGER BUILDING, TRA644. METAL FRAME OF BUILDING GOES ...

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

    ETR HEAT EXCHANGER BUILDING, TRA-644. METAL FRAME OF BUILDING GOES UP IN BACKGROUND AS WORKERS PLACE A SECTION OF WATER LINE THAT WILL CARRY SECONDARY COOLANT BETWEEN HEAT EXCHANGER BUILDING AND THE COOLING TOWER. INL NEGATIVE NO. 56-2205. Jack L. Anderson, Photographer, 6/28/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  20. Selection and costing of heat exchangers

    NASA Astrophysics Data System (ADS)

    1992-12-01

    ESDU 92013 gives guidance on the selection of heat exchanger types for a given duty against various criteria; they include the general characteristics, together with such detailed aspects as the ranges of pressure and temperature appropriate, compatibility with the fluids involved, space and weight requirements, and cleaning accessibility and maintenance. That allows an initial choice to be made from 18 principal types of exchangers. The various types are all illustrated. A final choice can then be made between the feasible types on the basis of costs. Detailed costing data provided by manufacturers are tabulated as a function of heat load, operating pressure and the types of cold- and hot-side fluids for the following types of exchangers: shell-and-tube, double-pipe, printed-circuit, plate-fin, air-cooled and welded plate. Costing data are also tabulated as a function of heat load and the types of cold- and hot-side fluids for gasketed-plate exchangers. Seven worked examples of selection based on technical suitability and using the tabulated cost data illustrate fully the use of the information.

  1. Preliminary SP-100/Stirling heat exchanger designs

    SciTech Connect

    Schmitz, P.; Tower, L.; Dawson, R.; Blue, B.; Dunn, P.

    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.

  2. Titanium for condenser and heat exchanger service

    SciTech Connect

    Mountford, J.A. Jr.

    1996-12-31

    The use of titanium for heat exchanger service has increased dramatically over the past 20 years and continues to expand into many additional market applications. Its greatest use (as both tubing and tubesheets) is in utility steam condensers where tens of millions of feet are produced annually to service plants throughout the world with the harshest of cooling waters. Many additional utility in-plant heat exchangers use titanium as well, as do industries to include the Navy and marine, offshore oil, petrochemical processing, PTA, LNG, desalination, salt production, refinery, refrigeration and air conditioning, among others. With its virtual immunity to all natural and harsh waters (including seawater, brackish, fresh, chloride laden, etc.) and to MIC, titanium eliminates the corrosion problems and concerns related to cooling waters, the effects of tube cleaning operations necessary to eliminate normal debris and fouling, and stagnant or no flow conditions. This paper will review where and why titanium is used as exemplified in its corrosion immunity ranges and heat transfer comparisons, while providing updates on the development of newer available grades and more recent applications. Where thought to be used only in specific plant areas, titanium can and should be considered for providing uncompromised service to reduce maintenance and eliminate persistent corrosion problems in the many other areas where heat exchangers are required.

  3. Preliminary SP-100/Stirling heat exchanger designs

    NASA Technical Reports Server (NTRS)

    Schmitz, Paul; Tower, Leonard; Dawson, Ronald; Blue, Brian; Dunn, Pat

    1993-01-01

    Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor primary 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.

  4. High temperature active heat exchanger research for latent heat storage

    NASA Astrophysics Data System (ADS)

    Alario, J.; Haslett, R.

    1982-02-01

    An active heat exchange method in a latent heat (salt) thermal energy storage system that prevents a low conductivity solid salt layer from forming on heat transfer surfaces was developed. An evaluation of suitable media with melting points in the temperature range of interest (250 to 400 C) limited the candidates to molten salts from the chloride, hydroxide and nitrate families, based on high storage capacity, good corrosion characteristics and availability in large quantities at reasonable cost. The specific salt recommended for laboratory tests was a choride eutectic (20.5KCL o 24.5NaCL o 55.MgCl2% by wt.), with a nominal melting point of 385 C. Various active heat exchange concepts were given a technical and economic comparison to a passive tube shell design for a reference application (300 MW sub t for 6 hours). Test hardware was then built for the most promising concept: a direct contact heat exchanger in which molten salt droplets are injected into a cooler counter flowing stream of liquid metal carrier fluid (lead/Bismuth).

  5. Complex Heat Exchangers for Improved Performance

    NASA Astrophysics Data System (ADS)

    Bran, Gabriela Alejandra

    After a detailed literature review, it was determined that there was a need for a more comprehensive study on the transient behavior of heat exchangers. Computational power was not readily available when most of the work on transient heat exchangers was done (1956 - 1986), so most of these solutions have restrictions, or very specific assumptions. More recently, authors have obtained numerical solutions for more general problems (2003 - 2013), but they have investigated very specific conditions, and cases. For a more complex heat exchanger (i.e. with heat generation), the transient solutions from literature are no longer valid. There was a need to develop a numerical model that relaxes the restrictions of current solutions to explore conditions that have not been explored. A one dimensional transient heat exchanger model was developed. There are no restrictions on the fluids and wall conditions. The model is able to obtain a numerical solution for a wide range of fluid properties and mass flow rates. Another innovative characteristic of the numerical model is that the boundary and initial conditions are not limited to constant values. The boundary conditions can be a function of time (i.e. sinusoidal signal), and the initial conditions can be a function of position. Four different cases were explored in this work. In the first case, the start-up of a system was investigated where the whole system is assumed to be at the same temperature. In the second case, the new steady state in case one gets disrupted by a smaller inlet temperature step change. In the third case, the new steady state in case one gets disrupted by a step change in one of the mass flow rates. The response of these three cases show that there are different transient behaviors, and they depend on the conditions imposed on the system. The fourth case is a system that has a sinusoidal time varying inlet temperature for one of the flows. The results show that the sinusoidal behavior at the inlet

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

    NASA Astrophysics Data System (ADS)

    Coppola, M. A.; Croce, G.

    2016-09-01

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

  7. Heat Transfer of Nanofluid in a Double Pipe Heat Exchanger.

    PubMed

    Aghayari, Reza; Maddah, Heydar; Zarei, Malihe; Dehghani, Mehdi; Kaskari Mahalle, Sahar Ghanbari

    2014-01-01

    This paper investigates the enhancement of heat transfer coefficient and Nusselt number of a nanofluid containing nanoparticles (γ-AL2O3) with a particle size of 20 nm and volume fraction of 0.1%-0.3% (V/V). Effects of temperature and concentration of nanoparticles on Nusselt number changes and heat transfer coefficient in a double pipe heat exchanger with counter turbulent flow are investigated. Comparison of experimental results with valid theoretical data based on semiempirical equations shows an acceptable agreement. Experimental results show a considerable increase in heat transfer coefficient and Nusselt number up to 19%-24%, respectively. Also, it has been observed that the heat transfer coefficient increases with the operating temperature and concentration of nanoparticles.

  8. Heat Transfer of Nanofluid in a Double Pipe Heat Exchanger

    PubMed Central

    Aghayari, Reza; Maddah, Heydar; Zarei, Malihe; Dehghani, Mehdi; Kaskari Mahalle, Sahar Ghanbari

    2014-01-01

    This paper investigates the enhancement of heat transfer coefficient and Nusselt number of a nanofluid containing nanoparticles (γ-AL2O3) with a particle size of 20 nm and volume fraction of 0.1%–0.3% (V/V). Effects of temperature and concentration of nanoparticles on Nusselt number changes and heat transfer coefficient in a double pipe heat exchanger with counter turbulent flow are investigated. Comparison of experimental results with valid theoretical data based on semiempirical equations shows an acceptable agreement. Experimental results show a considerable increase in heat transfer coefficient and Nusselt number up to 19%–24%, respectively. Also, it has been observed that the heat transfer coefficient increases with the operating temperature and concentration of nanoparticles. PMID:27433521

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

    DOEpatents

    Huebotter, Paul R.; McLennan, George A.

    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.

  10. 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.

  11. Multi-Purpose Logistics Module (MPLM) Cargo Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Zampiceni, John J.; Harper, Lon T.

    2002-01-01

    This paper describes the New Shuttle Orbiter's Multi- Purpose Logistics Modulo (MPLM) Cargo Heat Exchanger (HX) and associated MPLM cooling system. This paper presents Heat Exchanger (HX) design and performance characteristics of the system.

  12. 1-MWe heat exchangers for OTEC. Final acceptance document

    SciTech Connect

    Snyder, J.E.

    1980-06-19

    Acceptance documents for major units of 1 MWe OTEC heat exchangers, including condensers and evaporators, are provided. Included are a transportation plan for the heat exchangers and design specifications for the phase separator. (LEW)

  13. Thermal induced flow oscillations in heat exchangers for supercritical fluids

    NASA Technical Reports Server (NTRS)

    Friedly, J. C.; Manganaro, J. L.; Krueger, P. G.

    1972-01-01

    Analytical model has been developed to predict possible unstable behavior in supercritical heat exchangers. From complete model, greatly simplified stability criterion is derived. As result of this criterion, stability of heat exchanger system can be predicted in advance.

  14. Multi-Purpose Logistics Module (MPLM) Cargo Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Zampiceni, John J.; Harper, Lon T.

    2002-01-01

    This paper describes the New Shuttle Orbiter's Multi- Purpose Logistics Modulo (MPLM) Cargo Heat Exchanger (HX) and associated MPLM cooling system. This paper presents Heat Exchanger (HX) design and performance characteristics of the system.

  15. Laser Processed Condensing Heat Exchanger Technology Development

    NASA Technical Reports Server (NTRS)

    Hansen, Scott; Wright, Sarah; Wallace, Sarah; Hamilton, Tanner; Dennis, Alexander; Zuhlke, Craig; Roth, Nick; Sanders, John

    2017-01-01

    The reliance on non-permanent coatings in Condensing Heat Exchanger (CHX) designs is a significant technical issue to be solved before long-duration spaceflight can occur. Therefore, high reliability CHXs have been identified by the Evolvable Mars Campaign (EMC) as critical technologies needed to move beyond low earth orbit. The Laser Processed Condensing Heat Exchanger project aims to solve these problems through the use of femtosecond laser processed surfaces, which have unique wetting properties and potentially exhibit anti-microbial growth properties. These surfaces were investigated to identify if they would be suitable candidates for a replacement CHX surface. Among the areas researched in this project include microbial growth testing, siloxane flow testing in which laser processed surfaces were exposed to siloxanes in an air stream, and manufacturability.

  16. 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.

  17. Analysis of the heat transfer in double and triple concentric tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Rădulescu, S.; Negoiţă, L. I.; Onuţu, I.

    2016-08-01

    The tubular heat exchangers (shell and tube heat exchangers and concentric tube heat exchangers) represent an important category of equipment in the petroleum refineries and are used for heating, pre-heating, cooling, condensation and evaporation purposes. The paper presents results of analysis of the heat transfer to cool a petroleum product in two types of concentric tube heat exchangers: double and triple concentric tube heat exchangers. The cooling agent is water. The triple concentric tube heat exchanger is a modified constructive version of double concentric tube heat exchanger by adding an intermediate tube. This intermediate tube improves the heat transfer by increasing the heat area per unit length. The analysis of the heat transfer is made using experimental data obtained during the tests in a double and triple concentric tube heat exchanger. The flow rates of fluids, inlet and outlet temperatures of water and petroleum product are used in determining the performance of both heat exchangers. Principally, for both apparatus are calculated the overall heat transfer coefficients and the heat exchange surfaces. The presented results shows that triple concentric tube heat exchangers provide better heat transfer efficiencies compared to the double concentric tube heat exchangers.

  18. Heat-Exchanger Computational Procedure For Temperature-Dependent Fouling

    NASA Technical Reports Server (NTRS)

    Chiappetta, L.; Szetela, E.

    1985-01-01

    Computer program predicts heat-exchanger performance under variety of conditions. Program provides rapid means of calculating distribution of fluid and wall temperatures, fuel deposit formation, and pressure losses at various locations in heat exchanger. Developed for use with heat exchanger that vaporizes fuel prior to fuel ignition; other applications possible.

  19. Heat exchanger support apparatus in a fluidized bed

    DOEpatents

    Lawton, Carl W.

    1982-01-01

    A heat exchanger is mounted in the upper portion of a fluidized combusting bed for the control of the temperature of the bed. A support, made up of tubes, is extended from the perforated plate of the fluidized bed up to the heat exchanger. The tubular support framework for the heat exchanger has liquid circulated therethrough to prevent deterioration of the support.

  20. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... subpart shall monitor each heat exchange system used to cool process equipment in an affected source... normal range. (5) The recirculating heat exchange system is used to cool process fluids that contain less...-through heat exchange system is used to cool process fluids that contain less than 5 percent by weight of...

  1. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Heat exchange systems provisions. 63... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1328 Heat exchange... of this subpart. (h) The compliance date for heat exchange systems subject to the provisions of this...

  2. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  3. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 29.1125 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger...

  4. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Heat exchanger provisions. 63.1435... Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63.1435 Heat exchanger... for heat exchange systems, with the exceptions noted in paragraphs (b) through (e) of this section. (b...

  5. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 25.1125 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger...

  6. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Exhaust heat exchangers. 29.1125 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger...

  7. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  8. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Exhaust heat exchangers. 25.1125 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger...

  9. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Heat exchanger provisions. 63.1435....1435 Heat exchanger provisions. (a) The owner or operator of each affected source shall comply with the requirements of § 63.104 for heat exchange systems, with the exceptions noted in paragraphs (b) through (e) of...

  10. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Exhaust heat exchangers. 29.1125 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger...

  11. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Exhaust heat exchangers. 25.1125 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger...

  12. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Heat exchanger provisions. 63.1435... Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63.1435 Heat exchanger... for heat exchange systems, with the exceptions noted in paragraphs (b) through (e) of this section. (b...

  13. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Heat exchange systems. 63.654 Section... Emission Standards for Hazardous Air Pollutants From Petroleum Refineries § 63.654 Heat exchange systems. (a) Except as specified in paragraph (b) of this section, the owner or operator of a heat exchange...

  14. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Exhaust heat exchangers. 29.1125 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger...

  15. 40 CFR 63.1435 - Heat exchanger provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 12 2012-07-01 2011-07-01 true Heat exchanger provisions. 63.1435... Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63.1435 Heat exchanger... for heat exchange systems, with the exceptions noted in paragraphs (b) through (e) of this section. (b...

  16. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Heat exchange systems provisions. 63... Heat exchange systems provisions. (a) Except as specified in paragraph (b) of this section, each owner... § 63.1335(e)(6), for the purposes of this subpart. (h) The compliance date for heat exchange systems...

  17. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Exhaust heat exchangers. 25.1125 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger...

  18. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 12 2012-07-01 2011-07-01 true Heat exchange systems provisions. 63... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1328 Heat exchange... of this subpart. (h) The compliance date for heat exchange systems subject to the provisions of this...

  19. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Heat exchange systems provisions. 63... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1328 Heat exchange... of this subpart. (h) The compliance date for heat exchange systems subject to the provisions of this...

  20. 14 CFR 29.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Exhaust heat exchangers. 29.1125 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger...

  1. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  2. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  3. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  4. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Exhaust heat exchangers. 25.1125 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger...

  5. A heat transfer model of a horizontal ground heat exchanger

    NASA Astrophysics Data System (ADS)

    Mironov, R. E.; Shtern, Yu. I.; Shtern, M. Yu.; Rogachev, M. S.

    2016-04-01

    Ground-source heat pumps are gaining popularity in Eastern Europe, especially those which are using the horizontal ground heat exchanger (GHX). Due to the difficulty of accessing GHX after the installation, materials and the quality of the installation must satisfy the very high requirements. An inaccurate calculation of GHX can be the reason of a scarcity of heat power in a crucial moment. So far, there isn't any appropriate mathematical description of the horizontal GHX which takes into account the mutual influence of GHX pipes on each other. To solve this problem we used the temperature wave approach. As a result, a mathematical model which describes the dependence of the heat transfer rate per unit length of the horizontal GHX pipe on the thermal properties of soil, operating time of GHX and the distance between pipes was obtained. Using this model, heat transfer rates per unit length of a horizontal GHX were plotted as functions of the distance between pipes and operating time. The modeling shows that heat transfer rates decreases rapidly with the distance between pipes lower then 2 meters. After the launch of heat pump, heat power of GHX is reduced during the first 20 - 30 days and get steady after that. The obtained results correlate with experimental data. Therefore the proposed mathematical model can be used to design a horizontal GHX with the optimal characteristics, and predict its capability during operation.

  6. Earth-type heat exchanger for heat pump systems

    SciTech Connect

    Bingham, G.A.

    1986-02-18

    This patent describes a heat pump heating and/or cooling system containing freon-type fluid. The system includes above-ground components and an earth-type heat exchanger unit disposed during use of the system entirely below ground level. The improvement described includes a cylindrical coil assembly having cylindrical fluid-conducting coils extending in substantially concentric relationship to each other about the central axis of the assembly. Each of the coils is formed of heat conductive and corrosion resistant tubing. The tubing of each coil is of different diameter than the tubing of each other coil; a conduit interconnects the coil assembly and the above-ground system components, during operation of the system, conducting the fluid to and from fluid-conducting coils of the assembly.

  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

  8. OXIDE DISPERSION-STRENGTHENED HEAT EXCHANGER TUBING

    SciTech Connect

    Harper, Mark A.

    2001-11-06

    Oxide dispersion strengthened (ODS) alloys (e.g. the INCOLOY{reg_sign} MA956 alloy) are known for their excellent high temperature properties and are prime candidate materials for the construction of very high temperature heat exchangers that will be used in Vision 21 power plants. The main limitation of these materials is their poor weldability. Commercially available ODS tubing also tends to exhibit relatively poor circumferential creep strength due to current processing practices resulting in a fine grain size in the transverse direction. Thus far, these two characteristics of the ODS tubing have restricted its use to mostly non-pressure containing applications. The objectives of this program are to develop: (a) an MA956 tube with sufficient circumferential creep strength for long term use as heat exchanger tubing for very high temperatures; (b) a welding technique(s) for producing adequate joints between an MA956 tube and an MA956 tube, and an MA956 tube and an INCONEL 601 tube; (c) the bending strain limits, below which recrystallization will not occur in a MA956 tube during normal operation; and (d) the high temperature corrosion limits for the MA956 alloy with respect to working-fluid side and fireside environments. Also, this program seeks to generate data for use by heat exchanger designers and the ASME Boiler and Pressure Vessel Code, and perform an analysis of the mechanical property, tube bending, and corrosion data in order to determine the implications on the design of a very high temperature heat exchanger (T>1093 C/2000 F). After one year, work is currently being conducted on increasing the circumferential strength of a MA956 tube, developing joining techniques for this material, determining the tube bending strain limits, and establishing the high temperature corrosion parameters for the MA956 alloy in environments expected to be present in Vision 21 power plants. Work in these areas will is continuing into the next fiscal year, with success

  9. Heat exchanger life extension via in-situ reconditioning

    DOEpatents

    Holcomb, David E.; Muralidharan, Govindarajan

    2016-06-28

    A method of in-situ reconditioning a heat exchanger includes the steps of: providing an in-service heat exchanger comprising a precipitate-strengthened alloy wherein at least one mechanical property of the heat exchanger is degraded by coarsening of the precipitate, the in-service heat exchanger containing a molten salt working heat exchange fluid; deactivating the heat exchanger from service in-situ; in a solution-annealing step, in-situ heating the heat exchanger and molten salt working heat exchange fluid contained therein to a temperature and for a time period sufficient to dissolve the coarsened precipitate; in a quenching step, flowing the molten salt working heat-exchange fluid through the heat exchanger in-situ to cool the alloy and retain a supersaturated solid solution while preventing formation of large precipitates; and in an aging step, further varying the temperature of the flowing molten salt working heat-exchange fluid to re-precipitate the dissolved precipitate.

  10. Comparison of different kinds of compact crossflow heat exchangers

    NASA Astrophysics Data System (ADS)

    Siemens, Werner

    1988-03-01

    A computer program for the calculation of compact heat exchangers for gas turbines was developed. The most important coefficients, pressure drops, and effectiveness of different kinds of exchangers were calculated as a function of Mach number, the dimensions of the exchanger, and the compactness. From the aerothermodynamic point of view, the plate exchanger is best, closely followed by the lancet heat exchanger. The ribs of the plate version have no significant effect on the characteristics, but are required for stiffness and uniform channel height. The tube heat exchanger can only compete as far as the transferable heat is concerned.

  11. Comparison of different kinds of compact cross flow heat exchangers

    NASA Astrophysics Data System (ADS)

    Siemens, Werner

    1986-09-01

    A computer program for the calculation of compact heat exchangers for gas turbines was developed. The most important coefficients, pressure drops, and effectiveness of different kinds of exchangers were calculated as a function of Mach number, the dimensions of the exchanger, and the compactness. From the aerothermodynamic point of view, the plate exchanger is best, closely followed by the lancet heat exchanger. The ribs of the plate version have no significant effect on the characteristics, but are required for stiffness and uniform channel height. The tube heat exchanger can only compete as far as the transferable heat is concerned.

  12. Microchannel Heat Exchangers with Carbon Dioxide

    SciTech Connect

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

    2001-09-15

    The objective of the present study was to determine the performance of CO{sub 2} 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 conditions corresponded to the typical operating conditions of residential heat pumps. In addition, a second set of commercial microchannel evaporators and gas coolers was tested for a less comprehensive range of operating conditions. The test results were reduced and a comprehensive data analysis, including comparison with the previous studies in this field, was performed. Capacity and pressure drop of the evaporator and gas cooler for the range of parameters studied were analyzed and are documented in this report. A gas cooler performance prediction model based on non-dimensional parameters was also developed and results are discussed as well. In addition, in the present study, experiments were conducted to evaluate capacities and pressure drops for sub-critical CO{sub 2} flow boiling and transcritical CO{sub 2} gas cooling in microchannel heat exchangers. An extensive review of the literature failed to indicate any previous systematic study in this area, suggesting a lack of fundamental understanding of the phenomena and a lack of comprehensive data that would quantify the performance potential of CO{sub 2} microchannel heat exchangers for the application at hand. All experimental tests were successfully conducted with an energy balance within {+-}3%. The only exceptions to this were experiments at very low saturation temperatures (-23 C), where energy balances were as high as 10%. In the case of evaporators, it was found that a lower saturation temperature (especially when moisture condensation occurs) improves the overall heat transfer coefficient

  13. Technology Solutions Case Study: Foundation Heat Exchanger, Oak Ridge, Tennessee

    SciTech Connect

    2014-03-01

    The foundation heat exchanger, developed by Oak Ridge National Laboratory, is a new concept for a cost-effective horizontal ground heat exchanger that can be connected to water-to-water or water-to-air heat pump systems for space conditioning as well as domestic water heating.

  14. Analytical and experimental analysis of tube coil heat exchanger

    NASA Astrophysics Data System (ADS)

    Smusz, R.

    2016-09-01

    The paper presents the analytical and experimental analysis of heat transfer for the finned tube coil heat exchanger immersed in thermal storage tank. The tank is equipped with three helical-shaped heating coils and cylindrical- shaped stratification device. Two coils, upper and lower, use the water as a heating medium. The third, double wall heat exchanger coil, located at the bottom head on the tank is filled by the refrigerant (freon). Calculations of thermal power of water coil were made. Correlations of heat transfer coefficients in curved tubes were applied. In order to verify the analytical calculations the experimental studies of heat transfer characteristic for coil heat exchanger were performed.

  15. Condensation in horizontal heat exchanger tubes

    SciTech Connect

    Leyer, S.; Zacharias, T.; Maisberger, F.; Lamm, M.; Vallee, C.; Beyer, M.; Hampel, U.

    2012-07-01

    Many innovative reactor concepts for Generation III nuclear power plants use passive safety equipment for residual heat removal. These systems use two phase natural circulation. Heat transfer to the coolant results in a density difference providing the driving head for the required mass flow. By balancing the pressure drop the system finds its operational mode. Therefore the systems depend on a strong link between heat transfer and pressure drop determining the mass flow through the system. In order to be able to analyze these kind of systems with the help of state of the art computer codes the implemented numerical models for heat transfer, pressure drop or two phase flow structure must be able to predict the system performance in a wide parameter range. Goal of the program is to optimize the numerical models and therefore the performance of computer codes analyzing passive systems. Within the project the heat transfer capacity of a heat exchanger tube will be investigated. Therefore the tube will be equipped with detectors, both temperature and pressure, in several directions perpendicular to the tube axis to be able to resolve the angular heat transfer. In parallel the flow structure of a two phase flow inside and along the tube will be detected with the help of x-ray tomography. The water cooling outside of the tube will be realized by forced convection. It will be possible to combine the flow structure measurement with an angular resolved heat transfer for a wide parameter range. The test rig is set up at the TOPLFOW facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), so that it will be possible to vary the pressure between 5 and 70 bar. The steam mass content will be varied between 0 and 100 percent. The results will be compared to the large scaled Emergency Condenser Tests performed at the INKA test facility in Karlstein (Germany). The paper will explain the test setup and the status of the project will be presented. (authors)

  16. Reliability analysis on a shell and tube heat exchanger

    NASA Astrophysics Data System (ADS)

    Lingeswara, S.; Omar, R.; Mohd Ghazi, T. I.

    2016-06-01

    A shell and tube heat exchanger reliability was done in this study using past history data from a carbon black manufacturing plant. The heat exchanger reliability study is vital in all related industries as inappropriate maintenance and operation of the heat exchanger will lead to major Process Safety Events (PSE) and loss of production. The overall heat exchanger coefficient/effectiveness (Uo) and Mean Time between Failures (MTBF) were analyzed and calculated. The Aspen and down time data was taken from a typical carbon black shell and tube heat exchanger manufacturing plant. As a result of the Uo calculated and analyzed, it was observed that the Uo declined over a period caused by severe fouling and heat exchanger limitation. This limitation also requires further burn out period which leads to loss of production. The MTBF calculated is 649.35 hours which is very low compared to the standard 6000 hours for the good operation of shell and tube heat exchanger. The guidelines on heat exchanger repair, preventive and predictive maintenance was identified and highlighted for better heat exchanger inspection and repair in the future. The fouling of heat exchanger and the production loss will be continuous if proper heat exchanger operation and repair using standard operating procedure is not followed.

  17. High-temperature self-circulating thermoacoustic heat exchanger

    NASA Astrophysics Data System (ADS)

    Backhaus, S.; Swift, G. W.; Reid, R. S.

    2005-07-01

    Thermoacoustic and Stirling engines and refrigerators use heat exchangers to transfer heat between the oscillating flow of their thermodynamic working fluids and external heat sources and sinks. An acoustically driven heat-exchange loop uses an engine's own pressure oscillations to steadily circulate its own thermodynamic working fluid through a physically remote high-temperature heat source without using moving parts, allowing for a significant reduction in the cost and complexity of thermoacoustic and Stirling heat exchangers. The simplicity and flexibility of such heat-exchanger loops will allow thermoacoustic and Stirling machines to access diverse heat sources and sinks. Measurements of the temperatures at the interface between such a heat-exchange loop and the hot end of a thermoacoustic-Stirling engine are presented. When the steady flow is too small to flush out the mixing chamber in one acoustic cycle, the heat transfer to the regenerator is excellent, with important implications for practical use.

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

    SciTech Connect

    G. K. Housley; J.E. O'Brien; G.L. Hawkes

    2008-11-01

    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 electrolysis module. The heat exchangers are mated to a base manifold unit that distributes the inlet and outlet flows to and from the four electrolysis stacks. Results of heat exchanger design calculations and assembly details are also presented.

  19. A heat exchanger computational procedure for temperature-dependent fouling

    NASA Technical Reports Server (NTRS)

    Chiappetta, L. M.; Szetela, E. J.

    1981-01-01

    A novel heat exchanger computational procedure is described which provides a means of rapidly calculating the distributions of fluid and wall temperatures, deposit formation, and pressure loss at various points in a heat exchanger. The procedure is unique in that it is capable of treating wide variations in heat exchanger geometry without recourse to restrictive assumptions concerning heat exchanger type (e.g., co-flow, counterflow, cross flow devices, etc.). The analysis has been used extensively to predict the performance of cross-counterflow heat exchangers in which one fluid behaves as a perfect gas (e.g., air) while the other fluid is assumed to be a distillate fuel. The model has been extended to include the effects on heat exchanger performance of time varying inflow conditions. Heat exchanger performance degradation due to deposit formation with time can be simulated, making this procedure useful in predicting the effects of temperature-dependent fouling.

  20. Shell-and-tube heat exchangers in refrigeration. Part 1

    SciTech Connect

    Cole, R.A.

    1996-12-01

    This article covers the basics of sizing and selecting shell-and-tube heat exchangers for refrigeration applications. The heat exchanger is an indispensable device in many instances where heat must be transferred from one fluid to another. Its use is necessary in many applications involving thermal energy transfer in both heating and cooling processes, and there are a variety of designs on the market. This article will focus on the shell-and-tube (S and T) type. While the ensuing discussion will deal with heat exchangers in this field, the discourse on shell-and-tube heat exchanger construction and operation is fundamental to all S and T applications.

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

    SciTech Connect

    Steinmeyer, D.

    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).

  2. Radiant heat exchange calculations in radiantly heated and cooled enclosures

    SciTech Connect

    Chapman, K.S.; Zhang, P.

    1995-08-01

    This paper presents the development of a three-dimensional mathematical model to compute the radiant heat exchange between surfaces separated by a transparent and/or opaque medium. The model formulation accommodates arbitrary arrangements of the interior surfaces, as well as arbitrary placement of obstacles within the enclosure. The discrete ordinates radiation model is applied and has the capability to analyze the effect of irregular geometries and diverse surface temperatures and radiative properties. The model is verified by comparing calculated heat transfer rates to heat transfer rates determined from the exact radiosity method for four different enclosures. The four enclosures were selected to provide a wide range of verification. This three-dimensional model based on the discrete ordinates method can be applied to a building to assist the design engineer in sizing a radiant heating system. By coupling this model with a convective and conductive heat transfer model and a thermal comfort model, the comfort levels throughout the room can be easily and efficiently mapped for a given radiant heater location. In addition, objects such as airplanes, trucks, furniture, and partitions can be easily incorporated to determine their effect on the performance of the radiant heating system.

  3. Flow losses in Stirling engine heat exchangers

    NASA Astrophysics Data System (ADS)

    Jones, J. D.

    1988-01-01

    In the present attempt to formulate closed-form expressions for the rapid and accurate calculation of crank-driven Stirling-cycle machines' pressure variation, flow velocities, and flow friction losses, compression and expansion spaces are assumed to be isothermal, with sinusoidally varying volumes. From the closed-form expressions deduced for the amplitude and phase of these variations, formulas are derived for friction losses in the three heat exchangers, taking into account the mass flow rate variation over the cycle and the variation in mass flow amplitude between the two ends of the regenerator.

  4. Characterization of various losses in a cryogenic counterflow heat exchanger

    NASA Astrophysics Data System (ADS)

    Aminuddin, Mohammad; Zubair, Syed M.

    2014-11-01

    A detailed assessment of irreversibility, predominantly heat in-leak and axial wall conduction, is essential in accurately predicting the performance of high effectiveness heat exchangers employed in cryogenic applications. Integration into a refrigeration system as well requires consideration of parasitic heat loss by conduction from exchanger cold end to the adjacent components. Governing equations incorporating these effects in a counterflow exchanger are solved numerically and the model predictions evaluated for heat exchanger ineffectiveness and heat loss by conduction. The optimum performance mandates minimization of both. Although ineffectiveness decreases at higher longitudinal conduction, cold end loss increases with deterioration of the overall performance. Utilizing lower heat capacity rate hot fluid, nevertheless, reduces the cold end loss. Heat in-leak is relatively high with concurrent consideration of axial wall conduction and has adverse consequence on heat exchanger effectiveness. Analysis of the net heat transferred to lower stages of refrigeration reveals a critical NTU.

  5. Aerodynamics of heat exchangers for high-altitude aircraft

    NASA Technical Reports Server (NTRS)

    Drela, Mark

    1996-01-01

    Reduction of convective beat transfer with altitude dictates unusually large beat exchangers for piston- engined high-altitude aircraft The relatively large aircraft drag fraction associated with cooling at high altitudes makes the efficient design of the entire heat exchanger installation an essential part of the aircraft's aerodynamic design. The parameters that directly influence cooling drag are developed in the context of high-altitude flight Candidate wing airfoils that incorporate heat exchangers are examined. Such integrated wing-airfoil/heat-exchanger installations appear to be attractive alternatives to isolated heat.exchanger installations. Examples are drawn from integrated installations on existing or planned high-altitude aircraft.

  6. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Heat exchange system provisions. 63... exchange system provisions. (a) Unless one or more of the conditions specified in paragraphs (a)(1) through... each heat exchange system used to cool process equipment in an affected source, according to the...

  7. BASIMO - Borehole Heat Exchanger Array Simulation and Optimization Tool

    NASA Astrophysics Data System (ADS)

    Schulte, Daniel; Rühaak, Wolfram; Welsch, Bastian; Bär, Kristian; Sass, Ingo

    2016-04-01

    Borehole heat exchangers represent a well-established technology, which pushes for new fields of applications and novel modifications. Current simulation tools cannot - or only to some extent - describe features like inclined or partly insulated boreholes unless they run fully discretized models of the borehole heat exchangers. However, fully discretized models often come at a high computational cost, especially for large arrays of borehole heat exchangers. We present a tool, which uses one dimensional thermal resistance and capacity models for the borehole heat exchangers coupled with a numerical finite element model for the subsurface heat transport. An unstructured tetrahedral mesh bypasses the limitations of structured grids for borehole path geometries, while the thermal resistance and capacity model is improved to account for borehole heat exchanger properties changing with depth. The presented tool benefits from the fast analytical solution of the thermal interactions within the boreholes while still allowing for a detailed consideration of the borehole heat exchanger properties.

  8. Shell-and-double concentric-tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Bougriou, Chérif; Baadache, Khireddine

    2010-03-01

    This study concerns a new type of heat exchangers, which is that of shell-and-double concentric-tube heat exchangers. These heat exchangers can be used in many specific applications such as air conditioning, waste heat recovery, chemical processing, pharmaceutical industries, power production, transport, distillation, food processing, cryogenics, etc. The case studies include both design calculations and performance calculations. It is demonstrated that the relative diameter sizes of the two tubes with respect to each other are the most important parameters that influence the heat exchanger size.

  9. Condensate removal device for heat exchanger

    NASA Technical Reports Server (NTRS)

    Trusch, R. B.; Oconnor, E. W. (Inventor)

    1975-01-01

    A set of perforated tubes disposed at the gas output side of a heat exchanger, in a position not to affect the rate of flow of the air or other gas is described. The tubes are connected to a common manifold which is connected to a sucking device. Where it is necessary to conserve and recirculate the air sucked through the tubes, the output of the manifold is run through a separator to remove the condensate from the gas. The perforations in the slurper tubes are small, lying in the range of 0.010 inch to 0.100 inch. The tubes are disposed in contact with the surfaces of the heat exchanger on which the condensate is precipitated, whether fins or plates, so that the water may be directed to the tube openings by means of surface effects, together with the assistance of the air flow. Only about 5 percent of the air output need be thus diverted, and it effectively removes virtually all of the condensate.

  10. Diffusion-Welded Microchannel Heat Exchanger for Industrial Processes

    SciTech Connect

    Piyush Sabharwall; Denis E. Clark; Michael V. Glazoff; Michael G. McKellar; Ronald E. Mizia

    2013-03-01

    The goal of next generation reactors is to increase energy ef?ciency in the production of electricity and provide high-temperature heat for industrial processes. The ef?cient transfer of energy for industrial applications depends on the ability to incorporate effective heat exchangers between the nuclear heat transport system and the industrial process. The need for ef?ciency, compactness, and safety challenge the boundaries of existing heat exchanger technology. Various studies have been performed in attempts to update the secondary heat exchanger that is downstream of the primary heat exchanger, mostly because its performance is strongly tied to the ability to employ more ef?cient industrial processes. Modern compact heat exchangers can provide high compactness, a measure of the ratio of surface area-to-volume of a heat exchange. The microchannel heat exchanger studied here is a plate-type, robust heat exchanger that combines compactness, low pressure drop, high effectiveness, and the ability to operate with a very large pressure differential between hot and cold sides. The plates are etched and thereafter joined by diffusion welding, resulting in extremely strong all-metal heat exchanger cores. After bonding, any number of core blocks can be welded together to provide the required ?ow capacity. This study explores the microchannel heat exchanger and draws conclusions about diffusion welding/bonding for joining heat exchanger plates, with both experimental and computational modeling, along with existing challenges and gaps. Also, presented is a thermal design method for determining overall design speci?cations for a microchannel printed circuit heat exchanger for both supercritical (24 MPa) and subcritical (17 MPa) Rankine power cycles.

  11. Experimental investigation of heat transfer and effectiveness in corrugated plate heat exchangers having different chevron angles

    NASA Astrophysics Data System (ADS)

    Kılıç, Bayram; İpek, Osman

    2017-02-01

    In this study, heat transfer rate and effectiveness of corrugated plate heat exchangers having different chevron angles were investigated experimentally. Chevron angles of plate heat exchangers are β = 30° and β = 60°. For this purpose, experimentally heating system used plate heat exchanger was designed and constructed. Thermodynamic analysis of corrugated plate heat exchangers having different chevron angles were carried out. The heat transfer rate and effectiveness values are calculated. The experimental results are shown that heat transfer rate and effectiveness values for β = 60° is higher than that of the other. Obtained experimental results were graphically presented.

  12. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Heat exchange systems. 63.654 Section... Emission Standards for Hazardous Air Pollutants From Petroleum Refineries § 63.654 Heat exchange systems. (a) Except as specified in paragraph (b) of this section, the owner or operator of a heat...

  13. A Project to Design and Build Compact Heat Exchangers

    ERIC Educational Resources Information Center

    Davis, Richard A.

    2005-01-01

    Students designed and manufactured compact, shell-and-tube heat exchangers in a project-based learning exercise integrated with our heat transfer course. The heat exchangers were constructed from common building materials available at home improvement centers. The cost of materials for a device was less than $20. The project gave students…

  14. A Project to Design and Build Compact Heat Exchangers

    ERIC Educational Resources Information Center

    Davis, Richard A.

    2005-01-01

    Students designed and manufactured compact, shell-and-tube heat exchangers in a project-based learning exercise integrated with our heat transfer course. The heat exchangers were constructed from common building materials available at home improvement centers. The cost of materials for a device was less than $20. The project gave students…

  15. Heat exchanger for fuel cell power plant reformer

    DOEpatents

    Misage, Robert; Scheffler, Glenn W.; Setzer, Herbert J.; Margiott, Paul R.; Parenti, Jr., Edmund K.

    1988-01-01

    A heat exchanger uses the heat from processed fuel gas from a reformer for a fuel cell to superheat steam, to preheat raw fuel prior to entering the reformer and to heat a water-steam coolant mixture from the fuel cells. The processed fuel gas temperature is thus lowered to a level useful in the fuel cell reaction. The four temperature adjustments are accomplished in a single heat exchanger with only three heat transfer cores. The heat exchanger is preheated by circulating coolant and purge steam from the power section during startup of the latter.

  16. Symposium on Condensing Heat Exchangers. Volume 2: Proceedings

    NASA Astrophysics Data System (ADS)

    1982-03-01

    Heat exchangers designed to recover a portion of the latent heat of the water vapor formed in the combustion process are discussed. They are applicable to equipment fired by either conventional power burners or pulse-combustion systems. Heat exchanger concepts and performance, corrosion resistant materials, condensate disposal, venting of flue gases and codes and standards are considered. Applications include use of condensing heat exchangers in conjunction with furnaces for space heating, and also with boilers for generation of steam or hot water for use in space heating or industrial processing.

  17. Entrance-length dendritic plate heat exchangers

    DOE PAGES

    Bejan, A.; Alalaimi, M.; Sabau, A. S.; ...

    2017-07-17

    We explore the idea that the highest heat transfer rate between two fluids in a given volume is achieved when plate channel lengths are given by the thermal entrance length, i.e., when the thermal boundary layers meet at the exit of each channel. The overall design can be thought of an elemental construct of a dendritic heat exchanger, which consists of two tree-shaped streams arranged in cross flow. Every channel is as long as the thermal entrance length of the developing flow that resides in that channel. The results indicate that the overall design will change with the total volumemore » and total number of channels. We found that the lengths of the surfaces swept in cross flow would have to decrease sizably as number of channels increases, while exhibiting mild decreases as total volume increases. The aspect ratio of each surface swept by fluid in cross flow should be approximately square, independent of total number of channels and volume. We also found that the minimum pumping power decreases sensibly as the total number of channels and the volume increase. FurtherThe maximized heat transfer rate per unit volume increases sharply as the total volume decreases, in agreement with the natural evolution toward miniaturization in technology.« less

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

    DOEpatents

    Koplow, Jeffrey P.

    2016-02-16

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

  19. 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

    2016-04-01

    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.

  20. Heat exchanger and water tank arrangement for passive cooling system

    DOEpatents

    Gillett, James E.; Johnson, F. Thomas; Orr, Richard S.; Schulz, Terry L.

    1993-01-01

    A water storage tank in the coolant water loop of a nuclear reactor contains a tubular heat exchanger. The heat exchanger has tubesheets mounted to the tank connections so that the tubesheets and tubes may be readily inspected and repaired. Preferably, the tubes extend from the tubesheets on a square pitch and then on a rectangular pitch therebetween. Also, the heat exchanger is supported by a frame so that the tank wall is not required to support all of its weight.

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

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Hertzberg, A.

    1982-01-01

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

  2. Sintered Lining for Heat-Pipe Evaporator

    NASA Technical Reports Server (NTRS)

    Ernst, D. M.; Eastman, G. Y.

    1985-01-01

    Hotspots eliminated by lining inner wall. Distribution of heat transfer liquid in heat-pipe evaporator improved by lining inner wall with layer of sintered metal. Sintered layer takes place of layer of screen wick formerly sintered or bonded to wall. Since sintered layer always full of liquid, no hotspot of type that previously arose where former screen wick did not fit properly against wall.

  3. DEVELOPMENT OF ODS HEAT EXCHANGER TUBING

    SciTech Connect

    Mark A. Harper, Ph.D.

    2001-01-01

    The Vision 21 project titled ''Development of ODS Heat Exchanger Tubing'' has been initiated. A project kick-off meeting was held in Huntington, WV, the MA956 powder that will be used in the extrusion campaign has been obtained, and some of the MA956 tubing and rod required for joining trials has been shipped to the appropriate subcontractors. Acquisition of the MA956 alloy powder will allow the extrusion campaign to begin during the month of February. Also, tubing shipped to Edison Welding Institute and rod shipped to Michigan Technological University will allow joining trials to begin. In addition to these technical aspects, negotiations with all the subcontractors have been completed and the Project Management Plan and Project Work Plan have been prepared and submitted for approval.

  4. Condensing Heat Exchanger with Hydrophilic Antimicrobial Coating

    NASA Technical Reports Server (NTRS)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor)

    2014-01-01

    A multi-layer antimicrobial hydrophilic coating is applied to a substrate of anodized aluminum, although other materials may form the substrate. A silver layer is sputtered onto a thoroughly clean anodized surface of the aluminum to about 400 nm thickness. A layer of crosslinked, silicon-based macromolecular structure about 10 nm thickness overlies the silver layer, and the outermost surface of the layer of crosslinked, silicon-based macromolecular structure is hydroxide terminated to produce a hydrophilic surface with a water drop contact angle of less than 10.degree.. The coated substrate may be one of multiple fins in a condensing heat exchanger for use in the microgravity of space, which has narrow channels defined between angled fins such that the surface tension of condensed water moves water by capillary flow to a central location where it is pumped to storage. The antimicrobial coating prevents obstruction of the capillary passages.

  5. Improved ceramic heat exchanger materials. Final report

    SciTech Connect

    Rauch, H.W. Sr.; McCreight, L.R.

    1980-12-01

    Numerous compositions were developed and evaluated for potential application as heat exchanger structures in automotive gas turbine engines. Test specimens were evaluated for thermal expansion and dimensional stability before and after exposure to sea salt and sulfuric acid, followed by thermal cycling up to 1200/sup 0/C. Materials which survived the screening tests were considered for fabrication into honeycomb form. The material finally selected, GE-7808, consists of the oxides, ZrO/sub 2/-MgO-Al/sub 2/O/sub 3/-SiO/sub 2/, and is described generically as ZrMAS. The original version on which the primary work was done was based on a commercially available cordierite (MAS) frit. Late in the program, however a clay/talc mixture was demonstrated to be a satisfactory very low cost source of the cordierite (MAS) phase. Several full size honeycomb regenerator cores, about 10.2 cm thick and 55 cm dia were fabricated from both the frit and mineral versions of GE-7808. The honeycomb cells in these cores had rectangular dimensions of about 0.5 mm x 2.5 mm and a wall thickness of approximately 0.2 mm (0.008''). Test specimens cut from the cores were evaluated. The multi-phase materials developed in this program demonstrated that their refractoriness and rheological behavior enabled them to retain shape and orientation of the gas passages parallel to the axis much better than some single phase (glass ceramic) materials. The test data show that GE-7808 is significantly more stable at 1100/sup 0/C in the presence of sodium than the Corning 9460 aluminosilicate reference materials.Overall assessment of GE-7808 properties, ease of material preparation, noncritical materials utilized and ready adaptability to honeycomb fabrication qualify this new material as a candidate for heat exchanger applications in automotive gas turbine engines.

  6. Thermal Propulsion Capture System Heat Exchanger Design

    NASA Technical Reports Server (NTRS)

    Richard, Evan M.

    2016-01-01

    One of the biggest challenges of manned spaceflight beyond low earth orbit and the moon is harmful radiation that astronauts would be exposed to on their long journey to Mars and further destinations. Using nuclear energy has the potential to be a more effective means of propulsion compared to traditional chemical engines (higher specific impulse). An upper stage nuclear engine would allow astronauts to reach their destination faster and more fuel efficiently. Testing these engines poses engineering challenges due to the need to totally capture the engine exhaust. The Thermal Propulsion Capture System is a concept for cost effectively and safely testing Nuclear Thermal Engines. Nominally, hydrogen exhausted from the engine is not radioactive, but is treated as such in case of fuel element failure. The Thermal Propulsion Capture System involves injecting liquid oxygen to convert the hydrogen exhaust into steam. The steam is then cooled and condensed into liquid water to allow for storage. The Thermal Propulsion Capture System concept for ground testing of a nuclear powered engine involves capturing the engine exhaust to be cooled and condensed before being stored. The hydrogen exhaust is injected with liquid oxygen and burned to form steam. That steam must be cooled to saturation temperatures before being condensed into liquid water. A crossflow heat exchanger using water as a working fluid will be designed to accomplish this goal. Design a cross flow heat exchanger for the Thermal Propulsion Capture System testing which: Eliminates the need for water injection cooling, Cools steam from 5800 F to saturation temperature, and Is efficient and minimizes water requirement.

  7. Advanced heat exchanger development for molten salts

    DOE PAGES

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; ...

    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 <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.« less

  8. Advanced heat exchanger development for molten salts

    SciTech Connect

    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 material 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 <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  9. Thermal and economic analysis of plastic heat exchangers for solar water heating

    SciTech Connect

    Liu, W.; Davidson, J.; Raman, R.; Mantell, S.

    1999-07-01

    The feasibility of polymer heat exchangers for solar water heaters is examined in terms of thermal performance and cost of tube-in-shell and immersed designs. High temperature nylon and cross-linked polyethylene were identified as suitable polymers for this application. These materials can meet the high temperature and pressure requirements of a domestic potable hot water system. The heat exchanger designs are compared for heat transfer area required to provide 3,000 and 6,000 W. A nylon tube-in-shell heat exchanger, sized for a 3,000 W load, is approximately 80% of the cost of a copper tube-in-shell heat exchanger. For an immersed heat exchanger, a high temperature nylon tube bank design has the lowest cost. The nylon tube bank heat exchanger, sized for a 3,000 W load, is approximately 80% the cost of an immersed coiled copper tube heat exchanger.

  10. Protective coating for copper in aluminum heat exchangers

    NASA Technical Reports Server (NTRS)

    Avazian, R.

    1978-01-01

    Application of ultrathin layer of molybdenum disulfied coating to copper tubing permits utilization of tubing in cast-aluminum heat exchangers. Coating prevents formation of copper/aluminum eutectic, but does not impede heat transfer.

  11. Matrix heat exchanger including a liquid, thermal couplant

    DOEpatents

    Fewell, Thomas E.; Ward, Charles T.

    1976-01-01

    A tube-to-tube heat exchanger is disclosed with a thermally conductive matrix between and around the tubes to define annuli between the tubes and matrix. The annuli are filled to a level with a molten metal or alloy to provide a conductive heat transfer path from one tube through the matrix to the second tube. A matrix heat exchanger of this type is particularly useful for heat transfer between fluids which would react should one leak into the second.

  12. Superphenix 1 intermediate heat exchanger fabrication

    SciTech Connect

    Noel, H.; Granito, F.; Pouderoux, P.

    1985-02-01

    The eight Superphenix 375-MW (thermal) intermediate heat exchangers (IHXs) are similar in overall design to the Phenix components. Detailed design changes had to be made during fabrication on the following grounds: Due to seismic resistance, the support area was raised as high as possible to situate the component natural frequencies well out of the resonance peak range and remove thick plate-to-shell connections from heavy thermal load areas. Integration of lessons drawn from the Phenix incidents, due mainly to secondary sodium radial temperature disparities, resulted in the design of a more adaptable outlet header, together with a sodium mixing device, and in the reduction of temperature differences by heat insulation. To avoid circumferential temperature disparities, the iron shot biological shielding plug was replaced by stacked stainless steel plates within an outer shell, which in the new design, is not a supporting structure. The thermal-hydraulic and mechanical design of the component necessitated the elaboration of sophisticated computer codes, with validation of results on mock-ups. The detailed design studies and the actual manufacturing work had to adapt to both design developments and to inherent fabrication difficulties, mainly related to the very tight tolerances imposed for these exceptionally large components and to the welding of steel with an excessive boron content. The construction of the Creys-Malville IHXs afforded valuable industrial experience, which should provide a basis for the design of simpler and less costly IHX units for the forthcoming 1500-MW (electric) breeder.

  13. Combined Steady-State and Dynamic Heat Exchanger Experiment

    ERIC Educational Resources Information Center

    Luyben, William L.; Tuzla, Kemal; Bader, Paul N.

    2009-01-01

    This paper describes a heat-transfer experiment that combines steady-state analysis and dynamic control. A process-water stream is circulated through two tube-in-shell heat exchangers in series. In the first, the process water is heated by steam. In the second, it is cooled by cooling water. The equipment is pilot-plant size: heat-transfer areas…

  14. Combined Steady-State and Dynamic Heat Exchanger Experiment

    ERIC Educational Resources Information Center

    Luyben, William L.; Tuzla, Kemal; Bader, Paul N.

    2009-01-01

    This paper describes a heat-transfer experiment that combines steady-state analysis and dynamic control. A process-water stream is circulated through two tube-in-shell heat exchangers in series. In the first, the process water is heated by steam. In the second, it is cooled by cooling water. The equipment is pilot-plant size: heat-transfer areas…

  15. A Liquid-Liquid Thermoelectric Heat Exchanger as a Heat Pump for Testing Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Makinen, Janice; Le, Hung V.

    2016-01-01

    The primary objective of the Phase Change HX payload on the International Space Station (ISS) is to test and demonstrate the viability and performance of Phase Change Material Heat Exchangers (PCM HX). The system was required to pump a working fluid through a PCM HX to promote the phase change material to freeze and thaw as expected on Orion's Multipurpose Crew Vehicle. Due to limitations on ISS's Internal Thermal Control System, a heat pump was needed on the Phase Change HX payload to help with reducing the working fluid's temperature to below 0degC (32degF). This paper will review the design and development of a TEC based liquid-liquid heat exchanger as a way to vary to fluid temperature for the freeze and thaw phase of the PCM HX. Specifically, the paper will review the design of custom coldplates and sizing for the required heat removal of the HX.

  16. Universal Monitor (UM) for OTEC compact heat exchangers

    SciTech Connect

    Kuzay, T.M.

    1981-09-01

    Universal Monitor (UM), is a device-independent concept to measure, with precision, the initiation and progression of fouling in any given OTEC Compact Heat Exchanger model with or without the application of countermeasures. Design description and supporting analyses for the Universal Monitor for OTEC Compact Heat Exchangers are presented.

  17. Heat transfer analysis of underground U-type heat exchanger of ground source heat pump system.

    PubMed

    Pei, Guihong; Zhang, Liyin

    2016-01-01

    Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions of a continuous and intermittent operation over 7 days on a GSHP with a single-well, single-U and double-U heat exchanger and the impact of single-U and double-U buried heat pipes on the surrounding rock-soil temperature field and the impact of intermittent operation and continuous operation on the outlet water temperature. The influence on the rock-soil temperature is approximately 13 % higher for the double-U heat exchanger than that of the single-U heat exchanger. The extracted energy of the intermittent operation is 36.44 kw·h higher than that of the continuous mode, although the running time is lower than that of continuous mode, over the course of 7 days. The thermal interference loss and quantity of heat exchanged for unit well depths at steady-state condition of 2.5 De, 3 De, 4 De, 4.5 De, 5 De, 5.5 De and 6 De of sidetube spacing are detailed in this work. The simulation results of seven working conditions are compared. It is recommended that the side-tube spacing of double-U underground pipes shall be greater than or equal to five times of outer diameter (borehole diameter: 180 mm).

  18. Cyclic high temperature heat storage using borehole heat exchangers

    NASA Astrophysics Data System (ADS)

    Boockmeyer, Anke; Delfs, Jens-Olaf; Bauer, Sebastian

    2016-04-01

    The transition of the German energy supply towards mainly renewable energy sources like wind or solar power, termed "Energiewende", makes energy storage a requirement in order to compensate their fluctuating production and to ensure a reliable energy and power supply. One option is to store heat in the subsurface using borehole heat exchangers (BHEs). Efficiency of thermal storage is increasing with increasing temperatures, as heat at high temperatures is more easily injected and extracted than at temperatures at ambient levels. This work aims at quantifying achievable storage capacities, storage cycle times, injection and extraction rates as well as thermal and hydraulic effects induced in the subsurface for a BHE storage site in the shallow subsurface. To achieve these aims, simulation of these highly dynamic storage sites is performed. A detailed, high-resolution numerical simulation model was developed, that accounts for all BHE components in geometrical detail and incorporates the governing processes. This model was verified using high quality experimental data and is shown to achieve accurate simulation results with excellent fit to the available experimental data, but also leads to large computational times due to the large numerical meshes required for discretizing the highly transient effects. An approximate numerical model for each type of BHE (single U, double U and coaxial) that reduces the number of elements and the simulation time significantly was therefore developed for use in larger scale simulations. The approximate numerical model still includes all BHE components and represents the temporal and spatial temperature distribution with a deviation of less than 2% from the fully discretized model. Simulation times are reduced by a factor of ~10 for single U-tube BHEs, ~20 for double U-tube BHEs and ~150 for coaxial BHEs. This model is then used to investigate achievable storage capacity, injection and extraction rates as well as induced effects for

  19. Circulating heat exchangers for oscillating wave engines and refrigerators

    DOEpatents

    Swift, Gregory W.; Backhaus, Scott N.

    2003-10-28

    An oscillating-wave engine or refrigerator having a regenerator or a stack in which oscillating flow of a working gas occurs in a direction defined by an axis of a trunk of the engine or refrigerator, incorporates an improved heat exchanger. First and second connections branch from the trunk at locations along the axis in selected proximity to one end of the regenerator or stack, where the trunk extends in two directions from the locations of the connections. A circulating heat exchanger loop is connected to the first and second connections. At least one fluidic diode within the circulating heat exchanger loop produces a superimposed steady flow component and oscillating flow component of the working gas within the circulating heat exchanger loop. A local process fluid is in thermal contact with an outside portion of the circulating heat exchanger loop.

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

    DOEpatents

    Drake, Richard L.

    1993-01-01

    A heat exchanger 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.

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

    NASA Technical Reports Server (NTRS)

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

    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 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.

  2. 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.

  3. SIMULATION OF BOILING HEAT TRANSFER AROUND MICRO PIN-FIN HEAT EXCHANGER: PROGRESS AND CHALLENGES

    SciTech Connect

    Tyagi, M.; Maha, A.; Singh, K. V.; Li, G.; and Pang, S.S.

    2006-07-01

    Boiling at microscales is a challenging problem for the computational models as well as the resources. During boiling, the formation and departure of vapor bubbles from the heated surface involves the physics from nano/micro level to the macro level. Therefore, a hierarchical methodology is needed to incorporate the nano/microscale physics with the macroscale system performance. Using micro-fabrication techniques, microstructures (micropin-fins) can be fabricated around the tubes in the heat exchanger of Pressurized Water Reactors (PWRs) to increase the heat-exchanging efficiency and reduce the overall size of the heat-exchanger for the given heat transfer rates. Combined with high fidelity simulations of the thermal transport in the entire system, optimal design of microstructure patterns and layouts can be worked out pragmatically. Properly patterned microstructures on the pipe in the steam generation zone should create more nuclei for bubble to form and result in a reduced average bubble size and shorter retention time, i.e. the time for the vapor phase sticking on the pipe surface. The smaller average steam bubble size and shorter bubble retention time will enhance the overall thermal efficiency. As a preliminary step, a periodic arrangement of micropin-fins containing four in-line cylindrical fins was modeled. The governing equations for the mass, momentum and energy transport were solved in the fluid in a conjugate heat transfer mode. In the future, several studies will be conducted to simulate different geometric arrangements, different fin cross-sections, and realistic operating conditions including phase-change with boiling by adding complexities in simple steps.

  4. A confluence-based expert system for the detection of heat exchanger fouling

    SciTech Connect

    Afgan, N.H.; Carvalho, M.D.G.

    1998-04-01

    Efficiency assessment of heat exchangers ensures appropriate use of the available energy. This article presents the concept of a heat exchanger on-line expert system based on qualitative reasoning. Using confluence of the heat exchanger effectiveness defined by the NTU (number of transfer units) concept for the simple parallel-stream heat exchanger, the methodology is developed to be used for the description of the generic behavior of those situations leading to the degradation of the effectiveness of the heat exchanger. The article describes the selection of the diagnostic variables, and their on-line measurements including the logging system for monitoring and acquisition of the data. For a specific heat exchanger, the expert system assessment was performed for a number of different situations. An appropriate diagnostic system in the specified time period produces a set of readings of the diagnostic variables, describing the state of the system. The set of diagnostic variables converted into the confluence parameters constitutes the qualitative description of the instantaneous state of the system. A retrieval strategy is used to find the corresponding state in the knowledge base with the set of the parameters describing the individual malfunction state of the system. Each malfunction state is accompanied by a recommendation for its correction specified by expert advice.

  5. Mapping Heat Exchange in an Allosteric Protein

    PubMed Central

    Gupta, Shaweta; Auerbach, Anthony

    2011-01-01

    Nicotinic acetylcholine receptors (AChRs) are synaptic ion channels that spontaneously isomerize (i.e., gate) between resting and active conformations. We used single-molecule electrophysiology to measure the temperature dependencies of mouse neuromuscular AChR gating rate and equilibrium constants. From these we estimated free energy, enthalpy, and entropy changes caused by mutations of amino acids located between the transmitter binding sites and the middle of the membrane domain. The range of equilibrium enthalpy change (13.4 kcal/mol) was larger than for free energy change (5.5 kcal/mol at 25°C). For two residues, the slope of the rate-equilibrium free energy relationship (Φ) was approximately constant with temperature. Mutant cycle analysis showed that both free energies and enthalpies are additive for energetically independent mutations. We hypothesize that changes in energy associated with changes in structure mainly occur close to the site of the mutation, and, hence, that it is possible to make a residue-by-residue map of heat exchange in the AChR gating isomerization. The structural correlates of enthalpy changes are discussed for 12 different mutations in the protein. PMID:21320434

  6. 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.

  7. Heat exchange units boiling process numerical modeling at subatmospheric pressure

    NASA Astrophysics Data System (ADS)

    Slobodina, E. N.; Mikhailov, A. G.

    2017-08-01

    The paper deals with the boiling process mechanism, the results of the boiling intensification methods analysis at subatmospheric pressure are presented. The calculation methodology for the boiling process on the surface performed in the form of capillary slotted channels is represented. Heat transfer coefficients variations calculation dependences defined by analytical and numerical methods applying are described. The heat exchange surface geometrical characteristics impact on the heat exchange capacity in vacuum conditions was investigated.

  8. Improvement of heat transfer by means of ultrasound: Application to a double-tube heat exchanger.

    PubMed

    Legay, M; Simony, B; Boldo, P; Gondrexon, N; Le Person, S; Bontemps, A

    2012-11-01

    A new kind of ultrasonically-assisted heat exchanger has been designed, built and studied. It can be seen as a vibrating heat exchanger. A comprehensive description of the overall experimental set-up is provided, i.e. of the test rig and the acquisition system. Data acquisition and processing are explained step-by-step with a detailed example of graph obtained and how, from these experimental data, energy balance is calculated on the heat exchanger. It is demonstrated that ultrasound can be used efficiently as a heat transfer enhancement technique, even in such complex systems as heat exchangers.

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

    DOEpatents

    Phillips, Benjamin A.; Zawacki, Thomas S.; Marsala, Joseph

    1994-11-29

    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 the working solution of the absorption system for the heat transfer medium.

  10. Direct-contact closed-loop heat exchanger

    DOEpatents

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

    1984-01-01

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

  11. Temperature distribution in internally heated walls of heat exchangers composed of nonnuclear flow passages

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Low, George M

    1951-01-01

    In the walls of heat exchangers composed of noncircular passages, the temperature varies in the circumferential direction because of local variations of the heat-transfer coefficients. A prediction of the magnitude of this variation is necessary in order to determine the region of highest temperature and in order to determine the admissible operating temperatures. A method for the determination of these temperature distributions and of the heat-transfer characteristics of a special type of heat exchanger is developed. The heat exchanger is composed of polygonal flow passages and the passage walls are uniformly heated by internal heat sources. The coolant flow within the passages is assumed to be turbulent. The circumferential variation of the local heat-transfer coefficients is estimated from flow measurements made by Nikuradse, postulating similarity between velocity and temperature fields. Calculations of temperature distributions based on these heat-transfer coefficients are carried out and results for heat exchangers with triangular and rectangular passages are presented.

  12. Heat loss through insulated steam lines

    SciTech Connect

    Kloepfer, J.G.; Dykstra, S.

    1982-02-22

    Heat loss through piping is a costly problem in steam-oriented thermal recovery operations. To determine the heat loss from above- and below-ground insulated steam piping, a program has been written for the TI-59 programmable calculator. Given the pipe parameters, steam temperature, and wind velocity, this program calculates the heat loss in w/m. Assuming pressure drop through the line is negligible, steam quality may be calculated at any point along the pipe. The newton-Raphson iterative technique is used to solve 2 simultaneous equations for the skin temperature. Once convergence is complete, skin temperature is used to calculate the heat loss. The program will allow the engineer to determine heat lost from the steam generator to the wellhead.

  13. 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 Si

  14. Heat Recovery Ventilation for Housing: Air-to-Air Heat Exchangers.

    ERIC Educational Resources Information Center

    Corbett, Robert J.; Miller, Barbara

    The air-to-air heat exchanger (a fan powered ventilation device that recovers heat from stale outgoing air) is explained in this six-part publication. Topic areas addressed are: (1) the nature of air-to-air heat exchangers and how they work; (2) choosing and sizing the system; (3) installation, control, and maintenance of the system; (4) heat…

  15. High performance microchannel heat exchanger for cooling high heat load x-ray optical elements

    SciTech Connect

    Choi, U.S.; Rogers, C.S.; Mills, D.M.

    1992-01-01

    Analysis has been carried out to demonstrate that a liquid nitrogen cooled microchannel heat exchanger can be designed to maximize the heat transfer from silicon to the working fluid. The results show that the performance of the liquid nitrogen cooled microchannel heat exchanger is significantly enhanced by approximately three times over flowing water through microchannels.

  16. High performance microchannel heat exchanger for cooling high heat load x-ray optical elements

    SciTech Connect

    Choi, U.S.; Rogers, C.S.; Mills, D.M.

    1992-12-01

    Analysis has been carried out to demonstrate that a liquid nitrogen cooled microchannel heat exchanger can be designed to maximize the heat transfer from silicon to the working fluid. The results show that the performance of the liquid nitrogen cooled microchannel heat exchanger is significantly enhanced by approximately three times over flowing water through microchannels.

  17. Physical explosion analysis in heat exchanger network design

    NASA Astrophysics Data System (ADS)

    Pasha, M.; Zaini, D.; Shariff, A. M.

    2016-06-01

    The failure of shell and tube heat exchangers is being extensively experienced by the chemical process industries. This failure can create a loss of production for long time duration. Moreover, loss of containment through heat exchanger could potentially lead to a credible event such as fire, explosion and toxic release. There is a need to analyse the possible worst case effect originated from the loss of containment of the heat exchanger at the early design stage. Physical explosion analysis during the heat exchanger network design is presented in this work. Baker and Prugh explosion models are deployed for assessing the explosion effect. Microsoft Excel integrated with process design simulator through object linking and embedded (OLE) automation for this analysis. Aspen HYSYS V (8.0) used as a simulation platform in this work. A typical heat exchanger network of steam reforming and shift conversion process was presented as a case study. It is investigated from this analysis that overpressure generated from the physical explosion of each heat exchanger can be estimated in a more precise manner by using Prugh model. The present work could potentially assist the design engineer to identify the critical heat exchanger in the network at the preliminary design stage.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Ishikawa, Osamu; Hamano, Masayoshi; Yanadori, Michio

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

  20. The predictive protective control of the heat exchanger

    NASA Astrophysics Data System (ADS)

    Nevriva, Pavel; Filipova, Blanka; Vilimec, Ladislav

    2016-06-01

    The paper deals with the predictive control applied to flexible cogeneration energy system FES. FES was designed and developed by the VITKOVICE POWER ENGINEERING joint-stock company and represents a new solution of decentralized cogeneration energy sources. In FES, the heating medium is flue gas generated by combustion of a solid fuel. The heated medium is power gas, which is a gas mixture of air and water steam. Power gas is superheated in the main heat exchanger and led to gas turbines. To protect the main heat exchanger against damage by overheating, the novel predictive protective control based on the mathematical model of exchanger was developed. The paper describes the principle, the design and the simulation of the predictive protective method applied to main heat exchanger of FES.

  1. On boundary condition in heat-exchange processes

    NASA Astrophysics Data System (ADS)

    Stolyarov, E. P.

    2016-10-01

    This paper describes the numerical study of heat-exchange of solid body with high-temperature external flow. As follows from the Newton's boundary condition, connecting a heat-flux density with temperature difference between the flow and a body, the heat-exchange coefficient is physically equivalent to the body-surface-normal component of the entropy flux from external flow at equilibrium flow regime. The method of determination of the heat-exchange characteristics using the time-history temperature measurements by a thin-film thermocouple sensor is described. As it is shown from the numerical analysis, the asymptotic value of the heat-exchange coefficient that corresponded to equilibrium regime of external flow exists. Implementation time of this value, i.e. relaxation time, may be of some characteristic time scales of the sensor measuring layer.

  2. 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.

  3. 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.

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

    DOEpatents

    Swift, Gregory W.; Migliori, Albert; Wheatley, John C.

    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.

  5. Parametric performance studies on fluidized-bed heat exchangers

    NASA Astrophysics Data System (ADS)

    Stoeffler, R. C.

    1982-01-01

    The performance of single and multistage shallow fluidized beds is investigated for possible application to the recovery of heat from sources such as waste heat, and coal combustion or coal gasification. Tests are conducted to (1) investigate the effects of fouling due to liquid condensate in the gas stream on fluidized bed heat exchanger performance, (2) investigate the performance of fluidized beds which are staged using baffle plates, and (3) investigate the effects of different heat exchanger surface geometries. Work is progressing in selecting the conditions for that portion of the program involving fouling by a liquid condensate, and in modifying the fluidized bed heat exchanger facility for the fouling experiments. Preliminary tests were conducted with water vapor injection. Water vapor and glycerol vapor were chosen as the condensates. The results are summarized as follows: (1) heat exchanger performance is seriously degraded by condensation when the dew point temperature exceeds the heat exchanger wall temperature; and (2) the performance decrease occurs as a result of particle adherence to the heat exchanger surface and not as a result of particle agglomeration.

  6. Acoustically enhanced heat exchange and drying apparatus

    DOEpatents

    Bramlette, T.T.; Keller, J.O.

    1987-07-10

    A heat transfer drying apparatus includes an acoustically augmented heat transfer chamber for receiving material to be dried. The chamber includes a first heat transfer gas inlet, a second heat transfer gas inlet, a material inlet, and a gas outlet which also serves as a dried material and gas outlet. A non-pulsing first heat transfer gas source provides a first drying gas to the acoustically augmented heat transfer chamber through the first heat transfer gas inlet. A valveless, continuous second heat transfer gas source provides a second drying gas to the acoustically augmented heat transfer chamber through the second heat transfer gas inlet. The second drying gas also generates acoustic waves which bring about acoustical coupling with the gases in the acoustically augmented heat transfer chamber. The second drying gas itself oscillates at an acoustic frequency of approximately 180 Hz due to fluid mechanical motion in the gas. The oscillations of the second heat transfer gas coupled to the first heat transfer gas in the acoustically augmented heat transfer chamber enhance heat and mass transfer by convection within the chamber. 3 figs.

  7. Compact heat exchangers for condensation applications: Yesterday, today and tomorrow

    SciTech Connect

    Panchal, C.B.

    1993-07-01

    Compact heat exchangers are being increasingly considered for condensation applications in the process, cryogenic, aerospace, power and refrigeration industries. In this paper, different configurations available for condensation applications are analyzed and the current state-of-the-knowledge for the design of compact condensers is evaluated. The key technical issues for the design and development of compact heat exchangers for condensation applications are analyzed and major advantages are identified. The experimental data and performance prediction methods reported in the literature are analyzed to evaluate the present design capabilities for different compact heat-exchanger configurations. The design flexibility is evaluated for the development of new condensation applications, including integration with other process equipment.

  8. Control strategies in a thermal oil - Molten salt heat exchanger

    NASA Astrophysics Data System (ADS)

    Roca, Lidia; Bonilla, Javier; Rodríguez-García, Margarita M.; Palenzuela, Patricia; de la Calle, Alberto; Valenzuela, Loreto

    2016-05-01

    This paper presents a preliminary control scheme for a molten salt - thermal oil heat exchanger. This controller regulates the molten salt mass flow rate to reach and maintain the desired thermal oil temperature at the outlet of the heat exchanger. The controller architecture has been tested using an object-oriented heat exchanger model that has been validated with data from a molten salt testing facility located at CIEMAT-PSA. Different simulations are presented with three different goals: i) to analyze the controller response in the presence of disturbances, ii) to demonstrate the benefits of designing a setpoint generator and iii) to show the controller potential against electricity price variations.

  9. Study of transient behavior of finned coil heat exchangers

    NASA Technical Reports Server (NTRS)

    Rooke, S. P.; Elissa, M. G.

    1993-01-01

    The status of research on the transient behavior of finned coil cross-flow heat exchangers using single phase fluids is reviewed. Applications with available analytical or numerical solutions are discussed. Investigation of water-to-air type cross-flow finned tube heat exchangers is examined through the use of simplified governing equations and an up-wind finite difference scheme. The degenerate case of zero air-side capacitance rate is compared with available exact solution. Generalization of the numerical model is discussed for application to multi-row multi-circuit heat exchangers.

  10. Heat exchanger and water tank arrangement for passive cooling system

    DOEpatents

    Gillett, J.E.; Johnson, F.T.; Orr, R.S.; Schulz, T.L.

    1993-11-30

    A water storage tank in the coolant water loop of a nuclear reactor contains a tubular heat exchanger. The heat exchanger has tube sheets mounted to the tank connections so that the tube sheets and tubes may be readily inspected and repaired. Preferably, the tubes extend from the tube sheets on a square pitch and then on a rectangular pitch there between. Also, the heat exchanger is supported by a frame so that the tank wall is not required to support all of its weight. 6 figures.

  11. Miniature Joule - Thomson liquefier with sintered heat exchanger

    NASA Astrophysics Data System (ADS)

    Eugeniusz, Bodio; Maciej, Chorowski; Marta, Wilczek; Arkadiusz, Bozek

    Conventional Joule-Thomson refrigerators are made with finned, capillary tubing for the heat exchanger and a throttling valve for reducing the pressure [1]. A new kind of recuperative miniature heat-exchanger can be developed if a powder metallurgy technology is used. A high pressure capillary tube is sintered with metal powder. The grains of metal should be ball shaped or similar. In result of sintering process a good thermal contact between an outside tube surface and powder grains is achieved. The heat exchange surface is well developed and a porous sinter acts as a low pressure gas canal.

  12. 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.

  13. Low Cost Polymer heat Exchangers for Condensing Boilers

    SciTech Connect

    Butcher, Thomas; Trojanowski, Rebecca; Wei, George; Worek, Michael

    2015-09-30

    Work in this project sought to develop a suitable design for a low cost, corrosion resistant heat exchanger as part of a high efficiency condensing boiler. Based upon the design parameters and cost analysis several geometries and material options were explored. The project also quantified and demonstrated the durability of the selected polymer/filler composite under expected operating conditions. The core material idea included a polymer matrix with fillers for thermal conductivity improvement. While the work focused on conventional heating oil, this concept could also be applicable to natural gas, low sulfur heating oil, and biodiesel- although these are considered to be less challenging environments. An extruded polymer composite heat exchanger was designed, built, and tested during this project, demonstrating technical feasibility of this corrosion-resistant material approach. In such flue gas-to-air heat exchangers, the controlling resistance to heat transfer is in the gas-side convective layer and not in the tube material. For this reason, the lower thermal conductivity polymer composite heat exchanger can achieve overall heat transfer performance comparable to a metal heat exchanger. However, with the polymer composite, the surface temperature on the gas side will be higher, leading to a lower water vapor condensation rate.

  14. Slotting Fins of Heat Exchangers to Provide Thermal Breaks

    NASA Technical Reports Server (NTRS)

    Scull, Timothy D.

    2003-01-01

    Heat exchangers that include slotted fins (in contradistinction to continuous fins) have been invented. The slotting of the fins provides thermal breaks that reduce thermal conduction along flow paths (longitudinal thermal conduction), which reduces heat-transfer efficiency. By increasing the ratio between transverse thermal conduction (the desired heat-transfer conduction) and longitudinal thermal conduction, slotting of the fins can be exploited to (1) increase heat-transfer efficiency (thereby reducing operating cost) for a given heat-exchanger length or to (2) reduce the length (thereby reducing the weight and/or cost) of the heat exchanger needed to obtain a given heat transfer efficiency. By reducing the length of a heat exchanger, one can reduce the pressure drop associated with the flow through it. In a case in which slotting enables the use of fins with thermal conductivity greater than could otherwise be tolerated on the basis of longitudinal thermal conduction, one can exploit the conductivity to make the fins longer (in the transverse direction) than they otherwise could be, thereby making it possible to make a heat exchanger that contains fewer channels and therefore, that weighs less, contains fewer potential leak paths, and can be constructed from fewer parts and, hence, reduced cost.

  15. 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.

  16. Experimental testing and analytical analysis of a plastic panel heat exchanger for greenhouse heating

    SciTech Connect

    Olszewski, M.; Thomas, J.F.

    1980-02-01

    The performance of a plastic panel-type heat exchanger, suitable for greenhouse heating using low-grade (25 to 60/sup 0/C water) power plant reject heat, was investigated theoretically and experimentally. The theoretical analysis showed that a plastic panel heat exchanger would have an overall heat transfer coefficient, U/sub 0/, of about 18 w/m/sup 2/-/sup 0/C compared to about 12 w/m/sup 2/-/sup 0/C for a fin-tube heat exchanger, under typical greenhouse conditions. Furthermore the plastic heat exchanger would require less fan power due to reduced air pressure losses. The experimental data revealed a similar functional relationship for U/sub 0/ and air flow when compared with the theoretical calculations, however the experimental values of U/sub 0/ were consistently larger by 20 to 30%. It was concluded that a properly designed plastic heat exchanger can compete with metal fin tube type exchangers on a performance basis, but the plastic heat exchangers are 3 to 4 times larger by volume. However, because of the lower cost of plastic, a substantial cost reduction is expected. It appears that further study, examining heat exchanger lifetime, performance and costs, is warranted.

  17. Heat exchanger for reactor core and the like

    DOEpatents

    Kaufman, Jay S.; Kissinger, John A.

    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.

  18. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    SciTech Connect

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-04-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  19. Process Heat Exchanger Options for the Advanced High Temperature Reactor

    SciTech Connect

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-06-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  20. Nosehouse: heat-conserving ventilators based on nasal counterflow exchangers.

    PubMed

    Vogel, Steven

    2009-12-01

    Small birds and mammals commonly minimize respiratory heat loss with reciprocating counterflow exchangers in their nasal passageways. These animals extract heat from the air in an exhalation to warm those passageways and then use that heat to warm the subsequent inhalation. Although the near-constant volume of buildings precludes direct application of the device, a pair of such exchangers located remotely from each other circumvents that problem. A very simple and crudely constructed small-scale physical model of the device worked well enough as a heat conserver to suggest utility as a ventilator for buildings.

  1. Air-cooled heat exchangers: Conventional and unconventional

    SciTech Connect

    Kals, W. )

    1994-08-01

    Wet-surface air-cooled heat exchangers, presently thought of as unconventional, should be considered for applications where fin-tube air coolers are not used. Wet-Surface coolers have advantages where fin-tube exchangers may not supply enough duty, especially during hot weather. They can also cool to temperatures below the capability of cooling water exchangers. Air-cooled heat exchangers made their first appearance in petroleum refineries and chemical processing plants in the US thirty years ago. Their rapidly increasing use is due to the desire of plant designers and operators to avoid problems associated with cooling water. With air as the cooling medium, process heat is surrendered directly to the atmosphere. No additional thermal load is added to existing cooling towers. The paper describes air-cooled exchangers, design features, applications, and limitations.

  2. A simplified model of heat transfer in heat exchangers and stack plates of thermoacoustic refrigerators

    NASA Astrophysics Data System (ADS)

    Herman, Cila; Chen, Yuwen

    2006-08-01

    A simplified model of heat transfer was developed to investigate the thermal behavior of heat exchangers and stack plates of thermoacoustic devices. The model took advantage of previous results describing the thermal behavior of the thermoacoustic core and heat transfer in oscillating flow to study the performance of heat exchangers attached to the core. The configuration considered is a flat tube (with a working fluid flowing in the tube) of the thickness of the stack plate attached to both ends of the stack plate. Geometrical and operational parameters as well as thermophysical properties of the heat exchangers, transport fluids in the heat exchangers, stack plate and the thermoacoustic working fluid were organized into dimensionless groups that allowed accounting for their impact on the performance of the heat exchangers. Two types of thermal boundary conditions were considered: constant temperature and constant heat flux along the heat exchanger tubes. Numerical simulations were carried out with the model introduced in the paper. The temperature distributions and heat fluxes near the edge of the stack plate were found to be nonlinear. The influence of system parameters on the thermal performance of the heat exchangers was analyzed.

  3. Heat exchanger identification by using iterative fuzzy observers

    NASA Astrophysics Data System (ADS)

    Lalot, Sylvain; Guðmundsson, Oddgeir; Pálsson, Halldór; Pálsson, Ólafur Pétur

    2016-05-01

    The principle of fuzzy observers is first illustrated on a general example: the determination of the two parameters of second order systems using a step response. The set of equations describing the system are presented and it is shown that accurate results are obtained, even for a high level of noise. The heat exchanger model is then introduced. It is based on a spatial division of a counter flow heat exchanger into multiple sections. The governing equations are rewritten as a state space representation. The number of sections needed to get accurate results is determined by comparing estimated values to experimental data. Based on the mean value of the root mean squared errors, it is shown that 80 sections is an appropriate value for this heat exchanger. It is then shown that the iterative fuzzy observers can be used to determine the main parameters of the counter flow heat exchanger, i.e. the convection heat transfer coefficients, when in transient state. The final values of these parameters are <3.5 % apart from the values determined by a time consuming trial and error procedure. Finally a sensitivity study is carried out, showing that a ±1.5 % variation of the actual value of the overall heat transfer coefficient corresponds to a ±0.5 % variation of the estimated overall heat transfer coefficient. This study also shows that the fuzzy observers are equally efficient when the heat exchanger is in steady state.

  4. Oscillating side-branch enhancements of thermoacoustic heat exchangers

    DOEpatents

    Swift, Gregory W.

    2003-05-13

    A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a gas oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the gas oscillates, and first and second heat exchangers, each of which is at one of the two different temperatures. A dead-end side branch into which the gas oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating gas flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating gas volumetric flow rate through the first heat exchanger. This configuration enables the first heat exchanger to be configured and located to better enhance the performance of the heat exchanger rather than being confined to the location and configuration of the regenerator.

  5. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4240 Cardiopulmonary..., consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or...

  6. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4240 Cardiopulmonary..., consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or...

  7. 1-MWE heat exchangers for OTEC. Final design report

    SciTech Connect

    Sprouse, A.M.

    1980-06-19

    The design of a 1 MWe OTEC heat exchanger is documented, including the designs of the evaporator and associated systems, condenser, instrumentation, and materials for corrosion/erosion control and fabrication processes. (LEW)

  8. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... that could be used to develop an acceptable monitoring program are ion specific electrode monitoring, p... associated with the leaking heat exchanger. The owner or operator shall document the basis for...

  9. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... section. Surrogate indicators that could be used to develop an acceptable monitoring program are ion... associated with the leaking heat exchanger. The owner or operator shall document the basis for...

  10. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... section. Surrogate indicators that could be used to develop an acceptable monitoring program are ion... associated with the leaking heat exchanger. The owner or operator shall document the basis for...

  11. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4240 Cardiopulmonary..., consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or...

  12. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4240 Cardiopulmonary..., consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or...

  13. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4240 Cardiopulmonary..., consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or...

  14. 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.

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

    SciTech Connect

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

    1998-10-01

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

  16. Acoustically enhanced heat exchange and drying apparatus

    DOEpatents

    Bramlette, T. Tazwell; Keller, Jay O.

    1989-01-01

    A heat transfer apparatus includes a first chamber having a first heat transfer gas inlet, a second heat transfer gas inlet, and an outlet. A first heat transfer gas source provides a first gas flow to the first chamber through the first heat transfer gas inlet. A second gas flow through a second chamber connected to the side of the first chamber, generates acoustic waves which bring about acoustical coupling of the first and second gases in the acoustically augmented first chamber. The first chamber may also include a material inlet for receiving material to be dried, in which case the gas outlet serves as a dried material and gas outlet.

  17. Two-phase/two-phase heat exchanger analysis

    NASA Technical Reports Server (NTRS)

    Kim, Rhyn H.

    1992-01-01

    A capillary pumped loop (CPL) system with a condenser linked to a double two-phase heat exchanger is analyzed numerically to simulate the performance of the system from different starting conditions to a steady state condition based on a simplified model. Results of the investigation are compared with those of similar apparatus available in the Space Station applications of the CPL system with a double two-phase heat exchanger.

  18. A fundamentally new approach to air-cooled heat exchangers.

    SciTech Connect

    Koplow, Jeffrey P.

    2010-01-01

    We describe breakthrough results obtained in a feasibility study of a fundamentally new architecture for air-cooled heat exchangers. A longstanding but largely unrealized opportunity in energy efficiency concerns the performance of air-cooled heat exchangers used in air conditioners, heat pumps, and refrigeration equipment. In the case of residential air conditioners, for example, the typical performance of the air cooled heat exchangers used for condensers and evaporators is at best marginal from the standpoint the of achieving maximum the possible coefficient of performance (COP). If by some means it were possible to reduce the thermal resistance of these heat exchangers to a negligible level, a typical energy savings of order 30% could be immediately realized. It has long been known that a several-fold increase in heat exchanger size, in conjunction with the use of much higher volumetric flow rates, provides a straight-forward path to this goal but is not practical from the standpoint of real world applications. The tension in the market place between the need for energy efficiency and logistical considerations such as equipment size, cost and operating noise has resulted in a compromise that is far from ideal. This is the reason that a typical residential air conditioner exhibits significant sensitivity to reductions in fan speed and/or fouling of the heat exchanger surface. The prevailing wisdom is that little can be done to improve this situation; the 'fan-plus-finned-heat-sink' heat exchanger architecture used throughout the energy sector represents an extremely mature technology for which there is little opportunity for further optimization. But the fact remains that conventional fan-plus-finned-heat-sink technology simply doesn't work that well. Their primary physical limitation to performance (i.e. low thermal resistance) is the boundary layer of motionless air that adheres to and envelops all surfaces of the heat exchanger. Within this boundary layer

  19. The Experimental Study on Heat Transfer Characteristics of The External Heat Exchanger

    NASA Astrophysics Data System (ADS)

    Ji, X. Y.; Lu, X. F.; Yang, L.; Liu, H. Z.

    Using the external heat exchanger in large-scale CFB boilers can control combustion and heat transfer separately, make the adjustments of bed temperature and steam temperature convenient. The state of gas-solid two phase flow in the external heat exchanger is bubbling fluidized bed, but differs from the regular one as there is a directional flow in it. Consequently, the temperature distribution changes along the flow direction. In order to study the heat transfer characteristics of the water cooled tubes in the bubbling fluidized bed and ensure the uniformity of heat transfer in the external heat exchanger, a physical model was set up according to the similarity principle and at the geometric ratio of 1∶28 to an external heat exchanger of a 300MW CFB boiler. The model was connected with an electrically heated CFB test-bed which provides the circulating particles. The influencing factors and the distribution rule of the particles' heat transfer coefficient in the external heat exchanger were assessed by measuring the temperature changes of the water in the tubes and different parts of particles flow along the flow direction. At the end, an empirical correlation of particles' heat transfer coefficient in external heat exchanger was given by modifying the Veedendery empirical correlation.

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

    SciTech Connect

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

    1981-01-01

    This addendum to the DOE/ANL/HTRI Heat Exchanger Tube Vibration Data Bank includes 16 new case histories of field experiences. The cases include several exchangers that did not experience vibration problems and several for which acoustic vibration was reported.

  1. The fouling in the tubular heat exchanger of Algiers refinery

    NASA Astrophysics Data System (ADS)

    Harche, Rima; Mouheb, Abdelkader; Absi, Rafik

    2016-05-01

    Crude oil fouling in refinery preheat exchangers is a chronic operational problem that compromises energy recovery in these systems. Progress is hindered by the lack of quantitative knowledge of the dynamic effects of fouling on heat exchanger transfer and pressure drops. In subject of this work is an experimental determination of the thermal fouling resistance in the tubular heat exchanger of the crude oil preheats trains installed in an Algiers refinery. By measuring the inlet and outlet temperatures and mass flows of the two fluids, the overall heat transfer coefficient has been determined. Determining the overall heat transfer coefficient for the heat exchanger with clean and fouled surfaces, the fouling resistance was calculated. The results obtained from the two cells of exchangers studies, showed that the fouling resistance increased with time presented an exponential evolution in agreement with the model suggested by Kern and Seaton, with the existence of fluctuation caused by the instability of the flow rate and the impact between the particles. The bad cleaning of the heat exchangers involved the absence of the induction period and caused consequently, high values of the fouling resistance in a relatively short period of time.

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

    SciTech Connect

    Wetzel, M.; Herman, C.

    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.

  3. Heat Exchanger Design Studies for AN Lhc Inner Triplet Upgrade

    NASA Astrophysics Data System (ADS)

    Rabehl, R. J.; Huang, Y.

    2008-03-01

    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.

  4. 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

  5. Investigation and optimization of the depth of flue gas heat recovery in surface heat exchangers

    NASA Astrophysics Data System (ADS)

    Bespalov, V. V.; Bespalov, V. I.; Melnikov, D. V.

    2017-09-01

    Economic issues associated with designing deep flue gas heat recovery units for natural gas-fired boilers are examined. The governing parameter affecting the performance and cost of surface-type condensing heat recovery heat exchangers is the heat transfer surface area. When firing natural gas, the heat recovery depth depends on the flue gas temperature at the condenser outlet and determines the amount of condensed water vapor. The effect of the outlet flue gas temperature in a heat recovery heat exchanger on the additionally recovered heat power is studied. A correlation has been derived enabling one to determine the best heat recovery depth (or the final cooling temperature) maximizing the anticipated reduced annual profit of a power enterprise from implementation of energy-saving measures. Results of optimization are presented for a surface-type condensing gas-air plate heat recovery heat exchanger for the climatic conditions and the economic situation in Tomsk. The predictions demonstrate that it is economically feasible to design similar heat recovery heat exchangers for a flue gas outlet temperature of 10°C. In this case, the payback period for the investment in the heat recovery heat exchanger will be 1.5 years. The effect of various factors on the optimal outlet flue gas temperature was analyzed. Most climatic, economical, or technological factors have a minor effect on the best outlet temperature, which remains between 5 and 20°C when varying the affecting factors. The derived correlation enables us to preliminary estimate the outlet (final) flue gas temperature that should be used in designing the heat transfer surface of a heat recovery heat exchanger for a gas-fired boiler as applied to the specific climatic conditions.

  6. Linking Trajectories: On-Line Learning and Intercultural Exchanges

    ERIC Educational Resources Information Center

    Levinson, Nanette; Davidson, Kaitlin E.

    2015-01-01

    There has been tremendous growth both in study abroad and intercultural exchange options in the United States and also in on-line learning options in higher education. Reviewing 91 cross-cultural experiences with at least one type of formal on-line component, this paper provides an overview and categorization of these offerings as well as a…

  7. Quantification of the heat exchange of chicken eggs.

    PubMed

    Van Brecht, A; Hens, H; Lemaire, J L; Aerts, J M; Degraeve, P; Berckmans, D

    2005-03-01

    In the incubation process of domestic avian eggs, the development of the embryo is mainly influenced by the physical microenvironment around the egg. Only small spatiotemporal deviations in the optimal incubator air temperature are allowed to optimize hatchability and hatchling quality. The temperature of the embryo depends on 3 factors: (1) the air temperature, (2) the exchange of heat between the egg and its microenvironment and (3) the time-variable heat production of the embryo. Theoretical estimates on the heat exchange between an egg and its physical microenvironment are approximated using equations that assume an approximate spherical shape for eggs. The objective of this research was to determine the heat transfer between the eggshell and its microenvironment and then compare this value to various theoretical estimates. By using experimental data, the overall and the convective heat transfer coefficients were determined as a function of heat production, air humidity, air speed, and air temperature. Heat transfer was not affected by air humidity but solely by air temperature, embryonic heat generation, and air speed and flow around eggs. Also, heat transfer in forced-air incubators occurs mainly by convective heat loss, which is dependent on the speed of airflow. A vertical airflow is more efficient than a horizontal airflow in transferring heat from the egg. We showed that describing an egg as a sphere underestimated convective heat transfer by 33% and was, therefore, too simplistic to accurately assess actual heat transfer from real eggs.

  8. Numerical and Experimental Investigation for Heat Transfer Enhancement by Dimpled Surface Heat Exchanger in Thermoelectric Generator

    NASA Astrophysics Data System (ADS)

    Wang, Yiping; Li, Shuai; Yang, Xue; Deng, Yadong; Su, Chuqi

    2016-03-01

    For vehicle thermoelectric exhaust energy recovery, the temperature difference between the heat exchanger and the coolant has a strong influence on the electric power generation, and ribs are often employed to enhance the heat transfer of the heat exchanger. However, the introduction of ribs will result in a large unwanted pressure drop in the exhaust system which is unfavorable for the engine's efficiency. Therefore, how to enhance the heat transfer and control the pressure drop in the exhaust system is quite important for thermoelectric generators (TEG). In the current study, a symmetrical arrangement of dimpled surfaces staggered in the upper and lower surfaces of the heat exchanger was proposed to augment heat transfer rates with minimal pressure drop penalties. The turbulent flow characteristics and heat transfer performance of turbulent flow over the dimpled surface in a flat heat exchanger was investigated by numerical simulation and temperature measurements. The heat transfer capacity in terms of Nusselt number and the pressure loss in terms of Fanning friction factors of the exchanger were compared with those of the flat plate. The pressure loss and heat transfer characteristics of dimples with a depth-to-diameter ratio ( h/D) at 0.2 were investigated. Finally, a quite good heat transfer performance with minimal pressure drop heat exchanger in a vehicle TEG was obtained. And based on the area-averaged surface temperature of the heat exchanger and the Seeback effect, the power generation can be improved by about 15% at Re = 25,000 compared to a heat exchanger with a flat surface.

  9. 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.

  10. Analysis of thermosyphon heat exchangers for use in solar domestic hot water heating systems

    NASA Astrophysics Data System (ADS)

    Dahl, Scott David

    1998-11-01

    A recent innovation in the solar industry is the use of thermosyphon heat exchangers. Determining the performance of these systems requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. This study demonstrates that several thermosyphon heat exchanger designs operate in the laminar mixed convection regime. Empirical heat transfer and pressure drop correlations are obtained for three tube-in-shell heat exchangers (four, seven, and nine tube). Thermosyphon flow is on the shell side. Correlations are obtained with uniform heat flux on the tube walls and with a mixture of glycol and water circulating inside the tubes. Ranges of Reynolds, Prandtl, and Grashof numbers are 50 to 1800, 2.5 and 6.0, and 4×105 to 1×108, respectively. Nusselt number correlations are presented in a form that combines the contributions of forced and natural convection, Nu4Mixed=Nu4Forced+Nu4Natural. The Nusselt number is influenced by natural convection when the term Raq0.25/(Re0.5Pr0.33) is greater than unity. Pressure drop through these three designs is not significantly affected by mixed convection because most pressure drop losses are at the heat exchanger inlet and outlet. A comparison and discussion of the performance of several other heat exchanger designs (tube-in-shell and coil-in- shell designs) are presented. Generally, the coil-in- shell heat exchangers perform better than the tube-in- shell heat exchangers. Data from all heat exchanger designs is used to develop a new one-dimensional model for thermosyphon heat exchangers in solar water heating systems. The model requires two empirically determined relationships, pressure drop as a function of water mass flow rate and the overall heat transfer coefficient-area product (UA) as a function of Reynolds, Prandtl, and Grashof number. A testing protocol is presented that describes the procedure to obtain the data for the correlations. Two new TRNSYS component models are presented

  11. A Freezable Heat Exchanger for Space Suit Radiator Systems

    NASA Technical Reports Server (NTRS)

    Nabity, James A.; Mason, Georgia R.; Copeland, Robert J.; Trevino, Luis a.

    2008-01-01

    During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut s metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment and the load from the electrical components. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Radiators have no moving parts and are thus highly reliable. Past freezable radiators have been too heavy, but the weight can be greatly reduced by placing a small and freeze tolerant heat exchanger between the astronaut and radiator, instead of making the very large radiator freeze tolerant. Therefore, the key technological innovation to improve space suit radiator performance was the development of a lightweight and freezable heat exchanger that accommodates the variable heat load generated by the astronaut. Herein, we present the heat transfer performance of a newly designed heat exchanger that endured several freeze / thaw cycles without any apparent damage. The heat exchanger was also able to continuously turn down or turn up the heat rejection to follow the variable load.

  12. Derivation of effectiveness-NTU method for heat exchangers with heat leak

    SciTech Connect

    William M. Soyars

    2001-11-01

    A powerful and useful method for heat exchanger analysis is the effectiveness-NTU method. The equations for this technique presented in textbooks, however, are limited to the case where all of the heat transfer occurs between the two fluid streams. In an application of interest to us, cryogenic heat exchangers, we wish to consider a heat leak term. Thus, we have derived equations for the {var_epsilon}-NTU method with heat leak involved. The cases to be studied include evaporators, condensers, and counter-flow, with heat leak both in and out.

  13. Temperature control system for a J-module heat exchanger

    DOEpatents

    Basdekas, Demetrios L.; Macrae, George; Walsh, Joseph M.

    1978-01-01

    The level of primary fluid is controlled to change the effective heat transfer area of a heat exchanger utilized in a liquid metal nuclear power plant to eliminate the need for liquid metal control valves to regulate the flow of primary fluid and the temperature of the effluent secondary fluid.

  14. Capillary pumped loop body heat exchanger

    NASA Technical Reports Server (NTRS)

    Swanson, Theodore D. (Inventor); Wren, deceased, Paul (Inventor)

    1998-01-01

    A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized.

  15. Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

    NASA Astrophysics Data System (ADS)

    Andrzejczyk, Rafał; Muszyński, Tomasz

    2016-12-01

    The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

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

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    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 pipe as the link between the engine and the heat source. Two inexpensive verification tests are proposed. The SSE heat exchanger module is described and the operating conditions for the module are outlined. The design process of the heat exchanger modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pipe to transport heat to a Stirling engine are discussed. Similarly, the problems encountered when using a true heat pipe, as opposed to a more simple reflux boiler, are described. The instruments incorporated into the modules and the test program are also outlined.

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

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    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 pipe as the link between the engine and the heat source. Two inexpensive verification tests are proposed. The SSE heat exchanger module is described and the operating conditions for the module are outlined. The design process of the heat exchanger modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pipe to transport heat to a Stirling engine are discussed. Similarly, the problems encountered when using a true heat pipe, as opposed to a more simple reflux boiler, are described. The instruments incorporated into the modules and the test program are also outlined.

  18. Air Circulation and Heat Exchange Under Reduced Pressures

    NASA Technical Reports Server (NTRS)

    Rygalov, V.; Wheeler, R.; Dixon, M.; Fowler, P.; Hillhouse, L.

    2010-01-01

    Heat exchange rates decrease non-linearly with reductions in atmospheric pressure. This decrease creates risk of thermal stress (elevated leaf temperatures) for plants under reduced pressures. Forced convection (fans) significantly increases heat exchange rate under almost all pressures except below 10 kPa. Plant cultivation techniques under reduced pressures will require forced convection. The cooling curve technique is a reliable means of assessing the influence of environmental variables like pressure and gravity on gas exchange of plant. These results represent the extremes of gas exchange conditions for simple systems under variable pressures. In reality, dense plant canopies will exhibit responses in between these extremes. More research is needed to understand the dependence of forced convection on atmospheric pressure. The overall thermal balance model should include latent and radiative exchange components.

  19. Dimensional Analysis of Ocean Thermal Energy Conversion Heat Exchangers

    DTIC Science & Technology

    1977-06-30

    8217thIJt4IiTY CLASSIFICATION OF TWI4S PAG(E ona Dola t ern.r) 20. (continued) c-a• of factors having significance in OTEC (Ocean Thermal Energy Conversion...heat exchangers. Certain of these groups are then evaluated for a model and prototype OTEC -Type heat exchanger using the same working fluid and ex...Development Administration, and the U. S. Navy are brought out. Chapter II investigates the scaling problems of heat ex- changers in OTEC (Ocean Thermal

  20. Study on finned pipe performance as a ground heat exchanger

    NASA Astrophysics Data System (ADS)

    Lin, Qinglong; Ma, Jinghui; Shi, Lei

    2017-08-01

    The GHEs (ground heat exchangers) is an important element that determines the thermal efficiency of the entire ground-source heat-pump system. The aim of the present study is to clarify thermal performance of a new type GHE pipe, which consists straight fins of uniform cross sectional area. In this paper, GHE model is introduced and an analytical model of new type GHE pipe is developed. The heat exchange rate of BHEs utilizing finned pips is 40.42 W/m, which is 16.3% higher than normal BHEs, based on simulation analyses.

  1. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1992-01-01

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

  2. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1993-02-01

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

  3. 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.

  4. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1993-02-01

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

  5. Direct use geothermal applications for brazed plate heat exchangers

    SciTech Connect

    Rafferty, K.

    1992-12-31

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

  6. Renormalized anisotropic exchange for representing heat assisted magnetic recording media

    SciTech Connect

    Jiao, Yipeng; Liu, Zengyuan; Victora, R. H.

    2015-05-07

    Anisotropic exchange has been incorporated in a description of magnetic recording media near the Curie temperature, as would be found during heat assisted magnetic recording. The new parameters were found using a cost function that minimized the difference between atomistic properties and those of renormalized spin blocks. Interestingly, the anisotropic exchange description at 1.5 nm discretization yields very similar switching and magnetization behavior to that found at 1.2 nm (and below) discretization for the previous isotropic exchange. This suggests that the increased accuracy of anisotropic exchange may also reduce the computational cost during simulation.

  7. Direct-contact closed-loop heat exchanger

    DOEpatents

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

    1981-11-02

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

  8. Carbon-Fiber Brush Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Knowles, Timothy R.

    2004-01-01

    Velvetlike and brushlike pads of carbon fibers have been proposed for use as mechanically compliant, highly thermally conductive interfaces for transferring heat. A pad of this type would be formed by attaching short carbon fibers to either or both of two objects that one desires to place in thermal contact with each other. The purpose of using a thermal-contact pad of this or any other type is to reduce the thermal resistance of an interface between a heat source and a heat sink.

  9. Thermodynamic analysis and optimization of air-cooled heat exchangers

    NASA Astrophysics Data System (ADS)

    Salimpour, Mohammad Reza; Bahrami, Zabihollah

    2011-01-01

    In the present study, a thermodynamic second-law analysis was performed to investigate the effects of different geometry and flow parameters on the air-cooled heat exchanger performance. For this purpose, the entropy generation due to heat transfer and pressure loss of internal and external flows of the air-cooled heat exchanger was calculated; and it was observed that the total entropy generation has a minimum at special tube-side Reynolds number. Also, it was seen that the increasing of the tube-side Reynolds number resulted in the rise of the irreversibility of the air-cooled heat exchanger. The results also showed when air-side Reynolds number decreased, the entropy generation rate of the external flow reduced. Finally, based on the computed results, a new correlation was developed to predict the optimum Reynolds number of the tube-side fluid flow.

  10. 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.

  11. Performance of parallel flow HeII heat exchangers

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed

    Khaled, A-R A

    2014-01-01

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

  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. Special heat transfer monitor (HTM) for the Trane Company OTEC heat exchanger

    SciTech Connect

    Kuzay, T.M.; Panchal, C.B.; Gavin, A.P.

    1981-02-01

    A Heat Transfer Monitor (HTM) is a sensitive device which quantifies development of biofouling in the OTEC heat exchanger surfaces in terms of degrading heat transfer coefficient as biofouling progresses. The Carnegie-Mellon University (CMU) type HTM has been successfully utilized to date for plain circular OTEC heat exchanger tubes. With the development of compact heat exchangers for OTEC with non-circular and/or complex tube geometries, a device independent HTM (Universal Monitor) concept is being sought. For the meantime, however, novel methods have been developed to extend the principles of the CMU type HTM to noncircular tube geometries. The theory, formulation, analytical solutions and laboratory test results are presented for the novel use of the CMU HTM concept with such a special tube for the Trane Company heat exchanger for OTEC.

  15. Applicability of uniform heat flux Nusselt number correlations to thermosyphon heat exchangers for solar water heaters

    SciTech Connect

    Dahl, S.; Davidson, J.

    1999-05-01

    Nusselt numbers are measured in three counterflow tube-in-shell heat exchangers with flow rates and temperatures representative of thermosyphon operation in solar water heating systems. Mixed convection heat transfer correlations for these tube-in-shell heat exchangers were previously developed in Dahl and Davidson (1998) from data obtained in carefully controlled experiments with uniform heat flux at the tube walls. The data presented in this paper confirm that the uniform heat flux correlations apply under more realistic conditions. Water flows in the shell and 50 percent ethylene glycol circulates in the tubes. Actual Nusselt numbers are within 15 percent of the values predicted for a constant heat flux boundary condition. The data reconfirm the importance of mixed convection in determining heat transfer rates. Under most operating conditions, natural convection heat transfer accounts for more than half of the total heat transfer rate.

  16. Applicability of uniform heat flux Nusselt number correlations to thermosyphon heat exchangers for solar water heaters

    SciTech Connect

    Dahl, S.; Davidson, J.

    1999-07-01

    Nusselt numbers are measured in three counterflow tube-in-shell heat exchangers with flow rates and temperatures representative of thermosyphon operation in solar water heating systems. Mixed convection heat transfer correlations for these tube-in-shell heat exchangers were previously developed in Dahl and Davidson (1998) from data obtained in carefully controlled experiments with uniform heat flux at the tube walls. The data presented in this paper confirm that the uniform heat flux correlations apply under more realistic conditions. Water flows in the shell and 50% ethylene glycol is circulated in the tubes. Actual Nusselt numbers are within 15% of the values predicted for a constant heat flux boundary condition. The data reconfirm the importance of mixed convection in determining heat transfer rates. Under most operating conditions, natural convection heat transfer accounts for more than half of the total heat transfer rate.

  17. Boiling heat transfer of refrigerant R-21 in upward flow in plate-fin heat exchanger

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. V.; Shamirzaev, A. S.

    2015-11-01

    The article presents the results of experimental investigation of boiling heat transfer of refrigerant R-21 in upward flow in a vertical plate-fin heat exchanger with transverse size of the channels that is smaller than the capillary constant. The heat transfer coefficients obtained in ranges of small mass velocities and low heat fluxes, which are typical of the industry, have been poorly studied yet. The characteristic patterns of the upward liquid-vapor flow in the heat exchanger channels and the regions of their existence are detected. The obtained data show a weak dependence of heat transfer coefficient on equilibrium vapor quality, mass flow rate, and heat flux density and do not correspond to calculations by the known heat transfer models. A possible reason for this behavior is a decisive influence of evaporation of thin liquid films on the heat transfer at low heat flux.

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

    DOEpatents

    Phillips, Benjamin A.; Zawacki, Thomas S.

    1996-12-03

    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 the working solution of the absorption system for the heat transfer medium. A combination of weak and rich liquor working solution is used as the heat transfer medium.

  19. Progress Report for Diffusion Welding of the NGNP Process Application Heat Exchangers

    SciTech Connect

    R.E. Mizia; D.E. Clark; M.V. Glazoff; T.E. Lister; T.L. Trowbridge

    2011-04-01

    The NGNP Project is currently investigating the use of metallic, diffusion welded, compact heat exchangers to transfer heat from the primary (reactor side) heat transport system to the secondary heat transport system. The intermediate heat exchanger will transfer this heat to downstream applications such as hydrogen production, process heat, and electricity generation. The channeled plates that make up the heat transfer surfaces of the intermediate heat exchanger will have to be assembled into an array by diffusion welding.

  20. Intensification of heat and mass transfer by ultrasound: application to heat exchangers and membrane separation processes.

    PubMed

    Gondrexon, N; Cheze, L; Jin, Y; Legay, M; Tissot, Q; Hengl, N; Baup, S; Boldo, P; Pignon, F; Talansier, E

    2015-07-01

    This paper aims to illustrate the interest of ultrasound technology as an efficient technique for both heat and mass transfer intensification. It is demonstrated that the use of ultrasound results in an increase of heat exchanger performances and in a possible fouling monitoring in heat exchangers. Mass transfer intensification was observed in the case of cross-flow ultrafiltration. It is shown that the enhancement of the membrane separation process strongly depends on the physico-chemical properties of the filtered suspensions.

  1. A Mini-channel Heat Exchanger System for Heating, Boiling, and Superheating Water by Radiant Combustion

    DTIC Science & Technology

    2007-11-02

    heat flux should not be overlooked. T [°C] Temperature TC Thermocouple w [cm] Width of rectangular channel wc [cm] Center -to- center spacing of...smaller hydraulic diameters changes the flow dynamics and brings the bulk fluid in closer contact with the heat exchanger wall. The objective is a...prescribed or targeted heat rate is known. The available contact area is then used to specify the required heat flux of the cooling or heating

  2. 40 CFR Table 6 to Subpart Hhhhh of... - Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 13 2010-07-01 2010-07-01 false Requirements for Heat Exchange Systems... Manufacturing Pt. 63, Subpt. HHHHH, Table 6 Table 6 to Subpart HHHHH of Part 63—Requirements for Heat Exchange... your heat exchange systems. For each . . . You must . . . Heat exchange system, as defined in §...

  3. Development, Fabrication, and Testing of a Liquid/Liquid Microchannel Heat Exchanger for Constellation Spacecrafts

    NASA Technical Reports Server (NTRS)

    Hawkins-Reynolds, Ebony; Le,Hung; Stephans, Ryan A.

    2009-01-01

    Minimizing mass and volume is critically important for space hardware. Microchannel technology can be used to decrease both of these parameters for heat exchangers. Working in concert with NASA, Pacific Northwest National Laboratories (PNNL) has developed a microchannel liquid/liquid heat exchanger that has resulted in significant mass and volume savings. The microchannel heat exchanger delivers these improvements without sacrificing thermal and pressure drop performance. A conventional heat exchanger has been tested and the performance of it recorded to compare it to the microchannel heat exchanger that PNNL has fabricated. The microchannel heat exchanger was designed to meet all of the requirements of the baseline heat exchanger, while reducing the heat exchanger mass and volume. The baseline heat exchanger was designed to have an transfer approximately 3.1 kW for a specific set of inlet conditions. The baseline heat exchanger mass was 2.7 kg while the microchannel mass was only 2.0 kg. More impressive, however, was the volumetric savings associated with the microchannel heat exchanger. The microchannel heat exchanger was an order of magnitude smaller than the baseline heat exchanger (2180cm3 vs. 311 cm3). This paper will describe the test apparatus designed to complete performance tests for both heat exchangers. Also described in this paper will be the performance specifications for the microchannel heat exchanger and how they compare to the baseline heat exchanger.

  4. Development, Fabrication, and Testing of a Liquid/Liquid Microchannel Heat Exchanger for Constellation Spacecrafts

    NASA Technical Reports Server (NTRS)

    Hawkins-Reynolds, Ebony; Le,Hung; Stephans, Ryan A.

    2009-01-01

    Minimizing mass and volume is critically important for space hardware. Microchannel technology can be used to decrease both of these parameters for heat exchangers. Working in concert with NASA, Pacific Northwest National Laboratories (PNNL) has developed a microchannel liquid/liquid heat exchanger that has resulted in significant mass and volume savings. The microchannel heat exchanger delivers these improvements without sacrificing thermal and pressure drop performance. A conventional heat exchanger has been tested and the performance of it recorded to compare it to the microchannel heat exchanger that PNNL has fabricated. The microchannel heat exchanger was designed to meet all of the requirements of the baseline heat exchanger, while reducing the heat exchanger mass and volume. The baseline heat exchanger was designed to have an transfer approximately 3.1 kW for a specific set of inlet conditions. The baseline heat exchanger mass was 2.7 kg while the microchannel mass was only 2.0 kg. More impressive, however, was the volumetric savings associated with the microchannel heat exchanger. The microchannel heat exchanger was an order of magnitude smaller than the baseline heat exchanger (2180cm3 vs. 311 cm3). This paper will describe the test apparatus designed to complete performance tests for both heat exchangers. Also described in this paper will be the performance specifications for the microchannel heat exchanger and how they compare to the baseline heat exchanger.

  5. 40 CFR Table 6 to Subpart Hhhhh of... - Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 14 2014-07-01 2014-07-01 false Requirements for Heat Exchange Systems... Manufacturing Pt. 63, Subpt. HHHHH, Table 6 Table 6 to Subpart HHHHH of Part 63—Requirements for Heat Exchange... your heat exchange systems. For each . . . You must . . . Heat exchange system, as defined in § 63.101...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 14 2013-07-01 2013-07-01 false Requirements for Heat Exchange Systems... Manufacturing Pt. 63, Subpt. HHHHH, Table 6 Table 6 to Subpart HHHHH of Part 63—Requirements for Heat Exchange... your heat exchange systems. For each . . . You must . . . Heat exchange system, as defined in § 63.101...

  7. 40 CFR Table 6 to Subpart Hhhhh of... - Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 14 2012-07-01 2011-07-01 true Requirements for Heat Exchange Systems... Manufacturing Pt. 63, Subpt. HHHHH, Table 6 Table 6 to Subpart HHHHH of Part 63—Requirements for Heat Exchange... your heat exchange systems. For each . . . You must . . . Heat exchange system, as defined in § 63.101...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 13 2011-07-01 2011-07-01 false Requirements for Heat Exchange Systems... Manufacturing Pt. 63, Subpt. HHHHH, Table 6 Table 6 to Subpart HHHHH of Part 63—Requirements for Heat Exchange... your heat exchange systems. For each . . . You must . . . Heat exchange system, as defined in § 63.101...

  9. BASIMO - Borehole Heat Exchanger Array Simulation and Optimization Tool

    NASA Astrophysics Data System (ADS)

    Schulte, Daniel O.; Bastian, Welsch; Wolfram, Rühaak; Kristian, Bär; Ingo, Sass

    2017-04-01

    Arrays of borehole heat exchangers are an increasingly popular source for renewable energy. Furthermore, they can serve as borehole thermal energy storage (BTES) systems for seasonally fluctuating heat sources like solar thermal energy or district heating grids. The high temperature level of these heat sources prohibits the use of the shallow subsurface for environmental reasons. Therefore, deeper reservoirs have to be accessed instead. The increased depth of the systems results in high investment costs and has hindered the implementation of this technology until now. Therefore, research of medium deep BTES systems relies on numerical simulation models. Current simulation tools cannot - or only to some extent - describe key features like partly insulated boreholes unless they run fully discretized models of the borehole heat exchangers. However, fully discretized models often come at a high computational cost, especially for large arrays of borehole heat exchangers. We give an update on the development of BASIMO: a tool, which uses one dimensional thermal resistance and capacity models for the borehole heat exchangers coupled with a numerical finite element model for the subsurface heat transport in a dual-continuum approach. An unstructured tetrahedral mesh bypasses the limitations of structured grids for borehole path geometries, while the thermal resistance and capacity model is improved to account for borehole heat exchanger properties changing with depth. Thereby, partly insulated boreholes can be considered in the model. Furthermore, BASIMO can be used to improve the design of BTES systems: the tool allows for automated parameter variations and is readily coupled to other code like mathematical optimization algorithms. Optimization can be used to determine the required minimum system size or to increase the system performance.

  10. 4. GENERAL VIEW OF AJAX MAGNETHERMIC HEAT TREATING LINE AT ...

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

    4. GENERAL VIEW OF AJAX MAGNETHERMIC HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  11. 5. DETAIL VIEW OF AJAX MAGNETHERMIC HEAT TREATING LINE AT ...

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

    5. DETAIL VIEW OF AJAX MAGNETHERMIC HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  12. 6. HOT BED FOR THE AJAX MAGNETHERMIC HEAT TREATING LINE ...

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

    6. HOT BED FOR THE AJAX MAGNETHERMIC HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  13. 3. HOT BED FOR SALEMBROSIUS CONTINUOUS GASFIRED HEAT TREATING LINE ...

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

    3. HOT BED FOR SALEM-BROSIUS CONTINUOUS GAS-FIRED HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  14. 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.

  15. Experimental investigation of a reticulated porous alumina heat exchanger for high temperature gas heat recovery

    SciTech Connect

    Banerjee, A; Chandran, RB; Davidson, JH

    2015-01-22

    The present study presents an experimental study of a prototype counter-flow heat exchanger designed to recover sensible heat from inert and reactive gases flowing through a high temperature solar reactor for splitting CO2. The tube-in-tube heat exchanger is comprised of two concentric alumina tubes, each filled with reticulated porous alumina with a nominal porosity of 80% and pore density of 5 pores per inch (ppi). The RPC provides high heat transfer surface area per unit volume (917 m(-1)) with low pressure drop. Measurements include the permeability, inertial coefficient, overall heat transfer coefficient, effectiveness and pressure drop. For laminar flow and an inlet gas temperature of 1240 K, the overall heat transfer coefficients are 36-41 W m(-2) K-1. The measured performance is in good agreement with a prior CFD model of the heat exchanger. (C) 2014 Elsevier Ltd. All rights reserved.

  16. Analysis of radiative heat transfer impact in cross-flow tube and fin heat exchangers

    NASA Astrophysics Data System (ADS)

    Hanuszkiewicz-Drapała, Małgorzata; Bury, Tomasz; Widziewicz, Katarzyna

    2016-03-01

    A cross-flow, tube and fin heat exchanger of the water - air type is the subject of the analysis. The analysis had experimental and computational form and was aimed for evaluation of radiative heat transfer impact on the heat exchanger performance. The main element of the test facility was an enlarged recurrent segment of the heat exchanger under consideration. The main results of measurements are heat transfer rates, as well as temperature distributions on the surface of the first fin obtained by using the infrared camera. The experimental results have been next compared to computational ones coming from a numerical model of the test station. The model has been elaborated using computational fluid dynamics software. The computations have been accomplished for two cases: without radiative heat transfer and taking this phenomenon into account. Evaluation of the radiative heat transfer impact in considered system has been done by comparing all the received results.

  17. CFD analysis of the plate heat exchanger - Mathematical modelling of mass and heat transfer in serial connection with tubular heat exchanger

    NASA Astrophysics Data System (ADS)

    Bojko, Marian; Kocich, Radim

    2016-06-01

    Application of numerical simulations based on the CFD calculation when the mass and heat transfer between the fluid flows is essential component of thermal calculation. In this article the mathematical model of the heat exchanger is defined, which is subsequently applied to the plate heat exchanger, which is connected in series with the other heat exchanger (tubular heat exchanger). The present contribution deals with the possibility to use the waste heat of the flue gas produced by small micro turbine. Inlet boundary conditions to the mathematical model of the plate heat exchanger are obtained from the results of numerical simulation of the tubular heat exchanger. Required parameters such for example inlet temperature was evaluated from temperature field, which was subsequently imported to the inlet boundary condition to the simulation of plate heat exchanger. From the results of 3D numerical simulations are evaluated basic flow variables including the evaluation of dimensionless parameters such as Colburn j-factor and friction ft factor. Numerical simulation is realized by software ANSYS Fluent15.0.

  18. Assessment of next generation nuclear plant intermediate heat exchanger design.

    SciTech Connect

    Majumdar, S.; Moisseytsev, A.; Natesan, K.; Nuclear Engineering Division

    2008-10-17

    The Next Generation Nuclear Plant (NGNP), which is an advanced high temperature gas reactor (HTGR) concept with emphasis on production of both electricity and hydrogen, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 900-1000 C. In the indirect cycle system, an intermediate heat exchanger is used to transfer the heat from primary helium from the core to the secondary fluid, which can be helium, nitrogen/helium mixture, or a molten salt. The system concept for the vary high temperature reactor (VHTR) can be a reactor based on the prismatic block of the GT-MHR developed by a consortium led by General Atomics in the U.S. or based on the PBMR design developed by ESKOM of South Africa and British Nuclear Fuels of U.K. This report has made an assessment on the issues pertaining to the intermediate heat exchanger (IHX) for the NGNP. A detailed thermal hydraulic analysis, using models developed at ANL, was performed to calculate heat transfer, temperature distribution, and pressure drop. Two IHX designs namely, shell and straight tube and compact heat exchangers were considered in an earlier assessment. Helical coil heat exchangers were analyzed in the current report and the results were compared with the performance features of designs from industry. In addition, a comparative analysis is presented between the shell and straight tube, helical, and printed circuit heat exchangers from the standpoint of heat exchanger volume, primary and secondary sides pressure drop, and number of tubes. The IHX being a high temperature component, probably needs to be designed using ASME Code Section III, Subsection NH, assuming that the IHX will be classified as a class 1 component. With input from thermal hydraulic calculations performed at ANL, thermal conduction and stress analyses were performed for the helical heat exchanger design and the results were compared with earlier-developed results on

  19. Supercritical heat exchanger field test (SHEFT), I. Field performance data on shell-and-tube heat exchangers in geothermal service

    SciTech Connect

    Silvester, L.F.; Beaulaurier, L.O.; Mirk, K.F.; Fulton, R.L.

    1981-06-01

    Field performance data on shell-and-tube heat exchangers in geothermal service are presented. The test data were taken for geothermal brine on the tube side and hydrocarbon on the shell side in counterflow for six primary heat exchangers, and for hydrocarbon on the shell side and cooling water on the tube side for the condenser. Test data were for heating isobutane, 1 90/10 isobutane/isopentane mixture, and a 80/20 isobutane/isopentane mixture at supercritical conditions in the vicinity of their critical pressure and temperature, and for condensing the same fluids. The test data were used in a preliminary data analysis to determine the reported heat exchanger performance parameters.

  20. 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.

  1. Effect of Heat Exchanger Material and Fouling on Thermoelectric Exhaust Heat Recovery

    SciTech Connect

    Love, Norman; Szybist, James P; Sluder, Scott

    2011-01-01

    This study is conducted in an effort to better understand and improve the performance of thermoelectric heat recovery systems for automotive use. For this purpose an experimental investigation of thermoelectrics in contact with clean and fouled heat exchangers of different materials is performed. The thermoelectric devices are tested on a bench-scale thermoelectric heat recovery apparatus that simulates automotive exhaust. The thermoelectric apparatus consists of a series of thermoelectric generators contacting a hot-side and a cold-side heat exchanger. The thermoelectric devices are tested with two different hot-side heat exchanger materials, stainless steel and aluminum, and at a range of simulated exhaust gas flowrates (40 to 150 slpm), exhaust gas temperatures (240 C and 280 C), and coolant-side temperatures (40 C and 80 C). It is observed that for higher exhaust gas flowrates, thermoelectric power output increases while overall system efficiency decreases. Degradation of the effectiveness of the EGR-type heat exchangers over a period of driving is also simulated by exposing the heat exchangers to diesel engine exhaust under thermophoretic conditions to form a deposit layer. For the fouled EGR-type heat exchangers, power output and system efficiency is observed to be significantly lower for all conditions tested. The study found, however, that heat exchanger material is the dominant factor in the ability of the system to convert heat to electricity with thermoelectric generators. This finding is thought to be unique to the heat exchangers used for this study, and not a universal trend for all system configurations.

  2. Heat exchange mediated by a quantum system

    NASA Astrophysics Data System (ADS)

    Panasyuk, George Y.; Levin, George A.; Yerkes, Kirk L.

    2012-08-01

    We consider heat transfer between two thermal reservoirs mediated by a quantum system using the generalized quantum Langevin equation. The thermal reservoirs are treated as ensembles of oscillators within the framework of the Drude-Ullersma model. General expressions for the heat current and thermal conductance are obtained for arbitrary coupling strength between the reservoirs and the mediator and for different temperature regimes. As an application of these results we discuss the origin of Fourier's law in a chain of large but finite subsystems coupled to each other by the quantum mediators. We also address a question of anomalously large heat current between the scanning tunneling microscope (STM) tip and substrate found in a recent experiment. The question of minimum thermal conductivity is revisited in the framework of scaling theory as a potential application of the developed approach.

  3. Heat exchange mediated by a quantum system.

    PubMed

    Panasyuk, George Y; Levin, George A; Yerkes, Kirk L

    2012-08-01

    We consider heat transfer between two thermal reservoirs mediated by a quantum system using the generalized quantum Langevin equation. The thermal reservoirs are treated as ensembles of oscillators within the framework of the Drude-Ullersma model. General expressions for the heat current and thermal conductance are obtained for arbitrary coupling strength between the reservoirs and the mediator and for different temperature regimes. As an application of these results we discuss the origin of Fourier's law in a chain of large but finite subsystems coupled to each other by the quantum mediators. We also address a question of anomalously large heat current between the scanning tunneling microscope (STM) tip and substrate found in a recent experiment. The question of minimum thermal conductivity is revisited in the framework of scaling theory as a potential application of the developed approach.

  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. A prototype heat pipe heat exchanger for the capillary pumped loop flight experiment

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Yun, Seokgeun; Kroliczek, Edward J.

    1992-01-01

    A Capillary Pumped Two-Phase Heat Transport Loop (CAPL) Flight Experiment, currently planned for 1993, will provide microgravity verification of the prototype capillary pumped loop (CPL) thermal control system for EOS. CAPL employs a heat pipe heat exchanger (HPHX) to couple the condenser section of the CPL to the radiator assembly. A prototype HPHX consisting of a heat exchanger (HX), a header heat pipe (HHP), a spreader heat pipe (SHP), and a flow regulator has been designed and tested. The HX transmits heat from the CPL condenser to the HHP, while the HHP and SHP transport heat to the radiator assembly. The flow regulator controls flow distribution among multiple parallel HPHX's. Test results indicated that the prototype HPHX could transport up to 800 watts with an overall heat transfer coefficient of more than 6000 watts/sq m-deg C. Flow regulation among parallel HPHX's was also demonstrated.

  6. Heat treatment of exchangers to remove coke

    SciTech Connect

    Turner, J.D.

    1990-02-20

    This patent describes a process for preparing furfural coke for removal from metallic surfaces. It comprises: heating the furfural coke without causing an evolution of heat capable of undesirably altering metallurgical properties of the surfaces in the presence of a gas containing molecular oxygen at a sufficient temperature below 800{degrees}F (427{degrees}C) for a sufficient time to change the crush strength of the coke so as to permit removal with a water jet at a pressure of five thousand pounds per square inch.

  7. Experimental investigation on heat transfer analysis of conical coil heat exchanger with 90° cone angle

    NASA Astrophysics Data System (ADS)

    Purandare, Pramod S.; Lele, Mandar M.; Gupta, Raj Kumar

    2015-03-01

    In the present study, an experimental investigation on thermal performance of the conical coil heat exchanger with 90° conical coil heat exchanger is reported. Three different conical coil heat exchangers of same mean coil diameter (Dm = 200 mm) with different tube diameters ( di = 8, 10, 12.5 mm) are analyzed under steady state condition. The analysis is carried out for the tube side hot fluid flow range of 10-100 lph ( Re = 500-5,000), while the shell side flow range of 30-90 lph. The data available from experimentation leads to evaluate heat transfer coefficients for inside and outside the tube of the conical coil heat exchanger by Wilsons plot method. The calculations are further extended to estimate Nusselt Number ( Nu) and effectiveness. The empirical correlations are proposed for predicting Nu and the outlet temperatures of hot and cold fluids. The predicted empirical correlations show reasonable agreement with the experimental results within the given range of parameters.

  8. Heat exchanger module for stirling engines

    SciTech Connect

    Darche, M. J. P.; Carlquist, S.

    1985-02-12

    The invention relates to Stirling engines and provides a modular assembly composed of a cylinder head, a heater, a regenerator, a cooler and a cold duct, and making it possible by mounting a plurality of identical modules on an engine assembly to construct a multi-cylinder double acting Stirling engine of the indirect heating type.

  9. Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems

    SciTech Connect

    Anderson, Mark; Nellis, Greg; Corradini, Michael

    2012-10-19

    The objective of this project is to produce the necessary data to evaluate the performance of the supercritical carbon dioxide cycle. The activities include a study of materials compatibility of various alloys at high temperatures, the heat transfer and pressure drop in compact heat exchanger units, and turbomachinery issues, primarily leakage rates through dynamic seals. This experimental work will serve as a test bed for model development and design calculations, and will help define further tests necessary to develop high-efficiency power conversion cycles for use on a variety of reactor designs, including the sodium fast reactor (SFR) and very high-temperature gas reactor (VHTR). The research will be broken into three separate tasks. The first task deals with the analysis of materials related to the high-temperature S-CO{sub 2} Brayton cycle. The most taxing materials issues with regard to the cycle are associated with the high temperatures in the reactor side heat exchanger and in the high-temperature turbine. The system could experience pressures as high as 20MPa and temperatures as high as 650°C. The second task deals with optimization of the heat exchangers required by the S-CO{sub 2} cycle; the S-CO{sub 2} flow passages in these heat exchangers are required whether the cycle is coupled with a VHTR or an SFR. At least three heat exchangers will be required: the pre-cooler before compression, the recuperator, and the heat exchanger that interfaces with the reactor coolant. Each of these heat exchangers is unique and must be optimized separately. The most challenging heat exchanger is likely the pre-cooler, as there is only about a 40°C temperature change but it operates close to the CO{sub 2} critical point, therefore inducing substantial changes in properties. The proposed research will focus on this most challenging component. The third task examines seal leakage through various dynamic seal designs under the conditions expected in the S-CO{sub 2} cycle

  10. Heat Exchange Following Atropine Injection Before and AFter Heat Acclimation,

    DTIC Science & Technology

    1983-08-01

    calculated from Nishi and Gagge (10) originally done in this chamber during treadmill walking. The net heat flow (Msk) was determined from M-Eres-Cres...wettedness levels. In normal circumstances (Table 2) Gagge and Nishi (5) have shown that typical environmental/work situations at 3 mets give a P of...Am. J. Physiol. 163:585-597, 1950. 4. Gonzalez, R.R., K.B. Pandolf and A.P. Gagge . Heat acclimation and decline in sweating during humidity

  11. Diffusion Welding of Compact Heat Exchangers for Nuclear Applications

    SciTech Connect

    Denis Clark; Ron Mizia; Dr. Michael V. Glazoff; Mr. Michael W. Patterson

    2012-06-01

    The next-­-generation nuclear plant (NGNP) is designed to be a flexible source of energy, producing various mixes of electrical energy and process heat (for example, for hydrogen generation) on demand. Compact heat exchangers provide an attractive way to move energy from the helium primary reactor coolant to process heat uses. For process heat efficiency, reactor outlet temperatures of 750-­-900°C are desirable. There are minor but deleterious components in the primary coolant; the number of alloys that can handle this environment is small. The present work concentrates on Alloys 800H and 617.

  12. Prefabricated heat-exchanging fireplace. Final technical report

    SciTech Connect

    Schleper, M.A.

    1981-06-15

    A heat-exchanging fireplace was installed in a 2000 square foot home and the standard air distribution equipment was ducted directly to the forced-air heating system of the home. The standard air distribution equipment for the fireplace included two squirrel-cage blowers which were connected to a thermostat, allowing a choice of temperature ranges; and a snap disc thermostat was used to disconnect the blowers in order to avoid blowing cold air after the fire died out. Arranged in this manner, one is able to set the regular home thermostat a few degrees lower than the fireplace thermostat, and this will allow the regular heating system to turn on after the fire has gone out in the fireplace. Energy consumption in both the fireplace and the conventional heating system was monitored throughout a heating season and then compared with past heating seasons when only a conventional heating system was used.

  13. 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.

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

    SciTech Connect

    Yeh, Y.S.; Chen, S.S. . Nuclear Engineering Dept.; Argonne National Lab., IL )

    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.

  15. Near-Term Laser Launch Capability: The Heat Exchanger Thruster

    NASA Astrophysics Data System (ADS)

    Kare, Jordin T.

    2003-05-01

    The heat exchanger (HX) thruster concept uses a lightweight (up to 1 MW/kg) flat-plate heat exchanger to couple laser energy into flowing hydrogen. Hot gas is exhausted via a conventional nozzle to generate thrust. The HX thruster has several advantages over ablative thrusters, including high efficiency, design flexibility, and operation with any type of laser. Operating the heat exchanger at a modest exhaust temperature, nominally 1000 C, allows it to be fabricated cheaply, while providing sufficient specific impulse (~600 seconds) for a single-stage vehicle to reach orbit with a useful payload; a nominal vehicle design is described. The HX thruster is also comparatively easy to develop and test, and offers an extremely promising route to near-term demonstration of laser launch.

  16. Potential polymer concrete heat exchanger tubes for corrosive environments

    SciTech Connect

    Fontana, J.J.; Reams, W.; Cheng, H.C.

    1986-11-01

    It has long been known that carbon steel exposed to some geothermal brines is aggressively attacked, and large corrosion allowances must be made in the design of piping used in such environments. In addition, scaling of the pipes reduces the flow through within a short period of time. Several high temperature polymer concretes have been developed which can be used as non-corrosive liner materials. In addition, polymer concretes with high thermal conductivities have been developed which may be used as heat exchanger tubes for geothermal brines. Studies have indicated that polymer concretes will not scale as rapidly as carbon steel does, thus making them attractive alternatives for heat exchanger tubes. Thin walled, thermally conductive polymer concrete tubes have been made that can withstand pressures >4.1 MPa at 150/sup 0/C without leaking. Continuing studies are being made to characterize these materials and evaluate them for heat exchanger applications.

  17. 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.

  18. Heat exchanger selection and design analyses for metal hydride heat pump systems

    SciTech Connect

    Mazzucco, Andrea; Voskuilen, Tyler G.; Waters, Essene L.; Pourpoint, Timothee L.; Rokni, Masoud

    2016-01-01

    This paper presents a design analysis for the development of highly efficient heat exchangers within stationary metal hydride heat pumps. The design constraints and selected performance criteria are applied to three representative heat exchangers. The proposed thermal model can be applied to select the most efficient heat exchanger design and provides outcomes generally valid in a pre-design stage. Heat transfer effectiveness is the principal performance parameter guiding the selection analysis, the results of which appear to be mildly (up to 13%) affected by the specific Nusselt correlation used. The thermo-physical properties of the heat transfer medium and geometrical parameters are varied in the sensitivity analysis, suggesting that the length of independent tubes is the physical parameter that influences the performance of the heat exchangers the most. The practical operative regions for each heat exchanger are identified by finding the conditions over which the heat removal from the solid bed enables a complete and continuous hydriding reaction. The most efficient solution is a design example that achieves the target effectiveness of 95%.

  19. The influence of a radiated heat exchanger surface on heat transfer

    NASA Astrophysics Data System (ADS)

    Morel, Sławomir

    2015-09-01

    The experiment leads to establish the influence of radiated surface development heat exchangers on the values of heat flux transferred with water flowing through the exchangers and placed in electric furnace chamber. The values of emissivity coefficients are given for the investigated metal and ceramic coatings. Analytical calculations have been made for the effect of the heating medium (flame) - uncoated wall and then heating medium (flame) - coated wall reciprocal emissivity coefficients. Analysis of the values of exchanged heat flux were also realized. Based on the measurement results for the base coating properties, these most suitable for spraying the walls of furnaces and heat exchangers were selected, and determined by the intensification of heat exchange effect. These coatings were used to spray the walls of a laboratory waste-heat boiler, and then measurements of fluxes of heat absorbed by the cooling water flowing through the boiler tubes covered with different type coatings were made. Laboratory tests and calculations were also confirmed by the results of full-scale operation on the metallurgical equipment.

  20. 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.

  1. Heat exchanger selection and design analyses for metal hydride heat pump systems

    DOE PAGES

    Mazzucco, Andrea; Voskuilen, Tyler G.; Waters, Essene L.; ...

    2016-01-01

    This paper presents a design analysis for the development of highly efficient heat exchangers within stationary metal hydride heat pumps. The design constraints and selected performance criteria are applied to three representative heat exchangers. The proposed thermal model can be applied to select the most efficient heat exchanger design and provides outcomes generally valid in a pre-design stage. Heat transfer effectiveness is the principal performance parameter guiding the selection analysis, the results of which appear to be mildly (up to 13%) affected by the specific Nusselt correlation used. The thermo-physical properties of the heat transfer medium and geometrical parameters aremore » varied in the sensitivity analysis, suggesting that the length of independent tubes is the physical parameter that influences the performance of the heat exchangers the most. The practical operative regions for each heat exchanger are identified by finding the conditions over which the heat removal from the solid bed enables a complete and continuous hydriding reaction. The most efficient solution is a design example that achieves the target effectiveness of 95%.« less

  2. 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.

  3. Subsurface environment database for application of ground heat exchanger system

    NASA Astrophysics Data System (ADS)

    Hamamoto, H.; Hachinohe, S.; Shiraishi, H.; Takashi, I.; Sasaka, K.; Miyakoshi, A.; Goto, S.

    2010-12-01

    Ground heat exchanger system is economical and environmentally friendly technology and widely used in Europe and North America, while it is rarely used in Japan. One of the causes is relatively complex topography and geological structure in Japan in comparison with those in Europe and North America. Complex structures produce regional differences in subsurface thermal properties and temperature structure, leading to regional variation in efficiency of heat exchanger system. It is thus important to evaluate available subsurface heat energy through thermal response tests and/or numerical simulation and to design appropriate systems (depth and number of boreholes for heat exchange). Information on subsurface environment in target areas is necessary for evaluation of potential subsurface heat energy, but little information has been published. Center for Environmental Science in Saitama is a research institute established by a local government, Saitama prefecture, which is located on the north of Tokyo and has a population of over seven million. We have been collecting various subsurface environmental data in Saitama (e.g., lithological column data on over 10,000 boreholes). We have compiled the accumulated data and obtained new data (geological information, subsurface temperature distribution, and hydrogeological properties) to construct a database for application of ground heat exchanger systems in Saitama. It is important to estimate demand for heat energy in the target areas as well as available subsurface heat energy. We therefore compile meteorological data (air temperature and solar radiation) necessary for estimation for the demand and investigate regional variation in meteorological condition. We intend to disclose the database and research products using web GIS (geographic information system) in the future. It will assist spread of ground heat exchanger systems in the target areas. Investigation methods of subsurface environment survey and database

  4. Mechanical Properties of Heat Exchanger Tube Materials at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Kahl, Sören; Zajac, Jozefa; Ekström, Hans-Erik

    Since automotive heat exchangers are operated at elevated temperatures and under varying pressures, both static and dynamic mechanical properties should be known at the relevant temperatures. We have collected elevated-temperature tensile test data, elevated-temperature stress amplitude-fatigue life data, and creep-rupture data in a systematic fashion over the past years. For thin, soft, and braze-simulated heat exchanger tube materials tested inside closed furnaces, none of the well-established methods for crack detection and observation can be applied. In our contribution, we present a simple statistical method to estimate the time required for crack initiation.

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

    DOEpatents

    Gamble, Robert L.; Garcia-Mallol, Juan A.

    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.

  6. 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.

  7. Circumferential arrays used for UT endoscopy on heat exchanger tubes

    SciTech Connect

    Liebig, V.; Koehler, B.; Gebhardt, W.; Kroening, M.; Mummert, K.

    1994-12-31

    Corrosion damage on steam generator (SG) heat exchanger tubes of nuclear power plants has repeatedly been the cause of limitations in availability and steam generator replacements. The objective here is to develop an ultrasonic testing (UT) method which enables damage phenomena on SG heat exchanger tubes to be determined and assessed. The method is based on the use of miniaturized ultrasonic array probes of piezoelectric composite materials whose characteristic impedance can be well matched to the load medium (water) and therefore guarantees a high signal efficiency with a good time resolution.

  8. Practical design of heat exchangers for dilution refrigerators: part 2

    NASA Astrophysics Data System (ADS)

    Oda, Y.; Fujii, G.; Ono, T.; Nagano, H.

    A dilution refrigerator with a He 3 circulation rate 80-730 μmols -1 and a minimum temperature of 2.85 mK which is continuously maintained has been built. Discrete heat exchangers with pressed metal (Cu and Ag) powder are used. The heat exchangers are newly developed, based on the analysis of Radebaugh and Siegwarth. The machine is designed for many purposes such as the base of nuclear cooling and studies of general solid state physics. The design, construction and performance of this refrigerator are described.

  9. Thermal conductivity of backfill materials for inground heat exchangers

    SciTech Connect

    Shadley, J.T.; Den Braven, K.R.

    1995-11-01

    The thermal conductivity of the material immediately surrounding the heat exchangers in a vertical borehole directly affects the performance and costs of a ground-coupled heat pump (GCHP) system by regulating the flow of energy to or from the ground. Many properties of the backfill material such as moisture content, composition, specific heat and density influence the thermal conductivity. The thermal conductivities of a wide variety of pure backfill materials and mixtures were measured. All the materials examined were compared with a standard bentonite backfill. Saturated natural sandy soil was the backfill material with the highest thermal conductivity. One attractive mixture consists of a pure silica sand, acrylic latex, and graphite. This mixture forms a solid backfill around the heat exchanger. Yet, the attractiveness of any backfill material combination remains very location and application dependent, varying with the native soils at the site, and the mode in which the GCHP is to be used.

  10. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Schunk, Richard G.

    2011-01-01

    An active thermal control system architecture has been modified to include a regenerative heat exchanger (regenerator) inboard of the radiator. Rather than using a radiator bypass valve a regenerative heat exchanger is placed inboard of the radiators. A regenerator cold side bypass valve is used to set the return temperature. During operation, the regenerator bypass flow is varied, mixing cold radiator return fluid and warm regenerator outlet fluid to maintain the system setpoint. At the lowest heat load for stable operation, the bypass flow is closed off, sending all of the flow through the regenerator. This lowers the radiator inlet temperature well below the system set-point while maintaining full flow through the radiators. By using a regenerator bypass flow control to maintain system setpoint, the required minimum heat load to avoid radiator freezing can be reduced by more than half compared to a radiator bypass system.

  11. ASME code considerations for the compact heat exchanger

    SciTech Connect

    Nestell, James; Sham, Sam

    2015-08-31

    The mission of the U.S. Department of Energy (DOE), Office of Nuclear Energy is to advance nuclear power in order to meet the nation's energy, environmental, and energy security needs. Advanced high temperature reactor systems such as sodium fast reactors and high and very high temperature gas-cooled reactors are being considered for the next generation of nuclear reactor plant designs. The coolants for these high temperature reactor systems include liquid sodium and helium gas. Supercritical carbon dioxide (sCO₂), a fluid at a temperature and pressure above the supercritical point of CO₂, is currently being investigated by DOE as a working fluid for a nuclear or fossil-heated recompression closed Brayton cycle energy conversion system that operates at 550°C (1022°F) at 200 bar (2900 psi). Higher operating temperatures are envisioned in future developments. All of these design concepts require a highly effective heat exchanger that transfers heat from the nuclear or chemical reactor to the chemical process fluid or the to the power cycle. In the nuclear designs described above, heat is transferred from the primary to the secondary loop via an intermediate heat exchanger (IHX) and then from the intermediate loop to either a working process or a power cycle via a secondary heat exchanger (SHX). The IHX is a component in the primary coolant loop which will be classified as "safety related." The intermediate loop will likely be classified as "not safety related but important to safety." These safety classifications have a direct bearing on heat exchanger design approaches for the IHX and SHX. The very high temperatures being considered for the VHTR will require the use of very high temperature alloys for the IHX and SHX. Material cost considerations alone will dictate that the IHX and SHX be highly effective; that is, provide high heat transfer area in a small volume. This feature must be accompanied by low pressure drop and mechanical reliability and robustness

  12. Selection, Evaluation, And Rating of Compact Heat exchangers

    SciTech Connect

    Carlson, Matt

    2014-10-07

    SEARCH determines and optimizes the design of a compact heat exchanger for specified process conditions. The user specifies process boundary conditions including the fluid state and flow rate and SEARCH will determine the optimum flow arrangement, channel geometry, and mechanical design for the unit. Fluids are modeled using NUST Refprop or tabulated values. A variety of thermal-hydraulic correlations are available including user-defined equations to accurately capture the heat transfer and pressure drop behavior of the process flows.

  13. Fuel type impact at heat exchanger performance

    NASA Astrophysics Data System (ADS)

    Durčanský, Peter; Patsch, Marek; Jandačka, Jozef

    2016-06-01

    Possible solution to the increasing energy consumption in the world may be use of alternative energy sources in micro-cogeneration in combination with increasing energy effectiveness. The use of renewable sources, such as biomass, represents an important contribution to possible solution of this problem. When designing a new heat source it is required to follow a number of technical regulations and recommendations. The proposed combustion furnace is intended for combustion of biomass, either piece, or in the form of wood biomass. But the combustion is not only affected by design of furnace, but also by fuel and its properties.

  14. Heat Exchange After Atropine and Pralidoxime Administration

    DTIC Science & Technology

    1986-12-01

    calculated from weight changes. b,,Z&-expected result -of 4 tropine injection, decreased eccrine sweating 6-66%v po<.05) and elevated esophageal W-O- ’ and...The expected result of atropine injection, decreased eccrine sweating (-60%, pɘ.05) and elevated esophageal (+0.4 0C, pɘ.05) and skin temperatures...heat, pralidoxime chloride, sweating rate vii r-1 INTRODUCTION Eccrine sweat gland activity is depressed by systemic or local atropine administration

  15. 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.

  16. Heat transfer characteristics of a new helically coiled crimped spiral finned tube heat exchanger

    NASA Astrophysics Data System (ADS)

    Srisawad, Kwanchanok; Wongwises, Somchai

    2009-02-01

    In the present study, the heat transfer characteristics in dry surface conditions of a new type of heat exchanger, namely a helically coiled finned tube heat exchanger, is experimentally investigated. The test section, which is a helically coiled fined tube heat exchanger, consists of a shell and a helical coil unit. The helical coil unit consists of four concentric helically coiled tubes of different diameters. Each tube is constructed by bending straight copper tube into a helical coil. Aluminium crimped spiral fins with thickness of 0.5 mm and outer diameter of 28.25 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Ambient air is used as a working fluid in the shell side while hot water is used for the tube-side. The test runs are done at air mass flow rates ranging between 0.04 and 0.13 kg/s. The water mass flow rates are between 0.2 and 0.4 kg/s. The water temperatures are between 40 and 50°C. The effects of the inlet conditions of both working fluids flowing through the heat exchanger on the heat transfer coefficients are discussed. The air-side heat transfer coefficient presented in term of the Colburn J factor is proportional to inlet-water temperature and water mass flow rate. The heat exchanger effectiveness tends to increase with increasing water mass flow rate and also slightly increases with increasing inlet water temperature.

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

    DOEpatents

    Phillips, Benjamin A.; Zawacki, Thomas 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.

  18. 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.

  19. Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Lacomini, Christie; Paul, Heather L.

    2009-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation gas of a PLSS is collected using a CO2-selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat exchanger using water or liquid carbon dioxide (L CO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. The water condensation from the ventilation gas represents a significant source of potential energy for the warming of the adsorbent bed as it represents as much as half of the energy potential in the moist ventilation gas. Designing a heat exchanger to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously.

  20. Initial characterization of a modular heat exchanger with an integral heat pipe

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    1989-01-01

    As part of the Civil Space Technology Initiative (CSTI) Advanced Technology program, a conceptual design of the Stirling space engine (SSE) was generated. The overall goal of the CSTI high capacity power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The free-piston Stirling engine (FPSE) was chosen as the growth option in the CSTI program. A major goal during the conceptual design of the SSE was to reduce the number of critical joints. One area of concern was the heat exchanger assemblies that typically have the majority of critical joints. The solution proposed in the SSE conceptual design used 40 modular heat exchangers. Each module has its own integral heat pipe to transport heat from the heat source to the engine. A demonstration of the modular concept was undertaken before committing to the detailed design of the SSE heat exchangers. An existing FPSE was modified as a test bed for modular heat exchanger evaluation. The engine incorporated three heat exchanger modules, each having a sodium filled heat pipe. The thermal loading of these modules was intended to be similar to the conditions projected for the SSE modules. The engine was assembled and tests are underway. The design and fabrication of the heat exchanger modules and the engine used for these tests were described. Evaluation of the individual heat pipes before installation in the engine is described. The initial test results with the modules in operation on the engine were presented. Future tests involving the engine were outlined.

  1. A novel compact heat exchanger using gap flow mechanism

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed

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

    2015-02-01

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

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

    SciTech Connect

    Mittereder, Nick; Poerschke, Andrew

    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.

  4. 40 CFR 63.654 - Heat exchange systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Emission Standards for Hazardous Air Pollutants From Petroleum Refineries § 63.654 Heat exchange systems..., Sampling Procedures Manual, Appendix P: Cooling Tower Monitoring, prepared by Texas Commission on..., dated January 2003, Sampling Procedures Manual, Appendix P: Cooling Tower Monitoring, prepared by Texas...

  5. Finned Tube With Vortex Generators For A Heat Exchanger.

    DOEpatents

    Sohal, Monohar S.; O'Brien, James E.

    2004-09-14

    A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

  6. Finned Tube With Vortex Generators For A Heat Exchanger.

    DOEpatents

    Sohal, Manohar S.; O'Brien, James E.

    2005-12-20

    A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

  7. Teaching Heat Exchanger Network Synthesis Using Interactive Microcomputer Graphics.

    ERIC Educational Resources Information Center

    Dixon, Anthony G.

    1987-01-01

    Describes the Heat Exchanger Network Synthesis (HENS) program used at Worcester Polytechnic Institute (Massachusetts) as an aid to teaching the energy integration step in process design. Focuses on the benefits of the computer graphics used in the program to increase the speed of generating and changing networks. (TW)

  8. Numerical Simulations of Particle Deposition in Metal Foam Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Sauret, Emilie; Saha, Suvash C.; Gu, Yuantong

    2013-01-01

    Australia is a high-potential country for geothermal power with reserves currently estimated in the tens of millions of petajoules, enough to power the nation for at least 1000 years at current usage. However, these resources are mainly located in isolated arid regions where water is scarce. Therefore, wet cooling systems for geothermal plants in Australia are the least attractive solution and thus air-cooled heat exchangers are preferred. In order to increase the efficiency of such heat exchangers, metal foams have been used. One issue raised by this solution is the fouling caused by dust deposition. In this case, the heat transfer characteristics of the metal foam heat exchanger can dramatically deteriorate. Exploring the particle deposition property in the metal foam exchanger becomes crucial. This paper is a numerical investigation aimed to address this issue. Two-dimensional (2D) numerical simulations of a standard one-row tube bundle wrapped with metal foam in cross-flow are performed and highlight preferential particle deposition areas.

  9. Heat-Exchange Fluids for Sulfuric Acid Vaporizers

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1982-01-01

    Some fluorine-substituted organic materials meet criteria for heat-exchange fluids in contact with sulfuric acid. Most promising of these are perfluoropropylene oxide polymers with degree of polymerization (DP) between 10 and 50. It is desirable to have DP in high range because vapor pressure of material decreases as DP increases, and high-DP liquids have lower loss due to vaporization.

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

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1981-01-01

    A series of liquids have been screened as candidate heat exchange fluids for service in thermochemical cycles that involve the vaporization of sulfuric acid. The required chemical and physical criteria of the liquids is described with the results of some preliminary high temperature test data presented.

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

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    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.

  12. 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.

  13. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... subpart shall monitor each heat exchange system used to cool process equipment in a chemical manufacturing process unit meeting the conditions of § 63.100 (b)(1) through (b)(3) of this subpart, except for chemical...

  14. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... subpart shall monitor each heat exchange system used to cool process equipment in a chemical manufacturing process unit meeting the conditions of § 63.100 (b)(1) through (b)(3) of this subpart, except for chemical...

  15. 40 CFR 63.104 - Heat exchange system requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... subpart shall monitor each heat exchange system used to cool process equipment in a chemical manufacturing process unit meeting the conditions of § 63.100 (b)(1) through (b)(3) of this subpart, except for chemical...

  16. Integral collector storage system with heat exchange apparatus

    DOEpatents

    Rhodes, Richard O.

    2004-04-20

    The present invention relates to an integral solar energy collector storage systems. Generally, an integral collector storage system includes a tank system, a plurality of heat exchange tubes with at least some of the heat exchange tubes arranged within the tank system, a first glazing layer positioned over the tank system and a base plate positioned under the tank system. In one aspect of the invention, the tank system, the first glazing layer an the base plate each include protrusions and a clip is provided to hold the layers together. In another aspect of the invention, the first glazing layer and the base plate are ribbed to provide structural support. This arrangement is particularly useful when these components are formed from plastic. In yet another aspect of the invention, the tank system has a plurality of interconnected tank chambers formed from tubes. In this aspect, a supply header pipe and a fluid return header pipe are provided at a first end of the tank system. The heat exchange tubes have inlets coupled to the supply header pipe and outlets coupled to the return header pipe. With this arrangement, the heat exchange tubes may be inserted into the tank chambers from the first end of the tank system.

  17. Active heat exchange thermal storage unit with pentaerythritol

    SciTech Connect

    Abe, Y.; Kamimoto, M.; Kanari, K.; Ozawa, T.; Sakamoto, R.; Takahashi, Y.

    1984-08-01

    A latent thermal energy storage unit with pentaerythritol was developed, and in the storage unit an active heat transfer enhancement was performed. The phase change material, pentaerythritol, was mixed with a hydrocarbon heat transfer oil and this two-phase storage medium was stirred in a shell-coil type heat exchanger. Through the preliminary experiments in a glass vessel, a lab-scale storage unit of 1 kWh storage capacity was developed. The storage unit demonstrated the feature of latent thermal energy storage; constant-temperature output in both charge and discharge periods was observed.

  18. High temperature heat exchangers for gas turbines and future hypersonic air breathing propulsion

    NASA Astrophysics Data System (ADS)

    Avran, Patrick; Bernard, Pierre

    After surveying the results of ONERA's investigations to date of metallic and ceramic heat exchangers applicable to automotive and aircraft powerplants, which are primarily of finned-tube counterflow configuration, attention is given to the influence of heat-exchanger effectiveness on fuel consumption and exchanger dimensions and weight. Emphasis is placed on the results of studies of cryogenic heat exchangers used by airbreathing hypersonic propulsion systems. The numerical codes developed by ONERA for the modeling of heat exchanger thermodynamics are evaluated.

  19. Dual Expander Cycle Rocket Engine with an Intermediate, Closed-cycle Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Greene, William D. (Inventor)

    2008-01-01

    A dual expander cycle (DEC) rocket engine with an intermediate closed-cycle heat exchanger is provided. A conventional DEC rocket engine has a closed-cycle heat exchanger thermally coupled thereto. The heat exchanger utilizes heat extracted from the engine's fuel circuit to drive the engine's oxidizer turbomachinery.

  20. 40 CFR Table 10 to Subpart Ffff of... - Work Practice Standards for Heat Exchange Systems

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Work Practice Standards for Heat... Standards for Heat Exchange Systems As required in § 63.2490, you must meet each requirement in the following table that applies to your heat exchange systems: For each . . . You must . . . Heat exchange...

  1. Novel Power Electronics Three-Dimensional Heat Exchanger: Preprint

    SciTech Connect

    Bennion, K.; Cousineau, J.; Lustbader, J.; Narumanchi, S.

    2014-08-01

    Electric drive systems for vehicle propulsion enable technologies critical to meeting challenges for energy, environmental, and economic security. Enabling cost-effective electric drive systems requires reductions in inverter power semiconductor area. As critical components of the electric drive system are made smaller, heat removal becomes an increasing challenge. In this paper, we demonstrate an integrated approach to the design of thermal management systems for power semiconductors that matches the passive thermal resistance of the packaging with the active convective cooling performance of the heat exchanger. The heat exchanger concept builds on existing semiconductor thermal management improvements described in literature and patents, which include improved bonded interface materials, direct cooling of the semiconductor packages, and double-sided cooling. The key difference in the described concept is the achievement of high heat transfer performance with less aggressive cooling techniques by optimizing the passive and active heat transfer paths. An extruded aluminum design was selected because of its lower tooling cost, higher performance, and scalability in comparison to cast aluminum. Results demonstrated a heat flux improvement of a factor of two, and a package heat density improvement over 30%, which achieved the thermal performance targets.

  2. The application and design of downhole heat exchanger

    SciTech Connect

    Freeston, D.H.; Pan, H.

    1985-01-01

    The direct use of low temperature geothermal fluids is finding increased usage around the world for space heating, air conditioning, etc. For non-artesian wells the conventional means of circulating the hot fluids is by a downhole turbine pump, with the geofluid being either returned to the reservoir or rejected to waste. The latter is the more common, with results, in some cases, of excessive drawdown of the reservoir and consequent environmental problems. The downhole heat exchanger, utilising a single or multiple ''U'' tube, can alleviate the above problems. Experience at Klamath Falls in Oregon, U.S.A., and at Rotorua and Taupo, New Zealand, shows that these devices are capable, given a good permeable reservoir with temperatures around 100C, of delivering up to 1 MW of thermal energy from a conventional shallow well (50 to 200 m). This paper discusses the application of the downhole heat exchanger for space heating using examples from New Zealand and Klamath Falls systems, and reports a recent study on the parameters necessary to achieve an optimum design. The discussion is based on a laboratory model, a computer simulation an full-scale tests on operational downhole heat exchangers in New Zealand.

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

    SciTech Connect

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

    1983-01-01

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

  4. Heat exchanger efficiently operable alternatively as evaporator or condenser

    DOEpatents

    Ecker, Amir L.

    1981-01-01

    A heat exchanger adapted for efficient operation alternatively as evaporator or condenser and characterized by flexible outer tube having a plurality of inner conduits and check valves sealingly disposed within the outer tube and connected with respective inlet and outlet master flow conduits and configured so as to define a parallel flow path for a first fluid such as a refrigerant when flowed in one direction and to define a serpentine and series flow path for the first fluid when flowed in the opposite direction. The flexible outer tube has a heat exchange fluid, such as water, flowed therethrough by way of suitable inlet and outlet connections. The inner conduits and check valves form a package that is twistable so as to define a spiral annular flow path within the flexible outer tube for the heat exchange fluid. The inner conduits have thin walls of highly efficient heat transfer material for transferring heat between the first and second fluids. Also disclosed are specific materials and configurations.

  5. Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Iacomini, Christie; Paul, Heather, L.

    2008-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation gas of a PLSS is collected using a CO2selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat exchanger using water or liquid carbon dioxide (LCO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. The water condensation from the ventilation gas is a significant heat transfer mechanism for the warming of the adsorbent bed because it represents as much as half of the energy potential in the moist ventilation gas. Designing a heat exchanger to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously. A NASA Small Business Innovative Research (SBIR) Phase 1 contract was performed to investigate condensing and icing as applied to MTSA to enable higher fidelity modeling and assess the impact of geometry variables on CIHX performance for future CIHX design optimization. Specifically, a design tool was created using analytical relations to explore the complex, interdependent design space of a condensing ice heat exchanger. Numerous variables were identified as having nontrivial contributions

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

    NASA Technical Reports Server (NTRS)

    Simon, Terrence W.; Seume, Jorge R.

    1988-01-01

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

  7. Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Iacomini, Christie; Paul, Heather, L.

    2008-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation gas of a PLSS is collected using a CO2selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat exchanger using water or liquid carbon dioxide (LCO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. The water condensation from the ventilation gas is a significant heat transfer mechanism for the warming of the adsorbent bed because it represents as much as half of the energy potential in the moist ventilation gas. Designing a heat exchanger to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously. A NASA Small Business Innovative Research (SBIR) Phase 1 contract was performed to investigate condensing and icing as applied to MTSA to enable higher fidelity modeling and assess the impact of geometry variables on CIHX performance for future CIHX design optimization. Specifically, a design tool was created using analytical relations to explore the complex, interdependent design space of a condensing ice heat exchanger. Numerous variables were identified as having nontrivial contributions

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

    NASA Astrophysics Data System (ADS)

    Simon, Terrence W.; Seume, Jorge R.

    1988-03-01

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

  9. 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).

  10. Heat-Transfer and Friction Factor Design Data for All-Metal Compact Heat Exchangers

    DTIC Science & Technology

    1989-03-01

    modeled as a "matrix," similar to a porous media , but the correlation parameters generated didn’t describe the system correctly. Finally, the plate...40. 3. WI.M. Kays, and A.L. London, Compact Heat Exchangers, ?nd Edition, McGraw Hill, New York, 1964. 4. McAdams, Heat Transmision , 3rd Edition

  11. Investigation of heat transfer inside a PCM-air heat exchanger: a numerical parametric study

    NASA Astrophysics Data System (ADS)

    Herbinger, Florent; Bhouri, Maha; Groulx, Dominic

    2017-07-01

    In this paper, the use of PCMs for thermal storage of energy in HVAC applications was investigated by studying numerically the thermal performance of a PCM-air heat exchanger. The PCM used in this study was dodecanoic acid. A symmetric 3D model, incorporating conductive and convective heat transfer (air only) as well as laminar flow, was created in COMSOL Multiphysics 5.0. Simulations examined the dependence of the heat transfer rate on the temperature and velocity of the incoming air as well as the size of the channels in the heat exchanger. Results indicated that small channels size lead to a higher heat transfer rates. A similar trend was also obtained for high incoming air temperature, whereas the heat transfer rate was less sensitive to the incoming air velocity.

  12. Next Generation Nuclear Plant Intermediate Heat Exchanger Acquisition Strategy

    SciTech Connect

    Mizia, Ronald Eugene

    2008-04-01

    DOE has selected the High Temperature Gas-cooled Reactor (HTGR) design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production. It will have an outlet gas temperature in the range of 900°C to 950°C and a plant design service life of 60 years. The reactor design will be a graphite moderated, helium cooled, prismatic or pebble-bed reactor, and use low-enriched uranium, TRISO-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Materials Research and Development (R&D) Program is responsible for performing R&D on likely NGNP materials in support of the NGNP design, licensing, and construction activities. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while at the same time setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. The purpose of this report is to address the acquisition strategy for the NGNP Intermediate Heat Exchanger (IHX).This component will be operated in flowing, impure helium on the primary and secondary side at temperatures up to 950°C. There are major high temperature design, materials availability, and fabrication issues that need to be addressed. The prospective materials are Alloys 617, 230, 800H and X, with Alloy 617 being the leading candidate for the use at 950°C. The material delivery schedule for these materials does not pose a problem for a 2018 start up as the vendors can quote reasonable delivery times at the moment. The product forms and amount needed must be finalized as soon as possible. An

  13. Pulse Detonation Engine Thrust Tube Heat Exchanger for Flash Vaporization and Supercritical Heating of JP-8

    DTIC Science & Technology

    2005-03-01

    was 38.1 cm long. The short heat exchanger did not have the helical flow coil installed. The same size inlet and outlet fittings were used and...three at the top and three at the bottom of the heat exchanger. The axial positions were determined by the helical coil geometry within the heat...HX Inlet HX Outlet Helical Coil - External Thermocouple T-1 B-1B-3 B-2 T-3 T-2 B - Bottom T - Top Figure 39. External thermocouple

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

    NASA Astrophysics Data System (ADS)

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

    1980-04-01

    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. 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.

  16. 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.

  17. Thermoacoustics with idealized heat exchangers and no stack.

    PubMed

    Wakeland, Ray Scott; Keolian, Robert M

    2002-06-01

    A model is developed for thermoacoustic devices that have neither stack nor regenerator. These "no-stack" devices have heat exchangers placed close together in an acoustic standing wave of sufficient amplitude to allow individual parcels of gas to enter both exchangers. The assumption of perfect heat transfer in the exchangers facilitates the construction of a simple model similar to the "moving parcel picture" that is used as a first approach to stack-based engines and refrigerators. The model no-stack cycle is shown to have potentially greater inviscid efficiency than a comparable stack model. However, losses from flow through the heat exchangers and on the walls of the enclosure are greater than those in a stack-based device due to the increased acoustic pressure amplitude. Estimates of these losses in refrigerators are used to compare the possible efficiencies of real refrigerators made with or without a stack. The model predicts that no-stack refrigerators can exceed stack-based refrigerators in efficiency, but only for particular enclosure geometries.

  18. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2012-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  19. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2011-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  20. Airside performances of finned eight-tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Li, Junming

    2016-11-01

    For applications in the relatively low temperature refrigeration systems with large constant temperature bath, the present work performed the experimental studies on the airside performances of the staggered finned eight-tube heat exchangers with large fin pitches. The airside heat transfer coefficients and pressure drops for three fin types and two fin pitches are obtained and analyzed. The heat transfer enhancement with louver fins is 11-16 % higher than the flat fins and that with sinusoidal corrugated fins is 1.1-3.4 % higher than the flat fins. Higher Re brings larger enhancement for various fins. Fin pitches show weak influence on heat transfer for eight tube rows. However, effects of fin pitch on heat transfer for both the sinusoidal corrugation and the louvered fin are larger than the flat fins and they are different from those for N ≤ 6. Airside Colburn j factor are compared with previous and it could be concluded that the airside j factor is almost constant for finned tube heat exchangers with eight tubes and large fin pitches, when Re is from 250 to 2500. The results are different from previous studies for fewer tube rows.

  1. Heat exchange between a bouncing drop and a superhydrophobic substrate.

    PubMed

    Shiri, Samira; Bird, James C

    2017-07-03

    The ability to enhance or limit heat transfer between a surface and impacting drops is important in applications ranging from industrial spray cooling to the thermal regulation of animals in cold rain. When these surfaces are micro/nanotextured and hydrophobic, or superhydrophobic, an impacting drop can spread and recoil over trapped air pockets so quickly that it can completely bounce off the surface. It is expected that this short contact time limits heat transfer; however, the amount of heat exchanged and precise role of various parameters, such as the drop size, are unknown. Here, we demonstrate that the amount of heat exchanged between a millimeter-sized water drop and a superhydrophobic surface will be orders of magnitude less when the drop bounces than when it sticks. Through a combination of experiments and theory, we show that the heat transfer process on superhydrophobic surfaces is independent of the trapped gas. Instead, we find that, for a given spreading factor, the small fraction of heat transferred is controlled by two dimensionless groupings of physical parameters: one that relates the thermal properties of the drop and bulk substrate and the other that characterizes the relative thermal, inertial, and capillary dynamics of the drop.

  2. Subscale Water Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik; Hansen, Scott

    2016-01-01

    Supplemental heat rejection devices are required in many spacecraft as the radiators are not sized to meet the full heat rejection demand. One means of obtaining additional heat rejection is through the use of phase change material heat exchangers (PCM HX's). PCM HX's utilize phase change to store energy in unfavorable thermal environments (melting) and reject the energy in favorable environments (freezing). Traditionally, wax has been used as a PCM on spacecraft. However, water is an attractive alternative because it is capable of storing about 40% more energy per unit mass due to its higher latent heat of fusion. The significant problem in using water as a PCM is its expansion while freezing, leading to structural integrity concerns when housed in an enclosed heat exchanger volume. Significant investigation and development has taken place over the past five years to understand and overcome the problems associated with water PCM HX's. This paper reports on the final efforts by Johnson Space Center's Thermal Systems Branch to develop a water based PCM HX. The test article developed and reported on is a subscale version of the full-scale water-based PCM HX's constructed by Mezzo Technologies. The subscale unit was designed by applying prior research on freeze front propagation and previous full-scale water PCM HX development. Design modifications to the subscale unit included use of urethane bladder, decreased aspect ratio, perforated protection sheet, and use of additional mid-plates. Testing of the subscale unit was successful and 150 cycles were completed without fail.

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

    SciTech Connect

    Xing, Lu; Cullin, James; Spitler, Jeffery; Im, Piljae; Fisher, Daniel

    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 factors, such as soil freezing and evapotranspiration. The FHX numerical model is validated with one year of experimental data collected at an experimental house located near Oak Ridge, Tennessee. The model shows good agreement with the experimental data-heat pump entering fluid temperatures typically within 1 C (1.8 F) - with minor discrepancies due to approximations, such as constant moisture content throughout the year, uniform evapotranspiration over the seasons, and lack of ground shading in the model.

  4. Flexible, reusable fiberglass insulation tailored to fit valves, heat exchangers

    SciTech Connect

    Gockenbach, L.G.; Singleton, D.; Toy, D.A.

    1986-06-01

    About 120,000 bbl/day of crude oil are refined into gasoline at the Marathon Petroleum refinery in Robinson, IL. Built in the early part of the century, the Robinson refinery has been continually updated and modernized in response to improving technology. To control heat loss on some of the unusually shaped and previously uninsulated process equipment, Marathon engineering personnel initiated a program to systematically evaluate and insulate these pieces of equipment. Primarily, over 500 valves and heat exchanger heads were losing heat which had been estimated to cost hundreds of thousands of dollars per year. The plant performed on-site evaluations of several types of removable insulation covers. The primary differences and deciding factors were in construction detail - particularly in the fasteners. Marathon chose lace-up fastening insulation covers because plant evaluation found them to be the best. Also the manufacturer agreed to provide tailor-made covers for all of the valves and heat exchanger heads. Service from the manufacturer through an insulation contractor located in Robinson was also a plus. The local contractor, working in conjunction with the manufacturer, conducted an in-plant survey that confirmed the already mentioned heat loss cost in the $100,000s range. It was also determined that an equipment temperature somewhere between 150 and 200/sup 0/F was the lowest temperature at which to economically install insulation. Marathon has been pleased with the performance of the insulation covers which reduce heat loss and, as an incidental benefit, provide personnel safety from hot surfaces. An important benefit has been the removability and reusability of the insulation, particularly advantageous on valves and heat exchangers the require frequent access.

  5. 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

    ... 40 Protection of Environment 10 2011-07-01 2011-07-01 false What heat exchange systems are exempt... Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What heat exchange systems are exempt from the requirements of this subpart? Your heat exchange system...

  6. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 11 2012-07-01 2012-07-01 false What heat exchange systems are exempt... Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What heat exchange systems are exempt from the requirements of this subpart? Your heat exchange system is...

  7. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 11 2014-07-01 2014-07-01 false What heat exchange systems are exempt... Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What heat exchange systems are exempt from the requirements of this subpart? Your heat exchange system is...

  8. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 11 2013-07-01 2013-07-01 false What heat exchange systems are exempt... Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What heat exchange systems are exempt from the requirements of this subpart? Your heat exchange system is...

  9. 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.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

    Kraft, G. A.

    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 1979. Both engines had a bypass ratio of 4.5 and a fan pressure ratio of 2.0. The design thrust of the engines was in the 4000 N range at a cruise condition of Mach 0.98 and 11.6 km. It is shown that heat pipe heat exchangers of this type cause a large weight and size problem for the engine. The penalties were too severe to be overcome by the small uninstalled fuel consumption advantage. The type of heat exchanger should only be considered for small airflow engines in flight applications. Ground applications might prove more suitable and flexible.

  12. X-ray Line Formation by Charge Exchange

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter

    Existing X-ray telescopes have revealed charge exchange to be a key astrophysical process leading to X-ray emission when highly charged ions from such diverse sources as stellar winds, supernova remnants, or galactic super-winds interact with comets, planetary atmospheres, or the interstellar neutral gas. Charge exchange with bare sulfur ions, for example, was proposed as an alternative explanation of the 3.5 keV X-ray feature in the emission of galactic clusters that had been associated with the possible decay of sterile neutrinos. Fe XVII dominates the spectral emission of a large number of astrophysical X-ray sources and, thus, is of prime diagnostic importance, as illustrated in numerous measurements by Chandra and XMM-Newton. Although immense progress has been made in laboratory measurements and spectral calculations of collisional plasmas since the launch of these X-ray observatories, model calculations of the Fe XVII X-ray spectrum still do not yield agreement with astrophysical observations that is completely satisfactory. As a result, charge exchange has been invoked as an alternative explanation for the poor agreement between models and observations. Theoretically, line formation by charge exchange, however, is still only poorly understood both in the case of the rather 'simple'K-shell spectra of hydrogenlike or heliumlike ions, such as Fe XXV and Fe XXVI, and the more complex L-shell spectra of neonlike ions such as Fe XVII. Experimentally, there is only a small set of laboratory measurements involving X-rays from K-shell ions, and almost no measurements of the charge exchange produced X-ray emission involving L-shell ions. Moreover, the existing laboratory measurements have focused mostly on charge exchange processes pertaining to the solar wind interacting with complex (molecular) gases in cometary and planetary atmospheres. By contrast, we propose here to perform X-ray measurements pertaining to astrophysical exchange processes dominated by atomic

  13. (Solar clothes dryer and wastewater heat exchanger). Final report

    SciTech Connect

    Baer, B.F.

    1984-12-04

    The first project investigated the technical possibilities of adapting a domestic electric clothes dryer to utilize solar-heated water as the heat source, replacing electric resistance heat. The second project attempted to extract wastewater heat from a commercial dishwasher to preheat fresh water to be used in the next dish washing cycle. It is felt that the clothes dryer project has met all of intended goals. Although a solar application has some real-world practical problems, the application of a dryer connected directly to the home heating system will prove to be cost-beneficial over the life of a dryer. The additional cost of a heat exchanger is not excessive, and the installation cost, if installed with the initial house plumbing is less than $100. From a practical point of view, the complexity of installing a wastewater heat extracter is considered impractical. The environment in which such equipment must operate is difficult at best, and most restaurants prefer to maintain as simple an operation as possible. If problems were to occur in this type of equipment, the kitchen would effectively be crippled. In conclusion, further research in the concept is not recommended. Recent advances in commercial dishwashers have also considerably reduced the heat losses which accompanied equipment only a few years old.

  14. Laboratory simulation of heat exchange for liquids with Pr > 1: Heat transfer

    NASA Astrophysics Data System (ADS)

    Belyaev, I. A.; Zakharova, O. D.; Krasnoshchekova, T. E.; Sviridov, V. G.; Sukomel, L. A.

    2016-02-01

    Liquid metals are promising heat transfer agents in new-generation nuclear power plants, such as fast-neutron reactors and hybrid tokamaks—fusion neutron sources (FNSs). We have been investigating hydrodynamics and heat exchange of liquid metals for many years, trying to reproduce the conditions close to those in fast reactors and fusion neutron sources. In the latter case, the liquid metal flow takes place in a strong magnetic field and strong thermal loads resulting in development of thermogravitational convection in the flow. In this case, quite dangerous regimes of magnetohydrodynamic (MHD) heat exchange not known earlier may occur that, in combination with other long-known regimes, for example, the growth of hydraulic drag in a strong magnetic field, make the possibility of creating a reliable FNS cooling system with a liquid metal heat carrier problematic. There exists a reasonable alternative to liquid metals in FNS, molten salts, namely, the melt of lithium and beryllium fluorides (Flibe) and the melt of fluorides of alkali metals (Flinak). Molten salts, however, are poorly studied media, and their application requires detailed scientific substantiation. We analyze the modern state of the art of studies in this field. Our contribution is to answer the following question: whether above-mentioned extremely dangerous regimes of MHD heat exchange detected in liquid metals can exist in molten salts. Experiments and numerical simulation were performed in order to answer this question. The experimental test facility represents a water circuit, since water (or water with additions for increasing its electrical conduction) is a convenient medium for laboratory simulation of salt heat exchange in FNS conditions. Local heat transfer coefficients along the heated tube, three-dimensional (along the length and in the cross section, including the viscous sublayer) fields of averaged temperature and temperature pulsations are studied. The probe method for measurements in

  15. 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.

  16. Subterranean heat exchanger for refrigeration air conditioning equipment

    SciTech Connect

    Rothwell, H.

    1980-09-30

    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 chilled) formations whereby the water of the formation stabilizes the temperature around the unit and enables heating and cooling. The sealed unit receives refrigerant from the top which flows along the sidewall at a reduced temperature, thereby condensing on the sidewall and trickling down the sidewall to collect in a sump at the bottom where the compressor pump picks up condensed refrigerant as a liquid and pumps it out of the artesian well to the connected refrigeration equipment.

  17. Heat exchange apparatus and process for rotary kilns

    SciTech Connect

    De Beus, A.J.

    1987-06-30

    This patent describes a heat exchange apparatus for use in a rotary kiln, the heat exchange apparatus comprising: refractory means for transferring heat from an upper heated portion of a rotary kiln above a bed disposed in a lower portion to within the bed as the rotary kiln is rotated. The refractory means comprises: tubular refractory members; means for attaching the refractory means in a spaced apart relationship with an interior wall of the rotary kiln in order to cause the refractory means to pass through the bed with a portion of the bed passing under the refractory means. A portion of the bed passes over the refractory means in order to enhance heat transfer as the rotary kiln is rotated. The means for attaching the refractory means comprises rods supported by stanchions and tubular refractory member disposed on the rods; the means for attaching the refractory means and the refractory means is configured and operative for stirring the bed as the refractory means pass through the bed without significant lifting of the bed to the heated upper portions of the rotary kiln as the rotary kiln is rotated; and compressible refractory spacer means disposed between each tubular refractory member for accommodating heat expansion and compressible refractory sleeve means dispersed between the rods and the tubular refractory members for accommodating heat expansion of the rods. Compressible refractory sleeve means and tubular refractory member sized so that the tubular refractory members are tightly held against the tubular refractory spacer means when the rotary kiln is at operating temperatures in order to inhibit fracture of the tubular refractory member as they pass through the bed.

  18. Investigation of effect of oblique ridges on heat transfer in plate heat exchangers

    NASA Astrophysics Data System (ADS)

    Novosád, Jan; Dvořák, Václav

    2014-03-01

    This article deals with numerical investigation of flow in plate heat exchangers. These are counterflow heat exchangers formed by plates. These plates are shaped by the ridges to intensify heat transfer. The objective of the work is the investigation of effect of straight oblique triangular ridges for increasing of heat transfer and pressure losses. The ridges on adjacent plates intersect and thus form a channel of complex shape. The research includes various types of ridges with different fillets and ridges spacing.The work also investigates the number of ridges that is necessary for optimization calculations. Obtained data are analysed and the heat transfer coefficient and pressure loss are evaluated. Conclusion describes the effect of fillets, ridges pitch and number of ridges.

  19. Thermal design of spiral heat exchangers and heat pipes through global best algorithm

    NASA Astrophysics Data System (ADS)

    Turgut, Oğuz Emrah; Çoban, Mustafa Turhan

    2017-03-01

    This study deals with global best algorithm based thermal design of spiral heat exchangers and heat pipes. Spiral heat exchangers are devices which are highly efficient in extremely dirty and fouling process duties. Spirals inherent in design maintain high heat transfer coefficients while avoiding hazardous effects of fouling and uneven fluid distribution in the channels. Heat pipes have wide usage in industry. Thanks to the two phase cycle which takes part in operation, they can transfer high amount of heat with a negligible temperature gradient. In this work, a new stochastic based optimization method global best algorithm is applied for multi objective optimization of spiral heat exchangers as well as single objective optimization for heat pipes. Global best algorithm is easy-to-implement, free of derivatives and it can be reliably applied to any optimization problem. Case studies taken from the literature approaches are solved by the proposed algorithm and results obtained from the literature approaches are compared with thosed acquired by GBA. Comparisons reveal that GBA attains better results than literature studies in terms of solution accuracy and efficiency.

  20. Simulation of lakes and surface water heat exchangers for design of surface water heat pump systems

    NASA Astrophysics Data System (ADS)

    Conjeevaram Bashyam, Krishna

    Surface Water Heat Pump (SWHP) system utilize surface water bodies, such as ponds, lakes, rivers, and the sea, as heat sources and/or sinks. These systems may be open-loop, circulating water between the surface water body and a heat exchanger on dry land, or closed-loop, utilizing a submerged surface water heat exchanger (SWHE). Both types of SWHP systems have been widely used, but little in the way of design data, design procedures, or energy calculation procedures is available to aid engineers in the design and analysis of these systems. For either type of SWHP system, the ability to predict the evolution of lake temperature with time is an important aspect of needed design and energy analysis procedures. This thesis describes the development and validation of a lake model that is coupled with a surface water heat exchanger model to predict both the lake dynamics (temperature, stratification, ice/snow cover) and the heat transfer performance of different types of SWHE. This one-dimensional model utilizes a detailed surface heat balance model at the upper boundary, a sediment conduction heat transfer model at the lower boundary, and an eddy diffusion model to predict transport within the lake. The lake model is implemented as part of the developed software design tool, which can be used as an aid in the sizing of SWHE used in closed loop SWHP systems.