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Sample records for mantle heat exchanger

  1. A two Layer Convecting Mantle With Exchange : A Unified Model Based on Geochemical, Seismic and Heat Flow Observations

    NASA Astrophysics Data System (ADS)

    Allègre, C. J.; Jaupart, C.; Nolet, G.

    2007-12-01

    -penetrating slabs as emphasized by Fukao and al.(2001) and the recent observation of the large energy spectrum differences at 670 km depth (Gu and al., 2006). We discuss the problem of return flow, which is crucial for both energy budget and convection regime. The recent work on plume by Montelli and al. (2004, 2006) shows the existence of broad plumes in the lower mantle and thin plumes in the upper mantle. d) The estimate of heat flow coming from the lower mantle of 35-32 TW. The work of Davies(1990) and Sleep(1992) shows clearly that this transfer is not the result of plumes reaching the surface, because they correspond at most to 3TW. At the reverse the estimated heat flow carried by the lower mantle plumes is much higher (Nolet and al., 2006). We also discuss the heat flow paradox to explain a Urey ratio of 0.4 with whole mantle convection. In conclusion, we propose mantle with two layers convecting separately but with some exchange of matter, this global exchange corresponding to 1.1024kg since 4.4 Gy. Plume genesis is a two-stage process. Lower mantle plumes heat the Mesosphere boundary layer generating second generation plumes which reach the surface (Allègre and Turcotte; 1983; Allègre, 1987). In the upper mantle itself, we have to distinguish between a vigorously convecting asthenosphere and a sluggish convecting transition zone, both convecting in same cells.

  2. 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.

  3. 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)

  4. Heat sources for mantle plumes

    NASA Astrophysics Data System (ADS)

    Beier, C.; Rushmer, T.; Turner, S. P.

    2008-06-01

    Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. This excess heat in mantle plumes could reflect either (1) an enrichment of the heat-producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay, (2) material transport from core to mantle (either advective or diffusive), or (3) conductive heat transport across the core-mantle boundary. The advective/diffusive transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g., increased 186Os, 187Os, and Fe concentrations. Geophysical and dynamic modeling indicate that at least Afar, Easter, Hawaii, Louisville, and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 0.9 Mg s-1 (Afar) to 8.7 Mg s-1 (Hawaii), providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat-producing elements are the cause of excess heat we looked for correlations between fractionation-corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th, and U are positively correlated with each other (e.g., Hawaii, Iceland, and Galapagos have significantly lower concentrations than, e.g., Tristan da Cunha, the Canary

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  11. 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)

  12. 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.

  13. 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.

  14. 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.

  15. "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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Convectively Driven Heat Flux Heterogeneity in Europa's Mantle

    NASA Astrophysics Data System (ADS)

    Travis, Bryan; Schubert, G.; Palguta, J.

    2006-09-01

    Features on the surface of Europa may reflect non-uniform heating in an underlying ocean due to variations in heat flux at the mantle surface. Pore water convection can generate a spatially heterogeneous heat flux in a fractured, permeable mantle, as illustrated in 2-D computer simulations of the thermal evolution of Europa. The model uses three layers - core, silicate mantle, and H2O (liquid and frozen). Processes active in the model include radiogenic heating, tidal dissipative heating (TDH), thermal diffusion, latent heat of melting and pore water convection. Starting from a cold Europa, radiogenic heating and TDH produce a temperature profile ranging from a peak near 1150 oC in the deep interior to 15 oC at the mantle surface, overlain by an 80 km deep ocean layer at 3 oC, capped by an ice shell approximately 20 km thick. This structure provides initial conditions for our pore water convection simulation. Mantle permeability is based on Earth values. An initial, very strong flow gives way to a weaker quasi-steady pattern of convection in the mantle's porosity. Plumes rise from the mantle at a roughly 10o spacing, through the ocean layer up to the base of the ice. These are typically 50 - 100 km wide at the base of the ice. Plume heat flux is 10-12 W/m2 during the initial transient, but later drops to about 0.5 - 1.5 W/m2. Heating at the base of the ice shell is spatially heterogeneous, but only strong enough to produce significant melt-through during the initial transient. However, strong spatial heterogeneity of basal heating of the ice shell could significantly influence convection in the ice phase. This work was supported by a grant from the Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory and by the NASA Planetary Geology and Geophysics Program.

  4. 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.

  5. Phase Change Material Heat Exchangers

    NASA Video Gallery

    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 ...

  6. 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.

  7. 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.

  8. 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.

  9. Mantle convection with continental drift and heat source around the mantle transition zone

    NASA Astrophysics Data System (ADS)

    Ichikawa, H.; Kameyama, M.; Kawai, K.

    2012-12-01

    Geological studies have suggested that significant amount of granitic crustal materials have been lost from the surface by the delamination (~1.1 km^3/yr) [1], continental collision (~0.4-0.7 km^3/yr) [1, 2], and subduction at ocean-margin (~2.5-3 km^3/yr) [1, 2]. At ocean-margin subduction zones, most of the granitic materials subducted from the surface are expected to be conveyed through subduction channels by viscous drag to 270km depth [Ichikawa el al., in revision]. If so, then the subducted crustal materials might be expected to be trapped in the mid-mantle owing to the density difference from peridotitic materials induced by the phase transition from coesite to stishovite at 270km depth. In other words, strong heat source materials are most likely to be accumulated around the mantle transition zone, at least, near the plate subduction zones. In this study, we conducted two-dimensional numerical experiments of mantle convection with continental drift and a heat source placed around the mantle transition zone, in order to study the effect of the subducted granitic materials drifting around the mantle transition zone. The simulations deal with a time-dependent convection of fluid under the extended Boussinesq approximation in a model of a two-dimensional rectangular box of 2900km height and 11600km width, where a continent and heat source is imposed. We found that the addition of the heat source considerably reduces the time scale of continental drift. In the absence of the heat source, the resulting time scale is too long compared with that of the so-called supercontinent cycle, where the breakup is induced from a plume generated by an insulating effect of the continent. The heat source also causes massive mechanical mixing especially on the upper mantle. The result suggests that the heat source drifting around mantle transition zone can be a possible candidate inducing the supercontinent cycle in an appropriate time scale. [1] Clift, P. D., P. Vannucchi, and

  10. 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.

  11. [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.

  12. 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.

  13. 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.

  14. 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.

  15. Calculations of Shipboard Heat Exchangers,

    DTIC Science & Technology

    1980-04-18

    Constrained moticn is created by the external exciting forces - pumps, compresors , fars, agitators. During the heat exchange distinguish the phenomena...cast tcttozs. (5). fcr fla*/plane covers/caps. FOOTNOTE 1. Is taken stall value. !NDFOCINOIE. Additional requirements fox the dished bcttcss. -w j DOC

  16. 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.

  17. 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.

  18. Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics

    NASA Astrophysics Data System (ADS)

    Surducan, E.; Surducan, V.; Limare, A.; Neamtu, C.; Di Giuseppe, E.

    2014-12-01

    We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm3 convection tank is filled with a water-based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals.

  19. Microwave heating device for internal heating convection experiments, applied to Earth's mantle dynamics

    SciTech Connect

    Surducan, E.; Surducan, V.; Neamtu, C.; Limare, A.; Di Giuseppe, E.

    2014-12-15

    We report the design, construction, and performances of a microwave (MW) heating device for laboratory experiments with non-contact, homogeneous internal heating. The device generates MW radiation at 2.47 GHz from a commercial magnetron supplied by a pulsed current inverter using proprietary, feedback based command and control hardware and software. Specially designed MW launchers direct the MW radiation into the sample through a MW homogenizer, devised to even the MW power distribution into the sample's volume. An adjustable MW circuit adapts the MW generator to the load (i.e., the sample) placed in the experiment chamber. Dedicated heatsinks maintain the MW circuits at constant temperature throughout the experiment. Openings for laser scanning for image acquisition with a CCD camera and for the cooling circuits are protected by special MW filters. The performances of the device are analyzed in terms of heating uniformity, long term output power stability, and load matching. The device is used for small scale experiments simulating Earth's mantle convection. The 30 × 30 × 5 cm{sup 3} convection tank is filled with a water‑based viscous fluid. A uniform and constant temperature is maintained at the upper boundary by an aluminum heat exchanger and adiabatic conditions apply at the tank base. We characterize the geometry of the convective regime as well as its bulk thermal evolution by measuring the velocity field by Particle Image Velocimetry and the temperature field by using Thermochromic Liquid Crystals.

  20. 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.

  1. 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)

  2. 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.

  3. 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…

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Carbon exchange between the mantle and the crust and its effect upon the atmosphere: Today compared to Archean time

    NASA Technical Reports Server (NTRS)

    Desmarais, D.

    1986-01-01

    Paleobiologists now recognize that the Earth's biosphere has been profoundly affected by geologic processes. One very important process is the dissipation of heat which has been generated by radioactivity and/or stored within the earth. Heat flow is responsible for crustal movements and therefore it is the principal architect for constructing the environments (e.g. shallow marine, continental, etc.) wherein life developed and flourished. Heat flow has also influenced the movements of volatile elements (e.g. C, N, H, S, rare gases, etc.) both within the Earth's crust and between the crust and mantle. The inventory of these elements in the Earth's crust is important, not just because some of them constitute the building blocks of organic matter, but also because they influence the biosphere's climate. The purpose of this work is to evaluate how the decline of heat flow over the course of the Earth's history has influenced the carbon inventory in the Earth's crust. Such an evaluation must first consider whether the rate at which carbon is presently being exchanged between the mantle and crust is sufficient to play an important role in controlling the crustal inventory. Secondly, this exchange of carbon must be reevaluated in the context of the Precambrian Earth's environment. One very important consideration is that the upper mantle was perhaps 300 C hotter 3 b.y. ago than it is today.

  13. 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.

  14. 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.

  15. 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.

  16. 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…

  17. 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)

  18. Deep mantle heat flow and thermal evolution of the Earth's core based on thermo-chemical mantle convection

    NASA Astrophysics Data System (ADS)

    Nakagawa, T.; Tackley, P.; Buffett, B.

    2004-12-01

    A coupled core-mantle evolution model that combines the global heat balance in the core with a fully-dynamical thermo-chemical mantle convection [Nakagawa and Tackley, 2004 published in EPSL] is used to investigate the deep mantle heat flow that is required to sustain the magnetic field generated by the geodynamo process. Effects of a radioactive heat source due to potassium in the core are also included in the global heat balance in the Earth??s core. Two important parameters are checked in this study; (1) density variation between depleted hartzbergite and basaltic material (0 to 3 percent) and (2) concentration of radioactive potassium in the core alloy (0ppm to 400ppm). The parameter set that most closely satisfies the criteria of size of the inner core (1220km at present time) is around 2 percent of density difference in a convecting mantle and 200ppm of radioactive heat source in the core. The concentration of potassium in the core is consistent with the geochemical approach [Murthy et al., 2003] but smaller than other successful thermal evolution models [Labrosse, 2003; Nimmo et al., 2004]. Heat flow through the core-mantle boundary and the contribution of radioactive heat sources in the core are consistent with theoretical estimates [e.g. Buffett, 2002] and geochemical constraints [Gessmann and Wood, 2002]. The power available to the geodynamo, based on the predicted heat flow through the core-mantle boundary, is approximately four times greater than the value predicted by numerical models of the geodynamo [Christensen and Kutzner, 2004] but closer to theoretical estimates [e.g. Buffett, 2002].

  19. 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.

  20. 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.

  1. 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.

  2. 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.

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

    SciTech Connect

    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.

  4. 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.

  5. 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.

  6. Effects from equation of state and rheology in dissipative heating in compressible mantle convection

    NASA Technical Reports Server (NTRS)

    Yuen, David A.; Quareni, Francesca; Hong, H.-J.

    1987-01-01

    The effects of compressibility on mantle convection are considered, incorporating the effects of equations of state and rheology in the dissipative heating term of the energy equation. The ways in which compression may raise the interior mantle temperature are explicitly demonstrated, and it is shown how this effect can be used to constrain some of the intrinsic parameters associated with the equation of state in the mantle. It is concluded that the coupling between variable viscosity and equation of state in dissipative heating is potentially an important mechanism in mantle convection. These findings emphasize that rheology, equation of state, and radiogenic heating are all linked to each other by nonlinear thermomechanical couplings.

  7. 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.

  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. 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.

  11. 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.

  12. 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.

  13. Superplumes from the core-mantle boundary to the lithosphere: implications for heat flux.

    PubMed

    Romanowicz, Barbara; Gung, Yuancheng

    2002-04-19

    Three-dimensional modeling of upper-mantle anelastic structure reveals that thermal upwellings associated with the two superplumes, imaged by seismic elastic tomography at the base of the mantle, persist through the upper-mantle transition zone and are deflected horizontally beneath the lithosphere. This explains the unique transverse shear wave isotropy in the central Pacific. We infer that the two superplumes may play a major and stable role in supplying heat and horizontal flow to the low-viscosity asthenospheric channel, lubricating plate motions and feeding hot spots. We suggest that more heat may be carried through the core-mantle boundary than is accounted for by hot spot fluxes alone.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. The temperature of the Icelandic mantle from olivine-spinel aluminum exchange thermometry

    NASA Astrophysics Data System (ADS)

    Matthews, S.; Shorttle, O.; Maclennan, J.

    2016-11-01

    New crystallization temperatures for four eruptions from the Northern Volcanic Zone of Iceland are determined using olivine-spinel aluminum exchange thermometry. Differences in the olivine crystallization temperatures between these eruptions are consistent with variable extents of cooling during fractional crystallization. However, the crystallization temperatures for Iceland are systematically offset to higher temperatures than equivalent olivine-spinel aluminum exchange crystallization temperatures published for MORB, an effect that cannot be explained by fractional crystallization. The highest observed crystallization temperature in Iceland is 1399 ± 20°C. In order to convert crystallization temperatures to mantle potential temperature, we developed a model of multilithology mantle melting that tracks the thermal evolution of the mantle during isentropic decompression melting. With this model, we explore the controls on the temperature at which primary melts begin to crystallize, as a function of source composition and the depth from which the magmas are derived. Large differences (200°C) in crystallization temperature can be generated by variations in mantle lithology, a magma's inferred depth of origin, and its thermal history. Combining this model with independent constraints on the magma volume flux and the effect of lithological heterogeneity on melt production, restricted regions of potential temperature-lithology space can be identified as consistent with the observed crystallization temperatures. Mantle potential temperature is constrained to be 1480-30+37 °C for Iceland and 1318-32+44 °C for MORB.

  6. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240... bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood...

  7. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240... bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood...

  8. New Insights Into the Heat Sources of Mantle Plumes, or: Where Does all the Heat Come From, Heat Producing Elements, Advective or Conductive Heat Flow?

    NASA Astrophysics Data System (ADS)

    Rushmer, T.; Beier, C.; Turner, S.

    2007-12-01

    Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that which is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. Excess heat in mantle plumes could reflect either a) an enrichment of the heat producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay or b) advective or conductive heat transport across the core-mantle boundary. The advective transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g. increased 186Os and Fe concentrations. Geophysical and dynamic modelling indicate that at least Afar, Easter, Hawaii, Louisville and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 1.2 Mgs -1(Afar) to 6.5 Mgs -1 (Hawaii) providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat producing elements are the cause of excess heat we looked for correlations between fractionation corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th and U are positively correlated with each other (e.g. Hawaii, Iceland and Galapagos have significantly lower concentrations than e.g. Tristan da Cunha, the Canary Islands and the Azores). We also find no correlation between currently available Fe

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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).

  19. 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).

  20. The role of heat source for spatio-temporal variations of mantle plumes

    NASA Astrophysics Data System (ADS)

    Kumagai, I.; Yamagishi, Y.; Davaille, A.

    2014-12-01

    Hot mantle plumes ascending from the core-mantle boundary experience a filtering effect by the endothermic phase change at the 660-km discontinuity. Fluid dynamics predicts that some hot mantle plumes stagnate at the phase boundary and locally heat the bottom of the upper mantle. This generates the secondary plumes in the upper mantle originating hotspots volcanic activities on the Earth's surface. Recently, seismic tomographic images around the upper-lower mantle boundary showed that the horizontal scale of the low velocity regions, which corresponds to that of the thermally buoyant heat sources, is the order of 100-1000 km. Although most of the fluid dynamic theories on the thermal plumes have been developed using an assumption that the heat source effect is negligible, the behaviors of the starting plumes in the upper mantle should depend on the size of heat source, which is generated by the hotter plume from the CMB. In order to understand the effects of heater size on the starting plume generation, we have experimentally investigated the behaviors of thermally buoyant plumes using a localized heat source (circular plate heater). The combination of quantitative visualization techniques of temperature (Thermochromic Liquid Crystals) and velocity (Particle Image Velocimetry) fields reveals the transient nature of the plume evolution: a variety of the spatio-tempotal distribution of plumes. Simple scaling laws for their ascent velocity and spacing of the plumes are experimentally determined. We also estimate the onset time of the secondary plumes in the upper mantle which depends on the local characteristics of the thermal boundary layer developing at the upper-lower mantle boundary.

  1. Heat transport in the Hadean mantle: From heat pipes to plates

    NASA Astrophysics Data System (ADS)

    Kankanamge, Duminda G. J.; Moore, William B.

    2016-04-01

    Plate tectonics is a unique feature of Earth, and it plays a dominant role in transporting Earth's internally generated heat. It also governs the nature, shape, and the motion of the surface of Earth. The initiation of plate tectonics on Earth has been difficult to establish observationally, and modeling of the plate breaking process has not consistently accounted for the nature of the preplate tectonic Earth. We have performed numerical simulations of heat transport in the preplate tectonic Earth to understand the transition to plate tectonic behavior. This period of time is dominated by volcanic heat transport called the heat pipe mode of planetary cooling. These simulations of Earth's mantle include heat transport by melting and melt segregation (volcanism), Newtonian temperature-dependent viscosity, and internal heating. We show that when heat pipes are active, the lithosphere thickens and lithospheric isotherms are kept flat by the solidus. Both of these effects act to suppress plate tectonics. As volcanism wanes, conduction begins to control lithospheric thickness, and large slopes arise at the base of the lithosphere. This produces large lithospheric stress and focuses it on the thinner regions of the lithosphere resulting in plate breaking events.

  2. 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... exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger... is subject to contact with exhaust gases; and (4) No exhaust heat exchanger or muff may have...

  3. 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... exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger... is subject to contact with exhaust gases; and (4) No exhaust heat exchanger or muff may have...

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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).

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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)

  3. Plume's buoyancy and heat fluxes from the deep mantle estimated by an instantaneous mantle flow simulation based on the S40RTS global seismic tomography model

    NASA Astrophysics Data System (ADS)

    Yoshida, Masaki

    2012-11-01

    It is still an open question as to how much heat is transported from the deep mantle to the upper mantle by mantle upwelling plumes, which would impose a strong constraint on models of the thermal evolution of the earth. Here I perform numerical computations of instantaneous mantle flow based on a recent highly resolved global seismic tomography model (S40RTS), apply new simple fluid dynamics theories to the plume's radius and velocity, considering a Poiseuille flow assumption and a power-law relationship between the boundary layer thickness and Rayleigh number, and estimate the plume's buoyancy and heat fluxes from the deep lower mantle under varying plume viscosity. The results show that for some major mantle upwelling plumes with localized strong ascent velocity under the South Pacific and Africa, the buoyancy fluxes of each plume beneath the ringwoodite to perovskite + magnesiowüstite ("660-km") phase decomposition boundary are comparable to those inferred from observed hotspot swell volumes on the earth, i.e., on the order of 1 Mg s-1, when the plume viscosity is 1019-1020 Pa s. This result, together with previous numerical simulations of mantle convection and the gentle Clausius-Clapeyron slope for the 660-km phase decomposition derived from recent high-pressure measurements under dehydrated/hydrated conditions in the mantle transition zone, implies that mantle upwelling plumes in the lower mantle penetrate the 660-km phase decomposition boundary without significant loss in thermal buoyancy because of the weak thermal barrier at the 660-km boundary. The total plume heat flux under the South Pacific is estimated to be about 1 TW beneath the 660-km boundary, which is significantly smaller than the core-mantle boundary heat flux. Previously published scaling laws for the plume's radius and velocity based on a plume spacing theory, which explains well plume dynamics in three-dimensional time-dependent mantle convection, suggest that these plume fluxes depend

  4. 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.

  5. 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....

  6. 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....

  7. 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.

  8. 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...

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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.

  2. Mantle heat flow and thermal structure of the northern block of Southern Granulite Terrain, India

    NASA Astrophysics Data System (ADS)

    Manglik, Ajay

    2006-07-01

    Continental shield regions are normally characterized by low-to-moderate mantle heat flow. Archaean Dharwar craton of the Indian continental shield also follows the similar global pattern. However, some recent studies have inferred significantly higher mantle heat flow for the Proterozoic northern block of Southern Granulite Terrain (SGT) in the immediate vicinity of the Dharwar craton by assuming that the radiogenic elements depleted exposed granulites constitute the 45-km-thick crust. In this study, we use four-layered model of the crustal structure revealed by integrated geophysical studies along a geo-transect in this region to estimate the mantle heat flow. The results indicate that: (i) the mantle heat flow of the northern block of SGT is 17 ± 2 mW/m 2, supporting the global pattern, and (ii) the lateral variability of 10-12 mW/m 2 in the surface heat flow within the block is of crustal origin. In terms of temperature, the Moho beneath the eastern Salem-Namakkal region appears to be at 80-100 °C higher temperature than that beneath the western Avinashi region.

  3. Internally heated mantle convection and the thermal and degassing history of the earth

    NASA Technical Reports Server (NTRS)

    Williams, David R.; Pan, Vivian

    1992-01-01

    An internally heated model of parameterized whole mantle convection with viscosity dependent on temperature and volatile content is examined. The model is run for 4l6 Gyr, and temperature, heat flow, degassing and regassing rates, stress, and viscosity are calculated. A nominal case is established which shows good agreement with accepted mantle values. The effects of changing various parameters are also tested. All cases show rapid cooling early in the planet's history and strong self-regulation of viscosity due to the temperature and volatile-content dependence. The effects of weakly stress-dependent viscosity are examined within the bounds of this model and are found to be small. Mantle water is typically outgassed rapidly to reach an equilibrium concentration on a time scale of less than 200 Myr for almost all models, the main exception being for models which start out with temperatures well below the melting temperature.

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

    NASA Astrophysics Data System (ADS)

    Blackwell, D. D.; Thakur, M.

    2007-12-01

    parameters of Birch's Law equation represent the starting place for discussions of lithospheric thermal regime and evolution. The stability of the values of intercept Qo for areas with thermal ages of Paleozoic and older prove that the lithosphere heat flow does not vary significantly with age as is demonstrated in the companion paper. The minimum mantle heat flow for preMesozoic thermal terrains is 20 - 25 mWm-2. This value is consistent with the lack of indication from xenolith data that lithosphere thickness changes with age and with theoretical models of mantle convection.

  5. 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...

  6. 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.

  7. Laboratory convection experiments with internal, noncontact, microwave generated heating, applied to Earth's mantle dynamics

    NASA Astrophysics Data System (ADS)

    Limare, Angela; Surducan, Emanoil; di Giuseppe, Erika; Surducan, Vasile; Neamtu, Camelia; Vilella, Kenny; Fourel, Loic; Farnetani, Cinzia; Kaminski, Edouard; Jaupart, Claude

    2014-05-01

    The thermal evolution of terrestrial planets is controlled by secular cooling and internal heating due to the decay of radiogenic isotopes, two processes which are equivalent from the standpoint of convection dynamics. Few studies have been devoted to the intrinsic characteristics of this form of convection, which are dominated by instabilities of a single boundary layer and which involve a non-isentropic interior thermal structure. Laboratory studies of such convection have been plagued by considerable technical difficulties and have been mostly restricted to aqueous solutions with moderate values of the Prandtl number, contrary to planetary mantles. Here, we describe a new laboratory setup to generate internal heating in controlled conditions based on microwave (MW) absorption. The advantages of our technique include, but are not limited to: (1) a volumetric heat source that can be localized or distributed in space, (2) selectively heating part of the volume with time varying intensity and space distribution. Our tank prototype had horizontal dimensions of 30 cm × 30 cm and 5 cm height. A uniform and constant temperature was maintained at the upper boundary by an aluminium heat exchanger and adiabatic conditions were imposed at the tank base. Experimental fluids were hydroxyethylcellulose - water mixtures whose viscosities were varied within a wide range depending on concentration. Experimental Prandtl numbers were set at values larger than 100. Thermochromic Liquid Crystals (TLC) were used to visualize the temperature field, and the velocity field was determined using Particle Image Velocimetry (PIV). The Rayleigh-Roberts number was varied from 105 to 107. We also conducted numerical simulations in 3D cartesian geometry using Stag-3D (Tackley 1993) to reproduce the experimental conditions, including the tank aspect ratio and the temperature dependence of physical properties. We observed that convection is driven by cold descending plumes generated at the upper

  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. Abnormal high surface heat flow caused by the Emeishan mantle plume

    NASA Astrophysics Data System (ADS)

    Jiang, Qiang; Qiu, Nansheng; Zhu, Chuanqing

    2016-04-01

    It is commonly believed that increase of heat flow caused by a mantle plume is small and transient. Seafloor heat flow data near the Hawaiian hotspot and the Iceland are comparable to that for oceanic lithosphere elsewhere. Numerical modeling of the thermal effect of the Parana large igneous province shows that the added heat flow at the surface caused by the magmatic underplating is less than 5mW/m2. However, the thermal effect of Emeishan mantle plume (EMP) may cause the surface hear-flow abnormally high. The Middle-Late Emeishan mantle plume is located in the western Yangtze Craton. The Sichuan basin, to the northeast of the EMP, is a superimposed basin composed of Paleozoic marine carbonate rocks and Mesozoic-Cenozoic terrestrial clastic rocks. The vitrinite reflectance (Ro) data as a paleogeothermal indicator records an apparent change of thermal regime of the Sichuan basin. The Ro profiles from boreholes and outcrops which are close to the center of the basalt province exhibit a 'dog-leg' style at the unconformity between the Middle and Upper Permian, and they show significantly higher gradients in the lower subsection (pre-Middle Permian) than the Upper subsection (Upper Permian to Mesozoic). Thermal history inversion based on these Ro data shows that the lower subsection experienced a heat flow peak much higher than that of the upper subsection. The abnormal heat flow in the Sichuan basin is consistent with the EMP in temporal and spatial distribution. The high-temperature magmas from deep mantle brought heat to the base of the lithosphere, and then large amount of heat was conducted upwards, resulting in the abnormal high surface heat flow.

  11. 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.

  12. 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…

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Modulation of mantle plumes and heat flow at the core mantle boundary by plate-scale flow: results from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Gonnermann, Helge M.; Jellinek, A. Mark; Richards, Mark A.; Manga, Michael

    2004-09-01

    We report results from analog laboratory experiments, in which a large-scale flow is imposed upon natural convection from a hot boundary layer at the base of a large tank of corn syrup. The experiments show that the subdivision of the convective flow into four regions provides a reasonable conceptual framework for interpreting the effects of large-scale flow on plumes. Region I includes the area of the hot thermal boundary layer (TBL) that is thinned by the large-scale flow, thereby suppressing plumes. Region II encompasses the critically unstable boundary layer where plumes form. Region III is the area above the boundary layer that is devoid of plumes. Region IV comprises the area of hot upwelling and plume conduits. Quantitative analysis of our experiments results in a scaling law for heat flux from the hot boundary and for the spatial extent of plume suppression. When applied to the Earth's core-mantle boundary (CMB), our results suggest that large-scale mantle flow, due to sinking lithospheric plates, can locally thin the TBL and suppress plume formation over large fractions of the CMB. Approximately 30% of heat flow from the core may be due to increased heat flux from plate-scale flow. Furthermore, CMB heat flux is non-uniformly distributed along the CMB, with large areas where heat flux is increased on average by a factor of 2. As a consequence, the convective flow pattern in the outer core may be affected by CMB heat-flux heterogeneity and sensitive to changes in plate-scale mantle flow. Because of plume suppression and 'focusing' of hot mantle from the CMB into zones of upwelling flow, plume conduits (hotspots) are expected to be spatially associated with lower-mantle regions of low seismic velocities, inferred as hot upwelling mantle flow.

  9. 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.

  10. Mantle Convection in a Microwave Oven: New Perspectives for the Internally Heated Convection

    NASA Astrophysics Data System (ADS)

    Limare, A.; Fourel, L.; Surducan, E.; Neamtu, C.; Surducan, V.; Vilella, K.; Farnetani, C. G.; Kaminski, E. C.; Jaupart, C. P.

    2015-12-01

    The thermal evolution of silicate planets is primarily controlled by the balance between internal heating - due to radioactive decay - and heat transport by mantle convection. In the Earth, the problem is particularly complex due to the heterogeneous distribution of heat sources in the mantle and the non-linear coupling between this distribution and convective mixing. To investigate the behaviour of such systems, we have developed a new technology based on microwave absorption to study internally-heated convection in the laboratory. This prototype offers the ability to reach the high Rayleigh-Roberts and Prandtl numbers that are relevant for planetary convection. Our experimental results obtained for a uniform distribution of heat sources were compared to numerical calculations reproducing exactly experimental conditions (3D Cartesian geometry and temperature-dependent physical properties), thereby providing the first cross validation of experimental and numerical studies of convection in internally-heated systems. We find that the thermal boundary layer thickness and interior temperature scale with RaH-1/4, where RaH is the Rayleigh-Roberts number, as theoretically predicted by scaling arguments on the dissipation of kinetic energy. Our microwave-based method offers new perspectives for the study of internally-heated convection in heterogeneous systems which have been out of experimental reach until now. We are able to selectively heat specific regions in the convecting layer, through the careful control of the absorption properties of different miscible fluids. This is analogous to convection in the presence of chemical reservoirs with different concentration of long-lived radioactive isotopes. We shall show results for two different cases: the stability of continental lithosphere over a convective fluid and the evolution of a hidden enriched reservoir in the lowermost mantle.

  11. 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…

  12. 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.

  13. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 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... operation at high temperatures and resistant to corrosion from exhaust gases; (2) There must be means...

  14. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 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... operation at high temperatures and resistant to corrosion from exhaust gases; (2) There must be means...

  15. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 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... operation at high temperatures and resistant to corrosion from exhaust gases; (2) There must be means...

  16. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 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... operation at high temperatures and resistant to corrosion from exhaust gases; (2) There must be means...

  17. 14 CFR 25.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 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... operation at high temperatures and resistant to corrosion from exhaust gases; (2) There must be means...

  18. 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.

  19. Lattice thermal conductivity of lower mantle minerals and heat flux from Earth’s core

    PubMed Central

    Manthilake, Geeth M.; de Koker, Nico; Frost, Dan J.; McCammon, Catherine A.

    2011-01-01

    The amount of heat flowing from Earth’s core critically determines the thermo-chemical evolution of both the core and the lower mantle. Consisting primarily of a polycrystalline aggregate of silicate perovskite and ferropericlase, the thermal boundary layer at the very base of Earth’s lower mantle regulates the heat flow from the core, so that the thermal conductivity (k) of these mineral phases controls the amount of heat entering the lowermost mantle. Here we report measurements of the lattice thermal conductivity of pure, Al-, and Fe-bearing MgSiO3 perovskite at 26 GPa up to 1,073 K, and of ferropericlase containing 0, 5, and 20% Fe, at 8 and 14 GPa up to 1,273 K. We find the incorporation of these elements in silicate perovskite and ferropericlase to result in a ∼50% decrease of lattice thermal conductivity relative to the end member compositions. A model of thermal conductivity constrained from our results indicates that a peridotitic mantle would have k = 9.1 ± 1.2 W/m K at the top of the thermal boundary layer and k = 8.4 ± 1.2 W/m K at its base. These values translate into a heat flux of 11.0 ± 1.4 terawatts (TW) from Earth’s core, a range of values consistent with a variety of geophysical estimates. PMID:22021444

  20. Microwave-based laboratory experiments for internally-heated mantle convection

    NASA Astrophysics Data System (ADS)

    Limare, A.; Surducan, E.; Surducan, V.; Neamtu, C.; di Giuseppe, E.; Vilella, K.; Farnetani, C. G.; Kaminski, E.; Jaupart, C.

    2013-11-01

    The thermal evolution of terrestrial planets is mainly controlled by the amount of radioactive heat sources in their mantle, and by the geometry and efficiency of solid state thermo-chemical convection within. So far, these systems have been studied using numerical methods only and cross validation by laboratory analogous experiments has not been conducted yet. To fill this gap we perform the first laboratory experiments of mantle convection driven by microwave-generated internal heating. We use a 30×30×5 cm3 experimental tank filled with 0.5 % Natrosol in water mixture (viscosity 0.6 Pa.s at 20°C). The fluid is heated from within by a microwave device that delivers a uniform volumetric heating from 10 to 70 kW/m3; the upper boundary of the fluid is kept at constant temperature, whereas the lower boundary is adiabatic. The velocity field is determined with particle image velocimetry and the temperature field is measured using thermochromic liquid crystals which enable us to charaterize the geometry of the convective regime as well as its bulk thermal evolution. Numerical simulations, conducted using Stag-3D in 3D cartesian geometry, reproduce the experimental setup (i.e., boundary conditions, box aspect ratio, temperature dependence of physical parameters, internal heating rate). The successful comparison between the experimental and numerical results validates our approach of modelling internal heating using microwaves.

  1. Microwave-based laboratory experiments for internally-heated mantle convection

    SciTech Connect

    Limare, A.; Di Giuseppe, E.; Vilella, K.; Farnetani, C. G.; Kaminski, E.; Jaupart, C.; Surducan, E.; Surducan, V.; Neamtu, C.

    2013-11-13

    The thermal evolution of terrestrial planets is mainly controlled by the amount of radioactive heat sources in their mantle, and by the geometry and efficiency of solid state thermo-chemical convection within. So far, these systems have been studied using numerical methods only and cross validation by laboratory analogous experiments has not been conducted yet. To fill this gap we perform the first laboratory experiments of mantle convection driven by microwave-generated internal heating. We use a 30×30×5 cm{sup 3} experimental tank filled with 0.5 % Natrosol in water mixture (viscosity 0.6 Pa.s at 20°C). The fluid is heated from within by a microwave device that delivers a uniform volumetric heating from 10 to 70 kW/m{sup 3}; the upper boundary of the fluid is kept at constant temperature, whereas the lower boundary is adiabatic. The velocity field is determined with particle image velocimetry and the temperature field is measured using thermochromic liquid crystals which enable us to charaterize the geometry of the convective regime as well as its bulk thermal evolution. Numerical simulations, conducted using Stag-3D in 3D cartesian geometry, reproduce the experimental setup (i.e., boundary conditions, box aspect ratio, temperature dependence of physical parameters, internal heating rate). The successful comparison between the experimental and numerical results validates our approach of modelling internal heating using microwaves.

  2. 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

  3. Seismic-geodynamic constraints on three-dimensional structure, vertical flow, and heat transfer in the mantle

    USGS Publications Warehouse

    Forte, A.M.; Woodward, R.L.

    1997-01-01

    Joint inversions of seismic and geodynamic data are carried out in which we simultaneously constrain global-scale seismic heterogeneity in the mantle as well as the amplitude of vertical mantle flow across the 670 km seismic discontinuity. These inversions reveal the existence of a family of three-dimensional (3-D) mantle models that satisfy the data while at the same time yielding predictions of layered mantle flow. The new 3-D mantle models we obtain demonstrate that the buoyancy forces due to the undulations of the 670 km phase-change boundary strongly inhibit the vertical flow between the upper and lower mantle. The strong stabilizing effect of the 670 km topography also has an important impact on the predicted dynamic topography of the Earth's solid surface and on the surface gravity anomalies. The new 3-D models that predict strongly or partially layered mantle flow provide essentially identical fits to the global seismic data as previous models that have, until now, predicted only whole-mantle flow. The convective vertical transport of heat across the mantle predicted on the basis of the new 3-D models shows that the heat flow is a minimum at 1000 km depth. This suggests the presence at this depth of a globally defined horizon across which the pattern of lateral heterogeneity changes rapidly. Copyright 1997 by the American Geophysical Union.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Heat transport in the high-pressure ice mantle of large icy moons

    NASA Astrophysics Data System (ADS)

    Choblet, G.; Tobie, G.; Sotin, C.; Kalousová, K.; Grasset, O.

    2017-03-01

    While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (∼ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to

  9. 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.

  10. 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.

  11. Factors affecting ground-water exchange and catchment size for Florida lakes in mantled karst terrain

    USGS Publications Warehouse

    Lee, Terrie Mackin

    2002-01-01

    In the mantled karst terrain of Florida, the size of the catchment delivering ground-water inflow to lakes is often considerably smaller than the topographically defined drainage basin. The size is determined by a balance of factors that act individually to enhance or diminish the hydraulic connection between the lake and the adjacent surficial aquifer, as well as the hydraulic connection between the surficial aquifer and the deeper limestone aquifer. Factors affecting ground-water exchange and the size of the ground-water catchment for lakes in mantled karst terrain were examined by: (1) reviewing the physical and hydrogeological characteristics of 14 Florida lake basins with available ground-water inflow estimates, and (2) simulating ground-water flow in hypothetical lake basins. Variably-saturated flow modeling was used to simulate a range of physical and hydrogeologic factors observed at the 14 lake basins. These factors included: recharge rate to the surficial aquifer, thickness of the unsaturated zone, size of the topographically defined basin, depth of the lake, thickness of the surficial aquifer, hydraulic conductivity of the geologic units, the location and size of karst subsidence features beneath and onshore of the lake, and the head in the Upper Floridan aquifer. Catchment size and the magnitude of ground-water inflow increased with increases in recharge rate to the surficial aquifer, the size of the topographically defined basin, hydraulic conductivity in the surficial aquifer, the degree of confinement of the deeper Upper Floridan aquifer, and the head in the Upper Floridan aquifer. The catchment size and magnitude of ground-water inflow increased with decreases in the number and size of karst subsidence features in the basin, and the thickness of the unsaturated zone near the lake. Model results, although qualitative, provided insights into: (1) the types of lake basins in mantled karst terrain that have the potential to generate small and large

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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…

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Giant impacts, heterogeneous mantle heating and a past hemispheric dynamo on Mars

    NASA Astrophysics Data System (ADS)

    Monteux, J.; Amit, H.; Choblet, G.; Langlais, B.; Tobie, G.

    2015-10-01

    The martian surface exhibits a strong dichotomy in elevation, crustal thickness and magnetization between the southern and northern hemispheres. A giant impact has been proposed as an explanation for the for-mation of the Northern Lowlands on Mars. Such an impact probably led to strong and deep mantle heat-ing which may have had implications on the magnetic evolution of the planet. We model the effects of such an impact on the martian magnetic field by imposing an impact induced thermal heterogeneity, and the sub-sequent heat flux heterogeneity, on the martian core- mantle boundary(CMB). The CMB heat flux lateral variations as well as the reduction in the mean CMB heat flux are determined by the size and geographic location of the impactor. A polar impactor leads to a north-south hemispheric magnetic dichotomy that is stronger than an east-west dichotomy created by an equatorial impactor. The amplitude of the hemispheric magnetic dichotomy is mostly controlled by the horizontal Rayleigh number Rah which represents the vigor of the convection driven by the lateral variations of the CMB heat flux. We show that, for a given Rah, an impact induced CMB heat flux heterogeneity is more efficient than a synthetic degree-1 CMB heat flux heterogeneity in generating strong hemispheric magnetic dichotomies. Large Rah values are needed to get a dichotomy as strong as the observed one, favoring a reversing paleo-dynamo for Mars. Our results imply that an impactor radius of˜1000 km could have recorded the magnetic dichotomy observed in the mar- tian crustal field only if very rapid post-impact magma cooling took place.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Giant impacts, heterogeneous mantle heating and a past hemispheric dynamo on Mars

    NASA Astrophysics Data System (ADS)

    Monteux, Julien; Amit, Hagay; Choblet, Gael; Langlais, Benoît; Tobie, Gabriel

    2015-04-01

    The martian surface exhibits a strong dichotomy in elevation, crustal thickness and magnetization between the southern and northern hemispheres. A giant impact has been proposed as an explanation for the formation of the Northern Lowlands on Mars. Such an impact probably led to strong and deep mantle heating which may have had implications on the magnetic evolution of the planet. We model the effects of such an impact on the martian magnetic field by imposing an impact induced thermal heterogeneity, and the subsequent heat flux heterogeneity, on the martian core-mantle boundary (CMB). The CMB heat flux lateral variations as well as the reduction in the mean CMB heat flux are determined by the size and geographic location of the impactor. A polar impactor leads to a north-south hemispheric magnetic dichotomy that is stronger than an east-west dichotomy created by an equatorial impactor. The amplitude of the hemispheric magnetic dichotomy is mostly controlled by the horizontal Rayleigh number Rah which represents the vigor of the convection driven by the lateral variations of the CMB heat flux. We show that, for a given Rah, an impact induced CMB heat flux heterogeneity is more efficient than a synthetic degree-1 CMB heat flux heterogeneity in generating strong hemispheric magnetic dichotomies. Large Rah values are needed to get a dichotomy as strong as the observed one, favoring a reversing paleo-dynamo for Mars. Our results imply that an impactor radius of ~ 1000 km could have recorded the magnetic dichotomy observed in the martian crustal field only if very rapid post-impact magma cooling took place.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 40 CFR 63.1328 - Heat exchange systems provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1328 Heat exchange... part, the owner or operator is only required to consider organic HAP listed on Table 6 of this...

  5. 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)

  6. 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...

  7. 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...

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Surface heat flow and the mantle contribution on the margins of Australia

    NASA Astrophysics Data System (ADS)

    Goutorbe, Bruno; Lucazeau, Francis; Bonneville, Alain

    2008-05-01

    We present thermal data from 473 oil exploration wells in Australia and New Zealand. Approximately 2300 bottom-hole temperatures are corrected to form a homogeneous set along with 86 temperatures from reservoir tests. Thermal conductivity profiles are estimated from a set of geophysical well logs using a recently developed neural network approach. Retaining wells in which temperature and thermal conductivity data overlap over an interval greater than 1000 m, we estimate 10 heat flow values in the Taranaki basin of New Zealand and 270 values in the northwestern, western, and southern margins and in the intracontinental Canning basin of Australia. The values are in the range 30-80 mW m-2. As a result of several differences in the data and methods, our heat flow values are 10-20 mW m-2 lower compared to previously published estimates for the same wells in New Zealand. For Australia, our values are consistent with previously measured values and trends in the continental and marine regions. On the northwestern and southeastern margins, we interpret the variations as reflecting changes in the nature of the underlying basement. Consistent with onshore data, it is inferred that the Archean crust is depleted in radiogenic elements compared to Proterozoic regions and that recent volcanism affects the eastern Paleozoic area. After removing from surface heat flow the sediment contributions, including a permanent radiogenic heat component and a transient sedimentation effect, a simple crustal model suggests that mantle heat flow on the continental margin bordering the Pilbara craton is higher than below the craton itself. Moreover, heat flow corrected for the sediment contributions is markedly lower in the Petrel intracontinental basin than in the adjacent margin, although the crust is thinner below this latter region. As both are underlaid by the same basement, this observation may indicate that the mantle contribution is also higher below that margin. Such a higher mantle

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

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

    DOEpatents

    Drake, R.L.

    1993-12-28

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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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 §...

  14. 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 §...

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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%.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Non-equilibrium effects of core-cooling and time-dependent internal heating on mantle flush events

    NASA Astrophysics Data System (ADS)

    Yuen, D. A.; Balachandar, S.; Steinbach, V. C.; Honda, S.; Reuteler, D. M.; Smedsmo, J. J.; Lauer, G. S.

    We have examined the non-equilibrium effects of core-cooling and time-dependent internal-heating on the thermal evolution of the Earth's mantle and on mantle flush events caused by the two major phase transitions. Both two- and three-dimensional models have been employed. The mantle viscosity responds to the secular cooling through changes in the averaged temperature field. A viscosity which decreases algebraically with the average temperature has been considered. The time-dependent internal-heating is prescribed to decrease exponentially with a single decay time. We have studied the thermal histories with initial Rayleigh numbers between 2 x 107 and 108 . Flush events, driven by the non-equilibrium forcings, are much more dramatic than those produced by the equilibrium boundary conditions and constant internal heating. Multiple flush events are found under non-equilibrium conditions in which there is very little internal heating or very fast decay rates of internal-heating. Otherwise, the flush events take place in a relatively continuous fashion. Prior to massive flush events small-scale percolative structures appear in the 3D temperature fields. Time-dependent signatures, such as the surface heat flux, also exhibits high frequency oscillatory patterns prior to massive flush events. These two observations suggest that the flush event may be a self-organized critical phenomenon. The Nusselt number as a function of the time-varying Ra does not follow the Nusselt vs. Rayleigh number power-law relationship based on equilibrium (constant temperature) boundary conditions. Instead Nu(t) may vary non-monotonically with time because of the mantle flush events. Convective processes in the mantle operate quite differently under non-equilibrium conditions from its behaviour under the usual equilibrium situations.

  2. 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

  3. 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

  4. 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.

  5. Time variability in Cenozoic reconstructions of mantle heat flow: plate tectonic cycles and implications for Earth's thermal evolution.

    PubMed

    Loyd, S J; Becker, T W; Conrad, C P; Lithgow-Bertelloni, C; Corsetti, F A

    2007-09-04

    The thermal evolution of Earth is governed by the rate of secular cooling and the amount of radiogenic heating. If mantle heat sources are known, surface heat flow at different times may be used to deduce the efficiency of convective cooling and ultimately the temporal character of plate tectonics. We estimate global heat flow from 65 Ma to the present using seafloor age reconstructions and a modified half-space cooling model, and we find that heat flow has decreased by approximately 0.15% every million years during the Cenozoic. By examining geometric trends in plate reconstructions since 120 Ma, we show that the reduction in heat flow is due to a decrease in the area of ridge-proximal oceanic crust. Even accounting for uncertainties in plate reconstructions, the rate of heat flow decrease is an order of magnitude faster than estimates based on smooth, parameterized cooling models. This implies that heat flow experiences short-term fluctuations associated with plate tectonic cyclicity. Continental separation does not appear to directly control convective wavelengths, but rather indirectly affects how oceanic plate systems adjust to accommodate global heat transport. Given that today's heat flow may be unusually low, secular cooling rates estimated from present-day values will tend to underestimate the average cooling rate. Thus, a mechanism that causes less efficient tectonic heat transport at higher temperatures may be required to prevent an unreasonably hot mantle in the recent past.

  6. Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

    PubMed Central

    Loyd, S. J.; Becker, T. W.; Conrad, C. P.; Lithgow-Bertelloni, C.; Corsetti, F. A.

    2007-01-01

    The thermal evolution of Earth is governed by the rate of secular cooling and the amount of radiogenic heating. If mantle heat sources are known, surface heat flow at different times may be used to deduce the efficiency of convective cooling and ultimately the temporal character of plate tectonics. We estimate global heat flow from 65 Ma to the present using seafloor age reconstructions and a modified half-space cooling model, and we find that heat flow has decreased by ∼0.15% every million years during the Cenozoic. By examining geometric trends in plate reconstructions since 120 Ma, we show that the reduction in heat flow is due to a decrease in the area of ridge-proximal oceanic crust. Even accounting for uncertainties in plate reconstructions, the rate of heat flow decrease is an order of magnitude faster than estimates based on smooth, parameterized cooling models. This implies that heat flow experiences short-term fluctuations associated with plate tectonic cyclicity. Continental separation does not appear to directly control convective wavelengths, but rather indirectly affects how oceanic plate systems adjust to accommodate global heat transport. Given that today's heat flow may be unusually low, secular cooling rates estimated from present-day values will tend to underestimate the average cooling rate. Thus, a mechanism that causes less efficient tectonic heat transport at higher temperatures may be required to prevent an unreasonably hot mantle in the recent past. PMID:17720806

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. How Irreversible Heat Transport Processes Drive Earth's Interdependent Thermal, Structural, and Chemical Evolution Providing a Strongly Heterogeneous, Layered Mantle

    NASA Astrophysics Data System (ADS)

    Hofmeister, A.; Criss, R. E.

    2013-12-01

    Because magmatism conveys radioactive isotopes plus latent heat rapidly upwards while advecting heat, this process links and controls the thermal and chemical evolution of Earth. We present evidence that the lower mantle-upper mantle boundary is a profound chemical discontinuity, leading to observed heterogeneities in the outermost layers that can be directly sampled, and construct an alternative view of Earth's internal workings. Earth's beginning involved cooling via explosive outgassing of substantial ice (mainly CO) buried with dust during accretion. High carbon content is expected from Solar abundances and ice in comets. Reaction of CO with metal provided a carbide-rich core while converting MgSiO3 to olivine via oxidizing reactions. Because thermodynamic law (and buoyancy of hot particles) indicates that primordial heat from gravitational segregation is neither large nor carried downwards, whereas differentiation forced radioactive elements upwards, formation of the core and lower mantle greatly cooled the Earth. Reference conductive geotherms, calculated using accurate and new thermal diffusivity data, require that heat-producing elements are sequestered above 670 km which limits convection to the upper mantle. These irreversible beginnings limit secular cooling to radioactive wind-down, permiting deduction of Earth's inventory of heat-producing elements from today's heat flux. Coupling our estimate for heat producing elements with meteoritic data indicates that Earth's oxide content has been underestimated. Density sorting segregated a Si-rich, peridotitic upper mantle from a refractory, oxide lower mantle with high Ca, Al and Ti contents, consistent with diamond inclusion mineralogy. Early and rapid differentiation means that internal temperatures have long been buffered by freezing of the inner core, allowing survival of crust as old as ca.4 Ga. Magmatism remains important. Melt escaping though stress-induced fractures in the rigid lithosphere imparts a

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

    DTIC Science & Technology

    1983-08-01

    poisoning and in chronic disorders such as peptic ulcer or Parkinsonism (9). The competition by atropine for similar receptor sites on the eccrine sweat ...block number) C. antimuscarinic drugs; exercise; heat acclimatization; mean body temperature; rational effective temperature; sweating rate L&J -J 20...20.5*C). Partitional calorimetric analysis was done for the periods in which maximum sweat inhibition occurred (30 min). Mean skin temperature (Tsk

  14. 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.

  15. 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.

  16. 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.

  17. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a... suitable for continued operation at high temperatures and resistant to corrosion from exhaust gases;...

  18. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a... suitable for continued operation at high temperatures and resistant to corrosion from exhaust gases;...

  19. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a... suitable for continued operation at high temperatures and resistant to corrosion from exhaust gases;...

  20. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a... suitable for continued operation at high temperatures and resistant to corrosion from exhaust gases;...

  1. 14 CFR 23.1125 - Exhaust heat exchangers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a... suitable for continued operation at high temperatures and resistant to corrosion from exhaust gases;...

  2. 40 CFR 63.1409 - Heat exchange system provisions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) of this section by monitoring using a surrogate indicator of heat exchange system leaks shall comply with the requirements specified in paragraphs (c)(1) through (3) of this section. Surrogate indicators... fluids into cooling water. The plan shall require monitoring of one or more surrogate indicators...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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).

  18. 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

  19. 2-D numerical simulations of groundwater flow, heat transfer and 4He transport — implications for the He terrestrial budget and the mantle helium heat imbalance

    NASA Astrophysics Data System (ADS)

    Castro, Maria Clara; Patriarche, Delphine; Goblet, Patrick

    2005-09-01

    Because helium and heat production results from a common source, a continental 4He crustal flux of 4.65 * 10 - 14 mol m - 2 s - 1 has been estimated based on heat flow considerations. In addition, because the observed mantle He / heat flux ratio at the proximity of mid-ocean ridges (6.6 * 10 - 14 mol J - 1 ) is significantly lower than the radiogenic production ratio (1.5 * 10 - 12 mol J - 1 ), the presence of a terrestrial helium-heat imbalance was suggested. The latter could be explained by the presence of a layered mantle in which removal of He is impeded from the lower mantle [R.K. O'Nions, E.R. Oxburgh, Heat and helium in the Earth, Nature 306 (1983) 429-431; E.R. Oxburgh, R.K. O'Nions, Helium loss, tectonics, and the terrestrial heat budget, Science 237 (1987) 1583-1588]. van Keken et al. [P.E. van Keken, C.J. Ballentine, D. Porcelli, A dynamical investigation of the heat and helium imbalance, Earth Planet, Sci. Lett. 188 (2001) 421-434] have recently claimed that the helium-heat imbalance remains a robust observation. Such conclusions, however, were reached under the assumption that a steady-state regime was in place for both tracers and that their transport properties are similar at least in the upper portion of the crust. Here, through 2-D simulations of groundwater flow, heat transfer and 4He transport carried out simultaneously in the Carrizo aquifer and surrounding formations in southwest Texas, we assess the legitimacy of earlier assumptions. Specifically, we show that the driving transport mechanisms for He and heat are of a fundamentally different nature for a high range of permeabilities ( k ≤ 10 - 16 m 2) found in metamorphic and volcanic rocks at all depths in the crust. The assumption that transport properties for these two tracers are similar in the crust is thus unsound. We also show that total 4He / heat flux ratios lower than radiogenic production ratios do not reflect a He deficit in the crust or mantle original reservoir. Instead, they

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. (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.

  16. 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

  17. 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.

  18. 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.

  19. Chemical Exchange Between the Core and the Convecting Mantle of the Earth: Evidence from Highly Siderophile Elements (HSE)

    NASA Astrophysics Data System (ADS)

    Schmidt, G.; Palme, H.; Kratz, K. L.

    1995-09-01

    , and Au with a slightly modified neutron activation analysis in combination with a NiS extraction method [16]. All samples (except peridotitic xenoliths) have essentially unfractionated patterns (except Pd/Ir) despite significant variations in absolute abundances [17]. Os/Re ratios from massive peridotitic rocks from Zabargad are chondritic. Peridotitic xenoliths generally have Os/Re-ratios much higher than the chondritic ratio [2]. The Pd/Ir ratios from all studied peridotites are approximately two times and the Rh/Ir ratios are approximately 1.5 times higher than the chondritic ratio of 1.21 and 0.29, respectively. This is in qualitative agreement with estimates of Pd and Ir in primitive undepleted mantle [1]. The non-chondritic Pd/Ir and Rh/Ir ratios is either the result of Pd and Rh addition or these elements are not quantitatively removed from the mantle in the process of core formation [10]. Extrapolation of experimentally determined palladium and iridium metal/silicate partition coefficients to 3500 K are 3.8x10^3 and 2x10^8, respectively [18,19]. The observed non-chondritic ratio of Ir to Pd in the upper mantle is in qualitative agreement with experimentally determined metal/silicate partition coefficients for Ir and Pd. This could support recent speculation on the possibility of chemical exchange between the outer liquid shell of the core and the convecting mantle of the Earth. Acknowledgements. This work was supported by DFG. References: [1] Morgan J. W. (1986) JGR, 91, 12375-12387. [2] Morgan J. W. et al. (1981) Tectonophys., 75, 47-67. [3] Anders E. (1968) Acc. Chem. Res., 1, 289-298. [4] Turekian K. K. and Clark S. P. (1969) EPSL, 6, 346-348. [5] Kimura K. et al. (1974) GCA, 38, 683-701. [6] Ganapathy R. and Anders E. (1974) Proc. LPSC. [7] Chou C.-L. (1978) Proc. LPSC 9th, 219-230. [8] Jagoutz E. et al. (1979) Proc. LPSC 10th, 2031-2050. [9] Wanke H. (1981) Philos. Trans. R. Soc. London, A303, 287-302. [10] Jones J. H. and Drake M. J. (1986) Nature, 322

  20. 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.

  1. Four K refrigerators with a new compact heat exchanger

    NASA Technical Reports Server (NTRS)

    Longsworth, R. C.; Steyert, W. A.

    1985-01-01

    Two refrigerators have been developed which have nominal cpacities of 0.25M and 0.5W at 4.2K. These use standard two stage Displex sup R expanders and compressors combined with a new compact heat exchanger which is concentric with the expander cylinder. These refrigerators can be used to cool superconducting electronic devices by direct attachment to the 4K heat station, or they can be plugged into the neck of a liquid helium superconducting magnet cryostat where they can cool the radiation shields and reliquefy helium.

  2. Thermal energy storage systems using fluidized bed heat exchangers

    NASA Technical Reports Server (NTRS)

    Ramanathan, V.; Weast, T. E.; Ananth, K. P.

    1980-01-01

    The viability of using fluidized bed heat exchangers (FBHX) for thermal energy storage (TES) in applications with potential for waste heat recovery was investigated. Of the candidate applications screened, cement plant rotary kilns and steel plant electric arc furnaces were identified, via the chosen selection criteria, as having the best potential for successful use of FBHX/TES system. A computer model of the FBHX/TES systems was developed and the technical feasibility of the two selected applications was verified. Economic and tradeoff evaluations in progress for final optimization of the systems and selection of the most promising system for further concept validation are described.

  3. Fluctuations of the heat exchanged between two quantum spin chains.

    PubMed

    Landi, Gabriel T; Karevski, Dragi

    2016-03-01

    The statistics of the heat exchanged between two quantum XX spin chains prepared at different temperatures is studied within the assumption of weak coupling. This provides simple formulas for the average heat and its corresponding characteristic function, from which the probability distribution may be computed numerically. These formulas are valid for arbitrary sizes and therefore allow us to analyze the role of the thermodynamic limit in this nonequilibrium setting. It is found that all thermodynamic quantities are extremely sensitive to the quantum phase transition of the XX chain.

  4. 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.

  5. 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.

  6. Horizontal Heat Exchanger Design and Analysis for Passive Heat Removal Systems

    SciTech Connect

    Vierow, Karen

    2005-08-29

    This report describes a three-year project to investigate the major factors of horizontal heat exchanger performance in passive containment heat removal from a light water reactor following a design basis accident LOCA (Loss of Coolant Accident). The heat exchanger studied in this work may be used in advanced and innovative reactors, in which passive heat removal systems are adopted to improve safety and reliability The application of horizontal tube-bundle condensers to passive containment heat removal is new. In order to show the feasibility of horizontal heat exchangers for passive containment cooling, the following aspects were investigated: 1. the condensation heat transfer characteristics when the incoming fluid contains noncondensable gases 2. the effectiveness of condensate draining in the horizontal orientation 3. the conditions that may lead to unstable condenser operation or highly degraded performance 4. multi-tube behavior with the associated secondary-side effects This project consisted of two experimental investigations and analytical model development for incorporation into industry safety codes such as TRAC and RELAP. A physical understanding of the flow and heat transfer phenomena was obtained and reflected in the analysis models. Two gradute students (one funded by the program) and seven undergraduate students obtained research experience as a part of this program.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    SciTech Connect

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

    1990-01-01

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

  9. The Design, Fabrication, and Testing of Composite Heat Exchange Coupons

    NASA Technical Reports Server (NTRS)

    Quade, Derek J.; Meador, Michael A.; Shin, Euy-Sik; Johnston, James C.; Kuczmarski, Maria A.

    2011-01-01

    Several heat exchanger (HX) test panels were designed, fabricated and tested at the NASA Glenn Research Center to explore the fabrication and performance of several designs for composite heat exchangers. The development of these light weight, high efficiency air-liquid test panels was attempted using polymer composites and carbon foam materials. The fundamental goal of this effort was to demonstrate the feasibility of the composite HX for various space exploration and thermal management applications including Orion CEV and Altair. The specific objectives of this work were to select optimum materials, designs, and to optimize fabrication procedures. After fabrication, the individual design concept prototypes were tested to determine their thermal performance and to guide the future development of full-size engineering development units (EDU). The overall test results suggested that the panel bonded with pre-cured composite laminates to KFOAM Grade L1 scored above the other designs in terms of ease of manufacture and performance.

  10. Condensing Heat Exchanger Concept Developed for Space Systems

    NASA Technical Reports Server (NTRS)

    Hasan, Mohammad M.; Nayagam, Vedha

    2005-01-01

    The current system for moisture removal and humidity control for the space shuttles and the International Space Station uses a two-stage process. Water first condenses onto fins and is pulled through "slurper bars." These bars take in a two-phase mixture of air and water that is then separated by the rotary separator. A more efficient design would remove the water directly from the air without the need of an additional water separator downstream. For the Condensing Heat Exchanger for Space Systems (CHESS) project, researchers at the NASA Glenn Research Center in collaboration with NASA Johnson Space Center are designing a condensing heat exchanger that utilizes capillary forces to collect and remove water and that can operate in varying gravitational conditions including microgravity, lunar gravity, and Martian gravity.

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

    NASA Astrophysics Data System (ADS)

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

    A new 1 W, 4.2 K cryocooler is under development that is intended to miniaturize helium temperature refrigeration systems using a high-pressure-ratio Collins-type cycle. The configuration resulted from optimization studies of a saturated vapor compression (SCV) cycle that employs miniature parallel-plate heat exchangers. The basic configuration is a long displacer in a close-fitting, thin-walled cylinder. The displacer-to-cylinder gap is the high-pressure passage of the heat exchanger, and the low-pressure passage is formed by a thin tube over the OD of the cylinder. A solenoid-operated inlet valve admits 40 atm helium to the displacer-to-cylinder gap at room temperature, while the solenoid-operated exhaust valve operates at 4 atm. The single-stage cryocooler produces 1 W of refrigeration at 40 K without precooling and at 20 K with liquid nitrogen precooling.

  12. Optimisation of Double Pipe Helical Tube Heat Exchanger and its Comparison with Straight Double Tube Heat Exchanger

    NASA Astrophysics Data System (ADS)

    Kareem, Rashid

    2016-06-01

    Optimization of double pipe helical coil heat exchanger with various optimizing parameters and its comparison with double pipe straight tube are the prime objectives of this paper. Numerical studies were performed with the aid of a commercial computational fluid dynamics package ANSYS FLUENT 14. In this paper the double pipe helical coil is analysed under turbulent flow conditions for optimum heat exchanger properties. The parameters used for optimization are cross-sectional shape and taper angles. Optimization analysis is being carried out for finding best cross sectional shape of heat exchanger coils by using rectangular, square, triangular and circular cross-sections. The tapered double pipe helical coil is then analysed for best heat transfer and pressure drop characteristics by varying the angle of taper. Finally, an optimum coil on the basis of all the analysis is selected. This optimized double pipe helical coil is compared with double pipe straight tube of equivalent cross-sectional area and length as that of unwounded length of double pipe helical coil.

  13. The Effects of the Heat and Moisture Exchanger on Humidity, Airway Temperature, and Core Body Temperature

    DTIC Science & Technology

    1999-10-01

    measurement was made a heat and moisture exchanger was added to the experimental group. Three more measurements were recorded at 10, 30 and 60 minutes after...system was insufficient, but the addition of a heat and moisture exchanger provided adequate humidification of the inspired gases. In the experimental ...of these patients had a heat and moisture exchanger incorporated in the ventilator Heat and Moisture Exchangers 16 circuit (the experimental group

  14. Experimental investigation of shell-and-tube heat exchanger with a new type of baffles

    NASA Astrophysics Data System (ADS)

    Wang, Yingshuang; Liu, Zhichun; Huang, Suyi; Liu, Wei; Li, Weiwei

    2011-07-01

    A shell-and-tube heat exchanger with new type of baffles, is designed, fabricated and tested. The experimental investigation for the proposed model and the original segmental baffle heat exchanger are conducted. The operation performances of the two heat exchangers are also compared. The results suggest that, under the same conditions, the overall performance of the new model is 20-30% more efficient than that of the segmental baffle heat exchanger.

  15. A cryogenic heat exchanger with bypass and throttling and its thermodynamic analysis

    NASA Astrophysics Data System (ADS)

    Tao, X.; Liu, D. L.; Wang, L. Y.; Shen, J.; Gan, Z. H.

    2015-12-01

    A precooled Joule-Thomson (J-T) cooler refrigerates at liquid helium temperature. Its third stage heat exchanger works below 20 K. Hot fluid cannot be sufficiently cooled due to nonidealism of the heat exchanger and helium-4 properties. In a J-T cycle of low pressure ratio, the heat exchanger with bypass and throttling improves the refrigeration capacity. Bypass and throttling reduces the temperature difference and entropy generation within the heat exchanger.

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

    DOEpatents

    Jukkola, Walfred W.; Leon, Albert M.; Van Dyk, Jr., Garritt C.; McCoy, Daniel E.; Fisher, Barry L.; Saiers, Timothy L.; Karstetter, Marlin E.

    1981-11-24

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

  17. An Investigation of Turbulent Heat Exchange in the Subtropics

    DTIC Science & Technology

    2014-09-30

    subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE ...30 SEP 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE An Investigation of Turbulent Heat Exchange in the...7200 IRGA to the flux systems. Sea surface temperatures were measured by the group using the sea-snake floating thermistor and radiometric

  18. Secondary Heat Exchanger Design and Comparison for Advanced High Temperature Reactor

    SciTech Connect

    Piyush Sabharwall; Ali Siahpush; Michael McKellar; Michael Patterson; Eung Soo Kim

    2012-06-01

    The goals of next generation nuclear reactors, such as the high temperature gas-cooled reactor and advance high temperature reactor (AHTR), are to increase energy efficiency in the production of electricity and provide high temperature heat for industrial processes. The efficient 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 heat transport system. The need for efficiency, compactness, and safety challenge the boundaries of existing heat exchanger technology, giving rise to the following study. 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 efficient conversion cycles, such as the Rankine super critical and subcritical cycles. This study considers two different types of heat exchangers—helical coiled heat exchanger and printed circuit heat exchanger—as possible options for the AHTR secondary heat exchangers with the following three different options: (1) A single heat exchanger transfers all the heat (3,400 MW(t)) from the intermediate heat transfer loop to the power conversion system or process plants; (2) Two heat exchangers share heat to transfer total heat of 3,400 MW(t) from the intermediate heat transfer loop to the power conversion system or process plants, each exchanger transfers 1,700 MW(t) with a parallel configuration; and (3) Three heat exchangers share heat to transfer total heat of 3,400 MW(t) from the intermediate heat transfer loop to the power conversion system or process plants. Each heat exchanger transfers 1,130 MW(t) with a parallel configuration. A preliminary cost comparison will be provided for all different cases along with challenges and recommendations.

  19. Evaluation of alloys for fuel cell heat exchanges

    NASA Astrophysics Data System (ADS)

    Perkins, R. A.; Vonk, S. J.

    1981-04-01

    The results are presented of an investigation to evaluate the behavior of commercial stainless steels, superalloys, and aluminide coatings in both clean (sulfur-free) and raw (1% H2S) gas representative of the Texaco slagging gasifier atmosphere are 1400 to 18000 F (1033 to 12550 K). The goal was to determine which, if any, of these materials is suitable for use in a high temperature heat exchanger operating on intermediate Btu coal gasification atmospheres. It has been found that none of the commercially available alloys or coatings are suitable for use in the raw (1% H2S) gas, even at temperatures as low as 14000 F (10330 K). Materials that are resistant to attack either have a limited life ( 5000 h) or cannot be fabricated as large size heat exchanger components. It is concluded that structural high temperature alloys must be coated for use in the raw gas and that the best coating or cladding materials are Ni-46Cr (IN671 type alloy) and MCrAl with 25 to 40% Cr and 30 to 40% Al (where M is Ni, Co, or Fe or some combination thereof). Heat exchanger components can be clad with Ni-46Cr but the alloy must be modified to improve its reliability and performance in coal conversion atmospheres.

  20. Update on Modular Laser Launch System and Heat Exchanger Thruster

    NASA Astrophysics Data System (ADS)

    Kare, Jordin T.

    2011-11-01

    The heat-exchanger (HX) thruster and modular laser array provide a comparatively low-risk route to a ground-to-orbit laser launch system. Recently, the reference designs for the propulsion system, laser array, and overall launch system have evolved significantly. By combining a variable flow of dense propellant with the primary hydrogen propellant, the heat exchanger thruster can trade reduced Isp for increased thrust at liftoff, with minimal increase in tank mass. Single-mode CW fiber lasers up to 10 kW power allow a beam module to be built with off-the-shelf commercial lasers. Low-cost high-radiance laser diode arrays can deliver launch-level fluxes of 5-10 MW/m2 over tens of kilometers, sufficient to power a vehicle through the atmosphere, and high enough to hand off propulsion to a main laser array several hundred kilometers downrange. These and other enhancements enable a system design with a true single-stage vehicle in which the only component not yet demonstrated is the silicon-carbide heat exchanger itself.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  2. Utilization of Porous Media for Condensing Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Tuan, George C.

    2006-01-01

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

  3. 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.

  4. 40 CFR 63.1085 - What are the general requirements for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SOURCE CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Heat Exchange System Requirements § 63.1085 What are the general... heat exchange systems? 63.1085 Section 63.1085 Protection of Environment ENVIRONMENTAL...

  5. 40 CFR Table 8 to Subpart Vvvvvv... - Emission Limits and Compliance Requirements for Heat Exchange Systems

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Requirements for Heat Exchange Systems 8 Table 8 to Subpart VVVVVV of Part 63 Protection of Environment... of Part 63—Emission Limits and Compliance Requirements for Heat Exchange Systems As required in § 63.11499, you must comply with the requirements for heat exchange systems as shown in the following...

  6. 40 CFR 63.1085 - What are the general requirements for heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... heat exchange systems? 63.1085 Section 63.1085 Protection of Environment ENVIRONMENTAL PROTECTION... SOURCE CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange Systems and Waste Operations Heat Exchange System Requirements § 63.1085 What are the...

  7. Fabrication, assembly and heat transfer testing of low-profile copper-based microchannel heat exchangers

    NASA Astrophysics Data System (ADS)

    Lu, Bin; Chen, Ke; Meng, W. J.; Mei, Fanghua

    2010-11-01

    Low-profile, Cu-based microchannel heat exchangers (MHEs) with different geometric dimensions were fabricated, bonded and assembled. A transient liquid phase (TLP) process was used for bonding of Cu-based MHEs with total thicknesses ranging from 600 µm to 1700 µm. The structural integrity of TLP-bonded Cu MHEs was examined. Device-level heat transfer testing was performed on a series of Cu-based MHEs to study the influence of microchannel dimensions on overall heat transfer performance, corroborated by computational results from a simple 2D finite element analysis. The present results demonstrate the promise of low-profile metallic MHEs for high heat flux cooling applications.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  9. Experimental investigate of heat transfer for graphene/water nanofluid in micro heat exchanger

    NASA Astrophysics Data System (ADS)

    Abd Elhafez, S. E.; Abo-Zahhad, E. M.; El-Shazly, A. H.; El-Kady, M. F.

    2017-02-01

    In this investigation, the heat transfer characteristics of graphene nano platelets (GNPs)/water nanofluid were studied in a micro heat exchanger (MHE). The micro heat exchanger performance was also examined. The test setup was worked out in the laminar regime with Reynold numbers varying between 100 and 400GNPs/water nanofluid was prepared three different concentrations (0.025 wt. %, 0.05 wt. % and 0.1 wt. %) using ultrasonic wave. The influence of mass flow rate, inlet temperatures and weight fraction on the overall heat transfer coefficient (U) and logarithmic mean temperature (LMTD) were examined. The results showed considerable enhancement on the overall heat transfer coefficient of graphene/water nanofluid and the MHE effectiveness. A maximum enhancement on overall heat transfer coefficient was reached to 150% at Re=100 by 0.1wt% nanofluid. The effectiveness of micro heat exchanger was enhanced by increase weight fraction of graphene nanoparticle. Moreover, the experimental results showed that 0.1 wt. % GNPs/water nanofluid, flowing through MHE, has had high pressure drop, and pumping power, when it has been compared with 0.5 wt. % and 0.025 wt.%.

  10. Experimental Investigation of Heat transfer rate of Nano fluids using a Shell and Tube Heat exchanger

    NASA Astrophysics Data System (ADS)

    SIVA ESWARA RAO, M.; SREERAMULU, DOWLURU; ASIRI NAIDU, D.

    2016-09-01

    Nano fluids are used for increasing thermal properties in heat transfer equipment like heat exchangers, radiators etc. This paper investigates the heat transfer rate of Nano fluids using a shell and tube heat exchanger in single and multi tubes under turbulent flow condition by a forced convection mode. Alumina Nanoparticles are prepared by using Sol-Gel method. Heat transfer rate increases with decreasing particle size. In this experiment Alumina Nano particles of about 22 nm diameter used. Alumina Nano fluids are prepared with different concentrations of Alumina particles (0.13%, 0.27%, 0.4%, and 0.53%) with water as a base fluid using ultra-sonicator. Experiment have been conducted on shell and tube heat exchanger for the above concentrations on parallel and counter flow conditions by keeping constant inlet temperatures and mass flow rate. The result shows that the heat transfer rate is good compared to conventional fluids. The properties of Nano fluids and non-dimensional numbers have been calculated.

  11. In-Situ Shipboard Heat Exchanger Cleaning and Maintenance Using Innovative I2 Bubble Infusion Technology

    DTIC Science & Technology

    2014-07-15

    at the Queens Botanical Gardens, Flushing, NY. This facility employed a geothermal system for heating and cooling. Iron reducing bacteria from the...the patented I2 infusion system to reduce the rate of foul within Department of Defense shipboard heat exchangers. Fouling of DoD shipboard heat ...selection of the heat exchangers used in the demonstration and provided invaluable information regarding Navy heat exchanger system construction

  12. An overview of heat exchanger enhancement techniques for industrial applications

    SciTech Connect

    Somasundaram, S.; Ohadi, M.M.; Richlen, S.

    1992-06-01

    An assessment is make of selected currently available heat exchanger enhancement techniques for single- and two-phase heat transfer mechanisms to determine their practicality and commercialization potential for different industrial applications. The assessment includes a screening review of the major techniques being investigated in the research community, and identification of selected passive techniques and determine their potential limitations with respect to industrial applications. A more detailed study of the research needs and the technology gaps is being conducted to address the issues of concern for each practical application of the chosen techniques. The technical and economic feasibility and the performance benefits of incorporating a particular technique in a heat transfer process is also discussed. The potential design, operational, and manufacturing cost issues that have prevented a technique from being widely commercialized are identified.

  13. Countercurrent direct contact heat exchange process and system

    DOEpatents

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

    1979-01-01

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

  14. A probabilistic model of a porous heat exchanger

    NASA Technical Reports Server (NTRS)

    Agrawal, O. P.; Lin, X. A.

    1995-01-01

    This paper presents a probabilistic one-dimensional finite element model for heat transfer processes in porous heat exchangers. The Galerkin approach is used to develop the finite element matrices. Some of the submatrices are asymmetric due to the presence of the flow term. The Neumann expansion is used to write the temperature distribution as a series of random variables, and the expectation operator is applied to obtain the mean and deviation statistics. To demonstrate the feasibility of the formulation, a one-dimensional model of heat transfer phenomenon in superfluid flow through a porous media is considered. Results of this formulation agree well with the Monte-Carlo simulations and the analytical solutions. Although the numerical experiments are confined to parametric random variables, a formulation is presented to account for the random spatial variations.

  15. Experimental study of mixed convection heat transfer in vertical helically coiled tube heat exchangers

    SciTech Connect

    Ghorbani, N.; Taherian, H.; Gorji, M.; Mirgolbabaei, H.

    2010-10-15

    In this study the mixed convection heat transfer in a coil-in-shell heat exchanger for various Reynolds numbers, various tube-to-coil diameter ratios and different dimensionless coil pitch was experimentally investigated. The experiments were conducted for both laminar and turbulent flow inside coil. Effects of coil pitch and tube diameters on shell-side heat transfer coefficient of the heat exchanger were studied. Different characteristic lengths were used in various Nusselt number calculations to determine which length best fits the data and several equations were proposed. The particular difference in this study in comparison with the other similar studies was the boundary conditions for the helical coils. The results indicate that the equivalent diameter of shell is the best characteristic length. (author)

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

    NASA Astrophysics Data System (ADS)

    Karaki, S.; Brothers, P.

    1980-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Olson, Douglas A.; Glover, Michael P.

    1990-01-01

    A compact heat exchanger was constructed consisting of circular tubes in parallel brazed to a grooved base plate. This tube specimen heat exchanger was tested in an apparatus which radiatively heated the specimen on one side at a heat flux of up to 54 W/sq cm, and cooled the specimen with helium gas at 3.5 MPa and Reynolds numbers of 3000 to 35,000. The measured friction factor of the tube specimen was lower than that of a circular tube with fully developed turbulent flow, although the uncertainty was high due to entrance and exit losses. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in circular tubes.

  18. Heat transfer enhancement by dynamic corrugated heat exchanger wall: Numerical study

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Schmidmayer, K.; Topin, F.; Miscevic, M.

    2016-09-01

    A new concept of heat exchanger at sub-millimeter scale is proposed for applications in cooling on-board electronics devices, in which the quality of the exchanges between fluid and wall is very critical. In the proposed system, the upper wall of the channel is deformed dynamically to obtain a sinusoidal wave on this surface. The lower wall is exposed to constant heat flux simulating the imprint of an electronic component. A systematic 3-D numerical study in transient regime on the different deformation parameters allowed obtaining both the pumping characteristics and the heat transfer characteristics of the system. It was observed that the dynamic deformation of the wall induces a significant pumping effect. The intensification of the heat transfer is very important even for highly degraded waveforms, although the pumping efficiency is reduced in this case.

  19. Effect of flow maldistribution and axial conduction on compact microchannel heat exchanger

    NASA Astrophysics Data System (ADS)

    Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon

    2014-03-01

    When a compact microchannel heat exchanger is operated at cryogenic environments, it has potential problems of axial conduction and flow maldistribution. To analyze these detrimental effects, the heat exchanger model that includes both axial conduction and flow maldistribution effect is developed in consideration of the microchannel heat exchanger geometry. A dimensionless axial conduction parameter (λ) is used to describe the axial conduction effect, and the coefficient of variation (CoV) is introduced to quantify the flow maldistribution condition. The effectiveness of heat exchanger is calculated according to the various values of the axial conduction parameter and the CoV. The analysis results show that the heat exchanger effectiveness is insensitive when λ is less than 0.005, and effectiveness is degraded with the large value of CoV. Three microchannel heat exchangers are fabricated with printed circuit heat exchanger (PCHE) technology for validation purpose of the heat exchanger model. The first heat exchanger is a conventional heat exchanger, the second heat exchanger has the modified cross section to eliminate axial conduction effect, and the third heat exchanger has the modified cross section and the cross link in parallel channel to mitigate flow maldistribution effect. These heat exchangers are tested in cryogenic single-phase, and two-phase environments. The third heat exchanger shows the ideal thermal characteristic, while the other two heat exchangers experience some performance degradation due to axial conduction or flow maldistribution. The impact of axial conduction and flow maldistribution effects are verified by the simulation results and compared with the experimental results.

  20. Water Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  1. Abyssal plains heat exchange could explain global deficit

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-07-01

    When researchers measure the amount of heat flowing conductively from the seafloor to the ocean waters and then compare that value against a theoretical prediction of that heat loss, they observe that the global average measured heat flow is lower than expected. Researchers think that advection, a heat transfer mechanism that is difficult to measure, makes up this difference between predicted and observed heat exchange. They suggest that as seawater circulates through the permeable upper layers of the seafloor crust, driven by a thermal gradient, the water accumulates heat, drawing it into the ocean. Scientists have recently proposed that seafloor sediment plays an important role in controlling the geometry of such intraocean crust circulation. In the abyssal plains, the accumulation of millions of years' worth of low permeability sediment limits direct contact between the ocean and the crust. Where the sediment is thin or absent—for example, at outcrops—water is thought to be able to move between the ocean and the crust. Scientists propose that seawater can travel through the crust for tens of kilometers beneath the sediment, moving laterally from outcrop to outcrop.

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

    SciTech Connect

    Wang, R.Z.; Wu, J.Y.; Xu, Y.X.

    1999-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Karaki, S.; Brothers, P.

    1980-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  5. Effects of a core/mantle chemical boundary layer with variable internal heat production on the thermal evolution of the core

    NASA Astrophysics Data System (ADS)

    Lassiter, J. C.

    2006-12-01

    Estimates of conductive heat flow across the core/mantle boundary suggest high heat flow values of 7-14 TW for a core/mantle temperature drop of 1000-1800 K. This level of heat flow predicts an inner core age of less than 1-2 Ga. However, some models of core/mantle thermal evolution predict late onset of inner core crystallization may require implausibly high core temperatures in the Archaean [1]. Sequestration of heat producing elements at the base of the mantle may reduce core/mantle heat flow and increase the age of the inner core [1]. In addition, Boyet and Carlson [2] reported ^{142}Nd excesses in terrestrial samples relative to chondrites, and proposed that an enriched reservoir produced by early differentiation may be "hidden" at the base of the mantle, and that this reservoir could contain up to 43% of the Earth's heat producing elements. The runaway core thermal evolution predicted by Buffett [1] for models with a relatively young inner core results from two assumptions. First, Buffett assumes that core/mantle heat flow has decreased ~3x since the onset of inner core crystallization, because the power required to drive the geodynamo today is much lower than prior to inner core crystallization. Second, Buffett treats the core/mantle boundary as a thermal boundary with strongly temperature-dependant viscosity, so that relatively small increases in core temperature result in a large decrease in boundary layer thickness and increase in core/mantle heat flow. If the core/mantle boundary is a chemical rather than purely thermal boundary the boundary layer thickness need not be time- or temperature-dependant. As a result, core/mantle heat flow is roughly linearly proportional to core-mantle ΔT, rather than exponential. Provided that modern core/mantle heat flow is greater than the heat flow required to drive the geodynamo in the absence of inner core crystallization, no significant secular evolution in core/mantle heat flow is required. Given these assumptions

  6. Multiple pollutant removal using the condensing heat exchanger

    SciTech Connect

    Jankura, B. J.; Kudlac, G. A.; Bailey, R. T.

    1998-06-01

    The Integrated Flue Gas Treatment (IFGT) system is a new concept whereby a Teflon ® covered condensing heat exchanger is adapted to remove certain flue gas constituents, both particulate and gaseous, while recovering low level heat. The pollutant removal performance and durability of this device is the subject of a USDOE sponsored program to develop this technology. The program was conducted under contract to the United States Department of Energy's Fossil Energy Technology Center (DOE-FETC) and was supported by the Ohio Coal Development Office (OCDO) within the Ohio Department of Development, the Electric Power Research Institute's Environmental Control Technology Center (EPRI-ECTC) and Babcock and Wilcox - a McDermott Company (B&W). This report covers the results of the first phase of this program. This Phase I project has been a two year effort. Phase I includes two experimental tasks. One task dealt principally with the pollutant removal capabilities of the IFGT at a scale of about 1.2MWt. The other task studied the durability of the Teflon ® covering to withstand the rigors of abrasive wear by fly ash emitted as a result of coal combustion. The pollutant removal characteristics of the IFGT system were measured over a wide range of operating conditions. The coals tested included high, medium and low-sulfur coals. The flue gas pollutants studied included ammonia, hydrogen chloride, hydrogen fluoride, particulate, sulfur dioxide, gas phase and particle phase mercury and gas phase and particle phase trace elements. The particulate removal efficiency and size distribution was investigated. These test results demonstrated that the IFGT system is an effective device for both acid gas absorption and fine particulate collection. Although soda ash was shown to be the most effective reagent for acid gas absorption, comparative cost analyses suggested that magnesium enhanced lime was the most promising avenue for future study. The durability of the Teflon

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  8. Simulation model air-to-air plate heat exchanger

    SciTech Connect

    Wetter, Michael

    1999-01-01

    A simple simulation model of an air-to-air plate heat exchanger is presented. The model belongs to a collection of simulation models that allows the eflcient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is to shorten computation time and to use only input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part-load operation mode, which is becoming increasingly important in energy eficient HVAC systems. The models are intended to be used for yearly energy calculations or load calculations with time steps of about 10 minutes or larger. Short- time dynamic effects, which are of interest for different aspects of control theory, are neglected. The part-load behavior is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part-load condition. If the heat transfer coefficients on the two exchanger sides are not equal (i. e. due to partial bypassing of air), their ratio can be easily calculated and set as a parameter. The model is static and uses explicit equations only. The explicit model formulation ensures short computation time and numerical stability, which allows using the model with sophisticated engineering methods like automatic system optimization. This paper fully outlines the algorithm description and its simplifications. It is not tailored for any particular simulation program to ensure easy implementation in any simulation program.

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

    NASA Astrophysics Data System (ADS)

    Kim, Yong Sung

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

  10. Counterflow heat exchanger with core and plenums at both ends

    SciTech Connect

    Bejan, A.; Alalaimi, M.; Lorente, S.; Sabau, A. S.; Klett, J. W.

    2016-04-22

    Here, this paper illustrates the morphing of flow architecture toward greater performance in a counterflow heat exchanger. The architecture consists of two plenums with a core of counterflow channels between them. Each stream enters one plenum and then flows in a channel that travels the core and crosses the second plenum. The volume of the heat exchanger is fixed while the volume fraction occupied by each plenum is variable. Performance is driven by two objectives, simultaneously: low flow resistance and low thermal resistance. The analytical and numerical results show that the overall flow resistance is the lowest when the core is absent, and each plenum occupies half of the available volume and is oriented in counterflow with the other plenum. In this configuration, the thermal resistance also reaches its lowest value. These conclusions hold for fully developed laminar flow and turbulent flow through the core. The curve for effectiveness vs number of heat transfer units (Ntu) is steeper (when Ntu < 1) than the classical curves for counterflow and crossflow.

  11. Counterflow heat exchanger with core and plenums at both ends

    DOE PAGES

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

    2016-04-22

    Here, this paper illustrates the morphing of flow architecture toward greater performance in a counterflow heat exchanger. The architecture consists of two plenums with a core of counterflow channels between them. Each stream enters one plenum and then flows in a channel that travels the core and crosses the second plenum. The volume of the heat exchanger is fixed while the volume fraction occupied by each plenum is variable. Performance is driven by two objectives, simultaneously: low flow resistance and low thermal resistance. The analytical and numerical results show that the overall flow resistance is the lowest when the coremore » is absent, and each plenum occupies half of the available volume and is oriented in counterflow with the other plenum. In this configuration, the thermal resistance also reaches its lowest value. These conclusions hold for fully developed laminar flow and turbulent flow through the core. The curve for effectiveness vs number of heat transfer units (Ntu) is steeper (when Ntu < 1) than the classical curves for counterflow and crossflow.« less

  12. Flat plate heat exchangers for the new production reactor

    SciTech Connect

    Ondrejcin, R.S.

    1988-12-07

    The New Production Reactor (NPR) will require heat exchangers (HX) as part of the ancillary equipment. The most common type of heat exchanger in the US is the shell and tube, the type presently in SRP reactor service. This type of design is the one that is normally described in detail in heat transfer texts. Other designs are more efficient, and there was a period when these designs were actively modified. The largest driving force for higher efficiency HX was the OPEC produced energy shortage of the early 1970's. Several comments were made by B.S. Spangler about flat plate HX for the NPR after my initial comparison between shell and tube and flat plate HX (DPST-88-729). Since answers were not readily available, Philippe Marchal of Packinox (Louveciennes, France) agreed to visit SRL. This report contains a series of answers to all comments raised in DPST-88-743 and some general statements comparing flat plate HX to shell and tube HX. 1 fig., 2 tabs.

  13. Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

    NASA Astrophysics Data System (ADS)

    Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

    2016-06-01

    Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Hansen, Scott; Poynot, Joe

    2014-01-01

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

  16. Design of heat exchanger for Ericsson-Brayton piston engine.

    PubMed

    Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef; Holubcik, Michal; Nosek, Radovan

    2014-01-01

    Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy--energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

  17. Development of Passive Fuel Cell Thermal Management Heat Exchanger

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  18. Design of Heat Exchanger for Ericsson-Brayton Piston Engine

    PubMed Central

    Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef

    2014-01-01

    Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy—energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element. PMID:24977174

  19. Modeling Urban Surface-Atmosphere Sensible Heat Exchanges

    NASA Astrophysics Data System (ADS)

    Roberts, S. M.; Oke, T.; Lemonsu, A.; Grimmond, C.; Jackson, P.

    2003-12-01

    Understanding the nature of energy partitioning at the surface of cities is prerequisite to gaining proper insight and ability to model their climatic environment and impacts. Of particular relevance in the urban setting is the surface-atmosphere exchange of sensible heat. The combined conductive-convective exchange of turbulent sensible heat flux (QH) and net storage heat flux (Δ QS) has been shown to account for over 90% of the daytime net radiation at highly urbanized sites. This relation depends on surface structure, materials and the degree of surface-atmosphere coupling and its understanding is required in many applications; for example, to assess building climates, and to model evapo-transpiration, the urban heat island, and boundary layer growth. Observational studies, while allowing for general awareness of urban surface-atmosphere energetic interactions, are often limited in their applicability to other urban sites and/or processes. To overcome this, numerical models which aim to simulate urban climates have been developed. The Town Energy Balance (TEB) model of Masson (2000) couples the micro- and meso- scales and accurately represents the urban energy budget in meso-scale atmospheric models. TEB uses local canyon geometry together with surface and substrate radiative, thermal, moisture and roughness properties to simulate the effects produced by the presence of buildings. The urban system is simulated by calculating individual energy balances for walls, roads, and roofs, which are then integrated to resolve the local-scale surface energy balance. The model has been independently evaluated using measured fluxes from three dry sites - central Mexico City, a light industrial site in Vancouver (Masson et al., 2002) and the city center of Marseille, France (Lemonsu et al., 2003). At these sites, TEB simulated net radiation to within less than 10 W m-2 and its partitioning into turbulent and storage heat fluxes to within a few tens of W -2. TEB's good

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

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1992-01-01

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

  1. Vapor Compression and Thermoelectric Heat Pump Heat Exchangers for a Condensate Distillation System: Design and Experiment

    NASA Technical Reports Server (NTRS)

    Erickson, Lisa R.; Ungar, Eugene K.

    2013-01-01

    Maximizing the reuse of wastewater while minimizing the use of consumables is critical in long duration space exploration. One of the more promising methods of reclaiming urine is the distillation/condensation process used in the cascade distillation system (CDS). This system accepts a mixture of urine and toxic stabilizing agents, heats it to vaporize the water and condenses and cools the resulting water vapor. The CDS wastewater flow requires heating and its condensate flow requires cooling. Performing the heating and cooling processes separately requires two separate units, each of which would require large amounts of electrical power. By heating the wastewater and cooling the condensate in a single heat pump unit, mass, volume, and power efficiencies can be obtained. The present work describes and compares two competing heat pump methodologies that meet the needs of the CDS: 1) a series of mini compressor vapor compression cycles and 2) a thermoelectric heat exchanger. In the paper, the system level requirements are outlined, the designs of the two heat pumps are described in detail, and the results of heat pump performance tests are provided. A summary is provided of the heat pump mass, volume and power trades and a selection recommendation is made.

  2. Heat as a tracer to determine streambed water exchanges

    USGS Publications Warehouse

    Constantz, J.

    2010-01-01

    This work reviews the use of heat as a tracer of shallow groundwater movement and describes current temperature-based approaches for estimating streambed water exchanges. Four common hydrologic conditions in stream channels are graphically depicted with the expected underlying streambed thermal responses, and techniques are discussed for installing and monitoring temperature and stage equipment for a range of hydrological environments. These techniques are divided into direct-measurement techniques in streams and streambeds, groundwater techniques relying on traditional observation wells, and remote sensing and other large-scale advanced temperatureacquisition techniques. A review of relevant literature suggests researchers often graphically visualize temperature data to enhance conceptual models of heat and water flow in the near-stream environment and to determine site-specific approaches of data analysis. Common visualizations of stream and streambed temperature patterns include thermographs, temperature envelopes, and one-, two-, and three-dimensional temperature contour plots. Heat and water transport governing equations are presented for the case of transport in streambeds, followed by methods of streambed data analysis, including simple heat-pulse arrival time and heat-loss procedures, analytical and time series solutions, and heat and water transport simulation models. A series of applications of these methods are presented for a variety of stream settings ranging from arid to continental climates. Progressive successes to quantify both streambed fluxes and the spatial extent of streambeds indicate heat-tracing tools help define the streambed as a spatially distinct field (analogous to soil science), rather than simply the lower boundary in stream research or an amorphous zone beneath the stream channel.

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

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.

    1980-01-01

    Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube and shell that exchanger, and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over fifty inorganic salt mixtures investigated. Preliminary experiments with various tube coatings indicated that a nickel or chrome plating of Teflon or Ryton coating had promise of being successful. An electroless nickel plating was selected for further testing. A series of tests with nickel-plated heat transfer tubes showed that the solidifying sodium nitrate adhered to the tubes and the experiment failed to meet the required discharge heat transfer rate of 10 kW(t). Testing of the reflux boiler is under way.

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

    NASA Astrophysics Data System (ADS)

    Lefrois, R. T.

    1980-03-01

    Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube and shell that exchanger, and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over fifty inorganic salt mixtures investigated. Preliminary experiments with various tube coatings indicated that a nickel or chrome plating of Teflon or Ryton coating had promise of being successful. An electroless nickel plating was selected for further testing. A series of tests with nickel-plated heat transfer tubes showed that the solidifying sodium nitrate adhered to the tubes and the experiment failed to meet the required discharge heat transfer rate of 10 kW(t). Testing of the reflux boiler is under way.

  5. Effect of Surface-mantle Water Exchange Parameterizations on Exoplanet Ocean Depths

    NASA Astrophysics Data System (ADS)

    Komacek, Thaddeus D.; Abbot, Dorian S.

    2016-11-01

    Terrestrial exoplanets in the canonical habitable zone may have a variety of initial water fractions due to random volatile delivery by planetesimals. If the total planetary water complement is high, the entire surface may be covered in water, forming a “waterworld.” On a planet with active tectonics, competing mechanisms act to regulate the abundance of water on the surface by determining the partitioning of water between interior and surface. Here we explore how the incorporation of different mechanisms for the degassing and regassing of water changes the volatile evolution of a planet. For all of the models considered, volatile cycling reaches an approximate steady state after ∼ 2 {Gyr}. Using these steady states, we find that if volatile cycling is either solely dependent on temperature or seafloor pressure, exoplanets require a high abundance (≳ 0.3 % of total mass) of water to have fully inundated surfaces. However, if degassing is more dependent on seafloor pressure and regassing mainly dependent on mantle temperature, the degassing rate is relatively large at late times and a steady state between degassing and regassing is reached with a substantial surface water fraction. If this hybrid model is physical, super-Earths with a total water fraction similar to that of the Earth can become waterworlds. As a result, further understanding of the processes that drive volatile cycling on terrestrial planets is needed to determine the water fraction at which they are likely to become waterworlds.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    SciTech Connect

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

    1994-06-01

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

  8. Improvement in performance of heat exchanger fitted with twisted tape

    SciTech Connect

    Sivashanmugam, P.; Sundaram, S.

    1999-04-01

    The improvement in performance of a double pipe heat exchanger fitted with twisted tape as a turbulence promoter with twist ratios of 15.649, 8.54, 5.882, 4.95, and 4.149 was experimentally studied. A maximum percentage gain of 44.7% in energy transfer rate was obtained for the twisted tape of twist ratio 4.149. For all twist ratios, the gain decreases with the Reynolds number and becomes constant for Reynolds numbers greater than 3,000. The smaller the twist ratio is, the larger the gain in energy for a specific Reynolds number.

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

    SciTech Connect

    Vine, E.

    1987-02-01

    Air-to-air heat exchangers were installed in 366 energy-efficient homes as part of a demonstration program in the United States. The median incremental cost of AAHX was $1268 ($7.42/mS), and it was less expensive (per square meter) to install this equipment in larger houses than in smaller houses. While most occupants did not notice problems with their AAHX, some households did experience problems related to noise, unpleasant drafts, condensation around the AAHX, and core freezing. Occupants of energy-efficient homes were found to have less problems with their indoor environment (especially mildew/mold and condensation) than a group of control homes.

  10. Heat exchanger. [rocket combustion chambers and cooling systems

    NASA Technical Reports Server (NTRS)

    Sokolowski, D. E. (Inventor)

    1978-01-01

    A heat exchanger, as exemplified by a rocket combustion chamber, is constructed by stacking thin metal rings having microsized openings therein at selective locations to form cooling passages defined by an inner wall, an outer wall and fins. Suitable manifolds are provided at each end of the rocket chamber. In addition to the cooling channel openings, coolant feed openings may be formed in each of rings. The coolant feed openings may be nested or positioned within generally U-shaped cooling channel openings. Compression on the stacked rings may be maintained by welds or the like or by bolts extending through the stacked rings.

  11. Testing of heat exchanger systems for reheating flue gases from wet scrubbing desulfurization plants

    NASA Astrophysics Data System (ADS)

    Than, K.

    1982-09-01

    Two heat exchanger systems: the cyclic process of GEA and, the plate heat exchanger of Kablitz/Thyssen, for reheating flue gases, which have been cooled to about 50 to 55 C due to wet scrubbing, to the required temperature at the outlet of the stack by extracting the sensible heat of the hot flue gases were tested. The problem of building materials and on keeping clean the heat exchanger surface are emphasized.

  12. Properties of Alloy 617 for Heat Exchanger Design

    SciTech Connect

    Wright, Richard Neil; Carroll, Laura Jill; Benz, Julian Karl; Wright, Julie Knibloe; Lillo, Thomas Martin; Lybeck, Nancy Jean

    2014-10-01

    Abstract – Alloy 617 is among the primary candidates for very high temperature reactor heat exchangers anticipated for use up to 950ºC. Elevated temperature properties of this alloy and the mechanisms responsible for the observed tensile, creep and creep-fatigue behavior have been characterized over a wide range of test temperatures up to 1000ºC. Properties from the current experimental program have been combined with archival information from previous VHTR research to provide large data sets for many heats of material, product forms, and weldments. The combined data have been analyzed to determine conservative values of yield and tensile strength, strain rate sensitivity, creep-rupture behavior, fatigue and creep- fatigue properties that can be used for engineering design of reactor components. Phenomenological models have been developed to bound the regions over which the engineering properties are well known or can be confidently extrapolated for use in design.

  13. Study of thermal energy storage using fluidized bed heat exchangers

    NASA Technical Reports Server (NTRS)

    Weast, T. E.; Shannon, L. J.; Ananth, K. P.

    1980-01-01

    The technical and economic feasibility of fluid bed heat exchangers (FBHX) for thermal energy storage (TES) in waste heat recovery applications is assessed by analysis of two selected conceptual systems, the rotary cement kiln and the electric arc furnace. It is shown that the inclusion of TES in the energy recovery system requires that the difference in off-peak and on-peak energy rates be large enough so that the value of the recovered energy exceeds the value of the stored energy by a wide enough margin to offset parasitic power and thermal losses. Escalation of on-peak energy rates due to fuel shortages could make the FBHX/TES applications economically attractive in the future.

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

    NASA Technical Reports Server (NTRS)

    Kim, Rhyn H.

    1992-01-01

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

  15. Design and simulation of heat exchangers using Aspen HYSYS, and Aspen exchanger design and rating for paddy drying application

    NASA Astrophysics Data System (ADS)

    Janaun, J.; Kamin, N. H.; Wong, K. H.; Tham, H. J.; Kong, V. V.; Farajpourlar, M.

    2016-06-01

    Air heating unit is one of the most important parts in paddy drying to ensure the efficiency of a drying process. In addition, an optimized air heating unit does not only promise a good paddy quality, but also save more for the operating cost. This study determined the suitable and best specifications heating unit to heat air for paddy drying in the LAMB dryer. In this study, Aspen HYSYS v7.3 was used to obtain the minimum flow rate of hot water needed. The resulting data obtained from Aspen HYSYS v7.3 were used in Aspen Exchanger Design and Rating (EDR) to generate heat exchanger design and costs. The designs include shell and tubes and plate heat exchanger. The heat exchanger was designed in order to produce various drying temperatures of 40, 50, 60 and 70°C of air with different flow rate, 300, 2500 and 5000 LPM. The optimum condition for the heat exchanger were found to be plate heat exchanger with 0.6 mm plate thickness, 198.75 mm plate width, 554.8 mm plate length and 11 numbers of plates operating at 5000 LPM air flow rate.

  16. Experimental investigation of plastic finned-tube heat exchangers, with emphasis on material thermal conductivity

    SciTech Connect

    Chen, Lin; Li, Zhen; Guo, Zeng-Yuan

    2009-07-15

    In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)

  17. Theoretical investigation on thermal performance of heat pipe flat plate solar collector with cross flow heat exchanger

    NASA Astrophysics Data System (ADS)

    Xiao, Lan; Wu, Shuang-Ying; Zhang, Qiao-Ling; Li, You-Rong

    2012-07-01

    Based on the heat transfer characteristics of absorber plate and the heat transfer effectiveness-number of heat transfer unit method of heat exchanger, a new theoretical method of analyzing the thermal performance of heat pipe flat plate solar collector with cross flow heat exchanger has been put forward and validated by comparisons with the experimental and numerical results in pre-existing literature. The proposed theoretical method can be used to analyze and discuss the influence of relevant parameters on the thermal performance of heat pipe flat plate solar collector.

  18. Analysis of induced temperature anomalies along borehole heat exchangers

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. Numerical analysis of heat exchange processes for the ground source heat pump system

    NASA Astrophysics Data System (ADS)

    Saito, H.; Muto, H.; Moritani, S.; Kohgo, Y.; Hamamoto, S.; Takemura, T.; Ohnishi, J.; Komatsu, T.

    2012-12-01

    Ground source heat pump systems (GSHP) use ground or groundwater as a heat source. They can achieve much higher coefficient of performance (COP) than conventional air source heat pump systems because the temperature of the ground is much more stable than that of the air. Heat energy in the ground is then viewed as one of the renewable energy sources. GSHP has been receiving great interests among countries in North America and Western Europe, as well as some developed countries in Asia because it can potentially reduce energy consumption and greenhouse gas emission. While GSHP can inject heat from the buildings to the ground for cooling during the summer, it can pump heat stored in the ground for heating during the winter. As some physical, chemical, and biological properties of the ground and groundwater are temperature dependent, running GSHP can eventually affect groundwater quality. The main objective of this project was to develop a model that allows predicting not only ground and groundwater temperatures but also changes in physical, chemical, and biological properties of ground and groundwater with GSHP under operations. This particular study aims at simulating heat exchange and transfer processes in the ground for a vertical-loop closed GSHP system. In the closed GSHP system, an anti-freezing solution is circulated inside the closed-loop tube, called U-tube, that is buried in the ground. Heat is then transferred to the anti-freezing solution in the U-tube by a heat exchanger. In this study we used HYDRUS to predict temperature of the anti-freezing solution, as well as that of the ground. HYDRUS allows one to simulate variably-saturated water flow and solute and heat transport in porous media numerically in two- and three-dimensional domains with great flexibility in defining boundary conditions. At first changes in anti-freezing solution temperatures measured were predicted in response to Thermal Response Test (TRT) conducted at our study site. Then, heat

  20. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    PubMed Central

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

  1. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

    PubMed

    Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

    2017-01-12

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  2. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    NASA Astrophysics Data System (ADS)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

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

    NASA Technical Reports Server (NTRS)

    Howell, H. R.

    1983-01-01

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

  4. Integrated heat exchanger design for a cryogenic storage tank

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Tomsik, T. M.; Bonner, T.; Oliveira, J. M.; Conyers, H. J.; Johnson, W. L.; Notardonato, W. U.

    2014-01-01

    Field demonstrations of liquid hydrogen technology will be undertaken for the proliferation of advanced methods and applications in the use of cryofuels. Advancements in the use of cryofuels for transportation on Earth, from Earth, or in space are envisioned for automobiles, aircraft, rockets, and spacecraft. These advancements rely on practical ways of storage, transfer, and handling of liquid hydrogen. Focusing on storage, an integrated heat exchanger system has been designed for incorporation with an existing storage tank and a reverse Brayton cycle helium refrigerator of capacity 850 watts at 20 K. The storage tank is a 125,000-liter capacity horizontal cylindrical tank, with vacuum jacket and multilayer insulation, and a small 0.6-meter diameter manway opening. Addressed are the specific design challenges associated with the small opening, complete modularity, pressure systems re-certification for lower temperature and pressure service associated with hydrogen densification, and a large 8:1 length-to-diameter ratio for distribution of the cryogenic refrigeration. The approach, problem solving, and system design and analysis for integrated heat exchanger are detailed and discussed. Implications for future space launch facilities are also identified. The objective of the field demonstration will be to test various zero-loss and densified cryofuel handling concepts for future transportation applications.

  5. Integrated heat exchanger design for a cryogenic storage tank

    SciTech Connect

    Fesmire, J. E.; Bonner, T.; Oliveira, J. M.; Johnson, W. L.; Notardonato, W. U.; Tomsik, T. M.; Conyers, H. J.

    2014-01-29

    Field demonstrations of liquid hydrogen technology will be undertaken for the proliferation of advanced methods and applications in the use of cryofuels. Advancements in the use of cryofuels for transportation on Earth, from Earth, or in space are envisioned for automobiles, aircraft, rockets, and spacecraft. These advancements rely on practical ways of storage, transfer, and handling of liquid hydrogen. Focusing on storage, an integrated heat exchanger system has been designed for incorporation with an existing storage tank and a reverse Brayton cycle helium refrigerator of capacity 850 watts at 20 K. The storage tank is a 125,000-liter capacity horizontal cylindrical tank, with vacuum jacket and multilayer insulation, and a small 0.6-meter diameter manway opening. Addressed are the specific design challenges associated with the small opening, complete modularity, pressure systems re-certification for lower temperature and pressure service associated with hydrogen densification, and a large 8:1 length-to-diameter ratio for distribution of the cryogenic refrigeration. The approach, problem solving, and system design and analysis for integrated heat exchanger are detailed and discussed. Implications for future space launch facilities are also identified. The objective of the field demonstration will be to test various zero-loss and densified cryofuel handling concepts for future transportation applications.

  6. Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

    SciTech Connect

    Pilyugin, N.N.; Chernova, T.A.

    1986-07-01

    The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted.

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

    NASA Technical Reports Server (NTRS)

    Alario, J.; Kosson, R.; Haslett, R.

    1980-01-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application (300 MW sub t storage for 6 hours). Two concepts were selected for hardware development: (1) a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and (2) a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which was nickel plated to decrease adhesion forces. In addition to improving performance by providing a nearly constant transfer rate during discharge, these active heat exchanger concepts were estimated to cost at least 25% less than the passive tube-shell design.

  8. Continuation of Studies on Development of ODS Heat Exchanger Tubing

    SciTech Connect

    Lawrence Brown; David Workman; Bimal Kad; Gaylord Smith; Archie Robertson; Ian Wright

    2008-04-15

    The Department of Energy (DOE), National Energy Technology Center (NETL), has initiated a strategic plan for the development of advanced technologies needed to design and build fossil fuel plants with very high efficiency and environmental performance. These plants, referred to as 'Vision 21' and FutureGen programs by DOE, will produce electricity, chemicals, fuels, or a combination of these products, and possibly secondary products such as steam/heat for industrial use. MA956 is a prime candidate material being considered for a high temperature heat exchanger in the 'Vision 21' and FutureGen programs. This material is an oxide dispersion strengthened (ODS) alloy; however, there are some gaps in the data required to commit to the use of these alloys in a full-size plant. To fill the technology gaps for commercial production and use of the material for 'Advanced Power Generation Systems' this project has performed development activity to significant increase in circumferential strength of MA956 as compared to currently available material, investigated bonding technologies for bonding tube-to-tube joints through joining development, and performed tensile, creep and fire-side corrosion tests to validate the use and fabrication processes of MA956 to heat exchanger tubing applications. Development activities within this projected has demonstrated increased circumferential strength of MA956 tubes through flow form processing. Of the six fabrication technologies for bonding tube-to-tube joints, inertia friction welding (IFW) and flash butt welding (FBW) were identified as processes for joining MA956 tubes. Tensile, creep, and fire-side corrosion test data were generated for both base metal and weld joints. The data can be used for design of future systems employing MA956. Based upon the positive development activities, two test probes were designed and fabricated for field exposure testing at 1204 C ({approx}2200 F) flue gas. The probes contained tube portions with FBW

  9. 40 CFR 63.1084 - What heat exchange systems are exempt from the requirements of this subpart?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Units: Heat Exchange Systems and Waste Operations Applicability for Heat Exchange Systems § 63.1084 What... (a) through (e) of this section. (a) Your heat exchange system operates with the minimum pressure on... normal range. (e) Your recirculating or once-through heat exchange system cools process fluids...

  10. Experimental and theoretical analysis of the local condensation heat transfer in a plate heat exchanger

    NASA Astrophysics Data System (ADS)

    Grabenstein, V.; Kabelac, S.

    2012-11-01

    Plate heat exchanger (PHE) are today widely used in industrial heat transfer applications due to their good thermal performance, modest space requirement, easy accessibility to all areas and their lower capital and operating costs as compared to shell-and-tube heat exchangers. Although authoritative models for the design of PHE used as condensers are missing, the number of applications where a PHE is operating as a condenser increases. On the way to a reliable model based on physical approaches for the prediction of heat transfer and pressure drop during the condensation process inside a PHE, the flow and heat interactions as well as their dependence on the geometrical parameters of the corrugated plates and the operating conditions must be studied in detail. In this work the stepwise procedure for the fundamental construction of such a model is described. An experimental setup was built to analyze the characteristics of the two-phase-flow in PHE. A single gap, consisting of two transparent corrugated plates, was tested with a two-phase flow of air/water and also with boiling refrigerant R365mfc. Flow pattern maps were constructed for plates with corrugation angles of 27 and 63 degrees relative to the direction of flow. Investigations of the local heat transfer coefficients and the pressure drop were done with the same plates. The measurement of the local heat transfer coefficients was carried out by the use of the "Temperature Oscillation InfraRed Thermography" (TOIRT) method. Based on these results three main flow patterns are defined: film flow, bubbly flow and slug flow. For each of the three flow patterns an own model for the heat transfer and pressure drop mechanism are developed and the heat transfer coefficient and the friction factor is calculated with different equations depending on the actual steam quality, mass flow and geometrical parameters by means of a flow pattern map. The theory of the flow pattern based prediction models is proved with own

  11. Heat Exchangers for Heavy Vehicles Utilizing High Thermal Conductivity Graphite Foams

    SciTech Connect

    James Klett, Ron Ott; April McMillan

    2000-06-19

    Approximately two thirds of the world's energy consumption is wasted as heat. In an attempt to reduce heat losses, heat exchangers are utilized to recover some of the energy. A unique graphite foam developed at the Oak Ridge National Laboratory (ORNL) and licensed to Poco Graphite, Inc., promises to allow for novel, more efficient heat exchanger designs. This graphite foam, Figure 1, has a density between 0.2 and 0.6 g/cm 3 and a bulk thermal conductivity between 40 and 187 W/m{center_dot}K. Because the foam has a very accessible surface area (> 4 m 2 /g) and is open celled, the overall heat transfer coefficients of foam-based heat exchangers can be up to two orders of magnitude greater than conventional heat exchangers. As a result, foam-based heat exchangers could be dramatically smaller and lighter.

  12. Experimental Investigation on Heat Transfer and Frictional Characteristics of Shell-and-tube Heat exchangers with Different Baffles and Tubes

    NASA Astrophysics Data System (ADS)

    Wang, C.; Zhu, J. G.; Sang, Z. F.

    2010-03-01

    In this study, the heat transfer and tube frictional characteristics of the helixchangers (shell-and-tube heat exchanger with helical baffles) with spirally corrugated and smooth tubes and the conventional shell-and-tube heat exchanger with smooth tubes were experimentally obtained. The results show that the helixchangers with the spirally corrugated tube and the smooth tubes enhance the total heat transfer coefficient about 26% and 7% on the average than the segmental baffled heat exchanger. In the tube side, the spirally corrugated tube leads to about 28% average increase on convective heat transfer performance and about 24% average increase on pressure drop than the smooth tube, but its conversion efficiency is still higher. The helical baffle could enhance the shell-side condensation coefficient by 13%, and the spirally corrugated tube could help the helixchanger with it enhance remarkably the condensation performance by 53% than the segmental baffled heat exchanger.

  13. 40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of...

  14. 40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of...

  15. 40 CFR 63.2490 - What requirements must I meet 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 What requirements must I meet for heat... must I meet for heat exchange systems? (a) You must comply with each requirement in Table 10 to this subpart that applies to your heat exchange systems, except as specified in paragraphs (b) and (c) of...

  16. 40 CFR 63.8030 - What requirements apply to my heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 13 2010-07-01 2010-07-01 false What requirements apply to my heat... apply to my heat exchange systems? (a) You must comply with the requirements specified in Table 6 to this subpart that apply to your heat exchange systems, except as specified in paragraphs (b) through...

  17. 40 CFR 63.2490 - What requirements must I meet for heat exchange systems?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true What requirements must I meet for heat... must I meet for heat exchange systems? (a) You must comply with each requirement in Table 10 to this subpart that applies to your heat exchange systems, except as specified in paragraphs (b) and (c) of...

  18. 40 CFR 63.8030 - What requirements apply to my heat exchange systems?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 13 2011-07-01 2011-07-01 false What requirements apply to my heat... apply to my heat exchange systems? (a) You must comply with the requirements specified in Table 6 to this subpart that apply to your heat exchange systems, except as specified in paragraphs (b) through...

  19. An Integrated Chemical Reactor-Heat Exchanger Based on Ammonium Carbamate (POSTPRINT)

    DTIC Science & Technology

    2012-10-01

    display, or disclose the work. 14. ABSTRACT In this work we present our recent effort in developing a novel heat exchanger based on endothermic ...conditions. 15. SUBJECT TERMS aircraft thermal management, ammonium carbamate, chemical reactor heat exchanger, endothermic decomposition 16... endothermic chemical reaction (HEX reactor). The proposed HEX reactor is designed to provide additional heat sink capability for aircraft thermal management

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

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Shariatmadar, A.

    1987-01-01

    This paper describes a lightweight, highly effective liquid droplet heat exchanger (LDHX) concept for thermal management in space. Heat is transferred by direct contact between fine droplets (100 to 300 micron diameter) of a low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the microgravity environment is accomplished by configuring the LDHX as a vortex chamber. A quasi-one-dimensional, two-phase heat transfer model of the LDHX is developed and used to investigate the potential use of the LDHX for both heating and cooling the working gas in a 100-k W(e) Braytoan cycle. Experimental studies on a small scale LDHX chamber, using air and water as the two media, show excellent agreement with the theoretical model.

  1. 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.

  2. Heat transfer from earth-coupled heat exchangers-Experimental and analytical results

    SciTech Connect

    Edwards, J.A.; Vitta, P.K.

    1985-01-01

    Experimental heat transfer results obtained with tubular heat transfer coils buried in soil are presented along with a finite difference simulation model that predicts the heat transfer to or from the buried pipes and the temperature distribution in the soil surrounding the buried pipes. The results were obtained with two different earth-coupled coils. Each coil was fabricated from 2.2 in. (5.6 cm) ID nominal 2 in. diameter cast iron pipe. The length of the heat exchanger for each earth-coupled system was 90 ft. (27.4 m). The earth-coupled coils were buried at a depth of 2.75 ft. (0.84 m) below the surface of the earth. The experimental data cover a time span of seven months and represent operation of the earth-coupled coils at various heat rates. Some of the prime quantities measured on a continuous basis are the earth's temperature at several locations in the vicinity of the buried coils, the far earth temperature, the solar insolation, moisture content of the soil, and the heat transferred to or from the buried coils to the surrounding soil. The finite difference model tracks the temperature distribution in the earth surrounding the coils on a continuous basis and predicts the earth's temperature at many locations adjacent to the earth-coupled coil with a maximum error of 4/sup 0/F (2.2/sup 0/C) during the seven month test. As parameters, the finite difference model included the moisture content of the soil, convection at the surface of the earth, emissivity of the soil, radiation exchange at the air-soil interface, as well as all of the pertinent parameters related to the flow of the heat transfer fluid through the buried pipes. The results presented, both experimental and simulated, have direct application in the design of earth-coupled water-source heat pump systems.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  4. Initial characterization of a modular heat exchanger with an integral heat pipe. [for Stirling space engine

    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 engibe (SSE) was generated 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. An existing FPSE was modified as a test bed for a modular heat exchanger evaluation. Evaluation of the individual heat pipes before installation in the engine is described.

  5. Performance of plate type heat exchanger as ammonia condenser

    NASA Astrophysics Data System (ADS)

    Rivera, Andrew

    In this study, I experimentally analyzed the performance of a commercial semi-welded plate type heat exchanger (PHE) for use with ammonia systems. I determined performance parameters such as overall heat transfer coefficient, capacity, and pressure drop of the semi-welded PHE. This was analyzed by varying different parameters which demonstrated changes in overall heat transfer coefficient, capacity, and pressure drop. Both water and ammonia flow rates to the semi-welded PHE were varied independently, and analyzed in order to understand how changes in flow rates affected performance. Inlet water temperature was also varied, in order to understand how raising condenser water inlet temperature would affect performance. Finally, pressure drop was monitored to better understand the performance limitations of the semi-welded PHE. Testing of the semi-welded will give insight as to the performance of the semi-welded PHE in a potential ocean thermal energy conversion system, and whether the semi-welded PHE is a viable choice for use as an ammonia condenser.

  6. Heat exchange at laminar flow in rectangular channels

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  7. Erosion of heat exchanger tubes in fluidized beds

    SciTech Connect

    Johnson, E.K.; Flemmer, R.L.C.

    1991-01-01

    This final report describes the activities of the 3-year project entitled Erosion of Heat Exchanger Tubes In Fluidized Beds.'' which was completed at the end of 1990. Project accomplishments include the collection of a substantial body of wear data In a 24in. [times] 24in. fluidized bed, comparative wear results In a 6in. [times] 6in. fluidized bed, the development of a dragometer and the collection of a comprehensive set of drag force data in the 24in. [times] 24in. bed, Fast Fourier Transform (FFT) analysis of bubble probe data to establish dominant bubble frequencies in the 24in. [times] 24in. bed, the use of a heat flux gauge for measurement of heat transfer coefficients in the 24in. [times] 24in. bed and the modeling of the tube wear in the 24in. [times] 24in. bed. Analysis of the wear data from the 24in. square bed indicates that tube wear increases with increase in superficial velocity, and with increase in tube height. The latter effect is a result of the tubes higher up in the bed seeing greater movement of dense phase than tubes lower down In the bed. In addition, tube wear was found to decrease with increase in particle size, for constant superficial velocity. Three models of tube wear were formulated and provided acceptable prediction of wear when compared with the experimental data.

  8. Efficiency of airway heat and moisture exchangers in anesthetized humans.

    PubMed

    Bickler, P E; Sessler, D I

    1990-10-01

    The efficiencies of airway heat and moisture exchanging filters in reducing respiratory water losses and increasing airway temperatures during general anesthesia were studied in five tracheally intubated patients given isoflurane, nitrous oxide, and oxygen anesthesia during controlled ventilation. Filters (Humid-Vent Filter, Humid-Vent 1, Pall Conserve, Siemens 150, and ThermoVent 600) were placed between the Y-piece of the anesthesia circle system and the endotracheal tube for 40 min each. Airway temperature, esophageal temperature, and water loss (determined by weighing expired water collected in CaSO4) were measured every 10 min. All of the filters reached near-maximum efficiency in reducing water losses within 10 min. The Humid-Vent Filter and Siemens 150 filters were most efficient, the Pall Conserve and ThermoVent 600 less efficient. Airway temperature rapidly increased 2 degrees-8 degrees C during each trial. The more efficient the filter in conserving water, the greater the airway temperature. The respiratory heat conserved by these filters represents 5.5%-7.2% of the estimated total metabolic heat production during anesthesia in adults.

  9. Study of heat exchange in cooling systems of heat-stressed structures

    NASA Astrophysics Data System (ADS)

    Vikulin, A. V.; Yaroslavtsev, N. L.; Zemlyanaya, V. A.

    2017-01-01

    Increasing working parameters of the cycle of gas-turbine engines, complicating design of gas-turbine plants, as well as growing aerodynamic, thermal, static, and dynamic loads, necessitate the development of promising cooling systems for heat-stressed structures. This work is devoted to an experimental study of heat exchange in ducts equipped with systems of inclined and cross walls (fins). It has been found that an increase in the Reynolds number Re from 3000 to 20000 leads to a decrease in the heat exchange, which is characterized by the relative Nusselt number overline{Nu}, by 19-30% at the angle of inclination of the walls φ = 0, 40°, 50°, and 90° if the length of the walls x w is comparable to the spacing b s and by 12-15% at φ = 30° and 90° if x w ≫ b s. If cross walls are used in cooling ducts, the length of the walls x w plays the governing role; an increase in this characteristic from 1.22 × 10-3 to 3.14 × 10-3 m leads to an increase in the intensity of heat exchange by 30-40% and to a decrease in the capacity of the entire system of the walls. It has been shown that, on surfaces with wavy fins, the intensity of heat exchange is closest to that determined in the models under study. For example, values of the Colborne criterion StPr2/3 for ducts equipped with wavy fins and for the models under study differ only slightly (by 2-20% depending on the value of the angle φ). However, the difference for surfaces with short plate fins and ducts equipped with inclined walls is high (30-40%). This is due to the design features of these surfaces and to the severe effect of the inlet portion on heat exchange, since the surfaces are characterized by a higher ratio of the duct length to the hydraulic diameter L/d h at small fin thicknesses ((0.1-0.15) × 10-3 m). The experimental results can be used in developing designs of nozzle and rotor blades of high-temperature gas turbines in gas-turbine engines and plants.

  10. The Effects of the Heat and Moisture Exchanger on Humidity, Airway Temperature, and Core Body Temperature

    DTIC Science & Technology

    1999-10-01

    was added to the experimental group. Three more measurements were recorded at 10, 30 and 60 minutes after the insertion of the heat and moisture...heat and moisture exchanger provided adequate humidification of the inspired gases. In the experimental group, there was no difference in...exchanger incorporated in the ventilator Heat and Moisture Exchangers 16 circuit (the experimental group) and 10 did not (the control group

  11. Analytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger

    SciTech Connect

    Su-Jong Yoon; Piyush Sabharwall; Eung-Soo Kim

    2013-09-01

    The analytical methodologies for the thermal design, mechanical design and cost estimation of printed circuit heat exchanger are presented in this study. In this study, three flow arrangements of parallel flow, countercurrent flow and crossflow are taken into account. For each flow arrangement, the analytical solution of temperature profile of heat exchanger is introduced. The size and cost of printed circuit heat exchangers for advanced small modular reactors, which employ various coolants such as sodium, molten salts, helium, and water, are also presented.

  12. Single and Multiresponse Adaptive Design of Experiments with Application to Design Optimization of Novel Heat Exchangers

    DTIC Science & Technology

    2009-01-01

    performance evaluation method for air- cooled heat exchangers in which conventional 3D Computational Fluid Dynamics (CFD) simulation is replaced with a 2D...parts to this research thrust. First, is a new multi-level performance evaluation method for air- cooled heat exchangers in which conventional 3D...performance of a novel air- cooled heat exchanger such as tube-fin or microchannels . The novel aspect generally refers to a new fin design or a tube

  13. Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets

    SciTech Connect

    O'Brien, James Edward; Sohal, Manohar Singh

    2000-11-01

    This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally applied one-dimensional semi-infinite inverse heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.51 x 10-3 to 14.0 x 10-3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 670 – 6300 with a duct height of 1.106 cm and a duct width-toheight ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of a circular tube, a delta-winglet pair, and a combination of a circular tube and a delta-winglet pair. Comparisons of local and average heat transfer distributions for the circular tube with and without winglets are provided. Overall mean finsurface Nusselt-number results indicate a significant level of heat transfer enhancement associated with the deployment of the winglets with the circular cylinder. At the lowest Reynolds numbers (which correspond to the laminar operating conditions of existing geothermal air-cooled condensers), the enhancement level is nearly a factor of two. At higher Reynolds numbers, the enhancement level is close to 50%.

  14. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    SciTech Connect

    O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  15. Development of Design Criteria for Fluid Induced Structural Vibrations in Steam Generators and Heat Exchangers

    SciTech Connect

    Uvan Catton; Vijay K. Dhir; Deepanjan Mitra; Omar Alquaddoomi; Pierangelo Adinolfi

    2004-04-06

    Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains.

  17. 40 CFR 63.1083 - Does this subpart apply to my heat exchange system?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange... or operate an ethylene production unit expressly referenced to this subpart XX from subpart YY...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange... or operate an ethylene production unit expressly referenced to this subpart XX from subpart YY...

  19. 40 CFR 63.1083 - Does this subpart apply to my heat exchange system?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange... or operate an ethylene production unit expressly referenced to this subpart XX from subpart YY...

  20. 40 CFR 63.1083 - Does this subpart apply to my heat exchange system?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CATEGORIES (CONTINUED) National Emission Standards for Ethylene Manufacturing Process Units: Heat Exchange... or operate an ethylene production unit expressly referenced to this subpart XX from subpart YY...