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1

Scraped surface heat exchangers.  

PubMed

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. PMID:16527753

Rao, Chetan S; Hartel, Richard W

2006-01-01

2

Development of two heat transfer correlations for a scraped surface heat exchanger in an ice-cream machine  

Microsoft Academic Search

Heat transfer in presence of a high viscosity fluid may be substantially enhanced using heat exchangers supported by a mechanical agitation system that can also “scrape” the exchange surface (Scraped Surface Heat Exchanger, SSHE). In this case, heat transfer efficiency depends strongly on exchanger and agitator geometries, agitation methods as well as fluid characteristics and heat transfer conditions. Correlations used

L. Saraceno; G. Boccardi; G. P. Celata; R. Lazzarini; R. Trinchieri

2011-01-01

3

Development of a time temperature integrator for quantification of thermal treatment in scraped surface heat exchangers  

Microsoft Academic Search

When processing highly viscous fluids in scraped surface heat exchangers, it is often difficult to follow the real heat flux received by each part of the product. Only average temperatures are measured, and the process cannot always guarantee a correct thermal treatment. During a pasteurisation process, the average temperature is around 80 °C, but some parts of the product may not

Jérôme Mabit; Rachida Belhamri; Francine Fayolle; Jack Legrand

2008-01-01

4

A mathematical model of fluid flow in a scraped-surface heat exchanger  

Microsoft Academic Search

A simple mathematical model of fluid flow in a common type of scraped-surface heat exchanger in which the gaps between the\\u000a blades and the device walls are narrow, so that a lubrication-theory description of the flow is valid, is presented. Specifically\\u000a steady isothermal flow of a Newtonian fluid around a periodic array of pivoted scraper blades in a channel with

B. R. Duffy; S. K. Wilson; M. E. M. Lee

2007-01-01

5

Scrape  

MedlinePLUS

... soap and water. Large pieces of dirt or debris should be removed with tweezers. (Clean the tweezers ... provider if: The scrape contains dirt and other debris deep inside. The scrape is very large. The ...

6

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

Microsoft Academic Search

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

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

2002-01-01

7

Heat exchanger  

SciTech Connect

A heat exchanger having primary and secondary conduits in heat-exchanging relationship is described comprising: at least one serpentine tube having parallel sections connected by reverse bends, the serpentine tube constituting one of the conduits; a group of open-ended tubes disposed adjacent to the parallel sections, the open-ended tubes constituting the other of the conduits, and forming a continuous mass of contacting tubes extending between and surrounding the serpentine tube sections; and means securing the mass of tubes together to form a predetermined cross-section of the entirety of the mass of open-ended tubes and tube sections.

Drury, C.R.

1988-02-02

8

Segmented heat exchanger  

DOEpatents

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.

Baldwin, Darryl Dean (Lafayette, IN); Willi, Martin Leo (Dunlap, IL); Fiveland, Scott Byron (Metamara, IL); Timmons, Kristine Ann (Chillicothe, IL)

2010-12-14

9

Ceramics in heat exchangers  

Microsoft Academic Search

This book presents the papers given at a conference on the testing of ceramics for heat exchangers. Topics considered at the conference included advanced heat-transfer systems, heat recovery equipment, air-to-air heat exchangers, fluidized bed heat-recovery boilers, industrial heat recovery, potential materials, materials development and evaluation, chemical vapor deposition, product testing, fracture properties, and the durability of silicon carbide heat-exchanger tubes

B. D. Foster; J. B. Patton

1984-01-01

10

Serpentine heat exchanger  

Microsoft Academic Search

This patent describes a furnace having a burner means for providing hot products of combustion, and an air flow means for circulating conditioned air, a heat exchanger for transferring heat from products of combustion to conditioned air. The heat exchanger comprises first and second matched clamshell plates assembled together. The plates connected at their respective edges by a sealing means

1991-01-01

11

Fouling of carbon steel heat exchanger caused by iron bacteria  

SciTech Connect

A carbon steel heat exchanger installed in a reverse osmosis unit failed after 1 1/2 years from start-up as a result of tubes, lids, tube sheets, and connection pipes clogging from rust deposits. Chemical analysis of cooling water and scraped precipitates, as well laboratory screening of the deposits for bacteria, revealed that activity of iron-oxidizing bacteria present in cooling water could lead to heat exchanger blockage.

Starosvetsky, J.; Armon, R.; Starosvetsky, D. (Technion-Israel Inst. of Tech. (Israel)); Groysman, A.

1999-01-01

12

Wound tube heat exchanger  

DOEpatents

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.

Ecker, Amir L. (Duncanville, TX)

1983-01-01

13

Compact, super heat exchanger  

NASA Technical Reports Server (NTRS)

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.

Fortini, A.; Kazaroff, J. M.

1980-01-01

14

Nature's Heat Exchangers.  

ERIC Educational Resources Information Center

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)

Barnes, George

1991-01-01

15

Active microchannel heat exchanger  

DOEpatents

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.

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

2001-01-01

16

Microscale Regenerative Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

17

Heat and mass exchanger  

DOEpatents

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

Lowenstein, Andrew (Princeton, NJ); Sibilia, Marc J. (Princeton, NJ); Miller, Jeffrey A. (Hopewell, NJ); Tonon, Thomas (Princeton, NJ)

2007-09-18

18

Heat and mass exchanger  

DOEpatents

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

Lowenstein, Andrew (Princeton, NJ); Sibilia, Marc J. (Princeton, NJ); Miller, Jeffrey A. (Hopewell, NJ); Tonon, Thomas (Princeton, NJ)

2011-06-28

19

Thermoelectric heat exchange element  

DOEpatents

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

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

2007-08-14

20

Microtube Strip Heat Exchanger  

SciTech Connect

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

Doty, F.D.

1990-12-27

21

Radial flow heat exchanger  

DOEpatents

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

Valenzuela, Javier (Hanover, NH)

2001-01-01

22

Thermosyphon heat exchanger  

NASA Technical Reports Server (NTRS)

Report summarizes final development, testing, and certification of pumpless, liquid-to-air heat exchanger for solar heating. System requires blower but no pump in water loop. Output is 35,000 Btu/hr when water temperature is 49 C.

Hankins, J. D.

1980-01-01

23

Monogroove liquid heat exchanger  

NASA Technical Reports Server (NTRS)

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).

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

1990-01-01

24

Chimney heat exchanger  

SciTech Connect

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.

Whiteley, I.C.

1981-09-01

25

Microgravity condensing heat exchanger  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

26

Microtube strip heat exchanger  

SciTech Connect

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

Doty, F.D.

1991-10-16

27

Heat exchanger panel  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

28

Conquer heat exchanger fouling  

SciTech Connect

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

Mukherjee, R. [Engineers India Ltd., New Delhi (India)

1996-01-01

29

Serpentine heat exchanger  

SciTech Connect

This patent describes a furnace having a burner means for providing hot products of combustion, and an air flow means for circulating conditioned air, a heat exchanger for transferring heat from products of combustion to conditioned air. The heat exchanger comprises first and second matched clamshell plates assembled together. The plates connected at their respective edges by a sealing means for providing a seal thereat, each the plate having an internal surface defining a depression. The depressions together defining a serpentine passageway, an entrance and exhaust ported formed in the passageway. The surfaces including elongated ribs for obstructing fluid flow adjacent the exhaust portal and for directing fluid flow to under-utilized portions in the passageway.

Tomlinson, R.S.

1991-01-08

30

Characterization of the ASDEX scrape-off-layer density profile during neutral beam heating  

NASA Astrophysics Data System (ADS)

The scrape-off layer electron profiles in the outer midplane during phases of high neutral injection power are quantified. The diverted discharges are sustained by gas puffing. Empirical scaling conditions are introduced. The stainless steel walls of the vacuum vessel were neither carbonized nor gettered for these discharges. The importance of recycling for the scrape-off layer properties is emphasized.

McCormick, G. K.; Pietrzyk, Z. A.

1988-11-01

31

Heat exchanger-accumulator  

DOEpatents

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.

Ecker, Amir L. (Dallas, TX)

1980-01-01

32

Heat exchange fluids and techniques  

Microsoft Academic Search

The book presents detailed technical information based on United States patents issued since January, 1975 on heat exchange fluids and techniques, emphasizing the potential energy savings attainable. Attention is given to general heat exchanger construction and design, including tubular and other constructions, particulate exchange mediums and surface treatments, and to the compositions of heat transfer fluids. Refrigerant processes and fluids

M. W. Ranney

1979-01-01

33

Lightweight long life heat exchanger  

NASA Technical Reports Server (NTRS)

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.

Moore, E. K.

1976-01-01

34

Direct contact heat exchangers for space  

Microsoft Academic Search

Direct contact heat exchanger concepts have been investigated for use in space, including droplet vortex heat exchangers, coflowing droplet heat exchangers, electrostatically driven heat exchangers, and belt and disk heat exchangers. These concepts are characterized by a low heat exchanger mass per unit of heat transferred, low pressure losses, high reliability, and compactness in design. Operation in zero-G poses unique

R. T. Taussig; W. J. Thayer; V. C. H. Lo; K. M. Sakins; A. P. Bruckner

1985-01-01

35

Liquid/liquid heat exchanger  

NASA Technical Reports Server (NTRS)

Conceptual design for heat exchanger, utilizing two immiscible liquids with dissimilar specific gravities in direct contact, is more efficient mechanism of heat transfer than conventional heat exchangers with walls or membranes. Concept could be adapted for collection of heat from solar or geothermal sources.

Miller, C. G.

1980-01-01

36

Fault-Tolerant Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

Izenson, Michael G.; Crowley, Christopher J.

2005-01-01

37

High heat flux single phase heat exchanger  

NASA Technical Reports Server (NTRS)

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.

Valenzuela, Javier A.; Izenson, Michael G.

1990-01-01

38

Hybrid Heat Exchangers  

NASA Technical Reports Server (NTRS)

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.

Tu, Jianping Gene; Shih, Wei

2010-01-01

39

Oscillating-Coolant Heat Exchanger  

NASA Technical Reports Server (NTRS)

Devices useful in situations in which heat pipes inadequate. Conceptual oscillating-coolant heat exchanger (OCHEX) transports heat from its hotter portions to cooler portions. Heat transported by oscillation of single-phase fluid, called primary coolant, in coolant passages. No time-averaged flow in tubes, so either heat removed from end reservoirs on every cycle or heat removed indirectly by cooling sides of channels with another coolant. Devices include leading-edge cooling devices in hypersonic aircraft and "frost-free" heat exchangers. Also used in any situation in which heat pipe used and in other situations in which heat pipes not usable.

Scotti, Stephen J.; Blosser, Max L.; Camarda, Charles J.

1992-01-01

40

Corrosion of furnace heat exchangers  

Microsoft Academic Search

Systematic investigations and field data indicate that corrosion of furnace heat exchangers is affected primarily by condensation tendencies caused by installation, design, and operating conditions and aggravated by the presence of contaminants, reports the Canadian Gas Research Institute. Designing for maximum heat-transfer efficiency can cause excessive chilling in some areas of the heat exchanger, resulting in condensation of combustion products

S. W. Khoo; F. D. Williamson

1976-01-01

41

TWISTED TUBE HEAT EXCHANGER TECHNOLOGY  

Microsoft Academic Search

Over 85% of all new heat exchanger applications in oil refining, chemical, petro-chemical, and power generation are accommodated through the use of conventional shell and tube type heat exchangers. The fundamental basis for this statistic is shell and tube technology is a cost effective, proven solution for a wide variety of heat transfer requirements. However, there are limitations associated with

R. Donald Morgan

42

CONJUGATE HEAT TRANSFER IN PLATE HEAT EXCHANGERS  

Microsoft Academic Search

In a real plate heat exchanger (PHX), heat transfer from the hot to the cold fluid is a conjugate problem, in which longitudinal heat conduction (LHC) along the walls plays some role. Large-scale LHC is always detrimental to the exchanger's effectiveness. On the contrary, if significant non-uniformities exist in the distribution of either convective heat transfer coefficient, small-scale LHC may

Michele Ciofalo

2004-01-01

43

Heat pipes in modern heat exchangers  

Microsoft Academic Search

Heat pipes are very flexible systems with regard to effective thermal control. They can easily be implemented as heat exchangers inside sorption and vapour-compression heat pumps, refrigerators and other types of heat transfer devices. Their heat transfer coefficient in the evaporator and condenser zones is 103–105 W\\/m2K, heat pipe thermal resistance is 0.01–0.03 K\\/W, therefore leading to smaller area and

Leonard L. Vasiliev

2005-01-01

44

Direct-Contact Heat Exchanger.  

National Technical Information Service (NTIS)

The working principle of direct contact heat exchanger, where heat transfer takes place between two immiscible fluids coming into direct contact, is described. Typical direct contact devices are outlined. A better understanding of the principles involved ...

A. Bricard

1991-01-01

45

Heat exchanger leakage problem location  

NASA Astrophysics Data System (ADS)

Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

Hej?ík, Ji?í; Jícha, Miroslav

2012-04-01

46

The microtube strip heat exchanger  

SciTech Connect

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

Doty, F.D.; Hosford, G.; Spitzmesser, J.B. (Doty Scientific, Inc., Columbia, SC (United States)); Jones, J.D. (Simon Fraser Univ., Burnaby, British Columbia (Canada). School of Engineering Science)

1991-01-01

47

High Temperature Heat Exchanger Project  

SciTech Connect

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

Anthony E. Hechanova, Ph.D.

2008-09-30

48

Modular heat exchanger  

DOEpatents

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.

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

1981-03-03

49

Direct-contact heat exchanger  

NASA Astrophysics Data System (ADS)

The working principle of direct contact heat exchanger, where heat transfer takes place between two immiscible fluids coming into direct contact, is described. Typical direct contact devices are outlined. A better understanding of the principles involved and the development of computational models for multiphase subsytems are concluded as stimulus for direct contact heat and mass transfer applications.

Bricard, A.

50

Direct-contact heat exchanger  

Microsoft Academic Search

The working principle of direct contact heat exchanger, where heat transfer takes place between two immiscible fluids coming into direct contact, is described. Typical direct contact devices are outlined. A better understanding of the principles involved and the development of computational models for multiphase subsytems are concluded as stimulus for direct contact heat and mass transfer applications.

A. Bricard

1991-01-01

51

Heat exchanger using graphite foam  

DOEpatents

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.

Campagna, Michael Joseph; Callas, James John

2012-09-25

52

Heat exchanger with ceramic elements  

DOEpatents

An annular heat exchanger assembly includes a plurality of low thermal growth ceramic heat exchange members with inlet and exit flow ports on distinct faces. A mounting member locates each ceramic member in a near-annular array and seals the flow ports on the distinct faces into the separate flow paths of the heat exchanger. The mounting member adjusts for the temperature gradient in the assembly and the different coefficients of thermal expansion of the members of the assembly during all operating temperatures.

Corey, John A. (North Troy, NY) [North Troy, NY

1986-01-01

53

Energy conservation utilizing ceramic heat exchangers  

Microsoft Academic Search

Ceramic heat exchangers are cost effective for reclaiming waste heat at temperatures in excess of 850°C. This paper reviews the types of ceramic materials currently available and correlates their properties with engineering design requirements and heat exchanger performance. Ceramic heat exchangers are being considered to preheat air for externally fired gas turbines. The outer surface of the heat exchanger can

R. A. Penty; J. W. Bjerklie

1980-01-01

54

Acceptance criteria for heat exchanger head staybolts  

Microsoft Academic Search

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

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

1991-01-01

55

Enhancement of heat transfer in waste-heat heat exchangers  

SciTech Connect

The Fluidfire shallow fluidized bed heat transfer facility was modified during this program to give increased air flow capacity and to allow testing with different distributor plates and with two-stage heat exchangers. Tests were conducted using this heat transfer facility to investigate the effect of reduced distributor plate pressure loss and amount and type of bed material on the heat transfer performance of a single-stage fluidized bed heat exchanger. Elutriation from the bed was measured for different bed materials and distributor plates; alternate heat exchanger surfaces having different fin spacings were also tested. Two types of two-stage fluidized bed heat exchangers were tested: one having a baffle (having almost no pressure loss) located between the stages and which allowed bed material to recirculate between upper and lower beds; the second having two distributor plates in series with no recirculation of the bed material. The results obtained in the experimental program were used in conceptual design studies of multi-stage fluidized bed heat exchangers for waste heat recovery from diesel engine exhaust gases. Information was obtained from the literature and from diesel engine manufacturers to determine allowable diesel engine operating back pressures. The costs were estimated for two- and three-stage designs and were compared with costs obtained previously for single-stage fluidized bed and conventional heat exchanger designs.

Not Available

1980-07-01

56

Ceramic heat exchanger  

DOEpatents

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.

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

1998-06-16

57

Ceramic heat exchanger  

DOEpatents

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.

LaHaye, Paul G. (Kennebunk, ME); Rahman, Faress H. (Portland, ME); Lebeau, Thomas P. E. (Portland, ME); Severin, Barbara K. (Biddeford, ME)

1998-01-01

58

Lightweight long life heat exchanger  

NASA Technical Reports Server (NTRS)

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.

Moore, E. K.

1975-01-01

59

Heat exchanger with oscillating flow  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

60

Heat exchanger with oscillating flow  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

61

Experimental methods to determine heat exchanger performances  

NASA Astrophysics Data System (ADS)

A heat exchanger test platform and experiments carried out thereon are described. The following studies are summarized: determination of the performances of a welded plate evaporator for a refrigeration unit; determination of the performance of a compact heat exchanger for gas turbine heat recovery; and determination of the performance of a fin and tube heat exchanger on diesel engine exhaust gases.

Marvillet, C.; Vidil, R.

62

Heat exchangers. [For solar water heaters  

Microsoft Academic Search

The types and configurations of heat exchangers used in liquid-type, solar-assisted domestic hot water heating systems are discussed. Failures in heat exchangers are attributed to corrosion, thermal stresses, mechanical stresses, or pressure drop in the potable water. The types and designs of the heat exchangers discussed include tube in shell, double tube in shell, tube on shell, tube on shell

Morales

2009-01-01

63

Pressurized bellows flat contact heat exchanger interface  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

64

Improved Ceramic for Heat Exchangers  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

65

Improved ceramic heat exchanger material  

Microsoft Academic Search

Various ceramic materials in the form of small, monolithic bars were screened as candidate materials in heat exchanger structures for automotive gas turbine engines. The material finally selected consists of 60 w\\/o* petalite (LAS) and 40 w\\/o of a recrystallizable glass which converts during thermal processing to cordierite (MAS). This new material, GE-3200, was fabricated by Coors Porcelain Company into

Rauch; H. W. Sr

1977-01-01

66

Cryogenic Heat Exchanger with Turbulent Flows  

ERIC Educational Resources Information Center

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…

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

2012-01-01

67

SAFE gas turbine cycle primary heat exchangers  

NASA Astrophysics Data System (ADS)

Los Alamos National Laboratory and Marshall Space Flight Center are jointly developing two modular heat pipe heat exchangers, collectively named FIGMENT (Fission Inert Gas Metal Exchanger for Non-nuclear Testing). The FIGMENT heat exchangers are designed to transfer power from the SAFE nuclear reactor cores to gas turbine energy converters. A stainless steel prototype heat exchanger will be built during 2002 in preparation for the construction of a larger refractory metal version. Two promising FIGMENT stainless steel heat exchanger concepts are reviewed here. .

Reid, Robert S.; Kapernick, Richard J.

2002-01-01

68

Manufacture of aluminum plate heat exchangers  

Microsoft Academic Search

Plate heat exchangers (Fig. 1) are widely used as regenerators for gas turbine plants, heat exchangers in plants for the fractionating of air, etc. They have a number of advantages over other types of this equipment: high efficiency, low heat capacity, compactness of the surface, relatively small overall dimensions, etc. [1-3]. The use of plate heat exhcangers in the chemical,

N. S. Baranov; G. A. Stepanov

1966-01-01

69

Heat exchanger for solar water heaters  

NASA Technical Reports Server (NTRS)

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

Cash, M.; Krupnick, A. C.

1977-01-01

70

Biofouling Countermeasure Evaluations for OTEC Heat Exchangers.  

National Technical Information Service (NTIS)

Several promising countermeasure methods for maintaining heat transfer efficiency in OTEC heat exchangers have been evaluated by the LaQue Center for Corrosion Technology, Inc., under contract to Argonne National Laboratory (ANL). Heat transfer monitors d...

R. O. Lewis

1981-01-01

71

Performance of Rotary Heat and Mass Exchangers  

Microsoft Academic Search

Rotary regenerative heat and mass exchangers (enthalpy exchangers) can reduce air-conditioning costs in ventilated buildings by recovering energy from the exhaust air and transferring it to the supply air stream. In this study the adsorption isotherms of a desiccant used in a commercially available heat and mass exchanger are measured. The isotherms and other property data are incorporated into the

G. Stiesch; S. A. Klein; J. W. Mitchell

1995-01-01

72

Testing and analysis of immersed heat exchangers  

SciTech Connect

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.

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

1986-08-01

73

Improved ceramic heat exchange material  

NASA Technical Reports Server (NTRS)

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.

Mccollister, H. L.

1977-01-01

74

Direct contact heat exchangers for space  

NASA Astrophysics Data System (ADS)

Direct contact heat exchanger concepts have been investigated for use in space, including droplet vortex heat exchangers, coflowing droplet heat exchangers, electrostatically driven heat exchangers, and belt and disk heat exchangers. These concepts are characterized by a low heat exchanger mass per unit of heat transferred, low pressure losses, high reliability, and compactness in design. Operation in zero-G poses unique problems for those direct contact heat exchangers which require separation of two fluid media after heat transfer is completed. Other problems include maintenance of good heat transfer coefficients in the absence of buoyant forces, exposure of heat transfer media to vacuum conditions for certain applications, and materials compatibility. A preliminary systems analysis indicates the potential for substantial weight reductions in turbine Brayton cycle space power systems for output powers above several MW(e). Based on the status of current technology and the results of this analysis, recommendations are made for the most attractive applications and the R&D required to ready a direct contact heat exchanger for use in space.

Taussig, R. T.; Thayer, W. J.; Lo, V. C. H.; Sakins, K. M.; Bruckner, A. P.

1985-06-01

75

“Zero Fouling” Self-Cleaning Heat Exchanger  

Microsoft Academic Search

Conventional shell and tube heat exchangers sometimes have to use two severely fouling process streams, one in the tubes and one in the shell. This paper presents the design of a self-cleaning heat exchanger that applies the self-cleaning mechanism in the tubes of two parallel bundles handling the fouling process streams. For the transfer of heat between both bundles, a

D. G. Klaren; E. F. De Boer; D. W. Sullivan

2007-01-01

76

Extruded Microchannel-Structured Heat Exchangers  

Microsoft Academic Search

In the search for more compact air\\/liquid heat exchangers, one possibility is to increase the heat transfer coefficient and surface area by a decrease of the size of the fluid channels. A practical example could be seen in the air\\/water cross-flow heat exchangers used in cars. For such exchangers, minimization of the total volume leads to a very thin structure,

Jean-Antoine Gruss; Christophe Bouzon; Bernard Thonon

2005-01-01

77

Process for repairing a cryogenic heat exchanger  

SciTech Connect

The patent describes a method for repairing leakage-causing cracks and fissures in a cryogenic heat exchanger. It comprises: reducing the interior pressure of the heat exchanger to a level which does not exceed the external pressure upon the hear exchanger while maintaining the temperature of the heat exchanger at a low level relative to the ambient external temperature; applying a curable liquid filler composition to the surface of the heat exchanger proximal the leakage site for seepage into the cracks and fissures located at the leakage. The composition upon a relatively short period of cure at low temperature forming a solid material which fills the cracks and fissures; curing the filler composition; and, applying a sealant composition to the surface of the heat exchanger at the filled leakage site. The sealant composition having long-term sealing performance under cyrogenic conditions.

Yan, T.Y.

1989-08-22

78

Analysis of Compact Heat Exchanger Performance.  

National Technical Information Service (NTIS)

Many cryogenic heat exchangers employ high-conductance metallic screens or perforated plates separated by insulating spacers normal to the fluid flow direction. The former insures a high rate of heat transfer between the fluid streams while the latter red...

S. Sarangi J. A. Barclay

1984-01-01

79

Heat Exchanger Design for Desalination Plants.  

National Technical Information Service (NTIS)

The Office of Saline Water (OSW) accomplished a very large amount of significant work related to the design and performance of large heat exchanger bundles and enhanced heat transfer surfaces. This work was undertaken to provide basic technical and econom...

1979-01-01

80

High temperature heat exchange: Nuclear process heat applications  

NASA Astrophysics Data System (ADS)

The unique element of the HTGR system is the high temperature operation and the need for heat exchanger equipment to transfer nuclear heat from the reactor to the process application. This paper discusses the potential applications of the HTGR in both synthetic fuel production and nuclear steel making and presents the design considerations for the high temperature heat exchanger equipment.

Vrable, D. L.

1980-09-01

81

Multiple heat exchange in a model furnace with direct heating  

Microsoft Academic Search

in this paper results are given for studies of multiple heat exchange during the combustion of natural gas in a standard model furnace in order to determine the convection component fraction in the multiple heat exchange. Besides the measurements taken during the study of the convection heat emission, the natural gas eonsumptiou, its pressure, and temperature were also measured in

V. I. Lebedev; V. A. Sokolov

1980-01-01

82

Probe Measures Fouling As In Heat Exchangers  

NASA Technical Reports Server (NTRS)

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.

Marner, Wilbur J.; Macdavid, Kenton S.

1990-01-01

83

Local effects of longitudinal heat conduction in plate heat exchangers  

Microsoft Academic Search

In a plate heat exchanger, heat transfer from the hot to the cold fluid is a multi-dimensional conjugate problem, in which longitudinal heat conduction (LHC) along the dividing walls often plays some role and can not be neglected. Large-scale, or end-to-end, LHC is always detrimental to the exchanger’s effectiveness. On the contrary, if significant non-uniformities exist in the distribution of

Michele Ciofalo

2007-01-01

84

Stability of a direct contact heat exchanger  

Microsoft Academic Search

Direct contact heat exchangers have received considerable attention in recent years for application in alternate energy systems. One version of a direct contact heat exchanger is a spray column. This device brings into contact a higher temperature fluid with cooler immiscible liquid. Fluctuations in the input characteristics of either fluid can upset the operation of the column and affect the

Golafshani

1984-01-01

85

Fuel delivery system including heat exchanger means  

NASA Technical Reports Server (NTRS)

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.

Coffinberry, G. A. (inventor)

1978-01-01

86

Improved ceramic heat exchanger materials  

NASA Technical Reports Server (NTRS)

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.

Rauch, H. W.

1980-01-01

87

Direct contact heat exchanger with phase change of working fluid  

Microsoft Academic Search

A direct contact thermal storage heat exchanger is disclosed which utilizes the liquid-vapor phase change of a working fluid within the heat exchanger, and energy generation systems incorporating the heat exchanger. The heat exchanger is particularly useful in combination with a solar energy receiver. The heat exchanger includes an insulated pressure vessel packed with pebbles or spheres. Working fluid in

Pierce

1980-01-01

88

Heat exchanger device and method for heat removal or transfer  

DOEpatents

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.

Koplow, Jeffrey P

2013-12-10

89

Heat exchanger device and method for heat removal or transfer  

DOEpatents

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.

Koplow, Jeffrey P. (San Ramon, CA)

2012-07-24

90

Heat flow through extended surface heat exchangers  

SciTech Connect

Contents of this book include the one-dimensional analysis of fin assembly heat transfer, the two dimensional analysis of fin assembly heat transfer, the analysis of fin radiation and the applicability of the perfect contact assumption.

Manzoor, M.

1984-01-01

91

Brayton-cycle heat exchanger technology program  

Microsoft Academic Search

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

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

1976-01-01

92

Design study of plastic film heat exchanger  

NASA Astrophysics Data System (ADS)

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.

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

1986-02-01

93

Heat Exchanger Support Bracket Design Calculations  

SciTech Connect

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.

Rucinski, Russ; /Fermilab

1995-01-12

94

Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers.  

National Technical Information Service (NTIS)

A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was si...

L. D. Garrett H. Duchacek M. Morselli F. M. Laing N. K. Huyler

1977-01-01

95

Heat exchanger with transpired, highly porous fins  

DOEpatents

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.

Kutscher, Charles F. (Golden, CO); Gawlik, Keith (Boulder, CO)

2002-01-01

96

Airway heat and gas exchange  

Microsoft Academic Search

The usual approach to analysis of pulmonary gas exchange deals with the airways as a dead space that does not participate in gas exchange and acts simply as a conduit for the passage of air between the outside environment and the alveoli. In reality, however, inspired air undergoes some change during its trans-airway passage. The relatively cool and dry air

M P Hlastala

1992-01-01

97

Physical Aspects of Scraped Heat Exchanger Crystallizers: An Application in Eutectic Freeze Crystallization  

Microsoft Academic Search

One of the most important natural resources is fresh water. An unfortunate issue is however, the low availability and high demand of fresh water world-wide. From the total resources industry consumes about 20 % (1200 km3 yearly) [UN, 2007]. Industrial aqueous waste streams are therefore widely occurring, and their reuse becomes obligatory. For the recovery of water from dilute solutions

M. Rodriguez Pascual

2009-01-01

98

Acceptance criteria for heat exchanger head staybolts  

SciTech Connect

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

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

1991-01-01

99

Acceptance criteria for heat exchanger head staybolts  

SciTech Connect

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

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

1991-12-31

100

Fatigue Testing of Heat-Exchanger Tubes  

NASA Technical Reports Server (NTRS)

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

Ackerman, P.

1984-01-01

101

High Efficiency Flat Panel Microchannel Heat Exchanger.  

National Technical Information Service (NTIS)

An apparatus providing high efficiency heat exchange between two fluids is disclosed. The apparatus most commonly comprises a flat panel with microchannels directing the flow of the two fluids, specifically: with a small hydraulic diameter in order to inc...

K. W. Kelly A. McCandless

2005-01-01

102

Biofouling countermeasure evaluations for OTEC heat exchangers  

SciTech Connect

Several promising countermeasure methods for maintaining heat transfer efficiency in OTEC heat exchangers have been evaluated by the LaQue Center for Corrosion Technology, Inc., under contract to Argonne National Laboratory (ANL). Heat transfer monitors designed at Carnegie-Mellon and modified by ANL were utilized to evaluate the effectiveness of several countermeasure methods for candidate OTEC heat exchanger tubing. Countermeasure methods evaluated included the use of abrasive slurries, Amertap sponge rubber balls (alone and in combination with continuous and intermittent chlorination), M.A.N. brush, surfactant/dispersant organic chemical cleaning and continuous and intermittent chlorination.

Lewis, R.O.

1981-06-01

103

FLOW-INDUCED NOISE IN HEAT EXCHANGERS  

Microsoft Academic Search

Noise or vibration problems in heat exchangers may be encountered in ; those instances when a natural acoustic frequency of the exchanger in the ; direction normal to the flow direction and tube length is close to the frequency ; determined by the Strouhal number. In this case coupling can occur giving ; oscillation of a large amplitude which results

1959-01-01

104

Modelling and simulation of a heat exchanger  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

105

Stirling Engine With Radial Flow Heat Exchangers  

NASA Technical Reports Server (NTRS)

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

Vitale, N.; Yarr, George

1993-01-01

106

Design and fabrication of a cross flow micro heat exchanger  

Microsoft Academic Search

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

Chad Harris; Mircea Despa; Kevin Kelly

2000-01-01

107

Dehydrogenation process utilizing indirect heat exchange and direct combustion heating  

Microsoft Academic Search

A multiple reaction zone process for dehydrogenating light hydrocarbons, preferably propane, is disclosed. The feed stream and intermediate streams are first heated by indirect heat exchange to temperatures slightly below the desired inlet temperature of the dehydrogenation catalyst beds. These streams are then transported to a location which is in close proximity of the dehydrogenation catalyst bed and further heated

Vora

1983-01-01

108

Ceramic heat exchangers: manufacturing techniques and performance  

SciTech Connect

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 have been 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.

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

1981-01-01

109

Full wave simulations of fast wave heating losses in the scrape-off layer of NSTX and NSTX-U  

NASA Astrophysics Data System (ADS)

Full wave simulations of fusion plasmas show a direct correlation between the location of the fast-wave cut-off, radiofrequency (RF) field amplitude in the scrape-off layer (SOL) and the RF power losses in the SOL observed in the National Spherical Torus eXperiment (NSTX). In particular, the RF power losses in the SOL increase significantly when the launched waves transition from evanescent to propagating in that region. Subsequently, a large amplitude electric field occurs in the SOL, driving RF power losses when a proxy collisional loss term is added. A 3D reconstruction of absorbed power in the SOL is presented showing agreement with the RF experiments in NSTX. Loss predictions for the future experiment NSTX-Upgrade (NSTX-U) are also obtained and discussed.

Bertelli, N.; Jaeger, E. F.; Hosea, J. C.; Phillips, C. K.; Berry, L.; Gerhardt, S. P.; Green, D.; LeBlanc, B.; Perkins, R. J.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, J. R.

2014-08-01

110

Heat transfer from oriented heat exchange areas  

NASA Astrophysics Data System (ADS)

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

Vantuch, Martin; Huzvar, Jozef; Kapjor, Andrej

2014-03-01

111

Condensing, Two-Phase, Contact Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

112

High-temperature ceramic heat exchanger  

Microsoft Academic Search

A ceramic heat exchanger for operation with a small, closed Brayton cycle engine was developed which operates with 3000 F combustion products on one side and heats high pressure Argon gas, which subsequently is delivered to the turbine, to 1800 F. A materials test program encompassing strength tests, cyclic fatigue tests, and stress rupture tests from room temperature to a

M. Coombs; D. Kotchick; H. Warren

1979-01-01

113

Advanced silicon carbide heat exchange materials  

Microsoft Academic Search

The continuing energy shortage has created an interest in developing heat exchangers to recover energy from hot flue gases. The hostile thermal and chemical environment associated with these heated gases is beyond the useful range of today's alloys, thus encouraging research with materials that retain desired qualities under the most adverse conditions. Silicon carbide (SiC) has been considered a candidate

M. E. Rorabaugh; D. L. Mann

1978-01-01

114

Acceptance criteria for heat exchanger head staybolts.  

National Technical Information Service (NTIS)

Each of the six primary coolant loop systems of the Savannah River Site production reactors contains two parallel single-pass heat exchangers to transfer heat from the primary coolant (D(sub 2)O) to the secondary cooling water (H(sub 2)O). The configurati...

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

1991-01-01

115

High effectiveness contour matching contact heat exchanger  

NASA Astrophysics Data System (ADS)

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.

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

1988-08-01

116

Heat Exchanger With Internal Pin Elements  

DOEpatents

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.

Gerstmann, Joseph (Framingham, MA); Hannon, Charles L. (Arlington, MA)

2004-01-13

117

Vibration damping in multispan heat exchanger tubes  

SciTech Connect

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

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

1998-08-01

118

Equal volume, contraflow heat exchanger  

Microsoft Academic Search

An apparatus is described for use in combination with a water heating system wherein the system includes (1) a cold water feed; (2) a water heater having an inlet connected to the cold water feed and a hot water outlet, and (3) a facility connected to the cold water feed and the hot water outlet and having a waste pipe

C. F. Vasile; S. F. Vasile

1986-01-01

119

Condensation Behavior in a Microchannel Heat Exchanger  

NASA Astrophysics Data System (ADS)

A small and high performance heat exchanger for small size energy equipments such as fuel cells and CO2 heat pumps is required in these days. In author's previous studies, the heat exchanger consisted of microchannels stacked in layers has been developed. It has resistance to pressure of larger than 15 MPa since it is manufactured by diffusion bond technique. Thus this device can be applied for high flow rate and pressure fluctuation conditions as boiling and condensation. The objectives of the present study are to clarify the heat transfer performance of the prototype heat exchanger and to investigate the thermal hydraulic behavior in the microchannel for design optimization of the device. As the results, it is clarified that the present device attained high heat transfer as 7 kW at the steam condensation, despite its weight of only 230 g. Furthermore, steam condensation behavior in a glass capillary tube, as a simulated microchannel, in a cooling water pool was observed with various inlet pressure and temperature of surrounding water. Relation between steam-water two-phase flow structure and the overall heat transfer coefficient is discussed.

Kaneko, Akiko; Takeuchi, Genki; Abe, Yutaka; Suzuki, Yutaka

120

Heat exchangers for vuilleumier cycle heat pumps  

SciTech Connect

The invention relates to a heat pump device comprising a pair of chambers and a plurality of elements extending within both chambers. A working fluid is disposed in both of the chambers and a displacer means is positioned in each of the chambers such that they are movable within their respective chambers. Both of the displacer means have a wall that divides their respective chambers into two zones, a regenerator material that is housed therein, a plurality of elements extending outwardly from and in proximity to the elements extending within the respective chamber, and at least one passageway communicating through each displacer means and through the respective regenerator material for the working fluid to flow therethrough between the zones. There is a drive means for reciprocably moving both of the displacer means in their respective chamber between the respective zones of the chamber. There is also means for maintaining one of the zones of each of the chambers at a cool temperature and means for maintaining the other of the zones either at a relatively hot temperature or at a cold temperature.

Leach, J.W.

1984-02-07

121

Carbon nanotube heat-exchange systems  

DOEpatents

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).

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

2008-11-11

122

Fouling of heat exchanger surfaces: General principles  

NASA Astrophysics Data System (ADS)

This Data Item ESDU 86038 is an addition to the Heat Transfer Sub-series. The importance of various parameters that affect fouling are discussed. Appropriate methods for dealing with fouling in all stages from design through to operation of heat exchanger equipment are indicated. Methods of suppressing fouling by additives, or of cleaning equipment chemically or mechanically, are considered. A brief outline of the physical process of fouling including some mathematical models is given.

1986-12-01

123

Qualification of Aluminum for OTEC Heat Exchangers.  

National Technical Information Service (NTIS)

The basis for qualification of aluminum as a material for use as tubing in Ocean Thermal Energy Conversion heat exchangers is reviewed. Reference is made to compendia of data from tests of aluminum alloys in natural sea water and to applicable service rec...

F. L. LaQue

1979-01-01

124

Fretting Wear of Heat Exchanger Tubes.  

National Technical Information Service (NTIS)

The results of a series of measurements made on the fretting wear of heat exchanger tubes and support plates at room temperature in a nitrogen/air atmosphere are presented. The fretting wear is shown to be a function of the amplitude and frequency of tube...

R. D. Blevins

1978-01-01

125

Hybrid OTEC cycle avoids indirect heat exchangers  

Microsoft Academic Search

A hybrid OTEC cycle which uses air as a working fluid is presented. Indirect heat exchangers are avoided and the air is alternately warmed and cooled by direct contact with water to produce useful work from the expansion and contraction. Methods are described to decrease the buoyancy and size of equipment, such as by increasing the compression beyond that caused

C. E. Jahnig

1979-01-01

126

Modelling heat exchangers for thermoelectric generators  

Microsoft Academic Search

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

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

2001-01-01

127

Cleaning Agents for Reactor Heat Exchangers.  

National Technical Information Service (NTIS)

At SRP, oxalic acid is occasionally used to remove an oxide film from the shell side of reactor heat exchangers (HXs). The single-pass flow-through procedure utilizing 100 ppM oxalic acid removes the fouling layer at a rate proportional to the water tempe...

E. W. Wilde L. R. Berger J. A. Berger

1984-01-01

128

Superphenix 1 intermediate heat exchanger fabrication  

Microsoft Academic Search

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

H. Noel; F. Granito; P. Pouderoux

1985-01-01

129

SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS  

Microsoft Academic Search

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

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

2009-01-01

130

Heat Exchange in Air, Water, and Soil  

NSDL National Science Digital Library

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

Eichinger, John

2009-05-30

131

Acoustic resonance in heat exchanger tube banks  

Microsoft Academic Search

Fluid mechanics of acoustic resonance in heat exchanger tube bundles continues. Data and theory, development of models for the acoustics of tube bundles, and construction of a wind tunnel and tube array model were previously reviewed. In the present phase of the problem, both the wind tunnel model and the analytical model were exercised. Using the wind tunnel, the ability

R. D. Blevins

1984-01-01

132

Measurement of heat and moisture exchanger efficiency.  

PubMed

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. PMID:24047355

Chandler, M

2013-09-01

133

Effectiveness enchancement of heat exchanger by using nanofluids  

Microsoft Academic Search

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

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

2011-01-01

134

Performance of a MEMS Heat Exchanger for a Cryosurgical Probe  

Microsoft Academic Search

This paper presents the experimental test results for two 2 nd generation Micro-Electro- Mechanical Systems (MEMS) heat exchangers that are a composite of silicon plates with micro- machined flow passages interleaved with glass spacers. The MEMS heat exchangers were designed for use as the recuperative heat exchanger within a Joule-Thomson (JT) cycle used to energize a cryosurgical probe. The heat

M. J. White; W. Zhu; G. F. Nellis; S. A. Klein; Y. B. Gianchandani

135

Equal volume, contraflow heat exchanger  

SciTech Connect

An apparatus is described for use in combination with a water heating system wherein the system includes (1) a cold water feed; (2) a water heater having an inlet connected to the cold water feed and a hot water outlet, and (3) a facility connected to the cold water feed and the hot water outlet and having a waste pipe for carrying mixed hot and cold water. The facility has a means for mixing the cold and hot water and immediately providing the mixed water to the waste pipe; the apparatus comprising: (a) first means including a cylindrical member connected to the waste pipe for directing the flow of the mixed hot and cold water in the form of a film spiraling downward over the inner surface of the cylindrical member; and (b) second means connected in-line with the cold water feed prior to the cold water feed connections to the facility and prior to the cold water feed connections to the water heater for directing the flow of cold water flowing in the cold water feed.

Vasile, C.F.; Vasile, S.F.

1986-10-28

136

Heat Exchanger Design in Combined Cycle Engines  

NASA Astrophysics Data System (ADS)

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.

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

137

Brayton heat exchange unit development program  

NASA Technical Reports Server (NTRS)

A Brayton Heat Exchanger Unit (BHXU), consisting of a recuperator, a heat sink heat exchanger and a gas ducting system, was designed, fabricated, and tested. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement. Evaluation testing was conducted from which it is estimated that near-design performance can be expected with the use of He-Xe as the working fluid.

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

1971-01-01

138

Heat Transfer Characteristics of a Three-Phase Volume Boiling Direct Contact Heat Exchanger.  

National Technical Information Service (NTIS)

The advantages of direct contact heat transfer over heat transfer utilizing conventional metallic heat exchangers are listed. The performance characteristics of a three-phase direct contact heat exchanger in near counterflow operation were evaluated using...

C. K. Blair R. F. Boehm H. R. Jacobs

1976-01-01

139

Predicting particle deposition on HVAC heat exchangers  

NASA Astrophysics Data System (ADS)

Particles in indoor environments may deposit on the surfaces of heat exchangers that are used in heating, ventilation and air conditioning (HVAC) systems. Such deposits can lead to performance degradation and indoor air quality problems. We present a model of fin-and-tube heat-exchanger fouling that deterministically simulates particle impaction, gravitational settling, and Brownian diffusion and uses a Monte Carlo simulation to account for impaction due to air turbulence. The model predicts that <2% of submicron particles will deposit on heat exchangers with air flows and fin spacings that are typical of HVAC systems. For supermicron particles, deposition increases with particle size. The dominant deposition mechanism for 1-10 ?m particles is impaction on fin edges. Gravitational settling, impaction, and air turbulence contribute to deposition for particles larger than 10 ?m. Gravitational settling is the dominant deposition mechanism for lower air velocities, and impaction on refrigerant tubes is dominant for higher velocities. We measured deposition fractions for 1-16 ?m particles at three characteristic air velocities. On average, the measured results show more deposition than the model predicts for an air speed of 1.5 m s -1. The amount that the model underpredicts the measured data increases at higher velocities and especially for larger particles, although the model shows good qualitative agreement with the measured deposition fractions. Discontinuities in the heat-exchanger fins are hypothesized to be responsible for the increase in measured deposition. The model and experiments reported here are for isothermal conditions and do not address the potentially important effects of heat transfer and water phase change on deposition.

Siegel, Jeffrey A.; Nazaroff, William W.

140

Proceedings of the DOE/Advanced Heat Exchangers Program Review  

SciTech Connect

Semiannual review meetings of the USDOE's Advanced Heat Exchanger Program with the objective of reviewing ongoing and recently completed project activities. Personnel from industrial contractors and National Laboratories present technical aspects of their projects. The projects deal with high temperature heat exchangers for waste heat recuperation and process heat exchange and other areas such as materials performance and heat transfer enhancement. Topics presented are high pressure heat exchangers, ceramic heat exchangers, enhanced tubes, and materials studies to include silicon carbide whiskers and alumina. (GHH)

Not Available

1992-02-01

141

Triple loop heat exchanger for an absorption refrigeration system  

DOEpatents

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.

Reimann, Robert C. (Lafayette, NY)

1984-01-01

142

Study on heat transfer of heat exchangers in the Stirling engine - Performance of heat exchangers in the test Stirling engine  

NASA Astrophysics Data System (ADS)

The heat transfer performance of the actual heat exchangers obtained from the experimental results of the test Stirling engine is presented. The heater for the test engine has 120 heat transfer tubes that consist of a bare-tube part and a fin-tube part. These tubes are located around the combustion chamber and heated by the combustion gas. The cooler is the shell-and-tube-type heat exchanger and is chilled by water. It is shown that the experimental results of heat transfer performance of the heater and cooler of the test Stirling engine are in good agreement with the results calculated by the correlation proposed in our previous heat transfer study under the periodically reversing flow condition. Our correlation is thus confirmed to be applicable to the evaluation of the heat transfer coefficient and the thermal design of the heat exchangers in the Stirling engine.

Kanzaka, Mitsuo; Iwabuchi, Makio

1992-11-01

143

Preliminary SP-100/Stirling heat exchanger designs  

SciTech Connect

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.

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

1994-09-01

144

Preliminary SP-100/Stirling heat exchanger designs  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

145

1-MWe heat exchangers for OTEC. Final acceptance document  

SciTech Connect

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)

Snyder, J.E.

1980-06-19

146

Multi-Purpose Logistics Module (MPLM) Cargo Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

Zampiceni, John J.; Harper, Lon T.

2002-01-01

147

40 CFR 63.654 - Heat exchange systems.  

Code of Federal Regulations, 2013 CFR

...Emission Standards for Hazardous Air Pollutants From Petroleum Refineries § 63.654 Heat exchange systems. (a) Except...this section for some heat exchange systems at the petroleum refinery and comply with paragraph (c)(4)(ii) of this...

2013-07-01

148

Optimizing heat exchanger design for crude oil stabilization  

SciTech Connect

The plate heat exchanger is used for heat recovery applications involving cooling of glycol or fresh water with sea water aboard offshore platforms and other modular constructions. Plate heat exchangers are rugged enough for both offshore and onshore crude oil heat transfer operations. The economics of heat recovery are highly favorable in a crude oil treatment plant when using a plate heat exchanger. By modifying the equipment layout, the plant operator can achieve minimum operating and maintenance costs while achieving a high degree of heat recovery at quite reasonable capital costs with a plate heat exchanger.

Wagner, R.L.; Sjogren, S.

1985-02-01

149

A modular phase change heat exchanger for a solar oven  

Microsoft Academic Search

A modular energy storing heat exchanger designed to use pentaerythritol for thermal storage (solid-solid phase change at 182 C) is tested in an oven by circulating heat transfer oil which is electrically heated in a manner to simulate a concentrating solar collector. Three efficiencies for heating the system under controlled and measured power input are determined - the heat exchanger

D. L. Bushnell; M. Sohi

1992-01-01

150

Optimizing heat exchanger design for crude oil stabilization  

Microsoft Academic Search

The plate heat exchanger is used for heat recovery applications involving cooling of glycol or fresh water with sea water aboard offshore platforms and other modular constructions. Plate heat exchangers are rugged enough for both offshore and onshore crude oil heat transfer operations. The economics of heat recovery are highly favorable in a crude oil treatment plant when using a

R. L. Wagner; S. Sjogren

1985-01-01

151

Joule-Thomson heat exchanger and cryostat  

SciTech Connect

This patent describes a refrigerator of the type wherein a fluid is passed through the high pressure tube of a heat exchanger and then expanded through a Joule-Thomson orifice to produce refrigeration proximate the Joule-Thomson orifice. The improvement described here comprises: fibrous material disposed in the Joule-Thomson orifice which is deformed to fix the fibrous material in place, whereby the fibrous material and deformed orifice result in an orifice with large flow impedance.

Steyert, W.A.

1987-03-31

152

Geothermal direct contact heat exchange. Final report  

Microsoft Academic Search

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

Sims

1977-01-01

153

Robust controllers for a heat exchanger  

SciTech Connect

A robust controller with uncertainty estimation is proposed for temperature control of process fluid in a fluid-fluid heat exchanger. The controller comprises an approximate input-output linearizing feedback and an observer-based uncertainty estimator. The performance of the proposed controller is evaluated by simulation for both regulatory and servo problems. The simulation results show the effectiveness of the present controller and its robustness to modeling errors and disturbances.

Alvarez-Ramirez, J.; Cervantes, I.; Femat, R.

1997-02-01

154

Heat-Exchanger Computational Procedure For Temperature-Dependent Fouling  

NASA Technical Reports Server (NTRS)

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

Chiappetta, L.; Szetela, E.

1985-01-01

155

Silicon carbide for high-temperature heat exchangers  

Microsoft Academic Search

It is noted that ceramic heat exchangers are now being used industrially in low-pressure applications, such as recuperators and air preheaters, and that serious consideration is being given to using ceramic materials for high-pressure heat exchangers. The principal advantage of using ceramic heat exchangers in the candidate applications is the potential for higher temperature service or increased life over that

R. A. Penty; J. W. Bjerklie

1982-01-01

156

OXIDE DISPERSION-STRENGTHENED HEAT EXCHANGER TUBING  

SciTech Connect

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 anticipated to produce innovative developments that will allow the reliable use of ODS alloys for heat exchanger tubing, as well as a variety of applications previously not possible with metallic materials.

Harper, Mark A.

2001-11-06

157

Graphite Foam Heat Exchangers for Thermal Management  

SciTech Connect

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

Klett, J.W.

2004-06-07

158

A Numerical Study on Flow and Heat Transfer Analysis of Various Heat Exchangers  

Microsoft Academic Search

This paper describes numerical methodologies of the flow and heat transfer analysis in heat exchangers of various types. Heat\\u000a exchangers considered in the present study include a louver fin radiator for a vehicle, a shell and tube heat exchanger for\\u000a HVAC and plate heat exchangers with patterns of herringbone and of dimple used in waste heat recovery. For the analysis

Myungsung Lee; Chan-Shik Won; Nahmkeon Hur

159

Advances in liquid fluidized-bed heat exchanger development  

Microsoft Academic Search

The paper reports the first heat transfer results from a horizontal liquid fluidized-bed heat exchanger. Geothermal water from Raft River Geothermal Wells provided the heat source. Treated water was the secondary fluid. Silica sand closely screened to 16 mesh was the bed material. The exchanger was 8 in. in diameter by 15 in. long. Heat transfer results are compared with

E. S. Grimmett; A. F. Fanous; C. A. Allen

1977-01-01

160

A heat exchanger computational procedure for temperature-dependent fouling  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

161

A heat exchanger computational procedure for temperature-dependent fouling  

NASA Astrophysics Data System (ADS)

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

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

1981-08-01

162

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

SciTech Connect

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.

Cole, R.A. [R.A. Cole and Associates, Champaign, IL (United States)

1996-12-01

163

Design and optimization of heat exchangers with helical baffles  

Microsoft Academic Search

The hydrodynamics and heat transfer characteristics of a heat exchanger with single-helical baffles are studied experimentally as well as numerically. A heat exchanger with two-layer helical baffles is designed by using computational fluid dynamics (CFD) method. The comparisons of the performance of three heat exchangers with single-segment baffles, single-helical baffles and two-layer helical baffles, respectively, are presented in the paper.

Yong-Gang Lei; Ya-Ling He; Pan Chu; Rui Li

2008-01-01

164

Microbial fouling control in heat exchangers  

SciTech Connect

Biofilm formation in turbulent flow has been studied a great deal during the last 15 years. Such studies have provided the basis for further experiments designed to test the efficacy of industrial antimicrobials against biofilms in laboratory models and in actual real-world industrial water-treatment programs. Biofilm microbiology is relevant from the industrial perspective because adherent populations of microorganisms often cause an economic impact on industrial processes. For example, it is the adherent population of microorganisms in cooling-water systems that can eventually contribute to significant heat transfer and fluid frictional resistances. The microbiology of biofilms in heat exchangers can be related to the performance of industrial antimicrobials. The development of fouling biofilms and methods to quantitatively observe the effect of biofouling control agents are discussed in this paper.

McCoy, W.F.

1991-11-01

165

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

Microsoft Academic Search

A recent innovation in the solar industry is the use of thermosyphon heat exchangers. Determining the performance of these systems requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. This study demonstrates that several thermosyphon heat exchanger designs operate in the laminar mixed convection regime. Empirical heat transfer and pressure drop correlations are obtained

Scott David Dahl

1998-01-01

166

Comparison of natural convection heat exchangers for solar water heating systems  

Microsoft Academic Search

Thermosyphon heat exchangers are used in indirect solar water heating systems to avoid using a pump to circulate water from the storage tank to the heat exchanger. In this study, the authors consider the effect of heat exchanger design on system performance. They also compare performance of a system with thermosyphon flow to the same system with a 40W pump

J. Davidson; W. Liu

1998-01-01

167

Aerodynamics of heat exchangers for high-altitude aircraft  

NASA Technical Reports Server (NTRS)

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

Drela, Mark

1996-01-01

168

Self-defrosting recuperative air-to-air heat exchanger  

Microsoft Academic Search

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,

Drake; Richard L

1993-01-01

169

Diffusion-Welded Microchannel Heat Exchanger for Industrial Processes  

SciTech Connect

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.

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

2013-03-01

170

Performance of a compact, spiral coil heat exchanger  

Microsoft Academic Search

A spiral coil heat exchanger consists of a number of horizontal layers of spirally wound, finned tubes connected to vertical manifolds at the inner and outermost turns of each coil. This design has advantages in heat recovery and air-conditioning applications. Two theoretical models to predict the performance of this compact heat exchanger are presented based upon unmixed and mixed air-flow

J. C. Ho; N. E. Wijeysundera; S. Rajasekar; T. T. Chandratilleke

1995-01-01

171

Heat exchanger development for Ocean Thermal Energy Conversion  

Microsoft Academic Search

Heat exchangers comprise one of the largest cost drivers for Ocean Thermal Energy Conversion (OTEC) systems. Reductions in fabrication costs and improvements in performance are critical to successfully commercialize sustainable energy power plants using this low (?20°C) ?T resource. Heat exchanger (HX) units should maximize heat transfer per unit area (U value) while minimizing pressure losses, corrosion and cost. Current

Michael P. Eldred; Joseph C. Van Ryzin; Steven Rizea; In Chieh Chen; Robert Loudon; N. John Nagurny; Scott Maurer; Eugene Jansen; Andrew Plumb; Michael R. Eller; Victor R. R. Brown

2011-01-01

172

Characteristics Of Vertical Mantle Heat Exchangers For Solar Water Heaters  

Microsoft Academic Search

The flow structure in vertical mantle heat exchangers was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the mantle were measured using a particle Image Velocimetry (PIV) system. A CFD simulation model of vertical mantle heat exchangers was also developed for detailed evaluation of the heat flux distribution over the mantle surface.

L. J. Shah; G. L. Morrison; M. Behnia

1999-01-01

173

Increasing the efficiency of plate cross-flow heat exchangers  

Microsoft Academic Search

The possibility of increasing the thermal efficiency of plate cross-flow heat exchangers is examined. The design of the corrugated\\u000a heat-exchange plate design with different slope angles of the troughs relative to the direction of movement of the heat carriers\\u000a is analyzed.

Yu. B. Danilov; V. V. Drozdov

2010-01-01

174

Tubular heat exchanger design. Complement to the report MT 131  

Microsoft Academic Search

An interactive program for a minicomputer which calculates the thermal performance of shell and tube heat exchangers was written. The algorithms used and program data flow are described. Heat transfer and pressure drop correlations were assembled from the literature to aid in limiting the overdimensioning of heat exchangers. The user can solve design problems by updating geometrical input parametes until

F. Vandeberghe

1980-01-01

175

Heat exchanger fouling model and preventive maintenance scheduling tool  

Microsoft Academic Search

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

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

2007-01-01

176

Control Dewar Subcooler Heat Exchanger Calculations  

SciTech Connect

The calculations done to size the control dewar subcooler were done to obtain a sufficient subcooler size based on some conservative assumptions. The final subcooler design proposed in the design report will work even better because (1) It has more tubing length, and (2) will have already subcooled liquid at the inlet due to the transfer line design. The subcooler design described in the 'Design Report of the 2 Tesla Superconducting Solenoid for the Fermilab D0 Detector Upgrade' is the final design proposed. A short description of this design follows. The subcooler is constructed of 0.50-inch OD copper tubing with 1.0-inch diameter fins. It has ten and one half spirals at a 11.375-inch centerline diameter to provide 31 feet of tubing length. The liquid helium supply for the solenoid flows through the subcooler and then is expanded through a J-T valve. The subcooler spirals are immersed in the return two phase helium process stream. The return stream is directed over the finned tubing by an annulus created by a 10-inch pipe inside a 12-inch pipe. The transfer line from the refrigerator to the control dewar is constructed such that the liquid helium supply tube is in the refrigerator return stream, thereby subcooling the liquid up to the point where the u-tubes connect the transfer line to the control dewar. The subcooler within the control dewar will remove the heat picked up in the helium supply u-tube/bayonets. The attached subcooler/heat exchanger calculations were done neglecting any subcooling in the transfer line. All heat picked up in the transfer line from the refrigerator storage dewar to the control dewar is absorbed by the supply stream. The subcooler was sized such that the two phase supply fluid is subcooled at 1.7 atm pressure and when expanded through a JT valve to 1.45 atm pressure it is at a saturated liquid state. The calculations apply during steady state operation and at a flow rate of 16 g/s. The analysis of the heat exchanger was broken into two parts relating to the heat transfer mode taking place. The first part is considered the condensing part in which the helium supply stream is changed from two phase fluid to one phase liquid. The second part is the subcooling part where the liquid temperature is lowered, i.e.. subcooled. A summary of the calculations and results appears on the next page. The raw calculations follow the summary.

Rucinski, R.; /Fermilab

1993-10-04

177

Aluminum alloy fin material for heat exchanger  

SciTech Connect

Process for preparing an aluminum alloy fin material for heat exchangers is described comprising casting an alloy consisting essentially of 0.4 to 1.0% by weight of silicon, 0.45 to 3.0% by weight of iron, 0.01 to 0.3% by weight of zirconium, at least one member of the group consisting of 0.2 to 2.0% by weight of zinc, 0.01 to 0.1% by weight of tin and 0.01 to 0.1% by weight of indium, and the balance being of aluminum and unavoidable impurities; heat treating said cast alloy at 450 C to 600 C for a time sufficient to provide homogenization of said cast alloy; hot rolling and cold rolling said heat treated alloy with at least one intermediate annealing; and following the final intermediate annealing, cold rolling at a cold roll ratio of 15 to 60% to obtain a final sheet thickness.

Ishikawa, Kazunori; Hashiura, Mituo; Hasegawa, Yoshiharu.

1993-06-08

178

Simplified Analysis of Radiation Heat Exchange in Boiler Superheaters  

Microsoft Academic Search

This article describes the determination of the radiation heat transfer coefficient in radiant platen superheaters and on convective heating surfaces. A new simple formula for determination of the heat transfer coefficient is derived on the basis of a diffusivity model of radiation heat exchange. The radiation heat transfer coefficients are determined on the tube surface in a convective evaporator, in

Dawid Taler; Jan Taler

2009-01-01

179

Optimal allocation of a heat-exchanger inventory in heat driven refrigerators  

Microsoft Academic Search

This paper reports the thermodynamic optimization (or entropy generation minimization) of a heat-driven refrigeration plant, that is, a refrigerator without work input, which is driven by a heat source. The treatment accounts for the heat transfer irreversibilities of the three heat exchangers, and for the finiteness of the total heat-exchanger inventory. The operating conditions for maximum refrigeration rate are determined.

M. Sokolov

1995-01-01

180

Heat exchanger and water tank arrangement for passive cooling system  

DOEpatents

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

Gillett, James E. (Greensburg, PA) [Greensburg, PA; Johnson, F. Thomas (Baldwin Boro, PA) [Baldwin Boro, PA; Orr, Richard S. (Pittsburgh, PA) [Pittsburgh, PA; Schulz, Terry L. (Murrysville Boro, PA) [Murrysville Boro, PA

1993-01-01

181

Baghouse heat exchanger saves fuel, protects equipment, warms workers  

Microsoft Academic Search

A heat exchanger system designed to cool 900°F exhaust air from a rotary kiln has also proven that it can provide large annual fuel savings, protect equipment from freezing and increase employee comfort. The system uses two plate-type heat exchangers and a fiber glass baghouse utilizing reverse air cleaning. The heat exchangers were designed to lower the kiln exhaust temperature

B. Krout; J. Kilheffer

1984-01-01

182

High temperature heat exchanger studies for applications to gas turbines  

NASA Astrophysics Data System (ADS)

Growing demand for environmentally friendly aero gas-turbine engines with lower emissions and improved specific fuel consumption can be met by incorporating heat exchangers into gas turbines. Relevant researches in such areas as the design of a heat exchanger matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in this paper. Based on results reported in previous studies, potential heat exchanger designs for an aero gas turbine recuperator, intercooler, and cooling-air cooler are suggested.

Min, June Kee; Jeong, Ji Hwan; Ha, Man Yeong; Kim, Kui Soon

2009-12-01

183

Direct contact droplet heat exchangers for thermal management in space  

NASA Technical Reports Server (NTRS)

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.

Bruckner, A. P.; Hertzberg, A.

1982-01-01

184

Tubular heat exchanger design. Complement to the report MT 131  

NASA Astrophysics Data System (ADS)

An interactive program for a minicomputer which calculates the thermal performance of shell and tube heat exchangers was written. The algorithms used and program data flow are described. Heat transfer and pressure drop correlations were assembled from the literature to aid in limiting the overdimensioning of heat exchangers. The user can solve design problems by updating geometrical input parametes until the desired performance criteria are reached. The behavior of a given heat exchanger in partial load or overload conditions, or an exchanger having different fluids can be checked by changing general performance criteria or fluid numbers. An example of a marine oil cooler is used to illustrate use of the program.

Vandeberghe, F.

1980-11-01

185

Heat extraction from salinity-gradient solar ponds using heat pipe heat exchangers  

SciTech Connect

This paper presents the results of experimental and theoretical analysis on the heat extraction process from solar pond by using the heat pipe heat exchanger. In order to conduct research work, a small scale experimental solar pond with an area of 7.0 m{sup 2} and a depth of 1.5 m was built at Khon Kaen in North-Eastern Thailand (16 27'N102 E). Heat was successfully extracted from the lower convective zone (LCZ) of the solar pond by using a heat pipe heat exchanger made from 60 copper tubes with 21 mm inside diameter and 22 mm outside diameter. The length of the evaporator and condenser section was 800 mm and 200 mm respectively. R134a was used as the heat transfer fluid in the experiment. The theoretical model was formulated for the solar pond heat extraction on the basis of the energy conservation equations and by using the solar radiation data for the above location. Numerical methods were used to solve the modeling equations. In the analysis, the performance of heat exchanger is investigated by varying the velocity of inlet air used to extract heat from the condenser end of the heat pipe heat exchanger (HPHE). Air velocity was found to have a significant influence on the effectiveness of heat pipe heat exchanger. In the present investigation, there was an increase in effectiveness by 43% as the air velocity was decreased from 5 m/s to 1 m/s. The results obtained from the theoretical model showed good agreement with the experimental data. (author)

Tundee, Sura; Terdtoon, Pradit; Sakulchangsatjatai, Phrut [Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand); Singh, Randeep; Akbarzadeh, Aliakbar [Energy Conservation and Renewable Energy Group, School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora East Campus, Bundoora, Victoria 3083 (Australia)

2010-09-15

186

The LUX prototype detector: Heat exchanger development  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

187

Acoustic resonance in heat exchanger tube banks  

NASA Astrophysics Data System (ADS)

Fluid mechanics of acoustic resonance in heat exchanger tube bundles continues. Data and theory, development of models for the acoustics of tube bundles, and construction of a wind tunnel and tube array model were previously reviewed. In the present phase of the problem, both the wind tunnel model and the analytical model were exercised. Using the wind tunnel, the ability of coherent sound to shift the natural frequency of vortex shedding was demonstrated. Sound at the vortex shedding frequency can also increase the magnitude of the shed vortex and increases the spanwise coherence. Acoustic resonance due to vortex and shedding from tube arrays was observed. The acoustic mode of the resonance was measured, and it is found to agree well with analytical predictions. Work on development of a nonlinear dynamic model for vortex shedding has been initiated. This model features coupled nonlinear oscillators that will simulate the sound-induced entrainment phenomena.

Blevins, R. D.

1984-11-01

188

Development of a Novel High-Performance Contact Heat Exchanger.  

National Technical Information Service (NTIS)

The development of a contact heat exchanger for space station type applications with the objective of providing on-orbit replaceability of damaged or degraded radiators is described. The device is to provide disconnect type thermal coupling between heat p...

W. H. Miller T. Buna

1988-01-01

189

Predict the temperature distribution in gas-to-gas heat pipe heat exchanger  

NASA Astrophysics Data System (ADS)

A theoretical model has been developed to investigate the thermal performance of a continuous finned circular tubing of an air-to-air thermosyphon-based heat pipe heat exchanger. The model has been used to determine the heat transfer capacity, which expresses the thermal performance of heat pipe heat exchanger. The model predicts the temperature distribution in the flow direction for both evaporator and condenser sections and also the saturation temperature of the heat pipes. The approach used for the present study considers row-by-row heat-transfer in evaporator and condenser sections of the heat pipe heat exchanger.

Azad, E.

2012-07-01

190

Combined Steady-State and Dynamic Heat Exchanger Experiment  

ERIC Educational Resources Information Center

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…

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

2009-01-01

191

Heat Exchange in Stirrer Vessels in Monophase Liquids.  

National Technical Information Service (NTIS)

In the field of heat transfer in stirrer vessels in monophase systems, the heat transfer behavior in the hydrodynamic regions, the description of heat exchange on the basis of similarity theory, the precalculation of heat transfer by means of empirical fo...

R. Poggemann

1978-01-01

192

Two dimensional model for multistream plate fin heat exchangers  

NASA Astrophysics Data System (ADS)

A model based on finite volume analysis is presented here for multistream plate fin heat exchangers for cryogenic applications. The heat exchanger core is discretised in both the axial and transverse directions. The model accounts for effects of secondary parameters like axial heat conduction through the heat exchanger metal matrix, parasitic heat in-leak from surroundings, and effects of variable fluid properties/metal matrix conductivity. Since the fins are discretised in the transverse direction, the use of a fin efficiency is eliminated and the effects of transverse heat conduction/stacking pattern can be taken care of. The model is validated against results obtained using commercially available software and a good agreement is observed. Results from the developed code are discussed for sample heat exchangers.

Goyal, Mukesh; Chakravarty, Anindya; Atrey, M. D.

2014-05-01

193

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

Microsoft Academic Search

A simplified model of heat transfer was developed to investigate the thermal behavior of heat exchangers and stack plates of thermoacoustic devices. The model took advantage of previous results describing the thermal behavior of the thermoacoustic core and heat transfer in oscillating flow to study the performance of heat exchangers attached to the core. The configuration considered is a flat

Cila Herman; Yuwen Chen

2006-01-01

194

Effect of Lewis number on wet surface heat exchangers  

Microsoft Academic Search

A linearized approximate modified analogy theory of wet surface heat exchangers, was developed which predicts the effect of Lewis number more accurately, by introducing modified transfer coefficients, wet bulb depression and wet bulb temperature. A linear approximate model of wet surface heat exchangers is adopted and the equations of the model are rearranged with approximations to two independent sets of

Mubashar Zafar

1987-01-01

195

Universal Monitor (UM) for OTEC compact heat exchangers  

SciTech Connect

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.

Kuzay, T.M.

1981-09-01

196

Failure analysis of heat exchanger tubes of four gas coolers  

Microsoft Academic Search

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

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

2011-01-01

197

Flat Plate Heat Exchangers for the New Production Reactor.  

National Technical Information Service (NTIS)

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 i...

R. S. Ondrejcin

1988-01-01

198

Computer techniques to analyse shell-and-tube heat exchangers  

SciTech Connect

Computer analyses to predict thermal-hydraulics, flow-induced vibration and fretting-wear damage in shell-and-tube heat exchangers are outlined. The analytical techniques are briefly described and the results are illustrated by examples. It is concluded that computer techniques can do much to improve the reliability and performance of heat exchangers.

Pettigrew, M.J.; Carlucci, L.N.; Ko, P.L.; Holloway, G.L.; Campagna, A.O.

1983-01-01

199

Use of phosphoric acid to remove heat exchanger deposits  

Microsoft Academic Search

removing these deposits. The deposits that foul heat exchangers usually consist of inorganic compounds cemented by tarry poly- merized products (1); they are formed in heat exchangers through the oxidation of hydrocarbons at high tem- peratures. Operating experience at the Novo-Ufa refinery has indicated that the initial processing of mixed West Siberian crudes in the unit was accompanied by a

T. M. Idrisova; Yu. M. Avyzgil'din; G. G. Telyashev; F. G. Gataullin; Yu. I. Kir'yanov

1979-01-01

200

Predicting Refinery Energy Losses Due to Fouling in Heat Exchangers  

Microsoft Academic Search

Energy efficiency is paramount in an oil refinery and heat integration is critical, especially in the energy-intensive atmospheric distillation unit. Thermal and hydraulic performance of each exchanger in the network used to pre-heat the crude is greatly reduced by the progressive deposition of unwanted material on the thermal exchange surfaces. Here, a detailed mathematical model for a shell and tube

Francesco Coletti; Sandro Macchietto

2009-01-01

201

Oil refinery saves $5500\\/wk cleaning own heat exchanger bundles  

Microsoft Academic Search

Hydrodrills supplied by Global Heat Exchanger, Inc. saves an oil refinery in California $5500 per week by enabling the refinery to do all their tube and shell heat exchanger cleaning. The refinery is so satisfied with the hydrodrills, which have been in operation for three years, that they plan to purchase another in the near future.

Regan

1983-01-01

202

Self-defrosting recuperative air-to-air heat exchanger  

Microsoft Academic Search

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

Drake

1993-01-01

203

Numerical computation of sapphire crystal growth using heat exchanger method  

Microsoft Academic Search

The finite element software FIDAP is employed to study the temperature and velocity distribution and the interface shape during a large sapphire crystal growth process using a heat exchanger method (HEM). In the present study, the energy input to the crucible by the radiation and convection inside the furnace and the energy output through the heat exchanger is modeled by

Chung-Wei Lu; Jyh-Chen Chen

2001-01-01

204

Direct contact heat exchangers for geothermal power plants  

Microsoft Academic Search

Several details relating to the design considerations for geothermal power plants using direct contact heat exchangers are given. Primary emphasis is given here to boiler and turbine parameters. Reports are outlined of tests of various types of heat exchangers in our laboratory and at the Raft River Geothermal Well. Also discussed are various parameters that affect the operation of turbines

R. Boehm; H. Jacobs; R. Bliss; D. Kelly

1976-01-01

205

Multifrequency Eddy Current Evaluation of Heat Exchangers Structures  

NASA Astrophysics Data System (ADS)

In this paper a method of flaw detection in heat exchangers is presented. The aim of this work was to evaluate the eddy current testing algorithm which will be effective in case of complex structures evaluation. The final target is to propose the modified version of the transducer for tube heat exchangers. For tubes with irregular construction of exchanging surface, different configurations of transducer excitation was used to reduce influence of radiator elements.

Chady, T.; Kowalczyk, J.

2009-03-01

206

Reactor safety research section probability of heat exchanger leaks  

SciTech Connect

Three heat exchangers (HXs) were changed out after the December 1991 leak of Process Water to the Savannah River. This leaves 6 of the original 304 stainless steel heat exchangers which will remain in K-Reactor for restart. This report discusses SRS site specific data which were used to estimate the probability of a leak within a one-year period as a function of leak rate and root cause in these six heat exchangers in conjunction with six new heat exchangers presently in service in K-Reactor. Based on several assumptions and statistical models, SRS data indicate that the total probability of a leak occurring during a one-year period in K-Reactor with 6 original (304 stainless steel) and 6 new (316-L or SEA-CURE) heat exchangers, with a leak rate greater than 20, 40 or 90 pounds/hr, is 0.013, 0.004 or 0.0005, respectively.

Cramer, D.S.; Shine, E.P.; Copeland, W.J.

1992-02-01

207

Special Heat Transfer Monitor (HTM) For the Trane Company OTEC Heat Exchanger.  

National Technical Information Service (NTIS)

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 ...

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

1981-01-01

208

The Design on the Refrigerant Circuit of Heat Exchanger  

NASA Astrophysics Data System (ADS)

The efficient design method for plate fin-and-tube heat exchanger has been developed with the directed graph(graph-based traversal method) in graph theory and the distribution model of refrigerant flow rate. According to the experimental results of heat exchanger which is carried out under 98 experimental conditions of the changes of air velocity and the refrigerant flow rates and so on, by using the refrigerant R 22 and R 410A, we conclude the following deviations of analysis: the heat transfer rate is within ±10% and the pressure drop is within ±20%. Now this design method has being used for designing plate fin-and-tube heat exchangers efficiently.

Wang, Kaijian; Fukaya, Masaharu; Ding, Guoliang; Liu, Jian

209

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

210

Testing of direct contact heat exchangers for geothermal brines  

Microsoft Academic Search

A 350,000 Btu\\/hr test loop was built and operated to assess the feasibility of utilizing direct contact heat exchange between a secondary working fluid and brine from liquid dominated geothermal resources. Isobutane working fluid was continuously heated in a liquid-liquid preheater and then vaporized in a separate boiler by direct contact heat exchange with 325 F simulated brine. The preheater

W. B. Suratt; G. K. Hart

1977-01-01

211

Optimal synthesis of heat exchanger network for thermochemical SI cycle  

Microsoft Academic Search

In this paper, a brief survey of hydrogen production methods is presented with a focus on S-I cycle. Based on heat duty data\\u000a of sulfuric acid decomposition in S-I cycle, optimization models are developed to explore the minimum utility consumption\\u000a and the minimum number of heat exchangers. Finally an optimal heat exchanger network for S-I thermochemical cycle is defined\\u000a by

H. Liu; I. Kantor; A. Elkamel; M. Fowler

2009-01-01

212

High-temperature ceramic heat exchanger. Final report  

Microsoft Academic Search

The results of an 18-month effort directed to developing the technology necessary to build a ceramic heat exchanger for operation with a small (200-hp) closed-Brayton-cycle engine are described. The ceramic heat exchanger operates with 3000°F combustion products on one side and heats high-pressure Argon gas, which subsequently is delivered to the turbine, to 1800°F. The design consisting of an array

M. Coombs; D. Kotchick; H. Warren

1979-01-01

213

High-temperature ceramic-heat-exchanger development. Final report  

Microsoft Academic Search

This report describes the results of a 27-month follow-on effort directed toward developing the technology necessary to build a high-temperature, high-pressure ceramic heat exchanger for operation with a small (200-hp) closed Brayton cycle engine. The ceramic heat exchanger operates with 3000°F combustion products on one side and heats high-pressure argon gas, which subsequently is delivered to a turbine, at 1800°F.

M. Coombs; D. Kotchick; M. Weidhaas

1983-01-01

214

Thermal and hydraulic performance of a graphite block heat exchanger  

Microsoft Academic Search

A test rig has been assembled to investigate the thermodynamic and hydraulic performance of a cylindrical graphite block heat exchanger consisting of three graphite blocks and a steel shell. The flow pattern in the heat exchanger was triple cross-flow on the shell-side (service side) with one pass per block and a single pass on the tube-side (process side). Overall heat

G. Schou; J. Deans; J. Künzel; H. Müller-Steinhagen

1997-01-01

215

Evaluation of porous media heat exchangers for fusion applications  

SciTech Connect

Several types of porous media heat exchangers are being evaluated for use in fusion applications. Broadly, these devices can be classified as capillary-pumped (heat pipes) or mechanically-pumped heat exchangers. Monel/water thermosyphon heat pipes with a porous metal wick are being evaluated for use in Faraday shields. A subscale prototype has been fabricated, and initial tests at Oak Ridge National Laboratory have shown favorable results. Alkali metal heat pipes have demonstrated absorbed heat flux capability of over 1000 MW/m{sup 2}. An advanced gyrotron microwave cavity is being developed that uses water cooling in a mechanically-pumped copper porous metal heat exchanger. Tests on a prototype demonstrated absorbed heat flux capability in excess of 100 MW/m{sup 2}. Porous metal heat exchangers with helium, water, or liquid metal coolants are being evaluated for plasma-facing component cooling. Tests on a helium/copper porous metal heat exchanger demonstrated absorbed heat flux capability in excess of 15 MW/m{sup 2}. Applications, conceptual designs, fabricated hardware, and test results are summarized. 22 refs., 5 figs., 2 tabs.

Rosenfeld, J.H.; Lindemuth, J.E.; North, M.T. [Thermacore Inc., Lancaster, PA (United States); Watson, R.D.; Youchison, D.L. [Sandia Natinal Lab., Albuquerque, NM (United States); Goulding, R.H. [Oak Ridge National Lab., TN (United States)

1996-07-01

216

Comparison of natural convection heat exchangers for solar water heating systems  

SciTech Connect

Thermosyphon heat exchangers are used in indirect solar water heating systems to avoid using a pump to circulate water from the storage tank to the heat exchanger. In this study, the authors consider the effect of heat exchanger design on system performance. They also compare performance of a system with thermosyphon flow to the same system with a 40W pump in the water loop. In the first part of the study, the authors consider the impact of heat exchanger design on the thermal performance of both one- and two-collector solar water heaters. The comparison is based on Solar Rating and Certification Corporation (SRCC) OG300 simulations. The thermosyphon heat exchangers considered are (1) a one-pass, double wall, 0.22 m{sup 2}, four tube-in-shell heat exchanger manufactured by AAA Service and Supply, Inc., (the Quad-Rod); (2) a two-pass, double wall, 0.2 m{sup 2}, tube-in-shell made by Heliodyne, Inc., but not intended for commercial development; (3) a one-pass, single wall, 0.28 m{sup 2}, 31 tube-in-shell heat exchanger from Young Radiator Company, and (4) a one-pass single-wall, 0.61 m{sup 2}, four coil-in-shell heat exchanger made by ThermoDynamics Ltd. The authors compare performance of the systems with thermosyphon heat exchangers to a system with a 40 W pump used with the Quad-Rod heat exchanger. In the second part of the study, the effects of reducing frictional losses through the heat exchanger and/or the pipes connecting the heat exchanger to the storage tank, and increasing heat transfer area are evaluated in terms of OG300 ratings.

Davidson, J.; Liu, W.

1998-09-15

217

Fluid flow consideration in fin-tube heat exchanger optimization  

NASA Astrophysics Data System (ADS)

The optimization of finned tube heat exchanger is presented focusing on different fluid velocities and the consideration of aerodynamic configuration of the fin. It is reasonable to expect an influence of fin profile on the fluid streamline direction. In the cross-flow heat exchanger, the air streams are not heated and cooled evenly. The fin and tube geometry affects the flow direction and influences temperature changes. The heat transfer conditions are modified by changing the distribution of fluid mass flow. The fin profile impact also depends on the air velocity value. Three-dimensional models are developed to find heat transfer characteristics between a finned tube and the air for different air velocities and fin shapes. Mass flow weighted average temperatures of air volume flow rate are calculated in the outlet section and compared for different fin/tube shapes in order to optimize heat transfer between the fin material and air during the air flow in the cross flow heat exchanger.

Wais, Piotr

2010-09-01

218

Microchannel crossflow fluid heat exchanger and method for its fabrication  

DOEpatents

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.

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

1985-05-14

219

Analysis of coiled-tube heat exchangers to improve heat transfer rate with spirally corrugated wall  

Microsoft Academic Search

Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the

A. Zachár

2010-01-01

220

Numerical and experimental investigations of heat transfer performance of rectangular coil heat exchangers  

Microsoft Academic Search

Both numerical and experimental investigations were conducted to understand convective heat transfer from a single round pipe coiled in rectangular pattern. The studied heat exchangers are composed with inner and outer coils so that the exterior flow is very similar to flow within tube-bundles. The inner and outer coils of the heat exchangers are in turn composed of bends and

I. Conté; X. F. Peng

2009-01-01

221

Evaporation heat transfer and pressure drop of refrigerant R-134a in a plate heat exchanger  

Microsoft Academic Search

Plate heat exchangers (PHE) have been widely used in food processing, chemical reaction processes, and other industrial applications for many years. Particularly, in the last 20 years plate heat exchangers have been introduced to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. Here, the evaporation heat transfer coefficient and pressure drop for

Y.-Y. Yan; T.-F. Lin

1999-01-01

222

A heat exchanger model to increase energy efficiency in refinery pre heat trains  

Microsoft Academic Search

Crude oil fouling in pre-heat train heat exchangers has been a major problem in oil refining for decades. The operating problems, increased energy requirements and greenhouse gases emissions which arise from the inefficiencies caused by fouling are discussed. A mathematical model capable of predicting the dynamic behavior of a shell and tube heat exchanger undergoing fouling is used to assess

Francesco Coletti; Sandro Macchietto

2009-01-01

223

Heat exchanger and water tank arrangement for passive cooling system  

DOEpatents

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.

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

1993-11-30

224

Study of transient behavior of finned coil heat exchangers  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

225

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

SciTech Connect

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.

Panchal, C.B.

1993-07-01

226

Study of transient behavior of finned coil heat exchangers  

NASA Astrophysics Data System (ADS)

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.

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

1993-11-01

227

Miniature Joule - Thomson liquefier with sintered heat exchanger  

NASA Astrophysics Data System (ADS)

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.

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

228

Slotting Fins of Heat Exchangers to Provide Thermal Breaks  

NASA Technical Reports Server (NTRS)

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.

Scull, Timothy D.

2003-01-01

229

Heat exchanger for reactor core and the like  

DOEpatents

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

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

1986-01-01

230

Experimental determination of correlations for mean heat transfer coefficients in plate fin and tube heat exchangers  

NASA Astrophysics Data System (ADS)

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

Taler, Dawid

2012-09-01

231

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

NASA Astrophysics Data System (ADS)

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

Taler, Dawid

2013-08-01

232

Advanced Heat Exchangers Program review meeting. Summary report.  

National Technical Information Service (NTIS)

On a semiannual basis a review meeting of the US Department of Energy's Advanced Heat Exchangers Program is held with the objective of reviewing ongoing and recently completed project activities. During the meeting, personnel from industrial contractors a...

1990-01-01

233

Heat Exchangers for High-Temperature Thermodynamic Cycles.  

National Technical Information Service (NTIS)

The special requirements of heat exchangers for high temperature thermodynamic cycles are outlined and discussed with particular emphasis on cost and thermal stress problems. Typical approaches that have been taken to a comprehensive solution intended to ...

A. P. Fraas

1975-01-01

234

Potential Heat Exchange Fluids for Use in Sulfuric Acid Vaporizers.  

National Technical Information Service (NTIS)

A series of liquids have been screened 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 physi...

D. D. Lawson G. R. Petersen

1979-01-01

235

An automatically compensating heat-exchange calorimeter for metabolic studies  

Microsoft Academic Search

This paper describes an easily constructed calorimeter functioning on a heat-exchange principle in which a continuously flowing\\u000a coolant removes heat at a preset rate. Variations in heat loss from an experimental animal are compensated by a resistance\\u000a hot wire in a simple feed-back circuit so that calorimeter temperature is held constant. Accommodation for simultaneous measurement\\u000a of oxygen consumption (heat production)

George V. Pickwell

1968-01-01

236

Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor  

SciTech Connect

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.

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

2011-04-01

237

Contaminant Transfer in Rotary Heat Exchangers.  

National Technical Information Service (NTIS)

In air conditioning, regenerators are widely used for heat recovery of exhaust air. A regenerator can simultaneously transfer heat and water or other compounds from exhaust to supply air. In particular the regenerators with hygroscopic matrix materials ca...

S. Enbom

1986-01-01

238

DOE/ANL/HTRI heat exchanger tube vibration data bank  

SciTech Connect

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.

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

1981-01-01

239

Advances in Science and Technology of Compact Heat Exchangers  

Microsoft Academic Search

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

Ramesh K. Shah

2006-01-01

240

High temperature heat exchanger studies for applications to gas turbines  

Microsoft Academic Search

Growing demand for environmentally friendly aero gas-turbine engines with lower emissions and improved specific fuel consumption\\u000a can be met by incorporating heat exchangers into gas turbines. Relevant researches in such areas as the design of a heat exchanger\\u000a matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in\\u000a this paper. Based on results reported

June Kee Min; Ji Hwan Jeong; Man Yeong Ha; Kui Soon Kim

2009-01-01

241

Fabrication of metallic heat exchangers using sacrificial polymer mandrils  

Microsoft Academic Search

This paper demonstrates the use of poly(dimethylsiloxane) (PDMS), polyurethane (PU), epoxy, and poly(methyl methacrylate) (PMMA) as mandrils to fabricate metallic heat exchangers having 300-700 ?m internal channels. The mandrils were prepared using two soft lithographic techniques-replica molding and microembossing. To fabricate the heat exchangers, the polymeric mandrils were coated with a thin layer of metal by thermal evaporation or sputtering;

Francisco Arias; Scott R. J. Oliver; Bing Xu; R. Erik Holmlin; George M. Whitesides

2001-01-01

242

Two-phase/two-phase heat exchanger analysis  

NASA Technical Reports Server (NTRS)

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.

Kim, Rhyn H.

1992-01-01

243

Fin Distance Effect at Tube-Fin Heat Exchanger  

NASA Astrophysics Data System (ADS)

Article deals with numerical simulation of the Tube-Fin heat exchanger. Several distances between fins are examined with intence of increasing the cooling output of the heat exchanger. Geometrical model consists of set of 2 fins with input and output area. Calculations covers the area of the gap from 2.25 mm to 4 mm with new fin geometry. For the numerical silumation was used software Ansys Fluent.

Lemfeld, F.; Muller, M.; Frana, K.

2013-04-01

244

Nomograms for Calculating Turbulent Heat Exchange and Heat Loss by Evaporation.  

National Technical Information Service (NTIS)

Calculation of turbulent heat exchange and heat loss by evaporation with empirical formulas is a rather long and work-consuming operation, requiring cumbersome computations, consisting of series of successive calculations. To facilitate such calculations ...

V. A. Shamontev

1970-01-01

245

Brazed aluminum, Plate-fin heat exchangers for OTEC  

SciTech Connect

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

Foust, H.D.

1980-12-01

246

Acoustically enhanced heat exchange and drying apparatus  

DOEpatents

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.

Bramlette, T. Tazwell (Livermore, CA); Keller, Jay O. (Oakland, CA)

1989-01-01

247

Heat Storage Characteristics of Latent-Heat Microcapsule Slurry Using Hot Air Bubbles by Direct-Contact Heat Exchange  

Microsoft Academic Search

This study deals with the heat storage characteristics of latent-heat microcapsule slurry consisting of a mixture of fine microcapsules packed with latent-heat storage material and water. The heat storage operation for the latent-heat microcapsules was carried out by the direct-contact heat exchange method using hot air bubbles. The latent-heat microcapsule consisted of n-paraffin as a core latent-heat storage material and

Hideo Inaba; Akihiko Horibe; Myoung-Jun Kim; Hirofumi Tsukamoto

2001-01-01

248

HEAT EXCHANGER DESIGN STUDIES FOR AN LHC INNER TRIPLET UPGRADE  

SciTech Connect

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.

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

2008-03-16

249

Radiation and natural convection heat transfer from wire-and-tube heat exchangers in refrigeration appliances  

Microsoft Academic Search

The air-side heat transfer from wire-and-tube heat exchangers of the kind widely used in small refrigeration appliances has been studied. Radiation and free-convection components have been separately investigated. The radiation component was theoretically computed using a diffuse, gray-body network with interactions between each part of the heat exchanger and the surroundings. For the free-convection heat transfer component, a semiempirical correlation

L Tagliafico; G Tanda

1997-01-01

250

Self-defrosting recuperative air-to-air heat exchanger  

DOEpatents

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.

Drake, R.L.

1993-12-28

251

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

NASA Astrophysics Data System (ADS)

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.

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

252

Use of a fluidized bed heat exchanger to improve the performance of a heat pump. Final report  

Microsoft Academic Search

The outdoor evaporator heat exchanger of a York 60,000 Btu heat pump in the heating mode was replaced with a fluidized bed heat exchanger. Air temperature control was achieved by recirculating the conditioned air from both the evaporator and condenser heat exchangers through a chambered plenum. Candidate particles and distributor plates for the design of the bed were tested separately.

R. G. Sarubbi; J. C. Chen

1981-01-01

253

Review of Heat Transfer and Pressure Drop Correlations for Evaporation of Fluid Flow in Plate Heat Exchangers (RP1352)  

Microsoft Academic Search

Plate heat exchangers have been widely used in dairy, food processing, paper\\/pulp, heating, ventilating, and other related industry. While single-phase flow in plate heat exchangers has been studied extensively, the industry lacks basic information on fluid flow evaporating in plate heat exchangers. This paper provides a review of heat transfer and pressure drop correlations for fluid flow evaporating in plate

Tariq S. Khan; Mohammad S. Khan; Ming-C. Chyu; Zahid H. Ayub; Javed A. Chattha

2009-01-01

254

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

SciTech Connect

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

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

2005-07-01

255

Heat transfer and pressure drop during HFC refrigerant vaporisation inside a brazed plate heat exchanger  

Microsoft Academic Search

This paper presents the experimental heat transfer coefficients and pressure drop measured during HFC refrigerant 134a, 410A and 236fa vaporisation inside a small brazed plate heat exchanger: the effects of heat flux, refrigerant mass flux, saturation temperature, outlet conditions and fluid properties are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure

G. A. Longo; A. Gasparella

2007-01-01

256

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

NASA Astrophysics Data System (ADS)

The development of a novel condensing heat exchanger, a modulating gas burner, and a zone-controlled residential warm-air heating system is described. The condensing heat exchanger uses ten thermosyphons which are manifolded at both the condenser and evaporator ends to achieve a compact low-cost design. Initial tests have demonstrated a + 92 percent steady-state efficiency for a conventional clamshell furnace operating with the thermosyphon heat exchanger located outside the furnace cabinet. A 100,000 -Btu/hr modulating burner has also been developed. Comprehensive study of the burner's operating characteristics has produced guidelines for the design and application of the device. Finally, the modulating burner has been incorporated into a zone-controlled heating system. In parallel with the development of the preceding heating system components, the performance of thermosyphons over a wide range of operating conditions is being explored with the objective of improving design procedures for incorporating these devices into heat exchangers.

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

1986-03-01

257

Nuclear reactor having double tube helical coil heat exchanger  

Microsoft Academic Search

A method for removing decay heat in a nuclear power plant is described comprising a nuclear reactor having a circulating liquid metal cooling system, which cooling system includes at least one heat exchanger comprising a vessel having a closed lower end. The cylindrical vessel is closed at its upper end by a closure plate having feedwater inlet nozzles and steam

G. Garabedian; R. A. De Luca

1988-01-01

258

Thermal Performance of a Geofluid Direct-Contact Heat Exchanger.  

National Technical Information Service (NTIS)

A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280 exp 0 F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ...

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

1983-01-01

259

Thermal performance of direct contact heat exchangers for mixed hydrocarbons  

Microsoft Academic Search

This paper describes a physical and a mathematical model for evaluating the tray efficiencies for a direct contact heat exchanger (DCHX). The model is then used to determine the efficiencies for tests conducted on a 60kW sieve tray DCHX as heat is transferred from a geofluid (brine) to a working fluid (mixed hydrocarbons). It is assumed that there are three

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

1985-01-01

260

Performance monitoring and replacement of heat exchanger components and materials  

Microsoft Academic Search

This book contains papers presented at the 1990 International Joint Power Generation Conference. Included are the following articles: A comparison of heat transfer coefficients, Extend heat exchanger and condenser life with metal alloy inserts, Design, service conditions and deaerator cracking in Dutch utility boilers.

1990-01-01

261

MULTIPLE POLLUTANT REMOVAL USING THE CONDENSING HEAT EXCHANGER  

Microsoft Academic Search

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

B. J. JANKURA; G. A. KUDLAC; R. T. BAILEY

1998-01-01

262

Application of Nanofluids in Thermal Design of Compact Heat Exchanger  

Microsoft Academic Search

Compact heat exchangers have been widely used in various applications in thermal fluid systems including automotive thermal fluid systems. Radiators for engine cooling systems, evaporators and condensers for HVAC systems, oil coolers and inter coolers are typical examples that can be found in ground vehicles. Recent development of Nanotechnology brings out a new heat transfer coolant called 'Nanofluids' these fluids

V. Vasu; K. Rama Krishna; A. C. S. Kumar

263

Heat Exchange in Stirrer Vessels in Multiphase Systems.  

National Technical Information Service (NTIS)

In the field of indirect heat exchange in stirrer boilers for gas-liquid, liquid-liquid, solid-liquid, and solid-gas systems, the heat transfer behavior has been analyzed and presented from the point of view of similarity theory. Experimental results from...

A. Steiff

1978-01-01

264

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

Microsoft Academic Search

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

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

2012-01-01

265

Deposition from Crude Oils in Heat Exchangers  

Microsoft Academic Search

Deposition in flow lines and processing and heat transfer equipment arises from fouling species, which may either be present in the fluid or generated in the vicinity of the equipment surface. Recent research on deposition during heat transfer from petroleum feedstocks is reviewed. For low-sulfur light crude oils, deposition is largely due to particulates and gums. For medium-sulfur crude oils,

A. Paul Watkinson

2007-01-01

266

Capillary pumped loop body heat exchanger  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

267

Direct use geothermal applications for brazed plate heat exchangers  

SciTech Connect

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.

Rafferty, K.

1993-02-01

268

Hydraulic and thermal design of a gas microchannel heat exchanger  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

269

Direct use geothermal applications for brazed plate heat exchangers  

SciTech Connect

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.

Rafferty, K.

1992-12-31

270

Thermal performance of advanced heat exchangers for ammonia refrigeration systems  

SciTech Connect

Current practice in the ammonia industry is to use plain tubes. This article demonstrates that the coefficient of performance (COP) can be increased by about 11% using tubes with ammonia-side enhancement and by about 26% using tubes with ammonia-side and water-side enhancement. Further improvements with respect to energy and cost are possible with the compact heat exchanger types -- plate-frame and plate-fin -- because they can be optimized for the system conditions for each application. These findings are based on experimentally determined overall heat transfer coefficients that were obtained for candidate heat exchangers for the Ocean Thermal Energy Conversion (OTEC) program.

Panchal, C.B.; Rabas, T.J. [Argonne National Lab., IL (United States)

1993-10-01

271

Performance Prediction of Cross-finned Tube Heat Exchangers  

NASA Astrophysics Data System (ADS)

An important issue in heat pumps is increasing their efficiency, in order to achieve a significant optimization for heat exchangers. Techniques to simulate the flow length averaged heat transfer coefficient and static pressure drop through the flow passage are presented in this paper. In addition, an analytical evaluation of the cost reduction for a cross-fined tube heat exchanger of outdoor heat pump units is instantiated. The dimensionless factors, Colburn's factor j and Fanning's friction factor f, express the heat transfer performance and frictional characteristics, as a function of Reynolds number. These depend on slit possession, an original parameter used in this study. Further, this paper describes an approximate expression of the fin efficiency, which can be used for to survey the fin parameters. The above three concepts were necessary to forecast the performance on the airside. In the results, the cost minimum point was obtained with a comparable performance.

Kondou, Chieko; Senshu, Takao; Matsumura, Kenji; Oguni, Kensaku

272

Comprehensive study of heat transfer enhancement in tubular heat exchangers  

NASA Astrophysics Data System (ADS)

A study was conducted of heat transfer enhancement in a heated tube in which a supercritical-pressure kerosene and oil flowed under the conditions of carbon deposit. This technique proved to be very effective when applied to boiling of heat carriers. At disperse and slug film boiling inside tubes, heat transfer increases three to eight times, and at surface boiling of water and water-glycerine mixtures, by 30-40 percent.

Kalinin, E. K.; Dreitser, G. A.; Paramonov, N. V.; Miakochin, A. S.; Tikhonov, A. I.; Zakirov, S. G.; Levin, E. S.; Ianovskii, L. S.

1991-11-01

273

Thermodynamic analysis and optimization of air-cooled heat exchangers  

NASA Astrophysics Data System (ADS)

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.

Salimpour, Mohammad Reza; Bahrami, Zabihollah

2011-01-01

274

Wall mounted heat exchanger characterization. [cryogenic propellant tanks  

NASA Technical Reports Server (NTRS)

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.

Bullard, B. R.

1975-01-01

275

Fast reactor power plant design having heat pipe heat exchanger  

DOEpatents

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.

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

1985-01-01

276

Fast reactor power plant design having heat pipe heat exchanger  

DOEpatents

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.

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

1984-08-30

277

Active heat exchange thermal storage unit with pentaerythritol  

Microsoft Academic Search

A latent thermal energy storage unit with pentaerythritol was developed, and in the storage unit an active heat transfer enhancement was performed. The phase change material, pentaerythritol, was mixed with a hydrocarbon heat transfer oil and this two-phase storage medium was stirred in a shell-coil type heat exchanger. Through the preliminary experiments in a glass vessel, a lab-scale storage unit

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

1984-01-01

278

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

NASA Astrophysics Data System (ADS)

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.

Schreiber, Jeffrey G.

279

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

NASA Astrophysics Data System (ADS)

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.

Schreiber, Jeffrey G.

1988-05-01

280

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

NASA Technical Reports Server (NTRS)

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.

Schreiber, Jeffrey G.

1988-01-01

281

Comparison of the thermal performance of double U-pipe borehole heat exchangers measured in situ  

Microsoft Academic Search

A borehole heat exchanger is a ground heat exchanger devised for the extraction or injection of thermal energy from\\/into the ground. The thermal performance of a borehole heat exchanger can be assessed with a response test. The response test method allows the in situ determination of the thermal conductivity of the ground in the vicinity of a borehole heat exchanger,

D. Pahud; B. Matthey

2001-01-01

282

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

283

High Performance Titanium Plate Fin Heat Exchanger Using a Novel Manufacturing Process.  

National Technical Information Service (NTIS)

The Plate Fin Heat Exchanger (PFHE), a compact heat exchanger which offers significant advantages over shell and tube exchangers in terms of weight, volume, and thermal effectivenesss, is described. It has a multistream capability and consequently a singl...

C. I. Adderley J. O. Fowler

1991-01-01

284

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

SciTech Connect

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.

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

1981-02-01

285

Assessment of next generation nuclear plant intermediate heat exchanger design.  

SciTech Connect

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 shell and straight tube and printed circuit heat exchangers.

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

2008-10-17

286

Heat transfer enhancement in cross-flow heat exchangers using oval tubes and multiple delta winglets  

Microsoft Academic Search

A three-dimensional study of laminar flow and heat transfer in a channel with built-in oval tube and delta winglets is carried out through the solution of the complete Navier–Stokes and energy equations using a body-fitted grid and a finite-volume method. The geometrical configuration represents an element of a gas–liquid fin–tube cross-flow heat exchanger. The size of such heat exchangers can

S. Tiwari; D. Maurya; G. Biswas; V. Eswaran

2003-01-01

287

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

NASA Astrophysics Data System (ADS)

The work presented includes: (1) the development of a heat-pipe condensing heat exchanger; (2) the development of a nominal 100,000 Btu/hr modulating air/gas valve; (3) the experimental performance studies of a water/copper thermosyphons; (4) the field operation of a six-zone warm-air heating system; (5) the adaptation of a conventional venturi-type burner to modulation; and (6) the results of a one-day workshop for manufacturers of HVAC equipment on heat-pipe heat exchangers. Several of the accomplishments of the project included: An air/gas valve was adapted to furnaces with heat-pipe and drum-type heat exchangers, providing these furnaces with over a 5 to 1 turndown capability. A six-zone warm-air heating system was tested for two winters with the modulating furnaces previously described. A data base for the application of copper/water thermosyphons was started. A ten-tube heat-pipe heat exchanger was incorporated into a conventional heat exchanger with only a small increase in the furnace's dimensions.

Lowenstein, A.; Cohen, B.; Feldman, S.; Marsala, J.; Spatz, M.; Smith, E.; Tandler, J.

1988-02-01

288

Fouling of convective heat exchangers in an MHD steam plant  

SciTech Connect

At Argonne National Laboratory (ANL), the fouling of convective heat transfer surfaces by seed and coal ash is being studied to obtain data for MHD steam plant design. Fouling experiments are being conducted in the Fossil Energy Users Laboratory (FEUL). In these tests, the seed-slag deposition rates and their effects on heat transfer to the convective heat exchanger surfaces and the size distribution of the seed particles are measured. In addition, the characteristics of the seed-slag deposits are studied. In conjunction with the experiments, theoretical models are developed to predict the deposition rates of seed and ash, the heat transfer rates to the convective heat exchangers, and the size distribution of the seed particles. These models are applied to interpret and extrapolate the test results. The measured data, together with the theoretical models, are essential to the design of the convective sections of an MHD steam plant.

Chow, L.S.H.; Johnson, T.R.; Klinger, J.; Smyk, E.B.

1984-02-01

289

Fouling of convective heat exchangers in an MHD steam plant  

SciTech Connect

At Argonne National Laboratory (ANL), the fouling of the convective heat transfer surfaces by seed and coal ash is being studied in order to obtain data for MHD steam plant design. Fouling experiments are being conducted in the Fossil Energy Users Laboratory (FEUL). In these tests, the seed-slag deposition rates and their effects on heat transfer to the convective heat exchanger surfaces and the size distribution of the seed particles are measured. In addition, the characteristics of the seed-slag deposits are studied. In conjunction with the experiments, theoretical models are developed to predict: (1) the deposition rates of seed and ash, (2) the heat transfer rates to the convective heat exchangers, and (3) the size distribution of the seed particles. These models are applied to interpret and extrapolate the test results. The measured data, together with the theoretical models, are essential to the design of the convective sections of an MHD steam plant.

Chow, L.S.H.; Smyk, E.B.; Johnson, T.R.; Klinger, J.G.

1984-01-01

290

Heat exchange mediated by a quantum system.  

PubMed

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. PMID:23005731

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

2012-08-01

291

Heat exchange mediated by a quantum system  

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

292

A novel underground solar thermal heat storage unit cum heat exchanger for non air-conditioned buildings  

Microsoft Academic Search

A novel passive space conditioning configuration is presented, integrating a Solar Collector System, Underground Storage Tank and Novel Heat Exchanger. This Underground Solar Thermal Heat Exchanger (USTHE) provided improved sensible heating\\/cooling of air by employing a Novel Heat Exchanger (NHX). The dynamic performance of the storage tank in USTHE is modelled using the finite difference method accounting thermal stratification of

Rakesh Kumar; S. C. Kaushik

2003-01-01

293

Heat resistance of Talaromyces flavus ascospores as determined by a two phase slug flow heat exchanger  

Microsoft Academic Search

Heat resistance of Talaromyces flavus was determined using two methods. Standard thermal death time vials were used to determine the heat resistance of T. flavus ascospores, from 80 to 90 °C with a decimal reduction time D90 of 6.2 min. A continuous two-phase slug flow heat exchanger System with heating, holding and cooling sections was used to determine the heat

A. Douglas King

1997-01-01

294

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

SciTech Connect

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.

Love, Norman [University of Texas, El Paso; Szybist, James P [ORNL; Sluder, Scott [ORNL

2011-01-01

295

Flow-induced vibration of component cooling water heat exchangers  

SciTech Connect

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

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

1990-01-01

296

Dynamic tube/support interaction in heat exchanger tubes  

SciTech Connect

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

Chen, S.S.

1991-01-01

297

Heat exchange pipes for a furnace system  

Microsoft Academic Search

This patent describes improvement in a flue products exhaust and preheated combustion air supply assembly for use in association with a heating furnace wherein an air intake pipe is provided outside of and around an exhaust product pipe and wherein each of the pipes extend horizontally to openings outside of a building. It comprises: an air intake pipe and exhaust

1991-01-01

298

Rotating Heat Exchanger for Liquid Manure.  

National Technical Information Service (NTIS)

When you treat liquid manure aerobic or anaerobic, the liquid manure has to be heated from the stable temperature to processing temperature, for composting 50 deg. - 60 deg. C and for biogas approx. 35 deg. C. In the manure processing systems known today ...

P. Hauge L. Berthelsen

1988-01-01

299

Oil-fluorocarbon direct contact heat exchanger for low temperature power generation  

Microsoft Academic Search

In order to demonstrate the feasibility of power generation from medium and low temperature waste heat, geothermal heat, etc, a direct contact heat exchanger was developed. This new heat exchanger is especially excellent in its economies and heat exchange characteristics. To obtain design data for actual applications, a full-scale test was conducted to clarify problems encountered in the basic experiments.

S. Sakaguchi; U. Kuroda

1983-01-01

300

Exergy optimization in a steady moving bed heat exchanger.  

PubMed

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

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

2009-04-01

301

Application of heat pipe heat exchangers to humidity control in air-conditioning systems  

Microsoft Academic Search

Relative humidity control in air-conditioning systems is an important aspect of the maintenance of good indoor air quality. However, considerable reheat energy is needed to control relative humidity using conventional reheating coils. For improved energy efficiency a thermosyphon heat pipe heat exchanger is under investigation using a Hilton Air-Conditioning Laboratory Unit in RMIT. The study involves aspects of the heat

Xiao Ping Wu; Peter Johnson; Aliakbar Akbarzadeh

1997-01-01

302

Thermal modeling for greenhouse heating by using thermal curtain and an earth–air heat exchanger  

Microsoft Academic Search

In this paper, a thermal model for heating of greenhouse by using different combinations of inner thermal curtain, an earth–air heat exchanger, and geothermal heating has been developed. The analysis incorporates the study of thermal performance of three-zone greenhouse. The calculations have been made for a typical production greenhouse in southern part of Argentina; available climatic data has been used.

Ashish Shukla; G. N. Tiwari; M. S. Sodha

2006-01-01

303

DYNAMIC RESPONSE OF HEAT EXCHANGERS HAVING INTERNAL HEAT SOURCES. PART III  

Microsoft Academic Search

The dynamic response of the temperature of the heattransfer surface and ; the fluid-surface temperature difference in a heat exchanger having internal heat ; sources is presented. A general solution is presented for a transient resulting ; from an arbitrary time rate of change of heat generation starting from an ; arbitrary initial condition. The results are obtained by a

V. S. Arpaci; J. A. Clark

1959-01-01

304

Experimental Testing and Analytical Analysis of a Plastic Panel Heat Exchanger for Greenhouse Heating.  

National Technical Information Service (NTIS)

The performance of a plastic panel-type heat exchanger, suitable for greenhouse heating using low-grade (25 to 60 exp 0 C water) power plant reject heat, was investigated theoretically and experimentally. The theoretical analysis showed that a plastic pan...

M. Olszewski J. F. Thomas

1980-01-01

305

A direct contact heat exchanger with a submerged combustion chamber for water heating  

Microsoft Academic Search

A direct contact heat exchanger with a submerged combustion chamber has been developed for feasibility study. Efficiencies of over 90 percent have been measured based on the higher heating value of the propane fuel used. Recovery of latent heat of vaporization was also achieved. It is found that the system is feasible and of application value but further study is

M. A. Reissig; J. N. Chung

1984-01-01

306

Heat Transfer Enhancement of Spray Cooling on Flat Aluminum Tube Heat Exchanger  

Microsoft Academic Search

This study provides an experimental analysis on the heat transfer performance of a flat aluminum tube micro-channel heat exchanger with spray cooling. The effects of water spraying rate, air flow rate and relative humidity were investigated. The test results show that the heat transfer performance increased with increasing the water spraying rate but without the penalty of increased flow resistance

Chia-Wei Chen; Chien-Yuh Yang; Yuh-Tang Hu

2013-01-01

307

Dimensional analysis for the heat transfer characteristics in the corrugated channels of plate heat exchangers  

Microsoft Academic Search

Using the Buckingham Pi theorem, this study derives dimensionless correlations to characterize the heat transfer performance of the corrugated channel in a plate heat exchanger. The experimental data are substituted into these correlations to identify the flow characteristics and channel geometry parameters with the most significant influence on the heat transfer performance. Simplified correlations by omitting the factors with less

J. H. Lin; C. Y. Huang; C. C. Su

2007-01-01

308

Sludge, fuel degradation and reducing fouling on heat exchangers  

SciTech Connect

Brookhaven National Laboratory, under contract to the US Department of Energy, operates an oil heat research primarily to lower energy consumption in the 12 million oil heated homes in the US. The program objectives include: Improve steady state efficiency of oil heating equipment, Improve seasonal efficiencies, Eliminate or minimize factors which tend to degrade system performance. This paper provides an overview of the status of three specific projects which fall under the above objectives. This includes our fuel quality project, oil appliance venting and a project addressing efficiency degradation due to soot fouling of heat exchangers.

Butcher, T.; Litzke, Wai Lin; Krajewski, R.; Celebi, Y.

1992-02-01

309

Mechanical design of heat exchangers and pressure vessel components  

SciTech Connect

The twenty-two chapters in this book are prefaced by brief descriptions of the computer codes referenced or listed within the pages that follow. The first chapter, which contains an outline of the more accepted heat-exchanger types and basic design considerations, is followed by another outlining various design-stress criteria. The next twenty chapters contain considerable detailed information concerning the design and operation of heat exchangers. The authors devote 121 pages to one of the most important design considerations, flow-induced vibration. Another chapter is dedicated to methods of seismic analysis. The remaining chapters address mechanical and thermal design as well as manufacturing.

Singh, K.P.; Soler, A.I.

1984-01-01

310

Transient response of parallel and counterflow heat exchangers  

SciTech Connect

The analysis of the transient behavior of shell and tube heat exchangers has been carried out by many researchers. Compared with the finite-difference procedure, the method presented in this note can be used to calculate directly the transient responses at arbitrary values of z and x, without performing many-step calculations pertinent to the selected time and space steps. Being different from other analytical procedures that can only deal with the transient responses to a step input change, this semi-analytical method can be applied to predicting the transient behavior subject to arbitrary inlet temperatures is shell and tube heat exchangers with parallel or countercurrent flow.

Roetzel, W.; Xuan, Y. (Univ. der Bundeswehr Hamburg (Germany))

1992-05-01

311

Shell-and-tube heat exchangers in refrigeration. Part 3  

SciTech Connect

This article is a continuation of a discussion of shell-and-tube heat exchangers (S and T HX) in refrigeration applications. Part 1 (December 1996) covered the basics of sizing and selection. Part 2 (January 1997) dealt with their application as evaporators with liquid chillers. The flooded cooler, the direct expansion (DX) chiller, and the spray chiller were mentioned. This segment will address major design problems that must be solved for heat exchangers to meet the requirements of specific applications and will focus on the DX chiller.

Cole, R.A. [R.A. Cole and Associates, Champaign, IL (United States)

1997-12-01

312

Internal dust recirculation system for a fluidized bed heat exchanger  

DOEpatents

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.

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

1981-01-01

313

Development of a modular heat exchanger with integrated latent heat energy store  

NASA Astrophysics Data System (ADS)

Latent heat storage materials and appropriate heat exchangers for solar heating applications, such as house heating and domestic hot water production were investigated. The melting and freezing characteristics and the effects of thermal cycling on a total of 12 substances, including paraffins, fatty acids and salt hydrates, were investigated and their corrosive interaction with five conventional construction materials was determined. The poor thermal conductivity of the heat storage materials requires the development of a modular finned heat pipe heat exchanger with increased heat transfer characteristics. A cost analysis is provided and comparisons with hot water storage indicate that latent heat storage has the potential of becoming economically more attractive than the former for domestic hot water production.

Abhat, A.; Heine, D.; Heinisch, M.; Malatidis, N. A.; Neuer, G.

1981-02-01

314

A modular phase change heat exchanger for a solar oven  

SciTech Connect

A modular energy storing heat exchanger designed to use pentaerythritol for thermal storage (solid-solid phase change at 182 C) is tested in an oven by circulating heat transfer oil which is electrically heated in a manner to simulate a concentrating solar collector. Three efficiencies for heating the system under controlled and measured power input are determined - the heat exchanger efficiency, the efficiency of the heater with distribution lines, and the total system efficiency. Thermal energy retention times and cooking extraction times are determined, and along with the efficiencies, are compared with the results previously reported for a nonmodular heat exchanger. The modular configuration provides a highly improved extraction rate for cooking due to its wrap-around character and its increased surface-to-volume ratio. A full scale glass model of the copper tubing of the system is described and flow observations reported demonstrating how uniformly the parallel pumping branches perform and how trapped air pockets affect pumping power. A technique for measuring pumping power is described and its application to the system is quantified to show that less than 1 watt is required to circulate the heat transfer oil even when the system includes the solar collector and its longer connecting tubes.

Bushnell, D.L.; Sohi, M. (Northern Illinois Univ., DeKalb (United States))

1992-10-01

315

Subsurface environment database for application of ground heat exchanger system  

NASA Astrophysics Data System (ADS)

Ground heat exchanger system is economical and environmentally friendly technology and widely used in Europe and North America, while it is rarely used in Japan. One of the causes is relatively complex topography and geological structure in Japan in comparison with those in Europe and North America. Complex structures produce regional differences in subsurface thermal properties and temperature structure, leading to regional variation in efficiency of heat exchanger system. It is thus important to evaluate available subsurface heat energy through thermal response tests and/or numerical simulation and to design appropriate systems (depth and number of boreholes for heat exchange). Information on subsurface environment in target areas is necessary for evaluation of potential subsurface heat energy, but little information has been published. Center for Environmental Science in Saitama is a research institute established by a local government, Saitama prefecture, which is located on the north of Tokyo and has a population of over seven million. We have been collecting various subsurface environmental data in Saitama (e.g., lithological column data on over 10,000 boreholes). We have compiled the accumulated data and obtained new data (geological information, subsurface temperature distribution, and hydrogeological properties) to construct a database for application of ground heat exchanger systems in Saitama. It is important to estimate demand for heat energy in the target areas as well as available subsurface heat energy. We therefore compile meteorological data (air temperature and solar radiation) necessary for estimation for the demand and investigate regional variation in meteorological condition. We intend to disclose the database and research products using web GIS (geographic information system) in the future. It will assist spread of ground heat exchanger systems in the target areas. Investigation methods of subsurface environment survey and database construction can be applied to other areas. We present results of numerical simulation of ground heat exchanger system operation based on the database. The amount of available heat energy and influence on subsurface thermal environment vary by up to about 20 % within the study area depending on geological and meteorological conditions. Map of temperature measurement stations and numerical simulation considering with groundwater flow

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

2010-12-01

316

Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

Ungar, Eugene K.; Schunk, Richard G.

2011-01-01

317

Characterization of a mini-channel heat exchanger for a heat pump system  

NASA Astrophysics Data System (ADS)

In this paper a mini-channel aluminum heat exchanger used in a reversible heat pump is presented. Mini-channel finned heat exchangers are getting more and more interest for refrigeration systems, especially when compactness and low refrigerant charge are desired. Purpose of this paper was to characterize the mini-channel heat exchanger used as evaporator in terms of heat transfer performance and to study the refrigerant distribution in the manifold. The heat exchanger characterization was performed experimentally by means of a test rig built up for this purpose. It is composed of an air-to-air heat pump, air channels for the external and internal air circulation arranged in a closed loop, measurement sensors and an acquisition system. The overall heat transfer capacity was assessed. Moreover, in order to characterize the flow field of the refrigerant in the manifold of the heat exchanger, a numerical investigation of the fluid flow by means of CFD was performed. It was meant to evaluate the goodness of the present design and to identify possible solutions for the future improvement of the manifold design.

Arteconi, A.; Giuliani, G.; Tartuferi, M.; Polonara, F.

2014-04-01

318

A passive thermosyphon heat exchanger for residential solar installations  

NASA Technical Reports Server (NTRS)

The paper details the development of a thermosyphon water-to-air heat exchanger for residential solar applications. Modeling techniques used in the analysis of thermosyphon performance are included, as well as test results from laboratory-scale experiments. In addition, a description of the initial full-scale prototype is presented, along with experimental test results. Present areas of development are discussed, with an economic comparison of thermosyphon and forced convection heating systems also being included.

Franklin, J. L.; Saaski, E. W.; Hankins, J. D.

1977-01-01

319

Shell-and-plate-type heat exchangers for OTEC plants  

Microsoft Academic Search

New titanium, shell-and-plate type heat exchangers for ocean-thermal-energyconversion (OTEC) plants have been developed which include three different plate types (fluted, impinging, and porous-surface) for the evaporator and two kinds of plates (No. 1 and No. 2) for the condenser. Performance tests with fresh water show that the overall heat transfer coefficient U of the evaporator using the porous plate is

H. Uehara; H. Kusudu; M. Monde; T. Nakoaka; H. Sumitomo

1984-01-01

320

Thermal performance of a geofluid direct-contact heat exchanger  

Microsoft Academic Search

A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280°F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ratios which produced different boiling conditions. In this paper, the results of these experiments are analyzed on the basis of thermal performance.

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

1983-01-01

321

Modeling of cross-flow heat exchangers with viscoelastic fluids  

Microsoft Academic Search

The conduction–convection heat loss from a viscoelastic liquid, subjected to two-dimensional flow within the core of a cross-flow heat exchanger arrangement with a mixed or unmixed external fluid, is investigated with direct numerical simulations. A numerical algorithm based on the finite difference method is implemented in time and space with the Giesekus constitutive model for the viscoelastic liquids. The core-fluid

T. Chinyoka

2009-01-01

322

The Direct Contact Heat Exchanger: Experiences on Ice Slurry Production  

Microsoft Academic Search

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

Raksit Thitipatanapong; Bundit Limmeechokchai

323

Metal foams as compact high performance heat exchangers  

Microsoft Academic Search

Open-cell metal foams with an average cell diameter of 2.3 mm were manufactured from 6101-T6 aluminum alloy and were compressed and fashioned into compact heat exchangers measuring 40.0 mm×40.0 mm×2.0 mm high, possessing a surface area to volume ratio on the order of 10,000 m2\\/m3. They were placed into a forced convection arrangement using water as the coolant. Heat fluxes

K. Boomsma; D. Poulikakos; F. Zwick

2003-01-01

324

Numerical computation of 3D heat transfer in complex parallel heat exchangers using generalized Graetz modes  

NASA Astrophysics Data System (ADS)

We propose and develop a variational formulation dedicated to the simulation of parallel convective heat exchangers that handles possibly complex input/output conditions as well as connection between pipes. It is based on a spectral method that allows to re-cast three-dimensional heat exchangers into a two-dimensional eigenvalue problem, named the generalized Graetz problem. Our formulation handles either convective, adiabatic, or prescribed temperature at the entrance or at the exit of the exchanger. This formulation is robust to mode truncation, offering a huge reduction in computational cost, and providing insights into the most contributing structure to exchanges and transfer. Several examples of heat exchangers are analyzed, their numerical convergence is tested and the numerical efficiency of the approach is illustrated in the case of Poiseuille flow in tubes.

Pierre, Charles; Bouyssier, Julien; de Gournay, Frédéric; Plouraboué, Franck

2014-07-01

325

Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

326

Plastic heat exchangers for waste heat recovery. Final report  

SciTech Connect

Metallic corrosion is one of the major impediments to using the large amounts of heat available in flue and exhaust gases. Our approach is to develop plastic coatings to eliminate this corrosion problem and make this waste heat available economically. The advantages of plastics and their limitations in this application are discussed. Laboratory testing in an acid-condensing environment has been performed on numerous plastics and has identified several plastics with good potential as corrosion barriers. Polyphenylene sulfide, in particular, has resisted sulfuric acid attack for over 5000 hours and can be used at temperatures up to 300/sup 0/C.

Roach, P.D.; Holtz, R.E.

1983-09-01

327

Direct contact heat exchange for latent heat-of-fusion energy storage systems  

Microsoft Academic Search

A computational-experimental work is performed to assess the feasibility of the 'shot tower' latent heat of fusion energy storage concept. The shot tower system uses mutually immiscible heat-transfer-fluid\\/phase-change-material pairs of different density in such a way that both the heat transfer fluid and the phase change material move. It is shown that a shot-tower-type heat exchanger using water\\/paraffin and having

M. C. Nichols; R. M. Green

1978-01-01

328

A numerical study on heat transfer characteristics in a spray column direct contact heat exchanger  

Microsoft Academic Search

A reliable computational heat transfer model has been investigated to define the heat transfer characteristics of a spray\\u000a column direct contact heat exchanger, which is often utilized in the process involving counterflows for heat and mass transfer\\u000a operations. Most of the previous studies investigated are one-dimensional unsteady solutions based on rather fragmentary experimental\\u000a data. Development of a multidimensional numerical model

Yong Heack Kang; Nam Jin Kim; Byung Ki Hur; Chong Bo Kim

2002-01-01

329

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

NASA Astrophysics Data System (ADS)

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.

Srisawad, Kwanchanok; Wongwises, Somchai

2009-02-01

330

Radiative heat exchange in Czochralski crystal growth  

NASA Astrophysics Data System (ADS)

The effect of diffuse-gray radiation on the parametric sensitivity and stability of the Czochralski crystal growth was analyzed using a thermal-capillary model (TCM) which governs heat transfer in the system, the shapes of the melt/crystal and melt/gas interfaces, and the shape of the growing crystal. The entire model was solved by a finite-element analysis for simultaneous calculation of the temperature field and interface shapes either by Newton's method for the quasi-steady-state model or by implicit time integration for transient simulations. Proportional and integral feedback control strategies were demonstrated for the control of the crystal radius by incorporating a servo-control equation for the heater temperature into the dynamic simulation based on the TCM.

Atherton, L. J.; Derby, J. J.; Brown, R. A.

1987-07-01

331

Brief Review of Tube Fretting-Wear in Heat Exchangers.  

National Technical Information Service (NTIS)

Fretting-wear damage in heat exchangers is caused by the relative motion of vibrating tubes against the walls of tube-support holes. Understanding the effects of various parameters on wear will help designers minimize or avoid such damages. This report de...

P. L. Ko

1984-01-01

332

Model Order Reduction of a Heat Exchanger Model  

Microsoft Academic Search

A nonlinear PDAE model of a heat exchanger is described. A Krylov based moment matching method, balanced truncation, and Galerkin projection onto a POD basis are used for generating reduced order models of the nonlinear DAE obtained after discreti- sation in space, and the results are compared with those from a physically motivated lumping method.

K. Henrik; A. Olsson

333

Transient radiative heat exchange at the surface of the moon  

Microsoft Academic Search

The surface of the Moon is characterized as an evacuated particulate medium in which radiative heat exchange between solid surfaces plays a decisive role in determining the transient behavior of the apparent temperature. A simple model is developed which permits quantitative comparisons with lunar surface temperature variations, observed in the 8-12 micron band, both during a lunation and a lunar

D. F. Winter

1967-01-01

334

Fouling characteristics of compact heat exchangers and enhanced tubes.  

SciTech Connect

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.

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

1999-07-15

335

Control of marine biofouling in heat exchanger systems  

Microsoft Academic Search

A critical review is provided of biofouling hazards associated with heat exchanger surfaces in contact with seawater; mechanisms of biofouling formation, environmental factors affecting fouling and control measures. Available antifoulants include elastomer or plastic-based toxic coatings, copper alloys, and the application of chemicals, principally chlorine. 29 refs.

R. Mitchell; P. Benson

1981-01-01

336

Numerical Simulations of Particle Deposition in Metal Foam Heat Exchangers  

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

337

Simulation of the Heat Exchangers Dynamics in MATLAB&Simulink  

Microsoft Academic Search

Heat exchangers that transfer energy from flue gas to steam are important units of thermal power stations. Their inertias are often decisive for the design of the steam temperature control system. In this paper, the analysis and the simulation of the dynamics of the steam superheater are discussed. Superheater is simulated as a unit of a control loop that generates

PAVEL NEVRIVA; STEPAN OZANA; LADISLAV VILIMEC

338

The effectiveness of a spiral coil heat exchanger  

Microsoft Academic Search

An expression has been obtained for the effectiveness of a spiral coil heat exchanger (SCHE) which consists of a number of horizontal layers of spirally wound finned tubes. An experimental SCHE has been fabricated and tested in a closed-loop test set-up to obtain its effectiveness. The effect of the various design parameters on the effectiveness of the SCHE has been

N. E. Wijeysundera; J. C. Ho; S. Rajasekar

1996-01-01

339

Heat exchanger with leak detecting double wall tubes  

DOEpatents

A straight shell and tube heat exchanger utilizing double wall tubes and three tubesheets to ensure separation of the primary and secondary fluid and reliable leak detection of a leak in either the primary or the secondary fluids to further ensure that there is no mixing of the two fluids.

Bieberbach, George (Tampa, FL); Bongaards, Donald J. (Seminole, FL); Lohmeier, Alfred (Tampa, FL); Duke, James M. (St. Petersburg, all of, FL)

1981-01-01

340

Countercurrent direct contact heat exchange process and system  

Microsoft Academic Search

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

Wahl; Edward F; Frederic B. Boucher

1979-01-01

341

MAXIMIZING THREE-PHASE DIRECT-CONTACT HEAT EXCHANGER OUTPUT  

Microsoft Academic Search

Findings that maximize output performance of three-phase spray columns show that dramatic increases in total heat transfer can be achieved. Results from simulations are presented that show when the dispersed fluid is introduced into the exchanger at or near its saturation temperature, increases of approximately a half order of magnitude are possible. In some cases, reversals in previously reported trends

Richard A. Brickman; Robert F. Boehm

1994-01-01

342

Countercurrent direct contact heat exchange process and system  

Microsoft Academic Search

The invention discloses an apparatus and method for 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

E. F. Wahl; F. B. Boucher

1979-01-01

343

Application of direct contact heat exchangers in geothermal systems  

Microsoft Academic Search

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

I. Oliker

1977-01-01

344

Opportunities for heat exchanger applications in environmental systems  

Microsoft Academic Search

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

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

2000-01-01

345

Results of Damage Research on Corrosion Failures in Heat Exchangers  

Microsoft Academic Search

Based on damage research and corrosion experiments, an attempt is made to systematize failures of heat-exchanger lubes through different kinds of corrosion (with and without mechanical loading) from the cooling-water side. Various countermeasures are offered to prevent corrosion of the tubes. Since the stability of the protective layer is the main barrier against corrosive attack, indications are given of ways

P. Forchhammer

1984-01-01

346

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOEpatents

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.

Sohal, Manohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)

2005-12-20

347

Teaching Heat Exchanger Network Synthesis Using Interactive Microcomputer Graphics.  

ERIC Educational Resources Information Center

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)

Dixon, Anthony G.

1987-01-01

348

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOEpatents

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.

Sohal, Monohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)

2004-09-14

349

Power and refrigeration plants for minimum heat exchanger inventory  

Microsoft Academic Search

What has been accomplished to date on the question of how to minimize and allocate the heat exchanger inventory in power plants and refrigeration plants is summarized in a table. This table also highlights the three objectives of the present study. The first objective is to devise a much simpler model and analysis to reproduce in closed form Ibrahim et

A. Bejan

1993-01-01

350

Analysis of titanium\\/carbon steel heat exchanger fire  

Microsoft Academic Search

In the past fifteen years two serious titanium fires have occurred at scrap dealer facilities. Both incidents involved the cutting of titanium\\/carbon steel heat exchangers by scrap metal dealers. This paper reviews the properties of titanium and carbon steel under extreme conditions and the oxy-acetylene cutting process relevant to its potential for initiating titanium fires. The probable modes of propagation

Brenda A. Prine

1992-01-01

351

Laboratory measurements of a direct-contact heat exchanger  

Microsoft Academic Search

Evaluations of a 0.62 m (24 in.) diameter direct contact tower heat exchanger have been made. The tower is a test bed designed to evaluate direct contact processes that might be used in a salt stratified solar pond power plant. In the present application, commercial grade normal pentane is boiled while in direct contact with hot water, with the water

R. F. Boehn

1985-01-01

352

State of technology of direct contact heat exchanging  

Microsoft Academic Search

The state of technology development was assessed and the constraints to wider use of direct contact heat exchanger (DCHE) technology were evaluated. Many types of generic systems and end-use applications, both current and future were studied. Domestic and foreign experience with DCHE technology are compared, although the primary focus is on domestic experience. Twenty-two distinct applications of DCHE technology were

R. W. Vallario; D. E. Debellis

1984-01-01

353

Potential Heat Exchange Fluids for Use in Sulfuric Acid Vaporizers.  

National Technical Information Service (NTIS)

The testing of several candidate perfluorocarbon liquids for the direct fluid contact heat exchange with H2SO4 at about 330 C prior to high temperature decomposition in the oxygen release step of several thermochemical cycles for splitting water into hydr...

D. D. Lawson G. R. Petersen

1980-01-01

354

Potential heat exchange fluids for use in sulfuric acid vaporizers  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

355

Potential heat exchange fluids for use in sulfuric acid vaporizers  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

356

Acoustic resonance in heat exchanger tube banks. Second annual report  

Microsoft Academic Search

The study of the fluid mechanics of acoustic resonance in heat exchanger tube bundles continues. The previous work included review of data and theory, development of models for the acoustics of tube bundles, and construction of a wind tunnel and tube array model. In the present phase of the program, both the wind tunnel model and the analytical model were

1984-01-01

357

Acoustic Resonance in Heat Exchanger Tube Banks. Second Annual Report.  

National Technical Information Service (NTIS)

The study of the fluid mechanics of acoustic resonance in heat exchanger tube bundles continues. The previous work included review of data and theory, development of models for the acoustics of tube bundles, and construction of a wind tunnel and tube arra...

R. D. Blevins

1984-01-01

358

Two-Phase/Two-Phase Heat Exchanger Analysis.  

National Technical Information Service (NTIS)

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....

R. H. Kim

1992-01-01

359

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

NASA Technical Reports Server (NTRS)

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.

Greene, William D. (Inventor)

2008-01-01

360

Use of high performance plate heat exchangers in chemical and process industries  

Microsoft Academic Search

At present, plate heat exchangers constantly open up new application fields in the chemical, process, and allied industries due to their numerous advantages. The channel flow between individual plates is characterized by high turbulence induced at low flow velocities. Heat transfer coefficients are generally higher in plate heat exchangers than in conventional shell-and-tube heat exchangers. According to the nature of

Marcus Reppich

1999-01-01

361

Compact heat exchanger for refrigeration systems  

SciTech Connect

In combination with a vapor/compression refrigeration system, a defrosting apparatus for receiving mixed phase refrigerant emanating from the system evaporator outlet during system defrost, and transmitting only superheated gaseous refrigerant to the system compressor inlet, is described comprising: a cylindrical metal body having a preselected length, diameter and wall thickness, and top and bottom ends; a metal defrost tube means having a first tube end; a first metal end cap, fixedly attached to the bottom end of the body, for sealably enclosing the bottom end; a second metal end cap, fixedly attached to the top end of the body, for sealably enclosing the top end thereby forming, in cooperation with the first cap, a chamber therewithin; a first metal standpipe tube, passing through and fixedly attached to the second end cap, and extending a first preselected depth into the chamber, for receiving the mixed phase refrigerant from the evaporator outlet and transmitting the mixed phase refrigeration into the chamber, the mixed phase refrigerant absorbing the heat transmitted therein from the coil and transforming the mixed phase refrigerant into superheated low pressure refrigerant gas; and a second metal standpipe tube, passing through and fixedly attached to the second end cap, and extending a second preselected depth into the chamber, the first depth of the first standpipe being substantially greater than the second depth, for receiving and transmitting only the superheated refrigerant to the compressor inlet.

Warren, J.

1988-01-12

362

Heat exchanger efficiently operable alternatively as evaporator or condenser  

DOEpatents

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.

Ecker, Amir L. (Dallas, TX)

1981-01-01

363

Heat transfer in counterflow heat exchangers with helical turbulators  

Microsoft Academic Search

A 3D mathematical model has been developed to investigate the heat transfer augmentation in a circular tube with a helical turbulator. Glycol–water blends of various concentrations were used in the inner tube, and pure water was used in the outer tube. Changes in fluid physical properties with temperature were taken into account, and k–?,k-?, and large eddy simulations were developed

Piroz Zamankhan

2010-01-01

364

Performance and modeling of thermosyphon heat exchangers for solar water heaters  

Microsoft Academic Search

Determining the performance of indirect solar heating systems that use thermosyphon heat exchangers requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. In this paper, measured performance of a two-pass, tube-in-shell, double-wall heat exchanger is discussed in terms of modeling issues. Thermosyphon heat exchangers may operate in the developing, mixed convection regime where natural

S. D. Dahl; J. H. Davidson

1997-01-01

365

Brayton heat exchanger unit development program (alternate design)  

NASA Technical Reports Server (NTRS)

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).

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

1973-01-01

366

Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development  

NASA Technical Reports Server (NTRS)

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 to performance such as hydraulic diameter, heat exchanger effectiveness, ventilation gas mass flow rate and surface roughness. Using this tool, four test articles were designed and manufactured to map to a full MTSA subassembly (the adsorbent bed, the sublimation heat exchanger for cooling and the condensing ice heat exchanger for warming). The design mapping considered impacts due to CIHX geometry as well as subassembly impacts such as thermal mass and thermal resistance through the adsorbent bed. The test articles were tested at simulated PLSS ventilation loop temperature, moisture content and subambient pressure. Ice accumulation and melting were observed. Data and test observations were analyzed to identify drivers of the condensing ice heat exchanger performance. This paper will discuss the analytical models, the test article designs, and testing procedures. Testing issues will be discussed to better describe data and share lessons learned. Data analysis and subsequent conclusions will be presented.

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

2008-01-01

367

Concepts and realization of microstructure heat exchangers for enhanced heat transfer  

SciTech Connect

Microstructure heat exchangers have unique properties that make them useful for numerous scientific and industrial applications. The power transferred per unit volume is mainly a function of the distance between heat source and heat sink-the smaller this distance, the better the heat transfer. Another parameter governing for the heat transfer is the lateral characteristic dimension of the heat transfer structure; in the case of microchannels, this is the hydraulic diameter. Decreasing this characteristic dimension into the range of several 10s of micrometers leads to very high values for the heat transfer rate. Another possible way of increasing the heat transfer rate of a heat exchanger is changing the flow regime. Microchannel devices usually operate within the laminar flow regime. By changing from microchannels to three dimensional structures, or to planar geometries with microcolumn arrays, a significant increase of the heat transfer rate can be achieved. Microheat exchangers in the form of both microchannel devices (with different hydraulic diameters) and microcolumn array devices (with different microcolumn layouts) are presented and compared. Electrically heated microchannel devices are presented, and industrial applications are briefly described. (author)

Brandner, J.J.; Anurjew, E.; Bohn, L.; Hansjosten, E.; Henning, T.; Schygulla, U.; Wenka, A.; Schubert, K. [Forschungszentrum Karlsruhe, Institute for Micro Process Engineering IMVT, P.O. Box 3640, DE-76021 Karlsruhe (Germany)

2006-08-15

368

Simultaneous derivation of clothing-specific heat exchange coefficients.  

PubMed

Clothing adds resistance to heat exchange between the wearer and the environment. If clothing-specific heat exchange coefficients are known, a combined rational/empirical approach can be used to describe thermal exchange between clothed humans and the environment. However, during exercise these coefficients--typically calculated using thermal manikins--change, primarily due to wetting of the fabric during intense sweating and body movement. A procedure is described that allows for the simultaneous determination of both total insulation (IT) and resistance to water vapor permeation (Re) on exercising clothed subjects without the need to directly measure skin water vapor pressure or continuously weigh the subjects. Two tests are performed by each subject in each clothing ensemble. In one test, ambient water vapor pressure (Pa) is systematically increased in stepwise fashion while dry-bulb temperature (Tdb) is held constant; in the second test protocol Pa is held constant while Tdb is increased. Heat exchange data are collected at the time at which core temperature is forced out of equilibrium by the environment (according to the assumption that heat production is balanced by heat loss immediately prior to this critical environmental limit). Previous studies using similar approaches have typically estimated IT a priori and used this value in the subsequent derivation of Re for each clothing ensemble or condition tested. In the proposed method, IT and Re are derived from the solution of two simultaneous equations based on heat balance data from both tests. This paper describes and critiques this methodology via an error analysis, and compares the coefficients obtained with those from similar trials using other physiological and nonphysiological approaches. PMID:8450734

Kenney, W L; Mikita, D J; Havenith, G; Puhl, S M; Crosby, P

1993-02-01

369

'Snow White' Trench After Scraping  

NASA Technical Reports Server (NTRS)

This view from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows the trench informally named 'Snow White.' This image was taken after a series of scrapings by the lander's Robotic Arm on the 58th Martian day, or sol, of the mission (July 23, 2008). The scrapings were done in preparation for collecting a sample for analysis from a hard subsurface layer where soil may contain frozen water.

The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide and about 60 centimeters (24 inches) long.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

2008-01-01

370

Thermoacoustics with idealized heat exchangers and no stack.  

PubMed

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. PMID:12083198

Wakeland, Ray Scott; Keolian, Robert M

2002-06-01

371

Proceedings of the DOE/Advanced Heat Exchangers Program Review. Summary report  

SciTech Connect

Semiannual review meetings of the USDOE`s Advanced Heat Exchanger Program with the objective of reviewing ongoing and recently completed project activities. Personnel from industrial contractors and National Laboratories present technical aspects of their projects. The projects deal with high temperature heat exchangers for waste heat recuperation and process heat exchange and other areas such as materials performance and heat transfer enhancement. Topics presented are high pressure heat exchangers, ceramic heat exchangers, enhanced tubes, and materials studies to include silicon carbide whiskers and alumina. (GHH)

Not Available

1992-02-01

372

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

Microsoft Academic Search

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

Yujin Nam; Ryozo Ooka; Suckho Hwang

2008-01-01

373

The CEBAF Beam Scraping Monitor  

SciTech Connect

The Beam Scraping Monitor (BSM) is used to detect small amounts of beam loss in Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF). The BSM acts as an early warning system that alerts CEBAF operators when the beam loss exceeds 10 to 20 nA. This allows the CEBAF operators to adjust the beam orbit before beam loss reaches the Beam Current Monitor (BCM) system threshold (presently 2 mu-A) and shuts down the accelerator. The reference oscillators of four digital signal processing (DSP) lock-in amplifiers are connected to two vertical and two horizontal corrector magnets in the CEBAF injector. These magnets excite transverse oscillations on the electron beam that are significantly smaller than the beam size, producing a negligible effect on beam delivery. To cover the entire accelerator enclosure, the correctors of each plane are separated by pi/2 betatron phase advance.When the electron beam approaches the beam enclosure some electrons get scraped off, causing an amplitude modulation of the beam current at the reference oscillator frequencies. This is picked up by the BCM cavities and relayed to the lock-in amplifiers for synchronous integrated detection. The lock-in amplifiers then transmit the scraping information serially to a LINUX computer running EPICS Portable Channel Access Server software.

T. Allison; V. Lebedev; C. Piller; J. Sage; M. Wiseman

2001-06-01

374

Direct contact heat exchange for latent heat-of-fusion energy storage systems  

Microsoft Academic Search

Rudimentary computational and experimental results are presented for a thermal energy storage process based on a novel counter current, direct contact heat exchange concept, the shot tower. The process uses a phase change material and a mutually immiscible heat transfer fluid. A two-tank storage system is used, one each for cool and hot phase change material, respectively. In use, the

M. C. Nichols; R. M. Green

1977-01-01

375

Design and Fabrication of a Stirling Engine Heat Exchanger Module with an Integral Heat Pipe.  

National Technical Information Service (NTIS)

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 ...

J. G. Schreiber

1988-01-01

376

Evaporation and Condensation Heat Transfer Performance of Flammable Refrigerants in a Brazed Plate Heat Exchanger.  

National Technical Information Service (NTIS)

Average Nusselt numbers were measured for R22, R290, R290/600a, and R32/152a undergoing evaporation and condensation in a brazed plate heat exchanger. The refrigerants experienced wavy, stratified flow at low heat and mass fluxes, 1.3 kW/sq m to 8.3 kW/sq...

S. C. Palmer W. V. Payne P. A. Domanski

2000-01-01

377

Experiment on a continuous heat regenerative adsorption refrigerator using spiral plate heat exchanger as adsorbers  

Microsoft Academic Search

Spiral plate heat exchangers were proposed to be used as adsorbers, and a prototype heat regenerative adsorption refrigerator using the activated carbon-methanol pair was developed and tested. The adsorption system using 12 kg activated carbon has a cycle time of 40 min., meanwhile 14 kg ice per day was made.

R. Z. Wang; J. Y. Wu; Y. X. Xu; Y. Teng; W. Shi

1998-01-01

378

Convective heat transfer from molten salt droplets in a direct contact heat exchanger  

NASA Astrophysics Data System (ADS)

This paper presents a new predictive model of droplet flow and heat transfer from molten salt droplets in a direct contact heat exchanger. The process is designed to recover heat from molten CuCl in a thermochemical copper-chlorine (Cu-Cl) cycle of hydrogen production. This heat recovery occurs through the physical interaction between high temperature CuCl droplets and air. Convective heat transfer between droplets and air is analyzed in a counter-current spray flow heat exchanger. Numerical results for the variations of temperature, velocity and heat transfer rate are presented for two cases of CuCl flow. The optimal dimensions of the heat exchanger are found to be a diameter of 0.13 m, with a height of 0.6 and 0.8 m, for 1 and 0.5 mm droplet diameters, respectively. Additional results are presented and discussed for the heat transfer effectiveness and droplet solidification during heat recovery from the molten CuCl droplets.

Jaber, O.; Naterer, G. F.; Dincer, I.

2010-10-01

379

Experimental Investigation of Ice Phase Change Material Heat Exchangers  

NASA Technical Reports Server (NTRS)

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.

Leimkuehler, Thomas O.; Stephan, Ryan A.

2011-01-01

380

Heat transfer enhancement in fin-tube heat exchangers by winglet type vortex generators  

NASA Astrophysics Data System (ADS)

Numerical investigations of the flow structure and heat transfer enhancement in a channel with a built-in-circular tube and a winglet type vortex generator are presented. The geometrical configuration represents an element of a gas-liquid fin-tube crossflow heat exchanger. In the absence of the winglet type vortex generator, relatively little heat transfer takes place in the downstream of the circular tube which is a recirculation region with low velocity fluid. However, in the presence of a winglet type longitudinal vortex generator in the wake region behind the cylinder, heat transfer in this region can be enhanced as high as 240%. Results show a marked increase in overall channel heat transfer. The enhancement shows great promise in reducing the size of the heat exchangers.

Biswas, G.; Mitra, N. K.; Fiebig, M.

1994-01-01

381

Use of a Fluidized Bed Heat Exchanger to Improve the Performance of a Heat Pump. Final Report.  

National Technical Information Service (NTIS)

The outdoor evaporator heat exchanger of a York 60,000 Btu heat pump in the heating mode was replaced with a fluidized bed heat exchanger. Air temperature control was achieved by recirculating the conditioned air from both the evaporator and condenser hea...

R. G. Sarubbi J. C. Chen

1981-01-01

382

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

SciTech Connect

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

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

2002-02-26

383

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

PubMed

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

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

2014-03-01

384

Hydromechanics and heat and mass exchange in weightlessness (Russian book): Table of contents  

NASA Technical Reports Server (NTRS)

The table of contents is given for a book on hydromechanics and heat and mass exchange in weightlessness. The book covers such subjects as hydromechanics, convection and heat and mass exchange, and technological experiments and complicated systems.

Avduyevskiy, V. S.; Poleshayev, V. I.

1983-01-01

385

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

NASA Technical Reports Server (NTRS)

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.

Kraft, G. A.

1975-01-01

386

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

PubMed

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

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

387

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

388

Auxiliary hot water boiler with solar heater and heat exchange system  

Microsoft Academic Search

An auxiliary hot water boiler and heat exchange system including a solar heater and adapted for use with a conventional, domestic closed loop hot water heating system and a conventional, domestic hot water heater is described. A first heat exchanger connected with a solar heat absorber provides a primary source of heat for a supply of water in the boiler.

Taschuk

1981-01-01

389

Experimental study of thermo-hydraulic and fouling performance of enhanced heat exchangers  

Microsoft Academic Search

The present study investigated the effect of two tube inserts (wire coil and wire mesh) on the heat transfer enhancement, pressure drop and mineral salts fouling mitigation in tube of a heat exchanger. A 3\\/4-in. tube that is heated by band heaters, is used which simulated a tube of heat exchanger. Working fluid is water with certain quality. The heat

H. Pahlavanzadeh; M. R. Jafari Nasr; S. H. Mozaffari

2007-01-01

390

The tribological behavior of tube supports in helium heat exchangers  

SciTech Connect

A closed-cycle gas turbine plant for high-temperature gas-cooled reactor application contains a number of heat exchangers for low to medium temperatures (up to 500/sup 0/C). The tubes of these heat exchangers are held in multiple spacers. Since thermal expansions lead to relative motions between tubes and spacers, a predictable tribological behavior of this sliding pair is important. The search for a low-cost treatment to achieve good tribological properties has led to manganese phosphate conversion layers on ferritic steel. Laboratory tests in helium with representative tube/spacer configurations have shown very small wear rates, complete absence of scuffing, and moderate and predictable coefficients of friction. Mechanical testing of phosphated tube material did not reveal any detrimental influence from the phosphate treatment. This work was performed under the joint German/Swiss development agreement for the helium high-temperature turbine project, HHT.

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

1984-09-01

391

Use of a heat exchanger in liver transplantation.  

PubMed

Of the first 16 patients who underwent orthoptic liver transplantation, 81% were observed to be hypothermic at termination of bypass (x = 34.5 degrees C, n = 16). In response, an in-line heat exchanger was added to the bypass circuit. Subsequently, 72% of the next 11 patients terminated bypass normothermic (x = 38.2 degrees C, n = 11). By removing from the sample those patients who incurred low blood flows, 100% of the patients terminated bypass normothermic (x = 38.2 degrees C, n = 8). At temperatures of 30-33 degrees C cardiac arrhythmias have been observed. Hypothermia has been documented to cause thrombocytopenia and neutropenia which can lead to blood loss. These low counts are only partially reversible with platelet infusion and white blood cells (WBC). The use of an in-line heat exchanger during liver transplantation is essential in preventing hypothermia in our experience. PMID:10149512

Butler, K T; Raskin, S A; Whisennand, H H; Lowell, W R; Gay, J R; Cornelius, G F

1991-01-01

392

Condensing Heat Exchanger Concept Developed for Space Systems  

NASA Technical Reports Server (NTRS)

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.

Hasan, Mohammad M.; Nayagam, Vedha

2005-01-01

393

Tritium permeation losses in HYLIFE-II heat exchanger tubes  

SciTech Connect

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.

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

1990-01-01

394

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

395

Experimental and Predicted Overall Heat-Transfer Coefficients for Four Residential Air-to-Air Heat Exchangers.  

National Technical Information Service (NTIS)

Experimental values of the overall heat transfer coefficient are obtained from measured values of the effectiveness for four residental size air-to-air heat exchangers. Predictions of the overall heat transfer coefficient are made from available informati...

R. A. Seban A. Rostami M. Zarringhalam

1981-01-01

396

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

Microsoft Academic Search

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

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

2001-01-01

397

Optimality of heat-exchange systems and selective decomposition of process fluxes  

Microsoft Academic Search

Optimally reliable chemical process systems are synthesized by generating optimal subsystems made up of optimal units. Optimal\\u000a resource-saving heat-exchange systems (HES) are formed by generating heat-exchange units equipped with optimal heat-exchange\\u000a vessels. The heat-exchange units are optimized by selecting the shell and tube dimensions, the number of tubes, the number\\u000a of passes in the tube space, and the number of

R. G. Gareev

1997-01-01

398

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

Microsoft Academic Search

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

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

2006-01-01

399

Thermal Performance Study of a Prototype Multiport Heat Exchanger  

NASA Astrophysics Data System (ADS)

Great efforts have been made to investigate the thermal performance and fluid flow behaviour in Minichannel Heat Exchangers (MICHX), however, the examination of air side in a multiport serpentine slab heat exchanger is rare. In the current investigation, experiments were conducted on air heating via a prototype multiport MICHX. Hot DI-water at different mass flow rates and a constant inlet temperature of 70°C was passed through the channels. The water side Reynolds numbers were varied from 255 to 411. The airside Reynolds numbers were calculated based on the free mean stream velocity and varied from 1750 to 5250, while, the air inlet temperatures were in the range of 22.5°C to 34.5°C. The effects of dimensional parameters, such as Reynolds number, Nusselt number, Prandtl number, Brinkman number, and Dean number on the heat transfer performance were investigated. The effect of the serpentine on the enhancement of DI water thermal performance behaviour was studied. Heat transfer correlations were established and compared to the results in the open literature.

Fotowat, Shahram

400

Heat exchange apparatus and process for rotary kilns  

SciTech Connect

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.

De Beus, A.J.

1987-06-30

401

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

DOEpatents

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.

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

1981-11-24

402

The effectiveness of a spiral coil heat exchanger  

SciTech Connect

An expression has been obtained for the effectiveness of a spiral coil heat exchanger (SCHE) which consists of a number of horizontal layers of spirally wound finned tubes. An experimental SCHE has been fabricated and tested in a closed-loop test set-up to obtain its effectiveness. The effect of the various design parameters on the effectiveness of the SCHE has been studied.

Wijeysundera, N.E.; Ho, J.C.; Rajasekar, S. [National Univ. of Singapore (Singapore). Dept. of Mechanical and Production Engineering] [National Univ. of Singapore (Singapore). Dept. of Mechanical and Production Engineering

1996-09-01

403

Geothermal direct-contact heat exchange. Final report  

Microsoft Academic Search

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

Sims

1976-01-01

404

Liquid-liquid direct contact heat exchanger for solar application  

Microsoft Academic Search

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as\\u000a dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the\\u000a top of the column. When it is closely connected with a solar collector which uses water as its working fluid,

In Seak Kang; Chong Bo Kim; Won Gee Chun

1995-01-01

405

Method for manufacturing a disassemblable core heat exchanger  

SciTech Connect

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

Sleep, R.E. Jr.

1986-08-26

406

A new reagent method for descaling heat-exchanging equipment  

Microsoft Academic Search

Corrosion and electrochemical studies of metallic materials (steel, St2, 08Kh22N6T, 12KhI8NIOT, copper M3, brass L062~I, aluminum ADI, titanium VT-O) applicable fo~ fabrication of heat-exchanging equipment were made to explore the scope of industrial use of the new reagent method. The tests were carried out on a special setup (Fig. i). The extent of carbonate scale removal and the corrosion rate

L. A. Luchinina; T. D. Konovalova; F. K. Davlet'yarova

1986-01-01

407

Characterization of HEM silicon for solar cells. [Heat Exchanger Method  

NASA Technical Reports Server (NTRS)

The Heat Exchanger Method (HEM) is a promising low-cost ingot casting process for material used for solar cells. This is the only method that is capable of casting single crystal ingots with a square cross section using a directional solidification technique. This paper describes the chemical, mechanical and electrical properties of the HEM silicon material as a function of position within the ingot.

Dumas, K. A.; Khattak, C. P.; Schmid, F.

1981-01-01

408

Effect of Lewis number on wet surface heat exchangers  

NASA Astrophysics Data System (ADS)

A linearized approximate modified analogy theory of wet surface heat exchangers, was developed which predicts the effect of Lewis number more accurately, by introducing modified transfer coefficients, wet bulb depression and wet bulb temperature. A linear approximate model of wet surface heat exchangers is adopted and the equations of the model are rearranged with approximations to two independent sets of equations for modified wet bulb depression and temperature. Each set has been solved previously in published solutions for dry bulb temperature in dry surface heat exchangers, giving modified wet bulb and humidifying efficiencies. The humidifying and wet bulb efficiencies are then calculated using equations derived from the modified wet bulb depression and temperature definitions. An exact finite difference solution, of the basic equations has been used here and compared with the current theory. The comparison showed that for a cross-flow cooling tower and a evaporative cooler, the modified analogy theory is in better agreement for effective Lewis numbers between 0.50 and 3.0.

Zafar, Mubashar

1987-10-01

409

Particle-surface interactions in heat exchanger fouling  

SciTech Connect

The problem of fouling is of vital importance to heat exchanger efficiency and should be considered during the design phase of the heat exchanger. The purpose of the present paper is to introduce a novel method to aid in the evaluation of the various parameters that affect the fouling phenomenon. The method considers the particle-surface interaction from the energy balance at the point of impaction and takes into consideration the material properties of the particle and surface as well as the effect of the surrounding flow field on the particle movement and impaction. The calculated deposition flux is used to form the deposit evolution in time considering the removal mechanisms resulting from fluid shear stress and the eroding impacts of the particles. The model is validated against experimental measurements of particle deposition from a two phase flow of hot gases around a circular cylinder. The experimentally measured flow field around a staggered tube bundle is also predicted and a fouling analysis is performed regarding the validity of fouling studies in scaled down model configurations. It is concluded that the actual dimensions of the heat exchanger configuration are of vital importance to its fouling behavior and scaling laws are difficult to apply.

Bouris, D.; Bergeles, G. [National Technical Univ. of Athens (Greece)

1996-09-01

410

Optimal cleaning policies in heat exchanger networks under rapid fouling  

SciTech Connect

This paper addresses the problem of short-term cleaning scheduling in a special class of heat-exchanger networks (HENs). A salient characteristic of this problem is that the performance of each heat exchanger decreases with time and can then be restored to its initial state by performing cleaning operations. Because of its practical importance, a specific problem has been considered here involving decaying equipment performance due to milk fouling. A mixed-integer nonlinear-programming (MINLP) model is first presented incorporating general fouling profiles. This model is then linearized to a tight mixed-integer linear-programming (MILP) model which can be solved to global optimality. A detailed objective function is used to account for cleaning cost and energy requirements. The formulations can model serial and parallel HENs as well as network arrangements arising from the combination of these basic cases. The optimization algorithm determines simultaneously: (1) the number of cleaning operation tasks required along with their corresponding timings and (2) the optimal utility utilization profile over time. A number of complex heat-exchanger networks examples are presented to illustrate the applicability of the proposed models together with comparative performance results between the MINLP and MILP models.

Georgiadis, M.C.; Papageorgiou, L.G.; Macchietto, S.

2000-02-01

411

Fouling of HVAC fin and tube heat exchangers  

SciTech Connect

Fin and tube heat exchangers are used widely in residential, commercial and industrial HVAC applications. Invariably, indoor and outdoor air contaminants foul these heat exchangers. This fouling can cause decreased capacity and efficiency of the HVAC equipment as well as indoor air quality problems related to microbiological growth. This paper describes laboratory studies to investigate the mechanisms that cause fouling. The laboratory experiments involve subjecting a 4.7 fins/cm (12 fins/inch) fin and tube heat exchanger to an air stream that contains monodisperse particles. Air velocities ranging from 1.5-5.2 m/s (295 ft/min-1024 ft/min) and particle sizes from 1--8.6 {micro}m are used. The measured fraction of particles that deposit as well as information about the location of the deposited material indicate that particles greater than about 1 {micro}m contribute to fouling. These experimental results are used to validate a scaling analysis that describes the relative importance of several deposition mechanisms including impaction, Brownian diffusion, turbophoresis, thermophoresis, diffusiophoresis, and gravitational settling. The analysis is extended to apply to different fin spacings and particle sizes typical of those found in indoor air.

Siegel, Jeffrey; Carey, Van P.

2001-07-01

412

Heat exchanger bypass system for an absorption refrigeration system  

DOEpatents

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.

Reimann, Robert C. (Lafayette, NY)

1984-01-01

413

All-metal, compact heat exchanger for space cryocoolers  

NASA Astrophysics Data System (ADS)

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.

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

1990-11-01

414

All-metal, compact heat exchanger for space cryocoolers  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

415

Update on Modular Laser Launch System and Heat Exchanger Thruster  

NASA Astrophysics Data System (ADS)

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.

Kare, Jordin T.

2011-11-01

416

Modeling of Sulfuric Acid Condensation on Heat Exchanger Cooling Fins  

NASA Astrophysics Data System (ADS)

Sulfuric acid corrosion on metallic heat exchanger cooling fins can cause serious blockage problem and stop the normal operation of heat exchangers. Corrosion rates are strongly dependent on surface film pH value. Therefore, a multi-physics computational framework was developed to predict the liquid film formed on solid surface and the pH distribution. Such a model can be used for better understanding of acid condensation from multi-species system. In this work, first, from S to H2SO4, formation of sulfuric acid in gas phase during combustion and cooling process was investigated with detailed chemistry mechanisms. The amount of SO2 and SO3 that plays important role in acid condensation process was calculated. Then, multi-component condensation process was modeled to produce a liquid film of acid and water solution condensed on solid surface that has low temperature. pH value was obtained based on the concentration of the acid. The above work provides critical information for corrosion analysis for heat exchangers.

Li, Xiaobai; Cook, David

2011-11-01

417

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

Microsoft Academic Search

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

J. McGrew; E. Jules

1961-01-01

418

Test and Development Program for Closed-Cycle OTEC Heat Exchangers  

Microsoft Academic Search

The Argonne Heat Exchanger Test Facility was constructed to test promising designs for OTEC heat exchangers. The facility has a nominal rating of 1 megawatt thermal and comprises separate loops for warm water, cold water, and ammonia. Since 1978 a total of 21 tests have been carried out on 13 different heat exchangers. Much valuable information has been generated. Future

David L. Hillis; Anthony Thomas

1981-01-01

419

Condensing heat exchanger microbial growth and control study-phase 2  

Microsoft Academic Search

The Space Station Temperature and Humidity Control Condensing Heat Exchangers will be utilized to collect and remove atmospheric water vapor generated by the metabolic and hygienic activity of crew members. The porous hydrophillic coating within the heat exchangers will always be wet. Cabin air will continuously flow through the heat exchangers during system operation which makes them a potential site

R. W. Marsh; M. E. Caron; C. Metselaar; J. Steele

1993-01-01

420

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

Microsoft Academic Search

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

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

1983-01-01

421

Dynamic simulation of accidental closure of intermediate heat exchanger isolation valve in a pool type LMFBR  

Microsoft Academic Search

In a pool type liquid metal cooled fast breeder reactor (LMFBR), core and other internals such as pumps, heat exchangers are immersed in a pool of sodium. Heat exchange from primary sodium circuit (pool) to secondary sodium circuit (loop) is through four intermediate heat exchangers (IHX) immersed in primary sodium pool. Each IHX is provided with a sleeve valve at

K. Natesan; N. Kasinathan; K. Velusamy; P. Selvaraj; P. Chellapandi; S. C. Chetal

2011-01-01

422

Experiment and Economic Analysis of an Air/Molten Salt Direct-Contact Heat Exchanger.  

National Technical Information Service (NTIS)

Direct-contact heat exchange (DCHX) has several advantages over conventional finned-tube heat exchangers. Without the intervening tube wall, thermal resistance is lower and fouling of the heat-exchange surface is not a problem. Intimate mixing of the two ...

M. S. Bohn

1983-01-01

423

Heat Storage Characteristics of Latent-Heat Microcapsule Slurry Using Hot Air Bubbles by Direct-Contact Heat Exchange  

NASA Astrophysics Data System (ADS)

This study deals with the heat storage characteristics of latent-heat microcapsule slurry consisting of a mixture of fine microcapsules packed with latent-heat storage material and water. The heat storage operation for the latent-heat microcapsules was carried out by the direct-contact heat exchange method using hot air bubbles. The latent-heat microcapsule consisted of n-paraffin as a core latent-heat storage material and melamine resin as a coating substance. The relationship between the completion time of latent-heat storage and some parameters was examined experimentally. The nondimensional correlation equations for temperature efficiency, the completion time period of the latent-heat storage process and variation in the enthalpy of air through the microcapsule slurry layer were derived in terms of the ratio of microcapsule slurry layer height to microcapsule diameter, Reynolds number for airflow, Stefan number and modified Stefan number for absolute humidity of flowing air.

Inaba, Hideo; Horibe, Akihiko; Kim, Myoung-Jun; Tsukamoto, Hirofumi

424

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

NASA Astrophysics Data System (ADS)

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

Novosád, Jan; Dvo?ák, Václav

2014-03-01

425

Heat exchangers and thermal energy storage concepts for the off-gas heat of steelmaking devices  

NASA Astrophysics Data System (ADS)

The fluctuating thermal emissions of electric arc furnaces require energy storage systems to provide downstream consumers with a continuous amount of thermal energy or electricity. Heat recovery systems based on thermal energy storage are presented. A comparison of different thermal energy storage systems has been performed. For the purpose, suitable heat exchangers for the off-gas heat have been developed. Dynamic process simulations of the heat recovery plants were necessary to check the feasibility of the systems and consider the non-steady-state off-gas emissions of the steelmaking devices. The implementation of a pilot plant into an existing off-gas duct of an electric arc furnace was required to check the real behavior of the heat exchanger and determine suitable materials in view of corrosion issues. The pilot plant is presented in this paper.

Steinparzer, T.; Haider, M.; Fleischanderl, A.; Hampel, A.; Enickl, G.; Zauner, F.

2012-11-01

426

Electrostatic enhancement of heat transfer in a gas-to-gas heat exchanger  

NASA Astrophysics Data System (ADS)

This is the final report on the last phase of a four-year GRI-sponsored experimental effort on heat transfer enhancement in gas-to-gas heat exchangers utilizing the electrostatic (or electrohydrodynamic, EHD) technique. The feasibility of the technique and the role of various controlling parameters for basic pipe flows and in a double-pipe heat exchanger were addressed in the first three phases of the project. In the current, and last, phase the feasibility of the electrostatic technique as a compound heat transfer augmentation methodology and its use in multi-tube heat exchangers was investigated. The compound enhancement experiments were performed on a commercially available finned tube by performing experiments on a micro-finned tube in the presence of electric field. Next, to address some of the practical problems that may be associated with the EHD technique, a multi-tube shell-and-tube heat exchanger was designed, fabricated, and experimentally tested. It is demonstrated that the EHD effect when used in conjunction with a low-fin or enhanced tube can yield additional enhancements to the already enhanced configuration as much as 80 percent in the present experiments technique.

Ohadi, M. M.; Ansari, A. I.

1992-07-01

427

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

SciTech Connect

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

Not Available

1993-11-01

428

Technical and economic evaluation of a solid-particle\\/air direct-contact heat exchanger  

Microsoft Academic Search

A conceptual design of a solid-particle\\/air heat exchanger system is presented including a multistage fluidized-bed heat exchanger, solid-particle feeders and defeeders, and cyclones. The system is designed for 100°C solid particles that heat air at 10 atm at a 100-MW heat rate. This type of heat exchanger could be part of a solar thermal central receiver system that uses solid

H. J. Green; C. M. Leboeuf; M. S. Bohn

1986-01-01

429

A probabilistic model of a porous heat exchanger  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

430

Abyssal plains heat exchange could explain global deficit  

NASA Astrophysics Data System (ADS)

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.

Schultz, Colin

2012-07-01

431

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

NASA Astrophysics Data System (ADS)

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.

Karaki, S.; Brothers, P.

1980-06-01

432

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

NASA Technical Reports Server (NTRS)

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.

Olson, Douglas A.; Glover, Michael P.

1990-01-01

433

Natural convection heat exchangers for solar water heating systems. Technical progress report, October 1, 1995--November 30, 1995  

SciTech Connect

The goals of this project are: (1) to develop guidelines for the design and use of thermosypohon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger.

Davidson, J.H.

1998-06-01

434

Natural convection heat exchangers for solar water heating systems. Technical progress report, April 1, 1995--May 31, 1995  

SciTech Connect

The goals of this project are: (1) to develop guidelines for the design and use of thermosypohon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger.

Davidson, J.H.

1998-06-01

435

Natural convection heat exchangers for solar water heating systems. Technical progress report, February 1, 1996--March 31, 1996.  

National Technical Information Service (NTIS)

This progress report describes the thermodynamic testing and modeling of a thermosyphon heat exchanger used in solar water heating systems. Testing of a four tube-in-shell thermosyphon heat exchanger was performed in two parts. The first portion of the te...

J. H. Davidson

1998-01-01

436

Heat treatment of fluid foods in a shell and tube heat exchanger: Comparison between smooth and helically corrugated wall tubes  

Microsoft Academic Search

Fluid foods are often subjected to thermal treatment inside surface heat exchangers. Besides the need for high heat transfer performance, also low friction losses and easy cleaning and sanitizing properties of the surface are imperative. In food process industry these requirements are often met by the shell and tube heat exchanger equipped with helically corrugated walls.The present work concerns convective

S. Rozzi; R. Massini; G. Paciello; G. Pagliarini; S. Rainieri; A. Trifirò

2007-01-01

437

Heat transfer enhancement mechanisms in inline and staggered parallel-plate fin heat exchangers  

Microsoft Academic Search

Heat transfer enhancement mechanisms and performance of parallel-plate fin heat exchangers are studied. Geometry effects such as finite fin thickness and inline vs staggered arrangements have been investigated. The time-dependent flow behavior due to vortex shedding has been taken into consideration by solving unsteady equations in two-dimensions. Companion steady symmetrized flow calculations have also been performed to identify the effect

L. W. Zhang; S. Balachandar; D. K. Tafti; F. M. Najjar

1997-01-01

438

Flow-induced vibration analysis of conical rings used for heat transfer enhancement in heat exchangers  

Microsoft Academic Search

In the present work, flow-induced vibration characteristics of conical-ring turbulators used for heat transfer enhancement in heat exchangers are investigated experimentally. The conical-rings, having 10, 20 and 30 mm pitches, are inserted in a model pipe-line through which air is passed as the working fluid. Vortex-shedding frequencies and amplitude are determined and St-Re, Prms-Re variations are presented graphically. Flow-acoustic coupling

Kenan Yakut; Bayram Sahin

2004-01-01

439

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

Microsoft Academic Search

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

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

2002-01-01

440

Investigation of heat exchanger flow arrangement on performance and cost in a geothermal binary cycle  

Microsoft Academic Search

The performance of an idealized geothermal binary-fluid-cycle energy conversion system is shown to be a function of the temperatures of brine and working fluid leaving the heat exchanger. System power output, heat exchanger area required and initial well and heat exchanger costs are determined for counterflow, single and multi-pass parallel-counterflow exchangers. Results are presented graphically as functions of the brine

W. H. Giedt

1976-01-01

441

Effects of Characteristics of Heat Exchangers on the Performance of a Heat Pump Cycle using NARBs  

NASA Astrophysics Data System (ADS)

COP of a heat pump using nonazeotropic refrigerant blends(NARBs) of R22 and R114 is calculated under the conditions that the heat pump thermal output and the inlet and outlet temperatures of the heat sink and source water are given. Heat transfer characteristics of the condenser and evaporator are either given as FK-parameters, which are the products of the heat transfer area F and the overall heat transfer coefficient K, or they are calculated with the empirical equations of the heat transfer coefficient and pressure drop. COP of NARBs is higher than that of pure refrigerants in case of large inlet and outlet temperature difference of both heat sink and source water and high heat transfer performance of heat exchangers. In case of same FK-value, heat transfer lengths of condenser and evaporator using NARBs are longer than those using pure refrigerant. The degree of improvement in COP estimated under the same heat transfer lengths condition is smaller than that estimated under the same FK-values condition.

Miyara, Akio; Koyama, Shigeru; Fujii, Tetsu

442

Fundamentals of heat exchanger and pressure vessel technology  

SciTech Connect

More than 1200 questions and answers provide access to information on process design, mechanical design, vibration analysis, construction, installation, operation, maintenance, and repair; quality control, inspection, and testing; codes and standards; corrosion, erosion, fouling, and water treatment. The question-and-answer format offers solutions to common heat exchanger problems. Supplemented by more than 200 illustrations and over 500 references, this book addresses directly such topics as; tie-rods and various types of baffles; procedures to take when the calculated pressure drop is higher than the allowable value; comparative value of various types of multipass exchangers, multiple segmental baffles, and tube layouts; the effects of laminar and turbulent flows; flow stratification; mechanical design and failure analysis; nondestructive testing methods; nozzle reinforcements; tube cleaning methods; types of corrosion and failing and standard preventive methods; and the causes and prevention of vibration and vibrational damage.

Gupta, J.P.

1986-01-01

443

Solar storage systems using salt hydrate latent heat and direct contact heat exchange. I - Preliminary design considerations  

Microsoft Academic Search

The operating characteristics of a salt hydrate latent heat storage system, using Glauber's salt and direct contact heat exchange through an immiscible heat transfer fluid, have been studied theoretically. Drop dynamics and heat transfer models from the literature were used to predict the system behavior for a range of conditions involving heat transfer fluid inlet temperature and drop size, composition

A. E. Fouda; G. J. G. Despault; J. B. Taylor; C. E. Capes

1980-01-01

444

An analysis of laminar forced convection heat transfer in helically finned heat exchanger passages  

NASA Astrophysics Data System (ADS)

Fluid-flow and heat-transfer results for a curved rectangular-duct model of a thermally developed laminar flow in the interfin passage of fine-pitched helically finned heat exchangers are presented. The study is restricted to fully developed velocity and temperature fields and carried out for values of the Dean number of up to 800 and Prandtl numbers of 0.1, 0.7, 5, and 10. It is noted that the secondary flow in the flow passage cross section exhibits a dual solution behavior for certain values of the Dean number, and that the local heat-transfer coefficient varies significantly over the heat-transfer perimeter. The local and overall heat transfer coefficients for the four-vortex solution are found to be lower than the two-vortex solution; the overall heat-transfer coefficient is shown to increase with the Dean and Prandtl numbers.

Choudhury, D.; Patankar, S. V.

1991-06-01

445

Investigations on two-phase heat exchanger for mixed refrigerant Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

The design of the recuperative heat exchanger used to pre-cool the refrigerant mixture prior to J-T expansion is crucial for the efficient operation of the mixed refrigerant Joule- Thomson (MR J-T) cryocooler. The multi-component non-azeotropic refrigerant mixture undergoes boiling and condensation heat transfer simultaneously in the heat exchanger. Therefore, it is important to analyze the performance of the heat exchanger in terms of temperature distribution with respect to the mixture of gases used. In the present work, temperature measurements are carried out at the ends of the heat exchanger for high pressure stream, while eight sensors are installed at equal distance along the length of heat exchanger to measure temperature of low pressure stream. The paper reports variation in heat transfer coefficient along the length of the heat exchanger. The variation is discussed with respect to temperature distribution across the length and changes in thermo-physical properties of the gas mixture.

Ardhapurkar, Purushottam; Sridharan, Arunkumar; Atrey, Milind

2012-06-01

446

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

NASA Astrophysics Data System (ADS)

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

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

447

Development of Passive Fuel Cell Thermal Management Heat Exchanger  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

448

Design of heat exchanger for ericsson-brayton piston engine.  

PubMed

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

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

2014-01-01

449

Design of Heat Exchanger for Ericsson-Brayton Piston Engine  

PubMed Central

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.

Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef

2014-01-01

450

Comparison of heat and mass transfer in different heat exchanger geometries with corrugated walls  

Microsoft Academic Search

In systematic comparative analyses heat exchangers with corrugated walls are analysed. The wall corrugation is generated by sinusoidally shaped walls as well as by crosswise corrugated cylinders of different cross-section on plane walls like those being used as spacers in membrane technology.Corrugated structures in crosswise orientation are composed of passages formed by layers of corrugated structures with opposite orientation of

C Zimmerer; P Gschwind; G Gaiser; V Kottke

2002-01-01

451

Oil\\/salt hydrate direct-contact heat-exchange experiments  

Microsoft Academic Search

A pilot-scale, direct-contact heat exchanger\\/storage column has been operated to determine heat transfer performance, storage capability, and operational difficulties associated with direct-contact heat exchange and storage with an oil heat transfer fluid and salt hydrate latent-heat storage medium. A fundamental analysis of the heat transfer mechanisms in the direct-contact process between oil droplets and the salt hydrate storage medium has

J. D. Wright; M. S. Bohn; R. S. Barlow

1983-01-01

452

Aging management guideline for commercial nuclear power plants - heat exchangers  

SciTech Connect

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.

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

1994-06-01

453

Performance Prediction of Cross-Finned Tube Heat Exchangers  

NASA Astrophysics Data System (ADS)

The plane fin of a cross-finned tube heat exchangers is the basis for all kinds of fins used in air conditioners. In this paper, an improvement the dimensionless arrangements of pressure drop for plane fins was attempted. The detailed calculation results for all geometrical parameters, especially tube disposition, showed the reflecting to the effect of contracted flow in the existing equations of friction factor is insufficient. Therefore, an amendment for these equations was suggested. Further, the analogy between the revised friction factor and the Colburn's j factor was verified. In addition an approximate expression for the fin efficiency using wide parameters was devised.

Kondou, Chieko; Senshu, Takao; Oguni, Kensaku

454

Exchange fluctuation theorem for heat transport between multiterminal harmonic systems  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

455

Characterization of silicon crystals grown by the heat exchanger method  

SciTech Connect

Silicon ingots grown by the Heat Exchanger Method (HEM) as large as 45 kg in mass (34 cm x 34 cm x 17 cm) are characterized electrically and structurally. The defect state in the crystal is related to the solar cell efficiency. Such characterization indicates that the solar cell efficiency of HEM crystals is limited by the crystal perfection, but that HEM silicon has the potential to yield silicon with quality comparable to Cz grown silicon. A new approach to grow HEM material of better quality is discussed.

Hyland, S.; Dumas, K.A.; Engelbrecht, J.A.A.; Leung, D.; Schwuttke, G.M.

1983-05-01

456

DETAILED LOOP MODEL (DLM) ANALYSIS OF LIQUID SOLAR THERMOSIPHONS WITH HEAT EXCHANGERS  

SciTech Connect

An analytical Detailed Loop Model (DLM) has been developed to analyze the performance of solar thermosiphon water heaters with heat exchangers in storage tanks. The model has been used to study the performance of thermosiphons as a function of heat exchanger characteristics, heat transfer fluids, flow resistances, tank stratification, and tank elevation relative to the collector. The results indicate that good performance can be attained with these systems compared to thermosiphons without heat exchangers.

Mertol, A.; Place, W.; Webster, T.; Greif, R.

1981-06-01

457

Performance evaluation of the recuperative heat exchanger in a miniature Joule–Thomson cooler  

Microsoft Academic Search

To develop effective heat exchangers for miniature and micro-Joule–Thomson (J–T) cooling system, the performance of the recuperative heat exchanger in a miniature J–T cooler is analyzed and evaluated. The evaluation is based on a theoretical model of the Hampson-type counter-flow heat exchanger. The effect of the pressure and temperature-dependent properties and longitudinal heat conduction are considered. The results of the

H. Xue; K. C. Ng; J. B. Wang

2001-01-01

458

Turbulent heat transfer enhancement in a heat exchanger using helically corrugated tube  

Microsoft Academic Search

The augmentation of convective heat transfer in a single-phase turbulent flow by using helically corrugated tubes has been experimentally investigated. Effects of pitch-to-diameter ratio (P\\/DH=0.18, 0.22 and 0.27) and rib-height to diameter ratio (e\\/DH=0.02, 0.04 and 0.06) of helically corrugated tubes on the heat transfer enhancement, isothermal friction and thermal performance factor in a concentric tube heat exchanger are examined.

S. Pethkool; S. Eiamsa-ard; S. Kwankaomeng; P. Promvonge

2011-01-01

459

Study of thermal energy storage using fluidized bed heat exchangers  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

460

Two-phase/two-phase heat exchanger simulation analysis  

NASA Technical Reports Server (NTRS)

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.

Kim, Rhyn H.

1992-01-01

461

Active heat exchange system development for latent heat thermal energy storage  

NASA Astrophysics Data System (ADS)

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.

Lefrois, R. T.

1980-03-01

462

Better Thermal Calculations Using Modified Generalized Leveque Equations for Chevron Plate Heat Exchangers  

Microsoft Academic Search

Plate heat exchangers are becoming vital process energy exchange equipment in chemical industries. The present work looks into the applicability of the Generalized Leveque Equation (GLE), which is used to generate thermal performance calculations for chevron-type plates utilized in plate and frame heat exchangers. New Modified Generalized Leveque Equations are proposed to improve calculation accuracy, which will enhance energy utilization

Mazen M. Abu-Khader

2007-01-01

463

Heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a heat exchanger  

NASA Astrophysics Data System (ADS)

This paper describes heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a fin-tube heat exchanger. The experiments in which the moist air was passed into the heat exchanger coated with sorption material were conducted under various conditions of air flow rate (0.5 1.0 m/s) and the temperature of brine (14 20°C) that was the heat transfer fluid to cool the air flow in the dehumidifying process. It is found that the sorption rate of vapor is affected by the air flow rate and the brine temperature. Meanwhile, the attempt of clarifying the sorption mechanism is also conducted. Finally the average mass transfer coefficient of the organic sorbent coated on heat transfer surface of a fin-tube heat exchanger is non-dimensionalzed as a function of Reynolds number and non-dimensional temperature, and it is found that the effect of non-dimensional temperature on them is larger than Reynolds number .

Inaba, Hideo; Komatsu, Fujio; Horibe, Akihiko; Haruki, Naoto; Machida, Akito

2008-09-01

464

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

NASA Technical Reports Server (NTRS)

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.

Erickson, Lisa R.; Ungar, Eugene K.

2013-01-01

465

Dynamics of compressible air flow in ducts with heat exchange  

NASA Astrophysics Data System (ADS)

An investigation into the effect of heat addition on subsonic flow of an air stream in a constant-area duct preceded by a convergent nozzle is carried out. A nozzle flow apparatus with a heat exchanger encasing the constant-area duct has been built for this purpose. Hot water is provided from an electric boiler where the flow rate and the in-flow hot water temperature could be controlled. It is confirmed experimentally, as predicted analytically, that heat transfer to the gas decreases its local static pressure along the duct axis, and that this decrease is associated with an increase in Mach number toward M = 1 at the exit (thermal choking). In the case of subsonic flow, the additional entropy generated by the heat interaction exceeding the amount that produces thermal choking can only be accommodated by moving to a new Rayleigh line, at a decreased flow rate which lowers the inlet Mach number. The good correlation between the experimental results and the analytical derivations illustrates that the experimental arrangement has potential for further experiments and investigations.

Abdulhadi, M.

1986-12-01

466

Heat-exchanger concepts for neutral-beam calorimeters  

SciTech Connect

Advanced cooling concepts that permit the design of water cooled heat exchangers for use as calorimeters and beam dumps for advanced neutral beam injection systems were evaluated. Water cooling techniques ranging from pool boiling to high pressure, high velocity swirl flow were considered. Preliminary performance tests were carried out with copper, inconel and molybdenum tubes ranging in size from 0.19 to 0.50 in. diameter. Coolant flow configurations included (1) smooth tube/straight flow, (2) smooth tube with swirl flow created by tangential injection of the coolant, and (3) axial flow in internally finned tubes. Additionally, the effect of tube L/D was evaluated. A CO/sub 2/ laser was employed to irradiate a sector of the tube exterior wall; the laser power was incrementally increased until burnout (as evidenced by a coolant leak) occurred. Absorbed heat fluxes were calculated by dividing the measured coolant heat load by the area of the burn spot on the tube surface. Two six element thermopiles were used to accurately determine the coolant temperature rise. A maximum burnout heat flux near 14 kW/cm/sup 2/ was obtained for the molybdenum tube swirl flow configuration.

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

1981-10-05

467

Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed  

NASA Astrophysics Data System (ADS)

Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

Honda, Ryosuke; Umekawa, Hisashi; Ozawa, Mamoru

2009-06-01

468

Integrated heat exchanger design for a cryogenic storage tank  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

469

Microbiologically influenced corrosion (MIC) in stainless steel heat exchanger  

NASA Astrophysics Data System (ADS)

Corrosion attack in the form of corrosion product tubercles was observed in an AISI 304 (EN 1.4301) stainless steel heat exchanger only after 36 months of service. Failure analyses revealed that in one of the attacked areas corrosion had penetrated the entire wall thickness of 6.2 mm, but in most of the cases it reached the depth of 2-4 mm. In this paper, we report the results from a thorough microstructural characterization of the corroded heat exchanger carried out with optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Microstructural studies by OM, SEM and XRD revealed a two-phase structure of austenite and ferrite in the bulk material, as well as the preferential attack of the ferrite phase. SEM surface studies disclosed bacteria in and close to the attacked areas. Cross-sectional SEM examinations showed the distribution and composition of corrosion products within and underneath the tubercles. TEM and XRD studies gave information about the amorphous and/or nanocrystalline nature of some of the formed corrosion products. These results are discussed in this paper and, based on them, the main corrosion mechanism for the observed attack is suggested. Further, explanations for the propagation of corrosion along the ferrite phase are presented.

Huttunen-Saarivirta, E.; Honkanen, M.; Lepistö, T.; Kuokkala, V.-T.; Koivisto, L.; Berg, C.-G.

2012-06-01

470

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

SciTech Connect

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

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

1996-05-01

471

Heat transfer between liquid3He and sintered metal heat exchangers  

NASA Astrophysics Data System (ADS)

A new model to explain the unexpectedly large heat transfer between liquid3He and sintered metal heat exchangers is described and evaluated. The heat transfer results from a direct coupling of3He quasiparticles in the pores to vibrational modes of the sintered metal powder. It is proposed that for a range of temperatures below 20 mK the dominant vibrational modes of the sinter are localized oscillations involving a few powder particles with frequencies distributed over a constant density of states. The3He is then treated as a Fermi gas in a set of boxes corresponding to the pores in the sinter. The vibrating or shaking boxes transfer energy to the3He quasiparticles inside the box. The calculated heat transfer between liquid3He and the vibrational modes of sintered metal heat exchangers is Q/(V?T)˜4×10 - 15 T/d 3 W m-3 K-1, where Q is the heat flow for a temperature difference ?T, V is the volume of the sinter (metal and helium), and d is the powder particle diameter in meters; this has the observed linear temperature dependence, and in magnitude is larger than or comparable to published results from several laboratories. The heat transfer between the vibrational modes and the electron gas in the metal sinter that is needed to complete the heat path can also be described by the same model with the result that the electron-“phonon” coupling is significantly larger than the3He-“phonon” coupling. When the model is applied to heat transfer between liquid3He-4He mixtures and sinter the calculated results are again comparable to or larger than those measured. The postulated localized oscillator modes give a specific heat, linear in temperature, that is in reasonable agreement with measurements for pressed powder by Pohl and Tait.

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

1984-04-01

472

Experimental investigation on condensation heat transfer and pressure drop of R134a in a plate heat exchanger  

NASA Astrophysics Data System (ADS)

Condensation heat transfer of R134a in a vertical plate heat exchanger was investigated experimentally. The local heat transfer coefficients are determined by means of the measured local wall temperatures. A differential energy balance model is developed for data evaluation. It is found that the correlation proposed by Shah using ? and Z factors is suitable for condensation in plate heat exchangers and is adopted to fit the measured data.

Shi, Z.-Y.; Chen, J.-P.; Grabenstein, V.; Kabelac, S.

2010-11-01

473