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1

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

2

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

NASA Astrophysics Data System (ADS)

The question of layered versus whole mantle convection has been pending since early models of mantle convection (Oxburgh and Turcotte, 1967; McKenzie and Richter, 1978). In a first phase, layered mantle models appeared to be the winners, because they explained most of geochemical observations. They of course also explained the seismic focal solutions (compressive/ non compressive) in subducting plate and the heat flow constraints (Richter, 1980). Later on, the discovery that slabs could penetrate the lower mantle was considered as proof of whole mantle convection. Most numerical experiments were then developed in this context, overlooking many geochemical observations such as rare gas isotopes or radioactive elements. In this presentation, we will examine the different data one by one. a) geochemical constraints include the budget equations for Sr, Nd, Hf, isotopes, the budget equation for He, Ne, Ar, the budget for heat producing elements U, Th, K (including Th/U and K/U ratios). (Allègre and al., 1979, 1982; De Paolo and Wasserburg, 1977; O'Nions and al.,1977). b) Constrains linking geochemical observations and geodynamics. How the so-called depleted mantle is generated ? Continuities and affinities between MORB and OIB, including the Dupal and Non Dupal provinces: The non-pristine source for OIB based on Pb isotope data. The marble cake structure for upper mantle. Continental crust recycling via sediments and delamination processes. In thise respect, we emphasize the difference in statistical variance of isotope or trace element ratios in the different/types of basalts reflecting the difference in stirring intensity in their sources. We also use information from extinct radioactivities 142Nd and 129Xe. In each case, we estimate the errors for measurements and models. c) The seismic evidence of slab penetration into the lower mantle are from Creager and Jordan(1984) to Van der Hilst et al.(1991), Sparkman and al.(1993), with the counter example of non-penetrating slabs as emphasized by Fukao and al.(2001) and the recent observation of the large energy spectrum differences at 670 km depth (Gu and al., 2006). We discuss the problem of return flow, which is crucial for both energy budget and convection regime. The recent work on plume by Montelli and al. (2004, 2006) shows the existence of broad plumes in the lower mantle and thin plumes in the upper mantle. d) The estimate of heat flow coming from the lower mantle of 35-32 TW. The work of Davies(1990) and Sleep(1992) shows clearly that this transfer is not the result of plumes reaching the surface, because they correspond at most to 3TW. At the reverse the estimated heat flow carried by the lower mantle plumes is much higher (Nolet and al., 2006). We also discuss the heat flow paradox to explain a Urey ratio of 0.4 with whole mantle convection. In conclusion, we propose mantle with two layers convecting separately but with some exchange of matter, this global exchange corresponding to 1.1024kg since 4.4 Gy. Plume genesis is a two-stage process. Lower mantle plumes heat the Mesosphere boundary layer generating second generation plumes which reach the surface (Allègre and Turcotte; 1983; Allègre, 1987). In the upper mantle itself, we have to distinguish between a vigorously convecting asthenosphere and a sluggish convecting transition zone, both convecting in same cells.

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

2007-12-01

3

Mantle heat flow  

Microsoft Academic Search

A map of the heat flux out of the earth's mantle has been prepared by subtracting the heat flow arising in the earth's crust from the surface heat flow. In continental areas the crustal contribution of the enriched zone is determined from the parameters of the linear heat flow-heat production relationship q0 = q* + bA0 in areas where such

Henry N. Pollack; David S. Chapman

1977-01-01

4

Heat sources for mantle plumes  

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

5

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

6

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

7

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

8

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

9

Excess Temperature and Heat Transport in Mantle Plumes: a reassessment  

Microsoft Academic Search

Heat transfer across the core mantle boundary (CMB) is fundamentally important to Earth's internal energy budget, but the amount of heat entering the mantle from the core is poorly known. Classic arguments based on the dynamic topography over mantle hotspots suggest a rather modest core contribution to the mantle energy budget, on the order of 5-10 percent. Recent geodynamic studies,

H. Bunge

2003-01-01

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

21

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

22

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

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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

39

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

40

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

41

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

42

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

43

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

44

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

45

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

46

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

47

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

NASA Astrophysics Data System (ADS)

Geological studies have suggested that significant amount of granitic crustal materials have been lost from the surface by the delamination (~1.1 km^3/yr) [1], continental collision (~0.4-0.7 km^3/yr) [1, 2], and subduction at ocean-margin (~2.5-3 km^3/yr) [1, 2]. At ocean-margin subduction zones, most of the granitic materials subducted from the surface are expected to be conveyed through subduction channels by viscous drag to 270km depth [Ichikawa el al., in revision]. If so, then the subducted crustal materials might be expected to be trapped in the mid-mantle owing to the density difference from peridotitic materials induced by the phase transition from coesite to stishovite at 270km depth. In other words, strong heat source materials are most likely to be accumulated around the mantle transition zone, at least, near the plate subduction zones. In this study, we conducted two-dimensional numerical experiments of mantle convection with continental drift and a heat source placed around the mantle transition zone, in order to study the effect of the subducted granitic materials drifting around the mantle transition zone. The simulations deal with a time-dependent convection of fluid under the extended Boussinesq approximation in a model of a two-dimensional rectangular box of 2900km height and 11600km width, where a continent and heat source is imposed. We found that the addition of the heat source considerably reduces the time scale of continental drift. In the absence of the heat source, the resulting time scale is too long compared with that of the so-called supercontinent cycle, where the breakup is induced from a plume generated by an insulating effect of the continent. The heat source also causes massive mechanical mixing especially on the upper mantle. The result suggests that the heat source drifting around mantle transition zone can be a possible candidate inducing the supercontinent cycle in an appropriate time scale. [1] Clift, P. D., P. Vannucchi, and J. P. Morgan (2009), Crustal redistribution, crust-mantle recycling and Phanerozoic evolution of the continental crust, Earth-Science Reviews. [2] Stern, R. J., and D. W. Scholl (2010), Yin and yang of continental crust creation and destruction by plate tectonic processes, International Geology Review, 52(1), 1-31.

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

2012-12-01

48

Geoneutrino perspective on Earth's heat budget and mantle structure  

NASA Astrophysics Data System (ADS)

Neutrino geophysics is an emerging interdisciplinary field with the potential to map the abundances and distribution of radiogenic heat sources in the continental crust and deep Earth. To date, data from two different experiments quantify the amount of Th and U in the Earth, and begin to put constraints on radiogenic power in the Earth available for driving mantle convection and plate tectonics. New improved detectors are under construction or in planning stages. Critical testing of compositional models of the Earth requires integrating geoneutrino and geological observations. Such tests will lead to significant constraints on the absolute and relative abundances of Th and U in the continents. High radioactivity in continental crust puts limits on land-based observatories' capacity to resolve mantle models with current detection methods. However, the quantification of deep-seated radioactivity is crucial for understanding the composition and dynamics of the Earth, including its thermal evolution, the style and planform of mantle convection, and the energetics of the core. Estimates of mantle radiogenic heat production vary significantly between some models. Th and U budget of Earth's compositional models based on enstatite chondrite chemistry, as well as models that employ an early loss of crustal material by a collisional erosion mechanism are consistent with a uniform mantle composition. Typically, these models end up with negligible amount of radiogenic power in the mantle after accounting for that in the crust. On the other hand, models constrained by composition of available Earth rock samples and C1 chondritic ratios of refractory lithophile elements require a mantle reservoir enriched in heat producing elements relative to the source of mid-oceanic ridge basalts. Such a reservoir is likely to show strong variation in thickness in the convecting mantle; it is usually identified with the seismically seen low shear wave velocity provinces (LLSVPs) in the deep mantle. The resulting laterally variable geoneutrino signal at Earth's surface may be measurable, thus offering an unprecedented direct detection of deep mantle chemical variability. We review the recent advances in geoneutrino research with a particular focus on mantle geoneutrino detection. We quantify how a multiple-site measurement in oceanic areas away from continental crust and nuclear reactors can be used to extract mantle information.

Sramek, O.; McDonough, W. F.; Kite, E. S.; Lekic, V.; Dye, S.; Zhong, S.

2012-12-01

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

Heat transport by conduction in the deep mantle  

NASA Astrophysics Data System (ADS)

At high mantle temperatures, the phonon (vibrational or lattice) component of thermal diffusivity is independent of T. Laser flash measurements, which isolate phonon transport, of mineral families show that the complex silicates (olivines, orthopyroxenes, clinopyroxenes, garnets) have D asymptoting to 0.7 mm2/s whereas simple oxides (spinel, MgO, quartz) have slightly higher values of 1 to 1.5 mm2/s, such that the impurites lower Dsat. Values in the lower mantle are hence controlled by pressure. Multiple measurements of olivine and MgO give d(ln D)/dP near 3%/GPa which are compatible with the damped harmonic oscillator model. This model predicts d(ln D)/dP = 1.7%/GPa for incompressible phases like perovskite. Data and model constrain values of D and k = density X heat capacity X D for the lower mantle. High temperatures also provide radiative transfer, for which the strong dependence on temperature, Fe-content, and grain-size supercede its weak pressure dependence. However, the small expected grainsize of ca 1 mm makes scattering important and calculated values of krad are similar for olivine, perovskite and garnet, despite the variation in absorption spectra. Roughly, krad is 0.5 W/m-K in the lower mantle increasing to 3 W/m-K the lowest mantle (layer D"), which is dwarfed by 60 W/m-K for klat of a perovskite dominated lower mantle. Magnesiowustite, if present, would further increase klat. Thus layer D" can carry immense power (100 TW) over a steep temperature gradient (1000 K over 200 km) and 3 TW, which is a likely value for core production, over an adiabatic D" layer. Thus, the efficiency of phonons in diffusing heat allows the lower mantle to conduct: convection in the lower mantle is not likely, other than in the form of weak Hadley-type unicells.

Hofmeister, A. M.

2008-05-01

54

Penetrative convective flows induced by internal heating and mantle compressibility  

NASA Technical Reports Server (NTRS)

Penetrative convective flows induced in a spherical shell by combined effects of internal heating and mantle compressibility are investigated using mathematical and numerical formulations for compressible spherical shell convection. Isothermal stress-free boundary conditions applied at the top and the bottom of the shell are solved using a time-dependent finite difference code in a temperature, vorticity, stream function formulation for Rayleigh numbers ranging from the critical Rc up to 2000 Rc. Results indicate that compressibility, together with internal heating, could be a mechanism capable of generating spontaneously layered convection and local melting in the mantle and that non-Boussinesq effects must be considered in interpretations of geophysical phenomena.

Machetel, Philippe; Yuen, David A.

1989-01-01

55

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

56

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

57

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

58

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

59

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

60

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

61

Deep mantle heat flow and thermal evolution of the Earth's core in thermochemical multiphase models of mantle convection  

Microsoft Academic Search

A coupled model of thermochemical multiphase mantle convection and parameterized heat balance in the Earth's core is used to investigate the need for radioactive potassium in the core, and chemical layering above the core-mantle boundary (CMB), to obtain a successful thermal evolution of the core, i.e., one in which the magnetic field exists over geological time and the final inner

Takashi Nakagawa; Paul J. Tackley

2005-01-01

62

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

63

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

64

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.

65

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

66

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

NASA Technical Reports Server (NTRS)

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

Desmarais, D.

1986-01-01

67

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

68

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

69

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

70

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

71

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

72

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

73

Heat production and heat flow in the mantle lithosphere, Slave craton, Canada  

NASA Astrophysics Data System (ADS)

Thermobarometric data for mantle xenoliths from a kimberlite pipe in the NWT, Canada are used to constrain the thermal properties of the lithospheric mantle underlying the Slave craton. We derive an analytical expression for a steady-state conductive mantle geotherm that is independent of the geometry and thermal properties of the crust. The model has an upper boundary coincident with the MOHO at a depth Zm and has temperature Tm and heat flow qm. The mantle is assumed to have constant radiogenic heat production ( A) and we allow for a temperature-dependent thermal conductivity [ K( T)= Ko(1+ B( T- Tm))]. Inverting the thermobarometric data through the model geotherm gives limiting values for mantle heat production ( A) and bounds on the temperature dependence of K (e.g. B) that are consistent with the mantle P- T array. We characterize the Slave lithospheric mantle in terms of three critical parameters qm (mW m -2), A (?W m -3), Tm (°C). The optimal solution has values [15.1, 0.012, 455]. This characterization of thermal state of the Slave mantle is based mainly on petrological data and is not biased by assumptions about crustal thermal properties. Our analysis shows that a substantial range of parameter values can be used to describe the data accurately and the two bounding solutions are [24.2, 0.088, 296] and [12.3, 0, 534], respectively. However, model parameters are strongly correlated and this precludes the arbitrary selection of values of [ qm, A, Tm] from these ranges.

Russell, James K.; Dipple, G. M.; Kopylova, M. G.

2001-03-01

74

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

75

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

76

The structure of convection in the spherical mantle with internal heating  

NASA Astrophysics Data System (ADS)

Thermal convection in the mantle is caused by the heat transported upwards from the core and by the heat produced by the internal radioactive sources. According to the data on the heat transfer by the mantle plumes and geochemical evidence, only 20% of the total heat of the Earth is supplied to the mantle from the core, whereas most of the heat is generated by the internal sources. Along with the models that correctly allow for the internal heat sources, there are also many publications (including monographs) on the models of mantle convection that completely ignore the internal heating or the heat flux from below. In this study, we analyze to what extent these approximations could be correct. The analytical distributions of temperature and heat flux in the case of internal heating without convection and the results of the numerical modeling for convection with different intensity are presented. It is shown that the structure of thermal convection is governed by the distribution of the heat flux in the mantle but not by the heat balance, as it is typically implicitly assumed in most works. Heat production by the internal sources causes the growth of the heat flux as a function of radius. However, in the spherical mantle of the Earth, the heat flux decreases with radius due to the geometry. It turned out that with the parameters of the present Earth, both these effects compensate each other to a considerable extent, and the resulting heat flux turns out to be nearly constant as a function of radius. Since the structure of the convective flows in the mantle is determined by the distributions of heat flux and total heat flux, in the Cartesian models of the mantle convection the effective contribution of internal heating is small, and ignoring the heat flux from the core significantly distorts the structure of the convective currents and temperature distributions in the mantle.

Trubitsyn, V. P.; Evseev, A. N.; Evseev, M. N.; Evseeva, A. V.

2013-09-01

77

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

78

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

79

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

80

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

81

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

82

“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

83

Energetics and heat budget of the earth's mantle convection constrained by plume and slab dynamics  

NASA Astrophysics Data System (ADS)

Understanding the heat budget and energetics of the Earth's mantle convection is important for constraining the thermal evolution history and chemical composition of the Earth's core and mantle. Mantle plumes and subducted slabs are two most important agents for energy transfer in the Earth's mantle convection. With numerical modeling and theoretical analysis, here we show that surface observations of plumes and slabs can be used to constrain the internal heating ratio of the mantle, the core-mantle boundary (CMB) heat flux and the viscous dissipation in the plate bending zones. We also show that including more realistic physics may significantly affect the surface manifestation of the conventional mantle plume model. Our main conclusions are summarized as below. First, mantle plumes account for 80%-90% of the CMB heat flux. Due to the steeper adiabatic gradient of plumes compared with ambient mantle, plume heat flux and plume excess temperature decrease approximately by a factor of two during plumes' ascent. In order to reproduce surface plume-related observations, ˜70% internal heating ratio of the Earth's mantle, i.e. ˜11 TW of CMB heat flux, is required. Second, the total viscous dissipation and the total adiabatic heating balance out each other at any instant in time for compressible mantle convection. The viscous dissipation in the plate bending zones only account for <10% of the total viscous dissipation in the Earth's mantle, thus plays a minor role in Earth's thermal evolution history. Third, instead of causing surface uplift as suggested by convectional plume models, a plume head temporarily ponding below the 660-km phase boundary may cause significant surface subsidence over an extended time period before it reaches surface and generates flood basalt eruptions. Therefore, the observed surface subsidence history in many flood basalt provinces may be used as diagnostics for identifying plume-induced flood basalt events.

Leng, Wei

84

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

85

Mantle convection with internal heating and pressure-dependent thermal expansivity  

NASA Technical Reports Server (NTRS)

Recent laboratory work suggests that the thermal expansivity alpha of the mantle decreases strongly with pressure. alpha determines the buoyancy of plumes and the rate at which plumes lose their thermal signature as they rise, and so may be expected to have a strong influence on the temperature and velocity structure of the mantle. Numerical simulations were conducted on convection in an internally heated, compressible mantle including constant and pressure-dependent alpha and thermal conductivity kappa. They show that a pressure-dependent alpha allows the existence of thermal plumes rising from the core-mantle boundary, however the plumes are weak and dissipate higher in the mantle.

Leitch, A. M.; Yuen, D. A.; Sewell, G.

1991-01-01

86

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

87

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

88

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

89

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

90

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

91

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

92

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

93

Core Heat Flow and Suppression of Mantle Plumes by Plate-Scale Mantle Flow: Results From Laboratory Experiments  

NASA Astrophysics Data System (ADS)

Heat flow from the Earth's core to the mantle remains an unresolved quantity. Its value has implications for the core's thermal evolution and growth of the inner core, the geodynamo, and the relative abundance of radioactive elements in the core and mantle. Core heat flow is affected by dynamics of the lowermost mantle in three ways: (1) advection of heat by plume instabilities; (2) conductive heating of subducted material; and (3) suppression of plume instabilities, as well as advection of heat by plate-scale mantle flow. We present results from a boundary-layer analysis and laboratory experiments aimed at understanding the effects of an imposed large-scale circulation on thermal convection at high-Rayleigh number (106<=Ra<=109) in a fluid with a strongly temperature-dependent viscosity. The ultimate goal of this work is to better understand the effect of plate-scale mantle flow on heat flux across the CMB and on the dynamics of plume formation at the CMB. Our theoretical analysis is complemented by lab experiments, in which a layer of corn syrup is heated from below and a large-scale flow is induced in the fluid above the hot boundary. We identify 4 convective regions associated with high-Rayleigh number convection in the presence of a large-scale flow: (1) a subcritical TBL region (Domain I), where plume instabilities are suppressed by the advective thinning of the TBL and heat flux is increased relative to convection without large-scale flow; (2) a supercritical TBL region (Domain II), where plume instabilities are no longer suppressed and heat flux is equal to convection without large-scale flow; (3) a flow-dominated region (Domain III), which is free of plumes; and (4) a plume-dominated domain (Domain IV), where the interaction of hot buoyant plumes and imposed large-scale flow results in lateral advection and distortion of rising plumes. In addition, we present a boundary-layer analysis that predicts heat flux, Q, from a hot surface as a function of imposed large-scale velocity (U) or Peclet number (Pe=UL/? , where L is fluid depth and ? is thermal diffusivity) and horizontal position. Due to the strong temperature dependence of our working fluid, we observe a viscosity contrast of order 10 to 100 between ambient fluid and fluid near the hot boundary. We find a good match between boundary layer analysis for a free-slip boundary and experiments and obtain a heat-flux ratio ?=QPe>0/QPe=0 that scales with Pe1/2 Ra-0.28. Throughout Domain I values of ?>1 and TBL thickness increases, while ? decreases in the downstream direction. When applied to the Earth, our results indicate that the TBL at the CMB may locally be stabilized by plate-scale mantle flow (Domain I), thereby resulting in locally increased heat flux across the CMB. If the mantle above D" is 2-3 times more viscous than the upper mantle (Ra~106) and lower-mantle velocities are ~1 cm/y, then plume formation will be suppressed over a significant distance (~1000 km). This would have implications for the distribution of hotspots. Furthermore, the increased CMB heat flux could be of importance in terms of core evolution, the geodynamo and global heat-flow estimates. For smaller velocities and/or larger Ra, our analysis suggests that plume suppression and increased CMB heat flux remain localized and of limited importance.

Gonnermann, H. M.; Jellinek, A. M.; Richards, M. A.; Manga, M.

2002-12-01

94

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

95

Modes of mantle convection and the removal of heat from the earth's interior  

NASA Technical Reports Server (NTRS)

Thermal histories for two-layer and whole-mantle convection models are calculated and presented, based on a parameterization of convective heat transport. The model is composed of two concentric spherical shells surrounding a spherical core. The models were constrained to yield the observed present-day surface heat flow and mantle viscosity, in order to determine parameters. These parameters were varied to determine their effects on the results. Studies show that whole-mantle convection removes three times more primordial heat from the earth interior and six times more from the core than does two-layer convection (in 4.5 billion years). Mantle volumetric heat generation rates for both models are comparable to that of a potassium-depleted chondrite, and thus surface heat-flux balance does not require potassium in the core. Whole and two-layer mantle convection differences are primarily due to lower mantle thermal insulation and the lower heat removal efficiency of the upper mantle as compared with that of the whole mantle.

Spohn, T.; Schubert, G.

1982-01-01

96

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

97

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

98

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

99

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

100

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

101

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

102

The influence of tectonic plates on mantle convection patterns, temperature and heat flow  

Microsoft Academic Search

SUMMARY The dynamic coupling between plate motion and mantle convection is investigated in a suite of Cartesian models by systematically varying aspect ratios and plate geometries. The aim of the study presented here is to determine to what extent plates affect mantle flow patterns, temperature and surface heat flux. To this end, we compare numerical convection models with free-slip boundary

Julian P. Lowman; Scott D. King; Carl W. Gable

2001-01-01

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

118

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

119

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

120

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

121

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

122

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

123

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

124

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

125

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

126

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

127

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

128

Constraining mantle heat generation and Earth's energy budget with geo-neutrinos  

NASA Astrophysics Data System (ADS)

The total energy loss of the Earth is well constrained by heat flux measurements on land, the plate cooling model for the oceans, and the buoyancy flux of hotspots. It amounts to 46±2 TW. The main sources that balance the total energy loss are the radio-activity of the Earth's crust and mantle, the secular cooling of the Earth's mantle, and the energy loss from the core. Only the crustal radio-activity is well constrained. The uncertainty on each of the other components is larger than the uncertainty of the total heat loss. The mantle energy budget can not be balanced by adding the current estimates of mantle radioactivity, secular cooling of the mantle, and heat flux from the core. Neutrino observatories in deep underground mines can detect antineutrinos emitted by the radioactivity of U and Th. Provided that the crustal contribution to the geo-neutrino flux can be very precisely calculated, it will be possible to put robust constraints on mantle radio-activity and its contribution to the Earth's energy budget. If directional information could be obtained, geo-neutrino observations could directly resolve radial variations in the distribution of the radio-elements U and Th and detect the presence of deep reservoirs of these elements in the mantle.

Mareschal, J.; Jaupart, C. P.; Phaneuf, C.

2011-12-01

129

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

130

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

131

Laser-Heated DAC Mössbauer Study of Lower Mantle Phases: Spin Transitions and Implications for Mantle Heterogeneity  

NASA Astrophysics Data System (ADS)

57Fe Mössbauer spectroscopy measured in the energy domain remains one of the best methods to determine iron valence and the nature of spin transitions in lower mantle phases, but up until now measurements at high P,T using a diamond anvil cell (DAC) could only be made using external heating and hence were limited to a maximum of around 800 K. Higher temperatures are possible through laser heating; however conventional radioactive sources have limited intensity and essentially no possibilities for focusing in a laboratory setting. To overcome these limitations we have developed an energy domain synchrotron Mössbauer source (SMS) on beamline ID18 at the European Synchrotron Radiation Facility, enabling rapid collection of high quality energy domain Mössbauer spectra. Combined with a portable double-sided laser heating system, SMS spectra can be collected on iron-containing phases at P,T conditions up to those close to the base of the lower mantle in less than one hour. In the current study we performed SMS measurements on several compositions of (Mg,Fe)(Si,Al)O3 perovskite (Pv) as well as Mg0.8Fe0.2O (Fp) up to 122 GPa and 2500 K. All Mössbauer spectra at high pressure and room temperature are consistent with previous observations: a high-spin (HS) to intermediate-spin (IS) transition of Fe2+(Pv) starting at around 30 GPa, a HS to low-spin (LS) transition of Fe2+(Fp) starting at around 50 GPa, and no spin transition in Fe3+(Pv) up to at least 100 GPa. At high temperature all Fe2+ components show the expected strong decrease in both centre shift and quadrupole splitting, which provides an independent measure of temperature based on the Debye model, and shows clearly the strong temperature gradient in one-sided versus double-sided laser heating experiments. Preliminary fitting of the high P,T Mössbauer spectra is consistent with predominantly IS Fe2+ (Pv), HS Fe3+ (Pv) and mixed HS-LS Fe2+ (Fp). The relative proportion of Fe3+ (Pv) does not appear to change significantly on heating, and all of the original Mössbauer spectra are recovered after cooling. Based on our results, Fe2+ in silicate perovskite is inferred to be predominantly in the IS state throughout the lower mantle while Fe3+ remains in the HS state, implying that seismic velocity anomalies in the main part of the lower mantle cannot be attributed to iron spin transitions in silicate perovskite.

McCammon, C. A.; Dubrovinsky, L. S.; Potapkin, V.; Glazyrin, K.; Prescher, C.; Kupenko, I.; Chumakov, A.; Rüffer, R.; Kantor, A.; Kantor, I.; Smirnov, G. V.; Popov, S.

2011-12-01

132

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

133

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

134

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

135

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

136

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

137

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

138

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

139

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

140

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

141

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

142

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

143

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

144

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

145

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

146

Variation of thermal conductivity and heat flux at the Earth's core mantle boundary  

NASA Astrophysics Data System (ADS)

The two convective systems that dominate Earth's internal dynamics meet at the boundary between the rocky mantle and metallic liquid core. Energy transfer between processes driving plate tectonics and the geodynamo is controlled by thermal conduction in the lowermost mantle (D?). We use atomic scale simulations to determine the thermal conductivity of MgSiO3 perovskite and post-perovskite under D? conditions and probe how these two convective systems interact. We show that the thermal conductivity of post-perovskite (?12 W/mK) is 50% larger than that of perovskite under the same conditions (?8.5 W/mK) and is anisotropic, with conductivity along the a-axis being 40% higher than conductivity along the c-axis. This enhances the high heat flux into cold regions of D? where post-perovskite is stable, strengthening the feedback between convection in the core and mantle. Reminiscent of the situation in the lithosphere, there is potential for deformation induced texturing associated with mantle convection to modify how the mantle is heated from below. We test this by coupling our atomic scale results to models of texture in D? and suggest that anisotropic thermal conductivity may help to stabilise the roots of mantle plumes over their protracted lifetime.

Ammann, Michael W.; Walker, Andrew M.; Stackhouse, Stephen; Wookey, James; Forte, Alessandro M.; Brodholt, John P.; Dobson, David P.

2014-03-01

147

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

148

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

149

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

150

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.

151

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

152

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

153

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.

154

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

155

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

156

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

157

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

158

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

159

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

NASA Astrophysics Data System (ADS)

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

Manglik, Ajay

2006-07-01

160

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

NASA Technical Reports Server (NTRS)

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

Williams, David R.; Pan, Vivian

1992-01-01

161

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

162

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

163

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

164

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

165

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

166

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

167

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

168

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

169

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

170

Curvature, heat flow and normal stresses in two-dimensional models of mantle convection  

Microsoft Academic Search

Predictions of surface heat flow and normal stresses at the boundaries from two-dimensional finite-difference models of mantle convection in curvilinear coordinates are compared with similar predictions from plane layer models. Curvature effects are parametrized in terms of f, the ratio of the radii, or fa, the ratio of the areas, of the inner and outer bounding surfaces of the model

Gary T. Jarvis

1995-01-01

171

Lattice thermal conductivity of lower mantle minerals and heat flux from Earth's core  

PubMed Central

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

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

2011-01-01

172

Short time-scale heating of the Earth's mantle by ice-sheet dynamics  

Microsoft Academic Search

We have studied the possibility of short time-scale energy transfer from the ice sheet loading and unloading processes to the Earth's interior via viscous dissipation associated with the transient viscoelastic flow in the mantle. We have focussed on the magnitude of glacially induced deformations and the corresponding shear heating for an ice sheet of the spatial extent of Laurentide region

Ladislav Hanyk; Ctirad Matyska; D. A. Yuen

2005-01-01

173

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

174

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

175

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

176

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

NASA Astrophysics Data System (ADS)

The thermal evolution of terrestrial planets is controlled by secular cooling and internal heating due to the decay of radiogenic isotopes, two processes which are equivalent from the standpoint of convection dynamics. Few studies have been devoted to the intrinsic characteristics of this form of convection, which are dominated by instabilities of a single boundary layer and which involve a non-isentropic interior thermal structure. Laboratory studies of such convection have been plagued by considerable technical difficulties and have been mostly restricted to aqueous solutions with moderate values of the Prandtl number, contrary to planetary mantles. Here, we describe a new laboratory setup to generate internal heating in controlled conditions based on microwave (MW) absorption. The advantages of our technique include, but are not limited to: (1) a volumetric heat source that can be localized or distributed in space, (2) selectively heating part of the volume with time varying intensity and space distribution. Our tank prototype had horizontal dimensions of 30 cm × 30 cm and 5 cm height. A uniform and constant temperature was maintained at the upper boundary by an aluminium heat exchanger and adiabatic conditions were imposed at the tank base. Experimental fluids were hydroxyethylcellulose - water mixtures whose viscosities were varied within a wide range depending on concentration. Experimental Prandtl numbers were set at values larger than 100. Thermochromic Liquid Crystals (TLC) were used to visualize the temperature field, and the velocity field was determined using Particle Image Velocimetry (PIV). The Rayleigh-Roberts number was varied from 105 to 107. We also conducted numerical simulations in 3D cartesian geometry using Stag-3D (Tackley 1993) to reproduce the experimental conditions, including the tank aspect ratio and the temperature dependence of physical properties. We observed that convection is driven by cold descending plumes generated at the upper boundary that induce a diffuse upward return flow. Within experimental error, excellent agreement was found between calculated and observed vertical profiles of the horizontally-averaged temperature. Calculations and experiments led to the same velocity field characteristics including the number of instabilities in the upper boundary layer and root mean square velocity values. P. J. Tackley, Geophys. Res. Lett. 20, 2187-2190 (1993).

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

2014-05-01

177

Effects of various lithospheric yield stresses and different mantle-heating modes on the breakup of the Pangea supercontinent  

NASA Astrophysics Data System (ADS)

simulations of three-dimensional spherical mantle convection were performed to investigate the effects of various lithospheric yield stresses and two different mantle-heating modes (i.e., mixed heating from the bottom and interior and purely internal heating) on the breakup of the Pangea supercontinent and the subsequent continental drift for the past 200 Myr. Results show that the continental breakup and subsequent continental drift are accomplished in mantle convection models with two different heating modes. This implies that active upwelling plumes from the core-mantle boundary are not necessarily required for the breakup of Pangea. In addition, I found that the continental breakup is only realized when choosing a moderate value of the yield stress (~120 MPa). The bound on the yield stress derived in the present study will potentially enable the self-consistent reconstruction of continental breakup and drift as well as the accompanying pattern on mantle convection since 200 Ma.

Yoshida, Masaki

2014-05-01

178

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

179

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

180

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

181

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

182

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

183

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

184

Carbon exchange between the mantle and the crust, and its effect upon the atmosphere - Today compared to archean time  

NASA Technical Reports Server (NTRS)

Estimates of the midocean ridge mantle carbon flux, whose exchange of carbon with the earth's surface has over geological time influenced atmospheric CO2, can be made by estimating concentration ratios of carbon to helium in hydrothermal fluids and tholeiitic glasses, followed by their multiplication by the oceanic primordial He-3 flux. A net carbon flux from the mantle of 1 billion moles/yr would require less than 700 million years to generate the present day crustal carbon inventory. It is deduced that the atmosphere of 3 billion years ago contained at least two orders of magnitude more CO2 than it does today.

Des Marais, D. J.

1985-01-01

185

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

186

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

187

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

188

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

189

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

190

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

191

Impact heating and coupled core cooling and mantle dynamics on Mars  

NASA Astrophysics Data System (ADS)

giant impact basins of mid-Noachian age have been identified on Mars, and the global magnetic field appears to have vanished at about the same time. The impacts that formed these basins delivered a large amount of heat to the planetary interior, modified the pattern of mantle convection, and suppressed core cooling, potentially contributing to the cessation of dynamo activity. Here we investigate the thermal evolution of Mars in response to the largest basin-forming impacts, using a new method of coupling models of mantle convection with parameterized core cooling. We find that heating by a large impact generates a strong hemispheric upwelling in the mantle, which quickly spreads into a warm layer beneath the stagnant lid. The impact heating of the core leads to spherically symmetric stratification of the core; the outermost layers are strongly heated. This acts as a thermal "blanket" that prevents cooling of the interior and shuts down core convection. While the hottest part of the thermal blanket in the outermost core disappears relatively quickly, dynamo activity does not restart for ~100 Myr, and the core does not return to a fully convective state for ~1 Gyr following the impact.

Roberts, James H.; Arkani-Hamed, Jafar

2014-04-01

192

The influence of mantle internal heating on lithospheric mobility: Implications for super-Earths  

NASA Astrophysics Data System (ADS)

Super-Earths, a recently discovered class of exoplanets, have been inferred to be of a similar rock and metal composition to the Earth. As a result, the possibility that they are characterised by the presence of plate tectonics has been widely debated. However, as the super-Earths have higher masses than Earth, it is assumed that they will also have higher Rayleigh numbers and non-dimensional heating rates. Accordingly, we conduct a systematic 2D study to investigate the influence of these parameters on the surface behaviour of mantle convection. The main focus of our work considers the response of surface motion to the mantle's internal heating. However, we also include an analysis of other parameters scaling with planet mass, such as viscosity. In agreement with the findings of Valencia and O'Connell (2009) and van Heck and Tackley (2011) we find plate-like surface mobilisation for increased Rayleigh numbers. But increasing the internal heating leads to the formation of a strong stagnant-lid because the mantle heating effects thermally activated viscosity. Additionally, viscosity is affected by the increased pressures and temperatures of super-Earths. In total, our findings indicate that surface mobility will likely be reduced on super-sized Earths. Our numerical models show that the interior temperature of the convecting system is of vital importance. In planets with a hotter interior plate tectonics is less likely.

Stein, C.; Lowman, J. P.; Hansen, U.

2013-01-01

193

Mantle Convection  

NSDL National Science Digital Library

This page discusses thermal convection as it applies to the Earth's mantle and includes three QuickTime movies for three different cases of convection: heating from below, heating from within, and a combination of the two.

Schmeling, H.; Goethe Universitat, Facheinheit G.

194

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

USGS Publications Warehouse

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

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

1997-01-01

195

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

196

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

197

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

198

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

199

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

200

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

201

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

202

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

203

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

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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

212

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

213

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

214

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

215

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

216

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

217

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

218

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

219

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

220

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

221

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

222

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

223

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

224

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

225

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

226

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

227

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

228

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

229

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

230

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

231

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

232

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

233

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

234

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

Microsoft Academic Search

Estimates of conductive heat flow across the core\\/mantle boundary suggest high heat flow values of 7-14 TW for a core\\/mantle temperature drop of 1000-1800 K. This level of heat flow predicts an inner core age of less than 1-2 Ga. However, some models of core\\/mantle thermal evolution predict late onset of inner core crystallization may require implausibly high core temperatures

J. C. Lassiter

2006-01-01

235

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

236

Non-linear effects from variable thermal conductivity and mantle internal heating: implications for massive melting and secular cooling of the mantle  

Microsoft Academic Search

The temperature-dependence of the phonon portion of the thermal conductivity k(T,P) devised by Hofmeister [Science 283 1699-1706] decreases with temperature, the same as in the dependence of mantle viscosity. Such a functional relationship of ?k\\/?T<0, when coupled with internal heating would present a situation very conducive for positive feedback action. On the other hand, the photon dependence of the conductivity

A. P. van den Berg; D. A. Yuen; J. R. Allwardt

2002-01-01

237

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

NASA Astrophysics Data System (ADS)

We present thermal data from 473 oil exploration wells in Australia and New Zealand. Approximately 2300 bottom-hole temperatures are corrected to form a homogeneous set along with 86 temperatures from reservoir tests. Thermal conductivity profiles are estimated from a set of geophysical well logs using a recently developed neural network approach. Retaining wells in which temperature and thermal conductivity data overlap over an interval greater than 1000 m, we estimate 10 heat flow values in the Taranaki basin of New Zealand and 270 values in the northwestern, western, and southern margins and in the intracontinental Canning basin of Australia. The values are in the range 30-80 mW m-2. As a result of several differences in the data and methods, our heat flow values are 10-20 mW m-2 lower compared to previously published estimates for the same wells in New Zealand. For Australia, our values are consistent with previously measured values and trends in the continental and marine regions. On the northwestern and southeastern margins, we interpret the variations as reflecting changes in the nature of the underlying basement. Consistent with onshore data, it is inferred that the Archean crust is depleted in radiogenic elements compared to Proterozoic regions and that recent volcanism affects the eastern Paleozoic area. After removing from surface heat flow the sediment contributions, including a permanent radiogenic heat component and a transient sedimentation effect, a simple crustal model suggests that mantle heat flow on the continental margin bordering the Pilbara craton is higher than below the craton itself. Moreover, heat flow corrected for the sediment contributions is markedly lower in the Petrel intracontinental basin than in the adjacent margin, although the crust is thinner below this latter region. As both are underlaid by the same basement, this observation may indicate that the mantle contribution is also higher below that margin. Such a higher mantle heat flow on old continental margins is consistent with experiments of fluid convection below an insulating lid and suggests that the thermal regime of the continental lithosphere never returns to its prerift state, as usually assumed by several thermomechanical models of evolution of continental margins.

Goutorbe, Bruno; Lucazeau, Francis; Bonneville, Alain

2008-05-01

238

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

239

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

240

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

241

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

242

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

243

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

244

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

245

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

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

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

254

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

255

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

256

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

257

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

258

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

259

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

260

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

261

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

262

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

263

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

264

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

265

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

266

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

267

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

268

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

269

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

270

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

271

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

272

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

273

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

274

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

275

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

276

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

277

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

278

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

279

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

280

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

281

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.

282

Ancient dynamos of terrestrial planets more sensitive to core-mantle boundary heat flows  

NASA Astrophysics Data System (ADS)

The early dynamos of Earth and Mars probably operated without an inner core being present. They were thus exclusively driven by secular cooling and radiogenic heating, whereas the present geodynamo is thought to be predominantly driven by buoyancy fluxes which arise from the release of latent heat and the compositional enrichment associated with inner core solidification. The impact of the inner core growth on the ancient geodynamo has been discussed extensively but is still controversial. The Martian dynamo stopped operating more than 4 Gyr ago but left its signature in the form of a strong crustal magnetization that is much stronger in the southern than in the northern hemisphere. This dichotomy can, for example, be explained by a dynamo predominantly operating in the southern hemisphere due to a heterogeneous heat flux through the core-mantle boundary (CMB). The early Martian dynamo may also have operated without an inner core being present. Here we explore the impact of lateral CMB heat flux variations on dynamos with and without an inner core by comparing numerical dynamos driven by homogeneous internal sources or by bottom buoyancy sources, arising from the inner core boundary (ICB). Three different CMB heat-flux patterns are tested that either break the northern/southern or the azimuthal symmetry. In the dynamos driven by internal heating a rather small CMB heat-flux heterogeneity suffices to break internal symmetries and leads to boundary-induced structures and different field strengths. The effect is much smaller for dynamos driven by ICB buoyancy sources. Our results indicate that the field intensity and morphology of the ancient dynamos of Earth or Mars were more variable and more sensitive to the thermal CMB structure than the geodynamo after onset of inner core growth.

Hori, K.; Wicht, J.; Dietrich, W.

2014-08-01

283

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

284

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

285

Heat Flow on Hotspot Swells Reflect Fluid Flow Masking Potential Variations in Mantle Heat Flux  

NASA Astrophysics Data System (ADS)

The origin of hotspot swells is poorly understood. Heat flow data collected on hotspot swells have been used to argue for and against sublithospheric thermal anomalies. The presence of sublithospheric thermal anomalies has been inferred from interpretations of anomalously high heat flow determinations, whereas the contention that hotspot swells result from normal melting processes within the lithosphere is based on `normal' heat flow values. These arguments depend in part on the choice of a thermal reference model, but more importantly assume conductive heat transfer through the lithosphere. We provide evidence that heat flow measurements collected on hotspot swells likely reflect shallow fluid flow rather than deep thermal variations within or at the base of the lithosphere. Discriminating between environments where heat is transferred conductively or convectively requires closely spaced heat flow determinations (1-2 km) collocated with seismic reflection profiles. Only Hawaii and Reunion have surveys meeting these requirements. The Hawaiian survey consists of two profiles, one north of Oahu and one north of Maro Reef. The Reunion survey also consists of two profiles, both north of Mauritius. These heat flow profiles reveal greater scatter than anticipated with spectral peaks on the order of 10 km consistent with fluid flow. Root mean square variations along the Oahu and Maro Reef profiles are 15 and 5 mW m-2, respectively, and along both Reunion profiles are about13 mW m-2. Coupled heat and fluid flow models demonstrate that thermal buoyancy due to bathymetric relief is capable of driving significant fluid flow that may suppress the background thermal field. These models are consistent with heat flow patterns observed at individual seamounts and oceanic basement highs that are more easily sampled and characterized than large hotspot swells. We caution that the ability of fluid flow to mask variations in sublithospheric heat flux make surface heat-flow values a poor discriminator between geodynamic models for hotspot swells.

Harris, R. N.; McNutt, M. K.

2004-12-01

286

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

287

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

288

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

289

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

290

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

291

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

292

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

293

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

294

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

295

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

296

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

297

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

298

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

299

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

300

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

301

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

302

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

303

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

304

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

305

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

306

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

307

The role of the heating mode of the mantle in intermittent reorganization of the plate velocity field  

NASA Astrophysics Data System (ADS)

The geological record indicates that stages of relatively steady plate motion have been punctuated by comparatively brief periods in which plate velocities have reorganized. The distribution of buoyancy sources in the mantle has generally been regarded as evolving too slowly to explain these rapid transitions in plate velocity. We investigate the feedback between mantle convection and plate velocity using 2-D and 3-D mantle convection models that incorporate mobile dynamic plates. We focus on the influence of internal heating in the mantle and consider the effect of mantle viscosity stratification and different plate geometries on the plate velocity time dependence. As either the Rayleigh number or the internal heating rate is increased to magnitudes approaching mantle values, the record of the plate motion from our calculations becomes characterized by intermittent changes in direction. This behaviour is a result of the influence of plates on heat loss from the inherently unsteady, internally heated convecting system. Plate motion instills a pattern of organization on the underlying convection that reflects the plate geometry and results in the formation of sheet-like downwelling structures at convergent plate boundaries in both 2-D and 3-D calculations (in contrast, upwellings in 3-D models are not sheet-like). The role of the sheet-like downwellings is critical in the observed episodic reorganization of the plate velocities. Warm material below the plates is entrained by plate motion into regions enveloping the downwelling sheets. During periods of fairly steady plate motion, buoyancy associated with the build-up of heat around the downwelling sheets leads to the creation of an unstable convection pattern. This build-up of heat is dramatic in calculations with mantle-like internal heating rates and resists continued long-term plate motion towards mature downwellings. When there are limitations on the degree of freedom of the direction of plate movement, such as in 2-D models, these effects become even more pronounced. Accordingly, the effect of plates on mean global thermal quantities is more dramatic in 2-D calculations than it is in 3-D calculations. Nevertheless, 3-D calculations incorporating plates of different sizes do exhibit rapid reorganizations in their convection patterns as the pull of young slab-like features supersedes the pull of mature downwelling sheets. We compare the timing and frequency of the reorganization events in our calculations with the general characteristics of plate motions determined from plate reconstruction studies.

Lowman, Julian P.; King, Scott D.; Gable, Carl W.

2003-02-01

308

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

309

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

310

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

311

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.

312

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

313

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

314

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

315

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

316

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

317

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

318

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

PubMed Central

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

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

2007-01-01

319

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

PubMed

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

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

2007-09-01

320

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

321

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

322

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

323

Modelling the effects of internal heating in the core and lowermost mantle on the earth’s magnetic history  

NASA Astrophysics Data System (ADS)

Recently, an incompatible-element enriched reservoir, bearing a high degree of radioactive heating, has been proposed to exist at the base of the mantle. This scenario has been discussed based on parameterized thermal and magnetic models of the core [Buffett, B.A., 2002. Estimates of heat flow in the deep mantle based on the power requirements for the geodynamo. Geophys. Res. Lett. 29(12), 7], as well as on geochemical grounds [Tolstikhin, I., Hofmann, A.W., 2005. Early crust on top of the Earth's core. Phys. Earth Plan. Int., 148, 109-130; Boyet M., Carlson, R.W., 2005. Nd142 Evidence for early ( >4.53 Ga) global differentiation of the sillicate earth. Science 309, 576-581]. A high degree of radioactivity at the base of the mantle [ Buffett, B.A., 2003. The thermal state of Earth's core. Science 299, 1675-1677], or alternatively the presence of radioactivity in the core [e.g., Labrosse, S., 2003. Thermal and magnetic evolution of the Earth's core. Phys. Earth Plan. Int. 140, 127-143; Nimmo F., Price, G.D., Brodholt, J., Gubbins, D., 2004. The influence of potassium on core and geodynamo evolution. Geophys. J. Int. 156, 363-376], have been proposed as means to allow sufficient buoyancy to power the geodynamo and maintain a magnetic field throughout most of the Earth's history as palaeomagnetic records indicate [ McElhinny, M.W., Senanayake, W.E., 1980. Paleomagnetic evidence for the existence of the geomagnetic field 3.5 Ga ago. J. Geophys. Res. 85, 3523-3528; Hale, C.J., D.J. Dunlop, 1984. Evidence for an early Archean geomagnetic field: a paleomagnetic study of the Komati Formation, Barberton Greenstone Belt, South Africa. Geophys. Res. Lett. 11, 97-100], while maintaining a sufficiently high temperature in the core. The present paper analyzes the consequences of internal heating in the core and the lowermost mantle on the core's magnetic history using numerical simulations of convection in the mantle coupled to an energy balance model for the core. This method allows feed-back at each time step between the cooling histories in the core and mantle through the heat flux and temperature at the core-mantle boundary (CMB). We employ a two dimensional, spherical-axisymmetric model of convection in the Earth's mantle, coupled to a heat reservoir model for the core. We calculate at each time-step the entropy available for ohmic dissipation in the core and use this result to estimate the intensity of a magnetic field generated by geodynamo action. In agreement with Nimmo et al. [Nimmo F., Price, G.D., Brodholt, J., Gubbins, D., 2004. The influence of potassium on core and geodynamo evolution. Geophys. J. Int. 156, 363-376], we find that the presence of 300 ppm potassium in the core allows for a magnetic field to have existed over the lifetime of the Earth with a reasonable final value for the temperature at the CMB. Almost all of the models with high internal heating at the base of the mantle exhibit warming of the core throughout much of the Earth's thermal history, a state that would prohibit a functioning geodynamo. In one simulation, we are driven to a scenario where the inner core has existed over the lifetime of the Earth only to gradually melt and then refreeze, with a functioning geodynamo existing for a short time. We conclude that careful tuning of the mantle viscosity, internal heating rate and initial core temperatures would be required in order to achieve a magnetic field over the lifetime of the Earth in the presence of a basal layer with a high degree of internal heating and therefore such a scenario must be better constrained before it could present itself as viable.

Costin, S. O.; Butler, S. L.

2006-08-01

324

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

325

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

326

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

327

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

328

Three-dimensional mantle convection simulations with a low-viscosity asthenosphere and the relationship between heat flow and the horizontal length scale of convection  

Microsoft Academic Search

Numerical mantle convection simulations show that depth-dependent viscosity can increase the flow wavelength. A recent analysis demonstrates that flow channelization into a low-viscosity region lowers lateral dissipation. This allows long wavelength flow to more efficiently cool the interior mantle. We present three-dimensional, mixed heating mantle convection simulations with a thin low-viscosity channel for a range of aspect ratios to test

Tobias Höink; Adrian Lenardic

2008-01-01

329

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

330

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

331

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

332

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

333

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

334

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

335

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

336

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

337

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

338

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

339

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

340

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

341

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

342

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

343

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

344

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

345

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

346

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

347

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

348

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

349

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

350

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

351

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

352

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

353

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

354

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

355

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

356

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

357

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

358

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

359

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

360

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

361

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

362

Experimental Study of Slab-Mantle Geochemical Exchange in Subduction Zones  

NASA Astrophysics Data System (ADS)

Aqueous fluids derived from subducting oceanic crust play an important role in the material transport leading to the production or arc lavas, and in the long-term chemical evolution of the Earth's mantle and crust. In order to determine the geochemical evolution of both the subducting slab and the overlying mantle wedge, a series of dehydration/hydration experiments was carried out at conditions of 0.8-4.0 GPa and 650-900° C appropriate for subduction zones. Blueschist facies rocks/minerals, and olivine (Fo90) were used for starting materials, as analogue materials of slab and mantle, respectively. Finely ground metabasalt (H2O = 5.9 wt%) and glaucophane (H2O = 2.3 wt%) were separately sealed in gold capsules with an olivine grain (1mm diameter), and then run in a piston-cylinder apparatus. Polished sections of run products were observed and analyzed for major element compositions with an electron micro-probe. Trace elements of selected run-products were determined using an ion probe (Cameca-5f). At subsolidus conditions, the metabasalt was transformed into amphibolite-facies mineral assemblages containing Mg-ilmenite at <1.5 GPa, and eclogite-facies assemblages containing rutile at >1.5 GPa. Glaucophane was transformed into the mineral assemblage of Na-Cpx, Opx +/- garnet. Garnets formed in the slab portion show low-LREE/HREE and higher-HREE contents when compared with the starting materials. In all subsolidus experiments, Al-rich silicate glasses, which could be quenched aqueous fluids, were observed between mineral grain boundaries in the slab portions. The fluids at 3.0 GPa show high-LREE/HREE, and higher-LILE and lower-HREE contents. In contrast, the quenched fluids for <1.5 GPa, which did not coexist with garnet, do not show strong depletion in HREE. Negative Nb anomalies were observed in the quenched fluids in the metabasalt experiments, but this anomaly does not appear to exist in the glaucophane experiments. The behavior of the HREE and HFSE is consistent with the existence of garnet and Ti-oxides (rutile and ilmenite) in the slab portion of the experiments. The fluids should therefore be enriched in SiO2, LILE and LREE. Mineral zones were observed on olivine grains near the initial olivine-slab interface. These reaction zones consisted of talc and enstatite layers at < 800° C, and an enstatite layer only at > 800° C. Because the enstatite layers are strongly LILE and LREE-enriched compared with the primary olivine, the reacted layers are thought to have been formed by chemical interaction between olivine and SiO2-riched aqueous fluids which were capable of also delivering these other trace elements. As a consequence of this transfer, the chemical compositions of the descending slab and the overlying mantle could be considerably depleted and enriched, respectively, in SiO2, LILE and LREE during the process of subduction.

Iizuka, Y.; Nakamura, E.; Kobayashi, K.

2001-12-01

363

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

364

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

365

Crustal composition and mantle heat flow: Implications from surface heat flow and radiogenic heat production in the Variscan Erzgebirge (Germany)  

Microsoft Academic Search

From an enlarged data set of temperature logs and thermal conductivity measurements, surface heat flow (qs) in the Erzgebirge was determined to range from 61 to 112 mWm-2. U-Th-K2O data show that the heat flow pattern is controlled to first order by the occurrence of high heat production Variscan granites within a metamorphic basement. Highest heat flow correlates with granite

Andrea Förster; Hans-Jürgen Förster

2000-01-01

366

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

367

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

368

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

369

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

370

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

371

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

372

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

373

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

374

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

375

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

376

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

377

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

378

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

379

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

380

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

381

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

382

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

383

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

384

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

385

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

386

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

387

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

388

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

389

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

390

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

391

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

392

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

393

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

394

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

395

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

396

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

397

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

398

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

399

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

400

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

401

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

402

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

403

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

404

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

405

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

406

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

407

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

408

Heat flow in the laser-heated diamond anvil cell and the thermal conductivity of iron-bearing oxides and silicates at lower mantle pressures and temperatures  

NASA Astrophysics Data System (ADS)

The thermal conductivity of minerals in the lowermost mantle controls the total heat flow across the core-mantle boundary and is critical for the thermal evolution of the Earth. However, lower mantle thermal conductivity values and their pressure, temperature, and compositional dependencies are not well known. Here we present our recent progress combining 3D models of heat flow in the laser-heated diamond cell (LHDAC) with laboratory measurements of hotspot temperature distributions to assess the thermal conductivity of lower mantle minerals as a function of pressure and temperature. Using our numerical model of heat flow in the LHDAC, central hotspot temperature and radial and axial temperature gradients are calculated as a function of laser power, sample thermal conductivity, and sample geometry. For a given geometry, the relationship between peak sample temperature and laser power depends on the sample thermal conductivity. However, quantifying the experimental parameters sufficiently to precisely determine an absolute value of sample thermal conductivity is difficult. But relative differences in thermal conductivity are easily inferred by comparing the slopes of differing temperature vs. laser power curves measured on the same system. This technique can be used to measure the pressure dependence of thermal conductivity for minerals at lower mantle conditions. We confirm the effectiveness of this approach by measuring the pressure slope of thermal conductivity for MgO between 10 and 30 GPa. MgO retains the B1 phase throughout the experimental pressure range, and existing experimental measurements and theoretical calculations are in good agreement on the pressure- and temperature- dependence of the thermal conductivity of MgO. We also use this technique to measure the relative thermal conductivity of high pressure assemblages created from San Carlos olivine starting material. Both MgO and (Mg,Fe)2SiO4 materials show a shallower temperature vs. laser power slope as a function of pressure as expected for increasing thermal conductivity. In addition, olivine undergoes a series of phase transformations which changes its thermal behavior at upper mantle conditions (10-20 GPa) where olivine and wadsleyite are stable compared with lower mantle (25-30 GPa) conditions where the olivine transforms to a perovskite + oxide assemblage.

Rainey, E. S.; Kavner, A.; Hernlund, J. W.; Pilon, L.; Veitch, M.

2012-12-01

409

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

410

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

411

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

412

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

413

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

414

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

415

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

416

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

417

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

418

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

NASA Astrophysics Data System (ADS)

Estimates of conductive heat flow across the core/mantle boundary suggest high heat flow values of 7-14 TW for a core/mantle temperature drop of 1000-1800 K. This level of heat flow predicts an inner core age of less than 1-2 Ga. However, some models of core/mantle thermal evolution predict late onset of inner core crystallization may require implausibly high core temperatures in the Archaean [1]. Sequestration of heat producing elements at the base of the mantle may reduce core/mantle heat flow and increase the age of the inner core [1]. In addition, Boyet and Carlson [2] reported ^{142}Nd excesses in terrestrial samples relative to chondrites, and proposed that an enriched reservoir produced by early differentiation may be "hidden" at the base of the mantle, and that this reservoir could contain up to 43% of the Earth's heat producing elements. The runaway core thermal evolution predicted by Buffett [1] for models with a relatively young inner core results from two assumptions. First, Buffett assumes that core/mantle heat flow has decreased ~3x since the onset of inner core crystallization, because the power required to drive the geodynamo today is much lower than prior to inner core crystallization. Second, Buffett treats the core/mantle boundary as a thermal boundary with strongly temperature-dependant viscosity, so that relatively small increases in core temperature result in a large decrease in boundary layer thickness and increase in core/mantle heat flow. If the core/mantle boundary is a chemical rather than purely thermal boundary the boundary layer thickness need not be time- or temperature-dependant. As a result, core/mantle heat flow is roughly linearly proportional to core-mantle ?T, rather than exponential. Provided that modern core/mantle heat flow is greater than the heat flow required to drive the geodynamo in the absence of inner core crystallization, no significant secular evolution in core/mantle heat flow is required. Given these assumptions and a present-day core/mantle ?T of ~1000 K, the Earth's core would have been ~500 K hotter at 3.5 Ga than it is today, and core/mantle heat flow would have ranged from ~10 TW at 3.5 Ga to ~8 TW today. This is a much more moderate evolution of core temperature and heat flow than predicted by earlier models. Sequestration of heat producing elements within D" may lower core/mantle heat flow and the magnitude of core temperature change over time. For example, sequestration of 9 TW heat production within D", as suggested by [2], would reduce present-day core/mantle heat flow from ~7.8 to ~3.6 TW, using the same parameters as above. However, radiogenic heat production was much higher earlier in Earth history than today (~2.8x current values at 3.5 Ga). Sequestration of more than ~30% of the Earth's heat producing elements (equivalent to 6 TW of present-day heat production) at the core/mantle boundary will result in negative core/mantle heat flow in the early Archaean unless convection within D" greatly increases the efficiency of heat transport. Negative heat flow is contradicted by the existence of Earth's magnetic field since at least 3.5 Ga. Although heat production within D" will result in lower early core temperatures, the impacts on more recent core/mantle heat flow and estimates of inner core age are relatively minor. Core/mantle heat flow has likely remained relatively constant throughout Earth history (in the absence of radiogenic heat production in D") or has increased as the amount of D" heat production has declined due to radioactive decay. [1] BA Buffett, GRL 29, 10.1029/2001GL014649, 2002. [2] M Boyet, RW Carlson, Science 309, 576-581, 2005.

Lassiter, J. C.

2006-12-01

419

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

420

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

421

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

422

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

423

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

424

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

425

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

426

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

427

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

428

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

429

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

430

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

431

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

432

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

433

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

434

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

435

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

436

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

437

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

438

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

439

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

440

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

441

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

442

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

443

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

444

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

445

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

446

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

447

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

448

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

449

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

450

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

451

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

452