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1

Observer-based monitoring of heat exchangers.  

PubMed

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

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

2008-01-01

2

Biofouling monitors for noncylindrical OTEC heat exchanger tubes  

SciTech Connect

Heat-transfer monitors (HTMs) have been used to measure the reduction in the seawater heat-transfer coefficient due to buildup of biofouling and corrosion products inside circular tubes of shell-and-tube heat exchangers being developed for ocean thermal energy conversion (OTEC) plants. For OTEC heat exchangers (HXs) with other tube geometries, special, modified HTMs, which we call STMs, are being sought. The analytical approaches and calibration results to date are summarized for STMs of two types: (i) an STM simulating a rectangular seawater passage in a compact, aluminum, plate-fin HX, and (ii) an STM for a helical stainless-steel tube. The development of type 1 has been successful. A software change is needed for type 2.

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

1982-08-01

3

Heat transfer monitor for measurements of fouling of industrial heat exchangers  

SciTech Connect

A Heat Transfer Monitor (HTM) is a sensitive device that quantifies development of fouling on heat exchanger surfaces in terms of degradation in the heat transfer coefficient as fouling progresses. The Argonne HTM was originally developed by Carnegie-Mellon University for Ocean Thermal Energy Conversion (OTEC) applications and later modified by Argonne National Laboratory. The HTM has been used for the OTEC biofouling and corrosion studies at the Natural Energy Laboratory of Hawaii for the last four years. The monitor has produced consistent results with an accuracy of about 0.0035 K m/sup 2//kW (0.00002/sup 0/F.h.ft/sup 2//Btu). The major findings from the experimental investigation are: (a) periodic low level of 50 to 70 ppB of chlorination can remove and prevent biofouling, (b) biofouling for deep cold water is negligible, and (c) biofouling control methods for moderately enhanced surfaces are comparable to those for smooth surfaces.

Panchal, C.B.

1985-01-01

4

Heat Exchanger Monitoring and Its Application to Cleaning and Antifoulant Use  

E-print Network

Many refineries and chemical plants are presently experiencing considerable fuel savings and reduced maintenance costs as a result of their heat exchanger monitoring activities. Significant energy credits can be generated with proper applications...

Garcia, E.; Leach, S. H.; VanNostrand, W. L.

1983-01-01

5

Greywater heat exchanger  

SciTech Connect

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

Holmberg, D.

1983-11-21

6

Corrosive resistant heat exchanger  

DOEpatents

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

Richlen, Scott L. (Annandale, VA)

1989-01-01

7

Segmented heat exchanger  

SciTech Connect

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

8

Heat pipe array heat exchanger  

DOEpatents

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

Reimann, Robert C. (Lafayette, NY)

1987-08-25

9

Woven heat exchanger  

DOEpatents

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

Piscitella, R.R.

1984-07-16

10

Demonstration and Performance Monitoring of Foundation Heat Exchangers (FHX) in Ultra-High Energy Efficient Research Homes  

SciTech Connect

The more widespread use of Ground Source Heat Pump (GSHP) systems has been hindered by their high first cost, which is mainly driven by the cost of the drilling and excavation for installation of ground heat exchangers (GHXs). A new foundation heat exchanger (FHX) technology was proposed to reduce first cost by placing the heat exchanger into the excavations made during the course of construction (e.g., the overcut for the basement and/or foundation and run-outs for water supply and the septic field). Since they reduce or eliminate the need for additional drilling or excavation, foundation heat exchangers have the potential to significantly reduce or eliminate the first cost premium associated with GSHPs. Since December 2009, this FHX technology has been demonstrated in two ultra-high energy efficient new research houses in the Tennessee Valley, and the performance data has been closely monitored as well. This paper introduces the FHX technology with the design, construction and demonstration of the FHX and presents performance monitoring results of the FHX after one year of monitoring. The performance monitoring includes hourly maximum and minimum entering water temperature (EWT) in the FHX compared with the typical design range, temperature difference (i.e., T) across the FHX, and hourly heat transfer rate to/from the surrounding soil.

Im, Piljae [ORNL] [ORNL; Hughes, Patrick [ORNL] [ORNL; Liu, Xiaobing [ORNL] [ORNL

2012-01-01

11

Active microchannel heat exchanger  

Microsoft Academic Search

The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The active 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

Anna Lee Y. Tonkovich; Gary L. Roberts; Charles J. Call; Robert S. Wegeng; Yong Wang

2001-01-01

12

Development of a high-temperature erosion monitor for FBC (fluidized bed combustion) heat exchanger tubes  

SciTech Connect

Metal wastage in tubing of heat exchangers used in fluidized bed combustion (FBC) could affect plant operation and threaten the successful development of FBC technology. Monitoring of such wastage during operation would be very beneficial. The development of a high-temperature erosion monitor was undertaken as part of a larger program to understand and ameliorate wastage processes. Two sensor principles, i.e., electromagnetic acoustic and piezoelectric transducers based on time-of-flight measurements, were evaluated. Spatial restrictions and high-energy requirements of electromagnetic acoustic transducers favored piezoelectric transducers as a prototype. Requirements for good coupling between sensor and tubing led to the exploration of two methods for accomplishing this task: pressure coupling and brazing. Initial disappointments with brazing led to the construction of a pressure-coupled transducer that was tested successfully to temperatures of up to 500{degree}C. A brazing method to bond the lithium niobate crystal to stainless steel was finally perfected, but will require additional work for brazing to ferritic steel. The prototype pressure-coupled transducer also needs more development to compensate for the expansion of components and oxidation of coupling surfaces. 3 refs., 15 figs., 1 tab.

Reimann, K.J.

1990-05-01

13

40 CFR 63.104 - Heat exchange system requirements.  

Code of Federal Regulations, 2010 CFR

...which the cooling water exits the heat exchanger or group of heat exchangers. (5) A minimum...using a surrogate indicator of heat exchange system leaks shall comply...acceptable monitoring program are ion specific electrode monitoring, pH,...

2010-07-01

14

40 CFR 63.1409 - Heat exchange system provisions.  

Code of Federal Regulations, 2010 CFR

...which the cooling water exits the heat exchanger or group of heat exchangers. (5) A minimum...using a surrogate indicator of heat exchange system leaks shall comply...acceptable monitoring program are ion specific electrode monitoring, pH,...

2010-07-01

15

Direct fired heat exchanger  

DOEpatents

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

Reimann, Robert C. (Lafayette, NY); Root, Richard A. (Spokane, WA)

1986-01-01

16

Contact Heat Exchanger  

NASA Technical Reports Server (NTRS)

Fluid pressure controls contact between heat pipe and heat exchanger. Heat exchanger system in cross section provides contact interface between fluid system and heat pipe with easy assembly/disassembly of heat-pipe/ pumped-liquid system. Originally developed for use in space, new device applicable on Earth where fluid system is linked with heat pipe, where rapid assembly/disassembly required, or where high pressures or corrosive fluids used.

Fleming, M. L.; Stalmach, D. D.; Cox, R. L.

1985-01-01

17

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

18

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

19

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

20

Heat pipe array heat exchanger  

Microsoft Academic Search

A heat exchanger is described for transferring heat between a first fluid and a second fluid in an absorption refrigeration system comprising: a first shell having an inlet for receiving the first fluid at a first elevated temperature and an outlet for discharging the first fluid at a first reduced temperature with the shell defining a free flow path for

Reimann

1987-01-01

21

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

22

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

23

Monitoring of marine biofouling of titanium tube heat exchanger using a remote controlled thermal resistance method  

SciTech Connect

A study of the marine biofouling characteristics for titanium tubed heat exchangers has been carried out using a purpose designed test rig that enabled an accurate simulation of expected service conditions. Test rigs were constructed as self-contained remote controllable units that could be moved from site to site enabling fouling data to be obtained for different seawater environments. The quantification of fouling was performed using a combination of thermal resistance measurements, biofilm sample analyses and differential pressure measurements and data were obtained giving real-time fouling results for test periods of up to 90 days. Once fouling behavior had been characterized, tests were performed to investigate the efficacy of a number of chemical treatments by operating two rigs in parallel enabling the effects of chemical treatments to be directly compared to the fouling response on an untreated system. Fouling behavior was seen to be dependent upon seawater temperature, tube wall heat transfer conditions, seawater flow velocity and time of year as well as site location. Suitable chemical treatment programs to control biofouling by periodic biocide injection were identified. The results allowed the definition of heat exchanger operating parameters for in-service units that seek to minimize biofilm growth.

Aylott, P.J.; Stott, J.F.D.; Eden, R.D. [CAPCIS Ltd., Manchester (United Kingdom); Grover, H.K. [John Brown Engineers and Constructors Ltd., London (United Kingdom)

1995-10-01

24

Heat exchanger support system  

Microsoft Academic Search

A mounting system to interconnect a gas turbine heat exchanger with a gas turbine includes three interconnecting gas manifolds: one to receive cool compressed air from the engine, one to receive hot exhaust gas from the engine, and one to communicate heated intake air to the engine. The manifolds, acting in cooperation with a jointed support arm, allow the heat

Young

1978-01-01

25

A corrosive resistant heat exchanger  

DOEpatents

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

Richlen, S.L.

1987-08-10

26

Modular Heat Exchanger With Integral Heat Pipe  

NASA Technical Reports Server (NTRS)

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

Schreiber, Jeffrey G.

1992-01-01

27

Counterflow Regolith Heat Exchanger  

NASA Technical Reports Server (NTRS)

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

Zubrin, Robert; Jonscher, Peter

2013-01-01

28

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

29

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

30

Gaseous Nitrogen Heat Exchanger  

SciTech Connect

A heat exchanger is necessary to warm the gaseous nitrogen from the nitrogen dewar from 77 K to ambient temperature for use in the D-Zero Building. The original proposal would use an ambient air vaporizer, but further investigation led to the consideration and evaluation of other possibilities and a different final system. The vaporizer must be able to handle a flow rate of 1200 scfh at 30 psig on a continuous basis subject to local weather conditions. Upon consulting with a representative from Thermax Incorporated, So. Dartmouth, Massachusetts, four different heat exchanging systems were proposed. Their advantages and disadvantages are stated.

Kurita, C.H.; /Fermilab

1988-08-19

31

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

32

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

SciTech Connect

The overall purpose of this Nuclear Engineering Education Research (NEER) project was to integrate new, innovative, and existing technologies to develop a fault diagnostics and characterization system for nuclear plant steam generators (SG) and heat exchangers (HX). Issues related to system level degradation of SG and HX tubing, including tube fouling, performance under reduced heat transfer area, and the damage caused by stress corrosion cracking, are the important factors that influence overall plant operation, maintenance, and economic viability of nuclear power systems. The research at The University of Tennessee focused on the development of techniques for monitoring process and structural integrity of steam generators and heat exchangers. The objectives of the project were accomplished by the completion of the following tasks. All the objectives were accomplished during the project period. This report summarizes the research and development activities, results, and accomplishments during June 2001-September 2004. (1) Development and testing of a high-fidelity nodal model of a U-tube steam generator (UTSG) to simulate the effects of fouling and to generate a database representing normal and degraded process conditions. Application of the group method of data handling (GMDH) method for process variable prediction. (2) Development of a laboratory test module to simulate particulate fouling of HX tubes and its effect on overall thermal resistance. Application of the GMDH technique to predict HX fluid temperatures, and to compare with the calculated thermal resistance. (3) Development of a hybrid modeling technique for process diagnosis and its evaluation using laboratory heat exchanger test data. (4) Development and testing of a sensor suite using piezo-electric devices for monitoring structural integrity of both flat plates (beams) and tubing. Experiments were performed in air, and in water with and without bubbly flow. (5) Development of advanced signal processing methods using wavelet transforms and image processing techniques for isolating flaw types. (6) Development and implementation of a new nonlinear and non-stationary signal processing method, called the Hilbert-Huang transform (HHT), for flaw detection and location. This is a more robust and adaptive approach compared to the wavelet transform. (7) Implementation of a moving-window technique in the time domain for detecting and quantifying flaw types in tubular structures. A window zooming technique was also developed for flaw location in tubes. (8) Theoretical study of elastic wave propagation (longitudinal and shear waves) in metallic flat plates and tubing with and without flaws. (9) Simulation of the Lamb wave propagation using the finite-element code ABAQUS. This enabled the verification of the experimental results. The research tasks included both analytical research and experimental studies. The experimental results helped to enhance the robustness of fault monitoring methods and to provide a systematic verification of the analytical results. The results of this research were disseminated in scientific meetings. A journal manuscript was submitted for publication. The new findings of this research have potential applications in aerospace and civil structures. The report contains a complete bibliography that was developed during the course of the project.

Belle R. Upadhyaya; J. Wesley Hines

2004-09-27

33

Heat transfer enhancement in heat exchangers  

Microsoft Academic Search

In the power generation industry, high performance heat exchangers are needed to promote substantial improvements in effective utilization of waste heat in low temperature heat recovery applications. High performance heat exchangers are also seriously needed in low temperature power and refrigeration cycles that operate on renewable base energy sources such as ocean thermal energy conversion, geothermal and solar energy systems.

Ohadi

1991-01-01

34

Heat-Exchanger/Heat-Pipe Interface  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

35

Heat pipe heat exchanger design considerations  

Microsoft Academic Search

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

K. T. Feldman; D. C. Lu

1976-01-01

36

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

37

Preliminary analysis of heat pipe heat exchangers for heat recovery  

Microsoft Academic Search

A preliminary analysis of fin tube heat pipe heat exchangers for air-to-air heat recovery was conducted. The analysis uses conventional heat exchanger design techniques and a new heat pipe design technique which includes probabilistic design of artery wick heat pipes. The heat transfer capability of the heat pipes may be matched with that of the finned tubes in order to

J. O. Amode; K. T. Feldman

1975-01-01

38

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

39

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

40

High heat flux single phase heat exchanger  

Microsoft Academic Search

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

Javier A. Valenzuela; Michael G. Izenson

1990-01-01

41

Optimization of Heat Exchanger Cleaning  

E-print Network

decrease models of the heat recovery decay. A mathematical comparison of mechanical and chemical cleaning of heat exchangers has identified the most significant parameters which affect the choice between the two methods. INTRODUCTION In most... can be somewhat mitigated by periodic chemical or mechanical cleaning of the exchanger surface, and by the addition of antifoul ants. The typical decay in heat recovery capabil ity due to fou 1i ng and restoration afte r heat exchanger cleaning...

Siegell, J. H.

42

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

43

Heat exchange system for recycling stack heat  

Microsoft Academic Search

A heat exchange system is described for recycling waste heat leaving a building stack to supply heat to incoming fresh air or temper stored water of the building water storage system, wherein the building has a source of heat at constant temperature, such as a cooking facility, from which air conveying waste heat is drawn and impelled through a stack

Giuffre

1980-01-01

44

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

45

Compact heat exchanger design progress  

Microsoft Academic Search

Development of compact plate type heat exchangers for OTEC plants is reviewed. The heat exchangers have horizontal, single pass water flow, vertical downflow condenser, and vertical upflow boiler passages. The design lends itself to many variations in type of water side configuration, and in boiling and condensing surface design. It makes high heat transfer coefficients possible, along with low pressure

J. H. Anderson Jr.; P. B. Pribis

1979-01-01

46

Two-stage heat exchanger  

Microsoft Academic Search

Improved furnaces are described in which secondary and tertiary heat exchanges are incorporated into new and existing hot-air furnace systems for controlled cooling of hot combustion products by co-current and countercurrent heat exchanges. Hot combustion products are cooled to a temperature at which latent heat of water vapor contained in combustion gases are substantially recovered. In one embodiment of our

J. C. Overall; O. O. Schaus

1981-01-01

47

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

48

Heat pipe heat exchanger for heat recovery in air conditioning  

Microsoft Academic Search

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5

Mostafa A. Abd El-Baky; Mousa M. Mohamed

2007-01-01

49

Heat exchange system for recycling waste heat  

Microsoft Academic Search

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

A. A. Giuffre; A. F. Giuffre

1982-01-01

50

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

51

Approximate calculations for heat exchangers  

Microsoft Academic Search

Estimates were developed for the total heat transfer coefficient for various types of heat exchangers. These estimates were not meant to replace more accurate calculations for individual heat exchangers, but to provide quick approximations for situations in which great accuracy was not required. The heat transfer coefficients k (in kcal\\/m²\\/hr\\/°C) were calculated based on assumed average values for input and

Matz

2008-01-01

52

Flow maldistribution in heat exchangers  

Microsoft Academic Search

Based on the study of gross flow maldistribution in an experimental electrical heater, this paper presents the effect of flow nonuniformity on the performance of heat exchangers. First, it is shown that it is much more important to understand maldistributions for electrical heaters than for two-fluid heat exchangers. The study of the flow distribution in a particular heater shows that

S. Lalot; P. Florent; S. K. Lang; A. E. Bergles

1999-01-01

53

Development of Monitoring Control and Fuzzy Control Test of Finned-Tube Heat-Exchanger Test-Board  

E-print Network

eminent capacity of noise proof and zero stabilization, and temperature auto-compensation. The pressure differences are recorded by PCI1713 analog input card with pressure difference transmitting instrument in this finned-tube heat-exchanger test... of possible mistakes in running process: one kind is foreseeable mistakes and other kind is unforeseen mistakes. Further more foreseeable mistakes are composed of computer running mistakes and man-made mistakes. The computer running mistakes have many...

Chen, Y.; Zhang, J.; Zhang, B.; Gao, F.

2006-01-01

54

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

55

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

56

Optimal design of the separate type heat pipe heat exchanger  

Microsoft Academic Search

Separate type heat pipe heat exchangers are often used for large-scale heat exchanging. The arrangement of such a heat exchanger\\u000a conveniently allows heat input to and output from the heat exchanger at remote locations. The traditional method of designing\\u000a an ordinary HPHE (heat pipe heat exchanger) is commonly applied in the separate type exchanger design, but the calculations\\u000a have to

Zi-tao Yu; Ya-cai Hu; Ke-fa Cen

2005-01-01

57

Ceramic heat pipe heat exchangers  

Microsoft Academic Search

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

W. A. Ranken

1976-01-01

58

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)

1986-01-01

59

Bayonet heat exchangers in heat-assisted Stirling heat pump  

SciTech Connect

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

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

1998-07-01

60

Designing Flexible Heat Exchanger Networks  

E-print Network

Procedures and methods used for designing flexible heat exchanger networks are described. The general approach consists of defining the flexibility problem as a set of cases. Pinch Technology is then used to develop an initial network design...

Gautam, R.; Chen, H. S.; Wareck, J. S.

61

The heat pipe heat exchangers: Design, technology and applications  

Microsoft Academic Search

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

S. Chadourne

1991-01-01

62

Relationship between Urban Heat Sink and Heat Energy Exchange in Beijing, China  

Microsoft Academic Search

During our monitoring of the UHI effect in central Beijing using Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, an urban heat sink was found. This paper focuses on the analysis of this urban heat sink developed in the winter morning of Beijing by analyzing the heat energy exchange in detail. The heat energy exchange including the net radiation,

Mingyi Du; Guoyin Cai; Dongwei Qiu

2009-01-01

63

Empirical Study of an Air-to-Air Heat Pipe Heat Exchanger in Tropical Climates  

Microsoft Academic Search

This article presents the empirical study of a heat pipe heat exchanger that was directly experiencing the ambient tropical air in its evaporator section. The performance of the heat pipe heat exchanger was monitored during two weeks of operation to determine the performance curves. The temperature of return air was controlled at about 22°C as the representative temperature of inside

Y. H. Yau; M. Ahmadzadehtalatapeh

2011-01-01

64

Microchannel heat exchanger optimization  

Microsoft Academic Search

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

G. M. Harpole; J. E. Eninger

1991-01-01

65

Evaporative heat transfer in mesoscale heat exchangers  

SciTech Connect

An application for an integrated array of small (mesoscale) cooling devices is introduced and a survey of related research is provided. A test apparatus appropriate for experiments with small-scale, low-capacity evaporators is described. Two-phase pressure drop and heat transfer data are presented for R-134a in a heat exchanger consisting of an inlet manifold, 52 parallel channels, and an exit manifold. Each individual channel has a cross-sectional flow area 800 {micro}m by 800 {micro}m and 74 {micro}m long. Experiments are conducted over a range of conditions, with flow rates up to 0.48 g/s, inlet qualities from 7% to 15%, and an evaporating temperature of approximately 10 C. The heat exchanger operated with a pressure drop of less than about 8 kPa and provided a heat transfer coefficient greater than 8,000 W/(m{sup 2}{center_dot}K). The heat transfer data suggest that nucleate boiling dominates for flow rates below an equivalent Reynolds number (Re{sub eq}) of about 40 in a channel. A comparison of the pressure drop and heat transfer results to related data from the literature shows general agreement and supports these promising results for mesoscale heat exchangers.

Mehendale, S.S.; Jacobi, A.M.

2000-07-01

66

Feedwater heater performance evaluation using the Heat Exchanger Workstation  

SciTech Connect

The Heat Exchanger Workstation (HEW) was developed to monitor performance of heat exchanging equipment in power plants. HEW enables engineers to analyze thermal performance and failure events for power plant feedwater heaters. HEW consists of five tightly integrated application systems: Database for heat-exchanger data storage, Diagrammer for creating heat-exchanger schematics and data displays, Performance Analyst for analyzing and predicting heat-exchanger performance. Performance Advisor for expertise on improving heat-exchanger performance, and Water Calculator for computing properties of steam and water. HEW also contains an electronic Operations and Maintenance Reference Manual. This paper describes these application modules and discusses how the failure analysis of feedwater heaters is being addressed by the Tube-Failure Advisor expert system due for delivery in June 1996. An on-line performance monitoring program for condensers is also being designed as a module for HEW.

Ranganathan, K.M. [Karta Technology, Inc., San Antonio, TX (United States); Tsou, J.L. [Electric Power Research Inst., Palo Alto, CA (United States)

1996-12-31

67

Evaporative heat transfer in mesoscale heat exchangers  

Microsoft Academic Search

An application for an integrated array of small (mesoscale) cooling devices is introduced and a survey of related research is provided. A test apparatus appropriate for experiments with small-scale, low-capacity evaporators is described. Two-phase pressure drop and heat transfer data are presented for R-134a in a heat exchanger consisting of an inlet manifold, 52 parallel channels, and an exit manifold.

S. S. Mehendale; A. M. Jacobi

2000-01-01

68

40 CFR 63.104 - Heat exchange system requirements.  

...exchanger or any combination of heat exchangers. (i) For samples taken at...exchanger or any combination of heat exchangers in chemical manufacturing process...individual heat exchanger or group of heat exchangers and the exit is the point...

2014-07-01

69

40 CFR 63.104 - Heat exchange system requirements.  

Code of Federal Regulations, 2013 CFR

...exchanger or any combination of heat exchangers. (i) For samples taken at...exchanger or any combination of heat exchangers in chemical manufacturing process...individual heat exchanger or group of heat exchangers and the exit is the point...

2013-07-01

70

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

71

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

Microsoft Academic Search

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

Feng Yang; Xiugan Yuan; Guiping Lin

2003-01-01

72

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

73

Preliminary design study of heat pipe heat exchangers  

Microsoft Academic Search

A preliminary design study was conducted in order to identify the important design parameters which can be varied to optimize overall performance of heat pipe heat exchangers. A computer program was developed to analyze the heat exchanger performance using conventional design procedures for finned tube heat exchangers and using conventional design procedures for three-puddle-artery heat pipes.

K. T. Feldman; D. C. Lu

1976-01-01

74

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

75

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

76

Methodology of optimization for microchannel heat exchanger  

Microsoft Academic Search

Heat generation from very large-scale integrated (VLSI) circuits increases with the advent of high-density integrated circuit technology. One of the promising techniques is liquid cooling by using microchannel heat exchanger. This work proposes a scheme for microchannel heat exchanger optimization with the constraint of pump. The cooling performance of microchannel heat exchanger was analyzed by constraining the flow rate and

HeeSung Park; Jongln Jo; JaeYoung Chang; SunSoo Kim

2006-01-01

77

Microchannel heat exchangers for advanced climate control  

Microsoft Academic Search

This paper presents details of fabrication and performance testing of prototype microchannel heat exchangers. The microchannel heat exchangers are being developed for advanced cooling and climate control applications, and are designed for heat loads of 100 W\\/cm2. Bulk and surface micromachining techniques are used to fabricate the test devices. Each heat exchanger section consists of over 150 microchannels etched in

Peter M. Martin; Wendy D. Bennett; John W. Johnston

1995-01-01

78

Multiple heat pipe heat exchanger and method for making  

Microsoft Academic Search

A heat pipe heat exchanger has a plurality of heat pipes which are interconnected so as to permit fluid communication between the pipes at least during charging so that the heat pipes may be simultaneously filled with heat transfer fluid.

Maxson

1979-01-01

79

Oxidizer heat exchanger component test  

NASA Technical Reports Server (NTRS)

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

Kanic, P. G.

1988-01-01

80

Second Law Optimization of Heat Exchangers  

E-print Network

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

Witte, L. C.

81

Synergistic diffuser/heat-exchanger design  

E-print Network

The theoretical and numerical evaluation of synergistic diffusing heat-exchanger design is presented. Motivation for this development is based on current diffuser and heat-exchange technologies in cogeneration plants, which ...

Lazzara, David S. (David Sergio), 1980-

2004-01-01

82

High Temperature Composite Heat Exchangers  

NASA Technical Reports Server (NTRS)

High temperature composite heat exchangers are an enabling technology for a number of aeropropulsion applications. They offer the potential for mass reductions of greater than fifty percent over traditional metallics designs and enable vehicle and engine designs. Since they offer the ability to operate at significantly higher operating temperatures, they facilitate operation at reduced coolant flows and make possible temporary uncooled operation in temperature regimes, such as experienced during vehicle reentry, where traditional heat exchangers require coolant flow. This reduction in coolant requirements can translate into enhanced range or system payload. A brief review of the approaches and challengers to exploiting this important technology are presented, along with a status of recent government-funded projects.

Eckel, Andrew J.; Jaskowiak, Martha H.

2002-01-01

83

Establishing turbulent flow in heat exchangers  

Microsoft Academic Search

Shell-and-tube are the most common style of noncontact heat exchangers used today. Those who use these exchangers naturally benefit when exchanger performance is optimized. Fluid velocities are important to optimization. They directly affect heat transfer efficiencies by contributing to the tubewall-to-fluid heat transfer coefficients inside and outside the exchanger tubes. These coefficients, in turn, are components of the overall heat

1995-01-01

84

A New Design of Heat Exchanger  

Microsoft Academic Search

Broad use of heat exchangers in various branches of industry, in transportation, and in everyday living predetermines continued improvement of these designs to intensify the heat-exchange process and lower costs. Moreover, it is necessary to ensure: • the possibility of conducting the heat-exchange process with large pressure and temperature gradients in the heat-exchange medium, and over a broad range of

D. L. Astanovskii; L. Z. Astanovskii

2003-01-01

85

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

86

21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.  

Code of Federal Regulations, 2013 CFR

...false Cardiopulmonary bypass heat exchanger. 870.4240 Section 870...4240 Cardiopulmonary bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting...

2013-04-01

87

Analysis and application of the heat pipe heat exchanger  

Microsoft Academic Search

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

T. H. Sun; R. C. Prager

1978-01-01

88

Performance of a variable conductance heat pipe heat exchanger  

Microsoft Academic Search

The performance of an air to air heat exchanger in which heat is transferred to a finned evaporator and from a finned condenser via a heat pipe was evaluated. The variable conductance heat pipe is to the condenser fins a heat source and to the evaporator fins a heat sink. The principal advantage of the variable conductance heat pipe heat

P. D. Chancelor

1983-01-01

89

Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes  

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

Talmud, Fred M. (Berkeley Heights, NJ); Garcia-Mallol, Juan-Antonio (Morristown, NJ)

1980-01-01

90

Heat pipe heat exchangers as energy recovery devices  

Microsoft Academic Search

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

Ruch

1976-01-01

91

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

92

Single tube hydride heat exchanger test facility  

Microsoft Academic Search

Heat exchanger tests were conducted to develop heat transfer data which would be needed to design a reasonably optimal HYCSOS device. To meet this primary objective, it was necessary to: (1) design and construct a test facility suitable for small scale heat transfer testing; (2) design and construct several representations of proposed HYCSOS heat exchangers; (3) test these designs under

H. P. Egbert; J. S. Horowitz; G. M. Warapius

1979-01-01

93

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

94

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

Microsoft Academic Search

Integrity monitoring and flaw diagnostics of flat beams and tubular structures was investigated in this research task using guided acoustic signals. A piezo-sensor suite was deployed to activate and collect Lamb wave signals that propagate along metallic specimens. The dispersion curves of Lamb waves along plate and tubular structures are generated through numerical analysis. Several advanced techniques were explored to

Belle R. Upadhyaya; J. Wesley Hines

2004-01-01

95

Fabrication and testing of microchannel heat exchangers  

Microsoft Academic Search

Micro-channel heat-exchanger test articles were fabricated and performance tested. The heat exchangers are being developed for innovative applications, and have been shown to be capable of handling heat loads of up to 100 W\\/cm2. The test articles were fabricated to represent two different designs for the micro-channel portion of the heat exchanger. One design consists of 166 micro-channels etched in

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

1995-01-01

96

NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger  

SciTech Connect

One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor - process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rational for considering liquid metals is the potential convective heat transfer is among the highest known. Thus explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. For process heat it is desired that, intermediate heat exchangers (IHX) transfer heat from the NGNP in the most efficient way possible. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet and inlet of the NGNP. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change heat exchanger with Na as the heat exchanger coolant. In order to design a very efficient and effective heat exchanger one must optimize the design such that we have a high heat transfer and a lower pressure drop, but there is always a trade-off between them. Based on NGNP operational parameters, a heat exchanger analysis with the sodium phase change will be presented to show that the heat exchanger has the potential for highly effective heat transfer, within a small volume at reasonable cost.

Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

2008-09-01

97

Optimum control of heat exchangers with internal heat generation  

Microsoft Academic Search

This paper investigates the optimum control of a heat exchanger having internal heat sources from a reference steady state to a desired value. Both the wall and coolant are treated as distributed-parameter systems. Under certain constraints inherent in the operating conditions and physical limitations of the heat exchanger, the control function of the system, i.e. the heat generation rate which

H. S. Huang; W. J. Yang

1971-01-01

98

Heat Transfer Characteristics of a Generalized Divided Flow Heat Exchanger  

E-print Network

HEAT TRANSFER CHARACTERISTICS OF A GENERALIZED DIVIDED FLrnJ HEAT EXCHANGER KRISHNA P. SINGH, CHIEF ENGINEER JOSEPH OAT CORPORATION 2500 Broadway, Camden, New Jersey 08104 ,l\\bstract The concept of a "Di vi ded-fl O~I" heat exchanger...HEAT TRANSFER CHARACTERISTICS OF A GENERALIZED DIVIDED FLrnJ HEAT EXCHANGER KRISHNA P. SINGH, CHIEF ENGINEER JOSEPH OAT CORPORATION 2500 Broadway, Camden, New Jersey 08104 ,l\\bstract The concept of a "Di vi ded-fl O~I" heat exchanger...

Singh, K. P.

1979-01-01

99

Condensation Behavior in a Microchannel Heat Exchanger  

Microsoft Academic Search

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

Akiko Kaneko; Genki Takeuchi; Yutaka Abe; Yutaka Suzuki

2009-01-01

100

Rotary heat exchanger with circumferential passages  

Microsoft Academic Search

A rotary heat exchanger is described for affecting indirect countercurrent and cocurrent heat exchange between fluid streams, which comprises: (a) circular shaped finned discs fabricated from heat conducting materials and configured with internal circumferential passages spaced in annular array; (b) finned discs coaxially aligned and affixed to a support means which facilitates rotation in predetermined direction and speed about a

Delahunty

1986-01-01

101

Effectively design air-cooled heat exchangers  

Microsoft Academic Search

Based on bare-tube heat-transfer area, air-cooled heat exchangers (ACHEs) cost two to three times more than water-cooled heat exchangers for the same heat duty (hardware costs only). There are two main reasons for this. First, the thermal conductivity of air is considerably lower than that of water, which results in a much lower heat-transfer coefficient. Second, since design ambient temperatures

1997-01-01

102

Analysis of capacitive heat exchangers, part 1  

NASA Technical Reports Server (NTRS)

Governing equations are developed for a simple capacitive heat exchanger. This type of heat exchanger consists of hot spherical particles falling through an ascending cold gas stream. The assumptions made in deriving the continuity, momentum and energy equations are clearly stated. The analysis yields a system of first order, ordinary, nonlinear equations which form a complex boundary value problem. The method of solution is presented together with a comparison between the performance of capacitive heat exchangers and conventional counter flow ones.

Schonfeld, D.

1981-01-01

103

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

104

Oxidizer heat exchanger component testing  

NASA Technical Reports Server (NTRS)

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

Kmiec, T.; Kanic, P.

1986-01-01

105

Innovative heat exchangers for solar water heaters.  

E-print Network

??The performance of two innovative collector-loop heat exchangers used in pumped circulation solar water heaters was investigated experimentally and numerically, and TRNSYS simulation models were… (more)

Soo Too, Yen Chean

2007-01-01

106

Advanced Micro-Heat Exchangers for High Heat Flux  

Microsoft Academic Search

Three micro-heat exchangers for use in a liquid cooling system with a long offset strip, short offset strip, and chevron flow path based on the traditional heat transfer enhancement concepts were designed and tested. A straight channel heat exchanger was also made for comparison. The liquid crystal thermography method described by Lin and Yang (2005) was used to observe the

Chien-Yuh Yang; Chun-Ta Yeh; Wei-Chi Liu; Bing-Chwen Yang

2007-01-01

107

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

108

A method of analysis for heat pipe heat exchangers  

Microsoft Academic Search

A method of analysis for the thermal performance of heat pipe heat exchangers based on the conductance model was developed in the present study. In the analysis the specific heat conductance of the heat pipe was obtained from a performance test of a single heat pipe described in the present paper and the well-known universal correlations were used to calculate

B. J. Huang; J. T. Tsuei

1985-01-01

109

Experimental investigation of a manifold heat-pipe heat exchanger  

Microsoft Academic Search

Results of experimental investigations of a heat exchanger on a manifold water heat pipe are given. An analysis is made of the temperature distribution along the heat-transfer agent path as a function of the transferred heat power. The influence of the degree of filling with the heat transfer agent on the operating characteristics of the construction is considered.

S. V. Konev

1995-01-01

110

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

111

Heat Exchanger With Reservoir And Controls  

NASA Technical Reports Server (NTRS)

Heat-pipe assembly operates as evaporator or as condenser. New heat exchanger incorporates important improvements over previous designs. By adding reservoir to primary loop, locating ultrasonic liquid-level sensors on reservoir rather than directly on one of heat pipes, and revising control logic, uneven distribution of flow among heat pipes and erroneous behavior of valves eliminated.

Brown, Richard F.; Edelstein, Fred

1989-01-01

112

Microchannel heat exchangers for chemical reactors  

SciTech Connect

A novel heat exchanger which uses microchannels to enhance heat transfer rates is investigated for chemical reactor applications. Heat exchange fluid flows in parallel through multiple channels of micron dimensions to both increase the surface area available for heat transfer and shrink the coolant boundary layer which reduces heat transfer resistance. An experimental apparatus simulates the operation of an exothermic reactor, and heat removal fluxes are measured between 6.5 and 42.5 W/cm{sup 2}. Overall heat transfer coefficients range from 5,000 to 16,000 W/m{sup 2}/K, which represents nearly an order of magnitude increase over a conventional heat exchanger of similar materials. The impact of higher heat removal fluxes is discussed for safe and stable reactor design and operation.

Tonkovich, A.L.Y.; Call, C.J.; Jimenez, D.M.; Wegeng, R.S.; Drost, M.K. [Pacific Northwest National Lab., Richland, WA (United States)

1996-12-31

113

Collector Pressure Losses in Micro Heat Exchangers  

Microsoft Academic Search

As collector losses are expected to play a crucial role in micro heat exchangers, an experimental method is developed to determine these losses. Experiments are performed on a micro heat exchanger consisting of 42 parallel microchannels positioned in a 6 by 7 matrix, with hydraulic diameters in the range of 260-280 mum. The proposed method is successfully applied. From the

M. Baelmans

2007-01-01

114

Analysis of capacitive heat exchangers, part 2  

NASA Technical Reports Server (NTRS)

The performance of a simple capacitive heat exchanger was analyzed. The shooting method for solving the governing equations is presented. Simplified linear and nonlinear models are analyzed using this method and it is shown that capacitive heat exchangers are more efficient than conventional ones.

Schonfeld, D.

1982-01-01

115

Cryogenic fluid flow instabilities in heat exchangers  

NASA Technical Reports Server (NTRS)

Analytical and experimental investigation determines the nature of oscillations and instabilities that occur in the flow of two-phase cryogenic fluids at both subcritical and supercritical pressures in heat exchangers. Test results with varying system parameters suggest certain design approaches with regard to heat exchanger geometry.

Fleming, R. B.; Staub, F. W.

1969-01-01

116

Modeling of Heat Transfer in Geothermal Heat Exchangers  

E-print Network

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

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

2006-01-01

117

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

118

40 CFR 63.1409 - Heat exchange system provisions.  

...exchanger or any combination of heat exchangers. (i) For samples taken at...exchanger or any combination of heat exchangers, the entrance is the point at...individual heat exchanger or group of heat exchangers, and the exit is the point...

2014-07-01

119

Two-Phase Bidirectional Heat Exchanger  

NASA Technical Reports Server (NTRS)

Heat exchanger transfers heat from one two-phase thermal loop to another. Condenses vapor in one loop while evaporating liquid in other. Transfers heat with very small drops in temperature and pressure, and efficiently joins heat pipes thermally without mixing of their working fluids. Several such heat exchangers used to build long, complex multiloop heat-control systems. Exchanger bidirectional: transfers heat in reverse, condensing on normally evaporating side, and vice versa. Can warm equipment it normally cools, without using auxiliary heater. In reverse transfer, wicks on evaporating side supply liquid continuously by capillary action; reverse-flow pump not needed. Design modified for other working fluids and larger heat-transfer rates.

Kroliczek, Edward; Ku, Jentung

1991-01-01

120

Heat Exchanger Technologies for Distillation Columns  

E-print Network

Heat Exchanger Technologies for Distillation Columns G.T.Polley Pinchtechnology.com In this paper we look at the challenges that improvements in energy efficiency of distillation systems presents the heat exchanger designer. We examine... condensate sub-cooling. So, if this condensate subsequently requires re-heating both energy and capital have been wasted. If the condensate forms a feed to another distillation column it results in increased energy consumption if that separation...

Polley, G. T.

121

Heat exchanger and method of making  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

122

Solar greenhouse heating using an underground heat exchange system  

Microsoft Academic Search

The air temperature in a greenhouse on a sunny day often exceeds the optimum temperature level for the growth of crops. Therefore, there are frequent occasions when it becomes necessary to discharge the excess heat. This has given rise to the development by some investigators of an underground heat exchange system for heating greenhouses which utilizes this excess heat. The

T. Masao; D. Kiyoshi; O. Toshiaki; O. Yoshihiro

1982-01-01

123

Heat transfer by a corona wind heat exchanger  

Microsoft Academic Search

A cold plate heat exchanger fitted with pin fins and having integral corona wind blowers was constructed and tested for thermal performance. The heat exchanger was operated in air at sea level pressure and at reduced pressures with Reynold's numbers up to 300. Test in sulphur hexafluoride gas at sea level pressures demonstrated that the thermal performance was considerably better

A. S. Mitchell

1978-01-01

124

Local heat transfer measurements of plate finned-tube heat exchangers by infrared thermography  

Microsoft Academic Search

An experimental study is performed using an infrared thermovision to monitor temperature distribution over a plate-fin surface inside the plate finned-tube heat exchangers. The differentiation of the temperature function is derived to determine the local convective heat transfer coefficients on the tested fin, using a local element lumped conduction equation included the convective effect on the boundaries with experimental data.

Herchang Ay; JiinYuh Jang; Jer-Nan Yeh

2002-01-01

125

40 CFR 63.1435 - Heat exchanger provisions.  

...2014-07-01 2014-07-01 false Heat exchanger provisions. 63.1435 Section...Polyols Production § 63.1435 Heat exchanger provisions. (a) The owner...requirements of § 63.104 for heat exchange systems, with the...

2014-07-01

126

40 CFR 63.1435 - Heat exchanger provisions.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Heat exchanger provisions. 63.1435 Section...Polyols Production § 63.1435 Heat exchanger provisions. (a) The owner...requirements of § 63.104 for heat exchange systems, with the...

2013-07-01

127

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

128

Condensing Heat Exchangers Optimize Steam Boilers  

E-print Network

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

Sullivan, B.; Sullivan, P. A.

1983-01-01

129

Marine fouling of titanium heat exchangers  

Microsoft Academic Search

A series of marine fouling experiments was conducted at Freeport, Texas, on two single-pass titanium heat exchangers. The exchangers, which were constructed with commercially pure titanium tubes (5\\/8-inch (1.59-centimeter)) outside diameter by 30-inch (76.3-centimeter length) and 6Al-4V alloy tube sheets and headers, were operated on natural seawater. One of the exchangers was fed electrolytically chlorinated seawater, while the other was

W. L. Adamson

1976-01-01

130

4. Heat exchangers; Steam, steam processes  

E-print Network

: Geometries /1 Schematics for (a) counterflow, (b) parallel flow, (c) crossflow, (d) 1 shell and 2 tube passes exchangers: (a) One fluid mixed, one fluid unmixed, (b) both fluids unmixed. Heat exchangers: Geometries /2 pictures: KJ05 Temperature distributions of fluid in (a) counterflow, (b) parallel flow, and (c) 1 shell

Zevenhoven, Ron

131

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

132

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

133

Intelligent Predictive Control of Micro Heat Exchanger  

Microsoft Academic Search

\\u000a An intelligent predictive control to temperature control of a micro heat exchanger is addressed. First, the dynamics of the\\u000a micro heat exchanger is identified using a locally linear model. Then, the predictive control strategy based on this model\\u000a of the plant is applied to provide set point tracking of the output of the plant.

Mehdi Galily; Farzad Habibipour Roudsari; Masoum Fardis; Ali Yazdian

2005-01-01

134

Joule-Thomson expander and heat exchanger  

NASA Technical Reports Server (NTRS)

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

Norman, R. H.

1976-01-01

135

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

136

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

Microsoft Academic Search

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

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

2000-01-01

137

Brayton-cycle heat exchanger technology program  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

138

Augmentation of heat transfer performance in coiled flow inverter vis-à-vis conventional heat exchanger  

Microsoft Academic Search

In the present work, primarily two studies were carried out to ascertain the performance of coiled flow inverter (CFI) as heat exchanger at pilot plant scale. In the first study, performance of CFI heat exchanger has been compared with conventional heat exchangers, i.e. shell and tube heat exchanger (SHE) and plate type heat exchanger (PHE) under identical heat transfer area

M. M. Mandal; Vimal Kumar; K. D. P. Nigam

2010-01-01

139

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

140

Boiling heat transfer in compact heat exchangers  

SciTech Connect

Small circular and noncircular channels are representative of flow passages in compact evaporators and condensers. This paper describes results of an experimental study on heat transfer to the flow boiling of refrigerant- 12 in a small circular tube of diameter = 2.46 mm. The objective of the study was to assess the effect of channel size on the heat transfer coefficient and to obtain additional insights relative to the heat transfer mechanisms. The flow channel was made of brass and had an overall length of 0.9 m. The channel wall was electrically heated, and temperatures were measured on the channel wall and in the bulk fluid stream. Voltage taps were located at the same axial locations as the stream thermocouples to allow testing over an exit quality range of 0.21 to 0.94 and a large range of mass flux (63 to 832 kg/m{sup 2}s) and heat flux (2.5 to 59 kW/m{sup 2}). Saturation pressure was nearly constant, averaging 0.82 MPa for most of the testing; a few test data were also taken at a constant lower pressure of 0.52 MPa. Local heat transfer coefficients were determined experimentally. Analysis provided additional support for the conclusion, arrived at from previous studies, that a nucleation mechanism dominates for flow boiling in small channels; nevertheless, a convective-dominant region was identified at very low values of wall superheat (<{approx}3{degrees}C). Previous flow boiling studies in small channels, that did not include wall superheats this low, did not encounter the convective dominant mechanism. Conversely, cryogenic studies at very low wall superheats ({approx}l{degree}C) did not encounter the nucleation dominant regime. The apparent discrepancy is explained by the results of this study.

Tran, T.N.; Wambsganss, M.W. [Argonne National Lab., IL (United States); France, D.M. [Illinois Univ., Chicago, IL (United States). Dept. of Mechanical Engineering

1994-12-31

141

Microchannel Heat Exchangers with Carbon Dioxide  

Microsoft Academic Search

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

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

2001-01-01

142

Dealing with Uncertainties During Heat Exchanger Design  

E-print Network

Over the last thirty years much progress has been made in heat exchanger design methodology. Even so, the design engineer still has to deal with a great deal of uncertainty. Whilst the methods used to predict heat transfer coefficients are now quite...

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

143

MODELING PARTICLE DEPOSITION ON HVAC HEAT EXCHANGERS  

E-print Network

energy and indoor air quality degradation for heating, ventilating, and air conditioning (HVAC) systems energy and indoor air quality effects can be evaluated. The model is simple and general enough. Particulate fouling of indoor fin- and-tube heat exchangers, particularly air conditioner evaporators

144

The water-cryogen heat exchanger  

NASA Technical Reports Server (NTRS)

Heat exchanger, using water as heat medium, converts liquid hydrogen to gaseous hydrogen at a very high rate. Possible applications include treatment of liquified natural gas in cities to bring the gas on-line quickly, conversion of liquid oxygen and liquid nitrogen for steel mills, and high volume inert purging.

Bartlit, J. R.; Boyer, K.; Williamson, K. D.

1970-01-01

145

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

146

Heat exchanger with valved pipe connection  

Microsoft Academic Search

This patent describes a heating and ventilating unit for motor cars having air temperature regulation by a heat exchanger which may be variably slid into a fresh air stream and the operative surface of which is variably acted upon in a defined constant position. The surface is acted upon approximately at right angles to the fresh air stream from a

Knab

1986-01-01

147

Performance Evaluation of Heat Pipe Heat Exchanger  

Microsoft Academic Search

To the basis of first law of thermodynamics, mainly applicable to engineering calculations; to the basis of the second law of thermodynamics - entropy analysis method, can be used to apply to theoretical analysis and engineering calculations. In this paper, a single performance valuation and entropy analysis for heat recovery equipment have been used, which is to make performance evaluation

Zhang Jie; Ren Yan; Zhang Li Hong; Zhang Kang

2010-01-01

148

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

149

Development of Micro Channel Heat Exchanging  

Microsoft Academic Search

In order to investigate the performance of the micro channel heat exchanger, three-dimensional numerical simulations and experiments on heat transfer behavior and pressure loss were carried out. So far as the heat transfer phenomena is concerned, results obtained using a silicon chip micro channel model showed a very small thermal resistance, about 0.1 (Kcm2\\/W). And, measured pressure loss showed good

Koichiro Kawano; Masayuki Sekimura; Ko Minakami; Hideo Iwasaki; Masaru Ishizuka

2001-01-01

150

Heat exchanger with auxiliary cooling system  

DOEpatents

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

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

1980-01-01

151

Microchannel heat exchangers: a review  

Microsoft Academic Search

The early work by Tuckerman and Pease on high-performance heat sinks has provoked numerous uses of them as a means of cooling electronic components. This paper is a review of 73 available works by academics and\\/or researchers who have used the original microchannel heat sink concept or have extended its design or use to turbulent flow, variable channel\\/fin width ratios,

John S. Goodling

1993-01-01

152

Package embedded heat exchanger for stacked multi-chip module  

Microsoft Academic Search

This paper described a polymer type micro heat exchanger for stacked multi-chip module (MCM). Usually, heat exchanger was fabricated by high thermal conductive substrate such as metal, silicon etc. Of course it showed efficient heat exchange ability. However, there was packaging problem when it was integrated in a package, because the heat exchanger became too huge to accommodate in present

Haehyung Lee; Yongwon Jeong; Joonghan Shin; Songyi Kim; Minha Kim; Moonkoo Kang; Kukjin Chun

2003-01-01

153

Multiple Sensor Fault Detection in Heat Exchanger Systems  

E-print Network

Multiple Sensor Fault Detection in Heat Exchanger Systems Abdelwahab Aïtouche* , Didier Maquin strategy is presented for a heat exchanger system for which the process model consists of a set of linear equations, and can be found in heat exchangers. The increasing importance of heat exchangers in the industry

Paris-Sud XI, Université de

154

Heat transfer with freezing in a scraped surface heat exchanger  

Microsoft Academic Search

An experimental study was carried out on a scraped surface heat exchanger used for freezing of water–ethanol mixture and aqueous sucrose solution. The influence of various parameters on heat transfer intensity was established: product type and composition, flow rate, blade rotation speed, distance between blades and wall. During starting (transient period) the solution is first supercooled, then ice crystals appear

Mohamed Ben Lakhdar; Rosalia Cerecero; Graciela Alvarez; Jacques Guilpart; Denis Flick; André Lallemand

2005-01-01

155

Experimental Analysis of Heat Transfer Characteristics for Plate Heat Exchanger  

Microsoft Academic Search

According to analysis of heat transfer characteristics for heat exchanger, one kind of comprehensive performance experimental system is designed, which is high degree of automation, high measurement accuracy, simple operation and wide range of applications. Using Wilson Method to control experimental data and fit curve, one empirical formula is induced and corresponding rule curve is drawn. They are similar with

Yan Liu; Qing Gao; Guohua Wang; Chun Gao

2010-01-01

156

Earth type heat exchanger for heat pump system  

Microsoft Academic Search

The heat exchanger unit is highly efficient in operation and is so constructed as to permit rapid installation in and removal from the earth at small size sites of desired use of the heat pump system. The unit includes a freon-conducting coil assembly preferably comprised of a plurality of concentric coils defining parallel flow paths for the fluid conducted to

Bingham

1985-01-01

157

Modeling particle deposition on HVAC heat exchangers  

SciTech Connect

Fouling of fin-and-tube heat exchangers by particle deposition leads to diminished effectiveness in supplying ventilation and air conditioning. This paper explores mechanisms that cause particle deposition on heat exchanger surfaces. We present a model that accounts for impaction, diffusion, gravitational settling, and turbulence. Simulation results suggest that some submicron particles deposit in the heat exchanger core, but do not cause significant performance impacts. Particles between 1 and 10 {micro}m deposit with probabilities ranging from 1-20% with fin edge impaction representing the dominant mechanism. Particles larger than 10 {micro}m deposit by impaction on refrigerant tubes, gravitational settling on fin corrugations, and mechanisms associated with turbulent airflow. The model results agree reasonably well with experimental data, but the deposition of larger particles at high velocities is underpredicted. Geometric factors, such as discontinuities in the fins, are hypothesized to be responsible for the discrepancy.

Siegel, J.A.; Nazaroff, W.W.

2002-01-01

158

Analysis of compact heat exchanger performance  

SciTech Connect

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 reduces longitudinal conduction. Packed-bed regenerators employing wire screens, perforated plates, or granular particles also have a similar structure. In these exchangers, any individual plate or particle has very high thermal conductivity and is essentially at a single temperature. As a result, the temperature profile along the length consists of many steps, rather than a single continuous curve. Conventional analysis based on a continuous temperature profile tends to overestimate the efficiency of these exchangers. Axial conduction down the bed, caused by finite contact or spacer resistance, further reduces the effectiveness. The ineffectiveness due to axial conduction adds to that due to finite number of plates and finite heat transfer coefficient. A closed form expression is derived for the efficiency of a compact heat exchanger with given design N/sub tu/ where the exchanger consists of layers of metallic screens, plates, or particle layers. It is observed that the effect of discrete temperature profile becomes significant when the per stage design N/sub tu/ exceeds about 0.5.

Sarangi, S.; Barclay, J.A.

1984-01-01

159

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

160

Heat exchange in short microtubes and micro heat exchangers with low hydraulic losses  

Microsoft Academic Search

Miniaturization of heat exchangers opens up the way to a considerable increase of their volumetric characteristics. We examine\\u000a the changes in heat transfer due to decreasing tube size and relative length. To get a higher overall thermal power, we have\\u000a considered a “checkmate” design that allows to combine a number of micro cross-flow heat exchange modules. The requirement\\u000a for low

D. A. Rachkovskij; E. M. Kussul; S. A. Talayev

1998-01-01

161

Heat exchanger containing a component capable of discontinuous movement  

DOEpatents

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices. 11 figures.

Wilson, D.G.

1993-11-09

162

Development and experimental evaluation of a thermography measurement system for real-time monitoring of comfort and heat rate exchange in the built environment  

NASA Astrophysics Data System (ADS)

A measurement system based on infrared (IR) thermovision technique (ITT) is developed for real-time estimation of room thermal variations and comfort conditions in office-type environment as a part of a feasibility study in the EU FP7 project ‘INTUBE’. An IR camera installed on the ceiling allows thermal image acquisition and post-processing is performed to derive mean surface temperatures, number of occupants and presence of other heat sources (e.g. computer) through detecting algorithms. A lumped parameter model of the room, developed in the Matlab/Simulink environment, receives as input the information extracted from image processing to compute room exchanged heat rate, air temperature and thermal comfort (PMV). The aim is to provide in real time the room thermal balance and comfort information for energy-saving purposes in an improved way with respect to traditional thermostats. Instantaneous information can be displayed for the users or eventually used for automatic HVAC control. The system is based on custom adaptation of a surveillance low-cost IR system with dedicated radiometric calibration. Experimental results show average absolute discrepancies in the order of 0.4 °C between calculated and measured air temperature during a time period of a day. A sensitivity analysis is performed in order to identify main uncertainty sources.

Revel, G. M.; Sabbatini, E.; Arnesano, M.

2012-03-01

163

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

164

Micro-Scale Regenerative Heat Exchanger  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

165

Heat transfer coefficients of shell and coiled tube heat exchangers  

SciTech Connect

In the present study, the heat transfer coefficients of shell and helically coiled tube heat exchangers were investigated experimentally. Three heat exchangers with different coil pitches were selected as test section for both parallel-flow and counter-flow configurations. All the required parameters like inlet and outlet temperatures of tube-side and shell-side fluids, flow rate of fluids, etc. were measured using appropriate instruments. Totally, 75 test runs were performed from which the tube-side and shell-side heat transfer coefficients were calculated. Empirical correlations were proposed for shell-side and tube-side. The calculated heat transfer coefficients of tube-side were also compared to the existing correlations for other boundary conditions and a reasonable agreement was observed. (author)

Salimpour, M.R. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran)

2009-01-15

166

Neurogenetic optimization of micro compact heat exchanger  

Microsoft Academic Search

Purpose – This paper seeks to introduce an optimization method for maximizing the effectiveness of the micro compact heat exchanger (MHE) under various geometrical parameters. Design\\/methodology\\/approach – Optimization is realized using the neuro-genetic methodology which combines the application of artificial neural network (ANN) together with genetic algorithms (GA). The analyses are divided into two main sections; the first being the

H. W. Lee; Y. J. Teng; I. A. Azid; K. N. Seetharamu

2007-01-01

167

Analysis of microchannel heat exchangers using FEM  

Microsoft Academic Search

A finite element method is applied to evaluate the performance of microchannel heat exchangers that are used in electronic packaging. The present approach is validated against the CFD data available in the literature. A comparison of the predicted results with other available results obtained from different concepts shows that the present method is able to predict the surface temperature, the

G. A. Quadir; Anvar Mydin; K. N. Seetharamu

2001-01-01

168

LMFBR intermediate-heat-exchanger experience  

Microsoft Academic Search

This paper presents developmental and operating experience of large Intermediate Heat Exchangers (IHX's) in US from the Fast Flux Test Facility (FFTF) to the Clinch River Breeder Reactor Plant (CRBRP) to the Large Development Plant (LDP). Design commonalities and deviations among these IHX's are synopsized. Various developmental tests that were conducted in the areas of hydraulic, structural and mechanical design

S. M. Cho; T. R. Beaver

1983-01-01

169

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

170

Heat exchanger, head and shell acceptance criteria  

Microsoft Academic Search

Instability of postulated flaws in the head component of the heat exchanger could not produce a large break, equivalent to a DEGB in the PWS piping, due to the configuration of the head and restraint provided by the staybolts. Rather, leakage from throughwall flaws in the head would increase with flaw length with finite leakage areas that are bounded by

P. S. Lam; R. L. Sindelar

1992-01-01

171

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

172

Water-to-water heat transfer in tube–tube heat exchanger: Experimental and analytical study  

Microsoft Academic Search

Tube–tube heat exchanger (TTHE) is a low cost, vented double wall heat exchanger which increases reliability by avoiding mixing of fluids exchanging heat. It can be potentially used for heat recovery from engine cooling circuit, oil cooling, desuperheating in refrigeration and air conditioning, dairy, and pharmaceutical industry, chemical industry, refinery, etc. These tube–tube heat exchangers are successfully demonstrated for superheat

Milind V. Rane; Madhukar S. Tandale

2005-01-01

173

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.

174

Comparative Studies on Micro Heat Exchanger Optimisation Tatsuya Okabe  

E-print Network

Comparative Studies on Micro Heat Exchanger Optimisation Tatsuya Okabe , Kwasi Foli ¡ , Markus- timisation of a micro heat exchanger (¤ HEX). The trend to- wards miniaturisation has led to the use of micro devices in industry and technology. Micro heat exchangers have very high heat transfer surface area

Coello, Carlos A. Coello

175

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

176

Plasma hydrophilic surface treatment for dehumidifying heat exchangers  

Microsoft Academic Search

This paper describes a method using plasma gas to form a hydrophilic surface on fin stock for dehumidifying finned-tube heat exchangers. The heat exchangers (with and without the plasma treatment) were subjected to 1000 wet\\/dry cycles and the contact angle was measured as a function of cycling time. The heat transfer and pressure drop characteristics of these heat exchangers were

Gyu-rak Kim; Hyunuk Lee; Ralph L. Webb

2002-01-01

177

Low heat transfer oxidizer heat exchanger design and analysis  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

178

Heat transfer analysis of boreholes in vertical ground heat exchangers  

Microsoft Academic Search

A ground heat exchanger (GHE) is devised for extraction or injection of thermal energy from\\/into the ground. Bearing strong impact on GHE performance, the borehole thermal resistance is defined by the thermal properties of the construction materials and the arrangement of flow channels of the GHEs. Taking the fluid axial convective heat transfer and thermal “short-circuiting” among U-tube legs into

Heyi Zeng; Nairen Diao; Zhaohong Fang

2003-01-01

179

Controlling space humidity with heat-pipe heat exchangers  

Microsoft Academic Search

The performance of an existing 5 ton (17.6 kW) air conditioning system with an energy efficiency ratio, EER, of 8 has been simulated by retrofitting it with a heat-pipe heat-exchanger (HPHE) to improve cooling and dehumidification. Weather data for Dallas (ASHRAE, 1997) is used for this investigation. This investigation shows that by retrofitting an existing 5 ton (17.6 kW) air

G. D. Mathur

2000-01-01

180

Cost-effectiveness study of heat pipe heat exchangers  

Microsoft Academic Search

The initial costs of three types of heat pipe heat exchangers are presented: aluminum-Freon 11 for the temperature range from -23 C to 121 C, copper-water for 38 C to 232 C, and carbon steel-Dowtherm A for 120 C to 400 C. An optimization computer program for the cost-effectiveness analysis is developed, which takes into consideration the costs for equipment,

D. C. Lu; K. T. Feldman Jr.

1977-01-01

181

A Plastic-Core Compact Heat Exchanger for Energy Conservation  

E-print Network

transfer in a heat exchanger, which in the effectiveness-NTU method takes the fonn of Equation (I) where the subscripts h, c, and i stand for hot, cold, and inlet conditions, respectively, T represents temperature, C min = (mcp)min is the minimum heat... acquisition was added later to scan and monitor the readings better. The experimental data of pressure drop as a function of volumetric flow rate at room temperature are shown in Figure 5 for the cold side and Figure 6 for the hot side. The maximum loss...

Lazaridis, A.; Rafailidis, E.

182

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

183

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

184

Titanium for condenser and heat exchanger service  

SciTech Connect

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

Mountford, J.A. Jr. [Titanium Metals Corp., Toronto, OH (United States)

1996-12-31

185

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

Microsoft Academic Search

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

K. Koyama; Y. Asako

2010-01-01

186

The analysis of heat transfer with and without condensation in a heat pipe heat exchanger  

Microsoft Academic Search

In most heat pipe heat exchangers, the fluid streams will be in counterflow, and the inlet temperatures and the volume or mass flow rates of each stream are known. The simplest analysis under these conditions is provided by the effectiveness method reported by Kreith (1967). An expression for the effectiveness of a counterflow heat exchanger is derived by Kays and

R. C. Prager; T. H. Sun

1978-01-01

187

Alternative approach in thermal analysis of plate heat exchanger  

Microsoft Academic Search

This paper presents alternative approach in heat transfer analysis of plate heat exchangers. In order to obtain heat transfer\\u000a rate and effectiveness values of plate heat exchanger, neural network (NN) approach was used. Experimentally, system used\\u000a in plate heat exchanger for heating and cooling applications was designed and constructed. Experimental data were used for\\u000a training and testing network. The training

Re?at Selba?; Arzu ?encan; Bayram K?l?ç

2009-01-01

188

Thermal induced flow oscillations in heat exchangers for supercritical fluids  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

189

14 CFR 29.1125 - Exhaust heat exchangers.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Exhaust heat exchangers. 29.1125 Section 29.1125 Aeronautics and...Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft...

2013-01-01

190

14 CFR 29.1125 - Exhaust heat exchangers.  

... 2014-01-01 2014-01-01 false Exhaust heat exchangers. 29.1125 Section 29.1125 Aeronautics and...Powerplant Exhaust System § 29.1125 Exhaust heat exchangers. For reciprocating engine powered rotorcraft...

2014-01-01

191

14 CFR 25.1125 - Exhaust heat exchangers.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Exhaust heat exchangers. 25.1125 Section 25.1125 Aeronautics and...Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes,...

2013-01-01

192

14 CFR 25.1125 - Exhaust heat exchangers.  

... 2014-01-01 2014-01-01 false Exhaust heat exchangers. 25.1125 Section 25.1125 Aeronautics and...Powerplant Exhaust System § 25.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes,...

2014-01-01

193

14 CFR 23.1125 - Exhaust heat exchangers.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Exhaust heat exchangers. 23.1125 Section 23.1125 Aeronautics and...Powerplant Exhaust System § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes...

2013-01-01

194

Compact Ceramic Heat Exchangers for Corrosive Waste Gas Applications  

E-print Network

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

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

1982-01-01

195

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

196

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

197

Cleaning agents for reactor heat exchangers  

SciTech Connect

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 temperature. A comparison of the effectiveness of oxalic acid with other potential cleaning agents using test specimens from a fouled heat exchanger demonstrated that oxalic acid at comparable concentrations is superior to the alternatives. The effects of periodic treatment of the HXs with oxalic acid on carbon steel components in the system is small or negligible when the naturally formed protective corrosion layer is undisturbed. Although it does etch the bare metal, oxalic acid has little effect on the protective corrosion layer. Periodic use of oxalic acid on the HX system should not decrease the life of the carbon steel headers.

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

1984-03-01

198

Measurement of flow field and local heat transfer distribution on a scraped heat exchanger crystalliser surface  

E-print Network

Measurement of flow field and local heat transfer distribution on a scraped heat exchanger.ravelet@laposte.net Geert-Jan Witkamp G.J.Witkamp@xs4all.nl Abstract In a cylindrical scraped heat exchanger crystallizer exchanger surface has been studied by direct measurements of the heat exchanger surface temperature

Boyer, Edmond

199

Comparative studies on micro heat exchanger optimisation  

Microsoft Academic Search

Although many methods for dealing with multi-objective optimisation (MOO) problems are avail- able (Deb01) and successful applications have been re- ported (Coe01), the comparison between MOO meth- ods applied to real-world problem was rarely car- ried out. This paper reports the comparison between MOO methods applied to a real-world problem, namely, the optimisation of a micro heat exchanger ( HEX).

Tatsuya Okabe; Kwasi Foli; Markus Olhofer; Yaochu Jin; Bernhard Sendhoff

2003-01-01

200

OXIDE DISPERSION-STRENGTHENED HEAT EXCHANGER TUBING  

Microsoft Academic Search

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

Mark A

2001-01-01

201

Optimizing PT Arun LNG main heat exchanger  

SciTech Connect

The capacity of a LNG liquefaction unit has been increased by upgrading the refrigeration system, without making changes to the main heat exchanger (MHE). It is interesting, that after all modifications were completed, a higher refrigerant circulation alone could not increase LNG production. However, by optimizing the refrigerant component ratio, the UA of the MHE increased and LNG production improved. This technical evaluation will provide recommendations and show how the evaluation of the internal temperature profile helped optimize the MHE operating conditions.

Irawan, B. [PT Arun NGL Co., Sumatra (Indonesia)

1995-12-01

202

Compact heat exchanger optimization tools based on volume averaging theory  

SciTech Connect

Optimization of the enhancement of heat exchangers (HE), compact heat exchangers (CHE) and micro-heat exchangers by design of their basic structure is the focus of this work. A theoretical basis for heat and momentum transport equations obtained with volume averaging theory (VAT) is developed for modeling and design of heat exchangers. Using different flow regime transport models, equation sets are obtained for momentum transport and two-temperature or three-temperature heat transfer in non-isotropic heterogeneous CHE media that account for interphase exchange and micro-roughness.

Travkin, V.S.; Catton, I.

1999-07-01

203

Boundary geometric control of a counter-current heat exchanger  

E-print Network

Boundary geometric control of a counter-current heat exchanger Ahmed MAIDIa , Moussa DIAFb , Jean control of a counter-current heat exchanger whose control is designed considering a model based on two. The objective consists in controlling the internal fluid temperature, at the heat exchanger outlet

Boyer, Edmond

204

The Neural Heat Exchanger ``Invited Talk'' at ICONIP'96  

E-print Network

The Neural Heat Exchanger ``Invited Talk'' at ICONIP'96 J¨urgen Schmidhuber IDSIA, Corso Elvezia 36 by the physical heat exchanger. Unlike backprop, it is entirely local. This makes its parallel implementation in written form. To fully understand the Neural Heat Exchanger's advantages and limitations, however, much

Schmidhuber, Juergen

205

OPTIMAL DESIGN OF MICRO BARE-TUBE HEAT EXCHANGER  

Microsoft Academic Search

An optimum design tool based on the simulated annealing technique has been developed for a compact heat exchanger that employs only small diameter tubes without conventional fins, and the performance achieved by the present design is compared to commercially available compact heat exchangers. For all design problems tested, the present heat exchanger design offers a significant degree of improvement in

Sawat Paitoonsurikarn; Nobuhide Kasagi; Yuji Suzuki

2003-01-01

206

Deposition of Biological Aerosols on HVAC Heat Exchangers  

E-print Network

LBNL-47669 Deposition of Biological Aerosols on HVAC Heat Exchangers Jeffrey Siegel and Iain Walker of Biological Aerosols on HVAC Heat Exchangers Jeffrey A. Siegel Iain S. Walker, Ph.D. ASHRAE Student Member heat exchangers. A model has been developed that incorporates the effects of several deposition

207

GEA Heat Exchangers GEA Searle Cooler and Condensing Unit Ranges  

E-print Network

GEA Heat Exchangers GEA Searle Cooler and Condensing Unit Ranges Top-level engineering solutions,Eurovent verification and many more. GEA is one of the longest established and principal manufacturers of heat exchange range. GEA Heat Exchangers products are utilised across many industries. Applications include industrial

Frandsen, Søren

208

Heat exchanger support apparatus in a fluidized bed  

DOEpatents

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

Lawton, Carl W. (West Hartford, CT)

1982-01-01

209

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

210

Liquid-metal heat transfer in a cocurrent- flow, double-pipe heat exchanger is investigated  

NASA Technical Reports Server (NTRS)

Analysis of liquid-metal heat transfer in cocurrent-flow, double-pipe heat exchangers shows that heat-transfer coefficients depend upon the operating conditions of the heat exchanger and that use of the customary design equation to predict heat-exchanger performance leads to significant errors.

Merriam, R. L.

1969-01-01

211

CORRELATING EVAPORATION HEAT TRANSFER COEFFICIENT OF REFRIGERANT R-134a IN A PLATE HEAT EXCHANGER  

E-print Network

1 CORRELATING EVAPORATION HEAT TRANSFER COEFFICIENT OF REFRIGERANT R-134a IN A PLATE HEAT EXCHANGER for evaporation heat transfer coefficient of refrigerant R-134a flowing in a plate heat exchanger. Correlation heat exchanger are found to result in large discrepancies with their own experimental data

Kandlikar, Satish

212

Effects of winglets to augment tube wall heat transfer in louvered fin heat exchangers  

E-print Network

.elsevier.com/locate/ijhmt International Journal of Heat and Mass Transfer 49 (2006) 4058­4069 #12;measurements within the heat exchangerEffects of winglets to augment tube wall heat transfer in louvered fin heat exchangers Paul A transfer along the tube wall of the compact heat exchanger through the use of winglets placed

Thole, Karen A.

213

Preliminary design package for maxi-therm heat exchanger module  

NASA Technical Reports Server (NTRS)

Heat exchangers were developed for use in a solar heating and cooling system installed in a single family dwelling. Each of the three exchangers consisted of a heating and cooling module and a submersed electric water heating element. Information necessary to evaluate the preliminary design of the heat exchanger is presented in terms of the development and verification plans, performance specifications, installation and maintenance, and hazard analysis.

1978-01-01

214

Microchannel Heat Exchangers with Carbon Dioxide  

SciTech Connect

The objective of the present study was to determine the performance of CO{sub 2} microchannel evaporators and gas coolers in operational conditions representing those of residential heat pumps. A set of breadboard prototype microchannel evaporators and gas coolers was developed and tested. The refrigerant in the heat exchangers followed a counter cross-flow path with respect to the airflow direction. The test conditions corresponded to the typical operating conditions of residential heat pumps. In addition, a second set of commercial microchannel evaporators and gas coolers was tested for a less comprehensive range of operating conditions. The test results were reduced and a comprehensive data analysis, including comparison with the previous studies in this field, was performed. Capacity and pressure drop of the evaporator and gas cooler for the range of parameters studied were analyzed and are documented in this report. A gas cooler performance prediction model based on non-dimensional parameters was also developed and results are discussed as well. In addition, in the present study, experiments were conducted to evaluate capacities and pressure drops for sub-critical CO{sub 2} flow boiling and transcritical CO{sub 2} gas cooling in microchannel heat exchangers. An extensive review of the literature failed to indicate any previous systematic study in this area, suggesting a lack of fundamental understanding of the phenomena and a lack of comprehensive data that would quantify the performance potential of CO{sub 2} microchannel heat exchangers for the application at hand. All experimental tests were successfully conducted with an energy balance within {+-}3%. The only exceptions to this were experiments at very low saturation temperatures (-23 C), where energy balances were as high as 10%. In the case of evaporators, it was found that a lower saturation temperature (especially when moisture condensation occurs) improves the overall heat transfer coefficient significantly. However, under such conditions, air side pressure drop also increases when moisture condensation occurs. An increase in airflow rate also increases the overall heat transfer coefficient. Air side pressure drop mainly depends on airflow rate. For the gas cooler, a significant portion of the heat transfer occurred in the first heat exchanger module on the refrigerant inlet side. The temperature and pressure of CO{sub 2} significantly affect the heat transfer and fluid flow characteristics due to some important properties (such as specific heat, density, and viscosity). In the transcritical region, performance of CO{sub 2} strongly depends on the operating temperature and pressure. Semi-empirical models were developed for predictions of CO{sub 2} evaporator and gas cooler system capacities. The evaporator model introduced two new factors to account for the effects of air-side moisture condensate and refrigerant outlet superheat. The model agreed with the experimental results within {+-}13%. The gas cooler model, based on non-dimensional parameters, successfully predicted the experimental results within {+-}20%. Recommendations for future work on this project include redesigning headers and/or introducing flow mixers to avoid flow mal-distribution problems, devising new defrosting techniques, and improving numerical models. These recommendations are described in more detail at the end of this report.

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

2001-09-15

215

A simplified methodology for sizing ground coupled heat pump heat exchangers in cooling dominated climates  

E-print Network

- Comparison of heat exchanger sizing methods for Houston. . . . . 9. 2- Comparison of heat exchanger sizing methods for Dallas. . . . . . . . 99 99 DEFINITION OF SYMBOLS A COP P SEER ron Surface Area (m~) Specific Heat (I/kg-'K) Coefficient...- Comparison of heat exchanger sizing methods for Houston. . . . . 9. 2- Comparison of heat exchanger sizing methods for Dallas. . . . . . . . 99 99 DEFINITION OF SYMBOLS A COP P SEER ron Surface Area (m~) Specific Heat (I/kg-'K) Coefficient...

Gonzalez, Jose Antonio

2012-06-07

216

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

217

Analysis of Influencing Factors of Heat Transfer Performance of Heat Pipe Heat Exchanger  

Microsoft Academic Search

Heat transfer performance of heat pipe heat exchanger affected by many factors, such as the opening temperature of the heat pipe, the rate of fluid-filled, the physical nature of liquid refrigerant, the work temperature of tube, angle, tube spacing, tube length, hot and cold fluid flow and wind speed. The above-mentioned parameters can not be measured because of Test conditions,

Zhang Jie; Ren Yan; Zhang Lihong; Liang Huimin

2009-01-01

218

A hybrid genetic algorithm for synthesis of heat exchanger networks  

Microsoft Academic Search

A new hybrid genetic algorithm for optimal design of heat exchanger networks is developed. The mathematical model used in the algorithm is based on an explicit solution of stream temperatures of heat exchanger networks with the stage-wise superstructure. By taking heat transfer areas and heat capacity flow rates as genes in the genetic algorithm, the thermal performance and total cost

Xing Luo; Qing-Yun Wen; Georg Fieg

2009-01-01

219

A fundamentally new approach to air-cooled heat exchangers  

Microsoft Academic Search

We describe breakthrough results obtained in a feasibility study of a fundamentally new architecture for air-cooled heat exchangers. A longstanding but largely unrealized opportunity in energy efficiency concerns the performance of air-cooled heat exchangers used in air conditioners, heat pumps, and refrigeration equipment. In the case of residential air conditioners, for example, the typical performance of the air cooled heat

Koplow; Jeffrey P

2010-01-01

220

Condensation in horizontal heat exchanger tubes  

SciTech Connect

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

Leyer, S.; Zacharias, T.; Maisberger, F.; Lamm, M. [AREVA NP GmbH, Paul-Gossen-Strasse 100, Erlangen, 91052 (Germany); Vallee, C.; Beyer, M.; Hampel, U. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstrasse 400, Dresden, 01328 (Germany)

2012-07-01

221

Expanded microchannel heat exchanger: design, fabrication and preliminary experimental test  

E-print Network

This paper first reviews non-traditional heat exchanger geometry, laser welding, practical issues with microchannel heat exchangers, and high effectiveness heat exchangers. Existing microchannel heat exchangers have low material costs, but high manufacturing costs. This paper presents a new expanded microchannel heat exchanger design and accompanying continuous manufacturing technique for potential low-cost production. Polymer heat exchangers have the potential for high effectiveness. The paper discusses one possible joining method - a new type of laser welding named "forward conduction welding," used to fabricate the prototype. The expanded heat exchanger has the potential to have counter-flow, cross-flow, or parallel-flow configurations, be used for all types of fluids, and be made of polymers, metals, or polymer-ceramic precursors. The cost and ineffectiveness reduction may be an order of magnitude or more, saving a large fraction of primary energy. The measured effectiveness of the prototype with 28 micro...

Denkenberger, David C; Pearce, Joshua M; Zhai, John; 10.1177/0957650912442781

2012-01-01

222

High-temperature self-circulating thermoacoustic heat exchanger  

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

223

Thermographic analysis of flow distribution in compact heat exchangers for a Formula 1 car  

NASA Astrophysics Data System (ADS)

A non-intrusive approach is investigated to calculate the internal flow distribution in heat exchangers. In particular, the liquid flow rate can be determined in each tube of an air-liquid finned-tube heat exchanger. A purposely designed test bench impresses a sudden change of temperature of the liquid flowing through the heat exchanger. The thermal transient that follows is monitored by a thermographic camera. This measures the rise of surface temperature along each tube. The temperature evolution pattern is then correlated to the flow rate in the tube by simple mathematical processing. The heat exchanger is tested in still air. Modification is not required. The approach is tested on heat exchangers for a F1 race car, with encouraging results.

Caffagni, E.; Levoni, P.; Piraccini, M.; Muscio, A.; Corticelli, M. A.; Barozzi, G. S.

2007-01-01

224

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

SciTech Connect

Design details of a compact heat exchanger and supporting hardware for heat recuperation in a high-temperature electrolysis application are presented. The recuperative heat exchanger uses a vacuum-brazed plate-fin design and operates between 300 and 800°C. It includes corrugated inserts for enhancement of heat transfer coefficients and extended heat transfer surface area. Two recuperative heat exchangers are required per each four-stack electrolysis module. The heat exchangers are mated to a base manifold unit that distributes the inlet and outlet flows to and from the four electrolysis stacks. Results of heat exchanger design calculations and assembly details are also presented.

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

2008-11-01

225

Oxidizer heat exchangers for rocket engine operation in idle modes  

NASA Technical Reports Server (NTRS)

The heat exchanger concept is discussed together with its role in rocket engine operation in idle modes. Two heat exchanger designs (low and high heat transfer) utilizing different approaches to achieve stable oxygen vaporization are presented as well as their performance test results. It is concluded that compact and lightweight heat exchangers can be used in a stable manner under the 'idle' operating conditions expected with the RL10 rocket engine.

Kanic, P. G.; Kmiec, T. D.

1987-01-01

226

Industrial applications for LIGA-fabricated micro heat exchangers  

Microsoft Academic Search

One of the well-known benefits of micro scale is enhanced heat transfer. This fact provides the motivation for fabricating a variety of micro heat exchangers using derivatives of the LIGA micromachining process. These heat exchangers can be made of polymers, nickel (electroplated or electroless), or ceramics (Si3N4 and alumina are presently being investigated). These heat exchangers are envisioned for applications

Kevin W. Kelly; Chad Harris; Lyndon S. Stephens; Christophe Marques; Dan Foley

2001-01-01

227

Package embedded heat exchanger for stacked multi-chip module  

Microsoft Academic Search

This paper describes a polymer type micro-heat exchanger applicable to 272 BGA multi-chip module (MCM). Usually stacked MCM becomes easily overheated at low dissipated power due to the lack of heat path. To overcome this problem, we fabricated a polymer type micro-heat exchanger between chips. Normally, the heat exchanger is fabricated by high thermal conductive substrate such as metal, silicon,

Haehyung Lee; Yongwon Jeong; Joonghan Shin; Joonghyun Baek; Moonkoo Kang; Kukjin Chun

2004-01-01

228

Optimization of cross flow heat exchangers for thermoelectric waste heat recovery  

Microsoft Academic Search

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

Douglas T. Crane; Gregory S. Jackson

2004-01-01

229

Ring-shaped microchannel heat exchanger based on turning process  

Microsoft Academic Search

A ring-shaped microchannel heat exchanger based on turning process is developed. Guide vanes are designed and added for enhancing the flow distribution uniformity among microchannels. The performance of the ring-shaped microchannel heat exchanger with or without guide vanes is investigated by experiments. The influence of the flow distribution uniformity among microchannels on the heat transfer performance is analyzed. The results

Yong Tang; Zhanshu He; Minqiang Pan; Jiabao Wang

2010-01-01

230

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

231

Comparisons of the heat transfer and pressure drop of the microchannel and minichannel heat exchangers  

Microsoft Academic Search

The present study investigated the comparisons of the heat transfer and pressure drop of the microchannel and minichannel\\u000a heat exchangers, both numerically and experimentally. The results obtained from this study indicated that the heat transfer\\u000a rate obtained from microchannel heat exchanger was higher than those obtained from the minichannel heat exchangers; however,\\u000a the pressure drops obtained from the microchannel heat

Thanhtrung Dang; Jyh-Tong Teng

2011-01-01

232

Air-cooled heat exchangers: Conventional and unconventional  

Microsoft Academic Search

Wet-surface air-cooled heat exchangers, presently thought of as unconventional, should be considered for applications where fin-tube air coolers are not used. Wet-Surface coolers have advantages where fin-tube exchangers may not supply enough duty, especially during hot weather. They can also cool to temperatures below the capability of cooling water exchangers. Air-cooled heat exchangers made their first appearance in petroleum refineries

Kals

1994-01-01

233

Heat exchanger development at Reaction Engines Ltd.  

NASA Astrophysics Data System (ADS)

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

Varvill, Richard

2010-05-01

234

Heat exchanger for fuel cell power plant reformer  

DOEpatents

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

Misage, Robert (Manchester, CT); Scheffler, Glenn W. (Tolland, CT); Setzer, Herbert J. (Ellington, CT); Margiott, Paul R. (Manchester, CT); Parenti, Jr., Edmund K. (Manchester, CT)

1988-01-01

235

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

E-print Network

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

236

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

237

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

238

Industrial applications for LIGA-fabricated micro heat exchangers  

NASA Astrophysics Data System (ADS)

One of the well-known benefits of micro scale is enhanced heat transfer. This fact provides the motivation for fabricating a variety of micro heat exchangers using derivatives of the LIGA micromachining process. These heat exchangers can be made of polymers, nickel (electroplated or electroless), or ceramics (Si3N4 and alumina are presently being investigated). These heat exchangers are envisioned for applications such as gas turbine blades, mechanical seals and/or bearings, boilers, condensers, radiators, evaporators, electronic component cooling, and catalytic converters. In this paper, methods to fabricate an array of heat exchangers for different applications are described. In addition, simple analytic models that illustrate the motivation for fabricating micro cross flow heat exchanges are shown to compare favorably with experimental heat transfer results.

Kelly, Kevin W.; Harris, Chad; Stephens, Lyndon S.; Marques, Christophe; Foley, Dan

2001-10-01

239

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

240

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

241

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

Microsoft Academic Search

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 7.0m2 and a depth of 1.5m was built at Khon Kaen in North-Eastern Thailand (16°27?N102°E). Heat was successfully extracted

Sura Tundee; Pradit Terdtoon; Phrut Sakulchangsatjatai; Randeep Singh; Aliakbar Akbarzadeh

2010-01-01

242

Application of thermal energy storage to process heat recovery, Phase III, heat exchanger evaluation  

Microsoft Academic Search

The overall goals of the Phase III Heat Exchanger Evaluation are to develop data which will enable the design of a heat exchanger suitable for long-term continuous operation in the aluminum plant pollution control system environment and to assure that the installation of such a device will have no negative impact upon the existing processes. This heat exchanger's function is

Katter

1981-01-01

243

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

Microsoft Academic Search

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

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

2011-01-01

244

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

Microsoft Academic Search

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

Christina L. Cain

1989-01-01

245

Predicting yearly energy recovery and dehumidification enhancement with a heat pipe heat exchanger using typical meteorological year data in the tropics  

Microsoft Academic Search

An investigation was carried out to study the effect of an air-to-air heat pipe heat exchanger on the energy recovery and\\u000a dehumidification enhancement of the air conditioning system in tropical climates. For this purpose, the performance of a heat\\u000a pipe heat exchanger, which was experiencing tropical ambient air in its evaporator section and fan coil unit, was monitored\\u000a during one

Yat Huang Yau; Mohammad Ahmadzadehtalatapeh

2011-01-01

246

The empirical study of a four-row heat pipe heat exchanger to predict the year-round energy recovery in the tropics  

Microsoft Academic Search

The effect of heat pipe heat exchanger on the heat recovery was studied in the tropics. The performance of the heat exchanger was monitored during the one week of operation (168 h) to find out the performance characteristic curves. Three coil face velocities namely, 2, 2.2 and 2.5 m\\/s were tested and the temperature of return air was controlled at

YH Yau; M Ahmadzadehtalatapeh

2011-01-01

247

Protective coating for copper in aluminum heat exchangers  

NASA Technical Reports Server (NTRS)

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

Avazian, R.

1978-01-01

248

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

249

Test and evaluation of a geothermal heat exchanger  

Microsoft Academic Search

A small-scale, tube-in-shell heat exchanger with four sections in series was tested with geothermal brine. The brine inlet temperature was approximately 355F and contained 14,500 ppm dissolved solids. Scale was deposited on the heat exchanger tubes as heat was extracted from the brine and caused the overall heat transfer coefficient to decrease with time. Tube materials tested were titanium, carbon

G. L. Lombard

1975-01-01

250

Test and evaluation of a geothermal heat exchanger. Final report  

Microsoft Academic Search

A small-scale, tube-in-shell heat exchanger with four sections in series was tested with geothermal brine from the Nowlin No. 1 well at Heber, CA. The brine inlet temperature was approximately 355F and contained 14,500 ppm dissolved solids. Scale was deposited on the heat exchanger tubes as heat was extracted from the brine and caused the overall heat transfer coefficient to

Lombard

1975-01-01

251

Evaluation of porous media heat exchangers for fusion applications  

Microsoft Academic Search

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

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

1996-01-01

252

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

Microsoft Academic Search

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

P. M. Dussinger; J. R. Hartenstine

1992-01-01

253

Optimization of conduits' shape in micro heat exchangers  

Microsoft Academic Search

An approximate theory is derived to compute the thermal resistances of flat plate micro heat exchangers whose surfaces are heated with uniform flux. It is demonstrated that the thermal resistance can be minimized by proper selection of uniform conduit geometry. Further reductions in the maximum heated surface temperature and in the heated surface temperature gradients can be achieved by varying

Haim H. Bau

1998-01-01

254

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

Microsoft Academic Search

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

M. S Söylemez

2003-01-01

255

Performance of a serpentine heat exchanger: Part I – Effectiveness and heat transfer characteristics  

Microsoft Academic Search

This work deals with the heat transfer performance of a cross-flow serpentine heat exchanger for waste heat recovery. The heat exchanger is made of rectangular tubes which afford a narrow spacing for the flow outside the tubes (channel flow). In the analysis, the channel flow and the tube flow were considered as an unmixed flow and a mixed flow, respectively.

Jung-Yang San; Gean-Sheng Lin; Kai-Li Pai

2009-01-01

256

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

ERIC Educational Resources Information Center

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

Corbett, Robert J.; Miller, Barbara

257

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

Microsoft Academic Search

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

Kraft

1975-01-01

258

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

Microsoft Academic Search

A Capillary Pumped Two-Phase Heat Transport Loop (CAPL) Flight Experiment, currently planned for 1993, will provide microgravity verification of the prototype capillary pumped loop (CPL) thermal control system for EOS. CAPL employs a heat pipe heat exchanger (HPHX) to couple the condenser section of the CPL to the radiator assembly. A prototype HPHX consisting of a heat exchanger (HX), a

Jentung Ku; Seokgeun Yun; Edward J. Kroliczek

1992-01-01

259

Fouling of HVAC fin and tube heat exchangers  

Microsoft Academic Search

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.

Jeffrey Siegel; Van P. Carey

2001-01-01

260

Hydraulic and thermal design of a gas microchannel heat exchanger  

Microsoft Academic Search

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

Yahui Yang; Juergen J Brandner; Gian Luca Morini

2012-01-01

261

Testing and simulation of ceramic micro heat exchangers  

Microsoft Academic Search

Ceramic microstructure devices in form of counterflow and crossflow microchannel heat exchangers have been manufactured to be used in thermal and chemical process engineering. The performance has been tested using water as a test fluid with maximum flow rates of 120kg\\/h. The results of the measurements are compared with global estimations using standard correlations for heat exchangers and a more

B. Alm; U. Imke; R. Knitter; U. Schygulla; S. Zimmermann

2008-01-01

262

Microchannel crossflow fluid heat exchanger and method for its fabrication  

Microsoft Academic Search

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

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

1985-01-01

263

Microchannel crossflow fluid heat exchanger and method for its fabrication  

Microsoft Academic Search

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

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

1982-01-01

264

Foundation Heat Exchanger Model and Design Tool Development and Validation  

E-print Network

Foundation Heat Exchanger Model and Design Tool Development and Validation The attached document.1080/10789669.2013.774887) Fan, D., S. Rees, J. Spitler. 2013. A dynamic thermal network approach to the modeling of Foundation of Dynamic Thermal Networks to the Modelling of Foundation Heat Exchangers. Building Simulation 2011. Sydney

265

Condensing Heat Exchanger for Optimization of Energy Efficiency  

E-print Network

for every 40F (4.5C) reduction in flue gas stack temperature. In the CHX® condensing heat exchanger, all gas wetted surfaces are covered with DuPont Teflon®. The Teflon covered heat exchanger surfaces are impervious to all acids normally resulting from...

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

266

IntroductiontoProcessEngineering(PTG) 4. Heat exchangers;  

E-print Network

ProcessEngineering(PTG) VST rz13 5/72 Heat exchangers: Geometries /1 Schematics of (a) counterflow, (b) parallel flow, (c/6 IntroductiontoProcessEngineering(PTG) VST rz13 6/72 Schematic of mixed and unmixed heat exchangers: (a) One fluid Temperature distributions of fluid in (a) counterflow, (b) parallel flow, and (c) 1 shell pass and 2 tubes

Zevenhoven, Ron

267

Mode localization of a component cooling water heat exchanger  

Microsoft Academic Search

In a nuclear power plant, the tubes of a component cooling water heat exchanger are frequently affected by cold and hot fluid shock waves. Thus, tubes are often found to be worn out. This wear may alter the dynamics of the tubes and introduce mode localization in the heat exchanger. This paper examines mode localization in a component cooling water

Bo-Wun Huang; Huang-Kuang Kung

2005-01-01

268

PRELIMINARY RESULTS OF STATISTICAL DYNAMIC EXPERIMENTS ON A HEAT EXCHANGER  

Microsoft Academic Search

The inherent noise signals present in a heat exchanger were recorded and ; analyzed in order to determine some of the statistical dynamic characteristics of ; the heat exchanger. Preliminary results show that the primary-side temperature ; frequency response may be determined by analyzing the inherent noise. The ; secondary-side temperature frequency response and cross-coupled-temperature ; frequency responses between primary

E. R. Corran; J. D. Cummins

1962-01-01

269

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

270

Heat as a tracer to determine streambed water exchanges  

USGS Publications Warehouse

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

Constantz, J.

2010-01-01

271

The Influence of Availability Costs on Optimal Heat Exchanger Size  

E-print Network

THE INFLUENCE OF AVAILABILITY COSTS ON OPTIMAL H~ EXCHANGER SIZE Larry C. Witte Professor of Mechanical Engineering University of Houston Houston, TX 77004 examples of such a process. I I Optimizing heat exchangers based on se cond law... rather than first law co~idera? tions e~ures that the most efficient use of available energy is being made. ~chnique8 for second-law optimising heat exchangers have been developed recently that are straightforward and simple. The main diffi culty...

Witte, L. C.

272

Self-defrosting recuperative air-to-air heat exchanger  

DOEpatents

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

Drake, Richard L. (Delmar, NY)

1993-01-01

273

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

Microsoft Academic Search

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 m² and a depth of 1.5 m was built at Khon Kaen in North-Eastern Thailand (16 27'N102 E).

Sura Tundee; Pradit Terdtoon; Phrut Sakulchangsatjatai; Randeep Singh; Aliakbar Akbarzadeh

2010-01-01

274

Mapping Heat Exchange in an Allosteric Protein  

PubMed Central

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

Gupta, Shaweta; Auerbach, Anthony

2011-01-01

275

Comparative study of rotating regenerators and heat-pipe heat exchangers  

Microsoft Academic Search

A heat wheel was purchased and installed for air to air heat recovery on a Terylene fiber drying and setting oven at ICI Wilton. At the same time a heat pipe heat exchanger was prepared at IRD and tested under controlled conditions. The heat wheel was then replaced by the heat pipe unit. During this procedure measurements were made regularly

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

1980-01-01

276

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

277

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

278

Characteristics of cooling water fouling in a heat exchange system  

Microsoft Academic Search

This study investigated the efficiency of the physical water treatment method in preventing and controlling fouling accumulation\\u000a on heat transfer surfaces in a laboratory heat exchange system with tap and artificial water. To investigate the fouling characteristics,\\u000a an experimental test facility with a plate type heat exchange system was newly built, where cooling and hot water moved in\\u000a opposite directions

Sun-Kyung Sung; Sang-Ho Suh; Dong-Woo Kim

2008-01-01

279

A closer look at integrally finned-tube heat exchangers  

SciTech Connect

Extensive research has been done on the mechanisms of heat transfer, yet much of the technology that has evolved from these endeavors is underutilized. For example, the integrally finned-tube heat exchanger has been used in refrigeration for evaporators, recuperators and condensers, as well as in refinery reboilers. However, the exchanger`s use in other applications, such as reboilers, gas coolers and condensers, has been relatively slow to catch on. Perhaps this is because of a lack of knowledge and appreciation of this type of shell-and-tube exchanger. Although many papers have been written about the successful use of integral fin tubes, no volume on them, along with a readable guide to the practical application and utilization of finned-tube exchangers, is in existence. This paper attempts to remedy this lack by summarizing the advantages and applications of this type of heat exchanger.

Pase, G.K. Sr. [Joseph Oat Corp., Camden, NJ (United States)

1996-02-01

280

Study on the Heat-flow Controlable Heat Exchanger (first report)  

NASA Astrophysics Data System (ADS)

Heat generating devices and heat recovery systems are desired to control the heat flow and the temperature, contrary to the prior thermo-siphon uncontrolable heat flow. Then, authors have developed a heat flow controlable heat exchanger having a bubble pump mechanism without movable par t. The heat exchanger is consisted of evaporator, condenser, vapor passage pipe, liquid return pipe with a reverse-U type pipe, and heater located on the reverse pipe. Further the system encloses evaporating liquid and is possible to control heat flow between the evaporator to the condenser by adjusting the heater power. This paper presents experimental results on the system. The following results are obtained. (1) The heat exchanger can control heat flow between the evaporator to the condenser by adjusting the heater input which is smaller about 1/20 the above heat flow. (2) The complex heat flow controlable heat exchanger system is possible to control the output temperature by changing its operating heat exchanger number. (3) This heat exchanger is useful to the heat recovery at the room, the temperature control at the space, and the system joining heat storage system.

Hamano, Masayoshi; Yanadori, Michio; Kawano, Tomohiro

281

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

PubMed

A new kind of ultrasonically-assisted heat exchanger has been designed, built and studied. It can be seen as a vibrating heat exchanger. A comprehensive description of the overall experimental set-up is provided, i.e. of the test rig and the acquisition system. Data acquisition and processing are explained step-by-step with a detailed example of graph obtained and how, from these experimental data, energy balance is calculated on the heat exchanger. It is demonstrated that ultrasound can be used efficiently as a heat transfer enhancement technique, even in such complex systems as heat exchangers. PMID:22546297

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

2012-11-01

282

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.

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

1985-01-01

283

Supercritical Heat Exchanger Field Test (SHEFT). 1: Field performance data on shell-and-tube heat exchangers in geothermal service  

Microsoft Academic Search

Field performance on shell-and-tube heat exchangers in geothermal service are presented. The test data were taken for geothermal brine on the tube side and hydrocarbon on the shell side in counterflow for six primary heat exchangers, and for hydrocarbon on the shell side and cooling water on the tube side for the condenser. Test data were for heating isobutane, 90\\/10

L. F. Silvester; L. O. Veaulaurier; K. F. Mirk; R. L. Fulton

1981-01-01

284

METALLIC MICRO HEAT EXCHANGERS: PROPERTIES, APPLICATIONS AND LONG TERM STABILITY  

Microsoft Academic Search

Micro heat exchangers, which until recently have been implemented only at laboratory scale, are now being available for industrial applications. They are well known for their superior heat transfer properties due to the large surface-to-volume ratio. But there are little data available on the long term stability of these devices. In this paper application several application examples for micro heat

J. J. Brandner; W. Benzinger; U. Schygulla; S. Zimmermann; K. Schubert

2008-01-01

285

Active heat exchange system development for latent heat thermal energy storage  

Microsoft Academic Search

Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube

R. T. Lefrois; A. K. Mathur

1980-01-01

286

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

SciTech Connect

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

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

1992-01-01

287

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

SciTech Connect

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

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

1992-12-01

288

Active heat exchange system development for latent heat thermal energy storage  

Microsoft Academic Search

Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange

R. T. Lefrois; G. R. Knowles; A. K. Mathur; J. Budimir

1979-01-01

289

Air-Side Flow and Heat Transfer in Compact Heat Exchangers: A Discussion of Enhancement Mechanisms  

Microsoft Academic Search

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

ANTHONY M. JACOBI; RAMESH K. SHAH

1998-01-01

290

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

E-print Network

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

Chen, Y.; Zhang, J.

2006-01-01

291

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

Microsoft Academic Search

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

Yuanfang Zhu; Ruihua Wang; Yating Zhang

2010-01-01

292

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

Microsoft Academic Search

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

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

2010-01-01

293

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

Microsoft Academic Search

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

C. S. Rogers; D. M. Mills

1992-01-01

294

Parametric performance studies on fluidized-bed heat exchangers  

NASA Astrophysics Data System (ADS)

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

Stoeffler, R. C.

1982-01-01

295

Predicted energy savings for a residential heat pump utilizing a fluidized-bed heat exchanger  

Microsoft Academic Search

The objective of this study was to determine if the energy efficiency of an optimized, state-of-the-art, residential heat pump could be increased by utilizing a fluidized-bed heat exchanger in place of a conventional heat exchanger on the outdoor side of the heat pump system. Using the Oak Ridge National Laboratory (ORNL) Heat Pump Model, comparisons were made between the advanced

Vineyard

1984-01-01

296

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

297

Performance of heat exchangers used in whole body perfusion circuits.  

PubMed Central

The performance of some commonly used heat exchangers has been investigated with particular reference to the effect of varying the water flow. The results demonstrate that there is considerable variation in the performance of most units when the water flow is changed. It is suggested that more information should be provided by the manufacturers of heat exchangers and that there should be a supply of water in cardiothoracic theatres at a sufficient pressure to allow the full performance of the heat exchangers to be realized. PMID:1198400

Bethune, D W; Gill, R D; Wheeldon, D R

1975-01-01

298

SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS  

SciTech Connect

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

DR. DENNIS NAGLE; DR. DAJIE ZHANG

2009-03-26

299

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

Code of Federal Regulations, 2010 CFR

... false Equipment leak and heat exchange system provisions...63.502 Equipment leak and heat exchange system provisions...506(e)(6). (h) If specific items of equipment, comprising...purposes of this subpart. (n) Heat exchange system...

2010-07-01

300

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

Code of Federal Regulations, 2013 CFR

...standards and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat exchange system is equal to or...reactor as the surrogate indicator of heat exchanger system leaks when complying...

2013-07-01

301

Performance of Counterflow Microchannel Heat Exchangers Subjected to External Heat Transfer  

Microsoft Academic Search

This article analyzes the effect of external heat transfer on the thermal performance of counterflow microchannel heat exchangers. Equations for predicting the axial temperature and the effectiveness of both fluids as well as the heat transferred between the fluids, while operating under external heating or cooling conditions, are provided in this article. External heating may decrease and increase the effectiveness

Bobby Mathew; Hisham Hegab

2010-01-01

302

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

303

Simplified method of calculating temperature fields in the checkerwork of regenerative heat-exchangers  

NASA Astrophysics Data System (ADS)

Equations are given with the aid of a priori information on the plant. It is possible to obtain data on the temperature fields in the checkerwork of regenerative heat exchangers with sufficient accuracy. These are needed for solving problems of monitoring and controlling the regenerator performance. An example is given of the application of the method to a blast furnace hot blast stove.

Shklyar, F. R.; Yaroshenko, Y. G.; Trofimov, N. I.; Sovetkin, V. L.; Malkin, V. M.

1983-07-01

304

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); Kissinger, John A. (Del Mar, CA)

1986-01-01

305

Development and demonstration of improved gas to gas heat pipe heat exchangers for the recovery of residual heat. Final report  

Microsoft Academic Search

A new form of heat exchanger has been developed with the following characteristics: (1) compact modular construction: the modules are built up to provide the final exchanger face area as required by the available exhaust gas stream; (2) the above construction allows in situ dismantling of the heat exchanger for cleaning in case of internal fouling; (3) in order that

M. J. Davies; G. H. Chaffey

2008-01-01

306

Evaluation of fluid bed heat exchanger optimization parameters. Final report  

SciTech Connect

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

Not Available

1980-03-01

307

Basic study of radiative and convective heat exchange in a room with floor heating  

SciTech Connect

Radiative heat exchange is a dominant factor in a room with a heated floor. Convective heat exchange is also important because it is increased by air circulation caused by natural convection. Surface temperatures inside the room increase when surfaces receive radiative heat flux originating from the heated floor. Since convective heat exchange takes place between the room air and the inside surfaces, it directly affects the room air temperature. Although radiative heat exchange does not influence room air temperature directly, it decreases the temperature difference between inside surfaces. These behaviors determine the wall surface temperatures and the amount of heat flux between the room air and the inside surfaces. This paper presents several basic characteristics of heat transfer on inside surfaces and temperature and velocity distribution in a room with a heated floor. Basic experiments and numerical analysis on radiative and convective heat transfer were carried out. The following conclusions were obtained: (1) a floor heating experiment produces approximately uniform air temperature except near windows where cold drafts lower the air temperature; (2) numerical analysis qualitatively predicts this kind of room air temperature distribution within 1.8 F (1 C); (3) convective heat exchange constitutes approximately half of the total heat exchange based on numerical analysis.

Hanibuchi, Haruo [Sekisui House Ltd., Kizu, Kyoto (Japan); Hokoi, Shuichi [Kyoto Univ., Sakyo, Kyoto (Japan). Dept. of Architecture and Environmental Design

1998-10-01

308

Energy effectiveness of simultaneous heat and mass exchange devices  

E-print Network

Simultaneous heat and mass exchange devices such as cooling towers, humidifiers and dehumidifiers are widely used in the power generation, desalination, air conditioning, and refrigeration industries. For design and rating ...

Narayan, G. Prakash

2010-01-01

309

1-MWE heat exchangers for OTEC. Final design report  

SciTech Connect

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

Sprouse, A.M.

1980-06-19

310

Progress in heat pipe and porous heat exchanger technology  

Microsoft Academic Search

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

A. V. Luikov; L. L. Vasiliev

1975-01-01

311

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

PubMed

Small birds and mammals commonly minimize respiratory heat loss with reciprocating counterflow exchangers in their nasal passageways. These animals extract heat from the air in an exhalation to warm those passageways and then use that heat to warm the subsequent inhalation. Although the near-constant volume of buildings precludes direct application of the device, a pair of such exchangers located remotely from each other circumvents that problem. A very simple and crudely constructed small-scale physical model of the device worked well enough as a heat conserver to suggest utility as a ventilator for buildings. PMID:19920310

Vogel, Steven

2009-12-01

312

Parametric performance studies on fluidized-bed heat exchangers  

NASA Astrophysics Data System (ADS)

The performance of single and multistage shallow fluidized beds for possible application to the recovery of heat from sources as waste heat, and coal combustion or coal gasification were investigated. The following tests are investigated: (1) the effects of fouling due to liquid condensate in the gas stream of fluidized beds which are staged using baffle plates; and (3) the effects of different heat exchanger surface geometries. The conditions fouling by a liquid condensate are selected. Modifications are made to the fluidized bed heat exchanger facility for the fouling experiments.

Stoffler, R. C.

1981-10-01

313

RESEARCH CONCERNING DESIGN OF HIGH EFFICIENCY BRAZED PLATE HEAT EXCHANGERS  

E-print Network

Brazed plate heat exchangers are carving a big chunk out of the heat transfer industry with their compact size and high efficiency design. Brazed plate units are up to six times smaller than alternative methods of heat exchange with the same capacity. This is because of their unique construction: more then hundred corrugated stainless steel plates are brazed together with every second plate turned 180 degrees. This design creates two highly turbulent fluid channels that flow in opposite directions over a massive surface area. The result of this construction is a significantly higher heat transfer coefficient with less required surface area and outstanding performance characteristics.

Ionel Olaru; Codrin Cobrea

314

Optimal assignment of multiple utilities in heat exchange networks  

Microsoft Academic Search

Existing numerical geometry-based techniques, developed by [A.I.A. Salama, Numerical techniques for determining heat energy targets in pinch analysis, Computers & Chemical Engineering 29 (2005) 1861–1866; A.I.A. Salama, Determination of the optimal heat energy targets in heat pinch analysis using a geometry-based approach, Computers & Chemical Engineering 30 (2006) 758–764], have been extended to optimally assign multiple utilities in heat exchange

A. I. A. Salama

2009-01-01

315

Process Heat Exchanger Options for the Advanced 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

2011-06-01

316

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

317

Heat Exchanger Fouling- Prediction, Measurement and Mitigation  

E-print Network

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

Peterson, G. R.

318

A Comparison Study of Numerical Simulations in a Borehole Heat Exchanger Field  

Microsoft Academic Search

Borehole heat exchanger (BHE) field with heat-pump was installed at the building of the Korea Earthquake Research Center in Korea Institute of Geoscience and Mineral (KIGAM). It consists of 28 BHEs equipped with a double U-tube and three monitoring wells. Two BHEs are equipped with optical fiber that measures temperature of the U-tube. A borehole televiewer survey was conducted in

S. Kim; G. Bae; K. Lee; B. Shim; Y. Song

2007-01-01

319

Modeling of plate heat exchangers with generalized configurations  

Microsoft Academic Search

A mathematical model is developed in algorithmic form for the steady-state simulation of gasketed plate heat exchangers with generalized configurations. The configuration is defined by the number of channels, number of passes at each side, fluid locations, feed connection locations and type of channel-flow. The main purposes of this model are to study the configuration influence on the exchanger performance

Jorge A. W. Gut; José M. Pinto

2003-01-01

320

Design of chemical reactors of the heat exchanger type  

E-print Network

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

McBeth, Lloyd Theodore

2012-06-07

321

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

322

Analysis of Spray-Cooled Finned-Tube Heat Exchangers  

Microsoft Academic Search

A mathematical model has been developed for the analysis of spray-cooled finned-tube heat exchangers. An experimental study was conducted on a four-pass, finned-tube heat exchanger in a vertical air\\/water mist flow to validate the model, and the results compared well with the predicted performance.Significant performance enhancement (up to 3.5 times the dry performance) was found by spraying relatively small amounts

A. A. DREYER; D. E. KRIEL; P. J. ERENS

1992-01-01

323

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

324

Prototype solar-heated hot water systems and double-walled heat exchangers  

NASA Technical Reports Server (NTRS)

Development progress made on two solar-heated hot water systems and two heat exchangers is reported. The development, manufacture, installation, maintenance, problem resolution, and system evaluation are described.

1978-01-01

325

Sensible and latent heat transfer in cross-counterflow gas-to-gas heat exchangers  

SciTech Connect

Simultaneous heat and mass transfer during condensation in cross-counterflow gas-to-gas heat exchangers has been analyzed. The coupled heat and mass transfer equations are derived for boundary-layer controlled heat and mass transfer and include longitudinal heat conduction in the exchanger wall. A numerical method of the finite-difference type is applied to the steady-state performance. Temperature and absolute humidity distributions are calculated for exchanger parameters that are typical in air conditioning systems. Temperature and humidity efficiencies together with frosting limits are evaluated for different inlet air conditions.

Holmberg, R.B. (Flakt Evaporator AB, S-551 84 Jonkoping (SE))

1989-02-01

326

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

327

Proceedings of the 1987 International Symposium on Condensing Heat Exchangers  

NASA Astrophysics Data System (ADS)

Technology for advanced, high-efficiency heating equipment was discussed. Twenty-six papers from nine countries were presented, covering various aspects of such equipment designed to operate with condensing heat exchangers - including furnaces, boilers, water heaters, and fuel-fired heat pumps. The emphasis was on residential and commercial equipment, and both gas- and oil-firing were considered. Specific topics included: (1) condensate characterization; (2) metallic materials for condensing heat exchangers - aluminum and stainless steel; (3) non-metallic materials for heat exchangers and vents - ceramics and polymers; (4) example condensing units and systems; (5) experience with oil-fired condensing units; (6) field experience; (7) design techniques and efficiency test procedures. Papers are indexed separately.

1987-04-01

328

Mechanisms of heat exchange between water and rock in karst conduits  

Microsoft Academic Search

Heat conduction through rock largely controls heat exchange in karst conduitsCharacteristic time scales determine the dominant heat exchange mechanismA new karst heat transport model is validated using field data

M. D. Covington; A. J. Luhmann; F. Gabrovšek; M. O. Saar; C. M. Wicks

2011-01-01

329

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

330

A Proposal of a Nonlinear Observer Applied to the Heat Exchange Phenomena in a Double Pipe Heat Exchanger  

Microsoft Academic Search

\\u000a The aim of this paper is to show the heat exchange phenomena applied in a double pipe heat exchanger pilot plant scale, by\\u000a considering a macroscopic dynamic model, that describes the evolution of the temperature of hot and cold fluids in the equipment.\\u000a The proposed dynamic model is function of mean effective temperature difference and of the thermodynamic and transport

J. F. Briones; M. A. Paz; J. L. Gallegos; J. I. O. Rodriguez; S. C. Garibo

331

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

SciTech Connect

The PS1 heat exchanger is one of three prototype heat exchangers built by Atomic Welders before Meyer was given the contract to build the Satellite Refrigerator Heat Exchanger components. This heat exchanger was first put into operation in July 1983. In November 1991, this heat exchanger experienced a failure in the shell of heat exchanger 1 causing nitrogen to contaminate the helium in the refrigerator. The resulting contamination plugged heat exchanger 3. The break occurred at a weld that connects a 0.25 inch thick ring to heat exchanger 1. The failure appears to be a fatigue of the shell due to temperature oscillations. The flow rate through the break was measured to be 1.0 scfm for a pressure drop over the crack of 50 psi. An ANSYS analysis of the failure area indicates that the stress would be 83,000 psi if the metal did not yield. This is based on cooling down the shell to 80K from 300K with the shell side helium on the outside of the shell at 300K. This is the largest change in temperature that occurs during operation. During normal operations, the temperature swings are not nearly this large, however temperatures down to 80K are not unusual (LN2 overflowing pot). The highest temperatures are typically 260K. The analysis makes no attempt to estimate the stress concentration factor at this weld but there is no doubt that it is greater than 1. No estimate as to the number of cycles to cause failure was calculated nor any estimate as to the actual number of cycles was made.

Squires, B.

1992-11-01

332

Integrated heat exchange and heat storage system using low-temperature reactions  

Microsoft Academic Search

An integrated heat exchange and heat storage system using thermochemical reactions which comprises a first plurality of parallel adjacent tubes containing an element for storing and yielding heat; and a second plurality of tubes parallel to said first plurality of tubes and interposed therebetween and containing a fluid heat vehicle, the first and second plurality of tubes being disposed in

U. Buzzi; F. Farfaletti-casali; L. Nobel; F. Reiter

1982-01-01

333

Assessment of heating dynamics in a prototype magnetic induction heat exchanger  

Microsoft Academic Search

Magnetic induction (MI) heating has the potential to be used in food processing systems to heat flowing food material. Due to electromagnetic properties, MI heating theoretically has the ability to evenly distribute energy to heat exchanger surfaces in a manner that is more energy efficient and gentler to the processing stream than current steam-boiler systems. The goal of this project

Philip C Sadler

2011-01-01

334

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

E-print Network

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

Gaskill, Travis

2012-02-14

335

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

Microsoft Academic Search

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

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

2005-01-01

336

Integrated Approach to Revamping Heat Exchangers Networks  

E-print Network

'1(U"veS o lM<"h"'"," I-Z=.... I @ ThetlMll RMlA5.::=.J - I'.!J Figure 7. Optimum thermal performance results of the Aspen Hetran rigorous design for the new exchanger from within the Aspen Plus simulation environment. 031 Figure 8. Setting plan...'1(U"veS o lM<"h"'"," I-Z=.... I @ ThetlMll RMlA5.::=.J - I'.!J Figure 7. Optimum thermal performance results of the Aspen Hetran rigorous design for the new exchanger from within the Aspen Plus simulation environment. 031 Figure 8. Setting plan...

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

337

Heat transfer effectiveness of three-fluid separated heat pipe exchanger  

NASA Astrophysics Data System (ADS)

A heat transfer model for three-fluid separated heat pipe exchanger was analyzed, and the temperature transfer matrix for general three-fluid separated heat exchanger working in parallel-flow or counter-flow mode was obtained. It was found that the forms of temperature transfer matrix are similar for heat pipe rows with equal or different heat transfer surface area. Furthermore, by using the temperature transfer matrix of the heat pipe exchanger, the relationship between heat transfer effectiveness ? 1, ? 2 and M, NTU, U, ?t i were derived for the exchanger operating in parallel-flow or counter-flow mode, and a simple special example was adopted to demonstrate the correctness of these relationships.

Shi, Chengming; Wang, Yang; Yang, Ying; Liao, Quan

2011-03-01

338

Air Circulation and Heat Exchange Under Reduced Pressures  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

339

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

Microsoft Academic Search

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

YH Yau

2008-01-01

340

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

E-print Network

The effects of outdoor heat exchanger hydrophobic treatment on the performance of an air source heat pump were investigated. The base case tests used a bare aluminum outdoor heat exchanger in the experimental setup. The base case test results were...

Parker, Brandon DeWayne

2012-06-07

341

Numerical modeling of pin-fin micro heat exchangers  

Microsoft Academic Search

A micro heat exchanger (MHE) can effectively control the temperature of surfaces in high heat flux applications. In this study, several turbulence models are analyzed using a 3D finite element model of a MHE. The MHE consists of a narrow planar flow passage between flat parallel plates with small cylindrical pin fins spanning these walls. The pin fin array geometry

E. Galvis; B. A. Jubran; F. Xi. K. Behdinan; Z. Fawaz

2008-01-01

342

Fully developed thermal behaviors for parallel flow microchannel heat exchanger  

Microsoft Academic Search

The hydrodynamics and thermal behaviors of the flow in micro-heat exchanger parallel-plate are investigated numerically. The model that combines both the continuum approach and the possibility of slip at the boundary is adopted in the study. Effects of different parameters, such as, Knudsen number (Kn), heat capacity ratio (Cr), the effectiveness (e) and number of transfer units (NTU) are investigated.

M. A. Al-Nimr; M. Maqableh; A. F. Khadrawi; S. A. Ammourah

2009-01-01

343

Practical thermodynamic tools for heat exchanger design engineers  

Microsoft Academic Search

This book provides an approach to the design of heat exchanger equipment as is used throughout the mechanical and chemical industries, offering practical information that goes beyond the present state of this applied art. It introduces a number of guidelines to be satisfied by physical laws in thermal engineering, treating thermodynamics, fluid mechanics, and heat transfer as a unified body

Soumerai

1987-01-01

344

Two-phase flow distribution in compact heat exchanger manifolds  

Microsoft Academic Search

In this paper an experimental study to investigate two-phase flow distribution in compact heat exchanger manifolds is presented. An experimental test rig to measure the flow distribution in realistic manifold geometries and under relevant operating conditions was built. To elucidate the effect on the flow distribution, the following factors are investigated: vapour fraction at the manifold inlet, heating load on

Sivert Vist; Jostein Pettersen

2004-01-01

345

Evaluation of porous media heat exchangers for plasma facing components  

Microsoft Academic Search

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

J. Rosenfeld; J. Lindemuth

1993-01-01

346

A Freezable Heat Exchanger for Space Suit Radiator Systems  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

347

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

348

Quantification of the heat exchange of chicken eggs.  

PubMed

In the incubation process of domestic avian eggs, the development of the embryo is mainly influenced by the physical microenvironment around the egg. Only small spatiotemporal deviations in the optimal incubator air temperature are allowed to optimize hatchability and hatchling quality. The temperature of the embryo depends on 3 factors: (1) the air temperature, (2) the exchange of heat between the egg and its microenvironment and (3) the time-variable heat production of the embryo. Theoretical estimates on the heat exchange between an egg and its physical microenvironment are approximated using equations that assume an approximate spherical shape for eggs. The objective of this research was to determine the heat transfer between the eggshell and its microenvironment and then compare this value to various theoretical estimates. By using experimental data, the overall and the convective heat transfer coefficients were determined as a function of heat production, air humidity, air speed, and air temperature. Heat transfer was not affected by air humidity but solely by air temperature, embryonic heat generation, and air speed and flow around eggs. Also, heat transfer in forced-air incubators occurs mainly by convective heat loss, which is dependent on the speed of airflow. A vertical airflow is more efficient than a horizontal airflow in transferring heat from the egg. We showed that describing an egg as a sphere underestimated convective heat transfer by 33% and was, therefore, too simplistic to accurately assess actual heat transfer from real eggs. PMID:15782902

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

2005-03-01

349

Wireless Health Data Exchange for Home Healthcare Monitoring Systems  

PubMed Central

Ubiquitous home healthcare systems have been playing an increasingly significant role in the treatment and management of chronic diseases, such as diabetes and hypertension, but progress has been hampered by the lack of standardization in the exchange of medical health care information. In an effort to establish standardization, this paper proposes a home healthcare monitoring system data exchange scheme between the HL7 standard and the IEEE1451 standard. IEEE1451 is a standard for special sensor networks, such as industrial control and smart homes, and defines a suite of interfaces that communicate among heterogeneous networks. HL7 is the standard for medical information exchange among medical organizations and medical personnel. While it provides a flexible data exchange in health care domains, it does not provide for data exchange with sensors. Thus, it is necessary to develop a data exchange schema to convert data between the HL7 and the IEEE1451 standard. This paper proposes a schema that can exchange data between HL7 devices and the monitoring device, and conforms to the IEEE 1451 standard. The experimental results and conclusions of this approach are presented and show the feasibility of the proposed exchange schema. PMID:22319296

Lee, Malrey; Gatton, Thomas M.

2010-01-01

350

Direct use geothermal applications for brazed plate heat exchangers  

NASA Astrophysics Data System (ADS)

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 H2S 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 H2S 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 deg or greater. Size limitations restrict applications to 100 gpm and/or 200 sq ft heat transfer surface area.

Rafferty, K.

1993-02-01

351

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

352

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

353

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

354

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

355

Pressure drop across spined heat exchangers in crossflow  

E-print Network

15 . 22 . 23 . 36 . 37 . 43 . 57 10. 12. 13. Physical Geometry of Plate Finned Tubes in Figures 30-47 Weight of Spined Tube, Bare Tube, and Individual Spine rr(ft ') for the Four Heat Exchangers, 1/4-in Nominal Diameter u...(ft ) for the Four Heat Exchangers, 1/8-in Nominal Diameter . 58 72 . 82 14. Spined Tube Heat Transfer Data for One Row . 89 1X LIST OF FIGURES Figure Geometry of plate fins and helical fins. 1/8-inch nominal diameter spined tubes. 1/4-inch nominal...

Carranza, Richard Guy

2012-06-07

356

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

357

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

358

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

Microsoft Academic Search

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

K. S. Ong

2010-01-01

359

Compact\\/micro-heat exchangers – Their role in heat pumping equipment  

Microsoft Academic Search

Compact and micro-heat exchangers have many advantages over their larger counterparts, particularly when used to handle clean fluid streams, either single- or two-phase. Probably the most exciting feature of such heat exchangers is their ability to operate with close approach temperatures, leading to high effectiveness. This can be particularly beneficial when the exchangers are used in power-producing or power-consuming systems, where the

Peter A. Kew; David A. Reay

2011-01-01

360

Carbon-Fiber Brush Heat Exchangers  

NASA Technical Reports Server (NTRS)

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

Knowles, Timothy R.

2004-01-01

361

Micro heat exchanger by using MEMS impinging jets  

Microsoft Academic Search

A micro impinging-jet heat exchanger is presented. Heat transfer is studied for single jet, slot arrays and jet arrays. In order to facilitate micro heat transfer measurements with these devices, a MEMS sensor chip, which has an 8×8 temperature-sensor array on one side, and an integrated heater on the other side has been designed and fabricated. This sensor chip allows

S. Wu; J. Mai; Y. C. Tai; C. M. Ho

1999-01-01

362

Direct-contact closed-loop heat exchanger  

DOEpatents

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

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

1981-11-02

363

Thermodynamic Efficiency of Heat Exchange Devices  

E-print Network

irreversibilities. The reclamation of what was formerly 'waste heat' by using additional, or more efficient, equipment has become not only economically feasible, but sometimes essential. A thermodynamic efficiency based on the second law of thermodynamics...

Witte, L. C.; Shamsundar, N.

1982-01-01

364

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.

365

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

366

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

367

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

PubMed

Enhancement of heat transfers in counterflow plate heat exchanger due to presence of an intermediate auxiliary fluid flow is investigated. The intermediate auxiliary channel is supported by transverse conducting pins. The momentum and energy equations for the primary fluids are solved numerically and validated against a derived approximate analytical solution. A parametric study including the effect of the various plate heat exchanger, and auxiliary channel dimensionless parameters is conducted. Different enhancement performance indicators are computed. The various trends of parameters that can better enhance heat transfer rates above those for the conventional plate heat exchanger are identified. Large enhancement factors are obtained under fully developed flow conditions. The maximum enhancement factors can be increased by above 8.0- and 5.0-fold for the step and exponential distributions of the pins, respectively. Finally, counterflow plate heat exchangers with auxiliary fluid flows are recommended over the typical ones if these flows can be provided with the least cost. PMID:24719572

Khaled, A-R A

2014-01-01

368

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

369

Online optimization and choice of optimization variables for control of heat exchanger networks  

E-print Network

On­line optimization and choice of optimization variables for control of heat exchanger networks B operation of a general heat exchanger network with given structure, heat exchanger areas and stream data to any heat exchanger network. Using this model periodically for optimization, the operating conditions

Skogestad, Sigurd

370

On-line optimization and choice of optimization variables for control of heat exchanger networks  

E-print Network

On-line optimization and choice of optimization variables for control of heat exchanger networks B operation of a general heat exchanger network with given structure, heat exchanger areas and stream data to any heat exchanger network. Using this model periodically for optimization, the operating conditions

Skogestad, Sigurd

371

Model based methodology development for energy recovery in flash heat exchange systems  

E-print Network

Model based methodology development for energy recovery in flash heat exchange systems Problem with a condensing heat exchanger can be used when heat exchange is required between two streams and where at leastH, consistency etc.). To increase the efficiency of heat exchange, a cascade of these units in series can be used

McCarthy, John E.

372

On-line optimization of a crude unit heat exchanger Statoil Mongstad  

E-print Network

On-line optimization of a crude unit heat exchanger network Tore Lid #3; Statoil Mongstad N-5954 modeling and on-line optimization of a crude unit heat exchanger network at the Statoil Mongstad re#12;nery oil in the heat exchanger network. The steady state mass and energy balance of the 20 heat exchangers

Skogestad, Sigurd

373

Heat transfer and friction characteristics of typical wavy fin-and-tube heat exchangers  

Microsoft Academic Search

Extensive experiments on the heat transfer and pressure drop characteristics of typical wavy fin-and-tube heat exchangers were carried out. In the present study, 18 samples of wavy fin-and-tube heat exchangers with different geometrical parameters, including the number of tube rows, fin pitch, and flow arrangements, were tested in a wind tunnel. Results are presented as plots of the Fanning friction

W. L. Fu; C. T. Chang

1997-01-01

374

Design of Intelligent Predictive Controller for Electrically Heated Micro Heat Exchanger  

Microsoft Academic Search

\\u000a An intelligent predictive control with locally linear neurofuzzy identifier and numerically optimization procedure has been\\u000a proposed for temperature control of electrically heated micro heat exchanger. To this end, first the dynamics of the micro\\u000a heat exchanger is identified using Locally Linear Model Tree (LOLIMOT) algorithm. Then, the predictive control strategy based\\u000a on the LOLIMOT model of the plant is applied

Farzad Habibipour Roudsari; Mahdi Jalili-kharaajoo; Mohammad Khajepour

2005-01-01

375

Specific features of heat transfer via micro and nanochannels in micro-heat exchangers  

Microsoft Academic Search

The present research aims to study the way heat transfer occurs within micro and nano channels of a micro-heat exchanger. Several such heat exchangers were manufactured and a test rig was conceived and built in order to test them. For the experimental investigations, a method to test copper micro-tubes reaching 40mum in depth and 0.35 mm in width was advanced.

Ioan Mihai; Cornel Suciu

2010-01-01

376

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

Microsoft Academic Search

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

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

1986-01-01

377

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

Microsoft Academic Search

\\u000a Using the external heat exchanger in large-scale CFB boilers can control combustion and heat transfer separately, make the\\u000a adjustments of bed temperature and steam temperature convenient. The state of gas-solid two phase flow in the external heat\\u000a exchanger is bubbling fluidized bed, but differs from the regular one as there is a directional flow in it. Consequently,\\u000a the temperature distribution

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

378

Electrically enhanced fluidized bed heat exchanger  

SciTech Connect

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

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

1994-05-01

379

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

SciTech Connect

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

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

2011-04-01

380

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

381

Liquid Salt Heat Exchanger Technology for VHTR Based Applications  

SciTech Connect

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

Mark Anderson; Kumar Sridhara; Todd Allen; Per Peterson

2012-10-11

382

Design of Heat Exchanger for Heat Recovery in CHP Systems  

E-print Network

The objective of this research is to review issues related to the design of heat recovery unit in Combined Heat and Power (CHP) systems. To meet specific needs of CHP systems, configurations can be altered to affect different factors of the design...

Kozman, T. A.; Kaur, B.; Lee, J.

383

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

384

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

Microsoft Academic Search

This paper presents a new predictive model of droplet flow and heat transfer from molten salt droplets in a direct contact\\u000a heat exchanger. The process is designed to recover heat from molten CuCl in a thermochemical copper–chlorine (Cu–Cl) cycle\\u000a of hydrogen production. This heat recovery occurs through the physical interaction between high temperature CuCl droplets\\u000a and air. Convective heat transfer

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

2010-01-01

385

NICKEL FOAM HEAT EXCHANGERS Kristin Wild  

E-print Network

of Mechanical and Industrial Engineering March 2009 #12;ABSTRACT A water circulation loop was designed and built to test hydraulic and heat transfer characteristics of a 10 PPI Nickel foam sample. The apparatus squares method. Hydraulic relationships were graphed for pressure drop, flow rate, Reynolds number

Sun, Yu

386

Heat exchanger development at Reaction Engines Ltd  

Microsoft Academic Search

The SABRE engine for SKYLON has a sophisticated thermodynamic cycle with heat transfer between the fluid streams. The intake airflow is cooled in an efficient counterflow precooler, consisting of many thousand small bore thin wall tubes. Precooler manufacturing technology has been under investigation at REL for a number of years with the result that flightweight matrix modules can now be

Richard Varvill

2010-01-01

387

Heat exchanger module for stirling engines  

SciTech Connect

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

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

1985-02-12

388

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

389

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

390

Final design and testing of a low-pressure drop heat exchanger with integral heat pipe  

NASA Astrophysics Data System (ADS)

The paper describes the design of a heat pipe heat exchanger (HPHX) compatible with capillary pumped loop (CPL) thermal control systems and the results of performance tests conducted at a CPL test facility. Steady-state tests evaluated HPHX performance parametrically as a function of condenser saturation temperature, heat exchanger temperature difference, and heat exchanger heat load. Transient tests evaluated HPHX performance as a function of normally occurring thermal control system transient events, such as heat load changes, heat sink temperature changes, and thermal control system setpoint change. An HPHX compatible with a CPL thermal control system was successfully tested. The selected condenser flow passage geometry with helix angle was proven to be a very effective condenser design. The observed condensation performance was much better than predicted due to the dramatic effect of flow turbulence on condensation effectiveness.

Fredley, J. E.; Warren, P. H.

1990-01-01

391

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

392

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

NASA Astrophysics Data System (ADS)

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

Zeng, Heyi; Diao, Nairen; Fang, Zhaohong

2003-02-01

393

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

394

A study on the simulation and experiment of a microchannel counter-flow heat exchanger  

Microsoft Academic Search

Numerical simulations and experimental tests were carried out to study the fluid flow and heat transfer characteristics for a rectangular-shaped microchannel heat exchanger. Moreover, influences of gravity to heat transfer and pressure drop behaviors of the microchannel heat exchanger were presented by variation of the physical inclinations of the microchannel heat exchanger system used for experiments. For experimental results, a

Thanhtrung Dang; Jyh-tong Teng; Jiann-cherng Chu

2010-01-01

395

SIMULATION OF COMPACT HEAT EXCHANGERS USING GLOBAL REGRESSION AND SOFT COMPUTING  

E-print Network

SIMULATION OF COMPACT HEAT EXCHANGERS USING GLOBAL REGRESSION AND SOFT COMPUTING A Dissertation investigates enhancement in accuracy of heat rate predictions in compact fin-tube heat exchangers. The sources determined and later applied to heat exchanger data. The direct heat-rate estimations are more accurate. #12

Sen, Mihir

396

Experimental Validation of Thermal Model of Counter Flow Microchannel Heat Exchangers Subjected to External Heat Flux  

Microsoft Academic Search

The effect of uniform external heat flux on the effectiveness of counter flow microchannel heat exchangers is experimentally studied in this article for validating an existing thermal model. The model validated in this study is a one dimensional model previously developed by the same authors. The model is validated to be independent of microchannel profile, hydraulic diameter, and heat capacity

Bobby Mathew; Hisham Hegab

2013-01-01

397

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

NASA Technical Reports Server (NTRS)

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

1977-01-01

398

Predicting yearly energy savings using BIN weather data with heat-pipe heat exchangers  

Microsoft Academic Search

In an earlier paper (Mathur, 1996), the author had investigated the impact that a heat pipe heat exchanger (HPHE) has on the energy consumption and the peak demand on an existing air conditioning system. A detailed performance investigation was carried out for a number of cities for year round operation of the HVAC system with HPHE. Heating degree days and

G. D. Mathur

1997-01-01

399

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

400

Heat transfer in the coolant channel of a heat-exchanger system based on fluctuation theories  

Microsoft Academic Search

We present a model to study the heat transfer in the coolant channel of a heat-exchanger system. Such a model introduces thermal fluctuations as well as external noises due to different mechanisms of heat interchange. A unified treatment of both kinds of noise is carried out. The stationary mean value of the channel temperature is studied, obtaining effective transport coefficients

A. Díaz-Guilera; M. A. Rodríguez; J. M. Rubí

1988-01-01

401

Diffusion Welding of Compact Heat Exchangers for Nuclear Applications  

SciTech Connect

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

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

2012-06-01

402

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

403

40 CFR 63.1086 - How must I monitor for leaks to cooling water?  

Code of Federal Regulations, 2010 CFR

...Manufacturing Process Units: Heat Exchange Systems and Waste Operations... Monitoring Requirements for Heat Exchange Systems § 63.1086...three sets of samples at each heat exchanger entrance and exit...acceptable monitoring program are ion specific electrode monitoring,...

2010-07-01

404

Heat energy Q: -energy exchanged between systems if they have a different temperature  

E-print Network

About heat Heat energy Q: - energy exchanged between systems if they have a different temperature - heat flows from higher to lower temperature - without temperature difference, no heat is exchanged If a system is receiving or releasing heat, then this heat is called a) Sensible heat, if the system changes

Boyd, Sylke

405

Heat Pump Cycle with Solution Circuit and Internal Heat Exchange  

E-print Network

Vapor compression heat pumps which employ working fluid mixtures rather than pure substances offer significant advantages leading to larger temperature lifts at low pressure ratios or to completely new applications. The main feature of such cycles...

Radermacher, R.

406

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

407

Modeling Air-Cooled Heat Sinks as Heat Exchangers  

Microsoft Academic Search

Heat sink performance is generally described by quoting its thermal resistance, Rth, in degrees C per Watt. When Rth is based on data, it can be relied on. When it is predicted, there may be problems. Rth=1\\/hAeff, the 'convective resistance model', can over-predict the heat transfer by more than 100%. Adding a 'fluid resistance' can get to the right result,

Robert J. Moffat

2007-01-01

408

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

409

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

410

Predicted energy savings for a residential heat pump utilizing a fluidized-bed heat exchanger  

SciTech Connect

The objective of this study was to determine if the energy efficiency of an optimized, state-of-the-art, residential heat pump could be increased by utilizing a fluidized-bed heat exchanger in place of a conventional heat exchanger on the outdoor side of the heat pump system. Using the Oak Ridge National Laboratory (ORNL) Heat Pump Model, comparisons were made between the advanced system (utilizing a fluidized-bed heat exchanger) and the base system (optimized, state-of-the-art) in eleven cities. The calculated annual energy savings for the advanced system ranged from 29 to 777 kWh/y, with the largest savings occurring in areas where the frosting and defrosting losses of the base unit are greatest, such as in the northeast.

Vineyard, E.A.

1984-01-01

411

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

SciTech Connect

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

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

2004-07-01

412

Optimal Heat Exchanger Network Synthesis Using Particle Swarm Optimization  

Microsoft Academic Search

1. Abstract Heat exchanger,network,(HEN) synthesis has been a well -studied subject over the past decades. Many studies and methodologies were proposed to make possible the energy recovery between process streams, minimizing the utilities consumption, the number of heat transfer equipment,and the gaseous and liquid pollutant emissions from the combustible burn and water usage. Most of papers published in t his

M. A. S. S. Ravagnani; A. P. Silva; E. C. Biscaia Jr; J. A. Caballero

2008-01-01

413

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

414

Numerical modeling of pin–fin micro heat exchangers  

Microsoft Academic Search

A micro heat exchanger (MHE) can effectively control the temperature of surfaces in high heat flux applications. In this study,\\u000a several turbulence models are analyzed using a 3D finite element model of a MHE. The MHE consists of a narrow planar flow\\u000a passage between flat parallel plates with small cylindrical pin fins spanning these walls. The pin fin array geometry

E. Galvis; B. A. Jubran; F. X. I. K. Behdinan; Z. Fawaz

2008-01-01

415

Thermo-Hydraulic Behavior of Microchannel Heat Exchanger System  

Microsoft Academic Search

This article presents an experimental study of thermo-hydrodynamic phenomena in a microchannel heat exchanger system. The aim of this investigation is to develop correlations between flow\\/thermal characteristics in the manifolds and the heat transfer performance of the microchannel. A rectangular microchannel fabricated by a laser-machining technique with channel width and hydraulic diameter of 87 ?m and 0.17 mm, respectively, and

A. G. Agwu Nnanna

2010-01-01

416

Design and Test of Tube & Shell Heat Exchangers for Potential  

E-print Network

and Technology, South Korea #12;Reynolds number Re VD = µ Nusselt number 0.8 0.4 0.023Re Pr hD Nu k = = HeatDesign and Test of Tube & Shell Heat Exchangers for Potential OTEC Application Jeong-Tae Kwon1 transfer coefficient h k h Nu D = Thermal resistance 0ln( / )1 1 1 1 1 2 i i i o o i i o o D D R UA U A U

417

Automatic Tube Cleaning Systems for Condensers and Heat Exchangers  

E-print Network

AUTOMATIC TUBE CLEANING SYSTEMS FOR CONDENSERS AND HEAT EXCHANGERS Kaveh Someah/V.P. Sales & Mktg. WSA Engineered Systems, Milwaukee, WI (414) 354-6470 ABSTRACT The on-line Automatic Tube Cleaning Systems (ATCS) for condensers and heat...-line cleaning systems, i.e. the Brush and Basket and the Sponge Rubber Ball type for various industrial applications will be discussed. Case studies will be used to demonstrate the actual plant operating and maintenance cost savings from these systems...

Someah, K.

418

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

419

Development of a Computer Heating Monitoring System and Its Applications  

E-print Network

This paper develops a computer heating monitoring system, introduces the components and principles of the monitoring system, and provides a study on its application to residential building heating including analysis of indoor and outdoor air...

Chen, H.; Li, D.; Shen, L.

2006-01-01

420

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

421

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid, forces it to evaporate, and thus cools it down. We show that this temperature difference can be used for an efficient heat exchange process. We investigate the use of a commercial parallel plate heat exchanger with a small liquid xenon detector. Although we expected to be limited by the available cooling power to flow rates of about 2 SLPM, rates in excess of 12 SLPM can easily be sustained, limited only by the pump speed and the impedance of the flow loop. The heat exchanger operates with an efficiency of (96.8 +/- 0.5)%. This opens the possibility for fast xenon gas recirculation in large-scale experiments, while minimizing thermal losses.

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-03-04

422

An experimental study on the heat transfer characteristics of a heat pipe heat exchanger with latent heat storage. Part II: Simultaneous charging\\/discharging modes  

Microsoft Academic Search

In this part of the paper, the performance of the simultaneous charging\\/discharging operation modes of the heat pipe heat exchanger with latent heat storage is experimentally studied. The experimental results show that the device may operate under either the fluid to fluid heat transfer with charging heat to the phase change material (PCM) or the fluid to fluid heat transfer

Zhongliang Liu; Zengyi Wang; Chongfang Ma

2006-01-01

423

DESIGN, CONSTRUCTION, AND PERFORMANCE OF TWO COMPACT AIR COOLED SODIUM HEAT EXCHANGERS  

Microsoft Academic Search

A bare-tube crossflow heat exchanger and a finned-tube crossflow heat ; exchanger were designed, constructed, and tested. The exchangers have sodium as ; a tube side fluid and air as a shell side fluid and are constructed of Inconel. ; The bare-tube heat exchanger has three unmixed passes on the sodium side and one ; mixed pass on the air

W. F. Brown; R. W. Fisher; H. M. Black

1963-01-01

424

Constructal multi-scale design of compact micro-tube heat sinks and heat exchangers  

Microsoft Academic Search

A constructal multi-scale design approach is examined for micro-tube heat sinks and heat exchangers. Heat transfer per unit volume is increased by considering the use of additional micro-tubes placed in the intersticial regions of a circular tube array. Three constructs are considered in the proposed analysis. As the system complexity increases, the heat transfer rate increases, and exceeds the theoretical

Y. S. Muzychka

2007-01-01

425

Constructal multi-scale design of compact micro-tube heat sinks and heat exchangers  

Microsoft Academic Search

A constructal multi-scale design approach is examined for micro-tube heat sinks and heat exchangers. Heat transfer per unit volume is increased by considering the use of additional micro-tubes placed in the intersticial regions of a circular tube array. Three constructs are considered in the proposed analysis. As the system complexity increases, the heat transfer rate increases, and exceeds the theoretical

Y. S. Muzychka

2006-01-01

426

Mathematical simulation of conjugate heat exchange in heating furnaces with a moving bottom  

Microsoft Academic Search

A mathematical model of conjugate heat exchange in heating furnaces with a moving bottom (ring furnaces and walking-beam furnaces)\\u000a has been developed. The model allows one to determine the heating of steel blanks in these furnaces with account for all mechanisms\\u000a of heat transfer in the high-temperature working region of a furnace, in its lining, and in the steel blanks.

V. I. Timoshpol’skii; M. L. German; P. S. Grinchuk; S. M. Kabishov

2006-01-01

427

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

Microsoft Academic Search

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

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

2008-01-01

428

Comparison of heat pump performance using fin-and-tube and microchannel heat exchangers under frost conditions  

Microsoft Academic Search

Vapor compression heat pumps are drawing more attention in energy saving applications. Microchannel heat exchangers can provide higher performance via less core volume and reduce system refrigerant charge, but little is known about their performance in heat pump systems under frosting conditions. In this study, the system performance of a commercial heat pump using microchannel heat exchangers as evaporator is

Liang-Liang Shao; Liang Yang; Chun-Lu Zhang

2010-01-01

429

Measurements and Predictions of the Heat Transfer at the Tube-Fin Junction for Louvered Fin Heat Exchangers  

E-print Network

Measurements and Predictions of the Heat Transfer at the Tube-Fin Junction for Louvered Fin Heat to the International Journal of Compact Heat Exchangers, May 2003 #12;2 Measurements and Predictions of the Heat Transfer at the Tube-Fin Junction for Louvered Fin Heat Exchangers Abstract The dominant thermal resistance

Thole, Karen A.

430

Active heat exchange system development for latent heat thermal energy storage  

NASA Technical Reports Server (NTRS)

Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out.

Lefrois, R. T.; Knowles, G. R.; Mathur, A. K.; Budimir, J.

1979-01-01

431

Axial conduction in a thick-wall matrix heat exchanger  

Microsoft Academic Search

Solutions are developed for temperature distributions and ineffectiveness for a high Ntu matrix heat exchanger having simultaneous axial conduction in the single phase (matrix\\/fluid) flow channels and separating wall. A scale analysis of the governing equations shows a large disparity in length scales for the conduction and convection effects, thus indicating a singular perturbation problem. Solutions for both balanced and

G. F. Jones

1995-01-01

432

Preliminary evaluation of tubular ceramic heat exchanger materials. Final report  

Microsoft Academic Search

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

D. L. Mann; K. H. Styhr

1977-01-01

433

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

434

Modeling non-adiabatic parallel flow microchannel heat exchangers  

Microsoft Academic Search

This article analyzes parallel flow microchannel heat exchangers with non-adiabatic thermal condition imposed on the wall separating the fluids and the ambient. For purposes of analysis, a thermal model comprising of two governing equations, one for each of the fluids, is developed and analytically solved to obtain equations for calculating the axial temperature and thereby the effectiveness of both fluids.

B. Mathew; H. Hegab

2011-01-01

435

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

436

Heat Exchanger Exergetic Lifecycle Cost Optimization using Evolutionary Algorithms  

Microsoft Academic Search

Considering lifecycle cost analysis during the design phase of thermal systems gives the design effort more worth. Furthermore thermodynamic exergetic optimization is a proven useful method for determining the most lifecycle cost optimal design of thermal systems for given thermodynamic constraints. The most thermodynamic efficient heat exchanger design basing on first law analysis may not be the better method for

LIAQUAT ALI KHAN; ALI EL-GHALBAN

2008-01-01

437

Polymer Heat Exchangers—History, Opportunities, and Challenges  

Microsoft Academic Search

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

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

2012-01-01

438

Acoustic resonance in heat-exchanger tube banks  

Microsoft Academic Search

The fluid mechanics of acoustic resonance in heat exchanger tube bundles was studied. Three phases of work were performed: (1) review of data and theory; (2) development of a model for the acoustics of tube bundles; and (3) construction of a tube bundle wind tunnel and a tube array model. The review indicates that there are no predictive tools or

R. D. Blevins

1983-01-01

439

Control of marine biofouling in heat exchanger systems  

SciTech Connect

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.

Mitchell, R.; Benson, P.

1981-01-01

440

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

441

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

442

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

443

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

444

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

445

Flow-induced vibration of component cooling water heat exchangers  

Microsoft Academic Search

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

Y. S. Yeh; S. S. Chen

1990-01-01

446

Thermodynamic optimal design of heat exchangers for an irreversible refrigerator  

Microsoft Academic Search

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

Giuseppe Grazzini; Rinaldo Rinaldi

2001-01-01

447

Heat exchanger for internal combustion engine exhaust, with noise suppressor  

Microsoft Academic Search

This patent describes a noise-suppressing heat exchanger, comprising: wall means, including two opposite header end walls and a perimetrical sidewall, defining an enclosed gas flow space; an outer shell completely, spacedly enclosing the wall means of the gas flow space so as to define a liquid jacket substantially completely surrounding the gas flow space;; the wall means including means mechanically

S. Suzuki; T. Fujita

1986-01-01

448

Heat exchange method and device therefor for thermal energy storage  

Microsoft Academic Search

A heat exchange device for the introduction of thermal energy into and removal of thermal energy from liquid-solid phase change material is described in which the phase change material is maintained in a container, which is slowly rotated about a generally horizontal axis at a substantially constant rotational speed. Means are provided for automatically nucleating the phase change material as

Herrick

1979-01-01

449

Analysis of a Bayonet-Type Counterflow Heat Exchanger with Axial Conduction and Radiative Heat Loss  

Microsoft Academic Search

A counterflow heat exchanger model, based on a bayonet-type configuration, has been developed for predicting the performance of small-scale thermal systems. The purpose of the model is to predict how well a counterflow heat exchanger works for isolating high temperatures for devices that might act as miniature combustors, fuel reformers, or micro-reactors. Three thermal loss mechanisms are considered: (1) flow

Richard B. Peterson; John A. Vanderhoff

2001-01-01

450

The use of helical heat exchanger for heat recovery domestic water-cooled air-conditioners  

Microsoft Academic Search

An experimental study on the performance of a domestic water-cooled air-conditioner (WAC) using tube-in-tube helical heat exchanger for preheating of domestic hot water was carried out. The main aims are to identify the comprehensive energy performance (space cooling and hot water preheating) of the WAC and the optimum design of the helical heat exchanger taking into account the variation in

Yi Xiaowen; W. L. Lee

2009-01-01

451

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

NASA Technical Reports Server (NTRS)

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

Schreiber, Jeffrey G.

1989-01-01

452

Secondary heat exchanger design and comparison for advanced high temperature reactor  

SciTech Connect

Next generation nuclear reactors such as the advanced high temperature reactor (AHTR) are designed to increase energy efficiency in the production of electricity and provide high temperature heat for industrial processes. The efficient transfer of energy for industrial applications depends on the ability to incorporate effective heat exchangers between the nuclear heat transport system and the industrial process heat transport system. This study considers two different types of heat exchangers - helical coiled heat exchanger and printed circuit heat exchanger - as possible options for the AHTR secondary heat exchangers with distributed load analysis and comparison. Comparison is provided for all different cases along with challenges and recommendations. (authors)

Sabharwall, P. [Idaho National Laboratory, Idaho Falls, ID 83415-3860 (United States); Kim, E. S. [Seoul National Univ., P.O. Box 1625, Idaho Falls, ID 83415-3860 (United States); Siahpush, A.; McKellar, M.; Patterson, M. [Idaho National Laboratory, Idaho Falls, ID 83415-3860 (United States)

2012-07-01

453

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

454

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

DOEpatents

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

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

1998-07-21

455

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

DOEpatents

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

Phillips, Benjamin A. (Benton Harbor, MI); Zawacki, Thomas S. (St. Joseph, MI)

1998-07-21

456

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

457

Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins  

Microsoft Academic Search

Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves

Andrew J. Onstad

2009-01-01

458

Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger  

SciTech Connect

Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m{sup 2} and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm{sup 2} area. An impressive 10 kW of power was absorbed on an area of 24 cm{sup 2}. Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m{sup 2} using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented.

YOUCHISON,DENNIS L.; NORTH,MART T.

2000-11-22

459

Air-side thermal hydraulic performance of an integrated fin and micro-channel heat exchanger  

Microsoft Academic Search

An integrated fin and micro-channel heat exchanger has been proposed. For 11 heat exchanger samples with different flow depth, fin height, fin pitch and fin thickness, a series of tests were conducted to determine their effect on the air-side thermal hydraulic performance. The heat transfer coefficient and pressure drop for heat exchangers with different geometrical configurations were reported in terms

Jiong Li; Shuangfeng Wang; Weijun Zhang

2011-01-01

460

Influence of channel geometry on the performance of a counter flow microchannel heat exchanger  

Microsoft Academic Search

Microchannel heat exchangers (MCHE) can be made with channels of various geometries. Their size and shape may have considerable effect on the thermal and hydraulic performance of a heat exchanger. In this paper numerical simulation is carried out to solve 3D developing flow and 3D conjugate heat transfer of a balanced counter flow microchannel heat exchanger (CFMCHE) to evaluate the

Mushtaq I. Hasan; A. A. Rageb; M. Yaghoubi; Homayon Homayoni

2009-01-01

461

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

462

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

Microsoft Academic Search

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

Shadi Mahjoob; Kambiz Vafai

2008-01-01

463

Sea surface exchanges of momentum, heat, and freshwater determined by satellite remote sensing  

E-print Network

1 Sea surface exchanges of momentum, heat, and freshwater determined by satellite remote sensing Sensible heat flux Shortwave radiation Surface wind fields 2 #12;Sea surface exchanges of momentum, heat and the atmosphere communicate through the interfacial exchanges of heat, freshwater, and momentum. While

Yu, Lisan

464

HEAT EXCHANGE IN THE YELLOWFIN TUNA, THUNNUS ALBACARES, AND SKIPJACK TUNA, KATSUWONUS PELAMIS, AND THE  

E-print Network

HEAT EXCHANGE IN THE YELLOWFIN TUNA, THUNNUS ALBACARES, AND SKIPJACK TUNA, KATSUWONUS PELAMIS. The central heat exchanger in T. albacares, while also in the haemal arch, is simpler, consisting of two small not conserve heat. The skipjack tunas, Euthynnu~ and Kat~u'Wonus, have well-developed central heat exchangers

465

A Semi-Empirical Model for Porous Media Heat Exchanger Design Richard A. Wirtz1  

E-print Network

A Semi-Empirical Model for Porous Media Heat Exchanger Design Richard A. Wirtz1 Mechanical-dimensional temperature Introduction Compact heat exchangers invariably incorporate heat transfer augmentation technology matrix at the fluid-solid interface of a compact heat exchanger will also enhance performance

Wirtz, Richard A.

466

Optimal Allocation of Heat Exchanger Inventory in a Serial Type Diabatic Distillation Column  

E-print Network

Optimal Allocation of Heat Exchanger Inventory in a Serial Type Diabatic Distillation Column Edward the column . We have previously shown (Jimenez et al. 2003) that optimaloperation of serial heat exchangers total heat exchanger area in different trays and calculate the optimal allocation of a given heat

Salamon, Peter

467

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

468

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

469

A survey of oscillating flow in Stirling engine heat exchangers  

NASA Technical Reports Server (NTRS)

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

Simon, Terrence W.; Seume, Jorge R.

1988-01-01

470

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

471

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

472

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

473

Modeling of turbulent heat transfer and thermal dispersion for flows in flat plate heat exchangers  

Microsoft Academic Search

In this paper, heat transfer and dispersion for both laminar and turbulent regimes in heat exchangers and nuclear cores are considered. Such hydraulic systems might be seen as spatially periodic porous media. The existence of a turbulent flow within a porous medium structure suggests the use of a spatial average operator, combined to a statistical average operator. Previous works [M.H.J.

F. Pinson; O. Gregoire; M. Quintard; M. Prat; O. Simonin

2007-01-01

474

Heat transfer and flow studies of the liquid droplet heat exchanger  

Microsoft Academic Search

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

A. P. Bruckner; A. Shariatmadar

1987-01-01

475

Heat transfer and friction correlation for compact louvered fin-and-tube heat exchangers  

Microsoft Academic Search

General heat transfer and friction correlations for louver fin geometry having round tube configuration were proposed in the present study. A total of 49 samples of louvered fin-and-tube heat exchangers with different geometrical parameters, including louver pitch, louver height, longitudinal tube pitch, transverse tube pitch, tube diameter, and fin pitch were used to develop the correlations. The proposed correlation describes

C.-C. Wang; C.-J. Lee; C.-T. Chang; S.-P. Lin

1998-01-01

476

Thermoacoustics and related oscillatory heat and fluid flows in micro heat exchangers  

Microsoft Academic Search

Classical linear thermoacoustic theory is applied to compact micro heat exchangers and the validity of such calculus applied to micro scale is discussed. Expressions for the radial profiles and average values of the fluid axial velocity and temperature are demonstrated, formulations for first order friction and heat transfer coefficients of oscillating flows are deduced. It is shown how aerodynamic and

Philippe Nika; Yannick Bailly; François Guermeur

2005-01-01

477

Numerical study of heat transfer enhancement of counter nanofluids flow in rectangular microchannel heat exchanger  

Microsoft Academic Search

The performance of a counter-flow rectangular shaped microchannel heat exchanger (MCHE) using nanofluids was modeled. The 3D steady, laminar developing flow and conjugate heat transfer in aluminum MCHE using finite volume method was solved. The effects of nanofluid types, Re number and nanoparticle concentration on the thermal, and flow fields were examined. It is found that the MCHE performance is

H. A. Mohammed; G. Bhaskaran; N. H. Shuaib; R. Saidur

2011-01-01

478

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

Microsoft Academic Search

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

C. K. Lee; H. N. Lam

2008-01-01

479

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

Microsoft Academic Search

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

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

2010-01-01

480

Hydrodynamics and heat transfer characteristics of a novel heat exchanger with delta-winglet vortex generators  

Microsoft Academic Search

The effects of vortex generators on heat transfer and pressure drop of a novel heat exchanger are investigated using computational fluid dynamics (CFD) method. The Reynolds numbers based on fin collar outside diameter varied from 600 to 2600, the attack angle from 10° to 50°, and the aspect ratio from 1 to 4. The numerical results are also analyzed from

Yong-Gang Lei; Ya-Ling He; Li-Ting Tian; Pan Chu; Wen-Quan Tao

2010-01-01

481

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

Microsoft Academic Search

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

Amanda Pertzborn; Scott Hackel; Greg Nellis; Sanford Klein

2011-01-01

482

Heat Transfer Analysis for a Concentric Tube Heat Exchanger Including the Wall Axial Conduction  

Microsoft Academic Search

The effect of wall axial conduction on the heat transfer in a concentric tube heat exchanger is examined for the inner flow laminar flow regime. The procedure used for the current analysis combines the analytical solution for the inner fluid with a numerical approximation for the wall conduction and has the capability of handling the temperature variation for the outer

Mehmet Emin Arici

2010-01-01

483

Fan cycling strategies and heat pipe heat exchangers provide energy efficient dehumidification  

Microsoft Academic Search

This article describes two methods to reduce energy consumption and peak demand in buildings that require humidity control that were demonstrated at the Salvador Dali Museum in St. Petersburg, Florida. The first method centered on alternative indoor fan cycling strategies and the second method involved the use of heat pipe heat exchangers. Both approaches increased the dehumidification performance of the

Shirey

1995-01-01

484

Heat transfer and pressure drop of ice slurries in plate heat exchangers  

Microsoft Academic Search

Ice slurries can be used both for cold storage in place of chilled water or ice and as a secondary refrigerant since, up to certain concentrations, they can be pumped directly through distribution pipeworks and heat exchangers. For ice slurries to become more widely accepted, however, more engineering information is required on fluid flow and heat transfer characteristics.This paper reports

J. Bellas; I. Chaer; S. A. Tassou

2002-01-01

485

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

486

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. T