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1

Radial flow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

Valenzuela, Javier (Hanover, NH)

2001-01-01

2

Heat exchange system with reversing receiver flow  

Energy Technology Data Exchange (ETDEWEB)

A heat exchange system is described comprising a compressor; first and second heat exchangers; an expansive valve; a receiver; flow direction reversing means; and conduit means interconnecting the compressor, the heat exchangers, the expansion valve, the receiver and the reversing valve to form a system containing refrigerant in which heat can be exchanged in either direction between the exchangers.

Jones, R.D.

1987-04-07

3

Stirling engine with parallel flow heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger system for a stirling engine includes a heater connected to the expansion space by a pair of parallel flow ducts , and a cooler connected to the compression space by a pair of parallel flow ducts. A circulator is arranged in one of the heater ducts and one of the cooler ducts to continuously circulate working fluid from the working space, through the heat exchanger, and back into the same working space. The expansion and compression processes are thereby made more isothermal and the heat exchangers may be made smaller, more effective and with a lower pressure drop.

Vitale, N.G.

1983-01-11

4

Heat flow characteristics of underground closed geothermal heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

In the paper there are presented the heat flow characteristics of an underground closed geothermal heat exchanger (UCGHE). The calculations were performed with the model described in the paper. These characteristics determine how the possible to extract heat flow changes in a function of temperature difference on the input and output of the exchanger. (orig.)

Kujawa, T.; Kaczmarek, R. [Szczecin Univ. of Tech. (Poland). Dept. of Heat Engineering

2006-07-01

5

Characteristics of heat flow in recuperative heat exchangers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simplified model of heat flow in cross-flow tube recuperative heat exchangers (recuperators) was presented in this paper. One of the purposes of this investigation was to analyze changes in the values of some parameters of heat transfer in recuperators during combustion air preheating. The logarit...

Lalovi? Milisav; Radovi? Žarko; Jaukovi? Nada

6

Buoyancy driven flow in counter flow heat exchangers  

Science.gov (United States)

The temperature distribution, the buoyancy head and the flow rate have been studied in a counter flow heat exchanger having buoyancy driven flow on at least one side. The assumptions made for heat flux distribution are varied and the resulting effects on the flow rate and fluid temperatures are studied. A network model is used to simulate the temperature distribution and oil flow rates in an oil-filled power transformer cooled by radiators. It is found that for operating conditions normally found for mineral oil the counter flow assumptions for heat flux distribution gives approximately the same results as assuming uniform heat flux. When a more viscous oil type is used or the radiators are placed lower than normal relative to the heat generating parts, the counter flow assumptions give more reliable results.

Olsson, C. O.

2012-11-01

7

Simulation Studies on A Cross Flow Plate Fin Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available Compact heat exchangers which were initially developed for the aerospace industries in the1940s have been considerably improved in the past few years. The main reasons for the goodperformance of compact heat exchangers are their special design which includes turbulent which inturn use high heat transfer coefficient and resists fouling, and maximum temperature driving forcebetween the hot and cold fluids. Numerous types use special enhancement techniques to achieve therequired heat transfer in smaller plot areas and, in many cases, less initial investment. One such type ofcompact heat exchanger is the Plate-fin heat exchanger. The complexity of compact heat exchangerdesign equations results from the exchangers unique ability to transfer heat between multiple processstreams and a wide array of possible flow configurations. This paper presents the performanceevaluation of cross flow plate fin heat exchanger with several different Gas-Liquid systems.Experimental results such as exchanger effectiveness, overall heat transfer coefficients were calculatedfor the flow systems of Cross flow Heat Exchangers. A steady state model for the outlet temperature ofboth the cold and hot fluid and overall heat transfer coefficient of a plate-fin cross flow heat exchangerwas developed and simulated using MATLAB, which was verified with the experiments conducted.

M. Thirumarimurugan; T. Kannadasan; E. Ramasamy

2008-01-01

8

Characteristics of heat flow in recuperative heat exchangers  

Directory of Open Access Journals (Sweden)

Full Text Available A simplified model of heat flow in cross-flow tube recuperative heat exchangers (recuperators) was presented in this paper. One of the purposes of this investigation was to analyze changes in the values of some parameters of heat transfer in recuperators during combustion air preheating. The logarithmic mean temperature (Atm) and overall heat transfer coefficient (U), are two basic parameters of heat flow, while the total heated area surface (A) is assumed to be constant. The results, presented as graphs and in the form of mathematical expressions, were obtained by analytical methods and using experimental data. The conditions of gaseous fuel combustions were defined by the heat value of gaseous fuel Qd = 9263.894 J.m-3, excess air ratio ?= 1.10, content of oxygen in combustion air ?(O2) = 26%Vol, the preheating temperature of combustion air (cold fluid outlet temperature) tco = 100-500°C, the inlet temperature of combustion products (hot fluid inlet temperature) thi = 600-1100°C.

Lalovi? Milisav; Radovi? Žarko; Jaukovi? Nada

2005-01-01

9

COUNTER FLOW HEAT EXCHANGERS' IRREVERSIBILITY MINIMIZATION  

Directory of Open Access Journals (Sweden)

Full Text Available The irreversibility minimization method of heat exchanger optimization is extended to include a term to account the exergy of the material of construction of the heat exchanger. The method permits physically realistic optimization to be conducted with the resulting optimum designs providing conceptually beneficial guideposts, which do not change with time or location. Such optima are in contrast to the optima obtained by presently advocated methods, which on onehand indicate unrealistic infinite area of the heat exchangers, and on the other hand point to optima that may change dramatically with location and time. Accompanying exergetic efficiency expressions using the same type of material exergy term show physically more realistic values than the usual expressions.

Abbas Alwi Sakhir Abed

2012-01-01

10

Flow and heat-transfer at the intake of a radially symmetrical longitudinal flow heat exchanger  

International Nuclear Information System (INIS)

At the admission section of a radially symmetrical longitudinal flow heat exchanger, cross flow of the tubes occurs. The cross flow is followed by an inclined flow, which turns over to a well-balanced longitudinal flow along the tubes. At two heat exchanger models (tube pitch S? = 1.5, S? = 2.0) the velocity distribution, the pressure-drop and the heat-transfer is determined experimentally. By the variation of the boundary-conditions, the influence of the geometry, the mass flow, the tube pitch and the position of the first spacer is shown in this investigation. Finally the experimental datas are compared with results of calculations. (orig.).

1986-01-01

11

Flow-induced vibration of component cooling water heat exchangers  

International Nuclear Information System (INIS)

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

1990-01-01

12

Constructal tree-shaped parallel flow heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The paper reports the performance of balanced two-stream parallel flow heat exchangers, in which each stream flows as a tree network through its allotted space. The two trees are in parallel flow, and are arranged like two palms pressed against each other. The relationships between effectiveness and number of heat transfer units are developed for several parallel tree flow configurations: (i) constructal dichotomous trees covering uniformly a rectangular area, (ii) trees on a disk-shaped area, and (iii) trees on a square-shaped area. In configurations (ii) and (iii) each stream flows between the center and the periphery of the area. Configurations (i) and (ii) are trees with minimal resistance to fluid flow. Configuration (iii) is designed by minimizing the length of each duct in the network. The performance of the parallel flow configurations is compared with the performance of counterflow configurations. The future use of dendritic heat exchangers in devices with maximal heat transport density is proposed. (author)

Zimparov, V.D. [Department of Mechanical Engineering, Gabrovo Technical University, 4 Hadji Dimitar Str., 5300 Gabrovo (Bulgaria); Da Silva, A.K. [Department of Mechanical Engineering, University of Hawaii, Manoa, Honolulu, HI 96822 (United States); Bejan, A. [Department of Mechanical Engineering and Materials Science, Duke University, Box 90300, Durham, NC 27708-0300 (United States)

2006-11-15

13

Heat exchanger  

UK PubMed Central (United Kingdom)

The present invention relates to a heat exchanger which is specifically adapted for use in connection with blood oxygenators, particularly bubble oxygenators. The core of the heat exchanger is generally cylindrical and closed at both ends. The cylinder is made of thin walled material with good heat exchange properties such as aluminum. The portion of the heat exchanger core which will be exposed to blood is coated with a biocompatible material such as tetrafluoroethylene. The heat exchanger may be connected to a source of heat exchange medium, such as water, through couplings in the top portion of the heat exchanger core. The heat exchange medium is then circulated through the core providing heating or cooling which is capable of heating or cooling blood within a bubble oxygenator. The heat exchanger core is then nested within a suitable receiver. The inner walls of said receiver may be reticulated in order to facilitate exchange of heat between the heat exchanger core and a fluid, such as blood, flowing between the outer wall of the heat exchanger core and the inner wall of the shell.

OSCARSSON ROLF A

14

Liquid-gas direct heat exchangers. Part 1: Fluid Flow  

International Nuclear Information System (INIS)

[en] The annular liquid-gas flow in vertical ducts is studied in order to know the possibilities of these devices as direct heat exchangers. The liquid-gas flow rate in liquid lifting and the friction losses are correlated with the Froude number of the mixture. (author) 17 refs

1987-01-01

15

Entropy resistance analyses of a two-stream parallel flow heat exchanger with viscous heating  

Science.gov (United States)

Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process. With this concept, a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed. It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger, while the minimizations of entropy generation rate, entropy generation numbers, and revised entropy generation number do not always.

Cheng, Xue-Tao; Liang, Xin-Gang

2013-08-01

16

Flow-induced vibration of component cooling water heat exchangers  

International Nuclear Information System (INIS)

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

1990-01-01

17

Flow-induced vibration of component cooling water heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-01-01

18

Optimization of cross flow heat exchangers for thermoelectric waste heat recovery  

International Nuclear Information System (INIS)

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 thermoelectric waste heat recovery with air cooling in a cross flow heat exchanger. Power losses from an air fan and a fluid pump result in an optimal configuration at intermediate cooling air and hot fluid flows. Results show that heat exchangers with Bi2Te3 thermoelectrics can achieve net power densities over 40 W/l.

2004-01-01

19

Numerical optimization for thermal flow design of a parallel flow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

There is a need to make heat exchangers for refrigeration and air conditioning systems compact in size and light in weight, because they are quite often installed into confined spaces. To meet the need, compact and light heat exchangers including the serpentine, laminated, and parallel flow type heat exchangers have been developed and used rather than the traditional tube heat exchangers. Here, thermal and flow characteristics of a parallel flow heat exchanger have been numerically examined to investigate the effects of its geometrical parameters on thermal performance. Flow nonuniformities along passages of the heat exchanger, which are believed to be dominantly influential to the thermal performance, have been observed to eventually optimize the design of the heat exchanger. The optimization has been done by minimizing the flow nonuniformity that was served as an object function when Newton's searching method was applied. The parameters include locations of separators, and the inlet and outlet of the heat exchanger. It is found that the heat transfer of the optimized model increased approximately 7.6% and the pressure drop decreased 4.7%, compared to those of the base model of the heat exchanger.

Lee, K.S.; Chung, K.; Cha, D.J.

1999-07-01

20

Strouhal numbers for heat exchanger tube arrays in cross flow  

Energy Technology Data Exchange (ETDEWEB)

The prediction of tube or acoustic resonance due to cross-flow in heat exchangers is dependent upon knowledge of the flow characteristics for a given tube array geometry. For this, a Strouhal number relating a peak frequency in the turbulence spectrum to the velocity of the flow is required. The data available in the literature for this are rather confusing and the prediction methods appear somewhat contradictory. This paper reports the results from experiments conducted to determine Strouhal numbers for eight tube array models. These results together with the data available in the literature are then compared and appropriate conclusions are drawn.

Weaver, D.S.; Fitzpatrick, J.A.; Elkashlan, M.

1987-05-01

 
 
 
 
21

Strouhal numbers for heat exchanger tube arrays in cross flow  

International Nuclear Information System (INIS)

The prediction of tube or acoustic resonance due to cross flow in heat exchangers is dependent upon knowledge of the flow characteristics for a given tube array geometry. For this, a Strouhal number relating a peak frequency in the turbulence spectrum to the velocity of the flow is required. The data available in the literature for this are rather confusing and the prediction methods appear somewhat contradictory. This paper reports the results from experiments conducted to determine Strouhal numbers for eight tube array models. These results together with the data available in the literature are then compared and appropriate conclusions drawn.

1986-01-01

22

Heat exchanger  

International Nuclear Information System (INIS)

The arrangement described relates particularly to heat exchangers for use in fast reactor power plants, in which heat is extracted from the reactor core by primary liquid metal coolant and is then transferred to secondary liquid metal coolant by means of intermediate heat exchangers. One of the main requirements of such a system, if used in a pool type fast reactor, is that the pressure drop on the primary coolant side must be kept to a minimum consistent with the maintenance of a limited dynamic head in the pool vessel. The intermediate heat exchanger must also be compact enough to be accommodated in the reactor vessel, and the heat exchanger tubes must be available for inspection and the detection and plugging of leaks. If, however, the heat exchanger is located outside the reactor vessel, as in the case of a loop system reactor, a higher pressure drop on the primary coolant side is acceptable, and space restriction is less severe. An object of the arrangement described is to provide a method of heat exchange and a heat exchanger to meet these problems. A further object is to provide a method that ensures that excessive temperature variations are not imposed on welded tube joints by sudden changes in the primary coolant flow path. Full constructional details are given. (U.K.)

1976-01-01

23

A simplified method of calculating heat flow through a two-phase heat exchanger  

International Nuclear Information System (INIS)

A simplified method of calculating the heat flow through a heat exchanger in which one or both heat carrying media are undergoing a phase change is proposed. It is based on enthalpies of the heat carrying media rather than their temperatures. The method enables the determination of the maximum rate of heat flow provided the thermodynamic properties of both heat-carrying media are known. There will be no requirement to separately simulate each part of the system or introduce boundaries within the heat exchanger if one or both heat-carrying media undergo a phase change. The model can be used at the pre-design stage, when the parameters of the heat exchangers may not be known, i.e., to carry out an assessment of a complex energy scheme such as a steam power plant. One such application of this model is in thermal simulation exercises within the TRNSYS modeling environment.

2005-01-01

24

Analysis of the flow structure and heat transfer in a vertical mantle heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

The flow structure inside the inner tank and inside the mantle of a vertical mantle heat exchanger was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the inner tank and in the mantle were measured using a Particle Image Velocimetry (PIV) system. A Computational Fluid Dynamics (CFD) model of the vertical mantle heat exchanger was also developed for a detailed evaluation of the heat flux at the mantle wall and at the tank wall. The flow structure was evaluated for both high and low temperature incoming flows and for both initially mixed and initially stratified inner tank and mantle. The analysis of the heat transfer showed that the flow in the mantle near the inlet is mixed convection flow and that the heat transfer is dependent on the mantle inlet temperature relative to the core tank temperature at the mantle level. (Author)

Knudsen, S.; Furbo, S. [Technical Univ. of Denmark, Dept. of Civil Engineering, Lyngby (Denmark); Morrison, G.L.; Behnia, M. [New South Wales Univ., School of Mechanical and Manufacturing Engineering, Sydney, NSW (Australia)

2005-02-01

25

Analysis of the flow structure and heat transfer in a vertical mantle heat exchanger  

DEFF Research Database (Denmark)

The flow structure inside the inner tank and inside the mantle of a vertical mantle heat exchanger was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the inner tank and in the mantle were measured using a Particle Image Velocimetry (PIV) system. A Computational Fluid Dynamics (CFD) model of the vertical mantle heat exchanger was also developed for a detailed evaluation of the heat flux at the mantle wall and at the tank wall. The flow structure was evaluated for both high and low temperature incoming flows and for both initially mixed and initially stratified inner tank and mantle. The analysis of the heat transfer showed that the flow in the mantle near the inlet is mixed convection flow and that the heat transfer is dependent on the mantle inlet temperature relative to the core tank temperature at the mantle level. (C) 2004 Elsevier Ltd. All rights reserved.

Knudsen, SØren; Morrison, GL

2005-01-01

26

Laminar fluid flow and heat transfer in a fin-tube heat exchanger with vortex generators  

Energy Technology Data Exchange (ETDEWEB)

Development of heat transfer enhancement techniques for fin-tube heat exchangers has great importance in industry. In recent years, heat transfer augmentation by vortex generators has been considered for use in plate fin-tube heat exchangers. The present work describes a numerical investigation about the influence of delta winglet pairs of vortex generators on the flow structure and heat transfer of a plate fin-tube channel. The Navier-Stokes and Energy equations are solved by the finite volume method using a boundary-fitted coordinate system. The influence of vortex generators parameters such as position, angle of attack and aspect ratio were investigated. Local and global influences of vortex generators in heat transfer and flow losses were analyzed by comparison with a model using smooth fin. The results indicate great advantages of this type of geometry for application in plate fin-tube heat exchangers, in terms of large heat transfer enhancement and small pressure loss penalty. (author)

Yanagihara, J.I.; Rodriques, R. Jr. [Polytechnic School of Univ. of Sao Paolo, Sao Paolo (Brazil). Dept. of Mechanical Engineering

1996-12-31

27

Experimental study on the cross flow air cooled plate heat exchanger using fin with electric pump.  

Directory of Open Access Journals (Sweden)

Full Text Available Experimental study on the cross flow air cooled plate heat exchanger using fin with electric pump was performed. Two prototype plate heat exchanger were manufactured in a stack of single wave plates and double plates in parallel. Cooling air flows through the plate heat exchanger in across wise direction against internal cooling water. In this study prototype heat exchanger were tested in a laboratoryscale experiments. From test double wave plates heatexchanger shows approximately 52.50 % enhanced heat transfer performance compare to single wave plates heat exchanger . However double wave heat exchanger costs 30%additional pressure drop .

Pankaj kumar mishra

2013-01-01

28

Investigation of heat exchange at the laminar flow of liquids in the pipe  

Directory of Open Access Journals (Sweden)

Full Text Available The results of the experimental investigation of heat exchange of various liquids at the laminar flow in pipes are presented in the paper. The design formula is received. Possibilities of heat exchange intensification are shown.

Kovalev Oleg Petrovich; Ilyin Albert Konstantinovich; Ilyin Roman Albertovich

2011-01-01

29

Flow length effect in heat exchangers with turbulent flow at low Prandtl number  

International Nuclear Information System (INIS)

[en] This work brings out the effect of energy length on the mean overall heat transfer coefficient of a heat exchanger for turbulent flow with low Prandtl number. For this purpose simple heat transfer correlations are proposed in the thermal energy length region and with these correlations the correction factors are calculated for selected special cases. The effect of flow parameters and total heat exchanger length has also been investigated. Finally comments are made regarding thermal boundary conditions and in its light the commonly used design method is assessed

1995-01-01

30

Heat exchanger panel for solar energy with improved flow distribution  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger panel having a desired system of tubular passageways having a heat exchange medium wherein said panel includes opposed headers including island-like bonded portions and said passageways have entry and exit portions extending from said headers to provide ingress and egress openings for said heat exchange medium. The headers include as a part of the island-like bonded portions alphanumeric bonded portions to assist in properly installing the panel within a complete solar collector assembly. 10 drawings.

Kleine, C.A.; Middelton, V.L.

1984-04-24

31

Heat exchanger panel having reference indicia and improved flow distribution  

Energy Technology Data Exchange (ETDEWEB)

In a heat exchanger panel for use in a solar energy collector system, said panel comprising a plurality of spaced parallel individual tubular passageways connecting opposed headers defined by numerous island-like bonded portions connected by a plurality of tubular channels passing therebetween, the boundaries of said headers defining a generally triangular shape with at least one of said boundaries being inclined with respect to an edge of said panel, said headers including entry and exit portions to said panel, siad entry and exit portions being laterally displaced from the center of said panel to permit a heat exchange medium to flow into said panel and across said headers so that said medium flows through each of the plurality of spaced parallel indiviual tubular passageways connecting said headers; and said parallel individual tubular passageways being interconnected by further tubular interconnecting portions spaced from said headers the improvement wherein said tubular interconnecting portions are arranged across said panel at an inclination generally corresponding to the inclination of said at least one boundary.

Kleine, C.; Middleton, V.

1980-07-01

32

Heat transfer in tube bundles of heat exchangers with flow baffles induced forced mixing  

International Nuclear Information System (INIS)

Thermal analysis of shell-and-tube heat exchangers is being investigated through geometric modeling of the unit configuration in addition to considering the heat transfer processes taking place within the tube bundle. The governing equations that characterize the heat transfer from the shell side fluid to the tube side fluid across the heat transfer tubewalls are indicated. The equations account for the heat transfer due to molecular conduction, turbulent thermal diffusion, and forced fluid mixing among various shell side fluid channels. The analysis, though general in principle, is being applied to the Clinch River Breeder Reactor Plant-Intermediate Heat Exchanger, which utilizes flow baffles appropriately designed for induced forced fluid mixing in the tube bundle. The results of the analysis are presented in terms of the fluid and tube wall temperature distributions of a non-baffled and baffled tube bundle geometry. The former case yields axial flow in the main bundle region while the latter is associated with axial/cross flow in the bundle. The radial components of the axial/cross flow yield the necessary fluid mixing that results in reducing the thermal unbalance among the heat transfer to the allowable limits. The effect of flow maldistribution, present on the tube or shell sides of the heat exchangers, in altering the temperature field of tube bundles is also noted

1976-12-05

33

Parallel tube heat exchanger  

International Nuclear Information System (INIS)

An improved heat exchanger for use in liquid metal cooled nuclear reactors, is described, which consists of a bundle of spaced, parallel tube assemblies for immersion in a primary heat exchange fluid. Each assembly defines flow and counterflow paths for a secondary heat exchange fluid in successive passes. Insulation reduces heat transfer between the flows of successive passes. (U.K.)

1982-01-01

34

Woven heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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, Roger R. (Idaho Falls, ID)

1987-01-01

35

Advantages of counterflow heat exchangers as compared to doubled cross-flow heat exchangers; Vorteile von Gegenstrom- im Vergleich zu verdoppelten Kreuzstromwaermetauschern  

Energy Technology Data Exchange (ETDEWEB)

The contribution outlines the advantages of counterflow heat exchangers over doubled cross-flow heat exchangers. The author already published an earlier contribution on this subject in the same journal. (orig.)

Jakobczak, A. [Wroclaw Univ. (Poland). Abt. Bau - und Sanitarwesen

2007-04-15

36

Random excitation of heat exchanger tubes by cross-flows  

International Nuclear Information System (INIS)

[en] For designing shell-and-tube heat exchangers against flow-induced vibration, a reasonable assessment of tube response to the random excitation by the crossflow is required. Resulting tube vibration amplitudes will not, usually, lead to failures on a short term basis. However, they can produce a progressive damage at the supports through fretting wear or fatigue. A considerable amount of experimental and theoretical work was already reported in the open literature, concerning flow-induced vibration in tube arrays. Nevertheless it is generally agreed that design oriented information on random excitation still remains insufficiently documented. This is largely because general interest was, at first, focused on fluidelastic instability and periodic wake shedding mechanisms, which can lead to catastrophic tube failures. This paper reviews information on this topics, gained at CEA Saclay during the past decade from several experimental programs. This includes tests performed in single phase flow (both air and water) and in two-phase flow (air-water and steam-water)

1988-12-02

37

Characteristics of flow distribution in compact parallel flow heat exchangers, part II: Modified inlet header  

International Nuclear Information System (INIS)

This study presents the experimental results of liquid flow distribution in compact parallel flow heat exchanger through a rectangular and 5 modified inlet headers (i.e., 1 trapezoidal, one multi-step, 2 baffle plates and 1 baffle tubes header). The basic header has a rectangular shape with 9 x 9 mm cross section and 90 mm long header length having a 4 mm inlet tube for flow into the header and distributed to nine 3 mm parallel tubes with 400 mm length. A jet stream induced at the header inlet associated with vortexes affecting the flow distribution to the front tubes. The flow distribution in the header highly depends on the header shape and the total flow rate. Normally the first several tubes have the lowest flow ratios for the conventional headers and the flow distribution is significantly improved by lifting the jet stream using the modified header with baffle tube, followed by the baffle plate and multi-step header. The baffle tube yields the best flow distribution for it removed the vortex flow, and it is applicable for all the flow rates. - Highlights: ? This study investigates flow distribution in parallel flow heat exchanger through 5 modified inlet headers. ? Jet flow induces at the header inlet with vortexes affecting the flow distribution to front tubes. ? The modified header with baffle tube removes the vortex flow and yields the best flow distribution.

2011-01-01

38

Study on flow-induced vibration and anti-vibration measures of nuclear heat exchanger  

International Nuclear Information System (INIS)

[en] Nuclear heat exchanger is the important equipment of nuclear power plant. Shell-and-tube is the ordinary style used in heat exchanger structure. Unreasonable design will make tubes vibrate and maybe lead tubes broken. Then the running safety of nuclear power plant is influenced. The flow-induced vibration mechanism is studied. Based on structure characteristic of shell-and-tube heat exchange, the failure modes of heat exchange caused by flow-induced vibration are analyzed roundly. Specific approaches are presented to prevent nuclear heat exchange from vibration. (authors)

2010-01-01

39

Characteristics of flow distribution in compact parallel flow heat exchangers, part I: Typical inlet header  

International Nuclear Information System (INIS)

This study experimentally and numerically investigates the single-phase flow into parallel flow heat exchangers with inlet and outlet rectangular headers having square cross section and 9 circular tubes. The effects of inlet flow condition, tube diameter, header size, area ratio, flow directions (Z and U-type), as well as the gravity are investigated. The experimental results indicate that flow distribution for U-type flow is more uniform than Z-type flow. Depending on the inlet volumetric flow rate, the flow ratio at the first several tubes can be lower than 50% of the last tube for Z-type arrangement, and this phenomenon becomes more and more pronounced with the rising velocity at the intake conduit. The mal-distribution can be eased via reducing the branching tube size or increasing the entrance settling distance at the intake conduit. It is found that the influence of gravity on mal-distribution is negligible and the mal-distribution is associated with the jet flow pattern. - Highlights: ? The flow distribution into parallel flow heat exchangers with rectangular headers is examined. ? The first several tubes may show only 50% flow rate of the last tube. ? The mal-distribution becomes more severe with the rising velocity at the intake conduit. ? The mal-distribution is mainly associated with the jet flow pattern. ? Flow distribution is improved via smaller tubes or increasing the inlet distance at the intake conduit.

2011-01-01

40

Bifurcation of vortex turbulent flow and heat exchange intensification in a dimple  

International Nuclear Information System (INIS)

The aim of the paper is to study the vortex intensification of heat exchange based on the turbulent modes of flowing out the dimples of asymmetrical form. The problem is solved by the computer simulation method. Effect of dimple parameter variation on the heat exchange value is analysed. It is noted that in the case of the vortex flow bifurcation essential decrease of heat exchange takes place

2000-01-01

 
 
 
 
41

Modeling heat efficiency, flow and scale-up in the corotating disc scraped surface heat exchanger  

DEFF Research Database (Denmark)

A comparison of two different scale corotating disc scraped surface heat exchangers (CDHE) was performed experimentally. The findings were compared to predictions from a finite element model. We find that the model predicts well the flow pattern of the two CDHE's investigated. The heat transfer performance predicted by the model agrees well with experimental observations for the laboratory scale CDHE whereas the overall heat transfer in the scaled-up version was not in equally good agreement. The lack of the model to predict the heat transfer performance in scale-up leads us to identify the key dimensionless parameters relevant for scale-up.

Friis, Alan; Szabo, Peter

2002-01-01

42

Heat exchangers  

International Nuclear Information System (INIS)

A heat exchanging apparatus comprises an elongate chamber which is part filled with a heat transfer medium, and a pair of U-shaped pipes. The pipes are spaced from one another, but are generally mutually adjacent so that heat from a liquid flowing in one pipe can be transferred through a medium to the liquid in the other pipe. If one or other of the pipes ruptures the escaping liquid can be vented and will not intermix with the liquid in the other pipe. A level detector detects a rise in the level of the material in the chamber when a pipe ruptures and closes valves to prevent further loss of liquid. The apparatus is particularly suitable for use in the food industry or where one of the liquids is toxic or radioactive. (author)

1981-01-01

43

Flow boiling heat transfer of ammonia/water mixture in a plate heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

The objective of this work is to contribute to the development of plate heat exchangers as desorbers for ammonia/water absorption refrigeration machines driven by waste heat or solar energy. In this study, saturated flow boiling heat transfer and the associated frictional pressure drop of ammonia/water mixture flowing in a vertical plate heat exchanger is experimentally investigated. Experimental data is presented to show the effects of heat flux between 20 and 50 kW m{sup -2}, mass flux between 70 and 140 kg m{sup -2} s{sup -1}, mean vapour quality from 0.0 to 0.22 and pressure between 7 and 15 bar, for ammonia concentration between 0.42 and 0.62. The results show that for the selected operating conditions, the boiling heat transfer coefficient is highly dependent on the mass flux, whereas the influence of heat flux and pressure are negligible mainly at higher vapour qualities. The pressure drop increases with increasing mass flux and quality. However, the pressure drop is independent of the imposed heat flux. (author)

Taboas, Francisco [Universidad de Cordoba, Campus de Rabanales, Edificio Leonardo da Vinci, 14014 Cordoba (Spain); Valles, Manel; Bourouis, Mahmoud; Coronas, Alberto [CREVER - Universitat Rovira i Virgili, Av. Paisos Catalans No. 26, 43007 Tarragona (Spain)

2010-06-15

44

Heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger of a type used to transfer heat from exhaust air (for instance air-conditioning) to fresh air is constructed in such way, that an evaporator of the pump circuit is situated after the exit of the exhaust air cooled in the heat exchanger. The condenser of the heat-pumps circuit is in contact with water in a water tank for domestic purposes.

Svendsen, B.R.

1981-02-28

45

New counter flow heat exchanger designed for ventilation systems in cold climates  

DEFF Research Database (Denmark)

In cold climates, mechanical ventilation systems with highly efficient heat recovery will experience problems with condensing water from the extracted humid indoor air. If the condensed water changes to ice in the heat exchanger, the airflow rate will quickly fall due to the increasing pressure drop. Preheating the inlet air (outdoor air) to a temperature above 0 degrees C before it enters the exchanger is one solution often used to solve the problem, however, this method reduces the energy saving potential significantly. To minimize the energy cost, a more efficient way to solve the freezing problem is therefore desirable. In this paper, the construction and test measurements of a new counter flow heat exchanger designed for cold climates are presented. The developed heat exchanger is capable of continuously defrosting itself without using supplementary heating. Other advantages of the developed beat exchanger are low pressure loss, cheap materials and a simple construction. The disadvantage is that the exchanger is big compared with other heat exchangers. In this paper, the new heat exchanger's efficiency is calculated theoretically and measured experimentally. The experiment shows that the heat exchanger is capable of continuously defrosting itself at outside air temperatures well below the freezing point while still maintaining a very high efficiency. Further analysis and development of a detailed simulation model of a counter flow air-to-air heat exchanger will be described in future articles.

Kragh, Jesper; Rose, JØrgen

2007-01-01

46

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

International Nuclear Information System (INIS)

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

2009-06-21

47

Degradation of the performance of microchannel heat exchangers due to flow maldistribution  

DEFF Research Database (Denmark)

The effect of flow maldistribution on the performance of microchannel parallel plate heat exchangers is investigated using an established single blow numerical model and cyclic steady-state regenerator experiments. It is found that as the variation of the individual channel thickness in a particular stack (heat exchanger) increases the actual performance of the heat exchanger decreases significantly, deviating from the expected nominal performance. We show that this is due to both the varying fluid flow velocities in each individual channel and the thermal cross talk between the channels transverse to the direction of the flow.

Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

2012-01-01

48

Three dimensional numerical simulation of flow in the shell-tube heat exchanger  

International Nuclear Information System (INIS)

A three dimensional numerical model based on PHOENICS-3.3 code using porous-media method was established to simulate fluid flow in the shell-tube heat exchanger. Tubes in the heat exchange were described by means of distributed resistance along with volumetric porosity and surface permeability. The model was validated by comparison of computed pressure drops with the experiments by Halle. And a modified code was used to calculate the fluid flow in the main heat exchanger of the 200 MW nuclear heating reactor (NHR-200)

2002-01-01

49

Pressure loss and heat transfer studies performed on axial-flow finned-tube bundle heat exchangers  

International Nuclear Information System (INIS)

The experimental studies intend to determine the dependence on the parameters of influence state of flow, tube length, and bundle pitch of the heat transfer and pressure loss characteristic of two tube types in the bundle. By means of suitable parameters for heat flow and pressure loss a comparison will be made of the heat transfer and pressure loss power of the axial-flow furried-tube bundle systems investigated here and conventional heat exchangers. (orig.)

1981-01-01

50

Heat exchanger  

Science.gov (United States)

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

Daman, Ernest L. (Westfield, NJ); McCallister, Robert A. (Mountain Lakes, NJ)

1979-01-01

51

Numerical analysis of non-isothermal Newtonian flows in plate heat exchangers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Numerical analysis of non-isothermal Newtonian flows in plate heat exchanger passages is carried out in the laminar flow region. The results of this analysis are compared with information available in the literature. Some interesting trends are observed for both heat transfer and pressure drop with ...

Fernandes, Carla S.; Dias, Ricardo P.; Nóbrega, João M.; Maia, João M.; Wadekar, Vishwas V.

52

Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration.

Teng Tun-Ping; Hung Yi-Hsuan; Teng Tun-Chien; Chen Jyun-Hong

2011-01-01

53

Experimental investigation of the heat exchange to a compartmentalized plug flow  

Energy Technology Data Exchange (ETDEWEB)

A two-phase (air-water), tubular counterflow heat exchanger was developed for industrial unitary process applications to realize an active heat transfer control. A controlled train of air plugs was injected in a stratified smooth water flow to yield a compartmentalized, continuous two-phase flow whose stability was carefully monitored. Related Nusselt numbers were evaluated for single- and two-phase flows, at the same flow regimes. This comparison shows how the traveling, controlled air plug 'turbulators' allowed for a large heat transfer rate increase, for all observed heating rates and phase velocity ratios. The analysis includes a comparison with the available literature correlations, and the efficiency of the adopted heat transfer control is finally inferred while a range of flow regimes is identified which optimizes the heat exchange. (authors)

Nino, E. [DIFA, Universita degli studi della Basilicata (Italy); Ruocco, G. [DITEC, Universita degli studi della Basilicata (Italy)

1999-12-01

54

Development of gas-solid direct contact heat exchanger by use of axial flow cyclone  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger between particulate or granular materials and gas is developed. It makes use of a swirling gas flow similar to the usual cyclone separators but the difference from them is that the swirl making gas is issued into the cyclone chamber with downward axial velocity component. After it turns the flow direction near the bottom of the chamber, the low temperature gas receives heat from high temperature particles supplied from above at the chamber's center. Through this configuration, a direct contact and quasi counter-flow heat exchange pattern is realized so that the effective recovery of heat carried by particles is achieved. A model heat exchanger was manufactured via several numerical experiments and its performances of heat exchange as well as particle recovery were examined. Attaching a small particle diffuser below the particle-feeding nozzle brought about a drastic improvement of the heat exchange performance without deteriorating the particle recovery efficiency. The outlet gas temperature much higher than the particle outlet temperature was finally obtained, which is never realized in the parallel flow heat exchanger. (author)

Shimizu, Akihiko; Yokomine, Takehiko [Kyushu University (Japan). Interdisciplinary Graduate School of Engineering Sciences; Nagafuchi, Tatsuro [Miura Co. Ltd., Matsuyamashi (Japan)

2004-10-01

55

Heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The heat exchange tube described is a light alloy multi-bore extrusion having the walls of the bores dimpled, with the dimples on opposite walls aligned so that each bore consists of a series of chambers along its length. The chambers are connected together by the restricted portion lying between the pair of dimples, and this gives the effect of high turbulation and most efficient heat exchange.

Smith, E.

1985-11-27

56

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

Energy Technology Data Exchange (ETDEWEB)

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

Xiao, Lan; Wu, Shuang-Ying; Zhang, Qiao-Ling; Li, You-Rong [Chongqing University, Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing (China); Chongqing University, College of Power Engineering, Chongqing (China)

2012-07-15

57

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

Science.gov (United States)

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

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

2012-07-01

58

Heat exchangers  

International Nuclear Information System (INIS)

[en] This invention relates to a heat exchanger, more particularly intended, although not exclusively, for transferring the thermal power acquired by an initial fluid medium cooling the core assemblies of a nuclear reactor to another fluid medium isolated from the first, therefore having low activity and suitable them to generate steam in a separate generator. The invention applies particularly in the case where the first fluid medium or primary fluid is a liquid metal, generally sodium, used as coolant in a fast nuclear reactor, the second fluid medium or secondary fluid also being liquid sodium, flowing through tubes between two tube plates respectively to enter an intake manifold and an outlet manifold of the secondary sodium. These tubes are externally steeped in the primary sodium. The exchanger concerned comprises two tube plates fitted inside an external envelope crossed by a primary fluid. These two tube plates are joined by a bundle of tubes extending vertically over the major part of their length and through which a secondary fluid flows, these tubes being covered externally by the primary fluid exchanging heat with the secondary fluid through these tubes[fr] La presente invention est relative a un echangeur de chaleur, destine plus particulierement, quoique non exclusivement, a transferer la puissance thermique acquise par un premier milieu fluide assurant le refroidissement des assemblages du coeur d'un reacteur nucleaire, a un deuxieme milieu fluide isole du premier, donc de faible activite et apte a produire ensuite de la vapeur dans un generateur separe. L'invention s'applique plus specialement dans le cas ou le premier milieu fluide ou fluide primaire est un metal liquide generalement du sodium, utilise comme refrigerant dans un reacteur nucleaire a neutrons rapides, le deuxieme milieu fluide ou fluide secondaire etant egalement du sodium liquide, parcourant des tubes s'etendant entre deux plaques a tubes pour deboucher respectivement dans un collecteur d'entree et un collecteur de sortie du sodium secondaire, ces tubes etant baignes exterieurement par le sodium primaire. L'echangeur considere, comporte, montees a l'interieur d'une enveloppe externe traversee par un fluide primaire, deux plaques a tubes reunies par un faisceau de tubes s'etendant verticalement sur la majeure partie de leur longueur et parcourus par un fluide secondaire, ces tubes etant baignes exterieurement par le fluide primaire echangeant des calories avec le fluide secondaire a travers ces tubes

1976-01-01

59

Phase change heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger for a phase change material having a solid density greater than its liquid density, the heat exchanger is described comprising a container holding the phase change material, a tube surrounding the container to define an annular space there between, means for connecting the tube in fluid communication with a first source of heat exchange fluid to allow heat exchange fluid to flow through the annular space to exchange heat with the phase change material, and at least two divider walls extending between the tube and the container across the annular space to divide the annular space into at least a lower flow passageway for receiving heat exchange fluid from the first source at a temperature sufficient to initiate melting of the phase change material and an upper flow passageway for receiving heat exchange fluid from the lower flow passageway to flow in counter flow relationship with the heat exchange fluid flowing in the lower passageway so that the phase change material is melted from the bottom as it moves to a lower portion of the container to cause newly-formed liquid phase change material to be displaced to an upper portion of the container.

Longardner, R.L.; Longardner, W.J.

1993-06-22

60

Study on heat transfer of heat exchangers in the Stirling engine - Heat transfer in a heated tube under the periodically reversing flow condition  

Science.gov (United States)

Heat transfer characteristics in heated tubes under periodically reversing flow conditions have been experimentally investigated, using a test apparatus that simulates heat exchangers for an actual Stirling engine. It is shown that the heat transfer characteristics under these conditions are greatly affected by the piston phase difference that generates the reversing flow of working fluid, and this phenomenon is peculiar to heat transfer under periodically reversing flow. The experimental correlation for the heat transfer coefficient under these conditions is obtained through the use of the working gas velocity evaluated from the Schmidt cycle model, which is one of the ideal Stirling cycles concerning the influence of the piston phase difference.

Kanzaka, Mitsuo; Iwabuchi, Makio

1992-11-01

 
 
 
 
61

Pressure Drop and Heat Transfer of Water Flowing Shell-Side of Multitube Heat Exchangers  

Science.gov (United States)

Experimental studies on heat transfer augmentation in water-flowing shell sides of counter flow multitube exchangers are presented. Various kinds of augmented tube bundles have been examined to obtain the characteristics of pressure drop and heat transfer. Data for a smooth tube bundle were a little different from those for the tube side. The pressure drop in the shell side depended on Re-0.4 and deviated from the tube side pressure drop to within +30%, while the shell side heat transfer coefficient depended on Re0.8 but about 35%. larger than that of the tube side. Furthermore the augmented tube bundles have been evaluated and compared using 21 evaluation criteria. Enhanced tube bundles, low-finned tube bundles and those with twisted tapes inserted had especially good performances. The ratios of increase in heat transfer were larger than those in pressure drop. In case of low-finned tube bundles, there seem to exist an optimum fin-pitch and an optimum relation between the fin-pitch and the pitch of twisted tapes inserted.

Ohashi, Yukio; Hashizume, Kenichi

62

Heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

Drury, C.R.

1988-02-02

63

Heat exchanger  

International Nuclear Information System (INIS)

This patent describes a method to increase the surface area of a plate or pipe used in a gas-liquid heat exchanger. 6% of the gas side is covered with strands of aluminium or any other good heat conducting material. The strands are 2mm long and have a diameter of 0.1mm. A tenfold increase in surface area is obtained by this method. (Th.P.)

1980-01-01

64

Heat transfer coefficient in a shallow fluidized bed heat exchanger with a continuous flow of solid particles  

Directory of Open Access Journals (Sweden)

Full Text Available This work shows the experimental study of a continuous gas-solid fluidized bed with an immersed tube where cold water is heated by fluidized solid particles presenting inlet temperature from 450 to 700°C. Experiments were carried out in order to verify the influence of solid particle flow rate and distance between baffles immersed in a shallow fluidized bed. The solid material was 254µm diameter silica sand particles, fluidized by air in a 0.90m long and 0.15m wide heat exchanger. The measurements were taken at steady state conditions for solid mass flow rate from 10 to 100 kg/h, in a heat exchanger with the presence of 5 or 8 baffles. Bed temperature measurements along the length of the heat exchanger were experimentally obtained and heat balances for differential control volumes of the heat exchanger were made in order to obtain the axial profile of the bed-to-tube heat transfer coefficient. The results showed that heat transfer coefficient increases with the solid particle mass flow rate and with the presence of baffles, suggesting that these are important factors to be considered in the design of such heat exchanger.

Araí A. Bernárdez Pécora; Maria Regina Parise

2006-01-01

65

Heat transfer coefficient in a shallow fluidized bed heat exchanger with a continuous flow of solid particles  

Directory of Open Access Journals (Sweden)

Full Text Available This work shows the experimental study of a continuous gas-solid fluidized bed with an immersed tube where cold water is heated by fluidized solid particles presenting inlet temperature from 450 to 700degreesC. Experiments were carried out in order to verify the influence of solid particle flow rate and distance between baffles immersed in a shallow fluidized bed. The solid material was 254µm diameter silica sand particles, fluidized by air in a 0.90m long and 0.15m wide heat exchanger. The measurements were taken at steady state conditions for solid mass flow rate from 10 to 100 kg/h, in a heat exchanger with the presence of 5 or 8 baffles. Bed temperature measurements along the length of the heat exchanger were experimentally obtained and heat balances for differential control volumes of the heat exchanger were made in order to obtain the axial profile of the bed-to-tube heat transfer coefficient. The results showed that heat transfer coefficient increases with the solid particle mass flow rate and with the presence of baffles, suggesting that these are important factors to be considered in the design of such heat exchanger.

Pécora Araí A. Bernárdez; Parise Maria Regina

2006-01-01

66

Balance of mechanical energy and intensification effects of heat exchange in laminar liquid flow  

International Nuclear Information System (INIS)

[en] The balance of mechanical energy for laminar flows of drop liquids with term-wise separation of all the constituents is presented. Numerical studies on evaluation of effects and causes of convective heat exchange intensification for the drop liquids internal flows are carried out on the basis of analysis of the mechanical energy balance[ru] ???????? ?????? ???????????? ??????? ??? ?????????? ????????? ????????? ? ????????? ?????????? ???? ????????????. ?? ?????? ??????? ??????? ???????????? ??????? ????????? ????????? ???????????? ?? ?????? ???????? ? ?????? ?????????????? ????????????? ??????????? ??? ?????????? ??????? ????????? ?????????

1998-01-01

67

Heat exchangers  

International Nuclear Information System (INIS)

The tubes of a heat exchanger tube bank have a portion thereof formed in the shape of a helix, of effective radius equal to the tube radius and the space between two adjacent tubes, to tangentially contact the straight sections of the tubes immediately adjacent thereto and thereby provide support, maintain the spacing and account for differential thermal expansion thereof

1975-03-03

68

Plate heat exchanger; Plattvaermevaexlare  

Energy Technology Data Exchange (ETDEWEB)

The invention suggests a plate package where the end plates have eight openings for through-flow of the heat exchange fluid. By choosing which openings should be utilized, it is possible to connect two or more plates to a plate heat exchanger

Kaellrot, M.

1995-10-09

69

Two-phase flow and pressure drop in flow passages of compact heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 {times} 1.59 mm (aspects ratio equal to 6), for applications to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1), and in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m{sup 2}s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation. 13 refs.

Wambsganss, M.W.; Jendrzejczyk, J.A.; France, D.M.

1992-01-01

70

Two-phase flow and pressure drop in flow passages of compact heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 {times} 1.59 mm (aspects ratio equal to 6), for applications to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1), and in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m{sup 2}s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation. 13 refs.

Wambsganss, M.W.; Jendrzejczyk, J.A.; France, D.M.

1992-02-01

71

Heat transfer coefficient in a shallow fluidized bed heat exchanger with a continuous flow of solid particles  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english This work shows the experimental study of a continuous gas-solid fluidized bed with an immersed tube where cold water is heated by fluidized solid particles presenting inlet temperature from 450 to 700°C. Experiments were carried out in order to verify the influence of solid particle flow rate and distance between baffles immersed in a shallow fluidized bed. The solid material was 254µm diameter silica sand particles, fluidized by air in a 0.90m long and 0.15m wide h (more) eat exchanger. The measurements were taken at steady state conditions for solid mass flow rate from 10 to 100 kg/h, in a heat exchanger with the presence of 5 or 8 baffles. Bed temperature measurements along the length of the heat exchanger were experimentally obtained and heat balances for differential control volumes of the heat exchanger were made in order to obtain the axial profile of the bed-to-tube heat transfer coefficient. The results showed that heat transfer coefficient increases with the solid particle mass flow rate and with the presence of baffles, suggesting that these are important factors to be considered in the design of such heat exchanger.

Pécora, Araí A. Bernárdez; Parise, Maria Regina

2006-09-01

72

Microtube strip heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchanger. DSI completed a heat exchanger stress analysis of the ten-module heat exchanger bank; and, performed a shell-side flow inhomogeneity analysis of the three-module heat exchanger bank. The company produced 50 tubestrips using an in-house CNC milling machine and began pressing them onto tube arrays. DSI revised some of the tooling required to encapsulate a tube array and press tubestrips into the array to improve some of the prototype tooling. 2 refs., 4 figs.

Doty, F.D.

1991-07-08

73

Heat exchangers  

International Nuclear Information System (INIS)

Description is given of a heat exchanger with exchange surfaces of preformed metal-sheets constituting at least one exchange bundle. A bundle comprises juxtaposed independent compartments, each of which comprising two superimposed preformed sheets and its respective manifolds for the inlet and outlet of a coolant. Substantially in parallel relationship to one surface of the respective compartment, said manifolds are mounted at the ends and on the opposed surfaces of the compartment, thus giving it, in cross-section, the shape of a Z with truncated arms. Since the sheets forming each compartments are of rectangular shape, the various juxtaposed independent compartments constitute an exchange-bundle of generally parallelepipedic shape, the manifolds being arranged in stepped fashion and defining those two sides of the parallelepiped inclined with respect to the axis of the latter. The heat-exchanger according to the invention can be used in particular in nuclear power stations, either mobile or not, e.g. of the PWR-type, and also in small-size installations

1974-01-01

74

Heat exchanger system  

Energy Technology Data Exchange (ETDEWEB)

The heat exchanger system is used for gas-cooled high temperature reactors. The high-temperature primary gas passes over a nest of blind tubes and thereafter flows over the tubes of a plurality of counter-current heat-exchangers disposed about a jacket encasing the blind tubes. The cool working gas flows into the system via a header and then passes through the tubes of the counter-current heat-exchangers before passing into the blind tubes. The working gas is exhausted via insert tubes within the blind tubes. The maximum temperatures on the heat exchanger surfaces occur at the closed ends of the blind tubes. However, these parts are substantially stress free in normal operation. The heat exchanger system may be constructed to permit ready disassembly of the insert tubes for inspection and replacement purposes.

Weber, M.

1980-09-02

75

Heat exchanger  

International Nuclear Information System (INIS)

A heat exchanger such as forms, for example, part of a power steam boiler is made up of a number of tubes that may be arranged in many different ways, and it is necessary that the tubes be properly supported. The means by which the tubes are secured must be as simple as possible so as to facilitate construction and must be able to continue to function effectively under the varying operating conditions to which the heat exchanger is subject. The arrangement described is designed to meet these requirements, in an improved way. The tubes are secured to a member extending past several tubes and abutment means are provided. At least some of the abutment means comprise two abutment pieces and a wedge secured to the supporting member, that acts on these pieces to maintain the engagement. (U.K.)

1975-01-01

76

Heat Exchanger  

International Nuclear Information System (INIS)

A liquid metal heated tube and shell heat exchanger where straight tubes extend between upper and lower tube sheets. In order to prevent thermal stress problems, one tube sheet is fixed to the shell, and the other tube sheet is sealed to the shell by means of a flexible bellows. In the event of a catastrophic bellows failure, a housing that utilizes a packing gland sliding seal is used to enclose and back-up the bellows. Also, a key and slot arrangement is provided for preventing relative rotation between the shell and tube sheet which could damage the bellows and cause failure thereof. This exchanger is seen to be of use in sodium cooled reactors between the liquid sodium circuit on the steam generator

1976-07-15

77

Difference in characteristics between parallel and counter flow type heat exchangers with frosting  

Energy Technology Data Exchange (ETDEWEB)

On heat exchangers which involve frosting, frost growth greatly varies depending on time and the location of the heat exchanger. This means that the thermal resistance of a heat exchanger varies with time and its location. When investigating the efficiency of a heat exchanger, it is important to understand frost layer variations with locations and frost growth variations with time. Experiments using a frost layer structure model were conducted, and the results were analyzed. The findings are as follows: An experimental formula which can apply in a wide range of initial conditions necessary for theoretical analysis of frost growth was obtained. This formula has made it possible to calculate frost growth under various conditions. In heat exchangers, the thermal resistance in parallel flow is higher in the upstream area where the amount of stuck frost is larger, whereas the thermal resistance in counterflow is lower in the upstream area than in the downstream area. In general, the average thermal resistance per unit amount of stuck frost is higher in counterflow than in parallel flow, and the difference in temperature efficiency between parallel flow and counterflow is lower when the amount of stuck frost is larger. (14 figs, 1 tab, 4 refs)

Aoki, Kazuo; Hattori, Masaru; Mizuno, Satoru

1988-07-25

78

Flow distribution analysis in nuclear heat exchangers with application to CRBRP-IHX  

International Nuclear Information System (INIS)

The shell side flow distribution of a shell-and-tube heat exchanger, in which the shell side fluid moves downwards in an axial/cross flow combination dictated by the design of the flow baffles, is examined. Depending on the degree of overlapping and perforation of the baffles, the magnitude of the cross flow component can be controlled in a manner compatible with the unit design. Axial/cross flow field would yield a relatively small pressure drop on the shell side, and in the meantime it creates sufficient fluid mixing to minimize any thermal unbalance among the heat transfer tubes. Such requirements are essential in the design of nuclear heat exchangers similar to the CRBRP-IHX. The present flow distribution analysis utilizes two models: The lumped model and the detailed model. The lumped model employs an overall flow distribution and pressure drop approach to determine the magnitudes of the axial and cross flow components as a function of the baffle overlapping and baffle perforation. The detailed model utilizes more of a fundamental approach in solving the governing equations for the conservation of mass and momentum of a turbulent flowing fluid in a nodal mesh. The mesh incorporates distributed resistances resulting from the presence of the heat transfer tubes and the flow baffles in the tube bundle. The model employs a modified version of the computer code VARR II tailored specifically to the analysis of the shell side flow of heat exchangers. The results of both models are indicated and compared with emphasis on demonstrating the influence of the baffle overlapping and baffle perforation on the flow field and the pressure distribution

1976-06-21

79

Effectiveness-ntu computation with a mathematical model for cross-flow heat exchangers  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Due to the wide range of design possibilities, simple manufactured, low maintenance and low cost, cross-flow heat exchangers are extensively used in the petroleum, petrochemical, air conditioning, food storage, and others industries. In this paper a mathematical model for cross-flow heat exchangers with complex flow arrangements for determining epsilon -NTU relations is presented. The model is based on the tube element approach, according to which the heat exchanger outle (more) t temperatures are obtained by discretizing the coil along the tube fluid path. In each cross section of the element, tube-side fluid temperature is assumed to be constant because the heat capacity rate ratio C*=Cmin/Cmax tends toward zero in the element. Thus temperature is controlled by effectiveness of a local element corresponding to an evaporator or a condenser-type element. The model is validated through comparison with theoretical algebraic relations for single-pass cross-flow arrangements with one or more rows. Very small relative errors are obtained showing the accuracy of the present model. epsilon -NTU curves for several complex circuit arrangements are presented. The model developed represents a useful research tool for theoretical and experimental studies on heat exchangers performance.

Navarro, H. A.; Cabezas-Gómez, L. C.

2007-12-01

80

Effectiveness-ntu computation with a mathematical model for cross-flow heat exchangers  

Directory of Open Access Journals (Sweden)

Full Text Available Due to the wide range of design possibilities, simple manufactured, low maintenance and low cost, cross-flow heat exchangers are extensively used in the petroleum, petrochemical, air conditioning, food storage, and others industries. In this paper a mathematical model for cross-flow heat exchangers with complex flow arrangements for determining epsilon -NTU relations is presented. The model is based on the tube element approach, according to which the heat exchanger outlet temperatures are obtained by discretizing the coil along the tube fluid path. In each cross section of the element, tube-side fluid temperature is assumed to be constant because the heat capacity rate ratio C*=Cmin/Cmax tends toward zero in the element. Thus temperature is controlled by effectiveness of a local element corresponding to an evaporator or a condenser-type element. The model is validated through comparison with theoretical algebraic relations for single-pass cross-flow arrangements with one or more rows. Very small relative errors are obtained showing the accuracy of the present model. epsilon -NTU curves for several complex circuit arrangements are presented. The model developed represents a useful research tool for theoretical and experimental studies on heat exchangers performance.

H. A. Navarro; L. C. Cabezas-Gómez

2007-01-01

 
 
 
 
81

Heat Transfer in Thermal Entrance Region of Cocurrent Flow Heat Exchangers with Fully Developed Laminar Flow.  

Science.gov (United States)

Although the method developed was applied only to cocurrent flow systems, it is believed that a similar approach involving the Duhamel theorem can be used for other multistream problems such as countercurrent flow systems. (Author)

W. N. Gill E. W. Porta R. J. Nunge

1968-01-01

82

Numerical simulation of two phase flows in heat exchangers  

International Nuclear Information System (INIS)

[en] The report presents globally the works done by the author in the thermohydraulic applied to nuclear reactors flows. It presents the studies done to the numerical simulation of the two phase flows in the steam generators and a finite element method to compute these flows. (author)

2006-01-01

83

Vacuum powered heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

In an internal combustion engine including an oil lubrication system, a liquid cooling system, and an improved air intake system is described. The improved air intake system comprises: a housing including a first opening in one end, which opening is open to the atmosphere and a second opening comprising an air outlet opening in the other end open to the air intake manifold of the engine, a heat exchanger positioned in the first opening. The heat exchanger consists of a series of coils positioned in the flow path of the atmospheric air as it enters the housing, the heat exchanger being fluidly connected to either the engine lubrication system or the cooling system to provide a warm heat source for the incoming air to the housing, acceleration means positioned in the housing downstream of the heat exchanger, the acceleration means comprising a honeycomb structure positioned across the air intake flow path. The honey-comb structure includes a multitude of honey combed mini-venturi cells through which the heated air flows in an accelerated mode, a removable air filter positioned between the heat exchanger and the acceleration means and a single opening provided in the housing through which the air filter can be passed and removed, and additional openings in the housing positioned downstream of the heat exchanger and upstream of the air filter, the additional openings including removable flaps for opening and closing the openings to control the temperature of the air flowing through the housing.

Ruffolo, R.F.

1986-06-24

84

An experimental study of the influence of the temperature difference field uniformity on cross-flow heat exchanger performance  

Energy Technology Data Exchange (ETDEWEB)

An experimental study of heat exchanger performance has been conducted utilizing a basic cross-flow heat exchanger configuration. Six different cross-flow, finned-tube heat exchanger flow configurations were tested in a specially designed wind tunnel system to investigate the importance of the Temperature Difference Uniformity on the effectiveness of heat exchanger performance. The Temperature Difference Field (TDF) and the Temperature Difference Uniformity Factor, {Phi}, were employed as design factors to characterize and evaluate heat exchanger thermal performance. A base heat exchanger configuration was established, and then five modifications on the base configuration were made in a systematic study to enhance the performance. The fluids were air on the outside, and hot water inside the tubes. The basic configurations included either 28 or 56 tubes in the bank. The results of the experiments have clearly demonstrated the importance of flow distribution and how it can be used to control the Temperature Difference Field; which, as a design parameter, is an important component of heat exchanger performance optimization. Heat exchanger effectiveness for the best flow distribution was found to increase by 4.3% over that of the conventional flow distribution with no associated increase in pressure drop. This promotes a new path for them to increase heat exchanger heat transfer effectiveness. Comments on further possible performance enhancement strategies are presented.

Lu, B.; Lloyd, J.R. [Michigan State Univ., East Lansing, MI (United States). Dept. of Mechanical Engineering; Guo, Z.Y.; Zhou, S.Q. [Tsinghua Univ., Beijing (China). Dept. of Engineering Mechanics

1996-12-31

85

Corrosive resistant heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

86

A review of heat exchanger tube bundle vibrations in two-phase cross-flow  

International Nuclear Information System (INIS)

Flow-induced vibration is an important concern to the designers of heat exchangers subjected to high flows of gases or liquids. Two-phase cross-flow occurs in industrial heat exchangers, such as nuclear steam generators, condensers, and boilers, etc. Under certain flow regimes and fluid velocities, the fluid forces result in tube vibration and damage due to fretting and fatigue. Prediction of these forces requires an understanding of the flow regimes found in heat exchanger tube bundles. Excessive vibrations under normal operating conditions can lead to tube failure. Relatively little information exists on two-phase vibration. This is not surprising as single-phase flow induced vibration; a simpler topic is not yet fully understood. Vibration in two-phase is much more complex because it depends upon two-phase flow regime, i.e. characteristics of two-phase mixture and involves an important consideration, which is the void fraction. The effect of characteristics of two-phase mixture on flow-induced vibration is still largely unknown. Two-phase flow experiments are much more expensive and difficult to carry out as they usually require pressurized loops with the ability to produce two-phase mixtures. Although convenient from an experimental point of view, air-water mixture if used as a simulation fluid, is quite different from high-pressure steam-water. A reasonable compromise between experimental convenience and simulation of steam-water two-phase flow is desired. This paper reviews known models and experimental research on two-phase cross-flow induced vibration in tube bundles. Despite the considerable differences in the models, there is some agreement in the general conclusions. The effect of tube bundle geometry, random turbulence excitations, hydrodynamic mass and damping ratio on tube response has also been reviewed. Fluid-structure interaction, void fraction modeling/measurements and finally Tubular Exchanger Manufacturers Association (TEMA) considerations have also been highlighted.

2004-01-01

87

New idea of heat exchanger for study of flow-induced vibration for tube arrays in cross-flow  

International Nuclear Information System (INIS)

The flow-induced vibration of tube arrays is very important in heat exchanger. On the basis of the author's theory system and research experiment in the field of flow induced vibration, a new idea to study the flow induced vibration of tube bundle in heat exchanger is presented in this paper. The oscillating fluid mechanics theorem and parameter polynomial method are used to solve the flow equations. Then, the fluid force induced the bundles vibration can be obtained. The full functional analysis method is applied to predict the stability condition of fluid-elasticity. The theory of propagation characteristic of oscillating pressure is used to analyze the phenomena of flow-induced vibration including acoustic resonance. The idea indicates a new approach in the study of the flow-induced vibration in this area

2003-01-01

88

Dynamic model of counter flow air to air heat exchanger for comfort ventilation with condensation and frost formation  

DEFF Research Database (Denmark)

In cold climates heat recovery in the ventilation system is essential to reduce heating energy demand. Condensation and freezing occur often in efficient heat exchangers used in cold climates. To develop efficient heat exchangers and defrosting strategies for cold climates, heat and mass transfer must be calculated under conditions with condensation and freezing. This article presents a dynamic model of a counter flow air to air heat exchanger taking into account condensation and freezing and melting of ice. The model is implemented in Simulink and results are compared to measurements on a prototype heat exchanger for cold climates.

Nielsen, Toke Rammer; Rose, JØrgen

2009-01-01

89

Microtube strip heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

Doty, F.D.

1991-10-16

90

HEAT TRANSFER AND FLUID FLOW ANALYSIS IN PLATE-FIN AND TUBE HEAT EXCHANGERS WITH DIFFERENT SHAPED VORTEX GENERATORS  

Directory of Open Access Journals (Sweden)

Full Text Available Numerical analyses were carried out to study the heat transfer and flow in the plate-fin and tube heat exchangers with different shaped vortex generators mounted behind the tubes. The effects of different span angles a (? = 30°, 45° and 60°) are investigated in detail for the Reynolds number ranging from 500 to 2500. Numerical simulation was performed by computational fluid dynamics of the heat transfer and fluid flow. The results indicated that the triangle shaped winglet is able to generate longitudinal vortices and improve the heat transfer performance in the wake regions. The case of ? = 45° provides the best heat transfer augmentation than rectangle shape winglet generator in case of inline tubes. Common flow up configuration causes significant separation delay, reduces form drag, and removes the zone of poor heat transfer from the near wake of the tubes.

K.Thirumalai kannan; B.Senthil Kumar

2012-01-01

91

Heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger comparising a shell attached at its open end to one side of a tube sheet and a detachable head connected to the other side of said tube sheet. The head is divided into a first and second chamber in fluid communication with a nozzle inlet and nozzle outlet, respectively, formed in said tube sheet. A tube bundle is mounted within said shell and is provided with inlets and outlets formed in said tube sheet in communication with said first and second chambers, respectively.

Brackenbury, Phillip J. (Richland, WA)

1986-01-01

92

Theoretical and experimental investigation of wickless heat pipes flat plate solar collector with cross flow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

In this work, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was investigated theoretically and experimentally under the meteorological conditions of Cairo, Egypt. The author's earlier simulation program of wickless heat pipes flat plate solar water heaters was modified to be valid for the present type of wickless heat pipes solar collector by including the solution of the dimensionless governing equations of the present analysis. For verifying the modified simulation program, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was designed, constructed, and tested at different meteorological conditions and operating parameters. These parameters include different cooling water mass flow rates and different inlet cooling water temperatures. The comparison between the experimental results and their corresponding simulated ones showed considerable agreement. Under different climatic conditions, the experimental and theoretical results showed that the optimal mass flow rate is very close to the ASHRAE standard mass flow rate for testing conventional flat plate solar collectors. Also, the experimental and theoretical results indicated that the number of wickless heat pipes has a significant effect on the collector efficiency. (author)

Hussein, H.M.S. [Solar Energy Department, National Research Centre, El-Tahrir St., Dokki 12622, Giza (Egypt)

2007-04-15

93

Theoretical and experimental investigation of wickless heat pipes flat plate solar collector with cross flow heat exchanger  

International Nuclear Information System (INIS)

In this work, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was investigated theoretically and experimentally under the meteorological conditions of Cairo, Egypt. The author's earlier simulation program of wickless heat pipes flat plate solar water heaters was modified to be valid for the present type of wickless heat pipes solar collector by including the solution of the dimensionless governing equations of the present analysis. For verifying the modified simulation program, a wickless heat pipes flat plate solar collector with a cross flow heat exchanger was designed, constructed, and tested at different meteorological conditions and operating parameters. These parameters include different cooling water mass flow rates and different inlet cooling water temperatures. The comparison between the experimental results and their corresponding simulated ones showed considerable agreement. Under different climatic conditions, the experimental and theoretical results showed that the optimal mass flow rate is very close to the ASHRAE standard mass flow rate for testing conventional flat plate solar collectors. Also, the experimental and theoretical results indicated that the number of wickless heat pipes has a significant effect on the collector efficiency.

1262-01-00

94

Numerical simulation of turbulent shear flow in an isothermal heat exchanger model  

Energy Technology Data Exchange (ETDEWEB)

Numerical predictions of fluid flow are reported for the isothermal, two-dimensional, axisymmetric flow in a disk-doughnut heat exchanger. The system consists of alternating and equi-spaced doughnut and disk baffles located in a pipe with water flowing in a turbulent regime. The two-equation (k = f) turbulence model is modified to accommodate disc and doughnut baffles. The governing equations for steady-state flow are solved in primitive variable form using segregated pressure correction linked algorithm. Predictions are critically evaluated against available data for mean quantities.

Zhang, C.; Sousa, A.C.M. (New Brunswick Univ., Fredericton, NB (Canada). Dept. of Mechanical Engineering)

1990-03-01

95

Entropy Generation Minimization in a Ram-Air Cross-Flow Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the constrained thermodynamic optimization of a crossflow heat exchanger with ram air on the cold side. The ram-air stream passes through a diffuser before entering the heat exchanger, and exits through a nozzle. This configuration is used in the environmental control systems of aircraft. In the first part of the study the heat exchanger is optimized alone, subject to fixed total volume and volume fraction occupied by solid walls. Optimized geometric features such as the ratio of channel spacings and flow lengths are reported. It is found that the optimized features are relatively insensitive to changes in other physical parameters of the installation. In the second part of the study the entropy generation rate also accounts for the irreversibility due to discharging the ram-air stream into the atmosphere. The optimized geometric features are relatively insensitive to this additional effect, emphasizing the robustness of the thermodynamic optimum.

Asad Alebrahim; Adrian Bejan

1999-01-01

96

Experimental investigation of air side heat transfer and fluid flow performances of multi-port serpentine cross-flow mesochannel heat exchanger  

International Nuclear Information System (INIS)

Highlights: ? Air side heat transfer and flow characteristics of mesochannel cross-flow heat exchanger are studied experimentally. ? Hot ethylene glycol–water mixture (50:50) at constant mass flow rate is used against varying air flow. ? Air side heat transfer and fluid flow key parameters such as Nusselt number, Colburn factor, friction factor are obtained. ? General correlations are proposed for air side heat transfer and fluid flow parameters. - Abstract: Air side force convective heat transfer and flow characteristics of cross-flow mesochannel heat exchanger are investigated experimentally. A series of experiments representing 36 different operating conditions have been conducted on a finned mesochannel heat exchanger through the fully automated dynamic single-phase experimental facility which is capable of handling a wide variety of working fluids in air-to-liquid cross-flow orientation. The mesochannel heat exchanger is made of 15 aluminum slabs with arrays of wavy fins between slabs; 68 one millimeter circular diameter port located at each slab, and the air side frontal area of 304-mm × 304-mm. The ethylene glycol–water mixture as the working fluid in the liquid side was forced to flow through mesochannels maintaining constant inlet temperature and flow rate at 74 °C and 0.0345 kg/s respectively whereas the inlet flowing air into the arrays of wavy fins was changed at four different temperature levels from 28 °C to 43 °C. Frontal air velocity was altered in nine steps from 3 m/s to 11 m/s at each temperature level corresponding range of Reynolds number 752 a a) and Colburn factor (ja) were found higher in comparison with other studies.

2012-01-01

97

Visualization of Sub-Cooled Flow Film Boiling in Horizontal Channel on Flat Heat Exchangers  

International Nuclear Information System (INIS)

The observation of sub-cooled flow film boiling was performed on a single-side-heated flat heat exchanger by using refrigerant R134a as the testing fluid. A stable vapor film was observed with the co-existence of sub-cooled bulk liquid. Vapor bubbles might release from the film, with the number and frequency changing under different conditions. The purpose of this paper is to describe these observations, and to provide a quantitative analysis of the phenomena. Results are compared with Berenson's model on horizontal heating surface, with discussion and suggestion made. (authors)

2006-01-01

98

A 2-D oscillating flow analysis in Stirling engine heat exchangers  

Science.gov (United States)

A two dimensional oscillating flow analysis was conducted, simulating the gas flow inside Stirling heat exchangers. Both laminar and turbulent oscillating pipe flow were investigated numerically for Re(max) = 1920 (Va = 80), 10800 (Va = 272), 19300 (Va = 272), and 60800 (Va = 126). The results are compared with experimental results of previous investigators. Also, predictions of the flow regime on present oscillating flow conditions were checked by comparing velocity amplitudes and phase differences with those from laminar theory and quasi-steady profile. A high Reynolds number k-epsilon turbulence model was used for turbulent oscillating pipe flow. Finally, performance evaluation of the K-epsilon model was made to explore the applicability of quasi-steady turbulent models to unsteady oscillating flow analysis.

Ahn, Kyung H.; Ibrahim, Mounir B.

1991-01-01

99

High temperature heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This book contains the proceedings from the XVII Symposium of the International Center for Heat and Mass Transfer on High Temperature Heat Exchangers, held August 1985 in Yugoslavia. Papers were presented under the following topics: High Temperature Heat Exchangers Development; Basic Problem in High Temperature Heat Exchangers; Heat Exchangers for High Temperature Recovery; and High Temperature Heat Exchangers for Future Power Plants and Industrial Process Application. Some of the papers' titles are: Future Development of High Temperature Heat Exchangers; Regenerative and Direct Contact High Temperature Heat Exchangers; Heat Exchangers for Heat Recovery; High Temeprature Heat Transfer Augmentation; and Development of a BOF Slag Granulating and Heat Recovering System.

Mori, Y.; Sheindlin, A.E.; Afgan, N.

1986-01-01

100

The transient, steady-state, and stability behavior of a toroidal thermosyphon with a parallel-flow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

The transient and steady-state heat transfer, fluid flow, and stability of a toroidal thermosyphon have been studied theoretically. The thermosyphon is heated over the lower half and cooled over the upper half by an annular parallel-flow heat exchanger. Under some conditions the system becomes unstable and the interaction between the fluids in the thermosyphon and in the heat exchanger is of special interest. Indeed, two neutrally stable curves are obtained for the same heat exchanger conditions. Detailed results and discussion are presented for the stability of the system as well as for the temperature, velocity, pressure drop, and efficiency.

Mertol, A.; Giz, A.T.; Greif, R.

1983-02-01

 
 
 
 
101

The axial dispersion model for cross-flow heat exchangers; Das axiale Dispersionsmodell fuer Kreuzstromwaermeuebertraeger  

Energy Technology Data Exchange (ETDEWEB)

The steady and transient behaviour of cross-flow heat exchangers are investigated using the axial dispersion model. One direct application of Danckwerts` boundary value problem is the steady-state temperature distribution in a cross-flow heat exchanger with axial dispersion in a fluid. The algorithm also applies to the field of complex variables. The transient behaviour of the cros-flow heat exchanger with axial dispersion in a fluid as a result of random time vriations of temperature at the inlet of both fluids was solved analytically. The method can also be applied to mass transfer processes. A method of measurement with steady temperature variation for liquid flow and another one with developing temperature oscillation for fluids in general were developed for experimental determination of the heat transfer coefficients and axial dispersion coefficients in the heat exchanger. (orig.) [Deutsch] Mit dem Konzept des axialen Dispersionsmodells wird das stationaere und instationaere Verhalten von Kreuzstromwaermeuebertragern untersucht. Das Verfahren zur analytischen Loesung des in der Untersuchung getroffenen Randwertproblems von Danckwerts wurde aufgestellt. Eine unmittelbare Anwendung des Randwertproblems von Danckwerts ist die stationaere Temperaturverteilung im Kreuzstromwaermeuebertrager mit axialer Dispersion in einem Fluid. Der Algorithmus gilt auch im Gebiet komplexer Variablen. Somit wurde das instationaere Verhalten des Kreuzstromwaermeuebertragers mit axialer Dispersion in einem Fluid infolge beliebiger zeitlicher Temperaturaenderungen an den Eintritten beider Fluide analytisch geloest. Dieses Verfahren kann auch auf Stoffuebergangsprozesse angewendet werden. Zur experimentellen Bestimmung der Waermeuebergangskoeffizienten und der axialen Dispersionskoeffizienten im Waermeuebertrager wurde ein Messverfahren mit stationaerer Temperaturschwingung fuer Fluessigkeitsstroemung sowie ein Messverfahren mit sich entwickelender Temperaturschwingung fuer allgemeine Fluide aufgestellt. (orig.)

Luo, Xing

1998-09-01

102

The Design of Heat Exchangers  

Directory of Open Access Journals (Sweden)

Full Text Available A relation between heat transferred and energy loss, for turbulent flow. In different tube arrangements, is made. The conditions are determined which decide the dimensions and velocities for a heat exchanger. Also, a reference to the economic dimensioning of heat exchangers is presented. In this study, the conditions which a heat exchanger must satisfy represent the best balance between the amounts of material employed. The investigation is restricted to the case of turbulent flow.

Arturo Reyes-León; Miguel Toledo Velázquez; Pedro Quinto-Diez; Florencio Sánchez-Silva; Juan Abugaber-Francis; Celerino Reséndiz-Rosas

2011-01-01

103

Velocity Boundary Layer Analysis of a Flat Plate Heat Exchanger in Laminar Flow: A Case Study  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, a behavioral analysis of velocity boundary layer in a flat plate heat exchanger in laminar flow condition through CFD simulation using FLUENT software is done. The main objective of this study is to determine the velocity vectors between the flat plates of the heat exchanger. In addition, wake occurrence, differences of velocity at different surfaces between plates, angles of velocity vectors and the effect of wake phenomenon on the shear stresses exerted on the plates are discussed in detail. The study graphically illustrates results based on fluid’s behavior by a 3D and 2D simulation with air and water as cold and hot streams that affect plate’s situation and its hydro dynamical operations. Consequently, some important design features regarding wake point occurrence and pressure loss are investigated. In addition, eddy current and reverse flows in the wake area and the angles of the velocity vectors are described.

M. Mirdrikvand; B. Roozbehani; S. I. Moqadam; A. C. Roshan; Y. Ramezani

2012-01-01

104

Heat pipe array heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

105

Numerical study of a M-cycle cross-flow heat exchanger for indirect evaporative cooling  

Energy Technology Data Exchange (ETDEWEB)

In this paper, numerical analyses of the thermal performance of an indirect evaporative air cooler incorporating a M-cycle cross-flow heat exchanger has been carried out. The numerical model was established from solving the coupled governing equations for heat and mass transfer between the product and working air, using the finite-element method. The model was developed using the EES (Engineering Equation Solver) environment and validated by published experimental data. Correlation between the cooling (wet-bulb) effectiveness, system COP and a number of air flow/exchanger parameters was developed. It is found that lower channel air velocity, lower inlet air relative humidity, and higher working-to-product air ratio yielded higher cooling effectiveness. The recommended average air velocities in dry and wet channels should not be greater than 1.77 m/s and 0.7 m/s, respectively. The optimum flow ratio of working-to-product air for this cooler is 50%. The channel geometric sizes, i.e. channel length and height, also impose significant impact to system performance. Longer channel length and smaller channel height contribute to increase of the system cooling effectiveness but lead to reduced system COP. The recommend channel height is 4 mm and the dimensionless channel length, i.e., ratio of the channel length to height, should be in the range 100 to 300. Numerical study results indicated that this new type of M-cycle heat and mass exchanger can achieve 16.7% higher cooling effectiveness compared with the conventional cross-flow heat and mass exchanger for the indirect evaporative cooler. The model of this kind is new and not yet reported in literatures. The results of the study help with design and performance analyses of such a new type of indirect evaporative air cooler, and in further, help increasing market rating of the technology within building air conditioning sector, which is currently dominated by the conventional compression refrigeration technology. (author)

Zhan, Changhong [Department of the Built Environment, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); School of Civil Engineering, Northeast Forestry University, Harbin 150040 (China); Zhao, Xudong; Smith, Stefan [Institute of Energy and Sustainable Development, De Montfort University, The Gateway, Leicester LE1 9BH (United Kingdom); Riffat, S.B. [Department of the Built Environment, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

2011-03-15

106

Visualization of fluidized-bed heat exchanger in upward/downward flow condition by neutron radiography  

International Nuclear Information System (INIS)

[en] Heat transfer characteristics of a fluidized-bed heat exchanger are dominated by the characteristics of bed-material movement, especially, in the neighboring region of the heat transfer tube. In the present experiment, a simulated fluidized-bed heat exchanger model was partitioned into two channels to form an upward and downward flow simultaneously in the same fluidized-bed model. Then the total amount of circulating material was kept at the same value even at the different void fractions between two channels. The flow pattern of bed material was visualized by neutron radiography with introducing tracers into the fluidized bed. The simulated fluidized bed consisted of aluminum plates, and the bed materials were sands of 96% SiO2 (mean particle diameter: 0.154-0.321 mm, density: 2550 kg/m3). Bed materials were almost transparent for neutrons. On the contrary, tracer particles of about 1 mm diameter made of B4C with clay were opaque. Thus, the tracer particles were detected clear enough for PTV (Particle Tracking Velocimetry). The fluidized-bed behavior was then discussed in relation to the heat transfer characteristics around the heated tubes submerged in the bed

2005-04-21

107

Performance Analysis of Cross Flow Plate Fin Heat Exchanger for Immiscible System Using ANN  

Directory of Open Access Journals (Sweden)

Full Text Available An experimental investigation on heat transfer study on a solvent and solution were made using cross flow plate fin heat exchanger. Steam is the hot fluid, whereas Steam and Toluene-Steam immiscible solution serves as cold fluid. A series of runs were made between steam and water, steam and Toluene solution. In addition to, the volume fraction of Toluene was varied and the experiment was held. The flow rate of the cold fluid is maintained from 120 to 720 lph and the volume fraction of Toluene is varied from 10-50%. Experimental results such as exchanger effectiveness, overall heat transfer coefficients were calculated. Simulation studies were carried out to predict Nusselt number of the cold fluid (NNu), Fin Effectiveness (?), Cold Side Efficiency (?c) and Hot Side Efficiency (?h) for the heat exchanger using ANN. General regression is used to train and test the network since the target data was continuous. It is shown that the predicted results are close to experimental data by ANN approach. The model was compared with the experimental findings and found to be valid.

Thirumarimurugan M.; Kannadasan T.; Gopalakrishnan S.

2010-01-01

108

Microtube strip heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

Doty, F.D.

1992-07-09

109

The influence of the wall temperature on the development of heat transfer and secondary flow in a coiled heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

In the present study the development of mixed convective flow is studied in a helically coiled heat exchanger with an axially varying wall temperature for Re = 500, Pr = 5 and {delta} = 1/14 and compared to the constant wall temperature boundary condition. In the method used the parabolized equations are solved using a finite difference discretization scheme. The influence of buoyancy forces is analyzed on heat transfer and secondary flow. For all Grashof numbers studied it appears that both heat transfer, quantified by the Nusselt number, and secondary flow, quantified by the relative kinetic energy, exhibit a wavy behavior in axial direction. For higher Grashof numbers, however, this phenomenon diminishes for the case with an axially varying wall temperature due to stabilizing stratification effects. A typical example of a helically coiled tube can be found in the storage vessel of a Solar Domestic Hot Water System (SDHWS).

Rindt, C.C.M.; Sillekens, J.J.M.; Steenhoven, A.A. van [Eindhoven Univ. of Technology (Netherlands). Dept. of Mechanical Engineering

1999-02-01

110

Modeling Free Convection Flow of Liquid Hydrogen within a Cylindrical Heat Exchanger Cooled to 14 K  

Energy Technology Data Exchange (ETDEWEB)

A liquid hydrogen in a absorber for muon cooling requires that up to 300 W be removed from 20 liters of liquid hydrogen. The wall of the container is a heat exchanger between the hydrogen and 14 K helium gas in channels within the wall. The warm liquid hydrogen is circulated down the cylindrical walls of the absorber by free convection. The flow of the hydrogen is studied using FEA methods for two cases and the heat transfer coefficient to the wall is calculated. The first case is when the wall is bare. The second case is when there is a duct some distance inside the cooled wall.

Green, Michael A.; Oxford U.; Yang, S.W.; Green, M.A.; Lau, W.

2004-05-08

111

Fouling of heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

All aspects of heat exchanger fouling are considered, from the basic science of how surfaces become fouled to very practical ways of mitigating the problem and from mathematical modeling of different fouling mechanisms to practical methods of heat exchanger cleaning. The problems that restrict the efficient operation of equipment are described and the costs, some of them hidden costs, that are associated with the fouling of heat exchangers are discussed. Some simple concepts and models of the fouling processes are presented as part of the introduction to the subject. Advice on the selection, design, installation and commissioning of heat exchangers to minimize fouling is given. A large part of the test is devoted to the use of chemical and other additives to reduce or eliminate the problem of fouling. Another large section is designed to give information on both on-line and off-line cleaning of heat exchangers. One of the difficulties faced by designers and operators of heat exchangers is anticipating the likely extent of fouling problems to be encountered with different flow streams. Another large section addresses the question and describes methods that have been used in attempting to define fouling potential. The book concludes with a chapter on how fouling information can be obtained using plant data, field tests and laboratory studies

Bott, T.R. [School of Chemical Engineering, University of Birmingham, Birmingham (United Kingdom)

1995-04-01

112

Effect of nonuniform inlet air flow on air-cooled heat-exchanger performance  

International Nuclear Information System (INIS)

Blowers used to propel air across tube bundles generate a non-uniform flow field due to their construction details. A formalism to evaluate heat transfer degradation due to non-uniform airflow has been developed. Certain symmetry relations for cross flowheat exchangers, heretofore unavailable in the open literature, have been derived. The solution presented here was developed to model a 4 tube pass air blast heat exchanger for the Clinch River Breeder Reactor Plant Project. This case is utilized to show how this method can be used as a design tool to select the most suitable blower construction for a particular application. A numerical example is used to illustrate the salient points of the solution

1983-01-01

113

Heat exchanger restart evaluation  

International Nuclear Information System (INIS)

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

1992-01-01

114

Heat exchanger restart evaluation  

International Nuclear Information System (INIS)

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

1992-01-01

115

Serpentine heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

Tomlinson, R.S.

1991-01-08

116

Non-newtonian flow and pressure drop of pineapple juice in a plate heat exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available The study of non-Newtonian flow in plate heat exchangers (PHEs) is of great importance for the food industry. The objective of this work was to study the pressure drop of pineapple juice in a PHE with 50º chevron plates. Density and flow properties of pineapple juice were determined and correlated with temperature (17.4 < T < 85.8ºC) and soluble solids content (11.0 < Xs < 52.4 ºBrix). The Ostwald-de Waele (power law) model described well the rheological behavior. The friction factor for non-isothermal flow of pineapple juice in the PHE was obtained for diagonal and parallel/side flow. Experimental results were well correlated with the generalized Reynolds number (20 < Re g < 1230) and were compared with predictions from equations from the literature. The mean absolute error for pressure drop prediction was 4% for the diagonal plate and 10% for the parallel plate.

R. A. F. Cabral; J. A. W. Gut; V. R. N. Telis; J. Telis-Romero

2010-01-01

117

Tubular heat exchanger for a nuclear reactor  

International Nuclear Information System (INIS)

[en] Heat exchanger appliance, featuring a first heat exchanger to bring the heating fluid and a heated fluid into thermal communication by flow of the fluids inside this exchanger, and a pre-cooling heat exchanger arranged in one unit inside the first heat exchanger for the purpose of bringing the heating fluid into thermal communication with the heating fluid flowing in the first heat exchanger, so that the temperature of the heating fluid is lowered before it is placed in thermal communication with the heated fluid

1978-06-22

118

Heat exchanger performance monitoring guidelines  

International Nuclear Information System (INIS)

Fouling can occur in many heat exchanger applications in a way that impedes heat transfer and fluid flow and reduces the heat transfer or performance capability of the heat exchanger. Fouling may be significant for heat exchanger surfaces and flow paths in contact with plant service water. This report presents guidelines for performance monitoring of heat exchangers subject to fouling. Guidelines include selection of heat exchangers to monitor based on system function, safety function and system configuration. Five monitoring methods are discussed: the heat transfer, temperature monitoring, temperature effectiveness, delta P and periodic maintenance methods. Guidelines are included for selecting the appropriate monitoring methods and for implementing the selected methods. The report also includes a bibliography, example calculations, and technical notes applicable to the heat transfer method.

1991-01-01

119

Performance testing of cross flow heat exchanger operating in the atmosphere of flue gas particulate with vapor condensation  

Directory of Open Access Journals (Sweden)

Full Text Available Performance testing of a cross flow heat exchanger operating under the atmosphere of flue gas particulate from combustion was carried out in this work. This heat exchanger exchanges heat between flue gas from the fuel oil combustion and cold water. The heat exchanger is composed of a spiral finned tube bank having 3 rows and 8 tubes per row with a staggered arrangement. The fin spacings considered are 2.85 and 6.10 mm. The theories of thermodynamics and heat transfer are used for analyzing the performance of this system.In this experiment, the flue gas temperature of 200ºC from combustion having 0.35 kg/s mass flow rate flows along outside surface of the heat exchanger and transfers heat to the 25ºC cooling water having 0.15 kg/s mass flow rate flowing in the tube side. Each experiment uses 750 hr for testing. During the testing, part of flue gas condenses on the heat transfer surface.From the experiment, it was found that the heat transfer rate of both heat exchangers tended to decrease with time while the airside pressure drop increased. These results come from the fouling on the heat transfer surface. Moreover, it is found that the heat exchanger having 2.85 mm fin spacing has an approximately 4 times higher fouling resistance than that of the 6.10 mm fin spacing.In this work a model for calculating the fouling resistance is also developed as a the function of time. The model is developed from that of Kern and Seaton and the mean deviation of the model is 0.789.

Nuntaphan, A.; Kiatsiriroat, T.

2006-01-01

120

Lightweight, compact heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger is described comprising: tubes defining first flow paths; pairs of generally C-shaped bars spacing tubes apart from adjacent tubes, the bars extending generally perpendicular to tubes and each pair of bars defining a second flow paths; an extended surface heat transfer element between each pair of bars; an integral lanced tab formed at each end of the bars, each tab folded over itself toward the heat exchanger center and capturing a portion of the extended surface heat transfer element between itself and the bar; side plates on each side of the heat exchanger, the side plate spaced from one of the tubes by a pair of bars; means for securing the tubes, bars, extended surface heat transfer elements and side plates together; and manifold means, sealingly attached to the tube ends for distributing a working fluid into first flow paths at one end of the tubes and for selecting the working fluid at the opposite end of the tubes.

Kredo, T.A.

1987-07-21

 
 
 
 
121

Heat exchanger vibration  

International Nuclear Information System (INIS)

The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration

1977-01-01

122

Helixchanger, advanced shell and tube heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

This article discusses the effectiveness of heat exchangers, and describes shellside flows and helical baffle enhancement technology, tube and tubeside enhancement technologies, and the cost of heat exchangers, retrofitting exchangers, and design are considered. (UK)

Van Der Ploeg, H.J. [ABB Lummus Heat Transfer B.V., Voorburg (Netherlands)

1996-12-01

123

Optimization of zigzag flow channels of a printed circuit heat exchanger for nuclear power plant application  

International Nuclear Information System (INIS)

Printed circuit heat exchanger (PCHE) is recently considered as a recuperator for the high-temperature gas cooled reactor. In this study, shape optimization of zigzag flow channels in a PCHE has been performed to enhance heat transfer performance and reduce the friction loss based on three-dimensional Reynolds-averaged Navier-Stokes analysis with the Shear Stress Transport Turbulence model. A multi-objective genetic algorithm is used for the multi-objective optimization. Two non-dimensional objective functions related to heat transfer performance and friction loss are employed. The shape of a flow channel is defined by two geometric design variables, viz. the cold channel angle and the ellipse aspect ratio of the cold channel. The experimental points within the design space are selected using Latin hypercube sampling as the design of the experiment. The response surface approximation model is used to approximate the Pareto-optimal front. Five optimal designs on the Pareto-optimal front have been selected using k-means clustering. The flow and heat transfer characteristics, as well as the objective function values, of these designs have been compared with those of the reference design. (author)

2012-01-01

124

The concept of a new approximate relation for heat transfer effectiveness for a cross-flow heat exchanger with unmixed fluids  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an approximate relation for the heat transfer effectiveness for a counter-flow heat exchanger, which was compared with the exact solution. Based on the obtained approximate relation for a counter-flow heat exchanger the approximate heat transfer effectiveness for a cross-flow heat exchanger in which both fluids do not mix is proposed. This approximate heat transfer effectiveness was compared with the exact solution proposed by Mason, the most well-known relation. A comparison between the most frequently used approximate formula and the exact solution proposed by Mason was made, too. The heat transfer effectiveness was analyzed for the ratio of the heat capacity of fluids C in the range from 0 to 1 and the number of transfer units NTU from the most common range 0 – 5.

Rafal Marcin Laskowski

2011-01-01

125

Assessment of flow induced vibration in a sodium-sodium heat exchanger  

International Nuclear Information System (INIS)

The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium cooled pool type fast reactor with all primary components located inside a sodium pool. The heat produced due to fission in the core is transported by primary sodium to the secondary sodium in a sodium to sodium Intermediate Heat Exchanger (IHX), which in turn is transferred to water in the steam generator. PFBR IHX is a shell and tube type heat exchanger with primary sodium on shell side and secondary sodium in the tube side. Since IHX is one of the critical components placed inside the radioactive primary sodium, trouble-free operation of the IHX is very much essential for power plant availability. To validate the design and the adequacy of the support system provided for the IHX, flow induced vibration (FIV) experiments were carried out in a water test loop on a 60 deg. sector model. This paper discusses the flow induced vibration measurements carried out in 60 deg. sector model of IHX, the modeling criteria, the results and conclusion.

2009-01-01

126

Assessment of flow induced vibration in a sodium-sodium heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium cooled pool type fast reactor with all primary components located inside a sodium pool. The heat produced due to fission in the core is transported by primary sodium to the secondary sodium in a sodium to sodium Intermediate Heat Exchanger (IHX), which in turn is transferred to water in the steam generator. PFBR IHX is a shell and tube type heat exchanger with primary sodium on shell side and secondary sodium in the tube side. Since IHX is one of the critical components placed inside the radioactive primary sodium, trouble-free operation of the IHX is very much essential for power plant availability. To validate the design and the adequacy of the support system provided for the IHX, flow induced vibration (FIV) experiments were carried out in a water test loop on a 60 deg. sector model. This paper discusses the flow induced vibration measurements carried out in 60 deg. sector model of IHX, the modeling criteria, the results and conclusion.

Prakash, V. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)], E-mail: prakash@igcar.gov.in; Thirumalai, M.; Prabhakar, R.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

2009-01-15

127

Heat exchanger with packing element between flow shield and the wall of the housing  

International Nuclear Information System (INIS)

The heat exchanger comprises a housing with a supply duct and an outlet duct for a first medium, a pipe bundle installed in the housing, the pipes being in connection with the supply duct, and an exit duct for a second medium, and round the pipe bundle over a greater part of the length thereof is placed a flow shield with a smaller spacing on the outer side than on the inner side of the housing, also one or more spacing elements between the flow shield and the inner wall of the inner shield of the housing, which elements substantially restrict the passage of the first medium through the space between the flow shield on the inner wall of the housing characterised in that the spacing element(s) is (are) composed of parts made of different metals, which metals have different expansion coefficients. (G.C.)

1980-01-01

128

Air flow test of MK-III dump heat exchanger tube arrays for JOYO  

Energy Technology Data Exchange (ETDEWEB)

The reactor thermal power of JOYO MK-III is to be increased from 100MWt to 140MWt due to high performance of reactor core. So, Dump Heat Exchanger(DHX) of MK-III was designed to improve its heat removal capability by changing U type heat transport tube arrays to {Sigma} type tube arrays and increasing air flow. Natural frequency between support and support of MK-III DHX`s tube arrays was about 15Hz, and Karman vortex shedding frequency of tube arrays was about 90Hz by Y.N.Chen`s report. Then, a possibility of piling up of Karman vortex shedding frequency in high frequency mode was to be considered. And, air velocity of flow tube arrays is also increased compared to the MK-II DHX. Sodium leak accident of MONJU was caused by a flow-induced vibration of thermometer well. Therefore, the air flow test to tube arrays of MK-III DHX was conducted. High cycles fatigue damage of tube arrays was evaluated. Since, peak stress is below 2kg/mm{sup 2}, it can be said that high cycles fatigue damage of tube arrays by Karman vortex shedding vibration will not be caused. (J.P.N.)

Isozaki, Kazunori; Kawahara, Hirotaka; Tomita, Naoki [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1997-07-01

129

Experiments on vibration of heat exchanger tube arrays in cross flow  

International Nuclear Information System (INIS)

[en] A series of tests have been made at the Commissariat a l'Energie Atomique, in cooperation with General Atomic Company, SAN DIEGO (U.S.A.) on the flow-induced vibration of heat exchanger tube bundles in cross flow. These tests were made in air on tube bundles which simulated heat exchangers in the high temperature gas cooled reactors. The tests were of two types. In the first type, an instrumented tube was inserted at various locations into a tube bundle. Measurements were made of pressure at a number of points along the tube and about the circumference of the tube. These measurements were processed to obtain the spectra of turbulent pressure fluctuations on the tube, the spanwise correlation and the lift force. The second set of tests was made on tube bundles with flexible tubes. As the flow velocity was increased, these tests clearly show an instability. Nine tube configurations were tested with both plastic and metallic tubes and the effect of tube-to-tube difference in natural frequency was investigated

1981-08-21

130

Local convective heat exchanges and flow structure in a rotor-stator system  

Energy Technology Data Exchange (ETDEWEB)

This work deals with an experimental study of the flow structure and the local convective exchanges in the air-gap of a rotor-stator system. The experimental technique uses infrared thermography to measure the surface temperatures of the rotor and the numerical solution of the steady state heat equation to determine the local heat transfer coefficients. The analysis of the flow structure between the rotor and the stator is obtained by PIV (Particle Image Velocimetry). Tests are carried out for rotational Reynolds numbers ranging from 5.87 x 10{sup 4} to 1.76 x 10{sup 5} and for gap ratios ranging from 0.01 to 0.17. Analysis of the experimental results has determined the influence of the rotational Reynolds number and the gap ratio on the flow structure and the convective exchanges in the gap between the rotor and the stator. Some correlations expressing the local Nusselt number as a function of the rotational Reynolds number and the gap ratio are proposed. (authors)

Boutarfa, Rachid; Harmand, Souad [Laboratoire de Mecanique et Energetique, Universite de Valenciennes et du Hainaut Cambresis, Le Mont Houy, 59313 cedex 9, Valenciennes (France)

2003-12-01

131

Heat exchanger with ceramic elements  

Energy Technology Data Exchange (ETDEWEB)

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

132

Designing heat exchangers for NPP  

International Nuclear Information System (INIS)

The bases for designing powerful heat exchangers for NPPs with sodium and gas coolants are delivered. The design features, methods of calculation and experimental development of heat exchangers with non-uniform longitudinal-cross coolant flow in a piping beam and methods of operating conditions determination are considered. 133 refs.; 171 figs.; 23 tabs

1988-01-01

133

Thermodynamics and heat exchange devices  

Energy Technology Data Exchange (ETDEWEB)

This paper reviews research efforts in the area of thermodynamic irreversibility of heat exchange components and systems, as well as, their design based on the minimization of the generation of entropy. The examination initially focusses upon the fundamental mechanisms responsible for the generation of entropy in heat and fluid flows and upon design compromises made to establish an equilibrium between the irreversibility of the fluid flow. The applications were chosen with reference to the field of heat exchange mechanisms and heat exchanger design (e.g. power plant components: reheaters, expanders, regenerators, coolers, compressors).

Bejan, A. (Duke Univ., Durham, NC (USA). Dept. of Mechanical Engineering and Material Science)

1988-01-01

134

Heat transfer and pressure drop of supercritical carbon dioxide flowing in several printed circuit heat exchanger channel patterns  

International Nuclear Information System (INIS)

Closed-loop Brayton cycles using supercritical carbon dioxide (SCO2) show potential for use in high-temperature power generation applications including High Temperature Gas Reactors (HTGR) and Sodium-Cooled Fast Reactors (SFR). Compared to Rankine cycles SCO2 Brayton cycles offer similar or improved efficiency and the potential for decreased capital costs due to a reduction in equipment size and complexity. Compact printed-circuit heat exchangers (PCHE) are being considered as part of several SCO2 Brayton designs to further reduce equipment size with increased energy density. Several designs plan to use a gas cooler operating near the pseudo-critical point of carbon dioxide to benefit from large variations in thermophysical properties, but further work is needed to validate correlations for heat transfer and pressure-drop characteristics of SCO2 flows in candidate PCHE channel designs for a variety of operating conditions. This paper presents work on experimental measurements of the heat transfer and pressure drop behavior of miniature channels using carbon dioxide at supercritical pressure. Results from several plate geometries tested in horizontal cooling-mode flow are presented, including a straight semi-circular channel, zigzag channel with a bend angle of 80 degrees, and a channel with a staggered array of extruded airfoil pillars modeled after a NACA 0020 airfoil with an 8.1 mm chord length facing into the flow. Heat transfer coefficients and bulk temperatures are calculated from measured local wall temperatures and local heat fluxes. The experimental results are compared to several methods for estimating the friction factor and Nusselt number of cooling-mode flows at supercritical pressures in millimeter-scale channels. (authors)

2012-01-01

135

Heat transfer and pressure drop of supercritical carbon dioxide flowing in several printed circuit heat exchanger channel patterns  

Energy Technology Data Exchange (ETDEWEB)

Closed-loop Brayton cycles using supercritical carbon dioxide (SCO{sub 2}) show potential for use in high-temperature power generation applications including High Temperature Gas Reactors (HTGR) and Sodium-Cooled Fast Reactors (SFR). Compared to Rankine cycles SCO{sub 2} Brayton cycles offer similar or improved efficiency and the potential for decreased capital costs due to a reduction in equipment size and complexity. Compact printed-circuit heat exchangers (PCHE) are being considered as part of several SCO{sub 2} Brayton designs to further reduce equipment size with increased energy density. Several designs plan to use a gas cooler operating near the pseudo-critical point of carbon dioxide to benefit from large variations in thermophysical properties, but further work is needed to validate correlations for heat transfer and pressure-drop characteristics of SCO{sub 2} flows in candidate PCHE channel designs for a variety of operating conditions. This paper presents work on experimental measurements of the heat transfer and pressure drop behavior of miniature channels using carbon dioxide at supercritical pressure. Results from several plate geometries tested in horizontal cooling-mode flow are presented, including a straight semi-circular channel, zigzag channel with a bend angle of 80 degrees, and a channel with a staggered array of extruded airfoil pillars modeled after a NACA 0020 airfoil with an 8.1 mm chord length facing into the flow. Heat transfer coefficients and bulk temperatures are calculated from measured local wall temperatures and local heat fluxes. The experimental results are compared to several methods for estimating the friction factor and Nusselt number of cooling-mode flows at supercritical pressures in millimeter-scale channels. (authors)

Carlson, M. [Univ. of Wisconsin - Madison, 839 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706 (United States); Kruizenga, A. [Sandia National Laboratory (United States); Anderson, M.; Corradini, M. [Univ. of Wisconsin - Madison, 839 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706 (United States)

2012-07-01

136

Experimental study of turbulent flow heat transfer and pressure drop in a plate heat exchanger with chevron plates  

Energy Technology Data Exchange (ETDEWEB)

Experimental data for isothermal pressure drop and heat transfer in single-phase water flows in a plate heat exchanger (PHE) with chevron plates are presented. A single-pass, U-type, counterflow PHE, with three different chevron plate arrangements is employed: two symmetric plate arrangements with {beta} = 30/30{degree} and 60/60{degree}, and a mixed-plate arrangement with {beta} = 30/60{degree}. With water flow rates in the turbulent flow regime (600 < Re < 10{sup 4} and 2 < Pr < 6), effects of the chevron corrugation inclination angle {beta} on Nu and f characteristics of the PHE are investigated. As {beta} increases and compared to a flat-plate pack, up to 2 to 5 times higher Nu are obtained; the concomitant f, however, are 13 to 44 times higher. Based on the experimental data for Re {le} 1,000, predictive correlations of the form Nu = C{sub 1}{beta} Re{sup p1({beta})} Pr{sup 1/3} ({mu}/{mu}{sub w}){sup 0.14} and f = C{sub 2}{beta} Re{sup p2({beta})} are devised. Also, at constant pumping power and depending upon {beta}, the heat transfer is found to be enhanced over 1.8 times that in equivalent flat-plate channels.

Muley, A.; Manglik, R.M.

1997-07-01

137

Microtube strip heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchangers. The team has begun a heat exchanger stress analysis, however they have been concentrating the bulk of their analytical energies on a CFD model to determine the location and magnitude of shell-side flow maldistribution which decreases heat exchanger effectiveness. DSI received 120 fineblanked tubestrips from Southern Fineblanking (SFB) for manufacturing process development. Both SFB and NIST provided inspection reports of the tubestrips. DSI completed the tooling required to encapsulate a tube array and press tubestrips on the array. Pressing the tubestrips on tube arrays showed design deficiencies both in the tubestrip design and the tooling design. DSI has a number of revisions in process to correct these deficiencies. The research effort has identified a more economical fusible alloy for encapsulating the tube array, and determined the parameters required to successfully encapsulate the tube array with the new alloy. A more compact MTS heat exchanger bank was designed. 1 ref., 4 figs.

Doty, F.D.

1991-04-02

138

Fouling in heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Subjects covered: introduction to heat exchanger fouling; basic fouling models; precipitation fouling; CaCO[sub 3] scaling; black liquor fouling; geothermal brine fouling; particulate fouling; chemical reaction fouling; fouling of enhanced surfaces - experimental results; fouling of enhanced surfaces - theory; chemical fouling mitigation; mechanical fouling mitigation; heat exchanger design for fouling conditions; fouling monitoring systems; cleaning of heat exchangers; and economic aspects of heat exchanger fouling.

1993-01-01

139

Theoretical investigation of the heat exchange in ring channels with local curling of the laminar flow of a viscous liquid  

International Nuclear Information System (INIS)

[en] Theoretical studies are aimed to realize the physical pattern of distribution of the velocity and the temperature fields within the range covering the beginning and complete dying down of flow swirl. The paper studies the heat exchange under the stationary laminar flow of viscous Newtonian liquid in ring channels at the inlet of which there is an axial-blade swirling device to swirl the liquid flow[ru] ???? ????????????? ???????????? - ????????? ?????????? ??????? ????????????? ??????????? ? ?????????????? ????? ? ??????? ?? ?????? ?? ??????? ????????? ???????? ??????. ??????????????? ?????????? ??? ???????????? ?????????? ??????? ?????? ???????????? ???????? ? ?????? ?????????? ???????, ?? ????? ? ??????? ?????????? ?????????-?????????? ????????????? ?????? ????????

1999-01-01

140

Bayonet heat exchangers in heat-assisted Stirling heat pump  

Energy Technology Data Exchange (ETDEWEB)

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

 
 
 
 
141

Methods for detecting fouling in heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Heat exchangers are frequently used in district heating systems, at power plants and public homes. Detecting fouling in district heating heat exchangers is of great importance. There are currently many different ways to detect fouling in heat exchangers that either rely on physical examination of the heat exchanger or modeling the heat exchanger and use measurements of the heat exchanger to predict fouling. The method describe in the paper can be used to detect fouling by using the inlet and outlet temperatures and either the hot or cold mass flow. Results of the method described on a simulated data are given

Gudmundsson, Oddgeir; Palsson, Olafur Petur; Palsson, Halldor (Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, Univ. of Iceland, Reykjavik (Iceland)); Lalot, Sylvain (LME, Univ. of Valenciennes and Hainaut Cambresis, IUT (France))

2008-09-15

142

Improvements to heat exchangers  

International Nuclear Information System (INIS)

[en] The heat exchanger presented consists of a chamber designed so that heating fluid passes through it over tubes carrying fluid which removes heat from the heating fluid. Generally speaking the heating fluid flows in the chamber downwards to the level of lateral holes through which it leaves the chamber or upwards from the level of lateral holes through which it enters, this level corresponding in the chamber to the top of a heating fluid mass cooled by the heat removal fluid. Partition system are foreseen in the heating fluid mass, so arranged as to define a passage through which heating fluid rises by differential thermal effect from the lowest region to that of the inlet and oulet holes. This system applies especially to exchangers associated with a liquid sodium-cooled reactor[fr] On presente un echangeur de chaleur comprenant une enceinte agencee pour que du fluide chauffant la traverse en balayant des tubes traverses par du fluide qui preleve de la chaleur sur le fluide chauffant. Le fluide chauffant circule d'une maniere generale, dans l'enceinte, de haut en bas vers le niveau d'orifices lateraux par lesquels le fluide chauffant sort de l'enceinte ou de bas en haut a partir du niveau d'orifices lateraux par lesquels le fluide chauffant entre dans l'enceinte, ce niveau delimitant dans l'enceinte le haut d'une masse de fluide chauffant refroidie par le fluide de prelevement de chaleur. Il est prevu, dans la masse de fluide chauffant, des moyens de cloisonnement disposes de maniere a definir un passage dans lequel du fluide chauffant monte, par effet thermique differentiel, de la region la plus basse jusqu'au voisinage des orifices, d'entree ou de sortie. Ceci s'applique particulierement aux echangeurs associes a un reacteur a refroidissement par sodium liquide

1974-08-23

143

Experimental study on flow-induced vibration and heat transfer characteristics of heat exchanger with helically coiled tube bundles  

Energy Technology Data Exchange (ETDEWEB)

An experimental study was carried out to investigate flow-induced vibration, heat transfer and pressure drop of helically coiled tube bundles of an intermediate heat exchanger (IHX) for the HTTR, using a full-size partial model and air as a testing fluid. The test model has 54 helically coiled tubes separated into three layer bundles, surrounding the center pipe. The vibration behavior in the fluid was investigated focussing on vortex-induced and fluidelastic vibrations which are main ones to cause failure of tubes. The vibration of the tube bundles was mainly at the center pipe, and their vibration amplitude was less than 0.1 mm. As the results, it was clarified that individual vibrations of the tube bundles were not significant under the operation conditions of the IHX. The Nusselt number of the tube outside, due to forced convection, was obtained as a function of Re{sup 0.56}, and the drag coefficient was proportional to Re{sup -0.14}. Furthermore, effect of radiative plates on heat transfer was clarified. (author)

Inagaki, Yoshiyuki [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

1997-10-01

144

Experimental and numerical study of the distribution of a single-phase flow in a small channel heat exchanger  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study focuses on the distribution of a single-phase flow in a small channel heat exchanger. A test section consisting of a cylindrical header connected to 8 multiport flat tubes of 7 parallel small channels (Dh = 0.889 mm) enables the measurement of singular and regular local pressure losses al...

Poggi, F.; Bontemps, A.; Macchi Tejeda, H.; Marechal, C.; Leducq, D.

145

Simulation of Cross Flow Heat Exchanger for Multi Tubes Using FLUENT 6.3.26  

Directory of Open Access Journals (Sweden)

Full Text Available In chemical engineering a lot of work is done to improve the results of the equipment to make its widespread applications be possible. Simulation is extensively used as the power of the computer is well known nowadays. Simulation is frequently used to study both real and virtual behavior. In this paper experimentation, simulation and development of mathematical models are performed. Practical experiments are made on a cross flow heat exchanger for a multi tube layout with staggered arrangement to study the rate of heat transfer. Simulation is carried out when experimental results are obtained. For designing and meshing of plate geometries GAMBIT 2.3.16 is used and then solution and analysis are accomplished on FLUENT 6.3.26. By comparing experimental and simulated results, it is found that both validate each other with minor differences. Empirical relationships have been also developed. Re and Nu relationships are developed mathematically and compared to the models found in literature concerned. The developed models are found in good agreement with theoretically available models. The future research in this regard can be done by using viscous fluids and an advanced version of the software like Cubit for designing and meshing the plate geometry.DOI: http://dx.doi.org/10.5755/j01.erem.65.3.4453

Suneela Sardar; Shahid Raza Malik

2013-01-01

146

Flow induced vibrations in heat exchangers equipped with helical finned tubes; Stroemungsinduzierte Schwingungen in Spiralrippenrohrbuendelwaermetauschern  

Energy Technology Data Exchange (ETDEWEB)

Flow-induced vibrations resulting from acoustic resonance or fluid-elastic instability cause severe damage to finned-tube heat exchangers. There are hardly any publications on spiral finned tubes. This contribution presents experimental data on intrinsic frequencies and damping of spiral finned tubes as well as equations for calculating intrinsic frequencies. Stability limits for fluid-elastic instabilities were defined in flow experiments. Examples are presented to illustrate the applicability of the calculation method in preventing vibration-induced damage. [German] Stroemungsinduzierte Schwingungen in Rippenrohrwaermetauschern aufgrund von akustischer Resonanz bzw. fluidelastischer Instabilitaet fuehren immer wieder zu schweren Schadensfaellen. Hinsichtlich ihres Schwingungsverhaltens sind Spiralrippenrohre in der Literatur bislang vernachlaessigt worden, obwohl sie in der industriellen Anwendung immer mehr an Bedeutung gewinnen. Im vorliegenden Beitrag werden die Eigenfrequenzen und Daempfungen von Spiralrippenrohren experimentell untersucht und Berechnungsformeln fuer die Eigenfrequenzen angegeben. In Stroemungsexperimenten werden Stabilitaetsgrenzen fuer fluidelastische Instabilitaeten ermittelt. Anhand einiger Beispielfaelle wird aufgezeigt, dass das daraus entwickelte Berechnungsschema zur Absicherung gegen Schwingungsschaeden geeignet ist. (orig.)

Fischer, M.

2003-08-01

147

An experimental study on the flow and heat transfer of flinak molten salt in small channels for the application to the VHTR intermediate heat exchanger  

International Nuclear Information System (INIS)

To make the design of the Very High Temperature Reactor (VHTR) complete and plausible, the designs of the Intermediate Heat Transport Loop (IHTL) as well as the Intermediate Heat Exchanger (IHX) are known to be one of the difficult engineering tasks due to its high temperature operating condition (up to 950degC). In this study, the Flinak molten salt, an eutectic mixture of LiF, NaF and KF (46.5:11.5:42.0 mole %) is considered as the heat transporting fluid in the IHTL. To evaluate the flow and heat transfer performance of the Flinak molten salt in small channels of millimeter-range hydraulic diameters, a double-pipe type heat exchanger was constructed using small-diameter tubes for the heat exchange between the Flinak and gas flow. The inner diameters of the inner tube and the outer tube are 1.4 mm and 4.6 mm, respectively, and the length of the tubes is 500 mm. The molten salt flows through the inner tube. The molten salt is prepared in a crucible made of Inconel 600 placed in an electric furnace. The molten salt flow is produced by differential pressure between a twin set of molten salt crucibles without using a mechanical pump. The flow rate of the molten salt is reduced from the weight change of a crucible measured by load cells. Temperatures of the two heat exchanging fluids at various points as well as pressure drop across the test tube are measured to obtain flow and heat transfer characteristics of the molten salt flow. For laminar flow of the Flinak in 1.4 mm inner-diameter circular tube, the measured friction factors were smaller than the 64/Re curve by 50%. Also the measured Nusselt numbers were generally in the range between 3.66 and 4.36, although the data were scattered due to the measurement error in such a high temperature condition. (author)

2009-01-01

148

Dehumidification: Prediction of condensate flow rate for plate-fin tube heat exchangers using the latent j factor  

Energy Technology Data Exchange (ETDEWEB)

Condensate flow rate is an important factor in designing dehumidifiers or evaporators. In this paper, the latent j factor is used to analyze the dehumidification performance of two plate-fin tube heat exchangers. This latent j factor, analogous to the total j factor, is a function of the mass transfer coefficient, the volumetric air flow rate, and the Schmidt number. This latent j factor did predict condensate flow rate more directly and accurately than any other sensible j factor method. The latent j factor has been used in the present study because the sensible j factor correlations presented in the literature failed to predict the condensate flow rate at high Reynolds numbers. Results show that the latent j factor can be simply correlated as a function of the Reynolds number based on the tube outside diameter and number of rows of the heat exchanger.

Chen, D.T.; Conklin, J.C.; Baxter, V.D.

1999-07-01

149

Dehumidification: Prediction of Condensate Flow Rate for Plate-Fin Tube Heat Exchangers Using the Latent j Factor  

Energy Technology Data Exchange (ETDEWEB)

Condensate flow rate is an important factor in designing dehumidifiers or evaporators. In this paper, the latentj fimtor is used to analyze the dehumidification performance of two plate-fin tube heat exchangers. This latent j factor, analogous to the total j factor, is a flmction of the mass transfa coefllcient, the volumetric air flow rate, and the Schmidt number. This latent j factor did predict condensate flow rate more directly and accurately than any other sensiblej factor method. The Iatentj factor has been used in the present study because the sensible j factor correlations presented in the literature failed to predict the condensate flow rate at high Reynolds numbers. Results show that the latent j i%ctor em be simply correlated as a fhnction of the Reynolds number based on the tube outside diameter and number of rows of the heat exchanger.

Baxter, V.D.; Chen, D.T.; Conklin, J.C.

1999-03-15

150

Heat exchange during natural circulation and laminar flow of a liquid in vertical and inclined tubes  

International Nuclear Information System (INIS)

[en] Paper presents the results of investigation into effect of inclination angle on heat transfer during natural circulation and liquid laminar flow in vertical and inclined heated tubes. One has revealed the maximum of heat transfer at 15-45o angles of deflection from the vertical. Paper presents explanation of the mentioned phenomenon[ru] ?????????? ?????????? ???????????? ??????? ???? ??????? ?? ??????????? ??? ???????????? ?????????? ? ?????????? ??????? ???????? ? ???????????? ? ????????? ???????????? ??????. ??????? ???????? ??????????? ??? ????? ?????????? ?? ????????? 15-45 ????. ?????????? ?????????? ????? ???????

2006-01-01

151

Heat exchange apparatus  

International Nuclear Information System (INIS)

The present invention relates to heat exchangers used for transferring heat from the gas cooled core of a nuclear reactor to a secondary medium during standby and emergency conditions. The construction of the heat exchanger described is such that there is a minimum of welds exposed to the reactor coolant, the parasitic heat loss during normal operation of the reactor is minimized and the welds and heat transfer tubes are easily inspectable. (UK).

1979-01-01

152

Damping of heat exchanger tubes  

International Nuclear Information System (INIS)

Damping information is required for flow-induced vibration analyses of heat exchangers. There are several possible energy dissipation mechanisms that contribute to overall tube damping, including structural damping, friction damping, tube-to-fluid viscous damping and squeeze-film damping. These mechanisms and their relative contribution to overall tube damping are discussed. The approach is to identify the more important energy dissipation mechanisms and to formulate them in terms of heat exchanger tube parameters. This will give the designer a method to evaluate overall tube damping. The results of recent measurements on a simple two-span heat exchanger tube, on tube bundles in two-phase cross-flow, and on real heat exchangers in the field are disscussed

1985-01-01

153

Compact cryocooler heat exchangers  

International Nuclear Information System (INIS)

Compact heat exchangers are subject to different constraints as a room temperature gas is cooled down by a cold stream returning from a JT valve (or a similar cryoprocess component). In particular, the optimization of exchangers for liquid helium systems has to cover a wide range in temperature and density of the fluid. In the present work we address the following thermodynamic questions: 1. The optimization of intermediate temperatures which optimize stage operation (a stage is assumed to have a constant cross section); 2. The optimum temperature difference available for best overall economic performance values. The results are viewed in the context of porous media concepts applied to rather low speeds of fluid flow in narrow passages. In this paper examples of fluid/solid constraints imposed in this non-classical low temperature area are presented

1991-01-01

154

Optimization of Heat Exchangers  

Energy Technology Data Exchange (ETDEWEB)

The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics )pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger disign.

Ivan Catton

2010-10-01

155

Distribution of air-water R134a in a header of a parallel flow heat exchanger  

International Nuclear Information System (INIS)

Flow distribution in a header of a parallel flow heat exchanger was experimentally investigated using R-134a. Both downward and upward flow configuration were tested with tubes protruded to the center of the header. For the test range, the flow pattern at the inlet of the header was identified as stratified flow. It was observed that, for the downward flow, most of the liquid was extracted from the frontal part of the header. For the upward flow, however, most of the liquid was extracted from the rear part of the header. For the downward configuration, better distribution was obtained at a low mass flux and at a low quality. For the upward configuration, however, the mass flux or quality had minor influence on the flow distribution

2005-01-01

156

Liquid droplet heat exchanger studies  

International Nuclear Information System (INIS)

Recent analytical and experimental investigations of the liquid droplet heat exchanger (LDHX) concept for space power applications are described. The performance of the LDHX is compared to that of a conventional heat exchanger for heat rejection applications in a Brayton cycle, using the mass-specific heat exchanger effectiveness as a figure of merit. It is shown that the LDHX has an order of magnitude advantage over the conventional heat exchanger. Furthermore, significant improvement in cycle efficiency and power to mass ratio is possible. Two-phase flow experiments in a laboratory scale LDHX, using air and water as the two media, show very good agreement with the quasi-one-dimensional model used in the parametric studies. 9 references.

1987-01-01

157

Analytical Entropy Analysis of Recuperative Heat Exchangers  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract: The analytical solutions for the temperature variation of two streams in parallel flow, counter flow and cross-flow heat exchangers and related entropy generation due to heat exchange between the streams are presented. The analysis of limiting cases for the relative entropy generation is performed, and corresponding analytical expressions are given. The obtained results may be included in a more general procedure concerning optimal heat exchanger design.

Antun Galovic; Zdravko Virag; Marija Zivic

2003-01-01

158

Experimental and numerical study of mixed convection with flow reversal in coaxial double-duct heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Velocity vectors in a vertical coaxial double-duct heat exchanger for parallel ascending flow of water under conditions of laminar mixed convection have been determined experimentally using the particle image velocimetry technique. The measured velocity distributions for large annular flow rates, resulting in an essentially isothermal environment for the stream in the inner tube, are in very good agreement with corresponding numerical predictions. For flow rates of the same order of magnitude in the inner tube and the annulus, and corresponding temperature differences of about 20 C, experimental observations show that flow reversal occurs simultaneously in both streams over large axial distances for both heating and cooling of the flow in the inner tube. (author)

Mare, Thierry; Voicu, Ionut; Miriel, Jacques [Laboratoire de Genie Civil et de Genie Mecanique (LGCGM), INSA de Rennes, IUT Saint Malo, 35043 Rennes (France); Galanis, Nicolas [Faculte de genie, Universite de Sherbrooke, Sherbrooke, QC (Canada); Sow, Ousmane [Laboratoire d' Energie Appliquee, Ecole superieure Polytechnique, Dakar (Senegal)

2008-04-15

159

Analytical Entropy Analysis of Recuperative Heat Exchangers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract: The analytical solutions for the temperature variation of two streams in parallel flow, counter flow and cross-flow heat exchangers and related entropy generation due to heat exchange between the streams are presented. The analysis of limiting cases for the relative entropy generation is p...

Antun Galovic; Zdravko Virag; Marija Zivic

160

Active microchannel heat exchanger  

Science.gov (United States)

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

2001-01-01

 
 
 
 
161

Advanced heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This brief article describes the concept of compact heat exchangers and the advantages both financially and in improved energy efficiency terms associated with their utilisation. Examples including the highly novel printed circuit heat exchanger are given of several successful applications in process industry based on projects from the UK's research and demonstration programmes on energy efficiency. (UK)

Mercer, A. (Energy Technology Support Unit, Harwell (United Kingdom))

1994-03-01

162

Nuclear heat exchangers  

International Nuclear Information System (INIS)

[en] This paper presents general design features and characteristics of nuclear heat exchangers including nuclear steam generators. In particular, the heat exchangers in the pressurized light or heavy water reactor and the liquid metal fast breeder reactor plants, and their thermal and hydraulic characteristics are discussed in detail

1988-01-01

163

Flow-induced vibration specifications for steam generators and liquid heat exchangers  

International Nuclear Information System (INIS)

It is desirable to avoid vibration problems by following appropriate guidelines and specifications at the design stage. Accordingly, design specifications were developed to prevent tube failures due to vibration in nuclear steam generators and liquid heat exchangers. These specifications are outlined in this report. (author). 14 refs., 2 figs.

1995-01-01

164

An experimental analysis of the flow pattern in heat exchangers with an egg carton configuration (parallel, convergent and divergent cases)  

International Nuclear Information System (INIS)

[en] An experimental analysis about the flow patterns that appear in the channel formed between two corrugated plates with an egg carton configuration is reported. The types of flow instabilities caused by the corrugated plates are identified and described by means of flow visualization experiments, and photographic sequences illustrate the flow features present for each case. The influence on flow instabilities of Reynolds number, phase angle, convergence/divergence angle and spacing between corrugated plates is investigated. The corrugated plates are set divergent and convergent in order to investigate if recirculations are broken by chaotic advection. The improvement of heat transfer in the laminar regime has become an essential task in many applications and therefore the experiments are conducted in this regime. The corrugated plates geometry provides two main advantages over the conventional plane plates: the recirculation zones observed in the longitudinal direction and the three-dimensionality of the flow, i.e. the recirculations reduce the thermal resistances while the three-dimensionality of flow generates a better mixing and a more uniform temperature distribution. This experimental study contributes to the general knowledge on the subject being the first that addresses the analysis of convergent and divergent egg carton plates. It is expected that the results presented here will shed some light as to advantageously use these geometries in the near-future heat exchangers. (Because of the improve chaotic mixing in divergent corrugated plates, this configuration may be a good option to improve heat exchangers performance, because a better mixing is always related to the presence of core fluid near exchange surfaces, and consequently an increase in temperature gradients and heat transfer.)

2009-01-01

165

EDP assisted computation of cross-flow plate heat exchangers. EDV-unterstuetzte Berechnung von Kreuzstrom-Platten-Waermeaustauschern  

Energy Technology Data Exchange (ETDEWEB)

A new computation method for cross-flow plate heat exchangers is presented. The EDP assisted computation by means of 'finite elements' permits depiction of the effective tmeperature curve of both air flows. It is thus possible to compute the effective performance data that applies during practical use. The reheat coefficient during condensation can be computed on the basis of this temperature curve and the outlet conditions of the volumetric flows 1 and 2 can be precisely shown. A comparison of the computation method with the measuring results shows that these correspond well. (orig.).

Ammann, J.

1991-10-01

166

A study of heat and fluid flow phenomena on the gas side of circular-tube plate-fin heat exchangers  

Science.gov (United States)

The heat transfer and pressure drop characteristics of a circular-tube, plate-fin heat exchanger geometry were investigated. These parameters, expressed as the Colburn J factor and a friction factor f, are presented for Reynolds numbers from 100 to 3200, for exchanger samples with 1, 2 and 4 tube rows and 8, 10 and 12 fins per inch. These results are presented graphically and as a mathematical predictor model. The Taylor first order expansion and a Monte-Carlo numerical simulation of data were used to estimate the uncertainty in the values of J and f due to instrument discretization and random error. Comparisons with earlier work by other authors using simplified equations were undertaken. Dye-streak flow visualization was undertaken to study the flow field in four times scale models of circular-tube exchanger geometries with louvred and un-louvred plate-fins. Local heat transfer coefficients were obtained for the plain exchanger using a phase change paint in a transient condition. Correlations between the flow field and local heat transfer coefficient distribution were identified on the plain geometry and used to estimate the trends in heat transfer coefficient distribution for a louvred geometry. Numerical prediction of the flow fields present in a three dimensional plain circular-tube, plate-fin exchanger geometry, and two designs of multi-fin louvre bank were undertaken using the PHOENICS 81 code. Comparisons of predicted flow fields and experimental flow visualization showed good qualitative agreement. The development and manufacture of the various rigs, tools, and techniques used in the investigation are described.

Baldwin, Stephen

167

Fouling analyses for heat exchangers of NPP  

International Nuclear Information System (INIS)

Fouling of heat exchanges is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. This fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. In order to analyze the fouling for heat exchangers of nuclear power plant, the fouling factor is introduced based on the ASME O and M codes and TEMA standards. This paper focuses on the fouling analyses for the heat exchangers of several primary systems; the RHR heat exchanger of the residual heat removal system, the letdown heat exchanger of the chemical and volume control system, and the CCW heat exchanger of the component cooling water system, Based on the results of the fouling levels for the three heat exchangers are assumed.

2000-01-01

168

Cyclone heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The study discusses cyclones situated in a preheater tower above a cement kiln. This preheater insures the thermal preparation of the material by a conter-flow heat exchange between the stream of cold material descending towards the kiln and the hot gaz drawn up towards the top of the tower by fans. The purpose is to reduce the energy consumption in the preheater tower. Energy can be saved by diminishing the power consumed by fans and by a better use of the heat brought by the gas. The efficiency of the thermal exchange is affected by the separation efficiency of the cyclones. However there is a lack of information about internal working parameters of these separators (separation efficiency, pressure drop, retention time of the material in the cyclones, etc...) since a suitable method of investigation was not available. An experimental method has been perfected, using radioactive tracers in order to investigate these parameters. A computer programme has been designed and evaluated by the experimental data. This programme has been used to optimise the cyclone geometry for a better separation efficiency and a lower pressure drop. An economic assessment shows that the profit is too small to justify alteration of a plant already working. But improvement of cyclones geometry shape with the help of the computer programme can be considered for future fittings.

Margrita, M.; Santos Cottin, M.; Pailhes, M.

1984-01-01

169

Tertiary heat exchanger  

International Nuclear Information System (INIS)

The invention deals with the improvement of a tertiary heat exchanger possessing a contact medium besides a heating and working medium. These kind of heat exchangers are used in sodium-cooled nuclear power plants. The contact medium used so far should be reploced by a metal granulate which is used in porous bulk of single grains of varying size. It is advantageous to use copper as granulate. (RW).

1977-01-01

170

Thermoelectric heat exchange element  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-08-14

171

CtFD-based correlations for the thermal-hydraulics of an HTS current lead meander-flow heat exchanger in turbulent flow  

Science.gov (United States)

The Karlsruhe Institute of Technology is responsible for the design, construction and testing of the high temperature superconductor (HTS) current leads for the Wendelstein 7-X stellarator and for the JT-60SA tokamak. These HTS current leads mount a heat exchanger of the meander-flow type, in which the helium flows between the fins and is forced to cross flow with respect to the central Cu bar, which actually carries the current. Since an important issue in the operation of the HTS current lead is the optimization of the cooling power consumption, the helium thermal-hydraulics in such complex geometry becomes rather important.In this paper we extend a computational thermal fluid dynamics (CtFD) technique, previously introduced by the same authors and validated on short samples of meander flow heat exchanger and on the W7-X HTS current lead prototype, to a systematic analysis of the helium thermal-fluid dynamics inside different meander flow geometries. The first aim is to clarify under what operative conditions the flow regime can be considered turbulent and how the pressure drop as well as the heat transfer are related to the geometrical parameters and to the flow conditions. From the results of this analysis, correlations for the pressure drop and the heat transfer in the meander flow geometry have also been derived, which are applicable with good accuracy for the design of HXs over a broad range of geometries.

Rizzo, Enrico; Heller, Reinhard; Richard, Laura Savoldi; Zanino, Roberto

2013-01-01

172

Heat exchanger apparatus  

Energy Technology Data Exchange (ETDEWEB)

A vapor component of a gas mixture is separated by condensation and is recovered for further use. A solvent vapor mixed with inert gas is condensed in a multistage heat exchange system in a manner which utilizes a first refrigerant to condense a portion of the vapor in a first heat exchange device, a second refrigerant, typically cold inert gas, for condensing a further portion of the vapor in a second heat exchanger and a third heat exchange device wherein the liquid phase of the inert gas (i.e. cryogenic liquid) is supplied to provide a source of refrigeration. In this latter heat exchange device, the cryogenic liquid is introduced into a body of condensed vapor thereby chilling such condensed vapor and stirring the same to avoid freezing. Chilled, condensed vapor is removed from the latter heat exchange device and is returned as a reflux thereto to condense the vapor component of the gaseous mixture supplied thereto. A further portion of the chilled, condensed vapor is recirculated to the body of condensed vapor to assist the stirring of this body to avoid freezing of condensed vapor which is collected from the above heat exchange devices and is passed to a suitable storage facility.

Banerjee, R.

1984-04-24

173

Plate-Type Heat Exchanger  

International Science & Technology Center (ISTC)

Conduction of Experimental Studies of Heat Exchange Element of Plate-Type Heat Exchanger Aiming at Enhancement of its Effectiveness Owing to Design Improvement and Optimization of Used Heat Exchange Intensifiers

174

Heat exchanger design handbook  

CERN Multimedia

Completely revised and updated to reflect current advances in heat exchanger technology, Heat Exchanger Design Handbook, Second Edition includes enhanced figures and thermal effectiveness charts, tables, new chapter, and additional topics--all while keeping the qualities that made the first edition a centerpiece of information for practicing engineers, research, engineers, academicians, designers, and manufacturers involved in heat exchange between two or more fluids.See What's New in the Second Edition: Updated information on pressure vessel codes, manufacturer's association standards A new c

Thulukkanam, Kuppan

2013-01-01

175

Maintenance of heat exchangers  

International Nuclear Information System (INIS)

A brief overview of failure indication, repair and maintenance methods of heat exchangers in nuclear power plants is presented. Two major techniques are applied for detecting failure in the heat exchanger: leak testing, erosion and wear inspection. Various water chemistry methods are shown for leakage identification. General repair methods depending on the type of failure are summarized, and some novel techniques are proposed. Thermal calculations are shown to be a useful method for heat exchanger maintenance and failure prevention. (R.P.) 2 figs.; 1 tab

1990-01-01

176

Effect of geometry and flow conditions on particulates fouling plate heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This article describes particulate fouling experiments performed on small-scale and full-scale plate heat exchangers for three different corrugation angles (30{degree}, 45{degree}, and 60{degree}). The velocity effect has been studied as well as the particle type and concentration effects. The rest duration ranges between 20 and 1,500 h in order to reach asymptotic behavior. The results clearly indicate that the corrugation angle has a major influence on the asymptotic fouling resistance, Increasing the corrugation angle leads to lower values for the fouling resistance. Increasing the corrugation angle leads to lower values for the fouling resistance. Furthermore, for a given corrugation angle, the asymptotic fouling resistance is inversely proportional to the velocity squared. Finally, the asymptotic fouling resistance is proportional to the particle concentration. Fouling mitigation can be obtained by taking into account at the design stage the heat exchanger geometry and fluid velocity.

Thonon, B.; Grandgeorge, S.; Jallut, C.

1999-09-01

177

Shell side numerical analysis of a shell and tube heat exchanger considering the effects of baffle inclination angle on fluid flow using CFD  

Directory of Open Access Journals (Sweden)

Full Text Available In this present study, attempts were made to investigate the impacts of various baffle inclination angles on fluid flow and the heat transfer characteristics of a shell-and-tube heat exchanger for three different baffle inclination angles namely 0°,10° and 20°. The simulation results for various shell and tube heat exchangers, one with segmental baffles perpendicular to fluid flow and two with segmental baffles inclined to the direction of fluid flow are compared for their performance. The shell side design has been investigated numerically by modeling a small shell-and-tube heat exchanger. The study is concerned with a single shell and single side pass parallel flow heat exchanger. The flow and temperature fields inside the shell are studied using non-commercial CFD software tool ANSYS CFX 12.1. For a given baffle cut of 36 %, the heat exchanger performance is investigated by varying mass flow rate and baffle inclination angle. From the CFD simulation results, the shell side outlet temperature, pressure drop, recirculation near the baffles, optimal mass flow rate and the optimum baffle inclination angle for the given heat exchanger geometry are determined.

Raj Karuppa Thundil R.; Ganne Srikanth

2012-01-01

178

Tubular heat exchangers. Rohrbuendel-Waermeaustauscher  

Energy Technology Data Exchange (ETDEWEB)

Depending on the field of application or on the use of the medium, heat exchangers which work according to the principle of counterflow, parallel flow or cross-flow are used in the area of heating technology, in service water heating or cooling systems. Heat exchangers with hair pin tube bundles, as two plate device, or with electric insert, water vapor generators and tube-in-tube heat exchangers are differentiated. Structure and mode of operation of tubular heat exchangers are explained with reference to the regulations. Compared to plate heat exchanges it shows that plate heat exchangers are more compact and that due to the embossed plates high velocities and turbulances can be produced in the narrow water pipes but this has the disadvantage that they are sensitive to pressure shock and soiling. (BWI).

Laeng, H. (Markom AG, Zurich (Switzerland))

1991-03-01

179

Vertical heat exchanger  

International Nuclear Information System (INIS)

The design is described in detail of a vertical heat exchanger with two separate vertical capillary tube bundles and with heating steam condensation in the inter-tube space of the tube bundles. The design features a number of advantages, such as: the heat exchanger allows the supply of condensate from a higher heating degree; the inner structure separates the top and the bottom tube bundles thus preventing the condensate from running down to the bottom bundle; the inner structure and the jacket form the inlet steam chamber from which the heating steam is evenly distributed to both tube bundles; the assembly of the heat exchanger is easy because the inner structure is welded in the jacket as a whole and the tube bundles are inserted from both sides. It is also advantageous that the condensate produced on the individual bundles can be separated and the condensate level in the collector can be controlled in service and discharged from the heat exchanger through the discharge pipe. The heat exchanger is usable for both conventional and nuclear power generation. (A.K.). 3 figs

1983-08-31

180

Spiraflow heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Although different in their design and mode of functioning Spiraflow heat exchangers combine the positive properties of other systems. They consist of several corrugated-surface tubes which being of the coaxially telescoping type are forming annular ducts for the counterflow heating or cooling of the media they carry. With the widths of apertures, the resistances and heat transmission changing as the tubes are twisted Spiraflow heat exchangers can be adapted to any process the most optimum way possible. Access is given to different types such as 1) the Spiraflow Multichannel with 4 to 8 coaxial ducts, 2) the Spiraflow Monochannel with three annular ducts, 3) the Spiraflow Multitube consisting of several tubes sheathed by one, and 4) the Spiraflow Monotube consisting of one sheathed tube. The paper concludes with describing the heat exchanger's advantages and practical uses.

1988-02-01

 
 
 
 
181

Heat exchanging with slowly rotating finned elements  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanging apparatus is described comprising, substantially parallel heat transfer elements each having a longitudinal axis in a plane perpendicular to the normal direction of fluid therethrough; a source of a fluid having lint particles and moving in a flow direction; means for supporting the heat transfer elements for intercepting the moving fluid for heat exchange in the flow direction having a major component substantially perpendicular to the plane; the fluid having lint particles which if allowed to accumulate would clog the heat exchanging apparatus and obstruct the flow of the fluid; each heat transfer element having fin means extending radially outward from an element longitudinal axis for increasing the heat transfer between the fluid and each heat transfer element; means for rotatably supporting each of the heat transfer elements; means for producing fluid flow; and means for slowly continuously rotating the heat transfer elements.

Deck, B.D.

1987-04-28

182

Heat exchanger for automobiles. Waermetauscher fuer Kraftfahrzeuge  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger for automobiles with inlet and outlet openings for the heat transfer medium and cooling air passages has improved in a way that the cooling medium flows from the inlet to the outlet in a way that the covered zone is at the same time the coolest part of the heat exchange surface.

Schmehl, T.; Breuer, N.

1992-10-22

183

Corrosion protected reversing heat exchanger  

International Nuclear Information System (INIS)

A reversing heat exchanger of the plate and fin type having multiple aluminum parting sheets in a stacked arrangement with corrugated fins separating the sheets to form multiple flow paths, means for closing the ends of the sheets, an input manifold arrangement of headers for the warm end of of the exchanger and an output manifold arrangement for the cold end of the exchanger with the input air feed stream header and the waste gas exhaust header having an alloy of zinc and aluminum coated on the inside surface for providing corrosion protection to the stack

1984-01-01

184

Corrosion protected reversing heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A reversing heat exchanger of the plate and fin type having multiple aluminum parting sheets in a stacked arrangement with corrugated fins separating the sheets to form multiple flow paths, means for closing the ends of the sheets, an input manifold arrangement of headers for the warm end of of the exchanger and an output manifold arrangement for the cold end of the exchanger with the input air feed stream header and the waste gas exhaust header having an alloy of zinc and aluminum coated on the inside surface for providing corrosion protection to the stack.

Zawierucha, R.

1984-09-25

185

Testing and analysis of immersed heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The objectives were to determine the performance of four immersed, ''supply-side'' heat exchangers used in solar domestic-hot-water systems; to examine the effects of flow rate, temperature difference, and coil configuration on performance; and to develop a simple model to predict the performance of immersed heat exchangers. We tested four immersed heat exchangers: a smooth coil, a finned spiral, a single-wall bayonet, and a double-wall bayonet. We developed two analyticl models and a simple finite difference model. We experimentally verified that the performance of these heat exchangers depends on the flow rate through them; we also showed that the temperature difference between the heat exchanger's inlet and the storage tank can strongly affect a heat exchanger's performance. We also compared the effects of the heat exchanger's configuration and correlated Nusselt and Rayleigh numbers for each heat exchanger tested. The smooth coil had a higher effectiveness than the others, while the double-wall bayonet had a very low effectiveness. We still do not know the long-term effectiveness of heat exchangers regarding scale accumulation, nor do we know the effects of very low flow rates on a heat exchanger's performance.

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

1986-08-01

186

The right exchange[Plate heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This article focuses on recent developments in plate heat exchangers which will increase the users choice in the industrial, chemical, petrochemical and refrigeration markets. Gasketed plate heat exchangers and their advantages and limitations are described, and components of the gasketed plate heat exchangers, a typical plate, and a typical gasket/plate assembly section are illustrated. The advantages of using welded pair gasketed plate heat exchangers in terms of flexibility, construction, and operation are discussed along with the combination of welded pairs and PTFE (polytetrafluoroethylene) lined rings for allowing the use of plate heat exchangers for solvents, acids and hydrocarbons.

Kumar, H. [APV Heat Exchanger Product Group (United States)

1999-09-01

187

Chapter 11. Heat Exchangers  

Energy Technology Data Exchange (ETDEWEB)

Most geothermal fluids, because of their elevated temperature, contain a variety of dissolved chemicals. These chemicals are frequently corrosive toward standard materials of construction. As a result, it is advisable in most cases to isolate the geothermal fluid from the process to which heat is being transferred. The task of heat transfer from the geothermal fluid to a closed process loop is most often handled by a plate heat exchanger. The two most common types used in geothermal applications are: bolted and brazed. For smaller systems, in geothermal resource areas of a specific character, downhole heat exchangers (DHEs) provide a unique means of heat extraction. These devices eliminate the requirement for physical removal of fluid from the well. For this reason, DHE-based systems avoid entirely the environmental and practical problems associated with fluid disposal. Shell and tube heat exchangers play only a minor role in low-temperature, direct-use systems. These units have been in common use in industrial applications for many years and, as a result, are well understood. For these reasons, shell and tube heat exchangers will not be covered in this chapter.

Rafferty, Kevin D.; Culver, Gene

1998-01-01

188

Food Processing Vat With Heat Exchangers  

UK PubMed Central (United Kingdom)

A food processing vat is provided with a zoned heat transfer system that includes a heat exchanger with a baffle that extends between a pair of spaced apart sheets. The baffle directs a flow of a heat transfer fluid through a void space between the sheets of the heat exchanger. The heat exchanger may also include multiple spaced apart posts that extend through the heat exchanger and around which the heat transfer fluid can flow. The posts and/or baffle may be defined by welded points of joinder between the sheets, and the sheets may be inflated to provide the space therebetween, such that the posts and/or baffles extend as webs of material that connect the sheets of the heat exchanger.

ISENBERG TIMOTHY J; ZIRBEL JOHN E

189

Food processing vat with heat exchangers  

UK PubMed Central (United Kingdom)

A food processing vat is provided with a zoned heat transfer system that includes a heat exchanger with a baffle that extends between a pair of spaced apart sheets. The baffle directs a flow of a heat transfer fluid through a void space between the sheets of the heat exchanger. The heat exchanger may also include multiple spaced apart posts that extend through the heat exchanger and around which the heat transfer fluid can flow. The posts and/or baffle may be defined by welded points of joinder between the sheets, and the sheets may be inflated to provide the space therebetween, such that the posts and/or baffles extend as webs of material that connect the sheets of the heat exchanger.

ISENBERG TIMOTHY J; ZIRBEL JOHN E

190

Fouling analyses of heat exchangers for PSR  

International Nuclear Information System (INIS)

Fouling of heat exchangers is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. This fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. This paper focuses on fouling analyses for six heat exchangers of two primary systems in two nuclear power plants; the regenerative heat exchangers of the chemical and volume control system and the component cooling water heat exchangers of the component cooling water system. To analyze the fouling for heat exchangers, fouling factor was introduced based on the ASME O and M codes and TEMA standards. Based on the results of the fouling analyses, the present thermal performances and fouling levels for the six heat exchangers were predicted.

2003-01-01

191

Scraped surface heat exchangers.  

Science.gov (United States)

Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs. PMID:16527753

Rao, Chetan S; Hartel, Richard W

2006-01-01

192

Guide to compact heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This Good Practice Guide is concerned with compact heat exchangers and their application in the UK process industries. The overall objective is to increase awareness of compact heat exchangers within industry. Its specific aims are to provide information on: the available types of compact heat exchangers, the potential benefits of compact heat exchangers and the application of compact heat exchangers within the UK process industries. (author)

1994-01-01

193

The effect of flat bar supports on the cross flow induced response of heat exchanger U-tubes  

Energy Technology Data Exchange (ETDEWEB)

A wind tunnel study was conducted to determine the effect of flat bar supports on the cross-flow induced response of heat exchanger U-tubes. The 13 mm diameter tubes formed a triangular array with a pitch ratio o 1.57 and a mean U-bend diameter of about 1.5 m. A 0.3 m long section of the array was exposed to a flow parallel to the plane of the U-bends. Experiments were conducted with no supports, with 1 set of flat bars at the apex and with 2 sets of flat bar supports at the apex and 45/sup 0/ points. In each case, the tube response was monitored to a flow velocity beyond that required for fluid elastic instability. Limited experiments were also conducted to examine the effect of tube support clearance on tube response. Conclusions are drawn regarding the effectiveness of flat bars as U-bend antivibration supports.

Weaver, D.S.; Schneider, W.

1982-01-01

194

Thin film heat exchanger  

International Nuclear Information System (INIS)

[en] The description is given of a heat exchanger between a first 'hot' fluid and a second fluid to be heated, of the type comprising at least one heat exchange wall separating the fluids and through which heat is exchanged. The characteristic of this exchanger is that the wall which includes an upper end is a cyclindrical area of which the generating lines are vertical and the straight section is composed of a regular succession of undulations alternately marking peaks of convex waves and peaks of concave waves and that the exchanger includes facilities for introducing the second fluid in the upper end near the convex wave peaks of the face of the wall turned towards the second fluid[fr] On decrit un echangeur de chaleur entre un premier fluide dit 'chaud' et un deuxieme fluide a chauffer du type comportant au moins une paroi d'echange separant les fluides et a travers laquelle s'effectue un echange de calories. Il est caracterise en ce que la paroi qui comporte une extremite superieure est une surface cylindrique dont les generatrices sont verticales et dont la section droite est constituee par une succession reguliere d'ondulations definissant alternativement des sommets d'ondes convexes et des sommets d'ondes concaves, et en ce que l'echangeur comprend des moyens pour introduire le deuxieme fluide a l'extremite superieure au voisinage des sommets d'ondes convexes de la face de la paroi tournee vers le deuxieme fluide

1976-01-01

195

Study on direct mixing type axial flow cyclone heat exchanger between gas and particles. 1. Proposal and gas-particle separation performance  

Energy Technology Data Exchange (ETDEWEB)

A direct mixing type axial flow cyclone heat exchanger between gas and high temperature particles is proposed which serves as particle separator as well. The proposal was motivated by the concept of high temperature nuclear energy conversion system for which dense gas-solid suspension flow is considered as primary coolant. However, it may also be used as a general heat recovery device from various high temperature powdery waste material from conventional industry. In this heat exchanger, the particles, after being mixed directly with gas, transfer their heat to the gas in the form of quasi-counter-flow and are effectively re-separated by centrifugal force due to swirling motion of the gas. The mock-up of the heat exchanger was designed and constructed and its re-separation performance was examined both experimentally and numerically, which is the key to realize such innovative energy conversion systems. (author)

Yokomine, Takehiko; Shimizu, Akihiko; Nagafuchi, Tatsurou; Nakamura, Mitsuhiro [Kyushu Univ., Fukuoka (Japan)

1997-03-01

196

Study on direct mixing type axial flow cyclone heat exchanger between gas and particles. 1. Proposal and gas-particle separation performance  

International Nuclear Information System (INIS)

[en] A direct mixing type axial flow cyclone heat exchanger between gas and high temperature particles is proposed which serves as particle separator as well. The proposal was motivated by the concept of high temperature nuclear energy conversion system for which dense gas-solid suspension flow is considered as primary coolant. However, it may also be used as a general heat recovery device from various high temperature powdery waste material from conventional industry. In this heat exchanger, the particles, after being mixed directly with gas, transfer their heat to the gas in the form of quasi-counter-flow and are effectively re-separated by centrifugal force due to swirling motion of the gas. The mock-up of the heat exchanger was designed and constructed and its re-separation performance was examined both experimentally and numerically, which is the key to realize such innovative energy conversion systems. (author)

1997-01-01

197

Conquer heat exchanger fouling  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-01-01

198

Heat exchange panel  

Energy Technology Data Exchange (ETDEWEB)

A heat exchange panel having a desired system of internal tubular passageways is described, wherein the internal passageways include opposed headers connected by connecting portions of said passageways extending therebetween. The headers are designed to provide uniform fluid distribution and to enable efficient drainage of fluid from the unit, including any entrapped gases.

Kleine, C.A.; Middleton, V.L.

1980-11-25

199

Experimental evaluation of vibrations in heat exchangers  

International Nuclear Information System (INIS)

[en] Flow induced vibrations may produce damage of heat exchangers, condensers and steam generators tubes. To evaluate this problem a set of tests were developed to know the real support state of the tubes, which have great influence on the vibration response. This paper include a description of the tests and the results obtained applying them on a heat exchanger equipment. (author)

1997-01-01

200

Fireplace heat exchanger unit  

Energy Technology Data Exchange (ETDEWEB)

A fireplace heat exchanger unit including a forward section disposed outside of the fireplace and a rearward section disposed within the fireplace are described. The forward section provides upper air inlet openings for admitting cool air into an air inlet chamber and a pair of lower air outlet openings having electric blowers for discharging warmed air from air outlet chambers housing electric blowers. The rearward section is generally u-shaped and provides a duct connection between the inlet and outlet chambers. It is disposed about the heat source and the duct connection provides air heating chambers to warm the air during passage from the inlet to the outlet chambers.

Livesay, K.

1980-11-04

 
 
 
 
201

Dirty water heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger is described for use with a burner which produces hot gases and consists of: a cylindrical furnace duct having a first end connected to the burner for receipt of the hot gases and an open second end, the furnace duct defining a heater chamber therein; the furnace duct including a spiral liquid heating path surrounding at least a part of the heater chamber, the spiral path having a liquid inlet and a liquid outlet; an exhaust tube spaced apart from and surrounding at least a portion of the length of the furnace duct to define an exhaust gap therebetween, the exhaust trube having first and second ends, the second exhaust tube end being closed and surrounding the second furnace end to direct hot gases from the heater chamber, past the furnace duct second end and into the exhaust gap, the first exhaust tube end having an exhaust gas outlet, whereby the hot gases make a double pass and the heated liquid makes a single pass through the heat exchanger; means for mounting the furnace duct and the exhaust tube to one another, the mounting means securing the furnace duct to the exhaust tube at no more than one axial position to accommodate differential expansion between the furnace duct and the exhaust tube; a stationary mount secured to the first furnace duct end and a sliding support secured to the second exhaust tube end to accommodate differential axial expansion and contraction of the heat exchanger; and a slip joint mounting means allowing relative axial movement between the furnace duct and the exhaust tube, including radially oriented and axially extending spacer plates secured to one of the furnace duct and exhaust tube; and means for supporting the heat exchanger in a chosen position.

Urbani, W.G.

1986-04-29

202

Simulation of the heat exchange between the supersonic flow and the stationary body in a gas centrifuge  

Science.gov (United States)

We have made comparative calculations of the heat exchange in the subpersonic flow of gaseous UF6 around the stationary cylindrical body inside the rotating rotor of the gas centrifuge. It has been revealed that the integral heat flux from the gas to the body calculated with the use of the ANSYS-CFX program complex from the viewpoint of the continuum model is much smaller than the heat flow calculated by the Monte Carlo method of direct statistical simulation. Estimates show that under the conditions being considered the boundary layer on the surface of the body has no time to be formed and has a thickness of the order of the mean free path of the gas molecules and, therefore, the use of the methods of continuum mechanics in this region is incorrect. On the contrary, the method of direct statistical simulation permits taking into account the interaction of gas molecules directly with the surface of the streamline body and obtaining more correct results.

Zvonarev, K. V.; Seleznev, V. D.; Tokmantsev, V. I.; Abramov, Yu. V.

2012-11-01

203

Heat exchanger with transpired, highly porous fins  

Energy Technology Data Exchange (ETDEWEB)

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

204

The temperature and humidity in a low-flow anesthesia workstation with and without a heat and moisture exchanger.  

UK PubMed Central (United Kingdom)

BACKGROUND: The Dräger Primus anesthesia workstation has a built-in hotplate to heat the patient's exhaled gas. The fresh gas flow is mixed with the heated exhaled gas as they pass through the soda lime canister. A heat and moisture exchanger (HME) may also be used to further heat and humidify the inhaled gas. In this study we measured the temperature and humidity of the inhaled gas coming from the Dräger Primus with or without a HME. METHODS: Thirty female patients were randomly divided into 2 groups and their lungs ventilated by the Primus Dräger anesthesia workstation with or without a HME. The humidity and temperature of the inhaled gas were measured 15, 30, 60, 90, and 120 minutes after connecting the patient to the breathing circuit. RESULTS: After 120 minutes of ventilation with a low-flow breathing circuit, the temperatures of inhaled gas were 25°C ± 1°C and 30°C ± 2°C without and with HME, respectively, with a statistically significant difference between groups (P < 0.001) with 95% confidence interval (CI) of 3.80°C to 6.40°C; and the absolute humidity values of the inhaled gas were 20.5 ± 3.6 mgH(2)O · L(-1) and 30 ± 2 mgH(2)O · L(-1) without and with HME, respectively, with a statistically significant difference between groups (P < 0.001) with 95% CI of 7.37°C to 13.03°C. CONCLUSIONS: The Primus anesthesia workstation partially humidifies the inspired gas when a low fresh gas flow is used. Insertion of an HME increases the humidity in inhaled gas, bringing it close to physiological values.

de Castro J Jr; Bolfi F; de Carvalho LR; Braz JR

2011-09-01

205

Heat exchanger-accumulator  

Energy Technology Data Exchange (ETDEWEB)

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

Ecker, Amir L. (Dallas, TX)

1980-01-01

206

Fireplace heat exchanger assembly  

Energy Technology Data Exchange (ETDEWEB)

A fireplace heat exchanger assembly is claimed having a conduit that includes a first passage communicating with an air inlet located outwardly of a fireplace and extending rearwardly across the top of the fireplace, and a second passage communicating with the first passage at the rear of the fireplace and extending forwardly across the top of the fireplace for communication with an air outlet located outwardly of the fireplace. A blower introduces air into the air inlet, passes the air through the first and second passages, and discharges the air through the air outlet. More particularly, the conduit includes a heat exchanger box of relatively smaller height than width and length, the box being provided with laterally spaced and enclosed slots therethrough to provide the first passage between the slots, and to provide a pair of second passages laterally outward of the slots, the slots terminating in spaced relation to the rear of the box to place the first and second passages in communication. In one embodiment, the heat exchanger box has angularly related box portions through which the enclosed slots extend, so that the first and second passages are disposed at an angle to the vertical at the rear of the fireplace, and the transverse passage interconnects the first and second passages at the bottom, rear of the fireplace. Further, the conduit includes a duct frame disposed externally at the top and sides of the fireplace through which the first and second passages communicate respectively with the air inlet and air outlet.

Pauley, E. E.

1980-02-12

207

Experimental study of flow resistance for inclined tube bundles in the intermediate heat exchange of liquid metal reactor  

International Nuclear Information System (INIS)

An experimental study of measurement of pressure drop in an inclined tube bundle located in a rectangular duct is performed. The main emphasis of present study is placed on the derivation of pressure drop correlation applicable to the design of the intermediate heat exchanger in a liquid metal reactor as well as the general exchanger. An experimental facility that can measure the pressure drop in a tube bundle is designed, manufactured and installed, and the pressure drop is measured varying the flow rate and the test sections that have different inclined angles. Measurements are made for pressure drop in a triangular tube array of P/d=1.6 and inclination angles of 30, 45, 60 and 90 degrees. The Reynolds number based on the inlet free stream velocity and tube diameter ranges from 900 and 6.5 x 104. The experimental data show that the magnitude of dimensionless flow resistance increases with the increase of inclined tube angle. The measured data are compared with six previous correlations available in the literatures. The agreement with previous correlations is generally good except some discrepancies in a certain region. It is found that the experimental data obtained from present study can be applied to the evaluation and modification of previous correlations

2001-01-01

208

Heat exchanger applied to the farm-produce industry  

UK PubMed Central (United Kingdom)

The subject of the present invention is a heat exchanger for the exchange between a liquid and a (heating or refrigerating) heat-exchange fluid consisting of at least on enclosure in which heat-exchange elements are arranged. It is characterised by the fact that the said elements consist of embossed plates 1, 2 formed by the superposition of metal sheets between which the embossing creates flow tubes, a heat-exchange fluid flowing in each of the tubes of each of the plates, the liquid being made to flow along the exchange surfaces of the said plates 1, 2.

209

Heat exchanger fouling  

Energy Technology Data Exchange (ETDEWEB)

The phenomenon of fouling in heat exchangers were described, with specific reference to studies underway in the Department of Chemical Engineering at the University of British Columbia. Studies at UBC cover five different types of fouling, i. e., particulate fouling from suspension, crystallization fouling from solution, chemical reaction fouling by deposit formation at the heat transfer surface, corrosion fouling due to accumulation of corrosion products at the heat transfer surface, and biofouling due to attachment of microorganisms to the surface. The deposition process for all forms of fouling under study involves a transport step in series with deposit attachment to the surface. New models for the deposit attachment are under development. The fouling of organic streams under oxygenated and non-oxidative conditions is also under study, with special attention to asphaltenes in the fouling of crude oils.

Epstein, N.

1996-11-01

210

High power heat pipe heat exchanger development  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of a recently completed SBIR Phase 2 program by Thermacore, Inc. to develop a 350kW heat pipe radiator for the M109 A6 Howitzer engine cooling. After a brief discussion of operating principles and unique advantages of heat pipe heat exchangers, the paper focuses on the development of high power heat pipe heat exchangers. Design and manufacturing issues associated with high power heat pipe heat exchangers, such as non-uniform heat load distribution, redundancy/damage resistance, and seals between the two fluid streams, are addressed. Test results of segment and full scale heat pipe radiators are presented. Heat pipe heat exchanger applications, including the potential applications in the turbine industry and the food and pharmaceutical industry, are discussed.

Fale, J.E.; Zuo, Z.J.; Gernert, N.J.; Goryca, M.L.

1998-07-01

211

Numerical Simulation of Passive Residual Heat Removal Heat Exchanger  

International Nuclear Information System (INIS)

FLUENT software was employed to simulate the temperature-field and flow-field of AP1000 passive residual heat removal heat exchanger (PRHR HX), and investigate its heat-transferring and flow characteristics. Through comparative analysis of the distributions of temperature-field and flow-field in different locations at the same time, and the variations of temperature-field and flow-field in the same location at different time, heat-transferring process and natural convection situation of PRHR HX were understood deeply. It contributes to analyze the natural circulation capacity of PRHR HX, and provides some references for the effective operation of passive residual heat removal system. (authors)

2010-01-01

212

Triple loop heat exchanger for an absorption refrigeration system  

Energy Technology Data Exchange (ETDEWEB)

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

Reimann, Robert C. (Lafayette, NY)

1984-01-01

213

Transient thermal, hydraulic, and mechanical analysis of a counter flow offset strip fin intermediate heat exchanger using an effective porous media approach  

Science.gov (United States)

This work presents a comprehensive thermal hydraulic analysis of a compact heat exchanger using offset strip fins. The thermal hydraulics analysis in this work is followed by a finite element analysis (FEA) to predict the mechanical stresses experienced by an intermediate heat exchanger (IHX) during steady-state operation and selected flow transients. In particular, the scenario analyzed involves a gas-to-liquid IHX operating between high pressure helium and liquid or molten salt. In order to estimate the stresses in compact heat exchangers a comprehensive thermal and hydraulic analysis is needed. Compact heat exchangers require very small flow channels and fins to achieve high heat transfer rates and thermal effectiveness. However, studying such small features computationally contributes little to the understanding of component level phenomena and requires prohibitive computational effort using computational fluid dynamics (CFD). To address this issue, the analysis developed here uses an effective porous media (EPM) approach; this greatly reduces the computation time and produces results with the appropriate resolution [1]. This EPM fluid dynamics and heat transfer computational code has been named the Compact Heat Exchanger Explicit Thermal and Hydraulics (CHEETAH) code. CHEETAH solves for the two-dimensional steady-state and transient temperature and flow distributions in the IHX including the complicating effects of temperature-dependent fluid thermo-physical properties. Temperature- and pressure-dependent fluid properties are evaluated by CHEETAH and the thermal effectiveness of the IHX is also calculated. Furthermore, the temperature distribution can then be imported into a finite element analysis (FEA) code for mechanical stress analysis using the EPM methods developed earlier by the University of California, Berkeley, for global and local stress analysis [2]. These simulation tools will also allow the heat exchanger design to be improved through an iterative design process which will lead to a design with a reduced pressure drop, increased thermal effectiveness, and improved mechanical performance as it relates to creep deformation and transient thermal stresses.

Urquiza, Eugenio

214

A comparison between heat transfer correlations obtained from experimental data and numerical simulation of flow of stirred yoghurt during cooling in plate heat exchangers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thermal processing is widely used in the food industry mainly to improve quality and safety of food products. The investigation of heat transfer problems of non-Newtonian fluids during heating and cooling in heat exchangers is of major interest since the main factor limiting heat transfer is the vis...

Afonso, Isabel M.; Fernandes, Carla S.; Maia, João M.; Melo, Luis F.

215

Heat exchanger with antivibration structure  

International Nuclear Information System (INIS)

Flow induced vibration of heat exchanger U-tubes is minimised by the use of generally V-shaped antivibration bars inserted into the tube bundle at the U-shaped sections thereof, the bars inserted into alternate gaps between adjacent layers of tubes being staggered with respect to those inserted into the adjacent gaps. All of the antivibration bars are interference fits between the tube layers so as to elastically deflect the tubes thereby ensuring positive tube support at each intersection between the tubes and bars. (author).

1985-05-17

216

Heat exchanger for liquid metals  

International Nuclear Information System (INIS)

The heat exchanger is for liquid metals, such as sodium, whereby the secondary liquid metal is fed through parallel pipes in one or more pipe bundles, and wherein the pipes, between pipe plates or other assembly pieces, are introduced, and the primary liquid metal flows or circulates along the outside of the pipes, characterised by that the pipes of the pipe handles consist of molybdenum, tantalum or niobium, or alloys thereof, and the outside diameter lies between 6 and 16 mm at least. (G.C.)

1977-01-01

217

Appendix to the thesis an experimental and numerical study of a jetfire stop material and a new helical flow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

This thesis consists of two parts. Part 1: Experimental and numerical study of jetfire stop, and Part 2: Experimental and numerical study of a new kind of shell and tube heat exchanger with helical flow on shell side. Part 1 describes the development of the model for simulation of the temperature development through Viking jetfirestop. A simulation program is developed that calculates the temperature development through Viking jetfirestop. In the development of the model, measurements of reaction energy, pyrolysis and heat conductivity at low temperatures are made. The conductivity at higher temperatures and when pyrolysis reactions are going on is estimated experimentally and by numerical calculations. Full-scale jet fire test and small-scale xenon lamp experiments are made to test the simulation model. Part 2 contains the development of a model that simulate the fluid flow and heat transfer in a helical flow shell and tube heat exchanger. It consists of the development of a porosity model and a model for pressure drop and heat transfer as well as experiments in non-standard tube layouts. Results from the simulation program are compared with experiments on a helical flow shell and tube heat exchanger. This is a separate appendix volume, including computer codes and simulated results. 316 figs., 11 tabs.

Austegard, Anders

1997-12-31

218

Plate heat exchanger  

International Nuclear Information System (INIS)

In a plate heat exchanger required to handle corrosive, toxic or radioactive fluids, wherein each plate has a peripheral recess or like formation adapted for receiving an elastomeric gasket, the plates are welded together in pairs by the method comprising the steps of inserting into the gasket recess of a first plate of said pair a metal packing piece and welding the second place (e.g. by a laser or electron beam weld running along the base of the recess) superimposing a second plate on to the first in contact with the packing piece and welding the second plate to the packing piece (e.g. by a laser or electron beam weld). The packing piece may be of hollow or solid cross section and is preferably of the same material (e.g. titanium or stainless steel) as the plates. In use a service fluid in heat exchange with the said corrosive etc. fluid is confined by peripheral and normally elastomeric gaskets. (author)

1982-01-01

219

Tubular heat exchanger  

International Nuclear Information System (INIS)

[en] The invention concerns a heat exchanger of which the tubes, placed in a long casing, cross the casing cover in a sealed manner. These tubes are fixed to the tube plate forming this cover or to the branch tubes it comprises by means of compression joints. These joints make it possible to do away with welds that are sources of defects and to improve the operational safety of the apparatus. An advantageous form of the heat exchanger under the invention includes a manifold for each thermal exchange fluid, and one end of each tube is connected to this manifold by a pipe that is itself connected to the tube by a threaded connection. The latter provides for easy disconnection of the pipe in order to introduce a probe for inspecting the state of the tubes[fr] L'invention concerne un echangeur de chaleur dont les tubes, disposes dans une enveloppe allongee, traversent de facon etanche le couvercle de l'enveloppe. Ces tubes sont fixes a la plaque tubulaire constituant ledit couvercle, ou aux tubes de branchement qu'elle comporte, a l'aide de raccords a compression. Ces raccords permettent de supprimer les soudures qui constituent des sources de defauts et d'ameliorer la surete de fonctionnement de l'appareil. Une forme avantageuse de l'echangeur de chaleur suivant l'invention comprend un collecteur pour chaque fluide d'echange thermique, et une extremite de chaque tube est reliee a ce collecteur par un conduit lui-meme relie au tube par un raccord filete. Ce dernier permet un demontage aise du conduit pour l'introduction d'une sonde permettant de controler l'etat des tubes

1975-08-20

220

Computation of two-dimensional isothermal flow in shell-and-tube heat exchangers  

International Nuclear Information System (INIS)

A computational procedure is outlined whereby two-dimensional isothermal shell-side flow distributions can be calculated for tube bundles having arbitrary boundaries and flow blocking devices, such as sealing strips, defined in arbitrary locations. The procedure is described in some detail and several computed results are presented to illustrate the robustness and generality of the method

1983-01-01

 
 
 
 
221

Heat pump heating with ambient air heat exchanger. Waermepumpenheizung mit Umgebungsluft-Waermetauscher  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to develop a heat pump heating system with ambient air heat exchanger, so that the plates of the heat exchanger have parallel flow over them of moving ambient air, without any additional drive. According to the invention, this problem is solved by the plate register being able to rotate around a vertical axis like a weather vane, and by the absorption plates of the plate register setting themselves automatically parallel to the direction of flow of the ambient air. This leads to a considerable increase in the efficiency of the ambient air heat exchanger and therefore of the heat pump heating system at little expense. (HWJ).

Dietrich, B.; Kimpenhaus, W.

1984-04-12

222

Non-Newtonian flows in laminar regime in chevron plate heat exchangers: the influence of geometrical configuration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Physical processing brings about irreversible textural and sensorial properties of nearly all the fluids on the food industry. In liquid food processing, plate heat exchangers (PHEs) are commonly used in the heating or cooling stages due to their advantages, such as high efficiency, ease of maintena...

Fernandes, Carla S.; Dias, Ricardo P.; Nóbrega, João M.; Maia, João M.

223

Heat exchanger bypass test report  

International Nuclear Information System (INIS)

This test report documents the results that were obtained while conducting the test procedure which bypassed the heat exchangers in the HC-21C sludge stabilization process. The test was performed on November 15, 1994 using WHC-SD-CP-TC-031, ''Heat Exchanger Bypass Test Procedure.'' The primary objective of the test procedure was to determine if the heat exchangers were contributing to condensation of moisture in the off-gas line. This condensation was observed in the rotameters. Also, a secondary objective was to determine if temperatures at the rotameters would be too high and damage them or make them inaccurate without the heat exchangers in place

1995-01-01

224

Heat exchanger with auxiliary cooling system  

Energy Technology Data Exchange (ETDEWEB)

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

225

Tube bundle heat exchanger  

International Nuclear Information System (INIS)

The heat exchanger consists of tube bundles mounted in parallel. Each bundle consists of a jacket in which tubes for a first coolant are mounted. Straight tubes are connected with their open ends to tube plates which, in turn, are connected to the jacket provided with the inlet and outlet for a second coolant. This passes between the outer surfaces of straight tubes and the inner jacket surface. Spacers are inserted between the tube bundles, this along the whole length of the bundles. The second coolant enters one tube plate through the open ends of inlet tubes. It leaves through the other tube plate of the respective bundle, through the open ends of the outlet tubes. The other open ends of the inlet and/or outlet tubes are inserted in auxiliary tube plates mounted in the jacket on both sides of the tube bundles. (H.S.)

1980-01-01

226

Total counterflow heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A total counterflow heat exchanger is described comprising: a shell of generally cylindrical shape open at a first end and a second end; a first end cap at the first end of the interior chamber; a second end cap at the second end of the interior chamber opposing the first end cap and extending radially inward from the periphery of the interior chamber perpendicular to the surface of the cylindrical portion of the shell and connected thereto; a first partition having a first end edge, an opposing second end edge, and an outer longitudinal edge, a second partition having a first end edge, an opposing second end edge, an outer longitudinal edge, and an opposing inner longitudinal edge; a third partition having a first end edge, an opposing second end edge, an outer longitudinal edge and an opposing inner longitudinal edge, and a serpentine tube spatially situated within and extending through the serpentine channel.

Christianson, P.O.; Mc Donald, J.M.

1987-11-17

227

Damping and fluidelastic instability in two-phase cross-flow heat exchanger tube arrays  

Science.gov (United States)

An experimental study was conducted to investigate damping and fluidelastic instability in tube arrays subjected to two-phase cross-flow. The purpose of this research was to improve our understanding of these phenomena and how they are affected by void fraction and flow regime. The model tube bundle had 10 cantilevered tubes in a parallel-triangular configuration, with a pitch ratio of 1.49. The two-phase flow loop used in this research utilized Refrigerant 11 as the working fluid, which better models steam-water than air-water mixtures in terms of vapour-liquid mass ratio as well as permitting phase changes due to pressure fluctuations. The void fraction was measured using a gamma densitometer, introducing an improvement over the Homogeneous Equilibrium Model (HEM) in terms of void fraction, density and velocity predictions. Three different damping measurement methodologies were implemented and compared in order to obtain a more reliable damping estimate. The methods were the traditionally used half-power bandwidth, the logarithmic decrement and an exponential fitting to the tube decay response. The decay trace was obtained by "plucking" the monitored tube from outside the test section using a novel technique, in which a pair of electromagnets changed their polarity at the natural frequency of the tube to produce resonance. The experiments showed that the half-power bandwidth produces higher damping values than the other two methods. The primary difference between the methods is caused by tube frequency shifting, triggered by fluctuations in the added mass and coupling between the tubes, which depend on void fraction and flow regime. The exponential fitting proved to be the more consistent and reliable approach to estimating damping. In order to examine the relationship between the damping ratio and mass flux, the former was plotted as a function of void fraction and pitch mass flux in an iso-contour plot. The results showed that damping is not independent of mass flux, and its dependency is a function of void fraction. A dimensional analysis was carried out to investigate the relationship between damping and two-phase flow related parameters. As a result, the inclusion of surface tension in the form of the Capillary number appears to be useful when combined with the two-phase component of the damping ratio (interfacial damping). A strong dependence of damping on flow regime was observed when plotting the interfacial damping versus the void fraction, introducing an improvement over the previous result obtained by normalizing the two-phase damping, which does not exhibit this behaviour. The interfacial velocity model was selected to represent the fluidelastic data in two-phase experiments, due to the inclusion of the tube array geometry and density ratio effects, which does not exist for the pitch velocity approach. An essential component in reliably establishing the velocity threshold for fluidelastic instability, is a measure of the energy dissipation available in the system to balance the energy input from the flow. The present analysis argues that the damping in-flow is not an appropriate measure and demonstrates that the use of quiescent fluid damping provides a better measure of the energy dissipation, which produces a much more logical trend in the stability behaviour. This value of damping, combined with the RAD density and the interfacial velocity, collapses the available data well and provides the expected trend of two-phase flow stability data over the void fraction range from liquid to gas flows. The resulting stability maps represent a significant improvement over existing maps for predicting fluidelastic instability of tube bundles in two-phase flows. This result also tends to confirm the hypothesis that the basic mechanism of fluidelastic instability is the same for single and two-phase flows.

Moran, Joaquin E.

228

Gifford-McMahon/Joule-Thomson cryocooler with high-flow-conductance counterflow heat exchanger for use in resistance thermometer calibration  

Science.gov (United States)

A cryocooler that consists of a two-stage Gifford-McMahon (GM) mechanical refrigerator and a Joule-Thomson (JT) expansion circuit is developed for use in resistance thermometer calibration. The cryocooler is designed to attain a lower temperature rather than to produce a higher cooling power. A simple but high-performance counterflow heat exchanger is developed for the cryocooler. The heat exchanger has a high flow conductance while maintaining a high heat exchange efficiency. It is an improved type of counterflow heat exchanger composed of a spiral capillary and a thin-wall straight outer tube. The developed cryocooler uses a single counterflow heat exchanger not like a conventional GM/JT cryocooler, which usually has two or three counterflow heat exchangers. 4He is used as the working fluid for the JT expansion circuit. The pot where the condensed 4He collects after the JT expansion can reach 1.3 K in the continuous operation mode and 1.0 K in the single-cycle operation mode. The cooling power of the cryocooler is 580 ?W at 1.34 K with a molar flow rate of 300 ?mol/s. Temperature control of the pot was demonstrated from 1.4 to 12 K using two control methods. One method involves controlling the evacuation speed in the JT circuit and the other involves controlling the heat input from a heater to the pot. The temperature of the pot is controlled within the order of magnitude of 2 mK from peak to peak with either method.

Shimazaki, Takeshi; Toyoda, Keishi; Tamura, Osamu

2006-03-01

229

Controller apparatus and method for heat exchange system  

Energy Technology Data Exchange (ETDEWEB)

A controller for use with two or more heat exchange systems in which each system includes first and second heat exchangers, a working fluid circuit between the heat exchangers of each system and a working fluid in the circuit, is described comprising: (a) means manifolding together the outputs of the working fluid circuits for all of the first heat exchangers for all of the heat exchange systems and providing an input from the manifolding means to all of the second heat exchangers for all of the heat exchange systems; and (b) means for controlling the flow of the working fluid from each of the first heat exchangers dependent upon the average energy demand for all of the second heat exchangers.

Hayes, J.H.

1988-01-05

230

Vibration in nuclear heat exchangers due to liquid and two-phase flow  

International Nuclear Information System (INIS)

The relationships discussed are based on findings derived from a comprehensive vibration testing program which included both water and simulated two-phase (air-water) flow regimes. Tube bundles of various configurations and spacings were tested in crossflow using 3/4 in (1.9 cm) and 7/8 in. (2.2 cm) o.d. tubes with 36 in. (91 cm) span lengths and as many as 40 tubes per array. Sufficient test loop capacity was provided to drive most test array configurations up to and beyond fluid-elastic instability. Parameters obtained included displacement, effective force coefficients, damping coefficients, Strouhal numbers, and instability constants for various tube array configurations in both liquid and simulated two-phase flow mediums

1981-01-01

231

Rotor bore and turbine rotor wheel/spacer heat exchange flow circuit  

Energy Technology Data Exchange (ETDEWEB)

In a turbine having closed-circuit steam-cooling passages about the rim of the rotor during steady-state operation, compressor discharge air is supplied to the rotor bore for passage radially outwardly into the wheel space cavities between the wheels and spacers. Communicating slots and channels in the spacers and wheels at circumferentially spaced positions enable egress of the compressor discharge air into the hot gas flow path. At turbine startup, cooling air flows through the closed-circuit steam passages to cool the outer rim of the rotor while compressor discharge air pre-warms the wheels and spacers. At steady-state, cooling steam is supplied in the closed-circuit steam-cooling passages and compressor discharge air is supplied through the bore and into the wheel space cavities to cool the rotor.

Caruso, Philip M. (Selkirk, NY); Eldrid, Sacheverel Quentin (Saratoga Springs, NY); Ladhani, Azad A. (Niskayuna, NY); DeMania, Alan Richard (Niskayuna, NY); Palmer, Gene David (Clifton Park, NY); Wilson, Ian David (Clifton Park, NY); Rathbun, Lisa Shirley (Scotia, NY); Akin, Robert Craig (Schenectady, NY)

2002-01-01

232

Investigations on fluid borne forces in heat exchangers with tubes in cross flow  

International Nuclear Information System (INIS)

[en] An experimental device is described with which steady and unsteady flow forces acting on a tube and the mechanical response of the tube to these forces can be measured. At first a single tube in cross flow was investigated to prove the reliability of the test procedure. After that experiments with four in-line tube banks with pitches ranging from 1.15 to 2.88 tube diameters were performed. The aerodynamic forces and the tube vibrations were registered simultaneously. The measurements show that four kinds of exciting mechanisms exist. Tube vibrations are caused either by vortices, buffeting, galloping or fluid elastic coupling. The tests were performed in an atmospheric wind tunnel in a range of Reynolds number 104 5 (author)

1983-01-01

233

High efficiency furnace with secondary heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A domestic forced-air furnace provided with a condensate collector downstream of air moving structure for flowing the products of combustion through the furnace. The furnace includes a secondary heat exchanger. Condensate produced therein is transferred therefrom through the air moving structure to the condensate separator. The secondary heat exchanger and air moving structure are inclined slightly to the horizontal so as to cause continuous flow of condensate therethrough not only during operation of the furnace but also subsequent thereto to assure removal of condensate from the furnace components and thereby avoid corrosive damage thereto from the condensate. The secondary heat exchanger provides the primary pressure drop in the combustion product flow path, permitting control of the furnace capacity by simple modification thereof without the need for changing other components, such as the air moving structure.

Trent, B. O.; Tomlinson, R. S.

1985-09-24

234

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

CERN Multimedia

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

235

Method for removing coronene from heat exchangers  

International Nuclear Information System (INIS)

A method for removing a coronene deposit in a reforming process is described that consists of (A) contacting a hydrocarbonacous feedstock with a catalyst in the presence of added hydrogen at reforming conditions in a reforming zone; (B) splitting the total reforming zone effluent into a first stream and a second stream; (C) passing said first stream into a first train of heat exchangers arranged in parallel with a second train of heat exchangers; (D) passing said second stream into said second train of heat exchangers, said reforming zone effluent comprising coronene, at least a portion of which deposits in said heateexchangers; (E) separating the heat exchanged total reforming zone effluent into a hydrogen-rich gaseous phase and a liquid hydrocarbon phase comprising normally liquid hydrocarbons and normally gaseous hydrocarbons, the improvement which comprises reducing the flow of said first stream in said first train of heat exchangers to produce a temperature sufficient to condense at least a portion of said reformer effluent therein such that the resulting condensate contacts said coronene deposit, and simultaneously increasing the flow of said second stream in said second train of heat exchangers

1980-01-01

236

Random excitation of heat exchanger tubes by two-phase cross-flows  

International Nuclear Information System (INIS)

This paper reports the results of several experimental studies performed at CEA, which concern the random forces exerted on tube arrays subjected to two-phase cross-flows. A rather large data base was obtained in air-water at various void fractions. The data obtained in steam-water and freon refer to the high void fraction range which is typically that of PWR steam generators at nominal conditions. From this information an empirical correlation between the random forces exerted on the tubes and the homogeneous void fraction is derived which is found to hold over a large range of mass-flux. Furthermore the data referring to the distinct fluid mixtures explored here, are found to collapse reasonably well on the same correlation curve.

1992-01-01

237

Spiral-passage heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A spiral passage chemical converter-heat exchanger formed by a cross-sectional rectangular housing containing a pair of rows each containing a plurality of side-by-side passages is described. The rectangular housing is wound into a spiral with the innermost row forming inlet passages and the outermost row forming outlet passages. Thermal contact exists between inflow passages and outflow passages. The outer end of the spiral is connected with an inlet and an outlet. The inlet joins the innermost row of passages and the outlet joins the outermost row of passages. The inner end of the spiral is capped, with a common wall separating the upper and lower passages slotted so that fluid flows from the inlet passages to the outlet passages. As can be seen when the structure is in a spiral, the inlet passages are between the outlet passages with the outlet passages forming the outer exposed surface of the spiral and the inlet passages forming the surface of the opening through the spiral at the center. A concave sunlight reflector will focus sunlight into the central opening of the spiral thereby heating the fluid in the inlet passages. Since the outlet passages are separated by the inlet passages in the spiral and are in thermal contact therewith, the solar heated outlet fluid will heat the input fluid as it circles the spiral to the outlet passages.

Chubb, T.A.

1980-06-10

238

Modular heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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)

1981-01-01

239

Dynamic simulation of plate heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The dynamic response of a parallel plate heat exchanger to a step input of the hot fluid temperature is studied and evaluated. The temperature profiles along the channels and in the outlets are simulated by using a ``Cinematic Model``. The experimental and numerical results for both dynamic and steady-state temperature profiles are compared and a general computer program based on finite differences is introduced for all kinds of PHEs. The applied PHE is a 5-plate, 2-fluid, looped U-flow heat exchanger, in which the fluids in adjacent channels flow in a counter-current direction.

Sharifi, F.; Narandji, M.R.G.; Mehravaran, K. [Amir-Kabir Univ. of Technology, Tehran (Iran, Islamic Republic of)

1995-03-01

240

Air-sand heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

This paper summarizes research activities that analyse the thermodynamic behaviour of an Air / Sand Heat Exchanger, developed by Solar-Institut Juelich (SIJ) and the German Aerospace Centre (DLR). A numerical 3-D model, new results and a model validation of this particular cross-flow heat exchanger are presented. Simulation results were obtained for sand with 1-2 mm grain size. The simulation was validated with operational results of a new 15 kW prototype unit. Ansys, including Ansys-CFX, is used as modelling and simulation platform. The bulk material is modelled by a porous solid medium without structural dynamic interaction between fluid and solid phase. For pressure drop calculations, Ergun's model for bulk material is used. The model parameters were validated and fitted with measured values of a separate pressure drop test rig. The validation was done with quartz sand. To determine the suitability of available granular products for this application, tests have been conducted regarding the thermomechanical properties as well as their attrition behaviour and abrasion on various wall materials.

Baumann, Torsten; Zunft, Stefan [German Aerospace Center (DLR), Stuttgart (Germany); Boura, Cristiano; Eckstein, Julian; Felinks, Jan; Goettsche, Joachim; Hoffschmidt, Bernhard; Schmitz, Stefan [FH Aachen, Juelich (Germany). Solar-Inst. Juelich

2011-07-01

 
 
 
 
241

Microtube strip heat exchanger. Final technical report  

Energy Technology Data Exchange (ETDEWEB)

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

Doty, F.D.

1992-07-09

242

Compact heat exchanger optimization tools based on volume averaging theory  

Energy Technology Data Exchange (ETDEWEB)

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

243

Observer-based monitoring of heat exchangers.  

Science.gov (United States)

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

2007-08-15

244

Heat exchange methods and apparatus  

Energy Technology Data Exchange (ETDEWEB)

A vapor component of a gas mixture is separated by condensation and is recovered for further use. A solvent vapor mixed with inert gas is condensed in a multistage heat exchange system in a manner which utilizes a first refrigerant to condense a portion of the vapor in a first heat exchange device, a second refrigerant, typically cold inert gas, for condensing a further portion of the vapor in a second heat exchanger and a third heat exchange device wherein the liquid phase of the inert gas (i.e. cryogenic liquid) is supplied to provide a source of refrigeration. In this latter heat exchange device, the cryogenic liquid is introduced into a body of condensed vapor thereby chilling such condensed vapor and stirring the same to avoid freezing. Chilled, condensed vapor is removed from the latter heat exchange device and is returned as a reflux thereto to condense the vapor component of the gaseous mixture supplied thereto. A further portion of the chilled, condensed vapor is recirculated to the body of condensed vapor to assist the stirring of this body to avoid freezing of condensed vapor which is collected from the above heat exchange devices and is passed to a suitable storage facility.

Banerjee, R.

1985-11-12

245

Spiral-passage heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A spiral passage chemical converter-heat exchanger is formed by a cross-sectionally rectangular housing containing a pair of rows each containing a plurality of side-by-side passages. The rectangular housing is wound into a spiral with the innermost row forming inlet passages and the outermost row forming outlet passages. Thermal contact exists between inflow passages and outflow passages. The outer end of the spiral is connected with an inlet and an outlet. The inlet joins the innermost row of passages and the outlet joins the outermost row of passages. The inner end of the spiral is capped, with a common wall separating the upper and lower passages slotted so that fluid flows from the inlet passages to the outlet passages. As can be seen when the structure is in a spiral, the inlet passages are between the outlet passages with the outlet passages forming the outer exposed surface of the spiral and the inlet passages forming the surface of the opening through the spiral at the center. A concave sunlight reflector will focus sunlight into the central opening of the spiral thereby heating the fluid in the inlet passages. Since the outlet passages are separated by the inlet passages in the spiral and are in thermal contact therewith, the solar heated outlet fluid will heat the input fluid as it circles the spiral to the outlet passages. Thus, the outlet passages aid in heating the inlet fluid during passage to the inner end of the spiral. The inlet passages may contain a porous catalyst which is prevented from escaping by a suitable structure at each end of the inlet passages for dissociating a fluid for storage of heat for future use.

Chubb, T.A.

1980-06-10

246

Laser-heated heat-exchanger thruster  

Energy Technology Data Exchange (ETDEWEB)

A hydrogen-fuelled laser-heated thruster can produce a specific impulse of 500--800 seconds -- sufficient to reach Earth orbit with plausible single-stage mass ratios -- at exhaust temperatures between 1000 K and 2000 K. At these low temperatures, a solid heat exchanger can be both cheap and efficient. A heat-exchanger-based thruster has a fundamental advantage over other laser-heated engines in that it is omnivorous -- any laser wavelength or pulse format is acceptable. We present some options for vehicle and launch-system design and estimate their performance. 13 refs., 8 figs.

Kare, J.

1991-04-01

247

Influence of SiC particles on the heat exchange at the metal-mould interface during composite flow along the mould channel  

Directory of Open Access Journals (Sweden)

Full Text Available Calculation results concerning the heat transfer coefficient at the metal-mould interface during flow of the AlMg10 alloy matrix composites containing various fractions of solid SiC particles and, for the purpose of comparison, of the pure AlMg10 alloy in the channel-like cavity of the spiral castability test mould have been presented. Cooling curves and flow velocities have been determined on the basis of metal temperature measured during flow. These experimental data have been used for calculation of the heat transfer coefficient values at given points of a metal stream along the mould channel. Comparison of obtained values and the analysis of the influence of SiC particles on the heat exchange have been presented.

Z. Konopka; M. ??giewka; A. Zyska; M. Nadolski

2008-01-01

248

Fouling of heat exchanger surfaces  

Energy Technology Data Exchange (ETDEWEB)

45 papers are presented under the session headings: microbial fouling; chemical reaction fouling; gas-side fouling of heat exchanger surfaces; particulate fouling; advanced cycle fouling; gas-side fouling as a result of impurities in fossil fuels; precipitate and freezing fouling; fouling of heat transfer surfaces at high pressures; and operation and cleaning of heat transfer equipment in dirty gas environments.

Bryers, R.W. (ed.)

1983-01-01

249

Heat exchanger using graphite foam  

Science.gov (United States)

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

Campagna, Michael Joseph; Callas, James John

2012-09-25

250

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

Energy Technology Data Exchange (ETDEWEB)

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

251

Ambient air heat exchanger for a heat pump heating system. Umgebungsluft-Waermetauscher fuer eine Waermepumpen-Heizungsanlage  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to develop an ambient air heat exchanger for a heat pump heating system so that it can work with heat exchange practically independent of the incoming direction of the air moved by the wind. According to the invention, this problem is solved by the heat exchanger elements being made as plates with a square plan view, which have the heat carrier flowing through them and which are provided with intermediate flow spaces for the air moved by the wind, and have practically the same flow resistance for all directions of flow. The surface of the heat exchanger elements can simply evaporate by the heat pump and by natural heat exchange with the air moved by the wind. Metals and plastics are suitable as materials for the heat exchanger elements. (HWJ).

Dietrich, B.; Kimpenhaus, W.

1984-06-14

252

Gas log fireplace heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

A gas fueled heat exchange machine consists of a fan-driven, air fed, sealed chamber manifold resting flush on the base of a fireplace and centered square to its back wall. A series of cylindrical thick-walled ceramic tubes act as heated air conduits which are inset with heat-resistant cement both in the rear manifold and in the extended forward ends of the front body wall at the fireplace opening. Desirably the sealed air chamber is rectangular and has horizontal fixed louvered fins across its lower front to allow room-temperature air to be drawn upward from the cooler floor level into the fireplace, then forced through the lint-filtered sealed chamber and manifold and heated ceramic conduits, returning the warmed air to the room by vertical-slatted louvers which divert the air flow to ascend at wide angles from the machine. The forced air cycle is provided by an electric transflow blower which is heat protected inside the sealed chamber at the internal base of the manifold. On the top surface of the seald chamber, there is a horizontal U-shaped gas burner with a controllable primary air inlet on the underside thereof, together with side vents on both ends of the machine's walls to provide secondary combustion air supply. The hollow gas burner has a plurality of apertures on its top, spaced apart and in varying sizes, forming a consistent design which governs the height of the gas flame in a regulated undulating pattern.

1988-07-19

253

Analysis of Heat Transfer Enhancement in Spiral Plate Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available In the present study, the heat transfer coefficients of benzene in a spiral plate heat exchanger are investigated. The test section consists of a Plate of width 0.3150 m, thickness 0.001 m and Mean hydraulic diameter of 0.01 m. The mass flow rate of water (Hot fluid) is varying from 0.5 kg sec-1 to 0.8 kg sec-1 and the mass flow rate of benzene (cold fluid) varies from 0.4 kg sec-1 to 0.7 kg sec-1. Experiments have been conducted by varying the mass flow rate, temperature and pressure of cold fluid, keeping the mass flow rate of hot fluid constant. The effects of relevant parameters on spiral plate heat exchanger are investigated. The data obtained from the experimental study are compared with the theoretical data. Besides, a new correlation for the nusselt number which can be used for practical applications is proposed.

Kaliannan Saravanan; Rangasamy Rajavel

2009-01-01

254

Heat exchanger fouling and corrosion  

International Nuclear Information System (INIS)

Fouling of heat transfer surfaces introduces perhaps the major uncertainty into the design and operation of heat exchange equipment. After a brief description of the various types of fouling the chapter goes on to review the current theories of fouling including the turbulent burst theory. Fouling in equipment involving boiling and evaporation is often more severe than in single phase heat exchangers and moreover, in aqueous systems, is frequently associated with corrosion. The reasons for this are identified and illustrated by reference to corrosion in nuclear power plant steam generators. Finally the modification of heat transfer and pressure drop characteristics by fouling layers is briefly reviewed.

1986-01-01

255

Solar radiant energy heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A radiant energy heat exchanger for use in a solar energy power plant comprises one or more banks of heat exchange ducts, each bank of ducts having an inlet and an outlet manifold to receive and discharge the medium to be heated. The ducts are curved along their length between the inlet and outlet manifolds so that the amount of radiant energy falling on the ducts per unit area of duct decreases between the inlet and outlet manifolds at such a rate that the duct temperature is substantially constant between the manifolds while the temperature of the medium being heated increases, the radiant energy falling on the ducts being substantially unidirectional.

Jubb, A.; Stansbury, E.W.

1980-09-16

256

Analytical, one-dimensional frequency model for U-shaped heat exchangers with regard to disturbances of inlet temperature and inlet mass flow in the primary and secondary loop  

International Nuclear Information System (INIS)

A linear, one- dimensional analytical frequency response model for U-tube heat exchangers will be presented. The model calculates the frequency response behaviour of fluid- temperatures both on the primary and secondary side at any position (and in particular at the outlet) of the heat exchanger with respect to perturbations of inlet fluid temperatures and inlet fluid mass flows. (orig.)

1975-01-01

257

Thermal performance analysis for heat exchangers having a variable overall heat transfer coefficient.  

Science.gov (United States)

The classic, conventional analysis for the thermal performance of heat exchangers is based on three assumptions: constant fluid flow rate, constant specific heat fluids, and constant overall heat transfer coefficient. Our analysis describes a general appr...

J. C. Conklin E. Granryd

1991-01-01

258

The dry heat exchanger calorimeter system  

Energy Technology Data Exchange (ETDEWEB)

A radiometric isothermal heat flow calorimeter and preconditioner system that uses air instead of water as the heat exchange medium has been developed at Mound. The dry heat exchanger calorimeter is 42 inches high by 18 inches in diameter and the preconditioner is a 22 inch cube, making it extremely compact compared to existing units. The new system is ideally suited for transportable, stand-alone, or glovebox applications. Preliminary tests of the system have produced sample measurements with standard deviations less than 0.25% and sample errors less than 0.50%. These tests have shown that the dry heat exchanger system will yield acceptance data with an accuracy comparable to those of Mound water bath systems now in use. 4 figs., 1 tab.

Renz, D.P.; Wetzel, J.R.; James, S.J.; Kasperski, P.W.; Duff, M.F.

1991-01-01

259

Stress analysis of heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This paper presents procedures for computing stresses in floating-head and fixed tubesheet heat exchangers. It does not cover U-tube exchangers. It was prepared in connection with the activities of the Special Working Group on Heat Transfer Equipment, Section VIII, of the ASME Boiler and Pressure Vessel Code Committee, for their use and consideration in the drafting of code rules for these items.

Soehrens, J.E.

1987-01-01

260

Designing heat exchangers by computer  

Energy Technology Data Exchange (ETDEWEB)

The design of heat exchangers by computer has come a long way in a short time due to the explosive development of computer hardware and the ingenuity of the software developers. It is already possible to design by computer a reasonably-sized heat exchanger for most services. However, the future potential is great for the computer to simulate performance for troubleshooting, optimum selection, and even operator training.

Palen, J.W.

1986-07-01

 
 
 
 
261

Condensation and frost formation in heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered.

Rostami, A.A.

1982-01-01

262

Condensation and frost formation in heat exchangers  

International Nuclear Information System (INIS)

The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered

1982-01-01

263

Vibration damping in multispan heat exchanger tubes  

International Nuclear Information System (INIS)

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

1998-01-01

264

Flow-induced vibrations in commercial heat-exchangers involving different densities and viscosities of the fluid  

Energy Technology Data Exchange (ETDEWEB)

Tube-array heat exchangers are known from operating experience to suffer damage due to periodical movements of the tubes. Project A 6 is aimed at studying the fluid-elastic combination of tube vibrations in fluids of different densities and viscosities. The paper reports the state of investigations, the study methods used and the test facility. In addition, it discusses the results achieved with the test facility. (HAG).

Hesse, F.

1986-01-01

265

Performance Analysis of Spiral Tube Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available In the present study, the performance of the spiral tube heat exchanger can be carried out. The heat exchanger consists of a shell and tube unit. Each coil is fabricated by bending a 12 mm diameter straight copper tube into a spiral coil tube of four turns. Cold water and hot oil are used as working fluids in shell side and tube side, respectively. The experiments are done at the cold water and hot oil mass flow rates ranging between 0.075 and 0.25 kg/s, and between 0.008 and 0.04 kg/s, respectively. The inlet temperatures of cold and hot water are between 29 and 37 °C, and between 70 and 56 °C, respectively. The cold water entering the heat exchanger at the shell inlet side and outer from the shell outside. The hot water enters the heat exchanger at the inner tube side and flows along the outside of the tube. The effects of the inlet conditions of both working fluids flowing through the test section on the heat transfer characteristics are discussed..

JAY J. BHAVSAR,; DR. V K. MATAWALA,; S.B.DIXIT

2013-01-01

266

Multidimensional numerical modeling of heat exchangers  

Science.gov (United States)

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

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

267

Multidimensional numerical modeling of heat exchangers. [LMFBR  

Energy Technology Data Exchange (ETDEWEB)

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

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

1982-01-01

268

Multidimensional numerical modeling of heat exchangers  

International Nuclear Information System (INIS)

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

1982-01-01

269

Heat exchangers with tube bundles  

Energy Technology Data Exchange (ETDEWEB)

A heat exchangr is described for heat-transfer between substances of high pressure difference including a shell, a region through which a cooler substance is conveyed; an inlet for the cooler substance; a bundle of tubes arranged in a cooler substance compartment; and riser conduits operatively connectible to the shell and communicating with the compartment, with the substance to be cooled being passed through the tubes having a high temperature at the inlet of the heat exchanger and at the outlet; a tube bottom of predetermined thickness arranged at the heat exchanger inlet; and a device including a support-grating arranged in the vicinity of the tube bottom, operatively connectible to the shell and extending at least nearly perpendicular to the tube bottom in the region through which the cooler substance is conveyed. The heat exchanger also includes a top provided with apertures and the like which are easily accessible from the steam-water space of the heat exchanger with cooling channels being provided which are adapted to be in communication with the apertures and riser conduits provided outside the heat exchanger proper.

Deuse, K.; Drobka, W.

1980-12-02

270

Examples of plate type heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

Gas-gas plate type heat exchanger is produced by the company which the author works for with its design and actual examples. The present heat exchanger can be used, without change in basic structure, in a wide temperature range covering the high temperature (900/sup 0/C at exhaust gas entrance) in the sludge incineration, etc. to the low temperature (150 to 70/sup 0/C exhaust gas) in the dryer exhaust heat recovery of paper machine. An actual example specifies 85 to 70/sup 0/C with 107,400m/sup 3//h on high temperature side, 30 to 52/sup 0/C with 75,300m/sup 3//h on low temperature side, 516,000Kcal/h in heat exchange quantity rate, 669.9m/sup 2/ in heat transfering area, SUS 304 in material and 0.6 mm in thickness. The plate type heat exchanger generally is lighter in weight and smaller in occupying space than the multi-tube type, and can be heightened to heigher than 80% in heat recovery ratio. Different engineered measures have been adopted to it, e.g. by approaching the low temperature side gas temperature to the water dew point of high temperature side gas for the prevention against corrosion or improving the flow conduit and temperature control to keep the heat transfering surface temperature to be higher than the acid dew point. (4 figs)

Fujii, Yasuji

1988-08-30

271

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

Science.gov (United States)

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

Kanzaka, Mitsuo; Iwabuchi, Makio

1992-11-01

272

Tube side flow rate distribution in a horizontal multitube heat exchanger. 5th Report. Flow characteristics in tube bundle arranged in a rectangular shape; Suiheina tabunkikan eno henryu ni kansuru kenkyu. 5. Chohokei no kangun ni okeru nagare no tokusei  

Energy Technology Data Exchange (ETDEWEB)

In the previous paper, we showed that the flow rate distribution into the branch tubes from the inlet header of a 2-tube pass multitude heat exchanger which has the tube bundle arranged in a rectangular shape is markedly different from that which has the tube bundle arranged in a square shape. In the present experiment, to clarify the mechanism which causes this difference, the flow pattern in the inlet, outlet and return header of the 2-tube pass multitude heat exchanger was visualized using aluminum powder as a tracer, and the pressure distribution on the bottom wall of the inlet header was measured. The results show that the flow rate distribution is closely related to the flow pattern in the inlet header. Also, the eddy generated in the return header is strong and contains air bubbles which are never discharged. 4 refs., 12 figs.

Esaki, S. [Kagoshima College of Technology, Kagoshima (Japan); Fukano, T. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

1995-09-25

273

High performance printed circuit heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

Three-dimensional thermal-hydraulic simulations have revealed a new flow channel configuration for Printed Circuit Heat Exchanger (PCHE) recuperators of a carbon dioxide gas turbine cycle. Simulation calculations were done changing the fin shape and angle parametrically to obtain an optimal flow channel configuration considering pressure drop and heat transfer performance. The new configuration has discontinuous fins with an S-shape, similar to a sine curve, in contrast to the conventional continuous zigzag configuration. The new configuration has one-fifth of the pressure drop reference to the conventional zigzag configuration with equal thermal-hydraulic performance. The pressure drop reduction is ascribed a superior uniform flow velocity profile in the flow area and elimination of reverse flows and eddies that occur around bend corners of zigzag flow channels in conventional PCHE. (author)

Tsuzuki, Nobuyoshi; Kato, Yasuyoshi; Ishiduka, Takao [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)

2007-07-15

274

Tube side flow rate distribution in a horizontal multitube heat exchanger. 2nd Report. ; Control of flow into branch tubes. Suiheina tabunkikan eno henryu ni kansuru kenkyu. Dai niho. ; Henryu no yokusei hoho ni tsuite no kento  

Energy Technology Data Exchange (ETDEWEB)

In case of branch flows between header and each branch tube inside multitube heat exchangers, since there will be partially faster flow or slower flow than mean velocity depends on water supply conditions towards the header, drifting flows are generated inside the tubes. This kind of drifting flows are closely related to heat transfer performance of heat exchanger and they are also related to corrosion of steel pipes when being beyond the allowable velocity. In this paper, authors have paid their attention that such drifting flows are strongly dependent on the distribution at the entrance of tubes of dynamic pressure of jets from water supply pipes, and several geometry discs or drifting flow control panels were set inside the header positioning at the downstream of the water supply tubes to buffer the dynamic pressure of the water supply tubes, then a method to control the drifting flow was examined. As a result, it could be possible to reduce approximately 60 % of the standard deviation of drifting flow ratio by attaching suitable discs to the appropriate places of exits of water supply pipes, and especially when using porous discs, it was confirmed appropriate hole diameter should be existing and more than 80 % of reduction could be obtained. 2 refs., 16 figs.

Esaki, S. (Kagoshima National College of Tech., Kagoshima (Japan)); Fukano, T. (Kyushu Univ., Fukuoka (Japan). Faculty of Engineering); Ando, Y. (Nippon Denso Co. Ltd., Aichi (Japan)); Kinoshita, H. (Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan))

1991-07-25

275

Heat transfer enhancement in heat exchangers by longitudinal vortex generators  

International Nuclear Information System (INIS)

In this paper heat transfer enhancement and flow losses are computed for the interaction of a laminar channel flow with a pair of counterrotating longitudinal vortices generated by a pair of delta-winglets punched out of the channel wall. The geometry simulates an element of a fin-plate or fin-tube heat exchanger. The structure of the vortex flow and temperature distribution, the local heat transfer coefficients and the local flow losses are discussed for a sample case. For a Reynolds number of Red = 1000 and a vortex generator angle of attack of ? = 25 degrees heat transfer is enhanced locally by more than 300% and in the mean by 50%. These values increase further with Re and ?

1990-01-01

276

Small Scale Thermosyphon Heat Exchanger.  

Science.gov (United States)

A small circular heat transfer cell was used to study the cooling of a disc heat source by a thin evaporating liquid film. This small scale thermosyphon is a thermal spreader and a passive heat sink in that the interfacially induced liquid flow rates are ...

M. Sujanani E. W. Kiewra P. C. Wayner

1986-01-01

277

RADIAL DESIGN OXYGENATOR WITH HEAT EXCHANGER  

UK PubMed Central (United Kingdom)

Described is an apparatus (100) for oxygenating and controlling the temperature of blood in an extracorporeal circuit, the apparatus having an inlet (112) and an outlet (109) that is located radially outward from the inlet in order to define a flowpath through the apparatus, the apparatus comprising: a core (120) in communication with the inlet such that blood from a patient can be supplied to the core, the core comprising a first element and a second element that interfit to define openings, wherein the elements and the openings together enhance flow of blood from the patient radially outward from the core a heat exchanger (130) that is arranged about the core and through which blood from the core can move radially outward and an oxygenator (140) that is arranged about the heat exchanger and through which blood from the heat exchanger can move radially outward before exiting the apparatus through the outlet.

CARPENTER WALT; OLSEN ROBERT W; HOBDAY MICHAEL J; MCLEVISH ALFORD L; PLOTT CHRISTOPHER; BRISCOE RODERICK E; CLOUTIER PATRICK J; THAPA ANIL; LI MING; MCINTOSH KEVIN; MERTE KEN

278

An investigation of heat exchange of liquid metal during flow in a vertical tube with non-uniform heating in the transverse magnetic field  

Science.gov (United States)

The results of experimental investigations of heat exchange during the downflow of liquid metal in a vertical tube with non-uniform heating in the transverse magnetic field are presented. The experiment was more realistic in terms of conditions of the blanket of a fusion reactor of the tokamak type. Profiles of the average temperature, distribution of local and mean heat transfer coefficients (Nusselt numbers), and the intensities and spectra of temperature pulsations have been measured. On certain combinations of operating parameters in the strong magnetic field low-frequency temperature pulsations with abnormal intensity were found.

Mel'nikov, I. A.; Razuvanov, N. G.; Sviridov, V. G.; Sviridov, E. V.; Shestakov, A. A.

2013-05-01

279

Polymer-based heat exchanger desiccant systems  

Energy Technology Data Exchange (ETDEWEB)

The increasing popularity of desiccant-enhanced air conditioning systems has sparked new interest in the search for a better, more efficient desiccant material. The ultimate goal of this research was to develop a material that, when applied to an existing air-to-air heat exchanger, would achieve the necessary heat and mass transfer in a single process, thus transforming a sensible heat exchanger into a total enthalpy exchanger. This study focused on the development and determination of appropriate polymeric desiccant materials for use in different heat and mass transfer systems. The specific objectives for the study were to select an appropriate polymer desiccant, determine the necessary materials properties for this material, and develop and implement mathematical models to analyze the desiccant performance. Two systems were investigated for this study: a rotary wheel total enthalpy exchanger and a fixed plate total enthalpy exchanger. Seven different polymer materials were analyzed to determine the most suitable candidate. Although for the specific conditions studied, the commercial paper-ceramic desiccant out-performed the PVOH materials in both rotary wheel and fixed plate systems, the results suggested that two PVOH materials, PVOH open-cell foam and PVOH/silica gel/molecular sieve composite, have potential for use in total energy exchange applications. By modifying the design conditions, total efficiencies exceeding 70% were achieved for both PVOH foam and PVOH/ceramic composite in rotary wheel systems. In addition, modified the design conditions resulted in total efficiencies greater than 90% for the PVOH foam in both counter-flow and cross-flow flat plate systems. These findings indicated that with appropriate optimization of the exchanger design, these two PVOH materials could have the potential to perform as well as desiccant materials in current rotary wheel and fixed plate exchanger systems.

Staton, J.C.; Howard, J.L.; Scott, E.P.; Kander, R.G.

1999-07-01

280

Materials Development for HTGR Heat Exchangers.  

Science.gov (United States)

Some versions of the HTGR generate high primary coolant gas temperatures (850 exp 0 to 950 exp 0 C) and exchange this heat, through intermediate heat exchangers (IHX's), to a secondary loop for higher temperature process heat applications. Although IHX's ...

W. R. Johnson D. I. Roberts

1982-01-01

 
 
 
 
281

Issues of predicting performance of thermosyphon heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Determination of 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 presented and discussed in terms of modeling issues. The inadequacy of using a simple temperature difference to predict thermosyphon flow rate is illustrated. Accuracy of prediction of thermosyphon flow rate from a pressure balance on the water loop depends on the accuracy of assumed temperature distributions in the heat exchanger and tank. For a given collector flow rate, heat exchanger performance depends on natural convection heat transfer coefficient and temperature of the antifreeze fluid and is not uniquely determined by thermosyphon flow rate. Models based on the assumption that for a given collector flow rate, overall heat transfer coefficient-area product or effectiveness of the heat exchanger are determined by thermosyphon flow rate may produce erroneous predictions of system performance.

Davidson, J.H.; Dahl, S.D. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Mechanical Engineering

1996-12-31

282

Solar heat exchange panel  

Energy Technology Data Exchange (ETDEWEB)

Heat-absorbing bars having a v-shape are placed parallel to one another in a spaced relationship over a reflective surface. Sunlight strikes the bars on their exposed surface and also off the reflective surface against the underside of the bars. Water tubes may also be used.

Thorne, N.J.

1980-09-09

283

Carbon nanotube heat-exchange systems  

Energy Technology Data Exchange (ETDEWEB)

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

284

Effect of the Moments of Probability Density Function for Non-uniform Air Flow Distribution on the Hydraulic Performance of a Fin-tube Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available The work presented in this paper examines the effect of a non-uniform airflow velocity distribution on the air pressure drop through the fin passages of a single row fin-tube heat exchanger. Water flow rate through the tubes and its temperature are taken as constant. Maldistribution of the airflow increases the average pressure drop with respect to that of a uniform flow. As a result of this, the pumping power required by the fan or blower will also increase. The increase of the pumping power is calculated by means of a discretization technique and it is analyzed with respect to the non-uniform distribution statistical moments of probability density function, i.e., the mean, standard deviation, skew and kurtosis. The analysis reveals that the increase of pumping power is dependent on the exchanger NTU, standard deviation and skew of the velocity distribution. Kurtosis has no effect on the pressure drop. Correlations have been developed to predict this increase of pumping power from known statistical moments and resulting air temperatures. These can then be used as design tools to optimize the sizing of the heat exchanger within the air-conditioning unit, hence giving the best energy efficiency performance.

Wai Meng Chin; Vijay R. Raghavan

2011-01-01

285

New heat exchanger conception applied to the heat pumps  

Energy Technology Data Exchange (ETDEWEB)

Improvements to the heat exchangers for heat pumps are presented in this paper. During the latterly years there has been an evolution in the geometries of tubes used as the exchange surface of heat exchange apparatus: different techniques which are commercially available are discussed in this article. The recent appearance of plate heat exchanger as condenser and evaporator have evolved.

Marvillet, C.

1987-09-01

286

Thermofluid characteristics of frosted finned-tube heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The performance of frosted finned-tube heat exchangers of different fin types is investigated by experiments in this paper. The effects of the air flow rate, the air relative humidity, the refrigerant temperature, and the fin type on the thermofluid characteristics of the heat exchangers are discussed. The time variations of the heat transfer rate, the overall heat transfer coefficient, and the pressure drop of the heat exchangers are presented. The heat transfer rate, the overall heat transfer coefficient, and the pressure drop for heat exchangers with re-direction louver fins are higher than those with flat plate fins and one-sided louver fins are. The amount of frost formation is the highest for heat exchangers with re-direction louver fins. (author)

Wei-Mon Yan; Hung-Yi Li [Huafan University, Taipei (Taiwan). Department of Mechatronical Engineering; Yeong-Ley Tsay [National Huwei Institute of Technology, Yunlin (Taiwan). Department of Aeronautical Engineering

2005-07-01

287

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

Science.gov (United States)

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

288

Numerical Analysis of Tube-Fin Heat Exchanger using Fluent  

Directory of Open Access Journals (Sweden)

Full Text Available Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of two-row plain Tube and Fin heat exchanger using FLUENT software. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created and meshed by using GAMBIT software. Fluid flow and heat transfer are simulated and results compared using both laminar and turbulent flow models k-, and SST k-omega, with steady-state solvers to calculate pressure drop, flow, and temperature fields. Model validation is carried out by comparing the simulated value friction factor f and Colburn factor j to experimental results investigate by Wang. Reasonable agreement is found between the simulations and experimental data, and the fluent software has been sufficient for simulating the flow fields in tube-fin heat exchangers.

M. V. Ghori; R. K. Kirar

2012-01-01

289

Characteristics of vertical mantle heat exchangers for solar water heaters  

Energy Technology Data Exchange (ETDEWEB)

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. Both the experimental and simulation results indicate that distribution of the flow around the mantle gap is governed by buoyancy driven recirculation in the mantle. The operation of the mantle was evaluated for both high and low temperature input flows. (author)

Shah, L.J. [Technical University of Denmark, Lyngby (Denmark). Dept. of Buildings and Energy; Morrison, G.L.; Behnia, M. [University of New South Wales, Sydney (Australia). Dept. of Mechanical and Manufacturing Engineering

1999-07-01

290

Analysis of flow-induced vibration of heat exchanger and steam generator tube bundles using the AECL computer code PIPEAU-2  

International Nuclear Information System (INIS)

[en] PIPEAU-2 is a computer code developed at the Chalk River Nuclear Laboratories for the flow-induced vibration analysis of heat exchanger and steam generator tube bundles. It can perform this analysis for straight and 'U' tubes. All the theoretical work underlying the code is analytical rather than numerical in nature. Highly accurate evaluation of the free vibration frequencies and mode shapes is therefore obtained. Using the latest experimentally determined parameters available, the free vibration analysis is followed by a forced vibration analysis. Tube response due to fluid turbulence and vortex shedding is determined, as well as critical fluid velocity associated with fluid-elastic instability

1983-01-01

291

Ceramic heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-01-01

292

A study on the heat transfer development of heat exchanger with vortex generator  

Energy Technology Data Exchange (ETDEWEB)

A numerical analysis using FLUENT code was carried out to investigate flow characteristics and heat transfer development of heat exchangers. The analysis results for both cases of the fin-circular tube and the fin-flat tube heat exchanger with the vortex generator show relatively higher heat transfer coefficient than that for both cases of the fin-circular tube and the fin-flat tube heat exchangers without the vortex generator. Also, the analysis result for the fin-circular tube heat exchanger with the vortex generator has relatively higher heat transfer coefficient and higher pressure loss than those for the fin-flat tube heat exchanger with the vortex generator. The results of this study can be used to design the heat exchanger with relatively low pressure loss and maximum heat transfer coefficient. 28 figs., 15 refs. (Author) .new.

Lee, Jung Sub; Oh, Kwang Suk; Kim, Sun Chul; Kim, Do Hyun; Oh, Jong Phil [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-05-01

293

Heat exchangers for HHT plants  

International Nuclear Information System (INIS)

[en] Closed gas turbine installations are equipped with recuperator, precooler and, depending on the design concept, intercooler. If the heat source is a nuclear reactor, core auxiliary heat interchangers must be provided additionally. The report deals with the corresponding heat exchangers of the HHT reference plant (high-temperature reactor with helium turbine). (orig.)[de] Geschlossene Gasturbinenanlagen sind mit Rekuperator, Vorkuehler und je nach Auslegung auch Zwischenkuehler ausgeruestet. Ist die Waermequelle ein Kernreaktor, so sind auch Nachwaermeabfuhr-Kuehler vorzusehen. Der Bericht behandelt die entsprechenden Waermetauscher der HHT-Referenzanlage (Hochtemperaturreaktor mit Heliumturbine). (orig.)

1979-01-01

294

Modeling water and heat flows through a mulch allowing for radiative and long-distance convective exchanges in the mulch  

Science.gov (United States)

This work aims at modeling quantitatively the effects of a mulch on the water and heat transfers in the soil-mulch-atmosphere system. The developed model TECmulch derives from the mechanistic model TEC, designed for bare soil. TECmulch accounts for (1) free convection, (2) forced convection, and (3) radiative transfer in the mulch. The mulch formalism does not rely on the classical local gradients theory but on long-distance exchanges. It is based on four parameters that are calibrated on experimental data for two different mulches (corn residue and crushed glass). Experimental data come from la Tinaja's station (Mexico) for corn mulch and Avignon's station (France) for glass mulch. Measurements concern the physical characterization of the soil and the mulch, the evolution of soil water content and temperature, and the radiative balance plus usual climatic data. TECmulch is validated on independent data, compared to the classical theory, and each modeled process is analyzed in detail.

Findeling, A.; Chanzy, A.; de Louvigny, N.

2003-09-01

295

Heat Transport Study of the Laminar Heat Pipe Heat Exchanger  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this experiment is to analyze the performance of the Laminar Heat Pipe Heat Exchanger. The test samples were divided two groups, one is the metal corrugated sheet with heat pipe, and the other is the metal corrugated sheet only. By dipping these two group samples into hot water and to...

Wei-Keng Lin; Ke Chine Liaw; Min-Zen Tsai; Min-Gung Chu

296

Residence time distribution measurements and simulation of the flow pattern in a scraped surface heat exchanger during crystallisation of ice cream  

UK PubMed Central (United Kingdom)

Scraped surface heat exchangers are used in the food industry to process highly viscous fluids, and ice-cream in particular, but most of the time, the influence of operating conditions on product quality is poorly understood. The objective of the study is to develop simple tools to help industrials understand, and then optimise their fabrication process. Residence Time Distribution (RTD) has been characterised in an industrial pilot system during real ice cream production, after the method had been validated in an experimental set-up with a simple mixture of water and sucrose. It has been shown that in its dimensionless form, RTD depend slightly on flow rate and scraper rotational speed. A simple model of flow pattern applicable to SSHE during crystallisation was developed to reproduce the observed RTD. It distinguishes two zones: the volume of fluid near the cooling wall where ice is generated and which is swept by the blades and the volume of fluid near to the rotor. Therefore, the model considers two parallel plug flow reactors with axial dispersion, and which exchange fluid by radial mixing. After adjustment of the model parameters, a good agreement was obtained with experimental results. The flow rate is lower in the zone near the cooling wall; this can be due to a higher ice concentration leading to higher viscosity. This approach can contribute to better understand, optimise and control SSHE used for ice cream production.

Fayolle Francine; Belhamri Rachida; Flick Denis

2013-05-01

297

Air duct heat exchanger; Luftkanal-Waermetauscher  

Energy Technology Data Exchange (ETDEWEB)

A mechanical building ventilation unit that brings together two functions - fluid transport and heat recovery - is presented. Aluminium fins in the supply air duct and in the adjacent extract air duct increase the heat flow from fluid to fluid. This unit is mainly intended to be used for residential ventilation and was investigated by means of experiments and simulations. Air flow rates, temperatures, air humidities and pressure differences were measured in an experimental set-up. Additionally, using a program for two-dimensional heat conduction analyses and a simple model, the efficiency of the heat recovery was calculated and compared with measurements. Afterwards, the influence of variations of the heat exchanger geometry was investigated by means of simulations. It was shown that by using this concept, it is possible to realise a ventilation unit in which heat is exchanged with high efficiency, e.g. temperature efficiency of 0.7 at a duct length of 6 m. At the same time, low pressure-drops occur, typically 20 Pa, which leads to low rates of electrical energy input. (author)

Huber, H.; Helfenfinger, D. [Berner Fachhochschule, Hochschule fuer Technik und Architektur (HTA), Lucerne (Switzerland); Manz, H. [EMPA Eidgenoessischen Materialpruefungs- und Forschungsanstalt, Duebendorf (Switzerland)

2000-07-01

298

Condensation in horizontal heat exchanger tubes  

Energy Technology Data Exchange (ETDEWEB)

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

299

Characterization of a tube-in-shell thermosyphon heat exchanger for solar water heating  

Energy Technology Data Exchange (ETDEWEB)

Performance of a double-wall, natural convection, two-pass, tube-in-shell heat exchanger designed for use in a solar water heating system is measured. The heat exchanger is mounted along the length of a solar water storage tank. Flow of cold water on the shell side of the heat exchanger is driven solely by buoyancy forces. Hot side fluid is pumped. Flow rate, pressure drop and temperature data needed for a semi-empirical model of the heat exchanger are obtained. Performance is measured for forced convection, hot side volumetric flow rates of 0.016, 0.032 and 0.079 l/s. Temperature difference between hot and cold fluid at the inlets is varied from 0 to 75 degC. Measured values include thermosyphon and forced flow rates, temperature differences across the beat exchanger, vertical temperature distribution in the storage tank, and pressure drop due to shear on the thermosyphon side of the heat exchanger. Heat exchanger effectiveness and overall heat transfer area product (UA) are calculated. Thermosyphon mass flow rates are on the order of 0.01 kg/s. Although the low flow rates create thermal stratification of the water storage tank, they restrict energy transfer in the heat exchanger.

Dahl, S.D.; Davidson, J.H. [Univ. of Minnesota, Minneapolis, MN (United States). Mechanical Engineering Dept.

1995-11-01

300

Applying the temperature effectiveness method to heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Off-design variations in heat load, flow rates, and service water inlet (heat sink) temperature, such as those due to seasonal changes, have been observed to cause significant variation in temperature effectiveness. This paper examines the effect of off-design test conditions on temperature effectiveness and further presents a correction to the temperature effectiveness for off-design variation in service water inlet temperature. Temperature effectiveness is the ratio of the actual heat load to the maximum theoretical heat load. As heat exchanger thermal performance degrades, temperature effectiveness decreases. It has been discovered, however, that off-design variations in system heat load, system flows, and heat sink temperature cause false trends in the temperature effectiveness. Three heat exchange systems are used to study the temperature effectiveness method: a typical water-to-water heat exchanger, an air-to-water room cooler, and a main steam condenser.

Pesce, M.M. [Power Generation Technologies, Knoxville, TN (United States)

1994-12-31

 
 
 
 
301

Comparative thermal analysis of theoretical and experimental studies of modified indirect evaporative cooler having cross flow heat exchanger with one fluid mixed and the other unmixed  

Energy Technology Data Exchange (ETDEWEB)

The comparative thermal analysis of theoretical and experimental studies of modified indirect evaporative cooler having cross flow heat exchanger with one fluid mixed and the other unmixed is presented in this research paper. A heat and mass transfer mathematical model is developed to simulate the properties of indirect evaporative cooler. The theoretical result analysis was done by plotting the curves between various performance parameters. This work presents the fabrication and experiments carried out on the indirect evaporative cooler at various outdoor air conditions. The data acquired by experiment were analyzed by plotting the curves between various performance parameters. The theoretical and experimental results were compared and analyzed. The theoretical model can be used to predict the performance of modified indirect evaporative cooler.

Bisoniya, Trilok Singh [Department of Mechanical Engineering, Sagar Institute of Research and Technology, Ayodhya Bypass Road, Bhopal 462041 (India); Rajput, S.P.S. [Department of Mechancical Engineering, Maulana Azad National Institute of Technology, Bhopal, 462051 (India); Kumar, Anil [Department of Energy, Maulana Azad National Institute of Technology, Bhopal, 462051 (India)

2011-07-01

302

Boiling heat transfer in compact heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

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

303

Industrial applications for LIGA-fabricated micro heat exchangers  

Science.gov (United States)

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

304

Planetary heat flow measurements.  

UK PubMed Central (United Kingdom)

The year 2005 marks the 35th anniversary of the Apollo 13 mission, probably the most successful failure in the history of manned spaceflight. Naturally, Apollo 13's scientific payload is far less known than the spectacular accident and subsequent rescue of its crew. Among other instruments, it carried the first instrument designed to measure the flux of heat on a planetary body other than Earth. The year 2005 also should have marked the launch of the Japanese LUNAR-A mission, and ESA's Rosetta mission is slowly approaching comet Churyumov-Gerasimenko. Both missions carry penetrators to study the heat flow from their target bodies. What is so interesting about planetary heat flow? What can we learn from it and how do we measure it?Not only the Sun, but all planets in the Solar System are essentially heat engines. Various heat sources or heat reservoirs drive intrinsic and surface processes, causing 'dead balls of rock, ice or gas' to evolve dynamically over time, driving convection that powers tectonic processes and spawns magnetic fields. The heat flow constrains models of the thermal evolution of a planet and also its composition because it provides an upper limit for the bulk abundance of radioactive elements. On Earth, the global variation of heat flow also reflects the tectonic activity: heat flow increases towards the young ocean ridges, whereas it is rather low on the old continental shields. It is not surprising that surface heat flow measurements, or even estimates, where performed, contributed greatly to our understanding of what happens inside the planets. In this article, I will review the results and the methods used in past heat flow measurements and speculate on the targets and design of future experiments.

Hagermann A

2005-12-01

305

Heat exchangers: Selection, rating, and thermal design  

Energy Technology Data Exchange (ETDEWEB)

This book takes a systematic approach to the subject, focusing on the selection, design, rating, and operational challenges of various types of heat exchangers. Written by well-known authors in the field of heat transfer, this book covers all the most commonly used types of heat exchangers, including condensers and evaporators. The text begins with the classification of the different types of heat exchangers and discusses methods for their sizing and rating. Single phase forced convection correlations in ducts and pressure drop and pumping power analysis are also covered. A chapter is devoted to the special problem of fouling. Thermal design methods and processes, including designs for condensers and evaporators, complete this thorough introduction to the subject. The appendix provides information on the thermophysical properties of fluids, including the new refrigerants. Every topic features worked examples to illustrate the methods and procedures presented, and additional problems are included at the end of each chapter, with examples to be used as a student design project. An instructor's manual is available, including complete solutions to selected problems in the text. The contents include: classification of heat exchangers; basic design methods of heat exchangers; forced convection correlations for single-phase side of heat exchangers; heat exchanger pressure drop and pumping power; fouling of heat exchangers; double-pipe heat exchangers; design correlations for condensers and evaporators; shell-and-tube heat exchangers; compact heat exchangers; gasketed-plate heat exchangers; and condensers and evaporators.

Kakac, S.; Liu, H.

1998-01-01

306

Noise spectra measured on the Dragon reactor primary heat exchanges  

International Nuclear Information System (INIS)

The frequency spectra of secondary water flow and tube wall temperatures have been measured on Dragon primary heat exchangers. No indication of tube wall temperature oscillations leading to tube burnout was found from the noise spectra analysed. (author)

1969-01-01

307

Temperature Profile Data in the Zone of Flow Establishment above a Model Air-cooled Heat Exchanger with 0.56 m2 Face Area Operating under Natural Convection  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to analyze the temperature profile in the Zone of Flow Establishment (ZFE) above a 0.56 m2 hot screen placed at different height above an electrically heated model air-cooled heat exchanger operating under natural convection. Installation of screens increased the...

Md. Mizanur Rahman; Sivakumar Kumaresan; Chu Chi Ming

308

Tube-type heat exchanger  

International Nuclear Information System (INIS)

The tube-type heat exchanger consists of a cylindrical casing in which are mounted U shaped heat exchange tubes anchored in a tube plate. The individual tubes of the inlet and outlet branch are fitted in support partitions normal to the axis of the tubes and provided with fins. The length of the fin equals half of the length of the chord of the support partition. The fins of the partitions of the inlet branch fit close to the partitions of the outlet branch and vice versa. The fin nearest to the tube plate comes into contact with the inner wall of the tube plate. Support partitions, fins and the inner surface of the casing thus form a helical throughflow channel to which are tangentially connected the inlet and outlet necks. (E.S.)

1979-03-08

309

Cooling device for a heat exchange fluid  

International Nuclear Information System (INIS)

[en] The invention refers to a system for cooling process or operation fluids, in which the local or general superheating of the coolant must be avoided. It particularly applies to the bleed fluid of a nuclear power station steam generator. This invention aims to create a heat exchange system that uses static components only and that is therefore completely reliable whilst remaining simple and relatively economical. This system includes a regeneration heat exchanger (with a primary and secondary system) and a triple flow heat exchanger with three circuits. The first and second circuits are in fluid communication with the primary and secondary circuits of the regeneration heat exchanger. The fluid communication between the regeneration heat exchanger and the triple circuit heat exchanger is such that the process fluid first goes through one of the circuits of the regeneration heat exchanger where it is cooled, then through one of the first two circuits of the triple circuit heat exchanger where it is cooled still more, then through the other of the circuits of the regeneration exchanger where it is heated and finally through the second of the first two circuits of the triple circuit heat exchanger where it is cooled again. A coolant flows through the third circuit in order to cool the process fluid concerned[fr] L'invention se rapporte a un dispositif destine au refroidisseent des fluides de processus ou d'operation, dans lequel la surchauffe localisee ou generale du fluide de refroidissement doit etre evitee. Elle s'applique particulierement au cas du fluide de purge du generateur de vapeur d'une centrale nucleaire. L'objet de l'invention est de creer un dispositif d'echange thermique qui utilise uniquement des composants statistiques et qui, par suite, est parfaitement fiable tout en restant simple et relativement economique. Ce dispositif comprend un echangeur thermique a regeneration (ledit echangeur thermique presentant un circuit primaire et un cricuit secondaire), et un echangeur thermique a triple flux comprenant trois circuits. Le premier et le deuxieme circuit sont en communication fluide avec le circuit primaire et le circuit secondaire de l'echangeur thermique a regeneration. La communication fluide entre l'echangeur de chaleur a regeneration et l'echangeur de chaleur a triple circuit est telle que le fluide de processus passe d'abord dans l'un des circuits de l'echangeur thermique a regenration ou il est refroidi, ensuite dans l'un des deux premiers circuits de l'echangeur thermique a triple circuit ou il est refroidi davantage, puis dans l'autre des circuits dudit echangeur a regeneration ou il est rechauffe, et enfin a travers l'autre des deux premiers circuits de l'echangeur thermique a triple circuit ou il se trouve refroidi a nouveau. Un fluide de refroidissement passe dans le troisieme circuit afin de refroidir ledit fluide de processus

1975-05-15

310

Radiative heat exchange between surfaces  

International Nuclear Information System (INIS)

[en] The geometrical features of radiative heat exchange between surfaces are discussed first by developing various radiation shape factor relations. The governing equations for enclosures with diffusely emitting and diffusely reflecting surfaces, as well as the equations for enclosures with gray surfaces having specular component of reflectivity are introduced next. Finally, a simplified model for enclosures with isothermal surfaces under the assumption of uniform radiosity over the surfaces is discussed, and various working relations for different conditions are presented

1986-07-04

311

Analysis of horizontal mantle heat exchangers in solar water heating systems  

Energy Technology Data Exchange (ETDEWEB)

The characteristics of horizontal mantle heat exchangers are investigated for application in thermosyphon solar water heaters. An experimental model of a horizontal mantle heat exchanger was used to evaluate the flow patterns in the annular passageways and the heat transfer into the inner tank. Flow visualisation was used to investigate the flow structure, and heat transfer was measured for isothermal inner tank conditions. A numerical model of the flow and heat transfer in the annular passageway was developed and used to evaluate the heat flux distribution over the surface of the inner tank. The numerical results indicate that configurations of mantle heat exchangers used in current solar water heater applications degrade thermal stratification in the inner tank. The effects of inlet flow rate, temperature and connecting port location are quantified. (Author)

Morrison, Graham L.; Nasr, Asghar; Behnia, Masud; Rosengarten, Gary [New South Wales Univ., Solar Thermal Energy Lab., Sydney, NSW (Australia)

1998-09-01

312

Heat flow in Oklahoma  

Science.gov (United States)

Twenty new heat flow values are incorporated, along with 40 previously published data, into a heat flow map of Oklahoma. The new heat flow data were estimated using previous temperature measurements in boreholes made by American Petroleum Institute researchers and 1,498 thermal conductivity measurements on drill cuttings. The mean of 20 average thermal gradients is 30.50sp°C/km. In general, thermal gradients increase from SW (14.11sp°C/km) to NE (42.24sp°C/km). The range of 1,498 in situ thermal conductivity measurements (after corrections for anisotropy, in situ temperature, and porosity) is 0.90-6.1 W/m-K; the average is 1.68 W/m-K. Estimated near-surface heat flow (±20%) at 20 new sites in Oklahoma varies between 22 ± 4 mW/msp2 and 86 ± 17 mW/msp2; the average is 50 mW/msp2. Twenty-seven new heat-generation estimates, along with 22 previously published data, are used to create a heat generation map of Oklahoma. The range of heat production estimates is 1.1-3.5 muW/msp3, with an average of 2.5 muW/msp3. The heat flow regime in Oklahoma is primarily conductive in nature, except for a zone in northeast. Transient effects due to sedimentary processes and metamorphic/igneous activity, as well as past climatic changes, do not significantly influence the thermal state of the Oklahoma crust. Heat flow near the margins of the Arkoma and Anadarko Basins may be depressed or elevated by 5-13 mW/msp2 by refraction of heat from sedimentary rocks of relatively low thermal conductivity (1-2 W/m-K) into crystalline basement rocks of relatively high thermal conductivity (˜3-4 W/m-K). The heat generation-heat flow relationship shows a modest correlation. The relatively high heat flow (˜70-80 mW/msp2) in part of northeastern Oklahoma suggests that the thermal regime there may be perturbed by regional groundwater flow originating in the fractured outcrops of the Arbuckle-Simpson aquifer in the Arbuckle Mountains.

Cranganu, Constantin

313

Optimization of heat exchanger for indirectly heated water heater  

Science.gov (United States)

Due to the optimization of geometrical parameters of the heat exchanger in indirect heated water heaters created a mathematical model of heating hot water, by which I have subsequently made the simulation of the device to change its geometrical parameters. Based on these results, the impacts of the geometrical parameters affect the performance of the heat exchanger. The results of the optimization to create a CFD model which watched at the behavior of optimized heat exchanger for indirect heated water heaters.

Kaduchová, Katarína; Lenhard, Richard; Janda?ka, Jozef

2012-04-01

314

Design of intermediate heat exchanger for PFBR  

International Nuclear Information System (INIS)

Prototype fast breeder reactor (PFBR) is a sodium cooled 500 MWe pool type reactor. It has three heat transfer circuits viz. primary sodium circuit, secondary sodium circuit and water- steam circuit. The main vessel contains the pool of sodium and houses all the components of the primary sodium circuit. Two numbers of primary sodium pumps and four numbers of intermediate heat exchangers (IHX) have been provided. The nuclear heat generated in the core is transferred to secondary sodium in IHX by circulation of primary sodium. There are two secondary sodium circuits. Each circuit contains one sodium pump, one surge tank and four steam generators (in parallel) and is connected to two IHXs in the reactor. The secondary sodium circuits transfer the heat to water/steam in steam generators (SG). Super heated steam produced in the SGs is used to drive the turbo-alternator set to generate power. The IHX is a very important component of the reactor because it forms the boundary between radioactive primary sodium in the reactor pool and non-radioactive secondary sodium. The IHX is a counter flow shell-and-tube heat exchanger. The IHX is designed to meet the specified design requirements and constraints. This involves thermal, hydraulic, and structural design. In this paper, the design features, design conditions and design of IHX for PFBR are described. 4 figs., 3 tabs.

1996-01-01

315

Preliminary SP-100/Stirling heat exchanger designs  

Energy Technology Data Exchange (ETDEWEB)

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

316

Preliminary SP-100/Stirling heat exchanger designs  

International Nuclear Information System (INIS)

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.

1993-01-01

317

Preliminary SP-100/Stirling heat exchanger designs  

International Nuclear Information System (INIS)

[en] 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

1994-01-01

318

Frost formation on fin-and-tube heat exchangers. Pt. 1. Modeling of frost formation on fin-and-tube heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

In this study, the heat and mass transfer characteristics of heat exchangers during frost formation process are analyzed numerically. Unsteady heat and mass transfer coefficients of the air side, heat transfer coefficient of the refrigerant side, air-frost layer interface temperature, the surface efficiency of the heat exchanger and the mass flow rate of the frost accumulated on the heat exchanger surface are calculated. The total conductivity (UA) and pressure drop of the heat exchanger are reported for different air inlet temperature, relative humidity, air mass flow rate and the refrigerant temperature. (author)

Seker, D.; Karatas, H. [Arcelik A.S., Istanbul (Turkey); Egrican, N. [Yeditepe University, Istanbul (Turkey)

2004-06-01

319

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

Science.gov (United States)

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.

1993-04-01

320

A core alternative[Heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The development of the efficient Core-in-kettle heat exchangers by Chart Heat Exchangers as an alternative to shell and tube exchangers is reported, and its use as condensers and reboilers in ethylene plants and refrigerant condensers and chillers in natural gas processing and liquid natural gas (LNG) plants are discussed. The novel technology is described with details given of the replacement of the tube bundle with a Chart brazed aluminium plate-fin heat exchanger core, the operation of the exchanger, the savings achieved by installing these heat exchangers in new or existing plants, and Core-in-Kettle retrofits of existing shell and tube heat exchangers. The limitations of the use of Core-in-Kettle heat exchangers to clean fluids typical of hydrocarbon processing, and temperature and pressure limitations are noted.

Weaver, R.H. [Chart Heat Exchangers, Wisconsin (United States)

2001-09-01

 
 
 
 
321

Sealing strips in tubular heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

This paper presents design data relating to sealing strips for tubular heat exchangers. Sealing strip shapes, locations, and gap widths (the distance between the sealing strip and the nearest tube) are evaluated as to the pressure drop they create and, more importantly, as to their heat transfer characteristics. Velocity data were collected using a laser-Doppler anemometry system for which the fluid within the test model flow loop was refractive index matched with the pyrex rods that made up the tube bundle. A normalized heat transfer coefficient for each test has been inferred from the local velocity field. Unexpected trends were found in the heat transfer and pressure drop results of the gap width tests. It was concluded that the rectangular sealing strip located at the seventh row with a gap equal to the difference between the tube pitch and the tube diameter was the most effective. The successful application of LDA in the test program introduces a powerful measuring technique for the flow field in and around tube banks. From the measurements, pressure drops and heat transfer coefficients may be deduced. In addition, the technique will prove to be of great value in field of flow-induced vibrations where detailed velocity data are required.

Taylor, C.E.; Currie, I.G. (Univ. of Toronto, Ontario (Canada))

1987-08-01

322

Operation of a plate-type heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

Osaka Gas has installed a plate-type heat exchanger as the cooler for the liquid circulating through a Fumaks type coke oven gas desulfurization facility. The plate-type construction was adopted after comparative evaluations of plate-type, spiral-type and shell-and-tube-type heat exchangers. Although the liquid flow rate through the Fumaks desulfurization equipment is approximately 14% less than the design flow rate, both the clean heat transfer coefficient (U/SUB/C) and the overall heat transfer coefficient (U/SUB/D) are in line with the original design values. 3 references.

Katagiri, K.; Yasuda, K.

1984-01-01

323

Online performance assessment of heat exchanger using artificial neural networks  

Directory of Open Access Journals (Sweden)

Full Text Available Heat exchanger is a device in which heat is transferred from one medium to another across a solid surface. The performance of heat exchanger deteriorates with time due to fouling on the heat transfer surface. It is necessary to assess periodically the heat exchanger performance, in order to maintain at high efficiency level. Industries follow adopted practices to monitor but it is limited to some degree. Online monitoring has an advantage to understand and improve the heat exchanger performance. In this paper, online performance monitoring system for shell and tube heat exchanger is developed using artificial neural networks (ANNs). Experiments are conducted based on full factorial design of experiments to develop a model using the parameters such as temperatures and flow rates. ANN model for overall heat transfer coefficient of a design/ clean heat exchanger system is developed using a feed forward back propagation neural network and trained. The developed model is validated and tested by comparing the results with the experimental results. This model is used to assess the performance of heat exchanger with the real/fouled system. The performance degradation is expressed using fouling factor (FF), which is derived from the overall heat transfer coefficient of design system and real system. It supports the system to improve the performance by asset utilization, energy efficient and cost reduction interms of production loss.

C. Ahilan, S. Kumanan, N. Sivakumaran

2011-01-01

324

Microchannel crossflow fluid heat exchanger and method for its fabrication  

Science.gov (United States)

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

325

Membrane and plastic heat exchangers performance  

Directory of Open Access Journals (Sweden)

Full Text Available The performance of a membrane-based heat exchanger utilizing porous paper as the heat and moisture transfer media is presented. The measured performance is compared with a plastic film heat exchanger. This novel heat exchanger is used in ventilation energy recovery systems. The results show that the sensible effectiveness is higher than the latent effectiveness. When a similar experiment was conducted using a plastic film heat exchanger surface instead of paper, where only heat is transferred, the sensible effectiveness values were lower than the effectiveness values recorded when the paper heat exchanger is used. Furthermore, energy analysis shows that utilizing a paper surface heat exchanger in a standard air conditioning system will lead to significant energy savings.

Mohammad Shakir Nasif; Graham L. Morrison; Masud Behnia

2005-01-01

326

A heat exchanger between forced flow helium gas at 14 to 18 K and liquid hydrogen at 20 K circulated by natural convection  

International Nuclear Information System (INIS)

[en] The Muon Ionization Cooling Experiment (MICE) has three 350-mm long liquid hydrogen absorbers to reduce the momentum of 200 MeV muons in all directions. The muons are then re-accelerated in the longitudinal direction by 200 MHz RF cavities. The result is cooled muons with a reduced emittance. The energy from the muons is taken up by the liquid hydrogen in the absorber. The hydrogen in the MICE absorbers is cooled by natural convection to the walls of the absorber that are in turn cooled by helium gas that enters at 14 K. This report describes the MICE liquid hydrogen absorber and the heat exchanger between the liquid hydrogen and the helium gas that flows through passages in the absorber wall

2003-01-01

327

A heat exchanger between forced flow helium gas at 14 to 18 K andliquid hydrogen at 20 K circulated by natural convection  

Energy Technology Data Exchange (ETDEWEB)

The Muon Ionization Cooling Experiment (MICE) has three 350-mm long liquid hydrogen absorbers to reduce the momentum of 200 MeV muons in all directions. The muons are then re-accelerated in the longitudinal direction by 200 MHz RF cavities. The result is cooled muons with a reduced emittance. The energy from the muons is taken up by the liquid hydrogen in the absorber. The hydrogen in the MICE absorbers is cooled by natural convection to the walls of the absorber that are in turn cooled by helium gas that enters at 14 K. This report describes the MICE liquid hydrogen absorber and the heat exchanger between the liquid hydrogen and the helium gas that flows through passages in the absorber wall.

Green, M.A.; Ishimoto, S.; Lau, W.; Yang, S.

2003-09-15

328

NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger  

Energy Technology Data Exchange (ETDEWEB)

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

329

Heat Transport Study of the Laminar Heat Pipe Heat Exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this experiment is to analyze the performance of the Laminar Heat Pipe Heat Exchanger. The test samples were divided two groups, one is the metal corrugated sheet with heat pipe, and the other is the metal corrugated sheet only. By dipping these two group samples into hot water and to see the thermal image by Infrared thermal imager. The results shown the temperature risen of the sheet with heat pipe was faster than that of the sheet without heat pipe. In addition, the bigger of the temperature difference between hot water temperature and ambient temperature, the quicker of the temperature risen for the metal corrugated sheet, and the temperature of the metal corrugated sheet were homogenous as well. For example, when the water temperature is 30?, ambient temperature is 20?, the metal corrugated sheet with heat pipe rise rapidly to 26? within 1 minute, while the metal corrugated sheet without heat pipe rise to 22? only, this temperature difference would be more obvious with the increasing of the hot water temperature. When the hot water temperature is up to 40?, the metal corrugated sheet with heat pipe rise rapidly to 31? within 1 minute, while the metal corrugated sheet without het pipe is still rise up to 22? only. When the hot water temperature is up to 50?, The metal corrugated sheet with heat pipe rise rapidly to 33? within 1 minute, while the sheet without heat pipe still keep at 22?, the results shown the heat pipe affect the temperature rising speed is obvious, and it also implying heat pipe is a very important parameter for the heat transfer rate of the Laminar Heat Pipe Heat Exchanger.

Wei-Keng Lin; Ke Chine Liaw; Min-Zen Tsai; Min-Gung Chu

2012-01-01

330

Heat exchanger fouling and corrosion evaluation  

Science.gov (United States)

The experimental determination of acid corrosion and fouling effects upon a series of tubular heat exchanger modules exposed to the exhaust gases from a large (8900-hp) diesel engine, with different fin geometries and materials was studied. A study of the exhaust gas analysis was undertaken and acid dew point temperatures were determined. Heat exchanger test modules were then operated with metal surface temperatures below the acid dew point to allow for acid condensation and fouling. A continuous soot buildup was observed on the heat exchanger, as a function of the diesel engine operating time, heat transfer metal surface temperature, and fin geometry. The corrosion effects on the heat exchangers were minimal.

Deanda, E.

1981-10-01

331

Fluid dynamical considerations on heat exchanger networks  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis and analysis of heat exchanger networks are issues of great industrial interest due to the possibilities of decreasing plant costs, through the reduction of the utilities consumption and/or the number of equipments, in a grassroot design or retrofitting an existent network. The present paper explores a new design algorithm based on the Total Annual Cost (TAC) optimization for a thermal equipment, with mean tubeside and shellside flow velocities constraints, studying also the influence of pumping cost in the network’s final cost.

A. J. M. Vieira; F. L. P. Pessoa; E. M. Queiroz

2000-01-01

332

Fluid dynamical considerations on heat exchanger networks  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis and analysis of heat exchanger networks are issues of great industrial interest due to the possibilities of decreasing plant costs, through the reduction of the utilities consumption and/or the number of equipments, in a grassroot design or retrofitting an existent network. The present paper explores a new design algorithm based on the Total Annual Cost (TAC) optimization for a thermal equipment, with mean tubeside and shellside flow velocities constraints, studying also the influence of pumping cost in the network?s final cost.

Vieira A. J. M.; Pessoa F. L. P.; Queiroz E. M.

2000-01-01

333

Acoustic resonance in heat exchanger tube bundles  

Energy Technology Data Exchange (ETDEWEB)

A series of experiments has been made on aeroacoustic tones produced by flow over tubes in a duct. The sound is characterized by the onset of a loud and persistent acoustic resonance. The acoustic resonance occurs at the frequency of the acoustic modes. The magnitude and extent of the resonance are functions of tube pattern and tube pitch. The sound levels increase in proportion with Mach number, dynamic head and pressure drop. A design procedure for predicting the magnitude of the sound within the tube array is presented. Methods of resonance avoidance are illustrated. An example is made for a large petrochemical heat exchanger.

Blevins, R.D. (Rohr Industries, San Diego, CA (United States))

1994-02-01

334

Design of a liquid metals heat exchanger  

International Nuclear Information System (INIS)

The method that has been used in this design is that of the summation of the partial resistances to the heat transference, permitting to obtain the value of the total coefficient of heat transfer which will be equal to the reciprocal of the summation of all the resistances. The obtained exchanger is of tubes and rod type shield with the primary sodium flowing through the tubes and the secondary sodium flowing in counter-current through the shield. The shield has a nominal diameter of 6 inches and the bundle of tubes is formed by 31 tubes with a nominal diameter of 1/2 inch. The shield as well as the tubes are of stainless steel. The total heat transfer area is of 7.299 square meters, and the effective length of heat transfer is of 3.519 meters. After sizing the interchanger it was proceeded to simulate its functioning through a computer program in which the effective length of heat transfer was divided in 150 points in such a way that according to the integration of the distinct parameters along these points a comparison can finally be made between the design values and those of the simulation, which show a concordance. (author)

1976-01-01

335

Numerical simulation of two phase flows in heat exchangers; Simulation numerique des ecoulements diphasiques dans les echangeurs  

Energy Technology Data Exchange (ETDEWEB)

The report presents globally the works done by the author in the thermohydraulic applied to nuclear reactors flows. It presents the studies done to the numerical simulation of the two phase flows in the steam generators and a finite element method to compute these flows. (author)

Grandotto Biettoli, M

2006-04-15

336

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

Science.gov (United States)

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

Taler, Dawid

2013-08-01

337

Thermal behavior of a heat exchanger module for seasonal heat storage  

DEFF Research Database (Denmark)

Experimental and theoretic investigations are carried out to study the heat transfer capacity rate of a heat exchanger module for seasonal heat storage with sodium acetate trihydrate (SAT) supercooling in a stable way. A sandwich heat storage test module has been built with the phase change material (PCM) storage box in between two plate heat exchangers. Charge of the PCM storage is investigated experimentally with solid phase SAT as initial condition. Discharge of the PCM storage with the presence of crystallization is studied experimentally. Fluid flow and heat transfer in the PCM module are theoretically investigated by Computational Fluid Dynamics (CFD) calculations. The heat transfer rates between the PCM storage and the heating fluid/cooling fluid in the plate heat exchangers are determined. The CFD calculated temperatures are compared to measured temperatures. Based on the studies, recommendations on how best to transfer heat to and from the seasonal heat storage module are given.

Fan, Jianhua; Furbo, Simon

2012-01-01

338

Simultaneous synthesis of flexible heat exchanger network  

Energy Technology Data Exchange (ETDEWEB)

A framework is presented for generating flexible heat exchanger networks (HENs) over a specified range of variations in the flow rates and temperatures of the streams. The flexible HEN is synthesised using a combination of a multiperiod simultaneous MINLP model and search algorithms, where the total annual costs due to utility duties, exchanger areas and selection of matches are optimised. The simultaneous HEN synthesis allows the data to be distributed according to a probability distribution and it does not rely on the concept of pinch point. Both search algorithms involve a developed multiperiod NLP/LP model where utility costs are minimised. The proposed procedures are explained through an example including variations resulting in a network with variable splits and bypasses. This framework results in a HEN working under variations without losing stream temperature targets while keeping an economically optimal energy integration. (Author)

Aaltola, Juha [Helsinki Univ. of Technology,Hut (Finland)

2002-06-01

339

OPTIMASI KINERJA HEAT EXCHANGER TABUNG KOSENTRIS  

Directory of Open Access Journals (Sweden)

Full Text Available Heat exchanger effectiveness is affected by some factors such as pipe shape, temperature, cold and hot air direction and velocity entering the heat exchanger. Research about heat exchanger has been done but the significance level of the heat exchanger effectiveness resulted is unknown. A designed experiment should be done to optimize the performance of concentric tube heat exchanger with measured significance level. From the analysis of result of previous experiment, factors that seem to affect the effectiveness are velocity of cold air, velocity of hot air, and pipe shape of heat exchanger used (outlet and inlet similar to U, S and L shape). Experimental design that is used here is three-level factorial design. On the arrangement of factors as follows: velocity of cold air = 4 m/s, velocity of hot air = 7 m/s, and pipe of S shape, optimum effectiveness gained at significance level of 95 % is 0,39098. Abstract in Bahasa Indonesia : Efektifitas heat exchanger tabung konsentris bisa dipengaruhi oleh beberapa faktor, antara lain bentuk pipa, temperatur, arah aliran dan kecepatan udara masuk baik dingin maupun panas. Penelitian mengenai heat exchanger telah dilakukan sebelumnya namun tingkat signifikasi dari efektifitas heat exchanger yang dihasilkan tidak diketahui. Suatu eksperimen yang terancang perlu dilakukan untuk mengoptimalkan kinerja dari heat exchanger tabung kosentris dengan tingkat signifikasi yang terukur. Dari analisa terhadap hasil eksperimen terdahulu, tampak bahwa faktor yang berpengaruh adalah kecepatan udara dingin, kecepatan udara panas dan bentuk pipa heat exchanger (outlet dan inlet menyerupai bentuk U, S dan L) yang digunakan. Rancangan eksperimen yang digunakan ialah rancangan faktorial 3 level. Pada pengaturan level faktor sebagai berikut: kecepatan udara dingin = 4 m/det, kecepatan udara panas = 7 m/det dan bentuk tabung yang digunakan ialah pipa berbentuk S, diperoleh efektifitas optimum pada tingkat signifikasi 95 % = 0,39098. Kata kunci: heat exchanger, desain eksperimen, efektifitas

Didik Wahjudi

2000-01-01

340

Resultant characteristics of internal heat exchange in rotary furnaces  

Energy Technology Data Exchange (ETDEWEB)

An experimental study was made of the heat exchange characteristics, thermal conductivity and efficiency coefficient of the radiation chambers of rotary furnaces. The tests involved finding the heat to the burner, heat absorbance of individual parts and the entire heating surface, the temperature distribution in the burner and the heat flows along the radiation pipes. Local temperatures in the burner were measured with a thermal probe. Temperatures of the tube shielding were measured with the aid of a radiation pyrometer. Heat flow values were determined from experimental values of radiation pipe temperatures, while efficiency coefficient values were determined from the pipe surfaces to the heated raw material. It was found that the radiative component dominates in the overall heat transfer to the radiation pipes. Reducing the air flow rate was shown to intensify the heat exchange in the radiation chamber and contribute to increased heater efficiencies; increasing the temp. of the emitting burners and reducing the temp. of the radiation pipes serves to increase the heat output in the burner; reducing the thermal stress of the burner area and shifting the maximum heat absorption to the crown of the burner increases the heat exchange efficiency in the radiation chamber. Based on these results, recommendations have been developed (and will soon be introduced) to raise reliability and efficiency of rotary furnaces.

Dolotovskii, B.V.; Molokanov, Yu.K.; Sedelkin, V.M.

1981-01-01

 
 
 
 
341

Feasibility study of improved heat exchanger  

International Nuclear Information System (INIS)

Generally shell and tube type heat exchangers have been used widely for many years in the auxiliary cooling systems of nuclear power plants. Recently, however, in general industrial facilities and so on many plate heat exchangers excellent in heat transfer performance have been used, compared with shell and tube heat exchangers, and their heat exchanger bodies and cooling system facilities have been rationalized. We carried out confirmation tests on the plate type heat exchangers in structural strength, aseismatic strength, heat transfer performance and maintenance regarding their application to nuclear power plants. As a result, we have confirmed that they can be applied to seawater systems of actual plants. The tests further provided useful information on their actual operation. (author)

1991-01-01

342

Basic design methods of heat exchangers  

International Nuclear Information System (INIS)

The most common heat exchanger design problems are rating and sizing problems. In this paper the basic design methods for two-fluid direct-transfer heat exchangers are reviewed. A heat exchanger is a device in which heat is transferred from a hot fluid to a cold fluid. In its simplest form, the two fluids mix and leave at an intermediate temperature determined by the conservation of energy. This device is not truly a heat exchanger but rather a mixer. In most applications, the fluids do not mix but transfer heat through a separating wall that takes on a wide variety of geometries. Three categories are normally used to classify heat exchangers: recuperators, regenerators, and direct-contact apparatus

1991-01-01

343

Simulation of cryogenic helium facility heat exchanger and experimental data  

International Nuclear Information System (INIS)

The results of verificatory calculations made with SHESE computer program for a cryogenic coiled tube (finned with copper wire) Heat Exchanger (HE) are presented. The tube and shell side flows nonuniform distribution across that exchange surface, the difference between a real coiled multitube HE flow arrangement and ideal counterflow are taken into account. The generalized computational results on the influence of the number of turns and paths on the HE efficiency at different flow capacitance ratios are presented. The experimental and computed data are compared. The SHESE program feasibility to predict achievable heat load of cryogenic highly efficient HE at designing stage is shown. 6 refs.; 4 figs.

1991-01-01

344

Heat exchanger development in the 1980s  

Energy Technology Data Exchange (ETDEWEB)

Heat exchanger development plays an important role in nuclear engineering. The author discusses improvements in materials for better thermal efficiency and considers safety aspects and future prospects.

Amacker, S. (Sulzer Bros. Ltd., Winterthur (Switzerland))

1982-01-01

345

Temperature control system for a J-module heat exchanger  

International Nuclear Information System (INIS)

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

1978-01-01

346

Modelling of natural-convection driven heat exchangers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract: A lumped model is developed for shell-and-tube heat exchangers driven by natural convection, which is based on a one-dimensional approximation. The heat flux is driven by the logarithmic mean temperature difference. The volumetric air flow rate is driven by the buoyant force. Based on ...

Dirkse, M.H.; Loon, W.K.P., van; Stigter, J.D.; Bot, G.P.A.

347

Process for oil shale retorting using gravity-driven solids flow and solid-solid heat exchange  

Science.gov (United States)

A cascading bed retorting process and apparatus are disclosed in which cold raw crushed shale enters at the middle of a retort column into a mixer stage where it is rapidly mixed with hot recycled shale and thereby heated to pyrolysis temperature. The heated mixture then passes through a pyrolyzer stage where it resides for a sufficient time for complete pyrolysis to occur. The spent shale from the pyrolyzer is recirculated through a burner stage where the residual char is burned to heat the shale which then enters the mixer stage.

Lewis, A.E.; Braun, R.L.; Mallon, R.G.; Walton, O.R.

1983-09-21

348

Process for oil shale retorting using gravity-driven solids flow and solid-solid heat exchange  

Energy Technology Data Exchange (ETDEWEB)

A cascading bed retorting process and apparatus in which cold raw crushed shale enters at the middle of a retort column into a mixer stage where it is rapidly mixed with hot recycled shale and thereby heated to pyrolysis temperature. The heated mixture then passes through a pyrolyzer stage where it resides for a sufficient time for complete pyrolysis to occur. The spent shale from the pyrolyzer is recirculated through a burner stage where the residual char is burned to heat the shale which then enters the mixer stage.

Lewis, Arthur E. (Los Altos, CA); Braun, Robert L. (Livermore, CA); Mallon, Richard G. (Livermore, CA); Walton, Otis R. (Livermore, CA)

1986-01-01

349

Heat flow in Oklahoma  

Energy Technology Data Exchange (ETDEWEB)

Oklahoma is one area in which terrestrial heat flow data are sparse. The thermal state of the southern mid-continent, however, is a key to understanding several important geologic problems. These include thermal anomalies associated with Paleozoic fluid migrations and the formation of Mississippi Valley-type lead-zinc deposits, the thermal evolution of the Arkoma and Anadarko sedimentary basins, and the history of hydrocarbon generation and overpressuring in the Anadarko Basin. In the late 1920s, the American Petroleum Institute made a set of equilibrium temperature logs in idle oil wells. These temperature data are generally regarded as being high quality, accurate estimates of rock temperature and they cover the entire central part of Oklahoma. Average thermal gradients in the API survey range from 14 to 43 {sup 0}C/km (average 31.2 {sup 0}C/km) over depth intervals that extend from the surface to a an average depth of 961 m. Geothermal gradients decrease from NNE to SSW. The observed change in thermal gradients could be due to a number of factors. The change in thermal gradients could simply reflect changes in lithology and thermal conductivity. Alternatively, the variation in thermal gradients could be indicative of a change in heat flow related perhaps to variations in the concentration of radioactive heat-producing elements in the crust or heat transport by one or more regional groundwater flow systems. We are proceeding to reduce ambiguity in interpretation by estimating heat flow from thermal conductivity measurements on drill cuttings and heat production from available gamma-ray logs which penetrate basement rocks.

Cranganu, C.; Deming, D. [Univ. of Oklahoma, Norman, OK (United States)

1996-12-31

350

Radiant energy heat exchanger system  

Energy Technology Data Exchange (ETDEWEB)

A radiant energy heat exchanger is described. It comprises a panel structure including a base having a multiplicity of transversely spaced barrier walls extending longitudinally between the end portions of the panel structure. An inner sheet form wall section is sealingly connected with each pair of adjacent barrier walls providing a plurality of inner fluid containing channel spaces extending longitudinally between the end portions of the panel structure, a concavo-convex outer sheet form wall section sealingly connected with each pair of adjacent barrier walls, and an intermediate sheet form wall section between the associated inner and outer wall sections defining a multiplicity of outer and intermediate fluid containing spaces in outwardly disposed relation with respect to the multiplicity of inner fluid containing channel spaces.

Mcalister, R.E.

1981-07-21

351

Characteristics of cooling water fouling in a heat exchange system  

International Nuclear Information System (INIS)

This study investigated the efficiency of the physical water treatment method in preventing and controlling fouling accumulation on heat transfer surfaces in a laboratory heat exchange system with tap and artificial water. To investigate the fouling characteristics, an experimental test facility with a plate type heat exchange system was newly built, where cooling and hot water moved in opposite directions forming a counter-flow heat exchanger. The obtained fouling resistances were used to analyze the effects of the physical water treatment on fouling mitigation. Furthermore, the surface tension and pH values of water were also measured. This study compared the fouling characteristics of cooling water in the heat exchange system with and without the mitigation methods for various inlet velocities. In the presence of the electrode devices with a velocity of 0.5m/s, the fouling resistance was reduced by 79% compared to that in the absence of electrode devices

2008-01-01

352

Maximum entropy generation of in-series connected heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Theoretical analysis of entropy generation and availability destruction of 'n' similar cocurrent or counter-current heat exchangers connected in series are presented. A criterion for comparing the relative performance of any number of in-series connected similar heat exchangers is developed. The effect of different influencing parameters such as the number of connected heat exchangers, the individual effectiveness of each unit, the heat capacity rate ratio and flow arrangement on the quality of heat exchange are presented. It is found that, the maximum of availability destruction (maximum entropy generation) for in-series-connected similar cocurrent heat exchangers is obtained at {epsilon}* = 1/(1+{delta}). However, for counter-current heat exchangers connected in-series; {epsilon}{sub n} {approx} = 1/({sigma} {sup {delta}}{sup i/n}). This analysis might be useful for a proper choice of the number of heat exchangers to be connected together and the choice for the best operating conditions. (Author)

Nafey, Ahmed Safwat [Suez Canal Univ., Engineering Science Dept., Suez (Egypt)

2000-07-01

353

Performance of heat exchangers used in whole body perfusion circuits.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 infor...

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

354

Microbial fouling control in heat exchangers  

International Nuclear Information System (INIS)

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

1991-01-01

355

Investigation into fouling factor in compact heat exchanger  

Directory of Open Access Journals (Sweden)

Full Text Available Fouling problems cannot be avoided in many heat exchanger operations, and it is necessary to introduce defensive measures to minimize fouling and the cost of cleaning. The fouling control measures used during either design or operation must be subjected to a thorough economic analysis, taking into consideration all the costs of the fouling control measures and their projected benefits in reducing costs due to fouling. Under some conditions, nearly asymptotic fouling resistances can be obtained, and this suggests a somewhat different approach to the economics. Fouling is a generic term for the deposition of foreign matter on a heat transfer surface. Deposits accumulating in the small channels of a compact heat exchanger affect both heat transfer and fluid flow. Fouling deposits constricting passages in a compact heat exchanger are likely to increase the pressure drop and therefore reduce the flow rate. Reduced flow rate may be a process constraint; it reduces efficiency and increases the associated energy use and running costs. Maintenance costs will also increase. Fouling remains the area of greatest concern for those considering the installation of compact heat exchangers. The widespread installation of compact heat exchangers has been hindered by the perception that the small passages are more strongly affected by the formation of deposits. In this paper different types of fouling and treatment are presented.

Masoud Asadi; Ramin Haghighi Khoshkhoo

2013-01-01

356

Plate heat exchangers design, applications and performance  

CERN Multimedia

Heat exchangers are important, and used frequently in the processing, heat and power, air-conditioning and refrigeration, heat recovery, transportation and manufacturing industries. Such equipment is also important in electronics cooling and for environmental issues like thermal pollution, waste disposal and sustainable development.The present book concerns plate heat exchangers (PHEs), which are one of the most common types in practice. The overall objectives are to present comprehensive descriptions of such heat exchangers and their advantages and limitations, to provide in-depth thermal and

Wang, L; Manglik, R M

2007-01-01

357

Design of heat exchangers by numerical methods  

International Nuclear Information System (INIS)

Differential equations describing the heat tranfer in shell - and tube heat exchangers are derived and solved numerically. The method of ?T sub(lm) is compared with the proposed method in cases where the specific heat at constant pressure, Cp and the overall heat transfer coefficient, U, vary with temperature. The error of the method of ?T sub (lm) for the computation of the exchanger lenght is less than + 10%. However, the numerical method, being more accurate and at the same time easy to use and economical, is recommended for the design of shell-and-tube heat exchangers. (Author)

1981-12-18

358

Heat exchange apparatus for a reactor  

Energy Technology Data Exchange (ETDEWEB)

A heat exchange apparatus for transferring heat from a reactor gas coolant to a secondary fluid medium is described. The heat exchange apparatus comprises an elongated vertically extending hole in a concrete shield. Supported within the hole in spaced relation to the wall thereof is an elongated vertical extending tubular shroud which shroud has a gas entry at its lower end and a gas exit at its upper end. Means are provided for dividing the annular space between the shroud 16 and the wall of the hole into an upper and a lower region. Disposed in the shield is an inlet for reactor coolant which communicates with the lower region and is positioned vertically so as to be spaced above the gas entry to the shroud to thereby suppress natural convection during nonoperating standby conditions of the apparatus. An outlet for reactor coolant, which is disposed in the shield, communicates with the upper region. A plurality of vertically extending, spaced apart bayonet tube assemblies are supported within the shroud and means are provided for passing secondary fluid through these tube assemblies. A circulator is provided for causing the reactor coolant to flow in through the inlet, downward in the annular space, into the shroud through the gas entry, upward through the shroud and out through the outlet during emergency conditions of the reactor.

Gertsch, P.R.; McDaniels, J.D.; Thurston, G.C.

1980-09-30

359

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

Science.gov (United States)

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

Dahl, Scott David

1998-11-01

360

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

Energy Technology Data Exchange (ETDEWEB)

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

Dahl, S.; Davidson, J.

1999-07-01

 
 
 
 
361

Optimization of heat exchanger for indirectly heated water heater  

Directory of Open Access Journals (Sweden)

Full Text Available Due to the optimization of geometrical parameters of the heat exchanger in indirect heated water heaters created a mathematical model of heating hot water, by which I have subsequently made the simulation of the device to change its geometrical parameters. Based on these results, the impacts of the geometrical parameters affect the performance of the heat exchanger. The results of the optimization to create a CFD model which watched at the behavior of optimized heat exchanger for indirect heated water heaters.

Kaduchová Katarína; Lenhard Richard; Janda?ka Jozef

2012-01-01

362

Conjugate heat and mass transfer in heat mass exchanger ducts  

CERN Multimedia

Conjugate Heat and Mass Transfer in Heat Mass Exchanger Ducts bridges the gap between fundamentals and recent discoveries, making it a valuable tool for anyone looking to expand their knowledge of heat exchangers. The first book on the market to cover conjugate heat and mass transfer in heat exchangers, author Li-Zhi Zhang goes beyond the basics to cover recent advancements in equipment for energy use and environmental control (such as heat and moisture recovery ventilators, hollow fiber membrane modules for humidification/dehumidification, membrane modules for air purification, desi

Zhang, Li-Zhi

2013-01-01

363

Experimental investigation of a manifold heat-pipe heat exchanger  

International Nuclear Information System (INIS)

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

1995-01-01

364

Optimum geometry of MEMS heat exchanger for heat transfer enhancement  

Directory of Open Access Journals (Sweden)

Full Text Available The study is based on an analysis of MEMS heat exchanger of three different geometries: wavy, triangular and rectangular using water as test fluid. The problem is solved using finite element method. The aim of this analysis is to evaluate the performance of MEMS heat exchanger for different geometry and to obtain an optimum design for better heat enhancement. It is apparent from this work that rectangular surface heat exchanger shows the best performance for heat enhancement technique in comparison to other geometry. Moreover, it is also easy to manufacture. Therefore, the rectangular surface may be used instead of other configurations of heat transfer surfaces. In this analysis, emphasis is given on enhancing heat transfer area of MEMS heat exchanger by reducing the pitch which shows that 0.475 mm is the optimum pitch as further decrease of pitch length does not have any significant effect on the effectiveness and heat transfer.

Nusrat J. Chhanda; Muhannad Mustafa; Maglub Al Nur

2010-01-01

365

Solar water heating system and heat exchanger therefor  

Energy Technology Data Exchange (ETDEWEB)

In a solar water system including a solar collector prevention of damage to the collector during freezing conditions is achieved by providing a relatively small independent heat exchanger between the solar collector and the water heater and a vacuum breaking system whereby the water in the solar collector is drained into the heat exchanger. The heat exchanger is connected to a thermal siphon arrangement with the water heater.

Koskela, M.O.

1982-04-27

366

Graphite Foam Heat Exchangers for Thermal Management  

Energy Technology Data Exchange (ETDEWEB)

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

Klett, J.W.

2004-06-07

367

Heat exchange intensification in evaporators of the ship refrigerating machinery with application of belt turbulence promoters  

Directory of Open Access Journals (Sweden)

Full Text Available The search of methods of intensification of the heat exchange process at boiling in evaporators of refrigerators is made to decrease mass-dimension pa-rameters of heat exchange equipment. The heat exchange process at boiling within belt six-ray turbulence promoter, made as a six-ray star is investigated. The results of the model experiment for hydrodynamics and heat exchange of two-phase flow observation are presented.

Bukin Vladimir Grigorievich; Kuzmin Andrey Yurievich; Proshkin Oleg Vladimirovich

2009-01-01

368

Condensing heat exchangers for maximum boiler efficiency  

Energy Technology Data Exchange (ETDEWEB)

Until now, boiler efficiency has been limited due to the minimum temperature allowed at the stack. Heat lost up the stack was in exchange for keeping the flue gas temperature above the water vapor dew point. If water vapor was allowed to condense out, rapid deterioration, due to acid corrosion, of the outlet duct and stack would result. With the development of the condensing heat exchanger, boiler efficiency can now exceed 90%. Approximately 1% gain in boiler efficiency can be expected for every 40 F (4.5 C) reduction in flue gas stack temperature. In the CHX{reg_sign} condensing heat exchanger, all gas wetted surfaces are covered with DuPont Teflon{reg_sign}. The Teflon covered heat exchanger surfaces are impervious to all acids normally resulting from the combustion of fossil fuels. This allows the flue gas to be cooled to below the water vapor dew point with no subsequent corrosion of the heat exchanger surfaces.

Johnson, D.W.; DiVitto, J.G.; Rakocy, M.E. [Babcock and Wilcox Co., Barberton, OH (United States). Environmental Equipment Div.

1994-12-31

369

Thermal and hydraulic performance of a graphite block heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

A test rig has been assembled to investigate the thermodynamic and hydraulic performance of a cylindrical graphite block heat exchanger consisting of three graphite blocks and a steel shell. The flow pattern in the heat exchanger was triple cross-flow on the shell-side (service side) with one pass per block and a single pass on the tube-side (process side). Overall heat transfer coefficients and pressure drops have been measured for a range of operating conditions. Shell-side leakage flows were significant, with values up to 19% with water and 38% with a heat transfer oil. Corresponding increases in the overall heat transfer coefficient withouth leakage flow were 8 and 21%, respectively. The mean difference between the theoretical and experimental overall heat transfer coefficients for the runs with leakage flow does not exceed 6% with water as the shell-side liquid. With oil the error does not exceed 8%. Pressure drop models were developed for both the shell-side and tube-side of the heat exchanger. The tube-side model predicted the pressure drop with a mean error of 5%. Errors within 20% can be expected for the shell-side pressure drop model. The pressure drop on the shell-side depends on a number of different losses and it is therefore difficult to be modelled accurately. (orig.)

Schou, G. [Auckland Univ. (New Zealand). Dept. of Chemical and Materials Engineering; Deans, J. [Auckland Univ. (New Zealand). Dept. of Mechanical Engineering; Kuenzel, J. [SGL Technik GmbH, Meitingen (Germany); Mueller-Steinhagen, H. [Surrey Univ., Guildford (United Kingdom). Dept. of Chemical and Process Engineering

1997-09-01

370

Compact interior heat exchangers for CO{sub 2} mobile heat pumping systems  

Energy Technology Data Exchange (ETDEWEB)

The natural refrigerant carbon dioxide (CO{sub 2}) offers new possibilities for design of flexible, efficient and environmentally safe mobile heat pumping systems. As high-efficient car engines with less waste heat are developed, extra heating of the passenger compartment is needed in the cold season. A reversible transcritical CO{sub 2} system with gliding temperature heat rejection can give high air delivery temperature which results in rapid heating of the passenger compartment and rapid defogging or defrosting of windows. When operated in cooling mode, the efficiency of transcritical CO{sub 2} systems is higher compared to common (HFC) air conditioning systems, at most dominant operating conditions. Several issues were identified for the design of compact interior heat exchangers for automotive reversible CO{sub 2} heat pumping systems. Among theses issues are: (1) Refrigerant flow distribution, (2) Heat exchanger fluid flow circuiting, (3) Air temperature uniformity downstream of the heat exchanger, (4) Minimization of temperature approach, (5) Windshield flash fogging due to retained water inside the heat exchanger, (6) Internal beat conduction in heating mode operation, and (7) Refrigerant side pressure drop In order to provide a basis for understanding these issues, the author developed a calculation model and set up a test facility and investigated different prototype heat exchangers experimentally.

Hafner, Armin

2003-07-01

371

Heat exchanger efficiently operable alternatively as evaporator or condenser  

Science.gov (United States)

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

372

Latent heat recovery on drying air in a malt house by means of an heat exchanger in polymer material  

Energy Technology Data Exchange (ETDEWEB)

Polymer material utilisation in gas heat exchangers is particularly attractive when condensations happen during the warmer fluid cooling. The polypropylene heat exchanger with a 5000 m{sup 2} exchange area has a very low pressure lost, for a 50 m.s{sup -1} gas flow, and leads to an energy saving of 30%. 4 tabs.

Grehier, A. (Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (FR)); Delatte, J.L.; Dehay, A.

1990-01-01

373

Experimental study on the heat transfer characteristics in corrugated and flat plate type heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

An experiment was performed to study heat transfer characteristics between corrugated heat exchanger and flat plate type one. While heat capacity(13.86kW) was provided constantly and the flow speed was varied from 2.8 to 17.9m/s, the temperature and the pressure drop were measured. Furthermore, heat transfer coefficient, Colburn factor and Nusselt number were calculated using them. With increase of the flow speed for both exchangers, the coefficient and the pressure drop increased, but Colburn factor decreased. The coefficient, pressure drop and Colburn factor of the corrugated type were all higher than those of the flat one, which is due to the flow interruption with recirculation and reattachment of the corrugated type. The empirical correlations of Nusselt number were suggested for the tested two heat exchangers.

Park, Jung Hun; Jeong, Yong Ki; Jeon, Chung Hwan; Chang, Young June [Busan National Univ., Busan (Korea, Republic of); Lim, Hyeok [DHT, Busan (Korea, Republic of)

2003-07-01

374

Experimental study on the heat transfer characteristics in corrugated and flat plate type heat exchanger  

International Nuclear Information System (INIS)

An experiment was performed to study heat transfer characteristics between corrugated heat exchanger and flat plate type one. While heat capacity(13.86kW) was provided constantly and the flow speed was varied from 2.8 to 17.9m/s, the temperature and the pressure drop were measured. Furthermore, heat transfer coefficient, Colburn factor and Nusselt number were calculated using them. With increase of the flow speed for both exchangers, the coefficient and the pressure drop increased, but Colburn factor decreased. The coefficient, pressure drop and Colburn factor of the corrugated type were all higher than those of the flat one, which is due to the flow interruption with recirculation and reattachment of the corrugated type. The empirical correlations of Nusselt number were suggested for the tested two heat exchangers.

2003-01-01

375

Influence of the yaw angle on heat transfer and pressure drop of helical type heat exchangers  

International Nuclear Information System (INIS)

The influence of the flow angle ? between the tube axis and the flow direction on heat transfer and pressure drop has been studied at 15 deg. ? ? ? 90 deg. (cross flow). The Reynolds number was varied in the range 2.103 ? Re ? 105. Experimental data are given for a number of tube banks of straight tubes as well as a helical type heat exchanger with a large thread pitch of the tubes. (author)

1988-01-01

376

Development and application of out-of-focus imaging in order to characterize heat and mass exchanges in two-phase flows  

International Nuclear Information System (INIS)

[en] The aim of this paper is to present the capacity of the out-of-focus imaging in order to measure droplets size in presence of heat and mass exchanges. It is supported with optical simulations first based on geometrical optics, and then with the Lorenz-Mie theory. Finally, this technique is applied in presence of heat and mass transfers in the TOSQAN experiment. (authors)

2007-01-01

377

Heat exchanger of a heat pipe type; Hito paipu shiki netsukokanki  

Energy Technology Data Exchange (ETDEWEB)

A previous apparatus to heat a gas with hot spring water as a heat source has a problem to cause a severe trouble or accident on the apparatus of a gas handling part due to the corrosion of the heat exchanger tube by sulfur content in the hot spring water and leakage of the hot spring water into the apparatus of the gas handling part. This invention aims to present a heat exchanger to heat a gas with hot spring water as a heat source and to prevent the leakage of the hot spring water into the apparatus of the gas handling part. The heat exchanger of this invention is of a heat pipe type and equipped with a vessel to pass hot spring water, a duct to pass a gas and a heat pipe extending from the vessel to the duct. An operating liquid is enclosed in the heat pipe and evaporated by heat exchange with the hot spring water and condensed by heat exchange with the gas and the thermal energy of the hot spring water is supplied to the gas in the duct. The hot spring water and the gas flow separately through the vessel and the duct respectively so that the hot spring water does not leak to the apparatus of the gas handling part even in the case of the corrosion of the heat pipe by the contact with the hot spring water. 3 figs.

Imaizumi, H.; Matsumoto, A.

1995-10-20

378

A practical method for defouling heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

Since 1976, many projects have been initiated in Alberta by industry and by academic research institutions for better utilization of the province's energy resources. Funding for research and development efforts is supported in part by the Alberta/Canada Energy Resources Research Fund. Program priorities have focused on coal, energy preservation, renewable energy, as well as conventional energy resources. This publication deals with the results of freezing the progressive buildup of biofilm, or fouling, restoring the temperature of the heat exchanger and then flushing the liberated biofilm. Several cycles of freezing followed by fluid flow can be used. This phenomenon is referred to as ''Ice Nucleation''.

1987-01-01

379

Two principles of differential Second Law heat exchanger design  

Energy Technology Data Exchange (ETDEWEB)

In this paper, two fundamental principles of differential Second Law analysis are set forth for heat exchanger design. The first principle defines a Second Law temperature, while the second principle defines a Second Law temperature difference. The square of the ratio of the Second Law temperature difference to the Second Law temperature is shown always to be equal to the negative of the partial derivative of the rate of entropy generation (for heat transfer) with respect to the overall conductance of the heat exchanger. For the basic design of elementary heat exchangers, each of these two Second Law quantities is shown to take the form of a simple geometric average. Nonelementary considerations result in corrected geometric averages, which relate directly to the corrected log-mean temperature difference. Both the corrected log-mean temperature difference (nonelementary considerations) and the uncorrected or just log-mean temperature difference (elementary considerations) are widely used in heat exchanger analysis. The importance of these two principles in both exergy and essergy analysis is illustrated by a unified basic treatment of the optimum design of elementary heat exchangers. This results in a single optimization expression for all flow arrangements (i.e., counterflow, parallel flow, and certain crossflow cases).

Evans, R.B. (Georgia Inst. of Tech., Atlanta (USA)); von Spakovsky, M.R. (Ecole Polytechnique Federale de Lausanne (Switzerland))

1991-05-01

380

On-line fouling monitor for heat exchangers  

International Nuclear Information System (INIS)

Biological and/or chemical fouling in utility service water system heat exchangers adversely affects operation and maintenance costs, and reduced heat transfer capability can force a power deaerating or even a plant shut down. In addition, service water heat exchanger performance is a safety issue for nuclear power plants, and the issue was highlighted by NRC in Generic Letter 89-13. Heat transfer losses due to fouling are difficult to measure and, usually, quantitative assessment of the impact of fouling is impossible. Plant operators typically measure inlet and outlet water temperatures and flow rates and then perform complex calculations for heat exchanger fouling resistance or ''cleanliness''. These direct estimates are often imprecise due to inadequate instrumentation. Electric Power Research Institute developed and patented an on-line condenser fouling monitor. This monitor may be installed in any location within the condenser; does not interfere with routine plant operations, including on-line mechanical and chemical treatment methods; and provides continuous, real-time readings of the heat transfer efficiency of the instrumented tube. This instrument can be modified to perform on-line monitoring of service water heat exchangers. This paper discusses the design, construction of the new monitor, and algorithm used to calculate service water heat exchanger fouling.

1995-01-01

 
 
 
 
381

Pump/heat exchanger assembly for pool-type reactor  

Energy Technology Data Exchange (ETDEWEB)

A heat exchanger and pump assembly comprising a heat exchanger including a housing for defining an annularly shaped cavity and supporting therein a plurality of heat transfer tubes. A pump is disposed beneath the heat exchanger and is comprised of a plurality of flow couplers disposed in a circular array. Each flow coupler is comprised of a pump duct for receiving a first electrically conductive fluid, i.e. the primary liquid metal, from a pool thereof, and a generator duct for receiving a second electrically conductive fluid, i.e. the intermediate liquid metal. The primary liquid metal is introduced from the reactor pool into the top, inlet ends of the tubes, flowing downward therethrough to be discharged from the tubes' bottom ends directly into the reactor pool. The primary liquid metal is variously introduced into the pump ducts directly from the reactor pool, either from the bottom or top end of the flow coupler. The intermediate fluid introduced into the generator ducts via the inlet duct and inlet plenum and after leaving the generator ducts passes through the annular cavity of the exchanger to cool the primary liquid in the tubes. The annular magnetic field of the pump is produced by a circular array of electromagnets having hollow windings cooled by a flow of the intermediate metal.

Nathenson, R.D.; Slepian, R.M.

1987-12-23

382

Heat Exchanger Support Bracket Design Calculations  

Energy Technology Data Exchange (ETDEWEB)

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

Rucinski, Russ; /Fermilab

1995-01-12

383

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

International Nuclear Information System (INIS)

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

2004-01-01

384

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-04-06

385

Furnace burners with regenerative heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The air supply to a burner is heated by passing it through a heat store which has been heated by contact with combustion products and continuous operation of the burner is possible because the air and combustion products pass alternately through different parts of the heat store. In one embodiment, a rotary valve at the centre of an annular heat store directs continuous streams of combustion air and combustion products radially outwardly then inwardly through different sectors of the heat store in turn, the burner being located at one end of the heat store. Alternatively, the air and combustion products flow longitudinally towards and back from an end of a cylindrical heat store. In a third embodiment, the air and combustion products flow alternately through a number of compartments containing heat storage elements, the flow being controlled by jets of fluid directed to deflect the flows. (author).

Wills, B.J.; Jasper, H.-D.; Flore, Raymond.

1989-03-30

386

Furnace burners with regenerative heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The air supply to a burner is heated by passing it through a heat store which has been heated by contact with combustion products and continuous operation of the burner is possible because the air and combustion products pass alternately through different parts of the heat store. In one embodiment, a rotary valve at the centre of an annular heat store directs continuous streams of combustion air and combustion products radially outwardly then inwardly through different sectors of the heat store in turn, the burner being located at one end of the heat store. Alternatively, the air and combustion products flow longitudinally towards and back from an end of a cylindrical heat store. In a third embodiment, the air and combustion products flow alternately through a number of compartments containing heat storage elements, the flow being controlled by jets of fluid directed to deflect the flows.

Wills, B.J.; Jasper, H.-D.; Flore, R.

1989-03-30

387

CALCULATION OF DISTRIBUTION OF TEMPERATURE ALONG THE CORE AT NON-STATIONARY HEAT EXCHANGE USING THE METHOD OF LOCAL THERMAL FLOWS  

Directory of Open Access Journals (Sweden)

Full Text Available Statement of the problem. Engineering practice has to deal with the problems of non-stationary heat exchange in flat elements of building structures, however, the methods of its calculation are not sufficiently developed.Results. An engineering method for calculating a non-stationary temperature field in a core heat-insulated from the sides was proposed, based on local application of physical and mathematical models of non-stationary heat exchange on the core. The expression was obtained for the calcula-tion of a constant of time which all of the calculation formulas include. Using a constant of time, the upper boundary for each step in time was established.Conclusions. The developed calculation techniques are applicable for non-uniform cores. The method to be further described is applicable and for calculation of distribution of temperature on a thickness of flat elements of the building designs, which cross-section sizes much more a thickness.

I. Yu. Butusov; R. A. Kumakov; V. L. Khudikovsky; Yu. N. Perin

2013-01-01

388

A study on the development of fouling analysis technique for shell-and-tube heat exchangers  

International Nuclear Information System (INIS)

Fouling of heat exchangers is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. The fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. This paper describes the fouling analysis technique developed in this study which can analyze the thermal performance for heat exchangers and estimate the future fouling variations. To develop the fouling analysis technique for heat exchangers, fouling factor was introduced based on the ASME O and M codes and TEMA standards. For the purpose of verifying the fouling analysis technique, the fouling analyses were performed for four heat exchangers in several nuclear power plants; two residual heat removal heat exchangers of the residual heat removal system and two component cooling water heat exchangers of the component cooling water system.

2004-01-01

389

Development of monitoring system using acoustic emission for detection of helium gas leakage for primary cooling system and flow-induced vibration for heat transfer tube of heat exchangers for the High Temperature Engineering Test Reactor (HTTR)  

Energy Technology Data Exchange (ETDEWEB)

The High Temperature Engineering Test Reactor (HTTR) uses helium gas for its primary coolant, whose leakage inside reactor containment vessel is considered in design of the HTTR. It is necessary to detect leakage of helium gas at an early stage so that total amount of the leakage should be as small as possible. On the other hand, heat transfer tubes of heat exchangers of the HTTR are designed not to vibrate at normal operation, but the flow-induced vibration is to be monitored to provide against an emergency. Thus monitoring system of acoustic emission for detection of primary coolant leakage and vibration of heat transfer tubes was developed and applied to the HTTR. Before the application to the HTTR, leakage detection test was performed using 1/4 scaled model of outer tube of primary concentric hot gas duct. Result of the test covers detectable minimum leakage rate and effect of difference in gas, pressure, shape of leakage path and distance from the leaking point. Detectable minimum leakage rate was about 5 Ncc/sec. The monitoring system is promising in leakage detection, though countermeasure to noise is to be needed after the HTTR starts operating. (author)

Tachibana, Yukio; Kunitomi, Kazuhiko; Furusawa, Takayuki; Shinozaki, Masayuki [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Satoh, Yoshiyuki; Yanagibashi, Minoru

1998-10-01

390

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

International Nuclear Information System (INIS)

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 tap water flow rate. A split-type WAC was set up for experimental study at different indoor and outdoor conditions. The cooling output, the amount of recovered heat, and the power consumption for different hot water flow rates were measured. The experimental results showed that the cooling coefficient of performance (COP) of the WAC improves with the inclusion of the heat recovery option by a minimum of 12.3%. This can be further improved to 20.6% by an increase in tap water flow rate. Same result was observed for the comprehensive COP of the WAC. The maximum achievable comprehensive COP was 4.92 when the tap water flow rate was set at 7.7 L/min. The overall heat transfer coefficient of the helical heat exchanger under various operating conditions were determined by Wilson plot. A mathematical model relating the over all heat transfer coefficient to the outer pipe diameter was established which provides a convenient way of optimising the design of the helical heat exchanger.

2009-01-01

391

Performance and modeling of thermosyphon heat exchangers for solar water heaters  

Energy Technology Data Exchange (ETDEWEB)

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 convection effects can significantly influence overall heat transfer and friction coefficients. Existing models which assume the thermal and hydraulic behaviors of thermosyphon heat exchangers are only functions of the thermosyphon and collector flow rates may not be suitable for all heat exchanger types. For example, the overall heat-transfer coefficient-area product for the two-pass, tube-in-shell heat exchanger is best expressed as a function of Reynolds, Grashof, and Prandtl numbers on the thermosyphon side of the heat exchanger. It is proposed that annual simulations of solar water heaters with thermosyphon heat exchangers use this type of relationship to characterize heat transfer in the heat exchanger.

Dahl, S.D.; Davidson, J.H. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Mechanical Engineering

1997-08-01

392

Heat exchanger module for secondary circuit of nuclear heating plant  

International Nuclear Information System (INIS)

[en] The heat exchanger placed in the reactor vessel consists of a bundle of heat exchange tubes, two tube plates, their lids, and inlet and outlet tubes. The heat exchange tubes of the exchanger of the secondary coolant circuit are attached by their upper ends to the upper tube plate and by their bottom ends to the bottom tube plate. The heat exchange elements are placed around the inlet tube of the secondary coolant circuit passing tightly through the upper tube plate. The outlet tube of the secondary coolant circuit passes tightly through the reactor vessel and by its upper end is attached to the inlet tube and by its bottom end to the lid of the upper tube plate. The inlet tube is tightly connected to the bottom tube plate via the expansion pressurizer. (B.S.)

1979-12-27

393

RADIAL DESIGN OXYGENATOR WITH HEAT EXCHANGER  

UK PubMed Central (United Kingdom)

Disclosed is an apparatus for oxygenating and controlling the temperature of blood in an extracorporeal circuit. The apparatus has an inlet and an outlet that is located radially outward from the inlet in order to define a flowpath through the apparatus. The apparatus comprises: a core that is substantially centrally located in the apparatus and to which blood from a patient can be supplied through the inlet a heat exchanger comprising a plurality of heat transfer elements that are arranged around the core and between which blood from the core can move radially outward and an oxygenator comprising a plurality of gas exchange elements that are arranged around the heat exchanger and between which blood from the heat exchanger can move radially outward before exiting the apparatus through the outlet.

CARPENTER WALT L; OLSEN ROBERT W; HOBDAY MICHAEL J; MCLEVISH ALFORD L; PLOTT CHRISTOPHER J; BRISCOE RODERICK E; CLOUTIER PATRICK J; THAPA ANIL; LI MING; MCINTOSH KEVIN; MERTE KEN

394

Heat exchanger development in the 1980s  

International Nuclear Information System (INIS)

[en] Heat exchanger development plays an important role in nuclear engineering. The author discusses improvements in materials for better thermal efficiency and considers safety aspects and future prospects. (G.T.H.)

1982-01-01