WorldWideScience

Sample records for heat exchanger studies

  1. Numerical study of heat transfer characteristics in BOG heat exchanger

    Science.gov (United States)

    Yan, Yan; Pfotenhauer, John M.; Miller, Franklin; Ni, Zhonghua; Zhi, Xiaoqin

    2016-12-01

    In this study, a numerical study of turbulent flow and the heat transfer process in a boil-off liquefied natural gas (BOG) heat exchanger was performed. Finite volume computational fluid dynamics and the k - ω based shear stress transport model were applied to simulate thermal flow of BOG and ethylene glycol in a full-sized 3D tubular heat exchanger. The simulation model has been validated and compared with the engineering specification data from its supplier. In order to investigate thermal characteristics of the heat exchanger, velocity, temperature, heat flux and thermal response were studied under different mass flowrates in the shell-side. The shell-side flow pattern is mostly determined by viscous forces, which lead to a small velocity and low temperature buffer area in the bottom-right corner of the heat exchanger. Changing the shell-side mass flowrate could result in different distributions of the shell-side flow. However, the distribution in the BOG will remain in a relatively stable pattern. Heat flux increases along with the shell-side mass flowrate, but the increase is not linear. The ratio of increased heat flux to the mass flow interval is superior at lower mass flow conditions, and the threshold mass flow for stable working conditions is defined as greater than 0.41 kg/s.

  2. Design study of plastic film heat exchanger

    Science.gov (United States)

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

    1986-02-01

    This report presents the results of an effort to develop and design a unique thermoplastic film heat exchanger for use in an industrial heat pump evaporator system and other energy recovery applications. The concept for the exchanger is that of individual heat exchange elements formed by two adjoining and freely hanging plastic films. Liquid flows downward in a regulated fashion between the films due to the balance of hydrostatic and frictional forces. The fluid stream on the outside of film may be a free-falling liquid film, a condensing gas, or a noncondensing gas. The flow and structural principles are similar to those embodied in an earlier heat exchange system developed for use in waste water treatment systems (Sanderson). The design allows for high heat transfer rates while working within the thermal and structural limitations of thermoplastic materials. The potential of this new heat exchanger design lies in the relatively low cost of plastic film and the high inherent corrosion and fouling resistance. This report addresses the selection of materials, the potential heat transf er performance, the mechanical design and operation of a unit applied in a low pressure steam recovery system, and the expected selling price in comparison to conventional metallic shell and tube heat exchangers.

  3. Heat transfer studies on spiral plate heat exchanger

    Directory of Open Access Journals (Sweden)

    Rajavel Rangasamy

    2008-01-01

    Full Text Available In this paper, the heat transfer coefficients 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 hot water (hot fluid is varying from 0.5 to 0.8 kg/s and the mass flow rate of cold water (cold fluid varies from 0.4 to 0.7 kg/s. 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.

  4. Heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, E L; Eisenmann, G; Hahne, E [Stuttgart Univ. (TH) (F.R. Germany). Inst. fuer Thermodynamik und Waermetechnik

    1976-04-01

    A survey is presented on publications on design, heat transfer, form factors, free convection, evaporation processes, cooling towers, condensation, annular gap, cross-flowed cylinders, axial flow through a bundle of tubes, roughnesses, convective heat transfer, loss of pressure, radiative heat transfer, finned surfaces, spiral heat exchangers, curved pipes, regeneraters, heat pipes, heat carriers, scaling, heat recovery systems, materials selection, strength calculation, control, instabilities, automation of circuits, operational problems and optimization.

  5. Heat exchanger

    International Nuclear Information System (INIS)

    Leigh, D.G.

    1976-01-01

    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.)

  6. Heat exchanger

    Science.gov (United States)

    Daman, Ernest L.; McCallister, Robert A.

    1979-01-01

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

  7. Heat exchanger

    International Nuclear Information System (INIS)

    Dostatni, A.W.; Dostatni, Michel.

    1976-01-01

    In the main patent, a description was given of a heat exchanger with an exchange surface in preformed sheet metal designed for the high pressure and temperature service particularly encountered in nuclear pressurized water reactors and which is characterised by the fact that it is composed of at least one exchanger bundle sealed in a containment, the said bundle or bundles being composed of numerous juxtaposed individual compartments whose exchange faces are built of preformed sheet metal. The present addendun certificate concerns shapes of bundles and their positioning methods in the exchanger containment enabling its compactness to be increased [fr

  8. Heat exchanger

    International Nuclear Information System (INIS)

    Drury, C.R.

    1988-01-01

    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

  9. Heat exchanger

    Science.gov (United States)

    Wolowodiuk, Walter

    1976-01-06

    A heat exchanger of the straight tube type in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration.

  10. Heat exchangers

    International Nuclear Information System (INIS)

    1975-01-01

    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

  11. Heat exchanger

    International Nuclear Information System (INIS)

    Wolowodiuk, W.

    1976-01-01

    A heat exchanger of the straight tube type is described in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration

  12. Heat exchanger

    International Nuclear Information System (INIS)

    Bennett, J.C.

    1975-01-01

    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.)

  13. Heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Harada, F; Yanagida, T; Fujie, K; Futawatari, H

    1975-04-30

    The purpose of this construction is the improvement of heat transfer in finned tube heat exchangers, and therefore the improvement of its efficiency or its output per unit volume. This is achieved by preventing the formation of flow boundary layers in gaseous fluid. This effect always occurs on flow of smooth adjacent laminae, and especially if these have pipes carrying liquid passing through them; it worsens the heat transfer of such a boundary layer considerably compared to that in the turbulent range. The fins, which have several rows of heat exchange tubes passing through them, are fixed at a small spacing on theses tubes. The fins have slots cut in them by pressing or punching, where the pressed-out material remains as a web, which runs parallel to the level of the fin and at a small distance from it. These webs and slots are arranged radially around every tube hole, e.g. 6 in number. For a suitable small tube spacing, two adjacent tubes opposite each other have one common slot. Many variants of such slot arrangements are illustrated.

  14. Study on finned pipe performance as a ground heat exchanger

    Science.gov (United States)

    Lin, Qinglong; Ma, Jinghui; Shi, Lei

    2017-08-01

    The GHEs (ground heat exchangers) is an important element that determines the thermal efficiency of the entire ground-source heat-pump system. The aim of the present study is to clarify thermal performance of a new type GHE pipe, which consists straight fins of uniform cross sectional area. In this paper, GHE model is introduced and an analytical model of new type GHE pipe is developed. The heat exchange rate of BHEs utilizing finned pips is 40.42 W/m, which is 16.3% higher than normal BHEs, based on simulation analyses.

  15. Segmented heat exchanger

    Science.gov (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  16. Study of ion exchange equilibrium and determination of heat of ion exchange by ion chromatography

    International Nuclear Information System (INIS)

    Liu Kailu; Yang Wenying

    1996-01-01

    Ion chromatography using pellicularia ion exchange resins and dilute solution can be devoted to the study of ion exchange thermodynamics and kinetics. Ion exchange equilibrium equation was obtained, and examined by the experiments. Based on ion exchange equilibrium, the influence of eluent concentration and resin capacity on adjusted retention volumes was examined. The effect of temperature on adjusted retention volumes was investigated and heats of ion exchange of seven anions were determined by ion chromatography. The interaction between anions and skeleton structure of resins were observed

  17. Experimental study of heat transfer in a heat exchanger with rectangular channels

    International Nuclear Information System (INIS)

    Hammami, Mahmoud; Ben Said, Akrem; Ben Maad, Rejeb; Rebay, Mourad

    2009-01-01

    This paper presents the results of an experimental study related to characterisation of a mini channel heat exchanger. Such heat exchanger may be used in water cooling of electronic components. The results obtained show the efficiency of this exchanger even with very low water flow rates. Indeed, in spite of the importance of the extracted heat fluxes which can reach about 50Kw/m 2 , the temperature of the cooled Aluminium bloc remained always lower than the tolerated threshold of 80 degree in electronic cooling. Moreover, several thermal characteristics such as equivalent thermal resistance of the exchanger, the average internal convective heat transfer coefficient and the increase in the temperature of the cooling water have been measured. The results presented have been obtained with in q uinconce r ectangular mini-channel heat exchanger, with a hydraulic diameter D h = 2mm. NOMENCLATURE h D Hydraulic diameter (mm). int

  18. VHTR engineering design study: intermediate heat exchanger program. Final report

    International Nuclear Information System (INIS)

    1976-11-01

    The work reported is the result of a follow-on program to earlier Very High Temperature Reactor (VHTR) studies. The primary use of the VHTR is to provide heat for various industrial processes, such as hydrocarbon reforming and coal gasification. For many processes the use of an intermediate heat transfer barrier between the reactor coolant and the process is desirable; for some processes it is mandatory. Various intermediate heat exchanger (IHX) concepts for the VHTR were investigated with respect to safety, cost, and engineering design considerations. The reference processes chosen were steam-hydrocarbon reforming, with emphasis on the chemical heat pipe, and steam gasification of coal. The study investigates the critically important area of heat transfer between the reactor coolant, helium, and the various chemical processes

  19. Numerical study on boiling heat transfer enhancement in a microchannel heat exchanger

    International Nuclear Information System (INIS)

    Jeon, Jin Ho; Suh, Young Ho; Son, Gi Hun

    2008-01-01

    Flow boiling in a microchannel heat exchanger has received attention as an effective heat removal mechanism for high power-density microelectronics. Despite extensive experimental studied, the bubble dynamics coupled with boiling heat transfer in a microchannel heat exchanger is still not well understood due to the technological difficulties in obtaining detailed measurements of microscale two-phase flows. In this study, complete numerical simulations are performed to further clarify the dynamics of flow boiling in a microchannel heat exchanger. The level set method for tracking the liquid-vapor interface is modified to include the effects of phase change and contact angle and to treat an immersed solid surface. Based on the numerical results, the effects of modified channel shape on the bubble growth and heat transfer are quantified

  20. Experimental study of particulate fouling onto heat exchanger elements

    International Nuclear Information System (INIS)

    Chandrasa

    1994-01-01

    An experimental study of particulate fouling onto tubular heat exchanger surfaces was carried out using sodium sulfate particles. An experimental apparatus equipped with an aerosol generator has been used to examine the deposition of small particles under controlled conditions. Two sets of experiments were performed. Firstly, the deposition against time of solid particles onto single heat exchanger tube in cross-flow was studied. The effects of a number variables such as particle size, gas velocity and temperature on the deposition was analysed. Secondly, the deposition for the aerosol particles as they passed through a bank of finned tubes was examined. The deposition patterns on various tubes depended on local conditions (velocity and temperature) within the bank. It was found that the fouling resistance increases as aerosol flow rate decreases. The smaller particles showed higher fouling resistance. (author) [fr

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  2. Investigation of heat transfer inside a PCM-air heat exchanger: a numerical parametric study

    Science.gov (United States)

    Herbinger, Florent; Bhouri, Maha; Groulx, Dominic

    2017-07-01

    In this paper, the use of PCMs for thermal storage of energy in HVAC applications was investigated by studying numerically the thermal performance of a PCM-air heat exchanger. The PCM used in this study was dodecanoic acid. A symmetric 3D model, incorporating conductive and convective heat transfer (air only) as well as laminar flow, was created in COMSOL Multiphysics 5.0. Simulations examined the dependence of the heat transfer rate on the temperature and velocity of the incoming air as well as the size of the channels in the heat exchanger. Results indicated that small channels size lead to a higher heat transfer rates. A similar trend was also obtained for high incoming air temperature, whereas the heat transfer rate was less sensitive to the incoming air velocity.

  3. Experimental study on heat pipe assisted heat exchanger used for industrial waste heat recovery

    International Nuclear Information System (INIS)

    Ma, Hongting; Yin, Lihui; Shen, Xiaopeng; Lu, Wenqian; Sun, Yuexia; Zhang, Yufeng; Deng, Na

    2016-01-01

    Highlights: • A heat pipe heat exchanger (HPHE) was used to recycle the waste heat in a slag cooling process of steel industry. • An specially designed on-line cleaning device was construed and used to enhance the heat transfer of HPHE. • The performance characteristics of a HPHE has been assessed by integrating the first and second law of thermodynamics. • The optimum operation conditions was determined by integrating the first and the second law of thermodynamics. - Abstract: Steel industry plays an important role economically in China. A great amount of hot waste liquids and gases are discharged into environment during many steelmaking processes. These waste liquids and gases have crucial energy saving potential, especially for steel slag cooling process. It could be possible to provide energy saving by employing a waste heat recovery system (WHRS). The optimum operation condition was assessed by integrating the first and the second law of thermodynamics for a water–water heat pipe heat exchanger (HPHE) for a slag cooling process in steel industry. The performance characteristics of a HPHE has been investigated experimentally by analyzing heat transfer rate, heat transfer coefficient, effectiveness, exergy efficiency and number of heat transfer units (NTU). A specially designed on-line cleaning device was used to clean the heat exchange tubes and enhance heat transfer. The results indicated that the exergy efficiency increased with the increment of waste water mass flow rate at constant fresh water mass flow rate, while the effectiveness decreased at the same operation condition. As the waste water mass flow rate varied from 0.83 m"3/h to 1.87 m"3/h, the effectiveness and exergy efficiency varied from 0.19 to 0.09 and from 34% to 41%, respectively. In the present work, the optimal flow rates of waste water and fresh water were 1.20 m"3/h and 3.00 m"3/h, respectively. The on-line cleaning device had an obvious effect on the heat transfer, by performing

  4. Experimental study of heat transfer and pressure drop characteristics of air/water and air-steam/water heat exchange in a polymer compact heat exchanger

    NARCIS (Netherlands)

    Cheng, L.; Geld, van der C.W.M.

    2005-01-01

    Experiments of heat transfer and pressure drop in a polymer compact heat exchanger made of PolyVinyliDene-Fluoride were conducted under various conditions for air/water heat exchange and air-steam/water heat exchange, respectively. The overall heat transfer coefficients of air-steam/water heat

  5. A study on experiment and numerical simulation of heat exchanger in heating furnace

    Directory of Open Access Journals (Sweden)

    Z. C. Lv

    2018-01-01

    Full Text Available In this paper, air preheater is used the research object and its heat transfer law is studied by experiment and numerical simulation. The experimental data showed that with the increases of inlet air velocity, the comprehensive heat transfer coefficient and heat transfer efficiency increase, but the temperature efficiency decreases and the resistance loss on the air side increases. The numerical simulation results showed that the larger the diameter of the tube, the better the heat transfer effect. When horizontal spacing in the range of 290 - 305 mm and longitudinal spacing is 70 - 90 mm, the heat transfer effect is best. The optimized heat exchanger structure is that diameter is 60 mm, horizontal spacing is 300 mm, longitudinal spacing is 90 mm. As the inlet air flow rate increases, the heat transfer efficiency increases, but the temperature efficiency decreases and the resistance loss on the air side increases.

  6. Experimental and numerical study of a printed circuit heat exchanger

    International Nuclear Information System (INIS)

    Chen, Minghui; Sun, Xiaodong; Christensen, Richard N.; Shi, Shanbin; Skavdahl, Isaac; Utgikar, Vivek; Sabharwall, Piyush

    2016-01-01

    Highlights: • A dynamic model is developed for transient analysis of the straight-channel PCHE. • Transient scenarios of the straight-channel PCHE subject to helium temperature and mass flow rate variations are numerically investigated. • Steady-state temperature distribution inside the straight-channel PCHE is obtained in calculation. • Experiments are conducted to study the dynamic behavior of the straight-channel PCHE. - Abstract: Printed circuit heat exchangers (PCHEs) are promising to be employed in very-high-temperature gas-cooled reactors (VHTRs) due to their high robustness for high-temperature, high-pressure applications and high compactness. PCHEs typically serve as intermediate heat exchangers (IHXs) that isolate the secondary loop from the reactor’s primary system and hence must be sufficiently robust to maintain the system integrity during normal and off-normal conditions. In addition, the performance of the PCHE-type IHX could considerably affect the nuclear power plant overall operation since any transients on the secondary side would be propagated back to the reactor’s primary coolant system via the IHX. It is therefore imperative to understand how the PCHE would dynamically respond to a variety of transients. In the current study, experiments were first conducted to examine the steady-state thermal performance of a reduced-scale straight-channel PCHE. A dynamic model benchmarked in a previous study was then used to predict the steady-state and transient behavior of the PCHE. The steady-state temperature profiles of the working fluids on both the hot and cold sides and in the solid plates of the heat exchanger were obtained, which served as the initial condition for the transient simulations. The detailed dynamic response of the straight-channel PCHE, subject to inlet temperature variations, helium mass flow variations, and combinations of the two, was simulated and analyzed. In addition, two sets of transient tests, one for helium inlet

  7. Horizontal Parallel Pipe Ground Heat Exchanger : Analytical Conception and Experimental Study

    International Nuclear Information System (INIS)

    Naili, Nabiha; Jemli, Ramzi; Farhat, Abdel Hamid; Ben Nasrallah, Sassi

    2009-01-01

    Due to limited amount of natural resources exploited for heating, and in order to reduce the environmental impact, people should strive to use renewable energy resources. Ambient low-grade energy may be upgraded by the ground heat exchanger (GH E), which exploits the ground thermal inertia for buildings heating and cooling. In this study, analytical performance and experiments analysis of a horizontal ground heat exchanger have been performed. The analytical study, relates to the dimensioning of the heat exchanger, shows that the heat exchanger characteristics are very important for the determination of heat extracted from ground. The experimental results were obtained during the period 30 November to 10 December 2007, in the heating season of the greenhouses. Measurements show that the ground temperature under a certain depth remains relatively constant. To exploit effectively the heat capacity of the ground, a horizontal heat exchanger system has to be constructed and tested in the Center of Research and Technology of Energy, in Tunisia

  8. Numerical Study of Condensation Heat Exchanger Design in a Subcooled Pool: Correlation Investigation

    International Nuclear Information System (INIS)

    Lee, Hee Joon; Ju, Yun Jae; Kang, Han Ok; Lee, Tae Ho; Park, Cheon Tae

    2012-01-01

    Generally the condensation heat exchanger has higher heat transfer coefficient compared to the single phase heat exchanger, so has been widely applied to the cooling systems of energy plant. Recently vertical or horizontal type condensation heat exchangers are being studied for the application to secondary passive cooling system of nuclear plants. Lee and Lee investigated the existing condensation correlation to the experiment for heat exchanger in saturated pool. They concluded Traviss' correlation showed most satisfactory results for the heat transfer coefficient and mass flow rate in a saturated water pool. In this study, a thermal sizing program of vertical condensation heat exchanger to design, TSCON(Thermal Sizing of CONdenser) was validated with the existing experimental data of condensation heat exchanger in a subcooled pool for pure steam condensation

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Su-Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kim, Eung-Soo [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2013-09-01

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

  10. Study of heat exchange characteristics of the Dalat Nuclear Reactor

    International Nuclear Information System (INIS)

    An, N.K.; Huy, N.Q.

    1989-01-01

    This report is presented some experimental data and related theoretical computations concerning the thermal exchange system under normal operating or accidental conditions from the thermodynamic point of view. In the normal operation, the reactor operates under safety condition T max fuel=96.2 degree C. Under LOFA condition, the heat exchage process is still realized, therefore, we should determine the allowable limits of the thermal regime at power and at shut down condition

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

    Science.gov (United States)

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

    2017-01-01

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

  12. Parametric study of moderator heat exchanger for Candu 6 advanced reactor

    International Nuclear Information System (INIS)

    Umar, Efrizon; Vecchiarelli, Jack

    2000-01-01

    The passive moderator system for Candu 6 advanced reactor require moderator heat exchanger with the small size and the low resistance coefficient of the shell-side. The study is to determine the required size of moderator heat exchanger, and to calculate the shell side of resistance coefficient have been done. Using computer code CATHENA, it is concluded that the moderator heat exchanger can be used at full power-normal operation condition, especially for the cases with 3600 to 8100 number of tube and 15.90 mm tube diameter. This study show that the proposed moderator heat exchanger have given satisfactory results

  13. Heat exchange apparatus

    International Nuclear Information System (INIS)

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

    1979-01-01

    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)

  14. A Numerical Study on Heat Transfer and Flow Characteristics of a Finned Downhole Coaxial Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chun Dong; Lee, Dong Hyun; Park, Byung-Sik; Choi, Jaejoon [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)

    2017-02-15

    In this study, the flow and heat transfer characteristics of the finned annular passage were investigated numerically. The annular passage simulates co-axial geothermal heat exchanger, and fins are installed on its inner wall to reduce heat loss from the production passage (annulus) to injection passage (inner pipe). A commercial CFD program, Ansys Fluent, was used with SST k-ω turbulence model. The effects of the geometric parameters of the fin on the inner tube were analyzed under the periodic boundary condition. The result indicated that most parameters had a tendency to increase with an increase in the height and angle of the fin. However, it was confirmed that the Nusselt number of the inner tube on the coaxial 15, 5, 0.3 was lower than that of the smooth tube. Additionally, the Nusselt number of the inner tube exhibited a tendency of decreasing with a decrease in the spacing in Coaxial 15, S{sub f}, 0.3.

  15. Experimental study on fouling in the heat exchangers of surface water heat pumps

    International Nuclear Information System (INIS)

    Bai, Xuelian; Luo, Te; Cheng, Kehui; Chai, Feng

    2014-01-01

    Fouling in the heat exchangers plays a key role on the performance of surface water heat pumps. It is also the basement for the system design criteria and operation energy efficiency. In this paper, experimental measurements are performed both in the field and the laboratory with different water qualities, temperatures and velocities. The research will focus on the dynamic growth characteristics of fouling and its main components. By studying the variation rules of fouling resistance, the fouling resistance allowance for certain water condition is recommended. Furthermore, a fouling prediction model in surface water heat pump will be developed and validated based on elaborating with fouling principle under specified water conditions. - Highlights: • Field and laboratory experiments are taken to measure the fouling variation. • Fouling growth process can be divided into four stages. • We recommend fouling resistance allowances for certain conditions. • A fouling prdiction model is developed and validated

  16. Optimization of Heat Exchangers

    International Nuclear Information System (INIS)

    Catton, Ivan

    2010-01-01

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

  17. Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study

    Directory of Open Access Journals (Sweden)

    Jeanette Janaina Jaber Lucato

    2009-06-01

    Full Text Available OBJECTIVES: To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. INTRODUCTION: Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. METHODS: Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37°C, a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH was calculated for each setting. RESULTS: Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. CONCLUSIONS: Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance, suggesting that their adjustment has a less significant effect on the performance of heat and moisture exchangers.

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

    Science.gov (United States)

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

    1980-01-01

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

  19. Role of heat exchangers in helium liquefaction cycles: Simulation studies using Collins cycle

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Rijo Jacob, E-mail: rijojthomas@gmail.com [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur 721302 (India); Ghosh, Parthasarathi; Chowdhury, Kanchan [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur 721302 (India)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Role of heat exchangers in basic helium liquefier analyzed to design large-scale ones. Black-Right-Pointing-Pointer Heat exchangers that determine inlet temperature to expanders are more significant. Black-Right-Pointing-Pointer Limiting values of nondimensional UA for each heat exchanger have been determined. Black-Right-Pointing-Pointer Extra area distributed such that effectiveness of all heat exchangers increase uniformly. Black-Right-Pointing-Pointer Heat exchanger performance variation have little influence on the optimum expander flow. - Abstract: Energy efficiency of large-scale helium liquefiers generally employed in fusion reactors and accelerators is determined by the performance of their constituting components. Simulation with Aspen HYSYS{sup Registered-Sign} V7.0, a commercial process simulator, helps to understand the effects of heat exchanger parameters on the performance of a helium liquefier. Effective UA (product of overall heat transfer coefficient U, heat transfer surface area A and deterioration factor F) has been taken as an independent parameter, which takes into account all thermal irreversibilities and configuration effects. Nondimensionalization of parameters makes the results applicable to plants of any capacity. Rate of liquefaction is found to increase linearly with the effectiveness of heat exchangers. Performance of those heat exchangers that determine the inlet temperatures to expanders have more influence on the liquid production. Variation of sizes of heat exchangers does not affect the optimum rate of flow through expanders. Increasing UA improves the rate of liquid production; however, the improvement saturates at limiting UA. Maximum benefit in liquefaction is obtained when the available heat transfer surface area is distributed in such a way that the effectiveness remains equal for all heat exchangers. Conclusions from this study may be utilized in analyzing and designing large helium

  20. Role of heat exchangers in helium liquefaction cycles: Simulation studies using Collins cycle

    International Nuclear Information System (INIS)

    Thomas, Rijo Jacob; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2012-01-01

    Highlights: ► Role of heat exchangers in basic helium liquefier analyzed to design large-scale ones. ► Heat exchangers that determine inlet temperature to expanders are more significant. ► Limiting values of nondimensional UA for each heat exchanger have been determined. ► Extra area distributed such that effectiveness of all heat exchangers increase uniformly. ► Heat exchanger performance variation have little influence on the optimum expander flow. - Abstract: Energy efficiency of large-scale helium liquefiers generally employed in fusion reactors and accelerators is determined by the performance of their constituting components. Simulation with Aspen HYSYS ® V7.0, a commercial process simulator, helps to understand the effects of heat exchanger parameters on the performance of a helium liquefier. Effective UA (product of overall heat transfer coefficient U, heat transfer surface area A and deterioration factor F) has been taken as an independent parameter, which takes into account all thermal irreversibilities and configuration effects. Nondimensionalization of parameters makes the results applicable to plants of any capacity. Rate of liquefaction is found to increase linearly with the effectiveness of heat exchangers. Performance of those heat exchangers that determine the inlet temperatures to expanders have more influence on the liquid production. Variation of sizes of heat exchangers does not affect the optimum rate of flow through expanders. Increasing UA improves the rate of liquid production; however, the improvement saturates at limiting UA. Maximum benefit in liquefaction is obtained when the available heat transfer surface area is distributed in such a way that the effectiveness remains equal for all heat exchangers. Conclusions from this study may be utilized in analyzing and designing large helium plants.

  1. Feasibility Study of Secondary Heat Exchanger Concepts for the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall

    2011-09-01

    The work reported herein represents a significant step in the preliminary design of heat exchanger options (material options, thermal design, selection and evaluation methodology with existing challenges). The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production using either a subcritical or supercritical Rankine cycle.

  2. Experimental simulation study on hydraulic behavior of the main heat exchanger of Daqing 200 MW nuclear heating reactor

    International Nuclear Information System (INIS)

    Jiang Shengyao; Zhang Youjie; Jia Haijun; Bo Jinhai; Hong Liuming; Bo Hanliang; Liu Zhiyong

    1997-07-01

    The hydraulic behavior of the main heat exchanger of Daqing 200 MW nuclear heating reactor is studied through a 1:2.33 test model. The design and other feature of the test model is described. The experimental results show that the flow resistance coefficient of the heat exchanger becomes self-simulation when Reynolds number is greater than 5000. The value of flow resistance coefficient at self-simulation condition and the distribution of pressure drop in the heat exchanger are given through experiment. The option design to reduce flow resistance is proposed. The designed and experimental value for the flow resistance coefficient are in good agreement. The variation of system parameters during flow excursion was described. The experimental results are of great significant for the final design of the main heat exchanger of Daqing 200 MW nuclear heating reactor. (2 refs., 5 figs., 1 tab.)

  3. Microscale Regenerative Heat Exchanger

    Science.gov (United States)

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

    2006-01-01

    The device described herein is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a "regenerator" in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle.

  4. Numerical Study of Heat Transfer Enhancement in Heat Exchanger Using AL2O3 Nanofluids

    Directory of Open Access Journals (Sweden)

    Hussein Talal Dhaiban

    2016-04-01

    Full Text Available In this study, the flow and heat transfer characteristics of Al2O3-water nanofluids for a range of the Reynolds number of 3000, 4500, 6000 and 7500 with a range of volume concentration of 1%, 2%, 3% and 4% are studied numerically. The test rig consists of cold liquid loop, hot liquid loop and the test section which is counter flow double pipe heat exchanger with 1m length. The inner tube is made of smooth copper with diameter of 15mm. The outer tube is made of smooth copper with diameter of 50mm. The hot liquid flows through the outer tube and the cold liquid (or nanofluid flow through the inner tube. The boundary condition of this study is thermally insulated the outer wall with uniform velocity at (0.2, 0.3, 0.4 and 0.5 m/s at the cold loop and constant velocity at (0.5 m/s at the hot loop. The results show that the heat transfer coefficient and Nusselt number increased by increasing Reynolds number and particle concentration. Numerical results indicate that the maximum enhancement in Nusselt number and heat transfer coefficient were 9.5% and 13.5% respectively at Reynolds number of 7100 and particles volume fraction of 4%. Results of nanofluids also showed a good agreement with the available empirical correlation at particles volume fractions of 1%, 2% and 3%, but at volume fractions of 4% a slight deviation is obtained.

  5. Comparing studies for an optimization of steam-heated tube bundle heat exchangers

    International Nuclear Information System (INIS)

    Horn, M.

    1975-01-01

    The problems of designing an apparatus are to be shown by the example of the steam-heated tube bundle heat exchanger, and optimizations are to be carried through by relevant examples. From the results of the optimization, a set of apparatus types is to be derived where the dimensions of the shell and the heat pipes as well as the length of the tube bundle are to be determined by as few data as possible. (orig./TK) [de

  6. Milk fouling in heat exchangers

    NARCIS (Netherlands)

    Jeurnink, T.J.M.

    1996-01-01


    The mechanisms of fouling of heat exchangers by milk were studied. Two major fouling mechanisms were indentified during the heat treatment of milk: (i) the formation and the subsequent deposition of activated serum protein molecules as a result of the heat denaturation; (ii) the

  7. Heat exchanger cleaning

    International Nuclear Information System (INIS)

    Gatewood, J.R.

    1980-01-01

    A survey covers the various types of heat-exchange equipment that is cleaned routinely in fossil-fired generating plants, the hydrocarbon-processing industry, pulp and paper mills, and other industries; the various types, sources, and adverse effects of deposits in heat-exchange equipment; some details of the actual procedures for high-pressure water jetting and chemical cleaning of some specific pieces of equipment, including nuclear steam generators. (DN)

  8. Heat exchanger vibrations - a case study (Paper No. 5.12)

    International Nuclear Information System (INIS)

    Khilnaney, V.K.

    1992-01-01

    The satisfactory performance of heat exchangers is crucial to the reliability of the plant. Thorough vibration analysis is essential at design stage to avoid failures at the time of operation. Detailed vibration analysis techniques were not available at the time of designing these exchangers and the exchangers were designed as per general guidelines and prevalent good engineering practices. The designs were not checked especially from the point of view of their proneness to excessive flow induced vibration. The present paper gives a study of revamping of cooling water heat exchanger at Heavy Water Plant, Kota. (author)

  9. Radial flow heat exchanger

    Science.gov (United States)

    Valenzuela, Javier

    2001-01-01

    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.

  10. Numerical Study of Compact Plate-Fin Heat Exchanger for Rotary-Vane Gas Refrigeration Machine

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2017-10-01

    Full Text Available Plate-fin heat exchangers are widely used in refrigeration technique. They are popular because of their compactness and excellent heat transfer performance. Here we present a numerical model for the development, research and optimization of a plate-fin heat exchanger for a rotary-vane gas refrigeration machine. The method of analysis by graphic method of plate - fin heat exchanger is proposed. The model describes the effects of secondary parameters such as axial thermal conductivity through a metal matrix of the heat exchanger. The influence of geometric parameters and heat transfer coefficient is studied. Graphs of dependences of length, efficiency of a fin and pressure drop in a heat exchanger on the thickness of the fin and the number of fins per meter are obtained. To analyze the results of numerical simulation, the heat exchanger was designed in the Aspen HYSYS program. The simulation results show that the total deviation from the proposed numerical model is not more than 15%. 

  11. Hydrodynamic studies of CNT nanofluids in helical coil heat exchanger

    Science.gov (United States)

    Babita; Sharma, S. K.; Mital Gupta, Shipra; Kumar, Arinjay

    2017-12-01

    Helical coils are extensively used in several industrial processes such as refrigeration systems, chemical reactors, recovery processes etc to accommodate a large heat transfer area within a smaller space. Nanofluids are getting great attention due to their enhanced heat transfer capability. In heat transfer equipments, pressure drop is one of the major factors of consideration for pumping power calculations. So, the present work is aimed to study hydrodynamics of CNT nanofluids in helical coils. In this study, pressure drop characteristics of CNT nanofluid flowing inside horizontal helical coils are investigated experimentally. The helical coil to tube diameter was varied from 11.71 to 27.34 keeping pitch of the helical coil constant. Double distilled water was used as basefluid. SDBS and GA surfactants were added to stablilize CNT nanofluids. The volumetric fraction of CNT nanofluid was varied from 0.003 vol% to 0.051 vol%. From the experimental data, it was analyzed that the friction factor in helical coils is greater than that of straight tubes. Concentration of CNT in nanofluids also has a significant influence on the pressure drop/friction factor of helical coils. At a constant concentration of CNT, decreasing helical coil to tube diameter from 27.24 to 11.71, fanning friction factor of helical coil; f c increases for a constant value of p/d t. This increase in the value of fanning friction factor can be attributed to the secondary flow of CNT nanofluid in helical coils.

  12. Chapter 11. Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, Kevin D.; Culver, Gene

    1998-01-01

    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.

  13. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    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

  14. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    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

  15. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-01-01

    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 summarized

  16. Experimental and computational study on thermoelectric generators using thermosyphons with phase change as heat exchangers

    International Nuclear Information System (INIS)

    Araiz, M.; Martínez, A.; Astrain, D.; Aranguren, P.

    2017-01-01

    Highlights: • Thermosyphon with phase change heat exchanger computational model. • Construction and experimentation of a prototype. • ±9% of maximum deviation from experimental values of the main outputs. • Influence of the auxiliary equipment on the net power generation. - Abstract: An important issue in thermoelectric generators is the thermal design of the heat exchangers since it can improve their performance by increasing the heat absorbed or dissipated by the thermoelectric modules. Due to its several advantages, compared to conventional dissipation systems, a thermosyphon heat exchanger with phase change is proposed to be placed on the cold side of thermoelectric generators. Some of these advantages are: high heat-transfer rates; absence of moving parts and lack of auxiliary consumption (because fans or pumps are not required); and the fact that these systems are wickless. A computational model is developed to design and predict the behaviour of this heat exchangers. Furthermore, a prototype has been built and tested in order to demonstrate its performance and validate the computational model. The model predicts the thermal resistance of the heat exchanger with a relative error in the interval [−8.09; 7.83] in the 95% of the cases. Finally, the use of thermosyphons with phase change in thermoelectric generators has been studied in a waste-heat recovery application, stating that including them on the cold side of the generators improves the net thermoelectric production by 36% compared to that obtained with finned dissipators under forced convection.

  17. Experimental study of heat transfer in a transverse flow around the heat exchanger tubes bank by lead

    International Nuclear Information System (INIS)

    Berezin, A.N.; Grabezhnaya, V.A.; Mikheev, A.S.; Parfenov, A.S.

    2014-01-01

    The results of the work to determine the heat transfer coefficient in crossflow by lead of pipes are presented. The study was conducted at supercritical pressure in the water circuit. There was a significant inequality in the distribution of the heat flow in different rows of the bundle of heat exchange tubes of corridor location at crossflow their lead. The experimentally determined heat transfer coefficients from the lead differ substantially from those generally accepted recommendations for the calculation of heat transfer at cross flow of rod bundle by liquid metal. The experimental results are close to those obtained earlier on the model with cross flow of heat exchanger tubes bundle by lead alloy with bismuth [ru

  18. Experimental study of heat transfer enhancement due to the surface vibrations in a flexible double pipe heat exchanger

    Science.gov (United States)

    Hosseinian, A.; Meghdadi Isfahani, A. H.

    2018-04-01

    In this study, the heat transfer enhancement due to the surface vibration for a double pipe heat exchanger, made of PVDF, is investigated. In order to create forced vibrations (3-9 m/s2, 100 Hz) on the outer surface of the heat exchanger electro-dynamic vibrators are used. Experiments were performed at inner Reynolds numbers ranging from 2533 to 9960. The effects of volume flow rate and temperature on heat transfer performance are evaluated. Results demonstrated that heat transfer coefficient increases by increasing vibration level and mass flow rate. The most increase in heat transfer coefficient is 97% which is obtained for the highest vibration level (9 m/s2) in the experiment range.

  19. Numerical Study of Condensation Heat Exchanger Design in a Cooling jacket: Correlation Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Kang, Han Ok; Lee, Tae Ho; Park, Cheon Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In this study, condensing heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without noncondensable gas effect (pure steam condensation) in a cooling jacket. From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah's correlation showed most satisfactory result for the condensation heat transfer coefficient with experimental data of Khun in a cooling jacket, whereas the Shah's correlation with experimental data of Lee. Lee et al. reported the improved Shah correlation gave us the best predictor for the condensation heat transfer data of Kim and Henderson in a subcooled and saturated water pool. They suggested the improved Shah correlation should be adopted as condensation heat transfer module in TSCON(Thermal Sizing of CONdenser) to design condensation heat exchanger in secondary passive cooling system of nuclear plant.

  20. Numerical Study of Condensation Heat Exchanger Design in a Cooling jacket: Correlation Investigation

    International Nuclear Information System (INIS)

    Kim, Myoung Jun; Lee, Hee Joon; Kang, Han Ok; Lee, Tae Ho; Park, Cheon Tae

    2013-01-01

    In this study, condensing heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without noncondensable gas effect (pure steam condensation) in a cooling jacket. From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah's correlation showed most satisfactory result for the condensation heat transfer coefficient with experimental data of Khun in a cooling jacket, whereas the Shah's correlation with experimental data of Lee. Lee et al. reported the improved Shah correlation gave us the best predictor for the condensation heat transfer data of Kim and Henderson in a subcooled and saturated water pool. They suggested the improved Shah correlation should be adopted as condensation heat transfer module in TSCON(Thermal Sizing of CONdenser) to design condensation heat exchanger in secondary passive cooling system of nuclear plant

  1. The study of development of welded compact plate heat exchanger for high temperature and pressure

    International Nuclear Information System (INIS)

    Park, Jae Hong; Lim, Hyug; Kim, Jung Kyu; Cho, Sung Youl; Kwon, Oh Boong

    2009-01-01

    In view of space saving, the design of more compact heat exchangers is relatively important. Also, to meet the demand for saving energy and resources today, manufacturers are trying to enhance efficiency and reduce the size and weight of heat exchangers. Over the past decade, there has been tremendous advancement in the manufacturing technology of high efficiency heat exchangers. This has allowed the use of smaller and high performance heat exchangers. Consequently, the use of smaller and high performance heat exchanger becomes popular in the design of heat exchangers. Welded compact plate heat exchanger is used in high temperature and pressure. In the design of heat exchanger, it is necessary to understand the heat transfer characteristics, so performance data are provided to help design of this type heat exchanger.

  2. Study regarding the influence of the crimping angle on the performances of the heat exchangers

    Directory of Open Access Journals (Sweden)

    Opruta D.

    2013-04-01

    Full Text Available The aim of this study is to determine the geometry of a plate for heat exchanger with high heat flow and low values for pressure losses. For this, in Solid Work software, were designed three plate geometries with different crimping angles for the flow channels. Was analyzed the influence of the crimping angle β on the fluid distribution and heat transfer. Also, were compared the data resulted from Computational Fluid Dynamics numeric simulation with the experimental ones for the plate heat exchangers with gaskets. The analysis of the vortices and temperature field distribution was achieved with the aid of simulation software Fluent. In order to validate the numerical simulation's results experimental research were carried out on a heat exchangers stand

  3. Update heat exchanger designing principles

    International Nuclear Information System (INIS)

    Lipets, A.U.; Yampol'skij, A.E.

    1985-01-01

    Update heat exchanger design principles are analysed. Different coolant pattern in a heat exchanger are considered. It is suggested to rationally organize flow rates irregularity in it. Applying on heat exchanger designing measures on using really existing temperature and flow rate irregularities will permit to improve heat exchanger efficiency. It is expedient in some cases to artificially produce irregularities. In this connection some heat exchanger design principles must be reviewed now

  4. Innovative heat exchangers

    CERN Document Server

    Scholl, Stephan

    2018-01-01

    This accessible book presents unconventional technologies in heat exchanger design that have the capacity to provide solutions to major concerns within the process and power-generating industries. Demonstrating the advantages and limits of these innovative heat exchangers, it also discusses micro- and nanostructure surfaces and micro-scale equipment, and introduces pillow-plate, helical and expanded metal baffle concepts. It offers step-by-step worked examples, which provide instructions for developing an initial configuration and are supported by clear, detailed drawings and pictures. Various types of heat exchangers are available, and they are widely used in all fields of industry for cooling or heating purposes, including in combustion engines. The market in 2012 was estimated to be U$ 42.7 billion and the global demand for heat exchangers is experiencing an annual growth of about 7.8 %. The market value is expected to reach U$ 57.9 billion in 2016, and approach U$ 78.16 billion in 2020. Providing a valua...

  5. Numerical study of a PCM-air heat exchanger's thermal performance

    Science.gov (United States)

    Herbinger, F.; Bhouri, M.; Groulx, D.

    2016-09-01

    In this paper, the use of PCMs in HVAC applications is investigated by studying numerically the thermal performance of a PCM-air heat exchanger. The PCM used in this study is dodecanoic acid. A symmetric 3D model, incorporating conductive and convective heat transfer (air only) as well as laminar flow, was created in COMSOL Multiphysics 5.0. Simulations examined the dependence of the heat transfer rate on the temperature and velocity of the incoming air as well as the size of the channels in the heat exchanger. Results indicated that small channels size lead to a higher heat transfer rates. A similar trend was also obtained for high incoming air temperature, whereas the heat transfer rate was less sensitive to the incoming air velocity.

  6. Cooperation of Horizontal Ground Heat Exchanger with the Ventilation Unit During Summer - Case Study

    Science.gov (United States)

    Romańska-Zapała, Anna; Furtak, Marcin; Dechnik, Mirosław

    2017-10-01

    Renewable energy sources are used in the modern energy-efficient buildings to improve their energy balance. One of them is used in the mechanical ventilation system ground air heat exchanger (earth-air heat exchanger - EAHX). This solution, right after heat recovery from exhaust air (recuperation), allows the reduction in the energy needed to obtain the desired temperature of supply air. The article presents the results of "in situ" measurements of pipe ground air heat exchanger cooperating with the air handling unit, supporting cooling the building in the summer season, in Polish climatic conditions. The laboratory consists of a ventilation unit intake - exhaust with rotor for which the source of fresh air is the air intake wall and two air intakes field cooperating with the tube with ground air heat exchangers. Selection of the source of fresh air is performed using sprocket with actuators. This system is part of the ventilation system of the Malopolska Laboratory of Energy-Efficient Building (MLBE) building of Cracow University of Technology. The measuring system are, among others, the sensors of parameters of air inlets and outlets of the heat exchanger channels EAHX and weather station that senses the local weather conditions. The measurement data are recorded and archived by the integrated process control system in the building of MLBE. During the study measurements of operating parameters of the ventilation unit cooperating with the selected source of fresh air were performed. Two cases of operation of the system: using EAHX heat exchanger and without it, were analyzed. Potentially the use of ground air heat exchanger in the mechanical ventilation system can reduce the energy demand for heating or cooling rooms by the pre-adjustment of the supply air temperature. Considering the results can be concluded that the continuous use of these exchangers is not optimal. This relationship is appropriate not only on an annual basis for the transitional periods (spring

  7. Performance study of a fin and tube heat exchanger with different fin geometry

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2016-01-01

    This study analyses the effect of different fin geometries on the heat transfer and pressure loss characteristics of a fin and tube heat exchanger. A numerical investigation is carried out on liquid–gas type double-finned tube heat exchanger under cross-flow condition. Three different cross......-sections namely: a) Rectangular, b) Trapezoidal, c) Triangular are adopted to define the fin geometry. The CFD simulations are performed to incorporate coupled steady state conjugate heat transfer with the turbulent flow phenomenon for the Reynolds number in the range of 5000-13000. Dimensionless heat transfer...... models show that triangular fin geometry can provide higher heat transfer performance in comparison to the fins with rectangular and trapezoidal geometry with lower pressure loss and a bonus of 7.27% reduction in weight under similar operating conditions....

  8. Study on drop pressure and flow distribution of double-tube heat exchanger

    International Nuclear Information System (INIS)

    Liu Junqiang; Chen Minghui; Hu Yumin; Li Rizhu; Kong Dechun; Zhang Weijie

    2007-01-01

    The parallel connection channel pressure drop characters of the double-tube bundle heat exchange were experimentally investigated in this paper in order to find out how the flow of the heat exchanger is distributed and then to optimize the structure of heat exchanger according to the flow distribution. A double-tube bundle heat exchanger was built according to the similarity criteria. The experiment system was also built to test the optimization of the heat exchanger. The experiment results reveal that the calculating model is reliable and decreasing pipe space to optimize the heat exchanger is reasonable. (authors)

  9. Heat exchanger vibration

    International Nuclear Information System (INIS)

    Richards, D.J.W.

    1977-01-01

    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

  10. Heat exchanger vibration

    Energy Technology Data Exchange (ETDEWEB)

    Richards, D J.W. [CERL, CEGB, Leatherhead, Surrey (United Kingdom)

    1977-12-01

    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.

  11. Tubular heat exchanger

    International Nuclear Information System (INIS)

    Hayden, Owen; Willby, C.R.

    1976-01-01

    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

  12. Experimental Study of Evaporative Heat Transfer Characteristics of R-134a with Channel-Bending Angle in Microchannel Heat Exchangers

    International Nuclear Information System (INIS)

    Lee, Hae Seung; Jeon, Dong Soon; Kim, Young Lyoul; Kim, Seon Chang

    2010-01-01

    Experimental investigations have been carried out to examine the evaporative heat transfer characteristics of R-134a with the channel-bending angle (CBA) in microchannel heat exchangers. In this study, we examined the effects of evaporation temperature and Reynolds number of R-134a on the evaporative heat transfer characteristics of R-134a in microchannel heat exchangers with CBAs of 120 .deg. , 150 .deg. , and 180 .deg. under counterflow conditions. Experimental results show that the evaporative heat transfer rate and evaporative heat transfer coefficient increased with an increase in the Reynolds number of R-134a. Further, the evaporative heat transfer rate corresponding to CBAs of 120 .deg. and 150 .deg. increased to values greater than the evaporative heat transfer rate corresponding to 180 .deg. by approximately 17.1% and 13.3%, respectively, for evaporating temperatures in the range 4.9-14.9 .deg. C. The evaporative heat transfer coefficient was affected by the channel angle with increasing evaporative heat transfer coefficient at small channel bending angle

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

    International Nuclear Information System (INIS)

    Liu Zhongliang; Wang Zengyi; Ma Chongfang

    2006-01-01

    In this part of the paper, the performance of the simultaneous charging/discharging operation modes of the heat pipe heat exchanger with latent heat storage is experimentally studied. The experimental results show that the device may operate under either the fluid to fluid heat transfer with charging heat to the phase change material (PCM) or the fluid to fluid heat transfer with discharging heat from the PCM modes according to the initial temperature of the PCM. The melting/solidification curves, the performances of the heat pipes and the device, the influences of the inlet temperature and the mass flow rate of the cold water on the operation performance are investigated by extensive experiments. The experimental results also disclose that under the simultaneous charging/discharging operation mode, although the heat transfer from the hot water directly to the cold water may vary, it always takes up a major part of the total heat recovered by the cold water due to the very small thermal resistance compared with the thermal resistance of the PCM side. The melting/solidification processes taking place in the simultaneous charging/discharging operation are compared with those in the charging only and discharging only processes. By applying a simplified thermal resistance analysis, a criterion for predicting the exact operation modes was derived and used to explain the observed experimental phenomena

  14. Cleaning Schedule Operations in Heat Exchanger Networks

    Directory of Open Access Journals (Sweden)

    Huda Hairul

    2018-01-01

    Full Text Available Heat exchanger networks have been known to be the essential parts in the chemical industries. Unfortunately, since the performance of heat exchanger can be decreasing in transferring the heat from hot stream into cold stream due to fouling, then cleaning the heat exchanger is needed to restore its initial performance periodically. A process of heating crude oil in a refinery plant was used as a case study. As many as eleven heat exchangers were used to heat crude oil before it was heated by a furnace to the temperature required to the crude unit distillation column. The purpose of this study is to determine the cleaning schedule of heat exchanger on the heat exchanger networks due to the decrease of the overall heat transfer coefficient by various percentage of the design value. A close study on the process of heat exchanger cleaning schedule in heat exchanger networks using the method of decreasing overall heat transfer coefficient as target. The result showed that the higher the fouling value the more often the heat exchanger is cleaned because the overall heat transfer coefficient decreases quickly.

  15. Study of a Coil Heat Exchanger with an Ice Storage System

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-12-01

    Full Text Available In this study, a coil heat exchanger with an ice storage system is analyzed by theoretical analysis, numerical analysis, and experimental analysis. The dynamic characteristics of ice thickness variation is studied by means of unstable heat conduction theory in cylindrical coordinates, and the change rule of the ice layer thickness is obtained. The computational fluid dynamics method is employed to simulate the flow field and ice melting process of the coil heat exchanger. The effect of the agitator height on the flow characteristics and heat transfer characteristics is investigated. The numerical results show that the turbulence intensity of the fluid near the wall of the heat exchanger is the largest with an agitator height of 80 mm. Furthermore, the process of ice melting is analyzed. The ice on the outer side of the evaporator tube close to the container wall melts faster than the inner side and this agrees well with the experimental result. The experimental study on the process of the operational period and deicing of the coil heat exchanger is conducted and the temperature variation curves are obtained by the arrangement of thermocouples. It is found that the temperature of the evaporating tube increases with increasing height in the process of ice storage.

  16. An optioneering and concept design study for the Astrid sodium-gas heat exchanger matrix

    International Nuclear Information System (INIS)

    Hattrell, T.; Lopez-Ramirez, S.; Pilatis, N.

    2014-01-01

    The ASTRID generation IV sodium cooled fast reactor design being developed by the CEA requires a component to transfer heat from the core to the power cycle. One of the ASTRID configurations currently being developed by the CEA uses a sodium to gas heat exchanger (SGHE) to fulfil this function. The design of the SGHE is challenging because of the high temperature of the sodium coolant and the significant pressure differential between the sodium and gas sides of the heat exchanger. This paper presents a study of the options examined for the ASTRID SGHE. A compact, superplastic formed diffusion bonded (SPF-DB) heat exchanger matrix (e.g. SGHE core) is proposed, based on the aerospace technology used by Rolls-Royce to manufacture light and strong wide chord fan blades for gas turbines. The in-house code CHESS is used to examine a number of feasible configurations for the matrix of the heat exchanger component and an optimisation study to maximise the thermal and mechanical performance of the most promising configurations is reported. The optimal matrix geometry identified by the study has a power density for the heat transfer region 157%1 greater than the baseline geometry (authors)

  17. Experimental study on the effects of the number of heat exchanger modules on thermal characteristics in a premixed combustion system

    International Nuclear Information System (INIS)

    Yu, Byeonghun; Lee, Chang-Eon; Kum, Sung Min; Lee, Seungro

    2016-01-01

    The effects of the number of heat exchanger modules on thermal characteristics were experimentally studied in a premixed combustion system with a cross-flow staggered-tube heat exchanger. The various heat exchanger modules, from 4 to 8, combined with a premixed burner were tested to investigate the performance of the heat exchanger through the surface area of the heat exchanger at various equivalence ratios. Additionally, the performance of the heat exchanger was analyzed by applying entropy generation theory to the heat exchanger system. As a result, although the heat transfer rate increases with the increase of the equivalence ratio, the NOx and CO concentrations also increase due to the increasing flame temperature. In addition, the entropy generation increases with an increase of the equivalence ratio. Furthermore, the heat transfer rate and the effectiveness are increased with the increase of the number of the heat exchanger modules. Also, the effectiveness is sharply increased when the number of the heat exchanger modules is increased from 4 to 5. Consequently, the optimal operating conditions regarding pollutant emission, effectiveness and entropy generation in this experimental range are 0.85 for the equivalence ratio and 8 for the number of heat exchanger modules

  18. Radiation effects on heat transfer in heat exchangers, (2)

    International Nuclear Information System (INIS)

    Mori, Yasuo; Watanabe, Kenji; Taira, Tatsuji.

    1980-01-01

    In a high temperature gas-cooled reactor system, in which the working fluid exchanges heat at high temperature near 1000 deg C, the heat transfer acceleration by positively utilizing the radiation heat transfer between solid surfaces should be considered. This paper reports on the results of experiment and analysis for the effects of radiant heat on the heat transfer performance at elevated temperature by applying the heat transfer-accelerating method using radiators to the heat exchanger with tube bundle composed of two channels of heating and heated sides. As the test heat exchangers, a parallel counter flow exchanger and the cross flow exchanger simulating helical tubes were employed, and the results studied on the characteristics of each heat exchanger are described. The plates placed in parallel to flow in every space of the tube bundle arranged in a matrix were used as the heat transfer accelerator. The effects of acceleration with the plates were the increase of heat transmission from 12 to 24% and 12 to 38% in the parallel flow and cross flow heat exchangers, respectively. Also, it was clarified that the theoretical analysis, in which it was assumed that the region within pitch S and two radiator plates, with a heat-transferring tube placed at the center, is the minimum domain for calculation, and that the heat exchange by radiation occurs only between the domain and the adjacent domains, can estimate the heat transfer-accelerating effect and the temperature distribution in a heat exchanger with sufficient accuracy. (Wakatsuki, Y.)

  19. Preliminary study on high temperature heat exchanger for nuclear steel making

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, T; Ohtomo, A; Yamada, R; Suzuki, K; Narita, Y [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1975-05-01

    Both in the high temperature heat exchanger and in the steam reformer, there remain several technical problems to be solved before nuclear steel making is actualized. The loop for use with basic studies of those problems was planned by the Iron and Steel Institute of Japan (ISIJ), and its actual design, construction and co-ordination of tests were undertaken by IHI on behalf of ISIJ. The primary coolant used in the loop was helium having a pressure of approx. 12 kg/cm/sup 2/g and a temperature of approx. 1100/sup 0/C at the inlet of the high temperature heat exchanger, i.e., the test section. Steam, hydrogen, and carbon monoxide were used as secondary coolants. Of the technical problems regarding the high temperature heat exchanger for nuclear steel making, which were selected and studied using the loop, the following items are discussed: (1) heat exchange performance using helium and steam; (2) hydrogen permeation of heat resisting alloys; (3) creep and carburization of heat resisting alloys; amd (4) hydrogen absorption performance of the titanium sponge.

  20. Manufacture of heat exchangers

    International Nuclear Information System (INIS)

    Burton, J.E.; Tombs, R.W.T.

    1980-01-01

    A tube bundle for use in a heat exchanger has a series of spaced parallel tubes supported by tube plates and is manufactured by depositing welding material around the end of each tube, machining the deposited material to form an annular flange around the end of the tube and welding the flange into apertures in the tube plate. Preferably the tubes have a length which is slightly less than the distance between the outer surfaces of the tube plates and the deposited material is deposited so that it overlaps and protects the end surfaces of the tubes. A plug may be inserted in the bore of the tubes during the welding material deposition which, as described, is effected by manual metal arc welding. One use of heat exchangers incorporating a tube bundle manufactured as above is in apparatus for reducing the volume of, and recovering nitric acid from, radioactive effluents from a nuclear reprocessing plant. (author)

  1. A Study on the Structural Integrity Considering the Installation of a Micro-tube Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Se Yun; Kim, Tae Jin; Cho, Jong Rae [Korea Maritime and Ocean University, Busan (Korea, Republic of); Jeong, Ho Sung [Pusan National University, Busan (Korea, Republic of)

    2015-04-15

    The objective of this study is to predict the structural characteristics of a heat exchanger mounted on an aircraft engine using finite element analysis. The plastic fracture and life of the heat exchanger were estimated by a thermo-mechanical analysis. Tensile tests were conducted under high temperature conditions (700, 800, 900, 1000 K) using five specimens to obtain the mechanical properties of the Inconel 625 tubes. To assess the structural characteristics of the heat exchanger, the full and partial models were applied under the operating conditions given by the thermo-mechanical and inertial load. As a result, the case, tubesheet, flange, and mounting components have a reasonable safety margin to the allowable stress assuming a fatigue strength of Inconel 625 of 10000 cycles under 1000 K.

  2. A Study on the Structural Integrity Considering the Installation of a Micro-tube Heat Exchanger

    International Nuclear Information System (INIS)

    Oh, Se Yun; Kim, Tae Jin; Cho, Jong Rae; Jeong, Ho Sung

    2015-01-01

    The objective of this study is to predict the structural characteristics of a heat exchanger mounted on an aircraft engine using finite element analysis. The plastic fracture and life of the heat exchanger were estimated by a thermo-mechanical analysis. Tensile tests were conducted under high temperature conditions (700, 800, 900, 1000 K) using five specimens to obtain the mechanical properties of the Inconel 625 tubes. To assess the structural characteristics of the heat exchanger, the full and partial models were applied under the operating conditions given by the thermo-mechanical and inertial load. As a result, the case, tubesheet, flange, and mounting components have a reasonable safety margin to the allowable stress assuming a fatigue strength of Inconel 625 of 10000 cycles under 1000 K

  3. AN EXPERIMENTAL STUDY ON A VAPOR COMPRESSION REFRIGERATION CYCLE BY ADDING INTERNAL HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Muhammad Asmail Eleiwi

    2013-05-01

    Full Text Available Thispaper presents practical study to improve the indication COP of a vaporcompression refrigeration cycle in instrumented automobile air conditioner bydesigning internal heat exchanger and installing it in the vapor compressionrefrigeration cycle.  Two cases of  vapor compression refrigeration cycle were takenin this paper:  the first case is thatthe vapor compression refrigeration cycle without internal heat exchanger andin  the second case the vapor compressionrefrigeration cycle with heat exchanger ; in these two cases, the temperatureat each point of  a vapor compressionrefrigeration cycle, the low and the high pressure ,the indoor temperature andthe outdoor temperature were measured at each time at compressor speed 1450 rpmand 2900 rpm for each blower speed 1, blower speed 2 and blower speed 3.Therefrigerant fluid was used in the vapor compression refrigeration cycle withoutIHE and with IHE is R134a..

  4. Upright heat exchanger

    International Nuclear Information System (INIS)

    Martoch, J.; Kugler, V.; Krizek, V.; Strmiska, F.

    1988-01-01

    The claimed heat exchanger is characteristic by the condensate level being maintained directly in the exchanger while preserving the so-called ''dry'' tube plate. This makes it unnecessary to build another pressure vessel into the circuit. The design of the heat exchanger allows access to both tube plates, which facilitates any repair. Another advantage is the possibility of accelerating the indication of leakage from the space of the second operating medium which is given by opening the drainage pipes of the lower bundle into the collar space and from there through to the indication pipe. The exchanger is especially suitable for deployment in the circuits of nuclear power plants where the second operating medium will be hot water of considerably lower purity than is that of the condensate. A rapid display of leakage can prevent any long-term penetration of this water into the condensate, which would result in worsening water quality in the entire secondary circuit of the nuclear power plant. (J.B.). 1 fig

  5. Heat exchanger tube tool

    International Nuclear Information System (INIS)

    Gugel, G.

    1976-01-01

    Certain types of heat-exchangers have tubes opening through a tube sheet to a manifold having an access opening offset from alignment with the tube ends. A tool for inserting a device, such as for inspection or repair, is provided for use in such instances. The tool is formed by a flexible guide tube insertable through the access opening and having an inner end provided with a connector for connection with the opening of the tube in which the device is to be inserted, and an outer end which remains outside of the chamber, the guide tube having adequate length for this arrangement. A flexible transport hose for internally transporting the device slides inside of the guide tube. This hose is long enough to slide through the guide tube, into the heat-exchanger tube, and through the latter to the extent required for the use of the device. The guide tube must be bent to reach the end of the heat-exchanger tube and the latter may be constructed with a bend, the hose carrying anit-friction elements at interspaced locations along its length to make it possible for the hose to negotiate such bends while sliding to the location where the use of the device is required

  6. Parametric study of a capillary tube-suction line heat exchanger in a transcritical CO2 heat pump cycle

    International Nuclear Information System (INIS)

    Agrawal, Neeraj; Bhattacharyya, Souvik

    2008-01-01

    The capillary tube in a transcritical CO 2 system behaves differently as temperature and pressure are two independent parameters unlike those in a sub-critical cycle. A capillary tube-suction line heat exchanger (CL-SLHX) in a transcritical vapour compression cycle considering homogeneous two-phase flow is modelled in this study based on mass, energy and momentum equations. Effects of gas cooler temperature, evaporator temperature and internal diameter of capillary tube are investigated. Heat transfer rate is observed to be influenced by refrigerant quality, mass flow rate and the prevailing temperature difference. Heat transfer rate variation with gas cooler temperature is unique, recording an initial increase followed by a decrease. Frictional pressure drop influences the heat transfer; consequently, chances of re-condensation of refrigerant vapour are very marginal. Larger diameter of capillary tube leads to increase in refrigerant mass flow rate and increase in heat transfer rate as well. Shorter inlet adiabatic capillary length with larger heat exchanger length is better for heat transfer. This study is an attempt to dispel the scepticism prevailing in transcritical CO 2 system community overemphasising the need for a throttle valve to control the optimum discharge pressure

  7. Studi Eksperimen Pengaruh Variasi Kecepatan Udara Terhadap Performa Heat Exchanger Jenis Compact Heat Exchanger (Radiator) Dengan Susunan Tube Inline Sebagai Pemanas Pada Sistem Pengeringan Batubara

    OpenAIRE

    Irvan Paramananda; Prabowo Prabowo

    2014-01-01

    Pengeringan yang dilakukan pada batu bara dengan memanfaatkan udara panas menggunakan konsep heat exchanger. Salah satu heat exchanger yang sering digunakan adalah heat exchanger dengan tipe single row-fin tube yaitu radiator. Radiator ini akan dimanfaatkan sebagai penghasil udara panas dari air panas yang mengalir dan dihembuskan oleh kipas radiator. Penelitian ini difokuskan pada effectiveness dari komponen radiator fungsi dari kecepatan udara mulai dari kecepatan 1 m/s, 2 m/s, 3 m/s, 4 m/s...

  8. Parametric Sensitivity Study of Operating and Design Variables in Wellbore Heat Exchangers

    International Nuclear Information System (INIS)

    Nalla, G.; Shook, G.M.; Mines, G.L.; Bloomfield, K.K.

    2004-01-01

    This report documents the results of an extensive sensitivity study conducted by the Idaho National Engineering and Environmental Laboratory. This study investigated the effects of various operating and design parameters on wellbore heat exchanger performance to determine conditions for optimal thermal energy extraction and evaluate the potential for using a wellbore heat exchanger model for power generation. Variables studied included operational parameters such as circulation rates, wellbore geometries and working fluid properties, and regional properties including basal heat flux and formation rock type. Energy extraction is strongly affected by fluid residence time, heat transfer contact area, and formation thermal properties. Water appears to be the most appropriate working fluid. Aside from minimal tubing insulation, tubing properties are second order effects. On the basis of the sensitivity study, a best case model was simulated and the results compared against existing low-temperature power generation plants. Even assuming ideal work conversion to electric power, a wellbore heat exchange model cannot generate 200 kW (682.4e+3 BTU/h) at the onset of pseudosteady state. Using realistic conversion efficiency, the method is unlikely to generate 50 kW (170.6e+3 BTU/h)

  9. A Simulation Study of Inter Heat Exchanger Process in SI Cycle Process for Hydrogen Production

    International Nuclear Information System (INIS)

    Shin, Jae Sun; Cho, Sung Jin; Choi, Suk Hoon; Qasim, Faraz; Lee, Euy Soo; Park, Sang Jin; Lee, Heung N.; Park, Jae Ho; Lee, Won Jae

    2014-01-01

    SI Cyclic process is one of the thermochemical hydrogen production processes using iodine and sulfur for producing hydrogen molecules from water. VHTR (Very High Temperature Reactor) can be used to supply heat to hydrogen production process, which is a high temperature nuclear reactor. IHX (Intermediate Heat Exchanger) is necessary to transfer heat to hydrogen production process safely without radioactivity. In this study, the strategy for the optimum design of IHX between SI hydrogen process and VHTR is proposed for various operating pressures of the reactor, and the different cooling fluids. Most economical efficiency of IHX is also proposed along with process conditions

  10. Compact cryocooler heat exchangers

    International Nuclear Information System (INIS)

    Luna, J.; Frederking, T.H.K.

    1991-01-01

    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

  11. Design for manufacturability of macro and micro products: a case study of heat exchanger design

    DEFF Research Database (Denmark)

    Omidvarnia, F.; Weng Feng, L.; Hansen, H. N.

    2018-01-01

    In this paper, a novel methodology in designing a micro heat exchanger is proposed by modifying a conventional design methodology for macro products with the considerations of differences between design of a micro and a macro product. The methodology starts with the identification of differences...... for fabricating micro heat exchangers are ranked based on the defined criteria. Following the design methodology, primary design ideas for micro heat exchangers are generated according to the heat transfer principles for macro heat exchangers. Taking micro design considerations into account, the designs from next...... iteration are created. Finally, the performances of the designs for micro heat exchangers are compared with their macro counterparts. The most appropriate designs for micro heat exchangers are finalized. The micro specific design guidelines obtained by the designer through evaluating the modeling results...

  12. Heat exchanger performance monitoring guidelines

    International Nuclear Information System (INIS)

    Stambaugh, N.; Closser, W. Jr.; Mollerus, F.J.

    1991-12-01

    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

  13. Experimental study on heat transfer performance of fin-tube exchanger and PSHE for waste heat recovery

    Science.gov (United States)

    Chen, Ting; Bae, Kyung Jin; Kwon, Oh Kyung

    2018-02-01

    In this paper, heat transfer characteristics of fin-tube heat exchanger and primary surface heat exchanger (PSHE) used in waste heat recovery were investigated experimentally. The flow in the fin-tube heat exchanger is cross flow and in PSHE counter flow. The variations of friction factor and Colburn j factor with air mass flow rate, and Nu number with Re number are presented. Various comparison methods are used to evaluate heat transfer performance, and the results show that the heat transfer rate of the PSHE is on average 17.3% larger than that of fin-tube heat exchanger when air mass flow rate is ranging from 1.24 to 3.45 kg/min. However, the PSHE causes higher pressure drop, and the fin-tube heat exchanger has a wider application range which leads to a 31.7% higher value of maximum heat transfer rate compared to that of the PSHE. Besides, under the same fan power per unit frontal surface, a higher heat transfer rate value is given in the fin-tube heat exchanger.

  14. Heat exchange studies on coconut oil cells as thermal energy storage for room thermal conditioning

    Science.gov (United States)

    Sutjahja, I. M.; Putri, Widya A.; Fahmi, Z.; Wonorahardjo, S.; Kurnia, D.

    2017-07-01

    As reported by many thermal environment experts, room air conditioning might be controlled by thermal mass system. In this paper we discuss the performance of coconut oil cells as room thermal energy storage. The heat exchange mechanism of coconut oil (CO) which is one of potential organic Phase Change Material (PCM) is studied based on the results of temperature measurements in the perimeter and core parts of cells. We found that the heat exchange performance, i.e. heat absorption and heat release processes of CO cells are dominated by heat conduction in the sensible solid from the higher temperature perimeter part to the lower temperature core part and heat convection during the solid-liquid phase transition and sensible liquid phase. The capability of heat absorption as measured by the reduction of air temperature is not influenced by CO cell size. Besides that, the application of CO as the thermal mass has to be accompanied by air circulation to get the cool sensation of the room’s occupants.

  15. Numerical study on turbulent heat transfer and pressure drop of nanofluid in coiled tube-in-tube heat exchangers

    International Nuclear Information System (INIS)

    Aly, Wael I.A.

    2014-01-01

    Highlights: • The performance of helically coiled tube heat exchanger using nanofluid is modeled. • The 3D turbulent flow and conjugate heat transfer of CTITHE are solved using FVM. • The effects of nanoparticle concentration and curvature ratio are investigated. • The Gnielinski correlation for Nu for turbulent flow in helical tubes can be used for water-based Al 2 O 3 nanofluid. - Abstract: A computational fluid dynamics (CFD) study has been carried out to study the heat transfer and pressure drop characteristics of water-based Al 2 O 3 nanofluid flowing inside coiled tube-in-tube heat exchangers. The 3D realizable k–ε turbulent model with enhanced wall treatment was used. Temperature dependent thermophysical properties of nanofluid and water were used and heat exchangers were analyzed considering conjugate heat transfer from hot fluid in the inner-coiled tube to cold fluid in the annulus region. The overall performance of the tested heat exchangers was assessed based on the thermo-hydrodynamic performance index. Design parameters were in the range of; nanoparticles volume concentrations 0.5%, 1.0% and 2.0%, coil diameters 0.18, 0.24 and 0.30 m, inner tube and annulus sides flow rates from 2 to 5 LPM and 10 to 25 LPM, respectively. Nanofluid flows inside inner tube side or annular side. The results obtained showed a different behavior depending on the parameter selected for the comparison with the base fluid. Moreover, when compared at the same Re or Dn, the heat transfer coefficient increases by increasing the coil diameter and nanoparticles volume concentration. Also, the friction factor increases with the increase in curvature ratio and pressure drop penalty is negligible with increasing the nanoparticles volume concentration. Conventional correlations for predicting average heat transfer and friction factor in turbulent flow regime such as Gnielinski correlation and Mishra and Gupta correlation, respectively, for helical tubes are also valid for

  16. Studies on direct liquid-liquid heat exchange in the context of seawater desalination

    International Nuclear Information System (INIS)

    Frederking, R.

    1974-01-01

    In order to lower the operational costs of a sea water desalination plant working by the evaporation principle, an economical heat flow must be provided for amongst other measures. This may be done by utilizing the heat content of newly condensed fresh water for preheating sea water. The easiest way would be a heat exchange between the sea water and the desalinated condensate, e.g. in a counter-flow tube bundle heat exchanger, and to compensate the heat loss by means of an additional heating unit. However, operational experience with this type of heat exchanger has shown that the metal walls on the sea water side get encrusted with hardly soluble salts even after only a short period of operation. Consequently, the heat-transmission resistance increases, so that expensive cleaning of the heat exchangers is necessary after only a few hours of operation already. (orig./TK) [de

  17. Fundamental basis and implementation of shell and tube heat exchanger project design: condenser and evaporator study

    Science.gov (United States)

    Dalkilic, A. S.; Acikgoz, O.; Tapan, S.; Wongwises, S.

    2016-12-01

    A shell and tube heat exchanger is used as a condenser and an evaporator in this theoretical study. Parametric performance analyses for various actual refrigerants were performed using well-known correlations in open sources. Condensation and evaporation were occurred in the shell side while the water was flowing in the tube side of heat exchanger. Heat transfer rate from tube side was kept constant for condenser and evaporator design. Condensing temperatures were varied from 35 to 60 °C whereas evaporating temperatures were ranging from -15 to 10 °C for the refrigerants of R12, R22, R134a, R32, R507A, R404A, R502, R407C, R152A, R410A and R1234ZE. Variation of convective heat transfer coefficients of refrigerants, total heat transfer coefficients with Reynolds numbers and saturation temperatures were given as validation process considering not only fouling resistance and omission of it but also staggered (triangular) and line (square) arrangements. The minimum tube lengths and necessary pumping powers were calculated and given as case studies for the investigated refrigerants considering validation criteria. It was understood that refrigerant type, fouling resistance and arrangement type are one of the crucial issues regarding the determination of heat exchanger's size and energy consumption. Consequently, R32 and R152a were found to require the shortest tube length and lowest pumping power in the condenser, whereas R507 and R407C have the same advantages in the evaporator. Their heat transfer coefficients were also determined larger than others as expectedly.

  18. Parametric CFD Analysis to Study the Influence of Fin Geometry on the Performance of a Fin and Tube Heat Exchanger

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2016-01-01

    Heat transfer and pressure loss characteristics of a fin and tube heat exchanger are numerically investigated based on parametric fin geometry. The cross-flow type heat exchanger with circular tubes and rectangular fin profile is selected as a reference design. The fin geometry is varied using...... a design aspect ratio as a variable parameter in a range of 0.1-1.0 to predict the impact on overall performance of the heat exchanger. In this paper, geometric profiles with a constant thickness of fin base are studied. Three-dimensional, steady state CFD model is developed using commercially available...... are determined. The best performed geometric fin profile based on the higher heat transfer and lower pressure loss is predicted. The study provides insights into the impact of fin geometry on the heat transfer performance which help escalate the understanding of heat exchanger designing and manufacturing...

  19. Fluidised bed heat exchangers

    International Nuclear Information System (INIS)

    Elliott, D.E.; Healey, E.M.; Roberts, A.G.

    1974-01-01

    Problems that have arisen during the initial stages of development of fluidised bed boilers in which heat transfer surfaces are immersed in fluidised solids are discussed. The very high heat transfer coefficients that are obtained under these conditions can be exploited to reduce the total heat transfer surface to a fraction of that in normal boilers. However, with the high heat flux levels involved, tube stressing becomes more important and it is advantageous to use smaller diameter tubes. One of the initial problems was that the pumping power absorbed by the fluidised bed appeared to be high. The relative influence of the fluidising velocity (and the corresponding bed area), tube diameter, tube spacing, heat transfer coefficient and bed temperature on pumping power and overall cost was determined. This showed the importance of close tube packing and research was undertaken to see if this would adversely affect the heat transfer coefficient. Pressure operation also reduces the pumping power. Fouling and corrosion tests in beds burning coal suggest that higher temperatures could be reached reliably and cost studies show that, provided the better refractory metals are used, the cost of achieving higher temperatures is not unduly high. It now remains to demonstrate at large scale that the proposed systems are viable and that the methods incorporated to overcome start up and part lead running problems are satisfactory. The promising role of these heat transfer techniques in other applications is briefly discussed

  20. Next Generation Microchannel Heat Exchangers

    CERN Document Server

    Ohadi, Michael; Dessiatoun, Serguei; Cetegen, Edvin

    2013-01-01

    In Next Generation Microchannel Heat Exchangers, the authors’ focus on the new generation highly efficient heat exchangers and presentation of novel data and technical expertise not available in the open literature.  Next generation micro channels offer record high heat transfer coefficients with pressure drops much less than conventional micro channel heat exchangers. These inherent features promise fast penetration into many mew markets, including high heat flux cooling of electronics, waste heat recovery and energy efficiency enhancement applications, alternative energy systems, as well as applications in mass exchangers and chemical reactor systems. The combination of up to the minute research findings and technical know-how make this book very timely as the search for high performance heat and mass exchangers that can cut costs in materials consumption intensifies.

  1. Catalytic heat exchangers for small-scale production of hydrogen - feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, F [Catator AB, Lund (Sweden)

    2002-02-01

    A feasibility study concerning heat-exchanger reactors in small-scale production of hydrogen has been performed on the request of Svenskt Gastekniskt Center AB and SWEP International AB. The basic idea is to implement different catalysts into brazed plate-type heat exchangers. This can be achieved by installing catalytic cylinders in the inlet-and outlet ports of the heat exchangers or through treatment of the plates to render them catalytically active. It is also possible to sandwich catalytically active wire meshes between the plates. Experiments concerning steam reforming of methanol and methane have been performed in a micro-reactor to gather kinetic data for modelling purposes. Performance calculations concerning heat exchanger reactors have then been conducted with Catator's generic simulation code for catalytic reactors (CatalystExplorer). The simulations clearly demonstrate the technical performance of these reactors. Indeed, the production rate of hydrogen is expected to be about 10 nm{sup 3}/h per litre of heat exchanger. The corresponding value for a conventional steam-reforming unit is about 1 nm{sup 3}/h or less per litre of reactor volume. Also, the compactness and the high degree of integration together with the possibilities of mass production will give an attractive cost for such units. Depending on the demands concerning the purity of the hydrogen it is possible to add secondary catalytic steps like water-gas shifters, methanation and selective oxidation, into a one-train unit, i.e. to design an all-inclusive design. Such reactors can be used for the supply of hydrogen to fuel cells. The production cost for hydrogen can be cut by 60 - 70% through the utilisation of heat exchanger reactors instead of conventional electrolysis. This result is primarily a result of the high price for electricity compared to the feed stock prices in steam reforming. It is important to verify the performance calculations and the simulation results through experimental

  2. Catalytic heat exchangers for small-scale production of hydrogen - feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, F. [Catator AB, Lund (Sweden)

    2002-02-01

    A feasibility study concerning heat-exchanger reactors in small-scale production of hydrogen has been performed on the request of Svenskt Gastekniskt Center AB and SWEP International AB. The basic idea is to implement different catalysts into brazed plate-type heat exchangers. This can be achieved by installing catalytic cylinders in the inlet-and outlet ports of the heat exchangers or through treatment of the plates to render them catalytically active. It is also possible to sandwich catalytically active wire meshes between the plates. Experiments concerning steam reforming of methanol and methane have been performed in a micro-reactor to gather kinetic data for modelling purposes. Performance calculations concerning heat exchanger reactors have then been conducted with Catator's generic simulation code for catalytic reactors (CatalystExplorer). The simulations clearly demonstrate the technical performance of these reactors. Indeed, the production rate of hydrogen is expected to be about 10 nm{sup 3}/h per litre of heat exchanger. The corresponding value for a conventional steam-reforming unit is about 1 nm{sup 3}/h or less per litre of reactor volume. Also, the compactness and the high degree of integration together with the possibilities of mass production will give an attractive cost for such units. Depending on the demands concerning the purity of the hydrogen it is possible to add secondary catalytic steps like water-gas shifters, methanation and selective oxidation, into a one-train unit, i.e. to design an all-inclusive design. Such reactors can be used for the supply of hydrogen to fuel cells. The production cost for hydrogen can be cut by 60 - 70% through the utilisation of heat exchanger reactors instead of conventional electrolysis. This result is primarily a result of the high price for electricity compared to the feed stock prices in steam reforming. It is important to verify the performance calculations and the simulation results through

  3. An experimental study on the thermal and fouling characteristics in a washable shell and helically coiled heat exchanger by the Wilson plot method

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Kyoung Min; Ahn, Young Chull [Pusan National University, Busan (Korea, Republic of); Hwang, Jun Hyeon; Hur, Hyun; Na, Byung Chul; Hwang, Yoon Jae; Kim, Byung Soon [LG Electronics, Changwon (Korea, Republic of); Lee, Jae Keun [EcoEnergy Research Institute, Busan (Korea, Republic of)

    2016-06-15

    Brazed plate heat exchangers (BPHEX) are broadly used in water source heat pump systems for their large heat transfer capacity. Despite their high heat transfer rate, their high-performance rate tends to decrease sharply, due to fouling and they cannot be cleaned. So the thermal and fouling resistances of washable Shell and helically coiled tube heat exchangers (SCHEX) are designed and experimentally investigated in this study. Heat exchangers with two different tube types are studied and compared with a brazed plate heat exchanger. The overall thermal resistance coefficient of the heat exchangers as determined by using Wilson plots is 38% lower than that of the brazed plate heat exchanger at a Reynolds number of 2460. Fouling test results revealed that regular maintenance and physical cleaning can be used to maintain the thermal resistance of fouling of the washable heat exchanger at a level equal to or less than that of the brazed plate heat exchanger.

  4. Heat pipes in modern heat exchangers

    International Nuclear Information System (INIS)

    Vasiliev, Leonard L.

    2005-01-01

    Heat pipes are very flexible systems with regard to effective thermal control. They can easily be implemented as heat exchangers inside sorption and vapour-compression heat pumps, refrigerators and other types of heat transfer devices. Their heat transfer coefficient in the evaporator and condenser zones is 10 3 -10 5 W/m 2 K, heat pipe thermal resistance is 0.01-0.03 K/W, therefore leading to smaller area and mass of heat exchangers. Miniature and micro heat pipes are welcomed for electronic components cooling and space two-phase thermal control systems. Loop heat pipes, pulsating heat pipes and sorption heat pipes are the novelty for modern heat exchangers. Heat pipe air preheaters are used in thermal power plants to preheat the secondary-primary air required for combustion of fuel in the boiler using the energy available in exhaust gases. Heat pipe solar collectors are promising for domestic use. This paper reviews mainly heat pipe developments in the Former Soviet Union Countries. Some new results obtained in USA and Europe are also included

  5. Experimental Study on the Airside Performance of Aluminum Heat Exchangers Having Slim Louver Fins

    International Nuclear Information System (INIS)

    Kim, Nae Hyun; Cho, Honggi

    2017-01-01

    Recent trends in slim air conditioners require heat exchangers of reduced flow depth. In this study, slim louver fin geometry was obtained using predictive correlations. The deduced geometry yielded 10 mm flow depth, 0.9 mm louver pitch, and 35° louver angle. Samples were made and tests were conducted. The new slim sample yielded 36% higher j factor and 2.3% higher f factor compared with those of the standard sample. This implies that 26% reduction of heat exchanger volume was possible by reducing the flow depth. In addition, the j/f1/3 of the slim sample was 55% larger than that of the standard sample. Furthermore, the results are compared with predictions made using existing correlations.

  6. Experimental Study on the Airside Performance of Aluminum Heat Exchangers Having Slim Louver Fins

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nae Hyun [Incheon Nat’l Univ., Incheon (Korea, Republic of); Cho, Honggi [Samsung Electronics Daejeon, Suwon (Korea, Republic of)

    2017-09-15

    Recent trends in slim air conditioners require heat exchangers of reduced flow depth. In this study, slim louver fin geometry was obtained using predictive correlations. The deduced geometry yielded 10 mm flow depth, 0.9 mm louver pitch, and 35° louver angle. Samples were made and tests were conducted. The new slim sample yielded 36% higher j factor and 2.3% higher f factor compared with those of the standard sample. This implies that 26% reduction of heat exchanger volume was possible by reducing the flow depth. In addition, the j/f1/3 of the slim sample was 55% larger than that of the standard sample. Furthermore, the results are compared with predictions made using existing correlations.

  7. Heat exchanger leakage problem location

    Directory of Open Access Journals (Sweden)

    Jícha Miroslav

    2012-04-01

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

  8. A study on the formation of fouling in a heat exchanging system for Han-river water as cooling water

    International Nuclear Information System (INIS)

    Sung, Sun Kyung; Suh, Sang Ho; Rho, Hyung Woon; Cho, Young Il

    2003-01-01

    Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When scale deposits in a heat exchanger surface, it is traditionally called fouling. The objective of the present study is to investigate the formation of fouling in a heat exchanging system. A lab-scale heat exchanging system is built-up to observe and measure the formation of fouling experimentally. Water analyses are conducted to obtain the properties of Han river water. In the present study a microscopic observation is conducted to visualize the process of scale formation. Hardness of Han-river water is higher than that of tap water in Seoul

  9. Theory and design of heat exchanger : Double pipe and heat exchanger in abnormal condition

    International Nuclear Information System (INIS)

    Min, Ui Dong

    1996-02-01

    This book introduces theory and design of heat exchanger, which includes HTRI program, multiple tube heat exchanger external heating, theory of heat transfer, basis of design of heat exchanger, two-phase flow, condensation, boiling, material of heat exchanger, double pipe heat exchanger like hand calculation, heat exchanger in abnormal condition such as Jackets Vessel, and Coiled Vessel, design and summary of steam tracing.

  10. Heat exchanges in coarsening systems

    Energy Technology Data Exchange (ETDEWEB)

    Corberi, Federico [Dipartimento di Fisica ' E R Caianiello' , Università di Salerno, via Ponte don Melillo, 84084 Fisciano (Italy); Gonnella, Giuseppe; Piscitelli, Antonio [Dipartimento di Fisica, Università di Bari and Istituto Nazionale di Fisica Nucleare, Sezione di Bari, via Amendola 173, 70126 Bari (Italy)

    2011-10-15

    This paper is a contribution to the understanding of the thermal properties of ageing systems where statistically independent degrees of freedom with greatly separated time scales are expected to coexist. Focusing on the prototypical case of quenched ferromagnets, where fast and slow modes can be respectively associated with fluctuations in the bulk of the coarsening domains and in their interfaces, we perform a set of numerical experiments specifically designed to compute the heat exchanges between different degrees of freedom. Our studies promote a scenario with fast modes acting as an equilibrium reservoir to which interfaces may release heat through a mechanism that allows fast and slow degrees to maintain their statistical properties independently.

  11. Study of alternative materials to minimize erosion in heat exchanger tubes used in thermoelectric generators

    Energy Technology Data Exchange (ETDEWEB)

    Arnt, A.B.C.; Paula, M.M. da S. Paula; Rocha, M.R. da; Angioletto, E.; Zanini, L.C.; Miranda, R.; Zanelatto, C.C. [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil)], e-mails: anb@unesc.net, mms@unesc.net, marcio2r@terra.com.br, an@unesc.net, elucaslcz@yahoo.com.br, frdgmiranda@hotmail.com, gcrisrincao20@yahoo.com.br; Felippe, L. [Universidade do Extremo Sul Catarinense (UNESC), Capivari de Baixo, SC (Brazil)], e-mail: hlfelippe@tractebelenergia.com.br

    2007-07-01

    comparison with the uncoated pipes located at the same heat exchanger. The real operation conditions of the coated pipes will be estimated from the field life cycle analysis, and after all the cost-benefit of the studied coating. (author)

  12. A study of flow patterns in a thermosyphon for compact heat exchanger applications

    NARCIS (Netherlands)

    Grooten, M.H.M.; Geld, van der C.W.M.; Deursen, van L.G.M.

    2008-01-01

    Recently, thermosyphons have attracted interest in the design of smaller, lighter and cheaper heat exchangers, because of their compactness, low thermal resistance, high heat recovery effectiveness, safety and reliability. In order to understand the effects of the angle of inclination on heat

  13. Heat exchanger design

    OpenAIRE

    Vítek, Tomáš

    2017-01-01

    Tato bakalářská práce řeší návrh výměníku tepla pro teplovodní kotel se zplyňovací komorou pro předehřev spalovacího vzduchu odpadním teplem spalin. Hodnoty pro výpočet byly experimentálně naměřeny. Práce obsahuje stručný popis trubkového výměníku tepla, stechiometrický vypočet spalování, návrh geometrických rozměrů výměníku, výpočet tlakových ztrát a výpočet výkonu. Její součástí je také výkresová dokumentace navrženého výměníku. This bachelor thesis solves design of a heat exchanger for ...

  14. Feasibility study on development of plate-type heat exchanger for BWR plants

    International Nuclear Information System (INIS)

    Ohyama, Nobuhiro; Suda, Kenichi; Ogata, Hiroshi; Matsuda, Shinichi; Nagasaka, Kazuhiro; Fujii, Toshi; Nozawa, Toshiya; Ishihama, Kiyoshi; Higuchi, Tomokazu

    2004-01-01

    In order to apply plate-type heat exchanger to RCW, TCW and FPC system in BWR plants, heat test and seismic test of RCW system heat exchanger sample were carried out. The results of these tests showed new design plate-type heat exchanger satisfied the fixed pressure resistance and seismic resistance and keep the function. The evaluation method of seismic design was constructed and confirmed by the results of tests. As anti-adhesion measure of marine organism, an ozone-water circulation method, chemical-feed method and combination of circulation of hot water and air bubbling are useful in place of the chlorine feeding method. Application of the plate-type heat exchanger to BWR plant is confirmed by these investigations. The basic principles, structure, characteristics, application limit and reliability are stated. (S.Y.)

  15. 3-D NUMERICAL STUDY AND COMPARISON OF ECCENTRIC AND CONCENTRIC ANNULAR-FINNED TUBE HEAT EXCHANGERS

    Directory of Open Access Journals (Sweden)

    FAROUK TAHROUR

    2015-11-01

    Full Text Available The use of 3-D computational fluid dynamics (CFD is proposed to simulate the conjugate conduction-convection of heat transfer problems in eccentric annularfinned tube heat exchangers. The numerical simulation results allow us to evaluate the heat transfer coefficient over fin surfaces, the fin efficiency and the pressure drop. The aim of the present paper is to determine the optimum tube position in the circular fin that maximizes heat dissipation and minimizes pressure drop. In addition, this study analyzes the effects of fin spacing and fin tube diameter on heat transfer and flow characteristics for a range of Reynolds numbers, 4500≤Re≤22500. A satisfactory qualitative and quantitative agreement was obtained between the numerical predictions and the results published in the literature. For small fin spacings, the eccentric annular finned tube is more efficient than the concentric one. Among the cases examined, the average heat transfer coefficient of the eccentric annular-finned tube, for a tube shift St =12 mm and a Reynolds number Re = 9923, was 7.61% greater than that of the concentric one. This gain is associated with a 43.09% reduction in pressure drop.

  16. Review: heat pipe heat exchangers at IROST

    OpenAIRE

    E. Azad

    2012-01-01

    The use of the heat pipe as a component in a heat recovery device has gained worldwide acceptance. Heat pipes are passive, highly reliable and offer high heat transfer rates. This study summarizes the investigation of different types of heat pipe heat recovery systems (HPHRSs). The studies are classified on the basis of the type of the HPHRS. This research is based on 30 years of experience on heat pipe and heat recovery systems that are presented in this study. Copyright , Oxford University ...

  17. Preliminary study on high temperature heat exchanger for nuclear steel making

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Y [Tokyo Inst. of Tech. (Japan); Ikegami, H

    1975-03-01

    In the high temperature heat exchanger as well as the steam reformer, several technical problems should be solved before realizing a nuclear plant complex for iron and steel making. Research has been carried out on heat exchanger between helium and steam, hydrogen permeation through super alloys, hydrogen removal using a titanium sponge, and creep and carburization performance of super alloys. The primary coolant used is helium having a pressure of approximately 12 kg/cm/sup 2/G and a temperature of approximately 1100/sup 0/C measured at the inlet of the high temperature heat exchanger, i.e., the test section. Steam, hydrogen and carbon monoxide are used as secondary coolants.

  18. The Study on bonding test of Inconel 617 Heat Exchanger by Measuring Properties

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Il Hwan; Song, Chan Ho; Yoon, Seok Ho; Park, Sang Jin [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2014-05-15

    Basic materials are not melted and bonded through the diffusion of atoms. It is different from welding in a view point of not melting and additional bonding insertion materials are not used which is different from the method in brazing. This bonding method is favor for ultra high temperature and pressure condition, and the bonding part becomes almost same structure and property with high heat resistance and strength when it is compared with brazing method. But the process time is long and the cost is high. The quantitative analysis in bonding surface has not been suggested yet. In this paper, the bonding performance for diffusion bonded heat exchanger is examined and analyzed where its material is Inconel 617. thermal and mechanical properties such as thermal diffusivity and tensile strength are measured and compared for different bonding conditions. In this study, the bonding performance for heat exchanger using Inconel 617 is analyzed by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength. The following results are obtained. From measuring thermal diffusivity, it is found that the difference between the diffusion bonded plates and bond failed plates is within 3%. The tensile strength in diffusion bonding is about 25% lower than that of original plate at 1150 .deg. C, but it is over 600 MPa. As bonding temperature increases, the size of grain boundary decreases From these results, the possibility for Inconel 617 heat exchanger under the high temperature and pressure through diffusion bonding process could be obtained and it is thought to be applied for many industrial equipment.

  19. The Study on bonding test of Inconel 617 Heat Exchanger by Measuring Properties

    International Nuclear Information System (INIS)

    Cho, Il Hwan; Song, Chan Ho; Yoon, Seok Ho; Park, Sang Jin

    2014-01-01

    Basic materials are not melted and bonded through the diffusion of atoms. It is different from welding in a view point of not melting and additional bonding insertion materials are not used which is different from the method in brazing. This bonding method is favor for ultra high temperature and pressure condition, and the bonding part becomes almost same structure and property with high heat resistance and strength when it is compared with brazing method. But the process time is long and the cost is high. The quantitative analysis in bonding surface has not been suggested yet. In this paper, the bonding performance for diffusion bonded heat exchanger is examined and analyzed where its material is Inconel 617. thermal and mechanical properties such as thermal diffusivity and tensile strength are measured and compared for different bonding conditions. In this study, the bonding performance for heat exchanger using Inconel 617 is analyzed by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength. The following results are obtained. From measuring thermal diffusivity, it is found that the difference between the diffusion bonded plates and bond failed plates is within 3%. The tensile strength in diffusion bonding is about 25% lower than that of original plate at 1150 .deg. C, but it is over 600 MPa. As bonding temperature increases, the size of grain boundary decreases From these results, the possibility for Inconel 617 heat exchanger under the high temperature and pressure through diffusion bonding process could be obtained and it is thought to be applied for many industrial equipment

  20. Simulation and experimental study on thermal optimization of the heat exchanger for automotive exhaust-based thermoelectric generators

    Directory of Open Access Journals (Sweden)

    C.Q. Su

    2014-11-01

    Full Text Available Thermoelectric technology has revealed the potential for automotive exhaust-based thermoelectric generator (TEG, which contributes to the improvement of the fuel economy of the engine-powered vehicle. As a major factor, thermal capacity and heat transfer of the heat exchanger affect the performance of TEG effectively. With the thermal energy of exhaust gas harvested by thermoelectric modules, a temperature gradient appears on the heat exchanger surface, so as the interior flow distribution of the heat exchanger. In order to achieve uniform temperature distribution and higher interface temperature, the thermal characteristics of heat exchangers with various heat transfer enhancement features are studied, such as internal structure, material and surface area. Combining the computational fluid dynamics simulations and infrared test on a high-performance engine with a dynamometer, the thermal performance of the heat exchanger is evaluated. Simulation and experiment results show that a plate-shaped heat exchanger made of brass with accordion-shaped internal structure achieves a relatively ideal performance, which can practically improve overall thermal performance of the TEG.

  1. Study on Fins' Effect of Boiling Flow in Millimeter Channel Heat Exchanger

    Science.gov (United States)

    Watanabe, Satoshi

    2005-11-01

    Recently, a lot of researches about compact heat exchangers with mini-channels have been carried out with the hope of obtaining a high-efficiency heat transfer, due to the higher ratio of surface area than existing heat exchangers. However, there are many uncertain phenomena in fields such as boiling flow in mini-channels. Thus, in order to understand the boiling flow in mini-channels to design high-efficiency heat exchangers, this work focused on the visualization measurement of boiling flow in a millimeter channel. A transparent acrylic channel (heat exchanger form), high-speed camera (2000 fps at 1024 x 1024 pixels), and halogen lamp (backup light) were used as the visualization system. The channel's depth is 2 mm, width is 30 mm, and length is 400 mm. In preparation for commercial use, two types of channels were experimented on: a fins type and a normal slit type (without fins). The fins are circular cylindrical obstacles (diameter is 5 mm) to promote heat transfer, set in a triangular array (distance between each center point is 10 mm). Especially in this work, boiling flow and heat transfer promotion in the millimeter channel heat exchanger with fins was evaluated using a high-speed camera.

  2. High temperature alloys and ceramic heat exchanger

    International Nuclear Information System (INIS)

    Okamoto, Masaharu

    1984-04-01

    From the standpoint of energy saving, the future operating temperatures of process heat and gas turbine plants will become higher. For this purpose, ceramics is the most promissing candidate material in strength for application to high-temperature heat exchangers. This report deals with a servey of characteristics of several high-temperature metallic materials and ceramics as temperature-resistant materials; including a servey of the state-of-the-art of ceramic heat exchanger technologies developed outside of Japan, and a study of their application to the intermediate heat exchanger of VHTR (a very-high-temperature gas-cooled reactor). (author)

  3. Heat exchanger using graphite foam

    Science.gov (United States)

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

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

  4. Designing heat exchangers for process heat reactors

    International Nuclear Information System (INIS)

    Quade, R.N.

    1980-01-01

    A brief account is given of the IAEA specialist meeting on process heat applications technology held in Julich, November 1979. The main emphasis was on high temperature heat exchange. Papers were presented covering design requirements, design construction and prefabrication testing, and selected problems. Primary discussion centered around mechanical design, materials requirements, and structural analysis methods and limits. It appears that high temperature heat exchanges design to nuclear standards, is under extensive development but will require a lengthy concerted effort before becoming a commercial reality. (author)

  5. Investigation and application of reduced-order methods for flows study in heat exchanger tube bundles

    International Nuclear Information System (INIS)

    Pomarede, M.

    2012-01-01

    The objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vibratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code-Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is applied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case. Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displacements of a confined moving tube in a bundle are shown to be faithfully reconstructed.Finally, the use of model reduction is extended to parametric studies. First, we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The results obtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann manifolds and allowing the construction of a POD basis from other pre-calculated basis, is applied to basic cases. (author)

  6. Study of heat transfer and pressure drop characteristics of air heat exchanger using PCM for free cooling applications

    Directory of Open Access Journals (Sweden)

    Kalaiselvam Sivakumar

    2016-01-01

    Full Text Available Free cooling is the process of storing the cool energy available in the night ambient air and using it during the day. The heat exchanger used in this work is a modular type which is similar to the shell and tube heat exchanger. The shell side is filled with Phase Change Materials (PCM and air flow is through the tubes in the module. The modules of the heat exchanger are arranged one over other with air spacers in between each module. The air space provided in between the module in-creases the retention time of the air for better heat transfer. Transient Computational Fluid Dynamics modeling is carried out for single air passage in a modular heat exchanger. It shows that the PCM phase transition time in the module in which different shape of fins is adopted. The module with rectangular fins has 17.2 % reduction in solidification compared with the plain module. Then steady state numerical analysis is accomplished to the whole module having the fin of high heat transfer, so that pressure drop, flow and thermal characteristics across the module and the air spacers are deter-mined for various air inlet velocities of 0.4 to 1.6 m/s. To validate the computational results, experiments are carried out and the agreement was found to be good.

  7. Microplate Heat Exchanger, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a microplate heat exchanger for cryogenic cooling systems used for continuous flow distributed cooling systems, large focal plane arrays, multiple cooling...

  8. Numerical Study of the Inertia Effect on Flow Distribution in Micro-gap Plate Heat Exchanger

    International Nuclear Information System (INIS)

    Park, Jang Min; Yoon, Seok Ho; Lee, Kong Hoon; Song Chan Ho

    2014-01-01

    This paper presents numerical study on flow and heat transfer characteristics in micro-gap plate heat exchanger. In particular, we investigate the effect of flow inertia on the flow distribution from single main channel to multiple parallel micro-gaps. The flow regime of the main channel is varied from laminar regime (Reynolds number of 100) to turbulent regime (Reynolds number of 10000) by changing the flow rate, and non-uniformity of the flow distribution and temperature field is evaluated quantitatively based on the standard deviation. The flow distribution is found to be significantly affected by not only the header design but also the flow rate of the main channel. It is also observed that the non-uniformity of the temperature field has its maximum at the intermediate flow regime

  9. Heat pipe heat exchangers in heat recovery systems

    Energy Technology Data Exchange (ETDEWEB)

    Stulc, P; Vasiliev, L L; Kiseljev, V G; Matvejev, Ju N

    1985-01-01

    The results of combined research and development activities of the National Research Institute for Machine Design, Prague, C.S.S.R. and the Institute for Heat and Mass Transfer, Minsk, U.S.S.R. concerning intensification heat pipes used in heat pipe heat exchangers are presented. This sort of research has been occasioned by increased interest in heat power economy trying to utilise waste heat produced by various technological processes. The developed heat pipes are deployed in construction of air-air, gas-air or gas-gas heat recovery exchangers in the field of air-engineering and air-conditioning. (author).

  10. Tube in shell heat exchangers

    International Nuclear Information System (INIS)

    Hayden, O.; Willby, C.R.; Sheward, G.E.; Ormrod, D.T.; Firth, G.F.

    1980-01-01

    An improved tube-in-shell heat exchanger to be used between liquid metal and water is described for use in the liquid metal coolant system of fast breeder reactors. It is stated that this design is less prone to failures which could result in sodium water reactions than previous exchangers. (UK)

  11. Heat pipes and heat pipe exchangers for heat recovery systems

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, L L; Grakovich, L P; Kiselev, V G; Kurustalev, D K; Matveev, Yu

    1984-01-01

    Heat pipes and heat pipe exchangers are of great importance in power engineering as a means of recovering waste heat of industrial enterprises, solar energy, geothermal waters and deep soil. Heat pipes are highly effective heat transfer units for transferring thermal energy over large distance (tens of meters) with low temperature drops. Their heat transfer characteristics and reliable working for more than 10-15 yr permit the design of new systems with higher heat engineering parameters.

  12. Heat Transfer in Metal Foam Heat Exchangers at High Temperature

    Science.gov (United States)

    Hafeez, Pakeeza

    Heat transfer though open-cell metal foam is experimentally studied for heat exchanger and heat shield applications at high temperatures (˜750°C). Nickel foam sheets with pore densities of 10 and 40 pores per linear inch (PPI), have been used to make the heat exchangers and heat shields by using thermal spray coating to deposit an Inconel skin on a foam core. Heat transfer measurements were performed on a test rig capable of generating hot gas up to 1000°C. The heat exchangers were tested by exposing their outer surface to combustion gases at a temperature of 550°C and 750°C while being cooled by air flowing through them at room temperature at velocities up to 5 m/s. The temperature rise of the air, the surface temperature of the heat exchangers and the air temperature inside the heat exchanger were measured. The volumetric heat transfer coefficient and Nusselt number were calculated for different velocities. The heat transfer performance of the 40PPI sample brazed with the foil is found to be the most efficient. Pressure drop measurements were also performed for 10 and 40PPI metal foam. Thermographic measurements were done on 40PPI foam heat exchangers using a high temperature infrared camera. A high power electric heater was used to produce hot air at 300°C that passed over the foam heat exchanger while the cooling air was blown through it. Heat shields were made by depositing porous skins on metal foam and it was observed that a small amount of coolant leaking through the pores notably reduces the heat transfer from the hot gases. An analytical model was developed based assuming local thermal non-equilibrium that accounts for the temperature difference between solid and fluid phase. The experimental results are found to be in good agreement with the predicted values of the model.

  13. Study of integral characteristics and efficiency of a heat exchanger of thermosyphon type with finned tubes

    Directory of Open Access Journals (Sweden)

    Iliev Iliya K.

    2016-01-01

    Full Text Available The experimental research aims at the analysis of the thermal performance of a gas-liquid heat exchanger in a pilot plant. Results of the conducted experiment with a finned tubes thermosyphon heat exchanger using natural gas are presented. The installation was mounted at the exit of a flue gas from an existing steam generator “PK-4” with total power of 2.88 MW in the boiler room of Vini, Sliven, Bulgaria. Different experiments were carried out at different loads of the steam generator in order to determine the efficiency of the heat exchanger. Based on these results the coefficient of heat transfer of flue gas to the finned tubes was determined, based on different modes of operation with crossed and straight pipe bundles. The effectiveness-number of transfer units method was used.

  14. Experimental Studies on Grooved Double Pipe Heat Exchanger with Different Groove Space

    Science.gov (United States)

    Sunu, P. W.; Arsawan, I. M.; Anakottapary, D. S.; Santosa, I. D. M. C.; Yasa, I. K. A.

    2018-01-01

    Experimental studies were performed on grooved double pipe heat exchanger (DPHE) with different groove space. The objective of this work is to determine optimal heat transfer parameter especially logarithmic mean temperature difference (LMTD). The document in this paper also provides the total heat observed by the cold fluid. The rectangular grooves were incised on outer surface of tube side with circumferential pattern and two different grooves space, namely 1 mm and 2 mm. The distance between grooves and the grooves high were kept constant, 8 mm and 0.3 mm respectively. The tube diameter is 20 mm and its made of aluminium. The shell is made of acrylic which has 28 mm in diameter. Water is used as the working fluid. Using counter flow scheme, the cold fluid flows in the annulus room of DPHE. The volume flowrate of hot fluid remains constant at 15 lpm. The volume flowrate of cold fluid were varied from 11 lpm to 15 lpm. Based on logarithmic mean temperature difference analysis, the LMTD of 1 mm grooves space was higher compared to that of 2 mm grooves space. The smaller grooves space has more advantage since the recirculating region are increased which essentially cause larger heat transfer enhancement.

  15. Heat transfer and friction characteristics of rotor-assembled strand heat exchanger studied by uniform design experiment

    Directory of Open Access Journals (Sweden)

    Yan Wei

    2015-10-01

    Full Text Available The uniform distribution and experimental design is employed to study the thermo-hydraulic characteristics of a heat exchanger, which consists of the rotor-assembled strands mounted in circular smooth tubes. The uniform distribution and experimental design parameters include multiple rotor parameters such as rotor diameters, rotor lead, and height of blade, with the aim of studying their influence on the PEC, that is, ( ( Nu z / Nu g / ( f g / f z 1 / 3 , which stands for the heat transfer and friction characteristics. The best matching schemes of rotor-assembled strand, which significantly improves PEC to 2.01, are given by the regression analysis of uniform distribution and experimental design table. The single-factor experiments are performed to compare a tube installed with different kinds of rotor-assembled strands with a smooth tube without any strands when the Reynolds number changes between 20,000 and 60,000. The experimental result is in good agreement with the result obtained by the regression analysis of uniform distribution and experimental design. It is shown that the rotor diameters play important role in the heat transfer, and the optimal PEC value is obtained under the case that the rotor diameter is 21 mm. The rotor lead also contributes to the improvement of heat transfer and its optimal value is 700 mm in this study. The Nusselt number, friction factor and PEC increase with the increase in blade height. It shows that the uniform distribution and experimental design is an efficient method to find out the optimal parameters.

  16. Preliminary Study of Printed Circuit Heat Exchanger (PCHE) for various power conversion systems for SMART

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jinsu; Baik, Seungjoon; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    The steam-Rankine cycle was the most widely used power conversion system for a nuclear power plant. The size of the heat exchanger is important for the modulation. Such a challenge was conducted by Kang et al. They change the steam generator type for the SMART from helical type heat exchanger to Printed Circuit Heat Exchanger (PCHE). Recently, there has been a growing interest in the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle as the most promising power conversion system. The reason is high efficiency with simple layout and compact power plant due to small turbomachinery and compact heat exchanger technology. That is why the SCO{sub 2} Brayton cycle can enhance the existing advantages of Small Modular Reactor (SMR) like SMART, such as reduction in size, capital cost, and construction period. Thermal hydraulic and geometric parameters of a PCHE for the S-CO{sub 2} power cycle coupled to SMART. The results show that the water - CO{sub 2} printed circuit heat exchanger size is smaller than printed circuit steam generator for the superheated steam Rankine cycle. This results show the potential benefit of using the S-CO-2 Brayton power cycle to a water-cooled small modular reactor.

  17. Condensation heat transfer in plate heat exchangers

    International Nuclear Information System (INIS)

    Panchal, C.B.

    1985-01-01

    An Alfa-Laval plate heat exchanger, previously tested as an evaporator, was retested as a condenser. Two series of tests with different chevron-angle plates were carried out using ammonia as a working fluid. The overall heat-transfer coefficient and pressure drop were measured, and the effects of operating parameters were determined. The experimental data were compared with theoretical predictions. In the analysis, a gravity-controlled condensation process was modeled theoretically, and the overall performance was calculated. The analysis shows that the overall heat-transfer coefficient can be predicted with an average uncertainty of about 10%. It is, however, important to consider the interfacial shear stress, because the effective friction factor is high for flow in plate heat exchangers

  18. Performance study of desiccant coated heat exchanger air conditioning system in winter

    International Nuclear Information System (INIS)

    Ge, T.S.; Dai, Y.J.; Wang, R.Z.

    2016-01-01

    Highlights: • Performance of desiccant coated heat exchanger AC system is predicted. • Effects of main operation parameters and climatic conditions are discussed. • Regeneration temperature of 30 °C is recommended under simulation condition. • Higher ambient humidity ratio results in increased humidity ratio of supply air. • Temperature of ambient air has neglectable effect on supply air. - Abstract: Conventional air source heat pump system faces several challenges when adopted in winter season. Solid desiccant air conditioning system can provide humidification and heating power simultaneously and can be driven by low grade thermal energy; it provides a good alternative for air source heat pump systems. However, conventional solid desiccant air conditioning system adopts desiccant wheel with high cost as core component, which hinders the development of such system. Recently, desiccant coated heat exchanger (DCHE) with low initial cost and high efficiency was developed and this paper aims to investigate performance of DCHE air conditioning system adopted in Shanghai winter season. Performance of the system is predicted by a developed mathematical model where supply air states, mass of humidification and coefficient of performance (COP) are adopted as performance indices to evaluate the feasibility and energy utilization ratio of the system. Effects of regeneration water temperature on system performance are analyzed. It is found that under the simulation condition, relatively low regeneration temperature (such as 20 °C) cannot meet the designed standard and relatively high regeneration temperature (such as 40 °C) provides too much extra heating power, thus moderate regeneration temperature around 30 °C is recommended. Meanwhile, switch time is a crucial operation parameter for the system to obtain satisfied supply air, switch time from 40 s to 80 s and from 70 s to 240 s are recommended for transient and average supply air states, respectively. Both

  19. Experimental study on the thermal hydraulic performance of plate-fin heat exchangers for cryogenic applications

    Science.gov (United States)

    Jiang, Qingfeng; Zhuang, Ming; Zhang, Qiyong; Zhu, Zhigang; Geng, Maofei; Sheng, Linhai; Zhu, Ping

    2018-04-01

    Efficient and compact plate-fin heat exchangers are critical for large-scale helium liquefaction/refrigeration systems as they constitute major part in the cold box. This study experimentally explores the heat transfer and pressure drop behaviors of helium gas at low temperature in four types of plate-fin channels, namely offset-strip and perforated fins, with different geometrical parameters. A series of cryogenic experiments at approximately liquid nitrogen temperature are carried out to measure the Colburn j factors and Fanning friction f factors with a wide range of Reynolds number. Besides, to reveal the performance variations under different operating temperatures, comparative experiments respectively conducted at room temperature and liquid nitrogen temperature are implemented. The results show that in comparison with the performance data at room temperature, most of j factors are relatively smaller perhaps because the lower aluminum thermal conductivity and higher Prandtl Number at low temperature. Meanwhile, the f factors corresponding to cryogenic conditions exhibit slightly larger even though the core pressure drops show considerable reductions. In contrast to the calculated results from the frequently-used performance curves (Chen and Shen, 1993), the Root Mean Squared Errors of j and f values are correlated within 8.38% and 6.97% for one perforated fin core, 41.29% and 34.97% for three OSF cores, respectively. For OSFs, further comparisons with the previous empirical correlations from literatures are conducted to verify the accuracy of each correlation. Generally, most of the calculated results predict acceptably within the deviations of ±25% for the j factors, while the predicted results express relatively large deviations for the f factors. Therefore, it may be revealed that most of the existing correlations were not able to accurately predict the experimental data in consideration of the performance differences under realistic cryogenic operating

  20. A comparative study of different heat exchange systems in a thermoelectric refrigerator and their influence on the efficiency

    International Nuclear Information System (INIS)

    Astrain, D.; Aranguren, P.; Martínez, A.; Rodríguez, A.; Pérez, M.G.

    2016-01-01

    Highlights: • Total efficiency optimisation of a thermoelectric refrigerator. • Experimental study of three different types of heat exchangers for thermoelectrics. • Influence of the occupancy ratio in thermal resistance. • Important decrease in the electric consumption of a thermoelectric refrigerator. - Abstract: Thermoelectric refrigeration (TEC) exhibits several advantages compared to vapour-compression, since this technology presents accurate temperature control systems and higher levels of compactness, robustness and noiselessness. However, its low efficiency is acting as a deterrent for it to spread in the refrigeration market. One of the factors determining the efficiency of a thermoelectric refrigerator is the temperature difference between the hot and cold sides of the thermoelectric modules (TEMs). This is dependent on the thermal resistances of the heat exchangers used. This paper discusses the results of an experimental study of different types of heat exchangers for the thermoelectric module hot side: a water–air system comprising a cold plate, pump and fan coil; a finned heat sink with fan; a heat pipe with fan. Expressions of thermal resistance have been obtained for these three types as a function of the air and water mass flows and the number of TEMs per unit of surface area of heat exchanger (occupancy ratio, δ), as well as expressions of the power consumed by the fans and the pump. Finally, a computational study has been carried out on a thermoelectric refrigerator of 15 m"3 of interior volume, in order to obtain the influence of the heat exchanger studied, on the total consumption of the refrigerator and its efficiency. The results have demonstrated that relevant improvements can be made in TEC efficiency by the proper optimisation of the heat exchangers.

  1. Experimental study of heat and mass transfer in a buoyant countercurrent exchange flow

    Science.gov (United States)

    Conover, Timothy Allan

    Buoyant Countercurrent Exchange Flow occurs in a vertical vent through which two miscible fluids communicate, the higher-density fluid, residing above the lower-density fluid, separated by the vented partition. The buoyancy- driven zero net volumetric flow through the vent transports any passive scalars, such as heat and toxic fumes, between the two compartments as the fluids seek thermodynamic and gravitational equilibrium. The plume rising from the vent into the top compartment resembles a pool fire plume. In some circumstances both countercurrent flows and pool fires can ``puff'' periodically, with distinct frequencies. One experimental test section containing fresh water in the top compartment and brine (NaCl solution) in the bottom compartment provided a convenient, idealized flow for study. This brine flow decayed in time as the concentrations approached equilibrium. A second test section contained fresh water that was cooled by heat exchangers above and heated by electrical elements below and operated steadily, allowing more time for data acquisition. Brine transport was reduced to a buoyancy- scaled flow coefficient, Q*, and heat transfer was reduced to an analogous coefficient, H*. Results for vent diameter D = 5.08 cm were consistent between test sections and with the literature. Some results for D = 2.54 cm were inconsistent, suggesting viscosity and/or molecular diffusion of heat become important at smaller scales. Laser Doppler Velocimetry was used to measure velocity fields in both test sections, and in thermal flow a small thermocouple measured temperature simultaneously with velocity. Measurement fields were restricted to the plume base region, above the vent proper. In baseline periodic flow, instantaneous velocity and temperature were ensemble averaged, producing a movie of the average variation of each measure during a puffing flow cycle. The temperature movie revealed the previously unknown cold core of the puff during its early development. The

  2. Nuclear research reactor IEA-R1 heat exchanger inlet nozzle flow - a preliminary study

    International Nuclear Information System (INIS)

    Angelo, Gabriel; Andrade, Delvonei Alves de; Fainer, Gerson; Angelo, Edvaldo

    2009-01-01

    As a computational fluid mechanics training task, a preliminary model was developed. ANSYS-CFX R code was used in order to study the flow at the inlet nozzle of the heat exchanger of the primary circuit of the nuclear research reactor IEA-R1. The geometry of the inlet nozzle is basically compounded by a cylinder and two radial rings which are welded on the shell. When doing so there is an offset between the holes through the shell and the inlet nozzle. Since it is not standardized by TEMA, the inlet nozzle was chosen for a preliminary study of the flow. Results for the proposed model are presented and discussed. (author)

  3. Integration of Heat Exchangers with Thermoelectric Modules

    DEFF Research Database (Denmark)

    Rezaniakolaei, Alireza

    2017-01-01

    processes wherein the critical system components such as the TEG module and the heat exchangers are thermally coupled. The optimization techniques of the TEG systems coupled with the heat transfer through the system using a maximum efficiency-power map for waste heat recovery applications offer maximum...... thermally interdependent in the system designs. This chapter studies the effect of the heat exchangers design on system performance, and discusses the challenges through accurate analyses techniques while introducing proper cooling technologies. Proper design of a TEG system involves design optimization...

  4. Experimental and parametric studies of a louvered fin and flat tube compact heat exchanger using computational fluid dynamics

    Directory of Open Access Journals (Sweden)

    P. Karthik

    2015-12-01

    Full Text Available The present study aimed to perform the parametric analysis on thermo-hydraulic performance of a compact heat exchanger using computational fluid dynamics (CFD. The analysis has been carried out at different frontal air velocities by varying the geometrical parameters such as fin pitch, transverse tube pitch, longitudinal tube pitch, louver pitch and louver angle. The air side performance of the heat exchanger has been evaluated by calculating Colburn factor (j and Fanning friction factor (f. The comparison of CFD results with the experimental data exhibited a good agreement and the influence of various geometrical parameters for the selected range of values on the pressure drop, heat transfer coefficient and goodness factor was analyzed. The results obtained from the analysis will be very useful to optimize the louvered fin and flat tube compact heat exchanger for better thermo-hydraulic performance analysis without the need of time consuming and expensive experimentation.

  5. Development of heat exchangers for nuclear service

    International Nuclear Information System (INIS)

    Hodge, R.I.; Dalrymple, D.G.

    1976-01-01

    Unusual design constraints, due to tube vibration, are called for when tube-in-shell heat exchangers are incorporated into CANDU type reactor power plants. CRNL has programs studying tube excitation and response, flow conditions, and the fretting process in such exchangers, tube plugging techniques, and eddy current scanning systems for inside bores of full-length tubes. (E.C.B.)

  6. Studies needed to prevent the use of expansion bends in LMFBR intermediate heat exchangers

    International Nuclear Information System (INIS)

    Kayser, G.

    1975-01-01

    The LMFBR IHX built in France consist in a vertical tube bundle welded on 2 tube sheets. The secondary sodium flows down a central pipe to the lower collector then up through the tube bundle where it is heated. The solution of the problems raised by the presence of thermal stresses needed thorough studies and led to the following theoretical and experimental developments: 1. A computer code was written for structural analysis. The structure was divided in annular elements that could be studied by means of the elementary theory of shells and plates; and reduced elastic coefficients were given to the tube sheets to account for the presence of drilled holes. 2. An experimental study was undertaken to determine the reduced elastic coefficients of the tube sheets. 3. A computer code was written to study the primary sodium flow around the tube bundle, and experimental studies were made on a mockup, the fluid being water. 4. The results of the previous code were used to determine, by means of a code for thermal analysis, the temperature field in the bundle both in steady state and transient regimes. Up to now, many transients were performed and the Phenix heat exchangers have been operating quite satisfactorily; this seems to prove the design assumptions were correct. (Auth.)

  7. Mechanical calculation of heat exchangers

    International Nuclear Information System (INIS)

    Osweiller, Francis.

    1977-01-01

    Many heat exchangers are still being dimensioned at the present time by means of the American TEMA code (Tubular Exchanger Manufacturers Association). The basic formula of this code often gives rise to significant tubular plate thicknesses which, apart from the cost of materials, involve significant machining. Some constructors have brought into use calculation methods that are more analytic so as to take into better consideration the mechanical phenomena which come into play in a heat exchanger. After a brief analysis of these methods it is shown, how the original TEMA formulations have changed to reach the present version and how this code has incorporated Gardner's results for treating exchangers with two fixed heads. A formal and numerical comparison is then made of the analytical and TEMA methods by attempting to highlight a code based on these methods or a computer calculation programme in relation to the TEMA code [fr

  8. Thermodynamic analysis on theoretical models of cycle combined heat exchange process: The reversible heat exchange process

    International Nuclear Information System (INIS)

    Zhang, Chenghu; Li, Yaping

    2017-01-01

    Concept of reversible heat exchange process as the theoretical model of the cycle combined heat exchanger could be useful to determine thermodynamics characteristics and the limitation values in the isolated heat exchange system. In this study, the classification of the reversible heat exchange processes is presented, and with the numerical method, medium temperature variation tendency and the useful work production and usage in the whole process are investigated by the construction and solution of the mathematical descriptions. Various values of medium inlet temperatures and heat capacity ratio are considered to analyze the effects of process parameters on the outlet temperature lift/drop. The maximum process work transferred from the Carnot cycle region to the reverse cycle region is also researched. Moreover, influence of the separating point between different sub-processes on temperature variation profile and the process work production are analyzed. In addition, the heat-exchange-enhancement-factor is defined to study the enhancement effect of the application of the idealized process in the isolated heat exchange system, and the variation degree of this factor with process parameters change is obtained. The research results of this paper can be a theoretical guidance to construct the cycle combined heat exchange process in the practical system. - Highlights: • A theoretical model of Cycle combined heat exchange process is proposed. • The classification of reversible heat exchange process are presented. • Effects of Inlet temperatures and heat capacity ratio on process are analyzed. • Process work transmission through the whole process is studied. • Heat-exchange-enhancement-factor can be a criteria to express the application effect of the idealized process.

  9. Study of two-phase flow redistribution between two passes of a heat exchanger

    International Nuclear Information System (INIS)

    Mendes de Moura, L.F.

    1989-04-01

    The object of the present thesis deals with the study of two-phase flow redistribution between two passes of a heat exchanger. Mass flow rate measurements of each component performed at each channel outlet of the second pass allowed us to determine the influence of mass flow, gas quality, flow direction (upward or downward) and common header geometry upon flow redistribution. Local void fraction inside common header was measured with an optical probe. A two-dimensional two-phase flow computational code was developed from a two-fluid model. Modelling of interfacial momentum transfer was used in order to take into account twp-phase flow patterns in common headers. Numerical simulation results show qualitative agreement with experimental results. Present theoretical model limitations are analysed and future improvements are proposed [fr

  10. A simulation-based analysis of variable flow pumping in ground source heat pump systems with different types of borehole heat exchangers: A case study

    International Nuclear Information System (INIS)

    Zarrella, Angelo; Emmi, Giuseppe; De Carli, Michele

    2017-01-01

    Highlights: • The work focuses on the variable flow in ground source heat pump systems. • The constant and variable speed circulation pumps in the ground loop are compared. • The constant temperature difference control across the heat pump is studied. • The variable flow affects the energy performance of the heat pump. • The constant temperature difference control offers an attractive energy saving. - Abstract: A simulation model of ground source heat pump systems has been used to investigate to what extent a variable flow of the heat-carrier fluid of the ground loop affects the energy efficiency of the entire system. The model contemporaneously considers the borehole heat exchangers, the heat pump, the building load, and the control strategies for the circulation pumps of the ground loop. A constant speed of the circulation pumps of the ground loop was compared with a variable flow controlled by means of a constant temperature difference across the heat pump on the ground side considering the load profile of an office building located in North Italy. The analysis was carried out for a single U-tube, double U-tube and coaxial pipe heat exchangers. The control strategies adopted to manage the flow rate of the heat-carrier fluid of the ground loop affect both the heat exchange rate of the borehole field and the heat pump’s long-term energy efficiency. The simulations show considerable differences in the system’s seasonal energy efficiency. The constant speed of the circulation pumps leads to the best results as far as the heat pump’s energy performance was concerned, but this advantage was lost because of the greater amount of electrical energy used by the circulation pumps; this, of course, affects the energy efficiency of the entire system. The optimal solution appears then to be a constant temperature difference in the heat-carrier fluid across the heat pump.

  11. Compact heat exchanger for power plants

    International Nuclear Information System (INIS)

    Kinnunen, L.

    2001-01-01

    Vahterus Oy, located at Kalanti, has manufactured heat exchangers since the beginning of 1990s. About 90% of the equipment produced are exported. In the PSHE (Plate and Shell) solution of the Vahterus heat exchanger the heat is transferred by round plated welded to form a compact package, which is assembled into a cylindrical steel casing. The heat exchanger contains no gaskets or soldered joints, which eliminates the leak risks. Traditional heat exchanges are usually operated at higher temperatures and pressures, but the heat transfer capacities of them are lower. Plate heat exchangers, on the other hand, are efficient, but the application range of them is narrow. Additionally, the rubber gasket of the heat exchange plates, sealing the joints of the heat exchanging plates, does not stand high pressures or temperatures, or corroding fluids. The new welded plate heat exchanger combine the pressure and temperature resistance of tube heat exchangers and the high heat exchange capacity of plate heat exchangers. The new corrosion resisting heat exchanger can be applied for especially hard conditions. The operating temperature range of the PSHE heat exchanger is - 200 - 900 deg C. The pressure resistance is as high as 100 bar. The space requirement of PSHE is only one tenth of the space requirement of traditional tube heat exchangers. Adjusting the number of heat exchanging plates can change the capacity of the heat exchanger. Power range of the heat exchanger can be as high as 80 MW. Due to the corrosion preventive construction and the small dimension the PSHE heat exchanger can be applied for refrigerators using ammonia as refrigerant. These kinds of new Vahterus heat exchangers are in use in 60 countries in more than 2000 refrigerators

  12. Corrosion protected reversing heat exchanger

    International Nuclear Information System (INIS)

    Zawierucha, R.

    1984-01-01

    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

  13. High Flux Heat Exchanger

    Science.gov (United States)

    1993-01-01

    maximum jet velocity (6.36 m/s), and maximum number of jets (nine). Wadsworth and Mudawar [49] describe the use of a single slotted nozzle to provide...H00503 (ASME), pp. 121-128, 1989. 40 49. D. C. Wadsworth and I. Mudawar , "Cooling of a Multichip Electronic Module by Means of Confined Two-Dimensional...Jets of Dielectric Liquid," HTD-Vol. 111, Heat Transfer in Electrglif, Book No. H00503 (ASME), pp. 79-87, 1989. 50. D.C. Wadsworth and I. Mudawar

  14. Ceramic heat exchanger

    Science.gov (United States)

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

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

  15. Heat Exchanger/Humidifier Trade Study and Conceptual Design for the Constellation Space Suit Portable Life Support System Ventilation Subsystem

    Science.gov (United States)

    Paul, Heather L.; Sompayrac, Robert; Conger, Bruce; Chamberlain, Mateo

    2009-01-01

    As development of the Constellation Space Suit Element progresses, designing the most effective and efficient life support systems is critical. The baseline schematic analysis for the Portable Life Support System (PLSS) indicates that the ventilation loop will need some method of heat exchange and humidification prior to entering the helmet. A trade study was initiated to identify the challenges associated with conditioning the spacesuit breathing gas stream for temperature and water vapor control, to survey technological literature and resources on heat exchanger and humidifiers to provide solutions to the problems of conditioning the spacesuit breathing gas stream, and to propose potential candidate technologies to perform the heat exchanger and humidifier functions. This paper summarizes the results of this trade study and also describes the conceptual designs that NASA developed to address these issues.

  16. Studi Eksperimen Pengaruh Variasi Kecepatan Udara Terhadap Performa Heat Exchanger Jenis Compact Heat Exchanger (Radiator Dengan Susunan Tube Inline Sebagai Pemanas Pada Sistem Pengeringan Batubara

    Directory of Open Access Journals (Sweden)

    Irvan Paramananda

    2014-03-01

    Full Text Available Pengeringan yang dilakukan pada batu bara dengan memanfaatkan udara panas menggunakan konsep heat exchanger. Salah satu heat exchanger yang sering digunakan adalah heat exchanger dengan tipe single row-fin tube yaitu radiator. Radiator ini akan dimanfaatkan sebagai penghasil udara panas dari air panas yang mengalir dan dihembuskan oleh kipas radiator. Penelitian ini difokuskan pada effectiveness dari komponen radiator fungsi dari kecepatan udara mulai dari kecepatan 1 m/s, 2 m/s, 3 m/s, 4 m/s dan 5 m/s dan fungsi jumlah radiator yang digunakan. Prinsip dari radiator yang digunakan adalah mengalirkan fluida panas berupa air ke dalam tube-tube radiator kemudian didinginkan oleh udara yang dihembuskan oleh fan yang melewati fin sehingga air yang keluar dari tube menjadi dingin dan udara yang melewati fin menjadi panas. Hasil yang didapatkan dari eksperimen ini diantaranya kecepatan udara yang optimal terhadap proses pengeringan batu bara yang dipakai pada alat pengering batu bara adalah sebesar 5 m/s dengan menggunakan 2 radiator. qhot untuk penggunaan 2 radiator dengan kecepatan udara sebesar 5 m/s adalah 30121.17 Watt. Effectiveness pada penggunaan 2 radiator dengan kecepatan udara sebesar 5 m/s adalah 0.65. Efisiensi fin yang terjadi pada kecepatan udara 5 m/s dengan menggunakan 2 radiator sebesar 0.93

  17. Heat exchanger with oscillating flow

    Science.gov (United States)

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

    1993-01-01

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

  18. Influence on Heat Transfer Coefficient of Heat Exchanger by Velocity and Heat Transfer Temperature Difference

    Directory of Open Access Journals (Sweden)

    WANG Fang

    2017-04-01

    Full Text Available Aimed to insufficient heat transfer of heat exchanger, research the influence on the heat transfer coefficient impacted by velocity and heat transfer temperature difference of tube heat exchanger. According to the different heat transfer temperature difference and gas velocity,the experimental data were divided into group. Using the control variable method,the above two factors were analyzed separately. K一△T and k一:fitting curve were clone to obtain empirical function. The entire heat exchanger is as the study object,using numerical simulation methods,porous media,k一£model,second order upwind mode,and pressure一velocity coupling with SIMPLE algorithm,the entire heat exchanger temperature field and the heat transfer coefficient distribution were given. Finally the trend of the heat transfer coefficient effected by the above two factors was gotten.

  19. Compact Ceramic Microchannel Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  20. Performance test of miniature heat exchangers with microchannels

    International Nuclear Information System (INIS)

    Hong, Yong Ju; Koh, Deuk Yong

    2005-01-01

    Etched microchannel heat exchanger, a subfield within MEMS, has high heat flux capability. This capability makes microchannels well-suited for a wide variety of application of cooling and chemical reaction. In this study, counter flow type miniature heat exchangers, which have flat metal plates with chemically etched microchannels, were manufactured by brazing method. Four type of the heat exchangers, which have straight microchannels, wavy shape microchannels, pin-fin channels and serpentine shape microchannels, were investigated to compare their thermal and hydraulic performance. Gas to gas heat exchange experiments were performed to measure the pressure drop and effectiveness of the heat exchangers at given gas flow rates and temperature difference

  1. Preliminary thermal sizing of intermediate heat exchanger for NHDD system

    International Nuclear Information System (INIS)

    Kim, Chan Soo; Hong, Sung Deok; Kim, Yong Wan; Chang, Jongh Wa

    2009-01-01

    Nuclear Hydrogen Development and Demonstration (NHDD) system is a Very High Temperature gascooled Reactor (VHTR) coupled with hydrogen production systems. Intermediate heat exchanger transfers heat from the nuclear reactor to the hydrogen production system. This study presented the sensitivity analysis on a preliminary thermal sizing of the intermediate heat exchanger. Printed Circuit Heat Exchanger (PCHE) was selected for the thermal sizing because the printed circuit heat exchanger has the largest compactness among the heat exchanger types. The analysis was performed to estimate the effect of key parameters including the operating condition of the intermediate system, the geometrical factors of the PCHE, and the working fluid of the intermediate system.

  2. Heat pipe heat exchanger for heat recovery in air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Baky, Mostafa A.; Mohamed, Mousa M. [Mechanical Power Engineering Department, Faculty of Engineering, Minufiya University, Shebin El-Kom (Egypt)

    2007-03-15

    The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5 and 2.3 have been adapted to validate the heat transfer and the temperature change of fresh air. Fresh air inlet temperature of 32-40{sup o}C has been controlled, while the inlet return air temperature is kept constant at about 26{sup o}C. The results showed that the temperature changes of fresh and return air are increased with the increase of inlet temperature of fresh air. The effectiveness and heat transfer for both evaporator and condenser sections are also increased to about 48%, when the inlet fresh air temperature is increased to 40{sup o}C. The effect of mass flow rate ratio on effectiveness is positive for evaporator side and negative for condenser side. The enthalpy ratio between the heat recovery and conventional air mixing is increased to about 85% with increasing fresh air inlet temperature. The optimum effectiveness of heat pipe heat exchanger is estimated and compared with the present experimental data. The results showed that the effectiveness is close to the optimum effectiveness at fresh air inlet temperature near the fluid operating temperature of heat pipes. (author)

  3. Experimental Study of the Variation Dynamic’s for Air Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Maryia Marozava

    2017-07-01

    Full Text Available The development of management systems is assigned one of the leading roles. When solving the problems of regulating the technological parameters, various problems arise. One of such problems is the adjustment of control loops. For some control objects, one-time adjustment of the controller parameters can be made, and then it is periodically refined as necessary. In other objects, the changes occur very quickly, but in a certain range. In the latter case, you should first estimate the range of changes. Then find universal robust settings that will ensure the stability and quality of the stabilization system. Some of such objects are air heat exchangers. The article presents the results of the determination of the heat exchanger dynamics. The limits of the variation of the parameters of the dynamic models are determined. There is a significant nonlinearity in the transfer function of the control channel.

  4. Numerical and Experimental Study of an Ambient Air Vaporizer Coupled with a Compact Heat Exchanger

    Science.gov (United States)

    Kimura, Randon

    The University of Washington was tasked with designing a "21st century engine" that will make use of the thermal energy available in cryogenic gasses due to their coldness. There are currently large quantities of cryogenic gases stored throughout the U.S. at industrial facilities whereupon the regasification process, the potential for the fluid to do work is wasted. The engine proposed by the University of Washington will try to capture some of that wasted energy. One technical challenge that must be overcome during the regasification process is providing frost free operation. This thesis presents the numerical analysis and experimental testing of a passive heat exchange system that uses ambient vaporizers coupled with compact heat exchangers to provide frost free operation while minimizing pressure drop.

  5. Thermal hydraulic simulation of moderator heat exchanger

    International Nuclear Information System (INIS)

    Anil Lal, S.; Rajakumar, A.; Vaidyanathan, G.; Srinivasan, R.; Chetal, S.C.

    1993-01-01

    Pressurized heavy water reactors form the majority in the first stage of India's nuclear power programme. Heavy water is both moderator and primary coolant. The heat generated in the moderator due to neutron moderation and capture has to be removed in moderator heat exchangers. It has been desired to improve the performance characteristics of moderator heat exchangers, whereby moderator would enter the calandria vessel at a low temperature and would enable higher power of operation for the same limiting temperature of moderator in the calandria. Results of studies carried out using a three dimensional computer code for various operating options are given. Using these velocities the heat exchangers have been analysed for flow induced vibrations. 7 refs., 6 figs., 6 tabs

  6. Intermediate heat exchanger for HTR process heat application

    International Nuclear Information System (INIS)

    Crambes, M.

    1980-01-01

    In the French study on the nuclear gasification of coal, the following options were recommended: Coal hydrogenation, the hydrogen being derived from CH 4 reforming under the effects of HTR heat; the use of an intermediate helium circuit between the nuclear plant and the reforming plant. The purpose of the present paper is to describe the heat exchanger designed to transfer heat from the primary to the intermediate circuit

  7. An experimental and numerical study of a jetfire stop material and a new helical flow heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Austegard, Anders

    1997-12-31

    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 jetfire stop. 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. There is a separate appendix volume. 62 refs., 152 figs., 22 tabs.

  8. Helically coiled tube heat exchanger

    International Nuclear Information System (INIS)

    Harris, A.M.

    1981-01-01

    In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle

  9. Radiative heat exchange between surfaces

    International Nuclear Information System (INIS)

    Yener, Y.; Yuncu, H.

    1987-01-01

    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

  10. Cryogenic Heat Exchanger with Turbulent Flows

    Science.gov (United States)

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

    2012-01-01

    An evaporator-type cryogenic heat exchanger is designed and built for introducing fluid-solid heat exchange phenomena to undergraduates in a practical and efficient way. The heat exchanger functions at liquid nitrogen temperature and enables cooling of N[subscript 2] and He gases from room temperatures. We present first the experimental results of…

  11. Heat exchanger. [Nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Molina, C; Brisseaux, A

    1976-01-19

    This invention concerns a heat exchanger between a fluid flowing through a tube and a gas. Such an exchanger can be used, inter alia, for removing calories that cannot be used for generating electricity in a thermal or nuclear power station. This exchanger can withstand any pressure surges in the system and even the use of a high vapour pressure coolant such as ammonia, since the fluid flows in a round tube with low pressure drops (both with respect to the fluid to be cooled and the cooling air). It is rigid enough to stand up to being moved and handled as well as to gusts of wind. It is formed of units that can be handled without difficulty and that are easily dismantable and interchangeable, even in service, and it is easily maintained. The exchange area is high for a minimum frontal area and this enables the size of the supporting frame to be reduced and makes it easy to hide it behind a screen of trees should this prove necessary. Finally, it is composed of a small number of standard units thus reducing the industrial production cost. These units are rectangular plates, each one being a flat tubular coil fitted between two flat parallel sheet metal plates having on their outer sides flat top raised bosses. These units are assembled together by the tops of the bosses so as to form an exchanger bank, each bank comprising two collectors to which the bank coils are tightly connected.

  12. Studying the performance of a dehumidifier with adsorbent coated heat exchangers for tropical climate operations

    KAUST Repository

    Oh, Seung Jin; Ng, Kim Choon; Thu, Kyaw; Kum Ja, Marip; Islam, Md Raisul; Chun, Wongee; Chua, Kian Jon Ernest

    2016-01-01

    A solid desiccant dehumidifier equipped with adsorbent coated heat exchangers has been developed and investigated experimentally. The main component of the solid desiccant dehumidifier included two heat exchangers that were coated with silica gel regular density (RD) type powder in order to increase water adsorption uptake by improving its heat transfer. A series of experiment were conducted to evaluate two key performance indices, namely, moisture removal capacity and thermal performance, under various operating conditions. Results revealed that the reduction of dehumidification process time by 50% can lead to significant improvement of the mean humidity ratio at outlet up to 9.3 g/kg. The maximum moisture removal was found to decrease from 14.8 to 13.2 g/kg with higher airflow rates arising from the reduced residence time of the process air. It was further observed that the water moisture removal was highly affected by inlet humidity ratio. In addition, marked improvement in thermal performance can be achieved by a lowered hot water regeneration temperature. Copyright © 2016 ASHRAE

  13. Studying the performance of a dehumidifier with adsorbent coated heat exchangers for tropical climate operations

    KAUST Repository

    Oh, Seung Jin

    2016-09-26

    A solid desiccant dehumidifier equipped with adsorbent coated heat exchangers has been developed and investigated experimentally. The main component of the solid desiccant dehumidifier included two heat exchangers that were coated with silica gel regular density (RD) type powder in order to increase water adsorption uptake by improving its heat transfer. A series of experiment were conducted to evaluate two key performance indices, namely, moisture removal capacity and thermal performance, under various operating conditions. Results revealed that the reduction of dehumidification process time by 50% can lead to significant improvement of the mean humidity ratio at outlet up to 9.3 g/kg. The maximum moisture removal was found to decrease from 14.8 to 13.2 g/kg with higher airflow rates arising from the reduced residence time of the process air. It was further observed that the water moisture removal was highly affected by inlet humidity ratio. In addition, marked improvement in thermal performance can be achieved by a lowered hot water regeneration temperature. Copyright © 2016 ASHRAE

  14. Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes

    Science.gov (United States)

    Talmud, Fred M.; Garcia-Mallol, Juan-Antonio

    1980-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided and includes a steam drum disposed adjacent the fluidized bed and a series of tubes connected at one end to the steam drum. A portion of the tubes are connected to a water drum and in the path of the air and the gaseous products of combustion exiting from the bed. Another portion of the tubes pass through the bed and extend at an angle to the upper surface of the bed.

  15. Numerical study on pressure drop and heat transfer for designing sodium-to-air heat exchanger tube banks on advanced sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    Kang, Hie-Chan; Eoh, Jae-Hyuk; Cha, Jae-Eun; Kim, Seong-O.

    2013-01-01

    Highlights: ► Numerical simulation for the heat flow characteristic of the sodium-to-air heat exchanger (AHX) and tube banks. ► Parallelogram tube banks showed almost similar thermal and hydraulic characteristics to the rectangular tube banks. ► Pressure drop and heat transfer of the staggered and rectangular tube banks compared with Zhukauskas’ correlation. ► AHX was modeled as porous media and suggested design guide to enhance the performance. - Abstract: A numerical study is performed to investigate the thermal and hydraulic characteristics and build up design model of the AHX (sodium-to-air heat exchanger) unit of a sodium-cooled fast reactor. Helical-coiled tube banks in the AHX are modeled as porous media and simulated heat and momentum transfer by a commercial program. Two-dimensional flow characteristic appears differently at the inlet region of the AHX annulus, and the required length of the inlet region is shorter for an inlet having a 45 degree chamber or a round shape than for one with a perpendicular corner. Pressure drop and heat transfer coefficient for rectangular, parallelogram and staggered tube banks as the main components of the AHX are evaluated and discussed. Pressure drop and heat transfer shows similar trends and underestimated values, respectively, when compared with Zhukauskas empirical correlations. The parallelogram tube bank shows similar results to the rectangular arrangement.

  16. Heat transfer enhancement for fin-tube heat exchanger using vortex generators

    International Nuclear Information System (INIS)

    Yoo, Seong Yeon; Park, Dong Seong; Chung, Min Ho; Lee, Sang Yun

    2002-01-01

    Vortex generators are fabricated on the fin surface of a fin-tube heat exchanger to augment the convective heat transfer. In addition to horseshoe vortices formed naturally around the tube of the fin-tube heat exchanger, longitudinal vortices are artificially created on the fin surface by vortex generators. The purpose of this study is to investigate the local heat transfer phenomena in the fin-tube heat exchangers with and without vortex generators, and to evaluate the effect of vortices on the heat transfer enhancement. Naphthalene sublimation technique is employed to measure local mass transfer coefficients, then analogy equation between heat and mass transfer is used to calculate heat transfer coefficients. Experiments are performed for the model of fin-circular tube heat exchangers with and without vortex generators, and of fin-flat tube heat exchangers with and without vortex generators. Average heat transfer coefficients of fin-flat tube heat exchanger without vortex generator are much lower than those of fin-circular tube heat exchanger. On the other hand, fin-flat tube heat exchanger with vortex generators has much higher heat transfer value than conventional fin-circular tube heat exchanger. At the same time, pressure losses for four types of heat exchanger is measured and compared

  17. Open heat exchanger for improved heat efficiency in geothermal spas

    Energy Technology Data Exchange (ETDEWEB)

    Nasrabady, S.J.; Palsson, H.; Saevarsdottir, G.A.

    2008-09-15

    Hot spas and Jacuzzis are popular in Iceland due to the abundance of reasonably prized geothermal heat available. However the water from the district heating system is too warm to be admitted directly into the spa. For safety reasons the water is mixed with cold water, in order to reduce temperature from about 80 deg C down to 45 deg C, which leads to wasting a large quantity of heat. Therefore a design is suggested here that enables the feeding of geothermal water directly into the spa, omitting the step of mixing it with cold water. The idea is to employ an open heat exchanger that transfers heat from the geothermal water to the bulk water in the spa, before letting it mix with the spa water. A case study was done for one particular spa. Heat load was calculated and measured when the spa was in use, and when it was unused. A design is suggested employing a circular double-plate which is to be placed at the bottom of the spa. This unit will function as an open heat exchanger feeding district heating water into the spa. Free convection takes place at the upper side of the upper plate and forced convection below the upper plate. Heat transfer coefficient for both was calculated. Using results from calculations, temperature distribution at critical parts of spa and plate was modeled. Results are reasonable and promising for a good design that may considerably reduce the energy expenses for a continuously heated geothermal spa

  18. Heat exchanger for solar water heaters

    Science.gov (United States)

    Cash, M.; Krupnick, A. C.

    1977-01-01

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

  19. Intermediate heat exchanger design study of 25 MW straight-tube hexagonal modular type

    International Nuclear Information System (INIS)

    Okamoto, Masaharu; Tanaka, Toshiyuki

    1983-09-01

    The helium-to-helium Intermediate Heat Exchanger(IHX), straight-tube hexagonal modular type was designed at General Atomic Company(GA), which heat duty is 421 MW. For this type IHX, at the selection of basic design, emphasis is placed on cost reduction and size reduction. Then small diameter tube size(11.1 mm), with wall thickness of 1.2 mm is applied to this IHX, necessary for the compact surface geometry. The other side, the helical-tube type IHX was designed at JAERI, which heat duty is 25 MW. This paper discusses the referance design of 25 MW scale IHX, with GA type application. The basic feature of this type IHX is as follows. (1) Thermal stress is reduced, as a result of using small diameter and thin wall thickness tube. (2) The possible improvements can make for higher heat flux, because of short length tube, compare with helical or U-tube type. (3) The simple tube support can use compare with helical or U-tube type. The conclusion reached is that GA type IHX is about one forth compactness and one forth weight compare with helical tube IHX. (author)

  20. Compact heat exchanger for fluids

    International Nuclear Information System (INIS)

    Marchal, P.A.H.

    1975-01-01

    The invention concerns a welded heat exchanger with two or more fluids which can be used counter current. The principle of the apparatus allows the use of rolled welded concentric metal strips as well as spiral rolled metal strips. The ring sheets are kept apart either by their rigidity due to the cylindrical shape or by deformations in the sheets themselves or yet again by spacers or chequered and/or perforated sheets forming for instance corrugated spacers, the end sheet being thick enough to take the pressure strain [fr

  1. Auxiliary Heat Exchanger Flow Distribution Test

    International Nuclear Information System (INIS)

    Kaufman, J.S.; Bressler, M.M.

    1983-01-01

    The Auxiliary Heat Exchanger Flow Distribution Test was the first part of a test program to develop a water-cooled (tube-side), compact heat exchanger for removing heat from the circulating gas in a high-temperature gas-cooled reactor (HTGR). Measurements of velocity and pressure were made with various shell side inlet and outlet configurations. A flow configuration was developed which provides acceptable velocity distribution throughout the heat exchanger without adding excessive pressure drop

  2. Stokes flow heat transfer in an annular, rotating heat exchanger

    International Nuclear Information System (INIS)

    Saatdjian, E.; Rodrigo, A.J.S.; Mota, J.P.B.

    2011-01-01

    The heat transfer rate into highly viscous, low thermal-conductivity fluids can be enhanced significantly by chaotic advection in three-dimensional flows dominated by viscous forces. The physical effect of chaotic advection is to render the cross-sectional temperature field uniform, thus increasing both the wall temperature gradient and the heat flux into the fluid. A method of analysis for one such flow-the flow in the eccentric, annular, rotating heat exchanger-and a procedure to determine the best heat transfer conditions, namely the optimal values of the eccentricity ratio and time-periodic rotating protocol, are discussed. It is shown that in continuous flows, such as the one under consideration, there exists an optimum frequency of the rotation protocol for which the heat transfer rate is a maximum. - Highlights: → The eccentric, annular, rotating heat exchanger is studied for periodic Stokes flow. → Counter-rotating the inner tube with a periodic velocity enhances the heat transfer. → The heat-transfer enhancement under such conditions is due to chaotic advection. → For a given axial flow rate there is a frequency that maximizes the heat transfer. → There is also an optimum value of the eccentricity ratio.

  3. Comparative ex vivo study on humidifying function of three speaking valves with integrated heat and moisture exchanger for tracheotomised patients

    NARCIS (Netherlands)

    van den Boer, C.; Lansaat, L.; Muller, S.H.; van den Brekel, M.W.M.; Hilgers, F.J.M.

    2015-01-01

    Objective Assessment of humidifying function of tracheotomy speaking valves with integrated heat and moisture exchanger. Design Ex vivo measurement of water exchange and storage capacity of three tracheotomy speaking valves: Humidiphon Plus, Spiro and ProTrach DualCare (with two different heat and

  4. Comparative ex vivo study on humidifying function of three speaking valves with integrated heat and moisture exchanger for tracheotomised patients

    NARCIS (Netherlands)

    van den Boer, C.; Lansaat, L.; Muller, S. H.; van den Brekel, M. W. M.; Hilgers, F. J. M.

    2015-01-01

    Assessment of humidifying function of tracheotomy speaking valves with integrated heat and moisture exchanger. Ex vivo measurement of water exchange and storage capacity of three tracheotomy speaking valves: Humidiphon Plus, Spiro and ProTrach DualCare (with two different heat and moisture

  5. Comparative study of different exhaust heat exchangers effect on the performance and exergy analysis of a diesel engine

    NARCIS (Netherlands)

    Hatami, M.; Boot, M.D.; Ganji, D.D.; Gorji-Bandpy, M.

    2015-01-01

    In this research, the effect of three designed heat exchangers on the performance of an OM314 diesel engine and its exergy balance is investigated. Vortex generator heat exchanger (HEX), optimized finned-tube HEX and non-optimized HEX are considered and mounted on the exhaust of diesel engine.

  6. Optimum Design of Heat Exchangers Networks Part-2: case study: Atmospheric Crude Distillation Unit

    International Nuclear Information System (INIS)

    Gabr, E.M.A.; EI-Temtamy, S.A.; Deriasl, S.F.; Moustafa, H.A.

    2004-01-01

    In this paper the computerized framework introduced in part-I for Heat Exchanger Network Synthesis (HENS) with optimality conditions of achieving the least operating and capital cost has been applied on an industrial atmospheric distillation unit existing in one of the Egyptian refineries . The application includes two types of designing: grass-root and revamp of the existing design. For the final grass-root design, the saving of utilities is 50% of the actual consumption while the net annual saving reaches 2,193,690 S/year .For revamping of existing design the % saving of hot and cold utilities are 38.1% and 43.2% respectively and the annual saving of 1,723,104 $/year is achieved

  7. Parametric study on design fractors for the SCS heat exchanger using the Taguchi method

    International Nuclear Information System (INIS)

    Kim, S. H.; Choi, B. S.; Yoon, J. H.; Jang, M. H.

    2002-01-01

    Using Taguchi method, design factors, i.e. control factors of the shutdown cooling heat exchanger were investigated to qualify the effect for the time elapsed after the beginning of the system operation. Levels of the control factors were selected from calculations based on the effectiveness-NTU method. From 18 simulations with the KDESCENT program, it was found that the performance of the system is greatly influenced by inlet temperature from the component cooling water at the shell side and mass flow rate of the reactor coolant at the tube side. The Taguchi method makes it possible to select the control factor that has to be controlled and designed with caution. The method gives the effective way to estimate the influence of each control factor to the system performance

  8. An experimental study of trans-critical CO2 water–water heat pump using compact tube-in-tube heat exchangers

    International Nuclear Information System (INIS)

    Jiang, Yuntao; Ma, Yitai; Li, Minxia; Fu, Lin

    2013-01-01

    Highlights: • Thermodynamic analyses of transcritical CO 2 cycle with and without IHX are provided. • A transcritical CO 2 heat pump system adopts compact tube-in-tube heat exchangers. • Experiment results of systems with and without IHX have been analyzed and compared. • IHX can improve the performance of the transcritical CO 2 heat pump system. - Abstract: A transcritical CO 2 water–water heat pump system is introduced in this study, which employs compact tube-in-tube evaporator and gas cooler. Its primary test standards and operating conditions are introduced. Under test conditions, experiments have been carried out with compression cycles with and without internal heat exchanger (IHX). Experiment results have been analyzed and compared, showing that IHX can improve the coefficient of performance of the system. The analyses are done mainly on the variations of outlet CO 2 temperature of the gas cooler, compressor discharge pressure, compressor lubricant temperature, hot water mass flow rate, etc. When the inlet water temperature of the gas cooler is 15 °C, 20 °C, 25 °C respectively, the hot water temperature ranges from 45 °C to 70 °C, the relative COP h (coefficient of performance when heating) change index (RCI COP ) of the heat pump system with IHX is about 3.5–8% higher than that without IHX. The relative capacity change index (RCI Q ) of the heat pump system with IHX is about 5–10% higher than that without IHX. Temperature of CO 2 increases at the outlet of the gas cooler when the outlet water temperature of the gas cooler increases. Lowering the outlet CO 2 temperature of the gas cooler is an important way to improve the performance of the system

  9. High temperature heat exchange: nuclear process heat applications

    International Nuclear Information System (INIS)

    Vrable, D.L.

    1980-09-01

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

  10. Experimental investigation of a manifold heat-pipe heat exchanger

    International Nuclear Information System (INIS)

    Konev, S.V.; Wang Tszin' Lyan'; D'yakov, I.I.

    1995-01-01

    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

  11. Heat exchangers in heavy water reactor systems

    International Nuclear Information System (INIS)

    Mehta, S.K.

    1988-01-01

    Important features of some major heat exchange components of pressurized heavy water reactors and DHRUVA research reactor are presented. Design considerations and nuclear service classifications are discussed

  12. Essential Specification Elements for Heat Exchanger Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Bower, L.

    2015-07-01

    Performance upgrade and equipment degradation are the primary impetuses for a nuclear power plant to engage in the large capital cost project of heat exchanger replacement. Along with attention to these issues, consideration of heat exchanger Codes and Standards, material improvements, thermal redesign, and configuration are essential for developing User’s Design Specifications for successful replacement projects. The User’s Design Specification is the central document in procuring ASME heat exchangers. Properly stated objectives for the heat exchanger replacement are essential for obtaining the materials, configurations and thermal designs best suited for the nuclear power plant. Additionally, the code of construction required and the applied manufacturing standard (TEMA or HEI) affects how the heat exchanger may be designed or configured to meet the replacement goals. Knowledge of how Codes and Standards affect design and configuration details will aid in writing the User’s Design Specification. Joseph Oat Corporation has designed and fabricated many replacement heat exchangers for the nuclear power industry. These heat exchangers have been constructed per ASME Section III to various Code-Years or ASME Section VIII-1 to the current Code-Year also in accordance with TEMA and HEI. These heat exchangers have been a range of like-for-like replacement to complete thermal, material and configuration redesigns. Several examples of these heat exchangers with their Code, Standard and specification implications are presented. (Author.

  13. Conjugate heat and mass transfer in heat mass exchanger ducts

    CERN Document Server

    Zhang, Li-Zhi

    2013-01-01

    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

  14. Thermodynamic criterions for heat exchanger networks design

    Energy Technology Data Exchange (ETDEWEB)

    Guiglion, C.; Farhat, S.; Pibouleau, L.; Domenech, S. (Ecole Nationale Superieure d' Ingenieurs de Genie Chimique, 31 - Toulouse (France))

    1994-03-01

    This problem under consideration consists in selecting a heat exchanger network able to carry out a given request in heatings and coolings, in steady-state behaviour with constant pressure, by using if necessary cold and hot utilities, and under the constraint [Delta] T [>=] e in order to restrict investment costs. The exchanged energy and the produced entropy are compared in terms of operating costs. According to the request to be satisfied and the constraints of utility consumption, it is shown that the goal to minimize the produced entropy more or less agrees with the goal to minimize the exchanged energy. In the last part, the case where the cost of utility use is assumed to be proportional to the flow rate, with a proportionality constant only depending on the input thermodynamic state, is studied thoroughly. Under this assumption, the minimization of operating costs is compatible with the minimization of exchanged energy, and can be obtained via the maximization of the difficulty of the request part, made without using utilities. This point is based on the notion of a request easier than another, which explicits the quite vague idea that a request is all the more easier because it involves less heatings at high temperatures and less coolings at low temperatures. (author). 5 refs., 1 fig.

  15. Heat exchanger network retrofit optimization involving heat transfer enhancement

    International Nuclear Information System (INIS)

    Wang Yufei; Smith, Robin; Kim, Jin-Kuk

    2012-01-01

    Heat exchanger network retrofit plays an important role in energy saving in process industry. Many design methods for the retrofit of heat exchanger networks have been proposed during the last three decades. Conventional retrofit methods rely heavily on topology modifications which often result in a long retrofit duration and high initial costs. Moreover, the addition of extra surface area to the heat exchanger can prove difficult due to topology, safety and downtime constraints. Both of these problems can be avoided through the use of heat transfer enhancement in heat exchanger network retrofit. This paper presents a novel design approach to solve heat exchanger network retrofit problems based on heat transfer enhancement. An optimisation method based on simulated annealing has been developed to find the appropriate heat exchangers to be enhanced and to calculate the level of enhancement required. The physical insight of enhanced exchangers is also analysed. The new methodology allows several possible retrofit strategies using different retrofit methods be determined. Comparison of these retrofit strategies demonstrates that retrofit modification duration and payback time are reduced when heat transfer enhancement is utilised. Heat transfer enhancement can be also used as a substitute for increased heat exchanger network surface area to reduce retrofit investment costs.

  16. Design of heat exchangers by numerical methods

    International Nuclear Information System (INIS)

    Konuk, A.A.

    1981-01-01

    Differential equations describing the heat tranfer in shell - and tube heat exchangers are derived and solved numerically. The method of ΔT 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 ΔT 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) [pt

  17. Theory and design of heat exchanger : air cooled plate, spiral heat exchanger

    International Nuclear Information System (INIS)

    Min, Ui Dong

    1960-02-01

    This book deals with air cooled heat exchanger, which introduces heat rejection system, wet surface cooler in new from, explanation of structure and design, materials, basic design like plenums chambers and fan ring, finned tube fouling factor, airflow in forced draft and fan design. It also tells of plate heat exchanger and spiral heat exchanger giving descriptions of summary, selection, basic design, device and safety function, maintenance, structure of plate heat exchanger, frames and connector plate and, basic things of spiral tube heat exchanger.

  18. Optimization of parameters of heat exchangers vehicles

    Directory of Open Access Journals (Sweden)

    Andrei MELEKHIN

    2014-09-01

    Full Text Available The relevance of the topic due to the decision of problems of the economy of resources in heating systems of vehicles. To solve this problem we have developed an integrated method of research, which allows to solve tasks on optimization of parameters of heat exchangers vehicles. This method decides multicriteria optimization problem with the program nonlinear optimization on the basis of software with the introduction of an array of temperatures obtained using thermography. The authors have developed a mathematical model of process of heat exchange in heat exchange surfaces of apparatuses with the solution of multicriteria optimization problem and check its adequacy to the experimental stand in the visualization of thermal fields, an optimal range of managed parameters influencing the process of heat exchange with minimal metal consumption and the maximum heat output fin heat exchanger, the regularities of heat exchange process with getting generalizing dependencies distribution of temperature on the heat-release surface of the heat exchanger vehicles, defined convergence of the results of research in the calculation on the basis of theoretical dependencies and solving mathematical model.

  19. The importance of control considerations for heat exchanger network synthesis: a case study

    Directory of Open Access Journals (Sweden)

    S.G. Oliveira

    2001-06-01

    Full Text Available Cost optimization in the synthesis decision tree often leads to a reduced degree of freedom which degrades the process’s ability to reject disturbances as a consequence of low controllability. In fact, Heat Exchanger Networks (HENs obtained by traditional synthesis procedures that ignore controllability aspects must be evaluated in this context a posteriori. The aim of this work was to develop a procedure that includes RGA and SVD measures of controllability, which are solely based on steady state information, thereby freeing the synthesis procedure of the cumbersome dynamic analysis. When a structure is defined during a traditional HEN synthesis procedure, a degree of freedom analysis is approached as a simulation problem. Next, an optimization is performed, since new variables are usually added to increase the degree of freedom of the HEN in order to render it controllable. A key point in the proposed procedure is the inference of controllability based on the proposed controllability measures, which also provide a control scheme by pairing controlled and manipulated variables during the process design. A HEN reported in the literature is used to illustrate the proposed procedure. The steady state simulator Aspen Plus and the dynamic simulator Aspen Dynamics (Aspentech, Inc. were employed.

  20. Complex Heat Exchangers for Improved Performance

    Science.gov (United States)

    Bran, Gabriela Alejandra

    After a detailed literature review, it was determined that there was a need for a more comprehensive study on the transient behavior of heat exchangers. Computational power was not readily available when most of the work on transient heat exchangers was done (1956 - 1986), so most of these solutions have restrictions, or very specific assumptions. More recently, authors have obtained numerical solutions for more general problems (2003 - 2013), but they have investigated very specific conditions, and cases. For a more complex heat exchanger (i.e. with heat generation), the transient solutions from literature are no longer valid. There was a need to develop a numerical model that relaxes the restrictions of current solutions to explore conditions that have not been explored. A one dimensional transient heat exchanger model was developed. There are no restrictions on the fluids and wall conditions. The model is able to obtain a numerical solution for a wide range of fluid properties and mass flow rates. Another innovative characteristic of the numerical model is that the boundary and initial conditions are not limited to constant values. The boundary conditions can be a function of time (i.e. sinusoidal signal), and the initial conditions can be a function of position. Four different cases were explored in this work. In the first case, the start-up of a system was investigated where the whole system is assumed to be at the same temperature. In the second case, the new steady state in case one gets disrupted by a smaller inlet temperature step change. In the third case, the new steady state in case one gets disrupted by a step change in one of the mass flow rates. The response of these three cases show that there are different transient behaviors, and they depend on the conditions imposed on the system. The fourth case is a system that has a sinusoidal time varying inlet temperature for one of the flows. The results show that the sinusoidal behavior at the inlet

  1. Regenerator heat exchanger – calculation of heat recovery efficiency and pressure loss

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per Kvols

    Performance of heat exchangers is determined based on two main parameters: efficiency to exchange / recover heat and pressure loss due to friction between fluid and exchanger surfaces. These two parameters are contradicting each other which mean that the higher is efficiency the higher becomes...... pressure loss. The aim of the optimized design of heat exchanger is to reach the highest or the required heat efficiency and at the same time to keep pressure losses as low as possible keeping total exchanger size within acceptable size. In this report is presented analytical calculation method...... to calculate efficiency and pressure loss in the regenerator heat exchanger with a fixed matrix that will be used in the decentralized ventilation unit combined in the roof window. Moreover, this study presents sensitivity study of regenerator heat exchanger performance, taking into account, such parameters as...

  2. Heat Exchanger Lab for Chemical Engineering Undergraduates

    Science.gov (United States)

    Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.

    2015-01-01

    Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…

  3. Heat exchanger versus regenerator: A fundamental comparison

    NARCIS (Netherlands)

    Will, M.E.; Waele, de A.T.A.M.

    2005-01-01

    Irreversible processes in regenerators and heat exchangers limit the performance of cryocoolers. In this paper we compare the performance of cryocoolers, operating with regenerators and heat exchangers from a fundamental point of view. The losses in the two systems are calculated from the entropy

  4. Experimental evaluation of vibrations in heat exchangers

    International Nuclear Information System (INIS)

    Martin Ghiselli, A.

    1997-01-01

    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) [es

  5. Cardioplegia heat exchanger design modelling using computational fluid dynamics.

    Science.gov (United States)

    van Driel, M R

    2000-11-01

    A new cardioplegia heat exchanger has been developed by Sorin Biomedica. A three-dimensional computer-aided design (CAD) model was optimized using computational fluid dynamics (CFD) modelling. CFD optimization techniques have commonly been applied to velocity flow field analysis, but CFD analysis was also used in this study to predict the heat exchange performance of the design before prototype fabrication. The iterative results of the optimization and the actual heat exchange performance of the final configuration are presented in this paper. Based on the behaviour of this model, both the water and blood fluid flow paths of the heat exchanger were optimized. The simulation predicted superior heat exchange performance using an optimal amount of energy exchange surface area, reducing the total contact surface area, the device priming volume and the material costs. Experimental results confirm the empirical results predicted by the CFD analysis.

  6. Heat transfer analysis of short helical borehole heat exchangers

    International Nuclear Information System (INIS)

    Zarrella, Angelo; De Carli, Michele

    2013-01-01

    Highlights: ► Vertical ground heat exchanger with a helical shaped pipe is analyzed. ► The model considers the interaction between the ground and the environment. ► The results of the model are in good agreement with the experimental values. ► The weather conditions considerably affect the fluid heat carrier temperature. ► The pitch between the turns does not affect the behaviour of the heat exchanger. -- Abstract: In this paper a numerical model to analyze the thermal behaviour of vertical ground heat exchangers with a helical shaped pipe is presented. This type of configuration can be a suitable alternative to conventional ground heat exchangers, especially when the heating and cooling loads of the building are very low. The model describes the heat transfer problem by means of a network of interconnected thermal resistances and capacitances. Moreover, as the investigated ground heat exchanger is usually installed in shallow depth, the model takes into account the interaction between the ground and the ambient environment which affects the fluid heat carrier temperature into the heat exchanger and, as a consequence, the energy efficiency of the heat pump. After a sensitivity analysis on the mesh parameters, the presented model is compared with experimental data and the simulation results show good agreement with the measurements. Finally, analyses to investigate the influence of the weather conditions, of the axial heat transfer and of the pitch between the turns of the helical pipe for two types of ground are carried out.

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

    Science.gov (United States)

    Koplow, Jeffrey P

    2013-12-10

    Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

  8. Heat transfer characteristics of a direct contact heat exchanger

    International Nuclear Information System (INIS)

    Kinoshita, I.; Nishi, Y.

    1993-01-01

    As a first step for development of a direct contact steam generator for FBRs, fundamental heat transfer characteristics of a liquid-liquid contact heat exchanger were evaluated by heat transfer experiment with low melting point alloy and water. Distinctive characteristics of direct contact heat transfer with liquid metal and water was obtained. (author)

  9. Effectiveness of a heat exchanger in a heat pump clothes dryer

    Science.gov (United States)

    Nasution, A. H.; Sembiring, P. G.; Ambarita, H.

    2018-02-01

    This paper deals with study on a heat pump clothes dryer coupled with a heat exchanger. The objective is to explore the effects of the heat exchanger on the performance of the heat pump dryer. The heat pump dryer consists of a vapor compression cycle and integrated with a drying room with volume 1 m3. The power of compressor is 800 Watt and the refrigerant of the cycle is R22. The heat exchanger is a flat plate type with dimensions of 400 mm × 400 mm × 400 mm. The results show the present of the heat exchanger increase the performance of the heat pump dryer. In the present experiment the COP, TP and SMER increase 15.11%, 4.81% and 58.62%, respectively. This is because the heat exchanger provides a better drying condition in the drying room with higher temperature and lower relative humidity in comparison with heat pump dryer without heat exchanger. The effectiveness of the heat exchanger is also high, it is above 50%. It is suggested to install a heat exchanger in a heat pump dryer.

  10. Component Cooling Heat Exchanger Heat Transfer Capability Operability Monitoring

    International Nuclear Information System (INIS)

    Mihalina, M.; Djetelic, N.

    2010-01-01

    The ultimate heat sink (UHS) is of highest importance for nuclear power plant safe and reliable operation. The most important component in line from safety-related heat sources to the ultimate heat sink water body is a component cooling heat exchanger (CC Heat Exchanger). The Component Cooling Heat Exchanger has a safety-related function to transfer the heat from the Component Cooling (CC) water system to the Service Water (SW) system. SW systems throughout the world have been the root of many plant problems because the water source, usually river, lake, sea or cooling pond, are conductive to corrosion, erosion, biofouling, debris intrusion, silt, sediment deposits, etc. At Krsko NPP, these problems usually cumulate in the summer period from July to August, with higher Sava River (service water system) temperatures. Therefore it was necessary to continuously evaluate the CC Heat Exchanger operation and confirm that the system would perform its intended function in accordance with the plant's design basis, given as a minimum heat transfer rate in the heat exchanger design specification sheet. The Essential Service Water system at Krsko NPP is an open cycle cooling system which transfers heat from safety and non-safety-related systems and components to the ultimate heat sink the Sava River. The system is continuously in operation in all modes of plant operation, including plant shutdown and refueling. However, due to the Sava River impurities and our limited abilities of the water treatment, the system is subject to fouling, sedimentation buildup, corrosion and scale formation, which could negatively impact its performance being unable to satisfy its safety related post accident heat removal function. Low temperature difference and high fluid flows make it difficult to evaluate the CC Heat Exchanger due to its specific design. The important effects noted are measurement uncertainties, nonspecific construction, high heat transfer capacity, and operational specifics (e

  11. Studi Analitik dan Numerik Perpindahan Panas pada Fin Trapesium (Studi Kasus pada Finned Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Ahmad Zaini

    2013-09-01

    Full Text Available Penambahan fin pada pipa penukar kalor merupakan suatu upaya memperbesar perpindahan kalor konduksi dan konveksi, dengan cara memperluas bidang geometri. Pada penelitian ini dianalisa secara analitik dan numerik perpindahan kalor pada fin dengan profil longitudinal tidak seragam atau berubah terhadap jarak dari dasar fin, dengan memvariasikan ketebalan ujung fin. Hasil dari kedua studi ini tidak jauh berbeda, pada keduanya menjelaskan bahwa fin dengan ketebalan ujung 0,9 mm (fin trapesium terbalik paling baik dari 5 variasi lainnya; serta perubahan temperatur paling besar terjadi pada sepertiga pertama dari panjang  fin, ini artinya pelepasan kalor terbesar terjadi pada daerah tersebut. Perbedaannya adalah pada persentase penurunan temperatur sepanjang  fin terhadap temperatur dasar fin, untuk ketebalan 0,9 mm pada studi analitik sebesar 91,92% dan pada studi numerik sebesar 91,78%. Hal ini berarti metode penyelesaian persamaan diferensial orde 2 dengan koefisien variabel dengan cara pembedahan koefisien variabel pada ODE, sudah benar dan valid. Namun bila ditinjau dari waktu yang diperlukan untuk komputasinya, studi analitik membutuhkan waktu lebih lama. Waktu yang diperlukan dalam komputasinya tergantung dari fungsi koefisien variabel.

  12. Modelling of Split Condenser Heat Pump with Limited Set of Plate Heat Exchanger Dimensions

    DEFF Research Database (Denmark)

    Christensen, Stefan Wuust; Elmegaard, Brian; Markussen, Wiebke Brix

    2017-01-01

    in parallel to different temperature levels, whereas only one stream is heated in a THP. The length/width ratio of the plate heat exchangers on the high pressure side of a SCHP was investigated to find the optimal plate dimensions with respect to minimum area of the heat exchangers. The total heat exchanger...... area was found to decrease with an increasing length/width ratio of the plates. The marginal change in heat exchanger area was shown to be less significant for heat exchangers with high length/width ratios. In practice only a limited number of plate dimensions are available and feasible...... in the production. This was investigated to find the practical potential of a SCHP compared to a THP. Using plates optimized for a SCHP in a THP, the total required heat exchanger area increased by approximately 100% for the conditions investigated in this study, indicating that available plate dimensions influence...

  13. Corrosion study of heat exchanger tubes in pressurized water cooled nuclear reactors by conversion electron Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Homonnay, Z.; Kuzmann, E.; Varga, K.; Nemeth, Z.; Szabo, A.; Rado, K.; Schunk, J.; Tilky, P.; Patek, G.

    2005-01-01

    Nuclear energy production tends to return into the focus of interest because of the constantly increasing energy need of the world and the green house effect problems of the strongest competitor oil or gas based power plants. In addition to the construction of new nuclear power plants, lifetime extension of the existing ones is the most cost effective investment in the energy business. However, feasibility and safety issues become very important at this point, and corrosion of the construction materials should be carefully investigated before decision on a potential lifetime extension of a reactor. 57 Fe-Conversion Electron Moessbauer Spectroscopy (CEMS) is a sensitive tool to analyze the phase composition of corrosion products on the surface of stainless steel. The upper ∼300 nm can be investigated due to the penetration range of conversion electrons. The corrosion state of heat exchanger tubes from the four reactor units of the Paks Nuclear Power Plant, Hungary, were analyzed by several methods including CEMS. The primary circuit side of the tubes was studied on selected samples cut out from the heat exchangers during regular maintenance. Cr- and Ni-substituted magnetite, sometimes hematite, amorphous Fe-oxides/oxyhydroxides as well as the signal of bulk austenitic steel of the tubes were detected. The level of Cr- and Ni-substitution in the magnetite phase could be estimated from the Moessbauer spectra. Correlation between earlier decontamination cycles and the corrosion state of the heat exchangers was sought. In combination with other methods, a hybrid structure of the surface oxide layer of several microns was established. It is suggested that previous AP-CITROX decontamination cycles can be responsible for this structure which makes the oxide layer mobile. This mobility may be responsible for unwanted corrosion product transport into the reactor vessel by the primary coolant.

  14. Thermal behavior of a heat exchanger module for seasonal heat storage

    DEFF Research Database (Denmark)

    Fan, Jianhua; Furbo, Simon; Andersen, Elsa

    2012-01-01

    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......, recommendations on how best to transfer heat to and from the seasonal heat storage module are given....

  15. Building America Case Study: Simplified Air Distribution, Desuperheaters, and Sub-Slab Geothermal Heat Exchangers, Pittsburgh, Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    N. Mittereder, A. Poerschke

    2017-05-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab.

  16. Building America Case Study: Simplified Air Distribution, Desuperheaters, and Sub-Slab Geothermal Heat Exchangers, Pittsburgh, Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    2017-06-08

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab.

  17. A study of the flow boiling heat transfer in an annular heat exchanger with a mini gap

    Directory of Open Access Journals (Sweden)

    Musiał Tomasz

    2017-01-01

    Full Text Available In this paper the research on flow boiling heat transfer in an annular mini gap was discussed. A one- dimensional mathematical approach was proposed to describe stationary heat transfer in the gap. The mini gap 1 mm wide was created between a metal pipe with enhanced exterior surface and an external tempered glass pipe positioned along the same axis. The experimental test stand consists of several systems: the test loop in which distilled water circulates, the data and image acquisition system and the supply and control system. Known temperature distributions of the metal pipe with enhanced surface and of the working fluid helped to determine, from the Robin boundary condition, the local heat transfer coefficients at the fluid - heated surface contact. In the proposed mathematical model it is assumed that the cylindrical wall is a planar multilayer wall. The numerical results are presented on a chart as function of the heat transfer coefficient along the length of the mini gap.

  18. Viscose liquid heat treatment using plate scraper heat exchanger

    Directory of Open Access Journals (Sweden)

    K. A. Rashkin

    2012-01-01

    Full Text Available The current work analyzes the use of different types of heat exchangers, depending on the technology of production. It is taken the detail analysis of the ways of applicability of various types of heat exchangers, depending on the viscosity of the processed product. It is posed the problem of the analytical determination of the required area of heat exchange with the use of differential equations of heat transfer in a moving liquid media, written in cylindrical coordinates, for symmetrical temperature distribution, without taking in account the energy dissipation.

  19. An experimental study of the air-side particulate fouling in finned-tube heat exchangers of air conditioners through accelerated tests

    International Nuclear Information System (INIS)

    Ahn, Young Chull; Cho, Jae Min; Lee, Jae Keun; Lee, Hyun Uk; Ahn, Seung Phyo; Youn, Deok Hyun; Kang, Tae Wook; Ock, Ju Jo

    2003-01-01

    The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the fouling characteristics trough accelerated tests. The fouling characteristics are analyzed as functions of a dust concentration (1.28 and 3.84 g/m 3 ), a face velocity (0.5, 1.0, and 1.5 m/s), and a surface condition. The cooling capacity in the slitted finned-tube heat exchangers at the face velocity of 1 m/s decreases about 2% and the pressure drop increases up to 57%. The rate of build-up of fouling is observed to be 3 times slower for this three-fold reduction of dust concentration whilst still approaching the same asymptotic level

  20. Heat exchanger, head and shell acceptance criteria

    International Nuclear Information System (INIS)

    Lam, P.S.; Sindelar, R.L.

    1992-09-01

    Instability of postulated flaws in the head component of the heat exchanger could not produce a large break, equivalent to a DEGB in the PWS piping, due to the configuration of the head and restraint provided by the staybolts. Rather, leakage from throughwall flaws in the head would increase with flaw length with finite leakage areas that are bounded by a post-instability flaw configuration. Postulated flaws at instability in the shell of the heat exchanger or in the cooling water nozzles could produce a large break in the Cooling Water System (CWS) pressure boundary. An initial analysis of flaw stability for postulated flaws in the heat exchanger head was performed in January 1992. This present report updates that analysis and, additionally, provides acceptable flaw configurations to maintain defined structural or safety margins against flaw instability of the external pressure boundary components of the heat exchanger, namely the head, shell, and cooling water nozzles. Structural and flaw stability analyses of the heat exchanger tubes, the internal pressure boundary of the heat exchangers or interface boundary between the PWS and CWS, were previously completed in February 1992 as part of the heat exchanger restart evaluation and are not covered in this report

  1. Sleeving repair of heat exchanger tubes

    International Nuclear Information System (INIS)

    Street, Michael D.; Schafer, Bruce W.

    2000-01-01

    Defective heat exchanger tubes can be repaired using techniques that do not involve the cost and schedule penalties of component replacement. FTI's years of experience repairing steam generator tubes have been successfully applied to heat exchangers. Framatome Technologies heat exchanger sleeves can bridge defective areas of the heat exchanger tubes, sleeves have been designed to repair typical heat exchanger tube defects caused by excessive tube vibration, stress corrosion cracking, pitting or erosion. By installing a sleeve, the majority of the tube's heat transfer and flow capacity is maintained and the need to replace the heat exchanger can be delayed or eliminated. Both performance and reliability are improved. FTI typically installs heat exchanger tube sleeves using either a roll expansion or hydraulic expansion process. While roll expansion of a sleeve can be accomplished very quickly, hydraulic expansion allows sleeves to be installed deep within a tube where a roll expander cannot reach. Benefits of FTI's heat exchanger tube sleeving techniques include: - Sleeves can be positioned any where along the tube length, and for precise positioning of the sleeve eddy current techniques can be employed. - Varying sleeve lengths can be used. - Both the roll and hydraulic expansion processes are rapid and both produce joints that do not require stress relief. - Because of low leak rates and speed of installations, sleeves can be used to preventatively repair likely-to-fail tubes. - Sleeves can be used for tube stiffening and to limit leakage through tube defects. - Because of installation speed, there is minimal impact on outage schedules and budgets. FTI's recently installed heat exchanger sleeving at the Kori-3 Nuclear Power Station in conjunction with Korea Plant Service and Engineering Co., Ltd. The sleeves were installed in the 3A and 3B component cooling water heat exchangers. A total of 859 tubesheet and 68 freespan sleeves were installed in the 3A heat

  2. Development of heat resistant ion exchange resin. First Report

    International Nuclear Information System (INIS)

    Onozuka, Teruo; Shindo, Manabu

    1995-01-01

    In nuclear power stations, as a means of maintaining the soundness of nuclear reactors, the cleaning of reactor cooling water has been carried out. But as for the ion exchange resin which is used as the cleaning agent in the filtrating and desalting facility in reactor water cleaning system, since the heat resistance is low, high temperature reactor water is cooled once and cleaned, therefore large heat loss occurs. If the cleaning can be done at higher temperature, the reduction of heat loss and compact cleaning facilities become possible. In this study, a new ion exchange resin having superior heat resistance has been developed, and the results of the test of evaluating the performance of the developed ion exchange resin are reported. The heat loss in reactor water cleaning system, the heat deterioration of conventional ion exchange resin, and the development of the anion exchange resin of alkyl spacer type are described. The outline of the performance evaluation test, the experimental method, and the results of the heat resistance, ion exchange characteristics and so on of C4 resin are reported. The with standable temperature of the developed anion exchange resin was estimated as 80 - 90degC. The ion exchange performance at 95degC of this resin did not change from that at low temperature in chloride ions and silica, and was equivalent to that of existing anion exchange resin. (K.I.)

  3. Development of heat resistant ion exchange resin. First Report

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, Teruo; Shindo, Manabu [Tohoku Electric Power Co., Inc., Sendai (Japan)

    1995-01-01

    In nuclear power stations, as a means of maintaining the soundness of nuclear reactors, the cleaning of reactor cooling water has been carried out. But as for the ion exchange resin which is used as the cleaning agent in the filtrating and desalting facility in reactor water cleaning system, since the heat resistance is low, high temperature reactor water is cooled once and cleaned, therefore large heat loss occurs. If the cleaning can be done at higher temperature, the reduction of heat loss and compact cleaning facilities become possible. In this study, a new ion exchange resin having superior heat resistance has been developed, and the results of the test of evaluating the performance of the developed ion exchange resin are reported. The heat loss in reactor water cleaning system, the heat deterioration of conventional ion exchange resin, and the development of the anion exchange resin of alkyl spacer type are described. The outline of the performance evaluation test, the experimental method, and the results of the heat resistance, ion exchange characteristics and so on of C4 resin are reported. The with standable temperature of the developed anion exchange resin was estimated as 80 - 90degC. The ion exchange performance at 95degC of this resin did not change from that at low temperature in chloride ions and silica, and was equivalent to that of existing anion exchange resin. (K.I.).

  4. Experimental study on CO2 frosting and clogging in a brazed plate heat exchanger for natural gas liquefaction process

    Science.gov (United States)

    Wu, Jitan; He, Tianbiao; Ju, Yonglin

    2018-04-01

    The plate-fin heat exchanger (PFHE), which has been widely used in natural gas liquefaction (LNG) industry at present, has some disadvantages such as being sensitive to the impurities in the feed gas, such as water, CO2 and H2S. Compared with the PFHE, the brazed plate heat exchanger (BPHE), which has been applied in some boil off gas (BOG) recycling LNG plants of small to middle size, has simpler inherent structure and higher impurity tolerance. In this study the BPHE is suggested to replace the PFHE to simplify or even omit the massive CO2 purification equipment for the LNG process. A set of experimental apparatus is designed and constructed to investigate the influence of the CO2 concentration of the natural gas on solid precipitation inside a typical BPHE meanly by considering the flow resistance throughout the LNG process. The results show that the maximum allowable CO2 concentration of the natural gas liquefied in the BPHE is two orders of magnitude higher than that in the PFHE under the same condition. In addition, the solid-liquid separation for the CO2 impurity is studied and the reasonable separating temperature is obtained. The solid CO2 should be separated below 135 K under the pressure of 3 MPa.

  5. Heat Exchanger Support Bracket Design Calculations

    International Nuclear Information System (INIS)

    Rucinski, Russ

    1995-01-01

    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.

  6. A concept of PWR using plate and shell heat exchangers

    International Nuclear Information System (INIS)

    Freire, Luciano Ondir; Andrade, Delvonei Alves de

    2015-01-01

    In previous work it was verified the physical possibility of using plate and shell heat exchangers for steam generation in a PWR for merchant ships. This work studies the possibility of using GESMEX commercial of the shelf plate and shell heat exchanger of series XPS. It was found it is feasible for this type of heat exchanger to meet operational and accidental requirements for steam generation in PWR. Additionally, it is proposed an arrangement of such heat exchangers inside the reactor pressure vessel. Such arrangement may avoid ANSI/ANS51.1 nuclear class I requirements on those heat exchangers because they are contained in the reactor coolant pressure barrier and play no role in accidental scenarios. Additionally, those plates work under compression, preventing the risk of rupture. Being considered non-nuclear safety, having a modular architecture and working under compression may turn such architectural choice a must to meet safety objectives with improved economics. (author)

  7. A concept of PWR using plate and shell heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Freire, Luciano Ondir; Andrade, Delvonei Alves de, E-mail: luciano.ondir@gmail.com, E-mail: delvonei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    In previous work it was verified the physical possibility of using plate and shell heat exchangers for steam generation in a PWR for merchant ships. This work studies the possibility of using GESMEX commercial of the shelf plate and shell heat exchanger of series XPS. It was found it is feasible for this type of heat exchanger to meet operational and accidental requirements for steam generation in PWR. Additionally, it is proposed an arrangement of such heat exchangers inside the reactor pressure vessel. Such arrangement may avoid ANSI/ANS51.1 nuclear class I requirements on those heat exchangers because they are contained in the reactor coolant pressure barrier and play no role in accidental scenarios. Additionally, those plates work under compression, preventing the risk of rupture. Being considered non-nuclear safety, having a modular architecture and working under compression may turn such architectural choice a must to meet safety objectives with improved economics. (author)

  8. Method of relative comparison of the thermohydraulic efficiency of heat exchange intensification in channels of heat-exchange surfaces

    International Nuclear Information System (INIS)

    Dubrovskij, E.V.; Vasil'ev, V.Ya.

    2002-01-01

    One introduces a technique to compare relatively thermohydraulic efficiency of heat transfer intensification in channels of heat exchange surfaces of any design types. It is shown that one should compare thermohydraulic efficiency of heat exchange intensification as to the thermal power of heat exchangers and pressure losses in channels with turbulators and in polished channels of heat exchange surfaces on the basis of dimensions of heat exchangers, their heat exchange surfaces and at similar (as to Re numbers) modes of coolant flow [ru

  9. Investigation of Condensation Heat Transfer Correlation of Heat Exchanger Design in Secondary Passive Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Yun Jae; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Kang, Hanok; Lee, Taeho; Park, Cheontae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-12-15

    Recently, condensation heat exchangers have been studied for applications to the passive cooling systems of nuclear plants. To design vertical-type condensation heat exchangers in secondary passive cooling systems, TSCON (Thermal Sizing of CONdenser), a thermal sizing program for a condensation heat exchanger, was developed at KAERI (Korea Atomic Energy Research Institute). In this study, the existing condensation heat transfer correlation of TSCON was evaluated using 1,157 collected experimental data points from the heat exchanger of a secondary passive cooling system for the case of pure steam condensation. The investigation showed that the Shah correlation, published in 2009, provided the most satisfactory results for the heat transfer coefficient with a mean absolute error of 34.8%. It is suggested that the Shah correlation is appropriate for designing a condensation heat exchanger in TSCON.

  10. Selection of Rational Heat Transfer Intensifiers in the Heat Exchanger

    Directory of Open Access Journals (Sweden)

    S. A. Burtsev

    2016-01-01

    Full Text Available The paper considers the applicability of different types of heat transfer intensifiers in the heat exchange equipment. A review of the experimental and numerical works devoted to the intensification of the dimpled surface, surfaces with pins and internally ribbed surface were presented and data on the thermal-hydraulic characteristics of these surfaces were given. We obtained variation of thermal-hydraulic efficiency criteria for 4 different objective functions and 15 options for the intensification of heat transfer. This makes it possible to evaluate the advantages of the various heat transfer intensifiers. These equations show influence of thermal and hydraulic characteristics of the heat transfer intensifiers (the values of the relative heat transfer and drag coefficients on the basic parameters of the shell-and-tube heat exchanger: the number and length of the tubes, the volume of the heat exchanger matrix, the coolant velocity in the heat exchanger matrix, coolant flow rate, power to pump coolant (or pressure drop, the amount of heat transferred, as well as the average logarithmic temperature difference. The paper gives an example to compare two promising heat transfer intensifiers in the tubes and shows that choosing the required efficiency criterion to search for optimal heat exchanger geometry is of importance. Analysis is performed to show that a dimpled surface will improve the effectiveness of the heat exchanger despite the relatively small value of the heat transfer intensification, while a significant increase in drag of other heat transfer enhancers negatively affects their thermalhydraulic efficiency. For example, when comparing the target functions of reducing the heat exchanger volume, the data suggest that application of dimpled surfaces in various fields of technology is possible. But there are also certain surfaces that can reduce the parameters of a heat exchanger. It is shown that further work development should be aimed at

  11. Local study of flow and low Reynolds thermal-hydraulic performance of a corrugated plane duct: application to plate heat exchangers

    International Nuclear Information System (INIS)

    Hugonnot, Patrick

    1989-01-01

    This research thesis addresses the local study of a flow in a corrugated plane duct by using experimental and numerical approaches on the one hand, and the experimental determination of thermal-hydraulic performance at low Reynolds number of different plate heat exchanger ducts on the other hand. Experimental visualisations of the local flow allowed regime transitions in 2D and 3D geometries to be determined. As far as the 2D duct is concerned, a wave profile optimisation is proposed, and the numerical study performed by using the TRIO software is in good agreement with experimental results. The optimised duct configuration can thus be envisaged for an industrial development. The determination of the friction coefficient and of the global heat exchange coefficient of different corrugated ducts allows plate exchangers to be sized on a wide range of Reynolds numbers. The respective influences of natural convection and of fluid thermal dependency on heat exchange have been studied [fr

  12. Numerical Simulation of Nanofluid Suspensions in a Geothermal Heat Exchanger

    OpenAIRE

    Xiao-Hui Sun; Hongbin Yan; Mehrdad Massoudi; Zhi-Hua Chen; Wei-Tao Wu

    2018-01-01

    It has been shown that using nanofluids as heat carrier fluids enhances the conductive and convective heat transfer of geothermal heat exchangers. In this paper, we study the stability of nanofluids in a geothermal exchanger by numerically simulating nanoparticle sedimentation during a shut-down process. The nanofluid suspension is modeled as a non-linear complex fluid; the nanoparticle migration is modeled by a particle flux model, which includes the effects of Brownian motion, gravity, turb...

  13. Integrated Heat Exchange For Recuperation In Gas Turbine Engines

    Science.gov (United States)

    2016-12-01

    combustion engines conduct heat transfer in the exhaust system. The exhaust valves have hollow stems containing sodium, which act as heat pipes with...is the use of heat pipes in internal combustion engines . Internal combustion engines have combustion chambers with temperatures as high as 2700 K...accomplished using evaporative heat pipes . This study explores the feasibility of embedding this heat exchange system within engines using a

  14. Experimental evaluation of sodium to air heat exchanger performance

    International Nuclear Information System (INIS)

    Vinod, V.; Pathak, S.P.; Paunikar, V.D.; Suresh Kumar, V.A.; Noushad, I.B.; Rajan, K.K.

    2013-01-01

    Highlights: ► Sodium to air heat exchangers are used to remove the decay heat produced in fast breeder reactor after shutdown. ► Finned tube sodium to air heat exchanger with sodium on tube side was tested for its heat transfer performance. ► A one dimensional computer code was validated by the experimental data obtained. ► Non uniform sodium and air flow distribution was present in the heat exchanger. - Abstract: Sodium to air heat exchangers (AHXs) is used in Prototype Fast Breeder Reactor (PFBR) circuits to reject the decay heat produced by the radioactive decay of the fission products after reactor shutdown, to the atmospheric air. The heat removal through sodium to air heat exchanger maintains the temperature of reactor components in the pool within safe limits in case of non availability of normal heat transport path. The performance of sodium to air heat exchanger is very critical to ensure high reliability of the decay heat removal systems in sodium cooled fast breeder reactors. Hence experimental evaluation of the adequacy of the heat transfer capability gives confidence to the designers. A finned tube cross flow sodium to air heat exchanger of 2 MW heat transfer capacity with sodium on tube side and air on shell side was tested in the Steam Generator Test Facility at Indira Gandhi Center for Atomic Research, India. Heat transfer experiments were carried out with forced circulation of sodium and air, which confirmed the adequacy of heat removal capacity of the heat exchanger. The testing showed that 2.34 MW of heat power is transferred from sodium to air at nominal flow and temperature conditions. A one dimensional computer code developed for design and analysis of the sodium to air heat exchanger was validated by the experimental data obtained. An equivalent Nusselt number, Nu eq is derived by approximating that the resistance of heat transfer from sodium to air is contributed only by the film resistance of air. The variation of Nu eq with respect

  15. Modelling and simulation of a heat exchanger

    Science.gov (United States)

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

    1991-01-01

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

  16. Improvements in or relating to heat exchangers

    International Nuclear Information System (INIS)

    Linning, D.L.

    1976-01-01

    A 'tube-in-shell' heat exchanger is described for effecting heat exchange between liquid metal and water. In conventional heat exchangers of this type a condition can arise wherein Na passing through the tube plate at the water inlet end of the heat exchanger may be above the saturation temperature of the water, and although resultant boiling of the water in the region of the tube plate would tend to counter stagnation there is a possibility that sub-cooled boiling associated with stagnation may occur in the central area of the tube plate, and this could be the source of corrosion. The design of heat exchanger described is directed towards a solution of this problem. The heat exchanger comprises an elongated shell having two spaced transverse tube plates sealed to the shell so as to provide end and intermediate chambers. A bundle of spaced parallel heat exchange tubes extends between the tube plates, interconnecting the end chambers with an inlet port for liquid metal flow to one of the end chambers and an outlet port for liquid metal flow from the other of the end chambers, and inlet and outlet ports for flow of water through the intermediate chamber, these ports being at opposite ends of the intermediate chamber. The intermediate chamber has a tube closed to liquid metal flow extending between the tube plates, this tube having an inlet port for water adjacent to the tube plate at the inlet region of the intermediate chamber and an outlet port at the outlet region. This tube has open ends and is laterally supported by neighbouring heat exchange tubes, or alternatively may have closed ends and be end supported by penetration of the tube plates, the inlet and outlet ports for flow of water being perforations in the wall of the tube. (U.K.)

  17. Design concept for vessels and heat exchangers

    International Nuclear Information System (INIS)

    Elfmann, W.; Ferrari, L.D.B.

    1981-01-01

    A design concept for vessels and heat exchangers against internal and external loads resulting from normal operation and accident is shown. A definition and explanation of the operating conditions and stress levels are given. A description of the type of analysis (stress, fatigue, deformation, stability, earthquake and vibration) is presented in detail, also including technical guidelines which are used for the vessels and heat exchangers and their individual structure parts. (Author) [pt

  18. Stirling Engine With Radial Flow Heat Exchangers

    Science.gov (United States)

    Vitale, N.; Yarr, George

    1993-01-01

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

  19. Optimization of the Single Staggered Wire and Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Arsana I Made

    2016-01-01

    Full Text Available Wire and tube heat exchanger consists of a coiled tube, and wire is welded on the two sides of it in normal direction of the tube. Generally,wire and tube heat exchanger uses inline wire arrangement between the two sides, whereas in this study, it used staggered wire arrangement that reduces the restriction of convection heat transfer. This study performed the optimization of single staggered wire and tube heat exchanger to increase the capacity and reduce the mass of the heat exchanger. Optimization was conducted with the Hooke-Jeeves method, which aims to optimize the geometry of the heat exchanger, especially on the diameter (dw and the distance between wires (pw. The model developed to present heat transfer correlations on single staggered wire and tube heat exchanger was valid. The maximum optimization factor obtained when the diameter wire was 0.9 mm and the distance between wires (pw was 11 mm with the fref value = 1.5837. It means that the optimized design only using mass of 59,10 % and could transfer heat about 98,5 % from the basis design.

  20. Research on Heat Exchange Process in Aircraft Air Conditioning System

    Science.gov (United States)

    Chichindaev, A. V.

    2017-11-01

    Using of heat-exchanger-condenser in the air conditioning system of the airplane Tu-204 (Boeing, Airbus, Superjet 100, MS-21, etc.) for cooling the compressed air by the cold air with negative temperature exiting the turbine results in a number of operational problems. Mainly it’s frosting of the heat exchange surface, which is the cause of live-section channels frosting, resistance increasing and airflow in the system decreasing. The purpose of this work is to analyse the known freeze-up-fighting methods for heat-exchanger-condenser, description of the features of anti-icing protection and offering solutions to this problem. For the problem of optimizing the design of heat exchangers in this work used generalized criterion that describes the ratio of thermal resistances of cold and hot sections, which include: the ratio of the initial values of heat transfer agents flow state; heat exchange surface finning coefficients; factors which describes the ratio of operating parameters and finning area. By controlling the ratio of the thermal resistances can be obtained the desired temperature of the heat exchange surface, which would prevent freezing. The work presents the results of a numerical study of the effect of different combinations of regime and geometrical factors changes on reduction of the heat-exchanger-condenser freezing surface area, including using of variable ratio of thermal resistances.

  1. Liquid metal heat transfer in heat exchangers under low flow rate conditions

    International Nuclear Information System (INIS)

    Mochizuki, Hiroyasu

    2015-01-01

    The present paper describes the liquid metal heat transfer in heat exchangers under low flow rate conditions. Measured data from some experiments indicate that heat transfer coefficients of liquid metals at very low Péclet number are much lower than what are predicted by the well-known empirical relations. The cause of this phenomenon was not fully understood for many years. In the present study, one countercurrent-type heat exchanger is analyzed using three, separated countercurrent heat exchanger models: one is a heat exchanger model in the tube bank region, while the upper and lower plena are modeled as two heat exchangers with a single heat transfer tube. In all three heat exchangers, the same empirical correlation is used in the heat transfer calculation on the tube and the shell sides. The Nusselt number, as a function of the Péclet number, calculated from measured temperature and flow rate data in a 50 MW experimental facility was correctly reproduced by the calculation result, when the calculated result is processed in the same way as the experiment. Finally, it is clarified that the deviation is a superficial phenomenon which is caused by the heat transfer in the plena of the heat exchanger. (author)

  2. RIBBED DOUBLE PIPE HEAT EXCHANGER: ANALYTICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    HUSSAIN H. AL-KAYIEM

    2011-02-01

    Full Text Available This paper presents the findings obtained by modeling a Double Pipe Heat Exchanger (DPHE equipped with repeated ribs from the inside for artificial roughing. An analytical procedure was developed to analyze the thermal and hydraulic performance of the DPHE with and without ribbing. The procedure was verified by comparing with experimental reported results and they are in good agreement. Several parameters were investigated in this study including the effect of ribs pitch to height ratios, P/e= 5, 10, 15, and 20, and ribs to hydraulic diameter ratios, e/Dh= 0.0595, 0.0765, and 0.107. These parameters were studied at various operating Reynolds number ranging from 2500 to 150000. Different installation configurations were investigated, too. An enhan-cement of 4 times in the heat transfer in terms of Stanton number was achieved at the expense of 38 times increase of pressure drop across the flow in terms of friction facto values.

  3. Microbial fouling control in heat exchangers

    International Nuclear Information System (INIS)

    McCoy, W.F.

    1991-01-01

    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

  4. Heat exchanger tube inspection using ultrasonic arrays

    International Nuclear Information System (INIS)

    Meyer, P.A.; Carodiskey, T.J.

    1986-01-01

    Tubing used in industrial heat exchangers is often subject to failure caused by corrosion and cracking. Technical conferences are used as a forum in the steam generator industry to ensure that the failure mechanisms are well understood and that the quality of the heat exchanger is maintained. The quality of a heat exchanger can be thought of as its ability to operate to design specifications over its intended life. This is the motivation to inspect and evaluate these devices periodically. Inspection, however, normally requires shutdown of the heat exchanger which is costly but is much more acceptable than an unscheduled shutdown due to failure of a tube. Therefore, the degree of inspection is established by balancing the cost of inspection with the risk of a tube failure. Any method of reducing the cost of inspection will permit a higher degree of inspection and, therefore, improve heat exchanger quality. This paper reviews the design and performance of an improved method of ultrasonic inspection of heat exchanger tubing with emphasis on applications in the nuclear industry

  5. Heat pipe heat exchanger and its potential to energy recovery in the tropics

    Directory of Open Access Journals (Sweden)

    Yau Yat H.

    2015-01-01

    Full Text Available The heat recovery by the heat pipe heat exchangers was studied in the tropics. Heat pipe heat exchangers with two, four, six, and eight numbers of rows were examined for this purpose. The coil face velocity was set at 2 m/s and the temperature of return air was kept at 24°C in this study. The performance of the heat pipe heat exchangers was recorded during the one week of operation (168 hours to examine the performance data. Then, the collected data from the one week of operation were used to estimate the amount of energy recovered by the heat pipe heat exchangers annually. The effect of the inside design temperature and the coil face velocity on the energy recovery for a typical heat pipe heat exchanger was also investigated. In addition, heat pipe heat exchangers were simulated based on the effectiveness-NTU method, and their theoretical values for the thermal performance were compared with the experimental results.

  6. Analysis of the Technological Parameters of the Heat Exchanger in the Heating Pipe

    Directory of Open Access Journals (Sweden)

    Knyazev Vladimir

    2017-01-01

    Full Text Available The main purpose of this article is to analyze the selecting of technological parameters for the heat exchanger to improve the heat transfer and reduce the noise during operation in the heating pipe, which is used in the different systems of the planes and helicopters. In result of this study, the best technical parameters are found, considering different variations of deformation cutting heat exchanger pipes.

  7. Computer aided heat transfer analysis in a laboratory scaled heat exchanger unit

    International Nuclear Information System (INIS)

    Gunes, M.

    1998-01-01

    In this study. an explanation of a laboratory scaled heat exchanger unit and a software which is developed to analyze heat transfer. especially to use it in heat transfer courses, are represented. Analyses carried out in the software through sample values measured in the heat exchanger are: (l) Determination of heat transfer rate, logarithmic mean temperature difference and overall heat transfer coefficient; (2)Determination of convection heat transfer coefficient inside and outside the tube and the effect of fluid velocity on these; (3)Investigation of the relationship between Nusselt Number. Reynolds Number and Prandtl Number by using multiple non-linear regression analysis. Results are displayed on the screen graphically

  8. Heat transfer, condensation and fog formation in crossflow plastic heat exchangers

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    1996-01-01

    In this paper heat transfer of air-water-vapour mixtures in plastic crossflow heat exchangers is studied theoretically and experimentally. First, a model for heat transfer without condensation is derived, resulting in a set of classical differential equations. Subsequently, heat transfer with wall

  9. Heat transfer characteristics of a helical heat exchanger

    International Nuclear Information System (INIS)

    San, Jung-Yang; Hsu, Chih-Hsiang; Chen, Shih-Hao

    2012-01-01

    Heat transfer performance of a helical heat exchanger was investigated. The heat exchanger is composed of a helical tube with rectangular cross section and two cover plates. The ε–Ntu relation of the heat exchanger was obtained using a numerical method. In the analysis, the flow in the tube (helical flow) was considered to be mixed and the flow outside the tube (radial flow) was unmixed. In the experiment, the Darcy friction factor (f) and convective heat transfer coefficient (h) of the radial flow were measured. The radial flow was air and the helical flow was water. Four different channel spacing (0.5, 0.8, 1.2 and 1.6 mm) were individually considered. The Reynolds numbers were in the range 307–2547. Two correlations, one for the Darcy friction factor and the other for the Nusselt number, were proposed. - Highlights: ► We analyze the heat transfer characteristics of a helical heat exchanger and examine the effectiveness–Ntu relation. ► Increasing number of turns of the heat exchanger would slightly increase the effectiveness. ► There is an optimum Ntu value corresponding to a maximum effectiveness. ► We measure the Darcy friction factor and Nusselt number of the radial flow and examine the correlations.

  10. Performance analysis of short helical borehole heat exchangers via integrated modelling of a borefield and a heat pump: A case study

    International Nuclear Information System (INIS)

    Zarrella, Angelo; Capozza, Antonio; De Carli, Michele

    2013-01-01

    This paper presents a new simulation tool package that calculates the energy efficiency of an entire Ground Source Heat Pump (GSHP) system. The package consists of two detailed models of borehole heat exchangers and heat pump equipment coupled in a single well-integrated calculation tool. It was used to analyze two types of ground heat exchangers in the same operating conditions for two Italian climates. Research focused on comparing a short helical-shaped pipe configuration with the more widespread and longer double U-tube. Analysis was carried out at the same energy exchange rate with the ground and addressed the difference in total borehole depth. The package also took into account the effects of the weather on the heat transfer between the heat exchanger and the surrounding ground. Analysis found that a much shorter total borehole depth was needed for the helical-shaped pipe, which consequently reduces installation costs. Therefore, this configuration may be a suitable alternative to conventional U-shaped tubes, especially for new residential housing with low energy loads and where deep probe drilling is not possible. Finally, this paper also investigates the influence of the axial effects in the ground on the seasonal energy efficiency of the whole system. -- Highlights: • A new model to evaluate the efficiency of the whole GSHP system is presented. • The model considers the interaction between the ground and the environment. • Two types of vertical ground heat exchangers are analyzed: helix and 2U-tube. • They are analyzed in the same operating conditions for two Italian climates. • With helical shaped pipe a shorter total borehole depth is required

  11. Improvements in or relating to heat exchangers

    International Nuclear Information System (INIS)

    Taylor, P.A.

    1978-01-01

    According to the present invention there is provided a method of producing superheated steam by use of the heat in liquid sodium, in which liquid sodium is caused to flow through a space having boundaries of which no part is common with the boundaries of a space in which vapour is produced, a fluid that is inert to sodium is heated by heat exchange at the boundaries of the space through which the liquid sodium flows and serves as the heating medium for the production of vapour, and the vapour is subsequently heated to the final degree of superheat by heat exchange with liquid sodium in a space that has a common boundary with a space through which liquid sodium is passed. (U.K.)

  12. Physical explosion analysis in heat exchanger network design

    Science.gov (United States)

    Pasha, M.; Zaini, D.; Shariff, A. M.

    2016-06-01

    The failure of shell and tube heat exchangers is being extensively experienced by the chemical process industries. This failure can create a loss of production for long time duration. Moreover, loss of containment through heat exchanger could potentially lead to a credible event such as fire, explosion and toxic release. There is a need to analyse the possible worst case effect originated from the loss of containment of the heat exchanger at the early design stage. Physical explosion analysis during the heat exchanger network design is presented in this work. Baker and Prugh explosion models are deployed for assessing the explosion effect. Microsoft Excel integrated with process design simulator through object linking and embedded (OLE) automation for this analysis. Aspen HYSYS V (8.0) used as a simulation platform in this work. A typical heat exchanger network of steam reforming and shift conversion process was presented as a case study. It is investigated from this analysis that overpressure generated from the physical explosion of each heat exchanger can be estimated in a more precise manner by using Prugh model. The present work could potentially assist the design engineer to identify the critical heat exchanger in the network at the preliminary design stage.

  13. Phase Change Material Heat Exchanger Life Test

    Science.gov (United States)

    Lillibridge, Sean; Stephan, Ryan

    2009-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The IR environment of the space craft varies drastically from the light side to the dark side of the moon. The result is a situation where a radiator sized for the maximal heat load in the most adverse situation is subject to freezing on the dark side of the orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor," storing thermal energy when there is too much being produced by the space craft to reject to space, and then feeding that energy back into the thermal loop when conditions are more favorable. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration LLO missions. In order to validate the performance of PCM Heat Exchangers, a life test is being conducted on four n-Pentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 melt-freeze cycles will be performed.

  14. Damping of multispan heat exchanger tubes. Pt. 1: in gases

    International Nuclear Information System (INIS)

    Pettigrew, M.J.; Goyder, H.G.D.; Qiao, Z.L.; Axisa, F.

    1986-07-01

    Flow-induced vibration analyses of heat exchanger tubes require the knowledge of damping. This paper treats the question of damping on multispan heat exchanger tubes in air and gases. The different energy dissipation mechanisms that contribute to tube damping are discussed. The available experimental data are reviewed and analysed. We find that the main damping mechanism in gases is friction between tube and tube-supports. Damping is strongly related to tube-support thickness. Damping values are recommended for design purposes. This study is interesting in the nuclear industry for it often uses heat exchangers

  15. Numerical Study of Solidification in a Plate Heat Exchange Device with a Zigzag Configuration Containing Multiple Phase-Change-Materials

    Directory of Open Access Journals (Sweden)

    Peilun Wang

    2016-05-01

    Full Text Available Latent heat thermal energy storage (TES plays an important role in the advocation of TES in contrast to sensible energy storage because of the large storage energy densities per unit mass/volume possible at a nearly constant thermal energy. In the current study, a heat exchange device with a zigzag configuration containing multiple phase-change-materials (m-PCMs was considered, and an experimental system was built to validate the model for a single PCM. A two-dimensional numerical model was developed using the ANSYS Fluent 14.0 software program. The energy fractions method was put forward to calculate the average Ste number and the influence of Re and Ste numbers on the discharge process were studied. The influence of phase change temperature among m-PCMs on the solidification process has also been studied. A new boundary condition was defined to determine the combined effect of the Re and Ste numbers on the discharging process. The modelling results show that for a given input power, the Ste (or Re number has a significant impact on the discharging process; however, the period value of inlet velocity has almost no impact on it. Besides, the zigzag plate with m-PCMs has a good impact on the temperature shock as “filter action” in the discharging process.

  16. Improvements in or relating to heat exchangers

    International Nuclear Information System (INIS)

    Graham, L.W.; Sturge, D.W.J.; Ridealgh, F.

    1978-01-01

    A heat exchanger is described that is suitable for use with high temperature gas cooled reactors in which the heat is used as process heat. The construction which is of necessity of large size, is of much lighter weight than current constructions and is better able to withstand the high operating temperature (up to about 1000 0 C). Carbon fibre reinforced carbon materials are employed as constructional materials. A method of fabrication is described. The heat exchanger comprises a tube or bundle of tubes associated with a header plate, and the tube can be of helical form. The carbon materials may be formed by carbonisation of a thermosetting plastic such as a phenolic resin. The exchanger is rendered substantially impermeable to gas by an infiltration treatment of the carbon material using a cracked hydrocarbon gas. (U.K.)

  17. The dry heat exchanger calorimeter system

    International Nuclear Information System (INIS)

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

    1991-01-01

    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

  18. Improvements in or relating to heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Graham, L W; Sturge, D W.J.; Ridealgh, F

    1978-04-05

    A heat exchanger is described that is suitable for use with high temperature gas cooled reactors in which the heat is used as process heat. The construction which is of necessity of large size, is of much lighter weight than current constructions and is better able to withstand the high operating temperature (up to about 1000/sup 0/C). Carbon fibre reinforced carbon materials are employed as constructional materials. A method of fabrication is described. The heat exchanger comprises a tube or bundle of tubes associated with a header plate, and the tube can be of helical form. The carbon materials may be formed by carbonisation of a thermosetting plastic such as a phenolic resin. The exchanger is rendered substantially impermeable to gas by an infiltration treatment of the carbon material using a cracked hydrocarbon gas.

  19. Design of common heat exchanger network for batch processes

    International Nuclear Information System (INIS)

    Anastasovski, Aleksandar

    2014-01-01

    Heat integration of energy streams is very important for the efficient energy recovery in production systems. Pinch technology is a very useful tool for heat integration and maximizing energy efficiency. Creating of heat exchangers network as a common solution for systems in batch mode that will be applicable in all existing time slices is very difficult. This paper suggests a new methodology for design of common heat exchanger network for batch processes. Heat exchanger network designs were created for all determined repeatable and non-repeatable time periods – time slices. They are the basis for creating the common heat exchanger network. The common heat exchanger network as solution, satisfies all heat-transfer needs for each time period and for every existing combination of selected streams in the production process. This methodology use split of some heat exchangers into two or more heat exchange units or heat exchange zones. The reason for that is the multipurpose use of heat exchangers between different pairs of streams in different time periods. Splitting of large heat exchangers would maximize the total heat transfer usage of heat exchange units. Final solution contains heat exchangers with the minimum heat load as well as the minimum need of heat transfer area. The solution is applicable for all determined time periods and all existing stream combinations. - Highlights: •Methodology for design of energy efficient systems in batch processes. •Common Heat Exchanger Network solution based on designs with Pinch technology. •Multipurpose use of heat exchangers in batch processes

  20. Secondary heat exchanger design and comparison for advanced high temperature reactor

    International Nuclear Information System (INIS)

    Sabharwall, P.; Kim, E. S.; Siahpush, A.; McKellar, M.; Patterson, M.

    2012-01-01

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

  1. Sustainability assessment of heat exchanger units for spray dryers

    International Nuclear Information System (INIS)

    Caglayan, Hasan; Caliskan, Hakan

    2017-01-01

    In this study, the sustainability assessment is performed to the system known as heat exchanger unit with spray dryer. The five-different dead state temperatures (0-5-10-15-20 °C) are considered. It is found that the heat exchanger has the highest energy efficiency (63.32%), while the overall system has the lowest one (5.56%). So, the combination of the spray dryer with the heat exchanger is more effective. On the other hand, the overall exergy efficiency of the system is lower than the heat exchanger and spray dryer for all of the dead state (environmental) temperatures. The exergy efficiency of the heat exchanger is inversely proportional to the dead state temperature, and the maximum rate is found as 49.65% at 0 °C. Furthermore, the exergy efficiencies of the spray dryer and overall system are directly proportional to the dead state temperatures, and the corresponding maximum rates are found to be 26.41% and 24.32% at 20 °C, respectively. Also, the exergy destruction is directly proportional to the dead state temperatures. The minimum and maximum exergy destruction rates are found at the dead state temperatures of 0 °C and 20 °C, respectively. Furthermore, the most sustainable system is found as the heat exchanger unit. - Highlights: • Thermodynamic analyses of industrial heat exchangers and spray dryers. • Sustainability of heat exchangers for spray dryers. • Dead state temperature effects on exergy efficiencies of heat exchangers and spray dryers.

  2. Experimental and Numerical Comparison of Two Borehole Heat Exchangers

    DEFF Research Database (Denmark)

    Alberdi Pagola, Maria; Poulsen, Søren Erbs

    2014-01-01

    This report outlines key results from a comparative study of two different pipe borehole heat exchanger (BHE) configurations. The work was carried out by VIA University College and in collaboration with GM Plast A/S.......This report outlines key results from a comparative study of two different pipe borehole heat exchanger (BHE) configurations. The work was carried out by VIA University College and in collaboration with GM Plast A/S....

  3. Process Heat Exchanger Options for the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  4. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    International Nuclear Information System (INIS)

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

    2011-01-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  5. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  6. Heat exchanger selection and design analyses for metal hydride heat pump systems

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Voskuilen, Tyler G.; Waters, Essene L.

    2016-01-01

    This study presents a design analysis for the development of highly efficient heat exchangers within stationary metal hydride heat pumps. The design constraints and selected performance criteria are applied to three representative heat exchangers. The proposed thermal model can be applied to select...... the most efficient heat exchanger design and provides outcomes generally valid in a pre-design stage. Heat transfer effectiveness is the principal performance parameter guiding the selection analysis, the results of which appear to be mildly (up to 13%) affected by the specific Nusselt correlation used....... The thermo-physical properties of the heat transfer medium and geometrical parameters are varied in the sensitivity analysis, suggesting that the length of independent tubes is the physical parameter that influences the performance of the heat exchangers the most. The practical operative regions for each...

  7. Multiphysics Numerical Modeling of a Fin and Tube Heat Exchanger

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2015-01-01

    In the present research work, a modeling effort to predict the performance of a liquid-gas type fin and tube heat exchanger design is made. Three dimensional (3D) steady state numerical model is developed using commercial software COMSOL Multiphysics based on finite element method (FEM......). For the purposes here, only gas flowing over the fin side is simulated assuming constant inner tube wall temperature. The study couples conjugate heat transfer mechanism with turbulent flow in order to describe the temperature and velocity profile. In addition, performance characteristics of the heat exchanger...... design in terms of heat transfer and pressure loss are determined by parameters such as overall heat transfer coefficient, Colburn j-factor, flow resistance factor, and efficiency index. The model provides useful insights necessary for optimization of heat exchanger design....

  8. Research of the heat exchanging processes running in the heating and hot water supply loops of the coil heat exchangers

    Directory of Open Access Journals (Sweden)

    Ірина Геннадіївна Шитікова

    2016-11-01

    Full Text Available The fuel-energy complex research has made it possible to disclose a huge power-saving potential in the municipal heat-and-power engineering. Power-and-resource-saving units and systems are becoming extremely urgent because of the power engineering crisis expansion. The self-adjusting heat supply system from the individual heating points with the heat-accumulating units and coil heat exchangers for independent heating and water supply systems has been examined. Coil heat exchangers are used in municipal heating for heat transfer (e.g. geothermal waters for the independent mains of the heating and hot water supply systems. The heat engineering calculation of the heating and accumulating unit with the coil heat exchanger for independent heat supply systems from individual heater was performed and experimental data were received at the experimental industrial unit under the laboratory conditions. The peculiarities of the flows in the intertubular space, their influence on the heat exchange and temperatures of the first and intermediate mains have been shown. It is important to know the processes running inside the apparatus to be able to improve the technical characteristics of the three-loop coil heat exchanger. The task solution will make it possible to save the materials consumption for the three-loop coil heat exchangers in the future

  9. Numerical study of an innovative design of a finned double-pipe heat exchanger with variable fin-tip thickness

    International Nuclear Information System (INIS)

    Syed, K.S.; Ishaq, Muhammad; Iqbal, Zafar; Hassan, Ahmad

    2015-01-01

    Highlights: • Variable fin tip angle significantly effect the velocity and temperature distribution. • Significant gain in the thermal performance with decrease in the friction factor. • Variable fin tip angle must be considered an important parameter in designing finned annulus. - Abstract: The analysis of fully developed laminar convective heat transfer in an innovate design of a finned double-pipe heat exchanger (DPHE) with longitudinal fins of variable thickness of the tip subjected to the constant heat transfer rate boundary conditions is investigated here. The tip thickness is controlled by the ratio of tip to base angles as a parameter whose values varying from 0 to 1 correspond to the fin shapes varying from the triangular to the rectangular cross-section. Upto the knowledge of the authors, this parameter is being introduced for the first time in the literature. Discontinuous Galerkin finite element method (DG-FEM) has been employed in the present work. The overall performance of the proposed DPHE has been investigated by considering the friction factor, the Nusselt number and the j-factor. Upto 178% gain in the Nusselt number and 89% gain in the j-factor have been achieved relative to the rectangular cross-section. Such gains relative to the triangular cross-section are respectively 9.5% and 19%. The results indicate that the newly introduced parameter the ratio of tip to base angles has proved to play significant role in the design of a double-pipe heat exchanger in reducing the cost, weight and frictional loss, in improving the heat transfer rate and making the exchanger energy-efficient. Therefore, it must be considered as an important design parameter for heat exchanger design

  10. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Science.gov (United States)

    2010-04-01

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

  11. Derivation of effectiveness-NTU method for heat exchangers with heat leak; TOPICAL

    International Nuclear Information System (INIS)

    William M. Soyars

    2001-01-01

    A powerful and useful method for heat exchanger analysis is the effectiveness-NTU method. The equations for this technique presented in textbooks, however, are limited to the case where all of the heat transfer occurs between the two fluid streams. In an application of interest to us, cryogenic heat exchangers, we wish to consider a heat leak term. Thus, we have derived equations for the(var e psilon)-NTU method with heat leak involved. The cases to be studied include evaporators, condensers, and counter-flow, with heat leak both in and out

  12. Comparison between conventional heat exchanger performance and an heat pipes exchanger

    International Nuclear Information System (INIS)

    Souza, J.R.G. de; Rocha, N.R.

    1989-01-01

    The thermal performance of conventional compact heat exchanger and of exchanger with heat pipes are simulated using a digital computer, for equal volumes and the same process conditions. The comparative analysis is depicted in graphs that indicate which of the situations each equipment is more efficient. (author)

  13. Modeling and parametric studies for thermal performance of an earth to air heat exchanger integrated with a greenhouse

    International Nuclear Information System (INIS)

    Ghosal, M.K.; Tiwari, G.N.

    2006-01-01

    A thermal model has been developed to investigate the potential of using the stored thermal energy of the ground for greenhouse heating and cooling with the help of an earth to air heat exchanger (EAHE) system integrated with the greenhouse located in the premises of IIT, Delhi, India. Experiments were conducted extensively throughout the year 2003, but the developed model was validated against typical clear and sunny days experiments. Parametric studies performed for the EAHE coupled with the greenhouse illustrate the effects of buried pipe length, pipe diameter, mass flow rate of air, depth of ground and types of soil on the greenhouse air temperatures. The temperatures of the greenhouse air, with the experimental parameters of the EAHE, were found to be, on average 7-8 deg. C higher in the winter and 5-6 deg. C lower in the summer than those of the same greenhouse without the EAHE. The greenhouse air temperatures increase in the winter and decrease in the summer with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing air inside buried pipe and increasing depth of ground up to 4 m. The predicted and measured values of the greenhouse air temperatures that were verified, in terms of root mean square percent deviation and correlation coefficient, exhibited fair agreement

  14. Experimental study of the structure of vapor phase during boiling of R134a on heat exchange surfaces of heat pump

    Science.gov (United States)

    Ustinov, D. A.; Sukhikh, A. A.; Sidenkov, D. V.; Ustinov, V. A.

    2017-10-01

    The heat supply by means of heat pumps is considered now as a rational method of local heating which can lead to economy of primary fuel. At use of low-potential heat, for example, the heat of a ground (5 … 18 °C) or ground waters (8 … 10°C) only small depressing of temperature of these sources (on 3 … 5°C) is possible that demands application of heat exchangers with intensified heatmass transfer surfaces. In thermal laboratory of TOT department the 200 W experimental installation has been developed for research of process of boiling of freon R134a. The principle of action of the installation consists in realisation of reverse thermodynamic cycle and consecutive natural measurement of characteristics of elements of surfaces of heat exchangers of real installations at boiling points of freon from-10°C to +10°C and condensing temperatures from 15°C to 50 °C. The evaporator casing has optical windows for control of process of boiling of freon on ribbed on technology of distorting cut tubes. Temperature measurement in characteristic points of a cycle is provided by copper-constantan thermocouples which by means of ADT are connected to the computer that allows treat results of measurements in a real time mode. The structure of a two-phase flow investigated by means of the optical procedure based on laser technique.

  15. Complex use of heat-exchange tunnels

    Directory of Open Access Journals (Sweden)

    А. Ф. Галкин

    2017-04-01

    Full Text Available The paper presents separate results of complex research (experimental and theoretical on the application of heat-exchange tunnels – in frozen rocks, among other things – as underground constructions serving two purposes. It is proposed to use heat-exchange tunnels as a separate multi-functional module, which under normal conditions will be used to set standards of heat regime parameters in the mines, and in emergency situations, natural or man-made, will serve as a protective structure to shelter mine workers. Heat-exchange modules can be made from mined-out or specially constructed tunnels. Economic analysis shows that the use of such multi-functional modules does not increase operation and maintenance costs, but enhances safety of mining operations and reliability in case of emergency situations. There are numerous theoretic and experimental investigations in the field of complex use of mining tunnels, which allows to develop regulatory design documents on their basis. Experience of practical application of heat-exchange tunnels has been assessed from the position of regulating heat regime in the mines.

  16. Investigation and optimization of the depth of flue gas heat recovery in surface heat exchangers

    Science.gov (United States)

    Bespalov, V. V.; Bespalov, V. I.; Melnikov, D. V.

    2017-09-01

    Economic issues associated with designing deep flue gas heat recovery units for natural gas-fired boilers are examined. The governing parameter affecting the performance and cost of surface-type condensing heat recovery heat exchangers is the heat transfer surface area. When firing natural gas, the heat recovery depth depends on the flue gas temperature at the condenser outlet and determines the amount of condensed water vapor. The effect of the outlet flue gas temperature in a heat recovery heat exchanger on the additionally recovered heat power is studied. A correlation has been derived enabling one to determine the best heat recovery depth (or the final cooling temperature) maximizing the anticipated reduced annual profit of a power enterprise from implementation of energy-saving measures. Results of optimization are presented for a surface-type condensing gas-air plate heat recovery heat exchanger for the climatic conditions and the economic situation in Tomsk. The predictions demonstrate that it is economically feasible to design similar heat recovery heat exchangers for a flue gas outlet temperature of 10°C. In this case, the payback period for the investment in the heat recovery heat exchanger will be 1.5 years. The effect of various factors on the optimal outlet flue gas temperature was analyzed. Most climatic, economical, or technological factors have a minor effect on the best outlet temperature, which remains between 5 and 20°C when varying the affecting factors. The derived correlation enables us to preliminary estimate the outlet (final) flue gas temperature that should be used in designing the heat transfer surface of a heat recovery heat exchanger for a gas-fired boiler as applied to the specific climatic conditions.

  17. A heat exchanger provided with plates

    International Nuclear Information System (INIS)

    Chaix, J.E.; Fajeau, Maurice; Chlique, Bernard.

    1976-01-01

    The invention relates to a heat exchanger of the plate type, in which two fluids exchange calories through parallel metal plates, delimiting spaces separated from each other in which two fluids respectively flow without direct contact between them. The invention particularly applies in the case where one of the two fluids is water under pressure or else a circulating liquid metal, specially sodium, used in the system of a pressurised water or fast neutron reactor, the second fluid being water to be vaporised in the exchanger by the calories supplied by the first fluid. The arrangement is designed to give minimum bulk, particularly enabling the exchanger to be housed in the area between the core of a nuclear reactor and a casing or outer vessel, or else in an external sealed containment, with a view to recovering with the best efficiency the heat acquired by a coolant flowing through the core [fr

  18. Diffusion bonding in compact heat exchangers

    International Nuclear Information System (INIS)

    Southall, David

    2009-01-01

    Heatric's diffusion bonding process is a solid-state joining technology that produces strong, compact, all-metal heat exchanger cores. Diffusion bonding allows for a large quantity of joints to be made in geometries that would normally be inaccessible for conventional welding techniques. Since Heatric's diffusion bonding process uses no interlayer or braze alloy, the resulting heat exchanger core has consistent chemistry throughout and, under carefully controlled conditions, a return to parent metal strength can be reached. This paper will provide an overview of the diffusion bonding process and its origins, and also its application to compact heat exchanger construction. The paper will then discuss recent work that has been done to compare mechanical properties of Heatric's diffusion bonded material with material that has been conventionally welded, as well as with material tested in the as-received condition. (author)

  19. Heat exchanger for coal gasification process

    Science.gov (United States)

    Blasiole, George A.

    1984-06-19

    This invention provides a heat exchanger, particularly useful for systems requiring cooling of hot particulate solids, such as the separated fines from the product gas of a carbonaceous material gasification system. The invention allows effective cooling of a hot particulate in a particle stream (made up of hot particulate and a gas), using gravity as the motive source of the hot particulate. In a preferred form, the invention substitutes a tube structure for the single wall tube of a heat exchanger. The tube structure comprises a tube with a core disposed within, forming a cavity between the tube and the core, and vanes in the cavity which form a flow path through which the hot particulate falls. The outside of the tube is in contact with the cooling fluid of the heat exchanger.

  20. An experimental study on single phase convection heat transfer and pressure drop in two brazed plate heat exchangers with different chevron shapes and hydraulic diameters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Man Bae; Park, Chang Yong [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2017-05-15

    An experimental study on heat transfer and pressure drop characteristics was performed at single phase flow in two Brazed plate heat exchangers (BPHEs) with different geometries. The corrugation density of one of the BPHE (Type II) was two times as high as that of the other BPHE (Type I). The hydraulic diameter of the type II BPHE was 2.13 mm, which was 38 % smaller than that of the type I BPHE. Also, the cross section shape of the flow channels for the type II BPHE was different from that for conventional BPHEs due to the unusual corrugation patterns and brazing points. The experimental conditions for temperatures were varied from 4.6 °C to 49.1 °C, and for mass flow rates were changed from 0.07 kg/s to 1.24 kg/s. The measured results showed that pressure drop in the type II BPHE was about 110 % higher than that in the type I BPHE. Nu of the type II was higher than that of the type I BPHE and the enhancement became larger with the increase of Re at the ranges above 800. New correlations for fF and Nu were proposed by this study and their prediction accuracy could be improved by considering the surface enlargement factor in the correlations. The performance evaluation of the two BPHEs was performed by (j/f{sub F}1{sup /3}) which represented the ratio of heat transfer and pressure drop performance. Also, a new parameter, the capacity compactness of PHE, was proposed and it presented the PHE capacity per unit volume and unit log mean temperature difference. The comparison showed that the two BPHEs had similar values of the (j/f{sub F}1{sup /3}), whereas they had significantly different values of the capacity compactness. The capacity compactness of the type II BPHE was 1.5 times higher than that for the type I BPHE.

  1. An experimental study on single phase convection heat transfer and pressure drop in two brazed plate heat exchangers with different chevron shapes and hydraulic diameters

    International Nuclear Information System (INIS)

    Kim, Man Bae; Park, Chang Yong

    2017-01-01

    An experimental study on heat transfer and pressure drop characteristics was performed at single phase flow in two Brazed plate heat exchangers (BPHEs) with different geometries. The corrugation density of one of the BPHE (Type II) was two times as high as that of the other BPHE (Type I). The hydraulic diameter of the type II BPHE was 2.13 mm, which was 38 % smaller than that of the type I BPHE. Also, the cross section shape of the flow channels for the type II BPHE was different from that for conventional BPHEs due to the unusual corrugation patterns and brazing points. The experimental conditions for temperatures were varied from 4.6 °C to 49.1 °C, and for mass flow rates were changed from 0.07 kg/s to 1.24 kg/s. The measured results showed that pressure drop in the type II BPHE was about 110 % higher than that in the type I BPHE. Nu of the type II was higher than that of the type I BPHE and the enhancement became larger with the increase of Re at the ranges above 800. New correlations for fF and Nu were proposed by this study and their prediction accuracy could be improved by considering the surface enlargement factor in the correlations. The performance evaluation of the two BPHEs was performed by (j/f F 1 /3 ) which represented the ratio of heat transfer and pressure drop performance. Also, a new parameter, the capacity compactness of PHE, was proposed and it presented the PHE capacity per unit volume and unit log mean temperature difference. The comparison showed that the two BPHEs had similar values of the (j/f F 1 /3 ), whereas they had significantly different values of the capacity compactness. The capacity compactness of the type II BPHE was 1.5 times higher than that for the type I BPHE.

  2. The radioactive inventory of a Berkeley heat exchanger

    International Nuclear Information System (INIS)

    Hancock, R.

    1988-10-01

    The Central Electricity Generating Board has announced a date for the final shutdown of the first of the Magnox power stations at Berkeley (March 1989), and is in the process of preparing Pre-Decommissioning Safety Reports (PDSR) for the decommissioning of Berkeley and Bradwell. This report supports these PDSR studies and reports work carried out within the Research Division at Berkeley Nuclear Laboratories on the radioactive inventories of the heat exchangers at Berkeley Power Station. At Berkeley, the heat exchangers will be included in stage two decommissioning to which they will contribute the largest mass of contaminated material. The purpose of this report is to bring together all of the available data on the contamination in the heat exchangers at Berkeley Power Station, and to recommend a database from which the options for disposal of the heat exchangers may be formulated. (author)

  3. Heat exchangers and recuperators for high temperature waste gases

    Science.gov (United States)

    Meunier, H.

    General considerations on high temperature waste heat recovery are presented. Internal heat recovery through combustion air preheating and external heat recovery are addressed. Heat transfer and pressure drop in heat exchanger design are discussed.

  4. Plate heat exchanger - inertia flywheel performance in loss of flow transient

    International Nuclear Information System (INIS)

    Abou-El-Maaty, Talal; Abd-El-Hady, Amr

    2009-01-01

    One of the most versatile types of heat exchangers used is the plate heat exchanger. It has principal advantages over other heat exchangers in that plates can be added and/or removed easily in order to change the area available for heat transfer and therefore its overall performance. The cooling systems of Egypt's second research reactor (ETRR 2) use this type of heat exchanger for cooling purposes in its primary core cooling and pool cooling systems. In addition to the change in the number of heat exchanger cooling channels, the effect of changing the amount of mass flow rate on the heat exchanger performance is an important issues in this study. The inertia flywheel mounted on the primary core cooling system pump with the plate heat exchanger plays an important role in the case of loss of flow transients. The PARET code is used to simulate the effect of loss of flow transients on the reactor core. Hence, the core outlet temperature with the pump-flywheel flow coast down is fed into the plate heat exchanger model developed to estimate the total energy transferred to the cooling tower, the primary side heat exchanger temperature variation, the transmitted heat exchanger power, and the heat exchanger effectiveness. In addition, the pressure drop in both, the primary side and secondary side of the plate heat exchanger is calculated in all simulated transients because their values have limits beyond which the heat exchanger is useless. (orig.)

  5. Experimental study of heat exchange coefficients, critical heat flux and charge losses, using water-steam mixtures in turbulent flow in a vertical tube

    International Nuclear Information System (INIS)

    Perroud, P.; De La Harpe, A.; Rebiere, J.

    1960-12-01

    Two stainless steel tubes were used (with diameters of 5 and 10 mm, lengths 400 and 600 mm respectively), heated electrically (50 Hz). The mixture flows from top to bottom. The work was carried out mainly on mixtures of high concentration (x > 0.1), at pressures between 50 and 60 kg/cm 2 , flowing as a liquid film on the walls of the tube with droplets suspended in the central current of steam. By analysis of the heat transfer laws the exchange mechanisms were established, and the conditions under which the critical heat flux may be exceeded without danger of actual burnout were determined. In this way high output concentrations (x s > 0.9) may be obtained. An attempt has been made to find out to what extent existing correlation formulae can be used to account for the phenomena observed. It is shown that those dealing with exchange coefficients can only be applied in a first approximation in cases where exchange by convection is preponderant, and only below the critical flux. The formulae proposed by WAPD and CISE do not give a satisfactory estimation of the critical heat flux, and the essential reasons for this inadequacy are explained. Lastly, the Martinelli and Nelson method may be used to an approximation of 30 per cent for the calculation of charge losses. (author) [fr

  6. Heat exchanger design for desalination plants

    International Nuclear Information System (INIS)

    1979-03-01

    The Office of Saline Water (OSW) accomplished a very large amount of significant work related to the design and performance of large heat exchanger bundles and enhanced heat transfer surfaces. This work was undertaken to provide basic technical and economic data for the design of distillation plants for the desalination of seawater, and should be of value to other industrial applications as well. The OSW work covers almost every aspect of heat exchanger design, and ranges academic research to data gathering on commercial desalting plants. Exchanger design configurations include multistage flash plant condensers, vertical tube falling film and upflow evaporators, and horizontal tube spray film evaporators. Unfortunately, the data is scattered through a large number of reports of which many are concerned primarily with factors other than heat transfer, and the quality of reporting and the quality of the data are far from consistent. This report catalogues and organizes the heat exchanger data developed by the OSW. Some analysis as to the validity of the data is made and ranges of performance that can be expected are given. Emphasis is placed on the vertical tube, falling film evaporators. A thorough analysis of the large literature file that was surveyed was not possible. No analysis was made of the quality of original data, but apparent data discrepancies are pointed out where such discrepancies happen to be found

  7. Micro-Scale Regenerative Heat Exchanger

    Science.gov (United States)

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

    2004-01-01

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

  8. Heat exchanges in a quenched ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Corberi, Federico; Zannetti, Marco [Dipartimento di Fisica ' E.R. Caianiello' , and CNISM, Unita di Salerno, Universita di Salerno, via Ponte don Melillo, I-84084 Fisciano, SA (Italy); Gonnella, Giuseppe; Piscitelli, Antonio [Dipartimento di Fisica, Universita di Bari and INFN, Sezione di Bari, via Amendola 173, I-70126 Bari (Italy)

    2013-02-01

    The off-equilibrium probability distribution of the heat exchanged by a ferromagnet in a time interval after a quench below the critical point is calculated analytically in the large-N limit. The distribution is characterized by a singular threshold Q{sub C} < 0, below which a macroscopic fraction of heat is released by the k = 0 Fourier component of the order parameter. The mathematical structure producing this phenomenon is the same responsible for the order parameter condensation in the equilibrium low temperature phase. The heat exchanged by the individual Fourier modes follows a non-trivial pattern, with the unstable modes at small wave vectors warming up the modes around a characteristic finite wave vector k{sub M}. Two internal temperatures, associated with the k = 0 and k = k{sub M} modes, rule the heat currents through a fluctuation relation similar to the one for stationary systems in contact with two thermal reservoirs. (fast track communication)

  9. Study of coupled heat and water transfer in proton exchange membrane fuel cells by the way of internal measurements

    International Nuclear Information System (INIS)

    Thomas, A; Maranzana, G; Didierjean, S; Dillet, J; Lottin, O

    2012-01-01

    Measurements of electrode temperatures within a proton exchange membrane fuel cell were performed using platinum wires. A temperature difference of 7°C between the electrodes and the bipolar plates was observed for a cell operating at a current density of 1.5 A.cm −2 . These measurements show a strong non-uniformity of the temperature profile through membrane electrode assembly (MEA) that future phenomenological models must take into account. In addition, the simultaneous measurements of heat and water flux through the MEA leads to the conclusion that produced water crosses the diffusion layer in vapor phase. A very simple heat transfer model is proposed.

  10. Optimal design of tests for heat exchanger fouling identification

    International Nuclear Information System (INIS)

    Palmer, Kyle A.; Hale, William T.; Such, Kyle D.; Shea, Brian R.; Bollas, George M.

    2016-01-01

    Highlights: • Built-in test design that optimizes the information extractable from the said test. • Method minimizes the covariance of a fault with system uncertainty. • Method applied for the identification and quantification of heat exchanger fouling. • Heat exchanger fouling is identifiable despite the uncertainty in inputs and states. - Graphical Abstract: - Abstract: Particulate fouling in plate fin heat exchangers of aircraft environmental control systems is a recurring issue in environments rich in foreign object debris. Heat exchanger fouling detection, in terms of quantification of its severity, is critical for aircraft maintenance scheduling and safe operation. In this work, we focus on methods for offline fouling detection during aircraft ground handling, where the allowable variability range of admissible inputs is wider. We explore methods of optimal experimental design to estimate heat exchanger inputs and input trajectories that maximize the identifiability of fouling. In particular, we present a methodology in which D-optimality is used as a criterion for statistically significant inference of heat exchanger fouling in uncertain environments. The optimal tests are designed on the basis of a heat exchanger model of the inherent mass, energy and momentum balances, validated against literature data. The model is then used to infer sensitivities of the heat exchanger outputs with respect to fouling metrics and maximize them by manipulating input trajectories; thus enhancing the accuracy in quantifying the fouling extent. The proposed methodology is evaluated with statistical indices of the confidence in estimating thermal fouling resistance at uncertain operating conditions, explored in a series of case studies.

  11. CFD as a Design Tool for a Concentric Heat Exchanger

    NARCIS (Netherlands)

    Oosterhuis, Joris; Bühler, Simon; wilcox, D; van der Meer, Theodorus H.

    2012-01-01

    A concentric gas-to-gas heat exchanger is designed for application as a recuperator in the domestic boiler industry. The recuperator recovers heat from the exhaust gases of a combustion process to preheat the ingoing gaseous fuel mixture resulting in increased fuel efficiency. This applied study

  12. Developing mixed convection in a coiled heat exchanger

    NARCIS (Netherlands)

    Sillekens, J.J.M.; Rindt, C.C.M.; Steenhoven, van A.A.

    1998-01-01

    In this paper the development of mixed convection in a helically coiled heat exchanger for Re = 500, Pr = 5 and d = 1/14 is studied. The influence of buoyancy forces (Gr = ¢O (105)) on heat transfer and secondary flow is analyzed. In the method used the parabolized equations are solved using a

  13. Developing mixed convection in a coiled heat exchanger

    NARCIS (Netherlands)

    Sillekens, J.J.M.; Rindt, C.C.M.; Steenhoven, van A.A.

    1998-01-01

    In this paper the development of mixed convection in a helically coiled heat exchanger for Re = 500, Pr = 5 and
    δ =114
    is studied. The influence of buoyancy forces ¢
    (Gr = ¢O (105))
    on heat transfer and secondary flow is analyzed. In the method used the parabolized equations are

  14. Hierarchic modeling of heat exchanger thermal hydraulics

    International Nuclear Information System (INIS)

    Horvat, A.; Koncar, B.

    2002-01-01

    Volume Averaging Technique (VAT) is employed in order to model the heat exchanger cross-flow as a porous media flow. As the averaging of the transport equations lead to a closure problem, separate relations are introduced to model interphase momentum and heat transfer between fluid flow and the solid structure. The hierarchic modeling is used to calculate the local drag coefficient C d as a function of Reynolds number Re h . For that purpose a separate model of REV is built and DNS of flow through REV is performed. The local values of heat transfer coefficient h are obtained from available literature. The geometry of the simulation domain and boundary conditions follow the geometry of the experimental test section used at U.C.L.A. The calculated temperature fields reveal that the geometry with denser pin-fins arrangement (HX1) heats fluid flow faster. The temperature field in the HX2 exhibits the formation of thermal boundary layer between pin-fins, which has a significant role in overall thermal performance of the heat exchanger. Although presented discrepancies of the whole-section drag coefficient C d are large, we believe that hierarchic modeling is an appropriate strategy for calculation of complex transport phenomena in heat exchanger geometries.(author)

  15. Optimization of porous microchannel heat exchanger

    Science.gov (United States)

    Kozhukhov, N. N.; Konovalov, D. A.

    2017-11-01

    The technical progress in information and communication sphere leads to a sharp increase in the use of radio electronic devices. Functioning of radio electronics is accompanied by release of thermal energy, which must be diverted from the heat-stressed element. Moreover, using of electronics at negative temperatures, on the contrary, requires supply of a certain amount of heat to start the system. There arises the task of creating a system that allows both to supply and to divert the necessary amount of thermal energy. The development of complex thermostabilization systems for radio electronic equipment is due to increasing the efficiency of each of its elements separately. For more efficient operation of a heat exchanger, which directly affects the temperature of the heat-stressed element, it is necessary to calculate the mode characteristics and to take into account the effect of its design parameters. The results of optimizing the microchannel heat exchanger are presented in the article. The target optimization functions are the mass, pressure drop and temperature. The parameters of optimization are the layout of porous fins, their geometric dimensions and coolant flow. For the given conditions, the optimum variant of porous microchannel heat exchanger is selected.

  16. A numerical study of the supercritical CO2 plate heat exchanger subject to U-type, Z-type, and multi-pass arrangements

    Science.gov (United States)

    Zhu, Chen-Xi; Wang, Chi-Chuan

    2018-01-01

    This study proposes a numerical model for plate heat exchanger that is capable of handling supercritical CO2 fluid. The plate heat exchangers under investigation include Z-type (1-pass), U-type (1-pass), and 1-2 pass configurations. The plate spacing is 2.9 mm with a plate thickness of 0.8 mm, and the size of the plate is 600 mm wide and 218 mm in height with 60 degrees chevron angle. The proposed model takes into account the influence of gigantic change of CO2 properties. The simulation is first compared with some existing data for water-to-water plate heat exchangers with good agreements. The flow distribution, pressure drop, and heat transfer performance subject to the supercritical CO2 in plate heat exchangers are then investigated. It is found that the flow velocity increases consecutively from the entrance plate toward the last plate for the Z-type arrangement, and this is applicable for either water side or CO2 side. However, the flow distribution of the U-type arrangement in the water side shows opposite trend. Conversely, the flow distribution for U-type arrangement of CO2 depends on the specific flow ratio (C*). A lower C* like 0.1 may reverse the distribution, i.e. the flow velocity increases moderately alongside the plate channel like Z-type while a large C* of 1 would resemble the typical distribution in water channel. The flow distribution of CO2 side at the first and last plate shows a pronounced drop/surge phenomenon while the channels in water side does not reveal this kind of behavior. The performance of 2-pass plate heat exchanger, in terms of heat transfer rate, is better than that of 1-pass design only when C* is comparatively small (C* < 0.5). Multi-pass design is more effective when the dominant thermal resistance falls in the CO2 side.

  17. Liquid-metal-gas heat exchanger for HTGR type reactors

    International Nuclear Information System (INIS)

    Werth, G.

    1980-01-01

    The aim of this study is to investigate the heat transfer characteristics of a liquid metal heat exchanger (HE) for a helium-cooled high temperature reactor. A tube-type heat exchanger is considered as well as two direct exchangers: a bubble-type heat exchanger and a heat exchanger according to the spray principle. Experiments are made in order to determine the gas content of bubble-type heat exchangers, the dependence of the droplet diameter on the nozzle diameter, the falling speed of the droplets, the velocity of the liquid jet, and the temperature variation of liquid jets. The computer codes developed for HE calculation are structured so that they may be used for gas/liquid HE, too. Each type of HE that is dealt with is designed by accousting for a technical and an economic assessment. The liquid-lead jet spray is preferred to all other types because of its small space occupied and its simple design. It shall be used in near future in the HTR by the name of lead/helium HE. (GL) [de

  18. Radiant heat exchange measurements for Tore Supra

    International Nuclear Information System (INIS)

    Chatain, D.; Disdier, F.; Gauthier, A.; Raffin, M.; Renaud, M.

    1984-03-01

    In order to minimize the energy consumption of the low temperature cryogenic system connected to the superconducting magnet of TORE-SUPRA, heat exchange from thermal radiation between the vacuum vessels and the thermal shields has been studied. Accordingly large scale cold and hot walls of T.S. have been simulated in a model with reduced dimensions. In this model, the experiment consists in the measurement of the thermal radiated power between two concentric cylindrical surfaces of stainless steel under vacuum conditions. The temperature of the external cylinder was kept constant at 80 K. The internal cylinder was bakeable up to 250 0 C. Various surface treatments were applied on the two cylinders (mechanical polishing and metal deposition of Al, Ag, Ni) [fr

  19. 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)

    Austegard, Anders

    1997-12-31

    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.

  20. Numerical simulation of shell-side heat transfer and flow of natural circulation heat exchanger

    International Nuclear Information System (INIS)

    Xue Ruojun; Deng Chengcheng; Li Chaojun; Wang Mingyuan

    2012-01-01

    In order to analyze the influence on the heat transfer and flow characteristics of the heat exchanger model of different solving models and structures, a variety of transformation to the model equivalent for the heat exchanger was studied. In this paper, Fluent software was used to simulate the temperature-field and flow-field of the equivalent model, and investigate its heat-transferring and flow characteristics. Through comparative analysis of the distribution of temperature-field and flow-field for different models, the heat-transferring process and natural convection situation of heat exchanger were deeply understood. The results show that the temperature difference between the inside and outside of the natural circulation heat exchanger tubes is larger and the flow is more complex, so the turbulence model is the more reasonable choice. Asymmetry of tubes position makes the flow and heat transfer of the fluid on both sides to be dissymmetrical and makes the fluid interaction, and increases the role of natural convection. The complex structure of heat exchanger makes the flow and heat transfer of the fluid on both sides to be irregular to some extent when straight tubes into C-bent are transformed, and all these make the turbulence intensity increase and improve the effect of heat transfer. (authors)

  1. Prediction of Heat Removal Capacity of Horizontal Condensation Heat Exchanger submerged in Pool

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Seong-Su; Hong, Soon-Joon [FNC Tech., Yongin (Korea, Republic of); Cho, Hyoung-Kyu [Seoul National University, Seoul (Korea, Republic of); Park, Goon-Cherl [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2014-10-15

    As representative passive safety systems, there are the passive containment cooling system (PCCS) of ESBWR, the emergency condenser system (ECS) of the SWR-1000, the passive auxiliary feed-water system (PAFS) of the APR+ and etc. During the nuclear power plant accidents, these passive safety systems can cool the nuclear system effectively via the heat transfer through the steam condensation, and then mitigate the accidents. For the optimum design and the safety analysis of the passive safety system, it is essential to predict the heat removal capacity of the heat exchanger well. The heat removal capacity of the horizontal condensation heat exchanger submerged in a pool is determined by a combination of a horizontal in-tube condensation heat transfer and a boiling heat transfer on the horizontal tube. Since most correlations proposed in the previous nuclear engineering field were developed for the vertical tube, there is a certain limit to apply these correlations to the horizontal tube. Therefore, this study developed the heat transfer model for the horizontal Ushaped condensation heat exchanger submerged in a pool to predict well the horizontal in-tube condensation heat transfer, the boiling heat transfer on the horizontal tube and the overall heat removal capacity of the heat exchanger using the best-estimate system analysis code, MARS.

  2. A fundamentally new approach to air-cooled heat exchangers.

    Energy Technology Data Exchange (ETDEWEB)

    Koplow, Jeffrey P.

    2010-01-01

    We describe breakthrough results obtained in a feasibility study of a fundamentally new architecture for air-cooled heat exchangers. A longstanding but largely unrealized opportunity in energy efficiency concerns the performance of air-cooled heat exchangers used in air conditioners, heat pumps, and refrigeration equipment. In the case of residential air conditioners, for example, the typical performance of the air cooled heat exchangers used for condensers and evaporators is at best marginal from the standpoint the of achieving maximum the possible coefficient of performance (COP). If by some means it were possible to reduce the thermal resistance of these heat exchangers to a negligible level, a typical energy savings of order 30% could be immediately realized. It has long been known that a several-fold increase in heat exchanger size, in conjunction with the use of much higher volumetric flow rates, provides a straight-forward path to this goal but is not practical from the standpoint of real world applications. The tension in the market place between the need for energy efficiency and logistical considerations such as equipment size, cost and operating noise has resulted in a compromise that is far from ideal. This is the reason that a typical residential air conditioner exhibits significant sensitivity to reductions in fan speed and/or fouling of the heat exchanger surface. The prevailing wisdom is that little can be done to improve this situation; the 'fan-plus-finned-heat-sink' heat exchanger architecture used throughout the energy sector represents an extremely mature technology for which there is little opportunity for further optimization. But the fact remains that conventional fan-plus-finned-heat-sink technology simply doesn't work that well. Their primary physical limitation to performance (i.e. low thermal resistance) is the boundary layer of motionless air that adheres to and envelops all surfaces of the heat exchanger. Within this

  3. Eddy current testing of heat exchangers tubes

    International Nuclear Information System (INIS)

    Gouez, J.F.; Rieusset, A.; Groix, F.

    An automatic system for Eddy Current testing of heat exchangers tubes of warships was developed. The advantages are an exposure of the controller limited at the time required to put in place the system and a reduced time of control [fr

  4. Assessing heat exchanger performance data using temperature ...

    African Journals Online (AJOL)

    In addition, any calculated performance acceptance criteria must also consider uncertainty and error in the experimental measurements of temperature and flow. However, most statistical methods are complex and not easily applied to heat exchangers such as those that serve the power plant industry where data are difficult ...

  5. Study of turbulent flows loaded with particles. Application to the particulate fouling of corrugated plate heat exchangers

    International Nuclear Information System (INIS)

    Kouidri, Frederic

    1997-01-01

    This work is a numerical and experimental study of the behaviour of a turbulent flow loaded with solid particles. It involves the particulate fouling of plate heat exchangers used in industrial field. Visual observation and LDA measurements inside a mock-up show the presence of large coherent vortices and confirm the tight link between particulate deposition and flow field. The vortices participate to the creation of preferential areas where the particles are in contact with the wall, and they shape the deposit according to a precise mechanism. Two processes of deposit removal have also been shown. Hydraulic phenomena and particles behaviours pointed out in the experiment are compared to different typical samples in a bibliographic survey. The use of the a software for computational fluid dynamics (TRIO developed at the Commissariat a l'Energie Atomique) completed the experimental results by predicting the particles behaviour into the turbulent flow. The approach is based on a connection between a pseudo-direct simulation of the turbulent flow and a Lagrangian model for particles paths. The results show good agreements, qualitatively speaking, between numerical predictions and experimental measurement. The arrangement of the deposit onto the corrugated surface is globally well described by numerical simulation. The influence of some parameters on deposition process such as the flow (corresponding to Re=5000 or Re=10000), the horizontal or vertical position of the channel or the particles diameter (d p =100 μm or d p =25 μm) has been studied. (author) [fr

  6. Numerical study of a novel counter-flow heat and mass exchanger for dew point evaporative cooling

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.; Riffat, S.B. [School of the Built Environment, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Li, J.M. [Department of Thermal Engineering, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2008-10-15

    The paper presents numerical investigation of a novel counter-flow heat and mass exchanger used in the indirect evaporative dew point cooling systems, a potential alternative to the conventional mechanical compression air conditioning systems. Numeric simulation was carried out to optimise the geometrical sizes and operating conditions of the exchanger in order to enhance the cooling (dew point and wet bulb) effectiveness of the exchanger and maximise the energy efficiency of the dew point cooling system. The results of the simulations indicated that cooling (dew point and wet bulb) effectiveness and energy efficiency are largely dependent on the dimensions of the airflow passages, air velocity and working-to-intake-air ratio, and less dependent on the temperature of the feed water. It is recommended that exchanger intake air velocity should be controlled to a value below 0.3-0.5 m/s; height of air passage (channel) should be set to 6 mm or below and the length of the passage should be 200 time the height; the working-to-intake-air ratio should be around 0.4. Under the UK summer design condition, i.e., 28{sup o}C of dry bulb temperature, 20{sup o}C of wet bulb temperature and 16{sup o}C of dew point temperature, the exchanger can achieve wet-bulb effectiveness of up to 1.3 and dew-point effectiveness of up to 0.9. (author)

  7. Continuous cleaning of heat exchanger with recirculating fluidized bed

    International Nuclear Information System (INIS)

    St Kollbach, J.; Dahm, W.; Rautenbach, R.

    1987-01-01

    Fluidized bed heat exchangers for liquids have been studied in the United States, the Netherlands, and the Federal Republic of Germany. Between 1965 and 1970, fluidized bed heat exchangers were developed in the United States as brine heaters in seawater desalination. Furthermore, their potential in the utilization of geothermal energy was tested between 1975 and 1980. In the Netherlands, fluidized bed heat exchangers have been developed since 1973 for brine heating and heat recovery in multistage flash evaporators for seawater desalination and, since about 1980, for applications in the process industry. The authors became interested in fluidized bed heat exchangers first in 1978 in connection with wastewater evaporation. The authors emphasize that the results of all these groups were in basic agreement. They can be summarized as follows: 1. The fluidized bed will in many cases maintain totally clean surfaces and neither scaling nor fouling will occur. In cases where even a fluidized bed cannot completely prevent scaling or fouling, the thickness of the layer is controlled. In these cases stable operation maintaining acceptable overall heat transfer coefficients is possible without cleaning. 2. There are always excellent heat transfer coefficients as low superficial velocities of less than ν < 0.5 m/s. 3. The pressure losses are comparable with those in normal heat exchangers since fluidized bed heat exchangers are mostly operated at low superficial velocities. 4. Feed flow may be varied between 50 and 150% or more of the design feed flow. 5. Erosion is negligible. 6. Fluidized bed particles can be manufactured from all sorts of chemically and mechanically resistant materials, such as sand, glass, ceramics, and metals

  8. Condensation and frost formation in heat exchangers

    International Nuclear Information System (INIS)

    Rostami, A.A.

    1982-01-01

    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

  9. Tube-in-shell heat exchangers

    International Nuclear Information System (INIS)

    Richardson, J.

    1976-01-01

    Tube-in-shell heat exchangers normally comprise a bundle of parallel tubes within a shell container, with a fluid arranged to flow through the tubes in heat exchange with a second fluid flowing through the shell. The tubes are usually end supported by the tube plates that separate the two fluids, and in use the tube attachments to the tube plates and the tube plates can be subject to severe stress by thermal shock and frequent inspection and servicing are required. Where the heat exchangers are immersed in a coolant such as liquid Na such inspection is difficult. In the arrangement described a longitudinally extending central tube is provided incorporating axially spaced cylindrical tube plates to which the opposite ends of the tubes are attached. Within this tube there is a tubular baffle that slidably seals against the wall of the tube between the cylindrical tube plates to define two co-axial flow ducts. These ducts are interconnected at the closed end of the tube by the heat exchange tubes and the baffle comprises inner and outer spaced walls with the interspace containing Ar. The baffle is easily removable and can be withdrawn to enable insertion of equipment for inspecting the wall of the tube and tube attachments and to facilitate plugging of defective tubes. Cylindrical tube plates are believed to be superior for carrying pressure loads and resisting the effects of thermal shock. Some protection against thermal shock can be effected by arranging that the secondary heat exchange fluid is on the tube side, and by providing a thermal baffle to prevent direct impingement of hot primary fluid on to the cylindrical tube plates. The inner wall of the tubular baffle may have flexible expansible region. Some nuclear reactor constructions incorporating such an arrangement are described, including liquid metal reactors. (U.K.)

  10. Thermodynamic optimization of heat exchanger tanks by exergy ...

    African Journals Online (AJOL)

    The paper introduces heat exchanger tanks, detailing their dominant thermodynamic relations to obtain the exergy analysis relations of heat exchanger tanks. Heat exchanger tank is examined under various laboratory conditions, including the power of heat element inside the tank, mass flow rate of cooling water of tank ...

  11. Dynamic Study of Feed-Effluent Heat Exchanger Addition on Double Bed Configuration Ammonia Reactor System within Varied Quenching Ratio

    Directory of Open Access Journals (Sweden)

    Adhi Tri Partono

    2018-01-01

    Full Text Available Ammonia is one of the most important industrial commodity due to its wide function. Ammonia synthesis reaction is an exotermic reaction. Therefore, Feed-Effluent Heat Exchanger (FEHE is added to increase thermal efficiency. However, FEHE could lead the process to experience hysteresis phenomenon due to interaction between equipments as one steady state T feed could result several T outlet. Hysteresis phenomenon may result asset losses like explosion, leakage, and loosing material integrity. Double bed reactor configuration allows us to use several operating parameters as variation to overcome hysteresis. In this review, quenching ratio was chosen to be that varied parameter. This study aims to determine how quenching ratio affects hysteresis zone by utilizing Aspen Hysys® V8.8 as simulation tool. Simulation showed that quenching ratio would narrow hysteresis zone yet increased extinction temperature that lower the conversion. Conversion profile showed that 0.2 quenching ratio got the highest conversion for system with bed volume ratio 2:1 while total volume was 30 m3. However, the feed temperature was fallen at hysteresis zone. Dynamic simulation showed that highest conversion feed temperature (10%ΔTf above extinct temperature was still able to preserve stability with descending temperature approach. Hysteresis itself started to occur at 1.7%ΔTf above extinct temperature

  12. Heat transfer study on open heat exchangers used in jaggery production modules – Computational Fluid Dynamics simulation and field data assessment

    International Nuclear Information System (INIS)

    La Madrid, Raul; Marcelo, Daniel; Orbegoso, Elder Mendoza; Saavedra, Rafael

    2016-01-01

    Highlights: • Heat transfer modeling and simulation between flue gases and sugar cane juice. • Use of Computational Fluid Dynamics to get thermal parameters of a jaggery furnace. • Data acquisition system installed in the jaggery production module. • Parametric analysis changing the flue-gases velocity to represent temperature drops. - Abstract: Jaggery (also called organic sugar) is a concentrated product of sugarcane juice that is produced in rural communities in the highlands and jungle of Peru. In the last few years there has been an increase in the exports of jaggery and higher volumes of production are required driving this activity from a rural process with small production to an industry seeking greater productivity. In this framework, optimization of the use of energy becomes essential for the proper development of the process of production and the correct performance of the involved equipment. Open heat exchangers made of stainless steel are used in the production of jaggery. These heat exchangers containing sugarcane juice are placed over a flue gas duct. The thermal energy contained in the gas is used to evaporate the water contained in the sugarcane juice thickening the juice and after evaporating almost all the water, a pasty crystalline yellow substance is left in the boiling pan which becomes solid after cooling, this is the jaggery. The modeling and simulation of heat transfer between the combustion gases and the juice is very important in order to improve the thermal efficiency of the process. It permits to know with a high level of detail the physical phenomena of heat transfer occurring from bagasse combustion flue gases to sugarcane juice. This paper presents the results of the numerical simulation of heat transfer phenomena in the open heat exchangers and those results are compared to field measured data. Numerical results about temperature drop of flue gases in the several locations of the jaggery furnace are in good accordance with

  13. Superphenix 1 intermediate heat exchanger fabrication

    International Nuclear Information System (INIS)

    Noel, H.; Granito, F.; Pouderoux, P.

    1985-01-01

    The eight Superphenix 375-MW (thermal) intermediate heat exchangers (IHXs) are similar in overall design to the Phenix components. Detailed design changes had to be made during fabrication on the following grounds: Due to seismic resistance, the support area was raised as high as possible to situate the component natural frequencies well out of the resonance peak range and remove thick plate-to-shell connections from heavy thermal load areas. Integration of lessons drawn from the Phenix incidents, due mainly to secondary sodium radial temperature disparities, resulted in the design of a more adaptable outlet header, together with a sodium mixing device, and in the reduction of temperature differences by heat insulation. To avoid circumferential temperature disparities, the iron shot biological shielding plug was replaced by stacked stainless steel plates within an outer shell, which in the new design, is not a supporting structure. The thermal-hydraulic and mechanical design of the component necessitated the elaboration of sophisticated computer codes, with validation of results on mock-ups. The detailed design studies and the actual manufacturing work had to adapt to both design developments and to inherent fabrication difficulties, mainly related to the very tight tolerances imposed for these exceptionally large components and to the welding of steel with an excessive boron content. The construction of the Creys-Malville IHXs afforded valuable industrial experience, which should provide a basis for the design of simpler and less costly IHX units for the forthcoming 1500-MW (electric) breeder

  14. Evaluation and Design of Downhole Heat Exchangers for Direct Application

    Energy Technology Data Exchange (ETDEWEB)

    Culver, G [Oregon Institute of Technology, Klamath Falls, Oregon; Reistad, G M [Oregon State University, Corvallis, Oregon

    0000-12-30

    Over 400 wells with downhole heat exchangers are in use in Klamath Falls, Oregon. Some have been in use for nearly 30 years. Despite the large number and the long experience, the exact nature of the mechanism of heat exchange and, therefore, the maximum output was not known, except that it had been theorized that convection cells were established in the well. Oregon Institute of Technology and Oregon State University are jointly involved in a project to study the heat exchange process and economics of the downhole heat exchanger system. The existence of significant convection cell circulation has been established and measured using a “spinner,” hot film anemometer, and by energy balance calculations. Based on these measurements, analytical models have been developed which predict heat extraction rates within 15% of actual measured values. The existence of significant mixing of “new” and circulating well fluid has been established and can be calculated, although at this time not accurately predicted before testing a well. Based on the analytical models, multi-tube heat exchangers have been designed and very recently tested with outputs within 15% of predicted values. Economic analyses shows that for small to moderate extraction rates, about 300 kW thermal, and shallow wells, DHEs may be more economical than pumped systems when surface discharge is not acceptable.

  15. An innovative plate heat exchanger of enhanced compactness

    International Nuclear Information System (INIS)

    Vitillo, Francesco; Cachon, Lionel; Reulet, Philippe; Laroche, Emmanuel; Millan, Pierre

    2015-01-01

    In the framework of CEA R&D program to develop the Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID), the present work aims to demonstrate the industrial interest of an innovative compact heat exchanger technology. In fact, one of the main innovations of the ASTRID reactor could be the use of a Brayton Gas-power conversion system, in order to avoid the energetic sodium–water interaction that might occur if a traditional Rankine cycle was used. The present work aims to study the thermal-hydraulic performance of the innovative compact heat exchanger concept. Hence, thanks to a trustful numerical model, friction factor and heat transfer correlations are obtained. Then, a global compactness comparison strategy is proposed, taking into account design constraints. Finally, it is demonstrated that the innovative heat exchanger concept is more compact then other already industrial technologies of interest, showing that is can be considered to warrant serious consideration for future ASTRID design as well as for any industrial application that needs very compact heat exchanger technologies. - Highlights: • We propose a new innovative compact heat exchanger technology. • We provide thermal-hydraulic correlations for designers. • We provide a comparison strategy with existing technologies. • We demonstrate the industrial interest of the innovative concept

  16. Preliminary SP-100/Stirling heat exchanger designs

    International Nuclear Information System (INIS)

    Schmitz, P.; Tower, L.; Blue, B.; Dunn, P.

    1994-01-01

    Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems

  17. On the optimal design of shell and tube heat exchanger for nuclear applications

    International Nuclear Information System (INIS)

    Abd Rabbo, F.M.M.; Fatb Allab, A.; El-Fawal, M.

    1997-01-01

    In nuclear industry, heat exchanger plays an important role in the transfer of heat from reactor core, where heat is generated, to the ultimate heat sink UHS, and then is dissipated. The actual design of heat exchanger not only relies on thermohydraulic considerations but also on economical aspects and radiological safety considerations. For optimal design of heat exchanger for a specific application a compromise should be made for determining the important factors affecting the design. In this paper, an optimization model is presented for shell and tube heat exchanger, which could be considered as a tool for computer aided design. A case study is presented to explore the present adopted model. 3 figs

  18. Numerical Modeling of Fin and Tube Heat Exchanger for Waste Heat Recovery

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    In the present work, multiphysics numerical modeling is carried out to predict the performance of a liquid-gas fin and tube heat exchanger design. Three-dimensional (3D) steady-state numerical model using commercial software COMSOL based on finite element method (FEM) is developed. The study...... associates conjugate heat transfer phenomenon with the turbulent flow to describe the variable temperature and velocity profile. The performance of heat exchanger design is investigated in terms of overall heat transfer coefficient, Nusselt number, Colburn j-factor, flow resistance factor, and efficiency...... between fin and tube. The present numerical model predicts the performance of the heat exchanger design, therefore, can be applied to existing waste heat recovery systems to improve the overall performance with optimized design and process-dependent parameters....

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  20. Diamond wire cutting of heat exchangers

    International Nuclear Information System (INIS)

    Beckman, T.R.; Bjerler, J.

    1991-01-01

    With the change-out of equipment at nuclear power plants comes large quantities of low level contaminated metallic waste. Of particular concern are large heat exchangers, preheaters and steam generators. These bulky items consume huge volumes of burial space. The need for volume reduction and recycling of these metals has created new demands for 'how' to cut heat exchangers into useful sizes for decontamination, melting or compaction. This paper reviews the cutting solution provided by a diamond wire system, with particular regard for cutting of a Ringhals Preheater Bundle at Studsvik Nuclear in 1989. The background of diamond wire sawing is discussed and basic components of wire sawing are explained. Other examples of wire cutting decommissioned components are also given. (author)

  1. Laser Processed Condensing Heat Exchanger Technology Development

    Science.gov (United States)

    Hansen, Scott; Wright, Sarah; Wallace, Sarah; Hamilton, Tanner; Dennis, Alexander; Zuhlke, Craig; Roth, Nick; Sanders, John

    2017-01-01

    The reliance on non-permanent coatings in Condensing Heat Exchanger (CHX) designs is a significant technical issue to be solved before long-duration spaceflight can occur. Therefore, high reliability CHXs have been identified by the Evolvable Mars Campaign (EMC) as critical technologies needed to move beyond low earth orbit. The Laser Processed Condensing Heat Exchanger project aims to solve these problems through the use of femtosecond laser processed surfaces, which have unique wetting properties and potentially exhibit anti-microbial growth properties. These surfaces were investigated to identify if they would be suitable candidates for a replacement CHX surface. Among the areas researched in this project include microbial growth testing, siloxane flow testing in which laser processed surfaces were exposed to siloxanes in an air stream, and manufacturability.

  2. Dynamics of the cross flow heat exchanger for heating purposes

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, K [Karlsruhe Univ. (TH) (Germany, F.R.). Inst. fuer Mess- und Regelungstechnik mit Maschinenlaboratorium

    1980-09-01

    A series of publications is available on the dynamic behaviour of heat exchangers (or heat transmitters, respectively), the subject of which is to deal with direct methods or with refined starting models for this general theme. The bridging between both these manners of advance remained as a problem. The author tried in his own investigation to solve the problem, and indeed by the selection of the correct starting model. He succeeded in this way, in that he removed conceptually a finned pipe from an arbitrary place of a heat exchanger and, furthermore, cut out from this particular pipe an arbitrary section. This section now does not stand alone for itself because the processes, which occur upstream of this section at the air-side and the water-side, are the input quantities of the section, which changes them due to its static and dynamic behaviour and emits them again as output quantities. The author, therefore, treats at first the dynamic behaviour of the section, which is represented in a signal flow diagram and which is used to derive approximate solutions from it. Furthermore, the author discusses the evident derivation of the total behaviour of heat exchangers.

  3. A study on development of a plugging margin evaluation method taking into account the fouling of shell-and tube heat exchangers

    International Nuclear Information System (INIS)

    Hwang, Kyeong Mo; Jin, Tae Eun; Kim, Kyung Hoon

    2006-01-01

    As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant

  4. Verification on reliability of heat exchanger for primary cooling system

    International Nuclear Information System (INIS)

    Koike, Sumio; Gorai, Shigeru; Onoue, Ryuji; Ohtsuka, Kaoru

    2010-07-01

    Prior to the JMTR refurbishment, verification on reliability of the heat exchangers for primary cooling system was carried out to investigate an integrity of continuously use component. From a result of the significant corrosion, decrease of tube thickness, crack were not observed on the heat exchangers, and integrity of heat exchangers were confirmed. In the long terms usage of the heat exchangers, the maintenance based on periodical inspection and a long-term maintenance plan is scheduled. (author)

  5. Geothermal heat exchanger with coaxial flow of fluids

    Directory of Open Access Journals (Sweden)

    Pejić Dragan M.

    2005-01-01

    Full Text Available The paper deals with a heat exchanger with coaxial flow. Two coaxial pipes of the secondary part were placed directly into a geothermal boring in such a way that geothermal water flows around the outer pipe. Starting from the energy balance of the exchanger formed in this way and the assumption of a study-state operating regime, a mathematical model was formulated. On the basis of the model, the secondary circle output temperature was determined as a function of the exchanger geometry, the coefficient of heat passing through the heat exchange areas, the average mass isobaric specific heats of fluid and mass flows. The input temperature of the exchanger secondary circle and the temperature of the geothermal water at the exit of the boring were taken as known values. Also, an analysis of changes in certain factors influencing the secondary water temperature was carried out. The parameters (flow temperature of the deep boring B-4 in Sijarinska Spa, Serbia were used. The theoretical results obtained indicate the great potential of this boring and the possible application of such an exchanger.

  6. Heat exchangers and methods of construction thereof

    International Nuclear Information System (INIS)

    Schluderberg, D.C.

    1988-01-01

    A heat exchanger is described comprising a shell having first inlet means and first outlet means for the flow of a first fluid therethrough, a plurality of tubes within the shell to provide a path for flow of a second fluid in heat exchange relation to the first fluid, second inlet means and second outlet means for flow of the second fluid to and from the tubes respectively, a tubular member concentric with at least a portion of the length of one of the tubes to define a space between the tube and the tubular member, at least one radially outwardly projecting portion on the tubular member, and a plurality of tube support means spaced apart and disposed generally perpendicular to the tube axes, wherein the tubular member is fixedly attached at one end to one of the tube support means and at the other end to an adjacent one of the tube support means, the space between the tube and the tubular member is closed to flow of both the first fluid and the second fluid, and the radially outwardly projecting portion on the tubular member extends longitudinally to allow flexing of the tubular member and expanding thereof radially outwardly during construction of the heat exchanger so as to allow insertion of the tube into the tubular member, the radially outwardly projecting portion defining a gap which contributes to the space between the tube and the tubular member. 6 figs

  7. Analysis of the heat transfer in double and triple concentric tube heat exchangers

    Science.gov (United States)

    Rădulescu, S.; Negoiţă, L. I.; Onuţu, I.

    2016-08-01

    The tubular heat exchangers (shell and tube heat exchangers and concentric tube heat exchangers) represent an important category of equipment in the petroleum refineries and are used for heating, pre-heating, cooling, condensation and evaporation purposes. The paper presents results of analysis of the heat transfer to cool a petroleum product in two types of concentric tube heat exchangers: double and triple concentric tube heat exchangers. The cooling agent is water. The triple concentric tube heat exchanger is a modified constructive version of double concentric tube heat exchanger by adding an intermediate tube. This intermediate tube improves the heat transfer by increasing the heat area per unit length. The analysis of the heat transfer is made using experimental data obtained during the tests in a double and triple concentric tube heat exchanger. The flow rates of fluids, inlet and outlet temperatures of water and petroleum product are used in determining the performance of both heat exchangers. Principally, for both apparatus are calculated the overall heat transfer coefficients and the heat exchange surfaces. The presented results shows that triple concentric tube heat exchangers provide better heat transfer efficiencies compared to the double concentric tube heat exchangers.

  8. Experimental investigation of water sprayed finned heat exchanger tube bundles

    International Nuclear Information System (INIS)

    Sommer, A.

    1987-07-01

    Experimental investigations have been made to study the performance of two finned tube-bundle heat exchangers (FORGO type) when wetted by water sprays. The heat exchangers are designed to cool water in a dry cooling tower. The test-elements had a frontal area of 1 m 2 . The water sprays were created by 20 nozzles, 200 mm in front of the heat exchangers. Air velocities at the inlet of the coolers were in the range 0,8 m/s to 12 m/s and initial temperature differences ITD reached 45 degrees C. The test facility was designed to determine the combined latent and sensible heat fluxes in the wetted heat exchanger, the airside pressure drop and the air humidity and temperature at the exchanger inlet and outlet, and to measure the weight of the water wetting the cooler's surface. The sprayed test elements were investigated in different positions, but most of the experiments were carried out in the position with the fins horizontal

  9. Heat transfer enhancement in heat exchangers by longitudinal vortex generators

    International Nuclear Information System (INIS)

    Guntermann, T.; Fiebig, M.; Mitra, N.K.

    1990-01-01

    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 Re d = 1000 and a vortex generator angle of attack of β = 25 degrees heat transfer is enhanced locally by more than 300% and in the mean by 50%. These values increase further with Re and β

  10. Heat exchanger support apparatus in a fluidized bed

    Science.gov (United States)

    Lawton, Carl W.

    1982-01-01

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

  11. Three-dimensional numerical study of heat transfer characteristics of plain plate fin-and-tube heat exchangers from view point of field synergy principle

    International Nuclear Information System (INIS)

    He, Y.L.; Tao, W.Q.; Song, F.Q.; Zhang, W.

    2005-01-01

    In this paper, 3-D numerical simulations were performed for laminar heat transfer and fluid flow characteristics of plate fin-and-tube heat exchanger. The effects of five factors were examined: Re number, fin pitch, tube row number, spanwise and longitudinal tube pitch. The Reynolds number based on the tube diameter varied from 288 to 5000, the non-dimensional fin pitch based on the tube diameter varied from 0.04 to 0.5, the tube row number from 1 to 4, the spanwise tube pitch S 1 /d varies from 1.2 to 3, and the longitudinal tube pitch S 2 /d from 1.0 to 2.4. The numerical results were analyzed from the view point of field synergy principle, which says that the reduction of the intersection angle between velocity and fluid temperature gradient is the basic mechanism to enhance convective heat transfer. It is found that the effects of the five parameters on the heat transfer performance of the finned tube banks can be well described by the field synergy principle, i.e., the enhancement or deterioration of the convective heat transfer across the finned tube banks is inherently related to the variation of the intersection angle between the velocity and the fluid temperature gradient. It is also recommended that to further enhance the convective heat transfer, the enhancement techniques, such as slotting the fin, should be adopted mainly in the rear part of the fin where the synergy between local velocity and temperature gradient become worse

  12. Advanced heat exchanger development for molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Sabharwall, Piyush, E-mail: Piyush.Sabharwall@inl.gov [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Clark, Denis; Glazoff, Michael [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark [University of Wisconsin, Madison (United States)

    2014-12-15

    Highlights: • Hastelloy N and 242, shows corrosion resistance to molten salt at nominal operating temperatures. • Both diffusion welds and sheet material in Hastelloy N were corrosion tested in at 650, 700, and 850 °C for 200, 500, and 1000 h. • Thermal gradients and galvanic couples in the molten salts enhance corrosion rates. • Corrosion rates found were typically <10 mils per year. - Abstract: This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non-nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, that show good corrosion resistance in molten salt at nominal operating temperatures up to 700 °C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in 58 mol% KF and 42 mol% ZrF{sub 4} at 650, 700, and 850 °C for 200, 500, and 1000 h. Corrosion rates were similar between welded and nonwelded materials, typically <100 μm per year after 1000 h of corrosion tests. No catastrophic corrosion was observed in the diffusion welded regions. For materials of construction, nickel-based alloys and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of the type of salt impurity and alloy composition, with respect to chromium and carbon, to better define the best conditions for corrosion resistance. Also presented is the division of the nuclear reactor and high-temperature components per American Society of Mechanical

  13. Graphite Foam Heat Exchangers for Thermal Management

    Energy Technology Data Exchange (ETDEWEB)

    Klett, J.W.

    2004-06-07

    Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S

  14. Liquid Salt Heat Exchanger Technology for VHTR Based Applications

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark; Sridhara, Kumar; Allen, Todd; Peterson, Per

    2012-10-11

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

  15. Empirical Analysis for the Heat Exchange Effectiveness of a Thermoelectric Liquid Cooling and Heating Unit

    Directory of Open Access Journals (Sweden)

    Hansol Lim

    2018-03-01

    Full Text Available This study aims to estimate the performance of thermoelectric module (TEM heat pump for simultaneous liquid cooling and heating and propose empirical models for predicting the heat exchange effectiveness. The experiments were conducted to investigate and collect the performance data of TEM heat pump where the working fluid was water. A total of 57 sets of experimental data were statistically analyzed to estimate the effects of each independent variable on the heat exchange effectiveness using analysis of variance (ANOVA. To develop the empirical model, the six design parameters were measured: the number of transfer units (NTU of the heat exchangers (i.e., water blocks, the inlet water temperatures and temperatures of water blocks at the cold and hot sides of the TEM. As a result, two polynomial equations predicting heat exchange effectiveness at the cold and hot sides of the TEM heat pump were derived as a function of the six selected design parameters. Also, the proposed models and theoretical model of conventional condenser and evaporator for heat exchange effectiveness were compared with the additional measurement data to validate the reliability of the proposed models. Consequently, two conclusions have been made: (1 the possibility of using the TEM heat pump for simultaneous cooling and heating was examined with the maximum temperature difference of 30 °C between cold and hot side of TEM, and (2 it is revealed that TEM heat pump has difference with the conventional evaporator and condenser from the comparison results between the proposed models and theoretical model due to the heat conduction and Joule effect in TEM.

  16. Fabrication experiments for large helix heat exchangers

    International Nuclear Information System (INIS)

    Burgsmueller, P.

    1978-01-01

    The helical tube has gained increasing attention as a heat transfer element for various kinds of heat exchangers over the last decade. Regardless of reactor type and heat transport medium, nuclear steam generators of the helix type are now in operation, installlation, fabrication or in the project phase. As a rule, projects are based on the extrapolation of existing technologies. In the particlular case of steam generators for HTGR power stations, however, existing experience is with steam generators of up to about 2 m diameter whereas several projects involve units more than twice as large. For this reason it was felt that a fabrication experiment was necessary in order to verify the feasibility of modern steam generator designs. A test rig was erected in the SULZER steam generator shops at Mantes, France, and skilled personnel and conventional production tools were employed in conducting experiments relating to the coiling, handling and threading of large helices. (Auth.)

  17. Corrosion resistance of heat exchange equipment in hydrotreating Orenburg Condensate

    International Nuclear Information System (INIS)

    Teslya, B.M.; Burlov, V.V.; Parputs, I.V.; Parputs, T.P.

    1986-01-01

    The authors study the corrosion resistance of materials of construction and select appropriate materials for the fabrication of heat exchange equipment that will be serviceable under hydrotreating conditions. This paper discusses the Orenburg condensate hydrotreating unit which has been shut down repeatedly for repair because of corrosion damage to components of heat exchangers in the reactor section: tube bundles (08Kh18N10T steel), corrugated compensators (12Kh18N10T steel), and pins of the floating heads (37Kh13N8G8MFB steel). The authors recommend that the tube bundles and the compensators in heat exchangers in the reaction section should be fabricated of 08Kh21N6M2T or 10Kh17N13M2T steel. The pins have been replaced by new pins made of 10Kh17N13 X M2T steel, increasing the service life from 6-12 months to 2 years

  18. Process Stability Identification Through Dynamic Study of Single-bed Ammonia Reactor with Feed-Effluent Heat Exchanger (FEHE

    Directory of Open Access Journals (Sweden)

    Adhi Tri Partono

    2018-01-01

    Full Text Available In ammonia reactor system, a feed-effluent heat exchanger (FEHE is typically installed to utilize reaction-generated heat to heat the reactor’s feed. Utilizing energy from exothermic reaction to the incoming feed stream is often called “autothermic operation”. Despite the advantage of FEHE, there is a risk of utilizing FEHE in a reactor system such as instability of process temperature or known as hysteresis. Hysteresis phenomena in chemical process could cause operational problems, for example it could damage the integrity of the equipment’s material. This paper aims to evaluate the dynamic behavior of a single-bed ammonia reactor with FEHE, particularly to propose a way to prevent instability within the system. The dynamic simulation of the single-bed ammonia reactor with FEHE was performed with Aspen HYSYS v8.8. The result of the simulation result shows that hysteresis phenomenon in the ammonia reactor system occurs when the feed’s temperature is below a certain value. If the feed temperature reaches that value, the temperature of the reactor’s outlet oscillates. One of the solution to keep the feed temperature above that critical value is by installing a trim heater within the system. Based on the simulation, trim heater installation within the system is able to prevent hysteresis in the system evaluated.

  19. Assessment of Real Heat Transfer Coefficients through Shell and Tube and Plate Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Dan CONSTANTINESCU

    2011-07-01

    Full Text Available The purpose of this paper is to present a procedure used in the assessment of the real heat transfer characteristic of shell and tube and plate heat exchangers. The theoretical fundamentals of the procedure are introduced as well as the measured data collection and processing. The theoretical analysis is focused on the adoption of criterial equations which, subjected to certain verification criteria presented in the paper, provide the most credible value of the convection heat transfer coefficients inside the circular and flat tubes. In the end two case studies are presented, one concerning a shell and tube heat exchanger operational at INCERC Thermal Substation and the other concerning a plate heat exchanger tested on the Laboratory Stand of the Department of Building Services and Efficient Use of Energy in Buildings of INCERC Bucharest.

  20. Thermal response test data of five quadratic cross section precast pile heat exchangers.

    Science.gov (United States)

    Alberdi-Pagola, Maria

    2018-06-01

    This data article comprises records from five Thermal Response Tests (TRT) of quadratic cross section pile heat exchangers. Pile heat exchangers, typically referred to as energy piles, consist of traditional foundation piles with embedded heat exchanger pipes. The data presented in this article are related to the research article entitled "Comparing heat flow models for interpretation of precast quadratic pile heat exchanger thermal response tests" (Alberdi-Pagola et al., 2018) [1]. The TRT data consists of measured inlet and outlet temperatures, fluid flow and injected heat rate recorded every 10 min. The field dataset is made available to enable model verification studies.

  1. Thermal response test data of five quadratic cross section precast pile heat exchangers

    Directory of Open Access Journals (Sweden)

    Maria Alberdi-Pagola

    2018-06-01

    Full Text Available This data article comprises records from five Thermal Response Tests (TRT of quadratic cross section pile heat exchangers. Pile heat exchangers, typically referred to as energy piles, consist of traditional foundation piles with embedded heat exchanger pipes. The data presented in this article are related to the research article entitled “Comparing heat flow models for interpretation of precast quadratic pile heat exchanger thermal response tests” (Alberdi-Pagola et al., 2018 [1]. The TRT data consists of measured inlet and outlet temperatures, fluid flow and injected heat rate recorded every 10 min. The field dataset is made available to enable model verification studies.

  2. Analysis of defect tubes of fast reactor heat exchanger

    International Nuclear Information System (INIS)

    Rukhlyada, N.Ya.

    2014-01-01

    The experimental Auger electron spectroscopy and X-ray diffraction microanalysis data of laboratory investigations of defect tubes of heat exchanger with sodium coolant are presented. Element distribution through depth of corrosion layers form on the side of coolant (sodium) and on the surface contacting with steam in heat exchanger tube is studied. Sodium presence through all thickness of the tube is determined. It is shown that treatment of 12Cr18N9 steel surface by plasma pulses decreases intergranular corrosion susceptibility. It is related with structural changes of surface layer (∼ 20 μm), its enrichment by chromium and formation of chromium oxide protective film [ru

  3. Potential for ultrasonic inspection of heat exchanger tubes

    International Nuclear Information System (INIS)

    Ward, M.J.

    1980-01-01

    Preliminary results of a program to develop an ultrasonic inspection method for heat-exchanger tubes, to be used as alternative or complementary to eddy-curent testing were sufficiently promising to warrant further study. Problems were encountered in adapting a standard commercial transducer and a custom-made transducer to provide full 360 degree coverage of an area for in-service inspection, but it might be possible to overcome these problems. The results showed it might prove impossible to design a transducer to handle the tight U-bends in some heat exchangers. The most promising area of application for ultrasonic inspection was found to be around the tubesheet. (DN)

  4. Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark; Nellis, Greg; Corradini, Michael

    2012-10-19

    The objective of this project is to produce the necessary data to evaluate the performance of the supercritical carbon dioxide cycle. The activities include a study of materials compatibility of various alloys at high temperatures, the heat transfer and pressure drop in compact heat exchanger units, and turbomachinery issues, primarily leakage rates through dynamic seals. This experimental work will serve as a test bed for model development and design calculations, and will help define further tests necessary to develop high-efficiency power conversion cycles for use on a variety of reactor designs, including the sodium fast reactor (SFR) and very high-temperature gas reactor (VHTR). The research will be broken into three separate tasks. The first task deals with the analysis of materials related to the high-temperature S-CO{sub 2} Brayton cycle. The most taxing materials issues with regard to the cycle are associated with the high temperatures in the reactor side heat exchanger and in the high-temperature turbine. The system could experience pressures as high as 20MPa and temperatures as high as 650°C. The second task deals with optimization of the heat exchangers required by the S-CO{sub 2} cycle; the S-CO{sub 2} flow passages in these heat exchangers are required whether the cycle is coupled with a VHTR or an SFR. At least three heat exchangers will be required: the pre-cooler before compression, the recuperator, and the heat exchanger that interfaces with the reactor coolant. Each of these heat exchangers is unique and must be optimized separately. The most challenging heat exchanger is likely the pre-cooler, as there is only about a 40°C temperature change but it operates close to the CO{sub 2} critical point, therefore inducing substantial changes in properties. The proposed research will focus on this most challenging component. The third task examines seal leakage through various dynamic seal designs under the conditions expected in the S-CO{sub 2} cycle

  5. Investigation Status of Heat Exchange while Boiling Hydrocarbon Fuel

    Directory of Open Access Journals (Sweden)

    D. S. Obukhov

    2006-01-01

    Full Text Available The paper contains analysis of heat exchange investigations while boiling hydrocarbon fuel. The obtained data are within the limits of the S.S. Kutateladze dependence proposed in 1939. Heat exchange at non-stationary heat release has not been investigated. The data for hydrocarbon fuel with respect to critical density of heat flow are not available even for stationary conditions.

  6. Practical design of a heat exchanger for dilution refrigeration. 1

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Y; Fujii, G; Nagano, H [Tokyo Univ. (Japan). Inst. for Solid State Physics

    1978-02-01

    A compact heat exchanger for a dilution refrigerator with a high thermal efficiency is presented. Discrete heat exchangers with by-pass channels were used to decrease the flow impedance. This heat exchanger was designed so that the thermal conductance of liquid along the stream was greatly reduced. The effective thickness of the sponge material in the heat exchanger and mixer is also discussed. The obtained minimum temperatures of 12 mK was very close to the designed value of 10.8 mK. Moreover a rapid response was obtained. This is attributed to the small liquid volume of the heat exchanger.

  7. Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Konopacki Maciej

    2015-03-01

    Full Text Available The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.

  8. CFD simulation of air to air enthalpy heat exchanger

    International Nuclear Information System (INIS)

    Al-Waked, Rafat; Nasif, Mohammad Shakir; Morrison, Graham; Behnia, Masud

    2013-01-01

    Highlights: • A CFD model capable of modelling conjugate heat and mass transfer processes. • A mesh independence studies and a CFD model validation have been conducted. • Effects of flow direction on the effectiveness have been examined. • Performance parameters were sensible and latent effectiveness and pressure drop. - Abstract: A CFD model which supports conjugate heat and mass transfer problem representation across the membrane of air-to-air energy recovery heat exchangers has been developed. The model consists of one flow passage for the hot stream and another for the adjacent cold stream. Only half of each flow passage volume has been modelled on each side of the membrane surface. Three dimensional, steady state and laminar flow studies have been conducted using a commercial CFD package. The volumetric species transport model has been adopted to describe the H 2 O and air gas mixtures. Mesh dependency has been examined and followed by validation of the CFD model against published data. Furthermore, effects of flow direction at the inlet of the heat exchanger on its thermal effectiveness have been investigated. Simulation results are presented and analysed in terms of sensible effectiveness, latent effectiveness and pressure drop across the membrane heat exchanger. Results have shown that counter-flow configuration has greater sensitivity to the mesh centre perpendicular distance from the membrane when compared to the other two flow configurations (cross-/parallel-flow). However, the lateral mesh element length has shown minimal effect on the thermal effectiveness of the enthalpy heat exchanger. For the quasi-flow heat exchanger, a perpendicular flow direction to the inlets has been found to produce a higher performance in contrast to the non-perpendicular flow

  9. The log mean heat transfer rate method of heat exchanger considering the influence of heat radiation

    International Nuclear Information System (INIS)

    Wong, K.-L.; Ke, M.-T.; Ku, S.-S.

    2009-01-01

    The log mean temperature difference (LMTD) method is conventionally used to calculate the total heat transfer rate of heat exchangers. Because the heat radiation equation contains the 4th order exponential of temperature which is very complicate in calculations, thus LMTD method neglects the influence of heat radiation. From the recent investigation of a circular duct in some practical situations, it is found that even in the situation of the temperature difference between outer duct surface and surrounding is low to 1 deg. C, the heat radiation effect can not be ignored in the situations of lower ambient convective heat coefficient and greater surface emissivities. In this investigation, the log mean heat transfer rate (LMHTR) method which considering the influence of heat radiation, is developed to calculate the total heat transfer rate of heat exchangers.

  10. Design of a liquid metals heat exchanger

    International Nuclear Information System (INIS)

    Roffiel C, L.

    1976-01-01

    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)

  11. SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS

    Energy Technology Data Exchange (ETDEWEB)

    DR. DENNIS NAGLE; DR. DAJIE ZHANG

    2009-03-26

    Silicon carbide (SiC) materials are prime candidates for high temperature heat exchangers for next generation nuclear reactors due to their refractory nature and high thermal conductivity at elevated temperatures. This research has focused on demonstrating the potential of liquid silicon infiltration (LSI) for making SiC to achieve this goal. The major advantage of this method over other ceramic processing techniques is the enhanced capability of making high dense, high purity SiC materials in complex net shapes. For successful formation of net shape SiC using LSI techniques, the carbon preform reactivity and pore structure must be controlled to allow the complete infiltration of the porous carbon structure which allows complete conversion of the carbon to SiC. We have established a procedure for achieving desirable carbon properties by using carbon precursors consisting of two readily available high purity organic materials, crystalline cellulose and phenolic resin. Phenolic resin yields a glassy carbon with low chemical reactivity and porosity while the cellulose carbon is highly reactive and porous. By adjusting the ratio of these two materials in the precursor mixtures, the properties of the carbons produced can be controlled. We have identified the most favorable carbon precursor composition to be a cellulose resin mass ratio of 6:4 for LSI formation of SiC. The optimum reaction conditions are a temperature of 1800 C, a pressure of 0.5 Torr of argon, and a time of 120 minutes. The fully dense net shape SiC material produced has a density of 2.96 g cm{sup -3} (about 92% of pure SiC) and a SiC volume fraction of over 0.82. Kinetics of the LSI SiC formation process was studied by optical microscopy and quantitative digital image analysis. This study identified six reaction stages and provided important understanding of the process. Although the thermal conductivity of pure SiC at elevated temperatures is very high, thermal conductivities of most commercial Si

  12. SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS

    International Nuclear Information System (INIS)

    Nagle, Dennis; Zhang, Dajie

    2009-01-01

    Silicon carbide (SiC) materials are prime candidates for high temperature heat exchangers for next generation nuclear reactors due to their refractory nature and high thermal conductivity at elevated temperatures. This research has focused on demonstrating the potential of liquid silicon infiltration (LSI) for making SiC to achieve this goal. The major advantage of this method over other ceramic processing techniques is the enhanced capability of making high dense, high purity SiC materials in complex net shapes. For successful formation of net shape SiC using LSI techniques, the carbon preform reactivity and pore structure must be controlled to allow the complete infiltration of the porous carbon structure which allows complete conversion of the carbon to SiC. We have established a procedure for achieving desirable carbon properties by using carbon precursors consisting of two readily available high purity organic materials, crystalline cellulose and phenolic resin. Phenolic resin yields a glassy carbon with low chemical reactivity and porosity while the cellulose carbon is highly reactive and porous. By adjusting the ratio of these two materials in the precursor mixtures, the properties of the carbons produced can be controlled. We have identified the most favorable carbon precursor composition to be a cellulose resin mass ratio of 6:4 for LSI formation of SiC. The optimum reaction conditions are a temperature of 1800 C, a pressure of 0.5 Torr of argon, and a time of 120 minutes. The fully dense net shape SiC material produced has a density of 2.96 g cm -3 (about 92% of pure SiC) and a SiC volume fraction of over 0.82. Kinetics of the LSI SiC formation process was studied by optical microscopy and quantitative digital image analysis. This study identified six reaction stages and provided important understanding of the process. Although the thermal conductivity of pure SiC at elevated temperatures is very high, thermal conductivities of most commercial Si

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

    International Nuclear Information System (INIS)

    Yi Xiaowen; Lee, W.L.

    2009-01-01

    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

  14. Intensification of Evaporation and Condensation Processes in Heat Exchange Apparatus

    Directory of Open Access Journals (Sweden)

    L. L. Vasiliev

    2005-01-01

    Full Text Available The paper describes proposed design solutions for an intensification of heat transfer in evaporation and condensation heat exchangers. Complex experimental research of heat and mass transfer processes in flat and round cross-section miniature heat pipes is carried out. Optimization, development, manufacturing and an experimental investigation of copper miniature heat pipes with sintered powder are executed. Investigation results of capillary-porous structure properties that are used in evaporation and condensation heat-exchange apparatus are presented.

  15. New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

    International Nuclear Information System (INIS)

    Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

    2012-01-01

    A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

  16. LMFBR intermediate-heat-exchanger experience

    International Nuclear Information System (INIS)

    Cho, S.M.; Beaver, T.R.

    1983-01-01

    This paper presents developmental and operating experience of large Intermediate Heat Exchangers (IHX's) in US from the Fast Flux Test Facility (FFTF) to the Clinch River Breeder Reactor Plant (CRBRP) to the Large Development Plant (LDP). Design commonalities and deviations among these IHX's are synopsized. Various developmental tests that were conducted in the areas of hydraulic, structural and mechanical design are also presented. The FFTF is currently operating. Performance data of the FFTF IHXs are reviewed, and comparisons between actual and predicted performances are made. The results are used to assess the adequacy of IHX designs

  17. Heat exchanges between droplets and atmosphere

    International Nuclear Information System (INIS)

    Yadigaroglu, Georges.

    1975-01-01

    Data necessary for calculating the droplet cooling in wet cooling systems are surveyed. This cooling obeys the laws of simultaneous heat and mass transfer. Exchanges with a solid sphere moving inside a surrounding fluid medium are first examined. The corrections needed for taking into account various secondary effects (circulation in the droplet, lack of sphericity, oscillations, etc...) are then dealt with. Some data necessary for calculating the trajectories of the droplets and their behavior in a cooling system are included (diameter distribution, limit velocities, decay thresholds, etc...). Finally, calculation methods applying to spray systems, as well as wet towers broadly outlined [fr

  18. evaluation of total annual costs of heat exchanger networks using

    African Journals Online (AJOL)

    This study presents pinch analysis of some heat exchanger networks (HENs) problems using Hint integration (HINT) software. Three examples reported to have been solved using different approaches by various researchers to obtain the least possible total annual cost (TAC) were solved using the Hint software. In this work ...

  19. The study on water ingress mass in the steam generator heat-exchange tube rupture accident of modular high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Wang Yan; Shi Lei; Li Fu; Zheng Yanhua

    2012-01-01

    The steam generator heat-exchange tube rupture (SGTR) accident is an important and particular accident which will result in water ingress to the primary loop of reactor. Water ingress will result in chemical reaction of graphite fuel and structure with water, which may cause overpressure due to generation of explosive gaseous in large quantity. The study on the water ingress accident is significant for the verification of the inherent characteristics of high temperature gas-cooled reactor. The previous research shows that the amount of water ingress mass is the dominant key factor on the severity of the accident consequence. The 200 MWe high temperature gas-cooled reactor (HTR-PM), which is the first modular pebble-bed high temperature gas-cooled reactor in China designed by the Institute of Nuclear and New Energy Technology of Tsinghua University, is selected to be analyzed in this paper. The different DBA accident scenarios of double-ended break of single heat-exchange tube are simulated respectively by the thermal-hydraulic analysis code RETRAN-02. The results show the water ingress mass through the broken heat-exchange tube is related to the break location. The amount of water ingress mass is affected obviously by the capacity of the emptier system. With the balance of safety and economical efficiency, the amount of water ingress mass from the secondary side of steam generator into the primary coolant loop will be reduced by increasing properly the diameter of the draining lines. (authors)

  20. Shell and Double Concentric Tube Heat Exchanger Calculations and Analysis

    Directory of Open Access Journals (Sweden)

    Basma Abbas Abdulmajeed

    2015-01-01

    Full Text Available This study concerns a new type of heat exchangers, which is that of shell-and-double concentric tube heat exchangers. The case studies include both design calculations and performance calculations. The new heat exchanger design was conducted according to Kern method. The volumetric flow rates were 3.6 m3/h and 7.63 m3/h for the hot oil and water respectively. The experimental parameters studied were: temperature, flow rate of hot oil, flow rate of cold water and pressure drop. A comparison was made for the theoretical and experimental results and it was found that the percentage error for the hot oil outlet temperature was (- 1.6%. The percentage errors for the pressure drop in the shell and in the concentric tubes were (17.2% and (- 39% respectively. For cold water outlet temperature, the percentage error was (- 3.3%, while it was (18% considering the pressure drop in the annulus formed. The percentage error for the total power consumed was (-10.8% A theoretical comparison was made between the new design and the conventional heat exchanger from the point of view of, length, mass, pressure drop and total power consumed.

  1. Heat transfer pipe shielding device for heat exchanger

    International Nuclear Information System (INIS)

    Hanawa, Jun.

    1991-01-01

    The front face and the rear face of a frame that surrounds the circumference of the water chamber body of a multi-tube heat exchanger are covered by a rotational shielding plate. A slit is radially formed to the shielding plate for the insertion of a probe or cleaner to the heat transfer pipe and a deflector is disposed on the side opposite to the slit. The end of the heat transfer pipe to be inspected is exposed to the outer side by way of the slit by the rotation of the shielding plate, and the probe or cleaner is inserted in the heat transfer pipe to conduct an eddy current injury monitoring test or cleaning. The inside of the water chamber and the heat transfer pipe is exhausted by a ventilation nozzle disposed to the frame. Accordingly, a shielding effect upon inspection and cleaning can be obtained and, in addition, inspection and exhaustion at the cleaning position can be conducted easily. Since the operation for attachment and detachment is easy, the effect of reducing radiation dose per unit can be obtained by the shortening of the operation time. (N.H.)

  2. A heat exchanger analogy of automotive paint ovens

    International Nuclear Information System (INIS)

    Rao, Preetham P.

    2013-01-01

    Computational prediction of vehicle temperatures in an automotive paint oven is essential to predict paint quality and manufacturability. The complex geometry of vehicles, varying scales in the flow, transient nature of the process, and the tightly coupled conjugate heat transfer render the numerical models computationally very expensive. Here, a novel, simplified model of the oven is developed using an analogy to a three-stream cross flow heat exchanger that transfers heat from air to a series of moving bodies and supporting carriers. The analogous heat exchanger equations are developed and solved numerically. Steady state Computational Fluid Dynamics (CFD) simulations are carried out to model the flow field and to extract the heat transfer coefficients around the body and carriers. The air temperature distribution from the CFD models is used as a boundary condition in the analogous model. Correction coefficients are used in the analogy to take care of various assumptions. These are determined from existing test data. The same corrections are used to predict air temperatures for a modified configuration of the oven and a different vehicle. The method can be used to conduct control volume analysis of ovens to determine energy efficiency, and to study new vehicle or oven designs. -- Highlights: • Analogy of an automotive paint oven as a three stream cross flow heat exchanger. • The three streams are vehicle bodies, carriers and hot air. • Convection coefficients and inlet air stream temperatures from steady CFD simulations. • Analogy useful for overall energy efficiency analysis of conveyor ovens in general

  3. A Numerical Study on Using Air Cooler Heat Exchanger for Low Grade Energy Recovery from Exhaust Flue Gas in Natural Gas Pressure Reduction Stations

    OpenAIRE

    Mansoor Naderi; Ghasem Zargar; Ebrahim Khalili

    2018-01-01

    Heat EXchangers (HEX) that are used in City Gate Station (CGS) systems are modeled numerically to recover the exhaust waste heat. It was tried to find the best viscous model to obtain results in accordance with experimental results and to change the heat exchanger design. This HEX is used for recovering heat from exhaust flue gas with a mixture of 40% water and 60% ethylene glycol as the cooling fluid. Then, the effects of sizes and numbers of fins and tube rows on recovered heat rate were in...

  4. Bank of heat exchangers intended for liquid cooling or heating

    International Nuclear Information System (INIS)

    Veizman, Marcel; Swetchine, Denise.

    1975-01-01

    The invention concerns the heat exchangers cooling a significant volume of water, by straight natural air draught, such as the towers or the draught ducts of dry type air coolers. In a compact form, they enable water cooling problems to be solved in certain industrial installations such as isotope separation plants. The design of this bank of exchangers is also such that its cost is considerably diminished in relation to that of conventional banks. To this effect, this bank is composed of one or several rows of thin flexible plastic pockets forming as many water or other liquid sheets, connected to intake and discharge collectors and arranged one after the other and separated by air flow gaps. These pockets are suspended from one of their ends to hangers fixed to the assembly frame whilst restrictors prevent the pockets from swelling so avoiding any contact between them in order to maintain the air circulation gaps between them [fr

  5. Polymeric hollow fiber heat exchanger as an automotive radiator

    International Nuclear Information System (INIS)

    Krásný, Ivo; Astrouski, Ilya; Raudenský, Miroslav

    2016-01-01

    Highlights: • Polymeric hollow fiber heat exchanger as an automotive radiator is proposed. • The mechanism of heat transfer (HT) relies on diameter of polymeric hollow fiber. • Grimson equation is sufficient for approximate prediction of the heat transfers. - Abstract: Nowadays, different automotive parts (tubing, covers, manifolds, etc.) are made of plastics because of their superior characteristics, low weight, chemical resistance, reasonable price and several other aspects. Manufacturing technologies are already well-established and the application of plastics is proven. Following this trend, the production of compact and light all-plastic radiators seems reasonable. Two plastic heat exchangers were manufactured based on polypropylene tubes of diameter 0.6 and 0.8 mm (so-called fibers) and tested. The heat transfer performance and pressure drops were studied with hot (60 °C) ethyleneglycol-water brine flowing inside the fibers and air (20 °C) outside because these conditions are conventional for car radiator operation. It was observed that heat transfer rates (up to 10.2 kW), overall heat transfer coefficients (up to 335 W/m"2 K), and pressure drops are competitive to conventional aluminium finned-tube radiators. Moreover, influence of fiber diameter was studied. It was observed that air-side convective coefficients rise with a decrease of fiber diameter. Air-side pressure drops of plastic prototypes were slightly higher than of aluminium radiator but it is expected that additional optimization will eliminate this drawback. Experimentally obtained air-side heat transfer coefficients were compared with the theoretical prediction using the Grimson equation and the Churchill and Bernstein approach. It was found that the Grimson equation is sufficient for approximate prediction of the outer HTCs and can be used for engineering calculations. Further work will concentrate on optimizing and developing a polymeric hollow fiber heat exchanger with reduced size

  6. Inverse Problem and Variation Method to Optimize Cascade Heat Exchange Network in Central Heating System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yin; WEI Zhiyuan; ZHANG Yinping; WANG Xin

    2017-01-01

    Urban heating in northern China accounts for 40% of total building energy usage.In central heating systems,heat is often transfened from heat source to users by the heat network where several heat exchangers arc installed at heat source,substations and terminals respectively.For given overall heating capacity and heat source temperarure,increasing the terminal fluid temperature is an effective way to improve the thermal performance of such cascade heat exchange network for energy saving.In this paper,the mathematical optimization model of the cascade heat exchange network with three-stage heat exchangers in series is established.Aim at maximizing the cold fluid temperature for given hot fluid temperature and overall heating capacity,the optimal heat exchange area distribution and the medium fluids' flow rates are determined through inverse problem and variation method.The preliminary results show that the heat exchange areas should be distributed equally for each heat exchanger.It also indicates that in order to improve the thernmal performance of the whole system,more heat exchange areas should be allocated to the heat exchanger where flow rate difference between two fluids is relatively small.This work is important for guiding the optimization design of practical cascade heating systems.

  7. Intermediate heat exchanger project for Super Phenix

    International Nuclear Information System (INIS)

    Roumailhac, J.; Desir, D.

    1975-01-01

    The Super Phenix (1200 MWe) intermediate heat exchangers are derived directly from those of Phenix (250 MWe). The intermediate exchangers are housed in the reactor vessel annulus: as this annulus must be of the smallest volume possible, these IHX are required to work at a high specific rating. The exchange surface is calculated for nominal conditions. A range is then defined, consistent with the above requirements and throughout which the ratio between bundle thickness and bundle length remains acceptable. Experimental technics and calculations were used to determine the number of tube constraint systems required to keep the vibration amplitude within permissible limits. From a knowledge of this number, the pressure drop produced by the primary flow can be calculated. The bundle geometry is determined together with the design of the corresponding tube plates and the way in which these plates should be joined to the body of the IHX. The experience (technical and financial) acquired in the construction of Phenix is then used to optimize the design of the Super Phenix project. An approximate definition of the structure of the IHX is obtained by assuming a simplified load distribution in the calculations. More sophisticated calculations (e.g. finite element method) are then used to determine the behaviour of the different points of the IHX, under nominal and transient conditions

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

    Institute of Scientific and Technical Information of China (English)

    王芳; 郑茂余; 邵俊鹏; 李忠建

    2008-01-01

    Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established. In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the solar collector was employed to heating. Some of the soil heat exchangers were used to store solar energy in the soil so as to be used in next winter after this heating period; and the others were used to extract cooling energy directly in the soil by circulation pump for air conditioning in summer. After that solar energy began to be stored in the soil and ended before heating period. Three dimensional dynamic numerical simulations were built for soil and soil heat exchanger through finite element method. Simulation was done in different strata month by month. Variation and restoration of soil temperature were studied. Economy and reliability of long term SAGSHP system were revealed. It can be seen that soil temperature is about 3 ℃ higher than the original one after one year’s running. It is beneficial for the system to operate for long period.

  9. Laboratory simulation of heat exchange for liquids with Pr > 1: Heat transfer

    Science.gov (United States)

    Belyaev, I. A.; Zakharova, O. D.; Krasnoshchekova, T. E.; Sviridov, V. G.; Sukomel, L. A.

    2016-02-01

    Liquid metals are promising heat transfer agents in new-generation nuclear power plants, such as fast-neutron reactors and hybrid tokamaks—fusion neutron sources (FNSs). We have been investigating hydrodynamics and heat exchange of liquid metals for many years, trying to reproduce the conditions close to those in fast reactors and fusion neutron sources. In the latter case, the liquid metal flow takes place in a strong magnetic field and strong thermal loads resulting in development of thermogravitational convection in the flow. In this case, quite dangerous regimes of magnetohydrodynamic (MHD) heat exchange not known earlier may occur that, in combination with other long-known regimes, for example, the growth of hydraulic drag in a strong magnetic field, make the possibility of creating a reliable FNS cooling system with a liquid metal heat carrier problematic. There exists a reasonable alternative to liquid metals in FNS, molten salts, namely, the melt of lithium and beryllium fluorides (Flibe) and the melt of fluorides of alkali metals (Flinak). Molten salts, however, are poorly studied media, and their application requires detailed scientific substantiation. We analyze the modern state of the art of studies in this field. Our contribution is to answer the following question: whether above-mentioned extremely dangerous regimes of MHD heat exchange detected in liquid metals can exist in molten salts. Experiments and numerical simulation were performed in order to answer this question. The experimental test facility represents a water circuit, since water (or water with additions for increasing its electrical conduction) is a convenient medium for laboratory simulation of salt heat exchange in FNS conditions. Local heat transfer coefficients along the heated tube, three-dimensional (along the length and in the cross section, including the viscous sublayer) fields of averaged temperature and temperature pulsations are studied. The probe method for measurements in

  10. Entropy resistance minimization: An alternative method for heat exchanger analyses

    International Nuclear Information System (INIS)

    Cheng, XueTao

    2013-01-01

    In this paper, the concept of entropy resistance is proposed based on the entropy generation analyses of heat transfer processes. It is shown that smaller entropy resistance leads to larger heat transfer rate with fixed thermodynamic force difference and smaller thermodynamic force difference with fixed heat transfer rate, respectively. For the discussed two-stream heat exchangers in which the heat transfer rates are not given and the three-stream heat exchanger with prescribed heat capacity flow rates and inlet temperatures of the streams, smaller entropy resistance leads to larger heat transfer rate. For the two-stream heat exchangers with fixed heat transfer rate, smaller entropy resistance leads to larger effectiveness. Furthermore, it is shown that smaller values of the concepts of entropy generation numbers and modified entropy generation number do not always correspond to better performance of the discussed heat exchangers. - Highlights: • The concept of entropy resistance is defined for heat exchangers. • The concepts based on entropy generation are used to analyze heat exchangers. • Smaller entropy resistance leads to better performance of heat exchangers. • The applicability of entropy generation minimization is conditional

  11. Ventilation Heat Recovery from Wood-Burning Domestic Flues. A Theoretical Analysis Based on a Triple Concentric Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Lionel Druette

    2013-01-01

    Full Text Available This paper presents a new air-heating system concept for energy-efficient dwellings. It is a system designed to heat a low-energy building by coupling a heat-recovery ventilation system with a three-fluid heat exchanger located on the chimney of a wood-pellet stove. The proposed work focuses on the heat transfer that occurs between flue gases, the ventilation air and the combustion air within a triple concentric tube heat exchanger with no insulation at its outer surface. The main objective is to predict outlet temperature for the specific geometry of the heat exchanger studied here. Thus, the governing differential equations are derived for a counter-co-current flow arrangement of the three fluids. Then analytical solutions for the steady-state temperature distribution are obtained as well as the amount of heat transferred to the outside. An expression for the effectiveness of the heat exchanger is also proposed. Based on these results, calculations are performed on a case study to predict the fluid temperature distribution along the heat exchanger. Finally, a parametric study is carried out on this case study to assess the influence of the relevant parameters on the effectiveness of the heat exchanger. In addition, computation of heat losses to the outside justifies whether insulation is needed.

  12. Heat transfer entropy resistance for the analyses of two-stream heat exchangers and two-stream heat exchanger networks

    International Nuclear Information System (INIS)

    Cheng, XueTao; Liang, XinGang

    2013-01-01

    The entropy generation minimization method is often used to analyze heat transfer processes from the thermodynamic viewpoint. In this paper, we analyze common heat transfer processes with the concept of entropy generation, and propose the concept of heat transfer entropy resistance. It is found that smaller heat transfer entropy resistance leads to smaller equivalent thermodynamic force difference with prescribed heat transfer rate and larger heat transfer rate with prescribed equivalent thermodynamic force difference. With the concept of heat transfer entropy resistance, the performance of two-stream heat exchangers (THEs) and two-stream heat exchanger networks (THENs) is analyzed. For the cases discussed in this paper, it is found that smaller heat transfer entropy resistance always leads to better heat transfer performance for THEs and THENs, while smaller values of the entropy generation, entropy generation numbers and revised entropy generation number do not always. -- Highlights: • The concept of entropy resistance is defined. • The minimum entropy resistance principle is developed. • Smaller entropy resistance leads to better heat transfer

  13. Study the Effect of the Flow on the Performance of a shell and Tube Type Heat Exchanger using Experimental Design Technique

    Directory of Open Access Journals (Sweden)

    Zuher Hassan Abdullah

    2016-10-01

    Full Text Available In the current research an experimental study was done to show the effect of pulse flow on the effectiveness of shell and tube type heat exchanger. the study was in the case of steady and pulse flows with a changing mass flow rate of hot water flowing inside the pipes of the heat exchanger for the range between (0.0273-0.0819 kg / s  at fix mass flow rate of cold water that flows through the shell and on the outer surface of the pipes when (0.0416 kg / s, to obtain pulsing a used was solenoid valve. The research aims to measure the percentage effect of independent factors which were presenting the mass flow rate of hot water, flow type and the surrounding environment conditions of the experimental side upon shell and tube type heat exchanger performance using experimental design technique at the significant level (0.05.The results derived from the experimental tests showed that pulse flow leads to increase internal heat transfer coefficient (hi comparing with its value in the steady flow and the highest increase was by (9.75% at a mass flow rate of hot water (0.0416 kg / s and increases the overall heat transfer coefficient (U, where the highest percentage was by 4.68% at a mass flow rate of hot water (0.0416kg/s. The results also showed increasing both the number of transmitted units (NTU and the effectiveness of the shell and tube type heat exchanger ( in the case of pulse flow of its value in the steady flow and the highest percentage of increase occurring was (4.75% and (1.85%, respectively, and at the mass flow rate of hot water (0.0416 kg / s. Percentage effect of mass flow rate of hot water was (97%, 97.42%, 95.5%, 99.48% and the percentage effect of each flow type and the errors were (2.8%, 2.25%, 2.44%, 0.4% and (0. 2, 0.33%, 2.06%, 0.12 respectively

  14. A novel compact heat exchanger using gap flow mechanism.

    Science.gov (United States)

    Liang, J S; Zhang, Y; Wang, D Z; Luo, T P; Ren, T Q

    2015-02-01

    A novel, compact gap-flow heat exchanger (GFHE) using heat-transfer fluid (HTF) was developed in this paper. The detail design of the GFHE coaxial structure which forms the annular gap passage for HTF is presented. Computational fluid dynamics simulations were introduced into the design to determine the impacts of the gap width and the HTF flow rate on the GFHE performance. A comparative study on the GFHE heating rate, with the gap widths ranged from 0.1 to 1.0 mm and the HTF flow rates ranged from 100 to 500 ml/min, was carried out. Results show that a narrower gap passage and a higher HTF flow rate can yield a higher average heating rate in GFHE. However, considering the compromise between the GFHE heating rate and the HTF pressure drop along the gap, a 0.4 mm gap width is preferred. A testing loop was also set up to experimentally evaluate the GFHE capability. The testing results show that, by using 0.4 mm gap width and 500 ml/min HTF flow rate, the maximum heating rate in the working chamber of the as-made GFHE can reach 18 °C/min, and the average temperature change rates in the heating and cooling processes of the thermal cycle test were recorded as 6.5 and 5.4 °C/min, respectively. These temperature change rates can well satisfy the standard of IEC 60068-2-14:2009 and show that the GFHE developed in this work has sufficient heat exchange capacity and can be used as an ideal compact heat exchanger in small volume desktop thermal fatigue test apparatus.

  15. Air Circulation and Heat Exchange under Reduced Pressures

    Science.gov (United States)

    Rygalov, Vadim; Wheeler, Raymond; Dixon, Mike; Hillhouse, Len; Fowler, Philip

    Low pressure atmospheres were suggested for Space Greenhouses (SG) design to minimize sys-tem construction and re-supply materials, as well as system manufacturing and deployment costs. But rarified atmospheres modify heat exchange mechanisms what finally leads to alter-ations in thermal control for low pressure closed environments. Under low atmospheric pressures (e.g., lower than 25 kPa compare to 101.3 kPa for normal Earth atmosphere), convection is becoming replaced by diffusion and rate of heat exchange reduces significantly. During a period from 2001 to 2009, a series of hypobaric experiments were conducted at Space Life Sciences Lab (SLSLab) NASA's Kennedy Space Center and the Department of Space Studies, University of North Dakota. Findings from these experiments showed: -air circulation rate decreases non-linearly with lowering of total atmospheric pressure; -heat exchange slows down with pressure decrease creating risk of thermal stress (elevated leaf tem-peratures) for plants in closed environments; -low pressure-induced thermal stress could be reduced by either lowering system temperature set point or increasing forced convection rates (circulation fan power) within certain limits; Air circulation is an important constituent of controlled environments and plays crucial role in material and heat exchange. Theoretical schematics and mathematical models are developed from a series of observations. These models can be used to establish optimal control algorithms for low pressure environments, such as a space greenhouse, as well as assist in fundamental design concept developments for these or similar habitable structures.

  16. The computational optimization of heat exchange efficiency in stack chimneys

    Energy Technology Data Exchange (ETDEWEB)

    Van Goch, T.A.J.

    2012-02-15

    For many industrial processes, the chimney is the final step before hot fumes, with high thermal energy content, are discharged into the atmosphere. Tapping into this energy and utilizing it for heating or cooling applications, could improve sustainability, efficiency and/or reduce operational costs. Alternatively, an unused chimney, like the monumental chimney at the Eindhoven University of Technology, could serve as an 'energy channeler' once more; it can enhance free cooling by exploiting the stack effect. This study aims to identify design parameters that influence annual heat exchange in such stack chimney applications and optimize these parameters for specific scenarios to maximize the performance. Performance is defined by annual heat exchange, system efficiency and costs. The energy required for the water pump as compared to the energy exchanged, defines the system efficiency, which is expressed in an efficiency coefficient (EC). This study is an example of applying building performance simulation (BPS) tools for decision support in the early phase of the design process. In this study, BPS tools are used to provide design guidance, performance evaluation and optimization. A general method for optimization of simulation models will be studied, and applied in two case studies with different applications (heating/cooling), namely; (1) CERES case: 'Eindhoven University of Technology monumental stack chimney equipped with a heat exchanger, rejects heat to load the cold source of the aquifer system on the campus of the university and/or provides free cooling to the CERES building'; and (2) Industrial case: 'Heat exchanger in an industrial stack chimney, which recoups heat for use in e.g. absorption cooling'. The main research question, addressing the concerns of both cases, is expressed as follows: 'what is the optimal set of design parameters so heat exchange in stack chimneys is optimized annually for the cases in which a

  17. Alfa-Laval plate heat exchangers for the power industries

    International Nuclear Information System (INIS)

    Kitae, Junnosuke; Mtsuura, Kazuyuki

    1979-01-01

    Within power-generating plants, the transfer and conversion of heat energy of very large quantity are carried out in the process of energy conversion, accordingly the importance of heat exchangers is very high. Heretofore, multi-tube heat exchangers have been used mostly, but Alfa-Laval group developed the heat exchanger with very high efficiency to incorporate it effectively into a power-generating plant. In this plate type heat exchanger, the heat transfer efficiency is very high, and the quantity of stagnation is small as it is compact, consequently it is suitable to the secondary cooling for power-generating plant or the heat exchange of high-priced liquid heat media such as heavy water. Originally, plate type heat exchangers were used for food and chemical industries, therefore the prevention of mixing two liquids, sanitary construction, and corrosion resistance were required. Then they were adopted in iron and steel industry, and large thermal load, large heat transfer area and corrosion resistance to sea water were required. They were adopted in a nuclear power plant for the first time in 1964. In this heat exchanger, channels are formed with corrugated metal sheets, and titanium, stainless steels, Incoloy, Hastelloy and others are used as occasion demands. The Alfa-Laval heat exchangers and their features are explained. (Kako, I.)

  18. High Thermal Conductivity Polymer Composites for Low Cost Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-08-01

    This factsheet describes a project that identified and evaluated commercially available and state-of-the-art polymer-based material options for manufacturing industrial and commercial non-metallic heat exchangers. A heat exchanger concept was also developed and its performance evaluated with heat transfer modeling tools.

  19. Methods of designing and manufacturing a heat exchanger for the ...

    African Journals Online (AJOL)

    The article describes the method of calculation, design and manufacture of the the plate heat exchanger for the gas turbine plants with heat recovery. We represented the method of threedimensional calculation, which allowed conducting a virtual experiment and clarifying the design of the heat exchanger for the given ...

  20. THEORETICAL AND EXPERIMENTAL ANALYSIS OF A CROSS-FLOW HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    R. Tuğrul OĞULATA

    1996-03-01

    Full Text Available In this study, cross-flow plate type heat exchanger has been investigated because of its effective use in waste heat recovery systems. For this purpose, a heat regain system has been investigated and manufactured in laboratory conditions. Manufactured heat exchanger has been tested with an applicable experimental set up and temperatures, velocity of the air and the pressure losses occuring in the system have been measured and the efficiency of the system has been determined. The irreversibility of heat exchanger has been taken into consideration while the design of heat exchanger is being performed. So minimum entropy generation number has been analysied with respect to second law of thermodynamics in cross-flow heat exchanger. The minimum entropy generation number depends on parameters called optimum flow path length, dimensionless mass velocity and dimensionless heat transfer area. Variations of entropy generation number with these parameters have been analysied and introduced their graphics with their comments.

  1. Thermal Performance Analyses of Multiborehole Ground Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Wanjing Luo

    2017-01-01

    Full Text Available Geothermal energy known as a clean, renewable energy resource is widely available and reliable. Ground heat exchangers (GHEs can assist the development of geothermal energy by reducing the capital cost and greenhouse gas emission. In this paper, a novel semianalytical method was developed to study the thermal performance of multiborehole ground heat exchangers (GHEs with arbitrary configurations. By assuming a uniform inlet fluid temperature (UIFT, instead of uniform heat flux (UHF, the effects of thermal interference and the thermal performance difference between different boreholes can be examined. Simulation results indicate that the monthly average outlet fluid temperatures of GHEs will increase gradually while the annual cooling load of the GHEs is greater than the annual heating load. Besides, two mechanisms, the thermal dissipation and the heat storage effect, will determine the heat transfer underground, which can be further divided into four stages. Moreover, some boreholes will be malfunctioned; that is, boreholes can absorb heat from ground when the GHEs are under the cooling mode. However, as indicated by further investigations, this malfunction can be avoided by increasing borehole spacing.

  2. Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

    Science.gov (United States)

    Koplow, Jeffrey P.

    2016-02-16

    Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

  3. Improved spacers for high temperature gas-cooled heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Nordstroem, L A [Swiss Federal Institute for Reactor Research, Wuerenlingen (Switzerland)

    1984-07-01

    Experimental and analytical investigations in the field of heat exchanger thermohydraulics have been performed at EIR for many years, Basic studies have been carried out on heat transfer and pressure loss for tube bundles of different geometries and tube surfaces. As a part of this overall R+D programme for heat exchangers, investigations have been carried out on spacer pressure loss in bundles with longitudinal flow. An analytical spacer pressure loss model was developed which could handle different types of subchannel within the bundle. The model has been evaluated against experiments, using about 25 spacers of widely differing geometries. In a gas-cooled reactor it is important to keep the pressure loss over the primary circuit heat exchangers to a minimum. In exchangers with grid spacers these contribute a significant proportion of the overall bundle losses. For example, in the HHT Recuperator, with a shell-side pressure loss of 3.5 % of the inlet pressure, the spacers cause about one half of this loss. Reducing the loss to, say, 2.5 % results in an overall increase in plant efficiency by more than 1 % - a significant improvement Preliminary analysis identified 5 geometries in particular which were chosen for experimental evaluation as part of a joint project with the SULZER Company, to develop a low pressure-loss spacer for HHT heat exchangers (longitudinal counter-flow He/He and He/H{sub 2}O designs). The aim of the tests was to verify the low pressure-loss characteristics of these spacer grid types, as well as the quality of the results calculated by the computer code analytical model. The experimental and analytical results are compared in this report.

  4. Numerical Study on the Design Concept of an Air-Cooled Condensation Heat Exchanger in a Long-term Passive Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Moon, Joo Hyung; Bae, Youngmin; Kim, Young In; Park, Hyun Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Hee Joon [Kookmin University, Seoul (Korea, Republic of)

    2016-10-15

    SMART is the only licensed SMR in the world since the Nuclear Safety and Security Commission (NSSC) issued officially the Standard Design Approval (SDA) on 4 July 2012. Recently, the pre-project engineering (PPE) was officially launched for the construction of SMART and developing human resources capability. Both KAERI and King Abdullah City for Atomic and Renewable Energy (K.A. CARE) will conduct a three-year preliminary study to review the feasibility of building SMART and to prepare for its commercialization. SMART is equipped with passive cooling systems in order to enhance the safety of the reactor. The PRHRS (Passive Residual Heat Removal System) is the major passive safety system, which is actuated after an accident to remove the residual heat and the sensible heat from the RCS (Reactor Coolant System) through the steam generators (SGs) until the safe shutdown condition is reached. In this study, condensing heat transfer correlations in TSCON were validated using experimental data. It was shown that most of the condensation correlation gave satisfactory predictions of the cooling capacity of an-air cooled condensation heat exchanger.

  5. Numerical Study on the Design Concept of an Air-Cooled Condensation Heat Exchanger in a Long-term Passive Cooling System

    International Nuclear Information System (INIS)

    Kim, Myoung Jun; Moon, Joo Hyung; Bae, Youngmin; Kim, Young In; Park, Hyun Sik; Lee, Hee Joon

    2016-01-01

    SMART is the only licensed SMR in the world since the Nuclear Safety and Security Commission (NSSC) issued officially the Standard Design Approval (SDA) on 4 July 2012. Recently, the pre-project engineering (PPE) was officially launched for the construction of SMART and developing human resources capability. Both KAERI and King Abdullah City for Atomic and Renewable Energy (K.A. CARE) will conduct a three-year preliminary study to review the feasibility of building SMART and to prepare for its commercialization. SMART is equipped with passive cooling systems in order to enhance the safety of the reactor. The PRHRS (Passive Residual Heat Removal System) is the major passive safety system, which is actuated after an accident to remove the residual heat and the sensible heat from the RCS (Reactor Coolant System) through the steam generators (SGs) until the safe shutdown condition is reached. In this study, condensing heat transfer correlations in TSCON were validated using experimental data. It was shown that most of the condensation correlation gave satisfactory predictions of the cooling capacity of an-air cooled condensation heat exchanger

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

    Energy Technology Data Exchange (ETDEWEB)

    Vierow, Karen

    2005-08-29

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

  7. Overhaul of the heat exchanger in JRR-3

    International Nuclear Information System (INIS)

    Ouchi, Yasuhiro; Kawamata, Satoshi; Taguchi, Yuji; Kamiishi, Eigo; Koda, Nobuyuki

    2013-01-01

    In JRR-3, heat exchangers are installed in the cooling system equipment to remove the heat generated in the nuclear reactor, For the heat exchangers, overhaul inspection based on the JRR-3 reactor facility maintenance plan, as well as the inspection and maintenance based on reactor facility security provisions and JRR-3 operation guidelines are systematically conducted. Considering the results of overhaul inspection, the second overhaul inspection was applied to the primary coolant heat exchanger. The thinning of heat transfer tubes is within judgment standards with little effects of aging, which verified their soundness. From the fact that the effects of corrosion have been confirmed on the inside of the water chamber, repair work through overlay welding or the like is planned in the next overhaul. As for heavy water heat exchanger and the spent fuel pool water heat exchanger, it is planned to conduct the second overhaul inspection in FY2013 to confirm their soundness. (A.O.)

  8. Efek Perbedaan Jumlah dan Material Tube pada Distribusi Temperatur Tube Heat Exchanger dalam Kompor (Studi Kasus Di Industri Tempe Kecamatan Tenggilis Mejoyo Surabaya

    Directory of Open Access Journals (Sweden)

    Putu Angga Kristyawan

    2013-09-01

    Full Text Available Pemakaian heat exchanger pada kompor industri tempe di kelurahan Tenggilis Mejoyo Surabaya mengaplikasikan tube heat exchanger dengan jumlah tube 4 dan material tembaga. Pada pemakaian awal mampu memperlama penggunaan bahan bakar hingga 3 hari. Proses produksi heat exchanger memerlukan biaya hingga 2,5 juta rupiah. Untuk dapat mengatasi masalah tersebut maka dilakukan penelitian tentang performansi heat exchanger dengan memvariasikan material dan jumlah tube. Masalah ini disimulasikan dengan computational fluid dynamics. Simulasi dilakukan pada jumlah grid 388149 dan model turbulensi dengan nilai deviasi terhadap temperatur ukur sebesar 1,0%. Hasil penelitian menunjukkan bahwa performansi dengan jumlah tube 6 dan material besi memiliki performansi yang hanya berbeda sebesar 2395,188 Watt dan nilai temperatur keluaran hanya berbeda 2,338 K dengan 4 tube tembaga. Nilai investasi 6 tube besi juga lebih rendah dibandingkan dengan 4 tube tembaga senilai Rp 4.335.866,00 dan perbedaan nilai payback period hingga 4,22 bulan.

  9. A simplified fracture network model for studying the efficiency of a single well semi open loop heat exchanger in fractured crystalline rock

    Science.gov (United States)

    de La Bernardie, Jérôme; de Dreuzy, Jean-Raynald; Bour, Olivier; Thierion, Charlotte; Ausseur, Jean-Yves; Lesuer, Hervé; Le Borgne, Tanguy

    2016-04-01

    Geothermal energy is a renewable energy source particularly attractive due to associated low greenhouse gas emission rates. Crystalline rocks are in general considered of poor interest for geothermal applications at shallow depths (structure, heat exchanges and storage may be highlighted.

  10. Numerical investigation of conjugate heat transfer and flow performance of a fin and tube heat exchanger with vortex generators

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim

    2017-01-01

    Vortex generator is considered as an effective device for augmentation of the thermal-hydraulic performance of a heat exchanger. The aim of present study is to examine the influence of vortex generators on a double fin and tube heat exchanger performance. Vortex generator of rectangular winglet...

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

    International Nuclear Information System (INIS)

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

    2004-01-01

    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

  12. Investigation on copper alloy and titanium heat exchanger tubes behaviour in sea water service

    International Nuclear Information System (INIS)

    Casarini, G.; Bianchi, M.; Winkler, L.; Caspani, M.

    1982-01-01

    Because of the contradictory behaviour in service of some copper alloys used in heat exchangers cooled by sea water (Mediterranean Sea - North Africa), a comparative study on the behaviour of some tubular test samples was performed by means of accelerated test run ''in situ'' using two little heat exchangers supplied by Foster Wheeler Italiana. The aim of the investigation was to obtain quick and reliable information on optimizing the choise of the most suitable material for the construction of new heat exchangers

  13. Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

    International Nuclear Information System (INIS)

    Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon; Bae, Sung-Won; Kwon, Tae-Soon

    2015-01-01

    Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant

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

    International Nuclear Information System (INIS)

    Cheng Xue-Tao; Liang Xin-Gang

    2013-01-01

    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. (general)

  15. Determination of Ground Heat Exchangers Temperature Field in Geothermal Heat Pumps

    Science.gov (United States)

    Zhurmilova, I.; Shtym, A.

    2017-11-01

    For the heating and cooling supply of buildings and constructions geothermal heat pumps using low-potential ground energy are applied by means of ground exchangers. The process of heat transfer in a system of ground exchangers is a phenomenon of complex heat transfer. The paper presents a mathematical modeling of heat exchange processes, the temperature fields are built which are necessary for the determination of the ground array that ensures an adequate supply of low potential energy excluding the freezing of soil around the pipes in the ground heat exchangers and guaranteeing a reliable operation of geothermal heat pumps.

  16. Design Guideline for Primary Heat Exchanger in a Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sunil; Seo, Kyoung-Woo; Kim, Seong-Hoon; Chi, Dae-Young; Park, Cheol [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    In this paper, analytical study is conducted to track the variation of the PCS outlet temperature in conditions of the constant core power and constant SCS inlet temperature. The PCS circulates demineralized water to remove the heat generated in reactor core. The heat is transferred to the cold water of the SCS through the primary heat exchanger. In JRTR, Plate-type Heat Exchanger (PHE) was used as the primary heat exchanger. The cooling tower automatically sets the SCS inlet temperature constant by fan speed control. The flow rate of SCS is adjusted to be identical with the PCS flow rate. To design the PHE, the inlet and outlet temperatures and the flow rates for both systems should be determined. The flow rate has the allowable band for the safe operation from the lower limit to upper limit resulting in different temperature distribution in the PHE. Specially, the PCS outlet temperature which is the core inlet temperature is used for a safety parameter for the reactor shutdown. Therefore, we need to figure out which limit for the flow rate should be used from the conservative point of view. At 200 kg/s of PCS and SCS flow rates, the inlet and outlet temperatures are 41.3℃and 34℃, respectively. With increase of the flow rate, both of PCS inlet and outlet temperatures decrease to 33.6℃ and 39.9℃. This result means the low limit of the allowable flow band should be used for the conservative design of primary heat exchanger. If the upper limit of the allowable flow band is used, the PCS outlet temperature which is the safety parameter used for the reactor shutdown increases with decrease of the flow rate.

  17. Design Guideline for Primary Heat Exchanger in a Research Reactor

    International Nuclear Information System (INIS)

    Lee, Sunil; Seo, Kyoung-Woo; Kim, Seong-Hoon; Chi, Dae-Young; Park, Cheol

    2016-01-01

    In this paper, analytical study is conducted to track the variation of the PCS outlet temperature in conditions of the constant core power and constant SCS inlet temperature. The PCS circulates demineralized water to remove the heat generated in reactor core. The heat is transferred to the cold water of the SCS through the primary heat exchanger. In JRTR, Plate-type Heat Exchanger (PHE) was used as the primary heat exchanger. The cooling tower automatically sets the SCS inlet temperature constant by fan speed control. The flow rate of SCS is adjusted to be identical with the PCS flow rate. To design the PHE, the inlet and outlet temperatures and the flow rates for both systems should be determined. The flow rate has the allowable band for the safe operation from the lower limit to upper limit resulting in different temperature distribution in the PHE. Specially, the PCS outlet temperature which is the core inlet temperature is used for a safety parameter for the reactor shutdown. Therefore, we need to figure out which limit for the flow rate should be used from the conservative point of view. At 200 kg/s of PCS and SCS flow rates, the inlet and outlet temperatures are 41.3℃and 34℃, respectively. With increase of the flow rate, both of PCS inlet and outlet temperatures decrease to 33.6℃ and 39.9℃. This result means the low limit of the allowable flow band should be used for the conservative design of primary heat exchanger. If the upper limit of the allowable flow band is used, the PCS outlet temperature which is the safety parameter used for the reactor shutdown increases with decrease of the flow rate

  18. Micro tube heat exchangers for Space, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Mezzo fabricates micro tube heat exchangers for a variety of applications, including aerospace, automotive racing, Department of Defense ground vehicles, economizers...

  19. Performance variations of river water source heat pump system according to heat exchanger capacity variations

    International Nuclear Information System (INIS)

    Park, Seong Ryong; Baik, Young Jin; Lee, Young Soo; Kim, Hee Hwan

    2003-01-01

    The utilization of unused energy is important because it can afford to offer a chance to increase energy efficiency of a heat pump system. One of the promising unused energy sources is river water. It can be used as a heat source in both heating and cooling effectively with its superior features as a secondary working fluids. In this study, the performance of a 5HP heat pump system using river water as a heat source is investigated by both experiment and simulation. According to system simulation results, performance improvement of condenser seems more effective than that of evaporator for better COPH. The serial connection is also preferred among several methods to improve plate type heat exchanger performance. The experimental results show that the hot water of 50∼60 .deg. C can be acquired from water heat source of 5∼9 .deg. C with COPH of 2.7∼3.5

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

    Science.gov (United States)

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

    2016-06-01

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

  1. Experiments and simulations on heat exchangers in thermoelectric generator for automotive application

    International Nuclear Information System (INIS)

    Liu, X.; Deng, Y.D.; Zhang, K.; Xu, M.; Xu, Y.; Su, C.Q.

    2014-01-01

    In this work, an energy-harvesting system which extracts heat from an automotive exhaust pipe and turns the heat into electricity by using thermoelectric power generators (TEGs) was built. Experiments show that the temperature difference in automotive system is not constant, especially the heat exchanger, which cannot provide the thermoelectric modules (TMs) large amount of heat. The thermal performance of different heat exchangers in exhaust-based TEGs is studied in this work, and the thermal characteristics of heat exchangers with different internal structures and thickness are discussed, to obtain higher interface temperature and thermal uniformity. Following computational fluid dynamics simulations, infrared experiments and output power testing system are carried out on a high-performance production engine with a dynamometer. Results show that a plate-shaped heat exchanger with chaos-shaped internal structure and thickness of 5 mm achieves a relatively ideal thermal performance, which is practically useful to enhance the thermal performance of the TEG, and larger total output power can be thus obtained. - Graphical abstract: The thermal and electrical characteristics of different heat exchangers of automotive exhaust-based thermoelectric generator are discussed, to obtain higher interface temperature and thermal uniformity. - Highlights: • Different internal structures and thickness of heat exchangers were proposed. • Power output testing system of the two heat exchangers was characterized. • Chaos-shaped heat exchanger (5 mm thickness) shows better performance

  2. Application of nanofluids in plate heat exchanger: A review

    International Nuclear Information System (INIS)

    Kumar, Vikas; Tiwari, Arun Kumar; Ghosh, Subrata Kumar

    2015-01-01

    , based on experiments and numerical studies. A review of previous works featuring experimental and numerical investigations seems to be suggesting, to the level of establishing, that nanofluids have great potential in increasing the overall performance of the plate heat exchangers. There is a further vital scope to work on the performance and utility of nanofluids and work on the equative proportions of its application, in the direction, the paper has made an attempt of.

  3. Miniaturized Air-to-Refrigerant Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Radermacher, Reinhard [Univ. of Maryland, College Park, MD (United States); Bacellar, Daniel [Univ. of Maryland, College Park, MD (United States); Aute, Vikrant [Univ. of Maryland, College Park, MD (United States); Huang, Zhiwei [Univ. of Maryland, College Park, MD (United States); Hwang, Yunho [Univ. of Maryland, College Park, MD (United States); Ling, Jiazhen [Univ. of Maryland, College Park, MD (United States); Muehlbauer, Jan [Univ. of Maryland, College Park, MD (United States); Tancabel, James [Univ. of Maryland, College Park, MD (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Mingkan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-23

    Air-to-refrigerant Heat eXchangers (HX) are an essential component of Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) systems, serving as the main heat transfer component. The major limiting factor to HX performance is the large airside thermal resistance. Recent literature aims at improving heat transfer performance by utilizing enhancement methods such as fins and small tube diameters; this has lead to almost exhaustive research on the microchannel HX (MCHX). The objective of this project is to develop a miniaturized air-to-refrigerant HX with at least 20% reduction in volume, material volume, and approach temperature compared to current state-of-the-art multiport flat tube designs and also be capable of production within five years. Moreover, the proposed HX’s are expected to have good water drainage and should succeed in both evaporator and condenser applications. The project leveraged Parallel-Parametrized Computational Fluid Dynamics (PPCFD) and Approximation-Assisted Optimization (AAO) techniques to perform multi-scale analysis and shape optimization with the intent of developing novel HX designs whose thermal-hydraulic performance exceeds that of state-of-the-art MCHX. Nine heat exchanger geometries were initially chosen for detailed analysis, selected from 35+ geometries which were identified in previous work at the University of Maryland, College Park. The newly developed optimization framework was exercised for three design optimization problems: (DP I) 1.0kW radiator, (DP II) 10kW radiator and (DP III) 10kW two-phase HX. DP I consisted of the design and optimization of 1.0kW air-to-water HX’s which exceeded the project requirements of 20% volume/material reduction and 20% better performance. Two prototypes for the 1.0kW HX were prototyped, tested and validated using newly-designed airside and refrigerant side test facilities. DP II, a scaled version DP I for 10kW air-to-water HX applications, also yielded optimized HX designs

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

    Science.gov (United States)

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

    2017-02-01

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

  5. Numerical Simulation of Nanofluid Suspensions in a Geothermal Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Xiao-Hui Sun

    2018-04-01

    Full Text Available It has been shown that using nanofluids as heat carrier fluids enhances the conductive and convective heat transfer of geothermal heat exchangers. In this paper, we study the stability of nanofluids in a geothermal exchanger by numerically simulating nanoparticle sedimentation during a shut-down process. The nanofluid suspension is modeled as a non-linear complex fluid; the nanoparticle migration is modeled by a particle flux model, which includes the effects of Brownian motion, gravity, turbulent eddy diffusivity, etc. The numerical results indicate that when the fluid is static, the nanoparticle accumulation appears to be near the bottom borehole after many hours of sedimentation. The accumulated particles can be removed by the fluid flow at a relatively high velocity. These observations indicate good suspension stability of the nanofluids, ensuring the operational reliability of the heat exchanger. The numerical results also indicate that a pulsed flow and optimized geometry of the bottom borehole can potentially improve the suspension stability of the nanofluids further.

  6. Combined Steady-State and Dynamic Heat Exchanger Experiment

    Science.gov (United States)

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

    2009-01-01

    This paper describes a heat-transfer experiment that combines steady-state analysis and dynamic control. A process-water stream is circulated through two tube-in-shell heat exchangers in series. In the first, the process water is heated by steam. In the second, it is cooled by cooling water. The equipment is pilot-plant size: heat-transfer areas…

  7. A Liquid-Liquid Thermoelectric Heat Exchanger as a Heat Pump for Testing Phase Change Material Heat Exchangers

    Science.gov (United States)

    Sheth, Rubik B.; Makinen, Janice; Le, Hung V.

    2016-01-01

    The primary objective of the Phase Change HX payload on the International Space Station (ISS) is to test and demonstrate the viability and performance of Phase Change Material Heat Exchangers (PCM HX). The system was required to pump a working fluid through a PCM HX to promote the phase change material to freeze and thaw as expected on Orion's Multipurpose Crew Vehicle. Due to limitations on ISS's Internal Thermal Control System, a heat pump was needed on the Phase Change HX payload to help with reducing the working fluid's temperature to below 0degC (32degF). This paper will review the design and development of a TEC based liquid-liquid heat exchanger as a way to vary to fluid temperature for the freeze and thaw phase of the PCM HX. Specifically, the paper will review the design of custom coldplates and sizing for the required heat removal of the HX.

  8. Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger

    International Nuclear Information System (INIS)

    Chen, Minghui; Sun, Xiaodong; Christensen, Richard N.; Skavdahl, Isaac; Utgikar, Vivek; Sabharwall, Piyush

    2016-01-01

    Highlights: • Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger have been obtained. • Comparisons of experimental data and available correlations have been performed. • New Fanning friction factor and heat transfer correlations for the test PCHE are developed. - Abstract: Printed circuit heat exchanger (PCHE) is one of the leading intermediate heat exchanger (IHX) candidates to be employed in the very-high-temperature gas-cooled reactors (VHTRs) due to its capability for high-temperature, high-pressure applications. In the current study, a reduced-scale zigzag-channel PCHE was fabricated using Alloy 617 plates for the heat exchanger core and Alloy 800H pipes for the headers. The pressure drop and heat transfer characteristics of the PCHE were investigated experimentally in a high-temperature helium test facility (HTHF) at The Ohio State University. The PCHE helium inlet temperatures and pressures were varied up to 464 °C/2.7 MPa for the cold side and 802 °C/2.7 MPa for the hot side, respectively, while the maximum helium mass flow rates on both sides of the PCHE reached 39 kg/h. The corresponding maximum channel Reynolds number was approximately 3558, covering the laminar flow and laminar-to-turbulent flow transition regimes. New pressure drop and heat transfer correlations for the current zigzag channels with rounded bends were developed based on the experimental data. Comparisons between the experimental data and the results obtained from the available PCHE and straight circular pipe correlations were conducted. Compared to the heat transfer performance in straight circular pipes, the zigzag channels provided little advantage in the laminar flow regime but significant advantage near the transition flow regime.

  9. Evaluation methodology for advance heat exchanger concepts using analytical hierarchy process

    International Nuclear Information System (INIS)

    Sabharwall, Piyush; Kim, Eung Soo; Patterson, Mike

    2012-01-01

    This study describes how the major alternatives and criteria being developed for the heat exchangers for next generation nuclear reactors are evaluated using the analytical hierarchy process (AHP). This evaluation was conducted as an aid in developing and selecting heat exchangers for integrating power production and process heat applications with next generation nuclear reactors. The basic setup for selecting the most appropriate heat exchanger option was established with evaluation goals, alternatives, and criteria. The two potential candidates explored in this study were shell-and-tube (helical coiled) and printed circuit heat exchangers. Based on study results, the shell-and-tube (helical coiled) heat exchanger is recommended for a demonstration reactor in the near term, mainly because of its reliability.

  10. Lab-scale experiment of a closed thermochemical heat storage system including honeycomb heat exchanger

    International Nuclear Information System (INIS)

    Fopah-Lele, Armand; Rohde, Christian; Neumann, Karsten; Tietjen, Theo; Rönnebeck, Thomas; N'Tsoukpoe, Kokouvi Edem; Osterland, Thomas; Opel, Oliver

    2016-01-01

    A lab-scale thermochemical heat storage reactor was developed in the European project “thermal battery” to obtain information on the characteristics of a closed heat storage system, based on thermochemical reactions. The present type of storage is capable of re-using waste heat from cogeneration system to produce useful heat for space heating. The storage material used was SrBr 2 ·6H 2 O. Due to agglomeration or gel-like problems, a structural element was introduced to enhance vapour and heat transfer. Honeycomb heat exchanger was designed and tested. 13 dehydration-hydration cycles were studied under low-temperature conditions (material temperatures < 100 °C) for storage. Discharging was realized at water vapour pressure of about 42 mbar. Temperature evolution inside the reactor at different times and positions, chemical conversion, thermal power and overall efficiency were analysed for the selected cycles. Experimental system thermal capacity and efficiency of 65 kWh and 0.77 are respectively obtained with about 1 kg of SrBr 2 ·6H 2 O. Heat transfer fluid recovers heat at a short span of about 43 °C with an average of 22 °C during about 4 h, acceptable temperature for the human comfort (20 °C on day and 16 °C at night). System performances were obtained for a salt bed energy density of 213 kWh·m 3 . The overall heat transfer coefficient of the honeycomb heat exchanger has an average value of 147 W m −2  K −1 . Though promising results have been obtained, ameliorations need to be made, in order to make the closed thermochemical heat storage system competitive for space heating. - Highlights: • Lab-scale thermochemical heat storage is designed, constructed and tested. • The use of honeycomb heat exchanger as a heat and vapour process enhancement. • Closed system (1 kg SrBr 2 ·6H 2 O) able to give back 3/4 of initial thermal waste energy. • System storage capacity and thermal efficiency are respectively 65 kWh and 0.77.

  11. Supervision of the thermal performance of heat exchanger trains

    Energy Technology Data Exchange (ETDEWEB)

    Negrao, C.O.R.; Tonin, P.C.; Madi, M. [Federal University of Technology Parana UTFPR, Post-graduate Program in Mechanical and Materials Engineering PPGEM, Thermal Science Laboratory LACIT, Av. Sete de Setembro, 3165, CEP 80230-901, Curitiba, Parana (Brazil)

    2007-02-15

    In oil refining, heat exchanger networks are employed to recover heat and therefore save energy of the plant. However, many heat exchangers in crude oil pre-heat trains are under high risk of fouling. Under fouling conditions, the thermal performance of heat exchangers is continuously reduced and its supervision becomes an important task. The large number of heat exchangers in pre-heat trains and the change of operation conditions and feedstock charges make the daily supervision a difficult task. This work applies an approach to follow the performance of heat exchangers [M.A.S. Jeronimo, L.F. Melo, A.S. Braga, P.J.B.F. Ferreira, C. Martins, Monitoring the thermal efficiency of fouled heat exchangers - A simplified method, Experimental Thermal and Fluid Science 14 (1997) 455-463] and extends it to monitor the whole train. The approach is based on the comparison of measured and predicted heat exchanger effectiveness. The measured value is computed from the four inlet and outlet temperatures of a heat exchanger unit. The predicted clean and dirty values of effectiveness are calculated from classical literature relations as a function of NTU and of heat capacity ratio (R). NTU and R are continuously adjusted according to mass flow rate changes. An index of fouling is defined for the whole network and the results show the performance degradation of the network with time. The work also suggests that Jeronimo's index of fouling can be used to estimate the fouling thermal resistance of heat exchangers. (author)

  12. A Modified Entropy Generation Number for Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    This paper demonstrates the difference between the entropy generation number method proposed by Bejian and the method of entropy generation per unit amount of heat transferred in analyzing the ther-modynamic performance of heat exchangers,points out the reason for leading to the above difference.A modified entropy generation number for evaluating the irreversibility of heat exchangers is proposed which is in consistent with the entropy generation per unit amount of heat transferred in entropy generation analysis.The entropy generated by friction is also investigated.Results show that when the entropy generated by friction in heat exchangers in taken into account,there is a minimum total entropy generation number while the NTU and the ratio of heat capacity rates vary.The existence of this minimum is the prerequisite of heat exchanger optimization.

  13. Optimal synthesis of a heat-exchanger network

    Energy Technology Data Exchange (ETDEWEB)

    Hamed, O A; Aly, S [University of United Arab Emirates, Al-Ain (United Arab Emirates). Faculty of Engineering

    1991-01-01

    Thermodynamic, heat transfer and economic concepts influencing the synthesis of a heat-exchanger network (HEN) coupled to a crude fractionation unit are examined. The impact of the variation of the minimum temperature approach on energy and capital targets is studied using recent developments in pinch technology. The optimal pinch approach temperature has been determined using the 'supertargeting' concept where proper trade-off between energy and capital targets is observed prior to design. A heuristic evolutionary approach has then been used for the generation of the optimal HEN. (author).

  14. Flow analysis of an innovative compact heat exchanger channel geometry

    International Nuclear Information System (INIS)

    Vitillo, F.; Cachon, L.; Reulet, F.; Millan, P.

    2016-01-01

    Highlights: • An innovative compact heat transfer technology is proposed. • Experimental measurements are shown to validate the CFD model. • CFD simulations show various flow mechanisms. • Flow analysis is performed to study physical phenomena enhancing heat transfer. - Abstract: In the framework of CEA R&D program to develop an industrial prototype of sodium-cooled fast reactor named ASTRID, the present work aims to propose an innovative compact heat exchanger technology to provide solid technological basis for the utilization of a Brayton gas-power conversion system, in order to avoid the energetic sodium–water interaction if a traditional Rankine cycle was used. The aim of the present work is to propose an innovative compact heat exchanger channel geometry to potentially enhance heat transfer in such components. Hence, before studying the innovative channel performance, a solid experimental and numerical database is necessary to perform a preliminary thermal–hydraulic analysis. To do that, two experimental test sections are used: a Laser Doppler Velocimetry (LDV) test section and a Particle Image Velocimetry (PIV) test section. The acquired experimental database is used to validate the Anisotropic Shear Stress Transport (ASST) turbulence model. Results show a good agreement between LDV, PIV and ASST data for the pure aerodynamic flow. Once validated the numerical model, the innovative channel flow analysis is performed. Principal and secondary flow has been analyzed, showing a high swirling flow in the bend region and demonstrating that mixing actually occurs in the mixing zone. This work has to be considered as a step forward the preposition of a reliable high-performance component for application to ASTRID reactor as well as to any other industrial power plant dealing needing compact heat exchangers.

  15. On Chaotic Behavior of Temperature Distribution in a Heat Exchanger

    Science.gov (United States)

    Bagyalakshmi, Morachan; Gangadharan, Saisundarakrishnan; Ganesh, Madhu

    The objective of this paper is to introduce the notion of fractional derivatives in the energy equations and to study the chaotic nature of the temperature distribution in a heat exchanger with variation of temperature dependent transport properties. The governing fractional partial differential equations are transformed to a set of recurrence relations using fractional differential transform method and solved using inverse transform. The approximate analytical solution obtained by the proposed method has good agreement with the existing results.

  16. Thermo-aerodynamic efficiency of non-circular ducts with vortex enhancement of heat exchange in different types of compact heat exchangers

    Science.gov (United States)

    Vasilev, V. Ya; Nikiforova, S. A.

    2018-03-01

    Experimental studies of thermo-aerodynamic characteristics of non-circular ducts with discrete turbulators on walls and interrupted channels have confirmed the rational enhancement of convective heat transfer, in which the growth of heat transfer outstrips or equals the growth of aerodynamic losses. Determining the regularities of rational (energy-saving) enhancement of heat transfer and the proposed method for comparing the characteristics of smooth-channel (without enhancement) heat exchangers with effective analogs provide new results, confirming the high efficiency of vortex enhancement of convective heat transfer in non-circular ducts of plate-finned heat exchange surfaces. This allows creating heat exchangers with much smaller mass and volume for operation in energy-saving modes.

  17. Cyclic high temperature heat storage using borehole heat exchangers

    Science.gov (United States)

    Boockmeyer, Anke; Delfs, Jens-Olaf; Bauer, Sebastian

    2016-04-01

    The transition of the German energy supply towards mainly renewable energy sources like wind or solar power, termed "Energiewende", makes energy storage a requirement in order to compensate their fluctuating production and to ensure a reliable energy and power supply. One option is to store heat in the subsurface using borehole heat exchangers (BHEs). Efficiency of thermal storage is increasing with increasing temperatures, as heat at high temperatures is more easily injected and extracted than at temperatures at ambient levels. This work aims at quantifying achievable storage capacities, storage cycle times, injection and extraction rates as well as thermal and hydraulic effects induced in the subsurface for a BHE storage site in the shallow subsurface. To achieve these aims, simulation of these highly dynamic storage sites is performed. A detailed, high-resolution numerical simulation model was developed, that accounts for all BHE components in geometrical detail and incorporates the governing processes. This model was verified using high quality experimental data and is shown to achieve accurate simulation results with excellent fit to the available experimental data, but also leads to large computational times due to the large numerical meshes required for discretizing the highly transient effects. An approximate numerical model for each type of BHE (single U, double U and coaxial) that reduces the number of elements and the simulation time significantly was therefore developed for use in larger scale simulations. The approximate numerical model still includes all BHE components and represents the temporal and spatial temperature distribution with a deviation of less than 2% from the fully discretized model. Simulation times are reduced by a factor of ~10 for single U-tube BHEs, ~20 for double U-tube BHEs and ~150 for coaxial BHEs. This model is then used to investigate achievable storage capacity, injection and extraction rates as well as induced effects for

  18. Corrosion of heat exchanger materials under heat transfer conditions

    International Nuclear Information System (INIS)

    Tapping, R.L.; Lavoie, P.A.; Disney, D.J.

    1987-01-01

    Severe pitting has occurred in moderator heat exchangers tubed with Incoloy-800 in Pickering Nuclear Generating Station. The pitting originated on the cooling side (outside) of the tubes and perforation occurred in less than two years. It was known from corrosion testing at CRNL that Incoloy-800 was not susceptible to pitting in Lake Ontario water under isothermal conditions. Corrosion testing with heat transfer across the tube wall was carried out, and it was noted that severe pitting could occur under deposits formed on the tubes in silty Lake Ontario water. Subsequent testing, carried out in co-operation with Ontario Hydro Research Division, investigated the pitting resistance of other candidate tubing alloys: Incoloy-825, 904 L stainless steel, AL-6X, Inconel-625, 70:30 Cu:Ni, titanium, Sanicro-30 and Sanicro-28 1 . Of these, only titanium and Sanicro-28 have not suffered some degree of pitting attack in silt-containing Lake Ontario Water. In the absence of silt, and hence deposits, no pitting took place on any of the alloys tested

  19. Heat transfer analysis of underground U-type heat exchanger of ground source heat pump system.

    Science.gov (United States)

    Pei, Guihong; Zhang, Liyin

    2016-01-01

    Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions of a continuous and intermittent operation over 7 days on a GSHP with a single-well, single-U and double-U heat exchanger and the impact of single-U and double-U buried heat pipes on the surrounding rock-soil temperature field and the impact of intermittent operation and continuous operation on the outlet water temperature. The influence on the rock-soil temperature is approximately 13 % higher for the double-U heat exchanger than that of the single-U heat exchanger. The extracted energy of the intermittent operation is 36.44 kw·h higher than that of the continuous mode, although the running time is lower than that of continuous mode, over the course of 7 days. The thermal interference loss and quantity of heat exchanged for unit well depths at steady-state condition of 2.5 De, 3 De, 4 De, 4.5 De, 5 De, 5.5 De and 6 De of sidetube spacing are detailed in this work. The simulation results of seven working conditions are compared. It is recommended that the side-tube spacing of double-U underground pipes shall be greater than or equal to five times of outer diameter (borehole diameter: 180 mm).

  20. 40 CFR 63.1409 - Heat exchange system provisions.

    Science.gov (United States)

    2010-07-01

    ... detect leaks. (2)(i) For recirculating heat exchange systems (cooling tower systems), the monitoring of...-through heat exchange systems, the monitoring of speciated HAP or total HAP refers to the HAP listed in... operator shall maintain, at all times, the monitoring plan that is currently in use. The current plan shall...

  1. Leak detection in a high-pressure heat exchanger system in a refinery using radiotracer technique

    International Nuclear Information System (INIS)

    Samantray, J.S.; Sunil Goswami; Sharma, V.K.; Jayashree Biswal; Pant, H.J.

    2014-01-01

    A radiotracer investigation was carried out in a diesel hydrotreater (DHDT) unit in a refinery for leak detection in a breech-lock heat exchanger system. The main objectives of the study were to identify the leaking heat exchanger in a system with six heat exchangers and estimate the leak rate. Bromine-82 as dibromobiphenyl was selected and used as radiotracer for the investigation. The radiotracer was instantaneously injected into the suction end of the feed pump line to the heat exchanger of the DHDT unit. The movement of the tracer was measured at strategically selected locations using NaI(Tl) scintillation detectors. Based upon the results of the radiotracer investigation, it was found that out of six heat exchangers, exchanger E-1F was leaking. (author)

  2. Heat transfer and pressure drop amidst frost layer presence for the full geometry of fin-tube heat exchanger

    International Nuclear Information System (INIS)

    Kim, Sung Jool; Choi, Ho Jin; Ha, Man Yeong; Kim, Seok Ro; Bang, Seon Wook

    2010-01-01

    The present study numerically solves the flow and thermal fields in the full geometry of heat exchanger modeling with frost layer presence on the heat exchanger surface. The effects of air inlet velocity, air inlet temperature, frost layer thickness, fin pitch, fin thickness, and heat exchanger shape on the thermo-hydraulic performance of a fin-tube heat exchanger are investigated. Heat transfer rate rises with increasing air inlet velocity and temperature, and decreasing frost layer thickness and fin pitch. Pressure drop rises with increasing air inlet velocity and frost layer thickness, and decreasing fin pitch. The effect of fin thickness on heat transfer and pressure drop is negligible. Based on the present results, we derived the correlations, which express pressure drop and temperature difference between air inlet and outlet as a function of air inlet velocity and temperature, as well as frost layer thickness

  3. Functional design of heat exchange for pneumatic vehicles

    Science.gov (United States)

    Xu, Z. G.; Yang, D. Y.; Shen, W. D.; Liu, T. T.

    2017-10-01

    With the increasingly serious environmental problems, especially the impact of fog and haze, the development of air powered vehicles has become an important research direction of new energy vehicles. Quadrature test was done with different materials, i.e. stainless steel and aluminum alloy, at different inlet pressures, using different expansion gases, i.e. air, CO2, for heat exchanging properties for pneumatic vehicles. The mathematics as well as simulation methods are used to analyze the different heat exchanging effects in the multistage cylinder. The research results showed that the stainless steel has better effects in heat exchanging than Aluminum Alloy; the intake pressure has little effect on CO2 than the air in heat exchanging effect. CO2 is better in heat exchanging than air.

  4. The heat exchanger of small pellet boiler for phytomass

    Science.gov (United States)

    Mičieta, Jozef; Lenhard, Richard; Jandačka, Jozef

    2014-08-01

    Combustion of pellets from plant biomass (phytomass) causes various troubles. Main problem is slagging ash because of low melting temperature of ash from phytomass. This problem is possible to solve either improving energetic properties of phytomass by additives or modification of boiler construction. A small-scale boiler for phytomass is different in construction of heat exchanger and furnace mainly. We solve major problem - slagging ash, by decreasing combustion temperature via redesign of pellet burner and boiler body. Consequence of lower combustion temperature is also lower temperature gradient of combustion gas. It means that is necessary to design larger heat exchanging surface. We plane to use underfed burner, so we would utilize circle symmetry heat exchanger. Paper deals design of heat exchanger construction with help of CFD simulation. Our purpose is to keep uniform water flux and combustion gas flux in heat exchanger without zone of local overheating and excess cooling.

  5. Comparison and validation of dynamic characteristic analytical method for tubular heat exchanger

    International Nuclear Information System (INIS)

    Huang Qing; Xu Dinggeng; Chen Meng; Shen Rui

    2013-01-01

    In this study, the natural frequencies of Normal Residual Heat Removal Heat Exchangers are evaluated based on the beam and shell-beam finite element models. The corresponding results are compared and some discrepancies are observed. These discrepancies are analyzed in terms of the analysis of a cylindrical shell and the unreasonable treatment of boundary conditions is accordingly pointed out. The experimental data of the natural frequencies of heat exchangers used for Qinshan Phase Ⅰ Nuclear Power Plant are compared with the computational results from the shell-beam models for corresponding heat exchangers of C-2 program. The experimental and numerical results agree quite well, which implies that the shell-beam finite element simplification is applicable to the heat exchangers. The results indicate that the procedures introduced in this article apply to the dynamic analysis of other similar heat exchangers. (authors)

  6. Two-phase plate-fin heat exchanger modeling for waste heat recovery systems in diesel engines

    NARCIS (Netherlands)

    Feru, E.; Jager, de A.G.; Willems, F.P.T.; Steinbuch, M.

    2014-01-01

    This paper presents the modeling and model validation for a modular two-phase heat exchanger that recovers energy in heavy-duty diesel engines. The model is developed for temperature and vapor quality prediction and for control design of the waste heat recovery system. In the studied waste heat

  7. Explosive plugging of nuclear heat exchangers

    International Nuclear Information System (INIS)

    Crossland, B.; Bahrani, A.S.; Townsley, W.J.

    1977-01-01

    Explosive welding is a well established process for cladding one metal on another or for welding tubes to tubeplates or lap welding, etc. Recently, the process has been adapted to plugging of heat exchangers in conventional and nuclear power plant, where it has already been accepted especially in situations where the access is difficult and remote from the site of plugging. The paper describes the explosive plugging techniques developed in the Department of Mechanical and Industrial Engineering of The Queen's University of Belfast for the reheater and superheater of the PFR, and for the reheater of the AGR. For the PFR a point charge system has been used which causes a spherical expansion of the plug, which gives two zones of welding. Initially for the much larger plug required for the AGR it was proposed to use a parallel stand-off welding set-up, but it proved difficult or impossible to avoid a crevice. Consequently, a rim charge set-up has been developed which gives a circular ring expansion of the plug with two zones of welding. Besides the problem of the design of the plug and explosive charge geometry it has also been necessary to consider the distortion of holes adjoining the hole in which a plug is welded. Bunging of adjoining holes in order to reduce the distortion has also been investigated

  8. A numerical study on improving the thermal hydraulic performance of printed circuit heat exchanger using the supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Park, Bo Guen; Kim, Dae Hyun; Chung, Jin Taek [Dept. of Mechanical Engineering, Korea University, Seoul (Korea, Republic of)

    2015-10-15

    The objective of this study is to propose a new channel shape that improves thermal-hydraulic performance. The existing Zigzag channel has high pressure loss due to flow separation and reverse flow. To improve this disadvantage, partial straight channel is inserted into bended points. Also, the effects of straight channel's length change on heat transfer and pressure loss are analyzed. Thermal-hydraulic performance of the new shape and existing Zigzag channel are quantitatively compared in terms of Goodness Factor. Mass flow rate was changed from 1.41 x 10{sup -4} kg/s to 2.48 x 10{sup -4} kg/s . The average volume goodness factor of 1mm straight channel shape was increased by 25% compared to the Zigzag channel.

  9. Using a Potassium Acetate Solution for Cooling High Pressure Hydrogen in a Prototype Heat Exchanger

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Abel, M.; Rokni, Masoud

    2011-01-01

    is to be delivered at high pressure a heat exchanger was designed and constructed. The paper presents a detailed study of construction of the heat exchanger which has been tested and compared to theory to predict and verify its performance. The method presented by Nellis and Klein for laminar flow in annulus tubes...

  10. MATHEMATICAL MODELING OF UNSTEADY HEAT EXCHANGE IN A PASSENGER CAR

    Directory of Open Access Journals (Sweden)

    I. Yu. Khomenko

    2013-07-01

    Full Text Available Purpose.Existing mathematicalmodelsofunsteadyheatexchangeinapassengercardonotsatisfytheneedofthedifferentconstructivedecisionsofthelifesupportsystemefficiencyestimation. They also don’t allow comparing new and old life support system constructions influence on the inner environment conditions. Moreoverquite frequently unsteady heat exchange processes were studied at the initial car motion stage. Due to the new competitive engineering decisionsof the lifesupportsystemthe need of a new mathematical instrument that would satisfy the mentioned features and their influence on the unsteadyheatexchangeprocesses during the whole time of the road appeared. The purpose of this work is creation of the mathematicalmodel ofunsteadyheatexchangeinapassengercarthatcan satisfythe above-listed requirements. Methodology. Fortheassigned task realizationsystemofdifferentialequationsthatcharacterizesunsteadyheatexchangeprocessesinapassengercarwascomposed; forthesystemof equationssolution elementary balance method was used. Findings. Computational algorithm was developed andcomputer program for modeling transitional heat processes in the car was designed. It allows comparing different life support system constructions influence on the inner environment conditionsand unsteady heat exchange processes can be studied at every car motion stage. Originality.Mathematicalmodelofunsteadyheatexchangeinapassengercarwasimproved. That is why it can be used for the heat engineering studying of the inner car state under various conditions and for the operation of the different life support systems of passenger cars comparison. Mathematicalmodelingofunsteadyheatexchangeinapassengercarwas made by the elementary balance method. Practical value. Created mathematical model gives the possibility to simulate temperature changes in passenger car on unsteady thermal conditions with enough accuracy and to introduce and remove additional elements to the designed model. Thus different

  11. Plate heat exchangers in the power plant industry

    International Nuclear Information System (INIS)

    Wersel, M.; Ridell, B.

    1984-01-01

    An increase in heat transfer and stability, small investment, high flexibility, easy maintenance and corrosion resistance are obtained by the design and construction of plate heat exchangers and by the introduction of the herringbone pattern. The plate heat exchanger can be used in nearly 90% of all secondary circuits in powerstations. Examples of its installation are the WYLFA, GENTILLY, RINGHALS and TVO Finland nuclear power-stations. (DG) [de

  12. Numerical simulation of fluid flow and heat transfer in a concentric tube heat exchanger

    International Nuclear Information System (INIS)

    Mokamati, S.V.; Prasad, R.C.

    2003-01-01

    In this paper, numerical simulation of a concentric tube heat exchanger is presented to determine the convective heat transfer coefficient and friction factor in a smooth tube. Increasing the convective heat transfer coefficient can increase heat transfer rate in a concentric tube heat exchanger from a given tubular surface area. This can be achieved by using heat transfer augmentation devices. This work constitutes the initial phase of the numerical simulation of heat transfer from tubes employing augmentation devices, such as twisted tapes, wire-coil inserts, for heat transfer enhancement. A computational fluid dynamics (CFD) simulation tool was developed with CFX software and the results obtained from the simulations are validated with the empirical correlations for a smooth tube heat exchanger. The difficulties associated with the simulation of a heat exchanger augmented with wire-coil inserts are discussed. (author)

  13. Enhancement of plate heat exchanger performance using electric fields

    International Nuclear Information System (INIS)

    Down, E.M.

    2000-12-01

    The falling film plate evaporator is often used in the food processing industry to remove large amounts of water from liquids, pulps and slurries. Although a compact efficient device with high heat transfer rates, there is a requirement for even greater performance, particularly when fuelled by the low grade energy from many renewable sources. Electrohydrodynamics (EHD) has been shown to give large heat transfer enhancements under many conditions, but most of this previous research has been with working fluids having much lower electrical conductivities than the water-based fluids that are the main concern of this study. The liquid flow in falling film plate evaporators is in the form of a very thin (less than a millimetre) film falling down a heated plate under the effect of gravity. The film surface exhibits waviness over much of the operating range of industrial heat exchangers, and the degree of waviness has previously been shown to have a large effect on the rate of heat transfer. A theoretical model was developed which suggested that significant increases in waviness, and therefore heat transfer, could be stimulated using high voltage electrodes, and these were subsequently observed on the surface of a pool of water during bench-top experiments. An experimental falling film rig was designed to study this EHD effect but the 2.5 kV maximum voltage attainable was thought to be too low to stimulate wave enlargement and no heat transfer enhancement was seen. Significant heat transfer enhancement was observed in the falling film rig when utilising corona discharge electrodes. This was thought to be due to a thinning of the film in the vicinity of the electrode via the corona wind and increased fluid mixing downstream of the electrode. Both point and wire electrodes improved heat transfer rates but wire electrodes were thought to have more potential for integration into existing industrial heat exchanger designs, so were studied more closely. Heat transfer rates

  14. Air-side performance evaluation of three types of heat exchangers in dry, wet and periodic frosting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ping [Zhejiang Vocational College of Commerce, Hangzhou, Binwen Road 470 (China); Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 West Green Street, Urbana, IL 61801 (United States); Hrnjak, P.S. [Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 West Green Street, Urbana, IL 61801 (United States)

    2009-08-15

    The performances of three types of heat exchangers that use the louver fin geometry: (1) parallel flow parallel fin with extruded flat tubes heat exchanger (PF{sup 2}), (2) parallel flow serpentine fin with extruded flat tubes heat exchanger (PFSF) and (3) round tube wave plate fin heat exchanger (RTPF) have been experimentally studied under dry, wet and frost conditions and results are presented. The parameters quantified include air-side pressure drop, water retention on the surface of the heat exchanger, capacity and overall heat transfer coefficient for air face velocity 0.9, 2 and 3 m/s, air humidity 70% and 80% and different orientations. The performances of three types of heat exchanger are compared and the results obtained are presented. The condensate drainage behavior of the air-side surface of these three heat exchanger types was studied using both the dip testing method and wind tunnel experiment. (author)

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

    Science.gov (United States)

    Corbett, Robert J.; Miller, Barbara

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

  16. Performance of tubes-and plate fins heat exchangers

    International Nuclear Information System (INIS)

    Rosman, E.C.

    1979-11-01

    By means of a two-dimensional analysis performance, and using local heat transfer coefficients, the plate fin temperature distribution, the air bulk temperature along the stream path and the fin efficiency can be obtained, for several Reynolds numbers and fin materials. Herein are also presented the average heat transfer coefficients for isothermal plate fins, referring to heat exchangers with central-tube and rear-tube row and to two-row tubes heat exchangers configurations. It is possible to obtain the real tax or the real area of heat transfer, using the average hea transfer coefficients for isothermal plate fins and the fin efficiency. (Author) [pt

  17. An investigation on the role of thermal fins in the design of micro heat exchangers

    DEFF Research Database (Denmark)

    Omidvarnia, Farzaneh; Hansen, Hans Nørgaard; Sarhadi, Ali

    2015-01-01

    The different dominant physical phenomena in design for micro and macro scale products result in different design considerati ons for both categories. In the cu rrent study, a few design concepts are proposed as micro heat exchangers. In addition, the influential parameters on design of a micro...... heat exchanger in comparison with the effective factors in designing its macro counterpart ar e investigated. Numerical si mulations in the finite element software COMSOL are used to evaluate the thermal performance of both micro and macro heat exchangers. The result of the analysis reveals the fact...... that the presence of some features such as “fins ” in micro heat exchanger is n ot as significant as it is in macro scale. The results of this study can be employed as guidelines in design of similar micro heat exchangers....

  18. Water Based Phase Change Material Heat Exchanger Development

    Science.gov (United States)

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

    2014-01-01

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

  19. Heat Transfer and Entropy Generation Analysis of an Intermediate Heat Exchanger in ADS

    Science.gov (United States)

    Wang, Yongwei; Huai, Xiulan

    2018-04-01

    The intermediate heat exchanger for enhancement heat transfer is the important equipment in the usage of nuclear energy. In the present work, heat transfer and entropy generation of an intermediate heat exchanger (IHX) in the accelerator driven subcritical system (ADS) are investigated experimentally. The variation of entropy generation number with performance parameters of the IHX is analyzed, and effects of inlet conditions of the IHX on entropy generation number and heat transfer are discussed. Compared with the results at two working conditions of the constant mass flow rates of liquid lead-bismuth eutectic (LBE) and helium gas, the total pumping power all tends to reduce with the decreasing entropy generation number, but the variations of the effectiveness, number of transfer units and thermal capacity rate ratio are inconsistent, and need to analyze respectively. With the increasing inlet mass flow rate or LBE inlet temperature, the entropy generation number increases and the heat transfer is enhanced, while the opposite trend occurs with the increasing helium gas inlet temperature. The further study is necessary for obtaining the optimized operation parameters of the IHX to minimize entropy generation and enhance heat transfer.

  20. Integrated system of nuclear reactor and heat exchanger

    International Nuclear Information System (INIS)

    McDonald, B.N.; Schluderberg, D.C.

    1977-01-01

    The invention concerns PWRs in which the heat exchanger is associated with a pressure vessel containing the core and from which it can be selectively detached. This structural configuration applies to electric power generating uses based on land or on board ships. An existing reactor of this kind is fitted with a heat exchanger in which the tubes are 'U' shaped. This particular design of heat exchangers requires that the ends of the curved tubes be solidly maintained in a tube plate of great thickness, hence difficult to handle and to fabricate and requiring unconventional fine control systems for the control rods and awkward coolant pump arrangements. These complications limit the thermal power of the system to level below 100 megawatts. On the contrary, the object of this invention is to provide a one-piece PWR reactor capable of reaching power levels of 1500 thermal megawatts at least. For this, a pressure vessel is provided in the cylindrical assembly with not only a transversal separation on a plane located between the reactor and the heat exchanger but also a cover selectively detachable which supports the fine control gear of the control rods. Removing the cover exposes a part of the heat exchanger for easy inspection and maintenance. Further, the heat exchanger can be removed totally from the pressure vessel containing the core by detaching the cylindrical part, which composes the heat exchanger section, from the part that holds the reactor core on a level with the transversal separation [fr

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

    International Nuclear Information System (INIS)

    Honda, Ryosuke; Umekawa, Hisashi; Ozawa, Mamoru

    2009-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Ryosuke [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Umekawa, Hisashi [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)], E-mail: umekawa@kansai-uac.jp; Ozawa, Mamoru [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-06-21

    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.

  3. Heat transfer in plate heat exchanger channels: Experimental validation of selected correlation equations

    Directory of Open Access Journals (Sweden)

    Cieśliński Janusz T.

    2016-09-01

    Full Text Available This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx. The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.

  4. Numerical Analysis for Heat Transfer Characteristics of Elliptic Fin-Tube Heat Exchanger with Various Shapes

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hwan; Yoon, Jun Kyu [Gachon Univ., Seongnam (Korea, Republic of)

    2013-04-15

    In this study, the characteristics of the heat transfer coefficient and pressure drop were numerically analyzed according to the axis ratio (A R), pitch, location of vortex generator, and bump phase of the tube surface about an elliptical fin-tube heat exchanger. The boundary condition for CAD analysis was decided as a tube surface temperature of 348 K and inlet air velocity of 1.5 m/s. RCM 7th turbulent model was chosen as the numerical analysis for the sensitivity level. The analysis results indicated that the A R and transverse pitch decreased whereas the heat transfer coefficient increased. On the other hand, there was little difference in the longitudinal pitch. Furthermore, the heat transfer rate was more favorable when the vortex generator was located in front of the tube. Also, the bump phase of the tube surface indicated that the pressure drop and heat transfer were more favorable with the circle type than with the serrated type.

  5. The influence of heat exchanger design on the synthesis of heat exchanger networks

    Directory of Open Access Journals (Sweden)

    Liporace F.S.

    2000-01-01

    Full Text Available Heat exchanger network (HEN synthesis has been traditionally performed without accounting for a more detailed unit design, which is important since the final HEN may require unfeasible units. Recently, publications on this matter have appeared, as well as softwares that simultaneously perform synthesis and units design. However, these publications do not clearly show the influence of the new added features on the final HEN. Hence, this work aims at showing that units' design can strongly affect the final HEN. Improvements on heat transfer area and total annual cost estimations, which influence the HEN structural evolution, are the main responsible for that. It is also shown the influence of some design bounds settings, which can indicate an unfeasible unit design and, therefore, the need for a new match search or the maintenance of a loop. An example reported in the literature is used to illustrate the discussion.

  6. Simultaneous heat and mass transfer to air from a compact heat exchanger with water spray precooling and surface deluge cooling

    International Nuclear Information System (INIS)

    Zhang, Feini; Bock, Jessica; Jacobi, Anthony M.; Wu, Hailing

    2014-01-01

    Various methods are available to enhance heat exchanger performance with evaporative cooling. In this study, evaporative mist precooling, deluge cooling, and combined cooling schemes are examined experimentally and compared to model predictions. A flexible model of a compact, finned-tube heat exchanger with a wetted surface is developed by applying the governing conservation and rate equations and invoking the heat and mass transfer analogy. The model is applicable for dry, partially wet, or fully wet surface conditions and capable of predicting local heat/mass transfer, wetness condition, and pressure drop of the heat exchanger. Experimental data are obtained from wind tunnel experiments using a louver-fin flat-tube heat exchanger with single-phase tube-side flow. Total capacity, pressure drop, and water drainage behavior under various water usage rates and air face velocities are analyzed and compared to data for dry-surface conditions. A heat exchanger partitioning method for evaporative cooling is introduced to study partially wet surface conditions, as part of a consistent and general method for interpreting wet-surface performance data. The heat exchanger is partitioned into dry and wet portions by introducing a wet surface factor. For the wet part, the enthalpy potential method is used to determine the air-side sensible heat transfer coefficient. Thermal and hydraulic performance is compared to empirical correlations. Total capacity predictions from the model agree with the experimental results with an average deviation of 12.6%. The model is also exercised for four water augmentation schemes; results support operating under a combined mist precooling and deluge cooling scheme. -- Highlights: • A new spray-cooled heat exchanger model is presented and is validated with data. • Heat duty is shown to be asymptotic with spray flow rate. • Meaningful heat transfer coefficients for partially wet conditions are obtained. • Colburn j wet is lower than j dry

  7. Hydraulic Validation of the LHC Cold Mass Heat Exchanger Tube

    CERN Document Server

    Provenaz, P

    1998-01-01

    The knowledge of the helium mass flow vs. the fraction of the tube wetted by the liquid helium II in the heat exchanger is a crucial input parameter for the heat exchange since the heat flux is direct ly proportional to the wetted surface. In the range of liquid and gas velocities inside the heat exchanger, the liquid flow behaves like in an open channel. Looking at the flow equations for such a s ituation, the velocity depends on the fluid properties only by the friction factor which is a function of the Reynolds number. Thus it was decided to build an experiment with water in order to check t he open channel equations in the heat exchanger geometry. This paper shows the results for water and gives the extrapolation for helium.

  8. Heat transfer study of a two-phase refrigerant with liquid-solid phase change inside a smooth plates heat exchanger; Etude des transferts de chaleur d'un fluide frigoporteur diphasique a changement de phase liquide-solide dans un echangeur a plaques lisses

    Energy Technology Data Exchange (ETDEWEB)

    Demasles, H.

    2002-05-15

    The purpose of the work is to study two-phase mixture heat exchange composed of water particles suspended in silicone oil circulating in a closed loop. Water, contained in polymer porous matrix, is freezing by successive passages in plane plate heat exchanger. Thermo-hydraulic literature data analysis about these fluids in exchangers shows important blanks in exchange coefficient and pressure drop forecast methods and in experimental data. Experimental results, issued of global energy balance on a test section specifically conceived and made for this study, show doping effect on exchange coefficient. Before phase change, micro-convective effects of rotating particles improve exchange coefficient of 2,3 factor. Supplementary enhancement included between 2 and 16 appeared during phase change. Trial measured discrepancy are certainly induced by bed layer formation due to low flow speed. At the end of particle freezing, when latent heat is not involved anymore in exchange enhancement, important heat transfer reduction is observed. This is attributed to the cooling suspension rheological evolution and the change of flow particle distribution. Modelling results corroborate heat exchange improvement due to phase change: particles act as sources when discharging there latent heat. They stop fluid temperature dropping and enable to keep a high wall temperature gradient. A deepened suspension rheological study is necessary for a better understanding of observed phenomenon, nevertheless these first results show already an important energetic profit brings by particles in range temperature of 0 and -6 deg C. (author)

  9. EXPLOSION POTENTIAL ASSESSMENT OF HEAT EXCHANGER NETWORK AT THE PRELIMINARY DESIGN STAGE

    Directory of Open Access Journals (Sweden)

    MOHSIN PASHA

    2016-07-01

    Full Text Available The failure of Shell and Tube Heat Exchangers (STHE is being extensively observed in the chemical process industries. This failure can cause enormous production loss and have a potential of dangerous consequences such as an explosion, fire and toxic release scenarios. There is an urgent need for assessing the explosion potential of shell and tube heat exchanger at the preliminary design stage. In current work, inherent safety index based approach is used to resolve the highlighted issue. Inherent Safety Index for Shell and Tube Heat Exchanger (ISISTHE is a newly developed index for assessing the inherent safety level of a STHE at the preliminary design stage. This index is composed of preliminary design variables and integrated with the process design simulator (Aspen HYSYS. Process information can easily be transferred from process design simulator to MS Excel spreadsheet owing to this integration. This index could potentially facilitate the design engineer to analyse the worst heat exchanger in the heat exchanger network. Typical heat exchanger network of the steam reforming process is presented as a case study and the worst heat exchanger of this network has been identified. It is inferred from this analysis that shell and tube heat exchangers possess high operating pressure, corrected mean temperature difference (CMTD and flammability and reactive potential needs to be critically analysed at the preliminary design stage.

  10. Soil temperature distribution around a U-tube heat exchanger in a multi-function ground source heat pump system

    International Nuclear Information System (INIS)

    Li Shuhong; Yang Weihua; Zhang Xiaosong

    2009-01-01

    The imbalance of heat extracted from the earth by the underground heat exchangers in winter and ejected into it in summer is expected to affect the long term performance of conventional ground source heat pump (GSHP) in territories with a cold winter and a warm summer such as the middle and downstream areas of the Yangtze River in China. This paper presents a new multi-function ground source heat pump (MFGSHP) system which supplies hot water as well as space cooling/heating to mitigate the soil imbalance of the extracted and ejected heat by a ground source heat pump system. The heat transfer characteristic is studied and the soil temperature around the underground heat exchangers are simulated under a typical climatic condition of the Yangtze River. A three-dimensional model was constructed with the commercial computational fluid dynamics software FLUENT based on the inner heat source theory. Temperature distribution and variation trend of a tube cluster of the underground heat exchanger are simulated for the long term performance. The results show that the soil temperature around the underground tube keeps increasing due to the surplus heat ejected into the earth in summer, which deteriorates the system performance and may lead to the eventual system deterioration. The simulation shows that MFGSHP can effectively alleviate the temperature rise by balancing the heat ejected to/extracted from underground by the conventional ground source heat pump system. The new system also improves the energy efficiency.

  11. Heat Exchangers for Utilization of the Heat of High-Temperature Geothermal Brines

    Science.gov (United States)

    Alkhasov, A. B.; Alkhasova, D. A.

    2018-03-01

    The basic component of two-circuit geothermal systems is the heat exchanger. When used in geothermal power systems, conventional shell-and-tube and plate heat exchangers cause problems related to the cleaning of the latter from salt-deposition and corrosion products. Their lifetime does not exceed, as a rule, 1 year. To utilize the heat of high-temperature geothermal brines, a heat exchanger of the "tube-in-tube" type is proposed. A heat exchanger of this design has been operated for several years in Ternair geothermal steam field; in this heat exchanger, the thermal potential of the saline thermal water is transferred to the fresh water of the secondary circuit of the heating system for apartment houses. The reduction in the weight and size characteristics of the heat exchangers is a topical problem that can be solved with the help of heat transfer enhancers. To enhance the heat transfer process in the heat exchanger, longitudinal ribbing of the heat exchange surface is proposed. The increase in the heat exchange surface from the heat carrier side by ribbing results in an increase in the amount of the heat transferred from the heating agent. The heat exchanger is easy to manufacture and is assembled out of components comprised of two concentrically positioned tubes of a definite length, 3-6 m, serially connected with each other. The method for calculation of the impact of the number and the size of the longitudinal ribs on the heat transfer in the well heat exchanger is presented and a criterion for the selection of the optimal number and design parameters of the ribs is formulated. To prevent the corrosion and salt deposition in the heat exchanger, the use of an effective OEDFK (oxyethylidenediphosphonic acid) agent is proposed. This agent has a long-lasting corrosion-inhibiting and antiscaling effect, which is explained by the formation of a strongly adhesive chelate layer difficult to wash off the surface. The passivating OEDFK layer is restored by periodical

  12. Heat exchanger with dirt separator for the use of the heat energy of waste water

    Energy Technology Data Exchange (ETDEWEB)

    1975-11-13

    Well-known heat exchanger systems consist of separate heat exchangers and dirt separators. In the case here in question both devices form a unit. A finned tube heat exchanger is positioned in the center of the dirt separator and is given extra protection through deflection sheets. A safety overflow is supplied so that no residue can appear in the waste water line when decanting.

  13. Design and economic optimization of shell and tube heat exchangers using Artificial Bee Colony (ABC) algorithm

    International Nuclear Information System (INIS)

    Sencan Sahin, Arzu; Kilic, Bayram; Kilic, Ulas

    2011-01-01

    Highlights: → Artificial Bee Colony for shell and tube heat exchanger optimization is used. → The total cost is minimized by varying design variables. → This new approach can be applied for optimization of heat exchangers. - Abstract: In this study, a new shell and tube heat exchanger optimization design approach is developed. Artificial Bee Colony (ABC) has been applied to minimize the total cost of the equipment including capital investment and the sum of discounted annual energy expenditures related to pumping of shell and tube heat exchanger by varying various design variables such as tube length, tube outer diameter, pitch size, baffle spacing, etc. Finally, the results are compared to those obtained by literature approaches. The obtained results indicate that Artificial Bee Colony (ABC) algorithm can be successfully applied for optimal design of shell and tube heat exchangers.

  14. Design and economic optimization of shell and tube heat exchangers using Artificial Bee Colony (ABC) algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Sencan Sahin, Arzu, E-mail: sencan@tef.sdu.edu.tr [Department of Mechanical Education, Technical Education Faculty, Sueleyman Demirel University, 32260 Isparta (Turkey); Kilic, Bayram, E-mail: bayramkilic@hotmail.com [Bucak Emin Guelmez Vocational School, Mehmet Akif Ersoy University, Bucak (Turkey); Kilic, Ulas, E-mail: ulaskilic@mehmetakif.edu.tr [Bucak Emin Guelmez Vocational School, Mehmet Akif Ersoy University, Bucak (Turkey)

    2011-10-15

    Highlights: {yields} Artificial Bee Colony for shell and tube heat exchanger optimization is used. {yields} The total cost is minimized by varying design variables. {yields} This new approach can be applied for optimization of heat exchangers. - Abstract: In this study, a new shell and tube heat exchanger optimization design approach is developed. Artificial Bee Colony (ABC) has been applied to minimize the total cost of the equipment including capital investment and the sum of discounted annual energy expenditures related to pumping of shell and tube heat exchanger by varying various design variables such as tube length, tube outer diameter, pitch size, baffle spacing, etc. Finally, the results are compared to those obtained by literature approaches. The obtained results indicate that Artificial Bee Colony (ABC) algorithm can be successfully applied for optimal design of shell and tube heat exchangers.

  15. Heat transfer enhancement in cross-flow heat exchanger using vortex generator

    International Nuclear Information System (INIS)

    Yoo, S. Y.; Kwon, H. K.; Kim, B. C.; Park, D. S.; Lee, S. S.

    2003-01-01

    Fouling is very serious problem in heat exchanger because it rapidly deteriorates the performance of heat exchanger. Cross-flow heat exchanger with vortex generators is developed, which enhance heat transfer and reduce fouling. In the present heat exchanger, shell and baffle are removed from the conventional shell-and-tube heat exchanger. The naphthalene sublimation technique is employed to measure the local heat transfer coefficients. The experiments are performed for single circular tube, staggered array tube bank and in-line array tube bank with and without vortex generators. Local and average Nusselt numbers of single tube and tube bank with vortex generator are investigated and compared to those of without vortex generator

  16. Low Cost Polymer heat Exchangers for Condensing Boilers

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Thomas [Brookhaven National Lab. (BNL), Upton, NY (United States); Trojanowski, Rebecca [Brookhaven National Lab. (BNL), Upton, NY (United States); Wei, George [Brookhaven National Lab. (BNL), Upton, NY (United States); Worek, Michael [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-30

    Work in this project sought to develop a suitable design for a low cost, corrosion resistant heat exchanger as part of a high efficiency condensing boiler. Based upon the design parameters and cost analysis several geometries and material options were explored. The project also quantified and demonstrated the durability of the selected polymer/filler composite under expected operating conditions. The core material idea included a polymer matrix with fillers for thermal conductivity improvement. While the work focused on conventional heating oil, this concept could also be applicable to natural gas, low sulfur heating oil, and biodiesel- although these are considered to be less challenging environments. An extruded polymer composite heat exchanger was designed, built, and tested during this project, demonstrating technical feasibility of this corrosion-resistant material approach. In such flue gas-to-air heat exchangers, the controlling resistance to heat transfer is in the gas-side convective layer and not in the tube material. For this reason, the lower thermal conductivity polymer composite heat exchanger can achieve overall heat transfer performance comparable to a metal heat exchanger. However, with the polymer composite, the surface temperature on the gas side will be higher, leading to a lower water vapor condensation rate.

  17. EVALUASI KINERJA HEAT EXCHANGER DENGAN METODE FOULING F

    Directory of Open Access Journals (Sweden)

    Bambang Setyoko

    2012-02-01

    Full Text Available The performance of heat exchangers usually deteriorates with time as a result of accumulation of depositson heat transfer surfaces. The layer of deposits represents additional resistance to heat transfer and causesthe rate of heat transfer in a heat exchanger to decrease. The net effect of these accumulations on heattransfer is represented by a fouling factor Rf , which is a measure of the thermal resistance introduced byfouling.In this case, the type of fouling is the precipitation of solid deposits in a fluid on the heat transfer surface.The mineral deposits forming on the inner and the outer surfaces of fine tubes in the heat exchanger. Thefouling factor is increases with time as the solid deposits build up on the heat exchanger surface. Foulingincreases with increasing temperature and decreasing velocity.In this research, we obtain the coefisien clean overal 5,93 BTU/h.ft2.oF, Dirt factor 0,004 BTU/h.ft2 0F,Pressure drope in tube 2,84 . 10-3 Psi and pressure drope in shell 4,93 . 10-4 Psi.This result are less thanthe standard of parameter. Its means this Heat exchanger still clean relativity and can operate continousslywithout cleaning.

  18. Fouling reduction characteristics of a no-distributor-fluidized-bed heat exchanger for flue gas heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Y.D.; Lee, K.B.; Islam, S.Z.; Ko, S.B. [Kongju National University, Kong Ju (Republic of Korea). Dept. for Mechanical Engineering

    2008-07-01

    In conventional flue gas heat recovery systems, the fouling by fly ashes and the related problems such as corrosion and cleaning are known to be major drawbacks. To overcome these problems, a single-riser no-distributor-fluidized-bed heat exchanger is devised and studied. Fouling and cleaning tests are performed for a uniquely designed fluidized bed-type heat exchanger to demonstrate the effect of particles on the fouling reduction and heat transfer enhancement. The tested heat exchanger model (1 m high and 54 mm internal diameter) is a gas-to-water type and composed of a main vertical tube and four auxiliary tubes through which particles circulate and transfer heat. Through the present study, the fouling on the heat transfer surface could successfully be simulated by controlling air-to-fuel ratios rather than introducing particles through an external feeder, which produced soft deposit layers with 1 to 1.5 mm thickness on the inside pipe wall. Flue gas temperature at the inlet of heat exchanger was maintained at 450{sup o}C at the gas volume rate of 0.738 to 0.768 CMM (0.0123 to 0.0128 m{sup 3}/sec). From the analyses of the measured data, heat transfer performances of the heat exchanger before and after fouling and with and without particles were evaluated. Results showed that soft deposits were easily removed by introducing glass bead particles, and also heat transfer performance increased two times by the particle circulation. In addition, it was found that this type of heat exchanger had high potential to recover heat of waste gases from furnaces, boilers, and incinerators effectively and to reduce fouling related problems.

  19. Thermal design heat sinks, thermoelectrics, heat pipes, compact heat exchangers, and solar cells

    CERN Document Server

    Lee, H S

    2010-01-01

    The proposed is written as a senior undergraduate or the first-year graduate textbook,covering modern thermal devices such as heat sinks, thermoelectric generators and coolers, heat pipes, and heat exchangers as design components in larger systems. These devices are becoming increasingly important and fundamental in thermal design across such diverse areas as microelectronic cooling, green or thermal energy conversion, and thermal control and management in space, etc. However, there is no textbook available covering this range of topics. The proposed book may be used as a capstone design cours

  20. Thermal Sizing of Heat Exchanger Tubes for Air Natural Convective Cooling System of Emergency Cooling Tank

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Moon, Joo Hyung; Bae, Youngmin; Kim, Youngin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    For the long operation of secondary passive cooling system, however, water level goes down by evaporation in succession at emergency cooling tank. At the end there would be no place to dissipate heat from condensation heat exchanger. Therefore, steam cooling heat exchanger is put on the top of emergency cooling tank to maintain appropriate water level by collecting evaporating steam. Steam cooling heat exchanger is installed inside an air chimney and evaporated steam is cooled down by air natural convection. In this study, thermal sizing of steam cooling heat exchanger under air natural convection was conducted by TSCON program for the design of experimental setup as shown in Fig. 2. Thermal sizing of steam cooling heat exchanger tube under air natural convection was conducted by TSCON program for the design of experimental setup. 25 - 1' tubes which has a length 1687 mm was determined as steam cooling heat exchanger at 2 kW heat load and 100 liter water pool in emergency cooling tank (experimental limit condition). The corresponding width of two tubes is 50 mm and has 5 by 5 tube array for heat exchanger.

  1. Thermal Sizing of Heat Exchanger Tubes for Air Natural Convective Cooling System of Emergency Cooling Tank

    International Nuclear Information System (INIS)

    Kim, Myoung Jun; Lee, Hee Joon; Moon, Joo Hyung; Bae, Youngmin; Kim, Youngin

    2014-01-01

    For the long operation of secondary passive cooling system, however, water level goes down by evaporation in succession at emergency cooling tank. At the end there would be no place to dissipate heat from condensation heat exchanger. Therefore, steam cooling heat exchanger is put on the top of emergency cooling tank to maintain appropriate water level by collecting evaporating steam. Steam cooling heat exchanger is installed inside an air chimney and evaporated steam is cooled down by air natural convection. In this study, thermal sizing of steam cooling heat exchanger under air natural convection was conducted by TSCON program for the design of experimental setup as shown in Fig. 2. Thermal sizing of steam cooling heat exchanger tube under air natural convection was conducted by TSCON program for the design of experimental setup. 25 - 1' tubes which has a length 1687 mm was determined as steam cooling heat exchanger at 2 kW heat load and 100 liter water pool in emergency cooling tank (experimental limit condition). The corresponding width of two tubes is 50 mm and has 5 by 5 tube array for heat exchanger

  2. A lumped parameter, low dimension model of heat exchanger

    International Nuclear Information System (INIS)

    Kanoh, Hideaki; Furushoo, Junji; Masubuchi, Masami

    1980-01-01

    This paper reports on the results of investigation of the distributed parameter model, the difference model, and the model of the method of weighted residuals for heat exchangers. By the method of weighted residuals (MWR), the opposite flow heat exchanger system is approximated by low dimension, lumped parameter model. By assuming constant specific heat, constant density, the same form of tube cross-section, the same form of the surface of heat exchange, uniform flow velocity, the linear relation of heat transfer to flow velocity, liquid heat carrier, and the thermal insulation of liquid from outside, fundamental equations are obtained. The experimental apparatus was made of acrylic resin. The response of the temperature at the exit of first liquid to the variation of the flow rate of second liquid was measured and compared with the models. The MWR model shows good approximation for the low frequency region, and as the number of division increases, good approximation spreads to higher frequency region. (Kato, T.)

  3. Multiple pollutant removal using the condensing heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Jankura, B. J. [McDermott Technology Inc., Alliance, OH (United States); Kudlac, G. A. [McDermott Technology Inc., Alliance, OH (United States); Bailey, R. T. [McDermott Technology Inc., Alliance, OH (United States)

    1998-06-01

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

  4. Studies on high-performance ceramic heat exchanger for ultra high temperature. 2nd Report. Heat transfer of finned tube bundle immersed in fluidized bed; Chokoon`yo koseino ceramic netsu kokanki ni kansuru kenkyu. 2. Ryudo sonai no rin kangun no netsudentatsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Himeji, Y; Kumada, M [Gifu University, Gifu (Japan). Faculty of Engineering

    1998-03-25

    Studies were carried out to develop a high-performance ceramic heat exchanger for ultra high temperatures using a fluidized bed. In the former study, Heat transfer coefficient had been improved by applying fluidized bed to the heat exchanger for high temperature with smooth ceramic tubes. In this study, finned ceramic tubes were applied instead of smooth tubes for more improvement of heat transfer and experiments were performed on condition that the maximum bed temperature was 1100degC. Fluidization remained stable and the bed temperature uniform in the bed similarly as the case of smooth tube. A heat transfer coefficient of finned tube was evaluated and it was improved about 3 times as large as that of smooth tube. The performance of the heat exchanger was also evaluated using temperature efficiency and exergy efficiency. 4 refs., 11 figs., 1 tab.

  5. Shivering and rewarming after cardiac surgery: comparison of ventilator circuits with humidifier and heated wires to heat and moisture exchangers.

    Science.gov (United States)

    McEvoy, M T; Carey, T J

    1995-07-01

    Detrimental physiologic effects of shivering in the cardiac surgery patient have been well documented. Rewarming techniques have been compared, with noted differences in the incidence of shivering. Ventilator circuits have not been examined independently from other rewarming variables. To compare heated wire humidification circuits with heat and moisture exchanger circuits on the incidence of shivering and speed and pattern of rewarming in mechanically ventilated patients. A prospective, descriptive, correlational study was done on 140 adult cardiac surgery patients in a university teaching medical center. All subjects underwent cardiac surgical procedures with hypothermic cardiopulmonary bypass. Subjects were randomized to humidified, heated wire circuits (n = 70) or heat and moisture exchanger circuits (n = 70). Heated water blankets were used on all patients. Mean intensive care unit admission temperature was 35.28 degrees C. No statistical differences were found in preoperative, demographic, or operative course data between treatment and control groups. Shivering was more common in the heat and moisture exchanger group than in the heated wire group. In our analysis, the only variable associated with shivering was the type of ventilator circuit. Patients using heated wire systems rewarmed more rapidly and had significantly higher temperatures than did patients using heat and moisture exchangers. These data suggest that use of heated wire humidified ventilator circuits with heated water blankets in adult cardiac surgery patients significantly reduces the incidence of shivering and results in a more rapid return to normothermia.

  6. Feedwater heater performance evaluation using the heat exchanger workstation

    International Nuclear Information System (INIS)

    Ranganathan, K.M.; Singh, G.P.; Tsou, J.L.

    1995-01-01

    A Heat Exchanger Workstation (HEW) has been developed to monitor the condition of heat exchanging equipment power plants. HEW enables engineers to analyze thermal performance and failure events for power plant feedwater heaters. The software provides tools for heat balance calculation and performance analysis. It also contains an expert system that enables performance enhancement. The Operation and Maintenance (O ampersand M) reference module on CD-ROM for HEW will be available by the end of 1995. Future developments of HEW would result in Condenser Expert System (CONES) and Balance of Plant Expert System (BOPES). HEW consists of five tightly integrated applications: A Database system for heat exchanger data storage, a Diagrammer system for creating plant heat exchanger schematics and data display, a Performance Analyst system for analyzing and predicting heat exchanger performance, a Performance Advisor expert system for expertise on improving heat exchanger performance and a Water Calculator system for computing properties of steam and water. In this paper an analysis of a feedwater heater which has been off-line is used to demonstrate how HEW can analyze the performance of the feedwater heater train and provide an economic justification for either replacing or repairing the feedwater heater

  7. Application of transient analysis methodology to heat exchanger performance monitoring

    International Nuclear Information System (INIS)

    Rampall, I.; Soler, A.I.; Singh, K.P.; Scott, B.H.

    1994-01-01

    A transient testing technique is developed to evaluate the thermal performance of industrial scale heat exchangers. A Galerkin-based numerical method with a choice of spectral basis elements to account for spatial temperature variations in heat exchangers is developed to solve the transient heat exchanger model equations. Testing a heat exchanger in the transient state may be the only viable alternative where conventional steady state testing procedures are impossible or infeasible. For example, this methodology is particularly suited to the determination of fouling levels in component cooling water system heat exchangers in nuclear power plants. The heat load on these so-called component coolers under steady state conditions is too small to permit meaningful testing. An adequate heat load develops immediately after a reactor shutdown when the exchanger inlet temperatures are highly time-dependent. The application of the analysis methodology is illustrated herein with reference to an in-situ transient testing carried out at a nuclear power plant. The method, however, is applicable to any transient testing application

  8. Thermal-hydraulic performance of the finned surface of a compact heat exchanger

    International Nuclear Information System (INIS)

    Errasti Cabrera, Michel

    2015-01-01

    In this work the thermal-hydraulic behavior of the finned surface of a compact heat exchanger is obtained in tube-fin configuration corrugated (wavy). Through numerical simulation are determined average values ​​of intensification of heat transfer and pressure loss in the inter-channel finned. The objective is to characterize the surface to use as a reference, to make comparisons with other heat exchange surfaces enhanced using traditional techniques combined with more current, such as vortex generators. The study is conducted in laminar flow, with Reynolds numbers below 1000. In the working model compact exchanger tubes and corrugated fins (wavy) heat is described, and the results of the coefficient of overall heat transfer and the pressure drop are explained from the local characteristics of the velocity field and temperature inside the heat exchanger. (Full text)

  9. Power and Thermal Technologies for Air and Space-Scientific Research Program. Delivery Order 0017: Study of Microchip Power Module Materials Using Mini-Channel Heat Exchanger

    Science.gov (United States)

    2009-12-01

    at the mid-point of the channels. In fabricating the heat exchanger, a method of attaching the inlet and exit flow tubes (stainless- steel 625 ) to...and the inlet/exit tubing. The mixing chambers ( Inconel 600) were machined as two pieces which were later welded together to make one chamber. The

  10. Experimental and numerical contribution to heat transfer enhancement in compact plate heat exchangers - 15563

    International Nuclear Information System (INIS)

    Vitillo, F.; Cachon, L.; Millan, P.

    2015-01-01

    In the framework of the CEA program to develop an industrial prototype of sodium-cooled fast reactor named (ASTRID), the present work aims at proposing an innovative compact heat exchanger technology, to provide solid technological basis for the utilization of a Brayton power conversion system. This allows avoiding the energetic sodium-water interaction that could potentially occur if a traditional Rankine cycle was used. The design of the gas-side (which determines the heat transfer resistance of the heat exchanger) of the sodium-gas heat exchanger has been the object of the present work. Compact technologies are necessary for the present application because of the low heat transfer capacity of the gas foreseen, i.e. nitrogen. The basic idea of this work is to design a channel were the fluid flow is as much as 3-dimensional as possible. In particular the proposed channel can be thought as the result of the superposition of 2 single PCHE wavy channels in phase opposition. The innovative channel geometry has to be studied numerically and experimentally to demonstrate its industrial interest and the final compact gain. To numerically provide a physically-consistent model, a new non-linear eddy viscosity named Anisotropic Shear Stress Transport (ASST) model has been developed and implemented into the available solver ANSYS FLUENT. It has been demonstrated that the ASST model can provide a valuable alternative to more complex models. Given the innovation of the proposed geometry, no test case has been found in the literature to be fully applicable to the present study. So, 3 experimental facilities have been used to acquire an extensive aerodynamic database. The Laser Doppler Velocimetry (LDV), Particle Image Velocimetry (PIV) and VHEGAS facilities have been built to investigate the innovative channel flow and heat transfer characteristics. The ASST model, used with a SGDH turbulent heat flux model, has been validate against the acquired thermal-hydraulic database

  11. Thermodynamic optimization of ground heat exchangers with single U-tube by entropy generation minimization method

    International Nuclear Information System (INIS)

    Li Min; Lai, Alvin C.K.

    2013-01-01

    Highlights: ► A second-law-based analysis is performed for single U-tube ground heat exchangers. ► Two expressions for the optimal length and flow velocity are developed for GHEs. ► Empirical velocities of GHEs are large compared to thermodynamic optimum values. - Abstract: This paper investigates thermodynamic performance of borehole ground heat exchangers with a single U-tube by the entropy generation minimization method which requires information of heat transfer and fluid mechanics, in addition to thermodynamics analysis. This study first derives an expression for dimensionless entropy generation number, a function that consists of five dimensionless variables, including Reynolds number, dimensionless borehole length, scale factor of pressures, and two duty parameters of ground heat exchangers. The derivation combines a heat transfer model and a hydraulics model for borehole ground heat exchangers with the first law and the second law of thermodynamics. Next, the entropy generation number is minimized to produce two analytical expressions for the optimal length and the optimal flow velocity of ground heat exchangers. Then, this paper discusses and analyzes implications and applications of these optimization formulas with two case studies. An important finding from the case studies is that widely used empirical velocities of circulating fluid are too large to operate ground-coupled heat pump systems in a thermodynamic optimization way. This paper demonstrates that thermodynamic optimal parameters of ground heat exchangers can probably be determined by using the entropy generation minimization method.

  12. On-line fouling monitor for heat exchangers

    International Nuclear Information System (INIS)

    Tsou, J.L.

    1995-01-01

    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

  13. Thermo-hydraulic design of earth-air heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Paepe, M. de [Ghent University (Belgium). Department of Flow, Heat and Combustion Mechanics; Janssens, A. [Ghent University (Belgium). Department of Architecture and Urbanism

    2003-05-01

    Earth-air heat exchangers, also called ground tube heat exchangers, are an interesting technique to reduce energy consumption in a building. They can cool or heat the ventilation air, using cold or heat accumulated in the soil. Several papers have been published in which a design method is described. Most of them are based on a discretisation of the one-dimensional heat transfer problem in the tube. Three-dimensional complex models, solving conduction and moisture transport in the soil are also found. These methods are of high complexity and often not ready for use by designers. In this paper, a one-dimensional analytical method is used to analyse the influence of the design parameters of the heat exchanger on the thermo-hydraulic performance. A relation is derived for the specific pressure drop, linking thermal effectiveness with pressure drop of the air inside the tube. The relation is used to formulate a design method which can be used to determine the characteristic dimensions of the earth-air heat exchanger in such a way that optimal thermal effectiveness is reached with acceptable pressure loss. The choice of the characteristic dimensions, becomes thus independent of the soil and climatological conditions. This allows designers to choose the earth-air heat exchanger configuration with the best performance. (author)

  14. Thermo-hydraulic design of earth-air heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    De Paepe, M. [Department of Flow, Heat and Combustion Mechanics, Ghent University, Ghent (Belgium); Janssens, A. [Department of Architecture and Urbanism, Ghent University, Ghent (Belgium)

    2003-07-01

    Earth-air heat exchangers, also called ground tube heat exchangers, are an interesting technique to reduce energy consumption in a building. They can cool or heat the ventilation air, using cold or heat accumulated in the soil. Several papers have been published in which a design method is described. Most of them are based on a discretisation of the one-dimensional heat transfer problem in the tube. Three-dimensional complex models, solving conduction and moisture transport in the soil are also found. These methods are of high complexity and often not ready for use by designers. In this paper, a one-dimensional analytical method is used to analyse the influence of the design parameters of the heat exchanger on the thermo-hydraulic performance. A relation is derived for the specific pressure drop, linking thermal effectiveness with pressure drop of the air inside the tube. The relation is used to formulate a design method which can be used to determine the characteristic dimensions of the earth-air heat exchanger in such a way that optimal thermal effectiveness is reached with acceptable pressure loss. The choice of the characteristic dimensions, becomes thus independent of the soil and climatological conditions. This allows designers to choose the earth-air heat exchanger configuration with the best performance. (author)

  15. High Effectiveness Heat Exchanger for Cryogenic Refrigerators, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative high performance cryogenic heat exchanger manufactured of titanium by photo-etching and diffusion bonding. This is a parallel plate design...

  16. Safety technology for air-cooled heat exchangers

    International Nuclear Information System (INIS)

    Kawai, Masafumi; Miyamoto, Hitoshi

    2011-01-01

    The air-cooled heat exchanger is a device that enables a large amount of heat exchange (cooling) by utilizing the atmosphere as a stable and infinite heat sink. It is widely used in general industrial plants, and nowadays it is also utilized in nuclear facilities. This type of exchanger is advantageous in that it can be constructed in any location without having to be near the sea or rivers. It can be operated safely if a natural disaster, such as a tsunami or flood, occurs, thus contributing to the safety of the mother facility. IHI's air-cooled heat exchangers are designed to ensure safe operation and withstand a large earthquake or severe atmospheric conditions. This report describes the technologies used to establish these safety features and their performance. (author)

  17. Various methods to improve heat transfer in exchangers

    Directory of Open Access Journals (Sweden)

    Pavel Zitek

    2015-01-01

    Full Text Available The University of West Bohemia in Pilsen (Department of Power System Engineering is working on the selection of effective heat exchangers. Conventional shell and tube heat exchangers use simple segmental baffles. It can be replaced by helical baffles, which increase the heat transfer efficiency and reduce pressure losses. Their usage is demonstrated in the primary circuit of IV. generation MSR (Molten Salt Reactors. For high-temperature reactors we consider the use of compact desk heat exchangers, which are small, which allows the integral configuration of reactor. We design them from graphite composites, which allow up to 1000°C and are usable as exchangers: salt-salt or salt-acid (e.g. for the hydrogen production. In the paper there are shown thermo-physical properties of salts, material properties and principles of calculations.

  18. Structure design of primary heat-exchanger for the MHWRR

    International Nuclear Information System (INIS)

    Li Yanshui; Cao Zhibin

    1999-01-01

    Primary heat-exchanger is one of the key equipment in the Multi-application Heavy Water Research Reactor (MHWRR). Its structure design ought to meet as much possible as the demands for safety, feasibility and economy. To reduce the liquid resistance, the locating structure between inner tube and outer tube is distributed spirally. The edge of outer tube is processed in the shape of hexahedron and then splice-welded into honeycomb structure thereby the heat-exchanger has the smallest outer diameter compared with that with the same heat-exchanging area according to 'Normal Design', 'Anabasis Design' is applied to the design for parts with Safety Class I, to ensure safety of the heat-exchanger

  19. IAEA Technical Meeting on Innovative Heat Exchanger and Steam Generator Designs for Fast Reactors. Working Material

    International Nuclear Information System (INIS)

    2011-01-01

    The IAEA, within the framework of its Nuclear Energy Department’s Technical Working Group on Fast Reactors (TWG-FR), assists Member States activities in fast reactors technology development areas by providing an umbrella for information exchange [topical Technical Meetings (TMs), Workshops and large Conferences] and collaborative R&D [Coordinated Research Projects (CRPs)]. The Technical meeting on “Innovative Heat Exchanger and Steam Generator Designs for Fast Reactors” was held from 21 – 22 December 2011 in Vienna, addressing Member States’ expressed needs of information exchange in the field of advanced fast reactor design features, with particular attention to innovative heat exchangers and steam generators. The Objective of the TM is to provide a global forum for in-depth information exchange and discussion on the most advanced concepts of heat exchangers and steam generators for fast reactors. More specifically, the objectives are: · Review of the status of advanced fast reactor development activities with special emphasis on design and performance of heat exchangers and steam generators; · Discuss requirements for innovative heat exchangers and steam generators; · Present results of studies and conceptual designs for innovative heat exchangers and steam generators; · Provide recommendations for international collaboration under the IAEA aegis. The meeting agenda of the meeting is in Annex I

  20. Eddy current inspection on heat exchanger tubes - problems and limitations

    International Nuclear Information System (INIS)

    Ilham Mukriz; Zainal Abidin Mohamed; Hairul Hasmoni Khairul Anuar; Mohd Salleh; Mahmood Dollah

    2005-01-01

    This paper focus on problems associated to eddy current inspection of heat exchanger tubes. A brief review on heat exchanger design and operation is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The limitation of the eddy current probe and equipment pertinent to the inspection are identified and areas of improvement are discussed. (Author)

  1. Shell-and-tube heat exchanger selection aid

    International Nuclear Information System (INIS)

    Lupton, L.R.; Basso, R.A.J.

    1989-11-01

    A prototype has been developed to investigate the feasibility of using expert systems to aid junior process system designers with the selection of components for shell-and-tube heat exchangers. The selection criteria for heat exchanger design were based on process, environmental and administrative constraints. The system was developed using EXSYS and consists of approximately 140 rules. This paper describes the development process and the lessons learned

  2. Ringshaped grid for supporting of pipes of a heat exchanger

    International Nuclear Information System (INIS)

    1976-01-01

    This heat exchanger furnishes a ring-shaped grid in which pipes can be ordered in a circular formation, as opposed to the conventional triangular ordering. In this structure the pipes are arranged in concentric circles. This means that each new row of pipes has an equal number of more pipes than the row directly inside, meaning that all the pipes in each row are equidistant from the center and form an equal surface for better heat exchange

  3. Numerical Simulation and Analysis on Liquid Nitrogen Spray Heat Exchanger

    OpenAIRE

    Wenjing Ding; Weiwei Shan; Zijuan; Wang; Chao He

    2017-01-01

    Liquid spray heat exchanger is the critical equipment of temperature regulating system by gaseous nitrogen which realizes the environment temperature in the range of -180 ℃~+180 ℃. Liquid nitrogen is atomized into smaller liquid drops through liquid nitrogen sprayer and then contacts with gaseous nitrogen to be cooled. By adjusting the pressure of liquid nitrogen and gaseous nitrogen, the flowrate of liquid nitrogen is changed to realize the required outlet temperature of heat exchanger. The ...

  4. Thermal performance modeling of cross-flow heat exchangers

    CERN Document Server

    Cabezas-Gómez, Luben; Saíz-Jabardo, José Maria

    2014-01-01

    This monograph introduces a numerical computational methodology for thermal performance modeling of cross-flow heat exchangers, with applications in chemical, refrigeration and automobile industries. This methodology allows obtaining effectiveness-number of transfer units (e-NTU) data and has been used for simulating several standard and complex flow arrangements configurations of cross-flow heat exchangers. Simulated results have been validated through comparisons with results from available exact and approximate analytical solutions. Very accurate results have been obtained over wide ranges

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

    NARCIS (Netherlands)

    de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries

    2014-01-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic

  6. Simulation and Optimization of the Heat Exchanger for Automotive Exhaust-Based Thermoelectric Generators

    Science.gov (United States)

    Su, C. Q.; Huang, C.; Deng, Y. D.; Wang, Y. P.; Chu, P. Q.; Zheng, S. J.

    2016-03-01

    In order to enhance the exhaust waste heat recovery efficiency of the automotive exhaust-based thermoelectric generator (TEG) system, a three-segment heat exchanger with folded-shaped internal structure for the TEG system is investigated in this study. As the major effect factors of the performance for the TEG system, surface temperature, and thermal uniformity of the heat exchanger are analyzed in this research, pressure drop along the heat exchanger is also considered. Based on computational fluid dynamics simulations and temperature distribution, the pressure drop along the heat exchanger is obtained. By considering variable length and thickness of folded plates in each segment of the heat exchanger, response surface methodology and optimization by a multi-objective genetic algorithm is applied for surface temperature, thermal uniformity, and pressure drop for the folded-shaped heat exchanger. An optimum design based on the optimization is proposed to improve the overall performance of the TEG system. The performance of the optimized heat exchanger in different engine conditions is discussed.

  7. Membrane heat exchanger in HVAC energy recovery systems, systems energy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nasif, M. [School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); Opus International Consultants (New Zealand); AL-Waked, R. [Mechanical Engineering Department, Prince Mohammad Bin Fahd University (PMU), P.O. Box 1614, AlKhobar 31952 (Saudi Arabia); Morrison, G. [School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); Behnia, M. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

    2010-10-15

    The thermal performance of an enthalpy/membrane heat exchanger is experimentally investigated. The heat exchanger utilizes a 60gsm Kraft paper as the heat and moisture transfer surface for HVAC energy recovery. The heat exchanger sensible, latent and total effectiveness have been determined through temperature and moisture content measurements. The annual energy consumption of an air conditioner coupled with an enthalpy/membrane heat exchanger is also studied and compared with a conventional air conditioning cycle using in-house modified HPRate software. The heat exchanger effectiveness are used as thermal performance indicators and incorporated in the modified software. Energy analysis showed that an air conditioning system coupled with a membrane heat exchanger consumes less energy than a conventional air conditioning system in hot and humid climates where the latent load is high. It has been shown that in humid climate a saving of up to 8% in annual energy consumption can be achieved when membrane heat exchanger is used instead of a conventional HVAC system. (author)

  8. DOE/ANL/HTRI heat exchanger tube vibration data bank

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-01-01

    This addendum to the DOE/ANL/HTRI Heat Exchanger Tube Vibration Data Bank includes 16 new case histories of field experiences. The cases include several exchangers that did not experience vibration problems and several for which acoustic vibration was reported.

  9. CTOD-based acceptance criteria for heat exchanger head staybolts

    International Nuclear Information System (INIS)

    Lam, P.S.; Sindelar, R.L.; Barnes, D.M.; Awadalla, N.G.

    1992-01-01

    The primary coolant piping system of the Savannah River Site (SRS) reactors contains twelve heat exchangers to remove the waste heat from the nuclear materials production. A large break at the inlet or outlet heads of the heat exchangers would occur if the restraint members of the heads become inactive. The heat exchanger head is attached to the tubesheet by 84 staybolts. The structural integrity of the heads is demonstrated by showing the redundant capacity of the staybolts to restrain the head at design conditions and under seismic loadings. The beat exchanger head is analyzed with a three- dimensional finite element model. The restraint provided by the staybolts is evaluated for several postulated cases of inactive or missing staybolts, that is, bolts that have a flaw exceeding the ultrasonic testing (UT) threshold depth of 25% of the bolt diameter. A limit of 6 inactive staybolts is reached with a fracture criterion based on the maximum allowable local displacement at the active staybolts which corresponds to the crack tip opening displacement (CTOD) of 0.032 inches. An acceptance criteria methodology has been developed to disposition flaws reported in the staybolt inspections while ensuring adequate restraint capacity of the staybolts to maintain integrity of the heat exchanger heads against collapse. The methodology includes an approach for the baseline and periodic inspections of the staybolts. A total of up to 6 staybolts, reported as containing flaws with depths at or exceeding 25% would be acceptable in the heat exchanger

  10. Optimization of liquid LBE-helium heat exchanger in ADS

    International Nuclear Information System (INIS)

    Meng Ruixue; Cai Jun; Huai Xiulan; Chen Fei

    2015-01-01

    The multi-parameter optimization of the liquid LBE-helium heat exchanger in ADS was conducted by genetic algorithm with entransy dissipation number and total cost as objective functions. The results show that the effectiveness of heat exchanger increases by 10.5% and 3.8%, and the total cost-reduces by 5.9% and 27.0% respectively with two optimization methods. Nevertheless, the optimization processes trade off increasing heat transfer area and decreasing heat transfer effectiveness respectively against achieving optimization targets. By comprehensively considering heat exchanger performance and cost-benefit, the optimization method with entransy dissipation number as the objective function is found to be more advantageous. (authors)

  11. Analysis of fluid flow and heat transfer in a double pipe heat exchanger with porous structures

    International Nuclear Information System (INIS)

    Targui, N.; Kahalerras, H.

    2008-01-01

    A numerical study of flow and heat transfer characteristics is made in a double pipe heat exchanger with porous structures inserted in the annular gap in two configurations: on the inner cylinder (A) and on both the cylinders in a staggered fashion (B). The flow field in the porous regions is modelled by the Darcy-Brinkman-Forchheimer model and the finite volume method is used to solve the governing equations. The effects of several parameters such as Darcy number, porous structures thickness and spacing and thermal conductivity ratio are considered in order to look for the most appropriate properties of the porous structures that allow optimal heat transfer enhancement. It is found that the highest heat transfer rates are obtained when the porous structures are attached in configuration B especially at small spacing and high thicknesses

  12. Heat transfer in a counterflow heat exchanger at low flow rates

    International Nuclear Information System (INIS)

    Hashimoto, A.; Hattori, N.; Naruke, K.

    1995-01-01

    A study was made of heat transfer in a double-tube heat exchanger at low flow rates of water. The temperatures of fluid and tube walls in the axial direction of tube were measured precisely at flow rate ratios of annulus to inner tube (or flow rate ratios of inner tube to annulus W i /W a , Re i approx. = 80 - 4000), W a /W i =0.1 - 1.1. In parallel with experiment, numerical calculation for forced-convection heat transfer was also carried out for laminar flows in the same tube configuration as experiment. Average over-all coefficients of heat transfer, obtained by experiments, indicate the same characteristics as numerical calculation in the examined range of flow rate ratio. Their experimental values, however, are somewhat larger than those of calculation at small values of flow rate ratio. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Yohanis, Y.G. [Thermal Systems Engineering Group, Faculty of Engineering, University of Ulster, Newtownabbey, Co Antrim, BT37 0QB Northern Ireland (United Kingdom)]. E-mail: yg.yohanis@ulster.ac.uk; Popel, O.S. [Non-traditional Renewable Energy Sources, Institute for High Temperatures, Russian Academy of Sciences, 13/19 Izhorskaya str., IVTAN, Moscow 125412 (Russian Federation); Frid, S.E. [Non-traditional Renewable Energy Sources, Institute for High Temperatures, Russian Academy of Sciences, 13/19 Izhorskaya str., IVTAN, Moscow 125412 (Russian Federation)

    2005-10-01

    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.

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

    International Nuclear Information System (INIS)

    Yohanis, Y.G.; Popel, O.S.; Frid, S.E.

    2005-01-01

    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

  15. The influence of a vertical ground heat exchanger length on the electricity consumption of the heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Michopoulos, A.; Kyriakis, N. [Process Equipment Design Laboratory, Mechanical Engineer Department, Aristotle University of Thessaloniki (AUTh), P.O. Box 487, 541 24 Thessaloniki (Greece)

    2010-07-15

    The use of heat pumps combined with vertical ground heat exchangers for heating and cooling of buildings, has significantly gained popularity in recent years. The design method for these systems, as it is proposed by ASHRAE, is taking into account the maximum thermal and cooling loads of the building, the thermophysical properties of the soil at the area of installation and a minimum Coefficient of Performance (COP) of the heat pumps. This approach usually results in larger than needed length of the ground heat exchanger, thus increasing the installation cost. A new analytical simulation tool, capable to determine the required ground heat exchanger length has been developed at the Process Equipment Design Laboratory (PEDL) of the AUTh. It models the function of the system as a whole over long time periods, e.g. 20 years, using as input parameters the thermal and cooling loads of the building, the thermophysical properties of the borehole and the characteristic curves of the heat pumps. The results include the electricity consumption of the heat pumps and the heat absorbed from or rejected to the ground. The aim of this paper is to describe the developed simulation algorithm and present the results of such a simulation in a case study. It is proved that the total required length of the ground heat exchanger is less than that calculated using the common numerical method. (author)

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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