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Sample records for ground heat exchanger

  1. Heat transfer characteristics of various kinds of ground heat exchangers for ground source heat pump system

    Science.gov (United States)

    Miyara, A.; Kariya, K.; Ali, Md. H.; Selamat, S. B.; Jalaluddin

    2017-01-01

    Three kinds of vertical-type ground heat exchangers, U-tube; double-tube; multi-tube, and two kinds of horizontal-type ground heat exchangers, standing Slinky; reclined Slinky, were experimentally and numerically investigated in order to clarify their heat transfer characteristics. Experiments and simulations were carried out under two operation conditions which are continuous operation mode and discontinuous operation mode and effects of temperature recovery and thermal storage on the heat transfer rate were shown. Differences of the heat transfer rate between standing Slinky and reclined Slinky were also indicated.

  2. 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.

  3. Performance Analysis of Slinky Horizontal Ground Heat Exchangers for a Ground Source Heat Pump System

    Directory of Open Access Journals (Sweden)

    Md. Hasan Ali

    2017-10-01

    Full Text Available This paper highlights the thermal performance of reclined (parallel to ground surface and standing (perpendicular to ground surface slinky horizontal ground heat exchangers (HGHEs with different water mass flow rates in the heating mode of continuous and intermittent operations. A copper tube with an outer surface protected with low-density polyethylene was selected as the tube material of the ground heat exchanger. Effects on ground temperature around the reclined slinky HGHE due to heat extraction and the effect of variation of ground temperatures on reclined HGHE performance are discussed. A higher heat exchange rate was experienced in standing HGHE than in reclined HGHE. The standing HGHE was affected by deeper ground temperature and also a greater amount of backfilled sand in standing HGHE (4.20 m3 than reclined HGHE (1.58 m3, which has higher thermal conductivity than site soil. For mass flow rate of 1 L/min with inlet water temperature 7 °C, the 4-day average heat extraction rates increased 45.3% and 127.3%, respectively, when the initial average ground temperatures at 1.5 m depth around reclined HGHE increased from 10.4 °C to 11.7 °C and 10.4 °C to 13.7 °C. In the case of intermittent operation, which boosted the thermal performance, a short time interval of intermittent operation is better than a long time interval of intermittent operation. Furthermore, from the viewpoint of power consumption by the circulating pump, the intermittent operation is more efficient than continuous operation.

  4. 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.

  5. Study of Ground Heat Exchangers in the Form of Parallel Horizontal Pipes Embedded in the Ground

    Directory of Open Access Journals (Sweden)

    Krzysztof Neupauer

    2018-02-01

    Full Text Available In order to predict long-term changes in the temperature of the ground in which a horizontal ground heat exchanger has been installed, it is beneficial to implement simplified mathematical models of heat transfer. The possibility of using a one-dimensional equation of heat conduction while modelling heat transfer in a ground heat exchanger with horizontal pipes has been demonstrated in the work. A theoretical analysis based on the linear heat source model as well as experimental research works have been carried out. It has been concluded that the temperature profiles of the ground in which parallel pipes of the heat exchanger are placed do not significantly differ from the profiles for the heat exchanger in the form of a plate; in particular, this refers to large distances from the level in which the pipes are positioned, small distances between pipes axes and the long duration of the process. Discrepancies between the calculated temperature increases for pipe and plate exchangers varied significantly in the individual time intervals, and were approx. 20–30%. The conducted experiments have demonstrated that the temperature field around parallel pipes of the heat exchanger may be described by the linear heat source model. The compatibility of temperature maps that were determined theoretically and experimentally was satisfactory with a good degree of accuracy.

  6. PERFORMANCE INVESTIGATION OF SLINKY HEAT EXCHANGER FOR SOLAR ASSISTED GROUND SOURCE HEAT PUMP

    OpenAIRE

    ÖZSOLAK, Onur; ESEN, Mehmet

    2014-01-01

    In the following study, 12 m2 test chamber was heated by solar and ground source heat pump under the physical conditions of Elazığ. In order to place slinky heat exchanger pipes, a hole was dug with 1 meter width, 2 meters depth and 15 meters length. Slinky pipes were put horizontally in the hole and water-antifreeze mixture was circulated with the circulating pump in the slinky heat exchanger. The heat taken from the ground was transferred into the environment to be heated through the heat p...

  7. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    Energy Technology Data Exchange (ETDEWEB)

    Mittereder, Nick [IBACOS, Inc., Pittsburgh, PA (United States); Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States)

    2013-11-01

    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. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season.

  8. Factors Influencing the Thermal Efficiency of Horizontal Ground Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Eloisa Di Sipio

    2017-11-01

    Full Text Available The performance of very shallow geothermal systems (VSGs, interesting the first 2 m of depth from ground level, is strongly correlated to the kind of sediment locally available. These systems are attractive due to their low installation costs, less legal constraints, easy maintenance and possibility for technical improvements. The Improving Thermal Efficiency of horizontal ground heat exchangers Project (ITER aims to understand how to enhance the heat transfer of the sediments surrounding the pipes and to depict the VSGs behavior in extreme thermal situations. In this regard, five helices were installed horizontally surrounded by five different backfilling materials under the same climatic conditions and tested under different operation modes. The field test monitoring concerned: (a monthly measurement of thermal conductivity and moisture content on surface; (b continuous recording of air and ground temperature (inside and outside each helix; (c continuous climatological and ground volumetric water content (VWC data acquisition. The interactions between soils, VSGs, environment and climate are presented here, focusing on the differences and similarities between the behavior of the helix and surrounding material, especially when the heat pump is running in heating mode for a very long time, forcing the ground temperature to drop below 0 °C.

  9. 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).

  10. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    Energy Technology Data Exchange (ETDEWEB)

    Mittereder, N.; Poerschke, A.

    2013-11-01

    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. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season. Upon completion of the monitoring phase, measurements revealed that the initial TRNSYS simulated horizontal sub-slab ground loop heat exchanger fluid temperatures and heat transfer rates differed from the measured values. To determine the cause of this discrepancy, an updated model was developed utilizing a new TRNSYS subroutine for simulating sub-slab heat exchangers. Measurements of fluid temperature, soil temperature, and heat transfer were used to validate the updated model.

  11. A new modelling approach for piled and other ground heat exchanger applications

    OpenAIRE

    Cecinato, F; Loveridge, F; Gajo, A; Powrie, W

    2015-01-01

    Pile heat exchangers have an increasing role to play in the delivery of renewable heating and cooling energy. Traditionally the thermal design of ground heat exchangers has relied upon analytical approaches which take a relatively simple approach to the inside of the heat exchanger. This approach is justified while the heat exchanger diameter remains small. However, as larger diameter piled founda-tions are used as heat exchangers, the transient heat transfer processes operating within the pi...

  12. 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

  13. The ground surface energy balance in modelling horizontal ground heat exchangers

    Science.gov (United States)

    Bortoloni, M.; Bottarelli, M.; Su, Y.

    2017-01-01

    The performance of horizontal ground heat exchangers (HGHEs) is strongly dependent on climatic conditions, due to the low installation depth. In numerical modelling of HGHEs, the estimation of shallow soil temperature distribution is a key issue, therefore the boundary condition (BC) at the ground surface should be assigned carefully. With this in mind, a model of the energy balance at the ground surface (GSEB), based on weather variables, was developed. The model was tested as the 3rd kind BC at ground surface in modelling HGHEs by means of the FEM code Comsol Multiphysics, solving the unsteady heat transfer problem in a 2D domain. The GSEB model was calibrated and validated with the observed soil temperature at different depths. In addition, the effect on numerical solutions of different BCs, when assigned at the ground surface, was analysed. Three different simulations were carried out applying the GSEB model, the equivalent surface heat flux and temperature as boundary conditions of the 1st, 2nd and 3rd kind, respectively. The results of this study indicate that the use of the GSEB model is a preferable approach to the problem and that the use of the equivalent surface temperature can be considered as a reasonable simplification.

  14. Seasonal performance for Heat pump with vertical ground heat exchanger in Riga

    Science.gov (United States)

    Jaundālders, S.; Stanka, P.; Rusovs, D.

    2017-10-01

    Experimental measurements of Seasonal Coefficient of Performance (SCOP) for heating of 160 m2 household in Riga were conducted for operation of brine-water heat pump with vertical ground heat exchangers (GHE). Data regarding heat and electrical power consumption were recorded during three-year period from 2013 to 2016. Vapor compression heat pump has heat energy output of 8 kW. GHE consists of three boreholes. Each borehole is 60 m deep. Data regarding brine temperature for borehole input and output were presented and discussed. As far as house had floor heating, there were presented data about COP for B0/W35 and its dependence from room and outdoor temperature during heating season. Empirical equation was created. Average heat energy consumption during one year for heating was 72 kWh/m2 measured by heat meter. Detected primary energy consumption (electrical energy from grid) was 21 kWh/m2 which resulted in SCOP=3.8. These data were compared with SCOP for air-to-water heat pump in Latvia and available configuration software for heat pumps operation. Good agreement between calculated performance and reported experimental data were founded.

  15. Impact of Seasonal Heat Accumulation on Operation of Geothermal Heat Pump System with Vertical Ground Heat Exchanger

    Science.gov (United States)

    Timofeev, D. V.; Malyavina, E. G.

    2017-11-01

    The subject of the investigation was to find out the influence of heat pump operation in summer on its function in winter. For this purpose a mathematical model of a ground coupled heat pump system has been developed and programmed. The mathematical model of a system ground heat exchanger uses the finite difference method to describe the heat transfer in soil and the analytical method to specify the heat transfer in the U-tubes heat exchanger. The thermal diffusivity by the heat transfer in the soil changes during gradual freezing of the pore moisture and thus slows soil freezing. The mathematical model of a heat pump includes the description of a scroll compressor and the simplified descriptions of the evaporator and condenser. The analysis showed that heating during the cold season and cooling in the warm season affect the average heat transfer medium temperature in the soil loop in the winter season. It has been also showed that the degree of this effect depends on the clay content in the soil.

  16. Mathematical modelling of thermal and flow processes in vertical ground heat exchangers

    Directory of Open Access Journals (Sweden)

    Pater Sebastian

    2017-12-01

    Full Text Available The main task of mathematical modelling of thermal and flow processes in vertical ground heat exchanger (BHE-Borehole Heat Exchanger is to determine the unit of borehole depth heat flux obtainable or transferred during the operation of the installation. This assignment is indirectly associated with finding the circulating fluid temperature flowing out from the U-tube at a given inlet temperature of fluid in respect to other operational parameters of the installation.

  17. 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.

  18. Analysis of Short Time Period of Operation of Horizontal Ground Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Salsuwanda Selamat

    2015-07-01

    Full Text Available Ground source heat pump (GSHP systems have been proven to have higher efficiency compared to conventional air source heat pump systems for space heating and cooling applications. While vertical ground heat exchangers (GHE are favorable in GSHP installation, this type of configuration requires higher capital costs as opposed to horizontal configuration. Numerical simulation has been used to accurately predict the thermal performance of GHE. In this paper, numerical analysis of thermal performance for slinky horizontal GHE loops in different orientations and operation modes is discussed. It was found that the loop orientation is not so important due to the little effect it has on thermal performance. While the mean heat exchange rate of copper loop increases 48% compared to HDPE loop, the analysis supports the common claim that heat exchange rate is predominantly limited by the thermal conductivity of the ground. With the same amount of circulation work, the mean heat exchange rate increases by 83%–162% when operated in parallel loops operations. The performance in these operations can be further optimized to 10%–14% increase when spacing between adjacent loops was provided. The spacing helps to minimize interference of heat flow that would penalize the overall thermal performance.

  19. 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

  20. Application of ground-to-air heat exchanger for preheating of supply air

    Science.gov (United States)

    Sorokins, Juris; Borodinecs, Anatolijs; Zemitis, Jurgis

    2017-10-01

    This study focuses on assessing the contribution of the passive ground-coupled air heat exchanger system to decreasing the energy consumption of air conditioning and ventilation systems for office buildings in the Latvian climate conditions. The theoretical part of the thesis deals with methods of office building ventilation, supply air preheating and heat recovery as well as particularities of using ground-coupled air heat exchangers, their design parameters and their joint impact on the thermal performance. The engineering project part includes a ventilation system for an office building with an integrated ground-coupled air heat exchanger. By simulating energy consumption of the ventilation system for a duration of one year, the thesis analyzes the contribution of the heat exchanger to the overall energy consumption, which totals 9.53 MWh and 4.02 MWh a year, according to the desired parameters of the indoor climate. The possible alternative heat recovery solutions are investigated to reach by European Regional Development Fund project Nr.1.1.1.1/16/A/048 “NEARLY ZERO ENERGY SOLUTIONS FOR UNCLASSIFIED BUILDINGS”.

  1. 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.)

  2. Heat exchanger

    International Nuclear Information System (INIS)

    Watabe, Ichiro.

    1996-01-01

    An inner cylinder is disposed coaxially in a vertical vessel, and a plurality of heat transfer pipes are wound spirally on the outer circumference of the inner cylinder. High temperature sodium descends on the outer side of the inner cylinder while exchanging heat with water in the heat transfer pipes and becomes low temperature sodium. The low temperature sodium turns at the lower portion of the vessel, rises in a sodium exit pipe inserted to the inner cylinder and is discharged from the top of the vessel to the outside of the vessel. A portion of a cover gas (an inert gas such as argon) filled to the upper portion of the vessel intrudes into the space between the outer circumference of the sodium exit pipe and the inner circumference of the inner cylinder to form a heat insulation layer of the inert gas. This prevents heat exchange between the high temperature sodium before heat exchange and low temperature sodium after heat exchange. The heat exchanger is used as a secondary heat exchanger for coolants (sodium) of an FBR type reactor. (I.N.)

  3. 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

  4. HEAT EXCHANGER

    Science.gov (United States)

    Fox, T.H. III; Richey, T. Jr.; Winders, G.R.

    1962-10-23

    A heat exchanger is designed for use in the transfer of heat between a radioactive fiuid and a non-radioactive fiuid. The exchanger employs a removable section containing the non-hazardous fluid extending into the section designed to contain the radioactive fluid. The removable section is provided with a construction to cancel out thermal stresses. The stationary section is pressurized to prevent leakage of the radioactive fiuid and to maintain a safe, desirable level for this fiuid. (AEC)

  5. Nature's Heat Exchangers.

    Science.gov (United States)

    Barnes, George

    1991-01-01

    Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)

  6. 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

  7. 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

  8. Effect of Borehole Material on Analytical Solutions of the Heat Transfer Model of Ground Heat Exchangers Considering Groundwater Flow

    Directory of Open Access Journals (Sweden)

    Sangwoo Park

    2016-04-01

    Full Text Available Groundwater flow is one of the most important factors for the design of a ground heat exchanger (GHEX since the thermal environment of the ground around the buried GHEX is significantly affected by heat convection due to the groundwater flow. Several preceding studies have been conducted to develop analytical solutions to the heat transfer model of GHEX with consideration of groundwater flow. One of these solutions is the combined heat transfer model of conduction and convection. However, the developed combined analytical models are inapplicable to all of the configurations of ordinary GHEXs because these solutions assume that the inner part of the borehole is thermally inert or consists of the same material as that of the surrounding ground. In this paper, the applicability of the combined solid cylindrical heat source model, which is the most suitable to energy piles until now, was evaluated by performing a series of numerical analyses. In the numerical analysis, the inner part of the borehole was modeled as two different materials (i.e., permeable ground formation and impermeable fill such as concrete to evaluate applicability of the analytical solution along with different diameter-length (D/L ratios of borehole. In a small value of the D/L ratio, the analytical solution to the combined heat transfer model is in good agreement with the result of numerical analysis. On the other hand, when increasing the D/L ratio, the analytical solution significantly overestimates the effect of groundwater flow on the heat transfer of GHEXs because the analytical solution disregards the existence of the impermeable region in the borehole. Consequently, such tendency is more critical in the GHEX with a large D/L ratio such as large-diameter energy piles.

  9. Horizontal Air-Ground Heat Exchanger Performance and Humidity Simulation by Computational Fluid Dynamic Analysis

    Directory of Open Access Journals (Sweden)

    Paolo Maria Congedo

    2016-11-01

    Full Text Available Improving energy efficiency in buildings and promoting renewables are key objectives of European energy policies. Several technological measures are being developed to enhance the energy performance of buildings. Among these, geothermal systems present a huge potential to reduce energy consumption for mechanical ventilation and cooling, but their behavior depending on varying parameters, boundary and climatic conditions is not fully established. In this paper a horizontal air-ground heat exchanger (HAGHE system is studied by the development of a computational fluid dynamics (CFD model. Summer and winter conditions representative of the Mediterranean climate are analyzed to evaluate operation and thermal performance differences. A particular focus is given to humidity variations as this parameter has a major impact on indoor air quality and comfort. Results show the benefits that HAGHE systems can provide in reducing energy consumption in all seasons, in summer when free-cooling can be implemented avoiding post air treatment using heat pumps.

  10. 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.)

  11. Computational Fluid Dynamic Modeling of Horizontal Air-Ground Heat Exchangers (HAGHE for HVAC Systems

    Directory of Open Access Journals (Sweden)

    Paolo Maria Congedo

    2014-12-01

    Full Text Available In order to satisfy the requirements of Directive 2010/31/EU for Zero Energy Buildings (ZEB, innovative solutions were investigated for building HVAC systems. Horizontal air-ground heat exchangers (HAGHE offer a significant contribution in reducing energy consumption for ventilation, using the thermal energy stored underground, in order to pre-heat or pre-cool the ventilation air, in winter and summer, respectively. This is particularly interesting in applications for industrial, commercial and education buildings where keeping the indoor air quality under control is extremely important. Experimental measurements show that, throughout the year, the outside air temperature fluctuations are mitigated at sufficient ground depth (about 3 m because of the high thermal inertia of the soil, the ground temperature is relatively constant and instead higher than that of the outside air in winter and lower in summer. The study aims to numerically investigate the behavior of HAGHE by varying the air flow rate and soil conductivity in unsteady conditions by using annual weather data of South-East Italy. The analysis shows that, in warm climates, the HAGHE brings a real advantage for only a few hours daily in winter, while it shows significant benefits in the summer for the cooling of ventilation air up to several temperature degrees, already by a short pipe.

  12. 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.

  13. 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.

  14. Verification of the Performance of a Vertical Ground Heat Exchanger Applied to a Test House in Melbourne, Australia

    Directory of Open Access Journals (Sweden)

    Koon Beng Ooi

    2017-10-01

    Full Text Available The ground heat exchanger is traditionally used as a heat source or sink for the heat pump that raises the temperature of water to about 50 °C to heat houses. However, in winter, the heating thermostat (temperature at which heating begins in the Australian Nationwide House Energy Rating Scheme (NatHERS is only 20 °C during daytime and 15 °C at night. In South-East Melbourne, the temperature at the bottom of a 50-meter-deep borehole has been recorded with an Emerson™ recorder at 17 °C. Melbourne has an annual average temperature of 15 °C, so the ground temperature increases by 2 °C per 50-m depth. A linear projection gives 23 °C at 200-m of depth, and as the average undisturbed temperature of the ground for a 400-m-deep vertical ground heat exchanger (VGHE. This study, by simulation and experimentation, aims to verify that the circulation of water in the VGHE’s U-tube to low-temperature radiators (LTRs could heat a house to thermal comfort. A literature review is included in the introduction. A simulation, using a model of a 60-m2 experimental house, shows that the daytime circulation of water in this VGHE/LTR-on-opposite-walls system during the 8-month cold half of the year, heats the indoors to NatHERS settings. Simulation for the cold half shows that this VGHE-LTR system could cool the indoors. Instead, a fan creating a cooling sensation of up to 4 °C is used so that the VGHE is available for the regeneration of heat extracted from the ground during the cold portion. Simulations for this hot portion show that a 3.4-m2 flat plate solar collector can collect more than twice the heat extracted from the ground in the cold portion. Thus, it can thus replenish the ground heat extracted for houses double the size of this 60-m2 experimental house. Therefore, ground heat is sustainable for family-size homes. Since no heat pump is used, the cost of VGHE-LTR systems could be comparable to systems using the ground source heat pump. Water

  15. Air/ground heat exchanger (GHE): Modelling, design, performance; Luft-/Erdwaermetauscher EWT: Modellierung, Auslegung und Betriebserfahrungen

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, A. [Fraunhofer-Inst. fuer Solare Energiesysteme, Freiburg (Germany); Pfafferott, J. [Energieversorgung Spree-Schwarze Elster AG (ESSAG), Cottbus (Germany); Dibowski, G. [Deutsches Zentrum fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Abt. Sonnenofen

    1998-02-01

    Air/Ground Heat Exchanger (GHE) utilize soil for seasonal heat storage and are used for air preheating or -cooling. Design and layout require suitable tools which adequately describe the complex heat temperature mechanisms in soils. Since heat densities in soil and heat exchange coefficients between air and GHE are both low, a detailed characterization of the soil and a precise modeling of the heat exchange processes within the GHE are needed. Tools for the design and yield prediction of GHE are presented by way of examples. Results are compared with measured data and both opportunities and limitations of GHEs are discussed using calculated and actual data. (orig.) [Deutsch] Luft-/Erdwaermetauscher EWT nutzen das Erdreich als saisonalen Energiespeicher, sie werden beispielsweise zur Zuluft-Vorerwaermung oder -kuehlung eingesetzt. Die Planung und Auslegung von Luft-/Erdwaermetauschern erfordert geeignete Hilfsmittel, um das komplizierte Temperaturfeld im Erdreich mit ausreichender Genauigkeit abbilden zu koennen. Da die Waermestromdichten im Erdreich und der Waermeuebergang zwischen der Luft im Luft-/Erdwaermetauscher und dem umgebenden Erdreich gering sind, ist sowohl eine detaillierte Abbildung des Erdreichs als auch die Modellierung des Waermeuebergangs im Luft-/Erdwaermetauscher erforderlich. Verfahren zur Auslegung und Ertragsvorhersage von Luft-/Erdwaermetauschern werden vorgestellt und deren Anwendung demonstriert. Die Ergebnisse werden mit Betriebserfahrungen von realisierten Luft-/Erdwrmetauschern verglichen. Moeglichkeiten und Grenzen von Luft-/Erdwaermetauschern werden anhand von Praxis und Simulationsrechnungen diskutiert. (orig.)

  16. Laser Processed Heat Exchangers

    Data.gov (United States)

    National Aeronautics and Space Administration — The considerable mass of Heat Exchangers (HXs) and coldplates on spacecraft as well as the problematic coatings of the Condensing Heat Exchanger (CHX) are among the...

  17. Direct fired heat exchanger

    Science.gov (United States)

    Reimann, Robert C.; Root, Richard A.

    1986-01-01

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

  18. Simulation and optimisation of a ground source heat pump with different ground heat exchanger configurations for a single-family residential house

    DEFF Research Database (Denmark)

    Pavlov, Georgi Krasimiroy; Olesen, Bjarne W.

    2012-01-01

    In the future there will be an increased demand for energy efficient cooling of residential buildings. Therefore it is essential to develop cooling concepts that are passive and/or using very little primary energy. A possible solution is a ground source heat pump combined with a low-temperature h...

  19. Contact Heat Exchanger

    Science.gov (United States)

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

    1985-01-01

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

  20. Simulation and optimisation of a ground source heat pump with different ground heat exchanger configurations for a single-family residential house

    DEFF Research Database (Denmark)

    Pavlov, Georgi Krasimiroy; Olesen, Bjarne W.

    2012-01-01

    In the future there will be an increased demand for energy efficient cooling of residential buildings. Therefore it is essential to develop cooling concepts that are passive and/or using very little primary energy. A possible solution is a ground source heat pump combined with a low-temperature h......In the future there will be an increased demand for energy efficient cooling of residential buildings. Therefore it is essential to develop cooling concepts that are passive and/or using very little primary energy. A possible solution is a ground source heat pump combined with a low......-temperature heating and high-temperature cooling system. The present work evaluates the performance in relation to thermal comfort and energy consumption of a GSHP with different GHE concepts. The different configurations are analyzed being part of the energy supply system of a low-energy residential house...

  1. Evaluation of the thermal efficiency and a cost analysis of different types of ground heat exchangers in energy piles

    International Nuclear Information System (INIS)

    Yoon, Seok; Lee, Seung-Rae; Xue, Jianfeng; Zosseder, Kai; Go, Gyu-Hyun; Park, Hyunku

    2015-01-01

    Highlights: • We performed field TPT with W and coil-type GHEs in energy piles. • We evaluated heat exchange rates from TPT results. • Field TPT results were compared with numerical analysis. • Cost analysis with GSHP design method was conducted for each type of GHEs in energy piles. - Abstract: This paper presents an experimental and numerical study of the results of a thermal performance test using precast high-strength concrete (PHC) energy piles with W and coil-type ground heat exchangers (GHEs). In-situ thermal performance tests (TPTs) were conducted for four days under an intermittent operation condition (8 h on; 16 h off) on W and coil-type PHC energy piles installed in a partially saturated weathered granite soil deposit. In addition, three-dimensional finite element analyses were conducted and the results were compared with the four-day experimental results. The heat exchange rates were also predicted for three months using the numerical analysis. The heat exchange rate of the coil-type GHE showed 10–15% higher efficiency compared to the W-type GHE in the energy pile. However, in considering the cost for the installation of the heat exchanger and cement grouting the additional cost of W-type GHE in energy pile was 200–250% cheaper than coil-type GHE under the condition providing equivalent thermal performance. Furthermore, the required lengths of the W, 3U and coil-type GHEs in the energy piles were calculated based on the design process of Kavanaugh and Rafferty. The additional cost for the W and 3U types of GHEs were also 200–250% lower than that of the coil-type GHE. However, the required number of piles was much less with the coil-type GHE as compared to the W and 3U types of GHEs. They are advantageous in terms of the construction period, and further, selecting the coil-type GHE could be a viable option when there is a limitation in the number of piles in consideration of the scale of the building.

  2. Wound tube heat exchanger

    Science.gov (United States)

    Ecker, Amir L.

    1983-01-01

    What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

  3. Laser Processed Heat Exchangers

    Science.gov (United States)

    Hansen, Scott

    2017-01-01

    The Laser Processed Heat Exchanger project will investigate the use of laser processed surfaces to reduce mass and volume in liquid/liquid heat exchangers as well as the replacement of the harmful and problematic coatings of the Condensing Heat Exchangers (CHX). For this project, two scale unit test articles will be designed, manufactured, and tested. These two units are a high efficiency liquid/liquid HX and a high reliability CHX.

  4. 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.

  5. Optimization of Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Ivan Catton

    2010-10-01

    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 disign.

  6. Active microchannel heat exchanger

    Science.gov (United States)

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

    2001-01-01

    The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction exhaust through the exhaust chamber and by conduction through a containment wall to the working fluid in the heat exchanger chamber thereby raising a temperature of the working fluid. The invention is particularly useful as a liquid fuel vaporizer and/or a steam generator for fuel cell power systems, and as a heat source for sustaining endothermic chemical reactions and initiating exothermic reactions.

  7. Heat and mass exchanger

    Science.gov (United States)

    Lowenstein, Andrew; Sibilia, Marc J.; Miller, Jeffrey A.; Tonon, Thomas

    2007-09-18

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

  8. A corrosive resistant heat exchanger

    Science.gov (United States)

    Richlen, S.L.

    1987-08-10

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

  9. 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)

  10. 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.

  11. Counterflow Regolith Heat Exchanger

    Science.gov (United States)

    Zubrin, Robert; Jonscher, Peter

    2013-01-01

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

  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 summarized

  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 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

  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 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

  16. Scraped surface heat exchangers.

    Science.gov (United States)

    Rao, Chetan S; Hartel, Richard W

    2006-01-01

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

  17. Microgravity condensing heat exchanger

    Science.gov (United States)

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

    2011-01-01

    A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

  18. Modular heat exchanger

    Science.gov (United States)

    Culver, Donald W.

    1978-01-01

    A heat exchanger for use in nuclear reactors includes a heat exchange tube bundle formed from similar modules each having a hexagonal shroud containing a large number of thermally conductive tubes which are connected with inlet and outlet headers at opposite ends of each module, the respective headers being adapted for interconnection with suitable inlet and outlet manifold means. In order to adapt the heat exchanger for operation in a high temperature and high pressure environment and to provide access to all tube ports at opposite ends of the tube bundle, a spherical tube sheet is arranged in sealed relation across the chamber with an elongated duct extending outwardly therefrom to provide manifold means for interconnection with the opposite end of the tube bundle.

  19. Paste heat exchange

    Energy Technology Data Exchange (ETDEWEB)

    1943-07-30

    The subject of coal paste heat exchangers is discussed in this letter report from Gelsenberg A.G. to I.G. Farbenindustrie A.G. Gelsenberg had given little consideration to the heating of coal paste by means of regeneration (heat exchange) because of the lack of experience in paste regeneration with bituminous coal, especially at 700 atmospheres. At the I.G. Farben plant at Poelitz, paste regeneration was carried out so that low concentration coal paste was heated in the regenerator together with the process gas, and the remaining coal was fed into the cold pass of the preheater in a thicker paste. Later tests proved this process viable. Gelsenberg heated normal coal paste and the gas in heat exchangers with the goal of relieving the preheater. Good results were achieved without change in design. The coal paste was heated with process gas in the regenerator at up to 315 degrees with constant pressure difference, so that after three months no decrease in K-values and no deposition or thickening was observed. Through the omission of paste gas, the pressure difference of the system became more constant and did not rise above the former level. The temperature also was more controllable, the chamber smoother running. Principal thermal data are given in a table. 1 table, 1 graph.

  20. Heat exchanger panel

    Science.gov (United States)

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

    2005-01-01

    The present invention relates to a heat exchanger panel which has broad utility in high temperature environments. The heat exchanger panel has a first panel, a second panel, and at least one fluid containment device positioned intermediate the first and second panels. At least one of the first panel and the second panel have at least one feature on an interior surface to accommodate the at least one fluid containment device. In a preferred embodiment, each of the first and second panels is formed from a high conductivity, high temperature composite material. Also, in a preferred embodiment, the first and second panels are joined together by one or more composite fasteners.

  1. Ground Source Heat Pump in Heating System with Electronics Monitoring

    Directory of Open Access Journals (Sweden)

    NEAMŢU Ovidiu

    2013-10-01

    Full Text Available The monitoring system is implemented for a ground coupled heat pump in heating/ system. The borehole heat exchangers – which are 150 m long - are filled with a mixture of water and ethilene glycol calledbrine. Metering and monitoring energy consumption is achieved for: heat pump, circulation pumps, additional electrical heating, hot air ventilation systems, control systems with sensors: analog and smart sensors. Instantaneous values are stored in a local computer.

  2. Heat exchanger-accumulator

    Science.gov (United States)

    Ecker, Amir L.

    1980-01-01

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

  3. Heat-Exchanger/Heat-Pipe Interface

    Science.gov (United States)

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

    1987-01-01

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

  4. Heat exchanger tube mounts

    Science.gov (United States)

    Wolowodiuk, W.; Anelli, J.; Dawson, B.E.

    1974-01-01

    A heat exchanger in which tubes are secured to a tube sheet by internal bore welding is described. The tubes may be moved into place in preparation for welding with comparatively little trouble. A number of segmented tube support plates are provided which allow a considerable portion of each of the tubes to be moved laterally after the end thereof has been positioned in preparation for internal bore welding to the tube sheet. (auth)

  5. 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

  6. Fault-Tolerant Heat Exchanger

    Science.gov (United States)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  7. Counterflow Regolith Heat Exchanger Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat...

  8. 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

  9. Cryogenic regenerative heat exchangers

    CERN Document Server

    Ackermann, Robert A

    1997-01-01

    An in-depth survey of regenerative heat exchangers, this book chronicles the development and recent commercialization of regenerative devices for cryogenic applications. Chapters cover historical background, concepts, practical applications, design data, and numerical solutions, providing the latest information for engineers to develop advanced cryogenic machines. The discussions include insights into the operation of a regenerator; descriptions of the cyclic and fluid temperature distributions in a regenerator; data for various matrix geometries and materials, including coarse and fine bronze, stainless steel-woven wire mesh screens, and lead spheres; and unique operating features of cryocoolers that produce deviations from ideal regenerator theory.

  10. Hybrid Heat Exchangers

    Science.gov (United States)

    Tu, Jianping Gene; Shih, Wei

    2010-01-01

    A hybrid light-weight heat exchanger concept has been developed that uses high-conductivity carbon-carbon (C-C) composites as the heat-transfer fins and uses conventional high-temperature metals, such as Inconel, nickel, and titanium as the parting sheets to meet leakage and structural requirements. In order to maximize thermal conductivity, the majority of carbon fiber is aligned in the fin direction resulting in 300 W/m.K or higher conductivity in the fin directions. As a result of this fiber orientation, the coefficient of thermal expansion (CTE) of the C-C composite in both non-fiber directions matches well with the CTE of various high-temperature metal alloys. This allows the joining of fins and parting sheets by using high-temperature braze alloys.

  11. 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...

  12. 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.

  13. 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.

  14. 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 ...

  15. 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

  16. Heat exchanger with ceramic elements

    Science.gov (United States)

    Corey, John A.

    1986-01-01

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

  17. 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.

  18. 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...

  19. 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)

  20. Heat exchanger and related methods

    Science.gov (United States)

    Turner, Terry D.; McKellar, Michael G.

    2015-12-22

    Heat exchangers include a housing having an inlet and an outlet and forming a portion of a transition chamber. A heating member may form another portion of the transition chamber. The heating member includes a first end having a first opening and a second end having a second opening larger than the first opening. Methods of conveying a fluid include supplying a first fluid into a transition chamber of a heat exchanger, supplying a second fluid into the transition chamber, and altering a state of a portion of the first fluid with the second fluid. Methods of sublimating solid particles include conveying a first fluid comprising a material in a solid state into a transition chamber, heating the material to a gaseous state by directing a second fluid through a heating member and mixing the first fluid and the second fluid.

  1. 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

  2. Heat exchanger with steam overheating

    International Nuclear Information System (INIS)

    Manek, O.; Motejl, V.; Quitta, R.; Schlinger, S.

    1975-01-01

    A heat exchanger incorporating steam superheating is proposed suitable for nuclear power plants having heat transfer surfaces housed in the pressure vessel. The heat exchanger is characterized by the fact that on the primary side the steam overheating surface is parallel to the afterheating and evaporating surfaces. The parallel heat transfer surfaces, afterheating and evaporating surfaces are connected to a common tube plate. The superheated steam outlet is formed by the central tube, the saturated steam by-pass channel is formed by a concentric tube. The steam superheating surface is formed by a cluster of U-tubes. Spatial U-tubes form the afterheating and the evaporating surfaces outside of the superheating surface. (Oy)

  3. Heat exchanger staybolt acceptance criteria

    International Nuclear Information System (INIS)

    Lam, P.S.; Sindelar, R.L.; Barnes, D.M.

    1992-02-01

    The structural integrity demonstration of the primary coolant piping system includes evaluating the structural capacity of each component against a large break or equivalent Double-Ended Guillotine Break. 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 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 Savannah River Site heat exchanger head is attached to the tubesheet by 84 staybolts. Access to the staybolts is limited due to a welded seal cap over the staybolts. An ultrasonic testing (UT) inspection technique to provide an in-situ examination of the staybolts has recently been developed at SRS. Examination of the staybolts will be performed to ensure their service condition and configuration is within acceptance limits. 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. The heat 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. Evaluation of specific, inactive staybolt configurations based on the UT results can be performed with the finite element model and fracture methodology in this report

  4. 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.

  5. SODIUM-WATER HEAT EXCHANGER

    Science.gov (United States)

    Simmons, W.R.; Koch, L.J.

    1962-04-17

    A heat exchanger comprising a tank for hot liquid and a plurality of concentric, double tubes for cool liquid extending vertically through the tank is described. These tubes are bonded throughout most of their length but have an unbonded portion at both ends. The inner tubes extend between headers located above and below the tanmk and the outer tubes are welded into tube sheets forming the top and bottom of the tank at locations in the unbonded portions of the tubes. (AEC)

  6. 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…

  7. 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.

  8. A Review of Industrial Heat Exchange Optimization

    Science.gov (United States)

    Yao, Junjie

    2018-01-01

    Heat exchanger is an energy exchange equipment, it transfers the heat from a working medium to another working medium, which has been wildly used in petrochemical industry, HVAC refrigeration, aerospace and so many other fields. The optimal design and efficient operation of the heat exchanger and heat transfer network are of great significance to the process industry to realize energy conservation, production cost reduction and energy consumption reduction. In this paper, the optimization of heat exchanger, optimal algorithm and heat exchanger optimization with different objective functions are discussed. Then, optimization of the heat exchanger and the heat exchanger network considering different conditions are compared and analysed. Finally, all the problems discussed are summarized and foresights are proposed.

  9. Temperatures and Heat Flows in a Soil Enclosing a Slinky Horizontal Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Pavel Neuberger

    2014-02-01

    Full Text Available Temperature changes and heat flows in soils that host “slinky”-type horizontal heat exchangers are complex, but need to be understood if robust quantification of the thermal energy available to a ground-source heat pump is to be achieved. Of particular interest is the capacity of the thermal energy content of the soil to regenerate when the heat exchangers are not operating. Analysis of specific heat flows and the specific thermal energy regime within the soil, including that captured by the heat-exchangers, has been characterised by meticulous measurements. These reveal that high concentrations of antifreeze mix in the heat-transfer fluid of the heat exchanger have an adverse impact on heat flows discharged into the soil.

  10. Assessment of impact of borehole heat exchanger design on heat extraction/rejection efficiency

    Directory of Open Access Journals (Sweden)

    Gornov V.F.

    2016-01-01

    Full Text Available The article considers the impact of design of borehole heat exchanger (BHE as one of the main elements of a geothermal heat pump system on its efficiency in the ground heat extraction/rejection. Four BHE modifications are considered: coaxial with metal and polyethylene outside tube as well as single and double U-shaped structures of polyethylene tubes. Numerical modeling resulted to data on the efficiency of these BHE modifications for rejection heat into ground (heat pump system in cooling mode, and ground heat extraction (heat pump system in heating mode. Numerical values were obtained and BHEs were ranked according to their efficiency in both operation modes. Besides, additional calculations were made for the most common modification - double U-shaped design - in the ground heat extraction mode for various tube sizes with various wall thicknesses.

  11. Comparing the thermal performance of horizontal slinky-loop and vertical slinky-loop heat exchangers

    OpenAIRE

    C.S.A. Chong; G. Gan; A. Verhoef; R.G. Garcia

    2014-01-01

    The heat pump market in the UK has grown rapidly over the last few years. Performance analyses of vertical ground-loop heat exchanger configurations have been widely carried out using both numerical modelling and experiments. However, research findings and design recommendations on horizontal slinky-loop and vertical slinky-loop heat exchangers are far fewer compared with those for vertical ground-loop heat exchanger configurations, especially where the long-term operation of the systems is c...

  12. Cooling device for a heat exchange fluid

    International Nuclear Information System (INIS)

    Farquhar, N.G.; Schwab, J.A.

    1976-01-01

    The invention refers to a system for cooling process or operation fluids, in which the local or general superheating of the coolant must be avoided. It particularly applies to the bleed fluid of a nuclear power station steam generator. This invention aims to create a heat exchange system that uses static components only and that is therefore completely reliable whilst remaining simple and relatively economical. This system includes a regeneration heat exchanger (with a primary and secondary system) and a triple flow heat exchanger with three circuits. The first and second circuits are in fluid communication with the primary and secondary circuits of the regeneration heat exchanger. The fluid communication between the regeneration heat exchanger and the triple circuit heat exchanger is such that the process fluid first goes through one of the circuits of the regeneration heat exchanger where it is cooled, then through one of the first two circuits of the triple circuit heat exchanger where it is cooled still more, then through the other of the circuits of the regeneration exchanger where it is heated and finally through the second of the first two circuits of the triple circuit heat exchanger where it is cooled again. A coolant flows through the third circuit in order to cool the process fluid concerned [fr

  13. 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

  14. 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.

  15. 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

  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. Heat exchanger for power generation equipment

    Science.gov (United States)

    Nirmalan, Nirm Velumylm; Bowman, Michael John

    2005-06-14

    A heat exchanger for a turbine is provided wherein the heat exchanger comprises a heat transfer cell comprising a sheet of material having two opposed ends and two opposed sides. In addition, a plurality of concavities are disposed on a surface portion of the sheet of material so as to cause hydrodynamic interactions and affect a heat transfer rate of the turbine between a fluid and the concavities when the fluid is disposed over the concavities.

  18. Use of air/ground heat exchangers for heating and cooling of buildings - in-situ measurements, analytical modeling, numerical simulation and system analysis[Dissertation 3357]; Utilisation des echangeurs air/sol pour le chauffage et le rafraichissement des batiments. Mesures in situ, modelisation analytique, simulation numerique et analyse systemique

    Energy Technology Data Exchange (ETDEWEB)

    Hollmuller, P.

    2002-07-01

    In this thesis, physical properties and practical implementation of air/ground heat exchangers were studied. These exchangers consist in ducts placed in the upper ground layer (up to a depth of several meters). Air is circulated through the ducts, with heat transfer from and to the surrounding earth/sand/gravel material, with heat diffusion (conductive and capacitive effects) through this material. Air/ground heat exchangers are used to preheat or cool the air needed by the ventilation system of a building (open loop systems), or to heat up or cool the air in a greenhouse (closed loop systems). The reported study consisted in: (i) case studies of built examples, by detailed measuring and monitoring and data analysis. (ii) modeling the basic system. (iii) solving the basic equations both numerically (by computerized simulation) and analytically. (iv) identifying the basic features of these systems. (v) establishing recommendations for the practical implementation, especially in what regards sizing. It turned out that daily and seasonal heat storage/delivery by means of an air/ground heat exchanger have to be considered separately, with ad hoc rules of thumb each. Depending on parameter values a phase shift by as much as half the period may even be observed, with very little damping of the temperature oscillation. In Switzerland the main relevance for these systems is for improving thermal comfort in buildings in the summer time when outdoor temperature is higher than 26 {sup o}C, and for damping the amplitude of day/night temperature variations in horticultural greenhouses. The work carried out can be considered as of basic relevance for all applications of the systems studied.

  19. 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.

  20. 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…

  1. 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

  2. Heat exchanger with a removable tube section

    Science.gov (United States)

    Wolowodiuk, W.; Anelli, J.

    1975-07-29

    A heat exchanger is described in which the tube sheet is secured against primary liquid pressure, but which allows for easy removal of the tube section. The tube section is supported by a flange which is secured by a number of shear blocks, each of which extends into a slot which is immovable with respect to the outer shell of the heat exchanger. (auth)

  3. 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.

  4. 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

  5. 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)

  6. 40 CFR 63.654 - Heat exchange systems.

    Science.gov (United States)

    2010-07-01

    ... any one of the criteria in paragraphs (b)(1) through (2) of this section. (1) All heat exchangers that... any heat exchangers that are in organic HAP service as defined in this subpart). (c) The owner or... each heat exchanger exit line for each heat exchanger or group of heat exchangers in organic HAP...

  7. Analysis of a Flooded Heat Exchanger

    Science.gov (United States)

    Fink, Aaron H.; Luyben, William L.

    2015-01-01

    Flooded heat exchangers are often used in industry to reduce the required heat-transfer area and the size of utility control valves. These units involve a condensing vapor on the hot side that accumulates as a liquid phase in the lower part of the vessel. The heat transfer occurs mostly in the vapor space, but the condensate becomes somewhat…

  8. Investigation of Heat Exchange Efficiency in the Heat Exchanger Waste Heat Recovery with Granular Nozzle

    Directory of Open Access Journals (Sweden)

    Boshkova I.L.

    2016-12-01

    Full Text Available The article analyzes the characteristics of the heat transfer process between the dispersed and gaseous medium for the moving and fixed layer of particulate material. The methods of calculus of thermal and hydraulic regimes of heat exchangers with a dense layer of particles were elaborated. The results of experimental studies of the process of heating of different kinds of granular material, intended for use as a nozzle in the recuperative heat exchanger. The influence of the height of heating chamber, the particle diameter on the output temperature of the granular material has been determined. The dependence of the temperature of the gas and solid components of the height of the nozzle has been presented.

  9. 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.

  10. Heat exchanger with transpired, highly porous fins

    Science.gov (United States)

    Kutscher, Charles F.; Gawlik, Keith

    2002-01-01

    The heat exchanger includes a fin and tube assembly with increased heat transfer surface area positioned within a hollow chamber of a housing to provide effective heat transfer between a gas flowing within the hollow chamber and a fluid flowing in the fin and tube assembly. A fan is included to force a gas, such as air, to flow through the hollow chamber and through the fin and tube assembly. The fin and tube assembly comprises fluid conduits to direct the fluid through the heat exchanger, to prevent mixing with the gas, and to provide a heat transfer surface or pathway between the fluid and the gas. A heat transfer element is provided in the fin and tube assembly to provide extended heat transfer surfaces for the fluid conduits. The heat transfer element is corrugated to form fins between alternating ridges and grooves that define flow channels for directing the gas flow. The fins are fabricated from a thin, heat conductive material containing numerous orifices or pores for transpiring the gas out of the flow channel. The grooves are closed or only partially open so that all or substantially all of the gas is transpired through the fins so that heat is exchanged on the front and back surfaces of the fins and also within the interior of the orifices, thereby significantly increasing the available the heat transfer surface of the heat exchanger. The transpired fins also increase heat transfer effectiveness of the heat exchanger by increasing the heat transfer coefficient by disrupting boundary layer development on the fins and by establishing other beneficial gas flow patterns, all at desirable pressure drops.

  11. 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

  12. Heat exchanger fouling: Prediction, measurement, and mitigation

    Science.gov (United States)

    The US Department of Energy (DOE), Office of Industrial Programs (OIP) sponsors the development of innovative heat exchange systems. Fouling is a major and persistent cost associated with most industrial heat exchangers and nationally wastes an estimated 2.9 Quads per year. To predict and control fouling, three OIP projects are currently exploring heat exchanger fouling in specific industrial applications. A fouling probe has been developed to determine empirically the fouling potential of an industrial gas stream and to derive the fouling thermal resistance. The probe is a hollow metal cylinder capable of measuring the average heat flux along the length of the tube. The local heat flux is also measured by a heat flux meter embedded in the probe wall. The fouling probe has been successfully tested in the laboratory at flue gas temperatures up to 2200 F and a local heat flux up to 41,000 BTU/hr sq ft. The probe has been field tested at a coal-fired boiler plant. Future tests at a municipal waste incinerator are planned. Two other projects study enhanced heat exchanger tubes, specifically the effect of enhanced surface geometries on the tube bundle performance. Both projects include fouling in a liquid heat transfer fluid. Identifying and quantifying the factors affecting fouling in these enhanced heat transfer tubes will lead to techniques to mitigate fouling.

  13. Thermal Propulsion Capture System Heat Exchanger Design

    Science.gov (United States)

    Richard, Evan M.

    2016-01-01

    One of the biggest challenges of manned spaceflight beyond low earth orbit and the moon is harmful radiation that astronauts would be exposed to on their long journey to Mars and further destinations. Using nuclear energy has the potential to be a more effective means of propulsion compared to traditional chemical engines (higher specific impulse). An upper stage nuclear engine would allow astronauts to reach their destination faster and more fuel efficiently. Testing these engines poses engineering challenges due to the need to totally capture the engine exhaust. The Thermal Propulsion Capture System is a concept for cost effectively and safely testing Nuclear Thermal Engines. Nominally, hydrogen exhausted from the engine is not radioactive, but is treated as such in case of fuel element failure. The Thermal Propulsion Capture System involves injecting liquid oxygen to convert the hydrogen exhaust into steam. The steam is then cooled and condensed into liquid water to allow for storage. The Thermal Propulsion Capture System concept for ground testing of a nuclear powered engine involves capturing the engine exhaust to be cooled and condensed before being stored. The hydrogen exhaust is injected with liquid oxygen and burned to form steam. That steam must be cooled to saturation temperatures before being condensed into liquid water. A crossflow heat exchanger using water as a working fluid will be designed to accomplish this goal. Design a cross flow heat exchanger for the Thermal Propulsion Capture System testing which: Eliminates the need for water injection cooling, Cools steam from 5800 F to saturation temperature, and Is efficient and minimizes water requirement.

  14. Heat exchangers: an energy viewpoint approach

    International Nuclear Information System (INIS)

    Buchet, E.

    1981-01-01

    This paper, at first, presents a brief discussion of the concept of exergy. The second part studies the exchange of heat by conduction, convection and radiation as well as the irreversibilities due to the required temperature gradient. It shows the importance of the temperature level on the heat flux and the exergy lost. This analysis results also in conclusions on the fins and the thermal insulation. The third part studies the heat exchangers, in general. The loss of exergy due to the thermal exchange permits a comparison of the thermal value of these apparatus and, as well, shows the influence of the isothermal change of state of a fluid, i.e. in vaporization. Finally, based on the conclusions reached above, different types of heat exchangers used in industrial applications are analysed [fr

  15. Lightweight Thermal Storage Heat Exchangers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR proposal aims to develop thermal energy storage heat exchangers that are significantly lighter and higher conductance than the present art which involves...

  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. 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.

  18. 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.

  19. 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

  20. 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.)

  1. Covering of heating load of object by using ground heat as a renewable energy source

    Directory of Open Access Journals (Sweden)

    Čenejac Aleksandra R.

    2012-01-01

    Full Text Available Rational use of energy, improving energy performance of buildings and use of renewable energy sources are the most important measures for reducing consumption of non-renewable primary energy (solid, liquid, and gaseous fuels, environmental protection and for the future sustainable development of mankind. In the total primary energy consumption great part is related to building industry, for heating spaces in which people stay and live. Renewable energy sources (RES present natural resources and they are one of the alternatives that allow obtaining heat for heating buildings, and by that they provide a significant contribution to the energy balance of a country. This paper analyzes the participation of ground source as RES, when the vertical (the probe in the ground and horizontal (registry in the ground heat exchangers are used for covering heating load of the building.

  2. Heat exchanger with auxiliary cooling system

    Science.gov (United States)

    Coleman, John H.

    1980-01-01

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

  3. Observer-based monitoring of heat exchangers.

    Science.gov (United States)

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

    2008-01-01

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

  4. Heat Exchanger With Internal Pin Elements

    Science.gov (United States)

    Gerstmann, Joseph; Hannon, Charles L.

    2004-01-13

    A heat exchanger/heater comprising a tubular member having a fluid inlet end, a fluid outlet end and plurality of pins secured to the interior wall of the tube. Various embodiments additionally comprise a blocking member disposed concentrically inside the pins, such as a core plug or a baffle array. Also disclosed is a vapor generator employing an internally pinned tube, and a fluid-heater/heat-exchanger utilizing an outer jacket tube and fluid-side baffle elements, as well as methods for heating a fluid using an internally pinned tube.

  5. Performance Evaluation of Plate - Fin Heat Exchangers.

    Science.gov (United States)

    1987-06-01

    children for their support, patience, understanding, and love during the preparation of this thesis and for the period of study at M.I.T. I’ .1’ -p...the ordinate values will yiela the number of heat transfer units ratio of the two heat exchangers. The required ratios are: Ren,b AFo On,b Reno AFb Dn...Dn a = Dno) tne frontal area for surface 2 will be greater than surface 1, AF .d > AFo . The same heat exchanger volume implies that the length wii

  6. 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.

  7. Experimental studies on a ground coupled heat pump with solar thermal collectors for space heating

    International Nuclear Information System (INIS)

    Xi, Chen; Hongxing, Yang; Lin, Lu; Jinggang, Wang; Wei, Liu

    2011-01-01

    This paper presents experimental studies on a solar-assisted ground coupled heat pump (SAGCHP) system for space heating. The system was installed at the Hebei Academy of Sciences in Shijiazhuang (lat. N38 o 03', long. E114 o 26'), China. Solar collectors are in series connection with the borehole array through plate heat exchangers. Four operation modes of the system were investigated throughout the coldest period in winter (Dec 5th to Dec 27th). The heat pump performance, borehole temperature distributions and solar colleting characteristics of the SAGCHP system are analyzed and compared when the system worked in continuous or intermittent modes with or without solar-assisted heating. The SAGCHP system is proved to perform space heating with high energy efficiency and satisfactory solar fraction, which is a promising substitute for the conventional heating systems. It is also recommended to use the collected solar thermal energy as an alternative source for the heat pump instead of recharging boreholes for heat storage because of the enormous heat capacity of the earth. -- Highlights: → We study four working modes of a solar-assisted ground coupled heat pump. → The heating performance is in direct relation with the borehole temperature. → Solar-assisted heating elevates borehole temperature and system performance. → The system shows higher efficiency over traditional heating systems in cold areas. → Solar heat is not suggested for high temperature seasonal storage.

  8. Ground Source Heat Supply in Moscow Oblast: Temperature Potential and Sustainable Depth of Heat Wells

    Science.gov (United States)

    Vasil'ev, G. P.; Gornov, V. F.; Dmitriev, A. N.; Kolesova, M. V.; Yurchenko, V. A.

    2018-01-01

    The paper is devoted to a problem of increasing the efficiency of low-potential geothermal heat in heat pump systems of residential buildings the Moscow oblast of Russia, including Moscow. Estimates of a natural geothermal potential in the Moscow oblast (based on climatological data for the period from 1982 to 2011) are presented and a "Typical climatic year of natural soil temperature variations for the geoclimatic conditions of the Moscow oblast, including the city of Moscow" is proposed. Numerical simulation of the influence of geothermal energy potential and the depth of heat wells on the efficiency of ground source heat pump systems for the heat supply of residential buildings is carried out. Analysis of the numerical simulation showed that the operation of a heat pump system in a house heating mode under the geoclimatic conditions of the Moscow oblast leads to a temperature drop of the heat-exchange medium circulating through heat wells to 5-6°C by the end of the first 10 years of operation, and the process stabilizes by the 15th year of operation, and further changes in the heat-exchange medium temperature do not any longer significantly affect the temperature of the heat-exchange medium in the heat well. In this case, the exact dependence of the heat-exchange medium temperature drop on the depth is not revealed. Data on the economically expedient heat well depth for the conditions of the Moscow oblast ensuring a net present value for the whole residential building life cycle are presented. It is found that the heat well depth of 60 m can be considered as an endpoint for the Moscow oblast, and a further heat well deepening is economically impractical.

  9. 21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240... 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...

  10. 40 CFR 63.104 - Heat exchange system requirements.

    Science.gov (United States)

    2010-07-01

    ... heat exchange system or at locations where the cooling water enters and exits each heat exchanger or any combination of heat exchangers. (i) For samples taken at the entrance and exit of recirculating... manufacturing process units. (iii) For samples taken at the entrance and exit of each heat exchanger or any...

  11. Energy absorber for sodium-heated heat exchanger

    Science.gov (United States)

    Essebaggers, J.

    1975-12-01

    A heat exchanger is described in which water-carrying tubes are heated by liquid sodium and in which the results of accidental contact between the water and the sodium caused by failure of one or more of the water tubes is minimized. An energy absorbing chamber contains a compressible gas and is connected to the body of flowing sodium by a channel so that, in the event of a sodium-water reaction, products of the reaction will partially fill the energy absorbing chamber to attenuate the rise in pressure within the heat exchanger.

  12. Ground Source Geothermal District Heating and Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, James William [Ball State Univ., Muncie, IN (United States)

    2016-10-21

    Ball State University converted its campus from a coal-fired steam boiler district heating system to a ground source heat pump geothermal district system that produces simultaneously hot water for heating and chilled water for cooling. This system will include the installation of 3,600 four hundred feet deep vertical closed loop boreholes making it the largest ground source geothermal district system in the country. The boreholes will act as heat exchangers and transfer heat by virtue of the earth’s ability to maintain an average temperature of 55 degree Fahrenheit. With growing international concern for global warming and the need to reduce worldwide carbon dioxide loading of the atmosphere geothermal is poised to provide the means to help reduce carbon dioxide emissions. The shift from burning coal to utilizing ground source geothermal will increase electrical consumption but an overall decrease in energy use and reduction in carbon dioxide output will be achieved. This achievement is a result of coupling the ground source geothermal boreholes with large heat pump chiller technology. The system provides the thermodynamic means to move large amounts of energy with limited energy input. Ball State University: http://cms.bsu.edu/About/Geothermal.aspx

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Carbon nanotube heat-exchange systems

    Science.gov (United States)

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  18. Cooperative heat transfer and ground coupled storage system

    Science.gov (United States)

    Metz, P.D.

    A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.

  19. North Village Ground Source Heat Pump Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Redderson, Jeff

    2015-08-03

    This project demonstrated the feasibility of converting from a traditional direct exchange system to a ground source heat pump system on a large scale, multiple building apartment complex on a university campus. A total of ten apartment buildings were converted using vertical well fields and a ground source loop that connected the 24 apartments in each building into a common system. The system has yielded significant operational savings in both energy and maintenance and transformed the living environments of these residential buildings for our students.

  20. 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.

  1. Investigations into the dynamic behaviour of finned tube heat exchangers

    International Nuclear Information System (INIS)

    Sandbrink, J.; Stegemann, D.

    1981-01-01

    Atmospheric disturbances due to thunder storms, side wind effects on the shell or ground inversion can impair the heat dissipation of a cooling tower. These effects react on the overall power plant, which is reflected in the varied electrical output. This uncontrolled behaviour has been investigated in detail for the case of a boiling water reactor nuclear power station with indirect natural draught dry cooling and compared with controlled performance. A computer model, which has been checked out by means of experimental investigations on three different types of tube, is presented to describe the dynamic behaviour of finned tube heat exchangers. (orig.) [de

  2. Low heat transfer oxidizer heat exchanger design and analysis

    Science.gov (United States)

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

    1987-01-01

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

  3. 14 CFR 29.1125 - Exhaust heat exchangers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 29.1125 Section 29... exchangers. For reciprocating engine powered rotorcraft the following apply: (a) Each exhaust heat exchanger... is subject to contact with exhaust gases; and (4) No exhaust heat exchanger or muff may have stagnant...

  4. 14 CFR 25.1125 - Exhaust heat exchangers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 25.1125 Section 25... exchangers. For reciprocating engine powered airplanes, the following apply: (a) Each exhaust heat exchanger... provisions wherever it is subject to contact with exhaust gases; and (4) No exhaust heat exchanger or muff...

  5. 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.

  6. 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

  7. Measurement of heat and moisture exchanger efficiency.

    Science.gov (United States)

    Chandler, M

    2013-09-01

    Deciding between a passive heat and moisture exchanger or active humidification depends upon the level of humidification that either will deliver. Published international standards dictate that active humidifiers should deliver a minimum humidity of 33 mg.l(-1); however, no such requirement exists, for heat and moisture exchangers. Anaesthetists instead have to rely on information provided by manufacturers, which may not allow comparison of different devices and their clinical effectiveness. I suggest that measurement of humidification efficiency, being the percentage moisture returned and determined by measuring the temperature of the respired gases, should be mandated, and report a modification of the standard method that will allow this to be easily measured. In this study, different types of heat and moisture exchangers for adults, children and patients with a tracheostomy were tested. Adult and paediatric models lost between 6.5 mg.l(-1) and 8.5 mg.l(-1) moisture (corresponding to an efficiency of around 80%); however, the models designed for patients with a tracheostomy lost between 16 mg.l(-1) and 18 mg.l(-1) (60% efficiency). I propose that all heat and moisture exchangers should be tested in this manner and percentage efficiency reported to allow an informed choice between different types and models. © 2013 The Association of Anaesthetists of Great Britain and Ireland.

  8. Exergo-ecological evaluation of heat exchanger

    Directory of Open Access Journals (Sweden)

    Stanek Wojciech

    2014-01-01

    Full Text Available Thermodynamic optimization of thermal devices requires information about the influence of operational and structural parameters on its behaviour. The interconnections among parameters can be estimated by tools such as CFD, experimental statistic of the deviceetc. Despite precise and comprehensive results obtained by CFD, the time of computations is relatively long. This disadvantage often cannot be accepted in case of optimization as well as online control of thermal devices. As opposed to CFD the neural network or regression is characterized by short computational time, but does not take into account any physical phenomena occurring in the considered process. The CFD model of heat exchanger was built using commercial package Fluent/Ansys. The empirical model of heat exchanger has been assessed by regression and neural networks based on the set of pseudo-measurements generated by the exact CFD model. In the paper, the usage of the developed empirical model of heat exchanger for the minimisation of TEC is presented. The optimisationconcerns operational parameters of heat exchanger. The TEC expresses the cumulative exergy consumption of non-renewable resources. The minimization of the TEC is based on the objective function formulated by Szargut. However, the authors extended the classical TEC by the introduction of the exergy bonus theory proposed by Valero. The TEC objective function fulfils the rules of life cycle analysis because it contains the investment expenditures (measured by the cumulative exergy consumption of non-renewable natural resources, the operation of devices and the final effects of decommissioning the installation.

  9. 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 ...

  10. Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers

    Science.gov (United States)

    Lawrence D. Garrett; Howard Duchacek; Mariafranca Morselli; Frederick M. Laing; Neil K. Huyler; James W. Marvin

    1977-01-01

    A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was similar to syrup produced in conventional systems in flavor and in chemical and physical composition; and (3) Heat...

  11. 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 ...

  12. Heat Transfer of Nanofluid in a Double Pipe Heat Exchanger.

    Science.gov (United States)

    Aghayari, Reza; Maddah, Heydar; Zarei, Malihe; Dehghani, Mehdi; Kaskari Mahalle, Sahar Ghanbari

    2014-01-01

    This paper investigates the enhancement of heat transfer coefficient and Nusselt number of a nanofluid containing nanoparticles (γ-AL2O3) with a particle size of 20 nm and volume fraction of 0.1%-0.3% (V/V). Effects of temperature and concentration of nanoparticles on Nusselt number changes and heat transfer coefficient in a double pipe heat exchanger with counter turbulent flow are investigated. Comparison of experimental results with valid theoretical data based on semiempirical equations shows an acceptable agreement. Experimental results show a considerable increase in heat transfer coefficient and Nusselt number up to 19%-24%, respectively. Also, it has been observed that the heat transfer coefficient increases with the operating temperature and concentration of nanoparticles.

  13. 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.

  14. 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

  15. Preliminary SP-100/Stirling heat exchanger designs

    International Nuclear Information System (INIS)

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

    1993-12-01

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

  16. NUMERICAL AND EXPERIMENTAL ANALYSIS OF UNSTEADY WORK OF U-SHAPE BOREHOLE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    S. A. Filatau

    2014-01-01

    Full Text Available Unsteady numerical model of borehole heat exchanger heat regime was developed. General numerical modeling results are borehole heat flux, heat carrier inlet temperature and average soil temperature distribution. Proposed model is based on solution of heat conduction equation in transient plane axially symmetric formulation with boundary conditions for borehole heat exchanger and undisturbed soil domain. Solution method is finite difference method. Numerical model is verified with comparisons numerical results and experimental data from developed laboratory installation for simulation unsteady heat regime of horizontal positioned U-shape ground heat exchanger in sand medium.Cooling of water is organized in ground exchanger in experiment. Experiment includes two steps. Thermal properties of sand is determined at the first stage. Thermal conductivity of sand is determined by stationary plate method, thermal diffusivity is determined by regular regime method using cylindrical calorimeter. Determined properties are used further in processing of experimental results at second step for analysis of transient work of ground heat exchanger. Results of four experiments are analyzed with different duration and time behavior of mass flow and heat carrier temperature. Divergences of experimental and simulated results for temperature of heat carrier changes in the range 0,5–1,8 %, for sand temperature in the range 1,0–2,3 %, for heat flux in the range 3,6–5,4 %. Experimental results can be used for validation of other simulation methods of ground heat exchangers. Presented numerical model can be used for analyzing of heat supply systems with heat pumps.

  17. Thermal induced flow oscillations in heat exchangers for supercritical fluids

    Science.gov (United States)

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

    1972-01-01

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

  18. Fan Duct Heat Exchanger for Turbine Cooling Air, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposal is for the design of a fan duct heat exchanger in order to improve aircraft fuel burn. The fan duct heat exchanger decreases the temperature of the 15%...

  19. Selection of materials for heat exchangers

    International Nuclear Information System (INIS)

    Rodriguez, P.

    1997-01-01

    This paper provides a frame work for selecting heat exchangers materials especially those used in nuclear power plants. Typical examples of materials selection for heat exchanger tubing of nuclear power plants and condensers are presented. The paper brings out also, the importance of continued intensive R and D in materials in order to enhance the reliability and reduce cost by improving upon the existing materials by minor additions of alloying elements or new materials. The properties of Cr- Mo - alloys with minor additions of W, V, Nb and N are discussed in view of their use at elevated temperatures in the power industry. These alloys were found to provide considerable operation flexibility due to their low expansion coefficient and high thermal conductivity in comparison with the austenitic stainless steels. Also, the Ni base alloy Inconel 617. Could be selected for his excellent combination of creep and hot corrosion resistance up to a temperature of a 50 degree C. 2 figs., 7 tabs

  20. 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.

  1. Conceptualizations for cleaning OTEC heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rice, M.S.; Hagel, D.; Conn, A.F.

    1978-09-01

    A critical operating aspect of Ocean Thermal Energy Conversion (OTEC) plants is the maintenance of clean surfaces on the seawater-side of the heat exchangers. The objective of this program was to assess the state of the art of biofouling control techniques and to evaluate the potential of these existing methods for solving the biofouling problems in the OTEC system. The first task of the program involved an in-depth review and discussion of various fouling control methods including water treatment, surface conditioning, and cleaning techniques. The methods considered applicable to OTEC were identified. This volume summarizes the second task of the program. The compatibility of the various cleaning and fouling control techniques with the different proposed heat exchanger designs and materials are discussed. Also provided are conceptual illustrations for adapting and incorporating the methods into an OTEC power plant. These conceptual designs suggest means for overcoming some of the shortcomings of the techniques which are considered suitable, however, detailed designs of the modified systems are beyond the scope of this report. Chlorination, chemical cleaning, Amertap recirculating sponge rubber balls, and MAN flow-driven brushes are the methods considered applicable for tubular heat exchangers with seawater inside the tubes. Water jets are suggested for the open-cycle and the ''trombone'' (Applied Physics Laboratory) heat exchanger designs. Although none of the methods are immediately applicable to OTEC in their present configuration, in several cases only minor developmental efforts should produce designs which can satisfy the stringent OTEC cleanliness requirements. Further research and development appear warranted for a number of other methods which indicate promise for long-range applicability. Specific recommendations are included.

  2. 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

  3. 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

  4. Geothermal energy. Ground source heat pumps

    International Nuclear Information System (INIS)

    2009-01-01

    Geothermal energy can be harnessed in 2 different ways: electricity or heat generation. The combined net electrical geothermal power of the European Union countries reached 719.3 MWe in 2008 (4.8 MW up on 2007) for 868.1 MWe of installed capacity. Gross electrical production contracted slightly in 2008 (down 1% on the 2007 level) and stood at 5809.5 GWh in 2008. Italy has a overwhelming position with a production of 5520.3 GWh. Geothermal heat production concerning aquifers whose temperature is 30-150 C. degrees generally at a depth of 1-3 km is called low- and medium-enthalpy energy. 18 of the 27 EU members use low- and medium-enthalpy energy totaling 2560.0 MWth of installed capacity that yielded 689.2 ktoe in 2008 and 3 countries Hungary, Italy and France totaling 480.3 ktoe. Very low-enthalpy energy concerns the exploitation of shallow geothermal resources using geothermal heat pumps. In 2008, 114452 ground heat pumps were sold in Europe. At the end of 2008, the installed capacity was 8955.4 MWth (16.5% up on 2007 level, it represented 785206 pumps. Over one million ground heat pumps are expected to be operating in 2010 in Europe. (A.C.)

  5. 40 CFR 63.1435 - Heat exchanger provisions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Heat exchanger provisions. 63.1435... Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63.1435 Heat exchanger... for heat exchange systems, with the exceptions noted in paragraphs (b) through (e) of this section. (b...

  6. 14 CFR 23.1125 - Exhaust heat exchangers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust heat exchangers. 23.1125 Section 23... § 23.1125 Exhaust heat exchangers. For reciprocating engine powered airplanes the following apply: (a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, inertia, and...

  7. 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.

  8. Heat exchanger for cooling liquid metal

    International Nuclear Information System (INIS)

    Mine, Masao; Nakao, Noboru; Ikeuchi, Toshiaki; Okabe, Ayao.

    1988-01-01

    Purpose: To improve the maintenance performance and heat resistance in heat exchangers integrated with solenoid pumps in the main coolant circuits of LMFBR type reactors. Constitution: Annular cores equipped with solenoid coils are disposed to the outside of the shell portion of a heat exchanger, while only annular cores are disposed to the inside of the shell and a flow channel for liquid metals is disposed between solenoid coils and the cores to constitute a structure of causing solenoid pump action. Then, the cores with coils generate magnetic fields and pumping action is caused by the Lorentz force due to the magnetic fields and the electric current generated in liquid metals in the flow channel between the cores and the shell, thereby driving the liquid metals. Accordingly, since the coils are disposed to the outside of the shell, the maintenance for the solenoid coils is facilitated, the heat resistant design and conditions for the coils are moderated and the sodium resistance is no more required to be considered. (Horiuchi, T.)

  9. Integrated Heat Exchange For Recuperation In Gas Turbine Engines

    Science.gov (United States)

    2016-12-01

    DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE INTEGRATED HEAT EXCHANGE FOR RECUPERATION IN GAS TURBINE ENGINES 5. FUNDING NUMBERS 6. AUTHOR...ship gas turbines is difficult due the size and weight of the heat exchanger components required. An alternate approach would be to embed a heat ... exchange system within the engine using existing blade surfaces to extract and insert heat . Due to the highly turbulent and transient flow, heat

  10. Characteristics of heat flow in recuperative heat exchangers

    Directory of Open Access Journals (Sweden)

    Lalović Milisav

    2005-01-01

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

  11. 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

  12. Heat exchanger life extension via in-situ reconditioning

    Science.gov (United States)

    Holcomb, David E.; Muralidharan, Govindarajan

    2016-06-28

    A method of in-situ reconditioning a heat exchanger includes the steps of: providing an in-service heat exchanger comprising a precipitate-strengthened alloy wherein at least one mechanical property of the heat exchanger is degraded by coarsening of the precipitate, the in-service heat exchanger containing a molten salt working heat exchange fluid; deactivating the heat exchanger from service in-situ; in a solution-annealing step, in-situ heating the heat exchanger and molten salt working heat exchange fluid contained therein to a temperature and for a time period sufficient to dissolve the coarsened precipitate; in a quenching step, flowing the molten salt working heat-exchange fluid through the heat exchanger in-situ to cool the alloy and retain a supersaturated solid solution while preventing formation of large precipitates; and in an aging step, further varying the temperature of the flowing molten salt working heat-exchange fluid to re-precipitate the dissolved precipitate.

  13. Microchannel Heat Exchangers with Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-09-15

    The objective of the present study was to determine the performance of CO{sub 2} microchannel evaporators and gas coolers in operational conditions representing those of residential heat pumps. A set of breadboard prototype microchannel evaporators and gas coolers was developed and tested. The refrigerant in the heat exchangers followed a counter cross-flow path with respect to the airflow direction. The test conditions corresponded to the typical operating conditions of residential heat pumps. In addition, a second set of commercial microchannel evaporators and gas coolers was tested for a less comprehensive range of operating conditions. The test results were reduced and a comprehensive data analysis, including comparison with the previous studies in this field, was performed. Capacity and pressure drop of the evaporator and gas cooler for the range of parameters studied were analyzed and are documented in this report. A gas cooler performance prediction model based on non-dimensional parameters was also developed and results are discussed as well. In addition, in the present study, experiments were conducted to evaluate capacities and pressure drops for sub-critical CO{sub 2} flow boiling and transcritical CO{sub 2} gas cooling in microchannel heat exchangers. An extensive review of the literature failed to indicate any previous systematic study in this area, suggesting a lack of fundamental understanding of the phenomena and a lack of comprehensive data that would quantify the performance potential of CO{sub 2} microchannel heat exchangers for the application at hand. All experimental tests were successfully conducted with an energy balance within {+-}3%. The only exceptions to this were experiments at very low saturation temperatures (-23 C), where energy balances were as high as 10%. In the case of evaporators, it was found that a lower saturation temperature (especially when moisture condensation occurs) improves the overall heat transfer coefficient

  14. 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.

  15. 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.

  16. Prototype Vent Gas Heat Exchanger for Exploration EVA - Performance and Manufacturing Characteristics

    Science.gov (United States)

    Quinn, Gregory J.; Strange, Jeremy; Jennings, Mallory

    2013-01-01

    NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation gas loop is a liquid-to-gas heat exchanger to transfer excess heat from the gas to the thermal control system s liquid coolant loop. A unique bench top prototype heat exchanger was built and tested for use in PLSS 2.0. The heat exchanger was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat exchangers manufactured by United Technologies Aerospace Systems (UTAS), but was half the size of any previous heat exchanger model and one third the size of previous liquid-to-gas heat exchangers. The prototype heat exchanger was less than 40 cubic inches and weighed 2.57 lb. Performance of the heat exchanger met the requirements and the model predictions. The water side and gas side pressure drops were less 0.8 psid and 0.5 inches of water, respectively, and an effectiveness of 94% was measured at the nominal air side pressure of 4.1 psia.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-01

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

  18. Materials development for HTGR heat exchangers

    International Nuclear Information System (INIS)

    Johnson, W.R.; Roberts, D.I.

    1983-01-01

    High-temperature, gas-cooled reactors (HTGR's) are uranium/thorium-fueled, graphite-moderated, helium-cooled systems capable of producing high-temperature primary coolant. Several variants of this system are under active development in the United States and worldwide. In one version, the primary coolant heat is transferred to steam generators producing 538 0 C/16.5 MPa steam for use in electricity generation or process heat applications. The materials and design technology for steam generators in this system are well developed, relying heavily upon prior experience with fossil-fired steam generators and the steam generators of the commercial HTGR's. The major work that remains to be done is to complete qualification of the materials and to respond to evolving rules pertinent to elevatedtemperature nuclear design and construction. Other versions of the HTGR generate much higher primary coolant gas temperatures (850 0 to 950 0 C) and exchange this heat, through intermediate heat exchangers (IHX's), to a secondary loop for higher temperature process heat applications. Although IHX's for these systems are typically pressure-balanced (low-stress) units, their design involves several challenges, including the potential interactions between structural materials and impurities present in the HTGR primary coolant. Considerable work is required to qualify materials for IHX applications, including detailed mechanical property characterization, determination of environmental influences on performance, provision of welding materials and procedures for producing joints of adequate strength and integrity, and provisions for wear protection. Some of the work currently under way addressing these issues is described

  19. 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)

  20. 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.

  1. Heat recovery from ground below the solar pond

    NARCIS (Netherlands)

    Ganguly, S.; Date, Abhijit; Akbarzadeh, Aliakbar

    2017-01-01

    The method of heat recovery from the ground below solar ponds is investigated in the present brief note. Solar ponds lose considerable amount of heat from its bottom to the ground due to temperature gradient between them. This waste heat from ground, which is at different temperature at different

  2. IMPACT OF GEOTHERMAL GRADIENT ON GROUND SOURCE HEAT PUMP SYSTEM MODELING

    Directory of Open Access Journals (Sweden)

    Tomislav Kurevija

    2014-07-01

    Full Text Available ndisturbed ground temperature is one of the most crucial thermogeological parameters needed for shallow geothermal resources assessment. Energy considered to be geothermal is energy stored in the ground at depths where solar radiation has no effect. At depth where undisturbed ground temperature occurs there is no influence of seasonal variations in air temperature from surface. Exact temperature value, and depth where it occurs, is functionally dependent on surface climate parameters and thermogeologic properties of ground. After abovementioned depth, increase of ground temperature is solely dependent on geothermal gradient. Accurately determined value of undisturbed ground temperature is beneficial for proper sizing of borehole heat exchangers. On practical example of building which is being heated and cooled with shallow geothermal resource, influences of undisturbed ground temperature and geothermal gradient, on size of borehole heat exchanger are going to be presented. Sizing of borehole heat exchanger was calculated with commercial software Ground Loop Designer (GLD, which uses modified line source and cylinder source solutions of heat conduction in solids.

  3. An analysis of solar assisted ground source heat pumps in cold climates

    International Nuclear Information System (INIS)

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

    2015-01-01

    Highlights: • The work focuses on solar assisted ground source heat pump in cold climates. • Multi-year simulations of SAGSHP, are carried out in six cold locations. • GSHP and SAGSHP are compared. • The effect of total borehole length on the heat pump energy efficiency is studied. • A dedicated control strategy is used to manage both solar and ground loops. - Abstract: Exploiting renewable energy sources for air-conditioning has been extensively investigated over recent years, and many countries have been working to promote the use of renewable energy to decrease energy consumption and CO 2 emissions. Electrical heat pumps currently represent the most promising technology to reduce fossil fuel usage. While ground source heat pumps, which use free heat sources, have been taking significant steps forward and despite the fact that their energy performance is better than that of air source heat pumps, their development has been limited by their high initial investment cost. An alternative solution is one that uses solar thermal collectors coupled with a ground source heat pump in a so-called solar assisted ground source heat pump. A ground source heat pump system, used to heat environments located in a cold climate, was investigated in this study. The solar assisted ground source heat pump extracted heat from the ground by means of borehole heat exchangers and it injected excess solar thermal energy into the ground. Building load profiles are usually heating dominated in cold climates, but when common ground source heat pump systems are used only for heating, their performance decreases due to an unbalanced ground load. Solar thermal collectors can help to ensure that systems installed in cold zones perform more efficiently. Computer simulations using a Transient System Simulation (TRNSYS) tool were carried out in six cold locations in order to investigate solar assisted ground source heat pumps. The effect of the borehole length on the energy efficiency of

  4. 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

  5. Integration of Heat Exchangers with Thermoelectric Modules

    DEFF Research Database (Denmark)

    Rezaniakolaei, Alireza

    2017-01-01

    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......Fundamentally, it is essential to have some basic components in a thermoelectric generator (TEG) system to be able to harvest energy. To achieve a high-performance system with overall efficiency close to conversion efficiency of thermoelectric materials, the components need to be considered...

  6. 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

  7. Systems for heat and cold from the ground. Proposal for a development program; System foer vaerme och kyla ur mark - Foerslag till utvecklingsprogram

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, Bengt; Gabrielsson, Anna; Fallsvik, Jan; Nilsson, Gunnel [Swedish Geotechnical Inst., Linkoeping (Sweden); Hellstroem, Goeran [Lund Inst. of Technology (Sweden). Dept. of Mathematical Physics

    2002-02-01

    Ground heat systems usually consist of a heat pump, with an evaporator connected to a heat carrier circuit of heat exchangers in the ground, and a condenser connected to the heat distribution system inside the building (radiators, fan convectors, floor heating etc). The heat pump's compressor is connected to the electricity grid. Similar systems without heat pumps are also used, where the excess heat from the building or process is exchanged with the cooler ground solely by circulation of the heat carrier fluid in the ground heat exchangers, so called 'Tree cooling'. The performance of ground heat systems depends on several factors. There is a continuous development of components and their interaction in heating/cooling systems, both in Sweden and abroad. Based on the current state of the art of ground heat systems and the national energy market it is possible to identify the development potential within many areas. In this report the development potentials for ground heat systems are presented in the following program areas: Combined heating/cooling systems with or without heat pumps and improvements of existing systems. Horizontal, compact and vertical ground heat exchangers, installation methods. Geological prerequisites and geotechnical impact of heating and/or cooling. Thermal capacity of all types of ground heat exchangers including moisture transport effects. Design specifications for different types of ground heat exchangers and ground conditions. Operation and maintenance. Environmental impact, e.g. of heat carrier fluids and local government environmental protection requirements. Economic optimization based on verified technical performance and cost figures.

  8. Shell-and-double concentric-tube heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Bougriou, Cherif; Baadache, Khireddine [University of Batna, Department of Mechanics, Batna (Algeria)

    2010-03-15

    This study concerns a new type of heat exchangers, which is that of shell-and-double concentric-tube heat exchangers. These heat exchangers can be used in many specific applications such as air conditioning, waste heat recovery, chemical processing, pharmaceutical industries, power production, transport, distillation, food processing, cryogenics, etc. The case studies include both design calculations and performance calculations. It is demonstrated that the relative diameter sizes of the two tubes with respect to each other are the most important parameters that influence the heat exchanger size. (orig.)

  9. 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

  10. 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

  11. 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

  12. A Project to Design and Build Compact Heat Exchangers

    Science.gov (United States)

    Davis, Richard A.

    2005-01-01

    Students designed and manufactured compact, shell-and-tube heat exchangers in a project-based learning exercise integrated with our heat transfer course. The heat exchangers were constructed from common building materials available at home improvement centers. The cost of materials for a device was less than $20. The project gave students…

  13. 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.

  14. 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 ...

  15. 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.

  16. Heat exchanger for fuel cell power plant reformer

    Science.gov (United States)

    Misage, Robert; Scheffler, Glenn W.; Setzer, Herbert J.; Margiott, Paul R.; Parenti, Jr., Edmund K.

    1988-01-01

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

  17. Optimal Ground Source Heat Pump System Design

    Energy Technology Data Exchange (ETDEWEB)

    Ozbek, Metin [Environ Holdings Inc., Princeton, NJ (United States); Yavuzturk, Cy [Univ. of Hartford, West Hartford, CT (United States); Pinder, George [Univ. of Vermont, Burlington, VT (United States)

    2015-04-01

    Despite the facts that GSHPs first gained popularity as early as the 1940’s and they can achieve 30 to 60 percent in energy savings and carbon emission reductions relative to conventional HVAC systems, the use of geothermal energy in the U.S. has been less than 1 percent of the total energy consumption. The key barriers preventing this technically-mature technology from reaching its full commercial potential have been its high installation cost and limited consumer knowledge and trust in GSHP systems to deliver the technology in a cost-effective manner in the market place. Led by ENVIRON, with support from University Hartford and University of Vermont, the team developed and tested a software-based a decision making tool (‘OptGSHP’) for the least-cost design of ground-source heat pump (‘GSHP’) systems. OptGSHP combines state of the art optimization algorithms with GSHP-specific HVAC and groundwater flow and heat transport simulation. The particular strength of OptGSHP is in integrating heat transport due to groundwater flow into the design, which most of the GSHP designs do not get credit for and therefore are overdesigned.

  18. Heat exchanger and water tank arrangement for passive cooling system

    Science.gov (United States)

    Gillett, James E.; Johnson, F. Thomas; Orr, Richard S.; Schulz, Terry L.

    1993-01-01

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

  19. Experimental Research and Simulation of Fin and Tube Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Artur Rubcov

    2017-09-01

    Full Text Available The paper provides the results of experimental and theoretical test of a wavy fin and tube heat exchanger used to cool air in a ventilation system when the wavy fin of the heat exchanger is dry and wet. The experimental tests, performed in the range of 1000heat transfer coefficient on the supplied air flow rate with the varying geometry of the heat exchanger (the number of tube rows, the distance between fins, the thickness of the fin and the diameter of the tube. The experimental tests were performed on 9 heat exchangers in heating and 6 heat exchangers in cooling mode. After processing the results of the experimental tests, empirical equation defining the characteristics of the heat transfer coefficient of all heat exchangers were derived. The maximum heat transfer coefficient deviation is 11.6 percent. The correction factor of the wet fin (Lewis number depending on the number of Reynolds, which ranges from 0.75 to 1.1 also is determined. Maximum capacity deviation equals 3.7 percent. The obtained equations can only be applied to a certain group of heat exchangers (with the same shape of fins or the distance between the tubes. The results of the experimental test and simulation with ANSYS program are compared and the heat transfer coefficients vary from 6.5 to 11.4 percent.

  20. 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)

  1. Analysis of fabrication process for AP1000 passive residual heat removal heat exchanger

    International Nuclear Information System (INIS)

    Gao Yongjun

    2011-01-01

    This paper introduces the design parameters of the passive residual heat removal heat exchanger for American advanced passive pressurized water reactor (AP1000), describes the fabrication process for the head, tubesheet, heat exchange tube, corrugated plate and support frame assembly of the heat exchanger, mainly in terms of material, forging, welding, and heat treatment, and also analyzes the crucial steps for the support frame assembling, tubesheet plate welding, tube penetration welding of C tube bundle, closure/head welding, heat treatment, hydraulic (pressure) test, and etc. in the process of heat exchanger assembling. (author)

  2. Condensing Heat Exchanger with Hydrophilic Antimicrobial Coating

    Science.gov (United States)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor)

    2014-01-01

    A multi-layer antimicrobial hydrophilic coating is applied to a substrate of anodized aluminum, although other materials may form the substrate. A silver layer is sputtered onto a thoroughly clean anodized surface of the aluminum to about 400 nm thickness. A layer of crosslinked, silicon-based macromolecular structure about 10 nm thickness overlies the silver layer, and the outermost surface of the layer of crosslinked, silicon-based macromolecular structure is hydroxide terminated to produce a hydrophilic surface with a water drop contact angle of less than 10.degree.. The coated substrate may be one of multiple fins in a condensing heat exchanger for use in the microgravity of space, which has narrow channels defined between angled fins such that the surface tension of condensed water moves water by capillary flow to a central location where it is pumped to storage. The antimicrobial coating prevents obstruction of the capillary passages.

  3. Ground-source heat pump barometer

    International Nuclear Information System (INIS)

    Anon.

    2011-01-01

    In Europe the ground-source heat pump market contracted for the second year running by 2.9% between 2009 and 2010. Around 103.000 units were sold in 2010, taking the number of installed units over one million. The 3 European countries with the most sales are Sweden (31953 units, +16%), Germany (25516 units, -13%) and France (12250 units, -21%). The drop in sales is generally due to market contraction on the current recession but some specificities exist: for instance the insufficient training of the installers has led to under-performance and to a bad image of this energy in France. The Swedish and German manufacturers are in a very strong position and are increasing their market share in the main European markets. (A.C.)

  4. 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.

  5. Fouling corrosion in aluminum heat exchangers

    Directory of Open Access Journals (Sweden)

    Su Jingxin

    2015-06-01

    Full Text Available Fouling deposits on aluminum heat exchanger reduce the heat transfer efficiency and cause corrosion to the apparatus. This study focuses on the corrosive behavior of aluminum coupons covered with a layer of artificial fouling in a humid atmosphere by their weight loss, Tafel plots, electrochemical impedance spectroscopy (EIS, and scanning electron microscope (SEM observations. The results reveal that chloride is one of the major elements found in the fouling which damages the passive film and initiates corrosion. The galvanic corrosion between the metal and the adjacent carbon particles accelerates the corrosive process. Furthermore, the black carbon favors the moisture uptake, and gives the dissolved oxygen greater chance to migrate through the fouling layer and form a continuous diffusive path. The corrosion rate decreasing over time is conformed to electrochemistry measurements and can be verified by Faraday’s law. The EIS results indicate that the mechanism of corrosion can be interpreted by the pitting corrosion evolution mechanism, and that pitting was observed on the coupons by SEM after corrosive exposure.

  6. 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

  7. 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…

  8. 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.

  9. The solution of private problems for optimization heat exchangers parameters

    Science.gov (United States)

    Melekhin, A.

    2017-11-01

    The relevance of the topic due to the decision of problems of the economy of resources in heating systems of buildings. To solve this problem we have developed an integrated method of research which allows solving tasks on optimization of parameters of heat exchangers. 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 author 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.

  10. 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

  11. Corrosion of heat exchanger materials under heat transfer conditions

    International Nuclear Information System (INIS)

    Tapping, R.L.; Lavoie, P.A.; Disney, D.J.

    1986-01-01

    Severe pitting has occurred in moderator heat exchangers tubed with Incoloy-800 in Pickering Nuclear Generating Station. The pitting originated on the cooling water side (outside) of the tubes and perforation occurred in less than two years. It was known from corrosion testing at Chalk River Laboratories 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. 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. (author). 3 refs., 4 tabs., 6 figs

  12. 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

  13. Thermodynamics of heat-and material-exchange in engineering

    Energy Technology Data Exchange (ETDEWEB)

    Matz, W.

    1944-05-23

    This book-length discussion of thermodynamics emphasized the situation of exchanges of heat and materials during various processes. Within the first chapter (on general foundations) the major headings were Points of view and means of representation, Conditions and characteristics of materials, The first law and energy, The second law and entropy, Equilibrium, and The general similarity-principle in heat-and material-exchange. The second chapter (on heat-and material-exchange in counterflow between two phases) had headings The harmonic triangle diagram, The heat exchanger, Heat exchange by means of procedures of blowing, Heating and cooling processes in vessels, Material exchange in couterflow, and Similarity among friction, heat-and material-exchange. The chapter on exchanges between vapor and liquid in single substances discussed evaporation processes and vapor-air mixtures. There were also chapters on exchanges during distillation, adsorption, absorption, and extraction. There was also an extensive bibliography and a collection of 107 diagrams of various types of representatives of thermodynamic relationships. (Some parts of the book appear out of order on the microfilm reels.) 107 diagrams.

  14. 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...

  15. 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.

  16. 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)

  17. 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)

  18. 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.

  19. 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

  20. Self-defrosting recuperative air-to-air heat exchanger

    Science.gov (United States)

    Drake, Richard L.

    1993-01-01

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

  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...

  2. 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...

  3. Development of suitability maps for ground-coupled heat pump systems using groundwater and heat transport models

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Hikari; Itoi, Ryuichi [Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Inatomi, Tadasuke [YBM Co. Ltd., Kishiyama 589-10 Kitahata, Karatsu 847-1211 (Japan); Uchida, Youhei [Geological Survey of Japan, AIST Tsukuba Central 7, Tsukuba 305-8567 (Japan)

    2007-10-15

    The thermophysical properties of subsurface materials (soils, sediments and rocks) and groundwater flow strongly affect the heat exchange rates of ground heat exchangers (GHEs). These rates can be maximized and the installation costs of the ground-coupled heat pump (GCHP) systems reduced by developing suitability maps based on local geological and hydrological information. Such maps were generated for the Chikushi Plain (western Japan) using field-survey data and a numerical modeling study. First, a field-wide groundwater model was developed for the area and the results matched against measured groundwater levels and vertical temperature profiles. Single GHE models were then constructed to simulate the heat exchange performance at different locations in the plain. Finally, suitability maps for GCHP systems were prepared using the results from the single GHE models. Variations in the heat exchange rates of over 40% revealed by the map were ascribed to differences in the GHE locations, confirming how important it is to use appropriate thermophysical data when designing GCHP systems. (author)

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

    Science.gov (United States)

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

    2012-11-01

    A new kind of ultrasonically-assisted heat exchanger has been designed, built and studied. It can be seen as a vibrating heat exchanger. A comprehensive description of the overall experimental set-up is provided, i.e. of the test rig and the acquisition system. Data acquisition and processing are explained step-by-step with a detailed example of graph obtained and how, from these experimental data, energy balance is calculated on the heat exchanger. It is demonstrated that ultrasound can be used efficiently as a heat transfer enhancement technique, even in such complex systems as heat exchangers. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. 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)

  6. Direct-contact closed-loop heat exchanger

    Science.gov (United States)

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1984-01-01

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

  7. 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.

  8. 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

  9. Ground-source Heat Pump Barometer

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-09-15

    The double whammy dealt by the economic crisis and housing slump has stifled expansion of the ground-source heat pump market in many European countries. The European Union market contracted for the second year running (by 2.9% between 2009 and 2010), and this despite the fact that more than 100,000 units were sold over the twelve-month period, taking the number of installed units past the one million mark. [French] La crise economique ainsi que la crise immobiliere qui touchent de nombreux pays europeens ne facilitent pas l'essor du marche de la pompe a chaleur geothermique. Pour la deuxieme annee consecutive, le marche de l'union europeenne est en baisse (-2,9 % entre 2009 et 2010). il parvient tout de meme a se maintenir au-dessus des 100 000 unites vendues par an, ce qui lui permet de depasser pour la premiere fois le cap du million d'unites installees.

  10. Modelling of Thermal Behavior of Borehole Heat Exchangers of Geothermal Heat Pump Heating Systems

    Directory of Open Access Journals (Sweden)

    Gornov V.F.

    2016-01-01

    Full Text Available This article reports results of comparing the accuracy of the software package “INSOLAR.GSHP.12”, modeling non-steady thermal behavior of geothermal heat pump heating systems (GHCS and of the similar model “conventional” using finite difference methods for solving spatial non-steady problems of heat conductivity. The software package is based on the method of formulating mathematical models of thermal behavior of ground low-grade heat collection systems developed by INSOLAR group of companies. Equations of mathematical model of spatial non-steady thermal behavior of ground mass of low-grade heat collection system obtained by the developed method have been solved analytically that significantly reduced computing time spent by the software complex “INSOLAR.GSHP.12” for calculations. The method allows to turn aside difficulties associated with information uncertainty of mathematical models of the ground thermal behavior and approximation of external factors affecting the ground. Use of experimentally obtained information about the ground natural thermal behavior in the software package allows to partially take into account the whole complex of factors (such as availability of groundwater, their velocity and thermal behavior, structure and arrangement of ground layers, the Earth’s thermal background, precipitation, phase transformations of moisture in the pore space, and more, significantly influencing the formation of thermal behavior of the ground mass of a low-grade geothermal heat collection system. Numerical experiments presented in the article confirmed the high convergence of the results obtained through the software package “INSOLAR.GSHP.12” with solutions obtained by conventional finite-difference methods.

  11. Technically exploitable geothermal energy by using Borehole Heat Exchangers: A revisit of the Cologne case

    Science.gov (United States)

    Shao, Haibing; Hein, Philipp; Bucher, Anke; Kolditz, Olaf

    2017-04-01

    In previous studies, the amount of shallow geothermal energy was estimated by assuming a uniform temperature drop of at least 2 °C in the aquifer. In this work, a more comprehensive numerical model has been employed to evaluate the technically exploitable geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems. A case study on the city of Cologne was revisited, adopting the same hydrogeological conditions and simulating the long-term evolution of the subsurface temperature field subject to the operation of borehole heat exchangers. It is found that the cities' heating demand could potentially be fully covered by BHE-coupled GSHP systems. The resulting equivalent uniform temperature drop is then around 1.6 °C . It was also found that utilising geothermal energy will lead to at least 50% reduction of CO2 equivalent emission in comparison to conventional district heating, depending on the source of electricity used for heat pump operation.

  12. 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.

  13. 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

  14. 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

  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. 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 sele...

  17. Exchange of moisture between atmosphere and ground regarding tritium transfer

    International Nuclear Information System (INIS)

    Bunnenberg, C.

    1980-09-01

    Two measuring equipment have been developed in the framework of this study which fulfill important conditions to avoid microclimatic interferences during measurement by using site-specific ground samples and embedding these in the ground surface. The beta-absorption lysimeter allows the detection of a minimum deposit height of 0.001 mm in a 1 mm sample layer. The conductivity moisture probe is to measure the moisture diffusion within the first 80 mm of the upper ground with a vertical spacial resolution of 2 mm. It is possible to measure a minimum water content increase of 0.02 wt% per 2 mm ground layer using this probe. The influences of single microclimatic parameter on condensation and evaporation were investigated and a transport equation was developed. Investigations in the Negev proved the application ability of the measuring equipment. The application of the transport equation showed very good agreement with the measured values. When the ground surface starts to cool in the afternoon, there is a countercurrent moisture transport from the atmosphere and the deeper ground layers which lead to a higher water content in the upper ground layer. At about 50 mm depth there is an overlapping layer of the two moisture flows which remains almost constant over the 24 h cycle. This exchange zone of atmospheric humidity and ground water must be paid great attention with regard to HTO transfer. (orig./HP) [de

  18. 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

  19. Dimensional Analysis of Ocean Thermal Energy Conversion Heat Exchangers

    Science.gov (United States)

    1977-06-30

    34Utilisation des Forces Naturelles ," Avenir de l’dlectricit6, Revue Scientifigue, pp 370- 372 (Sept. 17, 1881). 2 Claude, Georges, "Power From the...34 fluid side of heat exchanger 11. Convective heat transfer MT" 3 -1 coefficient of working fluid WF 12. Specific heat of working fluid C L2T𔃼e" p WY 13...Viscosity of sea water MT 1 L 12. Sea water pressure drop through AtP MT- 2 L-1 -heat exchanger SW 13. Sea water convective heat h MT- 3 e 1 transfer

  20. Thermal analysis of double-pipe heat exchanger in thermodynamic vent system

    International Nuclear Information System (INIS)

    Liu, Zhan; Li, Yanzhong; Zhou, Ke

    2016-01-01

    Highlights: • The thermodynamic analysis of TVS heat exchanger is investigated. • One quasi-steady state model is established to investigate the thermal performance of double-pipe heat exchanger. • The external natural convection, inner forced convection and the annular two-phase boiling are coupled. • The effect of the external natural convection should be given enough attention in the ground condition. • The influence of the pipe size is studied. - Abstract: Full use and effective management of cold capacity are significant for improving the performance of heat exchanger in the thermodynamic vent system (TVS). To understand the operation principle of TVS easily, the thermodynamic analysis, based on the ideal gas state equation and energy conservation equation, is detailed introduced. Some key operation parameters are optimized and suggested. As the low mass flow rate and low heat fluxes are involved in flow boiling of the annular pipe fluid, the Kandlikar’s boiling heat transfer correlation is selected to predict the flow boiling process, after validated with the related experimental results. One quasi-steady state model is established to investigate the heat transfer performance of double-pipe heat exchanger in normal gravity, with the bulk fluid natural convection, annular pipe two-phase boiling and inner pipe forced convection coupled from outside to inside. Determined by the local pressure and temperature, the fluid thermophysical properties are variable with the pipe length and time. With the variable fluid thermophysical properties, both the static analysis and the transient thermal performance of TVS heat exchanger are investigated respectively. Meanwhile, effects of the external natural convection and the pipe sizes on the thermal and flow performance of heat exchanger are detailed researched and analyzed. Some valuable conclusions are obtained and significant to optimize the TVS heat exchanger design.

  1. Basic Principles for Calculating Heat Exchanger Characteristics under Conditions of Environmental Heat Losses

    Directory of Open Access Journals (Sweden)

    B. A. Bayrashevsky

    2007-01-01

    Full Text Available The paper considers two most characteristic models of heat exchange mechanisms in heaters with due account of environmental heat losses. As a result of executed investigations a list of corresponding engineering formulae has been developed which can be used for determination of heat engineering characteristics of heat exchangers and calculation of heating modes of their operation.Authors of the paper have elaborated a special «Heat Exchanger» programming file that corroborates reliability of the executed analysis and makes it possible to carry out a number of the required calculations.

  2. 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

  3. 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.

  4. 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.

  5. The application of ground source heat pumps to a subdivision-wide district heating system

    International Nuclear Information System (INIS)

    Ciavaglia, L.

    2005-01-01

    Design guidelines for economic ground source heat pumps (GSHP) in district energy systems were presented. The broad economics of using central GSHP in a community district energy system were examined. Design parameters needed to utilize GSHP in district energy system were outlined. The sensitivity of energy prices and the costs of major capital were reviewed. District heating load duration curves were outlined. It was suggested that varying GSHP capacity from 0 to 100 per cent of load was advisable. In addition, capacity should be balanced with gas boiler technology. The amortizing of capital within energy costs was recommended. It was suggested that the best scenario was a minimum of 50 per cent ground energy. Details of pipings and heat exchanger costs were presented, along with costs for gas boilers and gas costs for the district energy system. Charts of current costing and reduction of piping capital were included. It was concluded that GSHP can be a viable component of a district energy system, as a GSHP based district energy system can provide more stable energy prices than conventional fossil fuel systems. It was suggested that sizing of GSHP at, or near, 40 per cent of peak demand provided optimal conditions with respect to energy cost and use of earth energy. tabs., figs

  6. 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

  7. 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

  8. Study of transient behavior of finned coil heat exchangers

    Science.gov (United States)

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

    1993-01-01

    The status of research on the transient behavior of finned coil cross-flow heat exchangers using single phase fluids is reviewed. Applications with available analytical or numerical solutions are discussed. Investigation of water-to-air type cross-flow finned tube heat exchangers is examined through the use of simplified governing equations and an up-wind finite difference scheme. The degenerate case of zero air-side capacitance rate is compared with available exact solution. Generalization of the numerical model is discussed for application to multi-row multi-circuit heat exchangers.

  9. 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

  10. Ground source heat pump performance in case of high humidity soil and yearly balanced heat transfer

    International Nuclear Information System (INIS)

    Schibuola, Luigi; Tambani, Chiara; Zarrella, Angelo; Scarpa, Massimiliano

    2013-01-01

    Highlights: • GSHPs are simulated in case of humid soil and yearly balanced heat transfer. • Humid soil and yearly balanced heat transfer imply higher compactness of GSHPs. • Resulting GSHPs are compared with other traditional and innovative HVAC systems. • GSHPs score best, especially in case of inverter-driven compressors. - Abstract: Ground source heat pump (GSHP) systems are spreading also in Southern Europe, due to their high energy efficiency both in heating and in cooling mode. Moreover, they are particularly suitable in historical cities because of difficulties in the integration of heating/cooling systems into buildings subjected to historical preservation regulations. In these cases, GSHP systems, especially the ones provided with borehole heat exchangers, are a suitable solution instead of gas boilers, air-cooled chillers or cooling towers. In humid soils, GSHP systems are even more interesting because of their enhanced performance due to higher values of soil thermal conductivity and capacity. In this paper, GSHP systems operating under these boundary conditions are analyzed through a specific case study set in Venice and related to the restoration of an historical building. With this analysis the relevant influences of soil thermal conductivity and yearly balanced heat transfer in the design of the borehole field are shown. In particular, the paper shows the possibility to achieve higher compactness of the borehole field footprint area when yearly balanced heat transfer in the borehole field is expected. Then, the second set of results contained in the paper shows how GSHP systems designed for high humidity soils and yearly balanced heat loads at the ground side, even if characterized by a compact footprint area, may still ensure better performance than other available and more common technologies such as boilers, air-cooled chillers, chillers coupled with cooling towers and heat pumps and chillers coupled with lagoon water. As a consequence

  11. A study of Ground Source Heat Pump based on a heat infiltrates coupling model established with FEFLOW

    Science.gov (United States)

    Chen, H.; Hu, C.; Chen, G.; Zhang, Q.

    2017-12-01

    Geothermal heat is a viable source of energy and its environmental impact in terms of CO2 emissions is significantly lower than conventional fossil fuels. it is vital that engineers acquire a proper understanding about the Ground Source Heat Pump (GSHP). In this study, the model of the borehole exchanger under conduction manners and heat infiltrates coupling manners was established with FEFLOW. The energy efficiency, heat transfer endurance and heat transfer in the unit depth were introduced to quantify the energy efficient and the endurance period. The performance of a the Borehole Exchanger (BHE) in soil with and without groundwater seepage was analyzed of heat transfer process between the soil and the working fluid. Basing on the model, the varied regularity of energy efficiency performance an heat transfer endurance with the conditions including the different configuration of the BHE, the soil properties, thermal load characteristic were discussed. Focus on the heat transfer process in multi-layer soil which one layer exist groundwater flow. And an investigation about thermal dispersivity was also analyzed its influence on heat transfer performance. The final result proves that the model of heat infiltrates coupling model established in this context is reasonable, which can be applied to engineering design.

  12. 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.

  13. 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.

  14. 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.)

  15. 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.

  16. Heat Pipe Heat Exchangers with Double Isolation Layers for Prevention of Interpath Leakage Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Current manned spacecraft heat rejection systems use two heat exchangers and an intermediate fluid loop to provide isolation between the crew compartment air and the...

  17. Heat Pipe Heat Exchangers with Double Isolation Layers for Prevention of Interpath Leakage, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Cooling Technologies, Inc. (ACT), supported by Hamilton Sundstrand, proposes to develop a heat pipe heat exchanger that is low mass and provides two levels...

  18. 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.

  19. 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.

  20. Heat exchanger for reactor core and the like

    Science.gov (United States)

    Kaufman, Jay S.; Kissinger, John A.

    1986-01-01

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

  1. 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

  2. Development of diffusion welded compact heat exchanger technology

    International Nuclear Information System (INIS)

    Mortean, M.V.V.; Cisterna, L.H.R.; Paiva, K.V.; Mantelli, M.B.H.

    2016-01-01

    Highlights: • Four new fabrication technologies for compact heat exchanger cores are presented. • The heat exchangers tested are fabricated by diffusion bonding process. • Results showed that cut-plate heat exchanger is the most promising technology. • Experimental results were compared favorably with numerical and analytical results. - Abstract: Compact heat exchangers are heat transfer equipment employed in applications where weight and volume are significantly relevant constraints, such as vehicles (automotive, maritime, avionics and space). The main characteristic of this equipment is the high heat transfer rate for small volumes. Only recently compact heat exchangers have received greater attention from the researchers, and therefore, manufacturing processes and mathematical modeling still demand development. The main objective of this work is to present and analyze four new fabrication technologies for compact heat exchanger cores, resulting in small cross sectional controlled geometry. Three of them consist of sandwiches of flat plates filled with: parallel circular wires, rectangular wires or rectangular tubes. The fourth consists of stacking flat plates interfiled with water jet machined plates. In all these procedures, stacks of metal layers are formed and diffusion bonding process is proposed for soldering. Copper prototypes were constructed to test the fabrication technologies. Results showed that stacking layers of machined comb-like plates interfiled with flat plates is the most promising fabrication technology, which was used to construct a copper prototype that was tested using water as both hot and cold fluids. The present technology was compared for both the volumetric power and the overall heat transfer coefficients with other heat exchangers, presenting an intermediate performance. Experimental results were compared favorably with numerical and analytical results from the literature.

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

    Science.gov (United States)

    Vogel, Steven

    2009-12-01

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

  4. 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.

  5. Oscillating side-branch enhancements of thermoacoustic heat exchangers

    Science.gov (United States)

    Swift, Gregory W.

    2003-05-13

    A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a gas oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the gas oscillates, and first and second heat exchangers, each of which is at one of the two different temperatures. A dead-end side branch into which the gas oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating gas flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating gas volumetric flow rate through the first heat exchanger. This configuration enables the first heat exchanger to be configured and located to better enhance the performance of the heat exchanger rather than being confined to the location and configuration of the regenerator.

  6. 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...

  7. Noise spectra measured on the Dragon reactor primary heat exchanges

    International Nuclear Information System (INIS)

    Cummins, J.D.

    1969-09-01

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

  8. 3D Manufacturing of Integrated Heat Exchangers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase I proposal presents an unprecedented method to do additive manufacturing of integrated heat exchangers for pumped fluid loop with a femtosecond...

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

    NARCIS (Netherlands)

    Brouwers, Jos; van der Geld, C.W.M.

    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

  10. 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

  11. Horizontal ground coupled heat pump: Thermal-economic modeling and optimization

    International Nuclear Information System (INIS)

    Sanaye, Sepehr; Niroomand, Behzad

    2010-01-01

    The modeling and optimizing processes of a Ground Coupled Heat Pump (GCHP) with closed Horizontal Ground Heat eXchanger (HGHX) are presented in this paper. After thermal modeling of GCHP including HGHX, the optimum design parameters of the system were estimated by minimizing a defined objective function (total of investment and operation costs) subject to a list of constraints. This procedure was performed applying Genetic Algorithm technique. For given heating/cooling loads and various climatic conditions, the optimum values of saturated temperature/pressure of condenser and evaporator as well as inlet and outlet temperatures of the water source in cooling and heating modes were predicted. Then, for our case study, the design parameters as well as the configuration of HGHX were obtained. Furthermore, the sensitivity analysis of change in the total annual cost of the system and optimum design parameters with the climatic conditions, cooling/heating capacity, and soil type were discussed.

  12. On the Influence of Operational and Control Parameters in Thermal Response Testing of Borehole Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Borja Badenes

    2017-09-01

    Full Text Available Thermal response test (TRT is a common procedure for characterization of ground and borehole thermal properties needed for the design of a shallow geothermal heat pump system. In order to investigate and to develop more accurate and robust procedures for TRT control, modelling, and evaluation in semi-permeable soils with large water content, a pilot borehole heat exchanger was built in the main campus of the Universitat Politècnica de València. The present work shows the results of the experiments performed at the site, analysing the improvements that have been introduced both in the control of the heat injected during TRTs and in the methods to infer the ground thermal parameter. Three models are compared: two based on the infinite-line source theory and one based on the finite-line source scheme. The models were tested under two possible configurations of the equipment, i.e., with and without strict control of injected heat. Our results show the importance of heat injection control for a robust parameter assessment and the existence of additional heat transfer processes that the used models cannot completely characterize and that are related to the presence of significant groundwater flow at the site. In addition, our experience with the current installation and the knowledge about its strengths and weaknesses have allowed us to design a new and more complete test-site to help in the analysis and validation of new ground heat exchanger geometries.

  13. 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

  14. An introduction to the calculation of continuous heat exchangers

    International Nuclear Information System (INIS)

    Lecocq, Pierre; Llory, Michel; Quinet, J.-L.

    1975-01-01

    Metallic continuous heat exchangers are discussed. They are classified according to the field of application. Heat transfer modes are reviewed (radiation, conduction, convection); the convective modes more frequent in continuous exchangers are emphasized (natural or forced convection with or without phase changes in the fluids involved). Some indications relating to pressure drop calculation in these apparatus are given before the calculation itself. The thermal and hydraulic aspects are stressed and rudiments are given in view of a mechanical study [fr

  15. 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....

  16. Fin Distance Effect at Tube-Fin Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Frana K.

    2013-04-01

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

  17. 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

  18. 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

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

    DEFF Research Database (Denmark)

    Fan, Jianhua; Furbo, Simon; Andersen, Elsa

    2012-01-01

    are theoretically investigated by Computational Fluid Dynamics (CFD) calculations. The heat transfer rates between the PCM storage and the heating fluid/cooling fluid in the plate heat exchangers are determined. The CFD calculated temperatures are compared to measured temperatures. Based on the studies......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...

  20. Ground coupled solar heat pumps: analysis of four options

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, J.W.

    1981-01-01

    Heat pump systems which utilize both solar energy and energy withdrawn from the ground are analyzed using a simplified procedure which optimizes the solar storage temperature on a monthly basis. Four ways of introducing collected solar energy to the system are optimized and compared. These include use of actively collected thermal input to the heat pump; use of collected solar energy to heat the load directly (two different ways); and use of a passive option to reduce the effective heating load.

  1. 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

  2. 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

  3. 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.

  4. Materials for nuclear diffusion-bonded compact heat exchangers

    International Nuclear Information System (INIS)

    Li, Xiuqing; Smith, Tim; Kininmont, David; Dewson, Stephen John

    2009-01-01

    This paper discusses the characteristics of materials used in the manufacture of diffusion bonded compact heat exchangers. Heatric have successfully developed a wide range of alloys tailored to meet process and customer requirements. This paper will focus on two materials of interest to the nuclear industry: dual certified SS316/316L stainless steel and nickel-based alloy Inconel 617. Dual certified SS316/316L is the alloy used most widely in the manufacture of Heatric's compact heat exchangers. Its excellent mechanical and corrosion resistance properties make it a good choice for use with many heat transfer media, including water, carbon dioxide, liquid sodium, and helium. As part of Heatric's continuing product development programme, work has been done to investigate strengthening mechanisms of the alloy; this paper will focus in particular on the effects of nitrogen addition. Another area of Heatric's programme is Alloy 617. This alloy has recently been developed for diffusion bonded compact heat exchanger for high temperature nuclear applications, such as the intermediate heat exchanger (IHX) for the very high temperature nuclear reactors for production of electricity, hydrogen and process heat. This paper will focus on the effects of diffusion bonding process and cooling rate on the properties of alloy 617. This paper also compares the properties and discusses the applications of these two alloys to compact heat exchangers for various nuclear processes. (author)

  5. Numerical and Experimental Investigation for Heat Transfer Enhancement by Dimpled Surface Heat Exchanger in Thermoelectric Generator

    Science.gov (United States)

    Wang, Yiping; Li, Shuai; Yang, Xue; Deng, Yadong; Su, Chuqi

    2016-03-01

    For vehicle thermoelectric exhaust energy recovery, the temperature difference between the heat exchanger and the coolant has a strong influence on the electric power generation, and ribs are often employed to enhance the heat transfer of the heat exchanger. However, the introduction of ribs will result in a large unwanted pressure drop in the exhaust system which is unfavorable for the engine's efficiency. Therefore, how to enhance the heat transfer and control the pressure drop in the exhaust system is quite important for thermoelectric generators (TEG). In the current study, a symmetrical arrangement of dimpled surfaces staggered in the upper and lower surfaces of the heat exchanger was proposed to augment heat transfer rates with minimal pressure drop penalties. The turbulent flow characteristics and heat transfer performance of turbulent flow over the dimpled surface in a flat heat exchanger was investigated by numerical simulation and temperature measurements. The heat transfer capacity in terms of Nusselt number and the pressure loss in terms of Fanning friction factors of the exchanger were compared with those of the flat plate. The pressure loss and heat transfer characteristics of dimples with a depth-to-diameter ratio ( h/D) at 0.2 were investigated. Finally, a quite good heat transfer performance with minimal pressure drop heat exchanger in a vehicle TEG was obtained. And based on the area-averaged surface temperature of the heat exchanger and the Seeback effect, the power generation can be improved by about 15% at Re = 25,000 compared to a heat exchanger with a flat surface.

  6. Sprinkled Heat Exchangers in Evaporation Mode

    Directory of Open Access Journals (Sweden)

    Pospisil J.

    2013-04-01

    Full Text Available The paper presents research on the heat transfer at sprinkled tube bundles situated in a test chamber at atmospheric pressure and low-pressure. Dynamic effects of physical quantities influencing the heat transfer coefficient during boiling are examined experimentally. Experimental results were achieved by means of balance measuring using thermocouple probes and by analysis of thermal diagrams created during operation periods.

  7. 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

  8. Transfer coefficients in elliptical tubes and plate fin heat exchangers

    International Nuclear Information System (INIS)

    Saboya, S.M.

    1979-09-01

    Mean transfer coefficients in elliptical tubes and plate fin heat exchangers were determined by application of heat and mass transfer analogy in conjunction with the naphthalene sublimation technique. The transfer coefficients are presented in a dimensionless form as functions of the Reynolds number. By using the least squares method analytical expressions for the transfer coefficients were determined with low scattering. (E.G.) [pt

  9. 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

  10. Temperature control system for a J-module heat exchanger

    Science.gov (United States)

    Basdekas, Demetrios L.; Macrae, George; Walsh, Joseph M.

    1978-01-01

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

  11. A structured approach to heat exchanger network retrofit design

    NARCIS (Netherlands)

    Van Reisen, J.L.B.

    2008-01-01

    Process plants have high energy consumption. Much energy can be saved by a proper design of the heat exchanger network, which contains the main heat transferring equipment of the plant. Existing plants can often be made more energy-efficient by a retrofit: the (physical) modification of the

  12. Modelling of natural-convection driven heat exchangers

    NARCIS (Netherlands)

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

    2007-01-01

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

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

    African Journals Online (AJOL)

    user

    This study presents pinch analysis of some heat exchanger networks (HENs) problems using Hint integration. (HINT) software. ... after solving the first problem using RPA based heat integration gave a minimum total annual cost (TAC) of $237,. 510 /yr. which .... with continuous variables, whereas HENs problems comprise ...

  14. 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

  15. Characteristics of Vertical Mantle Heat Exchangers for Solar Water Heaters

    DEFF Research Database (Denmark)

    Shah, Louise Jivan; Morrison, G.L.; Behnia, M.

    1999-01-01

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

  16. Micro-structured heat exchanger for cryogenic mixed refrigerant cycles

    Science.gov (United States)

    Gomse, D.; Reiner, A.; Rabsch, G.; Gietzelt, T.; Brandner, J. J.; Grohmann, S.

    2017-12-01

    Mixed refrigerant cycles (MRCs) offer a cost- and energy-efficient cooling method for the temperature range between 80 and 200 K. The performance of MRCs is strongly influenced by entropy production in the main heat exchanger. High efficiencies thus require small temperature gradients among the fluid streams, as well as limited pressure drop and axial conduction. As temperature gradients scale with heat flux, large heat transfer areas are necessary. This is best achieved with micro-structured heat exchangers, where high volumetric heat transfer areas can be realized. The reliable design of MRC heat exchangers is challenging, since two-phase heat transfer and pressure drop in both fluid streams have to be considered simultaneously. Furthermore, only few data on the convective boiling and condensation kinetics of zeotropic mixtures is available in literature. This paper presents a micro-structured heat exchanger designed with a newly developed numerical model, followed by experimental results on the single-phase pressure drop and their implications on the hydraulic diameter.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hafner, Armin

    2003-07-01

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

  19. Investigation of passive residual heat removal system for VVERs: Effects of finned type heat exchanger tubes

    International Nuclear Information System (INIS)

    Ayhan, Hüseyin; Sökmen, Cemal Niyazi

    2016-01-01

    Highlights: • Performance of passive residual heat removal system (PRHRS) of VVER type nuclear power plants is investigated. • Unit heat exchanger of PRHRS is designed to reject 4 MW heat amount from reactor via steam generator. • This study shows that decay heat can be rejected by 16 heat exchangers of PRHRS without any operator actions. - Abstract: After nuclear reactor shutdown, decay heat generation continues in the reactor core and it has the possibility to cause a severe accident. This residual heat has to be removed from the core sufficiently. In Water-Water Energetic Reactors (WWER) or VVERs, passive residual heat removal system is designed to remove decay heat after reactor shutdown. This system does not need any power operation, since ambient air is used as the cooling fluid in heat exchanger. The steam that is generated in the steam generators due to the heat released in the reactor core condenses and rejects its heat to the ambient air within this heat exchanger. The condensed liquid is returned back to the steam generator. The motion of the cooling medium occurs due to natural circulation. In the presented study, the original geometric design of passive residual heat removal system of VVER type nuclear power plants is introduced. The performance of this system is investigated. In the previous study, geometric design parameters for this system was determined for plain tubes of heat exchanger. Heat exchanger tubes were positioned as a helical in the previous study. With the knowledge of enhancing heat transfer using finned surfaces, geometrical design is modified in presented study. Circular type fin structures (having rectangular cross-section) are added to the outer surface of heat exchanger tubes. In the present heat exchanger model, tubes are positioned as a staggered bank. As the fin parameters, fin thickness, fin radius and total fin number are investigated in this study. Results are compared with the one obtained with plane tube (in tube

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  1. Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

    Directory of Open Access Journals (Sweden)

    Andrzejczyk Rafał

    2016-12-01

    Full Text Available The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

  2. Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

    Science.gov (United States)

    Andrzejczyk, Rafał; Muszyński, Tomasz

    2016-12-01

    The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

  3. Sensitivity analysis on the performances of a closed-loop Ground Source Heat Pump

    Science.gov (United States)

    Casasso, Alessandro; Sethi, Rajandrea

    2014-05-01

    Ground Source Heat Pumps (GSHP) permit to achieve a significant reduction of greenhouse gas emissions, and the margins for economic saving of this technology are strongly correlated to the long-term sustainability of the exploitation of the heat stored in the soil. The operation of a GSHP over its lifetime should be therefore modelled considering realistic conditions, and a thorough characterization of the physical properties of the soil is essential to avoid large errors of prediction. In this work, a BHE modelling procedure with the finite-element code FEFLOW is presented. Starting from the governing equations of the heat transport in the soil around a GSHP and inside the BHE, the most important parameters are individuated and the adopted program settings are explained. A sensitivity analysis is then carried on both the design parameters of the heat exchanger, in order to understand the margins of improvement of a careful design and installation, and the physical properties of the soil, with the aim of quantifying the uncertainty induced by their variability. The relative importance of each parameter is therefore assessed by comparing the statistical distributions of the fluid temperatures and estimating the energy consumption of the heat pump, and practical conclusions are from these results about the site characterization, the design and the installation of a BHE. References Casasso A., Sethi R., 2014 Efficiency of closed loop geothermal heat pumps: A sensitivity analysis, Renewable Energy 62 (2014), pp. 737-746 Chiasson A.C., Rees S.J., Spitler J.D., 2000, A preliminary assessment of the effects of groundwater flow on closed-loop ground-source heat pump systems, ASHRAE Transactions 106 (2000), pp. 380-393 Delaleux F., Py X., Olives R., Dominguez A., 2012, Enhancement of geothermal borehole heat exchangers performances by improvement of bentonite grouts conductivity, Applied Thermal Engineering 33-34, pp. 92-99 Diao N., Li Q., Fang Z., 2004, Heat transfer in

  4. Plate type heat exchanger for Reaktor TRIGA PUSPATI

    International Nuclear Information System (INIS)

    Mohd Fairus Abdul Farid; Mohammad Suhaimi Kassim; Mohamad Puad Abu; Mohd Fazli Zakaria; Shaharum Ramli

    2008-08-01

    The PUSPATI TRIGA reactor (RTP) reached its first criticality status on 28 June 1982 with an installed capacity of 1 MW. After 26 years in operation, the ageing process has set in and many systems in the reactor need maintenance and replacement. Among these systems, the more critical one is the heat exchanger system. Currently, the shell and tube type heat exchanger is being used. It has been observed that the performance of the heat exchanger has dropped significantly over the years. Visual inspections indicate that the tubes are corroded or even to the extent of being totally blocked. With this in mind and also with the setting up of the new Nuclear Power Division, whose mission includes upgrading the present reactor to 3 MW, the heat exchanger system is essential and a critical component. Literature indicates that the use of plate type exchangers are more efficient than the current shell and tube type. This paper will look into the engineering and safety aspects of using the plate type heat exchanger to the current TRIGA PUSPATI reactor. (Author)

  5. Carbon-Fiber Brush Heat Exchangers

    Science.gov (United States)

    Knowles, Timothy R.

    2004-01-01

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

  6. Simulation of heat exchangers and heat exchanger networks with an economic aspect

    Directory of Open Access Journals (Sweden)

    E. Kayabasi

    2018-02-01

    Full Text Available Relations between effectiveness (ε and expense coefficients (ζ were derived, and an economic simulation model was developed to simulate heat exchangers (HE and HE networks (HEN in all flow types for the first time. ε values of parallel flow, counter flow, cross flow and all HEs under the condition of Cr = 0 were derived in terms of ζ, NTU (Number of Transfer Unit and minimum heat capacities (Cmin. ε values obtained from economic calculations were used for developing economic simulation model of HEs. Vectors including outlet temperatures and inlet temperatures of flows were obtained from static simulation to utilize in economic simulation model. Then, case studies were performed with counter flow HE and ε values randomly determined in a sample HEN. Use (N, expense (P and savings (E of all HEs in a HEN were calculated easily by the way of linear equation systems without any complex processes, iterations, software and special hardware, in terms of both cold and hot flows properties by using economic simulation model.

  7. Reducing the energy consumption of an earth–air heat exchanger with a PID control system

    International Nuclear Information System (INIS)

    Diaz-Mendez, S.E.; Patiño-Carachure, C.; Herrera-Castillo, J.A.

    2014-01-01

    Highlights: • The application of control actions to green technologies has been simulated. • Energy consumption of green technologies can be reduced even more. • The efficiency of green technologies can be raised. • Environmental concerns can be diminished. • The sustainability of the planet can be increased. - Abstract: Reducing environmental emissions is one of the challenges that human being has to overcome. It can only be reached with a proper energetic efficiency and management of the processes that exist in the society nowadays. Several academic works have mentioned that raising the efficiency of a process it also increases sustainability and in turn decreases the environmental impact. One process that requires much attention is the cooling and heating of buildings; this process contributes to the major part of the electric bill, in particular, if a conventional and old air conditioning is used as commonly occurs in many countries. In recent years there have been developed new alternatives that are used in few countries, such as the earth–air heat exchanger, where air is passed through a heat exchanger buried a few meters below the ground. The heat exchanger takes advantage of the well-known difference between the temperature of the surrounding air and the temperature of the ground for cooling or heating the air that is subsequently injected into the buildings. This process requires less energy, then in the present work is thought that a PID (Proportional, Integral and Derivative) controller can be applied to an earth–air heat exchanger to reduce even more the energy consumption. Therefore, a simulation of a thermodynamic model of an earth–air heat exchanger was done and used along with a PID controller, to estimate savings in energy consumption. The results show that the energy consumption can be reduced up to 87% with the PID control, hence the efficiency of the process is increased as well as the sustainability of the planet and thus the

  8. Characteristics of Vertical Mantle Heat Exchangers for Solar Water Heaters

    DEFF Research Database (Denmark)

    Shah, Louise Jivan; Morrison, G.L.; Behnia, M.

    1999-01-01

    - The flow structure in vertical mantle heat exchangers was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the mantle were measured using a particle Image Velocimetry (PIV) system. A CFD simulation model of vertical mantle heat...... exchangers was also developed for detailed evaluation of the heat flux distribution over the mantle surface. Both the experimental and simulation results indicate that distribution of the flow around the mantle gap is governed by buoyancy driven recirculation in the mantle. The operation of the mantle...

  9. 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

  10. Optimization of Heat Exchangers for Intercooled Recuperated Aero Engines

    Directory of Open Access Journals (Sweden)

    Dimitrios Misirlis

    2017-03-01

    Full Text Available In the framework of the European research project LEMCOTEC, a section was devoted to the further optimization of the recuperation system of the Intercooled Recuperated Aero engine (IRA engine concept, of MTU Aero Engines AG. This concept is based on an advanced thermodynamic cycle combining both intercooling and recuperation. The present work is focused only on the recuperation process. This is carried out through a system of heat exchangers mounted inside the hot-gas exhaust nozzle, providing fuel economy and reduced pollutant emissions. The optimization of the recuperation system was performed using computational fluid dynamics (CFD computations, experimental measurements and thermodynamic cycle analysis for a wide range of engine operating conditions. A customized numerical tool was developed based on an advanced porosity model approach. The heat exchangers were modeled as porous media of predefined heat transfer and pressure loss behaviour and could also incorporate major and critical heat exchanger design decisions in the CFD computations. The optimization resulted in two completely new innovative heat exchanger concepts, named as CORN (COnical Recuperative Nozzle and STARTREC (STraight AnnulaR Thermal RECuperator, which provided significant benefits in terms of fuel consumption, pollutants emission and weight reduction compared to more conventional heat exchanger designs, thus proving that further optimization potential for this technology exists.

  11. Analysis of Heat Transfers inside Counterflow Plate Heat Exchanger Augmented by an Auxiliary Fluid Flow

    Science.gov (United States)

    Khaled, A.-R. A.

    2014-01-01

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

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

    Science.gov (United States)

    Khaled, A-R A

    2014-01-01

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

  13. Air Circulation and Heat Exchange Under Reduced Pressures

    Science.gov (United States)

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

    2010-01-01

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

  14. Phase Change Material (PCM) Heat Exchanger Development

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary focus of the project is to provide future space vehicles a reliable form of long duration supplemental heat rejection (SHREDs). SHREDs allow a vehicle to...

  15. Heat exchangers selection, rating, and thermal design

    CERN Document Server

    Kakaç, Sadik; Pramuanjaroenkij, Anchasa

    2012-01-01

    Praise for the Bestselling Second EditionThe first edition of this work gathered in one place the essence of important information formerly scattered throughout the literature. The second edition adds the following new information: introductory material on heat transfer enhancement; an application of the Bell-Delaware method; new correlation for calculating heat transfer and friction coefficients for chevron-type plates; revision of many of the solved examples and the addition of several new ones.-MEMagazine

  16. 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)

  17. Ground Source Integrated Heat Pump (GS-IHP) Development

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, V. D. [ORNL; Rice, K. [ORNL; Murphy, R. [ORNL; Munk, J. [ORNL; Ally, Moonis [ORNL; Shen, Bo [ORNL; Craddick, William [ORNL; Hearn, Shawn A. [ClimateMaster, Inc.

    2013-05-24

    experience, CM developed a 2nd generation (or beta) prototype in 2012. Field test verification units were fabricated and installed at the ZEBRAlliance site in Oak Ridge in May 2012 and at several sites near CM headquarters in Oklahoma. Field testing of the units continued through February 2013. Annual performance analyses of the beta unit (prototype 2) with vertical well ground heat exchangers (GHX) in 5 U.S. locations predict annual energy savings of 57% to 61%, averaging 59% relative to the minimum efficiency suite and 38% to 56%, averaging 46% relative to the SOA GSHPwDS. Based on the steady-state performance demonstrated by the test units it was projected that the 2nd generation units would achieve ~58% energy savings relative to the minimum efficiency suite at the Zebra Alliance site with horizontal GHX. A new product based on the beta unit design was announced by CM in 2012 – the Trilogy 40® Q-mode™ (http://cmdealernet.com/trilogy_40.html). The unit was formally introduced in a March 2012 press release (see Appendix A) and was available for order beginning in December 2012.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-01

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

  19. BASIMO - Borehole Heat Exchanger Array Simulation and Optimization Tool

    Science.gov (United States)

    Schulte, Daniel O.; Bastian, Welsch; Wolfram, Rühaak; Kristian, Bär; Ingo, Sass

    2017-04-01

    Arrays of borehole heat exchangers are an increasingly popular source for renewable energy. Furthermore, they can serve as borehole thermal energy storage (BTES) systems for seasonally fluctuating heat sources like solar thermal energy or district heating grids. The high temperature level of these heat sources prohibits the use of the shallow subsurface for environmental reasons. Therefore, deeper reservoirs have to be accessed instead. The increased depth of the systems results in high investment costs and has hindered the implementation of this technology until now. Therefore, research of medium deep BTES systems relies on numerical simulation models. Current simulation tools cannot - or only to some extent - describe key features like partly insulated boreholes unless they run fully discretized models of the borehole heat exchangers. However, fully discretized models often come at a high computational cost, especially for large arrays of borehole heat exchangers. We give an update on the development of BASIMO: a tool, which uses one dimensional thermal resistance and capacity models for the borehole heat exchangers coupled with a numerical finite element model for the subsurface heat transport in a dual-continuum approach. An unstructured tetrahedral mesh bypasses the limitations of structured grids for borehole path geometries, while the thermal resistance and capacity model is improved to account for borehole heat exchanger properties changing with depth. Thereby, partly insulated boreholes can be considered in the model. Furthermore, BASIMO can be used to improve the design of BTES systems: the tool allows for automated parameter variations and is readily coupled to other code like mathematical optimization algorithms. Optimization can be used to determine the required minimum system size or to increase the system performance.

  20. Analysis of radiative heat transfer impact in cross-flow tube and fin heat exchangers

    Directory of Open Access Journals (Sweden)

    Hanuszkiewicz-Drapała Małgorzata

    2016-03-01

    Full Text Available A cross-flow, tube and fin heat exchanger of the water – air type is the subject of the analysis. The analysis had experimental and computational form and was aimed for evaluation of radiative heat transfer impact on the heat exchanger performance. The main element of the test facility was an enlarged recurrent segment of the heat exchanger under consideration. The main results of measurements are heat transfer rates, as well as temperature distributions on the surface of the first fin obtained by using the infrared camera. The experimental results have been next compared to computational ones coming from a numerical model of the test station. The model has been elaborated using computational fluid dynamics software. The computations have been accomplished for two cases: without radiative heat transfer and taking this phenomenon into account. Evaluation of the radiative heat transfer impact in considered system has been done by comparing all the received results.

  1. Exergoeconomic analysis of a solar assisted ground-source heat pump greenhouse heating system

    International Nuclear Information System (INIS)

    Ozgener, Onder; Hepbasli, Arif

    2005-01-01

    EXCEM analysis may prove useful to investigators in engineering and other disciplines due to the methodology are being based on the quantities exergy, cost, energy and mass. The main objective of the present study is to investigate between capital costs and thermodynamic losses for devices in solar assisted ground-source heat pump greenhouse heating system (SAGSHPGHS) with a 50 m vertical 32 mm nominal diameter U-bend ground heat exchanger. This system was designed and installed at the Solar Energy Institute, Ege University, Izmir, Turkey. Thermodynamic loss rate-to-capital cost ratios are used to show that, for components and the overall system, a systematic correlation appears to exist between capital cost and exergy loss (total or internal), but not between capital cost and energy loss or external exergy loss. This correlation may imply that devices in successful air conditioning are configured so as to achieve an overall optimal design, by appropriately balancing the thermodynamic (exergy-based) and economic characteristics of the overall system and its devices. The results may, (i) provide useful insights into the relations between thermodynamics and economics, both in general and for SAGSHPGHS (ii) help demonstrate the merits of second-law analysis. It is observed from the results that the maximum exergy destructions in the system particularly occur due to the electrical, mechanical and isentropic efficiencies and emphasize the need for paying close attention to the selection of this type of equipment, since components of inferior performance can considerably reduce the overall performance of the system. In conjunction with this, the total exergy losses values are obtained to be from 0.010 kW to 0.480 kW for the system. As expected, the largest energy and exergy losses occur in the greenhouse and compressor. The ratio of thermodynamic loss rate to capital cost values are obtained for a range from 0.035 to 1.125

  2. Compact heat exchanger technologies for the HTRs recuperator application

    International Nuclear Information System (INIS)

    Thonon, B.; Breuil, E.

    2001-01-01

    Modern HTR nuclear power plants which are now under development (projects GT-MHR, PBMR) are based on the direct cycle concept. This concept leads to a more important efficiency compared to the steam cycle but requires the use of high performance components such as an helium/helium heat exchanger called recuperator to guarantee the cycle efficiency. Using this concept, a net plant efficiency of around 50% can be achieved in the case of an electricity generating plant. As geometric constraints are particularly important for such a gas reactor to limit the size of the primary vessels, compact heat exchangers operating at high pressure and high temperature are attractive potential solutions for the recuperator application. In this frame, Framatome and CEA have reviewed the various technologies of compact heat exchangers used in industry. The first part of the paper will give a short description of the heat exchangers technologies and their ranges of application. In a second part, a selection of potential compact heat exchangers technologies are proposed for the recuperator application. This selection will be based upon their capabilities to cope with the operating conditions parameters (pressure, temperature, flow rate) and with other parameters such as fouling, corrosion, compactness, weight, maintenance and reliability. (author)

  3. Light bulb heat exchanger for magnetohydrodynamic generator applications - Preliminary evaluation

    Science.gov (United States)

    Smith, J. M.; Hwang, C. C.; Seikel, G. R.

    1974-01-01

    The light-bulb heat-exchanger concept is investigated as a possible means of using a combustion heat source to supply energy to an inert gas MHD power generator system. In this concept, combustion gases flow through a central passage which consists of a duct with transparent walls through which heat is transferred by radiation to a radiation receiver which in turn heats the inert gas by convection. The effects of combustion-gas emissivity, transparent-wall-transmissivity, radiation-receiver emissivity, and the use of fins in the inert gas coolant passage are studied. The results indicate that inert gas outlet temperatures of 2500 K are possible for combustion temperatures of 3200 K and that sufficient energy can be transferred from the combustion gas to reduce its temperature to approximately 2000 K. At this temperature more conventional heat exchangers can be used.

  4. Thermal and hydrodynamic considerations of ice slurry in heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Bedecarrats, Jean-Pierre; Strub, Francoise; Peuvrel, Christophe [Laboratoire de Thermique, Energetique et Procedes, Equipe Energetique, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, BP 1155, 64013 Pau Cedex (France)

    2009-11-15

    This article focuses on the behavior in heat exchangers of an ice slurry composed of fine ice particles inside an ethanol-water solution. The heat transfer and friction characteristics were studied in two double pipe heat exchangers, one with a smooth surface and another with an improved surface. Heat transfer coefficients and pressure drops were experimentally investigated for the slurry flowing in the internal tube with ice mass fractions ranging from 0 to 30% and with flow velocities between 0.3 and 1.9 m s{sup -1}. For some flow velocities, the results showed that an increase in the ice fractions caused a change in the slurry flow structure influencing the evolution of the pressure drops and the heat transfer coefficients. Critical ice fraction values were determined corresponding to a change flow structure from laminar to turbulent motion revealed by the evolution of the friction factor. (author)

  5. 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

  6. Foundation Heat Exchanger Final Report: Demonstration, Measured Performance, and Validated Model and Design Tool

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Patrick [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Im, Piljae [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2012-01-01

    Geothermal heat pumps, sometimes called ground-source heat pumps (GSHPs), have been proven capable of significantly reducing energy use and peak demand in buildings. Conventional equipment for controlling the temperature and humidity of a building, or supplying hot water and fresh outdoor air, must exchange energy (or heat) with the building's outdoor environment. Equipment using the ground as a heat source and heat sink consumes less non-renewable energy (electricity and fossil fuels) because the earth is cooler than outdoor air in summer and warmer in winter. The most important barrier to rapid growth of the GSHP industry is high first cost of GSHP systems to consumers. The most common GSHP system utilizes a closed-loop ground heat exchanger. This type of GSHP system can be used almost anywhere. There is reason to believe that reducing the cost of closed-loop systems is the strategy that would achieve the greatest energy savings with GSHP technology. The cost premium of closed-loop GSHP systems over conventional space conditioning and water heating systems is primarily associated with drilling boreholes or excavating trenches, installing vertical or horizontal ground heat exchangers, and backfilling the excavations. This project investigates reducing the cost of horizontal closed-loop ground heat exchangers by installing them in the construction excavations, augmented when necessary with additional trenches. This approach applies only to new construction of residential and light commercial buildings or additions to such buildings. In the business-as-usual scenario, construction excavations are not used for the horizontal ground heat exchanger (HGHX); instead the HGHX is installed entirely in trenches dug specifically for that purpose. The potential cost savings comes from using the construction excavations for the installation of ground heat exchangers, thereby minimizing the need and expense of digging additional trenches. The term foundation heat exchanger

  7. Foundation Heat Exchanger Final Report: Demonstration, Measured Performance, and Validated Model and Design Tool

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Patrick [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Im, Piljae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2012-04-01

    Geothermal heat pumps, sometimes called ground-source heat pumps (GSHPs), have been proven capable of significantly reducing energy use and peak demand in buildings. Conventional equipment for controlling the temperature and humidity of a building, or supplying hot water and fresh outdoor air, must exchange energy (or heat) with the building's outdoor environment. Equipment using the ground as a heat source and heat sink consumes less non-renewable energy (electricity and fossil fuels) because the earth is cooler than outdoor air in summer and warmer in winter. The most important barrier to rapid growth of the GSHP industry is high first cost of GSHP systems to consumers. The most common GSHP system utilizes a closed-loop ground heat exchanger. This type of GSHP system can be used almost anywhere. There is reason to believe that reducing the cost of closed-loop systems is the strategy that would achieve the greatest energy savings with GSHP technology. The cost premium of closed-loop GSHP systems over conventional space conditioning and water heating systems is primarily associated with drilling boreholes or excavating trenches, installing vertical or horizontal ground heat exchangers, and backfilling the excavations. This project investigates reducing the cost of horizontal closed-loop ground heat exchangers by installing them in the construction excavations, augmented when necessary with additional trenches. This approach applies only to new construction of residential and light commercial buildings or additions to such buildings. In the business-as-usual scenario, construction excavations are not used for the horizontal ground heat exchanger (HGHX); instead the HGHX is installed entirely in trenches dug specifically for that purpose. The potential cost savings comes from using the construction excavations for the installation of ground heat exchangers, thereby minimizing the need and expense of digging additional trenches. The term foundation heat exchanger

  8. Intensification of heat exchange by method of interacting flows

    Science.gov (United States)

    Agishev, B. Y.; Varava, A. N.; Dedov, A. V.; Zakharenkov, A. V.; Komov, A. T.

    2017-11-01

    The effectiveness of the heat exchange intensifier “rib-twisted wire” is considered in this paper. The main goal was to study the influence of the wire coiling step t on heat transfer and hydraulic resistance for different values \\dot{H} of the dimensionless height of the edge \\dot{H}, as well as some results on heat exchange during bubbly boiling in an annular channel. Given: • a brief description and an image of the heat exchange intensifier “rib-twisted wire” • generalized results of studies of heat exchange and hydraulic resistance in the annular channel in the single-phase convection with different geometric characteristics of the intensifier • empirical correlations of the generalized experimental results that allow to calculate the coefficient of hydraulic resistance and heat transfer in the range of regime parameters in the single-phase convection that is being studied. • some results of experiments in bubbly boiling regimes and near-critical thermal loads.

  9. Pump/heat exchanger assembly for pool-type reactor

    International Nuclear Information System (INIS)

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

    1989-01-01

    This patent describes a heat exchanger and pump assembly for transferring thermal energy from a heated, first electrically conductive fluid to a pumped, second electrically conductive fluid and for transferring internal energy from the pumped, second electrically conductive fluid to the first electrically conductive fluid, the assembly adapted to be disposed within a pool of the first electrically conductive fluid and comprising: a heat exchanger comprising means for defining a first annularly shaped cavity for receiving a flow of the second electrically conductive fluid and a plurality of tubes disposed within the cavity, whereby the second electrically conductive fluid in the cavity is heated, each of the tubes having an input and an output end. The input ends being disposed at the top of the heat exchanger for receiving from the pool a flow of the first electrically conductive fluid therein. The output ends being disposed at the bottom of and free of the cavity defining means for discharging the first electrically conductive fluid directly into the pool; a pump disposed beneath the heat exchanger and comprised of a plurality of flow couplers disposed in a circular array, each flow coupler comprised of a pump duct for receiving the first electrically conductive fluid and a generator duct for receiving the second electrically conductive fluid

  10. 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

  11. Preliminary results of statistical dynamic experiments on a heat exchanger

    International Nuclear Information System (INIS)

    Corran, E.R.; Cummins, J.D.

    1962-10-01

    The inherent noise signals present in a heat exchanger have been recorded and analysed in order to determine some of the statistical dynamic characteristics of the heat exchanger. These preliminary results show that the primary side temperature frequency response may be determined by analysing the inherent noise. The secondary side temperature frequency response and cross coupled temperature frequency responses between primary and secondary are poorly determined because of the presence of a non-stationary noise source in the secondary circuit of this heat exchanger. This may be overcome by correlating the dependent variables with an externally applied noise signal. Some preliminary experiments with an externally applied random telegraph type of signal are reported. (author)

  12. 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

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

    Science.gov (United States)

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

    2014-04-01

    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.

  14. 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

  15. Effect of Corrugation Angle on Heat Transfer Studies of Viscous Fluids in Corrugated Plate Heat Exchangers

    Directory of Open Access Journals (Sweden)

    B Sreedhara Rao

    2015-04-01

    Full Text Available In the present investigation heat transfer studies are conducted in corrugated plate heat exchangers (PHEs having three different corrugation angles of 300, 400 and 500. The plate heat exchangers have a length of 30 cm and a width of 10 cm with a spacing of 5 mm. Water and 20% glycerol solution are taken as test fluids and hot fluid is considered as heating medium. The wall temperatures are measured along the length of exchanger at seven different locations by means of thermocouples. The inlet and outlet temperatures of test fluid and hot fluid are measured by means of four more thermocouples. The experiments are conducted at a flowrate ranging from 0.5 lpm to 6 lpm with the test fluid. Film heat transfer coefficient and Nusselt number are determined from the experimental data. These values are compared with different corrugation angles. The effects of corrugation angles on heat transfer rates are discussed.

  16. Failure analysis of dissimilar weld in heat exchanger

    Directory of Open Access Journals (Sweden)

    Carlos R. Corleto

    2017-10-01

    Full Text Available The failure analysis of a dissimilar weld in a heat exchanger has been conducted. Within hours of being placed in service, the circumferential weld joining the carbon steel shell to the duplex stainless steel tubesheet experienced partial cracking as H2S was being introduced into the exchanger. The cracking of the weld was determined to be associated with sulfide-stress corrosion cracking facilitated by high weld hardness levels and local dilution of chemistry in the weld.

  17. Performance Evaluation of Heat Exchangers in a Polyethylene Plant

    Directory of Open Access Journals (Sweden)

    Barinaadaa Thaddeus Lebele-Alawa

    2013-01-01

    Full Text Available This paper evaluates the performance of three heat exchanger units (2-E-2301, 3-E-901 and 3-E-401 in a polyethylene plant. Steady state monitoring and direct collection of data from the equipment in the plant were performed and the data were analyzed by using energy equations to determine the overall heat transfer coefficient, heat duty, temperature and pressure range of hot and cold fluids, capacity ratio and effectiveness. The results show that for 2-E-2301, the overall heat transfer coefficient is over 50 percent less than the design figure and the heat duty is over 75 percent than the design figure. For the 3-E-901 the heat duty and the overall heat transfer are over 75 percent less than the design figure which was traceable to fouling. This affected the effectiveness, capacity ratio and temperature range of the hot and cold fluid. For the 3-E-401, the heat duty was found to be within the limit of design figure. The temperature difference in the hot fluid side and the capacity ratio were within the limits of the design figure. Thus, the results show qualitative performance evaluation of the heat exchangers.

  18. Exergy optimization in a steady moving bed heat exchanger.

    Science.gov (United States)

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

    2009-04-01

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

  19. Thermal conductivity distributed from a Thermal Response Test (TRT in a borehole heat exchanger (BHE

    Directory of Open Access Journals (Sweden)

    A. Blasi

    2012-12-01

    Full Text Available The Thermal Response Test (TRT is the most versatile tool to determine the thermal propriety of the underground for designing and sizing of the borehole heat exchangers (BHE. The TRT permits to get the average thermal conductivity (λ across the whole stratigraphy, the thermal resistance (Rb of the borehole / grout / rocks and the undisturbed temperature of the soil (Tg. The ground temperature is influenced by climate, topographical, geological and hydrological factors. Vertical temperature changes allows to get the relationships with the lithology and especially with the groundwater. Vertical temperature log, acquired during and after the TRT, permits to calculate the distributed thermal conductivity over each stratigraphic interval. This method permits to verify how the different lithologies and the groundwater contribute to the heat exchange in the borehole/ground system, so called geoexchange. The experimental site test indicates that the marls and clayed-marls levels show a higher thermal inertia than the sandstone ones and then lower values of thermal conducivity. The sandstones have a higher thermal conductivity with a rapid cooling and they provide the main contribution to the ground heat exchange. The distributed thermal conductivity is an useful tool for designing the BHE with the best performance, a better economic return and with low environmental impacts.

  20. 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

  1. Simultaneous optimization of water and heat exchange networks

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhiyou; Hou, Yanlong; Li, Xiaoduan; Wang, Jingtao [Tianjin University, Tianjin (China)

    2014-04-15

    This paper focuses on the simultaneous optimization of the heat-integrated water allocation networks. A mathematic model is established to illustrate the modified state-space representation of this problem. An easy logical method is employed to help identify the streams of hot or cold ones. In this model, the water exchange networks (WEN), heat exchange networks (HEN), and the interactions between the WEN and HEN combine together as one unity. Thus, the whole network can be solved at one time, which enhances the possibility to get a global optimal result. Examples from the literature and a PVC plant are analyzed to illustrate the accuracy and applicability of this method.

  2. Internal dust recirculation system for a fluidized bed heat exchanger

    Science.gov (United States)

    Gamble, Robert L.; Garcia-Mallol, Juan A.

    1981-01-01

    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 in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

  3. 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 ......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...

  4. Transfer coefficients for plate fin and elliptical tube heat exchangers

    International Nuclear Information System (INIS)

    Saboya, S.M.; Saboya, F.E.M.

    1981-01-01

    In order to determine transfer coefficients for plate fin and elliptical tube exchangers, mass transfer experiments have been performed using the naphthalene sublimation technique. By means of the heat-mass transfer analogy, the results can be converted to heat transfer results. The transfer coefficients were compared with those for circular tube exchangers and the comparison revealed no major differences. This is a positive outcome, since the use of elliptical tubes may reduce substantially the pressure drop, without affecting the transfer characteristics.(Author) [pt

  5. Investigation of the tube side flow distribution in heat exchangers

    International Nuclear Information System (INIS)

    AbuRomia, M.M.; Pyare, R.

    1977-01-01

    The tube side flow distribution in heat exchangers is being investigated through the solution of the governing equations of fluid mechanics with distributed resistances that simulate the presence of the tubes. The modeling scheme used in the analysis and the numerical methods of solving the governing equations are described. The analysis is applied to the CRBRP-Intermediate Heat Exchanger (IHX), where its tube side plenum is simulated by several models that approximate its spherical boundary. The flow field within the plenum and the distribution of the total flow rate among the tubes are determined by the analysis

  6. Predicted and measured velocity distribution in a model heat exchanger

    International Nuclear Information System (INIS)

    Rhodes, D.B.; Carlucci, L.N.

    1984-01-01

    This paper presents a comparison between numerical predictions, using the porous media concept, and measurements of the two-dimensional isothermal shell-side velocity distributions in a model heat exchanger. Computations and measurements were done with and without tubes present in the model. The effect of tube-to-baffle leakage was also investigated. The comparison was made to validate certain porous media concepts used in a computer code being developed to predict the detailed shell-side flow in a wide range of shell-and-tube heat exchanger geometries

  7. Thermal performances of a "black box" heat exchanger in district heating system

    Science.gov (United States)

    Genić, Srbislav B.; Jaćimović, Branislav M.; Milovančević, Uroš M.; Ivošević, Miloš M.; Otović, Milena M.; Antić, Milan I.

    2018-03-01

    The procedure for field testing of plate heat exchanger, considered as a black box, is presented in the paper. After the field measurements have been conducted, simple but unambiguous procedure has been used to establish heat performance parameters including the heat duty and fouling factor. Advantage of hereby presented method is that it can be used for analysis of any other similar heat transfer equipment.

  8. Parametric simulation and experimental analysis of earth air heat exchanger with solar air heating duct

    OpenAIRE

    Sanjeev Jakhar; Rohit Misra; M.S. Soni; Nikhil Gakkhar

    2016-01-01

    Earth air heat exchanger (EAHE) systems are insufficient to meet the thermal comfort requirements in winter conditions. The low heating potential of such systems can be improved by integrating the system with solar air heating duct (SAHD). The aim of this paper is to present a model to estimate the heating potential for EAHE system with and without SAHD. The model is generated using TRNSYS 17 simulation tool and validated against experimental investigation on an experimental set-up in Ajmer, ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-06-01

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

  10. Optimization of heat exchanger networks using genetic algorithms

    International Nuclear Information System (INIS)

    Teyssedou, A.; Dipama, J.; Sorin, M.

    2004-01-01

    Most thermal processes encountered in the power industry (chemical, metallurgical, nuclear and thermal power stations) necessitate the transfer of large amounts of heat between fluids having different thermal potentials. A common practice applied to achieve such a requirement consists of using heat exchangers. In general, each current of fluid is conveniently cooled or heated independently from each other in the power plant. When the number of heat exchangers is large enough, however, a convenient arrangement of different flow currents may allow a considerable reduction in energy consumption to be obtained (Linnhoff and Hidmarsh, 1983). In such a case the heat exchangers form a 'Heat Exchanger Network' (HEN) that can be optimized to reduce the overall energy consumption. This type of optimization problem, involves two separates calculation procedures. First, it is necessary to optimize the topology of the HEN that will permit a reduction in energy consumption to be obtained. In a second step the power distribution across the HEN should be optimized without violating the second law of thermodynamics. The numerical treatment of this kind of problem requires the use of both discrete variables (for taking into account each heat exchanger unit) and continuous variables for handling the thermal load of each unit. It is obvious that for a large number of heat exchangers, the use of conventional calculation methods, i.e., Simplexe, becomes almost impossible. Therefore, in this paper we present a 'Genetic Algorithm' (GA), that has been implemented and successfully used to treat complex HENs, containing a large number of heat exchangers. As opposed to conventional optimization techniques that require the knowledge of the derivatives of a function, GAs start the calculation process from a large population of possible solutions of a given problem (Goldberg, 1999). Each possible solution is in turns evaluated according to a 'fitness' criterion obtained from an objective

  11. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger

    Science.gov (United States)

    Ungar, Eugene K.; Schunk, Richard G.

    2011-01-01

    An active thermal control system architecture has been modified to include a regenerative heat exchanger (regenerator) inboard of the radiator. Rather than using a radiator bypass valve a regenerative heat exchanger is placed inboard of the radiators. A regenerator cold side bypass valve is used to set the return temperature. During operation, the regenerator bypass flow is varied, mixing cold radiator return fluid and warm regenerator outlet fluid to maintain the system setpoint. At the lowest heat load for stable operation, the bypass flow is closed off, sending all of the flow through the regenerator. This lowers the radiator inlet temperature well below the system set-point while maintaining full flow through the radiators. By using a regenerator bypass flow control to maintain system setpoint, the required minimum heat load to avoid radiator freezing can be reduced by more than half compared to a radiator bypass system.

  12. Numerical Simulation of Different Models of Heat Pipe Heat Exchanger Using AcuSolve

    Directory of Open Access Journals (Sweden)

    Zainal Nurul Amira

    2017-01-01

    Full Text Available In this paper, a numerical simulation of heat pipe heat exchanger (HPHE is computed by using CFD solver program i.e. AcuSolve. Two idealized model of HPHE are created with different variant of entry’s dimension set to be case 1 and case 2. The geometry of HPHE is designed in SolidWorks and imported to AcuSolve to simulate the fluid flow numerically. The design of HPHE is the key to provide a heat exchanger system to work proficient as expected. Finally, the result is used to optimize and improving heat recovery systems of the increasing demand for energy efficiency in industry.

  13. Experimental analysis of an air–water heat pump with micro-channel heat exchanger

    International Nuclear Information System (INIS)

    Brignoli, Riccardo; Cecchinato, Luca; Zilio, Claudio

    2013-01-01

    A multi-port extruded (MPE) aluminium flat tube air heat exchanger was compared to a round tube finned coil (FC). The MPE heat exchanger has parallel flow vertical tube configuration with headers in horizontal position and conventional folded louvred fins. The two heat exchangers were mounted on a 10 kW cooling capacity R410A packaged air heat pump. They were sized to approximately obtain the same cooling and heating capacities in chiller and heating mode, respectively. Climatic room steady state tests without frosting phenomena occurring during heat pump operation, demonstrated that the round tube and the flat tube heat exchanger performance are comparable. The MPE heat exchanger was tested with different refrigerant inlet distributor/outlet tubes configurations to investigate the effect of liquid refrigerant distribution. Cycling frosting/defrosting operations were tested with two equivalent machines placed in parallel outdoor and working at full load condition, one of the units was equipped with the MPE heat exchanger while the other mounted a standard finned coil. Penalization factors were analytically introduced to evaluate frosting associated heating energy and energy efficiency degradation. Test results indicate that both the heat pumps are penalized by frost formation but both the penalization factors are higher for the MPE-unit than the FC-unit one in the −6 to 4 °C air dry bulb temperature range. For the two units, a roughly linear dependence of the heating energy penalization factor and of the energy efficiency factor from the difference between outdoor air and saturated air at the evaporation temperature humidity ratio can be pointed out. - Highlights: ► A multi-port aluminium flat tube heat exchanger was compared to a round tube finned one in a heat pump application. ► In steady state tests without frosting the round and the flat tube heat exchanger are comparable. ► Different inlet distributor/outlet tubes configurations were tested to

  14. Modeling of Rocket Fuel Heating and Cooling Processes in the Interior Receptacle Space of Ground-Based Systems

    Directory of Open Access Journals (Sweden)

    K. I. Denisova

    2016-01-01

    Full Text Available The propellant to fill the fuel tanks of the spacecraft, upper stages, and space rockets on technical and ground-based launch sites before fueling should be prepared to ensure many of its parameters, including temperature, in appropriate condition. Preparation of fuel temperature is arranged through heating and cooling the rocket propellants (RP in the tanks of fueling equipment. Processes of RP temperature preparation are the most energy-intensive and timeconsuming ones, which require that a choice of sustainable technologies and modes of cooling (heating RP provided by the ground-based equipment has been made through modeling of the RP [1] temperature preparation processes at the stage of design and operation of the groundbased fueling equipment.The RP temperature preparation in the tanks of the ground-based systems can be provided through the heat-exchangers built-in the internal space and being external with respect to the tank in which antifreeze, air or liquid nitrogen may be used as the heat transfer media. The papers [1-12], which note a promising use of the liquid nitrogen to cool PR, present schematic diagrams and modeling systems for the RP temperature preparation in the fueling equipment of the ground-based systems.We consider the RP temperature preparation using heat exchangers to be placed directly in RP tanks. Feeding the liquid nitrogen into heat exchanger with the antifreeze provides the cooling mode of PR while a heated air fed there does that of heating. The paper gives the systems of equations and results of modeling the processes of RP temperature preparation, and its estimated efficiency.The systems of equations of cooling and heating RP are derived on the assumption that the heat exchange between the fuel and the antifreeze, as well as between the storage tank and the environment is quasi-stationary.The paper presents calculation results of the fuel temperature in the tank, and coolant temperature in the heat exchanger, as

  15. Fouling detection in heat exchangers by Takagi-Sugeno observers

    International Nuclear Information System (INIS)

    Delrot, Sabrina

    2012-01-01

    The phenomenon of fouling in heat exchangers is currently an important topic. Indeed, the fouling is a costly issue that increases the energy loss (directly or indirectly through an over-sizing of the equipment), and therefore increases the water consumption. As a side effect, fouling increases CO 2 consumption that leads to environmental consequences. Fouling can be detected either on local scale, using expensive and specific sensors or on global scale. Global estimation of fouling can be done by measuring the variation of the mass of the exchanger, or by estimating the efficiency of the exchanger through the transfer coefficient. These two methods require very restricting conditions: a powered exchanger to measure mass variation and a steady state exchanger to estimate the efficiency. The work introduced in this thesis deals with the development of non-linear observers that detect fouling early enough to start an efficient cleaning process. As a beginning, a finite element model of a counter current tubular exchanger was proposed. Then three approaches, based on non-linear Takagi-Sugeno observers, were suggested to detect early fouling in heat exchangers. First approach consisted in a set of observers that estimated the parameters of fouling effect through an interpolation method. The second approach proposed a polynomial Takagi-Sugeno observer, using the theory of sums of squares. Finally, a observer of Takagi-Sugeno type with unknown inputs was developed. As a conclusion, a comparison between those different methods was done. (author)

  16. ASME code considerations for the compact heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Nestell, James [MPR Associates Inc., Alexandria, VA (United States); Sham, Sam [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-31

    The mission of the U.S. Department of Energy (DOE), Office of Nuclear Energy is to advance nuclear power in order to meet the nation's energy, environmental, and energy security needs. Advanced high temperature reactor systems such as sodium fast reactors and high and very high temperature gas-cooled reactors are being considered for the next generation of nuclear reactor plant designs. The coolants for these high temperature reactor systems include liquid sodium and helium gas. Supercritical carbon dioxide (sCO₂), a fluid at a temperature and pressure above the supercritical point of CO₂, is currently being investigated by DOE as a working fluid for a nuclear or fossil-heated recompression closed Brayton cycle energy conversion system that operates at 550°C (1022°F) at 200 bar (2900 psi). Higher operating temperatures are envisioned in future developments. All of these design concepts require a highly effective heat exchanger that transfers heat from the nuclear or chemical reactor to the chemical process fluid or the to the power cycle. In the nuclear designs described above, heat is transferred from the primary to the secondary loop via an intermediate heat exchanger (IHX) and then from the intermediate loop to either a working process or a power cycle via a secondary heat exchanger (SHX). The IHX is a component in the primary coolant loop which will be classified as "safety related." The intermediate loop will likely be classified as "not safety related but important to safety." These safety classifications have a direct bearing on heat exchanger design approaches for the IHX and SHX. The very high temperatures being considered for the VHTR will require the use of very high temperature alloys for the IHX and SHX. Material cost considerations alone will dictate that the IHX and SHX be highly effective; that is, provide high heat transfer area in a small volume. This feature must be accompanied by low pressure drop and mechanical reliability and

  17. Time resolved heat exchange in driven quantum systems

    Science.gov (United States)

    Florencia Ludovico, María; Lim, Jong Soo; Moskalets, Michael; Arrachea, Liliana; Sánchez, David

    2014-12-01

    We study time-dependent heat transport in systems composed of a resonant level periodically forced with an external power source and coupled to a fermionic continuum. This simple model contains the basic ingredients to understand time resolved energy exchange in quantum capacitors that behave as single particle emitters. We analyse the behaviour of the dynamic heat current for driving frequencies within the non-adiabatic regime, showing that it does not obey a Joule dissipation law.

  18. 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.

  19. Heat exchanger networks design with constraints

    International Nuclear Information System (INIS)

    Amidpur, M.; Zoghi, A.; Nasiri, N.

    2000-01-01

    So far there have been two approaches to the problem of heat recovery system design where stream matching constraints exist. The first approach involves mathematical techniques for solving the combinational problem taking due recognition of the constraints. These methodologies are now efficient, still suffer from the problem of taking a significant amount of control and direction away from the designer. The second approach based upon so called pinch technology and involves the use of adaptation of standard problem table algorithm. Unfortunately, the proposed methodologies are not very easy to understand, therefore they fail to provide the insight and generally associated with these approaches. Here, a new pinch based methodology is presented. In this method, we modified the traditional numerical targeting procedure-problem table algorithm which is stream cascade table. Unconstrained groups are established by using of artificial intelligence method such that they have minimum utility consumption among different alternatives. Each group is an individual network, therefore, traditional optimization, used in pinch technology, should be employed. By transferring energy between groups heat recovery can be maximized, then each group designs individually and finally networks combine together. One of the advantages of using this method is simple targeting and easy networks-design. Besides the approach has the potential using of new network design methods such as dual temperature approach, flexible pinch design, pseudo pinch design. It is hoped that this methodology provides insight easy network design

  20. Fluctuation relation for heat exchange in Markovian open quantum systems

    Science.gov (United States)

    Ramezani, M.; Golshani, M.; Rezakhani, A. T.

    2018-04-01

    A fluctuation relation for the heat exchange of an open quantum system under a thermalizing Markovian dynamics is derived. We show that the probability that the system absorbs an amount of heat from its bath, at a given time interval, divided by the probability of the reverse process (releasing the same amount of heat to the bath) is given by an exponential factor which depends on the amount of heat and the difference between the temperatures of the system and the bath. Interestingly, this relation is akin to the standard form of the fluctuation relation (for forward-backward dynamics). We also argue that the probability of the violation of the second law of thermodynamics in the form of the Clausius statement (i.e., net heat transfer from a cold system to its hot bath) drops exponentially with both the amount of heat and the temperature differences of the baths.

  1. Thermal dispersivity based calibration of a numerical borehole heat exchanger model

    Science.gov (United States)

    Wagner, Valentin; Bayer, Peter; Bisch, Gerhard; Klaas, Norbert; Braun, Jürgen; Blum, Philipp

    2013-04-01

    Shallow geothermal energy is used worldwide as a heat and/or cooling source for buildings. The most often used technique to exploit energy from the subsurface is ground source heat pump systems in combination with a borehole heat exchanger (BHE). The BHE consists either of one U-pipe, two U-pipes or a coaxial pipe, which are inserted in a borehole. The remaining void space is filled with a grouting material to improve the thermal connection between the pipes and the subsurface and to protect the subsurface if there is a leakage in the pipes. In the pipes, a heat carrier fluid is circulated to establish a thermal gradient around the BHE and thus promote conductive heat transfer. This causes a temperature anomaly in the subsurface. Extension and magnitude of such temperature anomalies do not only depend on the amount of exchanged energy, but also on the characteristics of the ground and the installed ground source heat pump system itself. In this study, we developed a high-resolution finite element BHE model to simulate the heat propagation from a BHE to the subsurface or vice versa. First, the resulting heat propagation predicted by the numerical model is compared to the analogous analytical solutions. Then the numerical model is calibrated based on a large-scale geothermal tank experiment. The tank has a size of 9m × 6m × 4.5m (length × width × depth), and it hosts a layered artificial aquifer with four BHEs, which are surrounded by a dense temperature sensor network (> 150 PT-100 temperature sensors). In the tank, a hydraulic gradient can be established and thus groundwater flow can be imitated. By calibrating the numerical model, the sensitivity of longitudinal and transversal dispersivity values is evaluated. Our analysis cannot prove that the commonly assumed ratio of 1:10 between transversal and longitudinal dispersivity is correct. Rather, it is shown that there exists a wide range of possible parameter value combinations.

  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. Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development

    Science.gov (United States)

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

    2009-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation gas of a PLSS is collected using a CO2-selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat exchanger using water or liquid carbon dioxide (L CO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. The water condensation from the ventilation gas represents a significant source of potential energy for the warming of the adsorbent bed as it represents as much as half of the energy potential in the moist ventilation gas. Designing a heat exchanger to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously.

  4. 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

  5. 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.

  6. Detailed Theoretical Characterization of a Transcritical CO2 Direct Expansion Ground Source Heat Pump Water Heater

    Directory of Open Access Journals (Sweden)

    Parham Eslami-Nejad

    2018-02-01

    Full Text Available A new avenue in modern heat pump technology is related to the use of natural refrigerants such as carbon dioxide (CO2. The use of CO2 in direct expansion ground source heat pumps (DX-GSHP has also gained significant interest as it offers opportunities for cost reduction of the ground loop, albeit some challenges remain in their development, design and use. To address these challenges and to characterize CO2-DX-GSHP performance for water heating applications, a detailed theoretical model and a fully-instrumented test apparatus was developed and built at CanmetENERGY Research Laboratory. The theoretical model was validated against a set of experimental results and adopted to investigate the performance of the system over a wide operating range. Validation results showed that the model predicts the experimental results within the measurement uncertainty. A detailed system performance analysis was also performed using the theoretical model to understand the system behavior and explore the actions required for performance improvement in future installations. The results of the analysis showed that improper design and control of some components, such as the gas cooler and ground heat exchanger can degrade the system performance by up to 25%, and the heat pump heating capacity by 7.5%.

  7. Ground-source heat pump systems in Norway

    International Nuclear Information System (INIS)

    Stene, Joern

    2007-01-01

    The Norwegian ground source heat pump (GSHP) market is reviewed. Boreholes in bedrock are of growing interest for residential systems and of growing interest for larger systems with thermal recharging or thermal energy storage. Ground water is limited to areas where the water has acceptable purity. Challenges and important boundary conditions include 1) high quality GSHP system requires engineering expertise, 2) new building codes and EU directive 'energy performance of buildings.'(2006), and 3) hydronic floor heating systems in 50 percent of new residences (author) (ml)

  8. 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)

  9. Heat exchanger, particularly liquid sodium heated steam generator

    International Nuclear Information System (INIS)

    Robin, Marcel; Tillequin, Jean.

    1977-01-01

    This invention relates to a liquid sodium heated steam generator the characteristic of which is an annular distribution chamber fed by two independent and diametrically opposed manifolds on a common horizontal axis, issuing respectively into two adjacent compartments made in the chambers on both sides of a vertical transversal partition containing the axis of the casing and extending perpendicularly to the manifolds, each compartment being itself divided into a number of adjacent sectors marked by folded metal sheets fixed to the distributor and shaped so as to present in pairs and with the chamber opposite the manifold issuing into a compartment two independent ducts for distributing the sodium flow [fr

  10. Heat exchanger with intermediate evaporating and condensing fluid

    International Nuclear Information System (INIS)

    Fraas, A.P.

    1978-01-01

    A shell and tube-type heat exchanger, such as a liquid sodium-operated steam generator for use in nuclear reactors, comprises a shell containing a primary fluid tube bundle, a secondary fluid tube bundle at higher elevation, and an intermediate fluid vaporizing at the surface of the primary fluid tubes and condensing at the surface of the secondary fluid tubes

  11. Thermal analysis of shell and tube heat exchangers using artificial ...

    African Journals Online (AJOL)

    A feed-forward artificial neural network is set up to simplify the iterative nature of the design process. This also gives the necessary quick design iteration cycles to reach the optimized design. A design space is created with heat exchanger parameters, and the feed forward network is trained with semi-empirical data.

  12. Minimum gas speed in heat exchangers to avoid particulate fouling

    NARCIS (Netherlands)

    Abd-Elhady, M.S.; Rindt, C.C.M.; Wijers, J.G.; van Steenhoven, A.A.; Bramer, Eduard A.; van der Meer, Theodorus H.

    2004-01-01

    The minimum gas speed for a heat exchanger (HE) at which particulate fouling is avoided is investigated. Fouling experiments have been done with particles of different sizes and different materials running under different gas speeds. It is found that the smallest particles in the flow deposit first

  13. 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.

  14. 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 ...

  15. Finned Tube With Vortex Generators For A Heat Exchanger.

    Science.gov (United States)

    Sohal, Monohar S.; O'Brien, James E.

    2004-09-14

    A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

  16. Heat exchanger with leak detecting double wall tubes

    Science.gov (United States)

    Bieberbach, George; Bongaards, Donald J.; Lohmeier, Alfred; Duke, James M.

    1981-01-01

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

  17. Heat exchanger with intermediate evaporating and condensing fluid

    Science.gov (United States)

    Fraas, Arthur P.

    1978-01-01

    A shell and tube-type heat exchanger, such as a liquid sodium-operated steam generator for use in nuclear reactors, comprises a shell containing a primary fluid tube bundle, a secondary fluid tube bundle at higher elevation, and an intermediate fluid vaporizing at the surface of the primary fluid tubes and condensing at the surface of the secondary fluid tubes.

  18. Heat exchangers. Key factors, markets, technology and innovation policy

    Energy Technology Data Exchange (ETDEWEB)

    Finkbeiner, F.; Gonard, T.; Filiol, B.

    1993-01-01

    This book gives a diagnosis, at the european scale, of the heat exchanger industry, which plays a very important role in many systems and processes, and in most of the economical sectors. The various applicative markets involved are industry, transportation, and residential-tertiary sector. The recent technological developments are reviewed. 53 figs., 23 refs.

  19. Performance evaluation of ground-source heat pump system and development of suitability map for its installation

    Science.gov (United States)

    Shrestha, G.; Uchida, Y.; Yoshioka, M.; Kuronuma, S.

    2015-12-01

    Ground-source heat pump (GSHP) system is an energy efficient and environment friendly technology that uses natural subsurface heat energy stored in the shallow depth for space-heating, space-cooling, snow-melting, hot water supply etc. In Japan, development of this system is gradually increasing, however the rate is still limited due to higher initial cost caused by oversized design of ground heat exchangers. An efficient system that can lower the installation cost should be developed and evaluated for its performance in order to expand the growth of GSHP system in Japan. In addition, development of suitability map to assess appropriate locations for the system installation is essential for optimum design and sustainability. In this study, GSHP system was constructed utilizing an artesian well as ground heat exchanger (GHE) and evaluated its performance. The objective of this study is to develop low cost and high efficiency system. In areas with abundant groundwater and its flow, higher heat exchange rate can be expected leading to cost reduction and energy saving. Further, suitability map was prepared in regional scale to assess the suitable locations where this type of system can be installed. The suitability map was prepared considering local hydrogeological and thermal data. Average coefficient of performance (COP) was found to be 7 during space-cooling operation and 5 during space-heating operation. These values of COP are higher than that of normal air conditioner (air-source heat pump system).

  20. Experimental investigation on an integrated thermal management system with heat pipe heat exchanger for electric vehicle

    International Nuclear Information System (INIS)

    Zou, Huiming; Wang, Wei; Zhang, Guiying; Qin, Fei; Tian, Changqing; Yan, Yuying

    2016-01-01

    Highlights: • An integrated thermal management system is proposed for electric vehicle. • The parallel branch of battery chiller can supply additional cooling capacity. • Heat pipe performance on preheating mode is better than that on cooling mode. • Heat pipe heat exchanger is a feasible choice for battery thermal management. - Abstract: An integrated thermal management system combining a heat pipe battery cooling/preheating system with the heat pump air conditioning system is presented to fulfill the comprehensive energy utilization for electric vehicles. A test bench with battery heat pipe heat exchanger and heat pump air conditioning for a regular five-chair electric car is set up to research the performance of this integrated system under different working conditions. The investigation results show that as the system is designed to meet the basic cabinet cooling demand, the additional parallel branch of battery chiller is a good way to solve the battery group cooling problem, which can supply about 20% additional cooling capacity without input power increase. Its coefficient of performance for cabinet heating is around 1.34 at −20 °C out-car temperature and 20 °C in-car temperature. The specific heat of the battery group is tested about 1.24 kJ/kg °C. There exists a necessary temperature condition for the heat pipe heat exchanger to start action. The heat pipe heat transfer performance is around 0.87 W/°C on cooling mode and 1.11 W/°C on preheating mode. The gravity role makes the heat transfer performance of the heat pipe on preheating mode better than that on cooling mode.

  1. Novel Power Electronics Three-Dimensional Heat Exchanger: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, K.; Cousineau, J.; Lustbader, J.; Narumanchi, S.

    2014-08-01

    Electric drive systems for vehicle propulsion enable technologies critical to meeting challenges for energy, environmental, and economic security. Enabling cost-effective electric drive systems requires reductions in inverter power semiconductor area. As critical components of the electric drive system are made smaller, heat removal becomes an increasing challenge. In this paper, we demonstrate an integrated approach to the design of thermal management systems for power semiconductors that matches the passive thermal resistance of the packaging with the active convective cooling performance of the heat exchanger. The heat exchanger concept builds on existing semiconductor thermal management improvements described in literature and patents, which include improved bonded interface materials, direct cooling of the semiconductor packages, and double-sided cooling. The key difference in the described concept is the achievement of high heat transfer performance with less aggressive cooling techniques by optimizing the passive and active heat transfer paths. An extruded aluminum design was selected because of its lower tooling cost, higher performance, and scalability in comparison to cast aluminum. Results demonstrated a heat flux improvement of a factor of two, and a package heat density improvement over 30%, which achieved the thermal performance targets.

  2. Evaluation of heat exchange performance for primary pressurized water cooler in HTTR

    International Nuclear Information System (INIS)

    Tochio, Daisuke; Nakagawa, Shigeaki

    2006-01-01

    In High Temperature Engineering Test Reactor (HTTR), the rated thermal power of 30 MW, the generated heat at reactor core is finally dissipated at the air-cooler by way of the heat exchangers of the primary cooling system, such as the primary pressurized water cooler (PPWC) and the intermediate heat exchanger (IHX). The heat exchangers in the primary cooling system are required the heat exchange performance to remove reactor generated heat 30 MW under the condition of reactor coolant outlet temperature 850degC/950degC. Therefore, the heat exchanges are required to satisfy the design criteria of heat exchange performance. In this report, heat exchange performance data of the rise-to-power-up test and the in-service operation for the PPWC in the main cooling system was evaluated. Moreover, the evaluated values were compared with the design values, and it is confirmed that PPWC has the required heat exchange performance in the design. (author)

  3. Evaluation of heat exchange performance for secondary pressurized water cooler in HTTR

    International Nuclear Information System (INIS)

    Tochio, Daisuke; Watanabe, Syuji; Saikusa, Akio; Oyama, Sunao; Nemoto, Takahiro; Hamamoto, Shinpei; Shinohara, Masanori; Isozaki, Minoru; Nakagawa, Shigeaki

    2006-02-01

    In High Temperature Engineering Test Reactor (HTTR), the rated thermal power of 30MW, the generated heat at reactor core is finally dissipated at the air-cooler by way of the heat exchangers of the primary cooling system, such as the intermediate heat exchanger (IHX) and the secondary pressurized water cooler (SPWC). The heat exchangers in the main cooling system are required the heat exchange performance to remove the reactor-generated-heat of 30MW under the condition of reactor coolant outlet temperature of 850degC/950degC. Therefore, the heat exchanges are required to satisfy the design criteria of heat exchange performance. In this report, heat exchange performance of the SPWC in the main cooling system was evaluated with the rise-to-power-up test and the in-service operation data. Moreover, evaluated value is compared with designed one, it is confirmed that the SPWC has required heat exchange performance. (author)

  4. Heat exchanger efficiently operable alternatively as evaporator or condenser

    Science.gov (United States)

    Ecker, Amir L.

    1981-01-01

    A heat exchanger adapted for efficient operation alternatively as evaporator or condenser and characterized by flexible outer tube having a plurality of inner conduits and check valves sealingly disposed within the outer tube and connected with respective inlet and outlet master flow conduits and configured so as to define a parallel flow path for a first fluid such as a refrigerant when flowed in one direction and to define a serpentine and series flow path for the first fluid when flowed in the opposite direction. The flexible outer tube has a heat exchange fluid, such as water, flowed therethrough by way of suitable inlet and outlet connections. The inner conduits and check valves form a package that is twistable so as to define a spiral annular flow path within the flexible outer tube for the heat exchange fluid. The inner conduits have thin walls of highly efficient heat transfer material for transferring heat between the first and second fluids. Also disclosed are specific materials and configurations.

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    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.

  7. 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

  8. 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

  9. 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.

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

    Science.gov (United States)

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

    2014-03-01

    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 systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

  11. Intensification of heat and mass transfer by ultrasound: application to heat exchangers and membrane separation processes.

    Science.gov (United States)

    Gondrexon, N; Cheze, L; Jin, Y; Legay, M; Tissot, Q; Hengl, N; Baup, S; Boldo, P; Pignon, F; Talansier, E

    2015-07-01

    This paper aims to illustrate the interest of ultrasound technology as an efficient technique for both heat and mass transfer intensification. It is demonstrated that the use of ultrasound results in an increase of heat exchanger performances and in a possible fouling monitoring in heat exchangers. Mass transfer intensification was observed in the case of cross-flow ultrafiltration. It is shown that the enhancement of the membrane separation process strongly depends on the physico-chemical properties of the filtered suspensions. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Comparing heat flow models for interpretation of precast quadratic pile heat exchanger thermal response tests

    DEFF Research Database (Denmark)

    Alberdi Pagola, Maria; Poulsen, Søren Erbs; Loveridge, Fleur

    2018-01-01

    This paper investigates the applicability of currently available analytical, empirical and numerical heat flow models for interpreting thermal response tests (TRT) of quadratic cross section precast pile heat exchangers. A 3D finite element model (FEM) is utilised for interpreting five TRTs...... by inverse modelling. The calibrated estimates of soil and concrete thermal conductivity are consistent with independent laboratory measurements. Due to the computational cost of inverting the 3D model, simpler models are utilised in additional calibrations. Interpretations based on semi-empirical pile G-functions...... the potential of applying TRTs for sizing quadratic, precast pile heat exchanger foundations....

  13. Active heat exchange system development for latent heat thermal energy storage

    Science.gov (United States)

    Lefrois, R. T.; Mathur, A. K.

    1980-01-01

    Five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants were discussed. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion phase change materials (PCMs) in the temperature range of 250 to 350 C. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. The most attractive major components in the temperature range of 250 to 350 C appeared to be NaNO3, NaNO2, and NaOH. Sketches of the two active heat exchange concepts selected for test are given.

  14. Next Generation Nuclear Plant Intermediate Heat Exchanger Acquisition Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Mizia, Ronald Eugene [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2008-04-01

    DOE has selected the High Temperature Gas-cooled Reactor (HTGR) design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production. It will have an outlet gas temperature in the range of 900°C to 950°C and a plant design service life of 60 years. The reactor design will be a graphite moderated, helium cooled, prismatic or pebble-bed reactor, and use low-enriched uranium, TRISO-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Materials Research and Development (R&D) Program is responsible for performing R&D on likely NGNP materials in support of the NGNP design, licensing, and construction activities. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while at the same time setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. The purpose of this report is to address the acquisition strategy for the NGNP Intermediate Heat Exchanger (IHX).This component will be operated in flowing, impure helium on the primary and secondary side at temperatures up to 950°C. There are major high temperature design, materials availability, and fabrication issues that need to be addressed. The prospective materials are Alloys 617, 230, 800H and X, with Alloy 617 being the leading candidate for the use at 950°C. The material delivery schedule for these materials does not pose a problem for a 2018 start up as the vendors can quote reasonable delivery times at the moment. The product forms and amount needed must be finalized as soon as possible. An

  15. Application of metal foam heat exchangers for a high-performance liquefied natural gas regasification system

    International Nuclear Information System (INIS)

    Kim, Dae Yeon; Sung, Tae Hong; Kim, Kyung Chun

    2016-01-01

    The intermediate fluid vaporizer has wide applications in the regasification of LNG (liquefied natural gas). The heat exchanger performance is one of the main contributors to the thermodynamic and cost effectiveness of the entire LNG regasification system. Within the paper, the authors discuss a new concept for a compact heat exchanger with a micro-cellular structure medium to minimize volume and mass and to increase thermal efficiency. Numerical calculations have been conducted to design a metal-foam filled plate heat exchanger and a shell-and-tube heat exchanger using published experimental correlations. The geometry of both heat exchangers was optimized using the conditions of thermolators in LNG regasification systems. The heat transfer and pressure drop performance was predicted to compare the heat exchangers. The results show that the metal-foam plate heat exchanger has the best performance at different channel heights and mass flow rates of fluid. In the optimized configurations, the metal-foam plate heat exchanger has a higher heat transfer rate and lower pressure drop than the shell-and-tube heat exchanger as the mass flow rate of natural gas is increased. - Highlights: • A metal foam heat exchanger is proposed for LNG regasification system. • Comparison was made with a shell and tube heat exchanger. • Heat transfer and pressure drop characteristics were estimated. • The geometry of both heat exchangers is optimized for thermolators. • It can be used as a compact and high performance thermolators.

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

    Science.gov (United States)

    Cain, Christina L.

    1989-03-01

    To improve system life, an effort was undertaken to develop all-metal compact heat exchangers to replace existing heat exchangers which contain organic materials. Eliminating organic materials increases system life because outgassing organics can contaminate the helium working fluid and reduce system life. Perforated plate heat exchangers were found to have inherently low axial conduction and are therefore excellent candidates for cryogenic applications where an all-metal design is required. A total of 11 plate cores were tested; 2 were chemically etched, 1 was mechanically punched, and 8 were manufactured using electron beam drilling. Hole size, percent open area, and plate thickness parameters were varied among the plates. Experimental results were compared to analytical projections and found to differ significantly. The single-blow transient test technique was used to determine the heat transfer coefficients and the isothermal pressure drop test was used to determine friction factors, as a function of Reynolds number.

  17. Heat exchange between a bouncing drop and a superhydrophobic substrate.

    Science.gov (United States)

    Shiri, Samira; Bird, James C

    2017-07-03

    The ability to enhance or limit heat transfer between a surface and impacting drops is important in applications ranging from industrial spray cooling to the thermal regulation of animals in cold rain. When these surfaces are micro/nanotextured and hydrophobic, or superhydrophobic, an impacting drop can spread and recoil over trapped air pockets so quickly that it can completely bounce off the surface. It is expected that this short contact time limits heat transfer; however, the amount of heat exchanged and precise role of various parameters, such as the drop size, are unknown. Here, we demonstrate that the amount of heat exchanged between a millimeter-sized water drop and a superhydrophobic surface will be orders of magnitude less when the drop bounces than when it sticks. Through a combination of experiments and theory, we show that the heat transfer process on superhydrophobic surfaces is independent of the trapped gas. Instead, we find that, for a given spreading factor, the small fraction of heat transferred is controlled by two dimensionless groupings of physical parameters: one that relates the thermal properties of the drop and bulk substrate and the other that characterizes the relative thermal, inertial, and capillary dynamics of the drop.

  18. Subscale Water Based Phase Change Material Heat Exchanger Development

    Science.gov (United States)

    Sheth, Rubik; Hansen, Scott

    2016-01-01

    Supplemental heat rejection devices are required in many spacecraft as the radiators are not sized to meet the full heat rejection demand. One means of obtaining additional heat rejection is through the use of phase change material heat exchangers (PCM HX's). PCM HX's utilize phase change to store energy in unfavorable thermal environments (melting) and reject the energy in favorable environments (freezing). Traditionally, wax has been used as a PCM on spacecraft. However, water is an attractive alternative because it is capable of storing about 40% more energy per unit mass due to its higher latent heat of fusion. The significant problem in using water as a PCM is its expansion while freezing, leading to structural integrity concerns when housed in an enclosed heat exchanger volume. Significant investigation and development has taken place over the past five years to understand and overcome the problems associated with water PCM HX's. This paper reports on the final efforts by Johnson Space Center's Thermal Systems Branch to develop a water based PCM HX. The test article developed and reported on is a subscale version of the full-scale water-based PCM HX's constructed by Mezzo Technologies. The subscale unit was designed by applying prior research on freeze front propagation and previous full-scale water PCM HX development. Design modifications to the subscale unit included use of urethane bladder, decreased aspect ratio, perforated protection sheet, and use of additional mid-plates. Testing of the subscale unit was successful and 150 cycles were completed without fail.

  19. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    Science.gov (United States)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2012-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  20. Inquiry of selected topics on heat exchanger design

    International Nuclear Information System (INIS)

    Mueller, A.C.

    1977-01-01

    Three specific topics of heat exchanger design are discussed. First is an examination of the effect of maldistribution on the performance of an exchanger. Three different patterns of maldistribution are investigated and for each type when the overall coefficient is independent of the maldistribution (constant) and when the maldistributed fluid is the controlling resistance and, hence, is a function of the maldistribution. It is the purpose of this investigation to determine how serious the maldistribution problem can be and hopefully, develop guidelines for the designer. Second, the simple laminar flow in tube heat transfer problem was examined with the further complications of appreciable external resistance and for countercurrent flow with appreciable temperature changes in the secondary fluid. This is a complex problem theoretically and it is shown how this would be simplified by means of several simple plots. Based on an old analog solution, the possible error if one used the conventional methods of applying overall coefficients in the design of laminar flow exchangers is discussed. Third, laminar flow heat transfer in tube banks was reviewed. The fundamental problem here is how does one handle the effect of the number of tube rows in baffled exchangers. Another form of correlation is suggested but basically it was found that insufficient experimental data were available to determine the best form of correlation. Further experimental data are needed

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

    Science.gov (United States)

    Kwon, Y H; Kim, D; Li, C G; Lee, J K; Hong, D S; Lee, J G; Lee, S H; Cho, Y H; Kim, S H

    2011-07-01

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

  2. Advanced control for ground source heat pump systems

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Patrick [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gehl, Anthony C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Xiaobing [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    Ground source heat pumps (GSHP), also known as geothermal heat pumps (GHP), are proven advanced HVAC systems that utilize clean and renewable geothermal energy, as well as the massive thermal storage capacity of the ground, to provide space conditioning and water heating for both residential and commercial buildings. GSHPs have higher energy efficiencies than conventional HVAC systems. It is estimated, if GSHPs achieve a 10% market share in the US, in each year, 0.6 Quad Btu primary energy consumption can be saved and 36 million tons carbon emissions can be avoided (Liu et al. 2017). However, the current market share of GSHPs is less than 1%. The foremost barrier preventing wider adoption of GSHPs is their high installation costs. To enable wider adoption of GSHPs, the costeffectiveness of GSHP applications must be improved.

  3. Applied Horizontal and Vertical Geothermal Heat Exchanger with Heat Pump System to Provide Air Conditioning for an Academic Facility in Mexico

    Directory of Open Access Journals (Sweden)

    Daniel Alcantar Martínez

    2017-07-01

    Full Text Available At present in Mexico, the renewable energy has become more important due to the great dependence of the country for fossil fuels. Within the several applications of renewable energy, there are the geothermal applications for the air conditioning of spaces. This technology employs heat pumps that interexchange heat with the ground. This technology is relatively young in Mexico, leaving a large field for study and application throughout the country. In this way, to calculate the correct sizing of geothermal heat exchangers, it is necessary to calculate the thermal loads of the complex in which this technology of geothermal heat pumps using vertical heat exchangers type U will be installed, to perform the calculation of thermal loads Autodesk Revit® software was used, with which was possible to make a virtual model in detail of the botanical center that is located in Morelia, Michoacán, Mexico and belongs to the Universidad Michoacana de San Nicolás de Hidalgo (UMNSH. This study shows the results of the analysis of the installations and determination of the thermal loads of the complex due to this type of infrastructure. By obtaining the values of the thermal loads, the dimensioning of the heat exchanger was archived, which will have to be installed to cover the thermal requirement of this system and his installation, in addition to the selection of the heat pump. This complex of 2 levels, where, on the first floor there are cubicles and laboratories and on the second floor, several common areas. The design was developed in detail in Autodesk Revit 2015. After obtaining the thermal loads, the GLHEPro software was used for dimensioning the Vertical heat exchangers with the number and depth of the exchangers was obtained. the GLD 2014 software was used for dimensioning the Horizontal heat exchangers with the number and depth of the exchangers was obtained.

  4. Multi-channel heat exchanger-reactor using arborescent distributors: A characterization study of fluid distribution, heat exchange performance and exothermic reaction

    International Nuclear Information System (INIS)

    Guo, Xiaofeng; Fan, Yilin; Luo, Lingai

    2014-01-01

    A multi-functional heat exchanger-reactor comprising arborescent (tree-like) distributors and collector, 16 mini-channels in parallel and T-mixers is introduced in this paper. Flow distribution property, pressure drop and heat exchange performance of proposed heat exchanger-reactor are tested and discussed. Firstly, flow distribution uniformity is characterized by CFD simulation and then qualitatively confirmed by visualization experiment. Results show that for total flowrates ranging from 5 mL s −1 to 20 mL s −1 , good distribution uniformity is obtained, with maximum flowrate deviation less than 10%. Then, experiments of heat exchange between hot and cold water are carried out. High values of overall heat transfer coefficient ranging from 2000 to 5000 W m −2  °C −1 are obtained under our working conditions. The volumetric heat exchange capability (UA/V) is found to be around 200 kW m −3  °C −1 , showing a high heat exchange capability with compact design. The roles of end-effect and non-established flow are discussed and are supposed to be responsible for efficient heat transfer. Finally a typical fast exothermic reaction, neutralization between acid and basic solutions, is carried out to test the thermal control capability of the studied heat exchanger-reactor. Results indicate that isothermal condition could be realized by circulating appropriate flowrate of coolant through the heat exchanger. The design of heat exchanger-reactor with arborescent distributor and collector makes possible the application of multi-channel systems. This paper introduces systematically the successful integration of heat exchanger-reactor and its performance evaluation. - Highlights: • A design of mini scale, multichannel heat exchanger-reactor is proposed. • Uniform distribution for parallel channels is obtained with arborescent structure. • High global heat exchange coefficient is found experimentally. • Thermal control capability is verified with an

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

    DEFF Research Database (Denmark)

    Knudsen, Søren; Morrison, GL; Behnia, M

    2005-01-01

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

  6. Improvement to heat exchanger elements, to the corresponding exchangers and their methods of production

    International Nuclear Information System (INIS)

    1974-01-01

    A description is given of a flat rectangular element for a heat exchanger made by closely assembling two regular ribbed sheets against each other. In the element thus obtained the ribbing forms two parallel passages at two opposite sides of the rectangle and running along these two sides, and a series of identical channels parallel to the two other sides of the rectangle. The two ends of these channels respectively give on to the two passages. Each light-alloy sheet is very thin, under .5mm. The total thickness of the element is less than 5 mm. The total area of each rectangular side of the element is around one square metre, its length being greater than 1 metre. The heat exchanger is built up of a bank of these elements juxtaposed side by side with requisite interpositions for the circulation of the external exchange [fr

  7. 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.

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

    International Nuclear Information System (INIS)

    AbuRomia, M.M.; Chu, A.W.; Cho, S.M.

    1976-01-01

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

  9. Radiative Heating in MSL Entry: Comparison of Flight Heating Discrepancy to Ground Test and Predictive Models

    Science.gov (United States)

    Cruden, Brett A.; Brandis, Aaron M.; White, Todd R.; Mahzari, Milad; Bose, Deepak

    2014-01-01

    During the recent entry of the Mars Science Laboratory (MSL), the heat shield was equipped with thermocouple stacks to measure in-depth heating of the thermal protection system (TPS). When only convective heating was considered, the derived heat flux from gauges in the stagnation region was found to be underpredicted by as much as 17 W/sq cm, which is significant compared to the peak heating of 32 W/sq cm. In order to quantify the contribution of radiative heating phenomena to the discrepancy, ground tests and predictive simulations that replicated the MSL entry trajectory were performed. An analysis is carried through to assess the quality of the radiation model and the impact to stagnation line heating. The impact is shown to be significant, but does not fully explain the heating discrepancy.

  10. Stead-state characteristic study of heat exchanger in water-cooled passive heat removal system for molten salt reactor

    International Nuclear Information System (INIS)

    Fa Dan; Yan Changqi; Sun Licheng; Sun Lu; Zhao Hangbin

    2013-01-01

    Background: In the water-cooled passive heat removal system for molten salt reactor, the decay heat generated in molten salt can finally be transferred to the heat exchanger placed in water tank by natural circulation. Purpose: Based on the principles of high safety and simplification, there is a need to transfer the decay heat passively without using external power. Methods: The heat exchanger consists of a set of bundles submerged into the water tank with a tube header at each side. Based on the flow process, corresponding numerical model was constructed in the code of C++. Then the total heat exchange coefficient is got and the heat transfer area is calculated. Continually iterate the heat transfer area until the iteration stopping criterion is met, after that the dimensions of water tank are figured out. Results: While the decay power is 100 kW in the initial of the operation, the power of heat exchanger reaches the maximum value of 130 kW due to the low-temperature water in water tank. Then it drops quickly for the decrease of heat exchanger pressure and the rise of water temperature in water tank. When the heat exchanger pressure begins to rise, the heat exchanger power drops slower than before. The heat transfer ability begins to decrease quickly as the temperature difference between inside and outside of heat exchanger tubes lowers. Then it drops gradually as a result of the slowly changed pressure. During early operation, the heat exchanger pressure decreases because the steam generation rate is lower than the steam condensation rate. Then the condition varies as the heat exchanger power declines gradually. When boiling happens inside the water tank, the steam condensation rate raises due to the increasing heat transfer ability which makes the pressure of heat exchanger drops quickly. Afterwards, the heat exchanger pressure changes very slowly as the steam generation rate is approximate to the steam condensation rate. The mass of water in water tank

  11. Corrosion of materials for heat exchangers and the countermeasures

    International Nuclear Information System (INIS)

    Kawamoto, Teruaki

    1978-01-01

    When the materials for heat exchangers are selected, the heat transfer performance, mechanical strength, workability, cost, corrosion resistance and so on are taken in consideration. Most of the failure of heat exchangers is due to corrosion, and the corrosion failure on cooling water side occurs frequently, to which attention is not paid much usually. The rate of occurrence of corrosion failure is overwhelmingly high in heating tubes, and the failure owing to cooling water exceeds that owing to process fluid. The material of heating tubes is mostly aluminum brass, and local failure such as pitting corrosion or stress corrosion cracking holds a majority. The cause of corrosion failure due to cooling water is mostly the poor water quality. The mechanism of corrosion of metals can be explained by the electrochemical reaction between the metals and solutions. As for the factors affecting corrosion, dissolved oxygen, pH, Cl - ions, temperature, flow velocity, and foreign matters are enumerated. Copper alloys are sensitive to the effect of polluted sea water. Erosion corrosion is caused by eddies and bubbles owing to high flow velocity, and impingement attack is caused by scratching foreign matters. The quality of fresh water affects corrosion more than sea water in case of copper alloys. The preliminary examination of water quality is essential. (Kako, I.)

  12. Major heat exchanger performance in Ontario Hydro-operated CANDU nuclear generating stations

    International Nuclear Information System (INIS)

    Dueck, D.G.

    1980-01-01

    The performance of heat exchangers is described in terms of their impact on the unit in the form of forced outages and deratings as well as incapability due to scheduled outages. Some major problems with heat exchangers are highlighted. (auth)

  13. Optimizing the Heat Exchanger Network of a Steam Reforming System

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh; Korsgaard, Anders Risum; Kær, Søren Knudsen

    2004-01-01

    Proton Exchange Membrane (PEM) based combined heat and power production systems are highly integrated energy systems. They may include a hydrogen production system and fuel cell stacks along with post combustion units optionally coupled with gas turbines. The considered system is based on a natural...... gas steam reformer along with gas purification reactors to generate clean hydrogen suited for a PEM stack. The temperatures in the various reactors in the fuel processing system vary from around 1000°C to the stack temperature at 80°C. Furthermore, external heating must be supplied to the endothermic...

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

    Science.gov (United States)

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

    2011-01-01

    Several heat exchanger (HX) test panels were designed, fabricated and tested at the NASA Glenn Research Center to explore the fabrication and performance of several designs for composite heat exchangers. The development of these light weight, high efficiency air-liquid test panels was attempted using polymer composites and carbon foam materials. The fundamental goal of this effort was to demonstrate the feasibility of the composite HX for various space exploration and thermal management applications including Orion CEV and Altair. The specific objectives of this work were to select optimum materials, designs, and to optimize fabrication procedures. After fabrication, the individual design concept prototypes were tested to determine their thermal performance and to guide the future development of full-size engineering development units (EDU). The overall test results suggested that the panel bonded with pre-cured composite laminates to KFOAM Grade L1 scored above the other designs in terms of ease of manufacture and performance.

  15. 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

  16. Tritium permeation losses in HYLIFE-II heat exchanger tubes

    International Nuclear Information System (INIS)

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

    1990-01-01

    Tritium permeation through the intermediate heat exchanger of the HYLIFE-II inertial fusion design concept is evaluated for routine operating conditions. The permeation process is modelled using the Lewis analogy combined with surface recombination. It is demonstrated that at very low driving potentials, permeation becomes proportional to the first power of the driving potential. The model predicts that under anticipated conditions the primary cooling loop will pass about 6% of the tritium entering it to the intermediate coolant. Possible approached to reducing tritium permeation are explored. Permeation is limited by turbulent diffusion transport through the molten salt. Hence, surface barriers with impendance factors typical of present technology can do very little to reduce permeation. Low Flibe viscosity is desirable. An efficient tritium removal system operating on the Flibe before it gets to the intermediate heat exchanger is required. Needs for further research are highlighted. 9 refs., 2 figs., 1 tab

  17. Heat exchange and heat exchangers. Systematics of construction - Series production - Tube oscillations - Economical optimization corresponding to manufacturing requirements due to exergy losses. Waermeaustausch und Waermeaustauscher. Konstruktionssystematik - Serienproduktion - Rohrschwingungen - Fertigungsgerechte wirtschaftliche Optimierung aufgrund von Exergieverlusten

    Energy Technology Data Exchange (ETDEWEB)

    Gregorig, R. (Technische Univ. Berlin (F.R. Germany). Fachbereich Verfahrenstechnik; Minas Gerais Univ., Belo Horizonte (Brazil). Escola de Engenharia)

    1973-01-01

    The author first gives a detailed description of the fundamental theories of heat exchange with special regard to the conditions for heat exchangers, followed by a systematic treatment of the constructional details, materials, and operation of heat exchangers. (DE)

  18. 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.

  19. Heat transfer in intermediate heat exchanger under low flow rate conditions

    International Nuclear Information System (INIS)

    Mochizuki, H.

    2008-01-01

    The present paper describes the heat transfer in intermediate heat exchangers (IHXs) of liquid metal cooled fast reactors when flow rate is low such as a natural circulation condition. Although empirical correlations of heat transfer coefficients for IHX were derived using test data at the fast reactor 'Monju' and 'Joyo' and also at the 50 MW steam generator facility, the heat transfer coefficient was very low compared to the well known correlation for liquid metals proposed by Seban-Shimazaki. The heat conduction in IHX was discussed as a possible cause of the low Nusselt number. As a result, the heat conduction is not significant under the natural circulation condition, and the heat conduction term in the energy equation can be neglected in the one-dimensional plant dynamics calculation. (authors)

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

    DEFF Research Database (Denmark)

    Friis, Alan; Szabo, Peter; Karlson, Torben

    2002-01-01

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

  1. STEADY-STATE HEAT REJECTION RATES FOR A COAXIAL BOREHOLE HEAT EXCHANGER DURING PASSIVE AND ACTIVE COOLING DETERMINED WITH THE NOVEL STEP THERMAL RESPONSE TEST METHOD

    Directory of Open Access Journals (Sweden)

    Marija Macenić

    2018-01-01

    Full Text Available At three locations in Zagreb, classical and extended thermal response test (TRT was conducted on installed coaxial heat exchangers. With classic TR test, thermogeological properties of the ground and thermal resistance of the borehole were determined at each location. It is seen that thermal conductivity of the ground varies, due to difference in geological profile of the sites. In addition, experimental research of steady-state thermal response step test (SSTRST was carried out to determine heat rejection rates for passive and active cooling in steady state regime. Results showed that heat rejection rate is only between 8-11 W/m, which indicates that coaxial system is not suitable for passive cooling demands. Furthermore, the heat pump in passive cooling mode uses additional plate heat exchanger where there is additional temperature drop of working fluid by approximately 1,5 °C. Therefore, steady-state rejection rate for passive cooling is even lower for a real case project. Coaxial heat exchanger should be always designed for an active cooling regime with an operation of a heat pump compressor in a classical vapour compression refrigeration cycle.

  2. Gas Turbine Engine with Air/Fuel Heat Exchanger

    Science.gov (United States)

    Karam, Michael Abraham (Inventor); Donovan, Eric Sean (Inventor); Krautheim, Michael Stephen (Inventor); Vetters, Daniel Kent (Inventor); Chouinard, Donald G. (Inventor)

    2017-01-01

    One embodiment of the present invention is a unique aircraft propulsion gas turbine engine. Another embodiment is a unique gas turbine engine. Another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines with heat exchange systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

  3. Thermal response testing of precast pile heat exchangers

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Poulsen, Søren Erbs; Jensen, Rasmus Lund

    The report is organized as follows: first, the concept of TRT is explained. Second, the test sites are described. Third, the field work is presented and a summary of the future work regarding the methodology to treat the data from the tests is provided. Finally, further documentation of the field...... of the fieldwork, the pile heat exchangers and the TRT equipment is extended in diverse appendices....

  4. Damping in heat exchanger tube bundles. A review

    International Nuclear Information System (INIS)

    Iqbal, Qamar; Khushnood, Shahab; Ghalban, Ali Roheim El; Sheikh, Nadeem Ahmed; Malik, Muhammad Afzaal; Arastu, Asif

    2007-01-01

    Damping is a major concern in the design and operation of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchangers and steam generators which are used in nuclear, process and power generation industries. System damping has a strong influence on the amplitude of vibration. Damping depends upon the mechanical properties of the tube material, geometry of intermediate supports and the physical properties of shell-side fluid. Type of tube motion, number of supports, tube frequency, vibration amplitude, tube mass or diameter, side loads, support thickness, higher modes, shell-side temperature etc., affect damping in tube bundles. The importance of damping is further highlighted due to current trend of larger exchangers with increased shell-side velocities in modern units. Various damping mechanisms have been identified (Friction damping, Viscous damping, Squeeze film damping, Support damping. Two-Phase damping, and very recent-Thermal damping), which affect the performance of process exchangers and steam generators with respect to flow induced vibration design, including standard design guidelines. Damping in two-phase flow is very complex and highly void fraction, and flow-regime dependent. The current paper focuses on the various known damping mechanisms subjected to both single and two-phase cross-flow in process heat exchangers and steam generators and formulates the design guidelines for safer design. (author)

  5. Utilization of Porous Media for Condensing Heat Exchangers

    Science.gov (United States)

    Tuan, George C.

    2006-01-01

    The use of porous media as a mean of separating liquid condensate from the air stream in condensing heat exchangers has been explored in the past inside small plant growth chambers and in the Apollo Command Module. Both applications used a cooled porous media made of sintered stainless steel to cool and separate condensation from the air stream. However, the main issues with the utilization of porous media in the past have been the deterioration of the porous media over long duration, such as clogging and changes in surface wetting characteristics. In addition, for long duration usage, biofilm growth from microorganisms on the porous medial would also be an issue. In developing Porous Media Condensing Heat Exchangers (PMCHX) for future space applications, different porous materials and microbial growth control methods will need to be explored. This paper explores the work performed at JSC and GRC to evaluate different porous materials and microbial control methods to support the development of a Porous Media Condensing Heat Exchanger. It outlines the basic principles for designing a PMCHX and issues that were encountered and ways to resolve those issues. The PMCHX has potential of mass, volume, and power savings over current CHX and water separator technology and would be beneficial for long duration space missions.

  6. Development of a heat exchanger root-cause analysis methodology

    International Nuclear Information System (INIS)

    Jarrel, D.B.

    1989-01-01

    The objective of this work is to determine a generic methodology for approaching the accurate identification of the root cause of component failure. Root-cause determinations are an everyday challenge to plant personnel, but they are handled with widely differing degrees of success due to the approaches, levels of diagnostic expertise, and documentation. The criterion for success is simple: If the root cause of the failure has truly been determined and corrected, the same causal failure relationship will not be demonstrated again in the future. The approach to root-cause analysis (RCA) element definition was to first selectively choose and constrain a functionally significant component (in this case a component cooling water to service water heat exchanger) that has demonstrated prevalent failures. Then a root cause of failure analysis was performed by a systems engineer on a large number of actual failure scenarios. The analytical process used by the engineer was documented and evaluated to abstract the logic model used to arrive at the root cause. For the case of the heat exchanger, the actual root-cause diagnostic approach is described. A generic methodology for the solution of the root cause of component failure is demonstrable for this general heat exchanger sample

  7. Heat exchanger bypass system for an absorption refrigeration system

    Science.gov (United States)

    Reimann, Robert C.

    1984-01-01

    A heat exchanger bypass system for an absorption refrigeration system is disclosed. The bypass system operates to pass strong solution from the generator around the heat exchanger to the absorber of the absorption refrigeration system when strong solution builds up in the generator above a selected level indicative of solidification of strong solution in the heat exchanger or other such blockage. The bypass system includes a bypass line with a gooseneck located in the generator for controlling flow of strong solution into the bypass line and for preventing refrigerant vapor in the generator from entering the bypass line during normal operation of the refrigeration system. Also, the bypass line includes a trap section filled with liquid for providing a barrier to maintain the normal pressure difference between the generator and the absorber even when the gooseneck of the bypass line is exposed to refrigerant vapor in the generator. Strong solution, which may accumulate in the trap section of the bypass line, is diluted, to prevent solidification, by supplying weak solution to the trap section from a purge system for the absorption refrigeration system.

  8. Risk Based Inspection of Gas-Cooling Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Dwi Priyanta

    2017-09-01

    Full Text Available On October 2013, Pertamina Hulu Energi Offshore North West Java (PHE – ONWJ platform personnel found 93 leaking tubes locations in the finfan coolers/ gas-cooling heat exchanger. After analysis had been performed, the crack in the tube strongly indicate that stress corrosion cracking was occurred by chloride. Chloride stress corrosion cracking (CLSCC is the cracking occurred by the combined influence of tensile stress and a corrosive environment. CLSCC is the one of the most common reasons why austenitic stainless steel pipework or tube and vessels deteriorate in the chemical processing, petrochemical industries and maritime industries. In this thesis purpose to determine the appropriate inspection planning for two main items (tubes and header box in the gas-cooling heat exchanger using risk based inspection (RBI method. The result, inspection of the tubes must be performed on July 6, 2024 and for the header box inspection must be performed on July 6, 2025. In the end, RBI method can be applicated to gas-cooling heat exchanger. Because, risk on the tubes can be reduced from 4.537 m2/year to 0.453 m2/year. And inspection planning for header box can be reduced from 4.528 m2/year to 0.563 m2/year.

  9. Ground water applications of the heat capacity mapping mission

    Science.gov (United States)

    Heilman, J. L.; Moore, D. G.

    1981-01-01

    The paper discusses the ground water portion of a hydrologic investigation of eastern South Dakota using data from the Heat Capacity Mapping Mission (HCMM) satellite. The satellite carries a two-channel radiometer (0.5-1.1 and 10.5-12.5 microns) in a sun synchronous orbit and collects data at approximately 0230 and 1330 local standard time with repeat coverage of 5 to 16 days depending on latitude. It is shown that HCMM data acquired at appropriate periods of the diurnal and annual temperature cycle can provide useful information on shallow ground water.

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

    Science.gov (United States)

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

    1977-01-01

    Sizing procedures are presented for latent heat thermal energy storage systems that can be used for electric utility off-peak energy storage, solar power plants and other preliminary design applications.

  12. Mean temperature profile at the entrance of a thermoacoustic stacked screen heat exchanger

    NARCIS (Netherlands)

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

    2015-01-01

    In thermoacoustic devises, the thermoacoustic e ect occurs in the regenerator placed between two heat exchangers. The entrance e ects of such heat exchanger are investigated with two computational uid dynamics (CFD) test cases. The rst CFD test case models an ideal heat exchanger adjacent to an open

  13. Performance and Economic Modeling of Horizontally Drilled Ground-Source Heat Pumps in Select California Climates

    Science.gov (United States)

    Wiryadinata, Steven

    Service life modeling was performed to gage the viability of unitary 3.5 kWt, ground-source terminal heat pumps (GTHP) employing horizontal directionally drilled geothermal heat exchangers (GHX) over air-source terminal heat pumps (PTHP) in hotels and motels and residential apartment building sectors in California's coastal and inland climates. Results suggest the GTHP can reduce hourly peak demand for the utility by 7%-25% compared to PTHP, depending on the climate and building type. The annual energy savings, which range from -1% to 5%, are highly dependent on the GTHP pump energy use relative to the energy savings attributed to the difference in ground and air temperatures (DeltaT). In mild climates with small ?T, the pump energy use may overcome any advantage to utilizing a GHX. The majority of total levelized cost savings - ranging from 0.18/ft2 to 0.3/ft 2 - are due to reduced maintenance and lifetime capital cost normally associated with geothermal heat pump systems. Without these reductions (not validated for the GTHP system studied), the GTHP technology does not appear to offer significant advantages over PTHP in the climate zones studied here. The GTHP levelized cost was most sensitive to variations in installed cost and in some cases, energy use (influenced by climate zone choice), which together highlights the importance of climate selection for installation, and the need for larger market penetration of ground-source systems in order to bring down installed costs as the technology matures.

  14. Energetic Efficiency Evaluation by Using GroundWater Heat Pumps

    Directory of Open Access Journals (Sweden)

    Tokar Adriana

    2012-09-01

    Full Text Available Romania has significant energy potential from renewable sources, but the potential used is much lower due to technical and functional disadvantages, to economic efficiency, the cost elements and environmental limitations. However, efforts are being made to integrate renewable energy in the national energy system. To promote and encourage private investments for renewable energy utilization, programs have been created in order to access funds needed to implement these technologies. Assessment of such investments was carried out from technical and economical point of view, by analyzing a heat pump using as heat source the solar energy from the ground.

  15. 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

  16. Analytical and Numerical Design Analysis of Concentric Tube Heat Exchangers – A Review

    Science.gov (United States)

    Silaipillayarputhur, Karthik; Mughanam, Tawfiq Al; Mojil, Abdulaziz Al; Dhmoush, Mohammed Al

    2017-12-01

    This paper considers an analytical and a numerical approach in the design of a concentric tube heat exchanger. Sensible heat transfer is considered in the analysis and the heat exchanger is developed for actual operating conditions in a chemical plant. The heat exchanger is a concentric tube heat exchanger where hot oil exchanges heat with hot water. Hot oil is in the inner pipe and the heating medium, hot water, is in the outer pipe (annular side) of the heat exchanger. An analytical model employing effectiveness-number of transfer units (ε-NTU) approach and log mean temperature difference (LMTD) approach were employed in the design of the concentric tube heat exchanger. In the design process, performance charts were developed for concentric tube heat exchanger. Performance charts describe the performance of the heat exchanger in terms of crucial dimensionless parameters. Performance charts help to select the right number of transfer units (NTU) for the given heat exchanger. Both parallel and counter flow configurations were considered for the design analysis. Likewise, a numerical model was also considered in the design of the heat exchanger. The results from the analysis are presented and compared. From the results it can be seen that both numerical and analytical approaches produce the exact same results. The designer certainly has the flexibility to choose an appropriate design methodology based on the available inputs and requirements.

  17. CFD ANALYSIS OF EXHAUST HEAT EXCHANGER FOR THERMO-ELECTRIC POWER GENERATION

    OpenAIRE

    Ravi Bhatt*1, Surendra Bharti2 & Abhishek Shahi3

    2017-01-01

    In thermo-electric power generation an exhaust heat exchanger is used for recovering exhaust heat and a thermo-electric module is used for converting heat into electricity.This research work focus on optimization of the design of exhaust heat exchanger by removing the internal fins and changing the cross-sectional area of heat exchanger to minimize the problem of pressure drop.The designs of exhaust heat exchangers used in the previous research works recovers maximum heat from an engine exhau...

  18. Heat transfer to helium. Application to the design of heat exchangers

    International Nuclear Information System (INIS)

    Johannes, C.

    1974-01-01

    The discovery of superconductivity has lead to a new technology at very low temperatures. This technology utilises liquid helium to maintain superconducting devices below their transition temperatures. These devices contain the heat exchangers for the circulation of the helium. The helium could be in two-phase flow or in single phase but near its critical point. This paper describes a study of the heat transfer and pressure drop characteristics of helium in two-phase flow and in the supercritical state. The results are compared with existing correlations. For two-phase pressure drop two methods were used: one based on slip between phases and the other based on a homogeneous model. The heat transfer data are compared with a number of existing correlations. The author proposes the best methods for calculating helium heat exchangers [fr

  19. 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.

  20. Ground-source heat pump case studies and utility programs

    Energy Technology Data Exchange (ETDEWEB)

    Lienau, P.J.; Boyd, T.L.; Rogers, R.L.

    1995-04-01

    Ground-source heat pump systems are one of the promising new energy technologies that has shown rapid increase in usage over the past ten years in the United States. These systems offer substantial benefits to consumers and utilities in energy (kWh) and demand (kW) savings. The purpose of this study was to determine what existing monitored data was available mainly from electric utilities on heat pump performance, energy savings and demand reduction for residential, school and commercial building applications. In order to verify the performance, information was collected for 253 case studies from mainly utilities throughout the United States. The case studies were compiled into a database. The database was organized into general information, system information, ground system information, system performance, and additional information. Information was developed on the status of demand-side management of ground-source heat pump programs for about 60 electric utility and rural electric cooperatives on marketing, incentive programs, barriers to market penetration, number units installed in service area, and benefits.

  1. Heat transfer to immiscible liquid mixtures in a spiral plate heat exchanger

    Directory of Open Access Journals (Sweden)

    S. Sathiyan

    2013-06-01

    Full Text Available This work presents new predictive correlations for heat transfer to immiscible liquid-liquid mixtures in a spiral plate heat exchanger. Liquid-liquid heat transfer studies were carried out in spiral plate heat exchangers for the water-octane, water-kerosene, and water-dodecane systems. For each composition of the mixture, the mass flow rate of the cold fluid was varied, keeping that of the hot fluid and the fluid inlet temperatures constant. Two-phase cold flow rates were in the laminar range, while the hot fluid flow was turbulent. Calculations of the LMTD (log mean temperature difference correction factor showed that the flow was countercurrent. Heat transfer coefficients of the two-phase liquids were found to be strongly dependent on the composition of the liquid mixture and exhibited abrupt transitions as a function of the compositions. Given the absence of predictive correlations in the literature that sufficiently capture this compositiondependence, new empirical correlations were developed using part of the experimental data, with the composition of the cold fluid as an explicit variable. Statistical analysis of the regression yielded satisfactory results. The correlations were tested against the rest of the experimental data and were found to predict heat transfer coefficients within ± 15%. These preliminary studies should be useful in designing compact exchangers for handling two-phase water-organics mixtures.

  2. A novel TRNSYS type for short-term borehole heat exchanger simulation: B2G model

    International Nuclear Information System (INIS)

    De Rosa, Mattia; Ruiz-Calvo, Félix; Corberán, José M.; Montagud, Carla; Tagliafico, Luca A.

    2015-01-01

    Highlights: • A novel dynamic borehole heat exchanger model is presented. • Theoretical approach for model parameters calculation is described. • The short-term model is validated against experimental data of a real GSHP. • Strong dynamic conditions due to the ON–OFF regulation are investigated. - Abstract: Models of ground source heat pump (GSHP) systems are used as an aid for the correct design and optimization of the system. For this purpose, it is necessary to develop models which correctly reproduce the dynamic thermal behavior of each component in a short-term basis. Since the borehole heat exchanger (BHE) is one of the main components, special attention should be paid to ensuring a good accuracy on the prediction of the short-term response of the boreholes. The BHE models found in literature which are suitable for short-term simulations usually present high computational costs. In this work, a novel TRNSYS type implementing a borehole-to-ground (B2G) model, developed for modeling the short-term dynamic performance of a BHE with low computational cost, is presented. The model has been validated against experimental data from a GSHP system located at Universitat Politècnica de València, Spain. Validation results show the ability of the model to reproduce the short-term behavior of the borehole, both for a step-test and under normal operating conditions

  3. Forced Convective Heat Transfer of Aqueous Al₂O₃ Nanofluid Through Shell and Tube Heat Exchanger.

    Science.gov (United States)

    Haque, A K M Mahmudul; Kim, Sedong; Kim, Junhyo; Noh, Jungpil; Huh, Sunchul; Choi, Byeongkeun; Chung, Hanshik; Jeong, Hyomin

    2018-03-01

    This study presents the forced convective heat transfer of a nanofluid consisting of distilled water and different weight concentrations (1 wt% and 2 wt%) of Al2O3 nanoparticles flowing in a vertical shell and tube heat exchanger under counter flow and laminar flow regime with certain constant heat flaxes (at 20 °C, 30 °C, 40 °C and 50 °C). The Al2O3 nanoparticles of about 50 nm diameter are used in the present study. Stability of aqueous Al2O3 nanofluids, TEM, thermal conductivity, temperature differences, heat transfer rate, T-Q diagrams, LMTD and convective heat transfer coefficient are investigated experimentally. Experimental results emphasize the substantial enhancement of heat transfer due to the Al2O3 nanoparticles presence in the nanofluid. Heat transfer rate for distilled water and aqueous nanofluids are calculated after getting an efficient setup which shows 19.25% and 35.82% enhancement of heat transfer rate of 1 wt% and 2 wt% aqueous Al2O3 nanofluids as compared to that of distilled water. Finally, the analysis shows that though there are 27.33% and 59.08% enhancement of 1 wt% Al2O3 and 2 wt% Al2O3 respectively as compared to that of distilled water at 30 °C, convective heat transfer coefficient decreases with increasing heat flux of heated fluid in this experimental setup.

  4. Weight-size Optimization of Aerospace Propulsion System Heat Exchangers

    Directory of Open Access Journals (Sweden)

    A. D. Kliukvin

    2015-01-01

    Full Text Available The paper offers an algorithm for optimizing weight-size parameters of heat exchangers (HE, which allows to take into account not only the size and weight of the matrix, but also the weight and size of the HE tubes and shell.The feature of the proposed algorithm is that a simplified HE model (matrix, shell, and tubes in assembly rather than HE matrix is considered during the optimization calculations. Thus, there are additional parameters to be specified such as wall thickness of tubes and shell, form and arrangement of tubes, coolant flow circuit. Simultaneously with the thermal-hydraulic calculation and estimate of HE weight-size parameters, as a whole, tube opening angles are optimized and a problem of splitter baffle to be in them is solved.In the context of simple calculation of air-to-air recuperative heat exchanger with a cross (one-way circuit coolant flow and plate-fin heat exchange surfaces with short plate fin (PlR1 - PlR12 are compared different methods for the HE weight-size optimization.It is shown that the techniques and algorithms using natural (size, area of heat transfer, mass characteristics or derivatives (cubic coefficient of the HE matrix, as the optimization criteria of variants calculation, provide only a very rough estimate of the HE weight-size characteristics, as a whole. Their use may result in non-optimal choice (in mass and size of the HE model that when using in aviation and space technology leads to an additionally increasing mass of the aircraft.Using the proposed technique allows more accurate (as compared to the methods based on the estimation of the matrix parameters assessment of weight-size characteristics of designed HE, as an explicit calculation involves parameters of tubes and shell with their share of the HE mass being more than half.

  5. 40 CFR 63.11499 - What are the standards and compliance requirements for heat exchange systems?

    Science.gov (United States)

    2010-07-01

    ... requirements for heat exchange systems? 63.11499 Section 63.11499 Protection of Environment ENVIRONMENTAL... and compliance requirements for heat exchange systems? (a) If the cooling water flow rate in your heat... part 211, you may use the physical integrity of the reactor as the surrogate indicator of heat...

  6. Heat pump systems with direct expansion ground coils

    Science.gov (United States)

    Svec, O. J.; Baxter, V. D.

    This paper is a summary of an International research project organized within the framework of the International Energy Agency (IEA), Implementing Agreement on Heat Pumps. This cooperative project, based on a task sharing principle, was proposed by the Canadian team and joined by the national teams of the United States of America, Japan and Austria. The Institute for Research in Construction (IRC) of the National Research Council of Canada (NRCC), has been acting as the Operating Agent for this project, known as Annex XV. The need for this research work is based on the recognition of the state-of-the-art of Ground Source Heat Pump (GSHP) technology, which can simply be described by the following two statements: (1) GSHP technology is the most successful among all renewable technologies in North American and northern European countries; and (2) installation cost of GSHP systems is currently too high for a meaningful worldwide penetration into the heating/cooling market.

  7. Specialists' meeting on heat exchanging components of gas-cooled reactors

    International Nuclear Information System (INIS)

    1984-01-01

    The objective of the Meeting sponsored by IAEA was to provide a forum for the exchange and discussion of technical information related to heat exchanging and heat conducting components for gas-cooled reactors. The technical part of the meeting covered eight subjects: Heat exchanging components for process heat applications, design and requirements, and research and development programs; Status of the design and construction of intermediate He/He exchangers; Design, construction and performance of steam generators; Metallic materials and design codes; Design and construction of valves and hot gas ducts; Description of component test facilities and test results; Manufacturing of heat exchanging components

  8. A dynamic model for helium core heat exchangers

    International Nuclear Information System (INIS)

    Schiesser, W.E.; Shih, H.J.; Hartozog, D.G.; Herron, D.M.; Nahmias, D.; Stuber, W.G.; Hindmarsh, A.C.

    1990-04-01

    To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core heat exchangers consisting of three partial differential equations (PDES) for each fluid stream (the continuity, energy and momentum balances for the He), and one PDE for each parting sheet (the energy balance for the parting sheet metal); the PDEs have time and axial position along the exchanger as independent variables. The computer code can accommodate any number of fluid streams and parting sheets in an adiabatic group. Features of the code include: rigorous or approximate thermodynamic properties for He, upwind and downwind approximation of the PDE spatial derivatives, and sparse matrix time integration. The outputs from the code include the time-dependent axial profiles of the fluid He mass flux, density, pressure, temperature, internal energy and enthalpy. The code is written in transportable Fortran 77, and can therefore be executed on essentially any computer

  9. 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

  10. 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...

  11. High-heat-flux testing of helium-cooled heat exchangers for fusion applications

    International Nuclear Information System (INIS)

    Youchison, D.L.; Izenson, M.G.; Baxi, C.B.; Rosenfeld, J.H.

    1996-01-01

    High-heat-flux experiments on three types of helium-cooled divertor mock-ups were performed on the 30-kW electron beam test system and its associated helium flow loop at Sandia National Laboratories. A dispersion-strengthened copper alloy (DSCu) was used in the manufacture of all the mock-ups. The first heat exchanger provides for enhanced heat transfer at relatively low flow rates and much reduced pumping requirements. The Creare sample was tested to a maximum absorbed heat flux of 5.8 MW/m 2 . The second used low pressure drops and high mass flow rates to achieve good heat removal. The GA specimen was tested to a maximum absorbed heat flux of 9 MW/m 2 while maintaining a surface temperature below 400 degree C. A second experiment resulted in a maximum absorbed heat flux of 34 MW/m 2 and surface temperatures near 533 degree C. The third specimen was a DSCu, axial flow, helium-cooled divertor mock-up filled with a porous metal wick which effectively increases the available heat transfer area. Low mass flow and high pressure drop operation at 4.0 MPa were characteristic of this divertor module. It survived a maximum absorbed heat flux of 16 MW/m 2 and reached a surface temperature of 740 degree C. Thermacore also manufactured a follow-on, dual channel porous metal-type heat exchanger, which survived a maximum absorbed heat flux of 14 MW/m 2 and reached a maximum surface temperature of 690 degree C. 11refs., 20 figs., 3 tabs

  12. Design of heat exchanger for Ericsson-Brayton piston engine.

    Science.gov (United States)

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

    2014-01-01

    Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy--energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

  13. Design of Heat Exchanger for Ericsson-Brayton Piston Engine

    Directory of Open Access Journals (Sweden)

    Peter Durcansky

    2014-01-01

    Full Text Available Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy—energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

  14. Development of Passive Fuel Cell Thermal Management Heat Exchanger

    Science.gov (United States)

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

    2010-01-01

    The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates that could conduct the heat, provide a sufficiently uniform temperature heat sink for each cell of the fuel cell stack, and be substantially lighter than the conventional thermal management approach. Tests were run with different materials to evaluate the design approach to a heat exchanger that could interface with the edges of the passive cooling plates. Measurements were made during fuel cell operation to determine the temperature of individual cooling plates and also to determine the temperature uniformity from one cooling plate to another.

  15. Continued Water-Based Phase Change Material Heat Exchanger Development

    Science.gov (United States)

    Hansen, Scott W.; Sheth, Rubik B.; Poynot, Joe; Giglio, Tony; Ungar, Gene K.

    2015-01-01

    In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to meet the full heat rejection demands. 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 HX's do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development two full-scale, Orion sized water-based PCM HX's were constructed by Mezzo Technologies. These HX's were designed by applying prior research on freeze front propagation to a full-scale design. Design options considered included bladder restraint and clamping mechanisms, bladder manufacturing, tube patterns, fill/drain methods, manifold dimensions, weight optimization, and midplate designs. Two units, Units A and B, were constructed and differed only in their midplate design. Both units failed multiple times during testing. This report highlights learning outcomes from these tests and are applied to a final sub-scale PCM HX which is slated to be tested on the ISS in early 2017.

  16. Qualification of stainless steel for OTEC heat exchanger tubes

    Energy Technology Data Exchange (ETDEWEB)

    LaQue, F.L.

    1979-01-01

    The history of the AL-6X alloy is reviewed and its credentials as a candidate for use as tubing in Ocean Thermal Energy Conversion Heat Exchangers are examined. Qualification is based on results of accelerated tests using ferric chloride for resistance to crevice corrosion and pitting, long-time crevice corrosion and pitting tests in natural sea water and anticipated resistance to attack by ammonia and mixtures of ammonia and sea water. Since the alloy has no natural resistance to fouling by marine organisms, it must be able to accomodate action to prevent fouling by chlorination or to remove it by mechanical cleaning techniques or appropriate chemical cleaning methods. The satisfactory behavior indicated by the various accelerated and long-time corrosion tests has been confirmed by excellent performance of several million feet of tubing in condensers in coastal power plants. Early evaluation tests demonstrated the need for proper heat treatment to avoid the presence of a sigma phase, which promoted severe pitting of some, but not all, specimens in tests in natural sea water. The available data qualify the AL-6X alloy as being a satisfactory alternate to titanium for tubes in OTEC heat exchangers.

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

    Science.gov (United States)

    Erickson, Lisa R.; Ungar, Eugene K.

    2013-01-01

    Maximizing the reuse of wastewater while minimizing the use of consumables is critical in long duration space exploration. One of the more promising methods of reclaiming urine is the distillation/condensation process used in the cascade distillation system (CDS). This system accepts a mixture of urine and toxic stabilizing agents, heats it to vaporize the water and condenses and cools the resulting water vapor. The CDS wastewater flow requires heating and its condensate flow requires cooling. Performing the heating and cooling processes separately requires two separate units, each of which would require large amounts of electrical power. By heating the wastewater and cooling the condensate in a single heat pump unit, mass, volume, and power efficiencies can be obtained. The present work describes and compares two competing heat pump methodologies that meet the needs of the CDS: 1) a series of mini compressor vapor compression cycles and 2) a thermoelectric heat exchanger. In the paper, the system level requirements are outlined, the designs of the two heat pumps are described in detail, and the results of heat pump performance tests are provided. A summary is provided of the heat pump mass, volume and power trades and a selection recommendation is made.

  18. Experimental Research about Thermal Capacity Difference between Domestic and Foreign Plate Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Zhang Ruihang

    2016-01-01

    Full Text Available Because of the noticeable advantages of plate heat exchangers compared with tube heat exchangers, it has been widely applied and researched. However, in the process of practical application, it is easy to find that the performance of heat exchangers produced domestically and from developed countries are quite different, which is one of the key factors that restrict the wide application of domestic plate heat exchangers, there are few studies on this subject yet. Thus, the paper analyzed the main difference of thermal capacity between a domestic and foreign plate heat exchangers through experimental researches, and the results all show that, foreign plate heat exchangers has a more superior thermal capacity and heat exchange efficiency than domestic one, which is in purpose of offering some guidance on technical improvements and applications in the future.

  19. Knowledge-based expert system for fouling assessment of industrial heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Afgan, N.H.; Carvalho, M.G. [Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Electrodinamica

    1996-03-01

    The paper emphasises the need for the development of the expert system as a tool for the mitigation of the fouling processes. Particular reference is given to the design margin lifetime assessment, fouling process control, fouling removal assessment and heat-exchanger safety by the expert system for industrial heat exchangers. This paper presents the concept of a heat-exchanger on-line system. The heat-exchanger efficiency is defined by the NTU concept for the simple parallel co-current heat exchanger. The respective methodology is used for the description of the generic behaviour of the heat-exchanger system. Particular attention was paid to the recognition of those situations leading to the degradation of the efficiency of the heat exchanger. The paper describes the selection of the diagnostic variables and their on-line measurements, including the logging system for the monitoring and acquisition of the data. (Author)

  20. Performance of Helical Coil Heat Recovery Exchanger using Nanofluid as Coolant

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2015-07-01

    Full Text Available Nanofluids are expected to be a promising coolant condidate in chemical processes for heat transfer system size reduction. This paper focuses on reducing the number of turns in a helical coil heat recovery exchanger with a given heat exchange capacity in a biomass heating plant using γ-Al2O3/n-decane nanofluid as coolant. The nanofluid flows through the tubes and the hot n-hexane flows through the shell. The numerical results show that using nanofluid as coolant in a helical coil heat exchanger can reduce the manufacturing cost of the heat exchanger and pumping power by reducing the number of turns of the coil.

  1. Control and prevention of ice formation and accretion on heat exchangers for ventilation systems

    DEFF Research Database (Denmark)

    Rahimi, Maral; Afshari, Alireza

    2015-01-01

    In cold climates, the application of mechanical ventilation systems with heat recovery like are airto-air exchangers is used for reducing energy consumption for heating buildings by transferring heat exhausted air to supply air. However, increase efficiency of heat exchanger results in lower...... exhaust air temperatures and Ice formation on heat exchanger fins, which can cause problem and is not favourable. Therefore, prevention and control of ice formation on heat exchangers is necessary. The existing methods are divided into two different methods: active and passive ice control methods...

  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. 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.

  5. Heat transfer and pressure drop in a heat exchanger with a helical pipe containing inside springs

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, C.; Bicer, Y.; Pehlivan, D. [Firat University, Elazig (Turkey). Engineering Faculty

    1997-12-31

    In this study, a heat exchanger which is constructed by placing spring-shaped wires with varying pitch within a helical pipe was considered. The pressure drop and the overall heat transfer rates were measured for the case of air flow at various Reynolds numbers inside and constant water flow outside. The results show that the Nusselt number increases with decreasing pitch/wire diameter ratio, as much as five times with respect to an empty pipe for the same Dean number, and for this relationship, a tentative empirical formula is suggested. Although a rise up to 10 times in the inlet/outlet pressure drop values with respect to the conventional empty helical case is observed, the increase in Nusselt number, naturally, reflects an increase of about 30% in the effectiveness of the helical heat exchanger. (Author)

  6. Study of hydraulic resistance and heat transfer in perforated-plate heat exchangers

    International Nuclear Information System (INIS)

    Shevyakova, S.A.; Orlov, V.K.

    1983-01-01

    Experimental data on hydraulic resistance and heat transfer in perforated-plate heat-exchangers with different internal geometry: diameter of perforation holes and distance between plates, have been studied and generalized. The plate perforation is formed by round holes 0.625; 0.9 and 1.65 mm in diameter. The distance between perforated plates ranged between 0.4 and 1.6 mm. Criterion ratios are suggested which inexplicitly take into account the effect of the above mentioned geometric parameters; these ratios are applicable for calculation of heat exchangers produced of perforated plates 0.5 mm thick with porosity of perforated plates in the limits of 0.3-0.6, the distance between plates being 0.4-1.6 mm and an arbitrary arrangement of holes in the neighbour plates relative to each other

  7. Annex 3: BRIDGESIM, a simulation tool for the system design of bridge heating for ice prevention with solar heat stored in a seasonal ground duct store

    Energy Technology Data Exchange (ETDEWEB)

    Pahud, D.

    2006-12-15

    This is the Annex 3 of the annual report 2006 of the Serso project. This appendix provides details on the BRIDGESIM simulation tool for the simulation of a bridge heating system that uses heat stored in summer in a long-term diffusive borehole store to ensure an ice-free surface on a road bridge in winter. The operation of the control system which controls the heating system is described. The simulation tool is described and the various input parameters are discussed, as is the parametrisation of the tool itself. These parameters include not only timescales but also data on the borehole heat exchangers, data on the buried heating pipes in the road surface, thermal conductivity of the circulating heat-transfer fluid, ground parameters, intermediate water tank parameters and many other related data. The running of the simulation and output data are also described. Outputs are also presented in graphical form.

  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. Modeling of Heat Transfer in the Helical-Coil Heat Exchanger for the Reactor Facility "UNITERM"

    Directory of Open Access Journals (Sweden)

    V. I. Solonin

    2014-01-01

    Full Text Available Circuit heat sink plays an important role in the reactor system. Therefore it imposes high requirements for quality of determining thermal-hydraulic parameters. This article is aimed at modeling of heat exchange process of the helical-coil heat exchanger, which is part of the heat sink circuit of the reactor facility "UNITERM."The simulation was performed using hydro-gas-dynamic software package ANSYS CFX. Computational fluid dynamics of this package allows us to perform calculations in a threedimensional setting, giving an idea of the fluid flow nature. The purpose of the simulation was to determine the parameters of the helical-coil heat exchanger (temperature, velocity at the outlet of the pipe and inter-tubular space, pressure drop, and the nature of the fluid flow of primary and intermediate coolants. Geometric parameters of the model were determined using the preliminary calculations performed by the criterion equations. In calculations Turbulence models k-ε RNG, Shear Stress Transport (SST are used. The article describes selected turbulence models, and considers relationship with wall function.The calculation results allow us to give the values obtained for thermal-hydraulic parameters, to compare selected turbulence models, as well as to show distribution patterns of the coolant temperature, pressure, and velocity at the outlet of the intermediate cooler.Calculations have shown that:- maximum values of primary coolant temperature at the outlet of the heat exchanger surface are encountered in the space between the helical-coil tubes;- higher temperatures of intermediate coolant at the outlet of the coils (in space of helicalcoil tubes are observed for the peripheral row;- primary coolant movement in the inter-tubular space of helical-coil surface is formed as a spiral flow, rather than as a in-line tube bank cross flow.

  10. Heat exchanger designed as longitudinal counter flow equipment

    International Nuclear Information System (INIS)

    Ecker, H.

    1976-01-01

    An improvement for heat exchangers is described, which should make them suitable for use in a closed gas turbine cycle or in the primary loop of a gas-cooled high-temperature reactor with a helium turbine, as they have a small volume. It is proposed that the bundles of tubes should be divided into separate boxes, which are arranged in a hexagonal grid; the return pipes are arranged in a sheath in the centre of this grid and are welded to the cover of this. The subdivision into separate boxes makes maintenance easier. Constructional details are given, and there are 9 drawings. (UWI) [de

  11. Aging management guideline for commercial nuclear power plants - heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-06-01

    This Aging Management Guideline (AMG) describes recommended methods for effective detection and mitigation of age-related degradation mechanisms in commercial nuclear power plant heat exchangers important to license renewal. The intent of this AMG is to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR 54. This AMG is presented in a manner that allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein.

  12. HECDOR: a heat exchanger cost and design optimization routine

    Energy Technology Data Exchange (ETDEWEB)

    Turner, S.E.; Madsen, W.W.

    1977-04-01

    An update is presented on a series of four computer codes developed by the Bureau of Mines. The programs were developed to evaluate design parameters and cost of heat exchangers. The major differences in three of the programs were concerned with pumping costs; the first (N = 1) used both fluids, the second (N = 2) used tube side fluid, and the third (N = 3) used shell side fluid as a base for prime parameters. All three assumed no change in phase. The fourth program (N = 4) assumed a change of phase on the shell side.

  13. Numerical simulation of two phase flows in heat exchangers

    International Nuclear Information System (INIS)

    Grandotto Biettoli, M.

    2006-04-01

    The author gives an overview of his research activity since 1981. He first gives a detailed presentation of properties and equations of two-phase flows in heat exchangers, and of their mathematical and numerical investigation: semi-local equations (mass conservation, momentum conservation and energy conservation), homogenized conservation equations (mass, momentum and enthalpy conservation, boundary conditions), equation closures, discretization, resolution algorithm, computational aspects and applications. Then, he reports the works performed in the field of turbulent flows, hyperbolic methods, low Mach methods, the Neptune project, and parallel computing

  14. Dynamic analysis of complex tube systems in heat exchangers

    International Nuclear Information System (INIS)

    Kouba, J.; Dvorak, P.

    1985-01-01

    Using a computation model, a dynamic analysis was made of tube assemblies of heat exchanger bundles by the finite element method. The algorithm is presented for determining the frequency mode properties, based on the Sturm sequences combined with inverse vector iteration. The results obtained using the method are compared with those obtained by analytical solution and by the transfer matrix method, this for the cases of both eigenvibrations and resonance vibrations. The results are in very good agreement. For the first four eigenfrequencies, the calculation error is less than 1.5% as against the analytical solution. (J.B.). 4 tabs., 8 figs., 5 refs

  15. Flow induced vibration in shell and tube heat exchangers

    International Nuclear Information System (INIS)

    Soper, B.M.H.

    1981-01-01

    Assessing heat exchanger designs, from the standpoint of flow induced vibration, is becoming increasingly important as shell side flow velocities are increased in a quest for better thermal performance. This paper reviews the state of the art concerning the main sources of vibration excitation, i.e. vortex shedding resonance, turbulent buffeting, fluidelastic instability and acoustic resonance, as well as the structural dynamics of the tubes. It is concluded that there are many areas which require further investigation but there are sufficient data available at present to design, with reasonable confidence, units that will be free from flow induced vibration. Topics which are considered to be key areas for further work are listed

  16. Aging management guideline for commercial nuclear power plants - heat exchangers

    International Nuclear Information System (INIS)

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

    1994-06-01

    This Aging Management Guideline (AMG) describes recommended methods for effective detection and mitigation of age-related degradation mechanisms in commercial nuclear power plant heat exchangers important to license renewal. The intent of this AMG is to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR 54. This AMG is presented in a manner that allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein

  17. 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.

  18. Properties of Alloy 617 for Heat Exchanger Design

    International Nuclear Information System (INIS)

    Wright, R.N.; Carroll, L.J.; Benz, J.K.; Wright, J.K.; Lillo, T.M.; Lybeck, N.J.

    2014-01-01

    Alloy 617 is among the primary candidates for very high temperature reactor heat exchangers anticipated for use up to 950ºC. Elevated temperature properties of this alloy and the mechanisms responsible for the observed tensile, creep and creep-fatigue behavior have been characterized over a wide range of test temperatures up to 1000ºC. Properties from the current experimental program have been combined with archival information from previous VHTR research to provide large data sets for many heats of material, product forms, and weldments. The combined data have been analyzed to determine conservative values of yield and tensile strength, strain rate sensitivity, creep-rupture behavior, fatigue and creep- fatigue properties that can be used for engineering design of reactor components. Phenomenological models have been developed to bound the regions over which the engineering properties are well known or can be confidently extrapolated for use in design. (author)

  19. Properties of Alloy 617 for Heat Exchanger Design

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Richard Neil [Idaho National Laboratory; Carroll, Laura Jill [Idaho National Laboratory; Benz, Julian Karl [Idaho National Laboratory; Wright, Julie Knibloe [Idaho National Laboratory; Lillo, Thomas Martin [Idaho National Laboratory; Lybeck, Nancy Jean [Idaho National Laboratory

    2014-10-01

    Abstract – Alloy 617 is among the primary candidates for very high temperature reactor heat exchangers anticipated for use up to 950ºC. Elevated temperature properties of this alloy and the mechanisms responsible for the observed tensile, creep and creep-fatigue behavior have been characterized over a wide range of test temperatures up to 1000ºC. Properties from the current experimental program have been combined with archival information from previous VHTR research to provide large data sets for many heats of material, product forms, and weldments. The combined data have been analyzed to determine conservative values of yield and tensile strength, strain rate sensitivity, creep-rupture behavior, fatigue and creep- fatigue properties that can be used for engineering design of reactor components. Phenomenological models have been developed to bound the regions over which the engineering properties are well known or can be confidently extrapolated for use in design.

  20. 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.

  1. THE EFFECTS OF SWIRL GENERATOR HAVING WINGS WITH HOLES ON HEAT TRANSFER AND PRESSURE DROP IN TUBE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Zeki ARGUNHAN

    2006-02-01

    Full Text Available This paper examines the effect of turbulance creators on heat transfer and pressure drop used in concentric heat exchanger experimentaly. Heat exchanger has an inlet tube with 60 mm in diameter. The angle of swirl generators wings is 55º with each wing which has single, double, three and four holes. Swirl generators is designed to easily set to heat exchanger entrance. Air is passing through inner tube of heat exhanger as hot fluid and water is passing outer of inner tube as cool fluid.

  2. Experimental investigation of thermal conductivity coefficient and heat exchange between fluidized bed and inclined exchange surface

    Directory of Open Access Journals (Sweden)

    B. Stojanovic

    2009-06-01

    Full Text Available The paper presents experimental research of thermal conductivity coefficients of the siliceous sand bed fluidized by air and an experimental investigation of the particle size influence on the heat transfer coefficient between fluidized bed and inclined exchange surfaces. The measurements were performed for the specific fluidization velocity and sand particle diameters d p=0.3, 0.5, 0.9 mm. The industrial use of fluidized beds has been increasing rapidly in the past 20 years owing to their useful characteristics. One of the outstanding characteristics of a fluidized bed is that it tends to maintain a uniform temperature even with nonuniform heat release. On the basis of experimental research, the influence of the process's operational parameters on the obtained values of the bed's thermal conductivity has been analyzed. The results show direct dependence of thermal conductivity on the intensity of mixing, the degree of fluidization, and the size of particles. In the axial direction, the coefficients that have been treated have values a whole order higher than in the radial direction. Comparison of experimental research results with experimental results of other authors shows good agreement and the same tendency of thermal conductivity change. It is well known in the literature that the value of the heat transfer coefficient is the highest in the horizontal and the smallest in the vertical position of the heat exchange surface. Variation of heat transfer, depending on inclination angle is not examined in detail. The difference between the values of the relative heat transfer coefficient between vertical and horizontal heater position for all particle sizes reduces by approximately 15% with the increase of fluidization rate.

  3. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

    Science.gov (United States)

    Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

    2017-01-12

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  4. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

  5. Heat-exchanger concepts for neutral-beam calorimeters

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  6. Estimation and optimization of heat transfer and overall presure drop for a shell and tube heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Bala Bhaskara [Dept. of Mechanical Engineering, SISTAM College, JNTU, Kakinada (India); Raju, V. Ramachandra [Dept. of Mechanical Engineering, JNTU, Kakinada (India); Deepak, B. B V. L. [Dept. of Industrial Design, National Institute of Technology, Rourkela (India)

    2017-01-15

    Most thermal/chemical industries are equipped with heat exchangers to enhance thermal efficiency. The performance of heat exchangers highly depends on design modifications in the tube side, such as the cross-sectional area, orientation, and baffle cut of the tube. However, these parameters do not exhibit a specific relation to determining the optimum design condition for shell and tube heat exchangers with a maximum heat transfer rate and reduced pressure drops. Accordingly, experimental and numerical simulations are performed for a heat exchanger with varying tube geometries. The heat exchanger considered in this investigation is a single-shell, multiple-pass device. A Generalized regression neural network (GRNN) is applied to generate a relation among the input and output process parameters for the experimental data sets. Then, an Artificial immune system (AIS) is used with GRNN to obtain optimized input parameters. Lastly, results are presented for the developed hybrid GRNN-AIS approach.

  7. A feasible system integrating combined heating and power system with ground-source heat pump

    International Nuclear Information System (INIS)

    Li, HongQiang; Kang, ShuShuo; Yu, Zhun; Cai, Bo; Zhang, GuoQiang

    2014-01-01

    A system integrating CHP (combined heating and power) subsystem based on natural gas and GSHP (ground-source heat pump subsystem) in series is proposed. By help of simulation software-Aspen Plus, the energy performance of a typical CHP and GSHP-S (S refers to ‘in series’) system was analyzed. The results show that the system can make a better use of waste heat in flue gas from CHP (combined heating and power subsystem). The total system energy efficiency is 123% and the COP (coefficient of performance) of GSHP (ground-source heat pump) subsystem is 5.3. A referenced CHP and GSHP-P (P refers to ‘in parallel’) system is used for comparison; its total system energy efficiency and COP of GSHP subsystem are 118.6% and 3.5 respectively. Compared with CHP and GSHP-P system with different operating parameters, the CHP and GSHP-S system can increase total system energy efficiency by 0.8–34.7%, with related output ratio of heat to power (R) from 1.9 to 18.3. Furthermore, the COP of GSHP subsystem can be increased between the range 3.6 and 6, which is much higher than that in conventional CHP and GSHP-P system. This study will be helpful for other efficient GSHP systems integrating if there is waste heat or other heat resources with low temperature. - Highlights: • CHP system based on natural gas and ground source heat pump. • The new system can make a better utilization of waste heat in flue gas by a special way. • The proposed system can realize energy saving potential from 0.8 to 34.7%. • The coefficient of performance of ground source heat pump subsystem is significantly improved from 3.5 to 3.6–6. • Warm water temperature and percentage of flue gas used to reheat are key parameters

  8. 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.

  9. 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.

  10. Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

    International Nuclear Information System (INIS)

    Pilyugin, N.N.; Chernova, T.A.

    1986-01-01

    The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted

  11. Analysis of field coordination on heat exchanger shell side with different diameter tubes and holding structure

    International Nuclear Information System (INIS)

    Li Jing; Lu Minshan; Dong Qiwu

    2009-01-01

    In order to overcome the disadvantages of the rod-baffle heat exchanger, which achieves the high heat transfer efficiency only at high flow velocity, and which with non compact layout of tubes and is weak in the resistance of operation mode changes, this paper proposed two sizes of heat exchange tubes and holding and support structures to replace the traditional rod-baffle support unit, to increase the heat exchange coefficient on shell side and the heat exchange effectiveness. Three-dimensional numerical simulation was conducted on the shellside flow field and heat exchange field by the CFD software, and the calculation method was proposed for the included angle for the shellside velocity-temperature gradient fields of the vertical flow heat exchanger with complex structure. The quantitative relationship of the field coordination angle for the shellside velocity field and temperature gradient field was obtained and it is proved that the new structure is with better field coordination relation. (authors)

  12. Copper metal foam as an essential construction element of innovative heat exchanger

    Directory of Open Access Journals (Sweden)

    R. Rybár

    2016-07-01

    Full Text Available Paper deals with creation of the innovative heat exchanger - manifold header for the heat pipe evacuated tube solar collector, which essential functional element is heat exchange chamber made of the copper metal foam. Design of the heat exchanger is based on effective utilization of the unique properties of the metal foam which makes it possible to design highly effective and space saving devices. Inner volume of heat exchanger was reducing from 0,00045 m3 to 0,000135 m3 and heat exchange surface was increase from 0,0104 m2 to 0,1403 m2 at proposed prototype, what drastically increase heat exchange efficiency. The proposal itself is based on the unique physical properties of the metal foam, which was described by computational analysis.

  13. Analysis of flow induced vibration in heat exchangers

    International Nuclear Information System (INIS)

    Beek, A.W. van

    1977-01-01

    A description will be given of three different types of heat exchangers developed by the Dutch Nuclear Industry Group ''Neratoom'' in cooperation with TNO for the sodium-cooled fast breeder reactor SNR-300 at Kalkar. Moreover, the research related with flow induced vibrations carried out by TNO (Organization for Applied Scientific Research) will be presented. The flow induced forces on the tubes of the straight-tube steam generators were measured at the inlet and outlet section where partial crossflow occurs. With the measured flow induced forces the response of a tube was calculated as a function of the tube-to-supportbush clearances taking into account the non-linear damping effects from the sodium. The theoretical results showed that for this particular design no tube impact damage is to be expected which was confirmed later by a full scale experiment. Special attention will be devoted to the steam generator with helical-coil tube-bundles, where the sodium flows in a counter cross-flow over the tube-bundle. Extensive measurements of the power spectra of the flow induced forces were carried out since no information could be found in the literature. The vibration analysis will be presented and vibration modes of the entire bundle will be compared with experimentally obtained results. Finally a description of the vibration tests to be carried out on the intermediate heat exchanger (IHX) will be presented. (author)

  14. Entropy Generation of Shell and Double Concentric Tubes Heat Exchanger

    Directory of Open Access Journals (Sweden)

    basma abbas abdulmajeed

    2016-06-01

    Full Text Available Entropy generation was studied for new type of heat exchanger (shell and double concentric tubes heat exchanger. Parameters of hot oil flow rate, temperature of inlet hot oil and pressure drop were investigated with the concept of entropy generation. The results showed that the value of entropy generation increased with increasing the flow rate of hot oil and when cold water flow rate was doubled from 20 to 40 l/min, these values were larger. On the other hand, entropy generation increased with increasing the hot oil inlet temperature at a certain flow rate of hot oil. Furthermore, at a certain hot oil inlet temperature, the entropy generation increased with the pressure drop at different hot oil inlet flow rates. Finally, in order to keep up with modern technology, infrared thermography camera was used in order to measure the temperatures. The entropy generation was determined with lower values when infrared thermography camera was used to measure the temperatures, compared with the values obtained by using thermocouples.

  15. Multilinear Model of Heat Exchanger with Hammerstein Structure

    Directory of Open Access Journals (Sweden)

    Dragan Pršić

    2016-01-01

    Full Text Available The multilinear model control design approach is based on the approximation of the nonlinear model of the system by a set of linear models. The paper presents the method of creation of a bank of linear models of the two-pass shell and tube heat exchanger. The nonlinear model is assumed to have a Hammerstein structure. The set of linear models is formed by decomposition of the nonlinear steady-state characteristic by using the modified Included Angle Dividing method. Two modifications of this method are proposed. The first one refers to the addition to the algorithm for decomposition, which reduces the number of linear segments. The second one refers to determination of the threshold value. The dependence between decomposition of the nonlinear characteristic and the linear dynamics of the closed-loop system is established. The decoupling process is more formal and it can be easily implemented by using software tools. Due to its simplicity, the method is particularly suitable in complex systems, such as heat exchanger networks.

  16. Failure Pressure Assessment of the Circumferentially Flawed Heat Exchanger Tubes

    Science.gov (United States)

    Kim, Hyun Su; Jin, Tae Eun; Chang, Yoon Suk; Kim, Young Jin; Kim, Hong Deok

    Since the structural integrity of thin-walled tubes in the heat exchanger is crucial from the viewpoint of safety and reliability, the integrity evaluation for flawed tubes is quite important. Accurate estimation of the failure pressure is a key element of the structural integrity assessment. With regard to the prediction of the failure pressure, most of preceding researches have been focused on the limit load approach. However, the integrity assessment scheme based on the elastic plastic fracture mechanics concept has not been settled despite of its accuracy and efficiency. In this paper, three-dimensional finite element analyses assuming elastic plastic material behavior are carried out for the thin-walled tubes with various sizes of the circumferential flaws. As for the flaw location, both the top of tube sheet and transition regions are considered. The flaw instability is evaluated by comparing the driving force with the fracture toughness of the tube material. Analysis results show that the elastic plastic fracture mechanics approach accurately predicts the failure pressures compared to the experimental data. Thus, it is thought that the elastic plastic fracture mechanics concept can be applied to the integrity assessment of the heat exchanger tubes with the circumferential through-wall flaws.

  17. DRIFT ANALYSIS ON NEURAL NETWORK MODEL OF HEAT EXCHANGER FOULING

    Directory of Open Access Journals (Sweden)

    M. RAMASAMY

    2008-04-01

    Full Text Available Neural Networks (NN provide a good platform for modeling complex and poorly understood systems in many different fields. Due to the empirical nature of NN, it is typically valid only for small operating windows. As the process drifts, the prediction accuracy of such models deteriorates very much rendering the models unfit. An on-line mechanism to follow the drift in the process is necessary in order to retrain the NN models. Information Criteria have been reported to be used for the selection of relevant input variables and determination of optimal NN model structures. This paper proposes the use of information criteria for tracking the model prediction accuracy and provides an algorithm for retraining the model. A heat exchanger in a refinery Crude Preheat Train (CPT has been used as a case study. The operational problems of heat exchangers in CPT are compounded by the varying nature of crude blends and the complex fouling phenomenon. Fouling develops slowly and therefore the drift in the process occurs on a slower scale. The performance of a NN fouling model, developed using industrial data is investigated for drift. Model performance at different operating conditions is evaluated and it has been shown that drifts do occur in the process. An algorithm for retraining NN model has been proposed.

  18. Manufacture of power station heat exchangers using modern production technology

    International Nuclear Information System (INIS)

    Genzlinger, W.; Hoffmann, J.; Ohlhaeuser, K.

    1986-01-01

    Heat exchangers of high quality and operational safety can only be fabricated economically if fabrication is as 'simple' as possible and can be controlled and if, through value analysis, the work flows can be mechanized and automated and the following requirements are met: use of materials that are easy to work with for the application considered, choice of product designs and wall thicknesses that offer favourable conditions for processing and non-destructive testing, placing of seams in such a way that good accessibility for welding and minimum residual welding stresses are assured, minimizing the number of welding seams, use of automatic welding machines for submerged-arc welding and electronically controlled sources of welding current - semi-automatic equipment for spatter-free interfaces (pulse technique), electronically controlled equipment for welding in rollers and pipes and CNC-controlled machining centres for drilling pipe galleries (deep-hole drilling) and baffle plates and for machining the sealing elements after welding. Continuous inspections in each phase of fabrication assures that heat exchangers are made which fully meet the requirements of nuclear power station operators. (orig.)

  19. Tube vibration in industrial size test heat exchanger

    International Nuclear Information System (INIS)

    Halle, H.; Wambsganss, M.W.

    1980-03-01

    Tube vibration data from tests of a specially built and instrumented, industrial-type, shell-and-tube heat exchanger are reported. The heat exchanger is nominally 0.6 m (2 ft) in dia and 3.7 m (12 ft) long. Both full tube and no-tubes-in-window bundles were tested for inlet/outlet nozzles of different sizes and with the tubes supported by seven, equally-spaced, single-segmental baffles. Prior to water flow testing, natural frequencies and damping of representative tubes were measured in air and water. Flow testing was accomplished by increasing the flow rates in stepwise fashion and also by sweeping through a selected range of flow rates. The primary variables measured and reported are tube accelerations and/or displacements and pressure drop through the bundle. Tests of the full tube bundle configuration revealed tube rattling to occur at intermediate flow rates, and fluidelastic instability, with resultant tube impacting, to occur when the flow rate exceeded a threshold level; principally, the four-span tubes were involved in the regions immediately adjacent to the baffle cut. For the range of flow rates tested, fluidelastic instability was not achieved in the no-tubes-in-window bundle; in this configuration the tubes are supported by all seven baffles and are, therefore, stiffer

  20. Optimal assignment of multiple utilities in heat exchange networks

    International Nuclear Information System (INIS)

    Salama, A.I.A.

    2009-01-01

    Existing numerical geometry-based techniques, developed by [A.I.A. Salama, Numerical techniques for determining heat energy targets in pinch analysis, Computers and Chemical Engineering 29 (2005) 1861-1866; A.I.A. Salama, Determination of the optimal heat energy targets in heat pinch analysis using a geometry-based approach, Computers and Chemical Engineering 30 (2006) 758-764], have been extended to optimally assign multiple utilities in heat exchange network (HEN). These techniques utilize the horizontal shift between the cold composite curve (CC) and the stationary hot CC to determine the HEN optimal energy targets, grand composite curve (GCC), and the complement grand composite curve (CGCC). The proposed numerical technique developed in this paper is direct and simultaneously determines the optimal heat-energy targets and optimally assigns multiple utilities as compared with an existing technique based on sequential assignment of multiple utilities. The technique starts by arranging in an ascending order the HEN stream and target temperatures, and the resulting set is labelled T. Furthermore, the temperature sets where multiple utilities are introduced are arranged in an ascending order and are labelled T ic and T ih for the cold and hot sides, respectively. The graphical presentation of the results is facilitated by the insertion at each multiple-utility temperature a perturbed temperature equals the insertion temperature minus a small perturbation. Furthermore, using the heat exchanger network (HEN) minimum temperature-differential approach (ΔT min ) and stream heat-capacity flow rates, the presentation is facilitated by using the conventional temperature shift of the HEN CCs. The set of temperature-shifted stream and target temperatures and perturbed temperatures in the overlap range between the CCs is labelled T ol . Using T ol , a simple formula employing enthalpy-flow differences between the hot composite curve CC h and the cold composite curve CC c is