WorldWideScience

Sample records for chemical heat pipes

  1. Solar chemical heat pipe

    International Nuclear Information System (INIS)

    The performance of a solar chemical heat pipe was studied using CO2 reforming of methane as a vehicle for storage and transport of solar energy. The endothermic reforming reaction was carried out in an Inconel reactor, packed with a Rh catalyst. The reactor was suspended in an insulated box receiver which was placed in the focal plane of the Schaeffer Solar Furnace of the Weizman Institute of Science. The exothermic methanation reaction was run in a 6-stage adiabatic reactor filled with the same Rh catalyst. Conversions of over 80% were achieved for both reactions. In the closed loop mode the products from the reformer and from the metanator were compressed into separate storage tanks. The two reactions were run either separately or 'on-line'. The complete process was repeated for over 60 cycles. The overall performance of the closed loop was quite satisfactory and scale-up work is in progress in the Solar Tower. (authors). 35 refs., 2 figs

  2. Solar chemical heat pipe in a closed loop

    International Nuclear Information System (INIS)

    The work on the solar CO2 reforming of methane was completed. A computer program was developed for simulation of the whole process. The calculations agree reasonably well with the experimental results. The work was written up and submitted for publication in Solar Energy. A methanator was built and tested first with a CO/H2 mixture from cylinders, and then with the products of the solar reformer. The loop was then closed by recirculating the products from the methanator into the solar reformer. Nine closed loop cycles were performed, so far, with the same original gas mixture. This is the first time that a closed loop solar chemical heat pipe was operated anywhere in the world. (author). 13 refs., 12 figs., 3 tabs

  3. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1994-01-01

    It is approximately 10 years since the Third Edition of Heat Pipes was published and the text is now established as the standard work on the subject. This new edition has been extensively updated, with revisions to most chapters. The introduction of new working fluids and extended life test data have been taken into account in chapter 3. A number of new types of heat pipes have become popular, and others have proved less effective. This is reflected in the contents of chapter 5. Heat pipes are employed in a wide range of applications, including electronics cooling, diecasting and injection mo

  4. Heat Pipes

    Science.gov (United States)

    1996-01-01

    Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.

  5. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1982-01-01

    A comprehensive, up-to-date coverage of the theory, design and manufacture of heat pipes and their applications. This latest edition has been thoroughly revised, up-dated and expanded to give an in-depth coverage of the new developments in the field. Significant new material has been added to all the chapters and the applications section has been totally rewritten to ensure that topical and important applications are appropriately emphasised. The bibliography has been considerably enlarged to incorporate much valuable new information. Thus readers of the previous edition, which has established

  6. Closed loop chemical systems for energy storage and transmission (chemical heat pipe). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vakil, H.B.; Flock, J.W.

    1978-02-01

    The work documents the anlaysis of closed loop chemical systems for energy storage and transmission, commonly referred to as the Chemical Heat Pipe (CHP). Among the various chemical reaction systems and sources investigated, the two best systems were determined to be the high temperature methane/steam reforming reaction (HTCHP) coupled to a Very High Temperature Gas Cooled Reactor (VHTR) and the lower temperature, cyclohexane dehydrogenation reaction (LTCHP) coupled to existing sources such as coal or light water reactors. Solar and other developing technologies can best be coupled to the LTCHP. The preliminary economic and technical analyses show that both systems could transport heat at an incremental cost of approximately $1.50/GJ/160 km (in excess of the primary heat cost of $2.50/GJ), at system efficiencies above 80%. Solar heat can be transported at an incremental cost of $3/GJ/160 km. The use of the mixed feed evaporator concept developed in this work contributes significantly to reducing the transportation cost and increasing the efficiency of the system. The LTCHP shows the most promise of the two systems if the technical feasibility of the cyclic closed loop chemical reaction system can be established. An experimental program for establishing this feasibility is recommended. Since the VHTR is several years away from commercial demonstration and the HTCHP chemical technology is well developed, future HTCHP programs should be aimed at VHTR and interface problems.

  7. Heat Pipe Planets

    Science.gov (United States)

    Moore, William B.; Simon, Justin I.; Webb, A. Alexander G.

    2014-01-01

    When volcanism dominates heat transport, a terrestrial body enters a heat-pipe mode, in which hot magma moves through the lithosphere in narrow channels. Even at high heat flow, a heat-pipe planet develops a thick, cold, downwards-advecting lithosphere dominated by (ultra-)mafic flows and contractional deformation at the surface. Heat-pipes are an important feature of terrestrial planets at high heat flow, as illustrated by Io. Evidence for their operation early in Earth's history suggests that all terrestrial bodies should experience an episode of heat-pipe cooling early in their histories.

  8. Oscillating heat pipes

    CERN Document Server

    Ma, Hongbin

    2015-01-01

    This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation,  theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary  factors affecting oscillating motions and heat transfer,  neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes.  The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...

  9. Heat Pipe Materials Compatibility

    Science.gov (United States)

    Eninger, J. E.; Fleischman, G. L.; Luedke, E. E.

    1976-01-01

    An experimental program to evaluate noncondensable gas generation in ammonia heat pipes was completed. A total of 37 heat pipes made of aluminum, stainless steel and combinations of these materials were processed by various techniques, operated at different temperatures and tested at low temperature to quantitatively determine gas generation rates. In order of increasing stability are aluminum/stainless combination, all aluminum and all stainless heat pipes. One interesting result is the identification of intentionally introduced water in the ammonia during a reflux step as a means of surface passivation to reduce gas generation in stainless-steel/aluminum heat pipes.

  10. Introduction to Heat Pipes

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    This is the presentation file for the short course Introduction to Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. NCTS 21070-15. Course Description: This course will present operating principles of the heat pipe with emphases on the underlying physical processes and requirements of pressure and energy balance. Performance characterizations and design considerations of the heat pipe will be highlighted. Guidelines for thermal engineers in the selection of heat pipes as part of the spacecraft thermal control system, testing methodology, and analytical modeling will also be discussed.

  11. Heat pipe technology issues

    International Nuclear Information System (INIS)

    Critical high temperature, high power applications in space nuclear power designs are near the current state of the art of heat pipe technology in terms of power density, operating temperature, and lifetime. Recent heat pipe development work at Los Alamos National Laboratory has involved performance testing of typical space reactor heat pipe designs to power levels in excess of 19 kW/cm2 axially and 300 W/cm2 radially at temperatures in the 1400 to 1500 K range. Operation at conditions in the 10 kW/cm2 range has been sustained for periods of up to 1000 hours without evidence of performance degradation. The effective length for heat transport in these heat pipes was from 1.0 to 1.5 M. Materials used were molybdenum alloys with lithium employed as the heat pipe operating fluid. Shorter, somewhat lower power, molybdenum heat pipes have been life tested at Los Alamos for periods of greater than 25,000 hours at 1700 K with lithium and 20,000 hours at 15000K with sodium. These life test demonstrations and the attendant performance limit investigations provide an experimental basis for heat pipe application in space reactor design and represent the current state-of-the-art of high temperature heat pipe technology

  12. Heat pipe technology issues

    International Nuclear Information System (INIS)

    Recent heat pipe development work at Los Alamos National Laboratory as involved performance testing of typical space reactor heat pipe designs to power levels in excess of 19 kW/cm2 axially and 300 W/cm2 radially at temperatures in the 1400 to 15000K range. Operation at conditions in the 10 kW/cm2 range has been sustained for periods of up to 1000 hours without evidence of performance degradation. The effective length for heat transport in these heat pipes was from 1.0 to 1.5 M. Materials used were molybdenum alloys with lithium employed as the heat pipe operating fluid. Shorter, somewhat lower power density, molybdenum heat pipes have been life tested at Los Alamos for periods of greater than 25,000 hours at 17000K with lithium and 20,000 hours at 15000K with sodium. These life test demonstrations and the attendant performance limit investigations provide an experimental basis for heat pipe application in space reactor design and represent the current state-of-the-art of high temperature heat pipe technology. 9 refs., 11 figs

  13. Silicon Heat Pipe Array

    Science.gov (United States)

    Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

    2013-01-01

    Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better

  14. Heat Pipe Systems

    Science.gov (United States)

    1993-01-01

    The heat pipe was developed to alternately cool and heat without using energy or any moving parts. It enables non-rotating spacecraft to maintain a constant temperature when the surface exposed to the Sun is excessively hot and the non Sun-facing side is very cold. Several organizations, such as Tropic-Kool Engineering Corporation, joined NASA in a subsequent program to refine and commercialize the technology. Heat pipes have been installed in fast food restaurants in areas where humid conditions cause materials to deteriorate quickly. Moisture removal was increased by 30 percent in a Clearwater, FL Burger King after heat pipes were installed. Relative humidity and power consumption were also reduced significantly. Similar results were recorded by Taco Bell, which now specifies heat pipe systems in new restaurants in the Southeast.

  15. Heat pipes and use of heat pipes in furnace exhaust

    Science.gov (United States)

    Polcyn, Adam D.

    2010-12-28

    An array of a plurality of heat pipe are mounted in spaced relationship to one another with the hot end of the heat pipes in a heated environment, e.g. the exhaust flue of a furnace, and the cold end outside the furnace. Heat conversion equipment is connected to the cold end of the heat pipes.

  16. Heat pipe applications workshop report

    Energy Technology Data Exchange (ETDEWEB)

    Ranken, W.A.

    1978-04-01

    The proceedings of the Heat Pipe Applications Workshop, held at the Los Alamos Scientific Laboratory October 20-21, 1977, are reported. This workshop, which brought together representatives of the Department of Energy and of a dozen industrial organizations actively engaged in the development and marketing of heat pipe equipment, was convened for the purpose of defining ways of accelerating the development and application of heat pipe technology. Recommendations from the three study groups formed by the participants are presented. These deal with such subjects as: (1) the problem encountered in obtaining support for the development of broadly applicable technologies, (2) the need for applications studies, (3) the establishment of a heat pipe technology center of excellence, (4) the role the Department of Energy might take with regard to heat pipe development and application, and (5) coordination of heat pipe industry efforts to raise the general level of understanding and acceptance of heat pipe solutions to heat control and transfer problems.

  17. Heat pipe applications workshop report

    International Nuclear Information System (INIS)

    The proceedings of the Heat Pipe Applications Workshop, held at the Los Alamos Scientific Laboratory October 20-21, 1977, are reported. This workshop, which brought together representatives of the Department of Energy and of a dozen industrial organizations actively engaged in the development and marketing of heat pipe equipment, was convened for the purpose of defining ways of accelerating the development and application of heat pipe technology. Recommendations from the three study groups formed by the participants are presented. These deal with such subjects as: (1) the problem encountered in obtaining support for the development of broadly applicable technologies, (2) the need for applications studies, (3) the establishment of a heat pipe technology center of excellence, (4) the role the Department of Energy might take with regard to heat pipe development and application, and (5) coordination of heat pipe industry efforts to raise the general level of understanding and acceptance of heat pipe solutions to heat control and transfer problems

  18. Heat Pipes For Alyeska

    Science.gov (United States)

    1977-01-01

    The heat pipes job is to keep the arctic ground frozen. The permafrost soil alternately freezes and thaws with seasonal temperature changes causing surface dislocations and problems for the builders. In winter, a phenomenon called frost-heaving uplifts the soil. It is something like the creation of highway potholes by the freezing of rainwater below the roadbed, but frost-heaving exerts a far greater force. Thawing of the frost in the summer causes the soil to settle unevenly. Therefore it is necessary to keep the soil in a continually frozen state so the pipeline won't rupture. To solve this problem, McDonnell Douglas Corp. applied heat pipe principles in the design of the vertical supports that hold up the pipeline.

  19. Heat Pipe Blocks Return Flow

    Science.gov (United States)

    Eninger, J. E.

    1982-01-01

    Metal-foil reed valve in conventional slab-wick heat pipe limits heat flow to one direction only. With sink warmer than source, reed is forced closed and fluid returns to source side through annular transfer wick. When this occurs, wick slab on sink side of valve dries out and heat pipe ceases to conduct heat.

  20. Electrodynamic heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Shkilev, V.D.

    1982-01-01

    An electrohydrodynamic heat pipe consists of a housing in the form of a closed loop with rising and descending branches, in the first of which are located evaporator, ionizer, which is connected to a high voltage source, a nozzle and a collector of electrical charges. The second branch contains a condenser. In order to improve operating stability, the condenser is equipped with a collector for part of the condensate. It is connected by means of a dielectric tube to a nozzle, and the ionizer of the unit in the outgoing section of the tube is inserted within the nozzle along its access and faces the collector.

  1. Equivalent thermal conductivity of heat pipes

    Institute of Scientific and Technical Information of China (English)

    Zesheng LU; Binghui MA

    2008-01-01

    In precision machining, the machining error from thermal distortion carries a high proportion of the total errors. If a precision machining tool can transfer heat fast, the thermal distortion will be reduced and the machining precision will be improved. A heat pipe working based on phase transitions of the inner working liquid transfers heat with high efficiency and is widely applied in spaceflight and chemical industries. In mechanics, applications of heat pipes are correspondingly less. When a heat pipe is applied to a hydrostatic motor-ized spindle, the thermal distortion cannot be solved dur-ing the heat transfer process because thermal conductivity or equivalent thermal conductivity should be provided first for special application in mechanics. An equivalent thermal conductivity model based on equivalent thermal resistances is established. Performance tests for a screen wick pipe, gravity pipe, and rotation heat pipe are done to validate the efficiency of the equivalent thermal conduc-tivity model. The proposed model provides a calculation method for the thermal distortion analysis of heat pipes applied in the motorized spindle.

  2. Alternate high capacity heat pipe

    Science.gov (United States)

    Voss, F. E.

    1986-01-01

    The performance predictions for a fifty foot heat pipe (4 foot evaporator - 46 foot condensor) are discussed. These performance predictions are supported by experimental data for a four foot heat pipe. Both heat pipes have evaporators with axial groove wick structures and condensers with powder metal external artery wick structures. The predicted performance of a rectangular axial groove/external artery heat pipe operating in space is given. Heat transport versus groove width is plotted for 100, 200 and 300 grooves in the evaporator. The curves show that maximum power is achieved for groove widths from 0.040 to 0.053 as the number of grooves varies from 300 to 100. The corresponding range of maximum power is 3150 to 2400 watts. The relationships between groove width and heat pipe evaporate diameter for 100, 200 and 300 grooves in the evaporator are given. A four foot heat pipe having a three foot condenser and one foot evaporator was built and tested. The evaporator wick structure used axial grooves with rectangular cross sections, and the condenser wick structure used powder metal with an external artery configuration. Fabrication drawings are enclosed. The predicted and measured performance for this heat pipe is shown. The agreement between predicted and measured performance is good and therefore substantiates the predicted performance for a fifty foot heat pipe.

  3. Heat pipe turbine vane cooling

    Energy Technology Data Exchange (ETDEWEB)

    Langston, L.; Faghri, A. [Univ. of Connecticut, Storrs, CT (United States)

    1995-10-01

    The applicability of using heat pipe principles to cool gas turbine vanes is addressed in this beginning program. This innovative concept involves fitting out the vane interior as a heat pipe and extending the vane into an adjacent heat sink, thus transferring the vane incident heat transfer through the heat pipe to heat sink. This design provides an extremely high heat transfer rate and an uniform temperature along the vane due to the internal change of phase of the heat pipe working fluid. Furthermore, this technology can also eliminate hot spots at the vane leading and trailing edges and increase the vane life by preventing thermal fatigue cracking. There is also the possibility of requiring no bleed air from the compressor, and therefore eliminating engine performance losses resulting from the diversion of compressor discharge air. Significant improvement in gas turbine performance can be achieved by using heat pipe technology in place of conventional air cooled vanes. A detailed numerical analysis of a heat pipe vane will be made and an experimental model will be designed in the first year of this new program.

  4. Heat pipe turbine vane cooling

    Energy Technology Data Exchange (ETDEWEB)

    Langston, L.; Faghri, A. [Connecticut Univ., Storrs, CT (United States). Dept. of Mechanical Engineering

    1995-12-31

    The applicability of using heat pipe principles to cool gas turbine vanes is addressed in this beginning program. This innovative concept involves fitting out the vane interior as a heat pipe and extending the vane into an adjacent heat sink, thus transferring the vane incident heat transfer through the heat pipe to heat sink. This design provides an extremely high heat transfer rate and a uniform temperature along the vane due to the internal change of phase of the heat pipe working fluid. Furthermore, this technology can also eliminate hot spots at the vane leading and trailing edges and increase the vane life by preventing thermal fatigue cracking. There is also the possibility of requiring no bleed air from the compressor, and therefore eliminating engine performance losses resulting from the diversion of compressor discharge air. Significant improvement in gas turbine performance can be achieved by using heat pipe technology in place of conventional air cooled vanes. A detailed numerical analysis of a heat pipe vane will be made and an experimental model will be designed in the first year of this new program.

  5. Mapping Temperatures On Heat Pipes

    Science.gov (United States)

    Gunnerson, Fred S.; Thorncroft, Glen E.

    1993-01-01

    Paints containing thermochromic liquid crystals (TLC's) used to map temperatures on heat pipes and thermosyphons. Color of thermally sensitive TLC coat changes reversibly upon heating or cooling. Each distinct color indicates particular temperature. Transient and steady-state isotherms become visible as colored bands. Positions and movements of bands yield information about startup transients, steady-state operation, cooler regions containing noncondensible gas, and other phenomena relevant to performance of heat pipe.

  6. Loop Heat Pipe Startup Behaviors

    Science.gov (United States)

    Ku, Jentung

    2016-01-01

    A loop heat pipe must start successfully before it can commence its service. The startup transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe startup behaviors. Topics include the four startup scenarios, the initial fluid distribution between the evaporator and reservoir that determines the startup scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power startup, and methods to enhance the startup success. Also addressed are the pressure spike and pressure surge during the startup transient, and repeated cycles of loop startup and shutdown under certain conditions.

  7. Physics of heat pipe rewetting

    Science.gov (United States)

    Chan, S. H.

    This is the final report which summarizes the research accomplishments under the project entitled 'Physics of Heat Pipe Rewetting' under NASA Grant No. NAG 9-525, Basic, during the period of April 1, 1991 to January 31, 1994. The objective of the research project was to investigate both analytically and experimentally the rewetting characteristics of the heated, grooved plate. The grooved plate is to simulate the inner surface of the vapor channel in monogroove heat pipes for space station design. In such designs, the inner surface of the vapor channel is threaded with monogrooves. When the heat pipe is thermally overloaded, dryout of the monogroove surface occurs. Such a dryout surface should be promptly rewetted to prevent the failure of the heat pipe operation in the thermal radiator of the space station.

  8. Loop Heat Pipe Startup Behaviors

    Science.gov (United States)

    Ku, Jentung

    2014-01-01

    A loop heat pipe must start successfully before it can commence its service. The start-up transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe start-up behaviors. Topics include the four start-up scenarios, the initial fluid distribution between the evaporator and reservoir that determines the start-up scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power start-up, and methods to enhance the start-up success. Also addressed are the thermodynamic constraint between the evaporator and reservoir in the loop heat pipe operation, the superheat requirement for nucleate boiling, pressure spike and pressure surge during the start-up transient, and repeated cycles of loop start-up andshutdown under certain conditions.

  9. Electrohydrodynamic inductively pumped heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, A.S.

    1981-01-19

    The self-priming voltage controllable electrohydrodynamic inductively pumped heat pipe of the present invention greatly improves the maximum thermal throughout of heat pipes in low and medium temperature applications calling for the use of dielectric working fluids. An applied traveling potential wave induces a traveling wave of electrical charge in selected phase relation in the liquid phase of the dielectric working fluid providing an electrical traction which pumps the working fluid from the condensor to the evaporator.

  10. Sintered aluminium heat pipe (SAHP)

    OpenAIRE

    Ameli, Masoud; Agnew, Brian; Ng, Bobo; McGlen, R. J.; C. J. Sutcliffe; Singh, J

    2012-01-01

    This work is the product of an ongoing PhD project in the School of the Built and Natural Environment of Northumbria University in collaboration with the University of Liverpool and Thermacore Europe Ltd. The achievements at the end of the first year are summarized. The main objective of the project is to develop an aluminum ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded axially grooved aluminum tubes as a capillary wick. There hav...

  11. Intermediate Temperature Water Heat Pipe Tests

    Science.gov (United States)

    Devarakonda, Angirasa; Xiong, Da-Xi; Beach, Duane E.

    2005-01-01

    Heat pipes are among the most promising technologies for space radiator systems. Water heat pipes are explored in the intermediate temperature range of 400 to above 500 K. The thermodynamic and thermo-physical properties of water are reviewed in this temperature range. Test data are reported for a copper-water heat pipe. The heat pipe was tested under different orientations. Water heat pipes show promise in this temperature range. Fabrication and testing issues are being addressed.

  12. High-Capacity Heat-Pipe Evaporator

    Science.gov (United States)

    Oren, J. A.; Duschatko, R. J.; Voss, F. E.; Sauer, L. W.

    1989-01-01

    Heat pipe with cylindrical heat-input surface has higher contact thermal conductance than one with usual flat surface. Cylindrical heat absorber promotes nearly uniform flow of heat into pipe at all places around periphery of pipe, helps eliminate hotspots on heat source. Lugs in aluminum pipe carry heat from outer surface to liquid oozing from capillaries of wick. Liquid absorbs heat, evaporates, and passes out of evaporator through interlug passages.

  13. Thermal Performance of High Temperature Titanium-Water Heat Pipes by Multiple Heat Pipe Manufacturers

    Science.gov (United States)

    Sanzi, James L.

    2007-01-01

    Titanium-water heat pipes are being investigated for use in heat rejection systems for lunar and Mars fission surface power systems. Heat pipes provide an efficient and reliable means to transfer heat to a radiator heat rejection system. NASA Glenn Research Center requisitioned nine titanium water heat pipes from three vendors. Each vendor supplied three heat pipes 1.25 cm diameter by 1.1 meter long with each vendor selecting a different wick design. Each of the three heat pipes is slightly different in construction. Additional specifications for the heat pipes included 500 K nominal operating temperature, light weight, and freeze tolerance. The heat pipes were performance tested gravity-aided, in the horizontal position and at elevations against gravity at 450 and 500 K. Performance of the three heat pipes is compared. The heat pipe data will be used to verify models of heat pipe radiators that will be used in future space exploration missions.

  14. Thermal Performance of High Temperature Titanium -- Water Heat Pipes by Multiple Heat Pipe Manufacturers

    Science.gov (United States)

    Sanzi, James L.

    2007-01-01

    Titanium - water heat pipes are being investigated for use in heat rejection systems for lunar and Mars fission surface power systems. Heat pipes provide an efficient and reliable means to transfer heat to a radiator heat rejection system. NASA Glenn Research Center requisitioned nine titanium water heat pipes from three vendors. Each vendor supplied three heat pipes 1.25 cm diameter by 1.1 meter long with each vendor selecting a different wick design. Each of the three heat pipes is slightly different in construction. Additional specifications for the heat pipes included 500 K nominal operating temperature, light weight, and freeze tolerance. The heat pipes were performance tested gravity-aided, in the horizontal position and at elevations against gravity at 450 K and 500 K. Performance of the three heat pipes is compared. The heat pipe data will be used to verify models of heat pipe radiators that will be used in future space exploration missions.

  15. Computing Temperatures And Pressures Along Heat Pipes

    Science.gov (United States)

    Faker, K. W.; Marks, T. S.; Tower, L. K.

    1994-01-01

    NASA Lewis Research Center Heat Pipe, LERCHP, computer code developed to predict performances of heat pipes in steady state. Used as design software tool on personal computer or, with suitable calling routine, as subroutine for mainframe-computer radiator code. For accurate mathematical modeling of heat pipes, LERCHP makes variety of wick structures available to user. User chooses among several working fluids, for which monomer/dimer equilibrium considered. Vapor-flow algorithm treats compressibility and axially varying heat input. Facilitates determination of heat-pipe operating temperatures and heat-pipe limits encountered at specified heat input and environmental temperature. Written in FORTRAN 77.

  16. Review of heat pipe liquid delivery concepts

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, C.C. Jr.

    1981-01-01

    The return of liquid condensate to the heat pipe evaporator is a limitation on heat pipe performance. This paper reviews the following schemes to achieve liquid pumping over vertical distances: (a) Mechanical pumping using external power, (b) buoyancy bubble pumping, (c) bubble injection pumping, (d) electrohydrodynamic pumping, (e) cascaded heat pipe, (f) mechanical pumping using internal power, (g) rotating wheel, (h) oscillating pressure driven pumping, (i) osmotic heat pipe. 7 refs.

  17. Review of heat pipe liquid delivery concepts

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, C.C. Jr.

    1981-01-01

    The return of liquid condensate to the heat pipe evaporator is a limitation on heat pipe performance. The following schemes are reviewed to achieve liquid pumping over vertical distances: (a) mechanical pumping using external power; (b) buoyancy bubble pumping; (c) bubble injection pumping; (d) electrohydrodynamic pumping; (e) cascaded heat pipe; (f) mechanical pumping using internal power; (g) rotating wheel; (h) oscillating pressure driven pumping; and (i) osmotic heat pipe.

  18. Heat-pipe thermionic reactor concept

    DEFF Research Database (Denmark)

    Storm Pedersen, E.

    1967-01-01

    Main components are reactor core, heat pipe, thermionic converter, secondary cooling system, and waste heat radiator; thermal power generated in reactor core is transported by heat pipes to thermionic converters located outside reactor core behind radiation shield; thermionic emitters are in direct...... contact with outside envelope of heat pipes and collectors are in contact with liquid metal secondary cooling system that transfers waste heat to radiator....

  19. Entrainment in electrohydrodynamic heat pipes

    Science.gov (United States)

    Jones, T. B.; Perry, M. P.

    1972-01-01

    A theoretical analysis for predicting the onset of the Kelvin-Helmholtz instability is reported. The model for the analysis is described, and the derived stability criterion are given. It is concluded that surface tension plays a role in the entrainment limit of electro hydrodynamic heat pipes. The surface of the liquid in an EHD flow structure is open, with no restriction placed on the wavenumbers of perturbations.

  20. Poisoning of Heat Pipes

    Science.gov (United States)

    Gillies, Donald; Lehoczky, Sandor; Palosz, Witold; Carpenter, Paul; Salvail, Pat

    2007-01-01

    Thermal management is critical to space exploration efforts. In particular, efficient transfer and control of heat flow is essential when operating high energy sources such as nuclear reactors. Thermal energy must be transferred to various energy conversion devices, and to radiators for safe and efficient rejection of excess thermal energy. Applications for space power demand exceptionally long periods of time with equipment that is accessible for limited maintenance only. Equally critical is the hostile and alien environment which includes high radiation from the reactor and from space (galactic) radiation. In space or lunar applications high vacuum is an issue, while in Martian operations the systems will encounter a CO2 atmosphere. The effect of contact at high temperature with local soil (regolith) in surface operations on the moon or other terrestrial bodies (Mars, asteroids) must be considered.

  1. Lightweight Heat Pipes Made from Magnesium

    Science.gov (United States)

    Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

    2010-01-01

    Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

  2. Heat pipes for temperature control

    International Nuclear Information System (INIS)

    Heat pipes have known for years as effective constructional elements for temperature control. With the aid of special techniques (gas, liquid, steam, and voltage control), special operating characteristics can be obtained, e.g. variable heat conduction or diode behaviour. Their main field of application is in spacecraft technology and in nuclear technology in the isothermalisation of irradiation capsules. The different control techniques are presented and critically evaluated on the basis of characteristic properties like heat transfer capacity, volume and mass requirements, complexity of structure and production, reliability, and temperature control characteristics. Advantages and shortcomings of the different concepts are derived and compared. The state of the art of these control techniques is established on the basis of four development levels. Finally, the necessity and direction of further R + D activities are discussed, and suggestions are made for further work. (orig./HP)

  3. 热管技术在化工领域中的应用综述%Overview of Heat Pipe Technology and Its Application in Chemical Industry

    Institute of Scientific and Technical Information of China (English)

    乔桂芝

    2011-01-01

    The sketch of development history, working theory and advantages of heat pipe technology were given, and its application in chemical industry and latest development were discussed.%时热管的发展历史、工作原理及其优点作了简单的阐述,主要介绍了热管技术在化工领城的几个方面的应用情况,并探讨了热管技术最新的发展方向.

  4. Heat-pipe thermionic reactor concept

    DEFF Research Database (Denmark)

    Storm Pedersen, E.

    1967-01-01

    Main components are reactor core, heat pipe, thermionic converter, secondary cooling system, and waste heat radiator; thermal power generated in reactor core is transported by heat pipes to thermionic converters located outside reactor core behind radiation shield; thermionic emitters are in dire...

  5. Heat Pipe with Axial Wick

    Science.gov (United States)

    Ambrose, Jay H. (Inventor); Holmes, Rolland (Inventor)

    2016-01-01

    A heat pipe has an evaporator portion, a condenser portion, and at least one flexible portion that is sealingly coupled between the evaporator portion and the condenser portion. The flexible portion has a flexible tube and a flexible separator plate held in place within the flexible tube so as to divide the flexible tube into a gas-phase passage and a liquid-phase artery. The separator plate and flexible tube are configured such that the flexible portion is flexible in a plane that is perpendicular to the separator plate.

  6. Intermediate Temperature Fluids for Heat Pipes and Loop Heat Pipes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop heat pipe and loop heat pipe (LHP) working fluids for what is known as the intermediate...

  7. Heat pipe cooling system with sensible heat sink

    Science.gov (United States)

    Silverstein, Calvin C.

    1988-01-01

    A heat pipe cooling system which employs a sensible heat sink is discussed. With this type of system, incident aerodynamic heat is transported via a heat pipe from the stagnation region to the heat sink and absorbed by raising the temperature of the heat sink material. The use of a sensible heat sink can be advantageous for situations where the total mission heat load is limited, as it is during re-entry, and a suitable radiation sink is not available.

  8. Mechanical and chemical properties of sewage pipes

    OpenAIRE

    Ł. Wierzbicki; M. Szymiczek

    2012-01-01

    Purpose: The purpose of this paper was to evaluate the compatibility of the physico-chemical properties of sewage pipes with the requirements of PN – EN ISO 1401-01: Plastics piping systems for non-pressure underground drainage and sewerage. This article is based on a research carried out for the water supply company. The article presents the results of mechanical and chemical testing of four pipes of unplasticized polyvinyl chloride and one pipe of polypropylene. All the test pipes were app...

  9. Heat pipes theory, design and applications

    CERN Document Server

    Reay, David; Kew, Peter

    2013-01-01

    Heat Pipes, 6th Edition, takes a highly practical approach to the design and selection of heat pipes, making it an essential guide for practicing engineers and an ideal text for postgraduate students. This new edition has been revised to include new information on the underlying theory of heat pipes and heat transfer, and features fully updated applications, new data sections, and updated chapters on design and electronics cooling. The book is a useful reference for those with experience and an accessible introduction for those approaching the topic for the first time. Contains all informat

  10. Flat plate electrohydrodynamic heat pipe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Loehrke, R.I.; Sebits, D.R.

    1975-07-01

    Performance capabilities of electrohydrodynamic (EHD) flat heat pipes were investigated using Freon 113 and Freon 11 as working fluids. All of the pipes employed straight rod electrodes to form axial liquid flow channels and tranverse grooves for capillary surface wetting. Results show: (1) the EHD pipe will prime under load; (2) voltage controlled conductance can be achieved by varying the active area of the evaporator; and (3) the average evaporator conductances measured in these experiments were consistent with those obtained in other experiments with heat pipes of similar surface geometry using the same or similar working fluids.

  11. Optimal design of the separate type heat pipe heat exchanger

    Institute of Scientific and Technical Information of China (English)

    YU Zi-tao; HU Ya-cai; CEN Ke-fa

    2005-01-01

    Separate type heat pipe heat exchangers are often used for large-scale heat exchanging. The arrangement of such a heat exchanger conveniently allows heat input to and output from the heat exchanger at remote locations. The traditional method of designing an ordinary HPHE (heat pipe heat exchanger) is commonly applied in the separate type exchanger design, but the calculations have to be carried out separately, which makes it very complicated. In this work, the ε-NTU (effectiveness-Number of Transfer Units) method was applied for optimization analysis of single- or multi-level separate type heat pipe heat exchangers. An optimizing formula for single-level separate type heat pipe heat exchangers was obtained. The optimizing principles of effectiveness-NTU and heat transfer rate by the equal distribution method for multi-level separate type heat pipe heat exchanger are presented. The design of separate type heat pipe heat exchangers by the optimizing method is more convenient and faster than by the traditional method.

  12. Heat pipe effect in porous medium

    International Nuclear Information System (INIS)

    In this thesis a parametric study of the thermal and hydrologic characteristics of the fractured porous tuffs at Yucca Mountain, Nevada was conducted. The effects of different fracture and matrix properties including permeability, thermal conductivity, specific heat, porosity, and tortuosity on heat pipe performance in the vicinity of the waste package were observed. Computer simulations were carried out using TOUGH code on a Cray YMP-2 supercomputer. None of the fracture parameters affected the heat pipe performance except the mobility of the liquid in the fracture. Matrix permeability and thermal conductivity were found to have significant effect on the heat pipe performance. The effect of mass injection was studied for liquid water and air injected at the fracture boundary. A high rate of mass injection was required to produce any effect on the heat pipe. The fracture-matrix equilibrium is influenced by the matrix permeability and the matrix thermal conductivity

  13. Modeling of pulsating heat pipes.

    Energy Technology Data Exchange (ETDEWEB)

    Givler, Richard C.; Martinez, Mario J.

    2009-08-01

    This report summarizes the results of a computer model that describes the behavior of pulsating heat pipes (PHP). The purpose of the project was to develop a highly efficient (as compared to the heat transfer capability of solid copper) thermal groundplane (TGP) using silicon carbide (SiC) as the substrate material and water as the working fluid. The objective of this project is to develop a multi-physics model for this complex phenomenon to assist with an understanding of how PHPs operate and to be able to understand how various parameters (geometry, fill ratio, materials, working fluid, etc.) affect its performance. The physical processes describing a PHP are highly coupled. Understanding its operation is further complicated by the non-equilibrium nature of the interplay between evaporation/condensation, bubble growth and collapse or coalescence, and the coupled response of the multiphase fluid dynamics among the different channels. A comprehensive theory of operation and design tools for PHPs is still an unrealized task. In the following we first analyze, in some detail, a simple model that has been proposed to describe PHP behavior. Although it includes fundamental features of a PHP, it also makes some assumptions to keep the model tractable. In an effort to improve on current modeling practice, we constructed a model for a PHP using some unique features available in FLOW-3D, version 9.2-3 (Flow Science, 2007). We believe that this flow modeling software retains more of the salient features of a PHP and thus, provides a closer representation of its behavior.

  14. Titanium Heat Pipe Thermal Plane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermacore Inc. proposes an innovative titanium heat pipe thermal plane for passive thermal control of individual cells within a fuel cell stack. The proposed...

  15. Titanium Heat Pipe Thermal Plane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Phase II program is to complete the development of the titanium heat pipe thermal plane and establish all necessary steps for production of...

  16. Additive Manufacturing of Heat Pipe Wicks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Wick properties are often the limiting factor in a heat pipe design. Current technology uses conventional sintering of metal powders, screen wick, or grooves to...

  17. Development of space reactor core heat pipes

    International Nuclear Information System (INIS)

    The Space Power Advance Reactor (SPAR) core heat pupes are being developed to transport 15 kW of power at 1400 K. A straight, 2-m-long, 15.9-mm-diam heat pipe was fabricated of low-carbon arc-cast molybdenum and filled with sodium as the working fluid. This nonconcentric, annular, screen-tube-wick pipe was tested successfully at 16.1 kW at 1310 K, at which point a boiling limit was encountered. Follow-on work has produced an as yet untested heat pipe which has its wick centered in the evaporator by spacer wires to alleviate the boiling limit problem. A dual artery wick heat pipe is being fabricated to further improve on the boiling limit and increase redundancy. Because the heat pipe must bend around the radiation shield of the SPAR reactor, a series of bending experiments was performed. Promising results were achieved by filling the pipe completely with sodium and bending at 3650 K

  18. Comparison of heat transfer efficiency between heat pipe and tube bundles heat exchanger

    OpenAIRE

    Wu Zhao-Chun; Zhu Xiang-Ping

    2015-01-01

    A comparison of heat transfer efficiency between the heat pipe and tube bundles heat exchanger is made based on heat transfer principle and the analysis of thermal characteristics. This paper argues that although heat pipe has the feature of high axial thermal conductivity, to those cases where this special function of heat transfer is unnecessary, heat pipe exchanger is not a high efficient heat exchanger when it is just used as a conventional heat exchang...

  19. Machined Titanium Heat-Pipe Wick Structure

    Science.gov (United States)

    Rosenfeld, John H.; Minnerly, Kenneth G.; Gernert, Nelson J.

    2009-01-01

    Wick structures fabricated by machining of titanium porous material are essential components of lightweight titanium/ water heat pipes of a type now being developed for operation at temperatures up to 530 K in high-radiation environments. In the fabrication of some prior heat pipes, wicks have been made by extruding axial grooves into aluminum unfortunately, titanium cannot be extruded. In the fabrication of some other prior heat pipes, wicks have been made by in-situ sintering of metal powders shaped by the use of forming mandrels that are subsequently removed, but in the specific application that gave rise to the present fabrication method, the required dimensions and shapes of the heat-pipe structures would make it very difficult if not impossible to remove the mandrels due to the length and the small diameter. In the present method, a wick is made from one or more sections that are fabricated separately and assembled outside the tube that constitutes the outer heat pipe wall. The starting wick material is a slab of porous titanium material. This material is machined in its original flat configuration to form axial grooves. In addition, interlocking features are machined at the mating ends of short wick sections that are to be assembled to make a full-length continuous wick structure. Once the sections have been thus assembled, the resulting full-length flat wick structure is rolled into a cylindrical shape and inserted in the heatpipe tube (see figure). This wick-structure fabrication method is not limited to titanium/water heat pipes: It could be extended to other heat pipe materials and working fluids in which the wicks could be made from materials that could be pre-formed into porous slabs.

  20. Application of Heat Pipes in Cold Region

    Science.gov (United States)

    Mochizuki, Masataka

    Recently, there has been put into practical use of heat pipes as space application, electronics cooling, and waste heat recovery. Especially, the low temperature heat pipe which can be used in below atmospheric temperature are also actively developed and applied in terrestrial field. These are based on utilization of natural energy in cold region. This paper is described about application of snow melting and deicing system on a road and roof, snow damage prevention system for electric pole branch wire, artificial permafrost storage system as a reverse utilization of cold atmosphere, and cryo-anchor applied in Alaska and northern Canada.

  1. Heat pipe reactors for space power applications

    Science.gov (United States)

    Koenig, D. R.; Ranken, W. A.; Salmi, E. W.

    1977-01-01

    A family of heat pipe reactors design concepts has been developed to provide heat to a variety of electrical conversion systems. Three power plants are described that span the power range 1-500 kWe and operate in the temperature range 1200-1700 K. The reactors are fast, compact, heat-pipe cooled, high-temperature nuclear reactors fueled with fully enriched refractory fuels, UC-ZrC or UO2. Each fuel element is cooled by an axially located molybdenum heat pipe containing either sodium or lithium vapor. Virtues of the reactor designs are the avoidance of single-point failure mechanisms, the relatively high operating temperature, and the expected long lifetimes of the fuel element components.

  2. Novel Wick Structures for Improved Heat Pipe Performance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Heat pipes are commonly used for transporting heat over relatively long distances with very low temperature drop. One of the limitations of heat pipes is the...

  3. Experimental Investigations of Vertical and Horizontal Heat Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Kim, Kyuung Mo; Jeong, Young Shin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    The interest in the application of heat pipes for heat transfer system is well known in industrial fields. Heat pipe uses the working fluid in containment as cylindrical shape tube. Vaporization occurs in evaporation section due to the heat input and vapor is transferred to condensation section. At the condensation area, the working fluid is condensed and immersed in the wick structure, which has highly porous media. The condensed working fluid returns to evaporator section by capillary wicking of wick structure. The driving force for working fluid is affected by capillary and gravitational force. The heat pipes for nuclear systems have been suggested as horizontal loop heat pipes for reactor core cooling system or vertical heat pipes for passive cooling for spent fuel. In the present research, preliminary tests of horizontal and vertical heat pipe were studied for its heat transfer performance. The main purpose of the research was the analysis of heat transfer behavior of heat pipe and the performance of heat transfer. The thermal performances of horizontal and vertical heat pipe were measured experimentally. Vertical heat pipe showed better performance compared to horizontal one, at high heat input region. The heat transfer coefficients of horizontal heat pipe were lower than vertical one because of gravitational force. Overall heat transfer coefficient of vertical heat pipes were enhanced to 28.5 % compared to the horizontal heat pipes. The horizontal heat pipes revealed high thermal resistance up to 54.3 % compared to vertical heat pipes. Therefore, vertical heat pipes analyzed better heat transfer performance than horizontal heat pipe.

  4. Experimental Investigations of Vertical and Horizontal Heat Pipes

    International Nuclear Information System (INIS)

    The interest in the application of heat pipes for heat transfer system is well known in industrial fields. Heat pipe uses the working fluid in containment as cylindrical shape tube. Vaporization occurs in evaporation section due to the heat input and vapor is transferred to condensation section. At the condensation area, the working fluid is condensed and immersed in the wick structure, which has highly porous media. The condensed working fluid returns to evaporator section by capillary wicking of wick structure. The driving force for working fluid is affected by capillary and gravitational force. The heat pipes for nuclear systems have been suggested as horizontal loop heat pipes for reactor core cooling system or vertical heat pipes for passive cooling for spent fuel. In the present research, preliminary tests of horizontal and vertical heat pipe were studied for its heat transfer performance. The main purpose of the research was the analysis of heat transfer behavior of heat pipe and the performance of heat transfer. The thermal performances of horizontal and vertical heat pipe were measured experimentally. Vertical heat pipe showed better performance compared to horizontal one, at high heat input region. The heat transfer coefficients of horizontal heat pipe were lower than vertical one because of gravitational force. Overall heat transfer coefficient of vertical heat pipes were enhanced to 28.5 % compared to the horizontal heat pipes. The horizontal heat pipes revealed high thermal resistance up to 54.3 % compared to vertical heat pipes. Therefore, vertical heat pipes analyzed better heat transfer performance than horizontal heat pipe

  5. Prototype testing of heat pipes for spacecraft heat control systems

    Energy Technology Data Exchange (ETDEWEB)

    Vasil' ev, L.L.; Gil, V.V.; Zharikov, N.A.; Zelenin, V.E.; Syvorotka, O.M.; Uvarov, E.I.

    1980-05-01

    Prototype testing of heat pipes for spacecraft heat control was done on board the Interkosmos-15 satellite launched on 19 June 1976. The purpose was to gather data for optimizing the design, namely the capillary structure and the selection of heat transfer agent, as well as to verify the soundness of manufacturing technologies and test procedures. Three heat pipes were tested, each 412 mm long with a 14 mm outside diameter. All had been made of an aluminum alloy. In two pipes the capillary structure consisted of 0.6 x 0.5 mm/sup 2/ rectangular channels running axially along the inside wall, in the third pipe a 1 mm thick tubular mesh of Kh18N10T steel wire running coaxially inside served as the capillary structure. The heat transfer agent was Freon-11 in one of the first two pipes and synthetic liquid ammonia in the other two pipes. The three pipes were mounted radially around a radiator as the hub, with the test conditions controllable by means of an electric heater coil along the evaporation zone of each pipe, resistance thermometers for the evaporation zone and for the condensation zone of each, and also an external cooling fan. The radial distribution of temperature drops along the pipes was measured and the thermal fluxes were calculated, these data being indicative of the performance under conditions of weightlessness over the 0 to 70/sup 0/C temperature range. The somewhat worse performance of the heat pipe with a tubular capillary mesh inside is attributable to formation of vapor bubbles which impede the mass transfer along such an artery.

  6. HEAT EXCHANGERS IN SEWAGE PIPES

    OpenAIRE

    Podobeková, Veronika; Peráčková, Jana

    2014-01-01

    The article discusses utilization of heat from waste water in sewage. During the year, temperature of water in sewage ranges between 10 °C and 20 °C and the heat from sewage could be used for heating, cooling and hot water preparation in building. The heat is extracted through a transfer surface area of the heat exchanger into the heat pump, which is able to utilize the low–potential energy. Different design and types of the heat exchangers in sewage are dealt with: heat exchangers embedded i...

  7. Visualization of working fluid flow in gravity assisted heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2015-05-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapor and vice versa help heat pipe to transport high heat flux. The article deal about construction and processes casing in heat pipe during operation. Experiment visualization of working fluid flow is performed with glass heat pipe filed with ethanol. The visualization of working fluid flow explains the phenomena as working fluid boiling, nucleation of bubbles, vapor flow, vapor condensation on the wall, vapor and condensate flow interaction, flow down condensate film thickness on the wall, occurred during the heat pipe operation.

  8. Visualization of working fluid flow in gravity assisted heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2015-01-01

    Full Text Available Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapor and vice versa help heat pipe to transport high heat flux. The article deal about construction and processes casing in heat pipe during operation. Experiment visualization of working fluid flow is performed with glass heat pipe filed with ethanol. The visualization of working fluid flow explains the phenomena as working fluid boiling, nucleation of bubbles, vapor flow, vapor condensation on the wall, vapor and condensate flow interaction, flow down condensate film thickness on the wall, occurred during the heat pipe operation.

  9. Variable conductance heat pipe technology. [research project resulting in heat pipe experiment on OAO-3 satellite

    Science.gov (United States)

    Anderson, W. T.; Edwards, D. K.; Eninger, J. E.; Marcus, B. D.

    1974-01-01

    A research and development program in variable conductance heat pipe technology is reported. The project involved: (1) theoretical and/or experimental studies in hydrostatics, (2) hydrodynamics, (3) heat transfer into and out of the pipe, (4) fluid selection, and (5) materials compatibility. The development, fabrication, and test of the space hardware resulted in a successful flight of the heat pipe experiment on the OAO-3 satellite. A summary of the program is provided and a guide to the location of publications on the project is included.

  10. Utilization of heat pipes for transfer heat from the flue gas into the heat transfer medium

    Directory of Open Access Journals (Sweden)

    Lenhard Richard

    2014-03-01

    Full Text Available The contribution is listed possible application of heat pipes in systems for obtaining heat from flue gas of small heat sources. It is also stated in the contribution design an experimental device on which to study the impact of fill (the quantity, type of load at various temperature parameters (temperature heating and cooling thermal power transferred to the heat pipe. Is listed measurement methodology using heat pipes designed experimental facility, measurement results and analysis of the results obtained.

  11. Development of Submersible Corrugated Pipe Sewage Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    BAI Li; SHI Yan; TAN Yu-fei

    2009-01-01

    Based on the characteristics of heat transfer for corrugated pipe,a method of calculating and de-sign on the submersible corrugated pipe sewage heat exchanger was put forward theoretically and experimental-ly.The actual movement parameters of air-conditioning system used in this heat exchanger were measured.The experimental result shows that the quantity of heat transfer of the corrugated pipe sewage heat exchanger can satisfy the building's load with the average coefficient of performance 4.55.At the same time.the quantity ot heat transfer of the corrugated pipe sewage heat exchanger was compared with that of the other nonmetallic sewage heat exchangers(i.e.,the plastic-Al pipe sewage heat exchanger and PP-R pipe sewage heat exchanger)experimentally.It is found out that the effect of heat transfer for submersible corrugated pipe sewage heat ex-changer is superior to those of the plastic-Al pipe and the PP-R pipe.The quantity of heat transfer per mile of corrugated pipe sewage heat exchanger is 5.2 times as much as that of the plastic-Al pipe,and it is 8.1 times as much as that of PP-R pipe.

  12. Hydrophobic liquid/gas separator for heat pipes

    Science.gov (United States)

    Marcus, B. D.

    1972-01-01

    Perforated nonwetting plug of material such as polytetrafluoroethylene is mounted in gas reservoir feed tube, preferably at end which extends into heat pipe condenser section, to prevent liquid from entering gas reservoir of passively controlled heat pipe.

  13. Research of heat exchange rate of the pulsating heat pipe

    OpenAIRE

    Kravets V. Yu.; Naumova A. M.; Vovkogon A. M.

    2010-01-01

    Given article presents experimental research of heat transfer characteristics of the pulsating heat pipe (PHP) which consists of seven coils with 1 mm inner diameter. Water was used as the heat carrier. PHP construction, measuring circuit and research technique are presented. It is shown that under PHP functioning there are two characteristic modes of operation, which can be distinguished by values of thermal resistance. PHP heat exchange features are disclosed.

  14. SEP BIMOD variable conductance heat pipes acceptance and characterization tests

    Science.gov (United States)

    Hemminger, J. A.

    1981-08-01

    A series of six heat pipes, similar in design to those flown on the Comunications Technology Satellite Hermes, for use in a prototype Solar Electric Propulsion BIMOD thrust module are evaluated. The results of acceptance and characterization tests performed on the heat pipe subassemble are reported. The performance of all the heat pipes met, or exceeded, design specifications.

  15. Heat pipe technology development for high temperature space radiator applications

    International Nuclear Information System (INIS)

    Technology requirements for heat pipe radiators, potentially among the lightest weight systems for space power applications, include flexible elements, and improved specific radiator performance (kg/kW). For these applications a flexible heat pipe capable of continuous operation through an angle of 1800 has been demonstrated. The effect of bend angle on the heat pipe temperature distribution is reviewed. An analysis of light weight membrane heat pipe radiators that use surface tension forces for fluid containment has been conducted. The design analysis of these lightweight heat pipes is described and a potential application in heat rejection systems for space nuclear power plants outlined

  16. HEAT PIPE RADIATIVE COOLING SYSTEMS FOR SPACE OPTICAL SENSORS

    OpenAIRE

    Baturkin, Volodya

    2007-01-01

    The heat pipes application in passive radiative cooling system is considered on the base of the analysis of thermal balance of consecutive thermal elements in system „Sensor - heat pipe – radiator-space“. This analysis defines the points of main thermal attention – heat leakage from mounting place, heat exchange with external radiative surrounding, minimization of thermal resistance of conductors and interaction between these factors. The secularities of heat pipe application as a heat tra...

  17. Graded-porosity heat-pipe wicks

    Science.gov (United States)

    Eninger, J. E.

    1976-01-01

    To maximize the capacity of a nonarterial heat pipe, a wick is considered whose porosity is allowed to vary axially along its length. At every axial location the porosity is set no lower than required to maintain the wick in a nearly saturated state under the maximum heat-transport rate. The result is a wick whose permeability is everywhere as high as possible. The differential equation that governs the optimum porosity variation is solved numerically between a condenser-end boundary condition that just prevents a liquid slug or puddle in the vapor spaces and an evaporator-end boundary condition that just prevents circumferential groove dry-up. Experimental performance measurements for an ammonia heat pipe are presented.

  18. Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    The main concern with the Fukushima accident was the failure of active and passive core cooling systems. The main function of existing passive decay heat removal systems is feeding additional coolant to the reactor core. Thus, an established emergency core cooling system (ECCS) cannot operate properly because of impossible depressurization under the station blackout (SBO) condition. Therefore, a new concept for passive decay heat removal system is required. In this study, an innovative hybrid control rod concept is considered for passive in-core decay heat removal that differs from the existing direct vessel injection core cooling system and passive auxiliary feedwater system (PAFS). The heat transfer between the evaporator and condenser sections occurs by phase change of the working fluid and capillary action induced by wick structures installed on the inner wall of the heat pipe. In this study, a hybrid control rod is developed to take the roles of both neutron absorption and heat removal by combining the functions of a heat pipe and control rod. Previous studies on enhancing the heat removal capacity of heat pipes used nanofluids, self-rewetting fluids, various wick structures and condensers. Many studies have examined the thermal performances of heat pipes using various nanofluids. They concluded that the enhanced thermal performance of the heat pipe using nanofluids is due to nanoparticle deposition on the wick structures. Thus, the wick structure of heat pipes has been modified by nanoparticle deposition to enhance the heat removal capacity. However, previous studies used relatively small heat pipes and narrow ranges of heat loads. The environment of a nuclear reactor is very specific, and the decay heat produced by fission products after shutdown is relatively large. Thus, this study tested a large-scale heat pipe over a wide range of power. The concept of a hybrid heat pipe for an advanced in-core decay heat removal system was introduced for complete

  19. Influence of structural design condensing part of NH3 heat pipe to heat transfer

    OpenAIRE

    Vantúch Martin; Malcho Milan

    2014-01-01

    The article describes influence design heat exchangers to efficiency condensation liquid ammonia in the gravitational heat pipe. Analyse adverse factors in the operation and flow of ammonia in heat pipe. Also describes heat transfer characteristics of heat pipe in low-potential geothermal heat transport simulations.

  20. Heat Pipe Solar Receiver for Oxygen Production of Lunar Regolith

    Science.gov (United States)

    Hartenstine, John R.; Anderson, William G.; Walker, Kara L.; Ellis, Michael C.

    2009-03-01

    A heat pipe solar receiver operating in the 1050° C range is proposed for use in the hydrogen reduction process for the extraction of oxygen from the lunar soil. The heat pipe solar receiver is designed to accept, isothermalize and transfer solar thermal energy to reactors for oxygen production. This increases the available area for heat transfer, and increases throughput and efficiency. The heat pipe uses sodium as the working fluid, and Haynes 230 as the heat pipe envelope material. Initial design requirements have been established for the heat pipe solar receiver design based on information from the NASA In-Situ Resource Utilization (ISRU) program. Multiple heat pipe solar receiver designs were evaluated based on thermal performance, temperature uniformity, and integration with the solar concentrator and the regolith reactor(s). Two designs were selected based on these criteria: an annular heat pipe contained within the regolith reactor and an annular heat pipe with a remote location for the reactor. Additional design concepts have been developed that would use a single concentrator with a single solar receiver to supply and regulate power to multiple reactors. These designs use variable conductance or pressure controlled heat pipes for passive power distribution management between reactors. Following the design study, a demonstration heat pipe solar receiver was fabricated and tested. Test results demonstrated near uniform temperature on the outer surface of the pipe, which will ultimately be in contact with the regolith reactor.

  1. Working fluid flow visualization in gravity heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-03-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. The article deal about gravity heat pipe construction and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm) and filled with water. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  2. Working fluid flow visualization in gravity heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2016-01-01

    Full Text Available Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. The article deal about gravity heat pipe construction and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm and filled with water. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  3. Numerical Modeling and Experimental Validation of Heat Pipe Solar Collector for Water Heating

    OpenAIRE

    Endalew, Abebe

    2012-01-01

    This work studies the performance of heat pipe solar collector for water heating. Experimental results are validated using numerical modeling. Homemade heat pipes with distilled water as a working fluid were used for experimental tests. Both natural and forced convective heat pipe condensing mechanisms are studied and their results are compared with conventional natural circulation solar water heating system. Cross flow and parallel flow heat exchanger were tested in forced type heat pipe con...

  4. Electrohydrodynamic heat pipe research. Final report

    International Nuclear Information System (INIS)

    Experimental and theoretical applications to electrohydrodynamic heat pipe (EHDHP) research are presented. Two problems in the research which are discussed are the prediction of the effective thermal conductance of an EHDHP with threaded grooves for fluid distribution to the evaporator of an EHDHP. Hydrodynamic equations are included along with a discussion of boundary conditions and burn-out conditions. A discussion of the theoretical and experimental results is presented. (U.S.)

  5. Computational model of miniature pulsating heat pipes.

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Mario J.; Givler, Richard C.

    2013-01-01

    The modeling work described herein represents Sandia National Laboratories (SNL) portion of a collaborative three-year project with Northrop Grumman Electronic Systems (NGES) and the University of Missouri to develop an advanced, thermal ground-plane (TGP), which is a device, of planar configuration, that delivers heat from a source to an ambient environment with high efficiency. Work at all three institutions was funded by DARPA/MTO; Sandia was funded under DARPA/MTO project number 015070924. This is the final report on this project for SNL. This report presents a numerical model of a pulsating heat pipe, a device employing a two phase (liquid and its vapor) working fluid confined in a closed loop channel etched/milled into a serpentine configuration in a solid metal plate. The device delivers heat from an evaporator (hot zone) to a condenser (cold zone). This new model includes key physical processes important to the operation of flat plate pulsating heat pipes (e.g. dynamic bubble nucleation, evaporation and condensation), together with conjugate heat transfer with the solid portion of the device. The model qualitatively and quantitatively predicts performance characteristics and metrics, which was demonstrated by favorable comparisons with experimental results on similar configurations. Application of the model also corroborated many previous performance observations with respect to key parameters such as heat load, fill ratio and orientation.

  6. High capacity heat pipe performance demonstration

    Science.gov (United States)

    1983-01-01

    A high capacity heat pipe which will operate in one-g and in zero-g is investigated. An artery configuration which is self-priming in one-g was emphasized. Two artery modifications were evolved as candidates to achieve one-g priming and will provide the very high performance: the four artery and the eight artery configurations. These were each evaluated analytically for performance and priming capability. The eight artery configuration was found to be inadequate from a performance standpoint. The four artery showed promise of working. A five-inch long priming element test article was fabricated using the four artery design. Plexiglas viewing windows were made on each end of the heat pipe to permit viewing of the priming activity. The five-inch primary element would not successfully prime in one-g. Difficulties on priming in one-g raised questions about zero-g priming. Therefore a small test element heat pipe for verifying that the proposed configuration will self-prime in zero-g was fabricated and delivered.

  7. Efficient adsorption refrigerators integrated with heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.Z. [Institute of Refrigeration and Cryogenics, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2008-03-15

    Several novel ideas to use heat pipes in adsorption water chiller or ice maker are presented in this paper. Experimental results have shown that the adsorption refrigerators are very efficient. The first example of such systems is a small scale silica gel-water adsorption water chiller with cooling power rated as 10 kW; the system could be powered by 60-100 C hot water, a cooling COP = 0.4 has been achieved when driven by 85 C hot water. This adsorption chiller has been used for solar powered air conditioner and also as the chiller for CCHP system. The second example is a silica gel-water adsorption room air conditioner powered by 80 C hot water. The system is very compact and is suggested for potential applications of micro CCHP system based on fuel cells. The system has a COP of over 0.3 and cooling power of about 1 kW. The third example is the use of split heat pipes to heat or cool the adsorber for making ice in fishing boats. The application of these technologies avoids the corrosion of adsorber at the heating phase by exhausted gases and at the cooling phase by seawater, and also has the advantage of high heat transfer performance. With such arrangement and careful considerations of the arrangement of wicks in heat pipes, and also the use of composite adsorbent (calcium chloride and activated carbon)-ammonia adsorption pair, the system test has shown the specific refrigeration power for more than 730 W/kg at -15 C. (author)

  8. Heat losses through pipe connections in hot water stores

    DEFF Research Database (Denmark)

    Andersen, Elsa; Fan, Jianhua; Furbo, Simon

    2007-01-01

    The heat loss from pipe connections at the top of hot water storage tanks with and without a heat trap is investigated theoretically and compared to similar experimental investigations. Computational Fluid Dynamics (CFD) is used for the theoretical analysis. The investigations show that the heat...... loss from an ideally insulated pipe connected to the top of a hot water tank is mainly due to a natural convection flow in the pipe, that the heat loss coefficient of pipes connected to the top of a hot water tank is high, and that a heat trap can reduce the heat loss coefficient significantly. Further...

  9. Distribution of heat flux by working fluid in loop heat pipe

    OpenAIRE

    Nemec Patrik; Malcho Milan

    2016-01-01

    The main topics of article are construction of loop heat pipe, thermal visualization of working fluid dynamics and research results interpretation. The work deals about heat flux transport by working fluid in loop heat pipe from evaporator to condenser evolution. The result of the work give us how the hydrodynamic and thermal processes which take place inside the loop of heat pipe affect on the overall heat transport by loop heat pipe at start-up and during operation.

  10. Distribution of heat flux by working fluid in loop heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2016-01-01

    Full Text Available The main topics of article are construction of loop heat pipe, thermal visualization of working fluid dynamics and research results interpretation. The work deals about heat flux transport by working fluid in loop heat pipe from evaporator to condenser evolution. The result of the work give us how the hydrodynamic and thermal processes which take place inside the loop of heat pipe affect on the overall heat transport by loop heat pipe at start-up and during operation.

  11. Distribution of heat flux by working fluid in loop heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-03-01

    The main topics of article are construction of loop heat pipe, thermal visualization of working fluid dynamics and research results interpretation. The work deals about heat flux transport by working fluid in loop heat pipe from evaporator to condenser evolution. The result of the work give us how the hydrodynamic and thermal processes which take place inside the loop of heat pipe affect on the overall heat transport by loop heat pipe at start-up and during operation.

  12. Simplification of simulation processes at gravity heat pipes

    OpenAIRE

    Hrabovský Peter; Papučík Štefan; Lenhard Richard

    2016-01-01

    Water heating by heat pipe is currently the object examined on the use in sphere of recovering heat from technological processes. The heat pipe is the device for water heating that provides us a very effective way of transferring heat from the heat source (combustion) to the place of consumption (water). For the draft proposal of such equipment is produced under the required conditions mathematical model of ANSYS that verifies the actual measurements the experiments. The paper deals with the ...

  13. Solid0Core Heat-Pipe Nuclear Batterly Type Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ehud Greenspan

    2008-09-30

    This project was devoted to a preliminary assessment of the feasibility of designing an Encapsulated Nuclear Heat Source (ENHS) reactor to have a solid core from which heat is removed by liquid-metal heat pipes (HP).

  14. Simplification of simulation processes at gravity heat pipes

    Science.gov (United States)

    Hrabovský, Peter; Papučík, Štefan; Lenhard, Richard

    2016-03-01

    Water heating by heat pipe is currently the object examined on the use in sphere of recovering heat from technological processes. The heat pipe is the device for water heating that provides us a very effective way of transferring heat from the heat source (combustion) to the place of consumption (water). For the draft proposal of such equipment is produced under the required conditions mathematical model of ANSYS that verifies the actual measurements the experiments. The paper deals with the possibility of simulations of heat pipes in the process of heat transport and apposite simplification of the simulation process by defining apposite the substitutes of the solid materials with its own thermal properties that ensure a similar heat transport as a heat transfer medium in the heat pipe.

  15. Experimental Analysis of Heat Transfer Behavior inside Heat Pipe Integrated with Cooling Plates

    OpenAIRE

    Chen-Ching Ting; Chien-Chih Chen

    2011-01-01

    This work used experimental methods to study heat transfer behavior inside a heat pipe and found that heat transfer behavior inside the heat pipe was changed due to its integration with cooling plates. This change caused the heat pipe to have copper-like heat transfer behavior. Experimental performances first built a CPU simulator with maximum heat power 300 W in accordance with the ASTM standard as heat source and measured temperature distribution by using infrared thermography and thermocou...

  16. Research and Development on Heat Pipes and Related Thermal Engineering Technologies in Japan

    OpenAIRE

    Oshima, Koichi

    1989-01-01

    Five advanced heat pipe systems utilizing phase changing heat transfer concept are introduced, which are; a separate type heat pipe heat exchanger, a heat pipe turbine, micro heat pipes, a thermocapillary loop system and mass-produced tubes with inner fin. Inside of these heat pipes, contrary to the conventional heat transfer tubes, evaporation and condensation processes are heavily influenced by the surface tension effect. This effect is also dominant in the heat pipes operating under micro-...

  17. Heat pipe efficiency enhancement with refrigerant-nanoparticles mixtures

    International Nuclear Information System (INIS)

    In the present study, the enhancement of heat pipe efficiency with refrigerant-nanoparticles mixtures is presented. The heat pipe is fabricated from the straight copper tube with the outer diameter and length of 15, 600 mm, respectively. The refrigerant (R11) is used as a base working fluid while the nanoparticles used in the present study are the titanium nanoparticles with diameter of 21 nm. The mixtures of refrigerant and nanoparticles are prepared using an ultrasonic homogenizer. Effects of the charge amount of working fluid, heat pipe tilt angle on the efficiency of heat pipe are considered. For the used pure refrigerant as working fluid, the heat pipe at the tilt angle of 60 deg., working fluid charge amount of 50% gives the highest efficiency. At the optimum condition for the pure refrigerant, the heat pipe with 0.1% nanoparticles concentration gives efficiency 1.40 times higher than that with pure refrigerant

  18. Heat pipe efficiency enhancement with refrigerant-nanoparticles mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Naphon, Paisarn; Thongkum, Dithapong; Assadamongkol, Pichai [Thermo-Fluid and Heat Transfer Enhancement Laboratory (TFHT), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot University, 63 Rangsit-Nakhornnayok Rd., Ongkharak, Nakhorn-Nayok 26120 (Thailand)

    2009-03-15

    In the present study, the enhancement of heat pipe efficiency with refrigerant-nanoparticles mixtures is presented. The heat pipe is fabricated from the straight copper tube with the outer diameter and length of 15, 600 mm, respectively. The refrigerant (R11) is used as a base working fluid while the nanoparticles used in the present study are the titanium nanoparticles with diameter of 21 nm. The mixtures of refrigerant and nanoparticles are prepared using an ultrasonic homogenizer. Effects of the charge amount of working fluid, heat pipe tilt angle on the efficiency of heat pipe are considered. For the used pure refrigerant as working fluid, the heat pipe at the tilt angle of 60 , working fluid charge amount of 50% gives the highest efficiency. At the optimum condition for the pure refrigerant, the heat pipe with 0.1% nanoparticles concentration gives efficiency 1.40 times higher than that with pure refrigerant. (author)

  19. Review of liquid metal heat pipe work at Los Alamos

    International Nuclear Information System (INIS)

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by a reference section citing sources where these works may be found. 53 refs

  20. Influence of the ambient temperature during heat pipe manufacturing on its function and heat transport ability

    OpenAIRE

    Čaja A.; Nemec P.; Malcho M.

    2014-01-01

    Heat pipe is heat transfer device working at a minimum temperature difference of evaporator and condenser. Operating temperature of the heat pipe determine by properties of the working substance and pressure achieved during production. The contribution is focused on the determining the effect of the initial surrounding temperature where the heat pipe is manufactured and on the obtaining performance characteristics produced heat pipes in dependence of manufacturing temperature. Generally hold,...

  1. Entropy generation analysis of cylindrical heat pipe using nanofluid

    Energy Technology Data Exchange (ETDEWEB)

    Ghanbarpour, Morteza, E-mail: morteza.ghanbarpour@energy.kth.se; Khodabandeh, Rahmatollah

    2015-06-20

    Highlights: • Entropy generation of heat pipe with nanofluid has been studied. • Nanofluid has significant effect on heat pipe performance. • Entropy generation in heat pipe decreases when nanofluids are used as working fluids. - Abstract: Thermal performance of cylindrical heat pipe with nanofluid is studied based on the laws of thermodynamics. The objective of the present work is to investigate nanofluids effect on different sources of entropy generation in heat pipe caused by heat transfer between hot and cold reservoirs and also frictional losses and pressure drop in the liquid and vapor flow along heat pipe. An analytical study was performed to formulate all sources of entropy generation and the predicted results are compared with experimental ones. Cylindrical miniature grooved heat pipes of 250 mm length and 6.35 mm outer diameter were fabricated and tested with distilled water and water based TiO{sub 2} and Al{sub 2}O{sub 3} nanofluids at different concentrations as working fluids. Analytical and experimental results revealed that the entropy generation in heat pipes decreases when nanofluids are used as working fluids instead of basefluid which results in improved thermal performance of the heat pipes with nanofluids.

  2. An investigation of electrohydrodynamic heat pipes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Loehrke, R.I.

    1977-03-01

    The principles of electrohydrodynamic heat pipe operation are discussed, and evaporator conductance experiments are described. A heat pipe was designed in which grooved and ungrooved evaporator surfaces could be interchanged to evaluate the necessity of capillary grooves. Optimum electrode spacing was also studied. Finally, heat convection in evaporating thin films is considered.

  3. Pressure Controlled Heat Pipe for Precise Temperature Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research project will develop Pressure Controlled Heat Pipes (PCHPs) for precise temperature control (milli-Kelvin level). Several...

  4. Method for the positioning of pipes in a heat exchanger

    International Nuclear Information System (INIS)

    The invention relates to a method for positioning pipes in a heat exchanger. The grating that supports the pipes of the heat exchanger may be equipped with projections in the passages that also support the pipes. Such projections may, however, obstruct the positioning of the pipes in the grating. The purpose of the invention is to bypass this problem by applying receding projections that move outward when a wedge is put in the grating and thereupon turned round in such a way that the pipes can freely be positioned. Thereupon, the wedge is turned back and the projections will resume their positions. (Auth.)

  5. RIBBED DOUBLE PIPE HEAT EXCHANGER: ANALYTICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    HUSSAIN H. AL-KAYIEM

    2011-02-01

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

  6. An Overview of Long Duration Sodium Heat Pipe Tests

    Science.gov (United States)

    Rosenfeld, John H.; Ernst, Donald M.; Lindemuth, James E.; Sanzi, James L.; Geng, Steven M.; Zuo, Jon

    2004-02-01

    High temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, and Stirling cycle heat sources; with the resurgence of space nuclear power, additional applications include reactor heat removal elements and radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly long-term materials compatibility is being evaluated through the use of high temperature life test heat pipes. Thermacore, Inc. has carried out several sodium heat pipe life tests to establish long term operating reliability. Four sodium heat pipes have recently demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A 316L stainless steel heat pipe with a sintered porous nickel wick structure and an integral brazed cartridge heater has successfully operated at 650C to 700C for over 115,000 hours without signs of failure. A second 316L stainless steel heat pipe with a specially-designed Inconel 601 rupture disk and a sintered nickel powder wick has demonstrated over 83,000 hours at 600C to 650C with similar success. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 41,000 hours at nearly 700C. A hybrid (i.e. gas-fired and solar) heat pipe with a Haynes 230 envelope and a sintered porous nickel wick structure was operated for about 20,000 hours at nearly 700C without signs of degradation. These life test results collectively have demonstrated the potential for high temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability. Detailed design specifications, operating history, and test results are described for each of these sodium heat pipes. Lessons learned and future life

  7. An Overview of Long Duration Sodium Heat Pipe Tests

    Science.gov (United States)

    Rosenfeld, John H.; Ernst, Donald M.; Lindemuth, James E.; Sanzi, James L.; Geng, Steven M.; Zuo, Jon

    2004-01-01

    High temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, and Stirling cycle heat sources; with the resurgence of space nuclear power, additional applications include reactor heat removal elements and radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly long-term materials compatibility is being evaluated through the use of high temperature life test heat pipes. Thermacore International, Inc., has carried out several sodium heat pipe life tests to establish long term operating reliability. Four sodium heat pipes have recently demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A 3l6L stainless steel heat pipe with a sintered porous nickel wick structure and an integral brazed cartridge heater has successfully operated at 650 to 700 C for over 115,000 hours without signs of failure. A second 3l6L stainless steel heat pipe with a specially-designed Inconel 60 I rupture disk and a sintered nickel powder wick has demonstrated over 83,000 hours at 600 to 650 C with similar success. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 41 ,000 hours at nearly 700 0c. A hybrid (i.e. gas-fired and solar) heat pipe with a Haynes 230 envelope and a sintered porous nickel wick structure was operated for about 20,000 hours at nearly 700 C without signs of degradation. These life test results collectively have demonstrated the potential for high temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability, Detailed design specifications, operating hi story, and test results are described for each of these sodium heat pipes. Lessons

  8. A parametric study of porous wick in heat pipe

    International Nuclear Information System (INIS)

    A Heat pipe which acquires a power by a capillary force has been used to mainly cool heat sources in satellites for long times. Among types of heat pipes, Loop Heat Pipe, Capillary Pumped Loop have usually used porous wicks such as sintered powder and fine wick to circulate a working fluid. These porous wicks have many design variables which affect thermal phenomena such as a capillary driven force, disjoining pressure, drying limitation, boiling limitation, etc. Additionally, Fins connecting an evaporator surface with a porous wick also after thermal characteristics of heat pipe. Especially, a vapor blanket thickness being main variables to decide a wick thickness has to do with fin sizes. Accordingly, understanding design variables' characteristics of porous wicks and fins is important to execute design optimization of heat pipe. In this paper, analytical methods and results will be discussed in terms of parametric study

  9. A parametric study of porous wick in heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Jin; Jun, Sang Ook; Jung, Ji Hun; Kim, Jeong Hwa; Lee, Dong Ho [Seoul National Univ., Seoul (Korea, Republic of)

    2008-07-01

    A Heat pipe which acquires a power by a capillary force has been used to mainly cool heat sources in satellites for long times. Among types of heat pipes, Loop Heat Pipe, Capillary Pumped Loop have usually used porous wicks such as sintered powder and fine wick to circulate a working fluid. These porous wicks have many design variables which affect thermal phenomena such as a capillary driven force, disjoining pressure, drying limitation, boiling limitation, etc. Additionally, Fins connecting an evaporator surface with a porous wick also after thermal characteristics of heat pipe. Especially, a vapor blanket thickness being main variables to decide a wick thickness has to do with fin sizes. Accordingly, understanding design variables' characteristics of porous wicks and fins is important to execute design optimization of heat pipe. In this paper, analytical methods and results will be discussed in terms of parametric study.

  10. Evaluating Program about Performance of Circular Sodium Heat Pipe

    International Nuclear Information System (INIS)

    The superior heat transfer capability, structural simplicity, relatively inexpensive, insensitivity to the gravitational field, silence and reliability are some of its outstanding features. We study about heat transfer equation of heat pipe and program predicting performance which is considering geometrical shape of heat pipe by the related heat transfer equation of heat pipe. The operating temperature is 450 .deg. C - 950 .deg. C, working fluid is sodium, material for container is stainless steel, and type of wick is sintered metal. As a result of evaluating program about performance of circular sodium heat pipe based on MATLAB code, express correlation between radius and LHR, correlation between heat transfer length and LHR, correlation between wick and LHR, correlation between operating temperature and LHR. Generally radius values of heat pipe are proportional to LHR because of increase of mass flow which is main factor of heat flow. Heat transfer length values of heat pipe are inversely proportional to LHR and slightly inversely proportional to heat rate. Pore size is proportional to LHR. Although increase of pore size decrease capillary pressure, decrease more pressure drop in liquid phase. As a result, mass flow and heat rate are increase. But we have to do additional consideration about pore size and voidage in the aspect of safety and production technique

  11. Heat pipe gas combustion system endurance test for Stirling engine

    Science.gov (United States)

    Mahrle, P.

    1990-12-01

    Stirling Thermal Motors, Inc. has been developing a general purpose Heat Pipe Gas Combustion (HPGC) system suitable for use with the STM4-120 Stirling engine. The HPGC consists of a parallel plate recuperative preheater, a finned heat pipe evaporator, and a film-cooled gas combustor. The principal component is the heat pipe evaporator which collects and distributes the liquid sodium over the heat transfer surfaces. The liquid sodium evaporates and flows to the condensers where it delivers its latent heat. Given here are the test results of the endurance tests run on a Gas Fired Stirling Engine (GFSE).

  12. Thermal performance of heat pipe with suspended nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, K.N. [Gurgaon College of Engineering, Gurgaon (India); Solomon, A.B.; Pillai, B.C.; Ruba Singh, B.J.; Saravana Kumar, S. [Karunya University, Centre for Research in Thermal Management, Coimbatore (India)

    2012-11-15

    Nanofluids are employed as the working medium for a conventional cylindrical heat pipe. A cylindrical copper heat pipe of 19.5 mm outer diameter and 400 mm length was fabricated and tested with two different working fluids. The working fluids used in this study are DI-water and Nano-particles suspension (mixture of copper nano particle and DI-water). The overall heat transfer coefficient of the heat pipe was calculated based on the lumped thermal resistance network and compared with the heat transfer coefficient of base fluid filled heat pipe. There is a quantitative improvement in the heat transfer coefficient using nano-particles suspension as the working medium. A heat transfer correlation was also developed based on multiple regression least square method and the results were compared with that obtained by the experiment. (orig.)

  13. Thermal performance of heat pipe with suspended nano-particles

    Science.gov (United States)

    Shukla, K. N.; Solomon, A. Brusly; Pillai, B. C.; Ruba Singh, B. Jacob; Saravana Kumar, S.

    2012-11-01

    Nanofluids are employed as the working medium for a conventional cylindrical heat pipe. A cylindrical copper heat pipe of 19.5 mm outer diameter and 400 mm length was fabricated and tested with two different working fluids. The working fluids used in this study are DI-water and Nano-particles suspension (mixture of copper nano particle and DI-water). The overall heat transfer coefficient of the heat pipe was calculated based on the lumped thermal resistance network and compared with the heat transfer coefficient of base fluid filled heat pipe. There is a quantitative improvement in the heat transfer coefficient using nano-particles suspension as the working medium. A heat transfer correlation was also developed based on multiple regression least square method and the results were compared with that obtained by the experiment.

  14. Influence of Different Parameters on Heat Pipe Performance

    OpenAIRE

    Sharmishtha Singh Hada; Prof. P. K. Jain

    2015-01-01

    In electrical and electronic industry due to miniaturization of electronic components heat density increases which, in turns increases the heat flux inside it. Scientist and many researchers are doing lot of work in this field for thermal management of devices. Heat pipe is a device that is used in electronic circuit (micro and power electronics), spacecraft & electrical components for cooling purpose. It is based on the principle of evaporation and condensation of working fluid. Heat pipe...

  15. EXPERIMENTAL STUDY ON SEMI-OPEN HEAT PIPES AND ITS APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Semi-open heat pipes were studied experimentally in this work. A new kind of semi-open heat pipe with fluid swirl backflow was developed on the basis of the traditional semi-open heat pipe. Heat transfer characteristics during operation and start-up of closed heat pipe、traditional semi-open heat pipe and swirl flow semi-open heat pipe were investigated. The swirl orifice' s backflow effect on enhancing the working limitation was obtained. Heat exchangers or waste heat boilers made of swirl flow semi-open heat pipes and semi-open heat pipes have been successfully used in high or variable gas temperature engineering applications.

  16. THERMION: Verification of a Thermionic Heat Pipe in Microgravity

    OpenAIRE

    Powell, George; Redd, Frank

    1991-01-01

    The Idaho National Engineering Laboratory (lNEL) is conducting intensive research in the design and development of a small excore heat-pipe-thermionic space nuclear reactor power system (SEHPTR). The SEHPTR spacecraft will be able to supply 40 kW of power in any given orbit. Figure 1-1 shows a conceptual diagram of the SEHPTR spacecraft. The key components in this reactor are the thermionic heat pipes. The heat pipes have two major functions: first, to convert heat energy into electrical ener...

  17. Heat pipe design and technology a practical approach

    CERN Document Server

    Zohuri, Bahman

    2011-01-01

    With its unique ability to transfer heat over large distances with minimal loss, the heat pipe has emerged as a proven environmentally friendly, energy-saving solution for passive thermal control. However, until recently, the high cost and complex construction use of these marvelous mechanisms has generally limited their use to space technology. Written by a former senior chief scientist at Lockheed who has also worked for Westinghouse and the U.S Air Force, Heat Pipe Design and Technology: A Practical Approach provides a practical study of modern heat pipe engineering in nuclear and solar ene

  18. Heat pipe design handbook, part 2. [digital computer code specifications

    Science.gov (United States)

    Skrabek, E. A.

    1972-01-01

    The utilization of a digital computer code for heat pipe analysis and design (HPAD) is described which calculates the steady state hydrodynamic heat transport capability of a heat pipe with a particular wick configuration, the working fluid being a function of wick cross-sectional area. Heat load, orientation, operating temperature, and heat pipe geometry are specified. Both one 'g' and zero 'g' environments are considered, and, at the user's option, the code will also perform a weight analysis and will calculate heat pipe temperature drops. The central porous slab, circumferential porous wick, arterial wick, annular wick, and axial rectangular grooves are the wick configurations which HPAD has the capability of analyzing. For Vol. 1, see N74-22569.

  19. Heat-pipe transient model for space applications

    Science.gov (United States)

    Tournier, Jean-Michel; El-Genk, Mohamed S.; Juhasz, Albert J.

    1991-01-01

    A two-dimensional model is developed for simulating heat pipes transient performance following changes in the input/rejection power or in the evaporator/condenser temperatures. The model employs the complete form of governing equations and momentum and energy jump conditions at the liquid-vapor interface. Although the model is capable of handling both cylindrical and rectangular geometries, the results reported are for a circular heat pipe with liquid lithium as the working fluid. The model incorporates a variety of other working fluids, such as water, ammonia, potassium, sodium, and mercury, and offers combinations of isothermal, isoflux, convective and radiative heating/cooling conditions in the evaporator and condenser regions of the heat pipe. Results presented are for lithium heat pipes with exponential heating of the evaporator and isothermal cooling of the condenser.

  20. Analysis and application of variable conductance heat pipe air preheater

    Science.gov (United States)

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

    2011-09-01

    The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature transfer matrix was obtained for the air preheater that comprises several discrete heat transfer units with same or different heat transfer surface area in a parallel or counter flow mode. By using the temperature transfer matrix, the outlet fluid temperatures could be easily calculated for a given air preheater and inlet fluid temperatures. The active length of condenser in a variable conductance heat pipe is determined according to the flat interface model. With the same initial conditions, the comparisons between variable conductance heat-pipe air preheater and regular heat pipe air preheater has been analyzed and tested in terms of heat pipe wall temperature, heat transfer surface area and outlet fluid temperatures. Based on the real industrial applications, it has been confirmed that the variable conductance heat pipe air preheater has excellent performance of anti-corrosion and anti-ash-deposition especially at the variable working condition and the sulfur coal (5%-6% mass fraction of sulfur) condition.

  1. Experimental investigation on Heat Transfer Performance of Annular Flow Path Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Kim, Kyung Mo; Jeong, Yeong Shin; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    Mochizuki et al. was suggested the passive cooling system to spent nuclear fuel pool. Detail analysis of various heat pipe design cases was studied to determine the heat pipes cooling performance. Wang et al. suggested the concept PRHRS of MSR using sodium heat pipes, and the transient performance of high temperature sodium heat pipe was numerically simulated in the case of MSR accident. The meltdown at the Fukushima Daiichi nuclear power plants alarmed to the dangers of station blackout (SBO) accident. After the SBO accident, passive decay heat removal systems have been investigated to prevent the severe accidents. Mochizuki et al. suggested the heat pipes cooling system using loop heat pipes for decay heat removal cooling and analysis of heat pipe thermal resistance for boiling water reactor (BWR). The decay heat removal systems for pressurized water reactor (PWR) were suggested using natural convection mechanisms and modification of PWR design. Our group suggested the concept of a hybrid heat pipe with control rod as Passive IN-core Cooling System (PINCs) for decay heat removal for advanced nuclear power plant. Hybrid heat pipe is the combination of the heat pipe and control rod. In the present research, the main objective is to investigate the effect of the inner structure to the heat transfer performance of heat pipe containing neutron absorber material, B{sub 4}C. The main objective is to investigate the effect of the inner structure in heat pipe to the heat transfer performance with annular flow path. ABS pellet was used instead of B{sub 4}C pellet as cylindrical structures. The thermal performances of each heat pipes were measured experimentally. Among them, concentric heat pipe showed the best performance compared with others. 1. Annular evaporation section heat pipe and annular flow path heat pipe showed heat transfer degradation. 2. AHP also had annular vapor space and contact cooling surface per unit volume of vapor was increased. Heat transfer

  2. Bottom ash from fluidising bed boilers as filler material in district heating pipe culverts. Chemical and geotechnical characterisation; Pannsand som kringfyllnadsmaterial foer fjaerrvaermeroergravar. Kemisk och geoteknisk karaktaerisering av fluidbaeddsand

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Roger; Rogbeck, Jan; Suer, Pascal

    2004-01-01

    Bottom ashes from fluid bed boilers have been characterised, both geotechnically and chemically, in order to investigate the possibility to use them as filler material in district heating pipe culverts. Bottom ashes from both biofuel boilers and waste boilers are represented in this project. The companies which ashes have been characterised are Sundsvall Energi AB, Sydkraft OestVaerme AB, Sydkraft MaelarVaerme AB, Eskilstuna Miljoe och Energi, Stora Enso Fors, Soederenergi and Fortum Vaerme. A total of ten ashes have been analysed where three ashes originates from Sundsvall Energi AB, two from Sydkraft OestVaerme AB and one from the each of the remaining companies. The chemical analyses have been performed both on fresh ashes and on ashes aged for three months. The geotechnical analyses performed are grain size distribution, packing abilities and permeability. Chemical analyses performed are total content, available content, leaching tests (leaching both by shaking method and column procedure) and organic analyses (PAH, EOX, TOC, dioxin and fenol). The geotechnical analyses show that the ashes fulfils the demands that are put on the filler material used in district heating pipe culverts. When using the ashes in applications, light compaction should be performed due to the risk of crushing the material which may cause an increased amount of fine material. The leachability of fine material is larger than for coarse material. The ashes are relatively insensitive to precipitation. Bio fuel based bottom ashes have a lower content of environmental affecting substances than waste fuel based ashes. This is also shown in the leaching analyses. The leaching water from fresh ashes contains a higher concentration of leachable components than aged ashes. When aged the pH in the ashes decreases due to carbon uptake and hydration and this makes metals as Pb, Cu, Cr and Zn less mobile. On the other hand, an increase in leachability of Sb, Mo and SO{sub 4} is shown when the ashes

  3. Commercial high efficiency dehumidification systems using heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    An improved heat pipe design using separately connected two-section one-way flow heat pipes with internal microgrooves instead of wicks is described. This design is now commercially available for use to increase the dehumidification capacity of air conditioning systems. The design also includes a method of introducing fresh air into buildings while recovering heat and controlling the humidity of the incoming air. Included are applications and case studies, load calculations and technical data, and installation, operation, and maintenance information.

  4. Heat pipes and solid sorption transformations fundamentals and practical applications

    CERN Document Server

    Vasiliev, LL

    2013-01-01

    Developing clean energy and utilizing waste energy has become increasingly vital. Research targeting the advancement of thermally powered adsorption cooling technologies has progressed in the past few decades, and the awareness of fuel cells and thermally activated (heat pipe heat exchangers) adsorption systems using natural refrigerants and/or alternatives to hydrofluorocarbon-based refrigerants is becoming ever more important. Heat Pipes and Solid Sorption Transformations: Fundamentals and Practical Applications concentrates on state-of-the-art adsorption research and technologies for releva

  5. Space qualification of high capacity grooved heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, M.; Mullender, B.; Druart, J. [SABCA, Societe Anomyme Belgel de Construction Aeronautique (Belgium); Supper, W.; Beddows, A. [ESTEC-The (Netherlands)

    1996-12-31

    Based on the thermal requirements of the future telecommunication satellites, the development of a High Capacity Grooved Heat Pipe (HPG), was contracted by ESA to SABCA leading to an aluminium extruded heat pipe (outer diameter of 25 mm) based on a multi re-entrant grooves design. After an intensive acceptance test campaign whose results showed a good confidence in the design and the fulfillment of the required specifications of heat transport and on tilt capability (experimental maximum heat transport capability of 1500 Watt metres for a vapour temperature of 20 deg C), similar heat pipes have been developed with various outer diameters (11 mm, 15 mm and 20 mm) and with various shapes (circular outer shapes, integrated saddles). Several of these heat pipes were tested during two parabolic flight campaigns, by varying the heat loads during the micro-gravity periods. This HGP heat pipe family is now being submitted to a space qualification program according to ESA standards (ESA PSS-49), both in straight and bent configuration. Within this qualification, the heat pipes are submitted to an extended test campaign including environmental (random/sinus vibration, constant acceleration) and thermal tests (thermal performance, thermal cycle, thermal soak, ageing). (authors) 9 refs.

  6. An investigation of heat pipe meniscus heat transfer

    Science.gov (United States)

    Saaski, E. W.; Franklin, J. L.; Mccreight, C. R.

    1978-01-01

    The use of grooved evaporator surfaces in heat pipes has increased in popularity in the past few years primarily due to the reproducibility achievable with grooved walls and the relatively low costs of the threading or extrusion processes involved in their production. The present study combines both analyses and experiments on square groove geometries, with special emphasis on overcoming the limitations of earlier analyses with finite-difference methods and groove-fillet hydrodynamic simplifications. The groove fillet, which has in previous analyses been assumed constant in radius of curvature, is permitted to change in thickness and curvature consistent with hydrodynamics and heat loss from the groove. A model is developed for accurate determination of the effect of constriction resistance on groove performance. The grooved-surface tests to be conducted are briefly described which will provide data under closely controlled operation to allow comparison and verification of the analyses.

  7. A thermosyphon heat pipe cooler for high power LEDs cooling

    Science.gov (United States)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  8. Developments of heat pipes for new industrial technologies

    International Nuclear Information System (INIS)

    Short historical review of investigations and developments of heat pipes in the Institute for Physics and Power Engineering after A.I. Lejpunskij is presented. The first calculational and experimental investigations began in 1967. In this period physical and technological basics are developed. The institute is the leader in the field of liquid metal heat pipe technologies. Practical mastering of temperature range from cryogenic up to 1500 deg C permitted to begin production of experimental and demonstration models of heat pipes as well as their short-run production for various branches of industry

  9. Transient Behaviour of a Heat Pipe with Extracapillary Circulation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Heat pipe devices, for their typical working mode, are particularly suitable for zero gravity applications, and have also been considered for applications in space satellites with nuclear generators because of the absence of active systems for the coolant circulation. The present work reports the results of experimental tests carried out on a heat pipe facility designed to investigate the thermal-hydraulic performance of a water heat pipe. The device layout, configuration and geometry, simulate a heat pipe working mode utilizable in space applications under zero gravity conditions. The evaporating section, completely lined (covered) with wicks (sintered stainless steel), and nearly plane shaped, is housed in a cylindrical container. The obtained results show that the system can approach steady-state conditions, at a pressure of 4 bar and with a heat flux transferred of about 150 W/cm2, supporting an electric power step of about 1.8 Kw.

  10. Survey of heat-pipe application under nuclear environment

    International Nuclear Information System (INIS)

    Heat pipes today are employed in a wide variety of special heat transfer applications including nuclear reactor. In this nuclear technology area in Japan, A headway speed of the heat pipe application technique is not so high because of safety confirmation and investigation under each developing step. Especially, the outline of space craft is a tendency to increase the size. Therefore, the power supply is also tendency to increase the outlet power and keep the long life. Under SP-100 project, the development of nuclear power supply system which power is 1400 - 1600 KW thermal and 100 KW electric power is steadily in progress. Many heat pipes are adopted for thermionic conversion and coolant system in order to construct more safety and light weight system for the project. This paper describes the survey of the heat pipe applications under the present and future condition for nuclear environment. (author)

  11. Working Fluids for Increasing Capacities of Heat Pipes

    Science.gov (United States)

    Chao, David F.; Zhang, Nengli

    2004-01-01

    A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

  12. Influence of the ambient temperature during heat pipe manufacturing on its function and heat transport ability

    Directory of Open Access Journals (Sweden)

    Čaja A.

    2014-03-01

    Full Text Available Heat pipe is heat transfer device working at a minimum temperature difference of evaporator and condenser. Operating temperature of the heat pipe determine by properties of the working substance and pressure achieved during production. The contribution is focused on the determining the effect of the initial surrounding temperature where the heat pipe is manufactured and on the obtaining performance characteristics produced heat pipes in dependence of manufacturing temperature. Generally hold, that the boiling point of the working liquid decrease with decreasing ambient pressure. Based on this can be suppose that producing of lower ambient temperature during heat pipe manufacturing, will create the lower pressure, the boiling point of the working fluid will lower too and the heat pipe should be better performance characteristics.

  13. Design of Refractory Metal Life Test Heat Pipe and Calorimeter

    Science.gov (United States)

    Martin, J. J.; Reid, R. S.; Bragg-Sitton, S. M.

    2010-01-01

    Heat pipe life tests have seldom been conducted on a systematic basis. Typically, one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. Results are often reported describing the wall material, working fluid, test temperature, test duration, and occasionally the nature of any failure. Important information such as design details, processing procedures, material assay, power throughput, and radial power density are usually not mentioned. We propose to develop methods to generate carefully controlled data that conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. The test approach detailed in this Technical Publication will use 16 Mo-44.5%Re alloy/sodium heat pipe units that have an approximate12-in length and 5/8-in diameter. Two specific test series have been identified: (1) Long-term corrosion rates based on ASTM-G-68-80 (G-series) and (2) corrosion trends in a cross-correlation sequence at various temperatures and mass fluences based on a Fisher multifactor design (F-series). Evaluation of the heat pipe hardware will be performed in test chambers purged with an inert purified gas (helium or helium/argon mixture) at low pressure (10-100 torr) to provide thermal coupling between the heat pipe condenser and calorimeter. The final pressure will be selected to minimize the potential for voltage breakdown between the heat pipe and radio frequency (RF) induction coil (RF heating is currently the planned method of powering the heat pipes). The proposed calorimeter is constructed from a copper alloy and relies on a laminar flow water-coolant channel design to absorb and transport energy

  14. Methodology for Life Testing of Refractory Metal / Sodium Heat Pipes

    International Nuclear Information System (INIS)

    This work establishes an approach to generate carefully controlled data to find heat pipe operating life with material-fluid combinations capable of extended operation. To accomplish this goal acceleration is required to compress 10 years of operational life into 3 years of laboratory testing through a combination of increased temperature and mass fluence. Specific test series have been identified, based on American Society for Testing and Materials (ASTM) specifications, to investigate long-term corrosion rates. The refractory metal selected for demonstration purposes is a molybdenum-44.5% rhenium alloy formed by powder metallurgy. The heat pipes each have an annular crescent wick formed by hot isostatic pressing of molybdenum-rhenium wire mesh. The heat pipes are filled by vacuum distillation with purity sampling of the completed assembly. Round-the-clock heat pipe tests with 6-month destructive and non-destructive inspection intervals are conducted to identify the onset and level of corrosion. Non-contact techniques are employed to provide power to the evaporator (radio frequency induction heating at 1 to 5 kW per heat pipe) and calorimetry at the condenser (static gas gap coupled water cooled calorimeter). The planned operating temperature range extends from 1123 to 1323 K. Accomplishments before project cancellation included successful development of the heat pipe wick fabrication technique, establishment of all engineering designs, baseline operational test requirements, and procurement/assembly of supporting test hardware systems. (authors)

  15. Titanium Loop Heat Pipes for Space Nuclear Radiators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop titanium Loop Heat Pipes (LHPs) that can be used in low-mass space nuclear radiators, such as...

  16. Micro-Channel Embedded Pulsating Heat Pipes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the need for thermal control technology becomes more demanding Micro-Channel Embedded Pulsating Heat Pipes (ME-PHPs) represents a sophisticated and enabling...

  17. Variable Conductance Heat Pipes for Radioisotope Stirling Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall program objective is to develop a high temperature variable conductance heat pipe (VCHP) backup radiator, and integrate it into a Stirling radioisotope...

  18. Startup analysis for a high temperature gas loaded heat pipe

    Science.gov (United States)

    Sockol, P. M.

    1973-01-01

    A model for the rapid startup of a high-temperature gas-loaded heat pipe is presented. A two-dimensional diffusion analysis is used to determine the rate of energy transport by the vapor between the hot and cold zones of the pipe. The vapor transport rate is then incorporated in a simple thermal model of the startup of a radiation-cooled heat pipe. Numerical results for an argon-lithium system show that radial diffusion to the cold wall can produce large vapor flow rates during a rapid startup. The results also show that startup is not initiated until the vapor pressure p sub v in the hot zone reaches a precise value proportional to the initial gas pressure p sub i. Through proper choice of p sub i, startup can be delayed until p sub v is large enough to support a heat-transfer rate sufficient to overcome a thermal load on the heat pipe.

  19. High thermal-transport capacity heat pipes for space radiators

    Science.gov (United States)

    Carlson, Albert W.; Gustafson, Eric; Roukis, Susan L.

    1987-01-01

    This paper presents the results of performance tests of several dual-slot heat pipe test articles. The dual-slot configuration has a very high thermal transport capability and has been identified as a very promising candidate for the radiator system for the NASA Space Station solar dynamic power modules. Two six-foot long aluminum heat pipes were built and tested with ammonia and acetone. A 20-ft long heat pipe was also built and tested with ammonia. The test results have been compared with performance predictions. A thermal transport capacity of 2000 W at an adverse tilt of 1 in. and a 1000 W capacity at an adverse tilt of 2 in. were achieved on the 20-ft long heat pipe. These values are in close agreement with the predicted performance limits.

  20. Experimental study on silicon micro-heat pipe arrays

    Energy Technology Data Exchange (ETDEWEB)

    Launay, S.; Sartre, V.; Lallemand, M. [Institut National des Sciences Appliquees, Villeurbanne (France). Centre de Thermique

    2004-02-01

    In this study, micro-heat pipe arrays etched into silicon wafers have been investigated for electronic cooling purposes. Micro-heat pipes of triangular cross-section and with liquid arteries were fabricated by wet anisotropic etching with a KOH solution. The microchannels (230 {mu}m wide) are closed by molecular bonding of a plain wafer with the grooved one. A test bench was developed for the micro-heat pipe filling and the thermal characterisation. The temperature profile on the silicon surface is deduced from experimental measurements. The results show that with the artery micro-heat pipe array, filled with methanol, the effective thermal conductivity of the silicon wafer is significantly improved compared to massive silicon. (author)

  1. Corrosion in alkali metal/molybdenum heat pipes

    International Nuclear Information System (INIS)

    Molybdenum/sodium (Mo/Na) and molybdenum/lithium (Mo/Li) heat pipes have been operated for long periods of time in a study of their resistance to failure by alkali metal corrosion. Some Mo/Na heat pipes have operated over 20,600 h at 1400 K without failure, while at least one similar heat pipe failed in less than 14 hours at 1435 K. Detailed post-mortem analyses which have been performed on three failed Mo/Na heat pipes all indicated impurity controlled corrosion of their evaporators. Impurities observed to be transported included carbon, oxygen, and silicon. A Mo/Li heat pipe that failed after 25,216 h of operation at 1700 K was also examined in detail. This failure was due to nickel impurities being transported to the evaporator resulting in perforation of the container tube by the formation of a low melting Mo-Ni alloy. Theoretical thermochemical calculations were conducted for these systems with the objective of corroborating the corrosion mechanisms in both types of heat pipes. The results of these calculations are in general agreement with the observed corrosion a phenomena

  2. Influence of Different Parameters on Heat Pipe Performance

    Directory of Open Access Journals (Sweden)

    Sharmishtha Singh Hada

    2015-10-01

    Full Text Available In electrical and electronic industry due to miniaturization of electronic components heat density increases which, in turns increases the heat flux inside it. Scientist and many researchers are doing lot of work in this field for thermal management of devices. Heat pipe is a device that is used in electronic circuit (micro and power electronics, spacecraft & electrical components for cooling purpose. It is based on the principle of evaporation and condensation of working fluid. Heat pipe made up of three main parts are evaporator, adiabatic and condenser sections. In this working fluid vaporise at evaporator and transfers heat to condenser by adiabatic section where heat release to surrounding. Vapour flows possible from evaporator to condenser section due to vapour pressure difference exist between them. Use of heat pipe material, type of working fluid & its property, wick structure, orientation, filled ratio, operating condition, dimensions of pipe has a prominent effect on heat pipe performance. Variation of these parameters for minimum thermal resistance gives better performance.

  3. Residual stress improvement for pipe weld by means of induction heating pre-flawed pipe

    International Nuclear Information System (INIS)

    The intergranular stress corrosion cracking (IGSCC) has been found in type 304 stainless steel piping of several BWR plants. It is already well known that IGSCC is most likely to occur when three essential factors, material sensitization, high tensile stress and corrosive environment, are present. If the welding residual stress is sufficiently high (200 to approximately 400 MPa) in the inside piping surface near the welded joint, then it may be one of the biggest contributors to IGSCC. If the residual stress is reduced or reversed by some way, the IGSCC will be effectively mitigated. In this paper a method to improve the residual stress named IHSI (Induction Heating Stress Improvement) is explained. IHSI aims to improve the condition of residual stress in the inside pipe surface using the thermal stress induced by the temperature difference in pipe wall, that is produced when the pipe is heated from the outside surface by an induction heating coil and cooled on the inside surface by water simultaneously. This method becomes more attractive when it can be successfully applied to in-service piping which might have some pre-flaw. In order to verify the validity of IHSI for such piping, some experiments and calculations using finite element method were conducted. These results are mainly discussed in this paper from the view-points of residual stress, flaw behaviour during IHSI and material deterioration. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Tundee, Sura; Terdtoon, Pradit; Sakulchangsatjatai, Phrut [Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand); Singh, Randeep; Akbarzadeh, Aliakbar [Energy Conservation and Renewable Energy Group, School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora East Campus, Bundoora, Victoria 3083 (Australia)

    2010-09-15

    This paper presents the results of experimental and theoretical analysis on the heat extraction process from solar pond by using the heat pipe heat exchanger. In order to conduct research work, a small scale experimental solar pond with an area of 7.0 m{sup 2} and a depth of 1.5 m was built at Khon Kaen in North-Eastern Thailand (16 27'N102 E). Heat was successfully extracted from the lower convective zone (LCZ) of the solar pond by using a heat pipe heat exchanger made from 60 copper tubes with 21 mm inside diameter and 22 mm outside diameter. The length of the evaporator and condenser section was 800 mm and 200 mm respectively. R134a was used as the heat transfer fluid in the experiment. The theoretical model was formulated for the solar pond heat extraction on the basis of the energy conservation equations and by using the solar radiation data for the above location. Numerical methods were used to solve the modeling equations. In the analysis, the performance of heat exchanger is investigated by varying the velocity of inlet air used to extract heat from the condenser end of the heat pipe heat exchanger (HPHE). Air velocity was found to have a significant influence on the effectiveness of heat pipe heat exchanger. In the present investigation, there was an increase in effectiveness by 43% as the air velocity was decreased from 5 m/s to 1 m/s. The results obtained from the theoretical model showed good agreement with the experimental data. (author)

  5. Neutronic and thermal design considerations for heat-pipe reactors

    International Nuclear Information System (INIS)

    SABRE (Space-Arena Baseline Reactor) is a 100-kW/sub e/, heat-pipe-cooled, beryllium-reflected, fast reactor that produces heat at a temperature of 15000K and radiatively transmits it to high-temperature thermoelectric (TE) conversion elements. The use of heat pipes for core heat removal eliminates single-point failure mechanisms in the reactor cooling system, and provides minimal temperature drop radiative coupling to the TE array, as well as automatic, self-actuating removal of reactor afterheat. The question of how the failure of a fuel module heat pipe will affect neighboring fuel modules in the core is discussed, as is fission density peaking that occurs at the core/reflector interface. Results of neutronic calculations of the control margin available are described. Another issue that is addressed is that of helium generation in the heat pipes from neutron reactions in the core with the heat pipe fluid. Finally, the growth potential of the SABRE design to much higher powers is examined

  6. Analysis of heat transfer of loop heat pipe used to cool high power LED

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A novel loop heat pipe(LHP)cooling device for high power LED is developed.The thermal capabilities, including startup performance,temperature uniformity and thermal resistance of the loop heat pipe under different heat loads and incline angles have been investigated experimentally.The obtained results indicate that the thermal resistance of the heat pipe heat sink is in the range of 0.19―3.1 K/W,the temperature uniformity in the evaporator is controlled within 1.5℃,and the junction temperature of high power LED can be controlled steadily under 100℃for a heat load of 100 W.

  7. Heat pipe central solar receiver. Volume I. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Bienert, W. B.; Wolf, D. A.

    1979-04-01

    The objective of this project was the conceptual design of a Central Solar Receiver Gas Turbine Plant which utilizes a high temperature heat pipe receiver. Technical and economic feasibility of such a plant was to be determined and preliminary overall cost estimates obtained. The second objective was the development of the necessary heat pipe technology to meet the requirements of this receiver. A heat pipe receiver is ideally suited for heating gases to high temperatures. The heat pipes are essentially loss free thermal diffusers which accept a high solar flux and transform it to a lower flux which is compatible with heat transferred to gases. The high flux capability reduces receiver heating surface, thereby reducing receiver heat losses. An open recuperative air cycle with a turbine inlet temperature of 816/sup 0/C (1500/sup 0/F) was chosen as the baseline design. This results in peak metal temperatures of about 870/sup 0/C (1600/sup 0/F). The receiver consists of nine modular panels which form the semicircular backwall of a cavity. Gas enters the panels at the bottom and exits from the top. Each panel carries 637 liquid metal heat pipes which are mounted at right angle to the gas flow. The evaporators of the heat pipes protrude from the flux absorbing front surface of the panels, and the finned condensors traverse the gas stream. Capital cost estimates were made for a 10 MW(e) pilot plant. The total projected costs, in mid-1978 dollars, range from $1,947 to $2,002 per electrical kilowatt. On the same basis, the cost of a water/steam solar plant is approximately 50% higher.

  8. Effect of heat treatment on carbon steel pipe welds

    International Nuclear Information System (INIS)

    The heat treatment to improve the altered properties of carbon steel pipe welds is described. Pipe critical components in oil, gasification and nuclear reactor plants require adequate room temperature toughness and high strength at both room and moderately elevated temperatures. Microstructure and microhardness across the welds were changed markedly by the welding process and heat treatment. The presentation of hardness fluctuation in the welds can produce premature failure. A number of heat treatments are suggested to improve the properties of the welds. (author) 8 figs., 5 refs

  9. Heat Exchanger System Piping Design for a Tube Rupture Event

    OpenAIRE

    Wakim, Fadi Antoine; Kavcar, Pinar Cakir; Samad, Mustafa

    2012-01-01

    ABSTRACT: Tube-rupture events in shell and tube heat exchangers can result in significantly high surge pressures. Steady state and dynamic methods can be used to assess the impacts of these events on heat exchanger system piping networks. This paper presents the findings of a set of dynamic surge simulations on the impacts of tube-rupture events in a Propane-Feed Gas Heat Exchanger System. Once adjacent piping design is considered, the Joukowsky formulation-based method is not always appropri...

  10. Investigation on critical heat flux of flow in pipes

    Science.gov (United States)

    Zhu, Senyuan

    1990-08-01

    This paper experimentally and theoretically investigates the critical heat flux of flow in pipes. From the analysis of the boiling mechanism and processing by means of the analogy principle of two-phase flow, a criterion equation to express critical heat flux has been derived. Correlated with six different coolants, 355 experimental data, the constant A and exponents K, m, and n are obtained. With a dimensionless correction term to calculate the effect on the varying slotted height of the cooling jacket, the previous equation will be a general equation to calculate the critical heat flux of flow in pipes.

  11. Loop heat pipes - highly efficient heat-transfer devices for systems of sun heat supply

    Energy Technology Data Exchange (ETDEWEB)

    Maydanik, Yu. [Ural Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Thermophysics

    2004-07-01

    Loop heat pipes (LHPs) are hermetic heat-transfer devices operating on a closed evaporation-condensation cycle with the use of capillary pressure for pumping the working fluid [1]. In accordance with this, they possess all the main advantages of conventional heat pipes, but, as distinct from the latter, have a considerably higher heat-transfer capacity, especially when operating in the ''antigravity'' regime, when heat is transferred from above downwards. Besides, LHPs possess a higher functional versatility, are adaptable to different operating conditions and provide great scope for various design embodiments. This is achieved at the expense of both the original design of the device and the properties of the wick - a special capillary structure used for the creation of capillary pressure. The LHP schematic diagram is given in Fig. 1. The device contains an evaporator and a condenser - heat exchanger connected by means of smooth-walled pipe-lines with a relatively small diameter intended for separate motion of vapor and liquid. At present loop heat pipes are most extensively employed in thermoregulation systems of spacecrafts. Miniature LHPs are used for cooling electronics and computers. At the same time there exists a considerable potential of using these devices for the recovery of low-grade (waste) heat from different sources, and also in systems of sun heat supply. In the latter case LHPs may serve as an efficient heat-transfer link between a sun collector and a heat accumulator, which has a low thermal resistance and does not consume any additional energy for pumping the working fluid between them. (orig.)

  12. Development of an improved high performance artery heat pipe

    Science.gov (United States)

    Kraehling, H.

    1981-05-01

    An existing space-qualified arterial high performance heat pipe was improved. Attempts to cut grooves with a self made single point threading tool were not successful. The grooves were not deep enough, so that a sufficient liquid supply over the entire circumference in the heating zone could not be obtained. Employment of commercially available thread taps showed an improvement in the groove depth but the groove profile itself was still poor. A further improvement of the profile shape was attained with a special set of threading tools consisting of an entering tap and a plug tap. Performance measurements with respective artery heat pipes confirmed that the heat pipe performance became better with the improvement of the circumferential groove profile. However, all investigated circumferential groove designs revealed a definitely poorer performance than the standard design with a screenwick as a secondary capillary structure.

  13. Variable Conductance Heat Pipe Performance after Extended Periods of Freezing

    Science.gov (United States)

    Ellis, Michael C.; Anderson, William G.

    2009-03-01

    Radiators operating in lunar or Martian environments must be designed to reject the maximum heat load at the maximum sink temperature, while maintaining acceptable temperatures at lower powers or sink temperatures. Variable Conductance Heat Pipe (VCHP) radiators can passively adjust to these changing conditions. Due to the presence of non-condensable gas (NCG) within each VCHP, the active condensing section adjusts with changes in either thermal load or sink temperature. In a Constant Conductance Heat Pipe (CCHP) without NCG, it is possible for all of the water to freeze in the condenser, by either sublimation or vaporization. With a dry evaporator, startup is difficult or impossible. Several previous studies have shown that adding NCG suppresses evaporator dryout when the condenser is frozen. These tests have been for relatively short durations, with relatively short condensers. This paper describes freeze/thaw experiments involving a VCHP with similar dimensions to the current reactor and cavity cooling radiator heat pipe designs.

  14. Testing Thermal Properties of the Cooling Device with Heat Pipes

    Directory of Open Access Journals (Sweden)

    Malcho M.

    2013-04-01

    Full Text Available Paper deal about testing of device with heat pipes and about research alternative possible applications of heat pipes and potential improvements in purpose effective heat sink from power switches of device. This device is used in various static and moveable applications. Testing device is part of control unit in rail vehicle. The amount of heat produced by power switches depend from working conditions of static converter. Great impact on heat sink has, how as season also this if the vehicle is moving or don't moving. If the vehicle is moving the heat transfer form energy converter to surrounding is caused by forced convection of air flow around device. But the critical conditions occur if the vehicle doesn't move, because the application of this cooling device is based on natural convection. The study deal solution of the problem heat transfer from energy converter to surrounding by natural convection.

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

    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...

  16. Solar dynamic heat rejection technology. Task 2: Heat pipe radiator development

    Science.gov (United States)

    League, Mark; Alario, Joe

    1988-01-01

    This report covers the design, fabrication, and test of several dual slot heat pipe engineering development units. The following dual-slot heat pipes were fabricated and tested: two 6-ft. aluminum heat pipes; a 20-ft. aluminum heat pipe; and a 20-ft. aluminum heat pipe with a four-leg evaporator section. The test results of all four test articles are presented and compared to the performance predicted by the design software. Test results from the four-leg article are incomplete. The methodology for fabricating stainless steel dual slot heat pipes was also studied by performing a tool life test with different single point cutters, and these results are also presented. Although the dual-slot heat pipe has demonstrated the potential to meet the requirements for a high capacity radiator system, uncertainties with the design still exist. The startup difficulties with the aluminum test articles must be solved, and a stainless steel/methanol heat pipe should be built and tested.

  17. Periodic inspection for safety of CANDU heat transport piping systems

    International Nuclear Information System (INIS)

    An approach has been developed for the prediction of the risk of failure or the survival of heat transport piping systems in a nuclear power plant. The effects of various inspection schemes on the risk of failure have been investigated and an inspection method proposed. A list of input data required to apply this method to real situations is specified. Using an example of a pressurized pipe containing a defect, it is shown that the required data can be obtained easily

  18. Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces

    Science.gov (United States)

    Dussinger, Peter M.; Lindemuth, James E.

    1997-01-01

    The principal objective of this Phase 2 SBIR program was to develop and demonstrate a practically insoluble coating for nickel-based superalloys for Stirling engine heat pipe applications. Specific technical objectives of the program were: (1) Determine the solubility corrosion rates for Nickel 200, Inconel 718, and Udimet 72OLI in a simulated Stirling engine heat pipe environment, (2) Develop coating processes and techniques for capillary groove and screen wick structures, (3) Evaluate the durability and solubility corrosion rates for capillary groove and screen wick structures coated with an insoluble coating in cylindrical heat pipes operating under Stirling engine conditions, and (4) Design and fabricate a coated full-scale, partial segment of the current Stirling engine heat pipe for the Stirling Space Power Convertor program. The work effort successfully demonstrated a two-step nickel aluminide coating process for groove wick structures and interior wall surfaces in contact with liquid metals; demonstrated a one-step nickel aluminide coating process for nickel screen wick structures; and developed and demonstrated a two-step aluminum-to-nickel aluminide coating process for nickel screen wick structures. In addition, the full-scale, partial segment was fabricated and the interior surfaces and wick structures were coated. The heat pipe was charged with sodium, processed, and scheduled to be life tested for up to ten years as a Phase 3 effort.

  19. AN INVESTIGATION OF THERMAL CHARACTERISTICS OF A SINTERED-WICK HEAT PIPE WITH DOUBLE HEAT SOURCES

    Directory of Open Access Journals (Sweden)

    Nattawut Tharawadee

    2013-01-01

    Full Text Available Heat pipes have been used extensively in the electronic industry for decades especially in laptop computers. For cost-effectiveness, a single heat pipe is designed to simultaneously transfer heat from both the Central Processing Unit (CPU and the Graphics Processing Unit (GPU inside the main board to the heat sink. This causes the efficiency of the heat pipe to change without any theoretical prediction. In this research, thermal performance of a sintered-wick heat pipe with double heat sources has been experimentally and numerically investigated by utilizing the Finite Element Method (FEM. The focus being the effect that the distance between the two heat sources and also the power input pattern (heat source#1 (HT1: heat source#2(HT2 has on temperature and thermal resistance of the heat pipe. The first heat source (HT1 was located at one end and the heat sink was located at another end of the heat pipe, while another heat source (HT2 was placed between HT1 and a heat sink. The ratios of heat input power were controlled at 10W:10W, 20W:10W and 30W:10W. Two copper blocks (15 mm×15 mm were used as heat sources for the evaporator section (Le1, Le2 to electrically supply heat to the bottom half of the heat pipe. A mathematical model using the Finite Element Method (FEM was established to calculate temperature and thermal resistance. The speed of the cooling fan was adjusted to maintain constant operating temperature at the adiabatic section throughout the tests. The operating temperature was controlled at 60 ± 3°C. It was noted that, when distance between the heat sources was increased from 0 mm to 75 mm, thermal resistance slightly decreased from 0.589-0.53°C/W respectively. Heat source 2, therefore, should be placed as close as possible to the condenser section. Both heat sources should have a distance between them of at least 12 mm, which minimizes heat accumulation. When the power input of HT1 was increased from 10 W to 30W (HT2 was

  20. Heat-balance Thermal Protection with Heat Pipes for Hypersonic Vehicle

    OpenAIRE

    Rong Yisheng; Wei Yuechuan; Duan Dongli; Zhan Renjun

    2016-01-01

    Heat-balance thermal protection is non-ablating thermal protection for leading edge of hypersonic vehicle. Heat will be quickly transferred from high aerodynamic heating area to low aerodynamic heating area, where the energy will be released by radiation. The temperature of high aerodynamic heating area could be reduced to protect the designed structure from being burned down. Heat-balance thermal protection is summarized. The research on heat-pipe for heat-balance thermal protection is intro...

  1. Applications of heat pipes for high thermal load beam lines

    International Nuclear Information System (INIS)

    The high flux beam produced by insertion devices often requires special heat removal techniques. For the optical elements used in such high thermal load beam lines the required precision demands a highly accurate design. Heat pipe cooling of critical elements of the x-1 beam line at the National Synchrotron Light Source is described. This method reduces vibrations caused by water cooling systems and simplifies the design. In some of these designs, deposited heat must be transferred through unbonded contact interfaces. A pinhole assembly and a beam position monitor designed for the x-1 beam line both transfer heat through such interfaces in an ultrahigh vacuum environment. The fundamental design objective is that of removing the heat with minimal interface thermal resistance. We present our test method and results for measuring the thermal resistance across metallic interfaces as a function of contact pressure. The design of some devices which utilize both heat pipes and thermal contact interfaces will also be described. (orig.)

  2. Wall thickness measurements of pipes in heat exchangers using ultrasonic waves

    International Nuclear Information System (INIS)

    Heat exchangers and reactors used in the chemical industry for heat exchange and conversion are exposed to the influence of corrosion and wear. These defect parts must be identified during operation in order to prevent damage occurring to the plant and to restrict break-down times. By means of manual ultrasonic wall thickness measurement worn parts in piping both on the inner and outer sides can be reliably detected in the assembled state. (orig.)

  3. Experimental investigations of the effect of the pipe diameter and heating nonuniformity on the appearance of the heat transfer crisis in steam-generating pipes

    International Nuclear Information System (INIS)

    The aim of the paper is to generalize the results of the efforts to investigate into effect of a steam-generating pipe diameter and of nonuniform heating (NH) along its perimeter on heat transfer crisis in the mentioned pipes. One makes a conclusion that extending of pipe diameter results in decrease of critical steam contents and heat loads. Perimetric NH affects flow hydrodynamics and increases heat loads under which crisis of heat transfer occurs

  4. Niobium alloy heat pipes for use in oxidizing environments

    International Nuclear Information System (INIS)

    Niobium alloys have been used for many years in rocket propulsion systems and afterburner sections of gas turbine engines. In these applications, adequate oxidation resistance is provided by protective silicide coatings. By utilizing these coatings and niobium powder metallurgy to produce porous wicks, it has been demonstrated that niobium alloy heat pipes can comfortably operate in flame temperatures exceeding 3000 K. Results of lithium corrosion tests on C-103 (Nb-10%Hf-1%Ti) up to 1477 K will be presented along with thermal performance data for specific heat pipe designs

  5. Niobium alloy heat pipes for use in oxidizing environments

    Science.gov (United States)

    Craig Wojcik, C.

    1991-01-01

    Niobium alloys have been used for many years in rocket propulsion systems and afterburner sections of gas turbine engines. In these applications, adequate oxidation resistance is provided by protective silicide coatings. By utilizing these coatings and niobium powder metallurgy to produce porous wicks, it has been demonstrated that niobium alloy heat pipes can comfortably operate in flame temperatures exceeding 3000 K. Results of lithium corrosion tests on C-103 (Nb-10%Hf-1%Ti) up to 1477 K will be presented along with thermal performance data for specific heat pipe designs.

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

    Science.gov (United States)

    Skupinski, Robert C.; Tower, Leonard K.; Madi, Frank J.; Brusk, Kevin D.

    1993-04-01

    The Heat Pipe Stirling Engine (HP-1000), a free-piston Stirling engine incorporating three heat exchanger modules, each having a sodium filled heat pipe, has been tested at the NASA-Lewis Research Center as part of the Civil Space Technology Initiative (CSTI). The heat exchanger modules were designed to reduce the number of potential flow leak paths in the heat exchanger assembly and incorporate a heat pipe as the link between the heat source and the engine. An existing RE-1000 free-piston Stirling engine was modified to operate using the heat exchanger modules. This paper describes heat exchanger module and engine performance during baseline testing. Condenser temperature profiles, brake power, and efficiency are presented and discussed.

  7. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    International Nuclear Information System (INIS)

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 2250C without any signs of thermal performance degradation

  8. Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

    Energy Technology Data Exchange (ETDEWEB)

    Strazza, N.P.

    1979-06-30

    This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 225/sup 0/C without any signs of thermal performance degradation. (TFD)

  9. An analysis of electro-osmotic and magnetohydrodynamic heat pipes

    International Nuclear Information System (INIS)

    Mechanically simple methods of improving heat transport in heat pipes are investigated. These methods are electro-osmotic and magnetohydrodynamic augmentation. For the electro-osmotic case, a detailed electrokinetic model is used. The electrokinetic model used includes the effects of pore surface curvature and multiple ion diffusivities. The electrokinetic model is extended to approximate the effects of elevated temperature. When the electro-osmotic model is combined with a suitable heat-pipe model, it is found that the electro-osmotic pump should be a thin membrane. Arguments are provided that support the use of a volatile electrolyte. For the magnetohydrodynamic case, a brief investigation is provided. A quasi-one-dimensional hydromagnetic duct flow model is used. This hydromagnetic model is extended to approximate flow effects unique to heat pipes. When combined with a suitable heat pipe model, it is found that there is no performance gain for the case considered. In fact, there are serious pressure-distribution problems that have not been previously recognized. Potential solutions to these pressure-distribution problems are suggested

  10. Insoluble coatings for Stirling engine heat pipe condenser surfaces

    Science.gov (United States)

    Dussinger, Peter M.

    1993-09-01

    The work done by Thermacore, Inc., Lancaster, Pennsylvania, for the Phase 1, 1992 SBIR National Aeronautics and Space Administration Contract, 'Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces' is described. The work was performed between January 1992 and July 1992. Stirling heat engines are being developed for electrical power generation use on manned and unmanned earth orbital and planetary missions. Dish Stirling solar systems and nuclear reactor Stirling systems are two of the most promising applications of the Stirling engine electrical power generation technology. The sources of thermal energy used to drive the Stirling engine typically are non-uniform in temperature and heat flux. Liquid metal heat pipe receivers are used as thermal transformers and isothermalizers to deliver the thermal energy at a uniform high temperature to the heat input section of the Stirling engine. The use of a heat pipe receiver greatly enhances system efficiency and potential life span. One issue that is raised during the design phase of heat pipe receivers is the potential solubility corrosion of the Stirling engine heat input section by the liquid metal working fluid. This Phase 1 effort initiated a program to evaluate and demonstrate coatings, applied to nickel based Stirling engine heater head materials, that are practically 'insoluble' in sodium, potassium, and NaK. This program initiated a study of nickel aluminide as a coating and developed and demonstrated a heat pipe test vehicle that can be used to test candidate materials and coatings. Nickel 200 and nickel aluminide coated Nickel 200 were tested for 1000 hours at 800 C at a condensation heat flux of 25 W/sq cm. Subsequent analyses of the samples showed no visible sign of solubility corrosion of either coated or uncoated samples. The analysis technique, photomicrographs at 200X, has a resolution of better than 2.5 microns (.0001 in). The results indicate that the heat pipe environment is not directly

  11. Shallow burial of district heating pipes; Grund foerlaeggning av fjaerrvaermeledningar

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Stefan; Saellberg, Sven-Erik; Bergstroem, Gunnar [Swedish National Testing and Research Inst., Boraas (Sweden)

    2006-07-28

    Previous studies have shown that the investment costs for district heating installations in suburban areas can be lowered with more rational construction work. This project has studied the possibilities of decreasing the laying depth for pipes in residential-area roads without risking damage on neither pipe nor road surface. An inventory of regulations from national and local authorities and district heating companies in Sweden was done. The larger cities have specific requirements regarding laying depth in road structures. In most places, however, the guidelines issued by the Swedish District Heating Association are followed. And in smaller cities, the question is handled directly by the municipal district heating company. In some places, e.g., Goeteborg, Joenkoeping and Luleaa, the local authorities and the district heating company have agreed on a smaller laying depth under certain circumstances. An analysis of the costs related to the excavation work, backfilling and asphalt laying showed that the costs can be reduced with about 30 % by decreasing the laying depth from 600 mm to 350 mm. A field trial was done with four twin pipes of dimension 2 x DN 32/160 laid 600 mm, 380 mm, 280 mm and 180 mm below the asphalt surface in a road with heavy traffic. Apart from the laying depth, the installation work was done in accordance with the guidelines from the Swedish District Heating Association. During traffic loading, measurements of internal deformations of the pipes, wheel-track depths in the asphalt surface and load-bearing capacity of the road structure were made. The deformation of the pipes is negligible at all laying depths. This is likely due to an arching action from the backfill which supports most of the forces from the traffic load. Significant wheel-tracks were measured, but they seem to correspond directly to settlements in the new soil. Hence, a shallower pipe trench leads to less prominent wheel-tracks. Shallow pipe burial yields slightly larger heat

  12. Thermal behavior investigation of silicon-Pyrex micro heat pipe

    Directory of Open Access Journals (Sweden)

    Yi Luo

    2014-02-01

    Full Text Available High heat flux is the major reason for the malfunctioning or shortened life of high-power light-emitting diodes (LEDs or integrated circuit (IC components. Cooling technical devices have been widely studied in recent years. A heat pipe made of silicon wafer and Pyrex 7740 has been used in the experiments. Silicon-to-Pyrex bonding is used for the visualization of the flow behavior of the working liquid in heat transfer. A thermal behavior testing system for micro heat pipes (MHPs, including a vacuum chamber, heat flux sensors and thermocouples, was designed and established. The experiments revealed the characteristics of the MEMS heat pipe in LEDs heat transfer, and the maximum equivalent thermal conductivity of the MHPs was 10.6 times that of the silicon wafer. Furthermore, the structure of MHP can be optimized based on these experimental results. They can also be the experimental basis for theoretical study of two-phase flow on the micro scale.

  13. Steady-state heat losses in pipes for low-energy district heating

    DEFF Research Database (Denmark)

    Dalla Rosa, Alessandro; Li, Hongwei; Svendsen, Svend

    2010-01-01

    areas. We start with a review of theories and methods for steady-state heat loss calculation. Next, the article shows how detailed calculations with 2D-modeling of pipes can be carried out by means of computer software based on the finite element method (FEM). The model was validated by comparison...... of low-energy DH systems. Various design concepts are considered in this paper: flexible pre-insulated twin pipes with symmetrical or asymmetrical insulation, double pipes, triple pipes. These technologies are potentially energyefficient and cost-effective solutions for DH networks in low-heat density....... Finally, the article describes proposals for the optimal design of pipes for low-energy applications and presents methods for decreasing heat losses....

  14. Laminar Mixed Convection Heat Transfer Correlation for Horizontal Pipes

    International Nuclear Information System (INIS)

    This study aimed at producing experimental results and developing a new heat transfer correlation based upon a semi-empirical buoyancy coefficient. Mixed convection mass transfers inside horizontal pipe were investigated for the pipe of various length-to-diameters with varying Re. Forced convection correlation was developed using a very short cathode. With the length of cathode increase and Re decrease, the heat transfer rates were enhanced and becomes higher than that of forced convection. An empirical buoyancy coefficient was derived from correlation of natural convection and forced convection with the addition of L/D. And the heat transfer correlation for laminar mixed convection was developed using the buoyancy coefficient, it describes not only current results, but also results of other studies. Mixed convection occurs when the driving forces of both forced and natural convections are of comparable magnitude (Gr/Re2∼1). It is classical problem but is still an active area of research for various thermal applications such as flat plate solar collectors, nuclear reactors and heat exchangers. The effect of buoyancy on heat transfer in a forced flow is varied by the direction of the buoyancy force. In a horizontal pipe the direction of the forced and buoyancy forces are perpendicular. The studies on the mixed convections of the horizontal pipes were not investigated very much due to the lack of practical uses compared to those of vertical pipes. Even the definitions on the buoyancy coefficient that presents the relative influence of the forced and the natural convections, are different by scholars. And the proposed heat transfer correlations do not agree

  15. Thermal control of electronic equipment by heat pipes; Controle thermique de composants electroniques par caloducs

    Energy Technology Data Exchange (ETDEWEB)

    Groll, M.; Schneider, M. [Stuttgart Univ. (Germany). Inst. fuer Kernenergetik und Energiesysteme; Sartre, V.; Chaker Zaghdoudi, M.; Lallemand, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France). Centre de Thermique de Lyon, Upresa CNRS

    1998-05-01

    In the frame of the BRITE-EURAM european programme (KHIEPCOOL project), a literature survey on the main beat pipe and micro heat pipe technologies developed for thermal control of electronic equipment has been carried out. The conventional heat pipes are cylindrical, flat or bellow tubes, using wicks or axial grooves as capillary structures. In the field of micro heat pipes, the component interconnection substrate. The best performances were achieved with Plesch`s axially grooved flat miniature heat pipe, which is able to transfer a heat flux of about 60 W.cm{sup -2}. Theoretical models have shown that the performance of micro heat pipe arrays increase with increasing tube diameter, decreasing tube length and increasing heat pipe density. The heat pipe technologies are classified and compared according to their geometry and location in the system. A list of about 150 references, classified according to their subjects, is presented. (authors) 160 refs.

  16. 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

  17. Experimental study on a heat pipe towards in-core decay heat removal control rod

    International Nuclear Information System (INIS)

    A novel in-core heat removal concept can be adopted in control rods for passive safety of nuclear power plants. The new concept is featured by a passive heat transfer device called heat pipe and combined with control rod. As the first step for this concept, stainless steel 316L heat pipes were tested in terms of heat removal capability under the same diameter condition with an actual control rod in a typical PWR. It has outer diameter of 3/4 inch (17.4 mm inner diameter), and the length of 1000 mm. Also, the capillary-driven heat pipe was compared with a bare tube with same diameter without wick structures called thermosyphon. As the results, heat transfer coefficients of the heat pipe were ∼34% higher than those of thermosyphon. The results were compared with existing correlations and a CFD analysis. The overall heat transfer characteristics of heat pipes such as thermal resistances were checked for potential uses in terms of in-core heat removal. (author)

  18. Kovar Micro Heat Pipe Substrates for Microelectronic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Benson, David A.; Burchett, Steven N.; Kravitz, Stanley H.; Robino, Charles V.; Schmidt, Carrie; Tigges, Chris P.

    1999-04-01

    We describe the development of a new technology for cooling microelectronics. This report documents the design, fabrication, and prototype testing of micro scale heat pipes embedded in a flat plate substrate or heat spreader. A thermal model tuned to the test results enables us to describe heat transfer in the prototype, as well as evaluate the use of this technology in other applications. The substrate walls are Kovar alloy, which has a coefficient of thermal expansion close to that of microelectronic die. The prototype designs integrating micro heat pipes with Kovar enhance thermal conductivity by more than a factor of two over that of Kovar alone, thus improving the cooling of micro-electronic die.

  19. Experimental investigation on a pulsating heat pipe with hydrogen

    Science.gov (United States)

    Deng, H. R.; Liu, Y. M.; Ma, R. F.; Han, D. Y.; Gan, Z. H.; Pfotenhauer, J. M.

    2015-12-01

    The pulsating heat pipe (PHP) has been increasingly studied in cryogenic application, for its high transfer coefficient and quick response. Compared with Nb3Sn and NbTi, MgB2 whose critical transformation temperature is 39 K, is expected to replace some high-temperature superconducting materials at 25 K. In order to cool MgB2, this paper designs a Hydrogen Pulsating Heat Pipe, which allows a study of applied heat, filling ratio, turn number, inclination angle and length of adiabatic section on the thermal performance of the PHP. The thermal performance of the hydrogen PHP is investigated for filling ratios of 35%, 51%, 70% at different heat inputs, and provides information regarding the starting process is received at three filling ratios.

  20. Construction of an Inexpensive Copper Heat-Pipe Oven

    Science.gov (United States)

    Grove, T. T.; Hockensmith, W. A.; Cheviron, N.; Grieser, W.; Dill, R.; Masters, M. F.

    2009-01-01

    We present a new, low-cost method of building an all copper heat-pipe oven that increases the practicality of this device in advanced undergraduate instructional labs. The construction parts are available at local hardware and plumbing supply stores, and the assembly techniques employed are simple and require no machining. (Contains 1 footnote, 3…

  1. Vapor-modulated heat pipe for improved temperature control

    Science.gov (United States)

    Edwards, D. K.; Eninger, J. E.; Ludeke, E. E.

    1978-01-01

    Dryout induced by vapor throttling makes control of equipment temperature less dependent on variations in sink environment. Mechanism controls flow of vapor in heat pipe by using valve in return path to build difference in pressure and also difference in saturation temperature of the vapor. In steady state, valve closes just enough to produce partial dryout that achieves required temperature drop.

  2. Design of megawatt power level heat pipe reactors

    Energy Technology Data Exchange (ETDEWEB)

    Mcclure, Patrick Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Poston, David Irvin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dasari, Venkateswara Rao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reid, Robert Stowers [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-12

    An important niche for nuclear energy is the need for power at remote locations removed from a reliable electrical grid. Nuclear energy has potential applications at strategic defense locations, theaters of battle, remote communities, and emergency locations. With proper safeguards, a 1 to 10-MWe (megawatt electric) mobile reactor system could provide robust, self-contained, and long-term power in any environment. Heat pipe-cooled fast-spectrum nuclear reactors have been identified as a candidate for these applications. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than “traditional” reactors. The goal of this project was to develop a scalable conceptual design for a compact reactor and to identify scaling issues for compact heat pipe cooled reactors in general. Toward this goal two detailed concepts were developed, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials and a power level of about 5 MWe. A series of more qualitative advanced designs were developed (with less detail) that show power levels can be pushed to approximately 30 MWe.

  3. Heat pipe solar receiver with thermal energy storage

    Science.gov (United States)

    Zimmerman, W. F.

    1981-01-01

    An HPSR Stirling engine generator system featuring latent heat thermal energy storge, excellent thermal stability and self regulating, effective thermal transport at low system delta T is described. The system was supported by component technology testing of heat pipes and of thermal storage and energy transport models which define the expected performance of the system. Preliminary and detailed design efforts were completed and manufacturing of HPSR components has begun.

  4. Literature review: Steady-state modelling of loop heat pipes

    OpenAIRE

    Siedel, B.; Sartre, V.; Lefèvre, Frédéric

    2015-01-01

    Loop heat pipes (LHPs) are efficient and reliable heat transfer systems whose operation is based on the liquid–vapour phase-change phenomenon. They use the capillary pressure generated in a porous structure to passively circulate the fluid from a heat source to a heat sink. In this paper, an exhaustive literature review is carried out in order to investigate the existing steady-state models of LHPs. These models can be divided into three categories: numerical models of the entire system, nume...

  5. Maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick

    Institute of Scientific and Technical Information of China (English)

    沈妍; 张红; 许辉; 于萍; 白穜

    2015-01-01

    A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered in the proposed model. Maximum heat transfer capacity was also investigated experimentally. The model was validated by comparing with the experimental results. The maximum heat transfer capacity increases with the vapor core radius increasing. Compared with the inclination angle of 0°, the maximum heat transfer capacity increases at the larger inclination angle, and the change with temperature is larger. The performance of heat pipe with triangular grooved wick is greatly influenced by gravity, so it is not recommended to be applied to the dish solar heat pipe receiver.

  6. Electrically heated pipe in pipe system for hydrate prevention on the Campos Basin

    Energy Technology Data Exchange (ETDEWEB)

    Euphemio, Mauro; Montesanti, Jose Ricardo; Braganca, Elton Jorge; Almeida, Murilo Mesquita de; Coelho, Eduardo; Maia, Alexandre Rodrigues; Peres, Marcelo Borges [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    This paper will refer briefly to some key aspects considered for the design of an Electrically Heated Pipe-in-Pipe- EHPIP system integrated to an Electric Submersible Pump-ESP, to be located at 1800 m water depth in the Campos Basin. In this system, under normal operation the well will be producing through the ESP and in case of long well shut in and during well restart up, a percentage of the electrical power will be delivered to heat the PIP system. The electrical system will have a common sub sea power cable and an Electrical Switch Module, to switch power alternatively to the heating system or to the pump. The systems will not operate simultaneously. (author)

  7. Start Up of a Nb-1%Zr Potassium Heat Pipe From the Frozen State

    Science.gov (United States)

    Glass, David E.; Merrigan, Michael A.; Sena, J. Tom

    1998-01-01

    The start up of a liquid metal heat pipe from the frozen state was evaluated experimentally with a Nb-1%Zr heat pipe with potassium as the working fluid. The heat pipe was fabricated and tested at Los Alamos National Laboratory. RF induction heating was used to heat 13 cm of the 1-m-long heat pipe. The heat pipe and test conditions are well characterized so that the test data may be used for comparison with numerical analyses. An attempt was made during steady state tests to calibrate the heat input so that the heat input would be known during the transient cases. The heat pipe was heated to 675 C with a throughput of 600 W and an input heat flux of 6 W/cm(exp 2). Steady state tests, start up from the frozen state, and transient variations from steady state were performed.

  8. Design and Fabrication of a Novel Hybrid-Structure Heat Pipe for a Concentrator Photovoltaic

    Directory of Open Access Journals (Sweden)

    Heiu-Jou Shaw

    2012-10-01

    Full Text Available This study presents a design method to fabricate a novel hybrid-structure flat plate heat pipe (NHSP heat pipe for a concentrator photovoltaic. The NHSP heat pipe is composed of a flattened copper pipe and a sintered wick structure, and a coronary-stent-like rhombic copper mesh supports the structure. The coronary-stent-like supporting structure enhances the mechanical strength and shortens the reflux path of the working fluid. Experiments demonstrate that the sintered capillary heat pipe reduces the thermal resistance by approximately 72%, compared to a traditional copper mesh-screen heat pipe. Furthermore, it can reduce thermal resistance by 65% after a supporting structure is added to the heat pipe. The results show that the NHSP heat pipe provided the best performance for the concentrator photovoltaic, which can increase photoelectric conversion efficiency by approximately 3.1%, compared to an aluminum substrate.

  9. Off-axis cooling of rotating devices using a crank-shaped heat pipe

    Science.gov (United States)

    Jankowski, Todd A.; Prenger, F. Coyne; Waynert, Joseph A.

    2007-01-30

    The present invention is a crank-shaped heat pipe for cooling rotating machinery and a corresponding method of manufacture. The crank-shaped heat pipe comprises a sealed cylindrical tube with an enclosed inner wick structure. The crank-shaped heat pipe includes a condenser section, an adiabatic section, and an evaporator section. The crank-shape is defined by a first curve and a second curve existing in the evaporator section or the adiabatic section of the heat pipe. A working fluid within the heat pipe provides the heat transfer mechanism.

  10. Assembly and testing of a composite heat pipe thermal intercept for HTS current leads

    International Nuclear Information System (INIS)

    The authors are building high temperature superconducting (HTS) current leads for a demonstration HTS high gradient magnetic separation (HGMS) system cooled by a cryocooler. The current leads are entirely conductively cooled. A composite nitrogen heat pipe provides efficient thermal communication, and simultaneously electrical isolation, between the lead and an intermediate temperature heat sink. Data on the thermal and electrical performance of the heat pipe thermal intercept are presented. The electrical isolation of the heat pipe was measured as a function of applied voltage with and without a thermal load across the heat pipe. The results show the electrical isolation with evaporation, condensation and internal circulation taking place in the heat pipe

  11. Hybrid Heat Pipes for High Heat Flux Spacecraft Thermal Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Grooved aluminum/ammonia Constant Conductance Heat Pipes (CCHPs) are the standard for thermal control in zero-gravity. Unfortunately, they are limited in terms of...

  12. Heat Transfer Effects on Laminar Velocity Profiles in Pipe Flow

    Science.gov (United States)

    Powell, Robert; Jenkins, Thomas

    1998-11-01

    Heat Transfer Effects on Laminar Velocity Profiles in Pipe Flow. Robert L. Powell, Thomas P. Jenkins Department of Chemical Engineering & Materials Science University of California, Davis, CA 95616 Using laser Doppler velocimetry, we have measured the axial velocity profiles for steady, pressure driven, laminar flow of water in a circular tube. The flow was established in a one inch diameter seamless glass tube. The entry length prior to the measuring section was over one hundred diameters. Reynolds numbers in the range 500-2000 were used. Under conditions where the temperature difference between the fluid and the surroundings differed by as little as 0.2C, we found significant asymmetries in the velocity profiles. This asymmetry was most pronounced in the vertical plane. Varying the temperature difference moved the velocity maximum either above or below the centerline depending upon whether the fluid was warmer or cooler than the room. These results compare well to existing calculations. Using the available theory and our experiments it is possible to identify parameter ranges where non-ideal conditions(not parabolic velocity profiles) will be found. Supported by the EMSP Program of DOE.

  13. High capacity demonstration of honeycomb panel heat pipes

    Science.gov (United States)

    Tanzer, H. J.

    1989-01-01

    The feasibility of performance enhancing the sandwich panel heat pipe was investigated for moderate temperature range heat rejection radiators on future-high-power spacecraft. The hardware development program consisted of performance prediction modeling, fabrication, ground test, and data correlation. Using available sandwich panel materials, a series of subscale test panels were augumented with high-capacity sideflow and temperature control variable conductance features, and test evaluated for correlation with performance prediction codes. Using the correlated prediction model, a 50-kW full size radiator was defined using methanol working fluid and closely spaced sideflows. A new concept called the hybrid radiator individually optimizes heat pipe components. A 2.44-m long hybrid test vehicle demonstrated proof-of-principle performance.

  14. Thermal Characteristics of Grooved Heat pipe with Hybrid Nanofluids

    Directory of Open Access Journals (Sweden)

    W S Han

    2011-01-01

    Full Text Available In the present study, the specially designed grooved heat pipe charged with nanofluids was investigated in terms of various parameters such as heat transfer rate(50∼300W with 50 W interval, volume concentration(0.005%, 0.05%, 0.1%, and hybrid combinations, inclination(5°, 45°, 90°, cooling water temperature (1℃, 10℃, and 20℃, surface state, transient state and so on. Hybrid nanofluids with different volume concentration ratios with Ag-H2O and Al2O3-H2O were used as working fluids on a grooved heat pipe(GHP. Comparing with the pure water system, nanofluidic and hybrid nanofluidic system shows greater overall thermal resistance with increasing nano-particle concentration. Also hybrid nanofluids make the system deteriorate in terms of thermal resistance. The post nanofluid experimental data regarding GHP show that the heat transfer performance is similar to the results of nanofluid system. The thermal performance of a grooved heat pipe with nanofluids and hybrid nanofluids were varied with driving parameters but they led to worse system performance.

  15. Behavior study on Na heat pipe in passive heat removal system of new concept molten salt reactor

    International Nuclear Information System (INIS)

    The high temperature Na heat pipe is an effective device for transporting heat, which is characterized by remarkable advantages in conductivity, isothermally and passively working. The application of Na heat pipe on passive heat removal system of new concept molten salt reactor (MSR) is significant. The transient performance of high temperature Na heat pipe was simulated by numerical method under the MSR accident. The model of the Na heat pipe was composed of three conjugate heat transfer zones, i.e. the vapor, wick and wall. Based on finite element method, the governing equations were solved by making use of FORTRAN to acquire the profiles of the temperature, velocity and pressure for the heat pipe transient operation. The results show that the high temperature Na heat pipe has a good performance on operating characteristics and high heat transfer efficiency from the frozen state. (authors)

  16. Transient response of a high-capacity heat pipe for Space Station Freedom

    Science.gov (United States)

    Ambrose, J. H.; Holmes, H. R.

    1991-01-01

    High-capacity heat pipe radiator panels have been proposed as the primary means of heat rejection for Space Station Freedom. In this system, the heat pipe would interface with the thermal bus condensers. Changes in system heat load can produce large temperature and heat load variations in individual heat pipes. Heat pipes could be required to start from an initially cold state, with heat loads temporarily exceeding their low-temperature transport capacity. The present research was motivated by the need for accurate prediction of such transient operating conditions. In this work, the cold startup of a 6.7-meter long high-capacity heat pipe is investigated experimentally and analytically. A transient thermohydraulic model of the heat pipe was developed which allows simulation of partially-primed operation. The results of cold startup tests using both constant temperature and constant heat flux evaporator boundary conditions are shown to be in good agreement with predicted transient response.

  17. Electrically heated pipe in pipe combined with electrical submersible pumps for deepwater development

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sidnei Guerreiro da; Euphemio, Mauro Luiz Lopes [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The general trend of deep water and ultra deep water field development is the requirement of highly insulated flow lines, as flow assurance has become one of the major considerations in designing and operating the sub sea system. If not adequately considered in the design phase, it can have significant and unexpected effects to the operational costs, increasing production lost time, decreasing efficiency. In this scenario, the use of pipe in pipe flow lines, with high passive insulation and/ or active heating (called the Electrically Heated Pipe in Pipe - EHPIP), emerges as an attractive method to prevent deposition, especially of waxes and hydrates, by actively maintaining or leading the temperature of the flow line above a critical limit. Besides, the recent heavy oil discoveries in Brazil have encouraged PETROBRAS to move a step forward in the artificial lift design and operation, by the use of Electrical Submersible Pumps (ESP) installed in deep water wells. The combination of EHPIP and ESP are particularly suitable for deep water, high viscosity and long tie back systems, but also can improve oil recovery and production efficiency by allowing the operator to drop down production losses associated Flow Assurance problems. (author)

  18. FLATTENING EFFECT ON HEAT TRANSFER CHARACTERISTICS OF A SINTERED-WICK HEAT PIPE

    Directory of Open Access Journals (Sweden)

    Weeranut Intagun

    2013-01-01

    Full Text Available The effect of pipe flattening on heat transfer characteristics and the internal phenomena of a sintered-wick heat pipe has been investigated by using three-dimensional Finite Element Method. The calculation domains were focused at three important regions, i.e., vapor core, wick and wall. The Cartesian coordinates and the three-dimensional tetrahedral elements were applied in this model. The selected total elements were 638,400 to ensure the accuracy. The original diameter and total length of heat pipe were 6 mm and 200 mm, respectively. The composite wick made from sintered copper powder and grooved copper pipe was applied with water as working fluid. The vapor flow was assumed to be laminar and incompressible. The predicted results from the program were validated with the experimental results conducted with all similar controlled parameters. It was found that the predicted wall temperature and thermal resistance agreed well with the experimental data with the standard deviations of ±5.95 and ±32.85%, respectively. Furthermore, the overall thermal resistances of the tubular heat pipes (original diameter of 6 mm, which were flattened into the final thickness of 4.0 and 3.0 mm, decreased from 0.91 to 0.83°C/W due to an increase of the contacted surface for heat transfer surface. However, the overall thermal resistance of a flattened heat pipe with the final thickness of 2.5 mm increased to 0.88°C/W, resulting from drastic increase of pressure drop in narrower vapor core. The pivotal final thickness of flattened heat pipe, which is the minimum thickness of pipe to be flattened, has been analysed to be 2.75 mm (about 45% from original diameter.

  19. Forced Convection Heat Transfer in Circular Pipes

    Science.gov (United States)

    Tosun, Ismail

    2007-01-01

    One of the pitfalls of engineering education is to lose the physical insight of the problem while tackling the mathematical part. Forced convection heat transfer (the Graetz-Nusselt problem) certainly falls into this category. The equation of energy together with the equation of motion leads to a partial differential equation subject to various…

  20. A heat pipe mechanism for volcanism and tectonics on Venus

    International Nuclear Information System (INIS)

    A heat pipe mechanism is proposed for the transport of heat through the lithosphere on Venus. This mechanism allows the crust and lithosphere on Venus to be greater than 150 km thick. A thick crust and thick lithosphere can explain the high observed topography and large associated gravity anomalies. For a 150-km-thick lithosphere the required volcanic flux on Venus is 200 km3/yr; this is compared with a flux of 17 km3/yr associated with the formation of the oceanic crust on Earth. A thick basaltic crust on Venus is expected to transform to eclogite at a depth of 60 to 80 km; the dense eclogite would contribute the lithospheric delamination that returns the crust to the interior of the planet completing the heat pipe cycle. Topography and the associated gravity anomalies can be explained by Airy compensation of the thick crust. The principal observation that is contrary to this hypothesis is the mean age of the surface that is inferred from crater statistics; the minimum mean age is about 130 Ma, and this implies an upper limit of 2 km3/yr for the surface volcanic flux. If the heat pipe mechanism was applicable on Earth in the Archean, it would provide the thick lithosphere implied by isotopic data from diamonds

  1. Experimental and Exergy Analysis of A Double Pipe Heat Exchanger for Parallel Flow Arrangement

    OpenAIRE

    Parth P. Parekh; Dr.Neeraj K. Chavda

    2014-01-01

    This paper presents For Experimental and Exergy Analysis of a Double Pipe Heat Exchanger for Parallel- flow Arrangement. The Double pipe heat exchanger is one of the Different types of heat exchangers. double-pipe exchanger because one fluid flows inside a pipe and the other fluid flows between that pipe and another pipe that surrounds the first.In a parallel flow, both the hot and cold fluids enter the Heatexchanger at same end andmove in same direction. The present work is taken up to carry...

  2. Experimental analysis of an adsorption refrigerator with mass and heat-pipe heat recovery process

    International Nuclear Information System (INIS)

    Highlights: ► We develop one heat pipe type adsorption refrigerator. ► New compound adsorbent of CaCl2/activated carbon–ammonia can work more effectively. ► Combined mass recovery-heat pipe heat recovery can improve adsorption performance. ► Combined mass recovery-heat pipe heat recovery can reduce cycle time. - Abstract: A heat pipe type adsorption refrigerator system is proposed and investigated, which can be powered by solar energy or waste heat of engine. The study assesses the performance of compound adsorbent (CaCl2 and activated carbon)–ammonia adsorption refrigeration cycle with different orifice sets and different mass and heat recovery processes by experimental prototype machine. Specific cooling power (SCP) and coefficient of performance (COP) were calculated with experimental data to analyze the influences of operating condition. The results show that the jaw opening of the hand needle nozzle can influence the adsorption performance obviously and the thermostatic expansion valve (TEV) is effective in the intermediate cycle time in the adsorption refrigeration system. The SCP of the cycle with the mass-heat recovery together (combined recovery process) is superior to that of the conventional cycles with mass recovery or heat recovery independently.

  3. Development of an integrated heat pipe-thermal storage system for a solar receiver

    Science.gov (United States)

    Keddy, E.; Sena, J. Tom; Merrigan, M.; Heidenreich, Gary; Johnson, Steve

    1988-01-01

    An integrated heat pipe-thermal storage system was developed as part of the Organic Rankine Cycle Solar Dynamic Power System solar receiver for space station application. The solar receiver incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain thermal energy storage (TES) canisters within the vapor space with a toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the earth orbit, solar energy is delivered to the heat pipe. Part of this thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of earth orbit, the stored energy in the TES units is transferred by the potassium vapor to the toluene heater tube. A developmental heat pipe element was constructed that contains axial arteries and a distribution wick connecting the toluene heater and the TES units to the solar insolation surface of the heat pipe. Tests were conducted to demonstrate the heat pipe, TES units, and the heater tube operation. The heat pipe element was operated at design input power of 4.8 kW. Thermal cycle tests were conducted to demonstrate the successful charge and discharge of the TES units. Axial power flux levels up to 15 watts/sq cm were demonstrated and transient tests were conducted on the heat pipe element. Details of the heat pipe development and test procedures are presented.

  4. Experimental and Numerical Study on Heat Pipe Assisted PCM Storage System

    OpenAIRE

    Behi, Hamidreza

    2015-01-01

    In this study, thermal performance, energy storage and cooling capacity of a heat pipe assisted Phase Change Material (PCM) storage system have been investigated experimentally andnumerically. The heat pipe assisted PCM storage system can store and release energy efficiently.Heat pipe as a two-phase heat transfer device with very high thermal conductivity can beemployed to transfer heat at a high rate and very low-temperature difference. The core ideareferred to this system is to improve the ...

  5. Numerical simulation of potassium heat pipe based on porous medium model

    International Nuclear Information System (INIS)

    The numerical simulation of the potassium heat pipe was performed for the purpose of researching the heat and mass transfer mechanisms inside the heat pipe. A three-phase conjugate mathematical model was built for the heat pipe. And the porous medium model was used in the wick region. The effect of liquid flow on heat transfer performance was considered. The mathematical model was solved by PHOENICS3.6 to acquire the steady state operation parameter inside the heat pipe. The heat and mass transfer mechanisms were obtained from analyzing the simulation results. The simulation results are in good agreement with experiment data. (authors)

  6. Engineering design aspects of the heat-pipe power system

    Science.gov (United States)

    Capell, B. M.; Houts, M. G.; Poston, D. I.; Berte, M.

    1997-01-01

    The Heat-pipe Power System (HPS) is a near-term, low-cost space power system designed at Los Alamos that can provide up to 1,000 kWt for many space nuclear applications. The design of the reactor is simple, modular, and adaptable. The basic design allows for the use of a variety of power conversion systems and reactor materials (including the fuel, clad, and heat pipes). This paper describes a project that was undertaken to develop a database supporting many engineering aspects of the HPS design. The specific tasks discussed in this paper are: the development of an HPS materials database, the creation of finite element models that will allow a wide variety of investigations, and the verification of past calculations.

  7. NASA Lewis Steady-State Heat Pipe Code Architecture

    Science.gov (United States)

    Mi, Ye; Tower, Leonard K.

    2013-01-01

    NASA Glenn Research Center (GRC) has developed the LERCHP code. The PC-based LERCHP code can be used to predict the steady-state performance of heat pipes, including the determination of operating temperature and operating limits which might be encountered under specified conditions. The code contains a vapor flow algorithm which incorporates vapor compressibility and axially varying heat input. For the liquid flow in the wick, Darcy s formula is employed. Thermal boundary conditions and geometric structures can be defined through an interactive input interface. A variety of fluid and material options as well as user defined options can be chosen for the working fluid, wick, and pipe materials. This report documents the current effort at GRC to update the LERCHP code for operating in a Microsoft Windows (Microsoft Corporation) environment. A detailed analysis of the model is presented. The programming architecture for the numerical calculations is explained and flowcharts of the key subroutines are given

  8. CTS TEP thermal anomalies: Heat pipe system performance

    Science.gov (United States)

    Marcus, B. D.

    1977-01-01

    A part of the investigation is summarized of the thermal anomalies of the transmitter experiment package (TEP) on the Communications Technology Satellite (CTS) which were observed on four occasions in 1977. Specifically, the possible failure modes of the variable conductance heat pipe system (VCHPS) used for principal thermal control of the high-power traveling wave tube in the TEP are considered. Further, the investigation examines how those malfunctions may have given rise to the TEP thermal anomalies. Using CTS flight data information, ground test results, analysis conclusions, and other relevant information, the investigation concentrated on artery depriming as the most likely VCHPS failure mode. Included in the study as possible depriming mechanisms were freezing of the working fluid, Marangoni flow, and gas evolution within the arteries. The report concludes that while depriming of the heat pipe arteries is consistent with the bulk of the observed data, the factors which cause the arteries to deprime have yet to be identified.

  9. Sintered Nickel Powder Wicks for Flat Vertical Heat Pipes

    OpenAIRE

    Geir Hansen; Erling Næss; Kolbeinn Kristjansson

    2015-01-01

    The fabrication and performance of wicks for flat heat pipe applications produced by sintering a filamentary nickel powder has been investigated. Tape casting was used as an intermediate step in the wick production process. Thermogravimetric analysis was used to study the burn-off of the organic binder used and to study the oxidation and reduction processes of the nickel. The wicks produced were flat, rectangular and intended for liquid transport in the upwards vertical direction. Rate-of-ris...

  10. Small ex-core heat pipe thermionic reactor concept (SEHPTR)

    International Nuclear Information System (INIS)

    The Idaho National Engineering Laboratory (INEL) has developed an innovative space nuclear power concept with unique features and significant advantages for both Defense and Civilian space missions. The Small Ex-core Heat Pipe Thermionic Reactor (SEHPTR) concept was developed in response to Air Force needs for space nuclear power in the range of 10 to 40 kilowatts. This paper describes the SEHPTR concept and discusses the key technical issues and advantages of such a system

  11. Status of high-temperature heat-pipe technology

    International Nuclear Information System (INIS)

    This paper discusses the application of heat pipes to nuclear reactor space power systems. Characteristics of the device that favor such an application are described and recent results of current technology development programs are presented. Research areas that will need to be addressed in demonstrating that adequate lifetimes can be achieved with evaporation/condensation cycles operating at high temperatures in a reactor environment are also discussed

  12. Applications of heat pipes for high thermal load beam lines

    International Nuclear Information System (INIS)

    The high flux beam produced by insertion devices often requires special heat removal techniques. For the optical elements used in such high thermal load beam lines, the required precision demands a highly accurate design. Heat pipe cooling of critical elements of the X-1 beam line at the National Synchrotron Light Source is described. This method reduces vibrations caused by water cooling systems and simplifies the design. In some of these designs, deposited heat must be transferred through unbonded contact interfaces. A pinhole assembly and a beam position monitor designed for the X-1 beam line both transfer heat through such interfaces in an ultrahigh vacuum environment. The fundamental design objective is that of removing the heat with minimal interface thermal resistance. We present our test method and results for measuring the thermal resistance across metallic interfaces as a function of contact pressure. The design of some devices which utilize both heat pipes and thermal contact interfaces will also be described. 12 refs., 8 figs

  13. Experimental study of a photovoltaic solar-assisted heat-pump/heat-pipe system

    International Nuclear Information System (INIS)

    A practical design for a heat pump with heat-pipe photovoltaic/thermal (PV/T) collectors is presented. The hybrid system is called the photovoltaic solar-assisted heat-pump/heat-pipe (PV-SAHP/HP) system. To focus on both actual demand and energy savings, the PV-SAHP/HP system was designed to be capable of operating in three different modes, namely, the heat-pipe, solar-assisted heat pump, and air-source heat-pump modes. Based on solar radiation, the system operates in an optimal mode. A series of experiments were conducted in Hong Kong to study the performance of the system when operating in the heat-pipe and the solar-assisted heat-pump modes. Moreover, energy and exergy analyses were used to investigate the total PV/T performance of the system. - Highlights: ► A novel PV-SAHP/HP system with three different operating modes was proposed. ► Performance of the PV-SAHP/HP system was studied experimentally. ► A optimal operating mode of the PV-SAHP/HP system was suggested in this paper.

  14. Solid-Core Heat-Pipe Nuclear Batterly Type Reactor

    International Nuclear Information System (INIS)

    This project was devoted to a preliminary assessment of the feasibility of designing an Encapsulated Nuclear Heat Source (ENHS) reactor to have a solid core from which heat is removed by liquid-metal heat pipes (HP). Like the SAFE 400 space nuclear reactor core, the HPENHS core is comprised of fuel rods and HPs embedded in a solid structure arranged in a hexagonal lattice in a 3:1 ratio. The core is oriented horizontally and has a square rather cylindrical cross section for effective heat transfer. The HPs extend from the two axial reflectors in which the fission gas plena are embedded and transfer heat to an intermediate coolant that flows by natural-circulation. The HP-ENHS is designed to preserve many features of the ENHS including 20-year operation without refueling, very small excess reactivity throughout life, natural circulation cooling, walkaway passive safety, and robust proliferation resistance. The target power level and specific power of the HP-ENHS reactor are those of the reference ENHS reactor. Compared to previous ENHS reactor designs utilizing a lead or lead-bismuth alloy natural circulation cooling system, the HP-ENHS reactor offers a number of advantageous features including: (1) significantly enhanced passive decay heat removal capability; (2) no positive void reactivity coefficients; (3) relatively lower corrosion of the cladding (4) a core that is more robust for transportation; (5) higher temperature potentially offering higher efficiency and hydrogen production capability. This preliminary study focuses on five areas: material compatibility analysis, HP performance analysis, neutronic analysis, thermal-hydraulic analysis and safety analysis. Of the four high-temperature structural materials evaluated, Mo TZM alloy is the preferred choice; its upper estimated feasible operating temperature is 1350 K. HP performance is evaluated as a function of working fluid type, operating temperature, wick design and HP diameter and length. Sodium is the

  15. 46 CFR 61.15-10 - Liquefied-petroleum-gas piping for heating and cooking.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Liquefied-petroleum-gas piping for heating and cooking. 61.15-10 Section 61.15-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Periodic Tests of Piping Systems § 61.15-10 Liquefied-petroleum-gas piping for heating and cooking. (a)...

  16. Titanium based flat heat pipes for computer chip cooling

    Science.gov (United States)

    Soni, Gaurav; Ding, Changsong; Sigurdson, Marin; Bozorgi, Payam; Piorek, Brian; MacDonald, Noel; Meinhart, Carl

    2008-11-01

    We are developing a highly conductive flat heat pipe (called Thermal Ground Plane or TGP) for cooling computer chips. Conventional heat pipes have circular cross sections and thus can't make good contact with chip surface. The flatness of our TGP will enable conformal contact with the chip surface and thus enhance cooling efficiency. Another limiting factor in conventional heat pipes is the capillary flow of the working fluid through a wick structure. In order to overcome this limitation we have created a highly porous wick structure on a flat titanium substrate by using micro fabrication technology. We first etch titanium to create very tall micro pillars with a diameter of 5 μm, a height of 40 μm and a pitch of 10 μm. We then grow a very fine nano structured titania (NST) hairs on all surfaces of the pillars by oxidation in H202. In this way we achieve a wick structure which utilizes multiple length scales to yield high performance wicking of water. It's capable of wicking water at an average velocity of 1 cm/s over a distance of several cm. A titanium cavity is laser-welded onto the wicking substrate and a small quantity of water is hermetically sealed inside the cavity to achieve a TGP. The thermal conductivity of our preliminary TGP was measured to be 350 W/m-K, but has the potential to be several orders of magnitude higher.

  17. Experimental investigation on EV battery cooling and heating by heat pipes

    International Nuclear Information System (INIS)

    Enhancing battery safety and thermal behaviour are critical for electric vehicles (EVs) because they affect the durability, energy storage, lifecycle, and efficiency of the battery. Prior studies of using air, liquid or phase change materials (PCM) to manage the battery thermal environment have been investigated over the last few years, but only a few take heat pipes into account. This paper aims to provide a full experimental characterisation of heat pipe battery cooling and heating covering a range of battery ‘off-normal’ conditions. Two representative battery cells and a substitute heat source ranging from 2.5 to 40 W/cell have been constructed. Results show that the proposed method is able to keep the battery surface temperature below 40 °C if the battery generates less than 10 W/cell, and helps reduce the battery temperature down to 70 °C under uncommon thermal abuse conditions (e.g. 20–40 W/cell). Additionally, the feasibility of using sintered copper-water heat pipes under sub-zero temperatures has been assessed experimentally by exposing the test rig to −15 °C/−20 °C for more than 14 h. Data indicates that the heat pipe was able to function immediately after long hours of cold exposure and that sub-zero temperature conditions had little impact on heat pipe performance. We therefore conclude that the proposed method of battery cooling and heating via heat pipes is a viable solution for EVs

  18. Theoretical Investigation of the Performance of a Novel Loop Heat Pipe Solar Water Heating System for Use in Beijing, China

    OpenAIRE

    ZHAO, Xudong; Wang, Zhangyuan; Tang, Qi

    2010-01-01

    Abstract A novel loop heat pipe (LHP) solar water heating system for typical apartment buildings in Beijing was designed to enable effective collection of solar heat, distance transport, and efficient conversion of solar heat into hot water. Taking consideration of the heat balances occurring in various parts of the loop, such as the solar absorber, heat pipe loop, heat exchanger and storage tank, a computer model was developed to investigate the thermal performance of the system. ...

  19. Hybrid Heat Pipes for Lunar and Martian Surface and High Heat Flux Space Applications

    Science.gov (United States)

    Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.

    2016-01-01

    Novel hybrid wick heat pipes are developed to operate against gravity on planetary surfaces, operate in space carrying power over long distances and act as thermosyphons on the planetary surface for Lunar and Martian landers and rovers. These hybrid heat pipes will be capable of operating at the higher heat flux requirements expected in NASA's future spacecraft and on the next generation of polar rovers and equatorial landers. In addition, the sintered evaporator wicks mitigate the start-up problems in vertical gravity aided heat pipes because of large number of nucleation sites in wicks which will allow easy boiling initiation. ACT, NASA Marshall Space Flight Center, and NASA Johnson Space Center, are working together on the Advanced Passive Thermal experiment (APTx) to test and validate the operation of a hybrid wick VCHP with warm reservoir and HiK"TM" plates in microgravity environment on the ISS.

  20. Convective Heat Transfer Analysis in Fluid Flow with Turbulence Promoters with Heat Pipes

    Directory of Open Access Journals (Sweden)

    Theodor Mateescu

    2007-01-01

    Full Text Available The present paper proposes the analysis and the simulation of the convection heat transfer into the fluid flow with turbulence promoters utilizing heat pipes. The study is based on the necesity of the unconventional energy forms capitalization, increasing of the energy efficiency and leads to the energy consumtion decrease in concordance with the sustainable development concept.

  1. Thermal Performance and Operation Limit of Heat Pipe Containing Neutron Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Jeong, Yeong Shin; Kim, In Guk; Bang, In Choel [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    Recently, passive safety systems are under development to ensure the core cooling in accidents involving impossible depressurization such as station blackout (SBO). Hydraulic control rod drive mechanisms, passive auxiliary feedwater system (PAFS), Passive autocatalystic recombiner (PAR), and so on are types of passive safety systems to enhance the safety of nuclear power plants. Heat pipe is used in various engineering fields due to its advantages in terms of easy fabrication, high heat transfer rate, and passive heat transfer. Also, the various concepts associated with safety system and heat transfer using the heat pipe were developed in nuclear engineering field.. Thus, our group suggested the hybrid control rod which combines the functions of existing control rod and heat pipe. If there is significant temperature difference between active core and condenser, the hybrid control rod can shutdown the nuclear fission reaction and remove the decay heat from the core to ultimate heat sink. The unique characteristic of the hybrid control rod is the presence of neutron absorber inside the heat pipe. Many previous researchers studied the effect of parameters on the thermal performance of heat pipe. However, the effect of neutron absorber on the thermal performance of heat pipe has not been investigated. Thus, the annular heat pipe which contains B{sub 4}C pellet in the normal heat pipe was prepared and the thermal performance of the annular heat pipe was studied in this study. Hybrid control rod concept was developed as a passive safety system of nuclear power plant to ensure the safety of the reactor at accident condition. The hybrid control rod must contain the neutron absorber for the function as a control rod. So, the effect of neutron absorber on the thermal performance of heat pipe was experimentally investigated in this study. Temperature distributions at evaporator section of annular heat pipe were lower than normal heat pipe due to the larger volume occupied by

  2. Effect of Nanofluids on Heat Pipe Thermal Performance: A Review of the Recent Literature

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2013-09-01

    Full Text Available The addition of the nanoparticles to the base fluid is one of the significant issues to enhance the heat transfer of heat pipes. The purpose of this review is to summarize the research done on heat pipes using nanofluids as working fluids in recent years (2012 to 2013. The peer reviewed papers published in citation index journals have been selected for review in this paper. This review article provides additional information for the design of heat pipes with optimum conditions regarding the heat transfer characteristics of nanofluids in heat pipes. Moreover, this paper identifies several important issues that should be considered further in future works.

  3. Hybrid Heat Pipes for High Heat Flux Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The thermal transport requirements for future spacecraft missions continue to increase, approaching several kilowatts. At the same time the heat acquisition areas...

  4. Heat transfer performance of a horizontal micro-grooved heat pipe using CuO nanofluid

    International Nuclear Information System (INIS)

    An experiment was carried out to study the heat transfer performance of a horizontal micro-grooved heat pipe using CuO nanofluid as the working fluid. CuO nanofluid was a uniform suspension of CuO nanoparticles and deionized water. The average diameter of CuO nanoparticles was 50 nm. Mass concentration of CuO nanoparticles varied from 0.5 wt% to 2.0 wt%. The experiment was performed at three steady operating pressures of 7.45 kPa, 12.38 kPa and 19.97 kPa, respectively. Effects of the mass concentration of CuO nanoparticles and the operating pressure on both the heat transfer coefficients of the evaporator and the condenser sections, the critical heat flux (CHF) and the total heat resistance of the heat pipe were discussed. Experimental results show that CuO nanofluid can improve the thermal performance of the heat pipe and there is an optimal mass concentration which is estimated to be 1.0 wt% to achieve the maximum heat transfer enhancement. Operating pressure has apparent influences on both the heat transfer coefficients and the CHF of nanofluids. The minimum pressure corresponds to the maximum heat transfer enhancement. Under an operating pressure of 7.45 kPa, the heat transfer coefficients of the evaporator can be averagely enhanced by 46% and the CHF can be maximally enhanced by 30% when substituting CuO nanofluids for water

  5. Effect of Surplus Standing Liquid on Heat Transfer Resistance in the Heat Pipe (With Mesh wick in a Horizontal Mode)

    OpenAIRE

    KAMATA, Makoto; Ikeda, Yoshio

    1986-01-01

    It is an engineering practice to fill a heat pipe with working fluid of a quantity a little larger than the clearance volume of the screen wick as the most desirable volume of working fluid is unknown. However, it is foresseeable that excessive volume of working fluid deteriorates the performance of the heat pipe. This paper discusses a new method of computation for heat flow and temperature distribution in a heat pipe with the assumptions that the depth of working fluid in the heat pipe can ...

  6. Effect of Nanofluids on Heat Pipe Thermal Performance: A Review of the Recent Literature

    OpenAIRE

    Navid Bozorgan; Nariman Bozorgan

    2013-01-01

    The addition of the nanoparticles to the base fluid is one of the significant issues to enhance the heat transfer of heat pipes. The purpose of this review is to summarize the research done on heat pipes using nanofluids as working fluids in recent years (2012 to 2013). The peer reviewed papers published in citation index journals have been selected for review in this paper. This review article provides additional information for the design of heat pipes with optimum conditi...

  7. Development of heat pipes with potassium as woking fluid: Performance limitations and test rig development

    OpenAIRE

    Odden, Dan Adrian

    2012-01-01

    The incentive to reduce energy consumption in the industry is big, especiallyin high temperature systems. Heat pipes are of great interest for this purposedue to their favorable thermomechanical properties. This master thesis is apart of the ongoing study of Ph.D. candidate Geir Hansen, who is currentlydeveloping a rectangular heat pipe with potassium as working fluid at NTNU.The rectangular heat pipe is intended to be implemented in the walls ofelectrolysis cells as a part of a heat recovery...

  8. Mathematical Modelling and Parameter Optimization of Pulsating Heat Pipes

    CERN Document Server

    Yang, Xin-She; Luan, Tao; Koziel, Slawomir

    2014-01-01

    Proper heat transfer management is important to key electronic components in microelectronic applications. Pulsating heat pipes (PHP) can be an efficient solution to such heat transfer problems. However, mathematical modelling of a PHP system is still very challenging, due to the complexity and multiphysics nature of the system. In this work, we present a simplified, two-phase heat transfer model, and our analysis shows that it can make good predictions about startup characteristics. Furthermore, by considering parameter estimation as a nonlinear constrained optimization problem, we have used the firefly algorithm to find parameter estimates efficiently. We have also demonstrated that it is possible to obtain good estimates of key parameters using very limited experimental data.

  9. Characterisation of girth pipe weld for primary heat transport system of pressurised heavy water reactors

    International Nuclear Information System (INIS)

    The weld and heat affected zone (HAZ) associated with the girth weld are most vulnerable regions of the piping system. The different regions of the weld joint such as the weld metal, HAZ and base metal lead to heterogeneous mechanical and metallurgical properties of the joints. Due to their different metallurgical and mechanical properties, the amounts of damage produced in these regions are different when the component is subjected to service condition. Thus, it is imperative to know the characteristics of these regions of a pipe weld in order to identify the weakest zone for safe designing of high energy piping components. In view of this necessity the present study has been planned to carry out complete characterisation of the weld joint of SA 333 Gr.6 steel pipe, in terms of its metallurgical, mechanical and fracture properties. The mechanical and fracture mechanics properties of the base metal, weld deposit and HAZ have been compared and correlated with reference to their microstructures. Weld joints of SA 333 Gr.6 steel pipe have been prepared by using GTAW root pass and SMAW filling of V-grove as per recommended welding procedure specifications (WPS) conforming to ASME Sec IX commonly used to fabricate nuclear piping system components. The emphasis of the study is to characterise base, weld and HAZ of the pipe weld in terms of chemical, metallurgical, mechanical and fracture mechanics properties. The fracture toughness behaviour of the welds and HAZ has been characterised by J-integral parameters. The fatigue crack growth rate has been characterised by Paris Law. Stretched zone width (SZW) has been measured under SEM to evaluate initiation fracture toughness. The estimated initiation fracture toughness based on SZW and blunting line given by EGF recommendation have been compared. The fracture mechanics properties of base, weld and HAZ has been determined and compared. The fracture mechanics properties of the weld and HAZ have been correlated to their

  10. Preliminary Test of a small heat pipe for hybrid control rod in-core passive decay heat removal system

    International Nuclear Information System (INIS)

    This paper introduces 'Hybrid control rod' combining its original function and heat removal ability. The high temperature operation and high resistance of radiation should be considered to adopt the hybrid heat pipe at the in-core condition. Other design consideration is to make extra inlet parts because it has a high risk of inlet boundary failure. It means that the introduction of heat pipe system is difficult to present nuclear power plants. The other concepts are presented to out-core cooling design but it has low performance compared with in-core heat removal system. Hybrid heat pipe for in-core heat removal system suggests the solution of these problems. Ultimate objective of this research is to develop the passive emergency decay heat removal system using hybrid heat pipes targeting design bases accidents such as station black-out (SBO) and small break loss of coolant accident (SBLOCA). The purpose of this work is to confirm the performance and heat transfer behavior of hybrid heat pipe. The hybrid heat pipe has special condition for operation. Therefore, it is hard to analyze their behavior in core. Table I shows the characteristics of hybrid heat pipe and consideration for manufacturing the heat pipe

  11. Preliminary Test of a small heat pipe for hybrid control rod in-core passive decay heat removal system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Ban, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-05-15

    This paper introduces 'Hybrid control rod' combining its original function and heat removal ability. The high temperature operation and high resistance of radiation should be considered to adopt the hybrid heat pipe at the in-core condition. Other design consideration is to make extra inlet parts because it has a high risk of inlet boundary failure. It means that the introduction of heat pipe system is difficult to present nuclear power plants. The other concepts are presented to out-core cooling design but it has low performance compared with in-core heat removal system. Hybrid heat pipe for in-core heat removal system suggests the solution of these problems. Ultimate objective of this research is to develop the passive emergency decay heat removal system using hybrid heat pipes targeting design bases accidents such as station black-out (SBO) and small break loss of coolant accident (SBLOCA). The purpose of this work is to confirm the performance and heat transfer behavior of hybrid heat pipe. The hybrid heat pipe has special condition for operation. Therefore, it is hard to analyze their behavior in core. Table I shows the characteristics of hybrid heat pipe and consideration for manufacturing the heat pipe.

  12. Effect of Localized Heating on Three-Dimensional Flat-Plate Oscillating Heat Pipe

    OpenAIRE

    Ma, H. B.; Thompson, S.M.

    2010-01-01

    An experimental investigation was conducted, both thermally and visually, on a three-dimensional flat-plate oscillating heat pipe (3D FP-OHP) to characterize its performance under localized heat fluxes while operating in the bottom heating mode and charged with acetone at a filling ratio of 0.73. The cooling area was held constant and three heating areas of 20.16 cm2, 11.29 cm2, and 1.00 cm2 were investigated, respectively. It was found that as the heating area was reduced and higher heat flu...

  13. Development and test of a space-reactor-core heat pipe

    International Nuclear Information System (INIS)

    A heat pipe designed to meet the heat transfer requirements of a 100-kW/sub e/ space nuclear power system has been developed and tested. General design requirements for the device included an operating temperature of 15000K with an evaporator radial flux density of 100 w/cm2. The total heat-pipe length of 2 m comprised an evaporator length of 0.3 m, a 1.2-m adiabatic section, and a condenser length of 0.5 m. A four-artery design employing screen arteries and distribution wicks was used with lithium serving as the working fluid. Molybdenum alloys were used for the screen materials and tube shell. Hafnium and zirconium gettering materials were used in connection with a pre-purified distilled lithium charge to ensure internal chemical compatibility. After initial performance verification, the 14.1-mm i.d. heat pipe was operated at 15 kW throughput at 15000K for 100 hours. No performance degradation was observed during the test

  14. Clearance of BWR steam piping by off line chemical decontamination

    International Nuclear Information System (INIS)

    This paper deals with laboratory tests that analyze the acid attack of metallic samples, contaminated by Co60 in the Caorso nuclear power plant in Italy. The main aim was to establish the working parameters of the decontamination plant for metallic components. The study took into consideration the steam piping, located in the turbine building, that is, piping from the main header to the high pressure turbine stage, as well as other steam piping, connecting different turbine stages or that had other functions. The Co60 is produced in the reactor vessel by neutron capture in the iron nuclei of the materials located in the pressure vessel. The coolant erodes the steel surfaces and deposits these products along the piping. In the first phase of the activity the chemical decontamination process was simulated in the laboratory, in particular the acid attack and the subsequent high pressure water washing. For the various parts of the piping (straight lines, bends, intersections) smear tests enabled the radioactivity distribution to be determined. Metallographic analyses of the samples, core bored by the piping, determined the composition of the deposit (crud) on the internal surface of the components and the radioactivity along the thickness of the crud, and consequently the time of the acid attack in order to obtain the Clearance. Numerical simulations of the Co60 deposition by means of CFD codes are currently being carried out in order to compare the results to those obtained experimentally. This will enable us to classify the systems from a radiological point of view by estimating ‘a priori’ the time required for decontamination

  15. Clearance of BWR steam piping by off line chemical decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Pilo, F. [Department of Mechanical Nuclear and Production Engineering, University of Pisa (Italy); Fontani, E. [Sogin Spa, Caorso Nuclear Power Plant (Italy); Aquaro, D., E-mail: aquaro@ing.unipi.it [Department of Mechanical Nuclear and Production Engineering, University of Pisa (Italy)

    2014-04-01

    This paper deals with laboratory tests that analyze the acid attack of metallic samples, contaminated by Co{sup 60} in the Caorso nuclear power plant in Italy. The main aim was to establish the working parameters of the decontamination plant for metallic components. The study took into consideration the steam piping, located in the turbine building, that is, piping from the main header to the high pressure turbine stage, as well as other steam piping, connecting different turbine stages or that had other functions. The Co{sup 60} is produced in the reactor vessel by neutron capture in the iron nuclei of the materials located in the pressure vessel. The coolant erodes the steel surfaces and deposits these products along the piping. In the first phase of the activity the chemical decontamination process was simulated in the laboratory, in particular the acid attack and the subsequent high pressure water washing. For the various parts of the piping (straight lines, bends, intersections) smear tests enabled the radioactivity distribution to be determined. Metallographic analyses of the samples, core bored by the piping, determined the composition of the deposit (crud) on the internal surface of the components and the radioactivity along the thickness of the crud, and consequently the time of the acid attack in order to obtain the Clearance. Numerical simulations of the Co{sup 60} deposition by means of CFD codes are currently being carried out in order to compare the results to those obtained experimentally. This will enable us to classify the systems from a radiological point of view by estimating ‘a priori’ the time required for decontamination.

  16. Variable Heat Rejection Loop Heat Pipe radiator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal control systems are sized for the maximum heat load in the warmest continuous environment. This design process results in a larger radiator surface area...

  17. Chemical Cleaning Process for Porable Water Distrubution Pipe Systems

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Aging potable water distribution pipe systems are becoming a major concern throughout the world. Deterioration of water quality and service as a result of micro biological tuberculation and corrosion continues to increase. Major costs for replacement or rehabilitation of distribution systems are being faced by most communities. The chemical cleaning solution is an organic oxide scavenger which is mixed with a predetermined quantity of muriatic acid and circulated through an isolated section o...

  18. Two-Pipe Chilled Beam System for Both Cooling and Heating of Office Buildings

    DEFF Research Database (Denmark)

    Afshari, Alireza; Gordnorouzi, Rouzbeh; Hultmark, Göran;

    2013-01-01

    Simulations were performed to compare a conventional 4-pipe chilled beam system and a 2-pipe chilled beam system. The objective was to establish requirements, possibilities and limitations for a well-functioning 2-pipe chilled beam system for both cooling and heating of office buildings. The...... consumption and hence energy savings in the 2-pipe chilled beam system in comparison with the 4-pipe system. The 2-pipe chilled beam system used high temperature cooling and low temperature heating with a water temperature of 20°C to 23°C, available for free most of the year. The system can thus take...... advantage of renewable energy. The results showed that the energy consumption was 3% less in the 2-pipe chilled beam system in comparison with the conventional 4-pipe system when moving cooled and heated water through the building, transferring the energy to where it is needed. Using free cooling (taking...

  19. A dynamic film model of the pulsating heat pipe

    International Nuclear Information System (INIS)

    This article deals with the numerical modeling of the pulsating heat pipe (PHP) and is based on the film evaporation/condensation model recently applied to the single-bubble PHP (Das et al., 2010, 'Thermally Induced Two-Phase Oscillating Flow Inside a Capillary Tube', Int. J. Heat Mass Transfer, 53(19-20), pp. 3905-3913). The described numerical code can treat the PHP of an arbitrary number of bubbles and branches. Several phenomena that occur inside the PHP are taken into account: coalescence of liquid plugs, film junction or rupture, etc. The model reproduces some of the experimentally observed regimes of functioning of the PHP such as chaotic or intermittent oscillations of large amplitudes. Some results on the PHP heat transfer are discussed. (author)

  20. Effect of Variable Emittance Coatings on the Operation of a Miniature Loop Heat Pipe

    Science.gov (United States)

    Douglas, Donya M.; Ku, Jentung; Ottenstein, Laura; Swanson, Theodore; Hess, Steve; Darrin, Ann

    2005-02-01

    As the size of spacecraft shrink to accommodate small and more efficient instruments, smaller launch vehicles, and constellation missions, all subsystems must also be made smaller. Under NASA NRA 03-OSS-02, Space Technology-8 (ST 8), NASA Goddard Space Flight Center and Jet Propulsion Laboratory jointly conducted a Concept Definition study to develop a miniature loop heat pipe (loop heat pipe) thermal management system design suitable for future small spacecraft. The proposed loop heat pipe thermal management system consists of a miniature loop heat pipe (LHP) and deployable radiators that are coated with variable emittance coatings (VECs). As part of the Phase A study and proof of the design concept, variable emittance coatings were integrated with a breadboard miniature loop heat pipe. The entire system was tested under vacuum at various temperature extremes and power loads. This paper summarizes the results of this testing and shows the effect of the VEC on the operation of a miniature loop heat pipe.

  1. An integrated heat pipe-thermal storage design for a solar receiver

    Science.gov (United States)

    Keddy, E.; Sena, J. T.; Woloshun, K.; Merrigan, M. A.; Heidenreich, G.

    Light-weight heat pipe wall elements that incorporate a thermal storage subassembly within the vapor space are being developed as part of the Organic Rankine Cycle Solar Dynamic Power System (ORC-SDPS) receiver for the Space Station application. The operating temperature of the heat pipe elements is in the 770 to 810 K range with a design power throughput of 4.8 kW per pipe. The total heat pipe length is 1.9 M. The Rankine cycle boiler heat transfer surfaces are positioned within the heat pipe vapor space, providing a relatively constant temperature input to the vaporizer. The heat pipe design employs axial arteries and distribution wicked thermal storage units with potassium as the working fluid. Performance predictions for this configuration have been conducted and the design characterized as a function of artery geometry, distribution wick thickness, porosity, pore size, and permeability.

  2. Cool-down and frozen start-up behavior of a grooved water heat pipe

    Science.gov (United States)

    Jang, Jong Hoon

    1990-01-01

    A grooved water heat pipe was tested to study its characteristics during the cool-down and start-up periods. The water heat pipe was cooled down from the ambient temperature to below the freezing temperature of water. During the cool-down, isothermal conditions were maintained at the evaporator and adiabatic sections until the working fluid was frozen. When water was frozen along the entire heat pipe, the heat pipe was rendered inactive. The start-up of the heat pipe from this state was studied under several different operating conditions. The results show the existence of large temperature gradients between the evaporator and the condenser, and the moving of the melting front of the working fluid along the heat pipe. Successful start-up was achieved for some test cases using partial gravity assist. The start-up behavior depended largely on the operating conditions.

  3. An Experimental Investigation of Micro Pulsating Heat Pipes

    Directory of Open Access Journals (Sweden)

    Kai-Shing Yang

    2014-06-01

    Full Text Available Two Si-based micro pulsating heat pipes (µPHPs charged using HFE-7100 were either horizontally or vertically oriented and were tested using several heating powers. The width of each channel was 0.8 mm in one µPHP containing uniform channels, and the channel width was 1.0 mm or 0.6 mm in the other µPHP, which did not contain uniform channels. The depth of each channel was 0.25 mm. The overall size of each µPHP was 60 × 10 × 1.25 mm. Visual observation and temperature measurement of the µPHPs under various conditions were performed and the results were analyzed. The results indicated that when the µPHPs were operated horizontally at a heating power ranging from 1 to 7 W, the pulsating two-phase flow in the channels of the µPHPs could not begin, except when the µPHP containing nonuniform channels was tested at a heating power of 7 W. With a heating power less than 5 W, the frequency of the sine-like oscillating displacement of the vapor slug increased and the displacement of the vapor slug reduced in either vertically oriented μPHP, as the heating power increased With a heating power higher than 5 W, periodic “start-stop” behaviors were observed in the vertical μPHP containing nonuniform channels.

  4. Cold Start of a Radiator Equipped with Titanium-Water Heat Pipes

    Science.gov (United States)

    Jaworske, Donald A.; Sanzi, James L.; Siamidis, John

    2008-01-01

    Radiator panels utilizing titanium-water heat pipes are being considered for lunar applications. A traditional sandwich structure is envisioned where heat pipes are embedded between two high thermal conductivity face sheets. The heat pipe evaporators are to be thermally connected to the heat source through one or more manifolds containing coolant. Initial radiator operation on the lunar surface would likely follow a cold soak where the water in the heat pipes is purposely frozen. To achieve heat pipe operation, it will be necessary to thaw the heat pipes. One option is to allow the sunlight impinging on the surface at sunrise to achieve this goal. Testing was conducted in a thermal vacuum chamber to simulate the lunar sunrise and additional modeling was conducted to identify steady-state and transient response. It was found that sunlight impinging on the radiator surface at sunrise was insufficient to solely achieve the goal of thawing the water in the heat pipes. However, starting from a frozen condition was accomplished successfully by applying power to the evaporators. Start up in this fashion was demonstrated without evaporator dryout. Concern is raised over thawing thermosyphons, vertical heat pipes operating in a gravity field, with no wick in the condenser section. This paper presents the results of the simulated cold start study and identifies future work to support radiator panels equipped with titanium-water heat pipes.

  5. Characterization of a solar photovoltaic/loop-heat-pipe heat pump water heating system

    International Nuclear Information System (INIS)

    Highlights: ► Describing concept and operating principle of the PV/LHP heat pump water heating system. ► Developing a numerical model to evaluate the performance of the system. ► Experimental testing of the prototype system. ► Characterizing the system performance using parallel comparison between the modelling and experimental results. ► Investigating the impact of the operating conditions to the system’s performance. -- Abstract: This paper introduced the concept, potential application and benefits relating to a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for hot water generation. On this basis, the paper reported the process and results of characterizing the performance of such a system, which was undertaken through dedicated thermo-fluid and energy balance analyses, computer model development and operation, and experimental verification and modification. The fundamental heat transfer, fluid flow and photovoltaic governing equations were applied to characterize the energy conversion and transfer processes occurring in each part and whole system layout; while the energy balance approach was utilized to enable inter-connection and resolution of the grouped equations. As a result, a dedicated computer model was developed and used to calculate the operational parameters, optimise the geometrical configurations and sizes, and recommend the appropriate operational condition relating to the system. Further, an experimental rig was constructed and utilized to acquire the relevant measurement data that thus enabled the parallel comparison between the simulation and experiment. It is concluded that the testing and modelling results are in good agreement, indicating that the model has the reasonable accuracy in predicting the system’s performance. Under the given experimental conditions, the electrical, thermal and overall efficiency of the PV/LHP module were around 10%, 40% and 50% respectively; whilst the system’s overall performance

  6. Experimental study of partially flattened axial grooved heat pipes

    Institute of Scientific and Technical Information of China (English)

    TAO HanZhong; ZHANG Hong; ZHUANG Jun; Jerry W. BOWMANS

    2008-01-01

    This article made experimental study on mini-axial grooved heat pipes (AGHP) with 11 flattening forms. It analyzed how the flattening form, flattening thickness and working temperature affect axial tem-perature distribution, thermal resistance, heat transfer limit and the phase-change heat transfer coeffi-cients in evaporator and condenser sections. The result indicates that all forms of AGHPs can maintain good isothermal performance under normal operating condition. The geometric shape of AGHP has obvious impact on heat transfer limit. With respect to an AGHP with 2 mm-thick evaporator section, when the thickness of its condenser section increases from 2 to 3 mm, its heat transfer limit increases by 81%; with respect to an AGHP with 3 mm-thick evaporator section, when the thickness of its con-denser section increases from 2 to 3 mm, its heat transfer limit increases by 134%; with respect to an AGHP with 4 mm-thick condenser section, when the thickness of its evaporator section increases from 2 to 3 mm, its heat transfer limit increases by 26%. When the thickness of the evaporator section in-creases by 1 mm, the heat transfer limit will increase by 9%-26%, while when the thickness of the condenser section increases by 1 mm, the heat transfer limit will increase by 20%-86%. The thickness of the condenser section has greater impact on heat transfer performance of an AGHP than the thick-ness of the evaporator section does. The study content of this article will help understand the heat transfer performance of AGHP, and electronic thermal design process.

  7. Simultaneous power generation and heat recovery using a heat pipe assisted thermoelectric generator system

    International Nuclear Information System (INIS)

    Highlights: • A new passive power cogeneration system using industrial waste heat was introduced. • Heat pipes and thermoelectrics were used for recovering waste heat and electricity. • Theoretical model predicted the 2 kW test rig could recover 1.345 kW thermal power. • 10.39 W electrical power was produced equivalent to 0.77% conversion efficiency. - Abstract: This research explores a new method of recovering waste heat and electricity using a combination of heat pipes and thermoelectric generators (HP-TEG). The HP-TEG system consists of Bismuth Telluride (Bi2Te3) based thermoelectric generators (TEGs), which are sandwiched between two finned heat pipes to achieve a temperature gradient across the TEG for thermoelectricity generation. A theoretical model was developed to predict the waste heat recovery and electricity conversion performances of the HP-TEG system under different parametric conditions. The modelling results show that the HP-TEG system has the capability of recovering 1.345 kW of waste heat and generating 10.39 W of electrical power using 8 installed TEGs. An experimental test bench for the HP-TEG system is under development and will be discussed in this paper

  8. Performance predictions and measurements for space-power-system heat pipes

    International Nuclear Information System (INIS)

    High temperature liquid metal heat pipes designed for space power systems have been analyzed and tested. Three wick designs are discussed and a design rationale for the heat pipe is provided. Test results on a molybdenum, annular wick heat pipe are presented. Performance limitations due to boiling and capillary limits are presented. There is evidence that the vapor flow in the adiabatic section is turbulent and that the transition Reynolds number is 4000

  9. Additive layer manufactured sinter-style aluminium/ammonia heat pipes

    OpenAIRE

    Masoud Ameli, Seied

    2012-01-01

    A novel heat pipe (HP) manufacturing method has been developed based on an additive layer manufacturing technique called “selective laser melting” or SLM. This innovation is expected to benefit current applications of aluminium/ammonia heat pipes in space and terrestrial projects as well as many new HP applications. The project was jointly sponsored by the Northumbria University and Thermacore, a world leading heat pipe manufacturing company in the UK, and formed the feasibility stage of ...

  10. Applications of heat pipes for HVAC dehumidification at Walt Disney World

    International Nuclear Information System (INIS)

    This paper presents the theory and application of heat pipes for HVAC dehumidification purposes. In HVAC applications, a heat pipe is used as a heat exchanger that transfers heat from the return air directly to the supply air. The air is pre-cooled entering the cooling coil and reheated using the same heat removed from the return air. While consuming no energy, the heat pipe lets the evaporator coil operate at a lower temperature, increasing the moisture removal capabilities of the HVAC system by 50% to 100%. WALT DISNEY WORLD is currently testing several heat pipe applications ranging from 1 to 240 tons. The applications include (1) water attractions (2) museums/artifacts areas (3) resort guest rooms and (4) locker rooms. Actual energy usage and relative humidity reductions are shown to determine the effectiveness of the heat pipe as an energy efficient method of humidity control

  11. Excess liquid in heat-pipe vapor spaces

    Science.gov (United States)

    Eninger, J. E.; Edwards, D. K.

    1977-01-01

    A mathematical model is developed of excess liquid in heat pipes that is used to calculate the parameters governing the axial flow of liquid in fillets and puddles that form in vapor spaces. In an acceleration field, the hydrostatic pressure variation is taken into account, which results in noncircular meniscus shapes. The two specific vapor-space geometries considered are circular and the 'Dee-shape' that is formed by a slab wick in a circular tube. Also presented are theoretical and experimental results for the conditions under which liquid slugs form at the ends of the vapor spaces. These results also apply to the priming of arteries.

  12. A New Wick Structure to Significantly Improve Heat Pipe Performance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Increasing thermal requirements for space-based thermal control systems are straining the capabilities of conventional heat pipes. Mainstream has experimentally...

  13. Thermal performance of evacuated tube heat pipe solar collector

    Science.gov (United States)

    Putra, Nandy; Kristian, M. R.; David, R.; Haliansyah, K.; Ariantara, Bambang

    2016-06-01

    The high fossil energy consumption not only causes the scarcity of energy but also raises problems of global warming. Increasing needs of fossil fuel could be reduced through the utilization of solar energy by using solar collectors. Indonesia has the abundant potential for solar energy, but non-renewable energy sources still dominate energy consumption. With heat pipe as passive heat transfer device, evacuated tube solar collector is expected to heat up water for industrial and home usage without external power supply needed to circulate water inside the solar collector. This research was conducted to determine the performance of heat pipe-based evacuated tube solar collector as solar water heater experimentally. The experiments were carried out using stainless steel screen mesh as a wick material, and water and Al2O3-water 0.1% nanofluid as working fluid, and applying inclination angles of 0°, 15°, 30°, and 45°. To analyze the heat absorbed and transferred by the prototype, water at 30°C was circulated through the condenser. A 150 Watt halogen lamp was used as sun simulator, and the prototype was covered by an insulation box to obtain a steady state condition with a minimum affection of ambient changes. Experimental results show that the usage of Al2O3-water 0.1% nanofluid at 30° inclination angle provides the highest thermal performance, which gives efficiency as high as 0.196 and thermal resistance as low as 5.32 °C/W. The use of nanofluid as working fluid enhances thermal performance due to high thermal conductivity of the working fluid. The increase of the inclination angle plays a role in the drainage of the condensate to the evaporator that leads to higher thermal performance until the optimal inclination angle is reached.

  14. Optimal design of the heat pipe using TLBO (teaching–learning-based optimization) algorithm

    International Nuclear Information System (INIS)

    Heat pipe is a highly efficient and reliable heat transfer component. It is a closed container designed to transfer a large amount of heat in system. Since the heat pipe operates on a closed two-phase cycle, the heat transfer capacity is greater than for solid conductors. Also, the thermal response time is less than with solid conductors. The three major elemental parts of the rotating heat pipe are: a cylindrical evaporator, a truncated cone condenser, and a fixed amount of working fluid. In this paper, a recently proposed new stochastic advanced optimization algorithm called TLBO (Teaching–Learning-Based Optimization) algorithm is used for single objective as well as multi-objective design optimization of heat pipe. It is easy to implement, does not make use of derivatives and it can be applied to unconstrained or constrained problems. Two examples of heat pipe are presented in this paper. The results of application of TLBO algorithm for the design optimization of heat pipe are compared with the NPGA (Niched Pareto Genetic Algorithm), GEM (Grenade Explosion Method) and GEO (Generalized External optimization). It is found that the TLBO algorithm has produced better results as compared to those obtained by using NPGA, GEM and GEO algorithms. - Highlights: • The TLBO (Teaching–Learning-Based Optimization) algorithm is used for the design and optimization of a heat pipe. • Two examples of heat pipe design and optimization are presented. • The TLBO algorithm is proved better than the other optimization algorithms in terms of results and the convergence

  15. Choice of insulation standard for pipe networks in 4th generation district heating systems

    DEFF Research Database (Denmark)

    Lund, Rasmus Søgaard; Mohammadi, Soma

    2016-01-01

    Reducing heat losses from the pipe networks in district heating (DH) systems is one of the main challenges when developing DH in the future. Fourth generation DH is a concept that defines the role of DH in future smart energy systems as an integrated part together with smart electricity grids and...... smart gas grids. Improving DH pipes by improving the insulation standard results in decreasing the heat and temperature losses from the pipe networks. When reducing heat losses from DH pipes, there is a trade-off between the increasing cost of pipe insulation and the associated savings in the heat...... implementing different pipe insulation standards. In the second step, the specific grid losses found in the first step are analysed in an integrated energy systems model where all main energy sectors and their interrelations are included. The outcome of the study can provide decision support when planning...

  16. A novel flat polymer heat pipe with thermal via for cooling electronic devices

    International Nuclear Information System (INIS)

    Highlights: • We design and fabricate a novel flat polymer heat pipe with thermal via arrays. • We examine the heat transfer performance of the fabricated flat plate heat pipes. • The thermal-via is effective in reducing the thermal resistance of the heat pipe. • There exists an optimal filling ratio which yields the lowest thermal resistance. • Using the flat heat pipe with thermal via for cooling electronics is investigated. - Abstract: The efficiency and heat transfer characteristics of a newly designed flat polymer heat pipe that uses copper micro thermal via was investigated using a fabricated laboratory model to measure the amount of heat that could be removed from a given heat source (a heater or a light emitting diode (LED) module) under a range of different operating conditions. The heat pipe consists of a copper frame 1 mm thick which is sandwiched between top and bottom sheets of FR4 polymer to form a vapor chamber. Copper meshes were used for the wick structure in the vapor chamber. The design also includes an array of thermal via, formed by 0.5 mm holes drilled through the polymer, which are copper plated and filled with resin similar to the FR4 polymer. This novel design enhances heat conduction through the wall of the polymer heat pipe. A transient dual interface method (TDIM) was used to measure the thermal resistance of the LED module mounted on the flat heat pipe. Experimental results showed that use of the thermal via design reduced the lateral thermal resistance by 20–25%. The thermal resistance of the flat heat pipe was also affected by the filling ratio of working fluid and the tilt angle. When the flat heat pipe with thermal via was used as a mounting substrate with the LED module located in the center of the top surface, experimental results showed the thermal resistance of the substrate was reduced by 57%

  17. Investigation of a wire plate micro heat pipe array

    Energy Technology Data Exchange (ETDEWEB)

    Launay, Stephane; Sartre, Valerie; Lallemand, Monique [CETHIL, UMR CNRS 5008, INSA, 20, av. A. Einstein, 69621 Cedex, Villeurbanne (France); Mantelli, Marcia B.H.; Paiva, Kleber Vieira de [Mechanical Engineering Department, Federal University of Santa Catarina UFSC, P.O. Box 476, 88040-900, SC, Florianopolis (Brazil)

    2004-05-01

    In the present work, experimental and theoretical investigations have been conducted on a copper/water wire plate micro heat pipe (MHP). The experimental results show that its effective thermal conductivity is improved by a factor 1.3 as compared to the empty MHP array. A numerical model is used to predict the fluid distribution along the MHP axis, the temperature field and the maximum heat flux corresponding to the MHP capillary limit. The 1D, steady-state hydrodynamic model is based on the conservation equations for the liquid and vapour phases. The wall temperatures are calculated from the thermal resistance network of the wall and the liquid film. A good agreement between the theoretical and experimental data is achieved. The effect of various parameters - contact angle, fluid type, corner angle, fill charge - is theoretically investigated. (authors)

  18. Transient cooling of electronic components by flat heat pipes

    International Nuclear Information System (INIS)

    This paper presents a theoretical investigation of a Flat Heat Pipe (spreader) designed for the cooling of multiple electronic components in transient state. This model is a transient model, coupling 3D thermal model with a 2D hydrodynamic one through the mass flux of evaporation-condensation, which occurs in a mass conservation equation. The model makes it possible to obtain the FHP wall transient temperatures, the transient pressures, velocities and temperatures in both liquid and vapor phases. A comparison of the behaviour of the FHP and an equivalent solid plate submitted to a transient thermal cycle shows that the FHP enhanced the electronic components cooling for the long thermal cycle duration when the solid plate is more efficient for the very short transient thermal cycles. The FHP provides also a very low thermal resistance, which helps to minimise the temperature gradient and then the hot spots and overheating. - Highlights: → In this study we model a Flat Heat Pipe (FHP) designed for the cooling of electronic components. → This model is a transient model, coupling 3D thermal and hydrodynamic models. → The model makes it possible to obtain the FHP wall transient temperatures. → Transient pressures, velocities and temperatures in liquid and vapor phases are also obtained. → We conclude that FHP is more efficient for long than very short thermal cycles.

  19. Effect of a heated pipe length on DNB heat flux in forced flow of liquid hydrogen

    International Nuclear Information System (INIS)

    The heat transfer in a forced flow of saturated liquid hydrogen was measured using vertically-mounted heated pipes with an inner diameter d of 6.0 mm and lengths L of 50, 100, 200 and 250 mm for wide ranges of flow velocity and pressure. The heat fluxes at departure from nucleate boiling (DNB) were higher for higher flow velocities, lower pressures and shorter L. The effect of L on the DNB heat flux was clarified and could be described by the modified authors' DNB correlation. (author)

  20. Tensile and fracture properties of primary heat transport system piping material

    International Nuclear Information System (INIS)

    The fracture mechanics calculations in leak-before-break analysis of nuclear piping system require material tensile data and fracture resistance properties in the form of J-R curve. There are large variations in fracture parameters due to variation in chemical composition and process used in making the steel components. Keeping this in view, a comprehensive program has been planned to generate the material data base for primary heat transport system piping using the specimens machined from actual pipes used in service. The material under study are SA333 Gr.6 (base as well as weld) and SA350 LF2 (base). Since the operating temperatures of 500 MWe Indian PHWR PHT system piping range from 260 degC to 304 degC the test temperature chosen are 28 degC, 200 degC, 250 degC and 300 degC. Tensile and compact tension specimens have been fabricated from actual pipe according to ASTM standard. Fracture toughness of base metal has been observed to be higher compared to weld metal in SA333 Gr.6 material for the temperature under consideration. Fracture toughness has been observed to be higher for LC orientation (notch in circumferential direction) compared to CL orientation (notch is in longitudinal direction) for the temperature range under study. Fracture toughness value decreases with increase in temperature for the materials under study. Finally, chemical analysis has been carried out to investigate the reason for high toughness of the material. It has been concluded that low percentage of carbon and nitrogen, low inclusion rating and fine grain size has enhanced the fracture toughness value

  1. The flexible heat pipe radiant panel; Het flexibele heat pipe stralingspaneel

    Energy Technology Data Exchange (ETDEWEB)

    Boeve, M.; Van Paassen, A.H.C. [Sectie Werktuigbouwkunde, Koudetechniek en Klimaatregeling, Faculteit Ontwerp, Constructie en Productie, Technische Universiteit Delft, Delft (Netherlands)

    2000-08-01

    WTH in Dordrecht, Netherlands, is a company that designs and supplies heating and cooling systems for walls and floors. It challenged the Climate Control and Refrigeration Technology Department at the Delft University of Technology (Delft, Netherlands) to devise and implement a new system. Further research has shown that the system that was designed is suitable for producing a flexible heating system. Further development of the system may result in its future use for the purposes of cooling. 4 refs.

  2. Experimental study on microcapsule fluid oscillating heat pipe

    Institute of Scientific and Technical Information of China (English)

    LIN ZiRong; WANG ShuangFeng; ZHANG WeiBao

    2009-01-01

    In this experiment, s four-turn oscillating heat pipe (OHP) is made of copper tube with an inner diameter of 1.3 mm, and an outer diameter of 2.5 mm. A series of experiments are performed to investigate the startup characteristics of OHP, and the effects of different working fluids (FS-39E microcapsule fluid, pure water, ethanol), different liquid filling rates (40%-80%) on the heat transport capability of OHP in vertical bottom heat mode. The results show that the startup of OHP is relative with liquid filling rate, thermal driving force and working fluid; and experiences different flow patterns with the increase of heat load. The best concentration of FS-39E microcapsule fluid is 1 wt%. While FS-39E microcapsule fluid is used as the working fluid, compared with pure water and ethanol, the OHP has a broader working scope; when the liquid filling rate is relatively high, the OHP shows a better performance on the startup and heat transport capability.

  3. Experimental study on microcapsule fluid oscillating heat pipe

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this experiment,a four-turn oscillating heat pipe(OHP)is made of copper tube with an inner diameter of 1.3mm,and an outer diameter of 2.5mm.A series of experiments are performed to investigate the startup characteristics of OHP,and the effects of different working fluids(FS-39E microcapsule fluid,pure water,ethanol),different liquid filling rates(40%-80%)on the heat transport capability of OHP in vertical bottom heat mode.The results show that the startup of OHP is relative with liquid filling rate,thermal driving force and working fluid;and experiences different flow patterns with the increase of heat load.The best concentration of FS-39E microcapsule fluid is 1wt%.While FS-39E microcapsule fluid is used as the working fluid,compared with pure water and ethanol,the OHP has a broader working scope;when the liquid filling rate is relatively high,the OHP shows a better performance on the startup and heat transport capability.

  4. Characteristics of Screen Mesh Wick Heat Pipe with Nanofluid as Passive Cooling System

    Directory of Open Access Journals (Sweden)

    W.N. Septiadi

    2013-04-01

    Full Text Available The heat pipe is one of the cooling media which is potential to be developed for the passive cooling system for nuclear reactors. To enhance the performance of the heat pipe, nanofluids have been used as the working fluid for the heat pipe. This paper studies the characteristics of nanofluids as the working fluid of heat pipe with screen mesh wick, which was the mixture of nano-sized particles (Al2O3 and TiO2 with water as the base fluid. The nanoparticles have average diameter of 20 nm, made with 1% to 5% volume fraction. The heat pipe thermal performance was tested using heater with different heat load. The experimental result shows the use of 5% Al2O3-water improve the thermal performance by reducing the temperature at evaporator side as much as 23.7% and the use of TiO2-water reduce the temperature at evaporator side as much as 20.2% compared to the use of water. The use of nanofluid also decreases the thermal resistance of heat pipe. As the use of nanofluid improves thermal performance of heat pipe, it has a potential for applications along with heat pipes at nuclear reactors

  5. High temperature superconducting current lead test facility with heat pipe intercepts

    International Nuclear Information System (INIS)

    A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections

  6. VALIDATION OF SIMULATION MODELS FOR DIFFERENTLY DESIGNED HEAT-PIPE EVACUATED TUBULAR COLLECTORS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Dragsted, Janne; Furbo, Simon

    2007-01-01

    Differently designed heat-pipe evacuated tubular collectors have been investigated theoretically and experimentally. The theoretical work has included development of two TRNSYS [1] simulation models for heat-pipe evacuated tubular collectors utilizing solar radiation from all directions. One model...... is developed for heat-pipe evacuated tubular collectors with flat fins and one model is developed for heat-pipe evacuated tubular collectors with curved fins. The models are characterized by detailed calculations of the heat transfer processes in the fins, by detailed shadow modeling and by fins with...... selective coating on both sides. The input to the models is thus not a simple collector efficiency expression but the actual collector geometry. In this study, the TRNSYS models are validated with measurements for four differently designed heat-pipe evacuated tubular collectors. The collectors are produced...

  7. Experimental investigation of the effect of graphene nanofluids on heat pipe thermal performance

    DEFF Research Database (Denmark)

    Sadeghinezhad, Emad; Mehrali, Mohammad; Rosen, Marc A.;

    2016-01-01

    An experimental investigation has been carried out to examine the thermal, performance of a sintered wick heat pipe using aqueous graphene nanoplatelets (GNP) nanofluids. The study focuses on changes in the effects of GNP concentration, heat pipe inclination angle and input heating power. The...... maximum reduction in the thermal resistance of a sintered wick heat pipe filled with 0.1 wt% of GNP is determined to be 48.4% compared with distilled water (DW). The results show that the maximum effective thermal conductivity enhancements for the heat pipe at a GNP concentration of 0.1 wt% and a tilt...... increases the surface wettability, thereby enhancing the thermal performance of the heat pipe....

  8. VALIDATION OF SIMULATION MODELS FOR DIFFERENTLY DESIGNED HEAT-PIPE EVACUATED TUBULAR COLLECTORS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Dragsted, Janne; Furbo, Simon

    Differently designed heat-pipe evacuated tubular collectors have been investigated theoretically and experimentally. The theoretical work has included development of two TRNSYS [1] simulation models for heat-pipe evacuated tubular collectors utilizing solar radiation from all directions. One model...... is developed for heat-pipe evacuated tubular collectors with flat fins and one model is developed for heat-pipe evacuated tubular collectors with curved fins. The models are characterized by detailed calculations of the heat transfer processes in the fins, by detailed shadow modeling and by fins with...... selective coating on both sides. The input to the models is thus not a simple collector efficiency expression but the actual collector geometry. In this study, the TRNSYS models are validated with measurements for four differently designed heat-pipe evacuated tubular collectors. The collectors are produced...

  9. Thermal performance of a flat polymer heat pipe heat spreader under high acceleration

    International Nuclear Information System (INIS)

    This paper presents the fabrication and application of a micro-scale hybrid wicking structure in a flat polymer-based heat pipe heat spreader, which improves the heat transfer performance under high adverse acceleration. The hybrid wicking structure which enhances evaporation and condensation heat transfer under adverse acceleration consists of 100 µm high, 200 µm wide square electroplated copper micro-pillars with 31 µm wide grooves for liquid flow and a woven copper mesh with 51 µm diameter wires and 76 µm spacing. The interior vapor chamber of the heat pipe heat spreader was 30×30×1.0 mm3. The casing of the heat spreader is a 100 µm thick liquid crystal polymer which contains a two-dimensional array of copper-filled vias to reduce the overall thermal resistance. The device performance was assessed under 0–10 g acceleration with 20, 30 and 40 W power input on an evaporator area of 8×8 mm2. The effective thermal conductivity of the device was determined to range from 1653 W (m K)−1 at 0 g to 541 W (m K)−1 at 10 g using finite element analysis in conjunction with a copper reference sample. In all cases, the effective thermal conductivity remained higher than that of the copper reference sample. This work illustrates the possibility of fabricating flexible, polymer-based heat pipe heat spreaders compatible with standardized printed circuit board technologies that are capable of efficiently extracting heat at relatively high dynamic acceleration levels. (paper)

  10. Study of PTFE wick structure applied to loop heat pipe

    International Nuclear Information System (INIS)

    This study investigated the use of sintered PTFE (polytetrafluoroethylene) particles as the wick material of loop heat pipe (LHP), taking advantage of PTFE's low thermal conductivity to reduce the heat leakage problem during LHP's operation. Different PTFE particle sizes were tried to find the one that resulted in the best wick; LHP performance tests were then conducted, and PTFE's potential for application to LHP was examined. Using PTFE particles ranging from 300–500 μm in size, the best wick properties were effective pore radius of 1.7 μm, porosity of 50%, and permeability of 6.2 × 10−12 m2. LHP performance tests showed that, under typical electronic devices' operating temperature of 85 °C, the heat load reached 450 W, the thermal resistance was 0.145 °C/W, and the critical heat load (dryout heat load) reached 600 W. Compared to LHP with a nickel wick, LHP with a PTFE wick had a significantly lower operating temperature, indicating reduced heat leakage during operation, while having comparable performance; also, during the manufacturing process, a PTFE wick required lower sintering temperature, needed shorter sintering time, and had no need for hydrogen gas during sintering. The results of this study showed that, for high heat transfer capacity cooling devices, PTFE wicks possess great potential for applications to LHPs. - Highlights: • The performances of PTFE and nickel wicks in LHP are comparable for the first time. • PTFE wick allows for lower operating temperature and thus pressure in LHP system. • A wick requiring lower temperature and manufacturing cost and less time was made. • PTFE wick has potential to replace metal wick and enhance performance of LHP

  11. Selenide isotope generator for the Galileo Mission. Axially-grooved heat pipe: accelerated life test results

    International Nuclear Information System (INIS)

    The results through SIG/Galileo contract close-out of accelerated life testing performed from June 1978 to June 1979 on axially-grooved, copper/water heat pipes are presented. The primary objective of the test was to determine the expected lifetime of axially-grooved copper/water heat pipes. The heat pipe failure rate, due to either a leak or a build-up of non-condensible gas, was determined. The secondary objective of the test was to determine the effects of time and temperature on the thermal performance parameters relevant to long-term (> 50,000 h) operation on a space power generator. The results showed that the gas generation rate appears to be constant with time after an initial sharp rise although there are indications that it drops to approximately zero beyond approx. 2000 h. During the life test, the following pipe-hours were accumulated: 159,000 at 1250C, 54,000 at 1650C, 48,000 at 1850C, and 8500 at 2250C. Heated hours per pipe ranged from 1000 to 7500 with an average of 4720. Applying calculated acceleration factors yields the equivalent of 930,000 pipe-h at 1250C. Including the accelerated hours on vendor tested pipes raises this number to 1,430,000 pipe-hours at 1250C. It was concluded that, for a heat pipe temperature of 1250C and a mission time of 50,000 h, the demonstrated heat pipe reliability is between 80% (based on 159,000 actual pipe-h at 1250C) and 98% (based on 1,430,000 accelerated pipe-h at 1250C). Measurements indicate some degradation of heat transfer with time, but no detectable degradation of heat transport

  12. Sodium Variable Conductance Heat Pipe for Radioisotope Stirling Systems

    Science.gov (United States)

    Tarau, Calin; Anderson, William G.; Walker, Kara

    2009-01-01

    In a Stirling radioisotope system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the converter stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, and also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) has been designed to allow multiple stops and restarts of the Stirling convertor in an Advanced Stirling Radioisotope Generator (ASRG). When the Stirling convertor is turned off, the VCHP will activate when the temperatures rises 30 C above the setpoint temperature. A prototype VCHP with sodium as the working fluid was fabricated and tested in both gravity aided and against gravity conditions for a nominal heater head temperature of 790 C. The results show very good agreement with the predictions and validate the model. The gas front was located at the exit of the reservoir when heater head temperature was 790 C while cooling was ON, simulating an operating Advanced Stirling Converter (ASC). When cooling stopped, the temperature increased by 30 C, allowing the gas front to move past the radiator, which transferred the heat to the case. After resuming the cooling flow, the front returned at the initial location turning OFF the VCHP. The against gravity working conditions showed a colder reservoir and faster transients.

  13. Miniature Loop Heat Pipe with Multiple Evaporators and Multiple Condensers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Loop Heat Pipe (LHP) is a high performance heat transport device using capillary forces to circulate the working fluid in a closed loop. Conventional LHPs usually...

  14. A Novel Heat Pipe Plate for Passive Thermal Control of Fuel Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project aims to develop a lightweight, highly thermally and electrically conductive heat pipe plate for passive removal of the heat from the individual...

  15. A study of start-up characteristics of a potassium heat pipe from the frozen state

    Science.gov (United States)

    Jang, Jong Hoon

    1992-01-01

    The start up characteristics of a potassium heat pipe were studied both analytically and experimentally. Using the radiation heat transfer mode the heat pipe was tested in a vacuum chamber. The transition temperature calculated for potassium was then compared with the experimental results of the heat pipe with various heat inputs. These results show that the heat pipe was inactive until it reached the transition temperature. In addition, during the start up period, the evaporator experienced dry-out with a heat input smaller than the capillary limit calculated at the steady state. However, when the working fluid at the condensor was completely melted, the evaporation was rewetted without external aid. The start up period was significantly reduced with a large heat input.

  16. Computer program grade for design and analysis of graded-porosity heat-pipe wicks

    Science.gov (United States)

    Eninger, J. E.

    1974-01-01

    A computer program for numerical solution of differential equations that describe heat pipes with graded-porosity fibrous wicks is discussed. A mathematical problem is provided with a summary of the input and output steps used to solve it. The program is also applied to the analysis of a typical heat pipe.

  17. Impact of the amount of working fluid in loop heat pipe to remove waste heat from electronic component

    Directory of Open Access Journals (Sweden)

    Smitka Martin

    2014-03-01

    Full Text Available One of the options on how to remove waste heat from electronic components is using loop heat pipe. The loop heat pipe (LHP is a two-phase device with high effective thermal conductivity that utilizes change phase to transport heat. It was invented in Russia in the early 1980’s. The main parts of LHP are an evaporator, a condenser, a compensation chamber and a vapor and liquid lines. Only the evaporator and part of the compensation chamber are equipped with a wick structure. Inside loop heat pipe is working fluid. As a working fluid can be used distilled water, acetone, ammonia, methanol etc. Amount of filling is important for the operation and performance of LHP. This work deals with the design of loop heat pipe and impact of filling ratio of working fluid to remove waste heat from insulated gate bipolar transistor (IGBT.

  18. Impact of the amount of working fluid in loop heat pipe to remove waste heat from electronic component

    Science.gov (United States)

    Smitka, Martin; Kolková, Z.; Nemec, Patrik; Malcho, M.

    2014-03-01

    One of the options on how to remove waste heat from electronic components is using loop heat pipe. The loop heat pipe (LHP) is a two-phase device with high effective thermal conductivity that utilizes change phase to transport heat. It was invented in Russia in the early 1980's. The main parts of LHP are an evaporator, a condenser, a compensation chamber and a vapor and liquid lines. Only the evaporator and part of the compensation chamber are equipped with a wick structure. Inside loop heat pipe is working fluid. As a working fluid can be used distilled water, acetone, ammonia, methanol etc. Amount of filling is important for the operation and performance of LHP. This work deals with the design of loop heat pipe and impact of filling ratio of working fluid to remove waste heat from insulated gate bipolar transistor (IGBT).

  19. Post-Test Analysis of a 10-Year Sodium Heat Pipe Life Test

    Science.gov (United States)

    Rosenfeld, John H.; Locci, Ivan E.; Sanzi, James L.; Hull, David R.; Geng, Steven M.

    2011-01-01

    High-temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, Stirling cycle heat sources; and with the resurgence of space nuclear power both as reactor heat removal elements and as radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly, long-term materials compatibility is being evaluated through the use of high-temperature life test heat pipes. Thermacore, Inc., has carried out a sodium heat pipe 10-year life test to establish long-term operating reliability. Sodium heat pipes have demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 87,000 hr (10 years) at nearly 700 C. These life test results have demonstrated the potential for high-temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability. Detailed design specifications, operating history, and post-test analysis of the heat pipe and sodium working fluid are described. Lessons learned and future life test plans are also discussed.

  20. Performance-Governing Transport Mechanisms for Heat Pipes at Ultra-thin Form Factors

    OpenAIRE

    Yadavalli, Y.; Weibel, J. A.; Garimella, S V

    2015-01-01

    Heat pipes and vapor chamber heat spreaders offer a potential solution to the increasing thermal management challenges in thin-form-factor mobile computing platforms, where efficient spreading is required to simultaneously prevent overheating of internal components and formation of hot regions on the device exterior surfaces. Heat pipe performance limitations unique to such ultrathin form factors and the key heat transfer mechanisms governing the performance must be characterized. A thermal r...

  1. BOILING OF WATER AND ORGANIC LIQUIDS ON LOW-TEMPERATURE POROUS SURFACES OF HEAT PIPES

    OpenAIRE

    Шаповал, Андрій Андрійович; Панов, Євген Миколайович; Сауліна, Юлія Валеріївна; Романчук, Борис Васильович; Трубійчук, Р. П.

    2015-01-01

    The experimental study results of the influence of porous metal fiber structures on the intensity of two-phase heat transfer of water and acetone boiling on porous surfaces in conditions of free movement and capillary transport of liquids are presented in the article. The experiments were realized using specially designed experimental installation simulated the operating conditions of heat pipes and thermosyphons. Such conditions are typical for two-phase heat transfer devices – heat pipes an...

  2. Closed-form analytical solutions of high-temperature heat pipe startup and frozen startup limitation

    Science.gov (United States)

    Cao, Y.; Faghri, A.

    1992-01-01

    Previous numerical and experimental studies indicate that the high-temperature heat pipe startup process is characterized by a moving hot zone with relatively sharp fronts. Based on the above observation, a flat-front model for an approximate analytical solution is proposed. A closed-form solution related to the temperature distribution in the hot zone and the hot zone length as a function of time are obtained. The analytical results agree well with the corresponding experimental data, and provide a quick prediction method for the heat pipe startup performance. Finally, a heat pipe limitation related to the frozen startup process is identified, and an explicit criterion for the high-temperature heat pipe startup is derived. The frozen startup limit identified in this paper provides a fundamental guidance for high-temperature heat pipe design.

  3. Heat pipe cooling system for safer storage of spent fuel in nuclear plant

    International Nuclear Information System (INIS)

    This paper proposes completely passive cooling system utilizing heat pipe thermal diode character and natural air convection cooling of condenser, for cooling spent fuel pool. Detail analysis of various heat pipe design cases to determine the best design concept in terms of cooling power, construction and cost has been presented. The best design when considering thermal safety margin and cost is the heat pipe cooling system with capacity of 0.9 MW, 1,662 heat pipe modules. For this design case, water temperature will reach to peak 68degC after 75 hours, and then it will saturate at 50degC after 2,000 hours. The proposed heat pipe systems can be operated completely passive which will provide safer operational environment to nuclear power plants. (author)

  4. Heat pipe technology: a bibliography with abstracts. Annual supplement, 1973. [323 citations

    Energy Technology Data Exchange (ETDEWEB)

    1973-01-01

    A bibliography is given listing 229 references with abstracts and 94 patents dealing with applications of heat pipe technology. Topics covered include: heat exchangers for heating and air conditioning; electronics cooling; temperature control of spacecraft; heat transfer in thermoelectric power generators; heat transfer in nuclear reactors; measurement of thermophysical properties; solar collectors; cooling engines; electrohydrodynamic phenomena; and vapor laser ovens. (GRA)

  5. Parametric analysis of loop heat pipe operation: a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Launay, Stephane; Sartre, Valerie; Bonjour, Jocelyn [Centre de Thermique UMR 5008 CNRS-INSA-Universite Lyon 1, Institut National des Sciences Appliquees, Bat. Sadi Carnot, 9 rue de la Physique, 69 621 Villeurbanne cedex (France)

    2007-07-15

    Loop heat pipes (LHPs) are heat transfer devices whose operating principle is based on the evaporation/condensation of a working fluid, and which use the capillary pumping forces to ensure the fluid circulation. Their major advantages as compared to heat pipes are an ability to operate against gravity and a greater maximum heat transport capability. In this paper, a literature review is carried out in order to investigate how various parameters affect the LHP operational characteristics. This review is based on the most recent published experimental and theoretical studies. After a reminder of the LHP operating principle and thermodynamic cycle, their operating limits are described. The LHP thermal resistance and maximum heat transfer capability are affected by the choice of the working fluid, the fill charge ratio, the porous wick geometry and thermal properties, the sink and ambient temperature levels, the design of the evaporator and compensation chamber, the elevation and tilt, the presence of non-condensable gases, the pressure drops of the fluid along the loop. The overall objective for this paper is to point the state-of-the-art for the related technology for future design and applications, where the constraints related to the LHPs are detailed and discussed. (author) [French] Les boucles diphasiques a pompage capillaire sont des systemes dont le principe de fonctionnement est base sur l'evaporation/condensation d'un fluide et qui utilisent les forces de capillarite pour faire circuler le fluide dans la boucle. En comparaison des caloducs, les principaux avantages des boucles diphasiques a pompage capillaire sont une aptitude a vaincre les forces de gravite, lorsque le systeme est en position defavorable, et une puissance maximale transferable superieure. La presente etude bibliographique, basee sur les travaux experimentaux et theoriques les plus recents, a pour but est de comprendre comment differents parametres influencent le comportement de la

  6. The cavity heat pipe Stirling receiver for space solar dynamics

    Science.gov (United States)

    Kesseli, James B.; Lacy, Dovie E.

    1989-01-01

    The receiver/storage unit for the low-earth-orbiting Stirling system is discussed. The design, referred to as the cavity heat pipe (CHP), has been optimized for minimum specific mass and volume width. A specific version of this design at the 7-kWe level has been compared to the space station Brayton solar dynamic design. The space station design utilizes a eutectic mixture of LiF and CaF2. Using the same phase change material, the CHP has been shown to have a specific mass of 40 percent and a volume of 5 percent of that of the space station Brayton at the same power level. Additionally, it complements the free-piston Stirling engine in that it also maintains a relatively flat specific mass down to at least 1 kWe. The technical requirements, tradeoff studies, critical issues, and critical technology experiments are discussed.

  7. Fuel and cladding nano-technologies based solutions for long life heat-pipe based reactors

    Energy Technology Data Exchange (ETDEWEB)

    Popa-Simil, L. [LAVM LLC, Los Alamos (United States)

    2012-07-01

    A novel nuclear reactor concept, unifying the fuel pipe with fuel tube functionality has been developed. The structure is a quasi-spherical modular reactor, designed for a very long life. The reactor module unifies the fuel tube with the heat pipe and a graphite beryllium reflector. It also uses a micro-hetero-structure that allows the fission products to be removed in the heat pipe flow and deposited in a getter area in the cold zone of the heat pipe, but outside the neutron flux. The reactor operates as a breed and burn reactor - it contains the fuel pipe with a variable enrichment, starting from the hot-end of the pipe, meant to assure the initial criticality, and reactor start-up followed by area with depleted uranium or thorium that get enriched during the consumption of the first part of the enriched uranium. (authors)

  8. Heat transfer augmentation in double pipe heat exchanger using mechanical turbulators

    Science.gov (United States)

    Kamboj, Kushal; Singh, Gurjeet; Sharma, Rohit; Panchal, Dilbagh; Hira, Jaspreet

    2016-05-01

    The work presented here focuses on heat transfer augmentation by means of divergent-convergent spring turbulator (the enhancement device). Aim of the present work is to find such an optimum pitch at which the augmentation in heat transfer is maximum and the amount of power consumption is minimum, so that an economic design can be created with maximum thermal efficiency. So, the concept of pitch variation is introduced, which is defined as the horizontal distance between two consecutive turbulators. It describes that, the lesser is the pitch the more number of turbulators that can be inserted in inner pipe of double pipe heat exchanger, hence more will be the friction factor. This physics increases convective ability of the heat transfer process from the surface of inner pipe. There is a certain limit to which a pitch can be decreased, lesser the pitch the more the pressure drop and friction factor and hence the more will be the pumping power requirement to maintain a desired mass flow rate of hot water. Analysis of thermal factors such as Nusselts number, friction factor, with different pitches of divergent convergent spring turbulators of circular cross-section 15, 10, and 5 cm at Reynolds's number ranging between 9000 < Re < 40,000 is done graphically.

  9. Heat transfer augmentation in double pipe heat exchanger using mechanical turbulators

    Science.gov (United States)

    Kamboj, Kushal; Singh, Gurjeet; Sharma, Rohit; Panchal, Dilbagh; Hira, Jaspreet

    2016-05-01

    The work presented here focuses on heat transfer augmentation by means of divergent-convergent spring turbulator (the enhancement device). Aim of the present work is to find such an optimum pitch at which the augmentation in heat transfer is maximum and the amount of power consumption is minimum, so that an economic design can be created with maximum thermal efficiency. So, the concept of pitch variation is introduced, which is defined as the horizontal distance between two consecutive turbulators. It describes that, the lesser is the pitch the more number of turbulators that can be inserted in inner pipe of double pipe heat exchanger, hence more will be the friction factor. This physics increases convective ability of the heat transfer process from the surface of inner pipe. There is a certain limit to which a pitch can be decreased, lesser the pitch the more the pressure drop and friction factor and hence the more will be the pumping power requirement to maintain a desired mass flow rate of hot water. Analysis of thermal factors such as Nusselts number, friction factor, with different pitches of divergent convergent spring turbulators of circular cross-section 15, 10, and 5 cm at Reynolds's number ranging between 9000 graphically.

  10. The service life of plastic pipe in the polyurethane foam insulation, used for heating systems

    OpenAIRE

    Petrakov G.P.

    2012-01-01

    The interest in the polymer (plastic) pipes in terms of their use in district heating networks of large cities settlements and neighborhoods as flexible pre-insulated pipes in the polyurethane foam insulation channel free laying increased in Russia during the last decade. Pipes made of PE-RT (polyethylene of Raised Temperature Resistance) and PE-X (cross-linked polyethylene) are the most promising plastic pipes.Pipes made of PE-RT have long term hydrostatic resistance (ability to prevent the ...

  11. Temperature Oscillation in a Loop Heat Pipe with Gravity Assist

    Science.gov (United States)

    Ku, Jentung; Garrison, Matt; Patel, Deepak; Ottenstein, Laura; Robinson, Frank

    2014-01-01

    ATLAS Laser Thermal Control System (LTCS) thermal vacuum testing where the condenser-radiator was placed in a vertical position, it was found that the loop heat pipe (LHP) reservoir required much more control heater power than the analytical model had predicted. The required control heater power was also higher than the liquid subcooling entering the reservoir using the measured temperatures and the calculated mass flow rate based on steady state LHP operation. This presentation describes the investigation of the LHP behaviors under a gravity assist mode with a very cold radiator sink temperature and a large thermal mass attached to the evaporator. It is concluded that gravity caused the cold liquid to drop from the condenser-radiator to the reservoir, resulting in a rapid decrease of the reservoir temperature. When the reservoir temperature was increasing, a reverse flow occurred in the liquid line, carrying warm liquid to the condenser-radiator. Both events consumed the reservoir control heater power. The fall and rise of the reservoir temperature also caused the net heat input to the evaporator to vary due to the release and storage of the sensible heat of the thermal mass. The combination of these effects led to a persistent reservoir temperature oscillation and a repeated influx of cold liquid from the condenser. This was the root cause of the extraordinary high control heater power requirement in the LTCS TV test. Without gravity assist, such a persistent temperature oscillation will not be present.

  12. Heat transport in the Hadean mantle: From heat pipes to plates

    Science.gov (United States)

    Kankanamge, Duminda G. J.; Moore, William B.

    2016-04-01

    Plate tectonics is a unique feature of Earth, and it plays a dominant role in transporting Earth's internally generated heat. It also governs the nature, shape, and the motion of the surface of Earth. The initiation of plate tectonics on Earth has been difficult to establish observationally, and modeling of the plate breaking process has not consistently accounted for the nature of the preplate tectonic Earth. We have performed numerical simulations of heat transport in the preplate tectonic Earth to understand the transition to plate tectonic behavior. This period of time is dominated by volcanic heat transport called the heat pipe mode of planetary cooling. These simulations of Earth's mantle include heat transport by melting and melt segregation (volcanism), Newtonian temperature-dependent viscosity, and internal heating. We show that when heat pipes are active, the lithosphere thickens and lithospheric isotherms are kept flat by the solidus. Both of these effects act to suppress plate tectonics. As volcanism wanes, conduction begins to control lithospheric thickness, and large slopes arise at the base of the lithosphere. This produces large lithospheric stress and focuses it on the thinner regions of the lithosphere resulting in plate breaking events.

  13. Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat Pipe

    Science.gov (United States)

    Mireles, Omar R.; Houts, Michael G.

    2011-01-01

    Compact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.

  14. Theoretical and experimental investigation of plate screen mesh heat pipe solar collector

    International Nuclear Information System (INIS)

    Highlights: • Experimental and computer simulation are performed for wicked heat pipe solar collectors. • Outdoor tests are conducted to compare its performance at different period of the year. • Modest improvement of the collector is achievement by adding fins to the condenser region. • Mesh number of heat pipe porous structure is an important factor in collector design. • Water slightly outperform methanol for such design and operating conditions. - Abstract: Heat pipes are efficient heat transfer devices for solar hot water heating systems. However, the effective downward transfer of solar energy in an integrated heat pipe system provides increased design and implementation options. There is a lack of literature about flat plate wicked assisted heat pipe solar collector, especially with the presence of finned water-cooled condenser wicked heat pipes for solar energy applications. In this paper the consequence of incorporating fins arrays into the condenser region of screen mesh heat pipe solar collector is investigated. An experimental and a transient theoretical model are conducted to compare the performances of solar heating system at different period of the year. A good agreement is shown between the model and the experiment. Two working fluids are investigated (water and methanol) and results reveal that water slightly outperforms methanol with a collector instantaneous efficiency of nearly 60%. That modest improvement is achieved by adding fins to the condenser region of the heat pipes. Results show that the collector efficiency increase as the number of fins increases (upon certain number) and reveal that the mesh number is an important factor which affect the overall collector efficiency. An optimal heat pipe mesh number of 100 meshes/in. with two layers appears to be favorable in such collectors for their design and operating conditions

  15. Vapor-modulated heat pipe report. Flight data analysis and further development of variable-conductance heat pipes. [design analysis and performance tests

    Science.gov (United States)

    Eninger, J. E.; Fleischman, G. L.; Luedke, E. E.

    1975-01-01

    The design and testing of a heat pipe for spacecraft application is presented. The application in mind calls for heat loads up to 20 watts, a set-point temperature of 294K, and a sink that varies from -220K to nearly as high as the set-point. The overall heat pipe length is 137 cm. Two basically different mechanisms of achieving variable conductance in the pipe by vapor-flow throttling were studied. In one, the thermal resistance between the heat source and sink is due to a saturation-temperature drop corresponding to the vapor-pressure drop developed across the valve. In the other, the pressure difference across the valve induces capillary groove and wick dry out in an evaporation region, and thus results in an increased thermal resistance. This mechanism was selected for fabrication and testing. The pipe is a stainless-steel/methanol two-heat-pipe system. Results are presented and discussed. Engineering drawings and specifications of the pipe are shown.

  16. The Experimental Study of the Thermal Performance of Heat Pipe using CuO/Water Nanofluid.

    OpenAIRE

    Mangal Singh Lodhi; Prof. R. C. Gupta

    2013-01-01

    This paper presents the enhancement of the thermal performance of a heat pipe charged with nanofluid. The CuO/Water nanofluid served as the working fluid with three concentrations by volume 1g/L, 5g/L and 10g/L in heat pipe. The heat pipe is fabricated by a straight copper tube with an outer diameter 18 mm, thickness 1mm and length of 475 mm. This paper presents a discussion on the effect of various performing parameters by varying different heat inputs as well as fluid concentration as menti...

  17. A modeling approach for district heating systems with focus on transient heat transfer in pipe networks

    DEFF Research Database (Denmark)

    Mohammadi, Soma; Bojesen, Carsten

    2015-01-01

    operational temperature. However, in order to implement low temperature concept for existing DH systems, there is a need to apply a stepwise changes in the existing systems. This study emphasis on improving the existing DH pipes networks. For this purpose the first step is developing a model, which comprises...... approximately 14 km pipelines (supply and return pipes). At the first stage, the Studstrup DH system is developed in TERMIS, which is commercial software for district heating system simulation, and then the developed model is validated and compared with the results obtained from TERMIS and measurements. The...... TERMIS model is already validated towards measurements. This paper explains the developed model, which is going to be used for performing possible scenarios to improve the existing DHN from heat and temperature loss viewpoints. Moreover, it provides a platform to add and extend different aspect of DH...

  18. Condensation heat transfer in rotating heat pipes in the presence of a non-condensable gas

    Science.gov (United States)

    Daniels, T. C.; Medwell, J. O.; Williams, R. J.

    1977-01-01

    An analysis of condensation problems in rotating heat pipes containing vapors with different concentrations of non-condensable gases is given. In situations such as this, temperature and concentration gradients are set up in the vapor-gas mixture. There is a transport of mass due to temperature gradients accompanied by an energy transport phenomena due to a concentration gradient. A Nusselt type analysis is not suited to this type of problem; however, a boundary layer type approach has successfully been used to analyze stationary condensation systems with non-condensable gases present. The present boundary layer analysis is presented for condensation processes on the inside of a rotating heat pipe in the presence of non-condensable gases.

  19. Design considerations for CRBRP heat transport system piping operating at elevated temperatures

    International Nuclear Information System (INIS)

    The heat transport system sodium piping for the Clinch River Breeder Reactor Plant (CRBRP) within the reactor containment building must withstand high temperatures for long periods of time. Each phase of the mechanical design process of the piping system is influenced by elevated temperature considerations which include material thermal creep effects, ratchetting caused by rapid temperature transients and stress relaxation, and material degradation effects. The structural design philosophy taken to design the CRBRP piping operating in a high temperature environment is described. The resulting design of the heat transport system piping is presented along with a discussion of special features that resulted from the elevated temperature considerations

  20. Combination study of operation characteristics and heat transfer mechanism for pulsating heat pipe

    International Nuclear Information System (INIS)

    Pulsating heat pipe (PHP) is becoming a promising heat transfer device for the application like electronics cooling. However, due to its complicated operation mechanism, the heat transfer properties of the PHP still have not been fully understood. This study experimentally investigated on a closed-loop PHP charged with four types of working fluids, deionized water, methanol, ethanol and acetone. Combined with the visualization experimental results from the open literature, the operation characteristics and the corresponding heat transfer mechanisms for different heat inputs (5 W up to 100 W) and different filling ratios (20% up to 95%) have been presented and elaborated. The results show that heat-transfer mechanism changed with the transition of operation patterns; before valid oscillation started, the thermal resistance was not like that described in the open literature where it decreased almost linearly, but would rather slowdown descending or even change into rise first before further decreasing (i.e. an inflection point existed); when the heat input further increased to certain level, e.g. 65 W or above, there presented a limit of heat-transfer performance which was independent of the types of working fluids and the filling ratios, but may be related to the structure, the material, the size and the inclination of the PHP. - Highlights: •The thermal mechanisms altered accordingly with the operation features in the PHP. •Unlike conventional heat pipes, continuous temperature soaring would not happen in the PHP. •Before the oscillation start-up, there existed a heat-transfer limit for the relatively stagnated flow in the PHP. •A limit of thermal performance existed in the PHP at relatively high heat inputs

  1. Enhanced heat transfer performances of molten salt receiver with spirally grooved pipe

    International Nuclear Information System (INIS)

    The enhanced heat transfer performances of solar receiver with spirally grooved pipe were theoretically investigated. The physical model of heat absorption process was proposed using the general heat transfer correlation of molten salt in smooth and spirally grooved pipe. According to the calculation results, the convective heat transfer inside the receiver can remarkably enhance the heat absorption process, and the absorption efficiency increased with the flow velocity and groove height, while the wall temperature dropped. As the groove height increased, the heat losses of convection and radiation dropped with the decrease of wall temperature, and the average absorption efficiency of the heat receiver can be increased. Compared with the heat receiver with smooth pipe, the heat absorption efficiency of heat receiver with spirally grooved pipe e/d = 0.0475 can rise for 0.7%, and the maximum bulk fluid temperature can be increased for 31.1 °C. As a conclusion, spirally grooved pipe can be a very effective way for heat absorption enhancement of solar receiver, and it can also increase the operating temperature of molten salt. - Highlights: • Spirally grooved tube is a very effective way for solar receiver enhancement. • Heat absorption model of receiver is proposed with general heat transfer correlation. • Spirally groove tube increases absorption efficiency and reduces wall temperature. • Operating temperature of molten salt remarkably increases with groove height. • Heat absorption performance is promoted for first and second thermodynamics laws

  2. Phase change driving mechanism and modeling for heat pipe with porous wick

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; LIU ZhiChun; YANG Kun; TU ZhengKai

    2009-01-01

    According to heat pipe theory,capillary force is the only driving force for the circle of working fluid in heat pipe with porous wick.By developing a simulating circuit of liquid and vapor flow in heat pipe with porous wick,this paper presents a new driving mechanism which is from phase change of fluid.Furthermore,by analyzing transport process of working fluid between evaporation and condensation in terfaces,a mathematical model is developed to describe this driving mechanism.Besides,calculating examples are given for heat pipe with water as working fluid to predict its driving force and flow resis tance.By applying the model presented in the paper,thermal design and calculation for heat pipe with porous wick,especially for miniature heat pipe,can be made correctly,and phase change driving me chanism of working fluid can be explained,which thereby leads to a better understanding of heat transfer limitation of heat pipe with porous wick.

  3. Numerical study of the conjugate heat transfer in a horizontal pipe heated by Joulean effect

    Directory of Open Access Journals (Sweden)

    Touahri Sofiane

    2012-01-01

    Full Text Available The three dimensional mixed convection heat transfer in a electrically heated horizontal pipe conjugated to a thermal conduction through the entire solid thickness is investigated by taking into account the thermal dependence of the physical properties of the fluid and the outer heat losses. The model equations of continuity, momentum and energy are numerically solved by the finite volume method. The pipe thickness, the Prandtl and the Reynolds numbers are fixed while the Grashof number is varied from 104to107. The results obtained show that the dynamic and thermal fields for mixed convection are qualitatively and quantitatively different from those of forced convection, and the local Nusselt number at the interface solid-fluid is not uniform: it has considerable axial and azimuthally variations. The effect of physical variables of the fluid depending on temperature is significant, which justifies its inclusion. The heat transfer is quantified by the local and average Nusselt numbers. We found that the average Nusselt number of solid-fluid interface of the duct increases with the increase of Grashof number. We have equally found out that the heat transfer is improved thanks to the consideration of the thermo dependence of the physical properties. We have tried modelling the average Nusselt number as a function of Richardson number. With the parameters used, the heat transfer is quantified by the correlation: NuA=12.0753 Ri0.156

  4. Design and development of high temperature heat pipes and thermosiphons for passive heat removal from compact high temperature reactor

    International Nuclear Information System (INIS)

    Compact High Temperature Reactor (CHTR) is 100 kWth, lead-bismuth eutectic (LBE) cooled reactor having several advanced passive safety features to enable its operation as compact power pack. It will also facilitate demonstration of technologies for high temperature process heat applications. In CHTR heat is transferred from primary to secondary side by means of high temperature heat pipes. Heat pipes are also employed to remove heat under postulated accident scenarios. Thus, reliable operation of heat pipes is essential for the safe working of the reactor. In this respect, computer codes have been developed for design and simulation of high temperature heat pipes. This includes design codes using empirical correlations as well as simplified FEM models for system level analysis. To verify the operation of these heat pipes under various steady state and transient conditions full CFD analysis is essential. This has been done by using a commercial CFD code by incorporating user defined functions (UDFs) which address the saturated nature of the vapour phase and the vapour wick interface conditions. A three dimensional transient numerical model has been developed to predict the vapor core, wall temperatures, vapor pressure, and vapor velocity in the screen mesh wick of sodium heat pipe. This thesis will give an outline of all the developed models and compared the predicted results against the experimental data. (author)

  5. HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR CHARACTERISTICS OF A GRAVITY ASSISTED BAFFLED SHELL AND HEAT-PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    P. Raveendiran

    2015-06-01

    Full Text Available The heat transfer coefficients and friction factors of a baffled shell and heat pipe heat exchanger with various inclination angles were determined experimentally; using methanol as working fluid and water as heat transport fluid were reported. Heat pipe heat exchanger reported in this investigation have inclination angles varied between 15o and 60o for different mass flow rates and temperature at the shell side of the heat exchanger. All the required parameters like outlet temperature of both hot and cold side of heat exchanger and mass flow rate of fluids were measured using an appropriate instrument. Different tests were performed from which condenser side heat transfer coefficient and friction factor were calculated. In all operating conditions it has been found that the heat transfer coefficient increases by increasing the mass flow rate and angle of inclination. The reduction in friction factor occurs when the Reynolds number is increased. The overall optimum experimental effectiveness of GABSHPHE has found to be 42% in all operating conditioning at ψ = 45o.

  6. Experimental and numerical investigation of a cross flow air-to-water heat pipe-based heat exchanger used in waste heat recovery

    OpenAIRE

    J. Ramos; Chong, A.; Jouhara, H

    2016-01-01

    This paper applies CFD modelling and numerical calculations to predict the thermal performance of a cross flow heat pipe based heat exchanger. The heat exchanger under study transfers heat from air to water and it is equipped with six water-charged wickless heat pipes, with a single-pass flow pattern on the air side (evaporator) and two flow passes on the water side (condenser). For the purpose of CFD modelling, the heat pipes were considered as solid devices of a known thermal conductivity w...

  7. Design and analysis of megawatt-class heat-pipe reactor concepts

    International Nuclear Information System (INIS)

    There is growing interest in finding an alternative to diesel-powered systems at locations removed from a reliable electrical grid. One promising option is a 1- to 10-MW mobile reactor system, that could provide robust, self-contained, and long-term (≥ 5 years) power in any environment. The reactor and required infrastructure could be transported to any location within one or a few standard transport containers. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than 'traditional' reactors that rely on pumped coolant through the core. This paper examines a heat pipe reactor that is fabricated and shipped as six identical core segments. Each core segment includes a heat-pipe-to-gas heat exchanger that is coupled to the condenser end of the heat pipes. The reference power conversion system is a CO2-Brayton system. The segments by themselves are deeply subcritical during transport, and they would be locked into an operating configuration (with control inserted) at the final destination. Two design options are considered: a near-term option and an advanced option. The near-term option is a 5-MWt concept that uses uranium-dioxide fuel, a stainless-steel structure, and potassium as the heat-pipe working fluid. The advanced option is a 15-MWt concept that uses uranium-nitride fuel, a molybdenum/TZM structure, and sodium as the heat-pipe working fluid. The materials used in the advanced option allow for higher temperatures and power densities, and enhanced power throughput in the heat pipes. Higher powers can be obtained from both concepts by increasing the core size and the number of heat pipes. (authors)

  8. The impacts of cooling construction on the ability distract the heat of condensation part of the heat pipe

    Directory of Open Access Journals (Sweden)

    Gavlas S.

    2013-04-01

    Full Text Available Heat pipes as cooling devices have a high potential. Their power to affect a variety of factors – the vapour pressure, the amount of media work etc. Itis therefore necessary to verify the calculated parameters also practically. To determine the performance of transmitted heat pipe is the best calorimetric method. When it is out of the flow and the temperature difference the cooling part of the heat pipe determines its transmitted power. The contribution is focused on comparison of two types of coolers. The first type is looped capillary cooler for the condenser section. The small diameter capillary is secured high coolant turbulence and hence heat dissipation. The second type is non-contact cooling, where cooling fluid washes direct heat pipe wall.

  9. Sintered Nickel Powder Wicks for Flat Vertical Heat Pipes

    Directory of Open Access Journals (Sweden)

    Geir Hansen

    2015-03-01

    Full Text Available The fabrication and performance of wicks for flat heat pipe applications produced by sintering a filamentary nickel powder has been investigated. Tape casting was used as an intermediate step in the wick production process. Thermogravimetric analysis was used to study the burn-off of the organic binder used and to study the oxidation and reduction processes of the nickel. The wicks produced were flat, rectangular and intended for liquid transport in the upwards vertical direction. Rate-of-rise experiments using heptane were used to test the flow characteristics of the wicks. The wick porosities were measured using isopropanol. The heat transfer limitation constituted by the vapour static pressure and the capillary pressure was discussed. The influence on wick performance by using pore former in the manufacturing was studied. When Pcap/Psat > 1, the use of a pore former to increase the wick permeability will always improve the wick performance. When Pcap/Psat < 1, it was shown that if the effective pore radius and the permeability increase with an equal percentage the overall influence on the wick capacity is negative. A criterion for a successful pore former introduction is proposed and the concept of a pore former evaluation plot is presented.

  10. Development of inspection and repairing technology for FBR heat exchanger pipes

    International Nuclear Information System (INIS)

    A hybrid optical fiber scope and a laser processing head were combined with an eddy current testing unit for the inspection and repairing for Fast Breeder Reactor's heat exchanger pipes. The project proposes an effective cost reduction method for maintenance of FBR by extension of the heat exchanger's lifetime. By the end of March 2010, a prototype probing system for heat exchanger pipes will be completed. (author)

  11. Modeling, Designing, Fabricating, and Testing of Channel Panel Flat Plate Heat Pipes

    OpenAIRE

    Harris, James R

    2008-01-01

    Flat plate heat pipes are very efficient passive two-phase heat transport devices. Their high e'ciency and low mass are desirable in the aerospace and electronics industries. The highly competitive nature of the thermal management industry results in little awareness of the capabilities of at plate heat pipes, which has resulted in only a few applications of the technology. In the year 2000 a research and development project sponsored by Space Dynamics Laboratory was launched to investigate b...

  12. Waste Heat Recovery by Heat Pipe Air-Preheater to Energy Thrift from the Furnace in a Hot Forging Process

    Directory of Open Access Journals (Sweden)

    Lerchai Yodrak

    2010-01-01

    Full Text Available Problem statement: Currently, the heat pipe air-preheater has become importance equipment for energy recovery from industrial waste heat because of its low investment cost and high thermal conductivity. Approach: This purpose of the study was to design, construct and test the waste heat recovery by heat pipe air-preheater from the furnace in a hot brass forging process. The mathematical model was developed to predict heat transfer rate and applied to compute the heat pipe air-preheater in a hot brass forging process. The heat pipe air-preheater was designed, constructed and tested under medium temperature operating conditions with inlet hot gas ranging between 370-420°C using water as the working fluid with 50% filling by volume of evaporator length. Results: The experiment findings indicated that when the hot gas temperature increased, the heat transfer rate also increased. If the internal diameter increased, the heat transfer rate increased and when the tube arrangement changed from inline to staggered arrangement, the heat transfer rate increased. Conclusion/Recommendations: The heat pipe air-preheater can reduced the quantity of using gas in the furnace and achieve energy thrift effectively.

  13. Experimental and Exergy Analysis of A Double Pipe Heat Exchanger for Parallel Flow Arrangement

    Directory of Open Access Journals (Sweden)

    Parth P. Parekh

    2014-07-01

    Full Text Available This paper presents For Experimental and Exergy Analysis of a Double Pipe Heat Exchanger for Parallel- flow Arrangement. The Double pipe heat exchanger is one of the Different types of heat exchangers. double-pipe exchanger because one fluid flows inside a pipe and the other fluid flows between that pipe and another pipe that surrounds the first.In a parallel flow, both the hot and cold fluids enter the Heatexchanger at same end andmove in same direction. The present work is taken up to carry experimental work and the exergy analysis based on second law analysis of a Double-Pipe Heat Exchanger. In experimental set up hot water and cold water will be used working fluids. The inlet Hot water will be varied from 40 0C and 50 0C and cold water temperature will be varied from between 15 and 20 0C. It has been planned to find effects of the inlet condition of both working fluid flowing through the heat exchanger on the heat transfer characteristics, entropy generation, and Exergy loss. The Mathematical modelling of heat exchanger will based on the conservation equation of mass, energy and based on second law of thermodynamics to find entropy generation and exergy losses.

  14. The Experimental Study of the Thermal Performance of Heat Pipe using CuO/Water Nanofluid.

    Directory of Open Access Journals (Sweden)

    Mangal Singh Lodhi

    2013-08-01

    Full Text Available This paper presents the enhancement of the thermal performance of a heat pipe charged with nanofluid. The CuO/Water nanofluid served as the working fluid with three concentrations by volume 1g/L, 5g/L and 10g/L in heat pipe. The heat pipe is fabricated by a straight copper tube with an outer diameter 18 mm, thickness 1mm and length of 475 mm. This paper presents a discussion on the effect of various performing parameters by varying different heat inputs as well as fluid concentration as mentioned above. The nanoparticles have observed significant effect on the enhancement of thermal performance of heat pipe by increasing fluid concentration as well as different heat inputs. Experimental results show that at a heating power of 80 W, the optimal thermal conductivity and heat transfer rate for CuO/Water nanofluid heat pipe are 50.46% and 1.75% respectively, which are better than that of pipes using pure water as the working fluid.

  15. Electricity eliminates rust from district heat pipes. The new deoxidation method works on radiators

    Energy Technology Data Exchange (ETDEWEB)

    Sonninen, R.; Leisio, C.

    1996-11-01

    Oxygen dissolving in district heating water through district heat pipes and pipe joints made of plastic corrodes many small and medium-size district heating systems, resulting in heat cuts in the buildings connected to these systems. IN some cases, corrosion products have even circulated back to district heating power plants, thus hampering heat generation in the worst of cases. People residing in blocks of flats where some radiator components are made of plastic also face a similar problem, though on a smaller scale. A small and efficient electrochemical deoxidation cell has now been invented to eliminate this nuisance, which occurs particularly in cold winter weather. (orig.)

  16. Pressure Profiles in a Loop Heat Pipe Under Gravity Influence

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

  17. Analysis of fluid flow and heat transfer in a double pipe heat exchanger with porous structures

    International Nuclear Information System (INIS)

    A numerical study of flow and heat transfer characteristics is made in a double pipe heat exchanger with porous structures inserted in the annular gap in two configurations: on the inner cylinder (A) and on both the cylinders in a staggered fashion (B). The flow field in the porous regions is modelled by the Darcy-Brinkman-Forchheimer model and the finite volume method is used to solve the governing equations. The effects of several parameters such as Darcy number, porous structures thickness and spacing and thermal conductivity ratio are considered in order to look for the most appropriate properties of the porous structures that allow optimal heat transfer enhancement. It is found that the highest heat transfer rates are obtained when the porous structures are attached in configuration B especially at small spacing and high thicknesses

  18. Heat pipe radiators for solar dynamic space power system heat rejection

    Science.gov (United States)

    Gustafson, Eric; Carlson, Albert

    1987-01-01

    The paper presents the results of a concept development study of heat rejection systems for Space Station solar dynamic power systems. The thermal performance and weights of each of the heat rejection subsystems have been addressed in detail, and critical technologies which require development tests and evaluation for successful demonstration were assessed and identified. Baseline and several alternate heat rejection system configurations and optimum designs were developed for both Brayton and Rankine cycles. The thermal performance, mass properties, assembly requirements, reliability, maintenance requirements, and life cycle costs were determined for each of the system configurations. Trade studies were performed on each configuration with respect to the heat pipe wall thickness and the amount of redundancy to determine the effects on system reliability, maintenance requirements, and life cycle costs. An optimum design was then selected for each configuration.

  19. A numerical model for the platelet heat-pipe-cooled leading edge of hypersonic vehicle

    Science.gov (United States)

    Liu, Hongpeng; Liu, Weiqiang

    2016-01-01

    A new design, the platelet heat-pipe-cooled leading edge, is discussed for the thermal management to prevent damage to hypersonic vehicle leading edge component. For calculating the steady state behavior of platelet heat-pipe-cooled leading edge, a numerical model based on the principles of evaporation, convection, and condensation of a working fluid is presented. And then its effectiveness is validated by comparing the wall and vapor temperature against experimental data for a conventional heat pipe. Further investigations indicate that alloy IN718, with sodium as the working fluid is a feasible combination for Mach 8 flight with a 15 mm leading edge radius.

  20. Application of axial grooves to cryogenic variable conductance heat pipe technology. [cryogenic thermal diodes

    Science.gov (United States)

    Brennan, P. J.; Groll, M.

    1976-01-01

    Tests results obtained with an ATS axial groove aluminum extrusion adapted for use as a cryogenic thermal diode and/or a variable conductance heat pipe are presented. Ethane at a nominal operating temperature of 185 C was used as working fluid. In addition to both active and passive gas control, diode designs utilizing gas blockage or liquid trap were investigated. Specific requirements and performance parameters such as transient behavior, reservoir sizes, shutdown energy, etc., were evaluated. Results are also presented for tests where the liquid trap was used as a secondary heat pipe to demonstrate thermal switching with simultaneous heat pipe operation and diode shutdown.

  1. Innovative two-pipe active chilled beam system for simultaneous heating and cooling of office buildings

    DEFF Research Database (Denmark)

    Maccarini, Alessandro; Afshari, Alireza; Bergsøe, Niels Christian;

    2014-01-01

    The aim of this paper was to investigate the energy savings potential of an innovative two-pipe system in an active chilled beam application for heating and cooling of office buildings. The characteristic of the system is its ability to provide simultaneous heating and cooling by transferring...... heating, cooling and ventilation loads were calculated by the program and an annual energy consumption evaluation of the system was made. Simulation results showed that the innovative two-pipe active chilled beam system used approximately 5% less energy than a conventional four-pipe system....

  2. Experiments on heat pipes submitted to strong accelerations; Experimentation de caloducs soumis a de fortes accelerations

    Energy Technology Data Exchange (ETDEWEB)

    Labuthe, A. [Dassault Aviation, 92 - Saint Cloud (France)

    1996-12-31

    In order to evaluate the possibility to use heat pipes as efficient heat transfer devices in aircrafts, a study of their behaviour during strong accelerations is necessary. This study has been jointly carried out by the Laboratory of Thermal Studies of Poitiers (France) and Dassault Aviation company. It is based on a series of tests performed with an experimental apparatus that uses the centrifugal effect to simulate the acceleration fields submitted to the heat pipe. Un-priming - priming cycles have been performed under different power and acceleration levels and at various functioning temperatures in order to explore the behaviour of heat pipes: rate of un-priming and re-priming, functioning in blocked mode etc.. This preliminary study demonstrates the rapid re-priming of the tested heat pipes when submitted to favourable acceleration situations and the possibility to use them under thermosyphon conditions despite the brief unfavourable acceleration periods encountered. (J.S.)

  3. Visualizing the thermal performance of heat pipes with thermochromic liquid crystals

    Science.gov (United States)

    Gunnerson, Fred S.; Thorncroft, Glen E.

    A novel technique has been developed to visualized the thermal performance characteristics of simple low temperature heat pipes and thermosyphons. Copper heat pipes with internal, annular mesh wicks and charged with Refrigerant-12 were externally coated with thermochromic liquid crystal (TLC) paints. The thermally sensitive TLC coating reversibly changes color upon heating and readily permits visual identification of transient and steady state isotherms during low temperature operation. The start-up and operational behaviors of the heat pipe as well as the presence of non-condensible gases can be visually identified through a spectrum of color changes. A brief video demonstration illustrating heat pipe thermal performance characteristics has been developed and illustrates the utility of TLCs for visualizing thermal behavior.

  4. Theoretical and bibliographic synthesis on micro-heat pipes; Synthese theorique et bibliographique sur les microcaloducs

    Energy Technology Data Exchange (ETDEWEB)

    Sartre, V.; Lallemand, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

    1996-12-31

    The technology, dimensioning and performances of heat pipes are well known since several years. Micro-heat pipes occurred more recently with the miniaturization of systems to be cooled and the increase of surface heat fluxes to be dissipated. Publications concerning this topic are not much older than the 90`s. Using these papers, a bibliographic synthesis on micro-heat pipe performances, functioning and dimensioning is presented. Experimental studies demonstrate the efficiency of such systems but also their high sensitivity with respect to the capillary limit which leads to a progressive drying of the evaporator and a reduction of its thermal conductance. Theoretical studies are based on the same equations than heat pipes. More or less complex models have been proposed in the literature and a relatively simple model is presented in this paper. These studies have permitted to show the great influence of some parameters on micro-heat pipes functioning like: the pipe geometry, the fluid-wall contact angle, the level of pipes filling, and the bonding zone of the liquid film on the wall. (J.S.) 15 refs.

  5. Chemistry effect of heat-exchange pipes on functional reliability of steam generators in PWR and VVER NPPs

    International Nuclear Information System (INIS)

    Functional reliability of steam generators depends heavily on the selection of material for steam generator heat-exchange pipes (SG HEP). Close analysis of references follows that most of damaged SG HEP in NPPs with PWR reactors are made of alloy 600 MA. The paper represents the analysis of effect of different steel chemical elements on their corrosion resistance. The choice of materials for manufacturing SG HEP is proved. (author)

  6. Analytical and experimental studies of heat pipe radiation cooling of hypersonic propulsion systems

    Science.gov (United States)

    Martin, R. A.; Merrigan, M. A.; Elder, M. G.; Sena, J. T.; Keddy, E. S.; Silverstein, C. C.

    1992-01-01

    Analytical and experimental studies were completed to assess the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This new approach involves using heat pipes to transport heat away from the combustor, nozzle, or inlet regions, and to reject it to the environment by thermal radiation from an external heat pipe nacelle. For propulsion systems using heat pipe radiation cooling (HPRC), it is possible to continue to use hydrocarbon fuels into the Mach 4 to Mach 6 speed range, thereby enhancing the economic attractiveness of commercial or military hypersonic flight. In the second-phase feasibility program recently completed, it is found that heat loads produced by considering both convection and radiation heat transfer from the combustion gas can be handled with HPRC design modifications. The application of thermal insulation to ramburner and nozzle walls was also found to reduce the heat load by about one-half and to reduce peak HPRC system temperatures to below 2700 F. In addition, the operation of HPRC at cruise conditions of around Mach 4.5 and at an altitude of 90,000 ft lowers the peak hot-section temperatures to around 2800 F. An HPRC heat pipe was successfully fabricated and tested at Mach 5 conditions of heat flux, heat load, and temperature.

  7. Investigation of Freeze and Thaw Cycles of a Gas-Charged Heat Pipe

    Science.gov (United States)

    Ku, Jentung; Ottenstein, Laura; Krimchansky, Alexander

    2012-01-01

    The traditional constant conductance heat pipes (CCHPs) currently used on most spacecraft run the risk of bursting the pipe when the working fluid is frozen and later thawed. One method to avoid pipe bursting is to use a gas-charged heat pipe (GCHP) that can sustain repeated freeze/thaw cycles. The construction of the GCHP is similar to that of the traditional CCHP except that a small amount of non-condensable gas (NCG) is introduced and a small length is added to the CCHP condenser to serve as the NCG reservoir. During the normal operation, the NCG is mostly confined to the reservoir, and the GCHP functions as a passive variable conductance heat pipe (VCHP). When the liquid begins to freeze in the condenser section, the NCG will expand to fill the central core of the heat pipe, and ice will be formed only in the grooves located on the inner surface of the heat pipe in a controlled fashion. The ice will not bridge the diameter of the heat pipe, thus avoiding the risk of pipe bursting during freeze/thaw cycles. A GCHP using ammonia as the working fluid was fabricated and then tested inside a thermal vacuum chamber. The GCHP demonstrated a heat transport capability of more than 200W at 298K as designed. Twenty-seven freeze/thaw cycles were conducted under various conditions where the evaporator temperature ranged from 163K to 253K and the condenser/reservoir temperatures ranged from 123K to 173K. In all tests, the GCHP restarted without any problem with heat loads between 10W and 100W. No performance degradation was noticed after 27 freeze/thaw cycles. The ability of the GCHP to sustain repeated freeze/thaw cycles was thus successfully demonstrated.

  8. Solar heat pipe testing of the Stirling thermal motors 4-120 Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Andraka, C.E.; Rawlinson, K.S.; Moss, T.A.; Adkins, D.R.; Moreno, J.B.; Gallup, D.R.; Cordeiro, P.G. [Sandia National Labs., Albuquerque, NM (United States); Johansson, S. [Stirling Thermal Motors, Inc., Ann Arbor, MI (United States)

    1996-07-01

    Stirling-cycle engines have been identified as a promising technology for the conversion of concentrated solar energy into usable electrical power. A 25kW electric system takes advantage of existing Stirling-cycle engines and existing parabolic concentrator designs. In previous work, the concentrated sunlight impinged directly on the heater head tubes of the Stirling Thermal Motors (STM) 4-120 engine. A Sandia-designed felt-metal-wick heat pipe receiver was fitted to the STM 4-120 engine for on-sun testing on Sandia`s Test Bed Solar Concentrator. The heat pipe uses sodium metal as an intermediate two-phase heat transfer fluid. The receiver replaces the directly-illuminated heater head previously tested. The heat pipe receiver provides heat isothermally to the engine, and the heater head tube length is reduced, both resulting in improved engine performance. The receiver also has less thermal losses than the tube receiver. The heat pipe receiver design is based on Sandia`s second-generation felt-wick heat pipe receiver. This paper presents the interface design, and compares the heat pipe/engine test results to those of the directly-illuminated receiver/engine package.

  9. Heat Removal from Bipolar Transistor by Loop Heat Pipe with Nickel and Copper Porous Structures

    Directory of Open Access Journals (Sweden)

    Patrik Nemec

    2014-01-01

    Full Text Available Loop heat pipes (LHPs are used in many branches of industry, mainly for cooling of electrical elements and systems. The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work was to develop porous structures from copper and nickel powder with different grain sizes. For experiment copper powder with grain size of 50 and 100 μm and nickel powder with grain size of 10 and 25 μm were used. Analysis of these porous structures and LHP design are described in the paper. And the measurements’ influences of porous structures in LHP on heat removal from the insulated gate bipolar transistor (IGBT have been made.

  10. Heat removal from bipolar transistor by loop heat pipe with nickel and copper porous structures.

    Science.gov (United States)

    Nemec, Patrik; Smitka, Martin; Malcho, Milan

    2014-01-01

    Loop heat pipes (LHPs) are used in many branches of industry, mainly for cooling of electrical elements and systems. The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work was to develop porous structures from copper and nickel powder with different grain sizes. For experiment copper powder with grain size of 50 and 100 μm and nickel powder with grain size of 10 and 25 μm were used. Analysis of these porous structures and LHP design are described in the paper. And the measurements' influences of porous structures in LHP on heat removal from the insulated gate bipolar transistor (IGBT) have been made. PMID:24959622

  11. Ultrasonic on-line flare testing of heat exchanger pipes

    International Nuclear Information System (INIS)

    Up to now, in field applications the degree of adhesion flaring of rolled-in pipes can only be determined inaccurately and non-reproducibly. A new process is introduced here for directly measuring the reduction of the pipe wall while pipes are rolled in, based on the measurement of ultrasonic propagation time. This permits to obtain the precise degree of adhesion flaring and to ensure the quality of the connection of a specific pipe. In view of the improved accuracy of measurements, destructive tests can now be dispensed with. (orig.)

  12. Development of an ISI robot for the fast breeder reactor MONJU primary heat transfer system piping

    International Nuclear Information System (INIS)

    The fast breeder reactor (FBR) 'MONJU' carry out in-service inspection (ISI) in important components for safety. ISI of the primary heat transfer system (PHTS) piping is performed by sodium leak monitoring, a visual testing with ITV camera and a volumetric testing with ultrasonic. The volumetric testing inspect maximum part of stress concentration in PHTS pipe by using ultrasonic. ISI use remote control robot on the grounds of high temperature (atmosphere 55 deg. C, pipe surface 80 deg. C) and radiation exposure condition (dose rate 10mGy/h, pipe surface dose rate 15mGy/h). Moreover, volumetric testing use tire type ultrasonic sensor on the grounds of a sodium boundary which chemically reacts with water and oil. Light-water reactors (LWR) can be inspected by ultrasonic that uses water and oil. Purpose. This development of inspection system is intended to use new control robot and new tire type ultrasonic sensor. The robot control adopt teaching control method. The target is reproducibility of less than ±5mm. The new tire type ultrasonic sensor adopt double oscillators, because of the multipath reflection wave from contact rubber etc., the noise level decreases and consequently S/N ratio well. The defective detection target was decided to be a depth 50% electrical discharge machining (EDM) slit from pipe wall thickness (t=11.1mm) with a signal per noise ratio (S/N) not less than 2 (6dB). Results and Conclusions We developed a new inspection system for the in-service inspection of PHTS of the FBR 'MONJU'. Moreover, we carried out performance test about new inspection system. The control performance of the new robot driving confirmed it was about less than 5mm by the experiment. The detection performance of new tire sensor confirmed it was detectable an EDM slit with depth 10% from pipe thickness and with a S/N ratio not less than 4.0 (12.0dB). The robot and new tire sensor that developed as a result of the experiment confirmed the performance that was able to be

  13. Flow visualization of silicon-based micro pulsating heat pipes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Two sets of silicon-based micro pulsating heat pipes(SMPHPs) with trapezoidal cross section having hydraulic diameters of 352 μm(#1) and 394 μm(#2) respectively were fabricated for the first time using MEMS technology.With FC-72 as the working fluid,the start-up,steady operation state,as well as flow patterns were investigated using a CCD camera.It was found that the start-up process of these two SMPHPs was rather rapid.At the start-up period,no nucleation was observed,and the vapor plugs at the evaporator U-bends were formed mainly due to the breakup of liquid slugs.At the steady operation state,self-sustained oscillation with large amplitudes dominated the flow behavior when the inclination angle varied from 10° to 90°,but the nucleate boiling and bulk circulation were observed only in SMPHP #2.While bubbly,slug/plug,annular/semi-annular,and wavy-annular flows were observed in both two SMPHPs,the injection flow only appeared in SMPHP #2.

  14. Heat pipe based passive emergency core cooling system for safe shutdown of nuclear power reactor

    International Nuclear Information System (INIS)

    On March 11th, 2011, a natural disaster created by earthquakes and Tsunami caused a serious potential of nuclear reactor meltdown in Fukushima due to the failure of Emergency Core Cooling System (ECCS) powered by diesel generators. In this paper, heat pipe based ECCS has been proposed for nuclear power plants. The designed loop type heat pipe ECCS is composed of cylindrical evaporator with 62 vertical tubes, each 150 mm diameter and 6 m length, mounted around the circumference of nuclear fuel assembly and 21 m × 10 m × 5 m naturally cooled finned condenser installed outside the primary containment. Heat pipe with overall thermal resistance of 1.44 × 10−5 °C/W will be able to reduce reactor temperature from initial working temperature of 282 °C to below 250 °C within 7 h. The overall ECCS also includes feed water flooding of the core using elevated water tank for initial 10 min which will accelerate cooling of the core, replenish core coolant during loss of coolant accident and avoids heat transfer crisis phenomena during heat pipe start-up process. The proposed heat pipe system will operate in fully passive mode with high runtime reliability and therefore provide safer environment to nuclear power plants. - Highlights: • Completely passive emergency core cooling system (ECCS) for nuclear power plants. • ECCS consists of loop type heat pipe and initial feed water flooding system. • Overall thermal resistance of loop type heat pipe is 1.44 × 10−5 °C/W. • Heat pipe system can reduce reactor temperature from 282 °C to 250 °C in 7 h. • Proposed system will provide reliable and safer cooling for nuclear reactor

  15. Design of Refractory Metal Heat Pipe Life Test Environment Chamber, Cooling System, and Radio Frequency Heating System

    Science.gov (United States)

    Martin, J. J.; Bragg-Sitton, S. M.; Reid, R. S.; Stewart, E. T.; Davis, J. D.

    2011-01-01

    A series of 16 Mo-44.5%Re alloy/sodium heat pipes will be experimentally tested to examine heat pipe aging. To support this evaluation, an environmental test chamber and a number of auxiliary subsystems are required. These subsystems include radio frequency (RF) power supplies/inductive coils, recirculation water coolant loops, and chamber gas conditioning. The heat pipes will be grouped, based on like power and gas mixture requirements, into three clusters of five units each, configured in a pentagonal arrangement. The highest powered heat pipe will be tested separately. Test chamber atmospheric purity is targeted at pressure of 76 torr (.1.5 psia), maintained by active purification (oxygen level is comparable to a 10(exp -6) torr environment). Treated water will be used in two independent cooling circuits to remove .85 kW. One circuit will service the RF hardware while the other will maintain the heat pipe calorimetry. Initial procedures for the startup and operation of support systems have been identified. Each of these subsystems is outfitted with a variety of instrumentation, integrated with distributed real-time controllers and computers. A local area network provides communication between all devices. This data and control network continuously monitors the health of the test hardware, providing warning indicators followed by automatic shutdown should potentially damaging conditions develop. During hardware construction, a number of checkout tests.many making use of stainless steel prototype heat pipes that are already fabricated.will be required to verify operation.

  16. Effect of nitrogen-doped graphene nanofluid on the thermal performance of the grooved copper heat pipe

    DEFF Research Database (Denmark)

    Mehrali, Mohammad; Sadeghinezhad, Emad; Azizian, Reza;

    2016-01-01

    Thermal performance of a grooved heat pipe using aqueous nitrogen-doped graphene (NDG) nanofluids was analysed. This study in particular focused on the effect of varying NDG nanosheets concentrations, heat pipe inclination angles and input heating powers. The results indicated that the inclination...... angle had a major influence on the heat transfer performance of heat pipes and the inclination angle (θ) of 90° was corresponded to the best thermal performance. The maximum thermal resistance reduction of 58.6% and 99% enhancement in the evaporator heat transfer coefficient of the heat pipe were...... performance of a grooved heat pipe. The present investigation indicated that the thermal performance of the grooved heat pipe can be improved significantly by using NDG nanofluids....

  17. Heat pipe central solar receiver. Semiannual progress report, September 1, 1976--May 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Bienert, W. B.; Wolf, D. A.

    1977-09-01

    It is proposed to develop a solar-to-gas heat exchanger for a Central Solar Receiver Power Plant. The concept employs heat pipes to transfer the concentrated solar flux to the gaseous working medium of a Brayton cycle conversion system. During early phases of the program, an open air cycle with recuperator and a turbine inlet temperature of 800/sup 0/C was selected as the optimum design. The predicted cycle efficiency is 33 percent and the overall solar-to-electric efficiency is 20 percent. Three potential receiver configurations were also identified during the initial phases of the program. Optimum heat pipe diameter is approximately 5 cm for all three receiver configurations, and typical lengths are 2 to 3 meters. The required number of heat pipes for a 10 MWe receiver ranges from 2000 to 8000. Heat transport requirements per pipe vary from 4 to 18 Kw. Several wick structures were developed and evaluated in subscale heat pipe tests using sodium as the working fluid. One full scale heat pipe (5 cm diameter by 183 cm long) was developed and tested with sodium as the working fluid.

  18. Optimisation of Double Pipe Helical Tube Heat Exchanger and its Comparison with Straight Double Tube Heat Exchanger

    Science.gov (United States)

    Kareem, Rashid

    2016-06-01

    Optimization of double pipe helical coil heat exchanger with various optimizing parameters and its comparison with double pipe straight tube are the prime objectives of this paper. Numerical studies were performed with the aid of a commercial computational fluid dynamics package ANSYS FLUENT 14. In this paper the double pipe helical coil is analysed under turbulent flow conditions for optimum heat exchanger properties. The parameters used for optimization are cross-sectional shape and taper angles. Optimization analysis is being carried out for finding best cross sectional shape of heat exchanger coils by using rectangular, square, triangular and circular cross-sections. The tapered double pipe helical coil is then analysed for best heat transfer and pressure drop characteristics by varying the angle of taper. Finally, an optimum coil on the basis of all the analysis is selected. This optimized double pipe helical coil is compared with double pipe straight tube of equivalent cross-sectional area and length as that of unwounded length of double pipe helical coil.

  19. Numerical simulation of the effects of nanofluid on a heat pipe thermal performance

    DEFF Research Database (Denmark)

    Gavtash, Barzin; Hussain, Khalid; Layeghi, Mohammad;

    2014-01-01

    This research aims at modeling and simulating the effects of nanofluids on cylindrical heat pipes thermal performance using the ANSYS-FLUENT CFD commercial software. The heat pipe outer wall temperature distribution, thermal resistance, liquid pressure and axial velocity in presence of suspended...... nano-scaled solid particle (i.e. Cu, Al2O3 and TiO2) within the fluid (water) were investigated. The effect of particle concentration and size were explored and it is concluded that the thermal performance of the heat pipe is improved when using nanofluid as the system working fluid. Additionally, it...... was observed that the thermal resistance of the heat pipe drops as the particle concentration level increases and particle radius decreases....

  20. Refractory Metal Heat Pipe Life Test - Test Plan and Standard Operating Procedures

    Science.gov (United States)

    Martin, J. J.; Reid, R. S.

    2010-01-01

    Refractory metal heat pipes developed during this project shall be subjected to various operating conditions to evaluate life-limiting corrosion factors. To accomplish this objective, various parameters shall be investigated, including the effect of temperature and mass fluence on long-term corrosion rate. The test series will begin with a performance test of one module to evaluate its performance and to establish the temperature and power settings for the remaining modules. The performance test will be followed by round-the-clock testing of 16 heat pipes. All heat pipes shall be nondestructively inspected at 6-month intervals. At longer intervals, specific modules will be destructively evaluated. Both the nondestructive and destructive evaluations shall be coordinated with Los Alamos National Laboratory. During the processing, setup, and testing of the heat pipes, standard operating procedures shall be developed. Initial procedures are listed here and, as hardware is developed, will be updated, incorporating findings and lessons learned.

  1. Titanium-Water Heat Pipe Radiator for Spacecraft Fission Power Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed program will develop titanium/water heat pipes suitable for Spacecraft Fission Power. NASA is examining small fission power reactors for future space...

  2. Corrected solutions of eigenvalue problems at transient heat with turbulent pipe flow

    International Nuclear Information System (INIS)

    For a given turbulent pipe flow, the transient heat occurs by convection as well as by thermal diffusitivity. The problems of their Eigenvalues will be analized in order to find out a corrected solution. (Author)

  3. Loop Heat Pipe with Thermal Control Valve for Passive Variable Thermal Link Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Loop heat pipes (LHPs) can provide variable thermal conductance needed to maintain electronics and batteries on Lunar/Martian rovers/landers within desired...

  4. Heat Pipe Solar Receiver for Oxygen Production of Lunar Regolith Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovative Research project by Advanced Cooling Technologies, Inc. (ACT) will develop an advanced high temperature heat pipe solar receiver that...

  5. Convective Heat Transfer of Nano fluids Flows Through an Isothermally Heated Curved Pipe

    International Nuclear Information System (INIS)

    In the current study, numerical simulation of laminar flow and heat transfer of water mixture with carbon nano tubes as nano fluids in a 90 degree curved pipe are considered. The incompressible Navier-Stokes and energy equations are solved numerically in a body fitted coordinates system using a control volume technique. An interfacial layer-based model is applied to predict the thermal conductivity of nano fluid. The axial velocity contours, secondary flow patterns and temperature fields for different values of the particles concentrations are examined in detail. Furthermore, the effects of nanoparticles concentration on the heat transfer are studied. The results indicate that due to the secondary flows induced by curvature effects, the heat transfer rate is improved, and enhanced remarkably further using nano fluids. Furthermore, the nanoparticles, especially at higher concentration levels, generate more uniform cross sectional temperature distributions.

  6. Experimental investigation on the thermal performance and optimization of heat sink with U-shape heat pipes

    International Nuclear Information System (INIS)

    Experimental investigation is carried out to study the thermal performance of a heat sink with finned U-shape heat pipes which is a contemporary central processing unit (CPU) cooler compatible for a wide range of high-frequency microprocessors. The optimum range of operating heat load based on thermal resistance analysis of the heat sink is characterized. The convection heat transfer coefficient between the fins and the ambient air is estimated by using Bessel's modified equation in conjunction with the results obtained through the experimental investigation. The thermal optimization of the heat sink involves the determination of the optimized L-ratio (ratio of the evaporator section length to the condenser section length) of the U-shape heat pipe, by evaluating the minima of the thermal resistance function, in which case the empirical convection heat transfer coefficient is applied in the calculation. In conjunction with this, the optimal L-ratio of a U-shape heat pipe is found to be dependent on other geometrical parameters such as the heat pipe diameter and the fin spacing, which are of practical engineering importance in the optimum design of the heat sink.

  7. Experimental investigation on the thermal performance and optimization of heat sink with U-shape heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Tian Shen [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia); Hung, Yew Mun [School of Engineering, Monash University, 46150 Bandar Sunway (Malaysia)

    2010-11-15

    Experimental investigation is carried out to study the thermal performance of a heat sink with finned U-shape heat pipes which is a contemporary central processing unit (CPU) cooler compatible for a wide range of high-frequency microprocessors. The optimum range of operating heat load based on thermal resistance analysis of the heat sink is characterized. The convection heat transfer coefficient between the fins and the ambient air is estimated by using Bessel's modified equation in conjunction with the results obtained through the experimental investigation. The thermal optimization of the heat sink involves the determination of the optimized L-ratio (ratio of the evaporator section length to the condenser section length) of the U-shape heat pipe, by evaluating the minima of the thermal resistance function, in which case the empirical convection heat transfer coefficient is applied in the calculation. In conjunction with this, the optimal L-ratio of a U-shape heat pipe is found to be dependent on other geometrical parameters such as the heat pipe diameter and the fin spacing, which are of practical engineering importance in the optimum design of the heat sink. (author)

  8. Theoretical investigation of the performance of a novel loop heat pipe solar water heating system for use in Beijing, China

    International Nuclear Information System (INIS)

    A novel loop heat pipe (LHP) solar water heating system for typical apartment buildings in Beijing was designed to enable effective collection of solar heat, distance transport, and efficient conversion of solar heat into hot water. Taking consideration of the heat balances occurring in various parts of the loop, such as the solar absorber, heat pipe loop, heat exchanger and storage tank, a computer model was developed to investigate the thermal performance of the system. With the specified system structure, the efficiency of the solar system was found to be a function of its operational characteristics - working temperature of the loop heat pipe, water flow rate across the heat exchanger, and external parameters, including ambient temperature, temperature of water across the exchanger and solar radiation. The relationship between the efficiency of the system and these parameters was established, analysed and discussed in detail. The study suggested that the loop heat pipe should be operated at around 72 deg. C and the water across the heat exchanger should be maintained at 5.1 l/min. Any variation in system structure, i.e., glazing cover and height difference between the absorber and heat exchanger, would lead to different system performance. The glazing covers could be made using either borosilicate or polycarbonate, but borosilicate is to be preferred as it performs better and achieves higher efficiency at higher temperature operation. The height difference between the absorber and heat exchanger in the design was 1.9 m which is an adequate distance causing no constraint to heat pipe heat transfer. These simulation results were validated with the primary testing results.

  9. Experimental investigation on thermal management of electric vehicle battery with heat pipe

    International Nuclear Information System (INIS)

    Highlights: ► The thermal management system of electric vehicle battery with heat pipes was designed. ► Temperature rise is a key factor for the design of power battery thermal management system. ► Temperature distribution is inevitable to reference for better design of heat pipes used for heat dissipation. ► Heat pipes are effective for power batteries thermal management within electric vehicles. - Abstract: In order to increase the cycle time of power batteries and decrease the overall cost of electric vehicles, the thermal management system equipped with heat pipes was designed according to the heat generated character of power batteries. The experimental result showed that the maximum temperature could be controlled below 50 °C when the heat generation rate was lower than 50 W. Coupled with the desired temperature difference, the heat generation rate should not exceed 30 W. The maximum temperature and temperature difference are kept within desired rang under unsteady operating conditions and cycle testing conditions. Applying heat pipes based power batteries thermal management is an effective method for energy saving in electric vehicles.

  10. Flight data analysis and further development of variable-conductance heat pipes

    Science.gov (United States)

    Eninger, J. E.; Edwards, D. K.; Luedke, E. E.

    1976-01-01

    The work focuses on the mathematical modeling of three critical mechanisms of heat-pipe operation: (1) the effect that excess liquid has on heat-pipe performance; (2) the calculation of the dryout limit of circumferential grooves; (3) an efficient mathematical model for the calculation of the viscous-inertial interaction in the vapor flow. These mathematical models are incorporated in the computer program GRADE II, which is described.

  11. Salt loaded heat pipes: steady-state operation and related heat and mass transport

    Science.gov (United States)

    Simakin, A.; Ghassemi, A.

    2003-10-01

    Fluids in the deep-seated zones (3.5-4.5 km) of active geothermal zones are known to have increased salinity and acidity that can enhance interaction with surrounding porous rocks. A possible mechanism for brine generation is the separation of the rising magmatic fluid into a gas-like and a liquid-like component. This work illustrates the main features of this mechanism by investigating the conditions for heat pipe convection of natural brines in hydrothermal systems. The well-established heat pipe regime for convection of two-phase pure water (vapor-liquid) in a porous column is extended to the case of boiling brines. In particular, the NaCl-H 2O system is used to model the 1-D reactive flow with dissolution-precipitation in geothermal reservoirs. The quasi steady-state equations of the conservation of matter, Darcy's law for the gas and liquid phases, and the heat balance equation have been examined while neglecting the temporal variation of porosity. A semi-analytical procedure is used to solve these equations for a two-phase fluid in equilibrium with a solid salt. The solution is in the form of the dependence of liquid volume fraction as a function of temperature for different heat fluxes. The solution is separated into two isolated regions by the temperature T=596°C, at the maximum fluid pressure for three-phase (H-L-V) equilibrium. In the case of unsaturated two-phase flow at the reference permeability of porous rocks (3·10 -16 m 2), the maximum heat flux that can be transferred through the porous column via convection is analytically estimated to be 4.3 W/m 2. This is close to the corresponding value for the three-phase case that is numerically calculated to be 6 W/m 2. Due to dissolution (partial leaching of oxide components by acid condensates) and precipitation of salt at the boiling front, heat transfer in a heat pipe in soluble media occurs in a direction opposite to the associated mass transfer. This can cause deep hydrothermal karsting that is

  12. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    Science.gov (United States)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a "segmented" thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed "segmented" model shows more precise than the "non-segmented" model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the "segmented" model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  13. Influence of dimension parameters of the gravity heat pipe on the thermal performance

    Science.gov (United States)

    Kosa, Ľuboš; Nemec, Patrik; Jobb, Marián; Malcho, Milan

    2016-06-01

    Currently the problem with the increasing number of electronic devices is a problem with the outlet Joule heating. Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor releases heat. Perfect dustproof cooling of electronic components ensures longer life of the equipment. One of more alternatives of heat transfer without the using of mechanical equipment is the use of the heat pipe. Heat pipes are easy to manufacture and maintenance of low input investment cost. The advantage of using the heat pipe is its use in hermetic closed electronic device which is separated exchange of air between the device and the environment. This experiment deals with the influence of changes in the working tube diameter and changing the working fluid on performance parameters. Changing the working fluid and the tube diameter changes the thermal performance of the heat pipe. The result of this paper is finding the optimal diameter with ideal working substance for the greatest heat transfer for 1cm2 sectional area tube.

  14. Influence of Heat Input, Working Fluid and Evacuation Level on the Performance of Pulsating Heat Pipe

    Directory of Open Access Journals (Sweden)

    K. Rama Narasimha

    2012-01-01

    Full Text Available An experimental study on pulsating heat pipe (PHP is presented in this work. A closed loop PHP with a single U turn is fabricated and tested. The transient and steady state experiments are conducted and operating temperatures are measured. The experiments are carried out for different working fluids, heat input and for different evacuation levels. The derived parameters include thermal resistance and heat transfer coefficient of PHP. The results of these experiments show an intermittent motion of the working fluid at lower heat input. The temperature difference between evaporator and condenser at steady state is found lower for acetone compared to water, ethanol and methanol. Lower value of thermal resistance and higher value of heat transfer coefficient are observed in case of acetone compared to water, ethanol and methanol. Lower values of temperature difference between evaporator and condenser and thermal resistance and higher value of heat transfer coefficient are observed at atmospheric conditions of operation of PHP compared to evacuation conditions. The Power Spectral Density Analysis is also carried out on the results of these experiments using FFT technique to analyse the pulsating motion of the fluid in a PHP. In the Power Spectral Density analysis, the frequency distribution of temperature variation in PHP was observed over a wider range, signifying the periodic motion in the fluid flow of the liquid slug and vapour plug. This characteristic frequency corresponded to the characteristic time for a couple of adjacent vapour plug and liquid slug passing through a specific local wall surface in a PHP.

  15. Experimental investigation of pulsating heat pipe performance with regard to fuel cell cooling application

    International Nuclear Information System (INIS)

    A pulsating heat pipe (PHP) is a closed loop, passive heat transfer device. Its operation depends on the phase change of a working fluid within the loop. Design and performance testing of a pulsating heat pipe was conducted under conditions to simulate heat dissipation requirements of a proton exchange membrane (PEM) fuel cell stack. Integration of pulsating heat pipes within bipolar plates of the stack would eliminate the need for ancillary cooling equipment, thus also reducing parasitic losses and increasing energy output. The PHP under investigation, having dimensions of 46.80 cm long and 14.70 cm wide, was constructed from 0.3175 cm copper tube. Heat pipes effectiveness was found to be dependent upon several factors such as energy input, types of working fluid and its filling ratio. Power inputs to the evaporator side of the pulsating heat pipe varied from 80 to 180 W. Working fluids tested included acetone, methanol, and deionized water. Filling ratios between 30 and 70 percent of the total working volume were also examined. Methanol outperformed other fluids tested; with a 45 percent fluid fill ratio and a 120 W power input, the apparatus took the shortest time to reach steady state and had one of the smallest steady state temperature differences. The various conditions studied were chosen to assess the heat pipe's potential as cooling media for PEM fuel cells. - Highlights: ► Methanol as a working fluid outperformed both acetone and water in a pulsating heat pipe. ► Performance for the PHP peaked with methanol and a fill ratio of 45 percent fluid to total volume. ► A smaller resistance was associated with a higher power input to the system.

  16. The TX-model - a quantitative heat loss analysis of district heating pipes by means of IR surface temperature measurements

    Energy Technology Data Exchange (ETDEWEB)

    Zinki, Heimo [ZW Energiteknik, Nykoeping (Sweden)

    1996-11-01

    The aim of this study was to investigate the possibility of analysing the temperature profile at the ground surface above buried district heating pipes in such a way that would enable the quantitative determination of heat loss from the pair of pipes. In practical applications, it is supposed that this temperature profile is generated by means of advanced IR-thermography. For this purpose, the principle of the TX - model has been developed, based on the fact that the heat losses from pipes buried in the ground have a temperature signature on the ground surface. Qualitative analysis of this temperature signature is very well known and in practical use for detecting leaks from pipes. These techniques primarily make use of relative changes of the temperature pattern along the pipe. In the quantitative heat loss analysis, however, it is presumed that the temperature profile across the pipes is related to the pipe heat loss per unit length. The basic idea is that the integral of the temperature profile perpendicular to the pipe, called TX, is a function of the heat loss, but is also affected by other parameters such as burial depth, heat diffusivity, wind, precipitation and so on. In order to analyse the parameters influencing the TX- factor, a simulation model for the energy balance at the ground surface has been developed. This model includes the heat flow from the pipe to the surface and the heat exchange at the surface with the environment due to convection, latent heat change, solar and long wave radiation. The simulation gives the surprising result that the TX factor is by and large unaffected during the course of a day even when the sun is shining, as long as other climate conditions are relatively stable (low wind, no rain, no shadows). The results from the simulations were verified at different sites in Denmark, Finland, Sweden and USA through a co-operative research program organised and partially financed by the IEA District Heating Programme, Task III, and

  17. Elaboration of thermal control systems on heat pipes for microsatellites Magion 4, 5 and BIRD

    International Nuclear Information System (INIS)

    The strong restricted requirements to mass and power budget of microsatellite subsystems lead to choice of mainly passive thermocontrol system, specifically with heat pipe (HP) integration. An objective of this paper is to present the experience collected by authors in the field of elaboration and flight exploitation of thermocontrol systems (TCS) with heat pipes for microsatellites Magion 4 (1995), Magion 5 (1996) and BIRD (2001). Microsatellites Magion 4, 5 (Project INTERBALL) were completed with TCS including four low-temperature U-shaped heat pipes (fabricated by Kyiv Polytechnic Institute) installed in pairs on symmetrical facets of microsatellites' bodies. Each pair of heat pipes was placed on two general flanges: one combined HP heating zones, the second combined their condensation zones. Heat pipes were fabricated from thin-wall copper shells with capillary structure of metal felt. Flanges were of aluminium, and acetone was used as heat carrier. Rated transferred heat power was not less than 60 W in the range of working temperatures from -20 to +50 deg. C. TCS for microsatellite BIRD included two U-shaped aluminium ammonia heat pipes (design and manufacture--Kiev Polytechnic Institute) symmetrically placed on opposite faces of the satellite. Heat pipe capillary structure was formed from 30 grooves of rectangular section. Rated transferred heat power reached 90 W in the range of working temperatures from -50 to +60 deg. C. Symmetrical layout of elements of TCS on microsatellite is the most acceptable due to stability of spatial orientation and geometrical symmetry of microsatellites and to enlarge the reliability of system operation. Microsatellites Magion 4, 5 and their parts have passed the full cycle of tests stipulated by Project INTERBALL. Currently Magion 5 active functioning exceeds 4.5 years and heat pipes' operational time reaches 40 000 h. The microsatellite BIRD has passed the qualification and acceptance test programs and has been launched on 22

  18. Elaboration of thermal control systems on heat pipes for microsatellites Magion 4, 5 and BIRD

    Energy Technology Data Exchange (ETDEWEB)

    Baturkin, V.; Zhuk, S. [National Technical University of Ukraine, Kyiv (Ukraine). Polytechnic Institute; Vojta, J. [Bocni II, Prague (Czech Republic). Institute of Atmospheric Physics; Lura, F.; Biering, B.; Loetzke, H.-G. [Institute of Space Sensor Technology and Planetary Exploration, Berlin (Germany). German Aerospace Center

    2003-06-01

    The strong restricted requirements to mass and power budget of microsatellite subsystems lead to choice of mainly passive thermocontrol system, specifically with heat pipe (HP) integration. An objective of this paper is to present the experience collected by authors in the field of elaboration and flight exploitation of thermocontrol systems (TCS) with heat pipes for microsatellites Magion 4 (1995), Magion 5 (1996) and BIRD (2001). Microsatellites Magion 4, 5 (Project INTERBALL) were completed with TCS including four low-temperature U-shaped heat pipes (fabricated by Kyiv Polytechnic Institute) installed in pairs on symmetrical facets of microsatellites' bodies. Each pair of heat pipes was placed on two general flanges: one combined HP heating zones, the second combined their condensation zones. Heat pipes were fabricated from thin-wall copper shells with capillary structure of metal felt. Flanges were of aluminium, and acetone was used as heat carrier. Rated transferred heat power was not less than 60 W in the range of working temperatures from -20 to +50{sup o}C. TCS for microsatellite BIRD included two U-shaped aluminium ammonia heat pipes (design and manufacture-Kiev Polytechnic Institute) symmetrically placed on opposite faces of the satellite. Heat pipe capillary structure was formed from 30 grooves of rectangular section. Rated transferred heat power reached 90 W in the range of working temperatures from -50 to +60{sup o}C. Symmetrical layout of elements of TCS on microsatellite is the most acceptable due to stability of spatial orientation and geometrical symmetry of microsatellites and to enlarge the reliability of system operation. Microsatellites Magion 4, 5 and their parts have passed the full cycle tests stipulated by Project INTERBALL. Currently Magion 5 active functioning exceeds 4.5 years and heat pipes' operational time reaches 40 000 h. The microsatellite BIRD has passed the qualification and acceptance test programs and has been

  19. Assessment of damages in the district heating pipe cartel

    DEFF Research Database (Denmark)

    Møllgaard, Peter

    2006-01-01

    The pre-insulated pipe cartel was established 1990 in Denmark, was extended to Italy and Germany during 1991 and re-organised in 1994 to cover the entire common market. Cartel members engaged in market sharing, price setting, bid rigging, coordinated predation and delaying of innovation. The...... practice.Keywords: cartel damages, pre-insulated pipesJEL: L13, L41, L61/L95...

  20. Research Progress of MEMS Micro Heat Pipes%MEMS微型热管研究进展

    Institute of Scientific and Technical Information of China (English)

    屈健; 王谦; 吴慧英

    2012-01-01

    MEMS微型热管作为一种新型的热管技术,在微电子、光电池、红外探测头和激光二极管等的热控制方面具有很大的应用前景.首先,介绍了MEMS微型热管的特点和基本工作原理,简单回顾了其发展历程.然后,从MEMS微型热管的加工制作方法、通道尺寸和总体结构特点出发,指出了其优势所在.在此基础上,综述了近年来微型槽道热管、微型毛细泵回路、微型回路热管和微型振荡热管等不同类型MEMS微型热管的研究进展.最后,总结了MEMS微型热管的发展趋势和实际应用所面临的挑战,指出降低制作成本、优化工质充注封装工艺、改进测试手段和加强运行机理研究是今后工作的重点.%The MEMS micro heat pipe, as a novel heat pipe technology, is considered as one of the most promising choices for thermal control applications in microelectronics, photovoltaic cells, infrared detectors, laser diodes, etc. The basic principle and characteristics of MEMS micro heat pipes are firstly introduced, and the development history of which is reviewed briefly. Then, the fabrication method, channel size, and overall structure feature are compared with those of a traditional heat pipe, which account for the advantages of a MEMS micro heat pipe. Based on the discussion above, the progress of the micro grooved heat pipe, micro capillary pumped loop, micro loop heat pipe, micro pulsating heat pipe and other different types of the MEMS micro heat pipes are thoroughly reviewed. Finally, the development tendency and challenges impacting on real applications of MEMS micro heat pipes are prospected, and it is pointed out that the fabrication cost reduction, working fluid filling and packaging optimization, testing method improvement, as well as operational mechanism investigation are identified as major issues for the future research.

  1. Thermal performance of a novel porous crack composite wick heat pipe

    International Nuclear Information System (INIS)

    Highlights: • This research developed a novel porous crack composite wick heat pipe. • Phase change flattening process was proposed to fabricate composite heat pipe. • The composite wick structure was characterized. • Heat transfer limit and thermal resistance were investigated by theoretically and experimentally. - Abstract: A novel porous crack composite wick flattened heat pipe (PCHP) has been developed for electronic device cooling. PCHP was fabricated from grooved–sintered wick cylindrical heat pipe (GSHP) by phase change flattening technology. The composite wick was composed of porous sintered powder structure and axial micro-crack channels. The crack channels of composite wick were characterized and the calculation models of thermal resistance and capillary limit of PCHP were built. An experimental setup was used to test thermal resistance and heat transfer limit. The results showed that the parameters affecting thermal resistance from the most significant to the least one were wick thickness, powder diameter, flattened height, and tear number. The optimal wick thickness of PCHP for the maximum heat transfer limit was about 0.45 mm at flattened height of 3 mm. Heat transfer limit of PCHP increased with powder diameter while decrease of powder diameter could enhance anti-gravity ability of PCHP. Heat transfer limit of PCHP increased with flattened height. The effect of tear number on thermal resistance and heat transfer limit of PCHP could be neglected

  2. High performance felt-metal-wick heat pipe for solar receivers

    Science.gov (United States)

    Andraka, Charles E.; Moss, Timothy A.; Baturkin, Volodymyr; Zaripov, Vladlen; Nishchyk, Oleksandr

    2016-05-01

    Sodium heat pipes have been identified as a potentially effective heat transport approach for CSP systems that require near-isothermal input to power cycles or storage, such as dish Stirling and highly recuperated reheat-cycle supercritical CO2 turbines. Heat pipes offer high heat flux capabilities, leading to small receivers, as well as low exergetic losses through isothermal coupling with the engine. Sandia developed a felt metal wick approach in the 1990's, and demonstrated very high performance1. However, multiple durability issues arose, primarily the structural collapse of the wick at temperature over short time periods. NTUU developed several methods of improving robustness of the wick2, but the resulting wick had limited performance capabilities. For application to CSP systems, the wick structures must retain high heat pipe performance with robustness for long term operation. In this paper we present our findings in developing an optimal balance between performance and ruggedness, including operation of a laboratory-scale heat pipe for over 5500 hours so far. Application of heat pipes to dish-Stirling systems has been shown to increase performance as much as 20%3, and application to supercritical CO2 systems has been proposed.

  3. Modeling of pipe break accident in a district heating system using RELAP5 computer code

    International Nuclear Information System (INIS)

    Reliability of a district heat supply system is a very important factor. However, accidents are inevitable and they occur due to various reasons, therefore it is necessary to have possibility to evaluate the consequences of possible accidents. This paper demonstrated the capabilities of developed district heating network model (for RELAP5 code) to analyze dynamic processes taking place in the network. A pipe break in a water supply line accident scenario in Kaunas city (Lithuania) heating network is presented in this paper. The results of this case study were used to demonstrate a possibility of the break location identification by pressure decrease propagation in the network. -- Highlights: ► Nuclear reactor accident analysis code RELAP5 was applied for accident analysis in a district heating network. ► Pipe break accident scenario in Kaunas city (Lithuania) district heating network has been analyzed. ► An innovative method of pipe break location identification by pressure-time data is proposed.

  4. Characteristics on the heat storage and recovery by the underground spiral heat exchange pipe; Chichu maisetsu spiral kan ni yoru chikunetsu shunetsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Imai, I. [Kure National College of Technology, Hiroshima (Japan); Taga, M. [Kinki University, Osaka (Japan)

    1996-10-27

    The consistency between the experimental value of a soil temperature and the calculation value of a soil temperature given by a non-steady heat conduction equation was confirmed. The experimental value is obtained by laying a spiral heat exchange pipe in the heat-insulated soil box and circulating hot water forcibly in the pipe. The temperature conductivity in soil significantly influences the heat transfer in soil. The storage performance is improved when the temperature conductivity increases because of the contained moisture. As the difference between the initial soil temperature and circulating water temperature becomes greater, the heat storage and recovery values increase. A thermal core heat transfer is done in the spiral pipe. Therefore, the diameter of the pipe little influences the heat storage performance, and the pitch influences largely. About 50 hours after heat is stored, the storage performance is almost the same as for a straight pipe that uses the spiral diameter as a pipe diameter. To obtain the same heat storage value, the spiral pipe is made of fewer materials than the straight pipe and low in price. The spiral pipe is more advantageous than the straight pipe in the necessary motive power and supply heat of a pump. 1 ref., 11 figs., 1 tab.

  5. Thermoelectric Exhaust Heat Recovery with Heat Pipe-Based Thermal Control

    Science.gov (United States)

    Brito, F. P.; Martins, Jorge; Hançer, Esra; Antunes, Nuno; Gonçalves, L. M.

    2015-06-01

    Heat pipe (HP)-based heat exchangers can be used for very low resistance heat transfer between a hot and a cold source. Their operating temperature depends solely on the boiling point of their working fluid, so it is possible to control the heat transfer temperature if the pressure of the HP can be adjusted. This is the case of the variable conductance HPs (VCHP). This solution makes VCHPs ideal for the passive control of thermoelectric generator (TEG) temperature levels. The present work assesses, both theoretically and experimentally, the merit of the aforementioned approach. A thermal and electrical model of a TEG with VCHP assist is proposed. Experimental results obtained with a proof of concept prototype attached to a small single-cylinder engine are presented and used to validate the model. It was found that the HP heat exchanger indeed enables the TEG to operate at a constant, optimal temperature in a passive and safe way, and with a minimal overall thermal resistance, under part load, it effectively reduces the active module area without deprecating the temperature level of the active modules.

  6. 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…

  7. Researches Regarding the Efficiency of Water to Air Heat Exchanger with Heat Pipes for the Mechanical Ventilation System

    Directory of Open Access Journals (Sweden)

    Andrei Burlacu

    2007-01-01

    Full Text Available The present paper proposes the analysis of the efficiency of water to air heat exchanger with heat pipes for the mechanical ventilation system. The performed study is based on the necessity of the unconventional energy forms capitalization, increasing of the energy efficiency and the energy consumption decrease in concordance with the sustainable development concept.

  8. Researches Regarding the Efficiency of Water to Air Heat Exchanger with Heat Pipes for the Mechanical Ventilation System

    OpenAIRE

    Andrei Burlacu; Theodor Mateescu

    2007-01-01

    The present paper proposes the analysis of the efficiency of water to air heat exchanger with heat pipes for the mechanical ventilation system. The performed study is based on the necessity of the unconventional energy forms capitalization, increasing of the energy efficiency and the energy consumption decrease in concordance with the sustainable development concept.

  9. On the stability of a convective motion generated by a chemically reacting fluid in a pipe

    Science.gov (United States)

    Koliskina, V.; Kolyshkin, A.; Volodko, I.; Kalis, H.

    2016-06-01

    Linear stability analysis of a chemically reacting fluid motion in a pipe is performed in the present paper. The reaction rate has an Arrhenius form. The base flow and temperature distribution is obtained from the nonlinear heat equation coupled with the equations of motion. The stability of the flow with respect to asymmetric (spiral) perturbations is investigated numerically. The critical Grasshof number of the flow depends on two dimensionless parameters: the Prandtl number and the Frank-Kamenetsky parameter. The increase of both parameters has a destabilizing influence on the flow. It is shown that the second branch of a marginal stability curve corresponding to smaller critical Grasshof numbers appears as the Prandtl number increases.

  10. Thermodynamic Analysis of a Heat Pipe-thermal Jet Refrigeration System

    OpenAIRE

    Mukilan S. Michael; R. BharathViswanath; Suresh, M.

    2013-01-01

    Presently the emphasis is to utilize renewable energy sources such as solar energy, geothermal energy, ocean thermal energy, etc. and waste heat from industrial processes, to produce refrigeration. The aim of many researchers was to develop thermal refrigerator and heat pump systems using heat energy as energy input for achieving better performance, compactness and cost effectiveness. In the present study, a simple thermal jet refrigerator is constituted into a heat pipe system and a th...

  11. Experimental investigation of silver nano-fluid on heat pipe thermal performance

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Shung-Wen; Wei, Wei-Chiang; Yang, Shih-Yu [Department of Mechanical and Electro-Mechanical Engineering,Tamkang University, 151, Ying-Chuan Road, Tamsui, 25137 Taipei (Taiwan); Tsai, Sheng-Hong [Department of Mechanical Engineering, St. John' s University, 499, Sec. 4, Tam-King Road, Tamsui, 25137 Taipei (Taiwan)

    2006-12-15

    Nano-fluid is employed as the working medium for a conventional 211{mu}mwidex217{mu}m deep grooved circular heat pipe. The nano-fluid used in this study is an aqueous solution of 35nm diameter silver nano-particles. The experiment was performed to measure the temperature distribution and to compare the heat pipe thermal resistance using nano-fluid and DI-water. The tested nano-particle concentrations ranged from 1mg/l to 100mg/l. The condenser section of the heat pipe was attached to a heat sink that was cooled by water supplied from a constant-temperature bath maintained at 40{sup o}C. At a same charge volume, the measured nano-fluid filled heat pipe temperature distribution demonstrated that the thermal resistance decreased 10-80% compared to DI-water at an input power of 30-60W. The measured results also show that the thermal resistances of the heat pipe decrease as the silver nano-particle size and concentration increase. (author)

  12. Experiments on Heat Transfer Performance Assessment of Multi-Pod Heat Pipe in presence of Non-condensable gas

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Gyeongho; Kim, Sangnyung [Kyung Hee Univ., Yongin (Korea, Republic of)

    2014-05-15

    Multi-Pod Heat Pipe (MPHP) is a new safety concept in which Two-Phase Closed Thermosyphon (TPCT) that makes heat exchange without separate external power supply using the phase change of working fluid is applicable to Passive Containment Cooling System (PCCS). The previous study explored the temperature and pressure variation of MPHP. To assess the heat transfer performance of MPHP, further experiment was conducted by increasing the capacity of heater. Such array of pipes will lead to a higher weight fraction of air, non-condensable gas, at the center of pipe assembly. In this study, experiments on the effect of heat transfer inhibition on non-condensable gas were conducted by increasing injection heat up to 10∼25kW as well as injecting a certain amount of air. As a result of this experiment, conclusions are as follows. In the case of MPHP assembly with the same length of 1m of Boiling region and condenser region, it is possible to remove heat up to about 20kW. Applying nuclear power plant for the equal distribution of working fluid requires considerations. To apply nuclear power plant, further research is needed through computer simulation of heat transfer rate depending on the number of pipe.

  13. How to protect underground water flowing into Fukushima Nuclear Facility. Using by heat pipes and LNG

    International Nuclear Information System (INIS)

    We invented an innovative artificial permafrost forming method to prevent the flowing of under-ground water into Fukushima nuclear facility. In this proposal, heat pipes are embedded at all around of the nuclear facility to cool the hygroscopic soil effectively, and LNG is used as both a cold source and the fuel of 1,000,000,000W gas-turbine electric generator. We calculated artificial permafrost wall forming by transient calculation at several condition, and we also calculated maximum amount of heat transport of heat pipe. Based on the result, we confirmed that this proposal have a good feasibility. Finally, we estimated the total cost of this proposal. (author)

  14. Using a heat pipe (TPTC for dissipating energy generated by an electronic circuit

    Directory of Open Access Journals (Sweden)

    Rodrigo Correa

    2010-07-01

    Full Text Available This paper presents an experimental investigation aimed at estimating the thermal efficiency of a heat pipe compared to the most common elements for removing heat from a circuit (i.e., an electric fan and a fin - extended surface. The input voltage frequency for a standard power circuit was changed for the experiments, whilst all the other parameters were kept constant. An experimental statistical design was used as an analytical tool. Unexpectedly, the heat pipe showed the lowest thermal efficiency for all the experiments, although it had the advantage of being a passive element having low volume and no mobile parts.

  15. Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project

    Science.gov (United States)

    Tower, L. K.; Kaufman, W. B.

    1977-01-01

    A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.

  16. Heat transfer characteristics of Sphere-Packed Pipe flow under high Reynolds number

    International Nuclear Information System (INIS)

    Sphere-Packed Pipe (SPP) flows for different diameter ratios of the pipe to the sphere are experimentally evaluated in order to clarify a correlation between the heat transfer and the pressure drop characteristics. Working fluid is water and the flow conditions are under ReD=2000 - 33000 and Pr=5.2 - 5.5. The results show that the pressure drops in the SPP flows don't exactly correspond to the Ergun's correlation and the drag model correlation. The empirical correlation for averaged Nusselt number is proposed and heat transfer performance of the SPP flows are compared with the other passive heat transfer enhancement technique. (author)

  17. Vapor Flow Patterns During a Start-Up Transient in Heat Pipes

    Science.gov (United States)

    Issacci, F.; Ghoniem, N, M.; Catton, I.

    1996-01-01

    The vapor flow patterns in heat pipes are examined during the start-up transient phase. The vapor core is modelled as a channel flow using a two dimensional compressible flow model. A nonlinear filtering technique is used as a post process to eliminate the non-physical oscillations of the flow variables. For high-input heat flux, multiple shock reflections are observed in the evaporation region. The reflections cause a reverse flow in the evaporation and circulations in the adiabatic region. Furthermore, each shock reflection causes a significant increase in the local pressure and a large pressure drop along the heat pipe.

  18. Dynamic performance of a novel solar photovoltaic/loop-heat-pipe heat pump system

    International Nuclear Information System (INIS)

    Highlights: • A transient model was developed to predict dynamic performance of new PV/LHP system. • The model accuracy was validated by experiment giving less than 9% in error. • The new system had basic and advanced performance coefficients of 5.51 and 8.71. • The new system had a COP 1.5–4 times that for conventional heat pump systems. • The new system had higher exergetic efficiency than PV and solar collector systems. - Abstract: Objective of the paper is to present an investigation into the dynamic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for potential use in space heating or hot water generation. The methods used include theoretical computer simulation, experimental verification, analysis and comparison. The fundamental equations governing the transient processes of solar transmission, heat transfer, fluid flow and photovoltaic (PV) power generation were appropriately integrated to address the energy balances occurring in different parts of the system, e.g., glazing cover, PV cells, fin sheet, loop heat pipe, heat pump cycle and water tank. A dedicated computer model was developed to resolve the above grouping equations and consequently predict the system’s dynamic performance. An experimental rig was constructed and operated under the real weather conditions for over one week in Shanghai to evaluate the system living performance, which was undertaken by measurement of various operational parameters, e.g., solar radiation, photovoltaic power generation, temperatures and heat pump compressor consumption. On the basis of the first- (energetic) and second- (exergetic) thermodynamic laws, an overall evaluation approach was proposed and applied to conduct both quantitative and qualitative analysis of the PV/LHP module’s efficiency, which involved use of the basic thermal performance coefficient (COPth) and the advanced performance coefficient (COPPV/T) of such a system. Moreover, a simple comparison

  19. Analysis Of The Extrusion Process Of A Square Tube Multi-Channel Heat Pipe

    Directory of Open Access Journals (Sweden)

    Kim K.S.

    2015-06-01

    Full Text Available Heat pipes have been recently in use for cooling purposes in various fields, including electronic circuit boards and vehicle parts that generate large amounts of heat. In order to minimize the loss of heat transferred, there is a need to maximize the contact area of the working fluid. This study produced a square tube multi-channel heat pipe to replace the existing circular pipe type to maximize the internal surface area thereof. This expands the surface, allowing the working fluid to come into contact with a wider area and enhancing thermal radiation performance. A mold for the production for such a product was designed, and finite element simulation was performed to determine whether production is possible.

  20. Numerical Investigation of Heat Transfer Enhancement in a Rectangular Heated Pipe for Turbulent Nanofluid

    Directory of Open Access Journals (Sweden)

    Hooman Yarmand

    2014-01-01

    Full Text Available Thermal characteristics of turbulent nanofluid flow in a rectangular pipe have been investigated numerically. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM. The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated. Four different types of nanoparticles Al2O3, ZnO, CuO, and SiO2 at different volume fractions of nanofluids in the range of 1% to 5% are considered in the present investigation. In this paper, effect of different Reynolds numbers in the range of 5000 < Re < 25000 on heat transfer characteristics of nanofluids flowing through the channel is investigated. The numerical results indicate that SiO2-water has the highest Nusselt number compared to other nanofluids while it has the lowest heat transfer coefficient due to low thermal conductivity. The Nusselt number increases with the increase of the Reynolds number and the volume fraction of nanoparticles. The results of simulation show a good agreement with the existing experimental correlations.

  1. Study on residual stress across the pipes' thickness using outer surface rapid heating. Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

    International Nuclear Information System (INIS)

    The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)

  2. Recommendations for Pipes Selections in Heating and Cooling Systems

    OpenAIRE

    Cătălin Popovici; Jan Ignat

    2009-01-01

    The present study finds it’s purpose in stressing that pipes selection is not just a matter of „how it is used”, or „how much does it costs” but also a question of „where” . Using experience of other countries, the work has at the basis calculation values from France, USA and UK and recommends selection tables of pipes diameters for low, medium and high pressure drops. Also, it illustrates the diameter choice in two different situations based on the economic criteria.

  3. Recommendations for Pipes Selections in Heating and Cooling Systems

    Directory of Open Access Journals (Sweden)

    Cătălin Popovici

    2009-01-01

    Full Text Available The present study finds it’s purpose in stressing that pipes selection is not just a matter of „how it is used”, or „how much does it costs” but also a question of „where” . Using experience of other countries, the work has at the basis calculation values from France, USA and UK and recommends selection tables of pipes diameters for low, medium and high pressure drops. Also, it illustrates the diameter choice in two different situations based on the economic criteria.

  4. Effect of pipe insulation losses on a loss-of-heat sink accident for an LMR

    International Nuclear Information System (INIS)

    The efficacy of pipe radiation losses as a heat sink during LOHS in a loop-type LMR plant is investigated. The Super System Code (SSC), which was modified to include pipe radiation losses, was used to simulate such an LOHS in an LMR plant. In order to enhance these losses, the pipes were assumed to be insulated by rock wool, a material whose thermal conductivity increases with increasing temperature. A transient was simulated for a total of eight days, during which the coolant temperatures peaked well below saturation conditions and then declined steadily. The coolant flow rate in the loop remained positive throughout the transient

  5. Two-Pipe Chilled Beam System for Both Cooling and Heating of Office Buildings

    OpenAIRE

    Afshari, Alireza; Gordnorouzi, Rouzbeh; Hultmark, Göran; Bergsøe, Niels Christian

    2013-01-01

    Simulations were performed to compare a conventional 4-pipe chilled beam system and a 2-pipe chilled beam system. The objective was to establish requirements, possibilities and limitations for a well-functioning 2-pipe chilled beam system for both cooling and heating of office buildings. The building model had a net volume of 3669 m3, (L*B: 25.5m*11.5 m) and net ceiling height of 2.55 m. The building model was assumed to consist of 78 office rooms, 6 meeting rooms and 5 corridors with a 50% o...

  6. Decision on Leakage of Heat-supply Pipe Network Based on Multi-sensor Information Merge

    OpenAIRE

    Pan-pan Zhao; Xiu-fang Wang; Hong-bo Bi; Qi Yang

    2013-01-01

    The complicated structure of heat-supply pipe network leads to the issue that the leakage position is difficult to locate by a single sensor. We propose to exploit the merge information by multi-sensor to determine the leakage pipeline section. The mathematical model is first established according to the topology of the pipe network. Furthermore, We present the concept of leakage time difference vector group and assign the elementary probability according to the cosine of the intersection ang...

  7. Design, fabrication and performance tests for a polymer-based flexible flat heat pipe

    International Nuclear Information System (INIS)

    Highlights: ► Fabrication of a polymer-based flexible flat heat pipe. ► Bending angle of 15° will lead to a better thermal performance of the system. ► Powers higher than 12.67 W can be transferred/delivered. - Abstract: In this paper, we report on the novel design, fabrication and performance tests for a polymer-based flexible flat heat pipe (FHP) with a bending angle in the range of 15–90°. Each heat pipe is 4 mm thick, 20 mm wide and 80 mm long, with two layers of No. 250 copper mesh as the wicking material. A copper/silicone rubber hybrid structure is designed and fabricated to achieve the flexibility of the heat pipe. Thermal characteristics are measured and studied for de-ionized water under different working conditions. Experimental results reveal that a bending angle of 15° on the vertical plane has a better thermal performance than those of heat pipes with/without bending. In addition, a higher power of 12.67 W can be transferred/delivered

  8. Heat sink welding of austenitic stainless steel pipes to control distortion and residual stress

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, H.; Albert, S.K.; Bhaduri, A.K. [Materials Technology Div., Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2007-07-01

    Construction of India's Prototype Fast Breeder Reactor (PFBR) involves extensive welding of austenitic stainless steels pipes of different dimensions. Due to high thermal expansion coefficient and poor thermal conductivity of this class of steels, welding can result in significant distortion of these pipes. Attempts to arrest this distortion can lead to high levels of residual stresses in the welded parts. Heat sink welding is one of the techniques often employed to minimize distortion and residual stress in austenitic stainless steel pipe welding. This technique has also been employed to repair welding of the piping of the Boiling Water Reactors (BWRs) subjected to radiation induced intergranular stress corrosion cracking (IGSCC). In the present study, a comparison of the distortion in two pipe welds, one made with heat sink welding and another a normal welds. Pipes of dimensions 350{phi} x 250(L) x 8(t) mm was fabricated from 316LN plates of dimensions 1100 x 250 x 8 mm by bending and long seam (L-seam) welding by SMAW process. Two fit ups with a root gap of 2 mm, land height of 1mm and a groove angle of 70 were prepared using these pipes for circumferential seam (C-seam) welding. Dimensions at predetermined points in the fit up were made before and after welding to check the variation in radius, circumference and and ovality of the pipes. Root pass for both the pipe fit up were carried out using conventional GTAW process with 1.6 mm AWS ER 16-8-2 as consumables. Welding of one of the pipe fit ups were completed using conventions GTAW process while the other was completed using heat sink welding. For second and subsequent layers of welding using this process, water was sprayed at the root side of the joint while welding was in progress. Flow rate of the water was {proportional_to}6 1/minute. Welding parameters employed were same as those used for the other pipe weld. Results of the dimensional measurements showed that there is no circumferential shrinkage in

  9. Temporal deterioration in thermal performance of screen mesh wick straight heat pipe using surfactant free aqueous nanofluids

    Science.gov (United States)

    Bhullar, Bhupinder Singh; Gangacharyulu, D.; Das, Sarit K.

    2016-04-01

    The study investigates the temporal performance of heat pipe using surfactant free Al2O3/De-ionised water nanofluids. The nanofluids prone to agglomeration and sedimentation with time are expected to influence the performance of heat pipe. Specially fabricated heat pipe is made to accommodate vapor velocity fluctuation through the vapor core and the end cap brazing effects. The heat pipe filled up to 40 % of the evaporator volume is tested at increasing volume concentration (0.005, 0.05, 0.5, 1 vol%) of Al2O3/De-ionised water nanofluid. The thermal performance of heat pipe is tested at three watt loads of heat input (12, 32, 72 W) and after successive durations (0, 3, 6, 9 months) from the date of manufacturing with non operational time span. The results are compared after successive time intervals and with deionised water as working fluid. Despite higher thermal performance of heat pipe observed using nanofluids as working fluids, consistency and reliability in heat pipe operating characteristics has been observed at high watt load heat input of 72 W as compared to low watt heat of 12 W. The thermal performance improvement of heat pipe using the nanofluid resulted due to nano-coating of Al2O3 nanoparticles on the mesh, resulting in localized high vapor pressure caused by the subsequent intermittent accelerated flow, reduction of contact angle and enhancement in boiling limit.

  10. Numerical study of finned heat pipe-assisted thermal energy storage system with high temperature phase change material

    International Nuclear Information System (INIS)

    Highlights: • A finned heat pipe-assisted latent heat thermal energy storage system is studied. • The effects of heat pipes spacing and fins geometrical features are investigated. • Smaller heat pipes spacing and longer fins improve the melting rate. • The optimal heat pipe and fin arrangements are determined. - Abstract: In the present study, the thermal characteristics of a finned heat pipe-assisted latent heat thermal energy storage system are investigated numerically. A transient two-dimensional finite volume based model employing enthalpy-porosity technique is implemented to analyze the performance of a thermal energy storage unit with square container and high melting temperature phase change material. The effects of heat pipe spacing, fin length and numbers and the influence of natural convection on the thermal response of the thermal energy storage unit have been studied. The obtained results reveal that the natural convection has considerable effect on the melting process of the phase change material. Increasing the number of heat pipes (decreasing the heat pipe spacing) leads to the increase of melting rate and the decrease of base wall temperature. Also, the increase of fin length results in the decrease of temperature difference within the phase change material in the container, providing more uniform temperature distribution. It was also shown that number of the fins does not have a significant effect on the performance of the system

  11. THEORETICAL STUDY OF HEAT TRANSFER ENHANCEMENT IN PIPE WITH POROUS BODY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A theoretical investigation of the fluid flow and heat transferin a pipe with porous body of high porosity twis ted by metal wire was carried out. A theoretical model of a circular pipe with porous matrix attached at the channel wall and extended inward the centerline was set up. Through ana lyzing the flow in the porous matrix by the Brinkman-extend ed-Darcy equation and through including the effect of disper sion by adding the dispersion coefficient into the energy equa tion, the theoretical solutions of velocity distribution and temperature fields were obtained. Finally the effect of the properties of the porous matrix on the flow and heat transfer in the porous body was studied, which indicates that dispersion can really enhance the heat transfer in pipe.

  12. Method for optimal design of pipes for low-energy district heating, with focus on heat losses

    DEFF Research Database (Denmark)

    Dalla Rosa, Alessandro; Li, Hongwei; Svendsen, Svend

    2011-01-01

    -effective solutions for DH networks in low-heat density areas. We start with a review of theories and methods for steady-state heat loss calculation. Next, the article shows how detailed calculations with 2D-modeling of pipes can be carried out by means of computer software based on the finite-element method (FEM......The synergy between highly energy-efficient buildings and low-energy district heating (DH) systems is a promising concept for the optimal integration of energy-saving policies and energy supply systems based on renewable energy (RE). Network transmission and distribution heat loss is one of the key...... showed the influence of the soil temperature throughout the year. Finally, the article describes proposals for the optimal design of pipes for low-energy applications and presents methods for decreasing heat losses....

  13. Physical concept and calculation of boiling point in a pulsating heat pipe

    OpenAIRE

    Naumova A. N.; Kravets V. Yu.; Nikolaenko Yu. E.

    2014-01-01

    LED development is accompanied by the need to ensure a constructive solution for the thermal conditions problem. For this purpose one can use pulsating heat pipes (PHP), that operate more efficiently after the start of heat carrier boiling. This article describes the physical representation and formula that allows determining the boiling point, which is a lower bound of the PHP effective operating range. It is shown that the main factors influencing the required heat flow are driving capillar...

  14. Physical mechanisms involved in grooved flat heat pipes: experimental and numerical analyses

    OpenAIRE

    Lips, S.; Lefevre, F.; Bonjour, J.

    2011-01-01

    An experimental database, obtained with flat plate heat pipes (FPHP) with longitudinal grooves is presented. The capillary pressure measured by confocal microscopy and the temperature field in the wall are presented in various experimental conditions (vapour space thickness, filing ratio, heat transfer rate, tilt angle, fluid). Coupled hydrodynamic and thermal models are developed. Experimental results are compared to results of numerical models. Physical mechanisms involved in grooved heat p...

  15. Anti-Gravity Loop-shaped heat pipe with graded pore-size wick

    International Nuclear Information System (INIS)

    An Anti-Gravity Loop-Shaped Heat Pipe (AGLSHP) with a Continuous Graded Pore-Size Wick (CGPSW) was developed for the cooling of electronic devices at the anti-gravity orientation on the ground. At this orientation, heat is transferred toward the direction of the gravitational field. The AGLSHP consists of an evaporator, a condenser, a vapor line and a liquid line. The CGPSW is formed by sintered copper powders and it is filled inside the evaporator and the liquid line. The corresponding test system was developed to investigate the start-up characteristics and heat transfer performance of the AGLSHP at the anti-gravity orientation. The experimental result shows that, the AGLSHP has the capability to start-up reliably without any temperature overshoot or oscillation at the test heat loads. And the AGLSHP is able to keep the temperature of the evaporator below 105 °C and the overall thermal resistance below 0.24 °C/W at the heat load of 100 W. It is also found that the ideal heat load range of the AGLSHP at the anti-gravity orientation is from 30 W to 90 W. In this power range the overall thermal resistance stabilizes at about 0.15 °C/W, and the maximum temperature of the evaporator is lower than 84 °C at the heat load of 90 W. - Highlights: ► We present a loop-shaped heat pipe for the anti-gravity application on the ground. ► We present the continuous graded pore-size wick and its fabrication process. ► We test the start-up and heat transfer performance of this loop-shaped heat pipe. ► This loop-shaped heat pipe starts up reliably and has satisfying heat transfer capability.

  16. Thermal protection mechanism of heat pipe in leading edge under hypersonic conditions

    OpenAIRE

    Peng Wengen; He Yurong; Wang Xinzhi; Zhu Jiaqi; Han Jiecai

    2015-01-01

    Sharp local structure, like the leading edge of hypersonic aircraft, confronts a severe aerodynamic heating environment at a Mach number greater than 5. To eliminate the danger of a material failure, a semi-active thermal protection system is proposed by integrating a metallic heat pipe into the structure of the leading edge. An analytical heat-balance model is established from traditional aerodynamic theories, and then thermal and mechanical characteristics of the structure are studied at Ma...

  17. Mathematical modeling of steady-state operation of a loop heat pipe

    International Nuclear Information System (INIS)

    A steady-state mathematical model of a loop heat pipe is established and compared with experimental results in this work. The modeling of the evaporator wick includes not only the single-layer wick, but also the two-layer compound wick. The annular flow model is adopted in the modeling of the condenser, in which the effect of surface tension of liquid and the interaction between the liquid and vapor phases including both frictional and momentum-transfer shear stresses are considered. The model can predict the decreasing length of the condenser two-phase zone under the constant conductance mode caused by the volume expansion of the liquid in the compensation chamber, and is in good agreement with the experimental data. It also shows that the application of the two-layer compound wick can improve the performance of the loop heat pipe operating under the variable conductance mode, due to the reduction of heat leak from the evaporator to the compensation chamber. A parametric study of the effect of heat sink temperature, ambient temperature, adverse elevation, and working fluid inventory on the operating temperatures of the loop heat pipe is also conducted, which further contributes to the understanding of the steady-state operating characteristics of loop heat pipes.

  18. Natural convection in inclined pipes - A new correlation for heat transfer estimations

    Science.gov (United States)

    Langebach, R.; Haberstroh, Ch.

    2014-01-01

    Heat intake minimization is one of the main challenges during the design process of cryogenic storage tanks. It is widely known that connection pipes significantly contribute to this residual heat transfer from ambient temperature conditions to the cold inner vessel. A certain pipe inclination can cause a convective flow field within the fluid. This effect usually increases the total heat transfer much more dramatically than anticipated. In several previous papers we discussed the impact of pipe geometry as well as boundary conditions intensively. However, there is no suitable correlation in literature available which could be used to estimate the total heat transfer properly. The large number of experimental data we gained during our investigations allows us to propose a new correlation in order to predict the total heat transfer through an inclined pipe in function of the inclination angle. In this paper we derivate this new correlation and show its application for heat transfer estimations. Several comparisons are carried out against our own measurements as well as literature data.

  19. Peach Bottom 2 and 3 regenerative heat exchangers: chemical decontamination and solidification

    International Nuclear Information System (INIS)

    In 1977, Dow Nuclear Services, under contract to Philadelphia Electric Company, chemically decontaminated the regenerative heat exchangers at the Peach Bottom 2 and 3 Atomic Power Station. The purpose of the decontamination was to reduce the radiation levels associated with the subsequent heat exchanger repairs to be performed by PECO maintenance. Samples of piping from the regenerative heat exchangers were analyzed at Dow Chemical, Midland, Michigan, and solvent testing and selection was performed. Nuclear Solvent-1 was selected. Temporary equipment, piping and radiation shielding was installed to perform all necessary functions safely. All designs and procedures were approved by the Peach Bottom Plant Operations Review Committee. The chemical decontamination removed 10.6 curies of radioactive material in the case of Peach Bottom 3 and similarly at Peach Bottom 2, 6.3 curies of material was removed. Radioactive waste generated by decontamination that could not be treated by existing facilities was successfully solidified by the Dow Solidification process

  20. Experimental Analysis of Thermal Stratification in a Heat Storage Tank Using Stratification Pipe

    Science.gov (United States)

    Boloņina, A.; Rochas, C.; Blumberga, D.

    2009-01-01

    The heat storage tank is an important element in any heating system where the heat source is not able to provide heat accordingly to consumer demand (for example solar collector systems, solid fuel boilers etc). Better heat storage efficiency can be achieved by providing good thermal stratification in the heat storage tanks. One of the best methods of increasing the degree of thermal stratification is the stratification pipes. In the Environmental monitoring laboratory of the Institute of Energy Systems and Environment (Riga Technical University, an experimental heat storage system has been developed and used for testing and studying stratification devices under different thermodynamic and hydraulic conditions. The experimental study carried out on the efficiency of the stratification pipe produced by German company SOLVIS Solar Systeme GmbH under different flow parameters, has been analyzed. The main aim of the experimental study was to define optimal heating system operation parameters to achieve good performance of the stratification pipe and a high degree of thermal stratification in the heat storage tank.

  1. Experimental Investigation of Solar Panel Cooling by a Novel Micro Heat Pipe Array

    OpenAIRE

    Zhenhua Quan; Yaohua Zhao; Xiao Tang

    2010-01-01

    A novel micro heat pipe array was used in solar panel cooling. Both of air-cooling and water-cooling conditions under nature convection condition were investigated in this paper. Compared with the ordinary solar panel, the maximum difference of the photoelectric conversion efficiency is 2.6%, the temperature reduces maximally by 4.7℃, the output power increases maximally by 8.4% for the solar panel with heat pipe using air-cooling, when the daily radiation value is 26.3 MJ. Compared with the ...

  2. Construction and testing of ceramic fabric heat pipe with water working fluid

    Science.gov (United States)

    Antoniak, Zenen I.; Webb, Brent J.; Bates, James M.; Cooper, Matthew F.

    1991-01-01

    A prototype ceramic fabric/titanium water heat pipe has been constructed and tested; it transported 25 to 80 W of power at 423 K. Component development and testing is continuing with the aim of providing an improved prototype, with a 38 micron stainless steel liner covered by a biaxially-braided Nextel (trademark) sleeve that is approximately 300 microns thick. This fabric has been tested to 800 K, and its emittance is about 0.5 at that temperature. Advanced versions of the water heat pipe will probably require a coating over the ceramic fabric in order to increase this emittance to the 0.8 to 0.9 range.

  3. Wind tunnel data of the analysis of heat pipe and wind catcher technology for the built environment

    Directory of Open Access Journals (Sweden)

    John Kaiser Calautit

    2015-12-01

    Full Text Available The data presented in this article were the basis for the study reported in the research articles entitled ‘Climate responsive behaviour heat pipe technology for enhanced passive airside cooling’ by Chaudhry and Hughes [10] which presents the passive airside cooling capability of heat pipes in response to gradually varying external temperatures and related to the research article “CFD and wind tunnel study of the performance of a uni-directional wind catcher with heat transfer devices” by Calautit and Hughes [1] which compares the ventilation performance of a standard roof mounted wind catcher and wind catcher incorporating the heat pipe technology. Here, we detail the wind tunnel test set-up and inflow conditions and the methodologies for the transient heat pipe experiment and analysis of the integration of heat pipes within the control domain of a wind catcher design.

  4. Wind tunnel data of the analysis of heat pipe and wind catcher technology for the built environment.

    Science.gov (United States)

    Calautit, John Kaiser; Chaudhry, Hassam Nasarullah; Hughes, Ben Richard

    2015-12-01

    The data presented in this article were the basis for the study reported in the research articles entitled 'Climate responsive behaviour heat pipe technology for enhanced passive airside cooling' by Chaudhry and Hughes [10] which presents the passive airside cooling capability of heat pipes in response to gradually varying external temperatures and related to the research article "CFD and wind tunnel study of the performance of a uni-directional wind catcher with heat transfer devices" by Calautit and Hughes [1] which compares the ventilation performance of a standard roof mounted wind catcher and wind catcher incorporating the heat pipe technology. Here, we detail the wind tunnel test set-up and inflow conditions and the methodologies for the transient heat pipe experiment and analysis of the integration of heat pipes within the control domain of a wind catcher design. PMID:26958604

  5. Heat Pipe Powered Stirling Conversion for the Demonstration Using Flattop Fission (DUFF) Test

    Science.gov (United States)

    Gibson, Marc A.; Briggs, Maxwell H.; Sanzi, James L.; Brace, Michael H.

    2013-01-01

    Design concepts for small Fission Power Systems (FPS) have shown that heat pipe cooled reactors provide a passive, redundant, and lower mass option to transfer heat from the fuel to the power conversion system, as opposed to pumped loop designs typically associated with larger FPS. Although many systems have been conceptually designed and a few making it to electrically heated testing, none have been coupled to a real nuclear reactor. A demonstration test named DUFF Demonstration Using Flattop Fission, was planned by the Los Alamos National Lab (LANL) to use an existing criticality experiment named Flattop to provide the nuclear heat source. A team from the NASA Glenn Research Center designed, built, and tested a heat pipe and power conversion system to couple to Flattop with the end goal of making electrical power. This paper will focus on the design and testing performed in preparation for the DUFF test.

  6. Application experience of gas-thermal aluminum coatings to protect the pipes for underground construction and repair of heat networks

    Science.gov (United States)

    Kolpakov, A. S.

    2013-11-01

    Questions of sacrificial protection for pipes of underground heat networks with aluminum against the external corrosion are considered. The description of pilot production of pipes with a plasma aluminum coating and the deposition of a sacrificial gas-plasma aluminum coating on weld joints of pipelines and the zone of their thermal influence during assemblage is presented. Examples of repairing the segments of distribution heat networks by the pipes with the tread protection are presented.

  7. The influence of pipe length on thermal statistics computed from DNS of turbulent heat transfer

    International Nuclear Information System (INIS)

    Highlights: ► Study of effects of streamwise periodicity on turbulent heat transfer in pipe flow. ► Streamwise periodic length for convergence depends on the type of statistics and Pr. ► Explain the reasons for variation of thermal statistics in published literature. ► All statistics seem to converge with DNS carried out with a pipe length of 8πδ. - Abstract: We present results from direct numerical simulation of turbulent heat transfer in pipe flow at a bulk flow Reynolds number of 5000 and Prandtl numbers ranging from 0.025 to 2.0 in order to examine the effect of streamwise pipe length (πδ ≡ πD/2 ⩽ L ⩽ 12πδ) on the convergence of thermal turbulence statistics. Various lower and higher order thermal statistics such as mean temperature, rms of fluctuating temperature, turbulent heat fluxes, two-point auto and cross-correlations, skewness and flatness were computed and it is found that the value of L required for convergence of the statistics depends on the Prandtl number: larger Prandtl numbers requires comparatively shorter pipe length for convergence of most of the thermal statistics.

  8. Effect of swirl flow on heat transfer characteristics in a circular pipe

    Science.gov (United States)

    Siddique, Hossain; Hoque, Md. Shafkat Bin; Ali, Mohammad

    2016-07-01

    Swirl flow is of great stature in heat transfer enhancement and in numerous engineering applications. In the present numerical study, the swirl flow of water in a circular pipe is considered. Here the Reynolds Number is kept within 2000. The pipe contains stationary blades to produce the swirl flow. The blades are considered heat resistant. The three-dimensional Navier-Stokes equations for incompressible Newtonian fluid flow are used. The code is corroborated by comparing the simulation results with the established Hagen-Poiseuille law. The comparison is quite satisfactory and thus the code is used for present investigation. In this study, the heat transfer performance of the swirl flow is evaluated. Two cases are considered on the outer surface of the pipe: (i) Constant heat flux and (ii) Constant temperature. This investigation reveals that the swirl flow increases the mean outlet temperature in both cases. The effects of the vane angle, pipe length and diameter on heat transfer characteristics are also evaluated.

  9. Methodology for Life Testing of Refractory Metal/Sodium Heat Pipes

    Science.gov (United States)

    Martin, James J.; Reid, Robert S.

    2006-01-01

    The focus of this work was to establish an approach to generate carefully controlled data that can conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. To accomplish this goal acceleration is required to compress 10 years of operational life into 3 years of laboratory testing through a combination of increased temperature and mass fluence. Specific test series have been identi3ed, based on American Society for Testing and Materials (ASTM) specifications, to investigate long term corrosion rates. The refractory metal selected for demonstration purposes is a Molybdenum-44.5%Rhenium alloy formed by powder metallurgy. The heat pipe makes use of an annular crescent wick design formed by hot isostatic pressing of Molybdenum-Rhenium wire mesh. The heat pipes are filled using vacuum distillation and purity sampling is considered. Testing of these units is round-the-clock with 6-month destructive and non-destructive inspection intervals to identify the onset and level of corrosion. Non-contact techniques are employed for providing power to the evaporator (radio frequency induction heating at I to 5 kW per unit) and calorimetry at the condenser (static gas gap coupled water cooled calorimeter). The planned operating temperature range would extend from 1123 to 1323 K. Accomplishments prior to project cancellation included successful demonstration of the heat pipe wick fabrication technique, establishment of all engineering designs, baselined operational test requirements and procurement/assembly of supporting test hardware systems.

  10. Heat transfer performance of an external receiver pipe under unilateral concentrated solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Jianfeng, Lu; Jing, Ding [School of Engineering, Sun Yat-Sen University, Guangzhou 510006 (China); Jianping, Yang [Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education, South China University of Technology, Guangzhou 510640 (China)

    2010-11-15

    The heat transfer and absorption characteristics of an external receiver pipe under unilateral concentrated solar radiation are theoretically investigated. Since the heat loss ratio of the infrared radiation has maximum at moderate energy flux, the heat absorption efficiency will first increase and then decrease with the incident energy flux. The local absorption efficiency will increase with the flow velocity, while the wall temperature drops quickly. Because of the unilateral concentrated solar radiation and different incident angle, the heat transfer is uneven along the circumference. Near the perpendicularly incident region, the wall temperature and absorption efficiency slowly approaches to the maximum, while the absorption efficiency sharply drops near the parallelly incident region. The calculation results show that the heat transfer parameters calculated from the average incident energy flux have a good agreement with the average values of the circumference under different boundary conditions. For the whole pipe with coating of Pyromark, the absorption efficiency of the main region is above 85%, and only the absorption efficiency near the parallelly incident region is below 80%. In general, the absorption efficiency of the whole pipe increases with flow velocity rising and pipe length decreasing, and it approaches to the maximum at optimal concentrated solar flux. (author)

  11. Direct numerical simulation of turbulent heat transfer in pipe flows: Effect of Prandtl number

    Energy Technology Data Exchange (ETDEWEB)

    Redjem-Saad, L. [LETEM, EA 2546, Universite de Marne-la-Vallee, F-77454 Marne-la-Vallee Cedex 2 (France); Ould-Rouiss, M. [LETEM, EA 2546, Universite de Marne-la-Vallee, F-77454 Marne-la-Vallee Cedex 2 (France)], E-mail: ould@univ-mlv.fr; Lauriat, G. [LETEM, EA 2546, Universite de Marne-la-Vallee, F-77454 Marne-la-Vallee Cedex 2 (France)

    2007-10-15

    Direct numerical simulations of heat transfer in a fully developed turbulent pipe flow with isoflux condition imposed at the wall are performed for a Reynolds number based on pipe radius Re = 5500. Main emphasis is placed on Prandtl number effects on turbulent heat transfer in pipe flow. The scaling of mean temperature profiles is investigated in order to derive correct logarithmic law for various Pr. The rms of temperature fluctuations and turbulent heat fluxes are found to increase when increasing Prandtl number. The turbulent Prandtl number, Pr{sub t}, is almost independent of the molecular Prandtl number Pr for Pr {>=} 0.2. The radial distributions of higher order statistics (skewness and flatness) confirm the intermittent behaviour at the close vicinity of the wall; this intermittent behaviour is more pronounced with an increase in Pr. The Nusselt number is in good agreement with the findings of the literature. Probability density functions and joint probability density functions of velocity and temperature fluctuations are used to describe the characteristics of the turbulent flow and heat transfer. The instantaneous flow and thermal fields are plotted in order to analyse the turbulent structures. To explore the impact of the wall curvature on turbulent heat transfer, predictions were compared to available results for channel flow. These comparisons show a slightly more intense temperature fluctuations in the pipe flow.

  12. Thermal-economic multiobjective optimization of heat pipe heat exchanger for energy recovery in HVAC applications using genetic algorithm

    Directory of Open Access Journals (Sweden)

    Sanaye Sepehr

    2014-01-01

    Full Text Available Cost and effectiveness are two important factors of heat pipe heat exchanger (HPHE design. The total cost includes the investment cost for buying equipment (heat exchanger surface area and operating cost for energy expenditures (related to fan power. The HPHE was thermally modeled using e-NTU method to estimate the overall heat transfer coefficient for the bank of finned tubes as well as estimating pressure drop. Fast and elitist non-dominated sorting genetic algorithm (NSGA-II with continuous and discrete variables was applied to obtain the maximum effectiveness and the minimum total cost as two objective functions. Pipe diameter, pipe length, numbers of pipes per row, number of rows, fin pitch and fin length ratio were considered as six design parameters. The results of optimal designs were a set of multiple optimum solutions, called ‘Pareto optimal solutions’. The comparison of the optimum values of total cost and effectiveness, variation of optimum values of design parameters as well as estimating the payback period were also reported for various inlet fresh air volume flow rates.

  13. Heat pipes and two-phase loops with capillary pumping; Caloducs et boucles diphasiques a pompage capillaire

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This workshop on heat pipes and two-phase capillary pumping loops was organized by the French society of thermal engineers. The 11 papers presented during this workshop deal with the study of thermal performances of heat pipes and on their applications in power electronics (cooling of components), and their use in satellites, aircrafts and trains. (J.S.)

  14. Improvements of U-pipe Borehole Heat Exchangers

    OpenAIRE

    Acuña, José

    2010-01-01

    The sales of Ground Source Heat Pumps in Sweden and many other countries are having a rapid growth in the last decade. Today, there are approximately 360 000 systems installed in Sweden, with a growing rate of about 30 000 installations per year. The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a Borehole Heat Exchanger (BHE), a closed loop in a vertical borehole. The fluid transports the heat from the groun...

  15. Validated TRNSYS model for forced circulation solar water heating systems with flat plate and heat pipe evacuated tube collectors

    OpenAIRE

    MC CORMACK, SARAH

    2011-01-01

    PUBLISHED This paper presents a validated TRNSYS model for forced circulation solar water heating systems used in temperate climates. The systems consist of two flat plate collectors (FPC) and a heat pipe evacuated tube collector (ETC) as well as identical auxiliary components. The systems were fitted with an automated unit that controlled the immersion heaters and hot water demand profile to mimic hot water usage in a typical European domestic dwelling. The main component of the TRNSYS mo...

  16. Validated TRNSYS Model for Forced Circulation Solar Water Heating Systems with Flat Plate and Heat Pipe Evacuated Tube Collectors

    OpenAIRE

    Ayompe, Lacour; Duffy, Aidan; MCCORMACK, SARAH; Conlon, Michael

    2011-01-01

    This paper presents a validated TRNSYS model for forced circulation solar water heating systems used in temperate climates. The systems consist of two flat plate collectors (FPC) and a heat pipe evacuated tube collector (ETC) as well as identical auxiliary components. The systems were fitted with an automated unit that controlled the immersion heaters and hot water demand profile to mimic hot water usage in a typical European domestic dwelling. The main component of the TRNSYS model was the T...

  17. Titanium-alloy, metallic-fluid heat pipes for space service

    Science.gov (United States)

    Morris, J. F.

    1979-01-01

    Reactivities of titanium limit its long-term terrestrial use for unprotected heat-pipe envelopes to about 870 K (1100 F). But this external thermochemical limitation disappears when considerations shift to space applications. In such hard-vacuum utilization much higher operating temperatures are possible. Primary restrictions in space environment result from vaporization, thermal creep, and internal compatibilities. Unfortunately, a respected head-pipe reference indicates that titanium is compatible only with cesium from the alkali-metal working-fluid family. This problem and others are subjects of the present paper which advocates titanium-alloy, metallic-fluid heat pipes for long-lived, weight-effective space service between 500 and 1300 K (440 and 1880 F).

  18. CONDENSATION HEAT TRANSFER OF R-134a IN A HELICAL PIPE

    Institute of Scientific and Technical Information of China (English)

    HAN Ji-tian; LIN Cheng-xian; EBADIAN M.A.

    2004-01-01

    Alternative refrigerant R-134a is considered to be ozone-friendly and a potential candidate for replacing the refrigerant R-12 in refrigeration and air-conditioning applications. This paper presents an experimental investigation on condensation heat transfer of the alternative refrigerant R134a flowing inside a helicoidal pipe with the cooling water flowing through the annular helicoidal passage in a counterflow direction. The heat transfer experiments were performed for R-134a mass flow flux ranging from 100 to 420 kg/m2 s with the superheat of the inlet vapor of 2. 8℃ and 8. 3℃, respectively. The average Nusselt numbers were experimentally determined for a helicoidal pipe with the helix axis of vertical direction. In addition, the obtained experimental results were compared with the results for R-134a condensation in straight and helicoidal pipes available in the open literature.

  19. Analytical modelling of the heat transfer to supercritical water in pipe flows

    International Nuclear Information System (INIS)

    The Supercritical Water-Cooled Reactor SCWR is investigated in order to achieve a higher thermal efficiency and to improve the economical competitiveness of light-water reactors. Due to the complex physical behaviour of supercritical water the heat transfer in the cooling channels may exhibit unusual behaviour such as heat transfer deterioration, with associated high temperatures of the cladding material. Among the various methods, e.g. empirical correlations, a lookup table or CFD codes to predict the wall temperatures of a heated channel or pipe the analytical method offers the advantage, that the influence of model parameters can be easily identified and the importance of physical mechanisms of flow and heat transfer can be understood as functions of the model parameters. Therefore, in the present work, an attempt is made to extend existing models for heat transfer in channel or pipe flows to variable-property fluids, i.e. supercritical water in a pipe. Emphasis is laid on the effect of the local maximum of the Prandtl number and the heat capacity near the pseudo-critical temperature on the laminar or turbulent heat transport. The assumption of quasi-fully developed flow, Prantdl's mixing length eddy viscosity turbulence model, the two layer concept of a logarithmic wall-layer and a laminar sub-layer are analytically extended to a fluid with variable properties. The turbulence intensity of the flow is taken into account by a modified turbulence heat capacity, which is obtained by weighted averaging with a probability density function of the turbulent temperature fluctuations. For a given pipe radius, wall heat flux, mass flux and bulk enthalpy the heat- transfer coefficient and the wall temperature can be determined fully analytical. Mechanisms of heat transfer deterioration or enhancement can well be identified in the model. Results are compared to various experiments of heated pipe flows at supercritical pressure, in particular Yamagata 72, Ornatski 71

  20. Heat transfer enhancement in sphere-packed pipes under high Reynolds number conditions

    International Nuclear Information System (INIS)

    In recent design of LHD-type helical reactor FFHR, the first wall is expected to be exposed to the high heat load of almost 1.0 MW/m2, which is removed by high temperature molten salt Flibe flow. The Flibe is a mixture of LiF and BeF2 and has advantages in high heat capacity, reduction of MHD-pressure drop due to its low electric conductivity. The Flibe blanket system, however, needs heat transfer enhancement under high heat flux since the Flibe is categorized as a high Prandtl number fluid. A Sphere-Packed Pipe (SPP) has been proposed as one of heat transfer enhancement techniques for the high Prandtl number fluid. The matrix of SPP is composed of a number of spheres. The fluid is mixed in the process of passing through the complicated flow channels, which leads to high heat transfer performance. In addition, heat conduction between each sphere and a heating wall contributes to the enhancement of heat transport to the center of pipe, which is called fin-effect. However, the complicated structure causes relatively large pressure drop, which means it necessary to exactly solve the trade-off between the heat transfer enhancement and pumping-power increase in order to optimize the design. Although several papers have been published relating to forced-convection heat transfer in SPPs, most of the studies have been performed under low Reynolds number regimes. In this study, therefore, the pressure drop and the heat transfer characteristics of the SPP flow are evaluated under high Reynolds number for different diameter ratios of the pipe to the sphere. A test section is made of a stainless pipe with the diameter of 56 mm and acrylic spheres. The diameters of packed spheres are 18.5 mm, 25.0 mm, 27.6 mm and 42.7 mm, respectively. Water is employed as a working fluid. The pipe wall of 600 mm length is uniformly heated by Joule heating. Experimental results show that the pressure drop in the SPP flows approximately corresponds to the values between Ergun's correlation and

  1. Application Closed-End Oscillating Heat Pipe for Essential Oil Condensation of the Small Scale Essential Oil Refiner

    OpenAIRE

    Sakultala WANNAPAKHE

    2013-01-01

    This research aimed to investigate the design and building of a small scale essential oil refiner by using heat pipes for essential oil condensation. The device structure of the small scale essential oil refiner was divided into 3 sections as follows: 1) the boiler with a heater for heating, 2) the vapor tube, and 3) the condenser unit. Three patterns of condenser unit were investigated: 1) condensation by water circulation, 2) condensation using heat pipes, and 3) condensation using heat pip...

  2. Heat-Pipe Development for Advanced Energy Transport Concepts Final Report Covering the Period January 1999 through September 2001

    Energy Technology Data Exchange (ETDEWEB)

    R.S.Reid; J.F.Sena; A.L.Martinez

    2002-10-01

    This report summarizes work in the Heat-pipe Technology Development for the Advanced Energy Transport Concepts program for the period January 1999 through September 2001. A gas-loaded molybdenum-sodium heat pipe was built to demonstrate the active pressure-control principle applied to a refractory metal heat pipe. Other work during the period included the development of processing procedures for and fabrication and testing of three types of sodium heat pipes using Haynes 230, MA 754, and MA 956 wall materials to assess the compatibility of these materials with sodium. Also during this period, tests were executed to measure the response of a sodium heat pipe to the penetration of water.

  3. Reflux heat-pipe solar receivers for dish-electric systems

    Science.gov (United States)

    Andraka, Charles E.; Diver, Richard B.

    1988-04-01

    The feasibility of competitive, modular bulk electric power from the sun may be greatly enhanced by the use of a reflux heat pipe receiver to combine a heat engine with a paraboloidal dish concentrator. This combination represents a potential improvement over previous successful demonstrations of dish-electric technology in terms of enhanced performance, lower cost, longer life, and greater flexibility in engine design. In the reflux (i.e., gravity assisted) heat pipe receiver, concentrated solar radiation causes liquid metal (sodium, potassium, or NaK) to evaporate. The vapor flows to the engine interface heat exchanger, where it condenses and releases the latent heat. The condensate is returned to the receiver absorber by gravity (refluxing), and distributed over the surface by gravity and/or capillary forces in a wick lining the receiver. It is essentially an adaptation of heat pipe technology to the peculiar requirements of concentrated solar flux, and provides many advantages over conventional heated tub receiver technology. This overview paper describes the current status and future plans for the U.S. Solar Thermal Program reflux receiver development program at Sandia National Laboratories. Current work includes conventional mesh wick receivers, sintered metal wicks, and pool boiler receivers. The relative design merits and concerns of the different approaches and technology development test plans are discussed.

  4. Effect of Heat up Rate on Thermal Stratification in Horizontal Pipe

    Directory of Open Access Journals (Sweden)

    Athar Rasool

    2013-01-01

    Full Text Available Thermal stratification is a well-known phenomenon in pressurizer surge line of pressurized water reactor. The pressurizer surge line has a complex geometry it runs down vertically and horizontally with varying slopes and curvatures connecting pressurizer with the hot leg of the primary loop. The significant thermal stratification is usually observed in horizontal sections of the pressurizer surge line during reactor starting up phase (heat up from cold shut down condition. To study the effect of heat up rate on thermal stratification a simple horizontal pipe model is considered. The pressurizer surge line is typically a 250 to 350mm diameter stainless steel pipe. The dimensions of horizontal pipe are selected on the basis of pressurizer surge line dimensions. The horizontal pipe model inner diameter is 305 mm with thickness of 33.5 mm and length of four diameters. The Pressurized Water Reactor type Nuclear Power Plants operate in the range of dimensionless Froude number 0.02 – 0.2. Four cases for flow velocities ranging between 0.01 and 0.2 m/sec, based on Froude number, are considered. The propensity for stratification of the fluid in a horizontal pipe can be correlated to the dimensionless Richardson number. If the Richardson number is greater than unity thermal stratification is expected to occur and for Richardson number above 10 the natural convection dominates the flow field and a strongly stratified flow can be maintained until either the temperature difference decreases or the flow velocity increases enough to lower the value of Richardson number below 0.1 or less. The Richardson number for the four cases is greater than unity. The transient analysis is performed using commercially available software ANSYS CFX. The transient temperature distribution along the horizontal pipe with different heat up rates is represented in this study. Thermal stratification reduces with increase in heat up rate or flow velocity.

  5. A preliminary study on the mixed convection heat transfer in a horizontal pipe

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Myeong Seon; Chung, Bum Jin [Jeju Nat' l Univ., Jeju (Korea, Republic of)

    2012-10-15

    Mixed convection phenomena have applications in heat exchangers designed for viscous liquids, pipelines used for transporting oil, and heat exchangers for gas flows and have been investigated for numerical study. The experimental studies on the topic are rare due to the limited practical uses. The definitions on the buoyancy coefficient that represent the relative influence of the forced and the natural convection are different by scholars. When the fluid passes through a horizontal heated pipe, the secondary flow patterns of the flows moving upward along inner wall and downward through the centerline of the pipe, appear. Two symmetric counter rotating, spiraling axial flows around the vertical centerline and the heat transfer of the bottom is higher due to the unstable stratification. This study is preliminary experiments for laminar and turbulent mixed convection for horizontal pipe geometries. The diameter of the pipe was 0.026m and lengths were ranging from 0.03m to 0.50m varying the Reynolds number. Experiments were carried out using a copper sulfate electroplating system was adopted for mass transfer based on the analogy concept.

  6. Thermal control of power supplies with electronic packaging techniques. [using low cost heat pipes

    Science.gov (United States)

    1977-01-01

    The integration of low-cost commercial heat pipes in the design of a NASA candidate standard modular power supply with a 350 watt output resulted in a 44% weight reduction. Part temperatures were also appreciably reduced, increasing the environmental capability of the unit. A complete 350- watt modular power converter was built and tested to evaluate thermal performance of the redesigned supply.

  7. Heat pipe based thermal management systems for energy-efficient data centres

    OpenAIRE

    Jouhara, H; Meskimmon, R

    2014-01-01

    This paper investigates the potential applications for heat-pipe based heat exchangers in enhancing the efficiency of data centres’ cooling. The paper starts by assessing current industry practise and highlighting the challenges facing the data-storage industry; illustrating the legislative, technical and commercial constraints that are now, or will be prevalent in the industry as the sector continues to grow to cater for the ever increasing appetite for public sector, commercial and consumer...

  8. Development and testing of passive autocatalytic recombiners cooled by heat pipes

    International Nuclear Information System (INIS)

    A severe accident in a nuclear power plant (NPP) can lead to core damage in conjunction with the release of large amounts of hydrogen. As hydrogen mitigation measure, passive autocatalytic recombiners (PARs) are used in today's pressurized water reactors. PARs recombine hydrogen and oxygen contained in the air to steam. The heat from this exothermic reaction causes the catalyst and its surroundings to heat up. If parts of the PAR heat up above the ignition temperature of the gas mixture, a spontaneous deflagration or detonation can occur. The aim of this work is the prevention of such high temperatures by means of passive cooling of the catalyst with heat pipes. Heat pipes are completely passive heat exchanger with a very high effective thermal conductivity. For a deeper understanding of the reaction kinetics at lower temperatures, single catalytic coated heat pipes are studied in a flow reactor. The development of a modular small-scale PAR model is then based on a test series with cooled catalyst sheets. Finally, the PAR model is tested inside a pressure vessel under boundary conditions similar to a real NPP. The experiments show, that the temperatures of the cooled catalytic sheets stay significantly below the temperature of the uncooled sheets and below the ignition temperature of the gas mixture under any set boundary conditions, although no significant reduction of the conversion efficiency can be observed. As a last point, a mathematical model of the reaction kinetics of the recombination process as well as a model of the fluid dynamic and thermohydraulic processes in a heat pipe are developed with the data obtained from the experiments.

  9. Numerical simulation of heat transfer in a pipe with non-homogeneous thermal boundary condition

    OpenAIRE

    Antoranz Perales, Antonio; Gonzalo Grande, Alejandro; Flores Arias, Óscar; García-Villalba Navaridas, Manuel

    2015-01-01

    Direct numerical simulations of heat transfer in a fully-developed turbulent pipe flow with circumferentially-varying thermal boundary conditions are reported. Three cases have been considered for friction Reynolds number in the range 180–360 and Prandtl number in the range 0.7–4. The temperature statistics under these heating conditions are characterized. Eddy diffusivities and turbulent Prandtl numbers for radial and circumferential directions are evaluated and compared to the values predic...

  10. Heat transfer in turbulent decaying swirl flow in a circular pipe

    Science.gov (United States)

    Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.

    1988-08-01

    Heat transfer coefficients for air are measured along a heated pipe for decaying swirl flow, generated by radial blade cascade. The results are compared with an expression proposed for predicting the heat transfer coefficients in swirling flow. The theoretical predictions are in good agreement with the experimental data, with average and maximum deviations of 7 and 11 percent, respectively. The application of the theoretical approach to the experimental results obtained by other investigators for heat transfer in a decaying swirl flow generated by short-twisted tapes and tangential slots at inlet also give rise to encouraging agreement.

  11. Design and Operation of a Cryogenic Nitrogen Pulsating Heat Pipe

    Science.gov (United States)

    Diego Fonseca, Luis; Miller, Franklin; Pfotenhauer, John

    2015-12-01

    We report the design, experimental setup and successful test results using an innovative passive cooling system called a “Pulsating Heat Pipe” (PHP) operating at temperatures ranging from 77 K to 80 K and using nitrogen as the working fluid. PHPs, which transfer heat by two phase flow mechanisms through a closed loop tubing have the advantage that no electrical pumps are needed to drive the fluid flow. In addition, PHPs have an advantage over copper straps and thermal conductors since they are lighter in weight, exhibit lower temperature gradients and have higher heat transfer rates. PHPs consist of an evaporator section, thermally anchored to a solid, where heat is received at the saturation temperature where the liquid portion of the two-phase flow evaporates, and a condenser where heat is rejected at the saturation temperature where the vapor is condensed. The condenser section in our experiment has been thermally interfaced to a CT cryocooler from SunPower that has a cooling capacity of 10 W at 77 K. Alternating regions of liquid slugs and small vapor plugs fill the capillary tubing, with the vapor regions contracting in the condenser section and expanding in the evaporator section due to an electric heater that will generate heat loads up to 10 W. This volumetric expansion and contraction provides the oscillatory flow of the fluid throughout the capillary tubing thereby transferring heat from one end to the other. The thermal performance and temperature characteristics of the PHP will be correlated as a function of average condenser temperature, PHP fill liquid ratio, and evaporator heat load. The experimental data show that the heat transfer between the evaporator and condenser sections can produce an effective thermal conductivity up to 35000 W/m-K at a 3.5 W heat load.

  12. Study of a Two-Pipe Chilled Beam System for both Cooling and Heating of Office Buildings

    DEFF Research Database (Denmark)

    Gordnorouzi, Rouzbeh; Hultmark, Göran; Afshari, Alireza;

    Active chilled beam systems are used to provide heating and cooling in order to achieve comfortable thermal indoor climate. For heating and cooling applications, an active chilled beam has two water circuits comprising four pipes that supply warm and cold water respectively to the beam coil...... according to the space demand. Lindab Comfort A/S has introduced an active chilled beam system which has just one water circuit (two pipes) that is used for both heating and cooling. The concept is based on high temperature cooling and low temperature heating. In this study the energy saving potential of...... the new two-pipe active chilled beam system is investigated....

  13. Variable Conductance Heat Pipe Cooling of Stirling Convertor and General Purpose Heat Source

    Science.gov (United States)

    Tarau, Calin; Schwendeman, Carl; Anderson, William G.; Cornell, Peggy A.; Schifer, Nicholas A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  14. Low Cost Variable Conductance Heat Pipe for Balloon Payload Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While continuously increasing in complexity, the payloads of terrestrial high altitude balloons need a thermal management system to reject their waste heat and to...

  15. Thermal Analysis of the Divertor Primary Heat Transfer System Piping During the Gas Baking Process

    Energy Technology Data Exchange (ETDEWEB)

    Yoder Jr, Graydon L [ORNL; Harvey, Karen [ORNL; Ferrada, Juan J [ORNL

    2011-02-01

    A preliminary analysis has been performed examining the temperature distribution in the Divertor Primary Heat Transfer System (PHTS) piping and the divertor itself during the gas baking process. During gas baking, it is required that the divertor reach a temperature of 350 C. Thermal losses in the piping and from the divertor itself require that the gas supply temperature be maintained above that temperature in order to ensure that all of the divertor components reach the required temperature. The analysis described in this report was conducted in order to estimate the required supply temperature from the gas heater.

  16. Chemical bond cleavage induced by electron heating

    International Nuclear Information System (INIS)

    Gas emissions from titanium-metalloid compounds (titanium nitride and oxide) have been investigated to understand the effects of a microwave field on chemical reactions. We employed a high vacuum system (PO2 = 10−6 Pa) to observe in situ reductions. For titanium oxides, H-field heating significantly differed from conventional one in terms of oxygen emissions. For titanium nitride, the emissions were also induced by microwave heating. These tendencies were observed at temperatures above 1000 °C. A quantum chemical interpretation is provided to explain the emissions of the gases, and the experimental data is in good agreement with results predicted using the electronic energy band structure.

  17. Theoretical energy saving analysis of air conditioning system using heat pipe heat exchanger for Indian climatic zones

    OpenAIRE

    T.S. Jadhav; M.M. Lele

    2015-01-01

    Heat pipe heat exchanger (HPHX) is an excellent device used for heat recovery in air conditioning systems. The Energy Conservation Building Code (ECBC) – Bureau of Energy Efficiency (BEE) India classifies Indian climatic zones into five categories viz., Hot and Dry (e.g. Ahmedabad, Jodhpur etc), Warm and Humid (e.g. Mumbai, Chennai etc), Composite (e.g. Nagpur, Jaipur etc), Cold (e.g. Guwahati etc) and Temperate (e.g. Bengaluru etc). The literature review indicated that very limited informati...

  18. Investigation of Residual Stress Distributions of Induction Heating Bended Austenitic Stainless Steel (316 Series) Piping

    International Nuclear Information System (INIS)

    The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects

  19. A Temperature-Profile Method for Estimating Flow Processes in Geologic Heat Pipes

    International Nuclear Information System (INIS)

    Above-boiling temperature conditions, as encountered, for example, in geothermal reservoirs and in geologic repositories for the storage of heat-producing nuclear wastes, may give rise to strongly altered liquid and gas flow processes in porous subsurface environments. The magnitude of such flow perturbation is extremely hard to measure in the field. We therefore propose a simple temperature-profile method that uses high-resolution temperature data for deriving such information. The energy that is transmitted with the vapor and water flow creates a nearly isothermal zone maintained at about the boiling temperature, referred to as a heat pipe. Characteristic features of measured temperature profiles, such as the differences in the gradients inside and outside of the heat pipe regions, are used to derive the approximate magnitude of the liquid and gas fluxes in the subsurface, for both steady-state and transient conditions

  20. Heat transfer enhancement in sphere-packed pipes under high Reynolds number conditions

    International Nuclear Information System (INIS)

    Flow analysis in sphere-packed pipes (SPP) for different pipe to sphere diameter ratios was experimentally performed in order to clarify a relationship between the heat transfer and pressure drop characteristics. The experiments, using water as a working fluid, were carried out with ReD = 2000-33,000 and Pr = 5.0-6.0. Experimental results of the pressure drop characteristics were compared with the Ergun's and Drag model correlations. Empirical correlations for the averaged Nusselt number are proposed, and SPP heat transfer performance is compared with that of the swirl flow. Furthermore, the applicability of the SPP system to the first wall cooling is also discussed from the temperature distribution aspect of the heating wall

  1. Numerical predictions of turbulent heat transfer for air flow in rotating pipe

    Energy Technology Data Exchange (ETDEWEB)

    Ould-Rouiss, M., E-mail: ould@univ-mlv.f [Universite Paris-Est, MSME, UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Dries, A. [Universite Paris-Est, MSME, UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Mazouz, A. [Universite de Valenciennes, LMF, 59326 Valenciennes (France)

    2010-08-15

    Heat transfer in fully developed turbulent pipe flow with isoflux condition imposed at the wall is investigated numerically by use of direct numerical simulation (DNS) and large eddy simulation (LES) for various rotation rates (0{<=}N{<=}7) at a Reynolds number equal to 5500. To validate the present computations, predictions are compared to the results reported in the archival literature, and found to agree fairly well with them. With increasing rotation number, the temperature fluctuations decrease near the wall and are enhanced in the core region. The pipe rotation induces a reduction of the streamwise turbulent heat flux and an obvious augmentation of the azimuthal one, especially near the wall. Thus, heat transfer between fluid and wall is reduced. For higher rotation numbers (N>3), the flow and the scalar transport become nearly insensitive to N. Joint probability density functions sketch the correlation between flow and thermal fields. Visualization of the temperature field exhibits the stabilizing effects of the centrifugal forces.

  2. Simulation and optimization of a pulsating heat pipe using artificial neural network and genetic algorithm

    Science.gov (United States)

    Jokar, Ali; Godarzi, Ali Abbasi; Saber, Mohammad; Shafii, Mohammad Behshad

    2016-01-01

    In this paper, a novel approach has been presented to simulate and optimize the pulsating heat pipes (PHPs). The used pulsating heat pipe setup was designed and constructed for this study. Due to the lack of a general mathematical model for exact analysis of the PHPs, a method has been applied for simulation and optimization using the natural algorithms. In this way, the simulator consists of a kind of multilayer perceptron neural network, which is trained by experimental results obtained from our PHP setup. The results show that the complex behavior of PHPs can be successfully described by the non-linear structure of this simulator. The input variables of the neural network are input heat flux to evaporator (q″), filling ratio (FR) and inclined angle (IA) and its output is thermal resistance of PHP. Finally, based upon the simulation results and considering the heat pipe's operating constraints, the optimum operating point of the system is obtained by using genetic algorithm (GA). The experimental results show that the optimum FR (38.25 %), input heat flux to evaporator (39.93 W) and IA (55°) that obtained from GA are acceptable.

  3. Wind tunnel data of the analysis of heat pipe and wind catcher technology for the built environment

    OpenAIRE

    John Kaiser Calautit; Hassam Nasarullah Chaudhry; Ben Richard Hughes

    2015-01-01

    The data presented in this article were the basis for the study reported in the research articles entitled 'Climate responsive behaviour heat pipe technology for enhanced passive airside cooling' by Chaudhry and Hughes [10] which presents the passive airside cooling capability of heat pipes in response to gradually varying external temperatures and related to the research article "CFD and wind tunnel study of the performance of a uni-directional wind catcher with heat transfer devices" by Cal...

  4. Comparative study of a novel liquid–vapour separator incorporated gravitational loop heat pipe against the conventional gravitational straight and loop heat pipes – Part II: Experimental testing and simulation model validation

    International Nuclear Information System (INIS)

    Highlights: • We constructed a liquid–vapour separator incorporated gravity-assisted loop heat pipe. • We examined the thermal performance of three heat pipes through experiments. • We analysed the axial temperature profile and start-up process of three heat pipes. • We validated the computer simulation model reported in previous research. • The new loop heat pipe could significantly enhance heat transfer effect in practice. - Abstract: Aim of the paper is to report the experimental study of a novel liquid–vapour separator incorporated gravity-assisted loop heat pipe (GALHP) (T1), against the conventional GALHP (T2) and a gravitational straight heat pipe (T3). Based on the results derived from the theoretical analyses and computer modelling, three prototype heat pipes, one for each type, were designed, constructed and tested to characterise their thermal performance under a series of operational conditions. By using the experimental data, the computer simulation model reported in the authors’ previous paper was examined and analysed, indicating that the model could achieve a reasonable accuracy in predicting the thermal performance of the three heat pipes. Under the specifically defined testing condition, T1 has more evenly distributed axial temperature profile than the other two heat pipes (T2 and T3). The start-up timings for T1, T2 and T3 were 410 s, 1400 s and 390 s respectively, indicating that the heat transfer within T2 was affected by the larger evaporator dry-out surface area and restricted evaporation area. The overall thermal resistance of T1 was 0.11 °C/W, which was around 20% and 50% that of T2 and T3. The tested effective thermal conductivity in T1 was 29,968 W/°C m, which was 296% and 648% that of T2 and T3, and 7492% that of a standard copper rod. It is therefore concluded that the novel heat pipe (T1) could achieve a significantly enhanced heat transport effect, relative to T2, T3 and standard cooper rod. The experimental results

  5. Transport phenomena in capillary-porous structures and heat pipes

    CERN Document Server

    Smirnov, Henry

    2009-01-01

    With emphasis on the processes involved, this text explores the experimental efforts in two-phase thermal control technology research and development. This work evaluates and compares different theoretical approaches, experimental results, and models, such as semi-empirical models for critical boiling heat fluxes.

  6. Experimental study on an innovative multifunction heat pipe type heat recovery two-stage sorption refrigeration system

    International Nuclear Information System (INIS)

    An innovative multifunction heat pipe type sorption refrigeration system is designed, in which a two-stage sorption thermodynamic cycle based on two heat recovery processes was employed to reduce the driving heat source temperature, and the composite sorbent of CaCl2 and activated carbon was used to improve the mass and heat transfer performances. For this test unit, the heating, cooling and heat recovery processes between two reactive beds are performed by multifunction heat pipes. The aim of this paper is to investigate the cycled characteristics of two-stage sorption refrigeration system with heat recovery processes. The two sub-cycles of a two-stage cycle have different sorption platforms though the adsorption and desorption temperatures are equivalent. The experimental results showed that the pressure evolutions of two beds are nearly equivalent during the first stage, and desorption pressure during the second stage is large higher than that in the first stage while the desorption temperatures are same during the two operation stages. In comparison with conventional two-stage cycle, the two-stage cycle with heat recovery processes can reduce the heating load for desorber and cooling load for adsorber, the coefficient of performance (COP) has been improved more than 23% when both cycles have the same regeneration temperature of 103 deg. C and the cooling water temperature of 30 deg. C. The advanced two-stage cycle provides an effective method for application of sorption refrigeration technology under the condition of low-grade temperature heat source or utilization of renewable energy

  7. Possibilities of using carbon dioxide as fillers for heat pipe to obtain low-potential geothermal energy

    Directory of Open Access Journals (Sweden)

    Malcho M.

    2013-04-01

    Full Text Available The use of low-potential heat is now possible especially in systems using heat pumps. There is a presumption that the trend will continue. Therefore, there is a need to find ways to be systems with a heat pump efficiencies. The usage of heat pipes seems to be an appropriate alternative to the establishedtechnology of obtaining heat through in-debt probes. This article describes a series of experiments on simulator for obtaining low-potential geothermal energy, in order to find the optimal amount of carbon dioxide per meter length of the heat pipe. For orientation and understanding of the conclusions of theexperiment, the article has also a detailed description of the device which simulates the transport of heat through geothermal heat pipes.

  8. Experimental Study on the Passive Containment Cooling System of PWR using Multi-Pod Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Gyeong Ho; Kim, Sang Nyung [Kyung Hee Univ., Yongin (Korea, Republic of)

    2013-10-15

    An experimental device, a scale model of MPHP to be applied to the Nuclear power plant was designed to design and produce 7 MPHP with 7 heat pipes in the form of Hexagonal array, and 7kW was injected to identify the temperature and the pressure to calculate Heat transfer coefficient and Quantity of heat. As a result of the experimental study, seeing that the pressure inside the boiling tank decreased steadily, it is judged that MPHP's heat transfer performance shows over 100% efficiency. Also, the air-weight fraction in the Boiling Tank showed about 0.02(ω/ο), Uchida correlation applied Heat transfer coefficient was about 5619(W/m{sup 2}· .deg. C), and Tagami correlation applied Heat transfer coefficient showed about 13333(ω/ο)

  9. Physical concept and calculation of boiling point in a pulsating heat pipe

    Directory of Open Access Journals (Sweden)

    Naumova A. N.

    2014-06-01

    Full Text Available LED development is accompanied by the need to ensure a constructive solution for the thermal conditions problem. For this purpose one can use pulsating heat pipes (PHP, that operate more efficiently after the start of heat carrier boiling. This article describes the physical representation and formula that allows determining the boiling point, which is a lower bound of the PHP effective operating range. It is shown that the main factors influencing the required heat flow are driving capillary pressure and velocity of the vapor bubble. The formula was obtained for the closed PHP made of the copper with water as a heat carrier. Information about this heat flux can be used for further design of cooling systems for heat-sensitive elements, such as LED for promising lighting devices.

  10. Evaluating Heat Pipe Performance in 1/6 g Acceleration: Problems and Prospects

    Science.gov (United States)

    Jaworske, Donald A.; McCollum, Timothy A.; Gibson, Marc A.; Sanzi, James L.; Sechkar, Edward A.

    2011-01-01

    Heat pipes composed of titanium and water are being considered for use in the heat rejection system of a fission power system option for lunar exploration. Placed vertically on the lunar surface, the heat pipes would operate as thermosyphons in the 1/6 g environment. The design of thermosyphons for such an application is determined, in part, by the flooding limit. Flooding is composed of two components, the thickness of the fluid film on the walls of the thermosyphon and the interaction of the fluid flow with the concurrent vapor counter flow. Both the fluid thickness contribution and interfacial shear contribution are inversely proportional to gravity. Hence, evaluating the performance of a thermosyphon in a 1 g environment on Earth may inadvertently lead to overestimating the performance of the same thermosyphon as experienced in the 1/6 g environment on the moon. Several concepts of varying complexity have been proposed for evaluating thermosyphon performance in reduced gravity, ranging from tilting the thermosyphons on Earth based on a cosine function, to flying heat pipes on a low-g aircraft. This paper summarizes the problems and prospects for evaluating thermosyphon performance in 1/6 g.

  11. Micro-Textured Black Silicon Wick for Silicon Heat Pipe Array

    Science.gov (United States)

    Yee, Karl Y.; Sunada, Eric T.; Ganapathi, Gani B.; Manohara, Harish; Homyk, Andrew; Prina, Mauro

    2013-01-01

    Planar, semiconductor heat arrays have been previously proposed and developed; however, this design makes use of a novel, microscale black silicon wick structure that provides increased capillary pumping pressure of the internal working fluid, resulting in increased effective thermal conductivity of the device, and also enables operation of the device in any orientation with respect to the gravity vector. In a heat pipe, the efficiency of thermal transfer from the case to the working fluid is directly proportional to the surface area of the wick in contact with the fluid. Also, the primary failure mechanism for heat pipes operating within the temperature range of interest is inadequate capillary pressure for the return of fluid from the condenser to the wick. This is also what makes the operation of heat pipes orientation-sensitive. Thus, the two primary requirements for a good wick design are a large surface area and high capillary pressure. Surface area can be maximized through nanomachined surface roughening. Capillary pressure is largely driven by the working fluid and wick structure. The proposed nanostructure wick has characteristic dimensions on the order of tens of microns, which promotes menisci of very small radii. This results in the possibility of enormous pumping potential due to the inverse proportionality with radius. Wetting, which also enhances capillary pumping, can be maximized through growth of an oxide layer or material deposition (e.g. TiO2) to create a superhydrophilic surface.

  12. Heat transfer and pressure drop characteristics of molten fluoride salt in circular pipe

    International Nuclear Information System (INIS)

    FLiNaK salt, eutectic mixture of fluorides of lithium, sodium and potassium, is a potential candidate coolant for high temperature reactors (HTRs). In this paper, a CFD analysis has been performed to study the heat transfer and pressure drop characteristics of FLiNaK salt flowing in a circular pipe for various regimes of flow. Simulation is performed with the help of in-house developed CFD code, NAFA. The calculated local Nusselt number (Nu) and friction factor along the pipe have been compared with the available correlations. The dependence of Nusselt number on Reynolds number (Re) has also been predicted and compared. Pressure drop along the pipe has been compared with various correlations. This study shows that the considered correlations for heat transfer and pressure drop are suitable to predict the heat transfer and pressure drop behavior of FLiNaK salt. -- Highlights: • Thermal-hydraulic study of FLiNaK salt has been performed using CFD code. • Laminar and turbulent regimes of the flow have been analyzed. • Analysis has been performed for various Reynolds number. • Results were compared with the correlations of heat transfer and pressure drop

  13. A heat-pipe mechanism for volcanism and tectonics on Venus

    Science.gov (United States)

    Turcotte, D. L.

    1989-01-01

    A heat-pipe mechanism is proposed for the transport of heat through the lithosphere of Venus. This mechanism allows the crust and lithosphere on Venus to be greater than 150 km thick. A thick basaltic crust on Venus is expected to transform eclogite at a depth of 60 to 80 km; the dense eclogite would contribute to lithospheric delamination that returns the crust to the interior of the planet completing the heat-pipe cycle. Topography and the associated gravity anomalies can be explained by Airy compensation of the thick crust. The principal observation that is contrary to this hypothesis is the mean age of the surface that is inferred from crater statistics; the minimum mean age is about 130 Myr and this implies an upper limit of 2 cubic kilometers per year for the surface volcanic flux. If the heat-pipe mechanism was applicable on the earth in the Archean it would provide the thick lithosphere implied by isotopic data from diamonds.

  14. Annual analysis of heat pipe PV/T systems for domestic hot water and electricity production

    International Nuclear Information System (INIS)

    Highlights: ► A novel heat pipe photovoltaic/thermal system with freeze protection was proposed. ► A detailed annual simulation model for the HP-PV/T system was presented. ► Annual performance of HP-PV/T was predicted and analyzed under different condition. - Abstract: Heat-pipe photovoltaic/thermal (HP-PV/T) systems can simultaneously provide electrical and thermal energy. Compared with traditional water-type photovoltaic/thermal systems, HP-PV/T systems can be used in cold regions without being frozen with the aid of a carefully selected heat-pipe working fluid. The current research presents a detailed simulation model of the HP-PV/T system. Using this model, the annual electrical and thermal behavior of the HP-PV/T system used in three typical climate areas of China, namely, Hong Kong, Lhasa, and Beijing, are predicted and analyzed. Two HP-PV/T systems, with and without auxiliary heating equipment, are studied annually under four different kinds of hot-water load per unit collecting area (64.5, 77.4, 90.3, and 103.2 kg/m2).

  15. Two-Phase Flow Modeling in a Single Closed Loop Pulsating Heat Pipes

    Institute of Scientific and Technical Information of China (English)

    YANG Hong-hai; Sameer Khandekar; Sanka V. V. S. N. S. Manyam; Manfred Groll

    2007-01-01

    Mathematical modeling of pulsating heat pipes through 'first’ principles is a contemporary problem which remains quite elusive. Simplifications and assumptions made in all the modeling approaches developed so far render them unsuitable for engineering design. In this paper, a more realistic modeling scheme is presented which provides considerable try for thought toward the next progressive step. At high enough heat flux level, closed loop pulsating heat pipes experience a bulk internal unidirectional fluid circulation. Under such a condition, conventional two-phaseflow modeling in capillary tubes may be applied. This has been attempted for single-loop PHPs. A homogeneous model and a separated two-fluid flow model based on simultaneous conservation of mass, momentum and energy, have been developed for an equivalent 'open flow' system. The model allows prediction of two-phase flow parameters in each subsection of the device thereby providing important insights into its operation. The concept of 'void fraction constraint'in pulsating heat pipe operation is introduced and its relevance to future modeling attempts is outlined.

  16. Inductively Heated Incompressible Flow of Electrically Conductive Liquid in Pipe

    Czech Academy of Sciences Publication Activity Database

    Doležel, Ivo; Dubcová, Lenka; Karban, P.; Červený, Jakub; Šolín, Pavel

    Florianopolis: International Compumag Society, 2009, s. 1-4. ISBN N. [COMPUMAG 2009 /17./. Florianopolis (BR), 22.11.2009-26.11.2009] R&D Projects: GA ČR(CZ) GA102/07/0496; GA AV ČR IAA100760702 Institutional research plan: CEZ:AV0Z20570509 Keywords : incompressible flow * induction heating * electromagnetic field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.compumag2009.com

  17. Performance Evaluation of the Concept of Hybrid Heat Pipe as Passive In-core Cooling Systems for Advanced Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yeong Shin; Kim, Kyung Mo; Kim, In Guk; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    As an arising issue for inherent safety of nuclear power plant, the concept of hybrid heat pipe as passive in-core cooling systems was introduced. Hybrid heat pipe has unique features that it is inserted in core directly to remove decay heat from nuclear fuel without any changes of structures of existing facilities of nuclear power plant, substituting conventional control rod. Hybrid heat pipe consists of metal cladding, working fluid, wick structure, and neutron absorber. Same with working principle of the heat pipe, heat is transported by phase change of working fluid inside metal cask. Figure 1 shows the systematic design of the hybrid heat pipe cooling system. In this study, the concept of a hybrid heat pipe was introduced as a Passive IN-core Cooling Systems (PINCs) and demonstrated for internal design features of heat pipe containing neutron absorber. Using a commercial CFD code, single hybrid heat pipe model was analyzed to evaluate thermal performance in designated operating condition. Also, 1-dimensional reactor transient analysis was done by calculating temperature change of the coolant inside reactor pressure vessel using MATLAB. As a passive decay heat removal device, hybrid heat pipe was suggested with a concept of combination of heat pipe and control rod. Hybrid heat pipe has distinct feature that it can be a unique solution to cool the reactor when depressurization process is impossible so that refueling water cannot be injected into RPV by conventional ECCS. It contains neutron absorber material inside heat pipe, so it can stop the reactor and at the same time, remove decay heat in core. For evaluating the concept of hybrid heat pipe, its thermal performance was analyzed using CFD and one-dimensional transient analysis. From single hybrid heat pipe simulation, the hybrid heat pipe can transport heat from the core inside to outside about 18.20 kW, and total thermal resistance of hybrid heat pipe is 0.015 .deg. C/W. Due to unique features of long heat

  18. Performance Evaluation of the Concept of Hybrid Heat Pipe as Passive In-core Cooling Systems for Advanced Nuclear Power Plant

    International Nuclear Information System (INIS)

    As an arising issue for inherent safety of nuclear power plant, the concept of hybrid heat pipe as passive in-core cooling systems was introduced. Hybrid heat pipe has unique features that it is inserted in core directly to remove decay heat from nuclear fuel without any changes of structures of existing facilities of nuclear power plant, substituting conventional control rod. Hybrid heat pipe consists of metal cladding, working fluid, wick structure, and neutron absorber. Same with working principle of the heat pipe, heat is transported by phase change of working fluid inside metal cask. Figure 1 shows the systematic design of the hybrid heat pipe cooling system. In this study, the concept of a hybrid heat pipe was introduced as a Passive IN-core Cooling Systems (PINCs) and demonstrated for internal design features of heat pipe containing neutron absorber. Using a commercial CFD code, single hybrid heat pipe model was analyzed to evaluate thermal performance in designated operating condition. Also, 1-dimensional reactor transient analysis was done by calculating temperature change of the coolant inside reactor pressure vessel using MATLAB. As a passive decay heat removal device, hybrid heat pipe was suggested with a concept of combination of heat pipe and control rod. Hybrid heat pipe has distinct feature that it can be a unique solution to cool the reactor when depressurization process is impossible so that refueling water cannot be injected into RPV by conventional ECCS. It contains neutron absorber material inside heat pipe, so it can stop the reactor and at the same time, remove decay heat in core. For evaluating the concept of hybrid heat pipe, its thermal performance was analyzed using CFD and one-dimensional transient analysis. From single hybrid heat pipe simulation, the hybrid heat pipe can transport heat from the core inside to outside about 18.20 kW, and total thermal resistance of hybrid heat pipe is 0.015 .deg. C/W. Due to unique features of long heat

  19. Modeling Transient Heat Transfer in Small-Size Twin Pipes for End-User Connections to Low-Energy District Heating Networks

    DEFF Research Database (Denmark)

    Dalla Rosa, Alessandro; Li, Hongwei; Svendsen, Svend

    2013-01-01

    of district heating branch pipes in low-temperature operation (supply temperature 50-55°C and return temperature 20-25°C). We looked at state-of-the-art district heating branch pipes, suitable for the connection of a typical single-family house to a substation equipped with a heat exchanger for domestic hot...... water preparation. Experimental measurements of the supply temperature profiles at the outlet of the pipe, i.e. at the inlet to the substation, were compared with detailed simulations based on the finite volume (FV) method. A programming code was developed to model these profiles, and this was validated...

  20. Testing corrosion rates on steel piping in geothermal district heating

    OpenAIRE

    İnce, Umut; Toksoy, Macit; Güden, Mustafa

    2008-01-01

    The corrosion behavior of St-37 pipeline carbon steel (CS) in a geothermal district heating system was tested at two different fluid velocities. An experimental set-up, directly connected the the end of the transmission line of a geothermal well, was used to assess the corrosion of St-37 steel tensile test coupons prepared in accordance with ASTM E8 in geothermal fluid. The geothermal fluid entered the set-up with a relatively low velocity, 0.02 m/s, and then injected into the well with a rel...

  1. Analytical and Numerical Solutions of Vapor Flow in a Flat Plate Heat Pipe

    Directory of Open Access Journals (Sweden)

    Mohsen GOODARZI

    2012-03-01

    Full Text Available In this paper, the optimal homotopy analysis method (OHAM and differential transform method (DTM were applied to solve the problem of 2D vapor flow in flat plate heat pipes. The governing partial differential equations for this problem were reduced to a non-linear ordinary differential equation, and then non-dimensional velocity profiles and axial pressure distributions along the entire length of the heat pipe were obtained using homotopy analysis, differential transform, and numerical fourth-order Runge-Kutta methods. The reliability of the two analytical methods was examined by comparing the analytical results with numerical ones. A brief discussion about the advantages of the two applied analytical methods relative to each other is presented. Furthermore, the effects of the Reynolds number and the ratio of condenser to evaporator lengths on the flow variables were discussed.Graphical abstract

  2. Mathematical modeling and analysis of heat pipe start-up from the frozen state

    International Nuclear Information System (INIS)

    The start-up process of a frozen heat pipe is described and a complete mathematical model for the start-up of the frozen heat pipe is developed based on the existing experimental data, which is simplified and solved numerically. The two-dimensional transient model for the wall and wick is coupled with the one-dimensional transient model for the vapor flow when vaporization and condensation occur at the interface. A parametric study is performed to examine the effect of the boundary specification at the surface of the outer wall on the successful start-up from the frozen state. For successful start-up, the boundary specification at the outer wall surface must melt the working substance in the condenser before dry-out takes place in the evaporator

  3. Determination of external measurements in aim to solve inverse heat conduction problem in piping

    International Nuclear Information System (INIS)

    The inverse heat conduction problem (IHCP) to be solved involves with the reconstruction of unknown thermal loadings applied on piping internal wall. Only external temperature measurements are available as data. Different approaches can be found in the literature for solving this ill-posed problem. The most frequently used among them is the function specification method proposed by Professor BECK. However, for multidimensional IHCP, the accuracy of the solution strongly depends on the number of sensors and their location. This work focuses on the determination of minimal number and locations of the external thermocouples to get the most complete estimation of internal heat flux in a straight pipe. It more particularly concerns the preparation of experimental validation tests which will be performed on the ESTHER mock-up of Electricite de France (EDF). (authors). 4 refs., 9 figs

  4. Design of Heat Pipe Type Adsorption Ice Maker for Fishing Boats

    Institute of Scientific and Technical Information of China (English)

    王丽伟; 王如竹; 夏再忠; 吴静怡

    2005-01-01

    A heat pipe type adsorption ice maker with two adsorbers for fishing boats is designed by using ammonia as refrigerant and compound of activated carbon-GaG12 as adsorbent. This type of heat pipe adsorber can solve the problem of incompatibility between ammonia, copper, seawater and steel. The working process of the ice maker with 8.7kg adsorbent per bed is simulated. The results show that the optimal semi-cycle time is about 9min at the evaporating temperature of -15℃, where the corresponding cooling power, specific cooling power per kilogram adsorbent SCP and coefficient of refrigerant performance COP are respectively 3.6 kW, 217 W·kg-1 and 0.404.

  5. Mathematical modeling and analysis of heat pipe start-up from the frozen state

    Science.gov (United States)

    Jang, J. H.; Faghri, A.; Chang, W. S.; Mahefkey, E. T.

    1990-01-01

    The start-up process of a frozen heat pipe is described and a complete mathematical model for the start-up of the frozen heat pipe is developed based on the existing experimental data, which is simplified and solved numerically. The two-dimensional transient model for the wall and wick is coupled with the one-dimensional transient model for the vapor flow when vaporization and condensation occur at the interface. A parametric study is performed to examine the effect of the boundary specification at the surface of the outer wall on the successful start-up from the frozen state. For successful start-up, the boundary specification at the outer wall surface must melt the working substance in the condenser before dry-out takes place in the evaporator.

  6. Life Test Results for Water Heat Pipes Operating at 200 °C to 300 °C

    Science.gov (United States)

    Rosenfeld, John H.; Gernert, Nelson J.

    2008-01-01

    For lunar or planetary bases to be viable, a robust electric generating system will be required for powering the habitat. Water heat pipes offer an attractive solution for lunar base heat rejection, and would serve as a qualification for them on other long duration missions. Successful operation near the upper end of water operating range is a requirement for the application. Results are reported for life tests on water heat pipes that were operated at various temperatures between 200 °C and 300 °C. Tests were conducted on twenty three gravity-assisted water heat pipes. Eleven titanium/water heat pipes and ten Monel/water heat pipes were tested at temperatures above 200 °C. Two cupronickel heat pipes were also assembled and tested. Titanium alloys tested included CP-2 titanium, as well as two beta-titanium alloys, namely 15-3 and Nitinol alloys. Some of the titanium alloy life tests used wicks fabricated from CP-2 titanium screen or porous felt. Monel alloys tested included 400 and K-500 alloys. Some of the Monel heat pipes contained copper/nickel wicks that were fabricated by brazing nickel-plated copper felt metal wicks. Although most of the envelope/material combinations exhibit favorable results at 200 °C, some of the combinations failed at higher temperatures. Causes of failure included stress-creep of envelopes and corrosion at axial or end cap welds. This information represents a significant advance in selection of materials for 200 °C to 300 °C water heat pipes. Life testing work is being continued.

  7. Analysis on Gravitational Effect o Nonlinear Diffusion System of Vapor Molecules in A Heat Pipe

    OpenAIRE

    ETORI, Kanji

    1986-01-01

    A nonlinear diffusion equation with a diffusion coefficient depending on number density of diffusing particles affected by gravity is approximately solved in a steady state. Characteristic properties of vapor molecules in a heat pipe are analyzed as diffusion process of Brownian particles. In order to explain the nonlinear shifts from a linear diffusion system in conventional theories, the expectation values and the variance of number density of vapor molecules are calculated by using the the...

  8. Heat pipes et two-phase loops for spacecraft applications. ESA programmes

    Energy Technology Data Exchange (ETDEWEB)

    Supper, W. [European Space Agency / ESTEC. Thermal control and life support division (France)

    1996-12-31

    This document is a series of transparencies presenting the current and future applications of heat pipes in spacecraft and the activities in the field of capillary pumped two-phase loops: thermal tests, high-efficiency low pressure drop condensers, theoretical understanding of evaporator function, optimization of liquid and vapor flows, trade-off between low and high conductivity wicks, development of high capillary capacity wicks etc.. (J.S.)

  9. Innovative Porous Media Approach in Modeling Biofilm Applications, Human Eye and Nanofluid Based Heat Pipes

    OpenAIRE

    Shafahi, Maryam

    2010-01-01

    Biofilm is a dominant form of existence for bacteria in most natural and synthetic environments. Depending on the application area, they can be useful or harmful. They have a helpful influence in bioremediation, microbial enhanced oil recovery, and metal extraction. On the other hand, biofilms are damaging for water pipes, heat exchangers, submarines and body organs. Formation of biofilm within a porous matrix reduces the pore size and total empty space of the system, altering the porosity an...

  10. Device for storage of radioactive material in a building with heat pipes set in the building wall

    International Nuclear Information System (INIS)

    When storing radio-active material in a building, safe and sufficient heat removal must always be guaranteed. On the other hand, the building should be safely closed to the environment. The invention makes it possible to ensure, for such a building with heat pipes set in the building wall, that it is possible to use at least part of the heat generated in the building without limiting the removal of heat. Cooling sleeves are fitted to the heat pipes near the building wall for this purpose, where a cooling circuit with a circulating coolant is connected to the cooling sleeves. (orig.)

  11. Cost-effective solar collectors using heat pipes. Interim progress report No. 1, September 1977-March 1978

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, D.M.

    1978-01-01

    The objective is the demonstration of high performance, cost effective non-concentrating solar collectors using heat pipes. The end products will be directly applicable for efficient use with absorption and Rankine cycle chillers. Evacuated tubular solar collectors were selected as the only economical non-concentrating approach capable of efficient operation of chillers. The General Electric TC family of collectors was chosen because of their superior performance and compatibility with heat pipe integration. The system was designed and specified. This work included the integration of the heat pipe with the evacuated tubular solar collector and the pumped loop heat removal mechanism. To date, two heat pipe fluid-envelope combinations look attractive: water-aluminum bearing steel and ethanol-low carbon steel. The jury is still out on the ability for the water-aluminum bearing steel to survive freezing cycles and for ethanol-low carbon steel to withstand predicted 400/sup 0/C stagnation temperatures. Full scale cost analysis was not completed for either case. Two 4' x 4' panels, each with ten tubular collectors fitted with heat pipes, were erected at Thermacore to test various aspects of the heat pipe and its integration into the collector-pumped loop system.

  12. Experimental Investigation of Micro Heat Pipes of Different Cross-Sections Having Same Hydraulic Diameter

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Effects of micro heat pipe (MHP) cross-sections and orientations on its thermal perforrnance are experimentally investigated in this study. Tests are conducted using five different cross-sections (circular, semicircular, elliptical,semi-elliptical and rectangular) of micro heat pipes having same hydraulic diameter of 3 mm placed at three different inclination angles (0°, 45°, 90°), where water is used as the working fluid. Evaporator section of the MHP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the MHP are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the MHP is flattened.Thus among all cross-sections of MHP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. Moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within +7%.

  13. HEAT TRANSFER ENHANCEMENT USING LOW VOLUME CONCENTRATIONS OF Fe3O4 NANOFLUID IN CIRCULAR PIPE

    Directory of Open Access Journals (Sweden)

    BHRAMARA PANITAPU

    2014-10-01

    Full Text Available Nanofluids are emerging as one of the effective means of enhancing the heat transfer compared to the conventional heat transfer fluids due enhancement of thermophysical properties of base fluids due to addition of nanosized particles. Numerical experiments were conducted for heat transfer inside a circular pipe subjected to constant heat flux with water as base fluid. Heat transfer enhancement was studied by adding low volume concentrations, viz., 0.1 to 0.6 % of Fe3O4 magnetic nanoparticles of particle size 36 nm in water. The numerical analysis of nanofluid was performed using the single phase approach for the Reynold Number of the flow ranging from 2500 – 22000. The results show that better enhancement was observed at higher Re and at higher volume fractions. The numerical results were compared with the experimental data available in the literature.

  14. Measurement of Coolant in a Flat Heat Pipe Using Neutron Radiography

    Science.gov (United States)

    Mizuta, Kei; Saito, Yasushi; Goshima, Takashi; Tsutsui, Toshio

    A newly developed flat heat pipe FGHPTM (Morex Kiire Co.) was experimentally investigated by using neutron radiography. The test sample of the FGHP heat spreader was 65 × 65 × 2 mm3 composed of several etched copper plates and pure water was used as the coolant. Neutron radiography was performed at the E-2 port of the Kyoto University Research Reactor (KUR). The coolant distributions in the wick area of the FGHP and its heat transfer characteristics were measured at heating conditions. Experimental results show that the coolant distributions depend slightly on its installation posture and that the liquid thickness in the wick region remains constant with increasing heat input to the FGHP. In addition, it is found that the wick surface does not dry out even in the vertical posture at present experimental conditions.

  15. Design of heat pipe heat exchanger used in communication base station%通信基站用热管换热器的设计

    Institute of Scientific and Technical Information of China (English)

    鲍玲玲; 王景刚; 王晓明

    2011-01-01

    热管及热管换热器凭借着其优良的传热特性得到了日益广泛的应用.分析了通信基站用重力热管换热器的工作原理及特点,结合通信基站实例,利用VB语言编写了重力热管换热器的计算程序,设计了一款结构和性能较合理的重力热管换热器.%Heat pipe and heat pipe heat exchanger have good heat transfer characteristics,therefore they obtain increasing application. Analyses the characteristics and working principle of the heat pipe heat exchanger used in communication base station,with a communication base station example,and based on VB compiling language,makes the calculation program for gravitation heat pipe heat exchanger and designs a gravitation heat pipe heat exchanger with adequate structure and performance.

  16. Passive Micro Power Generation for Nuclear Safety with Thermoelectric Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei Sheng; Lee, Jae Young [Handong Global Univ., Pohang (Korea, Republic of); Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2013-10-15

    Operators need to decide to take the SAMG when the plant exceeds the conditions to be managed by the emergency operation program (EOP). However, there is a few tools are available in case of severe accident under the loss of electricity. Sometimes, we cannot estimate the condition of the system due to loss of signals from sensors. Therefore, we need to provide micro power generator working under the accident. The micro power generators are capable of utilizing the energy released by accident. The thermal energy carried by the steam or hot water from the residual heat of core need to be converted into electricity. However, the high entropy of the thermal energy prevents us from employing proper power generators. The well-known organic Rankine cycle for the low temperature waste heat recovery is not useful because of its large volume taking and complexity and need of active engagement for startup. The micropower generator for the SAMG should be highly passive as the other safety systems. In line with this passive requirement, the heat pipe which use the natural capillary pumping power and the thermoelectricity generating electricity whenever temperature difference are providing are most promising candidates. They are auto starting when they are exposed into the hot medium and cold heat sink. Also, they have no duty in the normal condition of power plant because there is no hot source for these passive systems. Furthermore, because of the location flexibility of the heat pipe, when we combine the heat pipe and thermoelectricity generator, we can invent so many tools for SAMG including active hydrogen burning system etc.

  17. AN INVESTMENT SUPPORT STRATEGY FOR HEAT SUPPLY, WATER-SUPPLY AND OVERFLOW-PIPE ENTERPRISES IN UKRAINE

    OpenAIRE

    L. Blinova

    2013-01-01

    The investment necessities of heat-supply, water-supply and overflow-pipe enterprises are considered in the article. Priority measures for the search of financial sources to satisfy the investment necessities are determined. The most prior and effective financial sources for satisfaction of investment necessities of heat-supply, water-supply and overflow-pipe enterprises are analyzed. The analysis shows that the creation of regional investment funds of functioning and development of housing a...

  18. Analysing and evaluating a thermal management solution via heat pipes for lithium-ion batteries in electric vehicles

    OpenAIRE

    Wang, Qian

    2015-01-01

    Thermal management is crucial in many engineering applications because it affects the electrical, material, and other properties of the system. A recent study focuses on the use of heat pipes for battery thermal management in electric vehicles, which explores a new area for heat pipe applications. The battery, as one and only energy source in an EV, establishes a vital barrier for automotive industry because it can make the car more expensive and less reliable. The modelling methodology ...

  19. The overall heat transfer characteristics of a double pipe heat exchanger: comparison of experimental data with predictions of standard correlations

    International Nuclear Information System (INIS)

    The single-phase flow and thermal performance of a double pipe heat exchanger are examined by experimental methods. The working fluid is water at atmospheric pressure. Temperature measurements at the inlet and outlet of the two streams and also at an intermediate point half way between the inlet and outlet is made, using copper-constantan thermocouple wires. Mass flow rates for each stream are also measured using calibrated ratemeters. Heat is supplied to the inner tube stream by an immersion heater. The overall heat transfer coefficients are inferred from the measured data. The heat transfer coefficient of the inner tube flow (circular cross section) is calculated using the standard correlations. The heat transfer coefficient of the outer tube flow (annular cross section) is then deduced.Higher heat transfer coefficients are reported in the laminar flow regime in comparison to the predictions of standard correlations for straight and smooth tubes. The reasons for this discrepancy are identified and discussed. Experimental errors in measuring temperatures and mass flow rates are studied and their effects on the heat transfer coefficients are estimated. Experimental results for the range of operating conditions used in this work show that the outer tube side heat transfer coefficients are smaller than the inner side heat transfer coefficients by a factor of almost 1.5 and 3.4 in counter flow and parallel flow arrangements, respectively. The agreement with predictions is very good for the counter flow arrangement, but not very good for the parallel flow arrangement

  20. Experimental study on start-up characteristics of loop heat pipes

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Hongxing; LIN; Guiping; DING; Ting; SHAO; Xingguo

    2005-01-01

    This paper presents results of ground-experimental study on the start-up characteristics of a Loop Heat Pipe. The physical process of start-up is described, and the explanation that "Pressure Transfer" leads to the saturated temperature rise in compensation chamber during start-up is first discussed. Start-up behaviors as a function of various parameters including vapor/liquid distribution in the evaporator, adverse elevation, start-up heat load, sink temperature are described and explained. A peculiar start-up phenomenon composed of two start-up scenarios was first observed at adverse elevations and is described.

  1. Sensitivity studies of heat transfer: forced convection across a cylindrical pipe and duct flow

    CERN Document Server

    Ferrantelli, Andrea; Viljanen, Martti

    2013-01-01

    We consider two common heat transfer processes and perform a through sensitivity study of the variables involved. We derive and discuss analytical formulas for the heat transfer coefficient in function of film velocity, air temperature and pipe diameter. The according plots relate to a qualitative analysis of the multi-variable function $h$, according to functional optimization. For each process, we provide with graphs and tables of the parameters of interest, such as the Reynolds number. This method of study and the specific values can constitute a useful reference for didactic purposes.

  2. Modeling of Transient Response of the Wickless Heat Pipes

    International Nuclear Information System (INIS)

    Thermosyphons transient response for startup from ambient temperature to steady state until shutdown conditions, is considered a stringent necessity for applications such as electronic, solar, geothermal and even nuclear reactors safety systems. This typically returns to the need to keep the temperature within certain limits before reaching critical conditions. A simple network model is derived for describing the transient response of closed two-phase thermosyphon (CTPT) at startup and shutdown states. In addition, for predicting the effect of operational characteristics of water/copper closed two-phase thermosyphon such as thermal load, filling ratio, evaporator length, and thermosyphon tube diameter. The thermosyphons operation was considered a thermal network of various components with different thermal resistances and dynamic responses. The network model consists of six sub-models. These models are pure conduction in walls of evaporator, adiabatic and condenser, and convection in evaporator pool, evaporator film, and condenser film. So, an energy balance for each sub-model was done to estimate temperatures, heat transfer coefficients, thermal resistances, time constant, and other thermal characteristics that describe the required transient response of the closed two-phase thermosyphon. Governing equations of the transient thermosyphon behavior can be simplified into a set of first-order linear ordinary differential equations. The Runge-Kutta method can be used to obtain transient thermosyphon temperatures from these equations.

  3. A lead-before-break strategy for primary heat transport piping of 500 MWe Indian PHWR

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, J.; Dutta, B.K.; Kushwaha, H.S. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    Leak-Before-Break (LBB) is being used to design the primary heat transport piping system of 500 MWe Indian Pressurized Heavy Water Reactors (IPHWR). The work is categorized in three directions to demonstrate three levels of safety against sudden catastrophic break. Level 1 is inherent in the design procedure of piping system as per ASME Sec.III with a well defined factor of safety. Level 2 consists of fatigue crack growth study of a postulated part-through flaw at the inside surface of pipes. Level 3 is stability analysis of a postulated leakage size flaw under the maximum credible loading condition. Developmental work related to demonstration of level 2 and level 3 confidence is described in this paper. In a case study on fatigue crack growth on PHT straight pipes for level 2, negligible crack growth is predicted for the life of the reactor. For level 3 analysis, the R6 method has been adopted. A database to evaluate SIF of elbows with throughwall flaws under combined internal pressure and bending moment has been generated to provide one of the inputs for R6 method. The methodology of safety assessment of elbow using R6 method has been demonstrated for a typical pump discharge elbow. In this analysis, limit load of the cracked elbow has been determined by carrying out elasto-plastic finite element analysis. The limit load results compared well with those given by Miller. However, it requires further study to give a general form of limit load solution. On the experimental front, a set of small diameter pipe fracture experiments have been carried out at room temperature and 300{degrees}C. Two important observations of the experiments are - appreciable drop in maximum load at 300{degrees}C in case of SS pipes and out-of-plane crack growth in case of CS pipes. Experimental load deflection curves are finally compared with five J-estimation schemes predictions. A material database of PHT piping materials is also being generated for use in LBB analysis.

  4. A lead-before-break strategy for primary heat transport piping of 500 MWe Indian PHWR

    International Nuclear Information System (INIS)

    Leak-Before-Break (LBB) is being used to design the primary heat transport piping system of 500 MWe Indian Pressurized Heavy Water Reactors (IPHWR). The work is categorized in three directions to demonstrate three levels of safety against sudden catastrophic break. Level 1 is inherent in the design procedure of piping system as per ASME Sec.III with a well defined factor of safety. Level 2 consists of fatigue crack growth study of a postulated part-through flaw at the inside surface of pipes. Level 3 is stability analysis of a postulated leakage size flaw under the maximum credible loading condition. Developmental work related to demonstration of level 2 and level 3 confidence is described in this paper. In a case study on fatigue crack growth on PHT straight pipes for level 2, negligible crack growth is predicted for the life of the reactor. For level 3 analysis, the R6 method has been adopted. A database to evaluate SIF of elbows with throughwall flaws under combined internal pressure and bending moment has been generated to provide one of the inputs for R6 method. The methodology of safety assessment of elbow using R6 method has been demonstrated for a typical pump discharge elbow. In this analysis, limit load of the cracked elbow has been determined by carrying out elasto-plastic finite element analysis. The limit load results compared well with those given by Miller. However, it requires further study to give a general form of limit load solution. On the experimental front, a set of small diameter pipe fracture experiments have been carried out at room temperature and 300 degrees C. Two important observations of the experiments are - appreciable drop in maximum load at 300 degrees C in case of SS pipes and out-of-plane crack growth in case of CS pipes. Experimental load deflection curves are finally compared with five J-estimation schemes predictions. A material database of PHT piping materials is also being generated for use in LBB analysis

  5. Theoretical analysis of screened heat pipes for medium and high temperature solar applications

    International Nuclear Information System (INIS)

    A mathematical model is applied to study the cylindrical heat pipes (HPs) behaviour when it is exposed to higher heat input at the evaporator for solar collector applications. The steady state analytical model includes two-dimensional heat conduction in the wall, the liquid flow in the wick and vapour hydrodynamics, and can be used to evaluate the working limits and to optimize the HP. The results of the analytical model are compared with numerical and experimental results available in literature, with good agreement. The effects of heat transfer coefficient, power input, evaporator length, pipe diameter, wick thickness and effective pore radius on the vapour temperature, maximum pressure drop and maximum heat transfer capability (HTC) of the HP are studied. The analysis shows that wick thickness plays an important role in the enhancement of HTC. Results show that it is possible to improve HTC of a HP by selecting the appropriate wick thickness, effective pore radius, and evaporator length. The parametric investigations are aimed to determine working limits and thermal performance of HP for medium temperature solar collector application

  6. Augmented heat transport of mono sized sphere packed pipe for force free helical reactor

    International Nuclear Information System (INIS)

    The sphere packed pipe (SPP) consists of metal spheres inside a pipe which has been proposed as a heat transfer booster for the high Prandtl (Pr) number fluid. One of the potential applications of SPP is using it at the first wall of Force Free Helical Reactor (FFHR). The first wall of FFHR is expected to be exposed to a high thermal load of about 1 MW/m2, which will be removed by a high temperature molten salt Flibeflow. Flibe,a mixture of LiF and BeF2, has advantages of high heat capacity and reduced magnetohydrodynamic (MHD) pressure drop due to low electric conductivity. In the design of the FFHR blanket a heat transfer coefficient above 20,000 W/m2K is required to remove the high heat flux. This computational fluid dynamics (CFD) analysis aims to evaluate the flow structures and heat transfer characteristics in SPP resorting to ANSYS CFX 12.1.

  7. Theoretical research of helium pulsating heat pipe under steady state conditions

    Science.gov (United States)

    Xu, D.; Liu, H. M.; Li, L. F.; Huang, R. J.; Wang, W.

    2015-12-01

    As a new-type heat pipe, pulsating heat pipe (PHP) has several outstanding features, such as great heat transport ability, strong adjustability, small size and simple construction. PHP is a complex two-phase flow system associated with many physical subjects and parameters, which utilizes the pressure and temperature changes in volume expansion and contraction during phase changes to excite the pulsation motion of liquid plugs and vapor bubbles in the capillary tube between the evaporator and the condenser. At present time, some experimental investigation of helium PHP have been done. However, theoretical research of helium PHP is rare. In this paper, the physical and mathematical models of operating mechanism for helium PHP under steady state are established based on the conservation of mass, momentum, and energy. Several important parameters are correlated and solved, including the liquid filling ratio, flow velocity, heat power, temperature, etc. Based on the results, the operational driving force and flow resistances of helium PHP are analysed, and the flow and heat transfer is further studied.

  8. Fractal Loop Heat Pipe Performance Comparisons of a Soda Lime Glass and Compressed Carbon Foam Wick

    Science.gov (United States)

    Myre, David; Silk, Eric A.

    2014-01-01

    This study compares heat flux performance of a Loop Heat Pipe (LHP) wick structure fabricated from compressed carbon foam with that of a wick structure fabricated from sintered soda lime glass. Each wick was used in an LHP containing a fractal based evaporator. The Fractal Loop Heat Pipe (FLHP) was designed and manufactured by Mikros Manufacturing Inc. The compressed carbon foam wick structure was manufactured by ERG Aerospace Inc., and machined to specifications comparable to that of the initial soda lime glass wick structure. Machining of the compressed foam as well as performance testing was conducted at the United States Naval Academy. Performance testing with the sintered soda lime glass wick structures was conducted at NASA Goddard Space Flight Center. Heat input for both wick structures was supplied via cartridge heaters mounted in a copper block. The copper heater block was placed in contact with the FLHP evaporator which had a circular cross-sectional area of 0.88 cm(sup 2). Twice distilled, deionized water was used as the working fluid in both sets of experiments. Thermal performance data was obtained for three different Condenser/Subcooler temperatures under degassed conditions. Both wicks demonstrated comparable heat flux performance with a maximum of 75 W/cm observed for the soda lime glass wick and 70 W /cm(sup 2) for the compressed carbon foam wick.

  9. A study of circumferentially-heated and block-heated heat pipes. I - Experimental analysis and generalized analytical prediction of capillary limits. II - Three-dimensional numerical modeling as a conjugate problem

    Science.gov (United States)

    Schmalhofer, Joseph; Faghri, Amir

    1993-01-01

    The wall and centerline vapor temperatures and heat output are determined experimentally for a low-temperature copper-water heat pipe under uniform circumferential heating and block heating. The time required to reach a vapor temperature of 60 C from an initial ambient temperature of 21 C is determined for both modes of heating. The experimental capillary limit of the heat pipe is compared to the generalized capillary limits for block-heated pipes over a range of vapor temperatures. A three-dimensional numerical model is then developed for determining the temperature, pressure, and velocity distributions in the entire domain of a circumferentially heated and a block-heated pipe. The problem is formulated as a conjugate problem, without the assumption of a uniform vapor temperature. The predictions of the model are found to be in good agreement with the experimental data.

  10. Pipe Flov with Viscosity Gradient and Frictional Resistance : 1st Report, Flow of a High Viscosity Fluid in a Heated or Cooled Pipe

    OpenAIRE

    Kurokawa, Junichi; Uchida, Toshiyuki; Adachi, Toshiaki; Yamada, Takeshi

    1986-01-01

    The flow of a highly viscous fluid in a pipe, of which the wall is heated or cooled at a constant temperature, is studied theoretically and experimentally in order to determine the frictional resistance of the flow with a viscosity gradient. Measurements are performed for the Reynolds number 20

  11. Elastomere seals/gaskets for gas supply pipes and district heating gas pipes. Einsatz von Dichtungen aus Elastomeren fuer Gasversorgungs- und Gasfernleitungen

    Energy Technology Data Exchange (ETDEWEB)

    1982-06-01

    The leaflet applies to properties, storage, utilisation and installation of elastomere gaskets in gas supply lines and district gas heating pipes, as well as to their components in accordance with DIn 3535 part 3. Gas is transported at temperatures between -5deg C and +50deg C and operating pressures of up to 40 bar. (DG).

  12. Experimental investigation of a pulsating heat pipe for hybrid vehicle applications

    International Nuclear Information System (INIS)

    This paper deals with the experimental results of an unlooped pulsating heat pipe (PHP) developed and tested in an electronic thermal management field with hybrid vehicle applications in mind. The 2.5 mm inner tube diameter device was cooled by an air heat exchanger to replicate the environment of a vehicle. In order to characterize this pulsating heat pipe, four working fluids have been tested. They are acetone, methanol, water, and n-pentane, with applied thermal power ranging from 25 W to 550 W, air temperature ranging from 10 °C to 60 °C and air velocity ranging from 0.25 m s−1 to 2 m s−1. Three inclinations have also been tested according to their horizontal positions: +45° (condenser above the evaporator), 0° and −45° (condenser below the evaporator). Among the different results, some of the most revelatory were obtained with regard to unfavourable inclination (−45°), for which the performances were very interesting considering a terrestrial application. On the other hand, one also observed low temperature limitations for water as a working fluid and degradation of performances for n-pentane tested at 60 °C air temperature. On an overall basis, however, it should be noted that the PHP functioned with high reliability and reproducibility and without any failure during the start-up or working stage. - Highlights: ► An unlooped pulsating heat pipe (PHP) has been tested varying heat power, air velocity and temperature, inclination and fluid. ► Four working fluids have been tested and classified into two groups according to the performances of the PHP. ► Interesting water phenomena have been highlighted in this study. ► The PHP worked with a good reliability and reproducibility.

  13. NUMERICAL SIMULATION OF THERMAL PERFORMANCE AND TEMPERATURE FIELD IN HEAT PIPE HEAT EXCHANGER%热管换热器传热性能及温度场数值模拟

    Institute of Scientific and Technical Information of China (English)

    孙世梅; 张红

    2004-01-01

    Mathematic model for thermal performance of heat pipe heat exchanger based on the heat transfer model was presented. The infinite volume model was used to calculate the overall thermal performance and the temperature field of heat pipe heat exchanger. The calculation results essentially coincided with the results of an engineering case and provided the theoretical base for engineering application.

  14. Modelling the performance of the tapered artery heat pipe design for use in the radiator of the solar dynamic power system of the NASA Space Station

    Science.gov (United States)

    Evans, Austin Lewis

    1988-01-01

    The paper presents a computer program developed to model the steady-state performance of the tapered artery heat pipe for use in the radiator of the solar dynamic power system of the NASA Space Station. The program solves six governing equations to ascertain which one is limiting the maximum heat transfer rate of the heat pipe. The present model appeared to be slightly better than the LTV model in matching the 1-g data for the standard 15-ft test heat pipe.

  15. Building, in particular a warehouse, with up and down moveable heating pipes; Gebouw, in het bijzonder warenhuis, met omhoog en omlaag beweegbare verwarmingsbuizen

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-19

    In a complex of rotating heat pipes in a supporting framework large hoisting forces occur where the hoisting cables are connected to the pipes, which can result in bending or even damaging of the pipes (buckling or fatigue fractures). In a building with up and down movable heating pipes the above-mentioned problems will not take place, mainly by providing extra so-called hoisting force compensation cables. 3 figs.

  16. A Novel Approach for Cooling Electronics Using a Combined Heat Pipe and Thermoelectric Module

    Directory of Open Access Journals (Sweden)

    Banjerd Saengchandr

    2009-01-01

    Full Text Available The development of effective cooling systems for microprocessors, specifically for CPU and other computer chips, is greatly important due to growth of high speed performance chips, which operate at elevated heat rates. The same issues apply for adjacent units including RAM and HDD also contributing to overall generation of heat inside computer. Problem statement: Conventional cooling system for desktop PC has many problems, especially cooling performance. Lifespan of devices and reliable operation are largely dependent on junction temperature. Total power dissipation of recently introduced, new generation microprocessors had been increasing rapidly, pushing desktop system cooling technology close to its limits. Approach: Present research focused on a system for removal of dissipated heat that combined the advantages of heat pipe and thermoelectric modules. Proposed research presented a numerical analysis of a novel cooling system for electronics. Configuration studied concerns microprocessors and other computer ships. Simulations performed in this research were based on use of computational fluid dynamics and results obtained in terms of cooling efficiencies were compared to those of the traditional cooling. Heat resistance and temperature of each component were investigated in this modeling. Results: Lowest core temperature was found below 75°C and total thermal resistance of cooling system is 0.095°C/W. Conclusion/Recommendations: Proposed cooling systems had sufficient capacity for cooling 200 W heat dissipation. Temperature of proposed cooling system is lower than both existing cooling systems. Temperature of all components, CPU, heat pipe, TEC and heat sink were below 75°C. Thermal resistance characteristic of a cooling system had a major effect on cooling performance.

  17. Frozen start-up behavior of low-temperature heat pipes

    Science.gov (United States)

    Faghri, Amir

    1992-01-01

    Start-up and subsequent operation of a low-temperature heat pipe requires the liquid phase of the operating fluid to be continuously pumped back to the evaporator by the capillary action of the wick. If the pipe has been in an environment where ambient temperatures are below the freezing point of the working fluid prior to start-up, the frozen fluid in the condenser and adiabatic region scan prevent initial flow to the evaporator, causing dryout of the evaporator before all of the working fluid is in the liquid phase. This paper examines the time-dependent wall and vapor temperature profiles along the axial length of a low-temperature heat pipe during start-up from the frozen state, and freeze-out during a normal operation by applying a subfreezing temperature fluid through the condenser. In addition, the experimental transient frozen start-up wall temperature profile is compared with a two-dimensional numerical phase-change model. A successful start-up method using a pulsed power input is presented.

  18. Internal flow Patterns of the Horizontal Heat Mode Closed-Loop Oscillating Heat Pipe with Check Valves (HHMCLOHP/CV

    Directory of Open Access Journals (Sweden)

    S. Sangiamsuk

    2013-01-01

    Full Text Available This research was to study the internal flow patterns on heat transfer rates of the Horizontal Heat Mode Closed Loop Oscillating Heat Pipe with Check Valves (HHMCLOHP/CV. The HHMCLOHP/CV was made from a Pyrex glass capillary tube with a 2.4 mm inside diameter. There were 10 meandering turns with 2 check valves. Ethanol and a silver nano-ethanol mixture were used as working fluid. Experimental results found that if working fluid varies from ethanol to a silver nano-ethanol mixture and the evaporator temperature increases the main flow patterns were Slug flow + Annular flow. The main regime of each flow pattern can be determined from the flow pattern map.

  19. A study of high-temperature heat pipes with multiple heat sources and sinks. I - Experimental methodology and frozen startup profiles. II - Analysis of continuum transient and steady-state experimental data with numerical predictions

    Science.gov (United States)

    Faghri, A.; Cao, Y.; Buchko, M.

    1991-01-01

    Experimental profiles for heat pipe startup from the frozen state were obtained, using a high-temperature sodium/stainless steel pipe with multiple heat sources and sinks to investigate the startup behavior of the heat pipe for various heat loads and input locations, with both low and high heat rejection rates at the condensor. The experimental results of the performance characteristics for the continuum transient and steady-state operation of the heat pipe were analyzed, and the performance limits for operation with varying heat fluxes and location are determined.

  20. Development of an ISI Robot for the Fast Breeder Reactor MONJU Primary Heat Transfer System Piping

    International Nuclear Information System (INIS)

    This paper describes the development of a new inspection robot for the In-Service Inspection of the heat transfer system of the Fast Breeder Reactor MONJU. The inspection was carried out using a tire type ultrasonic sensor for volumetric tests at high temperature (atmosphere 55 degree C, Piping Surface 80 degree C) and radiation exposure condition (dose rate 10 mGy/h, piping surface dose rate 15 mGy/h). It was developed an inspection robot using a new tire type for the ultrasonic testing sensor and a new control method. A signal to noise ratio S/N over 2 was obtained during the functional test for a calibration defect with depth 50%t (from the tube wall thickness). (author)