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Sample records for heat pipe energy

  1. 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

  2. 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

    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...... 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....... Finally, the article describes proposals for the optimal design of pipes for low-energy applications and presents methods for decreasing heat losses....

  3. Energy and exergy evaluation of an integrated solar heat pipe wall ...

    Indian Academy of Sciences (India)

    The rate of increasing in temperature of air becomes negligible after 30 heat pipes and the trend of the thermal efficiency is descending with increasing heat pipes. The results also indicate that at a cold winter day of January, the proposed system with a 20 heat pipe collector shows maximum energy and exergy efficiency of ...

  4. 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.

  5. Thermodynamic analysis of alternate energy carriers, hydrogen and chemical heat pipes

    Science.gov (United States)

    Cox, K. E.; Carty, R. H.; Conger, W. L.; Soliman, M. A.; Funk, J. E.

    1976-01-01

    Hydrogen and chemical heat pipes were proposed as methods of transporting energy from a primary energy source (nuclear, solar) to the user. In the chemical heat pipe system, primary energy is transformed into the energy of a reversible chemical reaction; the chemical species are then transmitted or stored until the energy is required. Analysis of thermochemical hydrogen schemes and chemical heat pipe systems on a second law efficiency or available work basis show that hydrogen is superior especially if the end use of the chemical heat pipe is electrical power.

  6. 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

  7. Gas turbine cogeneration: the use of heat pipes to recover exhaust gas energy

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, J. L.; Perella Balestieri, J. A.; Masanobu Tanisho, P.; Araujo Zanardi, M.; Murcia, N. [Paulista State University, Guaratingueta (Brazil)

    1996-12-31

    Heat pipe heat exchangers for the recovery of exhaust gas heat from gas turbines for the simultaneous cogeneration of electricity were described. Technical and economic implications were reviewed. The overall conclusion was that cogeneration systems using heat pipe heat exchanger technology could be a useful alternative in the supply and use of energy, of particular interest for application in industrial, hospital, hotel or other large building system environment. 8 refs., 3 tabs., 5 figs.

  8. 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...... 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....... factors in the optimal design of low-energy DH systems. Various pipe configurations are considered in this paper: flexible pre-insulated twin pipes with symmetrical or asymmetrical insulation, double pipes, and triple pipes. These technologies represent potential energy-efficient and cost...

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

    Energy Technology Data Exchange (ETDEWEB)

    Shirey, D.B. III [Florida Solar Energy Center, Cape Canaveral, FL (United States)

    1995-03-01

    This article describes two methods to reduce energy consumption and peak demand in buildings that require humidity control that were demonstrated at the Salvador Dali Museum in St. Petersburg, Florida. The first method centered on alternative indoor fan cycling strategies and the second method involved the use of heat pipe heat exchangers. Both approaches increased the dehumidification performance of the existing air-conditioning systems and provided substantial savings. Simple, low cost alternative fan cycling strategies were used. When possible, auto fan control replaced constant fan operation to avoid excess fan energy consumption, ventilation load and compressor operation. The alternative fan control strategies reduced indoor humidity fluctuations in all zones, and significantly reduced overall humidity levels in the museum lobby and storage area. An HPHX was installed within one of the two gallery RTUs to improve the unit`s dehumidification performance. The passive HPHX significantly reduced electric reheat and compressor operation while maintaining the precise temperature and humidity requirements within the gallery. The second gallery RTU now operates primarily as a back-up unit to the heat pipe-assisted air-conditioning unit.

  10. 2D numerical analysis of energy harvesting in oscillating heat pipe using piezoelectric transducers

    Science.gov (United States)

    Vaidya, Sajiree; Myers, Oliver; Thompson, Scott; Shamsaei, Nima; Monroe, John G.

    2017-04-01

    Energy Harvesting is a powerful process that deals with exploring different possible ways of converting energy dispersed in the environment into more useful form of energy, essentially electrical energy. Piezoelectric materials are known for their ability of transferring mechanical energy into electrical energy or vice versa. Our work takes advantage of piezoelectric material's properties to covert thermal energy into electrical energy in an oscillating heat pipe. Specific interest in an oscillating heat pipe has relevance to energy harvesting for low power generation suitable for remote electronics operation as well as low-power heat reclamation for electronic packaging. The aim of this paper is develop a 2D multi-physics design analysis model that aids in predicting electrical power generation inherent to an oscillating heat pipe. The experimental design shows a piezoelectric patch with fixed configuration, attached inside an oscillating heat pipe and its behavior when subjected to the oscillating fluid pressure was observed. Numerical analysis of the model depicting the similar behavior was done using a multiphysics FEA software. The numerical model consists of a threeway physics interaction that takes into account fluid flow, solid mechanics, and electrical response of the harvester circuit.

  11. 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...

  12. Optimized Design of Thermoelectric Energy Harvesting Systems for Waste Heat Recovery from Exhaust Pipes

    Directory of Open Access Journals (Sweden)

    Marco Nesarajah

    2017-06-01

    Full Text Available With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert the waste heat from exhaust pipes, which are very often used to transport the heat, e.g., in automobiles, in industrial facilities or in heating systems. That is why a mockup of a heating is built-up, and the developed energy harvesting system is attached. To build-up this system, a model-based development process is used. The setup of the developed energy harvesting system is very flexible to test different variants and an optimized system can be found in order to increase the energy yield for concrete application examples. A corresponding simulation model is also presented, based on previously developed libraries in Modelica®/Dymola®. In the end, it can be shown—with measurement and simulation results—that a thermoelectric energy harvesting system on the exhaust pipe of a heating system delivers extra energy and thus delivers a contribution for a more efficient usage of the inserted primary energy carrier.

  13. Thermal distillation system utilizing biomass energy burned in stove by means of heat pipe

    Directory of Open Access Journals (Sweden)

    Hiroshi Tanaka

    2016-09-01

    Full Text Available A thermal distillation system utilizing a part of the thermal energy of biomass burned in a stove during cooking is proposed. The thermal energy is transported from the stove to the distiller by means of a heat pipe. The distiller is a vertical multiple-effect diffusion distiller, in which a number of parallel partitions in contact with saline-soaked wicks are set vertically with narrow gaps of air. A pilot experimental apparatus was constructed and tested with a single-effect and multiple-effect distillers to investigate primarily whether a heat pipe can transport thermal energy adequately from the stove to the distiller. It was found that the temperatures of the heated plate and the first partition of the distiller reached to about 100 °C and 90 °C, respectively, at steady state, showing that the heat pipe works sufficiently. The distilled water obtained was about 0.75 and 1.35 kg during the first 2 h of burning from a single-effect and multiple-effect distillers, respectively.

  14. Heat Pipe Technology

    Science.gov (United States)

    1981-01-01

    The heat pipe, a sealed chamber whose walls are lined with a "wick," a thin capillary network containing a working fluid in liquid form was developed for a heat distribution system for non-rotating satellites. Use of the heat pipe provides a continuous heat transfer mechanism. "Heat tubes" that improve temperature control in plastics manufacturing equipment incorporated the heat pipe technology. James M. Stewart, an independent consultant, patented the heat tubes he developed and granted a license to Kona Corporation. The Kona Nozzle for heaterless injection molding gets heat for its operation from an external source and has no internal heating bands, reducing machine maintenance and also eliminating electrical hazards associated with heater bands. The nozzles are used by Eastman Kodak, Bic Pen Corporation, Polaroid, Tupperware, Ford Motor Company, RCA, and Western Electric in the molding of their products.

  15. Pump Assisted Heat Pipe

    OpenAIRE

    Miyazaki, Yoshiro; OSHIMA, Shigeto

    1987-01-01

    A labortory model of a pump assisted heat pipe has been fablicated and tested. An arterial heat pipe with axial grooves and a gear pump with a magnetic coupling have been developed for the model. The test has been carried out successfully. The reasonable thermal conductance has been obtained so far as the necessary working fluid flow rate is supplied. The necessary flow rate exceeds the theoretical one and the excess flow rate increases as the heat load increases.

  16. Effects of boosting the supply temperature on pipe dimensions of low-energy district heating networks

    DEFF Research Database (Denmark)

    Tol, Hakan; Svendsen, Svend

    2015-01-01

    This paper presents a method for the dimensioning of the low-energy District Heating (DH) piping networks operating with a control philosophy of supplying heat in low-temperature such as 55 °C in supply and 25°C in return regularly while the supply temperature levels are being boosted in cold...... winter periods. The performance of the existing radiators that were formerly sized with over-dimensions was analyzed, its results being used as input data for the performance evaluation of the piping network of the low-energy DH system operating with the control philosophy in question. The optimization...... from the DH network. Sensitivity analysis was carried out in order to evaluate the area of applicability of the proposed method. Hence varied values of the original capacity and the current capacity of the existing radiators were evaluated with the design temperature values that were defined by two...

  17. 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.

  18. Improved Thin, Flexible Heat Pipes

    Science.gov (United States)

    Rosenfeld, John H.; Gernert, Nelson J.; Sarraf, David B.; Wollen, Peter J.; Surina, Frank C.; Fale, John E.

    2004-01-01

    Flexible heat pipes of an improved type are fabricated as layers of different materials laminated together into vacuum- tight sheets or tapes. In comparison with prior flexible heat pipes, these flexible heat pipes are less susceptible to leakage. Other advantages of these flexible heat pipes, relative to prior flexible heat pipes, include high reliability and greater ease and lower cost of fabrication. Because these heat pipes are very thin, they are highly flexible. When coated on outside surfaces with adhesives, these flexible heat pipes can be applied, like common adhesive tapes, to the surfaces of heat sinks and objects to be cooled, even if those surfaces are curved.

  19. Heat Pipe Integrated Microsystems

    Energy Technology Data Exchange (ETDEWEB)

    Gass, K.; Robertson, P.J.; Shul, R.; Tigges, C.

    1999-03-30

    The trend in commercial electronics packaging to deliver ever smaller component packaging has enabled the development of new highly integrated modules meeting the demands of the next generation nano satellites. At under ten kilograms, these nano satellites will require both a greater density electronics and a melding of satellite structure and function. Better techniques must be developed to remove the subsequent heat generated by the active components required to-meet future computing requirements. Integration of commercially available electronics must be achieved without the increased costs normally associated with current generation multi chip modules. In this paper we present a method of component integration that uses silicon heat pipe technology and advanced flexible laminate circuit board technology to achieve thermal control and satellite structure. The' electronics/heat pipe stack then becomes an integral component of the spacecraft structure. Thermal management on satellites has always been a problem. The shrinking size of electronics and voltage requirements and the accompanying reduction in power dissipation has helped the situation somewhat. Nevertheless, the demands for increased onboard processing power have resulted in an ever increasing power density within the satellite body. With the introduction of nano satellites, small satellites under ten kilograms and under 1000 cubic inches, the area available on which to place hot components for proper heat dissipation has dwindled dramatically. The resulting satellite has become nearly a solid mass of electronics with nowhere to dissipate heat to space. The silicon heat pipe is attached to an aluminum frame using a thermally conductive epoxy or solder preform. The frame serves three purposes. First, the aluminum frame provides a heat conduction path from the edge of the heat pipe to radiators on the surface of the satellite. Secondly, it serves as an attachment point for extended structures attached

  20. 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.

  1. 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.

  2. Heat Pipe Precools and Reheats Dehumidified Air

    Science.gov (United States)

    Koning, R. C.; Boggs, W. H.; Barnett, U. R.; Dinh, K.

    1986-01-01

    Precooling and reheating by heat pipe reduces operating costs of air-conditioning. Warm air returned from air-conditioned space and cooled air supplied are precooled and reheated, respectively, by each other through a heat pipe. Heat-pipe technology brought to bear on problem of conserving airconditioning energy in hot, humid environments. Any increase in the cost of equipment due to installation of heat-pipe heat exchangers expected to be recovered in energy savings during service period of 2 years or less.

  3. 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.

  4. Experimental Study of Thermal Energy Storage Characteristics using Heat Pipe with Nano-Enhanced Phase Change Materials

    Science.gov (United States)

    Krishna, Jogi; Kishore, P. S.; Brusly Solomon, A.

    2017-08-01

    The paper presents experimental investigations to evaluate thermal performance of heat pipe using Nano Enhanced Phase Change Material (NEPCM) as an energy storage material (ESM) for electronic cooling applications. Water, Tricosane and nano enhanced Tricosane are used as energy storage materials, operating at different heating powers (13W, 18W and 23W) and fan speeds (3.4V and 5V) in the PCM cooling module. Three different volume percentages (0.5%, 1% and 2%) of Nano particles (Al2O3) are mixed with Tricosane which is the primary PCM. This experiment is conducted to study the temperature distributions of evaporator, condenser and PCM during the heating as well as cooling. The cooling module with heat pipe and nano enhanced Tricosane as energy storage material found to save higher fan power consumption compared to the cooling module that utilities only a heat pipe.

  5. Transient thermohydraulic heat pipe modeling

    Science.gov (United States)

    Hall, Michael L.; Doster, Joseph M.

    Many space based reactor designs employ heat pipes as a means of conveying heat. In these designs, thermal radiation is the principle means for rejecting waste heat from the reactor system, making it desirable to operate at high temperatures. Lithium is generally the working fluid of choice as it undergoes a liquid-vapor transformation at the preferred operating temperature. The nature of remote startup, restart, and reaction to threats necessitates an accurate, detailed transient model of the heat pipe operation. A model is outlined of the vapor core region of the heat pipe which is part of a large model of the entire heat pipe thermal response. The vapor core is modeled using the area averaged Navier-Stokes equations in one dimension, which take into account the effects of mass, energy and momentum transfer. The core model is single phase (gaseous), but contains two components: lithium gas and a noncondensible vapor. The vapor core model consists of the continuity equations for the mixture and noncondensible, as well as mixture equations for internal energy and momentum.

  6. Heat-pipe planets

    Science.gov (United States)

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

    2017-09-01

    Observations of the surfaces of all terrestrial bodies other than Earth reveal remarkable but unexplained similarities: endogenic resurfacing is dominated by plains-forming volcanism with few identifiable centers, magma compositions are highly magnesian (mafic to ultra-mafic), tectonic structures are dominantly contractional, and ancient topographic and gravity anomalies are preserved to the present. Here we show that cooling via volcanic heat pipes may explain these observations and provide a universal model of the way terrestrial bodies transition from a magma-ocean state into subsequent single-plate, stagnant-lid convection or plate tectonic phases. In the heat-pipe cooling mode, magma moves from a high melt-fraction asthenosphere through the lithosphere to erupt and cool at the surface via narrow channels. Despite high surface heat flow, the rapid volcanic resurfacing produces a thick, cold, and strong lithosphere which undergoes contractional strain forced by downward advection of the surface toward smaller radii. We hypothesize that heat-pipe cooling is the last significant endogenic resurfacing process experienced by most terrestrial bodies in the solar system, because subsequent stagnant-lid convection produces only weak tectonic deformation. Terrestrial exoplanets appreciably larger than Earth may remain in heat-pipe mode for much of the lifespan of a Sun-like star.

  7. Glass heat pipe evacuated tube solar collector

    Science.gov (United States)

    McConnell, Robert D.; Vansant, James H.

    1984-01-01

    A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

  8. Flexible Heat Pipe

    Science.gov (United States)

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

    1985-01-01

    Narrow Tube carries 10 watts or more to moving parts. Heat pipe 12 inches long and diameter of 0.312 inch (7.92mm). Bent to minimum radius of 2.5 blocks. Flexible section made of 321 stainless steel tubing (Cajon Flexible Tubing or equivalent). Evaporator and condenser made of oxygen free copper. Working fluid methanol.

  9. Optimatization of loop heat pipe for cooling of electrotechnical box

    Science.gov (United States)

    Roman, Banovcan; Tomas, Puchor; Andrej, Kapjor; Milan, Malcho

    2017-09-01

    The paper deals with use of LOOP thermosyphon heat pipe to transfer heat from electrotechnical box and describe of construction individual types of LOOP heat pipes. The LOOP heat pipe is very good cooling device which requires no mechanical parts in their design. LOOP heat pipe use only phase change during heat transfer, without a compressor, fan or pump. LOOP heat pipe is more energy saving compared to conventional cooling systems with forced convection. The main advantage of cooling by heat pipe is that electrotechnical box can be hermetically closed (dust -free construction), because dust reduces the lifetime of electrotechnical elements in box. Lifetime of LOOP heat pipe equals to the lifetime of construction material. The paper describes mathematical model of LOOP thermosyphon heat pipe (condenser). Compares selected types of working fluids which are filled with a heat pipe and construction materials of heat pipe.

  10. Advanced thermal energy management: A thermal test bed and heat pipe simulation

    Science.gov (United States)

    Barile, Ronald G.

    1986-01-01

    Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

  11. Multileg Heat-Pipe Evaporator

    Science.gov (United States)

    Alario, J. P.; Haslett, R. A.

    1986-01-01

    Parallel pipes provide high heat flow from small heat exchanger. Six parallel heat pipes extract heat from overlying heat exchanger, forming evaporator. Vapor channel in pipe contains wick that extends into screen tube in liquid channel. Rods in each channel hold wick and screen tube in place. Evaporator compact rather than extended and more compatible with existing heat-exchanger geometries. Prototype six-pipe evaporator only 0.3 m wide and 0.71 m long. With ammonia as working fluid, transports heat to finned condenser at rate of 1,200 W.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Rodrigo Correa

    2010-01-01

    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.

  14. Modular Heat Exchanger With Integral Heat Pipe

    Science.gov (United States)

    Schreiber, Jeffrey G.

    1992-01-01

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

  15. A heat pipe quick disconnect

    Science.gov (United States)

    Alario, J. P.; Otterstedt, P. J.

    1985-07-01

    This paper reports the proof of concept demonstration of a heat pipe quick disconnect being developed for the space constructible radiator system. The disconnect provides a maintainable coupling between the heat pipe evaporator, which is brazed to a mating heat exchanger, and the replaceable condenser section of a monogroove heat pipe radiator element. Test results, with pressurized nitrogen gas, confirm low leakage rates in both demated and mated configurations. Comparative thermal tests in a working 3 m (10 ft) test bed heat pipe using ammonia fluid revealed a 30 percent decrease in heat transport due to the additional minor pressure losses from the quick disconnect. The bulk of this loss is attributed to the transition section that joins the two adjacent heat pipe flow channels to the separated liquid and vapor passages within the disconnect coupling. It would be possible to decrease this overall loss in heat transport to under 10 percent with a redesigned transition section.

  16. Heat pipes for industrial waste heat recovery

    Science.gov (United States)

    Merrigan, M. A.

    1981-01-01

    Development work on the high temperature ceramic recuperator at Los Alamos National Laboratory is described and involved material investigations, fabrication methods development, compatibility tests, heat pipe operation, and the modeling of application conditions based on current industrial usage. Solid ceramic heat pipes, ceramic coated refractory pipes, and high-temperature oxide protected metallic pipes are investigated. Economic studies of the use of heat pipe based recuperators in industrial furnaces are conducted and payback periods determined as a function of material, fabrication, and installation cost.

  17. Heat-Exchanger/Heat-Pipe Interface

    Science.gov (United States)

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

    1987-01-01

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

  18. The use of a double heat pipe heat exchanger system for reducing energy consumption of treating ventilation air in an operating theatre. A full year energy consumption model simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yau, Y.H. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2008-07-01

    In two earlier papers [Y.H. Yau, Application of a heat pipe heat exchanger to dehumidification enhancement in tropical HVAC systems - a baseline performance characteristics study, International Journal of Thermal Sciences 46 (2) (2007) 164-171; ], two series of experiments were conducted under controlled conditions to establish the baseline performance characteristics of the heat pipe heat exchanger (HPHX). In the present paper, a complete empirical transient systems simulation program model is assembled to estimate the air states as well as the entire typical meteorological year energy consumption of an operating theatre located in Kuala Lumpur, Malaysia. The current heating, ventilating and air conditioning (HVAC) systems for the operating theatre are found to be inherently energy-inefficient and can be further improved with a double heat pipe heat exchanger system. The impact on actual energy consumption of a custom-built Trane Air Handler Unit 0704 2-2MB is simulated with two 8-row heat pipe heat exchanger installed in the heating, ventilating and air conditioning system compared to the existing without HPHX HVAC system. Based on this investigation, the application of a double heat pipe heat exchanger system (Plant E) in the conventional Air Handler Unit operating in a tropical climate is strongly recommended as an efficient mean for humidity control and energy savings to maintain acceptable room conditions per American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) requirements [ASHRAE, ASHRAE Handbook HVAC Applications SI Edition, ASHRAE, Atlanta, GA, USA, 1995]. (author)

  19. High-Performance Heat Pipe

    Science.gov (United States)

    Alario, J. P.; Kosson, R.; Haslett, R.

    1985-01-01

    Single vapor channel and single liquid channel joined by axial slot. New design, permits high heat-transport capacity without excessively reducing heat-transfer efficiency. Contains two large axial channels, one for vapor and one for liquid, permitting axial transport and radial heat-transfer requirements met independently. Heat pipe has capacity of approximately 10 to sixth power watt-inches (2.5 X 10 to sixth power watt-cm) orders of magnitude greater than heat capacity of existing heat pipes. Design has high radial-heat-transfer efficiency, structurally simple, and has large liquid and vapor areas.

  20. 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.

  1. Design and experimental study of a mixed energy recovery system, heat pipes and indirect evaporative equipment for air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Francisco Javier Rey; Gomez, Eloy Velasco; Diez, Fernando Varela; Martin, Ruth Herrero [Valladolid Univ., Dept. of Energy Engineering aand Fluid Mechanics, Valladolid (Spain); Plasencia, Mario Antonio Alvarez-Guerra [Cienfuegos Univ., Faculty of Computer Engineering, Cienfuegos (Spain)

    2003-11-01

    Current difficulties surrounding air conditioning systems involve an increase in input air aimed at improving indoor air quality (IAQ), the financial costs arising from energy consumption and external environmental impact, linked to the greenhouse effect (GWP) and the destruction of the ozone layer (ODP). One alternative technique which offers an adequate combination of IAQ and acceptable energy saving is the introduction of energy recovery systems using air extracted from air-conditioned premises. We have designed a mixed air-energy recovery system, consisting of two heat pipes and indirect evaporative recuperators. The experimental set-up used is described and the proposed energy recovery system is characterised. A staggered set-up has been chosen for the input air pipe and a parallel one for the extracted air for variable recirculation. By means of the trace gas method and photoacoustic spectroscopy (PAS) the amount of exfiltrated flow in the installation is measured. The energy characterisation of the mixed energy recovery system was performed by means of the experimental design technique. An analysis was carried out of the influence of factors such as temperature, flow, relative humidity, water flow, etc. on the basic characteristics defined by the mixed system: heat flow, heat efficiency and COP. (Author)

  2. 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.

  3. 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.

  4. High performance flexible heat pipes

    Science.gov (United States)

    Shaubach, R. M.; Gernert, N. J.

    1985-01-01

    A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

  5. Heat-pipes-based first wall

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, V. [Research and Development Institute of Power Engineering, PO Box 788, Moscow 101000 (Russian Federation); Khripunov, V. [Russian Research Center `Kurchatov Institute`, Nuclear Fusion Institute, Kurchatov Square, Moscow 123182 (Russian Federation); Antipenkov, A. [Research and Development Institute of Power Engineering, PO Box 788, Moscow 101000 (Russian Federation); Ulianov, A. [State Enterprise `Krasnaya Zvezda`, Electrolytny pr-d., 1a, Moscow 115230 (Russian Federation)

    1995-03-01

    Feasibilities of heat pipes application for the heat transfer out of plasma facing components in test and power fusion reactors are discussed. Based on the space technology and practice the ``hot`` ITER first wall with liquid metal and water heat pipes are proposed in two options: heat-pipes and vapor-chamber options. Other high heat loading in-vessel elements such as divertor target and limiter can be provided by effective and reliable heat pipe cooling systems. (orig.).

  6. Experimental investigation for the optimization of heat pipe performance in latent heat thermal storage

    Energy Technology Data Exchange (ETDEWEB)

    Ladekar, Chandrakishor; Choudhary, S. K. [RTM Nagpur University, Wardha (India); Khandare, S. S. [B. D. College of Engineering, Wardha (India)

    2017-06-15

    We investigated the optimum performance of heat pipe in Latent heat thermal energy storage (LHTES), and compared it with copper pipe. Classical plan of experimentation was used to optimize the parameters of heat pipe. Heat pipe fill ratio, evaporator section length to condenser section length ratio i.e., Heat pipe length ratio (HPLR) and heat pipe diameter, was the parameter used for optimization, as result of parametric analysis. Experiment with flow rate of 10 lit./min. was conducted for different fill ratio, HPLR and different diameter. Fill ratio of 80 %, HPLR of 0.9 and heat pipe with diameter of 18 mm showed better trend in charging and discharging. Comparison between the storage tank with optimized heat pipe and copper pipe showed almost 186 % improvement in charging and discharging time compared with the copper pipe embedded thermal storage. Heat transfer between Heat transferring fluid (HTF) and Phase change material (PCM) increased with increase in area of heat transferring media, but storage density of storage tank decreased. Storage tank with heat pipe embedded in place of copper pipe is a better option in terms of charging and discharging time as well heat storage capacity due to less heat lost. This justifies the better efficiency and effectiveness of storage tank with embedded optimized heat pipe.

  7. Introduction to Loop Heat Pipes

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    This is the presentation file for the short course Introduction to Loop Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. This course will discuss operating principles and performance characteristics of a loop heat pipe. Topics include: 1) pressure profiles in the loop; 2) loop operating temperature; 3) operating temperature control; 4) loop startup; 4) loop shutdown; 5) loop transient behaviors; 6) sizing of loop components and determination of fluid inventory; 7) analytical modeling; 8) examples of flight applications; and 9) recent LHP developments.

  8. Cryogenic thermal diode heat pipes

    Science.gov (United States)

    Alario, J.

    1979-01-01

    The development of spiral artery cryogenic thermal diode heat pipes was continued. Ethane was the working fluid and stainless steel the heat pipe material in all cases. The major tasks included: (1) building a liquid blockage (blocking orifice) thermal diode suitable for the HEPP space flight experiment; (2) building a liquid trap thermal diode engineering model; (3) retesting the original liquid blockage engineering model, and (4) investigating the startup dynamics of artery cryogenic thermal diodes. An experimental investigation was also conducted into the wetting characteristics of ethane/stainless steel systems using a specially constructed chamber that permitted in situ observations.

  9. 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.

  10. 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.

  11. Dual axial channel heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Alario, J.P.; Haslett, R.A.; Kosson, R.L.

    1984-09-11

    A heat pipe comprising an elongated sealed metallic envelope having at least a pair of longitudinal channels extending along the length thereof. One of the channels is for the circulation of the vapor phase of the working medium in operation and the other for the liquid phase and capillary means are provided to furnish fluid communication therebetween. Dedicated vapor and liquid channels result in low viscous pressure drops, the capillary communication means and circumferential grooving in the vapor channel provide high capillary pressure differences, and circumferential grooving is provided to furnish the high evaporation and condensation film coefficients required. To support higher heat fluxes, wicking can be used to augment the capillary flow from the liquid channel. To support higher evaporator heat flux without the need for wicking means, the heat pipe can be provided with more than one liquid channel, each communicating with the vapor channel by capillary means. The heat pipe can be provided with an integral fin or equivalent means for rejection of heat by radiation to ambient or for attachment to a source of heat in the evaporator region thereof.

  12. Modular heat-pipe-radiator panel

    Science.gov (United States)

    Alario, J.

    1979-01-01

    Heat-Pipe panel assembled by joining series of Heat-Pipe modules is presented. Each module is identical and includes own radiator Fin and Fluid-Header section. Arrangement gives high turn-down ratio permitting ammonia heat pipes to freeze under low conditions.

  13. Numerical and Experimental Study on Energy Performance of Photovoltaic-Heat Pipe Solar Collector in Northern China

    Directory of Open Access Journals (Sweden)

    Hongbing Chen

    2015-01-01

    Full Text Available Several studies have found that the decrease of photovoltaic (PV cell temperature would increase the solar-to-electricity conversion efficiency. Water type PV/thermal (PV/T system was a good choice but it could become freezing in cold areas of Northern China. This paper proposed a simple combination of common-used PV panel and heat pipe, called PV-heat pipe (PV-HP solar collector, for both electrical and thermal energy generation. A simplified one-dimensional steady state model was developed to study the electrical and thermal performance of the PV-HP solar collector under different solar radiations, water flow rates, and water temperatures at the inlet of manifold. A testing rig was conducted to verify the model and the testing data matched very well with the simulation values. The results indicated that the thermal efficiency could be minus in the afternoon. The thermal and electrical efficiencies decreased linearly as the inlet water temperature and water flow rate increased. The thermal efficiency increased while the electrical efficiency decreased linearly as the solar radiation increased.

  14. Heat pipes as perspective base elements of heat recovery in heat supply and ventilating systems

    Directory of Open Access Journals (Sweden)

    Matveev Andrey

    2017-01-01

    Full Text Available Thermotechnical characteristics of heat pipes are considered as high-efficient heat-transfer devices, which can provide energy-saving technologies for heat supply and ventilating systems and for different branches of industry. Thermotechnical and working (”performance capability” characteristics of heat pipes are investigated. By ”performance capability” of heat pipes and heat-transfer devices on heat pipes we mean the system state, where it can perform set functions and keep parameter values (thermal power, conductivity, thermal resistance, heat-transfer coefficient, temperature level and differential, etc. within the regulations of standardized specifications. The article presents theoretical and experimental methods of «gaslock» length determination on noncondensable gases during long-lasting tests of ammonia heat pipes made of aluminum shape АS – КRА 7.5 – R1 (alloy АD – 31. The paper gives results of research of thermotechnical characteristics of heat pipes in horizontal and vertical states (separate and as a set part while using different systems of thermal insulation. The obtained results of thermotechnical and resource tests show the advantages of ammonia heat pipes as basic elements for heat exchanger design in heating and ventilation systems.

  15. Cogeneration with gas turbines. Use of heat pipe type exchangers for the energy recuperation of exhausted gases; Cogeracao com turbinas a gas. O uso de trocador tipo tubos de calor (heat pipe) para a recuperacao energetica dos gases de exaustao

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Jose Luz; Balestieri, Jose A.P.; Tanisho, Petronio Masanobu; Zanardi, Mauricio Araujo; Murcia, Nelson [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Energia

    1995-07-01

    Gas turbine cogeneration systems are being widely used in the simultaneous production of electricity and useful heat. Several devices can be indicated to the recovery of exhaust gas heat from gas turbine systems, for example heat recovery steam generators, boiling-water heaters, absorption refrigerating systems (cooled water), drying systems (heated air), each one indicated for a specific use of recovery heat. In this paper it is proposed the use of heat pipes exchangers in the recovery of exhaust gas heat to produce heated water to be used in a process. Heat pipes are devices that has high thermal conductance that can be used to reduce thermal losses to the environment. The use of heat pipes in these types of equipment can provide heat recoveries of high efficiency since both fluid flows are external and there are less contamination risks between the hot and cold streams. (author)

  16. 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

  17. 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...

  18. 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.

  19. 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...

  20. Orifice Blocks Heat Pipe in Reverse Mode

    Science.gov (United States)

    Alario, J. P.

    1982-01-01

    High forward-mode conductance is combined with rapid reverse-mode shutoff in a heat pipe originally developed to cool spacecraft payloads. A narrow orifice within the pipe "chokes off" the evaporator if heat sink becomes warmer than source. During normal operation, with source warmer than sink, orifice has little effect. Design is simpler and more compact than other thermal-diode heat pipes and requires no special materials, forgings, or unusual construction techniques.

  1. 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...

  2. 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.

  3. Basic measurements on a multiple heat pipe

    Science.gov (United States)

    Rohner, P.; Schippl, K.

    1982-04-01

    A multiple heat pipe which is a specially formed long heat pipe that fulfills the function of several single heat pipes was studied. The suitability of this arrangement for a heat exchanger was investigated. Several laboratory models were manufactured from corrugated tubes and their behavior was measured. Results show that the serpentine model exhibits the expected heat exchange properties. When subjected to severe operating conditions, the pipes remain operational, although somewhat limited in performance. The results are in function of the nature of the exchange media (air-air, air-water, water-water). This corrugated heat pipe design shows good promise for successful further development into an air-air heat exchanger.

  4. 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.

  5. Heat pipe nuclear reactor for space power

    Science.gov (United States)

    Koening, D. R.

    1976-01-01

    A heat-pipe-cooled nuclear reactor has been designed to provide 3.2 MWth to an out-of-core thermionic conversion system. The reactor is a fast reactor designed to operate at a nominal heat-pipe temperature of 1675 K. Each reactor fuel element consists of a hexagonal molybdenum block which is bonded along its axis to one end of a molybdenum/lithium-vapor heat pipe. The block is perforated with an array of longitudinal holes which are loaded with UO2 pellets. The heat pipe transfers heat directly to a string of six thermionic converters which are bonded along the other end of the heat pipe. An assembly of 90 such fuel elements forms a hexagonal core. The core is surrounded by a thermal radiation shield, a thin thermal neutron absorber, and a BeO reflector containing boron-loaded control drums.

  6. Theoretical and experimental validation study on automotive air-conditioning based on heat pipe and LNG cold energy for LNG-fueled heavy vehicles

    Science.gov (United States)

    Deng, Dong; Cheng, Jiang-ping; Zhang, Sheng-chang; Ge, Fang-gen

    2017-08-01

    As a clean fuel, LNG has been used in heavy vehicles widely in China. Before reaching the engine for combustion, LNG store in a high vacuum multi-layer thermal insulation tank and need to be evaporated from its cryogenic state to natural gas. During the evaporation, the available cold energy of LNG has been calculated. The concept has been proposed that the separated type heat pipe technology is employed to utilize the available cold energy for automotive air-conditioning. The experiment has been conducted to validate the proposal. It is found that it is feasible to use the separated type heat pipe to convey the cold energy from LNG to automotive air-conditioning. And the cooling capacity of the automotive air-conditioning increase with the LNG consumption and air flow rate increasing.

  7. Literature review and experimental investigation of heat pipes

    Science.gov (United States)

    Barsch, W. O.; Schoenhals, R. J.; Viskanta, R.; Winter, E. R. F.

    1971-01-01

    Tests on heat pipes determine operational limits, external boundary conditions, noncondensable gas effects, startup behavior, and geometric configurations. Experiment consists of design, construction, and testing of an apparatus for measuring wick properties, conventional heat pipes and coplanar heat pipes.

  8. Experimental study of the naphtaline heat pipe

    Science.gov (United States)

    Honda, I.; Suzuki, A.; Abe, Y.; Sugihara, S.

    1984-03-01

    Industrial needs for heat pipes which are operable at medium and high temperature ranges over 200 C are increasing in order to recover waste heat from high temperature furnaces or to cool aluminum diecasting molds. Naphthaline is attractive working fluid due to its cost and easiness of handling for medium temperature range. In the heat transfer characteristics, the fabrication method and also the life test result of the heat pipes using naphtaline as the working fluid are reported.

  9. Heat Pipe Technology: A bibliography with abstracts

    Science.gov (United States)

    1974-01-01

    This bibliography lists 149 references with abstracts and 47 patents dealing with applications of heat pipe technology. Topics covered include: heat exchangers for heat recovery; electrical and electronic equipment cooling; temperature control of spacecraft; cryosurgery; cryogenic, cooling; nuclear reactor heat transfer; solar collectors; laser mirror cooling; laser vapor cavitites; cooling of permafrost; snow melting; thermal diodes variable conductance; artery gas venting; and venting; and gravity assisted pipes.

  10. 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

  11. Multi-leg heat pipe evaporator

    Science.gov (United States)

    Alario, J. P.; Haslett, R. A.

    1986-04-01

    A multileg heat pipe evaporator facilitates the use and application of a monogroove heat pipe by providing an evaporation section which is compact in area and structurally more compatible with certain heat exchangers or heat input apparatus. The evaporation section of a monogroove heat pipe is formed by a series of parallel legs having a liquid and a vapor channel and a communicating capillary slot therebetween. The liquid and vapor channels and interconnecting capillary slots of the evaporating section are connected to the condensing section of the heat pipe by a manifold connecting liquid and vapor channels of the parallel evaporation section legs with the corresponding liquid and vapor channels of the condensing section.

  12. Heat pipe radiator. [for spacecraft waste heat rejection

    Science.gov (United States)

    Swerdling, B.; Alario, J.

    1973-01-01

    A 15,000 watt spacecraft waste heat rejection system utilizing heat pipe radiator panels was investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500 watt radiator panel was designed, built and tested. The panel, which is a module of the 15,000 watt system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiating fin. The thermal load to the VCHP is supplied by a Freon-21 liquid loop via an integral heat exchanger. Descriptions of the results of the system studies and details of the radiator design are included along with the test results for both the heat pipe components and the assembled radiator panel. These results support the feasibility of using heat pipes in a spacecraft waste heat rejection system.

  13. Flexible heat pipes with integrated bioinspired design

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2015-02-01

    Full Text Available In this work we report the facile fabrication and performance evaluation of flexible heat pipes that have integrated bioinspired wick structures and flexible polyurethane polymer connector design between the copper condenser and evaporator. Inside the heat pipe, a bioinspired superhydrophilic strong-base-oxidized copper mesh with multi-scale micro/nano-structures was used as the wicking material and deionized water was selected as working fluid. Thermal resistances of the fabricated flexible heat pipes charged with different filling ratios were measured under thermal power inputs ranging from 2 W to 12 W while the device was bent at different angles. The fabricated heat pipes with a 30% filling ratio demonstrated a low thermal resistance less than 0.01 K/W. Compared with the vertically oriented straight heat pipes, bending from 30° up to 120° has negligible influence on the heat-transfer performance. Furthermore, repeated heating tests indicated that the fabricated flexible heat pipes have consistent and reliable heat-transfer performance, thus would have important applications for advanced thermal management in three dimensional and flexible electronic devices.

  14. 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.

  15. Research of Spined Heat-Exchanging Pipes

    Directory of Open Access Journals (Sweden)

    Akulov Kirill

    2016-01-01

    Full Text Available Work is devoted to a research of spined heat-exchanging pipes that are assumed to use in air-cooler exchangers (ACE. The proposed new geometry of finning allows intensifying heat exchange and improving the efficiency of air coolers. It is caused by the increased area of finned surface with a value of finning ratio (the ratio of the area of the smooth pipe to a finned one to 42.7, while in the commercially available ACE, the figure is 22. Besides, the geometrical arrangement of the pin fins turbulizes the airflow. It should be mentioned that an easier method of manufacturing of heat exchanging pipes is proposed to use, which will reduce their costs. The proposed heat exchange pipes are made by winding cut aluminum strip to the supporting pipe or stretching stamped blanks on it. To increase the efficiency of the heat exchange surface pin fins should be as thin and long as possible; however, their strength should be sufficient for deformation-free operation. Fins should be staggered to maximize the distance between them. Spined heat-exchange pipes are designed to operate in a commercially produced ACE and their service is carried out similarly to commercially produced transversely finned pipes.

  16. Gas lensing in a heated spinning pipe

    CSIR Research Space (South Africa)

    Mafusire, C

    2006-07-01

    Full Text Available When a heated pipe is rotated, the dynamics of the gas inside exhibit properties reminiscent of a solid-state positive lens. The properties are a result of a parabolic distribution of refractive index in the pipe which is caused by mixing of hot...

  17. 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

  18. Reentrant-Groove Hydrogen Heat Pipe

    Science.gov (United States)

    Alario, J.; Kosson, R.

    1982-01-01

    Aluminum heat pipe extruded with reentrant axial grooves, which give better overall performance than conventional rectangular grooves. Reentrant grooves increase wicking height of cryogenic fluids and also lower amount of fluid charge required.

  19. 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 this...

  20. 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...

  1. 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...

  2. Mathematical Modeling of Loop Heat Pipes

    Science.gov (United States)

    Kaya, Tarik; Ku, Jentung; Hoang, Triem T.; Cheung, Mark L.

    1998-01-01

    The primary focus of this study is to model steady-state performance of a Loop Heat Pipe (LHP). The mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat exchange between each LHP component and the surrounding is taken into account. Both convection and radiation environments are modeled. The loop operating temperature is calculated as a function of the applied power at a given loop condition. Experimental validation of the model is attempted by using two different LHP designs. The mathematical model is tested at different sink temperatures and at different elevations of the loop. Tbc comparison of the calculations and experimental results showed very good agreement (within 3%). This method proved to be a useful tool in studying steady-state LHP performance characteristics.

  3. Modelling and performance of heat pipes with long evaporator sections

    NARCIS (Netherlands)

    Wits, Wessel W.; te Riele, Gert Jan

    2017-01-01

    This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling

  4. Flexible heat pipes with integrated bioinspired design

    OpenAIRE

    Chao Yang; Chengyi Song; Wen Shang; Peng Tao; Tao Deng

    2015-01-01

    In this work we report the facile fabrication and performance evaluation of flexible heat pipes that have integrated bioinspired wick structures and flexible polyurethane polymer connector design between the copper condenser and evaporator. Inside the heat pipe, a bioinspired superhydrophilic strong-base-oxidized copper mesh with multi-scale micro/nano-structures was used as the wicking material and deionized water was selected as working fluid. Thermal resistances of the fabricated flexible ...

  5. GPM Avionics Module Heat Pipes Design and Performance Test Results

    Science.gov (United States)

    Ottenstein, Laura; DeChristopher, Mike

    2011-01-01

    The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide the next-generation global observations of rain and snow. The GPM core satellite carries an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. Through improved measurements of precipitation globally, the GPM mission will help to advance our understanding of Earth's water and energy cycle, improve forecasting of extreme events that cause natural hazards and disasters, and extend current capabilities in using accurate and timely information of precipitation to directly benefit society. The avionics module on the core satellite contains a number of electronics boxes which are cooled by a network of aluminum/ammonia heat pipes and a honeycomb radiator which contains thirteen embedded aluminum/ammonia heat pipes. All heat pipes were individually tested by the vendor (Advanced Cooling Technologies, Inc.) prior to delivery. Following delivery to NASA, the flight avionics radiator and the flight spare transport heat pipes were mounted to flight-like test structure and a system level thermal vacuum test was performed. This test, which used simulators in place of all electronics boxes, was done to verify the operation of the thermal control system as a whole. This presentation will discuss the design of the avionics module heat pipes, and then discuss performance tests results for the individual heat pipes prior to delivery and for the system level thermal vacuum test. All heat pipes met their performance requirements. However, it was found that the power was too low in some instances to start all of the smaller radiator spreader heat pipes when they were tested in a reflux configuration (which is the nominal test configuration). Although this lowered the efficiency of the radiator somewhat, it did not impact the operating

  6. Performance testing of a hydrogen heat pipe

    Science.gov (United States)

    Alario, J.; Kosson, R.

    1980-01-01

    Test results are presented for a reentrant groove heat pipe with hydrogen working fluid. The heat pipe became operational between 20 and 30 K after a cooldown from 77 K without any difficulty. Steady-state performance data taken over a 19 to 23 K temperature range indicated the following: (1) maximum heat transport capacity = 5.4 W-m; (2) static wicking height = 1.42 cm; and (3) overall heat pipe conductance = 1.7 W/C. These data agreed remarkably well with extrapolations made from comparable ammonia test results. The maximum heat transport capacity is 9.5% larger than the extrapolated value, but the static wicking height is the same. The overall conductance is 29% of the ammonia value, which is close to the ratio of liquid thermal conductivities (24%). Also, recovery from a completely frozen condition was accomplished within 5 min by simply applying an evaporater heat load of 1.8 W.

  7. 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.

  8. 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...

  9. The monogroove high performance heat pipe

    Science.gov (United States)

    Alario, J.; Haslett, R.; Kosson, R.

    1981-06-01

    The development of the monogroove heat pipe, a fundamentally new high-performance device suitable for multi-kilowatt space radiator heat-rejection systems, is reported. The design separates heat transport and transfer functions, so that each can be separately optimized to yield heat transport capacities on the order of 25 kW/m. Test versions of the device have proven the concept of heat transport capacity control by pore dimensions and the permeability of the circumferential wall wick structure, which together render it insensitive to tilt. All cases tested were for localized, top-side heat input and cooling and produced results close to theoretical predictions.

  10. Casing free district heating pipes; Mantelfria fjaerrvaermeroer

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

    Previous studies have shown that polyurethane insulation (PUR foam) on district heating pipes acts as protection against water if it is of good quality, i.e. free from cracks, cavities and other defects. On the other hand water vapour easily diffuses through PUR foam. However this is not a problem as long as the steel pipe is warmer than the surface layer, since the high temperature will prevent the vapour from condensating. What will happen with the insulation of a casing free district heating pipe where the ground water level occasionally reaches above the pipe has not been studied in detail. The current project has studied to what extent moisture enters the PUR foam insulation of two approximately one meter long district heating pipes without casing which have been in the ground for four years. Occasionally, the ground-water has entirely covered the pipes. In addition, the foam has been studied with respect to damage from the surrounding backfill material. Test specimens were taken out of the casing free pipes and were analysed with respect to moisture content. Additional measurements were done with a moisture indicator, and the electric resistance between the steel pipes and the four surveillance wires in each pipe was measured. The results from the various measurement techniques were the compared. The results show that the PUR foam remains dry as long as the service pipe is hot if no defects, such as crack and cavities, are present. Close to the service pipe, the foam actually dries out over time. The moisture content of the middle layer remains more or less constant. Only the colder parts on the outside exhibit an increase in moisture content. It was also seen that defects may lead to water ingress with subsequent humidification of the foam. However, the damaged foam area is limited. This is not the case for a regular pipe with a vapour tight casing, where experience show that moisture tend to spread along the pipe. The pipes were buried in sand and no

  11. Heat pipe heat rejection system. [for electrical batteries

    Science.gov (United States)

    Kroliczek, E. J.

    1976-01-01

    A prototype of a battery heat rejection system was developed which uses heat pipes for more efficient heat removal and for temperature control of the cells. The package consists of five thermal mock-ups of 100 amp-hr prismatic cells. Highly conductive spacers fabricated from honeycomb panels into which heat pipes are embedded transport the heat generated by the cells to the edge of the battery. From there it can be either rejected directly to a cold plate or the heat flow can be controlled by means of two variable conductance heat pipes. The thermal resistance between the interior of the cells and the directly attached cold plate was measured to be 0.08 F/Watt for the 5-cell battery. Compared to a conductive aluminum spacer of equal weight the honeycomb/heat pipe spacer has approximately one-fifth of the thermal resistance. In addition, the honeycomb/heat pipe spacer virtually eliminates temperature gradients along the cells.

  12. Hydrogen evolution in nickel-water heat pipes.

    Science.gov (United States)

    Anderson, W. T.

    1973-01-01

    A study was made of the evolution of hydrogen gas in nickel-water heat pipes for the purpose of investigating methods of accelerated life testing. The data were analyzed in terms of a phenomenological corrosion model of heat pipe degradation which incorporates corrosion and oxidation theory and contains parameters which can be determined by experiment. The gas was evolved with a linear time dependence and an exponential temperature dependence with an activation energy of 1.03 x 10 to the minus 19th joules. A flow-rate dependence of the gas evolution was found in the form of a threshold. The results were used to predict usable lifetimes of heat pipes operated at normal operating conditions from results taken under accelerated operating conditions.

  13. Flexible Cryogenic Heat Pipe Development Program

    Science.gov (United States)

    1976-01-01

    A heat pipe was designed for operation in the 100 - 200 K temperature range with maximum heat transport as a primary design goal; another designed for operation in the 15 - 100 K temperature range with maximum flexibility as a design goal. Optimum geometry and materials for the container and wicking systems were determined. The high power (100 - 200 K) heat pipe was tested with methane at 100 - 140 K, and test data indicated only partial priming with a performance limit of less than 50 percent of theoretical. A series of tests were conducted with ammonia at approximately 280 K to determine the performance under varying fluid charge and test conditions. The low temperature heat pipe was tested with oxygen at 85 - 95 K and with methanol at 295 - 315 K. Performance of the low temperature heat pipe was below theoretical predictions. Results of the completed testing are presented and possible performance limitation mechanisms are discussed. The lower-than-expected performance was felt to be due to small traces of non-condensible gases which prevented the composite wick from priming.

  14. Stirling engine external heat system design with heat pipe heater

    Science.gov (United States)

    Godett, Ted M.; Ziph, Benjamin

    1986-01-01

    This final report presents the conceptual design of a liquid fueled external heating system (EHS) and the preliminary design of a heat pipe heater for the STM-4120 Stirling cycle engine, to meet the Air Force mobile electric power (MEP) requirement for units in the range of 20 to 60 kW. The EHS design had the following constraints: (1) Packaging requirements limited the overall system dimensions to about 330 mm x 250 mm x 100 mm; (2) Heat flux to the sodium heat pipe evaporator was limited to an average of 100 kW/m and a maximum of 550 kW/m based on previous experience; and (3) The heat pipe operating temperature was specified to be 800 C based on heat input requirements of the STM4-120. An analysis code was developed to optimize the EHS performance parameters and an analytical development of the sodium heat pipe heater was performed; both are presented and discussed. In addition, construction techniques were evaluated and scale model heat pipe testing performed.

  15. 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.)

  16. A multifunctional heat pipe sandwich panel structure

    Energy Technology Data Exchange (ETDEWEB)

    Queheillalt, Douglas T.; Wadley, Haydn N.G. [University of Virginia, Department of Materials Science and Engineering, 140 Chemistry Way, P.O. Box 400745, Charlottesville, VA 22904 (United States); Carbajal, Gerardo [University of Turabo, School of Engineering, P.O. Box 3030, Gurabo 00778 (Puerto Rico); Peterson, G.P. [University of Colorado at Boulder, 914 Broadway, Boulder, CO 80309 (United States)

    2008-01-15

    A multifunctional sandwich panel combining efficient structural load support and thermal management characteristics has been designed and experimentally assessed. The concept is based upon a truncated, square honeycomb sandwich structure. In closed cell honeycomb structures, the transport of heat from one face to the other occurs by a combination of conduction through the webs and convection/radiation within the cells. Here, much more effective heat transport is achieved by multifunctionally utilizing the core as a heat pipe sandwich panel. Its interior consists of a 6061 aluminum truncated-square honeycomb core covered with a stochastic open-cell nickel foam wick. An electroless nickel plating barrier layer inhibited the chemical reaction between the deionized water working fluid and the aluminum structure, retarding the generation of non-condensable hydrogen gas. A thermodynamic model was used to guide the design of the heat pipe sandwich panel. We describe the results of a series of experiments that validate the operational principle of the multifunctional heat pipe sandwich panel and characterize its transient response to an intense localized heat source. The systems measured thermal response to a localized heat source agrees well with that predicted by a finite difference method model used to predict the thermal response. (author)

  17. Heat Pipes and Loop Heat Pipes Acceptance Tests for Satellites Applications

    Science.gov (United States)

    Riehl, Roger R.

    2009-03-01

    The use of heat pipes and loop heat pipes (LHPs) as thermal control devices in satellites and other spacecrafts have increased considerably during the last decades. Due to the need of a crescent demand on heat dissipation, more of these devices have been used in low orbit and geo-stationary satellites to promote the adequate thermal control for the instrumentation and equipments aboard. Even though each design is dedicated to a specific application, heat pipes and LHPs have to go through acceptance tests prior to be integrated in the satellite's honeycomb panels (in case of most heat pipes applications) and instrumentation (in case of LHPs thermal control). In order to give a guideline for the required acceptance tests that heat pipes and LHPs have to be submitted, this paper presents the constraints that need to be considered while performing those tests. In all cases, the acceptance tests for both heat pipes and LHPs are related to the most important conditions to verify their proper operation before integrating them on their designed application in a satellite. Such acceptance tests are important to correctly evaluate these thermal control devices and avoid malfunctions while qualifying the entire satellite.

  18. Space shuttle orbiter heat pipe applications. Volume 1: Synopsis

    Science.gov (United States)

    Alario, J. P.; Prager, R. C.

    1972-01-01

    An investigation was made to formulate and evaluate heat pipe applications for the space shuttle orbiter. Of the twenty-seven specific applications which were identified, a joint evaluation resulted in the selection of five of the most promising ones for prototype development. The formulation process is described, along with the applications which evolved. The bulk of the discussion deals with the top five applications: (1) heat pipe augmented cold rail; (2) avionics heat pipe circuit; (3) heat pipe/phase change material modular sink; (4) air-to-heat-pipe heat exchanger; and (5) heat pipe radiator for compartment temperature control. The philosophy, physical design details, and performance data are presented for each concept along with a comparison to the baseline design where applicable. A sixth application, heat pipe space radiator for waste heat rejection, was also recommended for prototype development.

  19. 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.

  20. 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

  1. 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

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

    Directory of Open Access Journals (Sweden)

    Vantúch Martin

    2014-03-01

    Full Text Available 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.

  3. Computational model of miniature pulsating heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Mario J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Givler, Richard C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    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.

  4. 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...

  5. Heat pipes with variable thermal conductance property for space applications

    Energy Technology Data Exchange (ETDEWEB)

    Kravets, V.; Alekseik, Ye.; Alekseik, O.; Khairnasov, S. [National Technical University of Ukraine, Kyiv (Ukraine); Baturkin, V.; Ho, T. [Explorationssysteme RY-ES, Bremen (Germany); Celotti, L. [Active Space Technologies GmbH, Berlin (Germany)

    2017-06-15

    The activities presented in this paper demonstrate a new approach to provide passive thermal control using heat pipes, as demonstrated on the electronic unit of DLR’s MASCOT lander, which embarked on the NEA sample return mission Hayabusa 2 (JAXA). The focus is on the development and testing of heat pipes with variable thermal conductance in a predetermined temperature range. These heat pipes act as thermal switches. Unlike standard gasloaded heat pipes and thermal-diode heat pipes construction of presented heat pipes does not include any additional elements. Copper heat pipes with metal fibrous wicks were chosen as baseline design. We obtained positive results by choosing the heat carrier and structural parameters of the wick (i.e., pore diameter, porosity, and permeability). The increase in the thermal conductivity of the heat pipes from 0.04 W/K to 2.1 W/K was observed in the temperature range between −20 °C and +55 °C. Moreover, the heat pipes transferred the predetermined power of not less than 10 W within the same temperature range. The heat pipes have been in flight since December 2014, and the supporting telemetry data were obtained in September 2015. The data showed the nominal operation of the thermal control system.

  6. Modular heat pipe radiators for enhanced Shuttle mission capabilities

    Science.gov (United States)

    Alario, J.; Haslett, R.

    1979-01-01

    Current heat pipe radiator technology is reviewed and the results from three state-of-the-art hardware programs are summarized. Heat pipe radiators are shown to be an improvement over all-fluid loop panels for long duration space missions, when micrometeoroid survivability is important. Finally, several heat pipe radiator design concepts are presented which would enhance Shuttle mission capabilities by either extending mission life and/or augmenting heat rejection capability.

  7. 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

    The low-energy district heating concept has the potential of increasing the energy and exergy efficiencies of heat supply systems and of exploiting renewable energy, provided technical solutions for its wide application can be developed and implemented. This paper investigates the dynamic behaviour...... against experimental measurements and compared to the results of an analytical formula and the FV simulations. The model proved accurate, since it gives results that well represent the outlet temperature profiles measured in the experiments and calculated in the FV simulations, both where there was a step...... change of the inlet temperature and where there was a sinusoidal inlet temperature profile. The model could be used for the development of improved substation concepts and enhanced control strategies....

  8. 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.

  9. Space shuttle heat pipe thermal control systems

    Science.gov (United States)

    Alario, J.

    1973-01-01

    Heat pipe (HP) thermal control systems designed for possible space shuttle applications were built and tested under this program. They are: (1) a HP augmented cold rail, (2) a HP/phase change material (PCM) modular heat sink and (3) a HP radiating panel for compartment temperature control. The HP augmented cold rail is similar to a standard two-passage fluid cold rail except that it contains an integral, centrally located HP throughout its length. The central HP core helps to increase the local power density capability by spreading concentrated heat inputs over the entire rail. The HP/PCM modular heat sink system consists of a diode HP connected in series to a standard HP that has a PCM canister attached to its mid-section. It is designed to connect a heat source to a structural heat sink during normal operation, and to automatically decouple from it and sink to the PCM whenever structural temperatures are too high. The HP radiating panel is designed to conductively couple the panel feeder HPs directly to a fluid line that serves as a source of waste heat. It is a simple strap-on type of system that requires no internal or external line modifications to distribute the heat to a large radiating area.

  10. Study on heat pipe assisted thermoelectric power generation system from exhaust gas

    Science.gov (United States)

    Chi, Ri-Guang; Park, Jong-Chan; Rhi, Seok-Ho; Lee, Kye-Bock

    2017-11-01

    Currently, most fuel consumed by vehicles is released to the environment as thermal energy through the exhaust pipe. Environmentally friendly vehicle technology needs new methods to increase the recycling efficiency of waste exhaust thermal energy. The present study investigated how to improve the maximum power output of a TEG (Thermoelectric generator) system assisted with a heat pipe. Conventionally, the driving energy efficiency of an internal combustion engine is approximately less than 35%. TEG with Seebeck elements is a new idea for recycling waste exhaust heat energy. The TEG system can efficiently utilize low temperature waste heat, such as industrial waste heat and solar energy. In addition, the heat pipe can transfer heat from the automobile's exhaust gas to a TEG. To improve the efficiency of the thermal power generation system with a heat pipe, effects of various parameters, such as inclination angle, charged amount of the heat pipe, condenser temperature, and size of the TEM (thermoelectric element), were investigated. Experimental studies, CFD simulation, and the theoretical approach to thermoelectric modules were carried out, and the TEG system with heat pipe (15-20% charged, 20°-30° inclined configuration) showed the best performance.

  11. Study on heat pipe assisted thermoelectric power generation system from exhaust gas

    Science.gov (United States)

    Chi, Ri-Guang; Park, Jong-Chan; Rhi, Seok-Ho; Lee, Kye-Bock

    2017-04-01

    Currently, most fuel consumed by vehicles is released to the environment as thermal energy through the exhaust pipe. Environmentally friendly vehicle technology needs new methods to increase the recycling efficiency of waste exhaust thermal energy. The present study investigated how to improve the maximum power output of a TEG (Thermoelectric generator) system assisted with a heat pipe. Conventionally, the driving energy efficiency of an internal combustion engine is approximately less than 35%. TEG with Seebeck elements is a new idea for recycling waste exhaust heat energy. The TEG system can efficiently utilize low temperature waste heat, such as industrial waste heat and solar energy. In addition, the heat pipe can transfer heat from the automobile's exhaust gas to a TEG. To improve the efficiency of the thermal power generation system with a heat pipe, effects of various parameters, such as inclination angle, charged amount of the heat pipe, condenser temperature, and size of the TEM (thermoelectric element), were investigated. Experimental studies, CFD simulation, and the theoretical approach to thermoelectric modules were carried out, and the TEG system with heat pipe (15-20% charged, 20°-30° inclined configuration) showed the best performance.

  12. 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).

  13. 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-...

  14. Heat pipe applications for the space shuttle.

    Science.gov (United States)

    Tawil, M.; Alario, J.; Prager, R.; Bullock, R.

    1972-01-01

    Discussion of six specific applications for heat pipe (HP) devices on the space shuttle. These applications were chosen from 27 concepts formulated as part of a study to evaluate the potential benefits associated with HP use. The formulation process is briefly described along with the applications which evolved. The bulk of the discussion deals with the 'top' six - namely, HP radiators for waste heat rejection, an HP augmented cold rail, an HP circuit for electronic equipment cooling, modular heat sink for control of remote packages, an HP temperature control for compartments, and air-cooled equipment racks. The philosophy, physical design details, and performance data are presented for each concept along with a comparison with the baseline design where applicable.

  15. Modelling and performance of heat pipes with long evaporator sections

    Science.gov (United States)

    Wits, Wessel W.; te Riele, Gert Jan

    2017-11-01

    This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling through a fan-based heat sink. Successful heat pipe operation and experimental performances are determined for seven heating configurations, considering active bottom, middle and top sections, and four orientation angles (0°, 30°, 60° and 90°). For all heating sections active, the heat pipe oriented vertically in an evaporator-down mode and a power input of 150 W, the overall thermal resistance was 0.014 K/W at a thermal gradient of 2.1 K and an average operating temperature of 50.7 °C. Vertical operation showed best results, as can be expected; horizontally the heat pipe could not be tested up to the power limit and dry-out occurred between 20 and 80 W depending on the heating configuration. Heating configurations without the bottom section active demonstrated a dynamic start-up effect, caused by heat conduction towards the liquid pool and thereafter batch-wise introducing the working fluid into the two-phase cycle. By analysing the heat pipe limitations for the intended operating conditions, a suitable heat pipe geometry was chosen. To predict the thermal performance a thermal model using a resistance network was created. The model compares well with the measurement data, especially for higher input powers. Finally, the thermal model is used for the design of a 1 kW planar system-level electronics cooling infrastructure featuring six 1 m heat pipes in parallel having a long ( 75%) evaporator section.

  16. 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...

  17. 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.

  18. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Numerical and Experimental Investigations of a Rotating Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Todd A. [Univ. of New Mexico, Albuquerque, NM (United States)

    2007-05-01

    Rotating and revolving heat pipes have been used in a variety of applications including heat pipe heat exchangers, cooling of rotating electrical machines, and heat removal in high speed cutting operations. The use of heat pipes in rotating environments has prompted many analytical, numerical, and experimental investigations of the heat transfer characteristics of these devices. Past investigations, however, have been restricted to the study of straight heat pipes. In this work, a curved rotating heat pipe is studied numerically and experimentally. In certain types of rotating machines, heat generating components, which must be cooled during normal operation, are located at some radial distance from the axis of rotation. The bent heat pipe studied here is shown to have advantages when compared to the conventional straight heat pipes in these off-axis cooling scenarios. The heat pipe studied here is built so that both the condenser and evaporator sections are parallel to the axis of rotation. The condenser section is concentric with the axis of rotation while the evaporator section can be placed in contact with off-axis heat sources in the rotating machine. The geometry is achieved by incorporating an S-shaped curve between the on-axis rotating condenser section and the off-axis revolving evaporator section. Furthermore, the heat pipe uses an annular gap wick structure. Incorporating an annular gap wick structure into the heat pipe allows for operation in a non-rotating environment. A numerical model of this rotating heat pipe is developed. The analysis is based on a two-dimensional finite-difference model of the liquid flow coupled to a one-dimensional model of the vapor flow. Although the numerical model incorporates many significant aspects of the fluid flow, the flow in the actual heat pipe is expected to be threedimensional. The rotating heat pipe with the S-shaped curve is also studied experimentally to determine how well the numerical model captures the key

  1. 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.

  2. Laminar Flow Processes of Fluid Energy Carries in Pipe Lines

    Directory of Open Access Journals (Sweden)

    R. I. Еsman

    2012-01-01

    Full Text Available The paper proposes methodology for analysis and calculation of laminar fluid flows in pipes and channels.  Various regimes of fluid motion in pipelines of heat-power units and equipment are considered in the paper.The presented dependencies can be used for practical calculations while transporting energy carriers for various application.

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Zainal Nurul Amira

    2017-01-01

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

  5. Optimal Design of Piping Systems for District Heating,

    Science.gov (United States)

    1995-08-01

    First, a method for determining the optimal size for a single pipe segment in a district heating system is developed. The method is general enough to...excessive throttling losses in the consumer’s control valves. The method developed here should be feasible for designing the piping networks for district ... heating systems of moderate size, and its major advantage is its flexibility. (MM)

  6. Water-filled heat pipe useful at moderate temperatures

    Science.gov (United States)

    Mc Kinney, B. G.

    1970-01-01

    Heat pipe is used in the primary heat exchanger for nuclear power plants, as a heat sink for high-power electronic devices, and in a closed-cycle heat rejection mechanism for cryogenic storage tanks. It serves simultaneously as a heat transfer device and as a structural member.

  7. Simulation of Hybrid Photovoltaic Solar Assisted Loop Heat Pipe/Heat Pump System

    Directory of Open Access Journals (Sweden)

    Nannan Dai

    2017-02-01

    Full Text Available A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP mode and heat pump (HP mode, and the two modes can be run separately or compositely according to the weather conditions. The performances of independent heat pump (HP mode and hybrid loop heat pipe/heat pump (LHP/HP mode were simulated and compared. Simulation results showed that on typical sunny days in spring or autumn, using LHP/HP mode could save 40.6% power consumption than HP mode. In addition, the optimal switchover from LHP mode to HP mode was analyzed in different weather conditions for energy saving and the all-year round operating performances of the system were also simulated. The simulation results showed that hybrid LHP/HP mode should be utilized to save electricity on sunny days from March to November and the system can rely on LHP mode alone without any power consumption in July and August. When solar radiation and ambient temperature are low in winter, HP mode should be used

  8. Low Cost High Performance Generator Technology Program. Volume 5. Heat pipe topical, appendices

    Energy Technology Data Exchange (ETDEWEB)

    1975-07-01

    Work performed by Dynatherm Corporation for Teledyne Isotopes during a program entitled ''Heat Pipe Fabrication, Associated Technical Support and Reporting'' is reported. The program was initiated on November 29, 1972; the main objectives were accomplished with the delivery of the heat pipes for the HPG. Life testing of selected heat pipe specimens is continuing to and beyond the present date. The program consisted of the following tasks: Heat Pipe Development of Process Definition; Prototype Heat Pipes for Fin Segment Test; HPG Heat Pipe Fabrication and Testing; Controlled Heat Pipe Life Test; and Heat Pipe Film Coefficient Determination. (TFD)

  9. Heat Transfer of Mesh-wick Heat-pipes : Bottom Heat Mode

    OpenAIRE

    IKEDA, Yoshio; ONUMA, Sadayuki

    1988-01-01

    A heat-pipe in which the working fluid circulates by gravity need not contain a wick. this type of heat pipe can be examined as a thermo-siphon. For better moistening inside the evaporating zone and improvement of the limit of flooding or entrainment, wicks of groove type are often used. In the present study, the performance of the metal wick of the copper-ethanol heat-pipe is examined by investigating the effect of inclination angle and volume of enclosed fluid on thermal resistance. In mode...

  10. Theoretical analysis to investigate thermal performance of co-axial heat pipe solar collector

    Science.gov (United States)

    Azad, E.

    2011-12-01

    The thermal performance of co-axial heat pipe solar collector which consist of a collector 15 co-axial heat pipes surrounded by a transparent envelope and which heat a fluid flowing through the condenser tubes have been predicted using heat transfer analytical methods. The analysis considers conductive and convective losses and energy transferred to a fluid flowing through the collector condenser tubes. The thermal performances of co-axial heat pipe solar collector is developed and are used to determine the collector efficiency, which is defined as the ratio of heat taken from the water flowing in the condenser tube and the solar radiation striking the collector absorber. The theoretical water outlet temperature and efficiency are compared with experimental results and it shows good agreement between them. The main advantage of this collector is that inclination of collector does not have influence on performance of co-axial heat pipe solar collector therefore it can be positioned at any angle from horizontal to vertical. In high building where the roof area is not enough the co-axial heat pipe solar collectors can be installed on the roof as well as wall of the building. The other advantage is each heat pipe can be topologically disconnected from the manifold.

  11. Analysis of frozen startup of high-temperature heat pipes and three-dimensional modeling of block-heated heat pipes

    Science.gov (United States)

    Faghri, Amir

    1991-11-01

    The use of high-temperature heat pipes has been proposed for cooling the leading edges and nose cones of re-entry vehicles, rail guns, and laser mirrors, as well as for the thermal management of future hypersonic vehicle structures. The startup behavior of high temperature heat pipes from the frozen state was investigated both numerically and experimentally for various heat loads and input locations. A high temperature sodium/stainless steel heat pipe with multiple heat sources and sinks was fabricated, processed, and tested. A numerical simulation of the transient heat pipe performance including the vapor region, wick structure, and the heat pipe wall is given. Furthermore, experimental and numerical analyses of several operating parameters of a low-temperature copper-water heat pipe under uniform circumferential heating and block heating has been performed. Finally, a numerical analysis of transient heat pipe performance including nonconventional heat pipes with nonuniform heat distributions is presented. Numerical calculations were then made for a leading edge heat pipe with localized high heat fluxes.

  12. High Energy Vibration for Gas Piping

    Science.gov (United States)

    Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

    2017-07-01

    In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

  13. 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.

  14. 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.

  15. 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.

  16. Characterization and potential of nonmetallic piping systems for district heating

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.H.; Karnitz, M.A.; Naus, D.J.; Bryson, J.W. Jr.

    1987-07-01

    The objectives of this investigation were to characterize and evaluate the potential of nonmetallic piping systems for district heating applications. This investigation considered both currently available products and future products. Analyses of the cost components of district heating systems were performed for current steel heating piping technology. A comparison was then made with hypothetical nonmetallic piping technology, and opportunities where savings might occur were noted. As a result of these analyses, a conceptual design for a preinsulated, nonmetallic piping was developed to take advantage of likely areas of overall cost reduction. This design based on low-cost field fabrication and existing materials, used a postchlorinated polyvinylchloride carrier pipe supported structurally by high-density urethane foam and polyethylene jacketing. A structural analysis of this conceptual design was performed using two-dimensional, finite elements. The results are promising for practical operating temperatures.

  17. Heat pipe radiation cooling of advanced hypersonic propulsion system components

    Science.gov (United States)

    Martin, R. A.; Keddy, M.; Merrigan, M. A.; Silverstein, C. C.

    1991-01-01

    Heat transfer, heat pipe, and system studies were performed to assess the newly proposed heat pipe radiation cooling (HPRC) concept. With an HPRC system, heat is removed from the ramburner and nozzle of a hypersonic aircraft engine by a surrounding, high-temperature, heat pipe nacelle structure, transported to nearby external surfaces, and rejected to the environment by thermal radiation. With HPRC, the Mach number range available for using hydrocarbon fuels for aircraft operation extends into the Mach 4 to Mach 6 range, up from the current limit of about Mach 4. Heat transfer studies using a newly developed HPRC computer code determine cooling system and ramburner and nozzle temperatures, heat loads, and weights for a representative combined-cycle engine cruising at Mach 5 at 80,000 ft altitude. Heat pipe heat transport calculations, using the Los Alamos code HTPIPE, reveal that adequate heat trasport capability is available using molybdenum-lithium heat pipe technology. Results show that the HPRC system radiator area is limited in size to the ramburner-nozzle region of the engine nacelle; reasonable system weights are expected; hot section temperatures are consistent with advanced structural materials development goals; and system impact on engine performance is minimal.

  18. Multiphase numerical analysis of heat pipe with different working fluids for solar applications

    Science.gov (United States)

    Aswath, S.; Netaji Naidu, V. H.; Padmanathan, P.; Raja Sekhar, Y.

    2017-11-01

    Energy crisis is a prognosis predicted in many cases with the indiscriminate encroachment of conventional energy sources for applications on a massive scale. This prediction, further emboldened by the marked surge in global average temperatures, attributed to climate change and global warming, the necessity to conserve the environment and explore alternate sources of energy is at an all-time high. Despite being among the lead candidates for such sources, solar energy is utilized far from its vast potential possibilities due to predominant economic constraints. Even while there is a growing need for solar panels at more affordable rates, the other options to harness better out of sun’s energy is to optimize and improvise existing technology. One such technology is the heat pipe used in Evacuated Tube Collectors (ETC). The applications of heat pipe have been gaining momentum in various fields since its inception and substantial volumes of research have explored optimizing and improving the technology which is proving effective in heat recovery and heat transfer better than conventional systems. This paper carries out a computational analysis on a comparative simulation between two working fluids within heat pipe of same geometry. It further endeavors to study the multiphase transitions within the heat pipe. The work is carried out using ANSYS Fluent with inputs taken from solar data for the location of Vellore, Tamil Nadu. A wickless, gravity-assisted heat pipe (GAHP) is taken for the simulation. Water and ammonia are used as the working fluids for comparative multiphase analysis to arrive at the difference in heat transfer at the condenser section. It is demonstrated that a heat pipe ETC with ammonia as working fluid showed higher heat exchange (temperature difference) as against that of water as working fluid. The multiphase model taken aided in study of phase transitions within both cases and supported the result of ammonia as fluid being a better candidate.

  19. 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.

  20. Ductile fracture behaviour of primary heat transport piping material ...

    Indian Academy of Sciences (India)

    Design of primary heat transport (PHT) piping of pressurised heavy water reactors (PHWR) has to ensure implementation of leak-before-break concepts. In order to be able to do so, the ductile fracture characteristics of PHT piping material have to be quantified. In this paper, the fracture resistance of SA333, Grade 6 steel ...

  1. Discussion on the solar concentrating thermoelectric generation using micro-channel heat pipe array

    Science.gov (United States)

    Li, Guiqiang; Feng, Wei; Jin, Yi; Chen, Xiao; Ji, Jie

    2017-11-01

    Heat pipe is a high efficient tool in solar energy applications. In this paper, a novel solar concentrating thermoelectric generation using micro-channel heat pipe array (STEG-MCHP) was presented. The flat-plate micro-channel heat pipe array not only has a higher heat transfer performance than the common heat pipe, but also can be placed on the surface of TEG closely, which can further reduce the thermal resistance between the heat pipe and the TEG. A preliminary comparison experiment was also conducted to indicate the advantages of the STEG-MCHP. The optimization based on the model verified by the experiment was demonstrated, and the concentration ratio and selective absorbing coating area were also discussed. In addition, the cost analysis was also performed to compare between the STEG-MCHP and the common solar concentrating TEGs in series. The outcome showed that the solar concentrating thermoelectric generation using micro-channel heat pipe array has the higher electrical efficiency and lower cost, which may provide a suitable way for solar TEG applications.

  2. 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…

  3. Liquid metal micro heat pipes for space radiator applications

    Science.gov (United States)

    Gerner, F. M.; Henderson, H. T.

    1995-07-01

    Micromachining is a chemical means of etching three-dimensional structures, typically in single-crystalline silicon. These techniques are leading toward what is coming to be referred to as MEMS (micro electro mechanical systems), where in addition to the ordinary two dimensional (planar) microelectronics, it is possible to build three-dimensional micromotors, electrically-actuated microvalves, hydraulic systems, and much more on the same microchip. These techniques become possible because of differential etching rates of various crystallographic planes and materials used for semiconductor microfabrication. The University of Cincinnati group in collaboration with NASA Lewis formed micro heat pipes in silicon by the above techniques. Work is ongoing at a modest level, but several essential bonding and packaging techniques have been recently developed. Currently, we have constructed and filled water/silicon micro heat pipes. Preliminary thermal tests of arrays of 125 micro heat pipes etched in a 1 inch x 1 inch x 250 micron silicon wafer have been completed. These pipes are instrumented with extremely small P-N junctions to measure their effective conductivity and their maximum operating power. A relatively simple one-dimensional model has been developed in order to predict micro heat pipes' operating characteristics. This information can be used to optimize micro heat pipe design with respect to length, hydraulic diameter, and number of pipes. Work is progressing on the fabrication of liquid-metal micro heat pipes. In order to be compatible with liquid metal (sodium or potassium), the inside of the micro heat pipes will be coated with a refractory metal (such as tungsten, molybdenum, or titanium).

  4. Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid

    Science.gov (United States)

    Juhasz, Albert J.

    2010-01-01

    This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).

  5. 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...

  6. 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...

  7. 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...

  8. 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)

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

    National Research Council Canada - National Science Library

    Nemec, Patrik; Smitka, Martin; Malcho, Milan

    2014-01-01

    ... of insufficient cooling. In order to maintain appropriate working conditions, waste heat must be removed. One possibility to remove waste heat is to use loop heat pipe (LHP). LHPs are two-phase ...

  10. Heat pipe radiation cooling evaluation: Task 2 concept studies report

    Energy Technology Data Exchange (ETDEWEB)

    Silverstein, C.C.

    1991-10-01

    This report presents the result of Task 2, Concept Studies for Heat Pipe Radiation Cooling (HPRC), which was performed for Los Alamos National Laboratory under Contract 9-XT1-U9567. Studies under a prior contract defined a reference HPRC conceptual design for hypersonic aircraft engines operating at Mach 5 and an altitude of 80,000 ft. Task 2 involves the further investigation of heat pipe radiation cooling (HPRC) systems for additional design and operating conditions.

  11. Experimental Investigation of Concrete Runway Snow Melting Utilizing Heat Pipe Technology

    Directory of Open Access Journals (Sweden)

    Fengchen Chen

    2018-01-01

    Full Text Available A full scale snow melting system with heat pipe technology is built in this work, which avoids the negative effects on concrete structure and environment caused by traditional deicing chemicals. The snow melting, ice-freezing performance and temperature distribution characteristics of heat pipe concrete runway were discussed by the outdoor experiments. The results show that the temperature of the concrete pavement is greatly improved with the heat pipe system. The environment temperature and embedded depth of heat pipe play a dominant role among the decision variables of the snow melting system. Heat pipe snow melting pavement melts the snow completely and avoids freezing at any time when the environment temperature is below freezing point, which is secure enough for planes take-off and landing. Besides, the exportation and recovery of geothermal energy indicate that this system can run for a long time. This paper will be useful for the design and application of the heat pipe used in the runway snow melting.

  12. Transient characteristics of a grooved water heat pipe with variable heat load

    Science.gov (United States)

    Jang, Jong Hoon

    1990-01-01

    The transient characteristics of a grooved water heat pipe were studied by using variable heat load. First, the effects of the property variations of the working fluid with temperature were investigated by operating the water heat pipe at several different temperatures. The experimental results show that, even for the same heat input profile and heat pipe configuration, the heat pipe transports more heat at higher temperature within the tested temperature range. Adequate liquid return to the evaporator due to decreasing viscosity of the working fluid permits continuous vaporization of water without dry-out. Second, rewetting of the evaporator was studied after the evaporator had experienced dry-out. To rewet the evaporator, the elevation of the condenser end was the most effective way. Without elevating the condenser end, rewetting is not straight-forward even with power turned off unless the heat pipe is kept at isothermal condition for sufficiently long time.

  13. A simple method for removing leakage of metal pipes, like district heating and NG pipes

    Energy Technology Data Exchange (ETDEWEB)

    Tabatabaeeghomi, Mohammad; Mahmoudi, Jafar (Maelardalen Univ., Vaesteraas (Sweden)). E-mail: Jafar.Mahmoudi@mdh.se; Liaghat, Gholamhossien (Tarbiat Modaress Univ., Tehran (Iran))

    2009-07-01

    Explosive welding occur under high velocity oblique impact, though it is possible to use explosive energy to form a usual cold pressure weld. One of the advantages of this method is welding kind of materials with different shapes together. The ability of explosive welding can be used to maintenance of pipes and vessels, preventing pipe leakage especially under water in oil and gas industries. This research suggests a simple explosive welding method for removing the leakage of metal pipes that is very economy and easy for repairing pipes and vessels full of water or liquid

  14. Monogroove heat pipe design: Insulated liquid channel with bridging wick

    Science.gov (United States)

    Alario, J. P.; Brown, R. F.; Kosson, R. L.

    1985-05-01

    A screen mesh artery supported concentrically within the evaporator section of a heat pipe liquid channel retains liquid in the channel. Continued and uniform liquid feed to the heat pipe evaporation section (20) during periods of excessive heat transfer is assured. The overall design provides high evaporation and condensation film coefficients for the working fluid by means of the circumferential grooves in the walls of the vapor channel, while not interfering with the overall heat transport capability of the axial groove. The design has particular utility in zero-g environments.

  15. Monogroove heat pipe development for the space constructible radiator system

    Science.gov (United States)

    Alario, J.; Brown, R.; Kosson, R.

    1983-06-01

    A high-capacity, high-reliability space radiator is needed in order to satisfy the future heat rejection requirements of large space platforms or space stations. The Space Constructible Radiator (SCR) system is being developed to fill this need. The most important component of the SCR system is the high-capacity monogroove heat pipe which theoretically has a heat transport capacity of 12,700 W-m to 25,400 W-m. This performance represents a better than two order of magnitude increase in transport capacity over currently existing heat pipes. The present investigation is concerned with testing developments which occurred in connection with the monogroove heat pipe during the last two years. A short description of the SCR system is presented, and results are provided for two series of tests which were run on a 15.7-m long heat pipe. The first test series included both performance and diagnostic tests, which pointed to some design modifications which were necessary. The second test series, run on the modified heat pipe, showed improved performance.

  16. Heat pipes for terrestrial applications in dehumidification systems

    Science.gov (United States)

    Khattar, Mukesh K.

    1988-01-01

    A novel application of heat pipes which greatly enhances dehumidification performance of air-conditioning systems is presented. When an air-to-air heat pipe heat exchanger is placed between the warm return air and cold supply air streams of an air conditioner, heat is efficiently transferred from the return air to the supply air. As the warm return air precools during this process, it moves closer to its dew-point temperature. Therefore, the cooling system works less to remove moisture. This paper discusses the concept, its benefits, the challenges of incorporating heat pipes in an air-conditioning system, and the preliminary results from a field demonstration of an industrial application.

  17. Building, Testing, and Post Test Analysis of Durability Heat Pipe Number 6

    Science.gov (United States)

    Moss, T. A.

    2002-03-01

    The Solar Thermal Program at Sandia supports work developing dish/Stirling systems to convert solar energy into electricity. Heat pipe technology is ideal for transferring the energy of concentrated sunlight from the parabolic dish concentrators to the Stirling engine heat tubes. This report covers the building, testing, and post-test analysis of the sixth in a series of bench scale heat pipes. Durability heat pipe no. 6 was built and tested to determine the effects of a high temperature bakeout, 950 C, on wick corrosion during long-term operation. Previous tests showed high levels of corrosion with low temperature bakeouts (650-700 C). Durability heat pipe no. 5 had a high temperature bakeout and reflux cleaning and showed low levels of wick corrosion after long-term operation. After testing durability heat pipe no. 6 for 5,003 hours at an operating temperature of 750 C, it showed low levels of wick corrosion. This test shows a high temperature bakeout alone will significantly reduce wick corrosion without the need for costly and time consuming reflux cleaning.

  18. Research on thermal characteristics of heat pipes for led lightning devices

    Directory of Open Access Journals (Sweden)

    Lozovoi M. A.

    2014-12-01

    Full Text Available New energy-saving technologies for lighting is a promising trend in lighting technology. To this end, during the recent decade, have been actively developed and implemented lighting units based on LED modules. Reliability of such devices is largely dependent on the ensuring of cooling of the LEDs. Heat pipes are being used with ever increasing frequency for increasing an efficiency of cooling of powerful LEDs within a lightening device. Results of experimental modeling of thermal characteristics of two aluminum heat pipes with grooved capillary structure and ammonia used as a heat transfer agent, designed for application as a heat transfer elements in designs of powerful LED lightening device with forced air cooling are presented in this paper. It is shown that for the heat flux range of 50 to 100 W and for incident flow speed in the range of 0.8 to 2.1 m/s the temperature in the heating zone of the heat pipe falls into the range of 31.0 to 52.5 °C. In this case the temperature difference along the heat pipe is between 0.9…1.7 °C, when a minimal value of the fed heat flux is 50 W, and 1.7…3.1°C, when a maximum value of the heat flux is 100 W. The value of heat transfer resistance of the heat pipes was in the range of 0.012 to 0.044 °C/W. The key factors influencing the thermal characteristics of the heat pipes are: the value of the fed heat flux, the speed of cooling air flux, heat pipe inclination angle with respect to the horizon. By using five such heat pipes within the powerful LED lightning device it is possible to achieve an elimination of the total heat flux from LED modules up to 500 W. At an efficiency factor of LEDs of about 75% this is equivalent to intake power 665 W. Taking into account that luminous efficiency of modern LEDs is about 10 times as high as those of incandescent lamps, proposed lightning device will produce a luminous flux which is equivalent to the luminous flux of a lightening device with incandescent lamps

  19. 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

  20. Optimum charge of working fluids in horizontal rotating heat pipes

    Science.gov (United States)

    Nakayama, W.; Ohtsuka, Y.; Itoh, H.; Yoshikawa, T.

    The performance of wickless straight heat pipes rotating about their horizontal axes was investigated. The data reported herein were obtained with the copper pipes of 28 and 37 mm ID, 480 mm long with the evaporator and condenser sections each 170 mm long, and distilled water as the working fluid. The transition of two-phase flow in the heat pipe from the stratified to the annular structure occurs at a certain rotational speed (Froude number), and this affects the heat transfer performance. The volumetric percentage of liquid phase in the heat pipe (volumetric charge) determines the transition Froude numbers. For a given Froude number and a heat load, a too lean volumetric charge invites dry-out of the evaporator wall. A too high volumetric charge reduces the area for thin film evaporation and condensation on the rotating wall which dips and leaves the liquid reservoir of the stratified fluid. In the range of Froude numbers less than 13 which include many cases of heat pipe applications to conventional rotating machines, the volumetric charge of 10-14 percent minimizes the wall temperature difference between the evaporator and the condenser.

  1. Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Matthew (DOE/NNSA Kansas City Plant (United States)); Weyant, J.; Garner, S. (Advanced Cooling Technologies, Inc. (Lancaster, PA (United States)); Occhionero, M. (CPS Technologies Corporation, Norton, MA (United States))

    2010-01-07

    Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate’s effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

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

    Science.gov (United States)

    Lin, Qinglong; Ma, Jinghui; Shi, Lei

    2017-08-01

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

  3. 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....

  4. The Exergetic, Environmental and Economic Effect of the Hydrostatic Design Static Pressure Level on the Pipe Dimensions of Low-Energy District Heating Networks

    Directory of Open Access Journals (Sweden)

    Hakan İbrahim Tol

    2013-01-01

    Full Text Available Low-Energy District Heating (DH systems, providing great energy savings by means of very low operating temperatures of 55 °C and 25 °C for supply and return respectively, were considered to be the 4th generation of the DH systems for a low-energy future. Low-temperature operation is considered to be used in a low-energy DH network to carry the heat produced by renewable and/or low grade energy sources to low-energy Danish buildings. In this study, a comparison of various design considerations with different levels of maximum design static pressures was performed, and their results evaluated in terms of energetic, exergetic, economic, and environmental perspectives.

  5. 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

  6. 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...

  7. Heat and mass transfer analysis in unsaturated ground soils around the buried heating pipe

    National Research Council Canada - National Science Library

    JAHANGIR, Mohammad Hossein

    2015-01-01

    .... the pipe-soil interface. Thus, the model takes into account coupled heat and moisture transfer in the unsaturated soil, allowing for more accurate predictions of the soil thermal response to the heat fluxes induced...

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

    Science.gov (United States)

    League, Mark; Alario, Joe

    1988-05-01

    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.

  9. Analysis of Effect of Heat Pipe Parameters in Minimising the Entropy Generation Rate

    OpenAIRE

    Rakesh Hari; Chandrasekharan Muraleedharan

    2016-01-01

    Heat transfer and fluid flow in the heat pipe system result in thermodynamic irreversibility generating entropy. The minimum entropy generation principle can be used for optimum design of flat heat pipe. The objective of the present work is to minimise the total entropy generation rate as the objective function with different parameters of the flat heat pipe subjected to some constraints. These constraints constitute the limitations on the heat transport capacity of the heat pipe. This physic...

  10. 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.

  11. Radiative heat transfer estimation in pipes with various wall emissivities

    Science.gov (United States)

    Robin, Langebach; Christoph, Haberstroh

    2017-02-01

    Radiative heat transfer is usually of substantial importance in cryogenics when systems are designed and thermal budgeting is carried out. However, the contribution of pipes is commonly assumed to be comparably low since the warm and cold ends as well as their cross section are fairly small. Nevertheless, for a first assessment of each pipe rough estimates are always appreciated. In order to estimate the radiative heat transfer with traditional “paper and pencil“ methods there is only one analytical case available in literature - the case of plane-parallel plates. This case can only be used to calculate the theoretical lower and the upper asymptotic values of the radiative heat transfer, since pipe wall radiation properties are not taken into account. For this paper we investigated the radiative heat transfer estimation in pipes with various wall emissivities with the help of numerical simulations. Out of a number of calculation series we could gain an empirical extension for the used approach of plane-parallel plates. The model equation can be used to carry out enhanced paper and pencil estimations for the radiative heat transfer through pipes without demanding numerical simulations.

  12. Evaluation of heat transfer characteristics of a sphere-packed pipe for Flibe blanket

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Atsushi, E-mail: awata@karma.qse.tohoku.ac.jp [Tohoku University, Sendai (Japan); Ebara, Shinji [Tohoku University, Sendai (Japan); Sagara, Akio [National Institute for Fusion Science, Toki (Japan); Hashizume, Hidetoshi [Tohoku University, Sendai (Japan)

    2013-10-15

    A Flibe blanket has been proposed to be used in FFHR. Since Flibe has poor heat transfer performance, heat transfer promoter is required, and a sphere-packed pipe (SPP) has been proposed to enhance the heat transfer performance in the Flibe blanket. In this paper, the fluid flow and heat transfer characteristics in the SPP is evaluated numerically using a k–ε turbulent model for the flow field and an algebraic model for the thermal field. As a result, it was shown that bypass flows in the SPP play a significant role in heat transfer. Also it is thought that the turbulent energy can strongly affect heat transfer performance.

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

    Directory of Open Access Journals (Sweden)

    Knyazev Vladimir

    2017-01-01

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

  14. Development of a high capacity variable conductance heat pipe.

    Science.gov (United States)

    Kosson, R.; Hembach, R.; Edelstein, F.; Loose, J.

    1973-01-01

    The high-capacity, pressure-primed, tunnel-artery wick concept was used in a gas-controlled variable conductance heat pipe. A variety of techniques were employed to control the size of gas/vapor bubbles trapped within the artery. Successful operation was attained with a nominal 6-foot long, 1-inch diameter cold reservoir VCHP using ammonia working fluid and nitrogen control gas. The pipe contained a heat exchanger to subcool the liquid in the artery. Maximum transport capacity with a 46-inch effective length was 1200 watts level (more than 50,000 watt-inches) and 800 watts at 0.5-inch adverse tilt.

  15. Water pipe network as a heat source for heat pump integrated into a district heating

    Science.gov (United States)

    Jadwiszczak, Piotr; Niemierka, Elżbieta

    2017-11-01

    The paper will present a technical analysis of the performance of the Heat Pumps (HP) installed in the domestic water pipe network for a big city scale. The HP integration scheme predicts the domestic water flow as a heat source and the district heating as a heat sink. The technical factors which influence on the estimated thermal power and performance of HP unit will be identified. Additionally, the pros and cons of HP operation in water intake will be determined. The analysis will be based on long-term measurement data from Głogów city.

  16. Water pipe network as a heat source for heat pump integrated into a district heating

    Directory of Open Access Journals (Sweden)

    Jadwiszczak Piotr

    2017-01-01

    Full Text Available The paper will present a technical analysis of the performance of the Heat Pumps (HP installed in the domestic water pipe network for a big city scale. The HP integration scheme predicts the domestic water flow as a heat source and the district heating as a heat sink. The technical factors which influence on the estimated thermal power and performance of HP unit will be identified. Additionally, the pros and cons of HP operation in water intake will be determined. The analysis will be based on long-term measurement data from Głogów city.

  17. 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.

    1993-01-01

    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.

  18. Heat and Mass Transfer in a Pipe with Moving Surface: Effects of ...

    African Journals Online (AJOL)

    appropriate to simulate wind tunnel tests on lubrication phenomenon in engineering systems. Mathematics Subject Classification (1991): 76Z05, 76E25 Keywords: pipe flow, moving surface, viscosity variation;, heat and material flux, energy dissipation, physiological flows, magnetohydrodynamic and electrohydrodynamic ...

  19. Baseline experimental investigation of an electrohydrodynamically assisted heat pipe

    Science.gov (United States)

    Duncan, A. B.

    1995-07-01

    The increases in power demand and associated thermal management requirements of future space programs such as potential Lunar/Mars missions will require enhancing the operating efficiencies of thermal management devices. Currently, the use of electrohydrodynamically (EHD) assisted thermal control devices is under consideration as a potential method of increasing thermal management system capacity. The objectives of the currently described investigation included completing build-up of the EHD-Assisted Heat Pipe Test bed, developing test procedures for an experimental evaluation of the unassisted heat pipe, developing an analytical model capable of predicting the performance limits of the unassisted heat pipe, and obtaining experimental data which would define the performance characteristics of the unassisted heat pipe. The information obtained in the currently proposed study will be used in order to provide extensive comparisons with the EHD-assisted performance observations to be obtained during the continuing investigation of EHD-Assisted heat transfer devices. Through comparisons of the baseline test bed data and the EHD assisted test bed data, accurate insight into the performance enhancing characteristics of EHD augmentation may be obtained. This may lead to optimization, development, and implementation of EHD technology for future space programs.

  20. Progress of cryogenic pulsating heat pipes at UW-Madison

    Science.gov (United States)

    Diego Fonseca, Luis; Mok, Mason; Pfotenhauer, John; Miller, Franklin

    2017-12-01

    Space agencies continuously require innovative cooling systems that are lightweight, low powered, physically flexible, easily manufactured and, most importantly, exhibit high heat transfer rates. Therefore, Pulsating Heat Pipes (PHPs) are being investigated to provide these requirements. This paper summarizes the current development of cryogenic Pulsating Heat Pipes with single and multiple evaporator sections built and successfully tested at UW-Madison. Recently, a helium based Pulsating Heat Pipe with three evaporator and three condenser sections has been operated at fill ratios between 20 % and 80 % operating temperature range of 2.9 K to 5.19 K, resulting in a maximum effective thermal conductivity up to 50,000 W/m-K. In addition, a nitrogen Pulsating Heat Pipe has been built with three evaporator sections and one condenser section. This PHP achieved a thermal performance between 32,000 W/m-K and 96,000 W/m-K at fill ratio ranging from 50 % to 80 %. Split evaporator sections are very important in order to spread cooling throughout an object of interest with an irregular temperature distribution or where multiple cooling locations are required. Hence this type of configurations is a proof of concept which hasn’t been attempted before and if matured could be applied to cryo-propellant tanks, superconducting magnets and photon detectors.

  1. The influence of longitudinal vibrations on the heat transfer performance of inclined heat pipes

    Directory of Open Access Journals (Sweden)

    Rong-Horng Chen

    2015-02-01

    Full Text Available This study focused on investigating the influence of longitudinal vibrations, the condensation section temperature, and the inclination angles on the heat transfer performance of grooved cylindrical copper heat pipes with lengths of 600 and 150 mm and an outer diameter of 8 mm. The inclination angles of the tested heat pipes were 0°, ±45°, and ±90°. Longitudinal vibrations with frequencies of 3, 4, 5, 6, and 9 Hz and amplitudes of 2.8, 5, 10, 15, 20, and 25 mm, which resulted in accelerations between 0.1 and 1.01 g, were experimentally tested. The condensation section temperatures were set at 20°C, 30°C, and 40°C. A heating jacket and a cooling sleeve were installed at the evaporation and condensation sections of the test cell to simulate a constant heat flux and a constant temperature boundary, respectively. The results showed that with the heat pipe placed with the condensation section on top and the evaporation section on bottom, a fairly low and constant thermal resistance (approximately 0.25 K/W for the 600-mm heat pipe and 0.75–1.2 K/W for the 150-mm heat pipe was obtained, both with and without heat pipe vibration and regardless of the condensation section temperature.

  2. Novel Thermal Control Concepts Using Micro Heat Pipes - Spacecraft Thermal Control

    National Research Council Canada - National Science Library

    Peterson, G

    2001-01-01

    ...; Flexible polymer heat pipes have been fabricated and modeled; Theses polymer heat pipes offer a greater degree of flexibility and a potentially higher effective thermal conductivity than any previously developed...

  3. 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.

  4. 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.

  5. High-Performance Heat Pipe With Screen Mesh

    Science.gov (United States)

    Alario, J. P.; Brown, R. F.; Kosson, R.

    1986-01-01

    Liquid distributed more evenly in evaporator section. Improved heat pipe contains an artery and wick rolled from stainless-steel screen of 180 mesh (openings about 80 micrometers). Screen material helps to prevent dryout in evaporator section by conducting liquid through hotspots and to vaporchannel wall. Insert reduces incidence of dryout at hotspots or during intervals of general thermal overload.

  6. 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…

  7. Compressible Friction Coefficients in a Simulated Heat Pipe.

    Science.gov (United States)

    1987-12-01

    Second Lieutenant, USAF AFIT/ GAZ /AA/87D-6 1 * .~ DTI 1 COMRESSBLE RICTON CEFFIIETT 4t , DEPARTMENT OF THE AIR FORCEH AIR UNIVERSITY AIR FORCE INSTITUTE OF...generators, ,- 1 04 electronic and electrical equipment, and turbine blades. Heat pipes have also been used for cyrogenic eye surgery, in spacecraft for

  8. Ductile fracture behaviour of primary heat transport piping material ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Introduction. The design of primary heat transport piping (PHT) of nuclear reactors has to ensure that uncontrolled failure does not occur under normal, faulted or ... and unanticipated thermal expansion, and generally reflects an unnecessarily complex design philosophy. Over the years, with the development of a better ...

  9. Using heat pipe to make isotherm condition in catalytic converters of sulfuric acid plants

    Science.gov (United States)

    Yousefi, M.; Pahlavanzadeh, H.; Sadrameli, S. M.

    2017-08-01

    In this study, for the first time, it is tried to construct a pilot reactor, for surveying the possibility of creating isothermal condition in the catalytic convertors where SO2 is converted to SO3 in the sulfuric acid plants by heat pipe. The thermodynamic and thermo-kinetic conditions were considered the same as the sulfuric acid plants converters. Also, influence of SO2 gas flow rate on isothermal condition, has been studied. A thermo-siphon type heat pipe contains the sulfur + 5% iodine as working fluid, was used for disposing the heat of reaction from catalytic bed. Our results show that due to very high energy-efficiency, isothermal and passive heat transfer mechanism of heat pipe, it is possible to reach more than 95% conversion in one isothermal catalytic bed. As the results, heat pipe can be used as a certain piece of equipment to create isothermal condition in catalytic convertors of sulphuric acid plants. With this work a major evaluation in design of sulphuric acid plants can be taken place.

  10. Integral-type solar water heater using loop heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.J.; Yang, P.E.; Wang, J.H.; Wu, J.H. [New Energy Center, Taiwan Univ., Taipei (China)

    2008-07-01

    Taiwan University has been devoted to the development of low-cost LHP (loop hat pipe). A new manufacturing process for low-cost LHP has been developed that leads to a cost down to less than 10 USD for a 100W LHP. The present study utilizes the low-cost LHP to develop a new type of solar water heater. A thermosyphon which is thermally bonded with a solar absorber plate is used to absorb solar energy and transfer the heat upward to the evaporator of the LHP. From that, the heat is conducted downward to the condenser of the LHP which is immersed in a hot water tank beneath the solar collector. The solar water heater thus can be designed in integral type with streamline shape which is easy to install and has a good outlook as well as high efficiency. A prototype was designed and fabricated in the present study. A preliminary heat transfer test for a single unit of thermosyphon-LHP combination shows that it is capable of transferring the absorbed energy downward to the LHP condenser immersed in a hot water tank. The overall thermal resistance from the absorber plate to water is 0.34 C/W. and the thermal resistance of the LHP is 0.16 C/W. Two prototypes of the solar water heaters with 50 liters and 80 liters hot water tanks were designed according to the results of the feasibility test. In addition, an automatic monitoring system was designed and set up for the performance test of these two solar water heaters based on the test standard CNS B7277. The measured overall thermal resistance from solar absorber plate to water is 0.369 C/W. The daily solar water heater efficiency is 0.503. The present study has shown that the application of low-cost LHP in solar water heater is feasible and cost competitive. (orig.)

  11. 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)

  12. Design and demonstration of heat pipe cooling for NASP and evaluation of heating methods at high heating rates

    Energy Technology Data Exchange (ETDEWEB)

    Merrigan, M.A.; Sena, J.T.

    1989-01-01

    An evaluation of two heating methods for demonstration of NASP leading edge heat pipe technology was conducted. The heating methods were and rf induction heated plasma jet and direct rf induction. Tests were conducted to determine coupling from the argon plasma jet on a surface physically similar to a heat pipe. A molybdenum tipped calorimeter was fabricated and installed in an rf induction heated plasma jet for the test. The calorimetric measurements indicated a maximum power coupling of approximately 500 W/cm{sup 2} with the rf plasma jet. The effect of change in gas composition on the heating rate was investigated using helium. An alternative to the plasma heating of a heat pipe tip, an rf concentrator was evaluated for coupling to the hemispherical tip of a heat pipe. A refractory metal heat pipe was designed, fabricated, and tested for the evaluation. The heat pipe was designed for operation at 1400 to 1900 K with power input to 1000 W/cm{sup 2} over a hemispherical nose tip. Power input of 800 W/cm{sup 2} was demonstrated using the rf concentrator. 2 refs., 13 figs.

  13. Aircraft Thermal Management Using Loop Heat Pipes

    Science.gov (United States)

    2009-03-01

    Conversion Engineering Conference. Portsmouth, VA: AIAA, 2003. AIAA 2003- 6082. Incropera , F., DeWitt, D. Fundamentals of Heat and Mass Transfer . New...m/s2 h Heat transfer coefficient, W/(m2-K) H Altitude, m k Thermal conductivity, W/(m-K) L Length, m m Mass , kg Ma Mach number, aU / n Number...Since the mass flow rate was kept constant at cpm& = 0.0077 kg/s, the uncertainty associated with that setting was 4.0%. The heat transferred

  14. 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...

  15. 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.

  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. 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.

  18. 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)

  19. Heat transfer performance of an oscillating heat pipe under ultrasonic field with dual frequency

    Science.gov (United States)

    Fu, B. W.; Zhao, N. N.; Ma, H. B.; Su, F. M.

    2015-01-01

    The oscillating motion and heat transfer capacity in an oscillating heat pipe (OHP) under the effect of ultrasound was investigated experimentally. Using the electrically- controlled piezoelectric ceramics, the ultrasonic sound was applied to the evaporating section of the OHP. The heat pipe was tested with or without the ultrasonic sound. The effect of ultrasound on the heat transfer performance was conducted with ultrasound of single frequency or dual frequency. The experimental results demonstrate that the OHP under the effect of the ultrasonic sound with dual frequency performs better than that one with single frequency.

  20. The share flight experiment - An advanced heat pipe radiator for Space Station

    Science.gov (United States)

    Alario, J. P.; Otterstedt, P. J.

    1986-01-01

    This paper reports on the design and thermal vacuum certification testing of the Space Station Heat Pipe Advanced Radiator Element (SHARE) Shuttle flight experiment, with primary emphasis on the heat pipe radiator system. The main objective of the SHARE experiment is to demonstrate suitable 0 g heat transfer performance of a 50 ft-long high-capacity monogroove heat pipe radiator element being developed for possible Space Station application. All of the flight certification tests were achieved, including a maximum heat rejection of 2 kW and thawing of a frozen heat pipe; and uninterrupted operation under cycling environmental and evaporator heat loads.

  1. Design and Testing of Metal and Silicon Heat Spreaders with Embedded Micromachined Heat Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Benson, D.A.; Robino, C.V.

    1999-02-22

    The authors have developed a new type of heat spreader based on the integration of heat pipes directly within a thin planar structure suitable for use as a heat spreader or as the base layer in a substrate. The process uses micromachining methods to produce micron scale patterns that act as a wick in these small scale heat pipes. By using silicon or a low expansion metal as the wall material of these spreaders, they achieve a good match to the thermal coefficient of expansion of the die. The match allows the use of a thin high performance die attachment even on large size die. The embedded heat pipes result in high effective thermal conductivity for the new spreader technology.

  2. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

    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.

  4. 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.

  5. 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

  6. Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs flow performance

    Directory of Open Access Journals (Sweden)

    Amanowicz Łukasz

    2017-01-01

    Full Text Available In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ε realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

  7. Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs) flow performance

    Science.gov (United States)

    Amanowicz, Łukasz; Wojtkowiak, Janusz

    2017-11-01

    In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs) were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ɛ realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning) for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

  8. A design method of axially grooved heat pipes embedded in equipment panel for communication satellite

    Science.gov (United States)

    Miyasaka, Akihiro; Nakajima, Katsuhiko

    A calculation method of the maximum heat load for an axially grooved heat pipe which is embedded in a honeycomb sandwich panel with multipoint heating is developed by considering the estimation of heat flux rate along the heat pipe. A thermal mathematical model for the panel is also used to estimate the net heat input to the heat pipe. The maximum heat loads predicted for the heat pipe embedded in the panel show good agreement with the data obtained from tests which has been performed in a vacuum chamber. A minimum weight design method for rectangular grooved heat pipes which satisfied heat transport capabilities required are also proposed as a result of this study.

  9. 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 max......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...

  10. 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.

  11. 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.

  12. Simulation and experimental validation of a 400 m vertical CO2 heat pipe for geothermal application

    Science.gov (United States)

    Ebeling, Johann-Christoph; Kabelac, Stephan; Luckmann, Sebastian; Kruse, Horst

    2017-11-01

    Geothermal heat pipes are an effective heat source for heat pumps used for space heating. Because the area for the installation of borehole heat exchangers is limited in urban areas (one site per borehole), the maximum heat extractable from one borehole shall rise. In cooperation with the FKW Hannover, the Institute for Thermodynamics of the Leibniz University of Hannover is investigating the thermodynamic behavior of CO2 driven geothermal heat pipes of higher thermal power. Therefore two different types of geothermal heat pipes with a length of 400 m each have been installed. Furthermore a numerical simulation of the heat and mass transfer within the pipes is under development. The experimental setup and first results of the experiments are presented as well as the current status of the numerical simulation. A comparison of the two different types of heat pipes and a comparison of the experimental data with the numerical simulation is given.

  13. 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...

  14. Characterisation of a grooved heat pipe with an anodised surface

    Science.gov (United States)

    Solomon, A. Brusly; Ram Kumar, A. M.; Ramachandran, K.; Pillai, B. C.; Senthil Kumar, C.; Sharifpur, Mohsen; Meyer, Josua P.

    2017-03-01

    A grooved heat pipe (GHP) is an important device for managing heat in space applications such as satellites and space stations, as it works efficiently in the absence of gravity. Apart from the above application, axial GHPs are used in many applications, such as electronic cooling units for temperature control and permafrost cooling. Improving the performance of GHPs is essential for better cooling and thermal management. In the present study, the effect of anodization on the heat transfer characteristics of a GHP is studied with R600a as a working fluid. In addition, the effects of fill ratio, inclination angle and heat inputs on the heat transfer performance of a GHP are studied. Furthermore, the effect of heat flux on dimensional numbers, such as the Webber, Bond, Kutateladze and condensation numbers, are studied. The inclination angle, heat input and fill ratio of GHPs are varied in the range of 0°-90°, 25-250 W and 10-70 % respectively. It is found that the above parameters have a significant effect on the performance of a GHP. Due to the anodisation, the maximum enhancement in heat transfer coefficient at the evaporator is 39 % for a 90° inclination at a heat flux of 11 kW/m2. The reported performance enhancement of a GHP may be due to the large numbers of nucleation sites created by the anodisation process and enhancement in the capillary force due to the coating.

  15. Thermal performance of a selected heat pipe at different tilt angles

    Science.gov (United States)

    Raghuram, Jasti; Phani Kumar, K. V. N. K.; Khiran, G. V.; Snehith, K.; Bhanu Prakash, S.

    2017-08-01

    An attempt is made to design, fabricate and test a copper heat pipe with 12 mm diameter, 300mm length and thickness of 1mm with a heat input of 7.29W. Experiments were conducted with and without working fluid for different inclinations to assess the thermal performance of heat pipe. The working fluids chosen for the study are acetone and distilled water and are compared. The thermal performance of the heat pipe was quantified in terms of thermal resistance and overall heat transfer coefficient by measuring temperature distribution across the heat pipe. The heat pipe was aligned for different inclinations and an optimum tilt angle was found experimentally, validated the same with simulation result obtained by computational fluid dynamics analysis and also with a reference paper. The copper heat pipe is found to be effective when acetone is used as working fluid. The optimum inclination angle of heat pipe for maximum rate of heat transfer is found to be 60° for both the working fluids tested. Even the cost of the heat pipe fabricated is very less compared to the commercial heat pipes available in the market.

  16. Solar Energy: Heat Storage.

    Science.gov (United States)

    Knapp, Henry H., III

    This module on heat storage is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The module…

  17. Preparation and testing of nickel-based superalloy/sodium heat pipes

    Science.gov (United States)

    Lu, Qin; Han, Haitao; Hu, Longfei; Chen, Siyuan; Yu, Jijun; Ai, Bangcheng

    2017-11-01

    In this work, a kind of uni-piece nickel-based superalloy/sodium heat pipe is proposed. Five models of high temperature heat pipe were prepared using GH3044 and GH4099 nickel-based superalloys. And their startup performance and ablation resistance were investigated by quartz lamp calorifier radiation and wind tunnel tests, respectively. It is found that the amount of charging sodium affects the startup performance of heat pipes apparently. No startup phenomenon was found for insufficient sodium charged model. In contrast, the models charged with sufficient sodium startup successfully, displaying a uniform temperature distribution. During wind tunnel test, the corresponding models experienced a shorter startup time than that during quartz lamp heating. GH4099/sodium heat pipe shows excellent ablation resistance, being better than that of GH3044/sodium heat pipe. Therefore, it is proposed that this kind of heat pipe has a potential application in thermal protection system of hypersonic cruise vehicles.

  18. Ten Year Operating Test Results and Post-Test Analysis of a 1/10 Segment Stirling Sodium Heat Pipe, Phase III

    Science.gov (United States)

    Rosenfeld, John, H; Minnerly, Kenneth, G; Dyson, Christopher, M.

    2012-01-01

    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 yr) 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.

  19. Bayesian analysis of heat pipe life test data for reliability demonstration testing

    Energy Technology Data Exchange (ETDEWEB)

    Bartholomew, R.J.; Martz, H.F.

    1985-01-01

    The demonstration testing duration requirements to establish a quantitative measure of assurance of expected lifetime for heat pipes was determined. The heat pipes are candidate devices for transporting heat generated in a nuclear reactor core to thermoelectric converters for use as a space-based electric power plant. A Bayesian analysis technique is employed, utilizing a limited Delphi survey, and a geometric mean accelerated test criterion involving heat pipe power (P) and temperature (T). Resulting calculations indicate considerable test savings can be achieved by employing the method, but development testing to determine heat pipe failure mechanisms should not be circumvented.

  20. Experimental study of Large-scale cryogenic Pulsating Heat Pipe

    Science.gov (United States)

    Barba, Maria; Bruce, Romain; Bonelli, Antoine; Baudouy, Bertrand

    2017-12-01

    Pulsating Heat Pipes (PHP) are passive two-phase heat transfer devices consisting of a long capillary tube bent into many U-turns connecting the condenser part to the evaporator part. They are thermally driven by an oscillatory flow of liquid slugs and vapor plugs coming from phase changes and pressure differences along the tube. The coupling of hydrodynamic and thermodynamic effects allows high heat transfer performances. Three closed-loop pulsating heat pipes have been developed by the DACM (Department of Accelerators, Cryogenics and Magnetism) of CEA Paris-Saclay, France. Each PHP measures 3.7 meters long (0.35 m for the condenser and the evaporator and 3 m for the adiabatic part), being almost 20 times longer than the longest cryogenic PHP tested. These PHPs have 36, 22 and 12 parallel channels. Numerous tests have been performed in horizontal position (the closest configuration to non-gravity) using nitrogen as working fluid, operating between 75 and 90 K. The inner and outer diameters of the stainless steel capillary tubes are 1.5 and 2 mm respectively. The PHPs were operated at different filling ratios (20 to 90 %), heat input powers (3 to 20 W) and evaporator and condenser temperatures (75 to 90 K). As a result, the PHP with 36 parallel channels achieves a certain level of stability during more than thirty minutes with an effective thermal conductivity up to 200 kW/m.K at 10 W heat load and during forty minutes with an effective thermal conductivity close to 300 kW/m.K at 5 W heat load.

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

    Science.gov (United States)

    Kazi, Salim Newaz; Sadeghinezhad, Emad

    2014-01-01

    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 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. PMID:25254236

  2. 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 than...

  3. 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.

  4. Numerical investigation on pulsating heat pipes with nitrogen or hydrogen

    Science.gov (United States)

    Y Han, D.; Sun, X.; Gan, Z. H.; Y Luo, R.; Pfotenhauer, J. M.; Jiao, B.

    2017-12-01

    With flexible structure and excellent performance, pulsating heat pipes (PHP) are regarded as a great solution to distribute cooling power for cryocoolers. The experiments on PHPs with cryogenic fluids have been carried out, indicating their efficient performances in cryogenics. There are large differences in physical properties between the fluids at room and cryogenic temperature, resulting in their different heat transfer and oscillation characteristics. Up to now, the numerical investigations on cryogenic fluids have rarely been carried out. In this paper, the model of the closed-loop PHP with multiple liquid slugs and vapor plugs is performed with nitrogen and hydrogen as working fluids, respectively. The effects of heating wall temperature on the performance of close-looped PHPs are investigated and compared with that of water PHP.

  5. A numerical analysis of the effects of conjugate heat transfer, vapor compressibility, and viscous dissipation in heat pipes

    Science.gov (United States)

    Faghri, Amir; Chen, Ming-Ming

    1989-01-01

    The effects of conjugate heat transfer, vapor compressibility, and viscous dissipation in heat pipes are discussed. The accuracy of the partially parabolic versus the elliptic presentation of the governing equations is also examined. The results show that the axial wall conduction has a tendency to make the temperature distribution more uniform for heat pipes with large ratios of pipe wall to effective liquid-wick thermal conductivity. The compressible and incompressible models show very close agreement for the total pressure drop, while the local pressure variations along the heat pipe are quite different for these two models when the radial Reynolds number at the interface is high.

  6. 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.

  7. Analysis of Effect of Heat Pipe Parameters in Minimising the Entropy Generation Rate

    Directory of Open Access Journals (Sweden)

    Rakesh Hari

    2016-01-01

    Full Text Available Heat transfer and fluid flow in the heat pipe system result in thermodynamic irreversibility generating entropy. The minimum entropy generation principle can be used for optimum design of flat heat pipe. The objective of the present work is to minimise the total entropy generation rate as the objective function with different parameters of the flat heat pipe subjected to some constraints. These constraints constitute the limitations on the heat transport capacity of the heat pipe. This physical nonlinear programming problem with nonlinear constraints is solved using LINGO 15.0 software, which enables finding optimum values for the independent design variables for which entropy generation is minimum. The effect of heat load, length, and sink temperature on design variables and corresponding entropy generation is studied. The second law analysis using minimum entropy generation principle is found to be effective in designing performance enhanced heat pipe.

  8. Porous Foam Based Wick Structures for Loop Heat Pipes

    Science.gov (United States)

    Silk, Eric A.

    2012-01-01

    As part of an effort to identify cost efficient fabrication techniques for Loop Heat Pipe (LHP) construction, NASA Goddard Space Flight Center's Cryogenics and Fluids Branch collaborated with the U.S. Naval Academy s Aerospace Engineering Department in Spring 2012 to investigate the viability of carbon foam as a wick material within LHPs. The carbon foam was manufactured by ERG Aerospace and machined to geometric specifications at the U.S. Naval Academy s Materials, Mechanics and Structures Machine Shop. NASA GSFC s Fractal Loop Heat Pipe (developed under SBIR contract #NAS5-02112) was used as the validation LHP platform. In a horizontal orientation, the FLHP system demonstrated a heat flux of 75 Watts per square centimeter with deionized water as the working fluid. Also, no failed start-ups occurred during the 6 week performance testing period. The success of this study validated that foam can be used as a wick structure. Furthermore, given the COTS status of foam materials this study is one more step towards development of a low cost LHP.

  9. Central heating pipes cause unwanted heating; CV-leidingen zorgen voor ongewenste opwarming

    Energy Technology Data Exchange (ETDEWEB)

    Wessels, R. [biq-stadsontwerp, Rotterdam (Netherlands); Nuijten, O. [ISSO, Rotterdam (Netherlands)

    2011-12-15

    Research has shown that the risk of hot spots in the drinking water pipes is very high. Hot spots are, for example, caused by central heating pipes that are too close to the water pipes. The water pipes may be 25 C for a long period, thus creating the risk of legionella growth. The various disciplines need to be careful in the design stage and building stage to prevent such situations from occurring. [Dutch] Onderzoek heeft uitgewezen dat het risico op 'hotspots' in de drinkwaterleidingen erg groot is. Hotspots worden bijvoorbeeld veroorzaakt door cv-leidingen die te dicht in de buurt van waterleidingen lopen. Die waterleidingen kunnen dan langdurig warmer zijn dan 25C en daardoor gevaar opleveren voor legionellagroei. Het vereist zorg van meerdere disciplines in de ontwerpfase en de bouwfase om deze situaties te vermijden.

  10. 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...

  11. 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 buil...

  12. Casing of preinsulated district heating pipes. Functional Requirements. Scientific report

    Energy Technology Data Exchange (ETDEWEB)

    Bryder, K.L.; Feld, T.; Randloev, P.; Vestergaard, J.B.; Noergaard Pedersen, H.; Palle, S.; Amby, L.

    1996-10-01

    Requirements for the wall thickness of the casing pipes in Europe were formulated to clarify the laying conditions, representative for the European district heating areas. We achieved a broad estimate by defining four scenarios for the laying of district heating pipes. It is common to the four scenarios that that all bends, branches etc. are always laid in sand. The four scenarios are differentiated by soil types. The soil types include: Uniform sand, Well graded gravel, Sand with fines and Sand with crushed stone. In the following analysis it was possible to examine the influence from following parameters: Casing thickness; Diameter of steel pipe; Diameter of casing; Material properties (PUR and PE); Soil type. The results from the model showed that uniform sand is the absolute best soil type. Based on the results from and earlier project a laboratory method has been developed. The result was a test method based on the indentation of three mandrels with a diameter of {phi}30 mm with a taper with an angle of 45 deg. and with roundings on the apex of R5 mm, R10 mm and R15 mm, respectively. The mandrels simulate stones. The examinations among other things showed that even a 1.5 mm casing demands an indentation of 20 mm with a R5 mm mandrel before it is perforated. The demanded force is 1.6 kN, which is considerably higher than the theoretically highest force in an actual situation. On this background it is recommended that the minimum requirement for the wall thickness of the casings with diameters less than 200 mm should still follow the EN 253, whereas the minimum requirement for the larger casing pipes securely can be reduced. Based on the tests and an evaluation of the safety factors it is proposed that the wall thickness for the largest pipes can be reduced 50%. Thus the wall thickness of an 800 mm casing should be 6.6 mm with a linear reduction down to 3 mm for 180 mm casing. (EG)

  13. An Advanced Loop Heat Pipe for Cryogenic Applications

    Science.gov (United States)

    Ku, Jentung; Hoang, Triem

    2017-01-01

    A loop heat pipe (LHP) is a very versatile heat transfer device that can transport a large heat load over a long distance with a small temperature difference. All LHPs currently servicing orbiting spacecraft are designed to operate in the room temperature range. Future space telescopes and space-based Earth resource imaging satellites require passive cryogenic heat transport devices that can thermally couple remote cryocoolers to sensor or instrument of interest while providing the capability of payload vibration jitter isolation, implementation of redundant coolers, and coupling of multiple sensors to a common heat sink. All of these requirements can be satisfied by using a cryogenic LHP (CLHP). Although the development of CLHPs faces several technical challenges, NASA Goddard Space Flight Center has devoted extensive efforts in developing CLHP technology over the past decade and has made significant progress. In particular, the combination of the innovative ideas of using a secondary capillary pump to manage the parasitic heat gain and using a hot reservoir to reduce the system pressure under the ambient condition has led to the successful development of the CLHP. Several CLHPs charged with nitrogen and hydrogen were built and tested in thermal vacuum chambers. These CLHPs demonstrated reliable start-up and robust operation during power cycle and sink temperature cycle tests.

  14. Thermal conductivity of metal cloth heat pipe wicks

    Science.gov (United States)

    Phillips, J. R.; Chow, L. C.; Grosshandler, W. L.

    1987-08-01

    Experimental results on heat conduction through a metal cloth wick saturated with a liquid are determined and compared to results from both a new mean-gap-conductance model, based on the wick geometry, and the simple series model. The mean-gap-conductance model includes three-dimensional and contact conductance effects, and it evaluates the effects of the mesh geometry in addition to predicting the effective conductivity. This new model predicts the experimental data to within 10 percent, while the series model may be more than 40 percent in error. The present model is used to determine theoretical limits on the maximum and minimum conductivity enhancement as a function of geometric parameters, and to establish guidelines for the design of heat pipe wicks.

  15. 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)

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

    Science.gov (United States)

    Schreiber, Jeffrey G.

    1989-01-01

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

  17. 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...

  18. Procedures for measuring the properties of heat-pipe wick materials

    Energy Technology Data Exchange (ETDEWEB)

    Adkins, D.R.; Dykhuizen, R.C.

    1993-07-01

    Accurate measurements of wick properties must be available to design high-performance beat pipes and to properly interpret results from heat pipe tests. In a program that is aimed at developing heat-pipe receivers for solar-Stirling electric systems, we have recently explored procedures to measure the effective pore radius and permeability of wick materials in their final ``as fabricated`` condition. Measurement techniques are compared in this paper and problems that are frequently encountered in measuring wick properties are discussed.

  19. Investigation on medium temperature heat pipe receiver used in parabolic trough solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Dongdong; Zhang, Hong; Liu, Yun; Li, Sihai; Zhuang, Jun [Nanjing Univ. of Technology (China). Inst. of Thermal Energy Engineering

    2008-07-01

    In this paper, a novel medium temperature (250{proportional_to}500 C) heat pipe receiver was developed for parabolic trough solar collector and the feasibility study on the receiver was carried out. The lifetime analysis, thermal analysis and economic analysis of the heat pipe receiver were presented. The result showed that the heat pipe receiver was flexible, easily maintained, low manufacture cost and could be working reliability in the temperature and heat flux conditions of parabolic trough solar collector with a high heat collect efficiency. (orig.)

  20. The magnetic-nanofluid heat pipe with superior thermal properties through magnetic enhancement

    Science.gov (United States)

    Chiang, Yuan-Ching; Chieh, Jen-Jie; Ho, Chia-Che

    2012-06-01

    This study developed a magnetic-nanofluid (MNF) heat pipe (MNFHP) with magnetically enhanced thermal properties. Its main characteristic was additional porous iron nozzle in the evaporator and the condenser to form a unique flowing pattern of MNF slug and vapor, and to magnetically shield the magnet attraction on MNF flowing. The results showed that an optimal thermal conductivity exists in the applied field of 200 Oe. Furthermore, the minor thermal performance of MNF at the condenser limited the thermal conductivity of the entire MNFHP, which was 1.6 times greater than that filled with water for the input power of 60 W. The feasibilities of an MNFHP with the magnetically enhanced heat transfer and the ability of vertical operation were proved for both a promising heat-dissipation device and the energy architecture integrated with an additional energy system.

  1. 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.

  2. External Corrosion of Pipes in District Heating Systems; Utvaendig korrosion paa fjaerrvaermeroer

    Energy Technology Data Exchange (ETDEWEB)

    Sund, Goeran [Det Norske Veritas, Stockholm (Sweden)

    2002-07-01

    Corrosion damages of pipes in district heating systems can occur both external and internal. The aim with this work has been to clarify external corrosion damages of pipes, and try to correlate the damages to the corrosivity of different soils and waters. For the analysis the Swedish District Heating Association's district heating system statistics has been used. The district heating system statistics shows that the cost for corrosion damages is high, and pipes older than 20 years have increased risk for corrosion. The knowledge about corrosion concerning steel poles and water pipes in soils can not be applied to external corrosion of steel pipes in district heating systems. The corrosion rate of steel poles in soils is low. The corrosion of steel pipes in district heating systems can locally give high rates, up to 0,5 mm/year. The mechanism for this type of corrosion is different compared to the corrosion mechanism of poles in soils. The temperature is higher and aggressive water, with road-salt and chloride content, falls in drops on the steel pipe, and impurities evaporate on the steel surface. These factors increase the corrosion rate. If the material thickness is 5 mm, fracture can occur in the pipe within ten years. The number of copper pipe corrosion damage is limited. The most determining corrosion factors of copper pipes are pH-value and impurities as chloride and sulphate in the water. Stainless steel pipes of type 304 can not be used in soils due to the risk of local corrosion. Higher alloyed stainless steels, with molybdenum and higher chromium content should be used. It is concluded that failures can occur due to external corrosion of steel pipes. This failure is expensive and can lead to human damage. One way to eliminate failures of steel pipes is to carry out risk analysis.

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  7. Reactor Lithium Heat Pipes for HP-STMCs Space Reactor Power System

    Science.gov (United States)

    Tournier, Jean-Michel; El-Genk, Mohamed S.

    2004-02-01

    Design and performance analysis of the nuclear reactor's lithium heat pipes for a 110-kWe Heat Pipes-Segmented Thermoelectric Module Converters (HP-STMCs) Space Reactor Power system (SRPS) are presented. The evaporator length of the heat pipes is the same as the active core height (0.45 m) and the C-C finned condenser is of the same length as the STMC panels (1.5 m). The C-C finned condenser section is radiatively coupled to the collector shoes of the STMCs placed on both sides. The lengths of the adiabatic section, the values of the power throughput and the evaporator wall temperature depend on the radial location of the heat pipe in the reactor core and the number and dimensions of the potassium heat pipes in the heat rejection radiator. The reactor heat pipes have a total length that varies from 7.57 to 7.73 m, and a 0.2 mm thick Mo-14%Re wick with an average pore radius of 12 μm. The wick is separated from the Mo-14%Re wall by a 0.5 mm annulus filled with liquid lithium, to raise the prevailing capillary limit. The nominal evaporator (or reactor) temperature varies from 1513 to 1591 K and the thermal power of the reactor is 1.6 MW, which averages 12.7 kW for each of the 126 reactor heat pipes. The power throughput per heat pipe increase to a nominal 15.24 kW at the location of the peak power in the core and to 20.31 kW when an adjacent heat pipe fails. The prevailing capillary limit of the reactor heat pipes is 28.3 kW, providing a design margin >= 28%.

  8. Heat transfer at the sintered layer-polysynthetic material interface inside heat micro pipes

    Science.gov (United States)

    Sprinceana, Siviu; Mihai, Ioan

    2016-12-01

    If micro heat pipe heat transfers, the inside working fluid goes through a biphasic state. The flow of the liquid and the vapor thereof by the capillary beds of frittered copper and the layer of capillary polysynthetic material and migration of vapors liquid from the end, takes the heat flow towards the end where a transfer of heat may occur only if there is a difference in temperature between the end of a flat micro heat pipe that gives the acquirer heat and heat flux. The porosity of the material is total pore of the total material volume. In the analysis of heat and mass transfer through porous media, both convective and conductive transfer forms can not be separated, because of the surfaces in contact between the two capillar layers. It had been studied the dependence of the rate of flow of liquid through the frittered porous media, and Reynolds polysynthetic. It tracks changes in the Reynolds number based on the interior capillary porosity. They traced in Mathcad [1] the graphs for changing the Reynolds number of capillary pressure by capillary porosity.

  9. Parabolic solar cooker: Cooking with heat pipe vs direct spiral copper tubes

    Science.gov (United States)

    Craig, Omotoyosi O.; Dobson, Robert T.

    2016-05-01

    Cooking with solar energy has been seen by many researchers as a solution to the challenges of poverty and hunger in the world. This is no exception in Africa, as solar coking is viewed as an avenue to eliminate the problem of food insecurity, insufficient energy supply for household and industrial cooking. There are several types of solar cookers that have been manufactured and highlighted in literature. The parabolic types of solar cookers are known to reach higher temperatures and therefore cook faster. These cookers are currently being developed for indoor cooking. This technology has however suffered low cooking efficiency and thus leads to underutilization of the high heat energy captured from the sun in the cooking. This has made parabolic solar cookers unable to compete with other conventional types of cookers. Several methods to maximize heat from the sun for indirect cooking has been developed, and the need to improve on them of utmost urgency. This paper investigates how to optimize the heat collected from the concentrating types of cookers by proposing and comparing two types of cooking sections: the spiral hot plate copper tube and the heat pipe plate. The system uses the concentrating solar parabolic dish technology to focus the sun on a conical cavity of copper tubes and the heat is stored inside an insulated tank which acts both as storage and cooking plate. The use of heat pipes to transfer heat between the oil storage and the cooking pot was compared to the use of a direct natural syphon principle which is achieved using copper tubes in spiral form like electric stove. An accurate theoretical analysis for the heat pipe cooker was achieved by solving the boiling and vaporization in the evaporator side and then balancing it with the condensation and liquid-vapour interaction in the condenser part while correct heat transfer, pressure and height balancing was calculated in the second experiment. The results show and compare the cooking time, boiling

  10. Electric preheating - a new method for laying pre-insulated district heating pipes. District heating schemes on-line faster

    Energy Technology Data Exchange (ETDEWEB)

    Lambertsen, E.; Pedersen, H.N.

    1990-01-01

    i.c.moeller a/s of Fredericia, Denmark, is one of the world's leading manufacturers of pre-insulated pipe systems. The company, a member of the ABB Group, has refined district heating pipeline design to a degree where heat losses can be neglected over distances of 100 km and more. Pipe installation is also undergoing continuing improvement at i.c.moeller, which has developed a method of electric preheating that makes it easier to prestress friction-locked pipe systems. This method has also proved successful for large-diameter pipes. (orig.).

  11. 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

  12. Design and test of a self-controlled heat pipe radiator.

    Science.gov (United States)

    Swerdling, B.; Hembach, R.

    1973-01-01

    A 15,000-W spacecraft waste heat rejection system utilizing heat pipe radiator panels has been investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500-W radiator panel has been designed, built, and bench tested. The panel, which is a module of the 15,000-W system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiator. The thermal load to the VCHP is supplied by a Freon 21 liquid loop via an integral heat exchanger. This paper describes the results of the system studies and the radiator design. Also presented are test data on the VCHP, heat exchanger and isothermalizer heat pipes.

  13. An experimental study on an oscillating loop heat pipe consisting of three interconnected columns

    Science.gov (United States)

    Özdemir, Mustafa

    2007-04-01

    This paper presents some experimental results of an extensive research on a novel oscillating heat pipe. The heat pipe is formed of three interconnected columns as different from the pulsating heat pipe designs. The dimensions of the heat pipe considered in this study are large enough to neglect the effect of capillary forces. Thus, the self-oscillation of the system is driven by the gravitational force and the phase lag between the evaporation and condensation processes. The overall heat transfer coefficient is found to be approximately constant irrespective of heat load for the experimental cases considered. The results are also compared with the previously published data by other investigators for water as the working fluid and for the same heat input range. The experimental data for the time variation of the liquid column heights and the vapor pressure are correlated algebraically, convenient for practical uses.

  14. Two phase flow and heat transfer characteristics of a separate-type heat pipe

    Science.gov (United States)

    Tang, Zhiwei; Liu, Aijie; Jiang, Zhangyan

    2011-07-01

    Two phase flow and heat transfer characteristics of a separate-type heat pipe have been studied experimentally and theoretically. The experimental apparatus have the same geometry for the evaporator and the condenser which consist of 5-tube-banks, with working temperature ranges of 80-125°C. The experimental working fluid is dual-distilled water with corrosion-resistant agents. Heat transfer coefficients for boiling and condensation along with heat flux and working temperature are measured at different filling ratio. According to the results of the experiments, the optimized filling ratio ranges from 16 to 36%. Fitted correlations of average heat transfer coefficients of the evaporator and Nusselt numbers of the condenser at the proposed filling ratio are obtained. Two phase flow characteristics of the evaporator and the condenser as well as their influence on heat transfer are described on the basis of simplified analysis. Reasons for the pulse-boiling process remain to be studied.

  15. An experimental study of heat pipe thermal management system with wet cooling method for lithium ion batteries

    Science.gov (United States)

    Zhao, Rui; Gu, Junjie; Liu, Jie

    2015-01-01

    An effective battery thermal management (BTM) system is required for lithium-ion batteries to ensure a desirable operating temperature range with minimal temperature gradient, and thus to guarantee their high efficiency, long lifetime and great safety. In this paper, a heat pipe and wet cooling combined BTM system is developed to handle the thermal surge of lithium-ion batteries during high rate operations. The proposed BTM system relies on ultra-thin heat pipes which can efficiently transfer the heat from the battery sides to the cooling ends where the water evaporation process can rapidly dissipate the heat. Two sized battery packs, 3 Ah and 8 Ah, with different lengths of cooling ends are used and tested through a series high-intensity discharges in this study to examine the cooling effects of the combined BTM system, and its performance is compared with other four types of heat pipe involved BTM systems and natural convection cooling method. A combination of natural convection, fan cooling and wet cooling methods is also introduced to the heat pipe BTM system, which is able to control the temperature of battery pack in an appropriate temperature range with the minimum cost of energy and water spray.

  16. 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

    2017-02-01

    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.

  17. Feasibility study on the application of a heat-pipe type adsorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang Hyeok; Chung, Jae Dong [Dept. of Mechanical Engineering, Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Energy System R and D Group, Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)

    2017-01-15

    A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl{sub 2}) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature.

  18. Study on heat transfer of an osmotic heat pipe with a two-phase solution loop. 1st Report. Fundamental study; Niso yoeki junkan shinto heat pipe no netsu yuso ni kansuru kenkyu. 1. Kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ipposhi, S.; Imura, H. [Kumamoto University, Kumamoto (Japan). Faculty of Engineering; Ogata, A. [Kumamoto University, Kumamoto (Japan)

    1999-12-25

    In the prior paper, a loop-type osmotic beat pipe was investigated on the heat transport rate from the upper position to the lower. The beat transport rate of this osmotic heat pipe, however, was very small because of small driving force for the solution circulation. Therefore, the osmotic heat pipe with the higher driving force is devised. The larger driving force is produced by a two-phase flow taking place in the solution riser. For the sake of that, a vopor-liquid separator is installed at the top of the apparatus and a heated section is attached as some distance below the separator, so that buoyant force caused by density difference between the fluids in the solution riser and downcomer increases. This osmotic heat pipe with the two-phase solution circulation loop indicates the higher heat transport rate than that of the osmotic heat pipe shown in the prior paper. (author)

  19. Establishing low-power operating limits for liquid metal heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Secary, J. [Phillips Lab., Kirtland AFB, NM (United States); Merrigan, M.A.; Keddy, M.D. [Los Alamos National Lab., NM (United States)

    1992-05-01

    Liquid metal heat pipes operated at power throughputs well below their design point for long durations may fail as a result of the working fluid migrating to a cold region within the pipe, freezing there, and hot returning to the evaporator section. Eventually sufficient working fluid inventory may be lost to the cold region to cause a local dry-out condition in the evaporator. A joint experimental and analytical effort between the Air Force Phillips Laboratory and Los Alamos National Laboratory is underway to investigate the phenomena. Experiments include both high temperature liquid metal and low temperature organic heat pipes. To date, a low temperature working fluid has been selected and its performance in a heat pipe validated. Additionally, a low-temperature heat pipe has been fabricated and is presently being tested.

  20. A steady-state model for heat pipes of circular or rectangular cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, K.A.R. [UNICAMP-FEM, Departamento de Termica e Fluidos, Sao Paulo (Brazil); Zanardi, M.A. [UNESP-Guaratingueta, Faculdade de Engenharia, Departamento de Energia Guartingueta, Sao Paulo (Brazil)

    1996-08-01

    The objective of this paper is to present a generalized analytical- numerical model of the internal flow in heat pipes. The model formulation is based on two-dimensional formulation of the energy and momentum equations in the vapour and liquid regions and also in the metallic tube. The numerical solution of the model is obtained by using the descretization scheme LOAD and the SIMPLE numerical code. The flow fields, as well as the pressure fields, for different geometries were obtained and discussed. (Author)

  1. Using Solar Hot Water to Address Piping Heat Losses in Multifamily Buildings

    Energy Technology Data Exchange (ETDEWEB)

    Springer, David [Alliance for Residential Building Innovation, Davis, CA (United States); Seitzler, Matt [Alliance for Residential Building Innovation, Davis, CA (United States); Backman, Christine [Alliance for Residential Building Innovation, Davis, CA (United States); Weitzel, Elizabeth [Alliance for Residential Building Innovation, Davis, CA (United States)

    2015-10-01

    Solar thermal water heating is most cost effective when applied to multifamily buildings and some states offer incentives or other inducements to install them. However, typical solar water heating designs do not allow the solar generated heat to be applied to recirculation losses, only to reduce the amount of gas or electric energy needed for hot water that is delivered to the fixtures. For good reasons, hot water that is recirculated through the building is returned to the water heater, not to the solar storage tank. The project described in this report investigated the effectiveness of using automatic valves to divert water that is normally returned through the recirculation piping to the gas or electric water heater instead to the solar storage tank. The valves can be controlled so that the flow is only diverted when the returning water is cooler than the water in the solar storage tank.

  2. Using of Multiwall Carbon Nanotube Based Nanofluid in the Heat Pipe to Get Better Thermal Performance

    Directory of Open Access Journals (Sweden)

    Y. Bakhshan

    2014-09-01

    Full Text Available Thermal performance of a cylindrical heat pipe is investigated numerically. Three different types of water based nanofluids, namely, Al2O3 + Water, Diamond + Water, and Multi-Wall Carbon Nano tube (MWCNT + Water, have been used. The influence of using the simple nanofluids and MWCNT nanofluid on the heat pipe characteristics such as liquid velocity, pressure profile, temperature profile, thermal resistance, and heat transfer coefficient of heat pipe has been studied. A new correlation developed by Bakhshan and Saljooghi (2014 for viscosity of nanofluids has been implemented. The results show, a good agreement with the available analytical and experimental data. Also the results show, that the MWCNT based nanofluid has lower thermal resistance, higher heat transfer coefficient, and lower temperature difference between evaporator and condenser sections, so it has good thermal specifications as a working fluid for use in heat pipes. The prepared code has capability for parametric studies also.

  3. Particle shape effect on heat transfer performance in an oscillating heat pipe

    Directory of Open Access Journals (Sweden)

    Chen Hsiu-hung

    2011-01-01

    Full Text Available Abstract The effect of alumina nanoparticles on the heat transfer performance of an oscillating heat pipe (OHP was investigated experimentally. A binary mixture of ethylene glycol (EG and deionized water (50/50 by volume was used as the base fluid for the OHP. Four types of nanoparticles with shapes of platelet, blade, cylinder, and brick were studied, respectively. Experimental results show that the alumina nanoparticles added in the OHP significantly affect the heat transfer performance and it depends on the particle shape and volume fraction. When the OHP was charged with EG and cylinder-like alumina nanoparticles, the OHP can achieve the best heat transfer performance among four types of particles investigated herein. In addition, even though previous research found that these alumina nanofluids were not beneficial in laminar or turbulent flow mode, they can enhance the heat transfer performance of an OHP.

  4. Closeout Report for the Refractory Metal Accelerated Heat Pipe Life Test Activity

    Science.gov (United States)

    Martin, J.; Reid, R.; Stewart, E.; Hickman, R.; Mireles, O.

    2013-01-01

    With the selection of a gas-cooled reactor, this heat pipe accelerated life test activity was closed out and its resources redirected. The scope of this project was to establish the long-term aging effects on Mo-44.5%Re sodium heat pipes when subjected to space reactor temperature and mass fluences. To date, investigators have demonstrated heat pipe life tests of alkali metal systems up to .50,000 hours. Unfortunately, resources have not been available to examine the effect of temperature, mass fluence, or impurity level on corrosion or to conduct post-test forensic examination of heat pipes. The key objective of this effort was to establish a cost/time effective method to systematically test alkali metal heat pipes with both practical and theoretical benefits. During execution of the project, a heat pipe design was established, a majority of the laboratory test equipment systems specified, and operating and test procedures developed. Procurements for the heat pipe units and all major test components were underway at the time the stop work order was issued. An extremely important outcome was the successful fabrication of an annular wick from Mo-5%Re screen (the single, most difficult component to manufacture) using a hot isostatic pressing technique. This Technical Publication (TP) includes specifics regarding the heat pipe calorimeter water-cooling system, vendor design for the radio frequency heating system, possible alternative calorimeter designs, and progress on the vanadium equilibration technique. The methods provided in this TP and preceding project documentation would serve as a good starting point to rapidly implement an accelerated life test. Relevant test data can become available within months, not years, and destructive examination of the first life test heat pipe might begin within 6 months of test initiation. Final conclusions could be drawn in less than a quarter of the mission duration for a long-lived, fission-powered, deep space probe.

  5. Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects

    OpenAIRE

    Armijo, Kenneth Miguel

    2011-01-01

    This research investigates the impact of Marangoni phenomena, with low mixture concentrations of alcohol and water, to enhance thermal transport capability of gravity-assisted heat pipes. The use of binary mixture working fluids in gravity-assisted heat pipes are shown to improve the critical heat flux (CHF) and operating performance, more so than with pure fluids. The CHF is responsible for dryout when the pumping rate of a liquid flow structure is not sufficient to provide enough fluid to t...

  6. 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.

  7. Study on heat transfer rate of an osmotic heat pipe. 3rd Report. Estimation of heat transport limits; Shinto heat pipe no netsuyuso ni kansuru kenkyu. 3. Netsuyuso genkai no yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Ipposhi, S.; Imura, H. [Kumamoto University, Kumamoto (Japan). Faculty of Engineering; Konya, K. [Oji Paper Co. Ltd., Tokyo (Japan); Yamamura, H. [Kyushu University, Fukuoka (Japan)

    1998-07-25

    This paper describes an experimental and theoretical study on the heat transport limits of an osmotic heat pipe operated under the atmospheric pressure, using aqueous polyethylene glycol 600 solution (0.1 - 1.0 kmol/m{sup 3}) as the working fluid and 18 tubular-type acetyl cellulose osmotic membranes. As a result, the correlation between the heat transport rate and the osmotic area was revealed, and the effects of the physical properties of the solution and the geometry (i.e. inside diameters of the flow lines, etc.) of the osmotic heat pipe on the heat transport rate were theoretically investigated. Also, the heat transport rate of the present osmotic heat pipe is about 85% compared with that under such an ideal condition that the solution of the average concentration is assumed to be filled in the solution loop. 4 refs., 9 figs., 1 tab.

  8. 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.

  9. 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.)

  10. 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.)

  11. 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.

  12. Experimental studies of surface modified oscillating heat pipes

    Science.gov (United States)

    Leu, Tzong-Shyng; Wu, Cheng-Han

    2017-04-01

    Oscillating heat pipe (OHP) is a two-phase heat transfer device which has the characteristics of simple construction, high heat flux capability and no need of wicking structures for liquid transport. There are many studies in finding the ways how to improve the system performance OHP. In this paper, studies of the effects of contact angle (θ c ) on the inner wall of OHP system have been conducted first. Glass OHP systems with unmodified (θ c = 26.74°), superhydrophobic (θ c = 156.2°), superhydrophilic (θ c evaporator region and superhydrophobic within condensation region) surfaces, are studied. The research results indicated that thermal resistance of these four OHP systems can be significantly affected by different surface modification approaches. Although superhydrophobic OHP system can still work, the thermal resistance (R th ) is the highest one of the four OHP systems, R th = 0.36 °C/W at 200 W. Unmodified pure glass and superhydrophilic OHP systems have similar performance. Thermal resistances are 0.28 and 0.27 °C/W at 200 W respectively. The hybrid OHP achieves the lowest thermal resistance, R th = 0.23 °C/W at 200 W in this study. The exact mechanism and effects of contact angle on OHP systems are investigated with the help of flow visualization. By comparing the flow visualization results of OHP systems before and after surface modification, one tries to find the mechanism how the surface modified inner wall surface affects the OHP system performance. In additional to the reason that the superhydrophobic dropwise condensation surface inside the hybrid OHP system, hybrid OHP system shows more stable and energetic circulation flow. It is found that instead of stratified flow, vapor slug flows are identified within the evaporator section of the hybrid OHP system that can effectively generate higher pressure force for two phase interfacial flow. This effect is attributed to be the main mechanism for better performance of the hybrid OHP system.

  13. 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.

  14. 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.

  15. 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.

  16. A very light and thin liquid hydrogen/deuterium heat pipe target for COSY experiments

    Science.gov (United States)

    Abdel-Bary, M.; Abdel-Samad, S.; Kilian, K.

    2005-07-01

    A liquid hydrogen/deuterium heat pipe (HP) target is used at the COSY external experiments TOF, GEM and MOMO. The target liquid is produced at a cooled condenser and guided through a central tube assisted by gravitation into the target cell. An aluminum condenser is used instead of copper, which requires less material, improves conductivities and provides shorter cooling down time. Residual condenser temperature fluctuations in the order of ≈0.4 K are reduced by using thermal resistances between the cooling machine and the condenser of the heat pipe combined with a controlled heating power. A new design with only a 7-mm-diameter HP has been developed. The diameter of the condenser part remains at 16 mm to provide enough condensation area. The small amount of material ensures short cooling down times. A cold gas deuterium HP target has been designed and developed which allows protons with energy ⩽1 MeV to be measured. A 7-mm-diameter HP is used to fill a cooling jacket around the D 2 gas cell with LH 2. The D 2 gas is stabilized at 200 mbar to allow for thin windows. Its density is increased by factor 15 compared to room temperature.

  17. 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...

  18. Separation of Power and Capacity In latent Heat Energy Storage

    OpenAIRE

    Pointner, H.; Steinmann, W.D.; van Eck, M.; Bachelier, C.

    2015-01-01

    The state-of-the-art latent heat energy storage system is equipped with aluminum fins at the heat exchanger pipes in order to compensate the low thermal conductivity of the phase change material (PCM). The necessary amount of fins is directly coupled to the capacity of the storage system, what makes larger systems expensive. The PCMflux concept is developed in order to realize both a controllable and a possibly more cost effectivelatent heat storage system. These aims are addressed by separat...

  19. Design of Low-Energy District Heating System for a Settlement with Low-Energy Buildings

    DEFF Research Database (Denmark)

    Tol, Hakan; Svendsen, Svend

    2011-01-01

    With the integration of new low-energy buildings the traditional district heating (DH) systems with high operating temperatures will have significantly higher heat loss according to the heat supplied to the district. The relatively higher heat loss could be reduced with low operating temperatures...... of 55 °C and 25 °C in supply and return line of DH network, respectively with a convenient control of in-house installations (substations). Traditional DH pipe dimensioning methods were based on size searching algorithm in which lowest possible pipe diameter was defined according to the limit of max...

  20. Numerical investigation of heat transfer enhancement in a rectangular heated pipe for turbulent nanofluid

    National Research Council Canada - National Science Library

    Yarmand, Hooman; Gharehkhani, Samira; Kazi, Salim Newaz; Sadeghinezhad, Emad; Safaei, Mohammad Reza

    2014-01-01

    .... 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...

  1. Numerical simulation of heat and mass transfer in a 3D model of a loop heat pipe evaporator

    Directory of Open Access Journals (Sweden)

    Aleksey A. Pozhilov

    2017-10-01

    Full Text Available The article presents results of 3D numerical simulation of flow and conjugate heat and mass transfer in a model of the TacSat-4 satellite loop heat pipe evaporator. The mathematical model includes the Reynolds-averaged Navier–Stokes equations describing the flow in the liquid and vapor regions, Darcy's law for filtration modeling in the wicks and the energy equation with accurate coupling of connected sub-domains including effects of evaporation on interfaces between the porous and vapor regions. According to the simulation results, the evaporation localizes mainly at the vapor groove corners near the evaporator body. The vapor grooves operate under essentially different conditions, as a result, the flow rates differ by several times. Significant thickening of the evaporator body yields only weak reduction in a level of the grooves’ flow rate non-uniformity.

  2. Loop Heat Pipe Temperature Oscillation Induced by Gravity Assist and Reservoir Heating

    Science.gov (United States)

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

    2015-01-01

    The Laser Thermal Control System (LCTS) for the Advanced Topographic Laser Altimeter System (ATLAS) to be installed on NASA's Ice, Cloud, and Land Elevation Satellite (ICESat-2) consists of a constant conductance heat pipe and a loop heat pipe (LHP) with an associated radiator. During the recent thermal vacuum testing of the LTCS where the LHP condenser/radiator was placed in a vertical position above the evaporator and reservoir, it was found that the LHP reservoir control heater power requirement was much higher than the analytical model had predicted. Even with the control heater turned on continuously at its full power, the reservoir could not be maintained at its desired set point temperature. An investigation of the LHP behaviors found that the root cause of the problem was fluid flow and reservoir temperature oscillations, which led to persistent alternate forward and reversed flow along the liquid line and an imbalance between the vapor mass flow rate in the vapor line and liquid mass flow rate in the liquid line. The flow and temperature oscillations were caused by an interaction between gravity and reservoir heating, and were exacerbated by the large thermal mass of the instrument simulator which modulated the net heat load to the evaporator, and the vertical radiator/condenser which induced a variable gravitational pressure head. Furthermore, causes and effects of the contributing factors to flow and temperature oscillations intermingled.

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

    Science.gov (United States)

    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

  4. High-Speed Visual Analysis of Fluid Flow and Heat Transfer in Oscillating Heat Pipes with Different Diameters

    Directory of Open Access Journals (Sweden)

    Xiangdong Liu

    2016-10-01

    Full Text Available The oscillating heat pipe (OHP is a new member in the family of heat pipes, and it has great potential applications in energy conservation. However, the fluid flow and heat transfer in the OHP as well as the fundamental effects of inner diameter on them have not been fully understood, which are essential to the design and optimization of the OHP in real applications. Therefore, by combining the high-speed visualization method and infrared thermal imaging technique, the fluid flow and thermal performance in the OHPs with inner diameters of 1, 2 and 3 mm are presented and analyzed. The results indicate that three fluid flow motions, including small oscillation, bulk oscillation and circulation, coexist or, respectively, exist alone with the increasing heating load under different inner diameters, with three flow patterns occurring in the OHPs, viz. bubbly flow, slug flow and annular flow. These fluid flow motions are closely correlated with the heat and mass transfer performance in the OHPs, which can be reflected by the characteristics of infrared thermal images of condensers. The decrease in the inner diameter increases the frictional flow resistance and capillary instability while restricting the nucleate boiling in OHPs, which leads to a smaller proportion of bubbly flow, a larger proportion of short slug flow, a poorer thermal performance, and easier dry-out of working fluid. In addition, when compared with the 2 mm OHP, the increasing role of gravity induces the thermosyphon effect and weakens the ‘bubble pumping’ action, which results in a little smaller and bigger thermal resistances of 3 mm OHP under small and bulk oscillation of working fluid, respectively.

  5. A re-entrant groove hydrogen heat pipe

    Science.gov (United States)

    Alario, J.; Kosson, R.; Mccreight, C.

    1978-01-01

    This paper extends the development of reentrant groove technology to hydrogen heat pipes. Parametric analyses are presented which optimize the theoretical design while considering the limitations of state-of-the-art extrusion technology. Acceptable production-type runs of extruded lengths (over 300 m) could only be achieved at the expense of a wider nominal groove opening than specified (0.33 mm vs. 0.20 mm). However, dimensional variations of other critical dimensions were within 0.05 mm, which exceeded expectations. The 6063-T6 aluminum extrusion is 14.6 mm OD with a wall thickness of 1.66 mm and contains 20 axial grooves which surround a central 9.3-mm-diam vapor core. Each axial groove is 0.775-mm-diam with a 0.33 mm opening. An excess vapor reservoir is provided at the evaporator to minimize the pressure containment hazard during ambient storage. Details of the instrumentation and helium-cooled test installation are also presented.

  6. 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.

  7. Assessment of existing and prospective piping technology for district-heating applications

    Energy Technology Data Exchange (ETDEWEB)

    Oliker, I.

    1979-09-01

    Data on design features and operational experience of 40 hot water and steam district-heating networks with an overall heat capacity of 18,000 MWt have been collected, systematized, and analyzed. Piping networks located in Canada, Denmark, Finland, France, Italy, Japan, Netherlands, Sweden, USA, USSR, and West Germany have been analyzed and the data assembled. The data bank and analysis of the operational experience design features of hot water and steam district-heating networks are provided in Sections 2 and 3. In Section 4 the piping installation design is optimized in order to reduce costs wherever possible, without jeopardizing overall system efficiency, reliability or service life, and employing a mixture of typical US and European district-heating practices. The status of prospective non-metallic piping materials is presented in Section 5. The following materials have been investigated: fiberglass reinforced plastic, cross-linked polyethylene, polybutylene, prestressed concrete, polymer concrete, and asbestos-cement piping. (MCW)

  8. 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...

  9. 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...

  10. 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...

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

    Science.gov (United States)

    Kareem, Rashid

    2017-10-01

    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.

  12. An experimental study of naturally driven heated air flow in a vertical pipe

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Mostafa; Bayat, Mohammad Mehdi [Department of Mechanical Engineering, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2011-01-15

    Specifications of warm air flow within a vertical pipe which is induced by the buoyancy effect were investigated in this study. Air from surroundings was directed into a heating chamber connected to a vertical pipe to establish a flow within the pipe. The temperature and the velocity were measured at different points within the stable flow and the mean values of these parameters were computed. Mass flow rate of air was evaluated using ideal gas assumption. In order to investigate the effect of the thermal boundary condition of the pipe, two tests were conducted; once for the pipe exposed to the surroundings and then for the pipe with a thermal insulation. A model for predicting the induced flow rate of warm air was developed and the predictions of the model were compared with the experimental data over the tested range of the parameters. (author)

  13. Characteristics of low-temperature short heat pipes with a nozzle-shaped vapor channel

    Science.gov (United States)

    Seryakov, A. V.

    2016-01-01

    This paper presents the results of experimental and numerical studies of heat transfer and swirling pulsating flows in short low-temperature heat pipes whose vapor channels have the form of a conical nozzle. It has been found that as the evaporator of the heat pipe is heated, pressure pulsations occur in the vapor channel starting at a certain threshold value of the heat power, which is due to the start of boiling in the evaporator. The frequency of the pulsations has been measured, and their dependence on the superheat of the evaporator has been determined. It has been found that in heat pipes with a conical vapor channel, pulsations occur at lower evaporator superheats and the pulsation frequency is greater than in heat pipes of the same size with a standard cylindrical vapor channel. It has been shown that the curve of the heat-transfer coefficient versus thermal load on the evaporator has an inflection corresponding to the start of boiling in the capillary porous evaporator of the heat pipe.

  14. Fluid flow and heat transfer in an air-to-water double-pipe heat exchanger

    Science.gov (United States)

    Sheikholeslami, M.; Gorji-Bandpy, M.; Ganji, D. D.

    2015-11-01

    This paper reports experimental and numerical investigations on flow and heat transfer in an air-to-water double-pipe heat exchanger. The working fluids are air and water. To achieve fully developed conditions, the heat exchanger was built with additional lengths before and after the test section. The inner and outer tube was made from copper and Plexiglas, respectively. The experiments are conducted in the range of air flow Reynolds number for various cases with different water flow rate and water inlet temperature. Correlations for the Nusselt number and friction factor are presented according to experimental data. Also the commercial code ANSYS 15 is used for numerical simulation. Results show that the Nusselt number is an increasing function of Reynolds number and Prandtl number which are calculated at bulk temperature.

  15. Design, Construction, and Performance Analysis of a Wood Thermal Conductivity Measurement Device using Flat Plate Heat Pipes

    Directory of Open Access Journals (Sweden)

    Rasouli Moien

    2011-12-01

    Full Text Available In this paper, the design, construction, and performance analysis of a wood thermal conductivity measurement device using flat plate heat pipes has been experimentally studied. The device was designed to measure the thermal conductivity of wood in various ranges of temperature. Thermal conductivity of hornbeam (Carpinus betulus has been measured at various temperatures between 40-80 ºC and a relationship has been recommended for the sample. The results show that the thermal conductivity of this species increases linearly with temperature. Also, it has been concluded that flat plate heat pipes distribute heat flux on the surface of the wood uniformly leading to a faster steady state condition, which can reduce time of the test and result in energy saving and more accurate results.

  16. Development of heat pipe technology for permanent mold casting of magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elalem, K.; Mucciardi, F.; Gruzleski, J.E. [McGill Univ., Dept. of Mining and Metallurgical Engineering, Montreal, Quebec (Canada)]. E-mail: Kaled.elalem@mail.mcgill.ca; Carbonneau, Y. [Intermag Technologies, Inc., Sainte-Foy, Quebec (Canada)

    2002-07-01

    One of the key techniques for producing sound permanent mold castings is to use controlled mold cooling such as air cooling, water cooling and heat pipe cooling. Air-cooling has limited applications in permanent mold casting due to its low cooling capability and high cost. Water-cooling is widely used in permanent mold casting, but has some disadvantages such as safety issues and the facilities required. The early applications of heat pipes in permanent mold casting have shown tremendous results due to their high cooling rates, low cost and safety. In this work, a permanent mold for magnesium casting has been designed with the intention of producing shrinkage defects in the castings. Novel heat pipes that can generate high cooling rates have been constructed and used to direct the solidification in order to reduce the shrinkage. In this paper, the design of the mold and that of the heat pipes are presented. The results of some of the computer simulations that were conducted to determine casting conditions along with the potential of using heat pipes to direct the solidification are also presented. Moreover, a preliminary evaluation of the performance of heat pipes in the permanent mold casting of magnesium will also be discussed. (author)

  17. Computational Study of Convective Heat Transfer in Circular Pipe using Trapezoidal Ribs

    Science.gov (United States)

    Patel, V. K.; Sharma, P.; Saxena, K.

    2017-09-01

    Perturbations or interruptions provided in the passage of heat exchanger generate the vortices downstream. The formation of these natural vortices, augment local heat transfer abruptly. The effect on convective heat transfer enhancement and friction characteristics by providing trapezoidal ribs inside a circular pipe is computationally investigated in detail. Different variations of height, width and pitch of the ribs are used to optimize the rate of heat transfer through the pipe. Liquid water is employed as the working fluid. Input parameters of Reynolds Number ranging from 5000-60000 with axial flow along the pipe and constant heat flux of 50 W/cm2 to the pipe surface is used. After validation with the existing literature, Realizable k-ε turbulent model with enhanced wall function is used in commercial CFD software ANSYS FLUENT. The outcome of the investigation shows that the ribs provided on the inside of the pipe surface enhance the turbulence in the flow and produce recirculation which disturb the thermal boundary layer behind the ribs and thus help in enhancing the rate of heat transfer through the pipe.

  18. 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.

  19. 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

    Increasing the building energy efficiency in recent years results in noticeably reduction in their heating demand. Combined with the current trend for utilizing low temperature heat sources, it raises the necessity of introducing a new generation of district heating [DH] systems with lowered...

  20. 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.

  1. Heat emission inventories in urban areas reduction of transmission losses of district heating pipes

    OpenAIRE

    Wenk, Matthias

    2014-01-01

    Heat emission from buildings as a result of inadequate thermal insulation leads to energy loss and thus unnecessary costs. In long-distance heating lines thermal transfer also often causes undetected transmission losses. The knowledge of the sources of such loss would help increase energy efficiency significantly, decrease global energy consumption, reduce greenhouse gases and cut energy cost at the same time. A technological approach based on infrared thermography is presented in the followi...

  2. Behaviour : Seeing heat saves energy

    NARCIS (Netherlands)

    Steg, Linda

    2016-01-01

    Household energy conservation can help to significantly lower energy consumption. Visual cues provided by thermal imaging of heat loss in buildings are now shown to increase energy conserving behaviours and implementations among homeowners more effectively than just performing carbon footprint

  3. Effect of Material Property Variations at Near Critical Thermodynamic Conditions on Pipe Flow Heat Transfer

    Science.gov (United States)

    Barney, Rebecca; Nourgaliev, Robert; Delplanque, Jean-Pierre; McCallen, Rose

    2017-11-01

    Heat transfer is quantified and contrasted for the Poiseuille flow of a fluid at both subcritical and supercritical thermodynamic conditions in a circular pipe subject to a uniform wall heat flux. The conditions considered are relevant to Supercritical Water Reactor (SCWR) applications. In the supercritical thermodynamic regime, a fluid can exhibit large density variations of density, thermal conductivity, and viscosity, which will affect flow and heat transfer characteristics significantly. An advanced equation of state for supercritical water was implemented in a 2D and 3D Arbitrary Lagrangian-Eurlerian multi-physics simulation tool called ALE3D developed at Lawrence Livermore National Laboratory. A newly developed, robust, high-order in space and time, fully implicit reconstructed discontinuous Galerkin (rDG) method is used to enable the numerical simulation of convective heat transfer with supercritical water. Results demonstrate the capability of this approach to accurately capture the non-linear behavior and enhanced heat transfer with supercritical water. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Information management release number LLNL-ABS-736004. Work is supported by the Integrated University Program Graduate Fellowship. Opinions, findings, conclusions or recommendations expressed are of the authors and do not necessarily reflect the views of DOE office of NE.

  4. A numerical method for natural convection and heat conduction around and in a horizontal circular pipe

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Satoru; Niiyama, Daisuke [Tohoku Univ., Sendai (Japan). Dept. of Aeronautics and Space Engineering; Byeong Rog Shin [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science

    2004-12-01

    Natural convection around a horizontal circular pipe coupled with heat conduction in the solid structure is numerically investigated using a preconditioning method for solving incompressible and compressible Navier-Stokes equations. In this method, fundamental equations are completely reduced to an equation of heat conduction when the flow field is static (zero velocity). Therefore, not only compressible flows but also very slow flows such as natural convection in a flow field and heat conduction in a static field can be simultaneously calculated using the same computational algorithm. In this study, we first calculated the compressible flow around a NACA0012 airfoil with conduction in the airfoil and then simulated natural convections around a horizontal circular pipe with a different heat conductivity. Finally, we numerically investigated the effect of heat conductivity of the pipe on natural convection. (author)

  5. Heat transfer performance of a pulsating heat pipe charged with acetone-based mixtures

    Science.gov (United States)

    Wang, Wenqing; Cui, Xiaoyu; Zhu, Yue

    2017-06-01

    Pulsating heat pipes (PHPs) are used as high efficiency heat exchangers, and the selection of working fluids in PHPs has a great impact on the heat transfer performance. This study investigates the thermal resistance characteristics of the PHP charged with acetone-based binary mixtures, where deionized water, methanol and ethanol were added to and mixed with acetone, respectively. The volume mixing ratios were 2:1, 4:1 and 7:1, and the heating power ranged from 10 to 100 W with filling ratios of 45, 55, 62 and 70%. At a low filling ratio (45%), the zeotropic characteristics of the binary mixtures have an influence on the heat transfer performance of the PHP. Adding water, which has a substantially different boiling point compared with that of acetone, can significantly improve the anti-dry-out ability inside the PHP. At a medium filling ratio (55%), the heat transfer performance of the PHP is affected by both phase transition characteristics and physical properties of working fluids. At high heating power, the thermal resistance of the PHP with acetone-water mixture is between that with pure acetone and pure water, whereas the thermal resistance of the PHP with acetone-methanol and acetone-ethanol mixtures at mixing ratios of 2:1 and 4:1 is less than that with the corresponding pure fluids. At high filling ratios (62 and 70%), the heat transfer performance of the PHP is mainly determined by the properties of working fluids that affects the flow resistance. Thus, the PHP with acetone-methanol and acetone-ethanol mixtures that have a lower flow resistance shows better heat transfer performance than that with acetone-water mixture.

  6. 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...... in practice.Keywords: cartel damages, pre-insulated pipesJEL: L13, L41, L61/L95...

  7. A Designer Fluid For Aluminum Phase Change Devices. Performance Enhancement in Copper Heat Pipes Performance Enhancement in Copper Heat Pipes. Volume 3

    Science.gov (United States)

    2016-11-17

    Approved for public release: distribution is unlimited. 1 Summary Heat pipes and other phase change devices have vast application to thermal management ...and other phase change heat transfer devices offer many important advantages as a thermal management device and have been of interest for years. Their...saturation temperature of the working fluid and eliminate the interfacial resistance to evaporation created by air. Phase change devices will typically

  8. 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.

  9. Energetic and Economic Assessment of Pipe Network Effects on Unused Energy Source System Performance in Large-Scale Horticulture Facilities

    Directory of Open Access Journals (Sweden)

    Jae Ho Lee

    2015-04-01

    Full Text Available As the use of fossil fuel has increased, not only in construction, but also in agriculture due to the drastic industrial development in recent times, the problems of heating costs and global warming are getting worse. Therefore, the introduction of more reliable and environmentally-friendly alternative energy sources has become urgent and the same trend is found in large-scale horticulture facilities. In this study, among many alternative energy sources, we investigated the reserves and the potential of various different unused energy sources which have infinite potential, but are nowadays wasted due to limitations in their utilization. This study investigated the effects of the distance between the greenhouse and the actual heat source by taking into account the heat transfer taking place inside the pipe network. This study considered CO2 emissions and economic aspects to determine the optimal heat source. Payback period analysis against initial investment cost shows that a heat pump based on a power plant’s waste heat has the shortest payback period of 7.69 years at a distance of 0 km. On the other hand, the payback period of a heat pump based on geothermal heat showed the shortest payback period of 10.17 year at the distance of 5 km, indicating that heat pumps utilizing geothermal heat were the most effective model if the heat transfer inside the pipe network between the greenhouse and the actual heat source is taken into account.

  10. 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.

  11. Borehole model for simulation transport geothermal heat with heat pipe system and with forced circulation of heat carrier

    Directory of Open Access Journals (Sweden)

    Lenhard Richard

    2012-04-01

    Full Text Available In the call OPVaV-2008/2.2/01-SORO Operational Programme Research and Development - knowledge and technology transfer from research and development into practice (ITMS-26220220057, whose strategic goal is "Device to use low-potential geothermal heat without forced circulation of heat carrier deep in the well "in the Department of Energy laboratory techniques to construct a simulator of transport low potential of geothermal energy in comparative test-drilling in the laboratory. The article describes a device that was designed as a scale model of two deep boreholes each of which withdraws the earth's heat by heat transfer technology and heat carrier. Device using forced circulation of heat carrier will respond in the construction of equipment currently used to transport heat from deep borehole. As the heat carrier will be used CO2. Facilities without using forced circulation of heat carrier, the new technology, which will be used as heat carrier ammonia (NH3.

  12. 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...

  13. Heat pipe and surface mass transfer cooling of hypersonic vehicle structures

    Science.gov (United States)

    Colwell, Gene T.; Modlin, James M.

    1992-01-01

    The problem of determining the feasibility of cooling hypersonic vehicle leading-edge structures exposed to severe aerodynamic surface heating using heat pipe and mass transfer cooling techniques is addressed. A description is presented of a numerical finite-difference-based hypersonic leading-edge cooling model incorporating poststartup liquid metal heat pipe cooling with surface transpiration and film cooling to predict the transient structural temperature distributions and maximum surface temperatures of hypersonic vehicle leading edge. An application of this model to the transient cooling of a typical aerospace plane wing leading-edge section. The results of this application indicated that liquid metal heat pipe cooling alone is insufficient to maintain surface temperatures below an assumed maximum level of 1800 K for about one-third of a typical aerospace plane ascent trajectory through the earth's atmosphere.

  14. Split-core heat-pipe reactors for out-of-pile thermionic power systems.

    Science.gov (United States)

    Niederauer, G.; Lantz, E.; Breitweiser, R.

    1971-01-01

    Description of the concept of splitting a heat-pipe reactor for out-of-core thermionics into two identical halves and using the resulting center gap for reactivity control. Short Li-W reactor heat pipes penetrate the axial reflectors and form a heat exchanger with long heat pipes which wind through the shield to the thermionic diodes. With one reactor half anchored to the shield, the other is attached to a long arm with a pivot behind the shield and swings through a small arc for reactivity control. A safety shim prevents large reactivity inputs, and a fueled control arm drive shaft acts as a power stabilizer. Reactors fueled with U-235C and with U-233C have been studied.-

  15. 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.

  16. Thermal Management of Rapid Fire Gun Breeches: The Case for Heat Pipes

    Science.gov (United States)

    1992-07-01

    at a Depth of 1 Inch ........................................... 23 10. The Effect of the Presence of an Embedded Heat Pipe: Temperature vs. Tim e...desired, the lower the boiling point of the liquid chosen has to be. Exercising the gun barrel heat transfer algorithm of Polk (1980), the effect of the presence of an

  17. Design, fabrication and test of a hydrogen heat pipe. [extruding and grooving 6063-T6 aluminum tubes for cryogenic heat pipes

    Science.gov (United States)

    Alario, J.

    1979-01-01

    Re-entrant groove technology was extended to hydrogen heat pipes. Parametric analyses are presented which optimize the theoretical design while considering the limitations of state-of-the-art extrusion technology. The 6063-T6 aluminum extrusion is 14.6 mm OD with a wall thickness of 1.66 mm and contains 20 axial grooves which surround a central 9.3 mm diameter vapor core. Each axial groove is 0.775 mm diameter with a 0.33 mm opening. An excess vapor reservoir is provided at the evaporator to minimize the pressure containment hazard during ambient storage. Modifications to the basic re-entrant groove profile resulted in improved overall performance. While the maximum heat transport capacity decreased slightly to 103 w-m the static wicking height increased markedly to 4.5 cm. The heat pipe became operational between 20 and 30 K after a cooldown from 77 K without any difficulty. Steady state performance data taken over a 19 to 23 K temperature range indicated: (1) maximum heat transport capacity of 5.4 w-m; (2) static wicking height of 1.42 cm; and (3) overall heat pipe conductance of 1.7 watts/deg C.

  18. Mini-channel evaporator/heat pipe assembly for a chip cooling vapor compression refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Guilherme B.; Barbosa, Jader R. Jr.; Prata, Alvaro T. [Polo - Research Laboratories for Emerging Technologies in Cooling and Thermophysics, Department of Mechanical Engineering, Campus Universitario, Trindade, Federal University of Santa Catarina, Florianopolis, SC 88040900 (Brazil)

    2010-11-15

    We investigate a novel evaporator design for a small-scale refrigeration system whose function is to assist the existing heat pipe technology currently used in chip cooling of portable computers. A heat transfer model for the evaporator/heat pipe assembly was devised specifically for sizing the evaporator in order to keep the chip surface temperature below a certain value. A prototype was tested with R-600a at saturation temperatures of 45 and 55 C, mass flow rates between 0.5 and 1.5 kg h{sup -1} and heat transfer rates between 30 and 60 W. The experimental results demonstrated that the average refrigerant-side heat transfer coefficient is more sensitive to a change in the refrigerant mass flux than to changes in the saturation temperature and heat transfer rate. The agreement between the calculated heat transfer coefficient and the data was within {+-}10% for the conditions evaluated. (author)

  19. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    Science.gov (United States)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  20. Solution of the problem of pipes freezing with account for external heat exchange

    OpenAIRE

    Samarin Oleg Dmitrievich

    2015-01-01

    The author considered the problem statement on the pipes freezing in emergency regimes of building engineering systems and external pipe nets using liquid water as working fluid under boundary conditions of the 3rd type. This problem is a high-priority task now because of actualization of building standards in Russian Federation and because of the increasing requirements to safety and security of heat supply. That’s why it is very important to find a simple but accurate enough dependence for ...

  1. Experimental and Simulation Studies on Cold Welding Sealing Process of Heat Pipes

    Science.gov (United States)

    Li, Yong; Chen, Shengle; Huang, Jinlong; Yan, Yuying; Zeng, Zhixin

    2017-03-01

    Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process (CWSP) is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination ( A 1 B 3 C 1 D 3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity) is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.

  2. 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.

  3. 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

  4. 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 <0.3 ppb oxygen at an approximate operating 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.

  5. Investigation on the performance of a prototype of thermo-electric generation with heat pipe-heat sink

    Directory of Open Access Journals (Sweden)

    Elghool Ali

    2017-01-01

    Full Text Available A significant problem in thermo-electric generators is the thermal design of the heat sink because it affects the performance of thermo-electric modules. As compared to conventional cooling systems, heat pipe heat sink have numerous advantages. Some of these advantages are: high heat-transfer rates; absence of moving parts and lack of auxiliary consumption (passive system. This paper presents the analysis of power generation using the combination of heat pipes and thermo-electric generators. The aim is to improve power output by an appropriate design of the heat sink. The average geometrical parameters of heat sink (fin height, fin space and fin thickness were obtained from data collected from previous studies closely similar to this prototype. The prototype was tested and the temperature, voltage and current data were collected. All data were recorded by using a temperature data recorder, power meter and multimeter. It was found that the highest maximum power output was 1.925 watts at a temperature difference of 85°C. However, the prototype did not achieve the maximum output expected. This was a result of limitation of TEG model (where only one TEG was used and the limitation of the performance of the prototype. The prototype successfully generated enough power to charge a cell phone and laptop when connected to two or three TEGs. Moreover the heat pipe heat sink needs optimization to meet the design output from the manufacturer of the TEG at hot side temperature and cold side temperature

  6. Development and test of two flexible cryogenic heat pipes. [for spaceborne instrument cooling

    Science.gov (United States)

    Wright, J. P.; Brennan, P. J.; Mccreight, C. R.

    1976-01-01

    Results are presented for a comprehensive test program directed toward determining the physical and thermal performance of two flexible cryogenic heat pipes that can provide a highly efficient thermal link between a detector and a space radiator or other cooling system in spacecraft applications. A 100-200 K high-power heat pipe is tested with methane at 100-140 K while a 15-100 K low-temperature pipe is designed for operation with nitrogen and oxygen and is optimized for oxygen in the range 75-90 K. Parametric performance and design tradeoff studies are carried out to determine the optimum geometry and materials for the container and wicking systems. A spiral multiwrap wick in conjunction with braided bellows appears to be a workable solution to the problem of developing highly flexible heat transport devices for cryogenic applications.

  7. Heat transfer enhancement and pumping power optimization using CuO-water nanofluid through rectangular corrugated pipe

    Science.gov (United States)

    Salehin, Musfequs; Ehsan, Mohammad Monjurul; Islam, A. K. M. Sadrul

    2017-06-01

    Heat transfer enhancement by corrugation in fluid domain is a popular method. The rate of improvement is more when it is used highly thermal conductive fluid as heating or cooling medium. In this present study, heat transfer augmentation was investigated numerically by implementing corrugation in the fluid domain and nanofluid as the base fluid in the turbulent forced convection regime. Finite volume method (FVM) was applied to solve the continuity, momentum and energy equations. All the numerical simulations were considered for single phase flow. A rectangle corrugated pipe with 5000 W/m2 constant heat flux subjected to the corrugated wall was considered as the fluid domain. In the range of Reynolds number 15000 to 40000, thermo-physical and hydrodynamic behavior was investigated by using CuO-water nanofluid from 1% to 5% volume fraction as the base fluid through the corrugated fluid domain. Corrugation justification was performed by changing the amplitude of the corrugation and the corrugation wave length for obtaining the increased heat transfer rate with minimum pumping power. For using CuO-water nanofluid, augmentation was also found more in the rectangle corrugated pipe both in heat transfer and pumping power requirement with the increase of Reynolds number and the volume fraction of nanofluid. For the increased pumping power, optimization of pumping power by using nanofluid was also performed for economic finding.

  8. Development and Evaluation of Active Thermal Management System for Lithium-Ion Batteries using Solid-State Thermoelectric Heat Pump and Heat Pipes with Electric Vehicular Applications

    Science.gov (United States)

    Parekh, Bhaumik Kamlesh

    Lithium-Ion batteries have become a popular choice for use in energy storage systems in electric vehicles (EV) and Hybrid electric vehicles (HEV) because of high power and high energy density. But the use of EV and HEV in all climates demands for a battery thermal management system (BTMS) since temperature effects their performance, cycle life and, safety. Hence the BTMS plays a crucial role in the performance of EV and HEV. In this paper, three thermal management systems are studied: (a) simple aluminum as heat spreader material, (b) heat pipes as heat spreader, and (c) advanced combined solid state thermoelectric heat pump (TE) and heat pipe system; these will be subsequently referred to as Design A, B and C, respectively. A detailed description of the designs and the experimental setup is presented. The experimental procedure is divided into two broad categories: Cooling mode and Warming-up mode. Cooling mode covers the conditions when a BTMS is responsible to cool the battery pack through heat dissipation and Warming-up mode covers the conditions when the BTMS is responsible to warm the battery pack in a low temperature ambient condition, maintaining a safe operating temperature of the battery pack in both modes. The experimental procedure analyzes the thermal management system by evaluating the effect of each variable like heat sink area, battery heat generation rate, cooling air temperature, air flow rate and TE power on parameters like maximum temperature of the battery pack (T max), maximum temperature difference (DeltaT) and, heat transfer through heat sink/cooling power of TE (Q c). The results show that Design C outperforms Design A and Design B in spite of design issues which reduce its efficiency, but can still be improved to achieve better performance.

  9. 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.

  10. Development concept for a small, split-core, heat-pipe-cooled nuclear reactor

    Science.gov (United States)

    Lantz, E.; Breitwieser, R.; Niederauer, G. F.

    1974-01-01

    There have been two main deterrents to the development of semiportable nuclear reactors. One is the high development costs; the other is the inability to satisfy with assurance the questions of operational safety. This report shows how a split-core, heat-pipe cooled reactor could conceptually eliminate these deterrents, and examines and summarizes recent work on split-core, heat-pipe reactors. A concept for a small reactor that could be developed at a comparatively low cost is presented. The concept would extend the technology of subcritical radioisotope thermoelectric generators using 238 PuO2 to the evolution of critical space power reactors using 239 PuO2.

  11. 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.

  12. Optimal insulation of pipes and tanks for solar heating systems. Topical report

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G F; Lior, N

    1979-02-01

    A compact and time effective insulation design procedure for solar heating system piping and water-filled thermal storage tanks was developed. Recognizing the particular sensitivity of solar systems to cost, the economic aspect of the problem is treated by a comprehensive present-value life-cycle cost analysis. In the development of the method, a numerical sensitivity analysis was performed to determine the relative effects of all relevant independent variables (within their pertinent ranges) on piping and tank heat transfer coefficient values.

  13. Thermal analysis method of heat pipe embedded equipment panel of communications satellite

    Science.gov (United States)

    Tsunoda, Hiroaki

    The thermal analysis method for the heat pipe embedded equipment panel of communications satellite is presented. The analytical model of the honeycomb sandwich panel embedded with heat pipes is developed and evaluated by the experiments. The new method to predict temperature distribution of the entire communications equipment panel precisely without the increase of computer CPU memory size is proposed. It works even when the large number of communications transponders are put on the panel. The correctness of the method is also confirmed by the experiment.

  14. Study on heat transport rate of an osmotic heat pipe. Effects of the initial concentration on the heat transport limits; Shinto heat pipe no netsu yuso ni kansuru kenkyu. 1. Shoki nodo no netsu yuso genkai ni oyobosu eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Ipposhi, S.; Imura, H. [Kumamoto University, Kumamoto (Japan). Faculty of Engineering

    1998-01-25

    This paper describes an experimental study on. the effects of an initial concentration on a maximum heat transport rate of an osmotic heat pipe operated under the atmospheric pressure. The working fluid was aqueous polyethylene glycol 600 solution and the 18 tubular-type osmosis membranes made of acetyl cellulose were used. The initial concentration was varied from 0.1 to 1.0 kmol/ m{sup 3} with 0.1 kmol/m{sup 3} step. As a result, it is shown that the optimum initial concentration exists for the maximum heat transport rate in the osmotic heat pipe. In addition, the concentrations in the solution riser and downcomer are related to the initial concentration. 11 refs., 11 figs., 2 tabs.

  15. Plastic jacket piping - an important contribution to the development of district heating. Continuous improvement in insulation; KMR. Ein wichtiger Beitrag zur Entwicklung der Fernwaerme. Kontinuierliche Verbesserung der Daemmung

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Allan N.; Falsig, Bent [Logstor A/S, Logstor (Denmark)

    2011-07-15

    A well-functioning district heating system presupposes a pipe system that carries hot water from the power plant to the consumer with minimum heat loss. Plastic jacket piping has since long been the most preferred technology for piping systems. For more than 50 years piping suppliers have cooperated with power suppliers and other players in the branch to continually meet new challenges.

  16. Study on heat transport rate of an osmotic heat pipe. 2nd Report. Flow in a membrane module; Shinto heat pipe no netsuyuso ni kansuru kenkyu. 2. Maku module nai no ryudo ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Ipposhi, S.; Imura, H. [Kumamoto University, Kumamoto (Japan). Faculty of Engineering

    1998-05-25

    An osmotic heat pipe is a top beat mode heat pipe driven by an osmotic force. Therefore, a concentration and a solution flow rate in a membrane module of the osmotic heat pipe are especially of great importance for the heat transport. Thus, the flow in the membrane module is7investigated in detail. As a result, with a ratio of a concentration on the membrane wall to a mixed mean concentration derived semi-theoretically, correlations for the mixed mean concentration, the concentration on the wall and the solution flow rate along the channel in the membrane module were proposed, which can correlate the experimental data from reference (2) within {+-}20% errors. In addition, a method of increasing in the osmotic pumping rate and heat transport rate was proposed. 3 refs., 10 figs., 1 tab.

  17. Experimental investigation of freezing blowby in a copper/water heat pipe

    Science.gov (United States)

    Ochterbeck, J. M.; Peterson, G. P.

    1992-01-01

    An experimental investigation designed to evaluate and better define the overall characteristics of freezing blowby in a copper/water heat pipe was conducted. The results from various rates of restart heat addition and channel blockage, indicate that upon breakthrough the depressurization of the evaporator may result in an effective heat transport capacity far in excess of the steady-state transport limit. The resulting transient conditions imposed on the heat pipe by the effective increased heat transport capacity can cause a loss of liquid in the evaporator and potential dryout. Evidence is presented which indicates that in order to prevent either temporary or permanent dryout, sufficient liquid inventory must be present in the evaporator wicking structure to accommodate the increased transient thermal load and allow sufficient time for the capillary wicking structure to reprime.

  18. Design, development and test of a capillary pump loop heat pipe

    Science.gov (United States)

    Kroliczek, E. J.; Ku, J.; Ollendorf, S.

    1984-06-01

    The development of a capillary pump loop (CPL) heat pipe, including computer modeling and breadboard testing, is presented. The computer model is a SINDA-type thermal analyzer, combined with a pressure analyzer, which predicts the transients of the CPL heat pipe during operation. The breadboard is an aluminum/ammonia transport system which contains multiple parallel evaporator and condenser zones within a single loop. Test results have demonstrated the practicality and reliability of such a design, including heat load sharing among evaporators, liquid inventory/temperature control feature, and priming under load. Transport capability for this system is 65 KW-M with individual evaporator pumps managing up to 1.7 KW at a heat flux of 15 W/sq cm. The prediction of the computer model for heat transport capabilities is in good agreement with experimental results.

  19. Numerical performance study of paraffin wax dispersed with alumina in a concentric pipe latent heat storage system

    Directory of Open Access Journals (Sweden)

    Valan Arasu Amirtham

    2013-01-01

    Full Text Available Latent heat energy storage systems using paraffin wax could have lower heat transfer rates during melting/freezing processes due to its inherent low thermal conductivity. The thermal conductivity of paraffin wax can be enhanced by employing high conductivity materials such as alumina (Al2O3. A numerical analysis has been carried out to study the performance enhancement of paraffin wax with nanoalumina (Al2O3 particles in comparison with simple paraffin wax in a concentric double pipe heat exchanger. Numerical analysis indicates that the charge-discharge rates of thermal energy can be greatly enhanced using paraffin wax with alumina as compared with a simple paraffin wax as PCM.

  20. 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.

  1. 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.)

  2. Experimental performance and parametric analysis of heat pipe heat exchanger for air conditioning application integrated with evaporative cooling

    Science.gov (United States)

    Jadhav, Tushar S.; Lele, Mandar M.

    2017-11-01

    The experimental performance of different heat pipe heat exchanger (HPHX) configurations using distilled water as the working fluid is reported in the present study. The three HPHX configurations in the present investigation include HPHX with single wick structure (HPHX 1), HPHX with composite wick structure (HPHX 2) and hybrid HPHX (HPHX 3) which is the combination of HPHX 1 and HPHX 2. The parameters considered for the parametric analysis of HPHX in all the three configurations are outdoor air dry bulb temperature entering the evaporator section of HPHX (OADBT), return air dry bulb temperature entering the condenser section of HPHX (RADBT), outdoor air velocity (Ve) and return air velocity (Vc). The OADBT is varied between 40 and 24 °C and the outdoor & return air velocities between 0.6 and 2.4 m/s. The parametric analysis of HPHX without evaporative cooling is studied for RADBT = 24 °C whereas RADBT is maintained at 20 °C for the parametric analysis of HPHX integrated with evaporative cooling. In comparison with HPHX without evaporative cooling, the performance of HPHX with evaporative cooling is enhanced by 17% for single wick structure (HPHX 1), 47% for composite wick structure (HPHX 2) and 59% for hybrid HPHX (HPHX 3) for OADBT = 40 °C and at Ve = Vc of 0.6 m/s. The results of the experimental analysis highlights the benefits of HPHX integrated with evaporative cooling for achieving significant energy savings in air conditioning application.

  3. Lighting Energy Saving with Light Pipe in Farm Animal Production

    Directory of Open Access Journals (Sweden)

    Hans von Wachenfelt

    2015-12-01

    Full Text Available The Swedish animal production sector has potential for saving electric lighting of €4-9 million per year using efficient daylight utilisation. To demonstrate this, two light pipe systems, Velux® (house 1 and Solatube® (house 2, are installed in two identical pig houses to determine if the required light intensity, daylight autonomy (DA, and reduced electricity use for illumination can be achieved. In each house, three light sensors continuously measure the indoor daylight relative to an outdoor sensor. If the horizontal illuminance at pig height decreases below 40 lux between 08.00 and 16.00 hours, an automatic control system activates the lights, and electricity use is measured. The daylight factor (DF and DA are determined for each house, based on annual climate data. The mean annual DA of 48% and 55% is achieved for house 1 and house 2, respectively. Light pipes in house 2 have delivered significantly more DA than those in house 1. The most common illuminance range between 0 and 160 lux is recorded in both houses, corresponding to approximately 82% and 83% of daylight time for house 1 and house 2, respectively. Further, the daylighting system for house 2 has produced a uniform DF distribution between 0.05 and 0.59. The results demonstrate that considerable electric energy savings can be achieved in the animal production sector using light pipes. Saving 50% of electric lighting would correspond to 36 GWh or 2520 t CO2 per year for Sweden, but currently the energy savings are not making the investment profitable.

  4. Efficiently-cooled plasmonic amorphous silicon solar cells integrated with a nano-coated heat-pipe plate.

    Science.gov (United States)

    Zhang, Yinan; Du, Yanping; Shum, Clifford; Cai, Boyuan; Le, Nam Cao Hoai; Chen, Xi; Duck, Benjamin; Fell, Christopher; Zhu, Yonggang; Gu, Min

    2016-04-26

    Solar photovoltaics (PV) are emerging as a major alternative energy source. The cost of PV electricity depends on the efficiency of conversion of light to electricity. Despite of steady growth in the efficiency for several decades, little has been achieved to reduce the impact of real-world operating temperatures on this efficiency. Here we demonstrate a highly efficient cooling solution to the recently emerging high performance plasmonic solar cell technology by integrating an advanced nano-coated heat-pipe plate. This thermal cooling technology, efficient for both summer and winter time, demonstrates the heat transportation capability up to ten times higher than those of the metal plate and the conventional wickless heat-pipe plates. The reduction in temperature rise of the plasmonic solar cells operating under one sun condition can be as high as 46%, leading to an approximate 56% recovery in efficiency, which dramatically increases the energy yield of the plasmonic solar cells. This newly-developed, thermally-managed plasmonic solar cell device significantly extends the application scope of PV for highly efficient solar energy conversion.

  5. Visualization study on the enhancement of heat transfer for the groove flat-plate heat pipe with nanoflower coated CuO layer

    Science.gov (United States)

    Xu, Pengfei; Li, Qiang

    2017-10-01

    A flat-plate heat pipe combining the groove structure and the nanoflower structure was developed to improve the wettability of the wick and enhance the phase change heat transfer. The flow and boiling phenomenon of the coolant inside the flat-plate heat pipe was experimentally observed and quantitatively analyzed by the visualization system. The experiment results indicated that the nanoflower coated groove flat-plate heat pipe, owning to its higher wetting area, larger boiling area, and more violent boiling behaviors, possessed a higher two phase heat transfer rate and larger equivalent thermal conductivity under high heat load conditions compared with the groove flat-plate heat pipe. Our work demonstrates a promising approach to address thermal management challenges for high heat flux electronic devices.

  6. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-03-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  7. Experimental and theoretical analysis on the effect of inclination on metal powder sintered heat pipe radiator with natural convection cooling

    Science.gov (United States)

    Cong, Li; Qifei, Jian; Wu, Shifeng

    2017-02-01

    An experimental study and theoretical analysis of heat transfer performance of a sintered heat pipe radiator that implemented in a 50 L domestic semiconductor refrigerator have been conducted to examine the effect of inclination angle, combined with a minimum entropy generation analysis. The experiment results suggest that inclination angle has influences on both the evaporator and condenser section, and the performance of the heat pipe radiator is more sensitive to the inclination change in negative inclined than in positive inclined position. When the heat pipe radiator is in negative inclination angle position, large amplitude of variation on the thermal resistance of this heat pipe radiator is observed. As the thermal load is below 58.89 W, the influence of inclination angle on the overall thermal resistance is not that apparent as compared to the other three thermal loads. Thermal resistance of heat pipe radiator decreases by 82.86 % in inclination of 60° at the set of 138.46 W, compared to horizontal position. Based on the analysis results in this paper, in order to achieve a better heat transfer performance of the heat pipe radiator, it is recommended that the heat pipe radiator be mounted in positive inclination angle positions (30°-90°), where the condenser is above the evaporator.

  8. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-11-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  9. The multistage heat pipe radiator - An advancement in passive cooling technology

    Science.gov (United States)

    Wilson, D. E.; Wright, J. P.

    1977-01-01

    Mathematical models were developed for one-, two-, and three-stage radiator systems to determine optimum stage areas and system performance as a function of such parameters as insulation effectiveness, cold stage temperature, and heat load to the cold and intermediate stages. This study shows that multistage radiator systems can be optimized on the basis of weight or projected area, and that cold stage temperatures as low as 15 K are theoretically possible with present technology levels for insulation emittance. For the baseline design, analyses were performed to determine optimum radiator fin geometry and heat pipe spacing as a function of temperature, material properties, and heat pipe weight. In addition, a ground test system was designed for the baseline design with heat rejection requirements of 10 MW at 35 K on the cold stage and 100 MW at the second stage.

  10. A robust pulsating heat pipe cooler for integrated high power LED chips

    Science.gov (United States)

    Lv, Lucang; Li, Ji; Zhou, Guohui

    2017-11-01

    This paper presents a closed loop pulsating heat pipe (CLPHP) with specific pipe arrangement for high power LED cooling. Two CLPHPs were fabricated and charged with DI water and methanol, respectively. The effects of gravity force and working fluid on the heat transfer performance were investigated carefully. Results show that the water-CLPHP performed better than the methanol-CLPHP, with a minimum thermal resistance of 0.06 °C/W at a 220 W heat load under air natural convection situation. In addition, the gravity force can help the CLPHP starting up and enhance the robustness of the thermal transportation at steady state. Finally, the real application to cooling a 100 W LED chip indicates that the proposed CLPHP can meet the thermal control requirement for integrated high power LEDs. Nevertheless, the low cost and light weight of the proposed CLPHP heat sink are very suitable for the LED lighting devices.

  11. Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) for dual mode applications

    Science.gov (United States)

    Malloy, John; Jacox, Michael; Zubrin, Robert

    1992-07-01

    The Small Externally Fueled Heat-Pipe Thermionic Reactor (SEHPTR) is described in the context of applications as a dual-mode nuclear power source for satellites. The SEHPTR is a thermionic power system based on a reactor with modular fuel elements around cylindrical thermionic heat-pipe modules with diodes for heat rejection. The SEHPTR concept is theorized to be suitable for directly heating hydrogen gas in the core to increase propulsion and reduce orbit-transfer times. The advantages of dual-mode operation of the SEHPTR are listed including enhanced mission safety and performance at relatively low costs. The SEHPTR could provide direct thermal thrust and an integrated stage that symbiotically utilizes electric power, direct thrust, and hydrogen arcjets. The system is argued to be more effective than a nuclear power system designed solely for electrical power production.

  12. Condensation of HFE-7100 vapor in a loop heat pipe having a curvilinear fin

    Directory of Open Access Journals (Sweden)

    Lyulin Yuriy

    2017-01-01

    Full Text Available Vapor condensation of the HFE-7100 in loop heat pipe was studied experimentally and theoretically. Numerical calculations of the vapor condensation on the curvilinear fin have been performed. Numerical, theoretical and experimental data are in a good agreement. Minimal condensate film thickness on the top of the fin has been determined and increases monotonously with the increase in the temperature drop.

  13. Evaluation of conjugate, radial heat transfer in an internally insulated composite pipe

    NARCIS (Netherlands)

    Reurings, C.; Koussios, S.; Bergsma, O.K.; Vergote, K.

    2015-01-01

    In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer

  14. A novel approach of manufacturing Nickel Wicks for loop heat pipes ...

    Indian Academy of Sciences (India)

    Sintered nickel powder is proposed to be used as porous wicks in loop heat pipes used for space applications such as satellites and space crafts. In this work, the manufacturing procedure for tubular wicks through novel Metal Injection Moulding (MIM) route is discussed. Nickel powder, Polypropylene powder and ...

  15. Medical instrument based on a heat pipe for local cavity hypothermia

    Science.gov (United States)

    Vasil'Ev, L. L.; Zhuraviyov, A. S.; Molodkin, F. F.; Khrolenok, V. V.; Zhdanov, V. L.; Vasil'Ev, V. L.; Adamov, S. I.; Tyurin, A. A.

    1996-05-01

    The design and results of tests of an instrument based on a heat pipe for local cavity hypothermia are presented. The instrument is a part of a device for noninvasive nonmedical treatment of inflammatory diseases of the organs of the small pelvis, pathologies of alimentary canal, etc.

  16. Reflux heat-pipe solar receiver for a Stirling dish-electric system

    Science.gov (United States)

    Ziph, B.; Godett, T. M.; Diver, R. B.

    This paper describes the preliminary design of a reflux heat-pipe solar receiver to match the STM4-120 variable swashplate Stirling engine to a test bed concentrator at Sandia National Laboratories Distributed Receiver Test Facility. Performance analysis and other design considerations are presented and discussed.

  17. Reflux heat-pipe solar receiver for a Stirling dish-electric system

    Energy Technology Data Exchange (ETDEWEB)

    Ziph, B.; Godett, T.M.; Diver, R.B.

    1987-01-01

    The feasibility of competitive, modular bulk electric power from the sun is enhanced by the use of a reflux heat-pipe receiver to combine a Stirling engine with a paraboloidal dish concentrator. This combination represents a potential improvement over previous successful demonstrations of Stirling dish-electric technology in terms of enhanced performance, lower cost, and longer life. In the reflux (i.e. gravity assisted) heat-pipe receiver, concentrated solar radiation causes liquid sodium to evaporate, the vapor flows to the Stirling engine heaters where it condenses on the heater tubes. The condensate is returned to and distributed over the receiver by gravity (refluxing) and by capillary forces in a wick lining the receiver. It is essentially an adaptation of sodium heat pipe technology to the peculiar requirements of concentrated solar flux and provides many potential advantages over conventional tube receiver technology. This paper describes the preliminary design of a reflux heat-pipe solar receiver to match the STM4-120 variable swashplate Stirling engine to a Test Bed Concentrator at Sandia National Laboratories Distributed Receiver Test Facility. Performance analysis and other design considerations are presented and discussed.

  18. AUGMENTATION OF RIBS TURBULATORS HEIGHT ON THE HYDROTHERMAL PERFORMANCE OF DOUBLE PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    HUSSAIN H. AL-KAYIEM

    2017-02-01

    Full Text Available Thermal performance of double pipe heat exchanger can be enhanced by imposed turbulence in the annular flow using artificial roughening. This paper presents experimental results on enhancing the heat transfer by artificial roughening using energy promoters installed on the inner surface of the cold flow annulus. An experimental test rig was fabricated having 2.0 m long annular flow test section with 76.2 mm and 34.2 mm outside and inside diameters, respectively. The energy promoters have ribs shape with rectangular cross section. Two cases of rib’s pitch to height ratios, equal to 10 and 15 and three height to hydraulic diameter, equal to 0.0595, 0.083, and 0.107 have been studied. The investigations were carried out at various flow rates within Reynolds number range of 2900 to 21000 in the cold annulus. For each roughening case, the thermal and hydraulic performances wereevaluated by determining Stanton number and the associated pressure drop, respectively. The experimental results showed that enhancement in the heat transfer was combined with a penalty in the pressure drop due to the increase in the friction factor values. The combined hydrothermal enhancement results of the DPHE, in terms of the performance index, indicate that the small height ribs to hydraulic diameter of 0.0595, augmented higher than the large height ribs to hydraulic diameter of 0.107. Hence, it is recommended to use ribs installed on the inner surface of the annulus ribs to hydraulic diameter in the range of 0.06 ± 0.005. Also, it is recommended to investigate further parameters to explore further on the influencing of the ribs on the hydrothermal performance of the DPHE.

  19. Electrowetting-based microfluidic operations on rapid-manufactured devices for heat pipe applications

    Science.gov (United States)

    Hale, Renee S.; Bahadur, Vaibhav

    2017-07-01

    The heat transport capacity of traditional heat pipes is limited by the capillary pressure generated in the internal wick that pumps condensate to the evaporator. Recently, the authors conceptualized a novel heat pipe architecture, wherein wick-based pumping is replaced by electrowetting (EW)-based pumping of microliter droplets in the adiabatic section. An electrowetting heat pipe (EHP) can overcome the capillary limit to heat transport capacity and enable compact, planar, gravity-insensitive, and ultralow power consumption heat pipes that transport kiloWatt heat loads over extended distances. This work develops a novel technique for rapid, scalable fabrication of EW-based devices and studies critical microfluidic operations underlying the EHP, with the objective of predicting the key performance parameters of the EHP. Devices are fabricated on a printed circuit board (PCB) substrate with mechanically-milled electrodes, and a removable polyimide dielectric film. The first set of experiments uncovers the maximum channel gap (1 mm) for reliable EW-based pumping; this parameter determines the heat transport capacity of the EHP, which scales linearly with the channel gap. The second set of experiments uncovers the maximum channel gap (375 microns) at which EW voltages can successfully split droplets. This is an important consideration which ensures EHP operability in the event of unintentional droplet merging. The third set of experiments demonstrate and study EW-induced droplet generation from an open-to-air reservoir, which mimics the interface between the condenser and adiabatic sections of the EHP. The experimental findings predict that planar, water-based EHPs with a (10 cm by 4 mm) cross section can transport 1.6 kW over extended distances (>1 m), with a thermal resistance of 0.01 K W-1.

  20. Effect of heat treatment on the grooving corrosion resistance of ERW pipes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Kwon; Lee, Jae Young; Lim, Soo Hyun; Park, Ji Hwan; Seo, Bo Min; Kim, Seon Hwa [Soonchunhyang University, Asan (Korea, Republic of)

    2002-06-15

    The v-sharp grooving corrosion of ERW(electrical resistance welding) steel pipes limited their wide application in the industry in spite of their high productivity and efficiency. The grooving corrosion is caused mainly by the different microstructures between the matrix and weld that is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. Even though the diminishing of sulfur content is most effective to decrease the susceptibility of grooving corrosion, it requires costly process. In this study, improvement of grooving corrosion resistance was pursuited by post weld heat treatment in the temperature range between 650 .deg. C and 950 .deg. C. Also, the effect of heat input in the welding was investigated. By employing chromnoamperometry and potentiodynamic experiment, the corrosion rate and grooving corrosion index({alpha}) were obtained. It was found that heat treatment could improve the grooving corrosion resistance. Among them, the heat treated at 900 .deg. C and 950 .deg. C had excellent grooving corrosion resistance. The index of heat treated specimen at 900 .deg. C and 950 .deg. C were 1.0, 1.2, respectively, which are almost immune to the grooving corrosion. Potential difference after the heat treatment, between base and weld metal was decreased considerably. While the as-received one measured 61{approx}71 mV, that of the 900 .deg. C heat treated steel pipe measured only 10mV. The results were explained and discussed

  1. High performance heat pipes. Final technical report, June 1, 1978--June 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Eastman, G.Y.

    1979-06-30

    The report describes a program to develop and demonstrate in the 600 to 1600 C temperature range the heat transfer potential of heat pipes using a novel, high performance wick structure. The tunnel wick as conceived at Thermacore makes use of the high capillary pressure provided by the sinterng of finely divided metal powders. Low resistance liquid flow passages, or tunnels, are formed within the sintered powder. Theoretical analysis predicts higher performance for these structures than any demonstrated in the world to date.

  2. Reducing time for construction of district heating pipe systems; Foerkorta Byggtider foer Fjaerrvaermebyggnation

    Energy Technology Data Exchange (ETDEWEB)

    Gille, Hans [AaF Energi och Miljoe AB, Stockholm (Sweden)

    2004-07-01

    To enable shorter time of disturbance during construction of pipes for district heating there are several things that can be done. You have foremost to concentrate on the works taking place in and around the trenches for the pipes, from the first grip with the excavator until the refilling is done. There are also possibilities to reduce time for the welding works by looking over methods used for welding and, above all, when you change from welding with gas to welding with electricity. Welding with gas can be applied to larger pipe dimensions than what is common today. It takes half the time to weld with gas compared to weld with electricity, meaning that cost for welding works can be reduced. The right planning, right organisation on the site and right management of the works are the keys to success. Many of the district heating projects taking place are characterized by long open trenches and the installation of the pipes take place in as long stages as possible for pressure testing. If you can find a possible way to use less covering of the pipes and make the trenches as shallow as possible it will give possibilities to reduce time for interruption and also reduce time for construction works. To be able to reduce the length of and also the time for open trenches there is a possibility to use the same method as when you construct pipes for water and sewage systems. Work and organisation of the site must be planned on the basis of this. The question is it reasonable with such long time of disturbance for a few hundreds meter piping? There are several possibilities and measures which together make it possible to reduce time for open trenches considerably.

  3. THERMOELECTRIC HEAT REMOVAL SYSTEM FOR THE OPERATIONAL STABILISATION OF HEAT PIPES IN A SYSTEM FOR PROVIDING THE THERMAL REGIME OF RADIO ELECTRONIC EQUIPMENT

    Directory of Open Access Journals (Sweden)

    S. A. Peredkov

    2017-01-01

    Full Text Available Objectives. The aim of the study is to conduct an analysis of thermophysical processes in a thermoelectric system used for  providing the thermal regime of electronic equipment located in a cabinet. A cabinet design and thermoelectric system for efficient  heat removal from the condensing part of the heat pipe are  proposed. An additional advantage of the proposed design is the  obviation of significant additional power consumption requirement  for regulating the temperature of radio electronic equipment stored  in the cabinet.A distinctive feature of the constructive realisation is  the presence of an intermediate heat removal.Methods. The three-dimensionality of the problem and mixed boundary conditions lead to the need to develop a calculation  of heat transfer in the elements of the construction of the  thermoelectric system. The numerical calculation method is based on the method of energy balances. The analysis of the heat regimes of  the intermediate heat removal is performed on the basis of a mathematical model for a locally-heated and -cooled restricted plate.Results. A cabinet design and a thermoelectric system for efficient  heat removal from the condensing part of the heat pipe are  proposed. A distinctive feature of the constructive realisation is the  presence of an intermediate heat removal.Conclusion.The capacity of the intermediate heat removal for given dimensions and temperature of the source is weakly affected by its  thickness (in constructively reasonable limits, as well as the  temperature and area of the absorbing side of the thermoelectric  module; the total heat output from the heat source is determined by the dimensions and heat exchange conditions on the free surface of the intermediate heat removal, as well as by the temperature and dimensions of the heat absorbing side of the thermoelectric module. The use of an intermediate heat removal can significantly reduce the thermal load on

  4. Investigation of Counter-Flow in a Heat Pipe-Thermoelectric Generator (HPTEG)

    Science.gov (United States)

    Remeli, Muhammad Fairuz; Singh, Baljit; Affandi, Nor Dalila Nor; Ding, Lai Chet; Date, Abhijit; Akbarzadeh, Aliakbar

    2017-05-01

    This study explores a method of generating electricity while recovering waste heat through the integration of heat pipes and thermoelectric generators (i.e. HPTEG system). The simultaneous waste heat recovery and power generation processes are achieved without the use of any moving parts. The HPTEG system consists of bismuth telluride thermoelectric generators (TEG), which are sandwiched between two finned pipes to achieve a temperature gradient across the TEG for electricity generation. A counter-flow heat exchanger was built using two separate air ducts. The air ducts were thermally coupled using the HPTEG modules. The evaporator section of the heat pipe absorbed the waste heat in a hot air duct. The heat was then transferred across the TEG surfaces. The condenser section of the HPTEG collected the excess heat from the TEG cold side before releasing it to the cold air duct. A 2-kW electrical heater was installed in the hot air duct to simulate the exhaust gas. An air blower was installed at the inlet of each duct to direct the flow of air into the ducts. A theoretical model was developed for predicting the performance of the HPTEG system using the effectiveness-number of transfer units method. The developed model was able to predict the thermal and electrical output of the HPTEG, along with the rate of heat transfer. The results showed that by increasing the cold air velocity, the effectiveness of the heat exchanger was able to be increased from approximately 52% to 58%. As a consequence of the improved heat transfer, maximum power output of 4.3 W was obtained.

  5. Domestic hot water. Measurements of consumption and heat loss from circulation pipes; Varmt brugsvand. Maaling af forbrug og varmetab fra cirkulationsledninger

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, B.; Schroeder, F.; Bergsoee, N.C.

    2009-07-01

    It is likely that the production and distribution of domestic hot water (DHW) in buildings will constitute a dominant share of both the present and in particular future energy design requirements. The goal of this project has been to propose more energy efficient and environmentally friendly solutions for DHW systems based on analyses of existing conditions. The possibilities include new types of circulation pipes, which have the potential of a 40 per cent reduction of heat losses. In addition to the reduction of heat losses inside the building, a low return temperature from the hot water system will have a large impact on the heat losses from the district heating network when the building is being heated by district heating. The results of this project could influence not only future buildings but also existing buildings in case of renovation of the installations. In this project measurements of water and energy consumptions have been carried out in a number of buildings, and heat losses from the production of domestic hot water and the distribution lines have been measured. In addition to the measurements, analyses and simulations have been carried out. Two models have been developed: One of an apartment room with vertical pipes passing through the room, and one of a room above a basement with horizontal heating pipes. The models make it possible to assess how much of the heat loss from the heating pipes is utilised for space heating. The following recommendations are pointed out: 1) In large buildings e.g. apartment buildings and office buildings the technical installations should be provided with meters so that it is possible to separate the energy consumption for DHW, space heating and ventilation, respectively. 2) In new buildings and in case of retrofitting existing buildings, careful planning of the placement and disposition of hot water taps compared with the location of the hot water tank or heat exchanger is recommended. Also, the necessity of a

  6. 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.

  7. 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

  8. Numerical modelling and experimental measurements for a low-temperature district heating substation for instantaneous preparation of DHW with respect to service pipes

    DEFF Research Database (Denmark)

    Brand, Marek; Thorsen, Jan Eric; Svendsen, Svend

    2012-01-01

    as much as possible. This requires a review and improvement of a DH network, in-house substations, and the whole domestic hot water (DHW) supply system, with the focus on user comfort, hygiene, overall cost and energy efficiency. This paper describes some practical approaches to the implementation of low......-temperature district heating (LTDH) with an entry-to-substation temperature around 50 °C. To this end we developed a numerical model for an instantaneous LTDH substation that takes into consideration the effect of service pipes. The model has been verified and can be used for the further optimization of the whole...... concept as well for individual components. The results show that the way that the service pipe is operated has a significant effect on waiting time for DHW, heat loss, and overall cost. Furthermore, the service pipe should be kept warm by using a bypass in order to fulfil the comfort requirements for DHW...

  9. 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...

  10. Thermal performance analysis of a flat heat pipe working with carbon nanotube-water nanofluid for cooling of a high heat flux heater

    Science.gov (United States)

    Arya, A.; Sarafraz, M. M.; Shahmiri, S.; Madani, S. A. H.; Nikkhah, V.; Nakhjavani, S. M.

    2017-10-01

    Experimental investigation on the thermal performance of a flat heat pipe working with carbon nanotube nanofluid is conducted. It is used for cooling a heater working at high heat flux conditions up to 190 kW/m2. The heat pipe is fabricated from aluminium and is equipped with rectangular fin for efficient cooling of condenser section. Inside the heat pipe, a screen mesh was inserted as a wick structure to facilitate the capillary action of working fluid. Influence of different operating parameters such as heat flux, mass concentration of carbon nanotubes and filling ratio of working fluid on thermal performance of heat pipe and its thermal resistance are investigated. Results showed that with an increase in heat flux, the heat transfer coefficient in evaporator section of the heat pipe increases. For filling ratio, however, there is an optimum value, which was 0.8 for the test heat pipe. In addition, CNT/water enhanced the heat transfer coefficient up to 40% over the deionized water. Carbon nanotubes intensified the thermal performance of wick structure by creating a fouling layer on screen mesh structure, which changes the contact angle of liquid with the surface, intensifying the capillary forces.

  11. Convection influence on ice formation process on the evaporator heat pump pipes

    Directory of Open Access Journals (Sweden)

    Maksimov Vyacheslav

    2017-01-01

    Full Text Available The purpose of this research is to identify the effect of convection on the ice growth process on the evaporator of heat pump, and how this growth can affect the heat exchange, and the evaporator performance. An experimental analyse is done on the heat pump station which depends on water as heat source. A 2D model is built in Comsol environment depending on Brinkman and heat transfer equations. The experimental and mathematical simulation results confirm that the ice formation has a negative effect on the evaporator heat exchange efficiency, and the convection has high effect on ice growth rate and this effect increases when the pipe is closer to the heat exchanger base. The effect of block size on the convection and ice growth rate must be studied in future.

  12. Heat transfer performance of water and Nanoencapsulated n-nonadecane based Nanofluids in a double pipe heat exchanger

    Science.gov (United States)

    Doruk, Semahat; Şara, Osman Nuri; Karaipekli, Ali; Yapıcı, Sinan

    2017-06-01

    The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, and nanoencapsulated n-nonadecane based nanofluids in a double pipe heat exchanger were investigated. The results showed that no improvement in overall heat transfer coefficient was observed for the nanofluids containing 0.42% and 0.84% solid volume ratios with reference to the base fluid, while an improvement of about 10% was obtained for the nanofluids containing 1.68% solid volume ratio. It was found that the friction factors for the nanofluids exhibited a slight increase reference to the base fluid. A performance analysis based on constant pumping power was also performed.

  13. The sizes of Flat Plate and Evacuated Tube Collectors with Heat Pipe area as a function of the share of solar system in the heat demand

    Directory of Open Access Journals (Sweden)

    Olek Małgorzata

    2016-01-01

    Full Text Available The popularity of solar collectors in Poland is still increasing. The correct location of the collectors and a relatively high density of solar radiation allow delivering heat even in spite of relatively low ambient temperature. Moreover, solar systems used for heating domestic heat water (DHW in summer allow nearly complete elimination of conventional energy sources (e.g. gas, coal. That is why more and more house owners in Poland decide to install solar system installations. In Poland the most common types of solar collectors are flat plate collectors (FPC and evacuated tube collectors with heat pipe (ETCHP; both were selected for the analysis. The heat demand related to the preparation of hot water, connected with the size of solar collectors’ area, has been determined. The analysis includes FPC and ETCHP and heat demand of less than 10 000 kWh/year. Simulations were performed with the Matlab software and using data from a typical meteorological year (TMY. In addition, a 126–year period of measurements of insolation for Krakow has been taken into account. The HDKR model (Hay, Davis, Klucher, Reindl was used for the calculation of solar radiation on the absorber surface. The monthly medium temperature of the absorber depends on the amount of solar system heat and on the heat demand. All the previously mentioned data were used to determine solar efficiency. Due to the fact that solar efficiency and solar system heat are connected, the calculations were made with the use of an iterative method. Additionally, the upper limit for monthly useful solar system heat is resulted from the heat demand and thus the authors prepared a model of statistical solar system heat deviations based on the Monte Carlo method. It has been found that an increase in the useful solar system heat in reference to the heat demand is associated with more than proportional increase in the sizes of the analyzed surfaces of solar collector types.

  14. Experimental basis for parameters contributing to energy dissipation in piping systems

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, P.; Ware, A.G.

    1985-01-01

    The paper reviews several pipe testing programs to suggest the phenomena causing energy dissipation in piping systems. Such phenomena include material damping, plasticity, collision in gaps and between pipes, water dynamics, insulation straining, coupling slippage, restraints (snubbers, struts, etc.), and pipe/structure interaction. These observations are supported by a large experimental data base. Data are available from in-situ and laboratory tests (pipe diameters up to about 20 inches, response levels from milli-g's to responses causing yielding, and from excitation wave forms including sinusoid, snapback, random, and seismic). A variety of pipe configurations have been tested, including simple, bare, straight sections and complex lines with bends, snubbers, struts, and insulation. Tests have been performed with and without water and at zero to operating pressure. Both light water reactor and LMFBR piping have been tested.

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

    OpenAIRE

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

    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...

  16. Heat transfer enhancement in sphere-packed pipes under high Reynolds number conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seto, Nao [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-02, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)], E-mail: nseto@karma.qse.tohoku.ac.jp; Yuki, Kazuhisa; Hashizume, Hidetoshi [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-02, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Sagara, Akio [National Institute for Fusion Science, Oroshicho, 322-6, Toki, 509-5292 Gifu (Japan)

    2008-12-15

    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 Re{sub D} = 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.

  17. Experimental Investigation of Thermal Performance in a Concentric-Tube Heat Exchanger with Wavy Inner Pipe

    Science.gov (United States)

    Çakmak, Gülşah; Yücel, H. Lütfi; Argunhan, Zeki; Yıldız, Cengiz

    2012-06-01

    In this article, the heat transfer, friction factor, and thermal performance factor characteristics of a concentric-tube heat exchanger are examined experimentally. A wavy inner pipe is mounted in the tube with the purpose of generating swirl flow that would help to increase the heat transfer rate of the tube. The examination is performed for a Reynolds number ranging from 2700 to 8800. An empirical correlation is also formulated to match with experimental data of the Nusselt number using the Wilson plot method. In addition, to obtain the real benefits in using the swirl generator at a constant pumping power, the thermal enhancement factor is also determined. Over the range considered, the increases in the Nusselt number, friction factor, and thermal performance factor are found to be, respectively, about 113 %, 81 %, and 196 % higher than those obtained from a smooth-surface inner pipe.

  18. Cylindrical parabolic concentrator with heating pipe; Concentrador cilindrico parabolico com tubo de calor

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, K.A.R. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Zanardi, M.A. [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia

    1990-12-31

    This paper presents a numerical analytical model for cylindrical parabolic solar collector with absorber in the form of heat pipe enveloped by a glass tube to reduce the thermal losses. The model also accounts for the thermal conductive, convective and radiative losses. The model for the heat pipe includes heat and flow in the porous wick as well as the liquid and vapor phases. The numerical results obtained using the present model were compared with experiments performed on a collector having aperture area of 0.4 m{sup 2} and concentration factor of 5.0. The experiments were performed using two collector orientations, E - W and N - S. The comparisons indicated good agreement and confirmed the validity of the proposed model. (author). 11 refs., 7 figs

  19. Design, fabrication and test of a hydrogen heat pipe. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Alario, J.

    1979-02-01

    Re-entrant groove technology was extended to hydrogen heat pipes. Parametric analyses are presented which optimize the theoretical design while considering the limitations of state-of-the-art extrusion technology. The 6063-T6 aluminum extrusion is 14.6 mm OD with a wall thickness of 1.66 mm and contains 20 axial grooves which surround a central 9.3 mm diameter vapor core. Each axial groove is 0.775 mm diameter with a 0.33 mm opening. An excess vapor reservoir is provided at the evaporator to minimize the pressure containment hazard during ambient storage. Modifications to the basic re-entrant groove profile resulted in improved overall performance. While the maximum heat transport capacity decreased slightly to 103 w-m the static wicking height increased markedly to 4.5 cm. The heat pipe became operational between 20 and 30 K after a cooldown from 77 K without any difficulty. Steady state performance data taken over a 19 to 23 K temperature range indicated: (1) maximum heat transport capacity of 5.4 w-m; (2) static wicking height of 1.42 cm; and (3) overall heat pipe conductance of 1.7 watts/deg C.

  20. 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

    2016-11-01

    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.

  1. Evaluation of heat transfer and exergy loss in a concentric double pipe exchanger equipped with helical wires

    Energy Technology Data Exchange (ETDEWEB)

    Akpinar, Ebru Kavak [Mechanical Engineering Department, Firat University, TR-23119 Elazig (Turkey)

    2006-11-15

    In this study, the effects on heat transfer, friction factor and dimensionless exergy loss were investigated experimentally by mounting helical (spring shaped) wires of different pitch in the inner pipe in a double pipe heat exchanger. In the experiments, hot (air) and cold (water) fluids flowed through the inner pipe and annulus, respectively. The experiments were performed for both parallel and counter current flow modes of the fluids at Reynolds numbers between 6500 and 13,000. An augmentation of up to 2.64 times in Nusselt number compared to the empty pipe was obtained in the helical system. The increase in friction factor was about 2.74 times that of the empty pipe, depending on Reynolds number and the pitch or helical number. An augmentation of up to 1.16 times in the dimensionless exergy loss compared to the empty pipe was obtained in the helical system. Some empirical correlations expressing the results were also derived and discussed. (author)

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

    Science.gov (United States)

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

    2017-11-01

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

  3. Thermodynamic Peculiar Features of Steam Flow in Heat Pipe-Line

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2008-01-01

    Full Text Available The paper contains results of the investigations pertaining to thermodynamic steam characteristics of the operating pipe-line, analysis of steam flow regimes, influence of heat losses on temperature fall along the length. The eh-diagram presents changes in e and e values which are caused by decrease of mean temperatures with the given pressure value at pipe-line inlet and outlet. The paper shows that steam enthalpy at the pipeline outlet depends on inlet enthalpy, ambient temperature and entropy difference.The constructed nomograph makes it possible to forecast steam temperature fall in the pipe-line with the purpose to ensure more efficient usage of its thermodynamic potential.

  4. Thermal behavior of heat-pipe-assisted alkali-metal thermoelectric converters

    Science.gov (United States)

    Lee, Ji-Su; Lee, Wook-Hyun; Chi, Ri-Guang; Chung, Won-Sik; Lee, Kye-Bock; Rhi, Seok-Ho; Jeong, Seon-Yong; Park, Jong-Chan

    2017-06-01

    The alkali-metal thermal-to-electric converter (AMTEC) changes thermal energy directly into electrical energy using alkali metals, such as sodium and potassium, as the working fluid. The AMTEC system primarily consists of beta-alumina solid electrolyte (BASE) tubes, low and high-pressure chambers, an evaporator, and a condenser and work through continuous sodium circulation, similar to conventional heat pipes. When the sodium ions pass through the BASE tubes with ion conductivity, this ion transfer generates electricity. The efficiency of the AMTEC directly depends on the temperature difference between the top and bottom of the system. The optimum design of components of the AMTEC, including the condenser, evaporator, BASE tubes, and artery wick, can improve power output and efficiency. Here, a radiation shield was installed in the low-pressure chamber of the AMTEC and was investigated experimentally and numerically to determine an optimum design for preventing radiation heat loss through the condenser and the wall of AMTEC container. A computational fluid dynamics (CFD) simulation was carried out to decide the optimum size of the low-pressure chamber. The most suitable height and diameter of the chamber were 270 mm and 180 mm, respectively, with eight BASE tubes, which were 150 mm high, 25 mm in diameter, and 105 mm in concentric diameter. Increasing the temperature ratio (T Cond /T B ) led to high power output. The minimum dimensionless value (0.4611) for temperature (T Cond /T B ) appeared when the radiation shield was made of 500-mesh nickel. Simulation results for the best position and shape for the radiation shield, revealed that maximum power was generated when a stainless steel shield was installed in between the BASE tubes and condenser.

  5. Thermal behavior of heat-pipe-assisted alkali-metal thermoelectric converters

    Science.gov (United States)

    Lee, Ji-Su; Lee, Wook-Hyun; Chi, Ri-Guang; Chung, Won-Sik; Lee, Kye-Bock; Rhi, Seok-Ho; Jeong, Seon-Yong; Park, Jong-Chan

    2017-11-01

    The alkali-metal thermal-to-electric converter (AMTEC) changes thermal energy directly into electrical energy using alkali metals, such as sodium and potassium, as the working fluid. The AMTEC system primarily consists of beta-alumina solid electrolyte (BASE) tubes, low and high-pressure chambers, an evaporator, and a condenser and work through continuous sodium circulation, similar to conventional heat pipes. When the sodium ions pass through the BASE tubes with ion conductivity, this ion transfer generates electricity. The efficiency of the AMTEC directly depends on the temperature difference between the top and bottom of the system. The optimum design of components of the AMTEC, including the condenser, evaporator, BASE tubes, and artery wick, can improve power output and efficiency. Here, a radiation shield was installed in the low-pressure chamber of the AMTEC and was investigated experimentally and numerically to determine an optimum design for preventing radiation heat loss through the condenser and the wall of AMTEC container. A computational fluid dynamics (CFD) simulation was carried out to decide the optimum size of the low-pressure chamber. The most suitable height and diameter of the chamber were 270 mm and 180 mm, respectively, with eight BASE tubes, which were 150 mm high, 25 mm in diameter, and 105 mm in concentric diameter. Increasing the temperature ratio ( T Cond /T B ) led to high power output. The minimum dimensionless value (0.4611) for temperature ( T Cond /T B ) appeared when the radiation shield was made of 500-mesh nickel. Simulation results for the best position and shape for the radiation shield, revealed that maximum power was generated when a stainless steel shield was installed in between the BASE tubes and condenser.

  6. Inverse problem of estimating transient heat transfer rate on external wall of forced convection pipe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wen-Lih; Yang, Yu-Ching; Chang, Win-Jin; Lee, Haw-Long [Clean Energy Center, Department of Mechanical Engineering, Kun Shan University, Yung-Kang City, Tainan 710-03 (China)

    2008-08-15

    In this study, a conjugate gradient method based inverse algorithm is applied to estimate the unknown space and time dependent heat transfer rate on the external wall of a pipe system using temperature measurements. It is assumed that no prior information is available on the functional form of the unknown heat transfer rate; hence, the procedure is classified as function estimation in the inverse calculation. The accuracy of the inverse analysis is examined by using simulated exact and inexact temperature measurements. Results show that an excellent estimation of the space and time dependent heat transfer rate can be obtained for the test case considered in this study. (author)

  7. Application Feasibility Evaluation on a Co-axial Piping for Intermediate Heat Transport System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Gyu; Kim, Jong Bum; Lee, Jae Han

    2008-02-15

    The IHX in a pool-type SFR system transfers heat from the primary high temperature sodium to the intermediate cold temperature sodium. The upper internal structure of IHX is a co-axial piping to form the flow path of both the secondary high temperature and low temperature sodium. The co-axial piping of the IHX consists of a central downcomer and riser for incoming and outgoing intermediate sodium, respectively. The IHXs of a pool-type SFR are supported at the top surface of the reactor head which is low temperature condition relatively. Therefore, the temperature distribution of a co-axial piping including the IHX support structure may induce the complicated severe thermal stress distribution. In this study, the structural features of a co-axial piping are investigated and the advanced conceptual design to accommodate the IHTS piping expansion and the severe thermal stress is proposed. It is shown through the structural analysis that the advanced design concept is effective to reduce the thermal stress and the preliminary structural integrity by considering the refuel cycle is assured.

  8. 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.

  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. Full visualization and startup performance of an ammonia pulsating heat pipe

    Directory of Open Access Journals (Sweden)

    Zhihu Xue

    2013-12-01

    Full Text Available In this paper, a novel study on full visualization and startup performances of pulsating heat pipe using ammonia as working fluid are experimented. The tested pulsating heat pipe, consisting of 6 turns, is fully made of quartz glass tubes with 6 mm outer diameter and 2 mm inner diameter. The filling ratio is 70%. Wall temperature fluctuations of several key positions are recorded under a series charge of heat inputs. The visualization investigation is conducted to observe the oscillations and circulation flows with the advantage of high quality digital video camera, by which the unique thermodynamic behaviors are able to recognize and analyze more easily. The experimental results show that the startup power required by the ammonia Pulsating Heat Pipe (PHP is very small, owing to particular identities of ammonia. It is observed that there are also some unevenly distributions in slug-train during initial and operating state. Phenomena such as circulation flows and local oscillations coupling breaking up of bubbles and formation of slugs are observed.

  11. Heat pipe radiation cooling (HPRC) for high-speed aircraft propulsion. Phase 2 (feasibility) final report

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.A.; Merrigan, M.A.; Elder, M.G.; Sena, J.T.; Keddy, E.S. [Los Alamos National Lab., NM (United States); Silverstein, C.C. [CCS Associates, Bethel Park, PA (United States)

    1994-03-25

    The National Aeronautics and Space Administration (NASA), Los Alamos National Laboratory (Los Alamos), and CCS Associates are conducting the Heat Pipe Radiation Cooling (HPRC) for High-Speed Aircraft Propulsion program to determine the advantages and demonstrate the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This innovative 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 adjacent external surfaces. HPRC is viewed as an alternative (or complementary) cooling technique to the use of pumped cryogenic or endothermic fuels to provide regenerative fuel or air cooling of the hot surfaces. The HPRC program has been conducted through two phases, an applications phase and a feasibility phase. The applications program (Phase 1) included concept and assessment analyses using hypersonic engine data obtained from US engine company contacts. The applications phase culminated with planning for experimental verification of the HPRC concept to be pursued in a feasibility program. The feasibility program (Phase 2), recently completed and summarized in this report, involved both analytical and experimental studies.

  12. Solution of the problem of pipes freezing with account for external heat exchange

    Directory of Open Access Journals (Sweden)

    Samarin Oleg Dmitrievich

    2015-01-01

    Full Text Available The author considered the problem statement on the pipes freezing in emergency regimes of building engineering systems and external pipe nets using liquid water as working fluid under boundary conditions of the 3rd type. This problem is a high-priority task now because of actualization of building standards in Russian Federation and because of the increasing requirements to safety and security of heat supply. That’s why it is very important to find a simple but accurate enough dependence for the freezing time in pipe nets. The system of differential and algebraic equations of external heat exchange and internal heat transfer with account for heat ingress from hydraulic friction at water flow and Stephan’s condition on the freezing front is presented. The analytical solution of the given system is obtained as a quadrature for the dependence of the current coordinate of the freezing front. The results of numerical calculation of the corresponding integral are shown and their comparison with the former author’s researches concerning the solution of the considered problem at the boundary conditions of the 1st type is conducted. It is shown that the account of intensity of external heat exchange causes retarding of freezing because of adding thermal resistance on the external surface of the pipe. The former author’s conclusion on the existence of the ultimate water velocity, when freezing doesn’t take place, is verified. The area of use of the presented dependence is found. The obtained model contains is easy to use in engineering practice, especially during preliminary calculations. The presentation is illustrated with numerical and graphical examples.

  13. New stopper system for district heating pipes; Absperrblasen: Neuartiges Absperrsystem fuer Fernwaermetrassen

    Energy Technology Data Exchange (ETDEWEB)

    Berger, W.; Sperling, E. [Forschungsinstitut fuer Tief- und Rohrleitungsbau, Weimar (Germany)

    2003-03-01

    Repairs to district heating pipes, such as the replacement of faulty gate valves, entail taking the area affected and the following sections of the pipe out of service. Whole urban areas may be cut off from their hot water supply because of such measures. The short-term shutdown of district heating pipes, draining, disposing of and reprocessing the heating water involves high costs. A new isolation system has been developed by the Weimar-based Excavation and Pipelaying Research Institute (Forschungsinstitut fuer Tief- und Rohrleitungsbau Weimar e.V.) in conjunction with Huetz and Baumgarten GmbH and Co. KG., Remscheid, by using an established gas supply system for a new application. The fundamental suitability of a new inflatable MDS stopper by Kleiss and Co. BV, Zwijndrecht/Netherlands for use in district heating was tested. Several inflatable MDS stoppers with diameters of DN 200 and DN 400 were used. Their surface coatings and the connection between the filling hose and the envelope differed. Medium temperatures were 60 C and 90 C and pipe pressures from 0.5 to 2.4 bar. The series of tests revealed that the inflatable stoppers could withstand high temperature and pressure loads if modified appropriately. The resistance of the surface of the inflatable stopper to abrasion was enhanced by applying an additional PU coating. This also had a positive effect of the heat resistance of the basic material. However, the results only apply to single use of the inflatable stoppers. Multiple use may lead to failures. (orig.) [German] Bei Reparatur- und Einbindearbeiten an Fermwaermeleitungen, wie dem Auswechseln von defekten Schiebern, muessen der betroffene Bereich und die folgenden Trassenabschnitte ausser Betrieb genommen werden. Dies verursacht hohe Kosten. Neue Absperrblasen wurden auf ihre Eignung fuer die Verwendung in Fernwaermetrassen untersucht, um Reparaturzeiten und Kosten zu verringern. (orig.)

  14. Numerical Investigation of Deviation of Phase Change Characteristics of Horizontal and Vertical Flat Heat Pipe Configurations

    Directory of Open Access Journals (Sweden)

    Rakesh Hari

    2015-12-01

    Full Text Available The flow characteristics in the porous wick of a flat heat pipe subjected to boiling and condensation are analysed here using two-phase mixture model. Steady laminar boundary layer flow in the capillary wick structure is considered for both vertical and horizontal orientations. The governing boundary layer partial differential equations are simplified using similarity transformation. The transformed equations are then solved numerically by using shooting iterative technique. Investigation was carried out for the effects of the involved parameters such as saturation and temperature across the boundary layer. The behaviour of non-dimensional numbers due to the orientation of the heat pipe is also discussed. The study confirms that orientation plays a significant role in flow and temperature field.

  15. Comprehensive optimization of a heat pipe radiator assembly filled with ammonia or acetone

    Energy Technology Data Exchange (ETDEWEB)

    Vlassov, Valeri V.; De Sousa, Fabiano L.; Takahashi, Walter K. [National Institute for Space Research (INPE/DMC), Av. dos Astronautas, 1758. S.J.Campos, SP, 12227-010 (Brazil)

    2006-11-15

    Optimal mass characteristics for a heat pipe radiator assembly for space application are investigated. The assembly consists of the heat pipe itself, an evaporator saddle and a radiator. The internal HP geometry and the dimensions of the saddle and radiator panel are the variables to be optimized. Operational and structural constraints are considered and the assembly is optimized for different operational modes in 0g and 1g gravity conditions. A new global search metaheuristic, called generalized extremal optimization, was used as the optimization tool. The results show that under certain combinations of input parameters the assembly with acetone HP can be more weight effective than the one with ammonia, in spite of the liquid transport factor criterion indicates an opposite trend. (author)

  16. Mathematical modeling and analysis of heat pipe start-up from the frozen state

    Energy Technology Data Exchange (ETDEWEB)

    Jang, J.H.; Faghri, A. [Wright State Univ., Dayton, OH (United States); Chang, W.S.; Mahefkey, E.T. [Wright Research and Development Center, Wright-Patterson, OH (United States)

    1989-08-01

    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.

  17. 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.

  18. Thermal analysis method of high capacity communications satellite with heat pipes

    Science.gov (United States)

    Tsunoda, Hiroaki; Nakajima, Katsuhiko; Miyasaka, Akihiro

    Thermal analysis method for heat pipe embedded communications equipment panel is treated in this paper. The main problem of the thermal analysis is how to construct the mathematical model under the limitation of computer CPU memory size. The mathematical model for the heat pipe embedded panel is first established based on the experiments. The essence of this method is to divide panel area into several small regions and perform thermal analysis independently using the fact of low thermal conductivity of honeycomb sandwich panel. To check the correctness of this method, the experiment using the test panel which thermally simulates the north communications equipment panel of two-ton class high capacity communications satellite has been conducted. The experiment shows the method works well.

  19. Nuclear energy and process heating

    Energy Technology Data Exchange (ETDEWEB)

    Kozier, K.S

    1999-10-01

    Nuclear energy generated in fission reactors is a versatile commodity that can, in principle, satisfy any and all of mankind's energy needs through direct or indirect means. In addition to its dominant current use for electricity generation and, to a lesser degree, marine propulsion, nuclear energy can and has been used for process heat applications, such as space heating, industrial process heating and seawater desalination. Moreover, a wide variety of reactor designs has been employed to this end in a range of countries. From this spectrum of experience, two design approaches emerge for nuclear process heating (NPH): extracting a portion of the thermal energy from a nuclear power plant (NPP) (i.e., creating a combined heat and power, or CHP, plant) and transporting it to the user, or deploying dedicated nuclear heating plants (NHPs) in generally closer proximity to the thermal load. While the former approach is the basis for much of the current NPH experience, considerable recent interest exists for the latter, typically involving small, innovative reactor plants with enhanced and passive safety features. The high emphasis on inherent nuclear safety characteristics in these reactor designs reflects the need to avoid any requirement for evacuation of the public in the event of an accident, and the desire for sustained operation and investment protection at minimum cost. Since roughly 67% of mankind's primary energy usage is not in the form of electricity, a vast potential market for NPH systems exists, particularly at the low-to-moderate end-use temperatures required for residential space heating and several industrial applications. Although only About 0.5% of global nuclear energy production is presently used for NPH applications, an expanded role in the 21st century seems inevitable, in part, as a measure to reduce greenhouse gas emissions and improve air quality. While the technical aspects of many NPH applications are considered to be well proven, a

  20. Analytical Investigation of the Heat-Transfer Limits of a Novel Solar Loop-Heat Pipe Employing a Mini-Channel Evaporator

    Directory of Open Access Journals (Sweden)

    Thierno M. O. Diallo

    2018-01-01

    Full Text Available This paper presents an analytical investigation of heat-transfer limits of a novel solar loop-heat pipe developed for space heating and domestic hot water use. In the loop-heat pipe, the condensate liquid returns to the evaporator via small specially designed holes, using a mini-channel evaporator. The study considered the commonly known heat-transfer limits of loop-heat pipes, namely, the viscous, sonic, entrainment, boiling and heat-transfer limits due to the two-phase pressure drop in the loop. The analysis considered the main factors that affect the limits in the mini-channel evaporator: the operating temperature, mini-channel aspect ratio, evaporator length, evaporator inclination angle, evaporator-to-condenser height difference and the dimension of the holes. It was found that the entrainment is the main governing limit of the system operation. With the specified loop design and operational conditions, the solar loop-heat pipe can achieve a heat-transport capacity of 725 W. The analytical model presented in this study can be used to optimise the heat-transfer capacity of the novel solar loop-heat pipe.

  1. Experimental investigation and CFD analysis of a air cooled condenser heat pipe

    Directory of Open Access Journals (Sweden)

    Annamalai Selvan Arul

    2011-01-01

    Full Text Available In the present work a heat pipe of one meter length and 0.031m outer diameter was constructed and the experiments are conducted to determine the surface and vapour temperature at steady and transient conditions for two different input power in the evaporator section and cooling the condenser section by air. A CFD analysis was also carried and the results under steady state conditions are compared with the results obtained from the experiments and reported in this paper.

  2. Experimental Investigation of an Indirect Evaporative Cooler Consisting of a Heat Pipe Embedded in Porous Ceramic

    Directory of Open Access Journals (Sweden)

    S. Riffat

    2004-12-01

    Full Text Available An indirect evaporative cooler incorporating a porous ceramic and a heat pipe was described. Experiments were carried out to examine the effects of various ceramic properties, such as porosity, wall thickness, and outside diameter. Use of the cooler for a chilled ceiling in an environmental chamber was also investigated.Atemperature drop of 3.8oC per square metre of ceramic surface area was achieved for an 18 m chamber.

  3. 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.)

  4. Start-up Characteristics of Swallow-tailed Axial-grooved Heat Pipe under the conditions of Multiple Heat Sources

    Science.gov (United States)

    Zhang, Renping

    2017-12-01

    A mathematical model was developed for predicting start-up characteristics of Swallow-tailed Axial-grooved Heat Pipe under the conditions of Multiple Heat Sources. The effects of heat capacitance of heat source, liquid-vapour interfacial evaporation-condensation heat transfer, shear stress at the interface was considered in current model. The interfacial evaporating mass flow rate is based on the kinetic analysis. Time variations of evaporating mass rate, wall temperature and liquid velocity are studied from the start-up to steady state. The calculated results show that wall temperature demonstrates step transition at the junction between the heat source and non-existent heat source on the evaporator. The liquid velocity changes drastically at the evaporator section, however, it has slight variation at the evaporator section without heat source. When the effect of heat source is ignored, the numerical temperature demonstrates a quicker response. With the consideration of capacitance of the heat source, the data obtained from the proposed model agree well with the experimental results.

  5. Condensation on Highly Superheated Surfaces: Unstable Thin Films in a Wickless Heat Pipe.

    Science.gov (United States)

    Kundan, Akshay; Nguyen, Thao T T; Plawsky, Joel L; Wayner, Peter C; Chao, David F; Sicker, Ronald J

    2017-03-03

    A wickless heat pipe was operated on the International Space Station to provide a better understanding of how the microgravity environment might alter the physical and interfacial forces driving evaporation and condensation. Traditional heat pipes are divided into three zones: evaporation at the heated end, condensation at the cooled end, and intermediate or adiabatic in between. The microgravity experiments reported herein show that the situation may be dramatically more complicated. Beyond a threshold heat input, there was a transition from evaporation at the heated end to large-scale condensation, even as surface temperatures exceeded the boiling point by 160 K. The hotter the surface, the more vapor was condensed onto it. The condensation process at the heated end is initiated by thickness and temperature disturbances in the thin liquid film that wet the solid surface. Those disturbances effectively leave the vapor "superheated" in that region. Condensation is amplified and sustained by the high Marangoni stresses that exist near the heater and that drive liquid to cooler regions of the device.

  6. Simulation and Experimental Investigation of Thermal Performance of a Miniature Flat Plate Heat Pipe

    Directory of Open Access Journals (Sweden)

    R. Boukhanouf

    2013-01-01

    Full Text Available This paper presents the results of a CFD analysis and experimental tests of two identical miniature flat plate heat pipes (FPHP using sintered and screen mesh wicks and a comparative analysis and measurement of two solid copper base plates 1 mm and 3 mm thick. It was shown that the design of the miniature FPHP with sintered wick would achieve the specific temperature gradients threshold for heat dissipation rates of up to 80 W. The experimental results also revealed that for localised heat sources of up to 40 W, a solid copper base plate 3 mm thick would have comparable heat transfer performances to that of the sintered wick FPHP. In addition, a marginal effect on the thermal performance of the sintered wick FPHP was recorded when its orientation was held at 0°, 90°, and 180° and for heat dissipation rates ranging from 0 to 100 W.

  7. Application of LBB to high energy piping systems in operating PWR

    Energy Technology Data Exchange (ETDEWEB)

    Swamy, S.A.; Bhowmick, D.C. [Westinghouse Nuclear Technology Division, Pittsburgh, PA (United States)

    1997-04-01

    The amendment to General Design Criterion 4 allows exclusion, from the design basis, of dynamic effects associated with high energy pipe rupture by application of leak-before-break (LBB) technology. This new approach has resulted in substantial financial savings to utilities when applied to the Pressurized Water Reactor (PWR) primary loop piping and auxiliary piping systems made of stainless steel material. To date majority of applications pertain to piping systems in operating plants. Various steps of evaluation associated with the LBB application to an operating plant are described in this paper.

  8. Free convection flow and heat transfer in pipe exposed to cooling

    Energy Technology Data Exchange (ETDEWEB)

    Mme, Uduak Akpan

    2010-10-15

    One of the challenges with thermal insulation design in subsea equipment is to minimize the heat loss through cold spots during production shut down. Cold spots are system components where insulation is difficult to implement, resulting in an insulation discontinuity which creates by nature a thermal bridge. It is difficult to avoid cold spots or thermal bridges in items like sensors, valves, connectors and supporting structures. These areas of reduced or no insulation are referred to as cold spots. Heat is drained faster through these spots, resulting in an increased local fluid density resulting in an internal fluid flow due to gravity and accelerated cool- down. This natural convection flow is important for both heat loss and internal distribution of the temperature. This thesis is presenting both experimental work and modelling work. A series of cool down tests and Computational Fluid Dynamics (CFD) simulations of these tests are presented. These tests and simulations were carried out in order to understand the flow physics involved in heat exchange processes caused by free convection flow in pipe exposed to cooling. Inclination of the pipe relative to the direction of gravity and temperature difference between cooling water and internal pipe water are the two main parameters investigated in this study. The experimental heat removal and temperature field is discussed and further interpreted by means of computational fluid dynamics. For prediction of the evolvement of the local temperature and heat flow, selection of an appropriate turbulence model is critical. Hence, different models and wall functions are investigated. The predicted temperature profiles and heat extraction rates are compered to the experiments for the selected turbulence models. Our main conclusions, supported by our experimental and CFD results, include: (i) Heat transfer from a localized cold spot in an inclined pipe is most efficient when the pipe orientation is close to horizontal. As the

  9. A DISCUSSION ON UTILIZATION OF HEAT PIPE AND VAPOUR CHAMBER TECHNOLOGY AS A PRIMARY DEVICE FOR HEAT EXTRACTION FROM PHOTON ABSORBER SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Suthar, K. J.; Lurie, Alexander M.; Den Hartog, P.

    2016-01-01

    Heat pipes and vapour chambers work on heat exchange phenomena of two-phase flow and are widely used for in-dustrial and commercial applications. These devices offer very high effective thermal conductivities (5,000-200,000 W/m/K) and are adaptable to various sizes, shapes, and ori-entations. Although they have been found to be an excel-lent thermal management solution for laptops, satellites, and many things in-between, heat pipes and vapour cham-bers have yet to be adopted for use at particle accelerator facilities where they offer the possibility of more compact and more efficient means to remove heat from unwanted synchrotron radiation. As with all technologies, there are inherent limitations. Foremost, they are limited by practi-cality to serve as local heat transfer devices; heat transfer over long distances is likely best provided by other means. Heat pipes also introduce unique failure modes which must be considered.

  10. Thermal effects of planar high temperature heat pipes in solid oxide cell stacks operated with internal methane reforming

    Science.gov (United States)

    Dillig, Marius; Plankenbühler, Thomas; Karl, Jürgen

    2018-01-01

    The presented paper contributes to developing a new thermal control approach for solid oxide cell (SOC) stacks and systems. Integrating planar liquid metal heat pipes to the interconnector structure of the stacks targets a reduction of internal temperature gradients and an enhanced heat extraction from the stack. This work applies 3-D CFD-modelling to discuss the thermal effects of integrated heat pipes in solid oxide cell stacks, in order to evaluate the possible benefits in terms of temperature gradient reduction and heat removal as well as the resulting benefits for stacks and systems. The stack model set-up is described and its functioning is validated with experimental results from thermal short stack measurements with integrated heat pipe interconnectors. The simulation results are discussed with respect to the possible benefits for full-scale stacks of different cell size, in particular regarding internal heat recycling and the beneficial reduction of air ratios.

  11. 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.

  12. Heat pump cuts energy use

    Energy Technology Data Exchange (ETDEWEB)

    Barnwell, J.; Morris, C.P.

    1982-07-01

    It is shown how energy use can be cut by nearly half by using a heat pump installation in operation of a butane splitter. The technique has been used successfully for separation of other close boiling materials, i.e. ethane/ethylene, propane/propylene, and also for deisohexanizers. Compared to a conventional fractionator, the heat pump increases inside battery limit capital cost for which increase the payout time is less than one year. In this paper the effects of using a heat pump is evaluated as applied to a 35,000 bpsd butane splitter based on three alternative schemes: a conventional fractionation; overhead vapor recompression fractionation; and bottoms flash recompression fractionation. 2 refs.

  13. 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.

  14. Energy savings in cooling systems through use of new heat exchanger type with flat aluminium pipes and fins; Energibesparelser i koeleanlaeg ved anvendelse af ny varmevekslertype med flade aluminiumsroer og finner

    Energy Technology Data Exchange (ETDEWEB)

    Mulvad, R. (Aluventa A/S, Svendborg (Denmark)); Schneider, P. (Teknologisk Institut, Koele- og Varmepumpeteknik, AArhus (Denmark))

    2008-12-15

    This report describes the theoretical and practical work carried out to characterize and size air-cooled condensers and evaporators manufactured in MPE-tubes. Test heat exchangers were constructed for which capacity and pressure loss was measured. The measurements are compared with equations from the literature, and the most appropriate equations were selected. An analytical comparison of heat exchangers made with round tubes and fins of different types shows that by using heat exchangers with MPE-tubes and louvered fins lower air side pressure loss and higher performance can be achieved. Similarly, the refrigerant filling in MPE heat exchangers lower than in conventional heat exchangers with round tubes. This has great significance in the choice of heat exchangers because of the high price per kilo of HCF refrigerants. Correlations for heat transfer and pressure loss by condensation / evaporation and correlations for heat transfer and pressure drop were implemented in the calculation programs for design of condensers and evaporators. The calculation programs developed in the project are compared with a non-commercially available program designed for heat exchangers with MPE-tubes. The comparison shows good agreement. (ln)

  15. 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.

  16. Finite Element Analysis of the Polyethylene Pipe Heating during Welding with a Heating Plate

    Directory of Open Access Journals (Sweden)

    Adelin Tută

    2008-10-01

    Full Text Available In this paper we present the results of a study based on the finite element method applied to end-to-end polyethylene pipe welding. In the experiment we used the ANSYS 6.1 finite element program that succeeds to accurately capture many common physical phenomena.

  17. FEM-DBEM approach to analyse crack scenarios in a baffle cooling pipe undergoing heat flux from the plasma

    Directory of Open Access Journals (Sweden)

    R. Citarella

    2017-02-01

    Full Text Available Wendelstein 7-X is the world’s largest nuclear fusion experiment of stellarator type, in which a hydrogen plasma is confined by a magnet field generated with external superconducting coils, allowing the plasma to be heated up to the fusion temperature. The water-cooled Plasma Facing Components (PFC protect the Plasma Vessel (PV against radiative and convective heat from the plasma. After the assembly process of heat shields and baffles, several cracks were found in the braze and cooling pipes. Due to heat load cycles occurring during each Operational Phase (OP, thermal stresses are generated in the heat sinks, braze root and cooling pipes, capable to drive fatigue crack-growth and, possibly, a water leak through the pipe thickness. The aim of this study is to assess the most dangerous initial crack configurations in one of the most critical baffles by using numerical models based on a FEM-DBEM approach.

  18. Pulsating Heat pipe Only for Space (PHOS): results of the REXUS 18 sounding rocket campaign

    Science.gov (United States)

    Creatini, F.; Guidi, G. M.; Belfi, F.; Cicero, G.; Fioriti, D.; Di Prizio, D.; Piacquadio, S.; Becatti, G.; Orlandini, G.; Frigerio, A.; Fontanesi, S.; Nannipieri, P.; Rognini, M.; Morganti, N.; Filippeschi, S.; Di Marco, P.; Fanucci, L.; Baronti, F.; Mameli, M.; Manzoni, M.; Marengo, M.

    2015-11-01

    Two Closed Loop Pulsating Heat Pipes (CLPHPs) are tested on board REXUS 18 sounding rocket in order to obtain data over a relatively long microgravity period (approximately 90 s). The CLPHPs are partially filled with FC-72 and have, respectively, an inner tube diameter larger (3 mm) and slightly smaller (1.6 mm) than the critical diameter evaluated in static Earth gravity conditions. On ground, the small diameter CLPHP effectively works as a Pulsating Heat Pipe (PHP): the characteristic slug and plug flow pattern forms inside the tube and the heat exchange is triggered by thermally driven self-sustained oscillations of the working fluid. On the other hand, the large diameter CLPHP works as a two- phase thermosyphon in vertical position and doesn't work in horizontal position: in this particular condition, the working fluid stratifies within the device as the surface tension force is no longer able to balance buoyancy. Then, the idea to test the CLPHPs in reduced gravity conditions: as the gravity reduces the buoyancy forces becomes less intense and it is possible to recreate the typical PHP flow pattern also for larger inner tube diameters. This allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience low gravity conditions due to a failure in the yoyo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described.

  19. PHOS Experiment: Thermal Response of a Large Diameter Pulsating Heat Pipe on Board REXUS-18 Rocket

    Science.gov (United States)

    Creatini, F.; Guidi, G. M.; Belfi, F.; Cicero, G.; Fioriti, D.; Di Prizio, D.; Piacquadio, S.; Becatti, G.; Orlandini, G.; Frigerio, A.; Fontanesi, S.; Nannipieri, P.; Rognini, M.; Morganti, N.; Filippeschi, S.; Di Marco, P.; Fanucci, L.; Baronti, F.; Mameli, M.; Marengo, M.; Manzoni, M.

    2015-09-01

    In the present work, the results of two Closed Loop Pulsating Heat Pipes (CLPHPs) tested on board REXUS-1 8 sounding rocket in order to get experimental data over a relatively broad reduced gravity period (about 90 s) are thoroughly discussed. The CLPHPs are partially filled with refrigerant FC-72 and have, respectively, an inner tube diameter larger (3 .0 mm) and slightly smaller (1 .6 mm) than a critical diameter defined on Earth gravity conditions. On ground, the small diameter CLPHP works as a real Pulsating Heat Pipe (PHP): the typical capillary slug flow pattern forms inside the device and the heat exchange is triggered by self-sustained thermally driven oscillations of the working fluid. Conversely, the large diameter CLPHP behaves like a two-phase thermosyphon in vertical position while does not operate in horizontal position as the working fluid stratifies within the tube and surface tension is not able to balance buoyancy. Then, the idea to test the CLPHPs under reduced gravity conditions: as soon as gravity reduces, buoyancy becomes less intense and the typical capillary slug flow pattern can also forms within a tube with a larger diameter. Moreover, this allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience the expected reduced gravity conditions due to a failure of the yo-yo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described.

  20. A thermoelectric generator using loop heat pipe and design match for maximum-power generation

    KAUST Repository

    Huang, Bin-Juine

    2015-09-05

    The present study focuses on the thermoelectric generator (TEG) using loop heat pipe (LHP) and design match for maximum-power generation. The TEG uses loop heat pipe, a passive cooling device, to dissipate heat without consuming power and free of noise. The experiments for a TEG with 4W rated power show that the LHP performs very well with overall thermal resistance 0.35 K W-1, from the cold side of TEG module to the ambient. The LHP is able to dissipate heat up to 110W and is maintenance free. The TEG design match for maximum-power generation, called “near maximum-power point operation (nMPPO)”, is studied to eliminate the MPPT (maximum-power point tracking controller). nMPPO is simply a system design which properly matches the output voltage of TEG with the battery. It is experimentally shown that TEG using design match for maximum-power generation (nMPPO) performs better than TEG with MPPT.

  1. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

  2. Design and experimental investigation of a neon cryogenic loop heat pipe

    Science.gov (United States)

    He, Jiang; Guo, Yuandong; Zhang, Hongxing; Miao, Jianyin; Wang, Lu; Lin, Guiping

    2017-11-01

    Next generation space infrared sensor and detector have pressing requirement for cryogenic heat transport technology in the temperature range of 30-40 K. Cryogenic loop heat pipe (CLHP) has excellent thermal performance and particular characteristics such as high flexibility transport lines and no moving parts, thus it is regarded as an ideal thermal control solution. A neon CLHP referring to infrared point-to-point heat transfer element in future space application has been designed and experimented. And it could realize supercritical startup successfully. Experimental results show that the supercritical startup were realized successfully at cases of 1.5 W secondary evaporator power, but the startup was failed when 0.5 and 1 W heat load applied to secondary evaporator. The maximum heat transport capability of primary evaporator is between 4.5 and 5 W with proper auxiliary heat load. Before startup, even the heat sink temperature decreased to 35 K, the primary evaporator can still maintain at almost 290 K; and the primary evaporator temperature increased at once when the powers were cut off, which indicated the CLHP has a perfect function of thermal switch. The CLHP could adapt to sudden changes of the primary evaporator power, and reach a new steady-state quickly. Besides, some failure phenomena were observed during the test, which indicated that proper secondary evaporator power and heat sink temperature play important roles on the normal operation.

  3. Design and experimental investigation of a neon cryogenic loop heat pipe

    Science.gov (United States)

    He, Jiang; Guo, Yuandong; Zhang, Hongxing; Miao, Jianyin; Wang, Lu; Lin, Guiping

    2017-03-01

    Next generation space infrared sensor and detector have pressing requirement for cryogenic heat transport technology in the temperature range of 30-40 K. Cryogenic loop heat pipe (CLHP) has excellent thermal performance and particular characteristics such as high flexibility transport lines and no moving parts, thus it is regarded as an ideal thermal control solution. A neon CLHP referring to infrared point-to-point heat transfer element in future space application has been designed and experimented. And it could realize supercritical startup successfully. Experimental results show that the supercritical startup were realized successfully at cases of 1.5 W secondary evaporator power, but the startup was failed when 0.5 and 1 W heat load applied to secondary evaporator. The maximum heat transport capability of primary evaporator is between 4.5 and 5 W with proper auxiliary heat load. Before startup, even the heat sink temperature decreased to 35 K, the primary evaporator can still maintain at almost 290 K; and the primary evaporator temperature increased at once when the powers were cut off, which indicated the CLHP has a perfect function of thermal switch. The CLHP could adapt to sudden changes of the primary evaporator power, and reach a new steady-state quickly. Besides, some failure phenomena were observed during the test, which indicated that proper secondary evaporator power and heat sink temperature play important roles on the normal operation.

  4. Optimization of SiO2 nanoparticle mass concentration and heat input on a loop heat pipe

    Directory of Open Access Journals (Sweden)

    Prem Gunnasegaran

    2015-09-01

    Full Text Available This study presents the effect of nanoparticle mass concentration and heat input based on the total thermal resistance (Rth of loop heat pipe (LHP, employed for PC-CPU cooling. In this study, silica nanoparticles (SiO2 in water with particle mass concentration ranged from 0% (pure water to 3% is considered as the working fluid within the LHP. The experimental design and optimization is accomplished by the design of experimental tool, Response Surface Methodology (RSM. The results show that the nanoparticle mass concentration and the heat input have significant effect on the Rth of LHP. For a given heat input, the Rth is found to decrease with the increase of the nanoparticle mass concentration up to 0.5% and increased thereafter. It is also found that the Rth is decreased when the heat input is increased from 20 W to 60 W. The results are optimized with the objective of minimizing the Rth, using Design-Expert software, and the optimized nanoparticle mass concentration and heat input are 0.48% and 59.97 W, respectively, the minimum Rth being 2.66 (ºC/W. The existence of an optimum nanoparticle mass concentration and heat input are the predominant factors for the improvement in the thermal performance of nanofluid-charged LHP.

  5. Effect of Twisted-Tape Turbulators and Nanofluid on Heat Transfer in a Double Pipe Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Heydar Maddah

    2014-01-01

    Full Text Available Heat transfer and overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and titanium dioxide nanofluid were studied experimentally. The inner and outer diameters of the inner tube were 8 and 16 mm, respectively, and cold and hot water were used as working fluids in shell side and tube side. The twisted tapes were made from aluminum sheet with tape thickness (d of 1 mm, width (W of 5 mm, and length of 120 cm. Titanium dioxide nanoparticles with a diameter of 30 nm and a volume concentration of 0.01% (v/v were prepared. The effects of temperature, mass flow rate, and concentration of nanoparticles on the overall heat transfer coefficient, heat transfer changes in the turbulent flow regime Re≥2300, and counter current flow were investigated. When using twisted tape and nanofluid, heat transfer coefficient was about 10 to 25 percent higher than when they were not used. It was also observed that the heat transfer coefficient increases with operating temperature and mass flow rate. The experimental results also showed that 0.01% TiO2/water nanofluid with twisted tape has slightly higher friction factor and pressure drop when compared to 0.01% TiO2/water nanofluid without twisted tape. The empirical correlations proposed for friction factor are in good agreement with the experimental data.

  6. High energy pipe line break postulations and their mitigation - examples for VVER nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Zdarek, J.; Pecinka, L.; Kadecka, P.; Dotrel, J. [Nuclear Res. Inst., Rez (Czech Republic)

    1998-11-01

    The concept and the proposals for the protection and reinforcement of equipment against the effects of postulated rupture of the high-energy piping, in VVER Plant, are presented. The most recent version of the US NRC Guidelines has been used. The development of the legislation, the basic approach and selection of criteria for the assessment of the rupture of high energy piping, provide the basis for the application of the separation concept in the overall safety philosophy. (orig.)

  7. Numerical analysis of heat transfer in unsteady nanofluids in a small pipe with pulse pressure

    Science.gov (United States)

    Park, Cheol; Yu, KiTae; Song, HeeGeun; Kim, Sedong; Jeong, Hyomin

    2017-08-01

    In the present paper, developing turbulence forced convection flows were numerically investigated by using water-Al2O3 nano-fluid through a circular compact pipe which has 4.5mm diameter. Each model has a steady state and uniform heat flux(UHF) at the wall. The whole numerical experiments were processed under the RPM 100 to 500 and the nano-fluid models were made by the Alumina volume fraction. A single-phase fluid models were defined through nano-fluid physical and thermal properties calculations, Two-phase models(mixture granular model) were processed in 100nm diameter. The results show that comparison of nusselt number and heat transfer rate are improved as the Al2O3 volume fraction increased. All of the numerical flow simulations are processed by the FLUENT. The results show an increase from volume fraction concentration and an increase in heat transfer coefficient with increasing RPM.

  8. MATHEMATICAL MODELING OF HEAT EXCHANGE IN DIRECT FLAT CHANNELS AND DIRECT ROUND PIPES WITH ROUGH WALLS UNDER THE SYMMETRIC HEAT SUPPLY

    Directory of Open Access Journals (Sweden)

    I E. Lobanov

    2017-01-01

    Full Text Available Objectives. The aim of present work was to carry out mathematical modelling of heat transfer with symmetrical heating in flat channels and round pipes with rough walls.Methods. The calculation was carried out using the L'Hôpital-Bernoulli's method. The solution of the problem of intensified heat transfer in a round tube with rough walls was obtained using the Lyon's integral.Results. Different from existing theories, a methodology of theoretical computational heat transfer determination for flat rough channels and round pipes with rough walls is developed on the basis of the principle of full viscosity superposition in a turbulent boundary layer. The analysis of the calculated heat transfer and hydroresistivity values for flat rough channels and round rough pipes shows that the increase in heat transfer is always less than the corresponding increase in hydraulic resistance, which is a disadvantage as compared to channels with turbulators, with all else being equal. The results of calculating the heat transfer for channels with rough walls in an extended range of determinant parameters, which differ significantly from the corresponding data for the channels with turbulators, determine the level of heat exchange intensification.Conclusion. An increase in the calculated values of the relative average heat transfer Nu/NuGL for flat rough channels and rough pipes with very high values of the relative roughness is significantly contributed by both an increase in the relative roughness height and an increase in the Reynolds number Re. In comparison with empirical dependencies, the main advantage of solutions for averaged heat transfer in rough flat channels and round pipes under symmetrical thermal load obtained according to the developed theory is that they allow the calculation of heat exchange in rough pipes to be made in the case of large and very large relative heights of roughness protrusions, including large Reynolds numbers, typical for pipes

  9. Compound heat transfer enhancement for shell side of double-pipe heat exchanger by helical fins and vortex generators

    Science.gov (United States)

    Zhang, Li; Guo, Hongmei; Wu, Jianhua; Du, Wenjuan

    2012-07-01

    To improve heat transfer performance of shell side of double-pipe heat exchanger with helical fins on its inner tube, some vortex generators (VGs) were installed along the centerline of the helical channel. Heat transfer performance and pressure drop characteristic of the enhanced heat exchangers were investigated using air as the working fluid and steam as the heating medium. The helical fins were in the annulus and span its full width at different helical pitch. Wing-type VGs (delta or rectangular wing) and winglet-type VGs (delta or rectangular winglet pair) were used to combine with helical fins. The friction factor and Nusselt number can be well correlated by power-law correlations in the Reynolds number range studied. In order to evaluate the thermal performance of the shell side enhanced over the shell side without enhancement, comparisons were made under three constraints: (1) identical mass flow rate, IMF; (2) identical pressure drop, IPD and (3) identical pumping power, IPP. The results show the shell side enhanced by the compound heat transfer enhancement has better performance than the shell side only enhanced by helical fins at shorter helical pitch under the three constraints.

  10. Experimental analysis of thermal performance according to heat pipe working fluids for evacuated tube solar collector

    Science.gov (United States)

    Joo, Hong-Jin; Kwak, Hee-Youl

    2017-11-01

    The purpose of this study was to experimentally investigate the thermal performance and operating characteristics of various heat pipe working fluids in evacuated tube solar collectors. Heat pipe efficiency was evaluated by calculating the solar collector efficiency value when using four types of working fluids: water, ethanol, flutec-pp9 and methyl acetate under the same operating conditions on an indoor experiment apparatus. The experimental conditions were as follows: The inclination angle of the evacuated tube solar collectors were 20°, 40° and 60° from the normal basis. The mass flow rate into the manifold of the evacuated tubular solar collector was 0.3 kg/min. The heat flux on the collector surface was 870 W/m2. The results showed that, at an angle of incidence of 40°, the values of {F}R ( {τ α } ) and {F}R {U}L with methyl acetate as the working fluid were 0.6572 and -2.0086, respectively, with water they were 0.6636 and -1.8457, respectively, ethanol they were 0.6147 and -0.6353, respectively, and with flutec-pp9 they were 0.525, and -3.2313, respectively.

  11. Multiple-effect diffusion solar still coupled with a vacuum-tube collector and heat pipe

    KAUST Repository

    Chong, Tze-Ling

    2014-08-01

    The present study develops a multiple-effect diffusion solar still (MEDS) with a bended-plate design in multiple-effect diffusion unit (MDU) to solve the peel-off problem of wick material. The MDU is coupled with a vacuum-tube solar collector to produce a high temperature gradient for high productivity. A heat pipe is used to transfer the solar heat to the MDU. A prototype MEDS-1L was built and tested outdoors. Four performance indexes are proposed for the performance evaluation of MEDS, including daily pure water production per unit area of glass cover, solar absorber, and evaporating surface (Mcov, Msol, Mevp, respectively), and solar distillation efficiency Rcov. The outdoor test results of MEDS-1L show that the solar collector supply temperature Th reaches 100°C at solar radiation 800Wm-2. The highest Mcov is 23.9kgm-2d-1 which is about 29% higher than the basin-type MEDS [11]. The highest value is 25.9kgm-2d-1 for Msol and 2.79kgm-2d-1 for Mevp. The measured Rcov is 1.5-2.44, higher than the basin-type MEDS (1.45-1.88). The Mcov, Msol, Mevp and Rcov of MEDS-1L are all higher than the theoretical calculation of a MEDS with a flat-plate solar collector coupled with a heat pipe (MEDS-FHP) [17].© 2014 Elsevier B.V.

  12. Thermal Vacuum/Balance Test Results of Swift BAT with Loop Heat Pipe Thermal System

    Science.gov (United States)

    Choi, Michael K.

    2004-01-01

    The Swift Burst Alert Telescope (BAT) Detector Array is thermally well coupled to eight constant conductance heat pipes (CCHPs) embedded in the Detector Array Plate PAP), and two loop heat pipes (LHPs) transport heat from the CCHPs to a radiator. The CCHPs have ammonia as the working fluid and the LHPs have propylene as the working fluid. Precision heater controllers, which have adjustable set points in flight, are used to control the LHP compensation chamber and Detector Array xA1 ASIC temperatures. The radiator has AZ-Tek's AZW-LA-II low solar absorptance white paint as the thermal coating, and is located on the anti-sun side of the spacecraft. A thermal balance (T/B) test on the BAT was successfully completed. It validated that the thermal design satisfies the temperature requirements of the BAT in the flight thermal environments. Instrument level and observatory level thermal vacuum (TN) cycling tests of the BAT Detector Array by using the LHP thermal system were successfully completed. This paper presents the results of the T/B test and T N cycling tests.

  13. Generation of cross section data of heat pipe working fluids for compact nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Slewinski, Anderson; Ribeiro, Guilherme B. [Instituto Tecnológico de Aeronáutica (ITA), São José dos Campos, SP (Brazil); Caldeira, Alexandre D., E-mail: anderson_sle@live.com, E-mail: alexdc@ieav.cta.br, E-mail: gbribeiro@ieav.cta.br [Instituto de Estudos Avançados (IEAv), São José dos Campos, SP (Brazil). Divisão de Energia Nuclear

    2017-07-01

    For compact nuclear power plants, such as the nuclear space propulsion proposed by the TERRA project, aspects like mass, size and efficiency are essential drivers that must be managed during the project development. Moreover, for high temperature reactors, the use of liquid metal heat pipes as the heat removal mechanism provides some important advantages as simplicity and reliability. Considering these aforementioned aspects, this paper aims the development of the procedure necessary to calculate the microscopic absorption cross section data of several liquid metal to be used as working fluids with heat pipes; which will be later compared with the given data from JEF Report ⧣14. The information necessary to calculate the cross section data will be obtained from the latest ENDF library version. The NJOY system will be employed with the following modules: RECONR, BROADR, UNRESR and GROUPR, using the same specifications used to calculate the cross section data encountered in the JEF Report ⧣14. This methodology allows a comparison with published values, verifying the procedure developed to calculate the microscopic absorption cross section for selected isotopes using the TERRA reactor spectrum. Liquid metals isotopes of Sodium (Na), Lithium (Li), Thallium (TI) and Mercury (Hg) are part of this study. (author)

  14. Profitability of heating entrepreneurship from the viewpoint of heating energy buyer, heating energy seller and energy wood seller

    Energy Technology Data Exchange (ETDEWEB)

    Sauvula-Seppaelae, T.; Ulander, E. (Seinaejoki Univ. of Applied Sciences, Ahtari (Finland), School of Agriculture and Forestry), e-mail: tiina.sauvula-seppala@seamk.fi, e-mail: essi.ulander@seamk.fi

    2010-07-01

    The focus of this research was to study the profitability of heating entrepreneurships from the viewpoint of heating energy buyer, seller as well as energy wood seller. The average costs of heat production were Eur 44,8 / MWh and incomes Eur 43,4 /MWh. Energy wood purchase, comminution and long distance transportation formed slightly over a half of the heat production costs. Average net income in the group of the largest heating plants (>1000 kW) was Eur 29000 per year and in the group of the smallest (<200 kW) average net income was slightly over Eur 4000 per year. The net income from selling heat represents only a part of the income a heating entrepreneur receives from heat production. Other, significant parts are formed by income from selling energy wood to the plant as well as compensation for supervision and maintenance of the plant. The average net income of a forest owner from selling energy wood to heating entrepreneurs was Eur 18 / m3. Without state subsidies the net income would have been Eur 4 / m3. The price of the heating energy sold by heating entrepreneurs was very competitive. In 2006 it was Eur 30 / MWh cheaper than oil heat, Eur 34 / MWh cheaper than electric heat and Eur 3 / MWh cheaper than district heating. (orig.)

  15. Low-gravity experiments of lightweight flexible heat pipe panels with self-rewetting fluids.

    Science.gov (United States)

    Tanaka, Kotaro; Abe, Yoshiyuki; Nakagawa, Masayuki; Piccolo, Chiara; Savino, Raffaele

    2009-04-01

    Fluids with a unique surface tension behavior, the so-called "self-rewetting fluids," are considered to be promising working fluids not only in reduced-gravity environments but also in terrestrial applications. Ultralightweight polyimide-based wickless heat pipe panels with flexible, inflatable, and deployable functions were fabricated using self-rewetting fluids. Fundamental operation tests of these panels were conducted under conditions of reduced gravity during parabolic flight. We obtained promising experimental results on the thermal performance of the panels in reduced gravity, although the experimental conditions were not entirely satisfactory.

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

    Data.gov (United States)

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

  17. Heating of Microchannel Plates Detector Positioned Inside the LHC Beam Pipe by the Electromagnetic Fields of Relativistic Beams

    CERN Document Server

    Dubenskiy, V P; CERN. Geneva; Tsimbal, F A

    1995-01-01

    Here we present the results of our estimates of upper limits for heating induced by the relativistic beams of charged particles at the future LHC in the MCP detector placed inside the beam pipe. The energy losses are small for the uppermost intensities of the beams to be expected: less than 0.0033 Wt for the conductive cromium MCP cladding and not greater than 0.02 Wt for the dialectric MCP body (for the whole MCP disk of 100 sq.cm area). The special measurements of the dispersion law e(w) of the MCP dialectric material have been performed in order to get the reference data to the analytical calculations. The approaches outlined here could be applied to any detector positioned in the vicinity of the beams. The possible problems of the beam induced electrical signal in the detector circuits are touched also.

  18. Study of the technology of heat pipe on prevention wildfire of coal gangue hill

    Science.gov (United States)

    Deng, Jun; Li, Bei; Ding, Ximei; Ma, Li

    2017-04-01

    Self-ignitable coal gangue hill (CGH) is one kind of special combustion system, which has the characteristics of low self-ignite point, large heat storage, and easy reignition. The currently industrial fire extinguishing methods, such as inhibiting tendency of coal self-ignition, loessial overburden, and cement grouting, had unsatisfied effects for dispersing the heat out in time. Correspondingly, the CGH will lead reignition more frequently with the passage of time. The high underground temperature of CGH threatens the process of ecological and vegetation construction. Therefore, the elimination of high temperature is a vital issue to be solved urgently for habitat restoration. To achieve the ultimately ecological management goal of self-ignitable CGH - extinguishing the fire completely and never reignited, it is crucial to break the heat accumulation. Heat-pipe (HP) has a character of high efficient heat transfer capacity for eliminating the continuously high temperature in CGH. An experimental system was designed to test the heat transfer performance of HP for preventing and extinguishing the spontaneous combustion of coal gangue. Based on the heat transfer theory, the resistance network of the coal-HP heat removal system was analyzed for studying the cooling effect of HP. The experimental results show that the HP can accelerate the heat release in coal gangue pile. The coal temperature could be controlled at 59.6 ˚ C with HP in 7 h and the highest cooling value is 39.4 % with HP in 150 h, which can effectively cool the temperatures of high temperature zones. As a powerful heat transfer components, as soon as HPs were inserted into the CGH with a reasonable distance, it can completely play a vital role in inhibiting the coal self-ignition process.

  19. Heat transfer of a non-Newtonian fluid (Carbopol aqueous solution) in transitional pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Peixinho, J.; Desaubry, C.; Lebouche, M. [LEMTA - Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 2 Avenue de la foret de Haye, BP 160, 54 504 Vandoeuvre-les-Nancy (France)

    2008-01-15

    An experimental study of the forced convection heat transfer for non-Newtonian fluid flow in a pipe is presented. We focus particularly on the transitional regime. A wall boundary heating condition of heat flux is imposed. The non-Newtonian fluid used is Carbopol (polyacrylic acid) aqueous solutions. Detailed rheology as well as the variation of the rheological parameters with temperature are reported. Newtonian and shear thinning fluids are also tested for comparative purposes. The characterization of the flow and the thermal convection is made via the pressure drop and the wall temperature measurements over a range of Reynolds number from laminar to turbulent regime. Our measurements show that the non-Newtonian character stabilizes the flow, i.e., the critical Reynolds number to transitional flow increases with shear thinning and yield stress. The heat transfer coefficients are given and compared with heat transfer laws for different regime flows. Details when the heat transfer coefficient loses rapidly its local dependence on the Reynolds number are analyzed. (author)

  20. Experimental investigation on the thermal performance of a closed oscillating heat pipe in thermal management

    Science.gov (United States)

    Rao, Zhonghao; Wang, Qingchao; Zhao, Jiateng; Huang, Congliang

    2017-10-01

    To investigate the thermal performance of the closed oscillating heat pipe (OHP) as a passive heat transfer device in thermal management system, the gravitation force, surface tension, cooling section position and inclination angle were discussed with applied heating power ranging from 5 to 65 W. The deionized water was chosen as the working fluid and liquid-filling ratio was 50 ± 5%. The operation of the OHP mainly depends on the phase change of the working fluid. The working fluid within the OHP was constantly evaporated and cooled. The results show that the movement of the working fluid was similar to the forced damped mechanical vibration, it has to overcome the capillary resistance force and the stable oscillation should be that the OHP could successful startup. The oscillation frequency slowed and oscillation amplitude decreased when the inclination angle of the OHP increased. However, the thermal resistance increased. With the increment of the heating power, the average temperature of the evaporation and condensation section would be close. If the heating power was further increased, dry-out phenomenon within the OHP would appeared. With the decrement of the L, the start-up heating power also decreased and stable oscillation would be formed.

  1. Solar Energy for Space Heating & Hot Water.

    Science.gov (United States)

    Energy Research and Development Administration, Washington, DC. Div. of Solar Energy.

    This pamphlet reviews the direct transfer of solar energy into heat, particularly for the purpose of providing space and hot water heating needs. Owners of buildings and homes are provided with a basic understanding of solar heating and hot water systems: what they are, how they perform, the energy savings possible, and the cost factors involved.…

  2. ENERGY STAR Certified Geothermal Heat Pumps

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Geothermal Heat Pumps that are effective as of January 1, 2012. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=geo_heat.pr_crit_geo_heat_pumps

  3. Hot Topics! Heat Pumps and Geothermal Energy

    Science.gov (United States)

    Roman, Harry T.

    2009-01-01

    The recent rapid rises in the cost of energy has significantly increased interest in alternative energy sources. The author discusses the underlying principles of heat pumps and geothermal energy. Related activities for technology education students are included.

  4. CFD Analysis of nanofluid forced convection heat transport in laminar flow through a compact pipe

    Science.gov (United States)

    Yu, Kitae; Park, Cheol; Kim, Sedon; Song, Heegun; Jeong, Hyomin

    2017-08-01

    In the present paper, developing laminar forced convection flows were numerically investigated by using water-Al2O3 nano-fluid through a circular compact pipe which has 4.5mm diameter. Each model has a steady state and uniform heat flux (UHF) at the wall. The whole numerical experiments were processed under the Re = 1050 and the nano-fluid models were made by the Alumina volume fraction. A single-phase fluid models were defined through nano-fluid physical and thermal properties calculations, Two-phase model(mixture granular model) were processed in 100nm diameter. The results show that Nusselt number and heat transfer rate are improved as the Al2O3 volume fraction increased. All of the numerical flow simulations are processed by the FLUENT. The results show the increment of thermal transfer from the volume fraction concentration.

  5. Analytical model of heat transfer in porous insulation around cold pipes

    DEFF Research Database (Denmark)

    Guldbrandsen, Tom; Karlsson, Per W.; Korsgaard, Vagn

    2011-01-01

    A thermal insulation system is analysed that consists of a cold tube insulated with a porous material faced with a vapour retarding foil.Water vapour will diffuse through the vapour retarding foil and condense on the cold tube. To avoid build-up of water in the insulation a hydrophilic wicking...... cloth is wrapped around the cold tube and extended through a slit in the tubular insulation and a slot in the facing to the ambient so that condensed water can evaporate into the air. Some of the moisture in that part of the wicking cloth situated in the slit in the tubular insulation will diffuse...... backwards to the cold pipe and contribute to the heat uptake of the cold tube. This part is calculated for the stationary case and compared with the sensible heat transfer through the tubular shaped insulation material, using measured dry λ values and measured fictitious moist λ values....

  6. Nonlinear analysis of chaotic flow in a 3D closed-loop pulsating heat pipe

    CERN Document Server

    Pouryoussefi, S M

    2016-01-01

    Numerical simulation has been conducted for the chaotic flow in a 3D closed-loop pulsating heat pipe (PHP). Heat flux and constant temperature boundary conditions were applied for evaporator and condenser sections, respectively. Water and ethanol were used as working fluids. Volume of Fluid (VOF) method has been employed for two-phase flow simulation. Spectral analysis of temperature time series was carried out using Power Spectrum Density (PSD) method. Existence of dominant peak in PSD diagram indicated periodic or quasi-periodic behavior in temperature oscillations at particular frequencies. Correlation dimension values for ethanol as working fluid was found to be higher than that for water under the same operating conditions. Similar range of Lyapunov exponent values for the PHP with water and ethanol as working fluids indicated strong dependency of Lyapunov exponent to the structure and dimensions of the PHP. An O-ring structure pattern was obtained for reconstructed 3D attractor at periodic or quasi-peri...

  7. Evacuated tubular collector utilizing a heat pipe. Progress report, May 1 1975--August 31, 1975

    Energy Technology Data Exchange (ETDEWEB)

    Ortabasi, U.; Fehlner, F.P.

    1975-01-01

    Research and development activities performed by the Corning Glass Works solar group during the period from May 1, 1975 to August 31, 1975 are reported. The analytical studies encompassed optical modeling of a modified cusp reflector, fresnel losses from tubular enclosures as a function of orientation, preliminary work on a digital Monte-Carlo Ray Tracing Computer Code and the determination of U/sub L/ losses as a function of vacuum level and temperature of the absorber. Compatible enclosure materials, wicks and working fluids were selected to assemble heat pipes for use as solar collector absorbers. Cusp reflectors with good accuracy were fabricated from various commercial bright aluminum sheet and their optical properties determined. Evacuation techniques were developed and special bake-out procedures were worked out to assemble the evacuated tubular collectors. The work on selective coatings narrowed down the field of potential absorber films to ''black chrome'' which has good stability in vacuum and the necessary ..cap alpha../epsilon value. Six different heat pipes and one flow-through absorber were fabricated and were partially characterized for thermal performance. Indoor and outdoor test facilities were completed and calibrated within proposed NBS standards. They are now available for parametric as well as true-life experiments with solar radiation.

  8. Comparison of Two Potassium-Filled Gas-Controlled Heat Pipes

    Science.gov (United States)

    Bertiglia, F.; Iacomini, L.; Moro, F.; Merlone, A.

    2015-12-01

    Calibration by comparison of platinum resistance thermometers and thermocouples requires transfer media capable of providing very good short-term temperature uniformity and temperature stability over a wide temperature range. This paper describes and compares the performance of two potassium-filled gas-controlled heat pipes (GCHP) for operation over the range from 420° C to 900° C. One of the heat pipes has been in operation for more than 10 years having been operated at temperature for thousands of hours, while the other was commissioned in 2010 following recently developed improvements to both the design, assembly, and filling processes. It was found that the two devices, despite differences in age, structure, number of wells, and filling processes, realized the same temperatures within the measurement uncertainty. The results show that the potassium-filled GCHP provides a durable and high-quality transfer medium for performing thermometer calibrations with very low uncertainties, over the difficult high-temperature range from 420° C to 900° C.

  9. A hybrid surface modification method on copper wire braids for enhancing thermal performance of ultra-thin heat pipes

    Science.gov (United States)

    Sheng, W. K.; Lin, H. T.; Wu, C. H.; Kuo, L. S.; Chen, P. H.

    2017-02-01

    Copper is the most widely used material in heat pipe manufacturing. Since the capability of wick structures inside a heat pipe will dominate its thermal performance, in this study, we introduce a hybrid surface modification method on the copper wire braids being inserted as wick structure into an ultra-thin heat pipe. The hybrid method is the combination of a chemical-oxidation-based method and a sol-gel method with nanoparticles being dip-coated onto the braid. The experimental data show that braids under hybrid treatment perform higher water rising speed than the oxidized braids while owning higher water net weight than those braids being only dip-coated with nanoparticle.

  10. Visualization of the freeze/thaw characteristics of a copper/water heat pipe - Effects of non-condensible gas

    Science.gov (United States)

    Ochterbeck, J. M.; Peterson, G. P.

    1991-01-01

    The freeze/thaw characteristics of a copper/water heat pipe of rectangular cross section were investigated experimentally to determine the effect of variations in the amount of non-condensible gases (NCG) present. The transient internal temperature profiles in both the liquid and vapor channels are presented along with contours of the frozen fluid configuration obtained through visual observation. Several interesting phenomena were observed including total blockage of the vapor channel by a solid plug, evaporator dryout during restart, and freezing blowby. In addition, the restart characteristics are shown to be strongly dependent upon the shutdown procedure used prior to freezing, indicating that accurate prediction of the startup or restart characteristics requires a complete thermal history. Finally, the experimental results indicate that the freeze/thaw characteristics of room temperature heat pipes may be significantly different from those occurring in higher temperature, liquid metal heat pipes due to differences in the vapor pressures in the frozen condition.

  11. The influence of longitudinal vibrations on the heat transfer performance of inclined heat pipes

    National Research Council Canada - National Science Library

    Chen, Rong-Horng; Kuo, LW; Lai, Chi-Ming

    2015-01-01

    This study focused on investigating the influence of longitudinal vibrations, the condensation section temperature, and the inclination angles on the heat transfer performance of grooved cylindrical...

  12. Gravity Effects on the Performance of a Flat Loop Heat Pipe

    Science.gov (United States)

    Mo, Dong-Chuan; Ding, Nan; Lu, Shu-Shen

    2009-08-01

    A loop heat pipe with flat evaporator (FLHP) is manufactured from copper, and filled with ultrapure water as the working fluid. The heat transfer characteristics have been studied experimentally. The gravity impacts the heat transfer characteristics of the FLHP in different orientations. Operation of the FLHP at orientations against the gravity which is the evaporator above the condenser leads to the higher temperature of the evaporator and the lower loop heat tranfer performance. At horizontal orientation with the evaporator above the compensation chamber (CC), the working fluid is difficult to reach the wick and has the highest temperature. With the increasing of the heat load upto more than 300 W, the loop thermal resistance decreases and approaches a minimum value of about 0.2 K/W at the vertical orientation helped by gravity. Experimental results show that the start-up with low power needs a temperature overshoot. Oscillations with high frequency (with periods on the order of seconds to minutes) and high amplitude (with temperature changes on the order of tens degree Kelvin) are observed. A model is developed, which shows the working fluid distributing in the evaporator wick may result such oscillations. In most cases, the highest amplitude in the loop is observed in the liquid line near CC, and the lowest amplitude is in the CC.

  13. Startup of a frozen heat pipe in one-g and micro-g environments - A proposed shuttle flight experiment

    Science.gov (United States)

    Ochterbeck, J. M.; Peterson, G. P.

    1991-01-01

    An attempt is made to determine how a heat pipe freezes under various low load and/or no load conditions in both one-g and micro-g environments. Also of interest are the mechanisms that can be used to restart the heat pipe after freezing has occurred. Particular attention is given to step function power reductions and the resulting distribution of the working fluid after freezing has occurred and the effect of noncondensible gases on the frozen configuration and the restart characteristics.

  14. Effect of interfacial phenomena on evaporative heat transfer in micro heat pipes; Influence des phenomenes interfaciaux sur les transferts de chaleur par evaporation dans les microcaloducs

    Energy Technology Data Exchange (ETDEWEB)

    Sartre, V.; Chaker Zaghdoudi, M.; Lallemand, M. [Institut National des Sciences Appliquees (INSA), Centre Thermique de Lyon, UPRESA CNRS 5008, 69 - Villeurbanne (France)

    2000-04-01

    A three-dimensional steady-state model for predicting heat transfer in a micro pipe array is presented. Three coupled models, solving the micro region equations, the-dimensional wall heat conduction problem and the longitudinal capillarity two-phase flow have been developed. The results, presented for an aluminium/ammonia triangular micro heat pipe array, show that the major part of the total heat input in the evaporator section goes through the micro-region. In addition, both the apparent contact angle and the heat transfer are in the micro-region increase with an increasing wall superheat. It is also shown that the inner wall heat flux and temperatures as well as the contact angle decrease all along the evaporator section. (authors)

  15. Reduction of heat losses on the skid pipe system of a pusher type furnace; Verringerung der Waermeverluste am Tragrohrsystem eines Stossofens

    Energy Technology Data Exchange (ETDEWEB)

    Hoffelner, Mario; Winter, Franz [voestalpine Grobblech GmbH, Linz (Austria); Springer, Michael; Huegel, Frank [FBB Engineering GmbH, Moenchengladbach (Germany); Buhr, Andreas [Almatis GmbH, Frankfurt (Germany); Kockegey-Lorenz, Rainer [Almatis GmbH, Ludwigshafen (Germany)

    2013-06-15

    This paper discusses how energy consumption and energy loss can be reduced in reheating furnaces of hot rolling mills by new lightweight refractory materials and a new modular lining concept for the skid pipe insulation using pre-fabricated shells. The target is to optimise the hot rolling process from an energy point of view, and to reduce the operational cost of the furnaces. The new lightweight pre-fabricated shells based on the microporous castable and a thermotechnical optimised sandwich design can significantly reduce the heat losses compared to dense castable. Industrial application of the new system in a 110 t/h pusher type furnace at voestalpine Grobblech GmbH in Linz, Austria, resulted in reduction of heat loss about 30 %. The annualised energy saving gives a cost reduction of more than Euro 200,000 a year. Costs for the complete new lining about Euro 170,000 result in a payback period of less than one year. (orig.)

  16. Silicon Carbide (SiC) Device and Module Reliability, Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field

    Science.gov (United States)

    2016-05-01

    magnitude and direction, which are generated from a transitory and spatial acceleration vector field and their impact on the dynamical performance of two...Heat Input to an Acceleration Field Kirk L. Yerkes (AFRL/RQQI) and James D. Scofield (AFRL/RQQE) Flight Systems Integration Branch (AFRL/RQQI...CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field 5a

  17. Testing of a Neon Loop Heat Pipe for Large Area Cryocooling

    Science.gov (United States)

    Ku, Jentung; Robinson, Franklin Lee

    2014-01-01

    Cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks is required for future NASA missions. A cryogenic loop heat pipe (CLHP) can provide a closed-loop cooling system for this purpose and has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A neon CLHP was tested extensively in a thermal vacuum chamber using a cryopump as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components. Tests conducted included loop cool-down from the ambient temperature, startup, power cycle, heat removal capability, loop capillary limit and recovery from a dry-out, low power operation, and long duration steady state operation. The neon CLHP demonstrated robust operation. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by applying power to both the pump and evaporator without any pre-conditioning. It could adapt to changes in the pump power andor evaporator power, and reach a new steady state very quickly. The evaporator could remove heat loads between 0.25W and 4W. When the pump capillary limit was exceeded, the loop could resume its normal function by reducing the pump power. Steady state operations were demonstrated for up to 6 hours. The ability of the neon loop to cool large areas was therefore successfully verified.

  18. Thermal performance comparison of oscillating heat pipes with and without helical micro-grooves

    Science.gov (United States)

    Qu, Jian; Li, Xiaojun; Xu, Qian; Wang, Qian

    2017-06-01

    This paper presents an experimental investigation to compare the thermal performance of three closed loop oscillating heat pipes (OHPs) with and without internal helical microgrooves at vertical and horizontal orientations. All of these OHPs were made from copper tubes and have three turns with lengths of 70, 230 and 110 mm at the evaporator, adiabatic and condenser sections, respectively. Deionized water was used as the working fluid at a volumetric filling ratio of 50%. The internal diameters (IDs) of two smooth-tube OHPs are 4.0 and 4.8 mm, respectively, and the internal diameter of micro-grooved OHP without groove structures is about 4.5 mm. Experimental results demonstrated that the addition of groove structures make the OHP remarkably outperform smooth-tube OHPs in both effective thermal conductivity and thermal resistance. The thermal resistance of vertically-oriented micro-grooved OHP could be lowered to 0.057 °C/W associated with an effective thermal conductivity of 6.1 × 104 W/ (m·K) at the input heat flux of 3.8 × 104 W/m2. Compared to smooth-tube OHPs, preliminary mechanism analysis reveals that local heat transfer coefficients both at the heating and cooling sections of micro-grooved OHP could be significantly improved. Moreover, enhanced liquid backflow to the evaporator due to microgroove-induced capillarity is also responsible for the OHP performance enhancement.

  19. Boundary element method applied to a gas-fired pin-fin-enhanced heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Andraka, C.E.; Knorovsky, G.A.; Drewien, C.A.

    1998-02-01

    The thermal conduction of a portion of an enhanced surface heat exchanger for a gas fired heat pipe solar receiver was modeled using the boundary element and finite element methods (BEM and FEM) to determine the effect of weld fillet size on performance of a stud welded pin fin. A process that could be utilized by others for designing the surface mesh on an object of interest, performing a conversion from the mesh into the input format utilized by the BEM code, obtaining output on the surface of the object, and displaying visual results was developed. It was determined that the weld fillet on the pin fin significantly enhanced the heat performance, improving the operating margin of the heat exchanger. The performance of the BEM program on the pin fin was measured (as computational time) and used as a performance comparison with the FEM model. Given similar surface element densities, the BEM method took longer to get a solution than the FEM method. The FEM method creates a sparse matrix that scales in storage and computation as the number of nodes (N), whereas the BEM method scales as N{sup 2} in storage and N{sup 3} in computation.

  20. Thermal performance comparison of oscillating heat pipes with and without helical micro-grooves

    Science.gov (United States)

    Qu, Jian; Li, Xiaojun; Xu, Qian; Wang, Qian

    2017-11-01

    This paper presents an experimental investigation to compare the thermal performance of three closed loop oscillating heat pipes (OHPs) with and without internal helical microgrooves at vertical and horizontal orientations. All of these OHPs were made from copper tubes and have three turns with lengths of 70, 230 and 110 mm at the evaporator, adiabatic and condenser sections, respectively. Deionized water was used as the working fluid at a volumetric filling ratio of 50%. The internal diameters (IDs) of two smooth-tube OHPs are 4.0 and 4.8 mm, respectively, and the internal diameter of micro-grooved OHP without groove structures is about 4.5 mm. Experimental results demonstrated that the addition of groove structures make the OHP remarkably outperform smooth-tube OHPs in both effective thermal conductivity and thermal resistance. The thermal resistance of vertically-oriented micro-grooved OHP could be lowered to 0.057 °C/W associated with an effective thermal conductivity of 6.1 × 104 W/ (m·K) at the input heat flux of 3.8 × 104 W/m2. Compared to smooth-tube OHPs, preliminary mechanism analysis reveals that local heat transfer coefficients both at the heating and cooling sections of micro-grooved OHP could be significantly improved. Moreover, enhanced liquid backflow to the evaporator due to microgroove-induced capillarity is also responsible for the OHP performance enhancement.

  1. Experimental investigation on heat pipe cooling for Hybrid Electric Vehicle and Electric Vehicle lithium-ion battery

    Science.gov (United States)

    Tran, Thanh-Ha; Harmand, Souad; Sahut, Bernard

    2014-11-01

    In this work, we explored the use of heat pipe as cooling device for a specific HEV lithium-ion battery module. The evaporator blocks of heat pipe modules were fixed to a copper plate which played the role of the battery cooling wall. A flat heater was glued to the other surface of the copper plate and reproduced heat generated by the battery. The temperature at the cooper plate/heater interface corresponds to that of the battery module wall. An AMESim model of the battery was developed to estimate the cells' temperature within the battery. In inclined positions, a very slender evolution of the cooper plate/heater interface temperature was noticed, which means heat pipe works efficiently under different grade road conditions. Even though natural convection and chimney effect are not enough, coupling heat pipes with a confined ventilation structure is an efficient way to keep cells' temperature within its optimal range with an even temperature distribution. Furthermore, only low rate ventilation is necessary, which helps avoid parasitic power consumption and noise level in the vehicle.

  2. Detailed study of grooved heat pipes for a system functioning study; Etude fine des caloducs rainures en vue d`une etude systeme

    Energy Technology Data Exchange (ETDEWEB)

    Alexandre, A. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)

    1996-12-31

    The functioning of a heat pipe is complex. In this paper, a methodology for a detailed analysis of the functioning of a grooved heat pipe is developed in order to obtain the information required for a general analysis of such systems. (J.S.) 3 refs.

  3. Testing of a Methane Cryogenic Heat Pipe with a Liquid Trap Turn-Off Feature for use on Space Interferometer Mission (SIM)

    Science.gov (United States)

    Cepeda-Rizo, Juan; Krylo, Robert; Fisher, Melanie; Bugby, David C.

    2011-01-01

    Camera cooling for SIM presents three thermal control challenges; stable operation at 163K (110 C), decontamination heating to +20 C, and a long span from the cameras to the radiator. A novel cryogenic cooling system based on a methane heat pipe meets these challenges. The SIM thermal team, with the help of heat pipe vendor ATK, designed and tested a complete, low temperature, cooling system. The system accommodates the two SIM cameras with a double-ended conduction bar, a single methane heat pipe, independent turn-off devices, and a flight-like radiator. The turn ]off devices consist of a liquid trap, for removing the methane from the pipe, and an electrical heater to raise the methane temperature above the critical point thus preventing two-phase operation. This is the first time a cryogenic heat pipe has been tested at JPL and is also the first heat pipe to incorporate the turn-off features. Operation at 163K with a methane heat pipe is an important new thermal control capability for the lab. In addition, the two turn-off technologies enhance the "bag of tricks" available to the JPL thermal community. The successful test program brings this heat pipe to a high level of technology readiness.

  4. Determination of optimum pipe diameter along with energetic and exergetic evaluation of geothermal district heating systems. Modeling and application

    Energy Technology Data Exchange (ETDEWEB)

    Kalinci, Yildiz [Plumbing Technology, Department of Technical Programs, Izmir Vocational School, Dokuz Eyluel University, Education Campus Buca, Izmir (Turkey); Hepbasli, Arif [Department of Mechanical Engineering, Faculty of Engineering, Ege University, 35100 Bornova, Izmir (Turkey); Tavman, Ismail [Department of Mechanical Engineering, Faculty of Engineering, Dokuz Eyluel University, 35100 Bornova, Izmir (Turkey)

    2008-07-01

    This study deals with determination of optimum pipe diameters based on economic analysis and the performance analysis of geothermal district heating systems along with pipelines using energy and exergy analysis methods. In this regard, the Dikili geothermal district heating system (DGDHS) in Izmir, Turkey is taken as an application place, to which the methods presented here are applied with some assumptions. The system mainly consists of three cycles, namely (1) the transportation network, (2) the Danistay region, and (3) the Bariskent region. The thermal capacities of these regions are 21,025 and 7975 kW, respectively, while the supply (flow) and return temperature values of those are 80 and 50 C, respectively. Based upon the assessment of the transportation network using the optimum diameter analysis method, minimum cost is calculated to be US$ 561856.906 year{sup -1} for a nominal diameter of DN 300. The exergy destructions in the overall DGDHS are quantified and illustrated using exergy flow diagram. Furthermore, both energy and exergy flow diagrams are exhibited for comparison purposes. It is observed through analysis that the exergy destructions in the system particularly take place due to the exergy of the thermal water (geothermal fluid) reinjected, the heat exchanger losses, and all pumps losses, accounting for 38.77%, 10.34%, 0.76% of the total exergy input to the DGDHS. Exergy losses are also found to be 201.12817 kW and 1.94% of the total exergy input to the DGDHS for the distribution network. For the system performance analysis and improvement, both energy and exergy efficiencies of the overall DGDHS are investigated, while they are determined to be 40.21% and 50.12%, respectively. (author)

  5. One-heater flow-through polymerase chain reaction device by heat pipes cooling.

    Science.gov (United States)

    Chen, Jyh Jian; Liao, Ming Huei; Li, Kun Tze; Shen, Chia Ming

    2015-01-01

    This study describes a novel microfluidic reactor capable of flow-through polymerase chain reactions (PCR). For one-heater PCR devices in previous studies, comprehensive simulations and experiments for the chip geometry and the heater arrangement were usually needed before the fabrication of the device. In order to improve the flexibility of the one-heater PCR device, two heat pipes with one fan are used to create the requisite temperature regions in our device. With the integration of one heater onto the chip, the high temperature required for the denaturation stage can be generated at the chip center. By arranging the heat pipes on the opposite sides of the chip, the low temperature needed for the annealing stage is easy to regulate. Numerical calculations and thermal measurements have shown that the temperature distribution in the five-temperature-region PCR chip would be suitable for DNA amplification. In order to ensure temperature uniformity at specific reaction regions, the Re of the sample flow is less than 1. When the microchannel width increases and then decreases gradually between the denaturation and annealing regions, the extension region located in the enlarged part of the channel can be observed numerically and experimentally. From the simulations, the residence time at the extension region with the enlarged channel is 4.25 times longer than that without an enlarged channel at a flow rate of 2 μl/min. The treated surfaces of the flow-through microchannel are characterized using the water contact angle, while the effects of the hydrophilicity of the treated polydimethylsiloxane (PDMS) microchannels on PCR efficiency are determined using gel electrophoresis. By increasing the hydrophilicity of the channel surface after immersing the PDMS substrates into Tween 20 (20%) or BSA (1 mg/ml) solutions, efficient amplifications of DNA segments were proved to occur in our chip device. To our knowledge, our group is the first to introduce heat pipes into

  6. Heat Transfer in a Loop Heat Pipe Using Fe2NiO4-H2O Nanofluid

    Directory of Open Access Journals (Sweden)

    Gunnasegaran Prem

    2017-01-01

    Full Text Available Nanofluids are stable suspensions of nano fibers and particles in fluids. Recent investigations show that thermal behavior of these fluids, such as improved thermal conductivity and convection coefficients are superior to those of pure fluid or fluid suspension containing larger size particles. The use of enhanced thermal properties of nanofluids in a loop heat pipe (LHP for the cooling of computer microchips is the main aim of this study. Thus, the Fe2NiO4-H2O served as the working fluid with nanoparticle mass concentrations ranged from 0 to 3 % in LHP for the heat input range from 20W to 60W was employed. Experimental apparatus and procedures were designed and implemented for measurements of the surface temperature of LHP. Then, a commercial liquid cooling kit of LHP system similar as used in experimental study was installed in real desktop PC CPU cooling system. The test results of the proposed system indicate that the average decrease of 5.75oC (14% was achieved in core temperatures of desktop PC CPU charged with Fe2NiO4-H2O as compared with pure water under the same operating conditions. The results from this study should find it’s used in many industrial processes in which the knowledge on the heat transfer behavior in nanofluids charged LHP is of uttermost importance.

  7. Numerical Simulation of Heat and Flow Behaviors in Butt-fusion Welding Process of HDPE Pipes with Curved Fusion Surface

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hyun; Ahn, Kyung Hyun [Seoul National University, Seoul (Korea, Republic of); Choi, Sunwoong; Oh, Ju Seok [Hannam University, Daejeon (Korea, Republic of)

    2017-08-15

    Butt-fusion welding process is used to join the polymeric pipes. Recently, some researchers suggest the curved surface to enhance a welding quality. We investigated how curved welding surface affects heat and flow behaviors of polymer melt during the process in 2D axisymmetric domain with finite element method, and discussed the effect to the welding quality. In this study, we considered HDPE pipes. In heat soak stage, curved phase interface between the melt and solid is shown along the shape of welding surface. In jointing stage, squeezing flow is generated between curved welding surface and phase interface. The low shear rate in fusion domain reduces the alignment of polymer to the perpendicular direction of pipes, and then this phenomenon is expected to help to enhance the welding quality.

  8. INVESTIGATIONS ON DESIGN OF HEAT STORAGE PIPE CONNECTIONS FOR SOLAR COMBISYSTEMS

    DEFF Research Database (Denmark)

    Thür, Alexander; Furbo, Simon

    2005-01-01

    . In general the results showed only very little differences between external connection and internal PEX pipes, if the internal PEX pipes have thick walls. Typically used PEX pipes with only 2 mm wall thickness lead to reduced system performance compared to PEX pipes with 6 mm wall thickness and external pipe......This paper describes how different designed pipe connections on a tank for solar combisystems were evaluated based on experimental tests and theoretical investigations with the simulation tool TRNSYS. Measurement results from laboratory measurements were used to calibrate a TRNSYS model...... for simulations with parameter analysis. The possibility to connect pipes at the bottom and use internal PEX pipes to reach the inlet/outlet level in the tank was compared with the possibility to connect the pipe at the side of the tank and pass to the bottom level of the tank inside the tank insulation...

  9. ENERGY STAR Certified Geothermal Heat Pumps

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.1 ENERGY STAR Program Requirements for Geothermal Heat Pumps that are effective as of...

  10. The Energy Impacts of Solar Heating.

    Science.gov (United States)

    Whipple, Chris

    1980-01-01

    The energy required to build and install solar space- and water-heating equipment is compared to the energy saved under two solar growth paths corresponding to high and low rates of solar technology implementation. (Author/RE)

  11. Improvement on thermal performance of a disk-shaped miniature heat pipe with nanofluid.

    KAUST Repository

    Tsai, Tsung-Han

    2011-11-14

    The present study aims to investigate the effect of suspended nanoparticles in base fluids, namely nanofluids, on the thermal resistance of a disk-shaped miniature heat pipe [DMHP]. In this study, two types of nanoparticles, gold and carbon, in aqueous solution are used respectively. An experimental system was set up to measure the thermal resistance of the DMHP with both nanofluids and deionized [DI] water as the working medium. The measured results show that the thermal resistance of DMHP varies with the charge volume and the type of working medium. At the same charge volume, a significant reduction in thermal resistance of DMHP can be found if nanofluid is used instead of DI water.

  12. Balance-of-plant options for the Heat-Pipe Power System

    Energy Technology Data Exchange (ETDEWEB)

    Berte, M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Nuclear Engineering Dept.; Capell, B. [Michigan Univ., Ann Arbor, MI (United States). Nuclear Engineering Dept.

    1997-09-01

    The Heat-Pipe Power System (HPS) is a near-term, low-cost space fission power system with the potential for utilizing various option for balance-of-plant options. The following options have been studied: a low-power thermoelectric design (14-kWe output), a small Brayton cycle system (60--75 kWe), and a large Brayton cycle system (250 kWe). These systems were analyzed on a preliminary basis, including mass, volume, and structure calculations. These analyses have shown that the HPS system can provide power outputs from 10--250 kWe with specific powers of {approximately} 14 W/kg for a 14-kWe model to {approximately} 100 W/kg for a 250-kWe model. The system designs considered in this study utilize a common component base to permit easy expansion and development.

  13. Using Loop Heat Pipes to Minimize Survival Heater Power for NASA's Evolutionary Xenon Thruster Power Processing Units

    Science.gov (United States)

    Choi, Michael K.

    2017-01-01

    A thermal design concept of using propylene loop heat pipes to minimize survival heater power for NASA's Evolutionary Xenon Thruster power processing units is presented. It reduces the survival heater power from 183 W to 35 W per power processing unit. The reduction is 81%.

  14. Experimental validation of an analytical model for predicting the thermal and hydrodynamic capabilities of flat micro heat pipes

    OpenAIRE

    Revellin, Rémi; Rullière, Romuald; Lefèvre, Frédéric; Bonjour, Jocelyn

    2009-01-01

    Experimental validation of an analytical model for predicting the thermal and hydrodynamic capabilities of flat micro heat pipes correspondance: Corresponding author. Tel.: +33 4 7243 82 51; fax: +33 4 7243 8811. (Lefevre, Frederic) (Lefevre, Frederic) Centre de Thermique de Lyon (CETHIL) UMR 5008 CNRS-INSA-Univ. Lyon 1 Bat. Sadi Carnot--> , INSA-Lyon--> , F-69621 Villeurbanne Cedex--> -...

  15. Using nuclear energy for district heating

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, Yu.A.; Pleskov, G.I.; Tatarnikov, V.P.

    1982-01-01

    Problems of using nuclear energy for a centralized production of low-potential thermal energy are considered. Zones of economic effectiveness of DHP (district heating plant) and CHPP (central heating-and-power plant) in thermal loadings, optimum values of the coefficient of thermofication and the method of covering peak loadings, types of the main equipment for DHP CHPP and, are determined. The conclusion is made that for the purposes of heating three types of nuclear energy sources that accompany each other well are developed and introduced in the Soviet Union. They are CHPP, DHP and condensation NPP with heat transfer from non-controlled take-off.

  16. A RESEARCH ON VENTILATION EFFICIENCY OF PIPED VENTILATION SYSTEMS IN GEOTHERMALLY HEATED GREENHOUSES

    Directory of Open Access Journals (Sweden)

    İbrahim Örüng

    2016-07-01

    Full Text Available Greenhouse play significant roles in human nutrition. Vegetable and fruit consumption at certain amounts is the basic pre-condition for a well nutrition. It is possible to produce sufficient quantities of fruits and vegetables in places with available climate conditions. However, fruits and vegetables should be grown in special buildings to have a year-long production in places without available climate conditions. These places include under-cover production facilities, greenhouses, low and high tunnel facilities. Environmental conditions are adjusted are adjusted in greenhouses as to provide proper conditions for plant growth and development. Ventilation is used to remove excess heat, moisture and carbon dioxide from the greenhouses. Either natural or mechanical ventilation is used in greenhouses. Mechanical ventilation systems have various advantages over natural systems. However, mostly natural ventilation systems are preferred because of their low installation and operational costs. Both systems operates based on negative pressure. Air exchange rates are usually low in winters and it is quite hard to evenly distribute cold fresh air within the greenhouse. Air inlets are usually placed over side walls and outlets are commonly placed along the ridge. In this study an alternative natural ventilation system was proposed for more efficient ventilation of the greenhouses. In this system, fresh air gets into the greenhouse through ventilation pipes installed beneath the greenhouse floor. The incoming fresh air also heated with geothermal hot water lines, thus direct contact of cold fresh air is prevented. The design and efficiency of piped ventilation systems were provided in this paper.

  17. Heat Pipe Reactor Dynamic Response Tests: SAFE-100 Reactor Core Prototype

    Science.gov (United States)

    Bragg-Sitton, Shannon M.

    2005-01-01

    The SAFE-I00a test article at the NASA Marshall Space Flight Center was used to simulate a variety of potential reactor transients; the SAFEl00a is a resistively heated, stainless-steel heat-pipe (HP)-reactor core segment, coupled to a gas-flow heat exchanger (HX). For these transients the core power was controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. This type of non-nuclear test is expected to provide reasonable approximation of reactor transient behavior because reactivity feedback is very simple in a compact fast reactor (simple, negative, and relatively monotonic temperature feedback, caused mostly by thermal expansion) and calculations show there are no significant reactivity effects associated with fluid in the HP (the worth of the entire inventory of Na in the core is .concept, it was decided to use a temperature based feedback model (based on several thermocouples placed throughout the core).

  18. Theoretical analysis of start-up power in helium pulsating heat pipe

    Science.gov (United States)

    Li, Monan; Huang, Rongjin; Xu, Dong; Li, Laifeng

    2017-02-01

    An analytical model for one-turn helium pulsating heat pipes (PHPs) with single liquid slug and vapor plug is established in present study. When an additional heat power takes place in the evaporating section, temperature and pressure will increase. The pressure wave travels through vapor and liquid phases at different speed, producing a pressure difference in the system, which acts as an exciting force to start up the oscillating motion. Results show that the start-up power of helium PHP is related to the filling ratio. The start-up power increases with the filling ration. However, there exist an upper limit. Furthermore, the start-up power also depends on the inclination angle of PHP. When the inclination angle increases, the heat input needed to start up the oscillating motion decreases. But for one-turn helium PHP, it can not be started up when the inclination angle is up to 90°, equalling to horizontal position,. While the inclination angle ranges between 0° (vertical position) and 75°, it can operate successfully.

  19. Steady 3D Numerical Simulation of the Evaporator and Compensation Chamber of a Loop Heat Pipe

    Directory of Open Access Journals (Sweden)

    A. V. Nedayvozov

    2017-01-01

    Full Text Available The paper presents results of a steady three-dimensional numerical simulation of a flat evaporator and compensation chamber (CC of a loop heat pipe (LHP and describes a procedure of the thermal state calculation of the evaporator and the compensation chamber.The LHP is an efficient heat transfer device operating on the principle of evaporation-condensation cycle. It is successfully used in space technology and also to cool the heat-stressed components of electronic devices and computer equipment. The authors carried out a numerical study of the influence of the condensate pipeline length, immersed in water, on the thermal state of the evaporator and the compensation chamber.  The paper shows the influence of the mass forces field on the calculation results. Presents all the numerical studies carried out by the authors for a brass flat evaporator with a thermal load of 80 W. Water is used as a LHP heat-transfer fluid. Fields of temperature, pressure and velocity are presented for each design option.Based on the calculation results, the authors came to the following conclusions:Influence of the mass forces field for the LHP of this type is significant and leads to arising water vortex flow in the condensate pipeline and CC, thereby mixing and equalizing the water temperature in the CC and in the porous element, reducing the maximum temperature of the porous element;The increasing section length of the condensate pipeline in the CC leads to increasing velocity of the heat-transfer fluid in the CC and in the porous element, decreasing mixing zone of the condensate in the CC, and increasing temperature non-uniformity of the porous element.

  20. Rational use of energy via heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    Groscurth, H.M. (Inst. fuer Energiewirtschaft und Rationelle Energieanwendung (IER), Stuttgart Univ. (Germany))

    1992-01-01

    The linear, stochastic optimization model ECCO has been developed as a computerized planning tool for case studies on integrated energy management involving heat recovery by heat exchanger networks, heat pumps and cogeneration. The procedure of stochastic optimization is described in detail. For a model city, which consists of three districts with together nearly 20,000 inhabitants and 4 industrial companies, we obtain the following results: Via heat recovery and cogeneration, the primary energy input into the energy system of the model city may be reduced by 25% compared to a status quo scenario. At the same time, the CO[sub 2]-emissions are reduced by 31% with some fuel switching from coal to natural gas being involved. Introducing waste heat recovery and cogeneration into the model city at the current low energy price level would increase the cost of the energy system by at least 41% with respect to the status quo. (orig./BWI)

  1. The evaluation of energy efficiency of convective heat transfer surfaces in tube bundles

    Science.gov (United States)

    Grigoriev, B. A.; Pronin, V. A.; Salohin, V. I.; Sidenkov, D. V.

    2017-11-01

    When evaluating the effectiveness of the heat exchange surfaces in the main considered characteristics such as heat flow (Q, Watt), the power required for pumps (N, Watt), and surface area of heat transfer (F, m2). The most correct comparison provides a comparison “ceteris paribus”. Carried out performance comparison “ceteris paribus” in-line and staggered configurations of bundles with a circular pipes can serve as a basis for the development of physical models of flow and heat transfer in tube bundles with tubes of other geometric shapes, considering intertubular stream with attached eddies. The effect of longitudinal and transverse steps of the pipes on the energy efficiency of different configurations would take into account by mean of physical relations between the structure of shell side flow with attached eddies and intensity of transfer processes of heat and momentum. With the aim of energy-efficient placement of tubes, such an approach opens up great opportunities for the synthesis of a plurality of tubular heat exchange surfaces, in particular, the layout of the twisted and in-line-diffuser type with a drop-shaped pipes.

  2. Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

    Science.gov (United States)

    Seryakov, A. V.; Konkin, A. V.

    2017-11-01

    The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

  3. The Droplets Condensate Centering in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

    Science.gov (United States)

    Seryakov, A. V.; Shakshin, S. L.; Alekseev, A. P.

    2017-11-01

    The results of experimental studies of the process of condensate microdroplets centering contained in the moving moist vapour in the vapour channel of short heat pipes (HPs) for large thermal loads are presented. A vapour channel formed by capillary-porous insert in the form of the inner Laval-liked nozzle along the entire length of the HP. In the upper cover forming a condensation surface in the HP, on the diametrical line are installed capacitive sensors, forming three capacitors located at different distances from the longitudinal axis of the vapour channel. With increasing heat load and the boil beginning in the evaporator a large amount of moist vapour in the vapour channel of HP occur the pressure pulsation with frequency of 400-500 Hz and amplitude up to 1·104Pa. These pulsations affect the moving of the inertial droplets subsystem of the vapour and due to the heterogeneity of the velocity profile around the particle flow in the vapour channel at the diameter of microdroplets occurs transverse force, called the Saffman force and shear microdroplets to the center of vapour channel. Using installed in the top cover capacitors we can record the radial displacement of the condensable microdroplets.

  4. Optimized Heat Pipe Backup Cooling System Tested with a Stirling Convertor

    Science.gov (United States)

    Schwendeman, Carl L.; Tarau, Calin; Schifer, Nicholas A.; Anderson, William G.; Garner, Scott

    2016-01-01

    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 by bypassing the heat during stops. In a previous NASA Small Business Innovation Research (SBIR) Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for the Stirling RPS. In 2012, one of these VCHPs was successfully tested at NASA Glenn Research Center with a Stirling convertor as an Advanced Stirling Radioisotope Generator (ASRG) backup cooling system. The prototype; however, was not optimized and did not reflect the final heat rejection path. ACT through further funding has developed a semioptimized prototype with the finalized heat path for testing at Glenn with a Stirling convertor. The semioptimized system features a two-phase radiator and is significantly smaller and lighter than the prior prototype to reflect a higher level of flight readiness. The VCHP is designed to activate and remove heat from the GPHS during stoppage with a small temperature increase from the nominal vapor temperature. This small temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the multilayer insulation (MLI). The VCHP passively allows the Stirling convertor to be turned off multiple times during a mission with potentially unlimited off durations. Having the ability to turn the Stirling off allows for the Stirling to be reset and reduces vibrations on the platform during sensitive measurements or

  5. Experimental study of a novel photovoltaic solar-assisted heat pump/loop heat-pipe (PV-SAHP/LHP) system

    Science.gov (United States)

    Zhang, Tao; Pei, Gang; Zhu, Qunzhi; Ji, Jie

    2017-01-01

    A prototype of a photovoltaic solar-assisted heat-pump/loop heat-pipe system (PV-SAHP/LHP) was constructed in this paper. The system was a combination of photovoltaic solar-assisted heat pump system (PV-SAHP) and loop heat pipe photovoltaic/thermal (LHP-PV/T) system. The combined system can carry out with two modes but using the same working fluid, and the two modes can switch operation freely. R600a was employed as the working fluid, and system performance under different working mode was presented in this paper. The results show that the day average photothermal efficiency & photovoltaic efficiency can reach to 43.6% & 11.3% under LHP-PV/T working mode compared with that of 57.5% & 12.1% under PV-SAHP working mode: Besides that, a day average COP of 3.66 was obtained under PV-SAHP working mode.

  6. INVESTIGATIONS ON DESIGN OF HEAT STORAGE PIPE CONNECTIONS FOR SOLAR COMBISYSTEMS

    DEFF Research Database (Denmark)

    Thür, Alexander; Furbo, Simon

    2005-01-01

    for simulations with parameter analysis. The possibility to connect pipes at the bottom and use internal PEX pipes to reach the inlet/outlet level in the tank was compared with the possibility to connect the pipe at the side of the tank and pass to the bottom level of the tank inside the tank insulation...

  7. Heat Pipe and Thermal Energy Storage and Corrosion Studies (1988)

    Science.gov (United States)

    1989-06-01

    distribution near end cap showing alumina in crevice due to polishing ......... 71 38. Norma !;ised change in concentration of constituents in #14...BSE image of grain boundary near the edge. Figure 29. Images neai inner edge of sample # 17. 63 40b a. SEI of outer edge profile. APA ’’IP b. 13SE of

  8. Use matrix for district heating pipes to provide cooling; Einsatzmatrix fuer Fernwaermerohre in der Kaelteversorgung. Untersuchungen zur Wasserdampfdiffusion

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, D. [Universitaet Hannover (Germany). Inst. fuer Energietechnik; Pareidt, H. [Fernwaerme-Forschungsinstitut in Hannover e.V., Hemmingen (Germany)

    2003-10-01

    The use of conventional district heating (DH) pipes in cooling systems represents an interesting expansion of business for the DH industry. However, other demands are also being made on the pipe systems, due to changes in the conditions of use. In particular, penetration of the insulating layer by ambient moisture in the form of water vapour diffusion may restrict fitness for use under certain conditions. In addition, the optimum insulating layer thickness for cold transport must be identified and compared with the insulation thickness of commercially-available DH pipes. Initial experimental examinations of water vapour diffusion processes at different media temperatures have therefore been carried out on DH pipe systems within the scope of the 'Use of district heating components in air conditioning and process cooling supply systems' at the District Heating Research Institute in Hanover. (orig.) [German] Der Einsatz von Fernwaermerohrsystemen in der Kaelteversorgung stellt fuer die Fernwaermebranche eine interessante Geschaeftsfelderweiterung dar. Aufgrund der veraenderten Einsatzbedingungen werden jedoch andere Anforderungen an die Rohrsysteme gestellt. Am Fernwaerme-Forschungsinstitut in Hannover soll daher eine Einsatzmatrix erstellt werden, mit der die Einsatztauglichkeit bewertet werden kann. (orig.)

  9. The energy transfer mechanism of a perturbed solid-body rotation flow in a rotating pipe

    Science.gov (United States)

    Feng, Chunjuan; Liu, Feng; Rusak, Zvi; Wang, Shixiao

    2017-04-01

    Three-dimensional direct numerical simulations of a solid-body rotation superposed on a uniform axial flow entering a rotating constant-area pipe of finite length are presented. Steady in time profiles of the radial, axial, and circumferential velocities are imposed at the pipe inlet. Convective boundary conditions are imposed at the pipe outlet. The Wang and Rusak (Phys. Fluids 8:1007-1016, 1996. doi: 10.1063/1.86882) axisymmetric instability mechanism is retrieved at certain operational conditions in terms of incoming flow swirl levels and the Reynolds number. However, at other operational conditions there exists a dominant, three-dimensional spiral type of instability mode that is consistent with the linear stability theory of Wang et al. (J. Fluid Mech. 797: 284-321, 2016). The growth of this mode leads to a spiral type of flow roll-up that subsequently nonlinearly saturates on a large amplitude rotating spiral wave. The energy transfer mechanism between the bulk of the flow and the perturbations is studied by the Reynolds-Orr equation. The production or loss of the perturbation kinetic energy is combined of three components: the viscous loss, the convective loss at the pipe outlet, and the gain of energy at the outlet through the work done by the pressure perturbation. The energy transfer in the nonlinear stage is shown to be a natural extension of the linear stage with a nonlinear saturated process.

  10. Research on Heat Recovery Technology for Reducing the Energy Consumption of Dedicated Ventilation Systems: An Application to the Operating Model of a Laboratory

    Directory of Open Access Journals (Sweden)

    Lian Zhang

    2016-01-01

    Full Text Available In this research, the application of heat pipes in the air handler dedicated to decoupling dehumidification from cooling to reduce energy consumption was simulated and investigated by simulations and experimental studies. The cooling load profiles and heat pipes with effectiveness of 0.45 and 0.6, respectively, were evaluated in achieving the desired space conditions and calculated hour by hour. The results demonstrated that for all examined cases, a heat pipe heat exchanger (HPHX can be used to save over 80% of the energy during the hours of operation of air conditioning. The overall energy reduction rate was from 3.2% to 4.5% under air conditioning system conditions. It was found that the energy saving potential of a laboratory was higher than for other kinds of buildings. Therefore, the dedicated ventilation system combined with heat recovery technology can be efficiently applied to buildings, especially for laboratories in subtropical areas.

  11. New encapsulation method using low-melting-point alloy for sealing micro heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Congming; Wang, Xiaodong; Zhou, Chuanpeng; Luo, Yi; Li, Zhixin; Li, Sidi [Dalian University of Technology, Dalian (China)

    2017-06-15

    This study proposed a method using Low-melting-point alloy (LMPA) to seal Micro heat pipes (MHPs), which were made of Si substrates and glass covers. Corresponding MHP structures with charging and sealing channels were designed. Three different auxiliary structures were investigated to study the sealability of MHPs with LMPA. One structure is rectangular and the others are triangular with corner angles of 30° and 45°, respectively. Each auxiliary channel for LMPA is 0.5 mm wide and 135 μm deep. LMPA was heated to molten state, injected to channels, and then cooled to room temperature. According to the material characteristic of LMPA, the alloy should swell in the following 12 hours to form strong interaction force between LMPA and Si walls. Experimental results show that the flow speed of liquid LMPA in channels plays an important role in sealing MHPs, and the sealing performance of triangular structures is always better than that of rectangular structure. Therefore, triangular structures are more suitable in sealing MHPs than rectangular ones. LMPA sealing is a plane packaging method that can be applied in the thermal management of high-power IC device and LEDs. Meanwhile, implanting in commercialized fabrication of MHP is easy.

  12. Testing of a Loop Heat Pipe Subjective to Variable Accelerations. Part 1; Start-up

    Science.gov (United States)

    Ku, Jentung; Rogers, Paul; Hoff, Craig

    2000-01-01

    The effect of accelerating forces on the performance of loop heat pipes (LHP) is of interest and importance to terrestrial and space applications. They are being considered for cooling of military combat vehicles and for spinning spacecraft. In order to investigate the effect of an accelerating force on LHP operation, a miniature LHP was installed on a spin table. Variable accelerating forces were imposed on the LHP by spinning the table at different angular speeds. Several patterns of accelerating forces were applied, i.e. continuous spin at different speeds and periodic spin at different speeds and frequencies. The resulting accelerations ranged from 1.17 g's to 4.7 g's. This paper presents the first part of the experimental study, i.e. the effects of a centrifugal force on the LHP start-up. Tests were conducted by varying the heat load to the evaporator, sink temperature, magnitude and frequency of centrifugal force, and LHP orientation relative to the direction of the accelerating force. The accelerating force seems to have little effect on the loop start-up in terms of temperature overshoot and superheat at boiling incipience. Changes in these parameters seem to be stochastic with or without centrifugal accelerating forces. The LHP started successfully in all tests.

  13. Cryogenic Loop Heat Pipes for the Cooling of Small Particle Detectors at CERN

    CERN Document Server

    Pereira, H; Silva, P; Wu, J; Koettig, T

    2010-01-01

    The loop heat pipe (LHP) is among the most effective heat transfer elements. Its principle is based on a continuous evaporation/condensation process and its passive nature does not require any mechanical devices such as pumps to circulate the cooling agent. Instead a porous wick structure in the evaporator provides the capillary pumping forces to drive the fluid [1]. Cryogenic LHP are investigated as potential candidates for the cooling of future small-scale particle detectors and upgrades of existing ones. A large spectrum of cryogenic temperatures can be covered by choosing appropriate working fluids. For high luminosity upgrades of existing experiments installed at the Large Hadron Collider (LHC) (TOTEM) and planned ones (FP420) [2-3] being in the design phase, radiation-hard solutions are studied with noble gases as working fluids to limit the radiolysis effect on molecules detrimental to the functioning of the LHP. The installation compactness requirement of experiments such as the CAST frame-store CCD d...

  14. Modal analysis of main steam line piping under high energy line break condition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Jin; Kim, Seung Hyun; Je, Sang-Yun; Chang, Yoon-Suk [Kyung Hee University, Yongin (Korea, Republic of)

    2016-10-15

    If HELB (High Energy Line Break) occurs in NPPs (Nuclear Power Plants), not only environmental effect like release of radioactive material but also secondary structural defects should be considered. Jet impingement phenomenon caused by sudden pipe rupture may lead to severe damage on neighboring safe-related components and other structure. Lots of studies have been conducted to assess dynamic behaviors of the SG and MSL piping while pipe whip restraints and jet impingement shields are taken into account during design stage. Arroyo et al. performed modal analyses of a simple square component to examine the jet impingement phenomenon. Also, structural characteristics were predicted to assure structural integrity against the HELB. In this study, we examined dynamic characteristics of SG and MSL piping in a typical 1000MWe NPP. Simulation was performed by using two commercial computational softwares. In particular, modal analyses were conducted to determine mode shapes and natural frequencies of the structure and maximum displacements. The data obtain from each software were compared and observation was discussed in relation to the jet impingement phenomenon. In this research, modal analyses on the SG and MSL piping were carried out to get natural frequencies, vibration mode shapes and maximum displacements. Thereby, the following key finding was observed. (1) Maximum displacement was calculated at the top of SG outlet nozzle with y-directional bending at the third mode. (2) The differences between two models were respectively 7% in natural frequencies and less than 1% in maximum displacements.

  15. Energy efficient ammonia heat pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Claus; Pijnenburg, B.; Schumann Grindorf, H. [Danish Technological Institute, Aarhus (Denmark); Christensen, Rolf [Alfa Laval, Lund (Sweden); Rasmussen, Bjarne D. [Grundfos, Bjerringbro (Denmark); Gram, S.; Fredborg Jakobsen, D. [Svedan Industri Koeleanlaeg, Greve (Denmark)

    2013-09-15

    The report describes the development of a highly effective ammonia heat pump. Heat pumps play an increasingly important role in the search for more effective use of energy in our society. Highly efficient heat pumps can contribute to reduced energy consumption and improved economy of the systems which they are a part of. An ammonia heat pump with high pressure reciprocating compressor and a novel split condenser was developed to prove potential for efficiency optimization. The split of the condenser in two parts can be utilized to obtain smaller temperature approaches and, thereby, improved heat pump efficiency at an equal heat exchanger area, when compared to the traditional solution with separate condenser and de-superheater. The split condenser design can also be exploited for heating a significant share of the total heating capacity to a temperature far above the condensing temperature. Furthermore, the prototype heat pump was equipped with a plate type evaporator combined with a U-turn separator with a minimum liquid height and a liquid pump with the purpose of creating optimum liquid circulation ratio for the highest possible heat transfer coefficients at the lowest possible pressure drop. The test results successfully confirmed the highest possible efficiency; a COP of 4.3 was obtained when heating water from 40 deg. C to 80 deg. C while operating with evaporating/condensing temperatures of +20 deg C/+73 deg C. (Author)

  16. An experimental investigation of the interfacial condensation heat transfer in steam/water countercurrent stratified flow in a horizontal pipe

    Energy Technology Data Exchange (ETDEWEB)

    Chu, In Cheol; Yu, Seon Oh; Chun, Moon Hyun [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Kim, Byong Sup; Kim, Yang Seok; Kim, In Hwan; Lee, Sang Won [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    An interfacial condensation heat transfer phenomenon in a steam/water countercurrent stratified flow in a nearly horizontal pipe has been experimentally investigated. The present study has been focused on the measurement of the temperature and velocity distributions within the water layer. In particular, the water layer thickness used in the present work is large enough so that the turbulent mixing is limited and the thermal stratification is established. As a result, the thermal resistance of the water layer to the condensation heat transfer is increased significantly. An empirical correlation of the interfacial condensation heat transfer has been developed. The present correlation agrees with the data within {+-} 15%. 5 refs., 6 figs. (Author)

  17. Application of Waste Heat Recovery Energy Saving Technology in Reform of UHP-EAF

    Science.gov (United States)

    Zhao, J. H.; Zhang, S. X.; Yang, W.; Yu, T.

    2017-08-01

    The furnace waste heat of a company’s existing 4 × 100t ultra-high-power electric arc furnaces is not used and discharged directly of the situation has been unable to meet the national energy-saving emission reduction requirements, and also affected their own competitiveness and sustainable development. In order to make full use of the waste heat of the electric arc furnace, this paper presents an the energy-saving transformation program of using the new heat pipe boiler on the existing ultra-high-power electric arc furnaces for recovering the waste heat of flue gas. The results show that after the implementation of the project can save energy equivalent to 42,349 tons of standard coal. The flue gas waste heat is fully utilized and dust emission concentration is accorded with the standard of Chinese invironmental protection, which have achieved good results.

  18. Development and characterization of high collapse boron alloys heat treated pipes for oil wells; Tubos de aco TiB para aplicacao em revestimento de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Fabio A.; Silva, Ronaldo; Chad, Luis [Tenaris Confab, Pindamonhangaba SP (Brazil); Fritz, Marcelo C. [Tenaris Confab, Pindamonhangaba SP (Brazil). Dept. de Engenharia do Produto

    2008-07-01

    The utilization of OCTG (Oil Country Tubular Goods) pipes will increase with the discovery of new oil wells in ultra deep waters. This study aims to evaluate the mechanical and microstructural performance of welded and heat treated pipes through quenching and tempering using a steel project based in titanium/boron for casing pipes. The objective of this development is to present a set of techniques used during the manufacturing of heated treated ERW pipes boron allowing, discussing mechanical and metallurgical aspects of the steel project, coil conformation, heat treatment and test procedures. The results are within the limits set by the API 5CT standard. It was found that the pipes obtained good geometry and uniformity of mechanical properties, showing that this product can be applied safely and reliability as wells' casing. (author)

  19. Effects of Induction Heat Bending and Heat Treatment on the Boric Acid Corrosion of Low Alloy Steel Pipe for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Tae; Kim, Young-Sik [Andong National University, Gyeongbuk (Korea, Republic of); Chang, Hyun-Young; Park, Heung-Bae [KEPCO EandC, Gyeongbuk (Korea, Republic of); Sung, Gi-Ho; Shin, Min-Chul [Sungil SIM Co. Ltd, Busan (Korea, Republic of)

    2016-11-15

    In many plants, including nuclear power plants, pipelines are composed of numerous fittings such as elbows. When plants use these fittings, welding points need to be increased, and the number of inspections also then increases. As an alternative to welding, the pipe bending process forms bent pipe by applying strain at low or high temperatures. This work investigates how heat treatment affects on the boric acid corrosion of ASME SA335 Gr. P22 caused by the induction heat bending process. Microstructure analysis and immersion corrosion tests were performed. It was shown that every area of the induction heat bent pipe exhibited a high corrosion rate in the boric acid corrosion test. This behavior was due to the enrichment of phosphorous in the ferrite phase, which occurred during the induction heat bending process. This caused the ferrite phase to act as a corrosion initiation site. However, when re-heat treatment was applied after the bending process, it enhanced corrosion resistance. It was proved that this resistance was closely related to the degree of the phosphorus segregation in the ferrite phase.

  20. A comparison study on energy savings and fungus growth control using heat recovery devices in a modern tropical operating theatre

    Energy Technology Data Exchange (ETDEWEB)

    Yau, Y.H., E-mail: yhyau@um.edu.m [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ng, W.K. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2011-04-15

    Research highlights: {yields} The paper can be used as a comprehensive guide for building services engineers. {yields} Energy is wasted in overcooling and reheating processes in the reheat system. {yields} The recovery wheel integrated system is a good choice for heat recovery purpose. {yields} The heat pipe heat exchanger system is the best choice for energy saving purpose. -- Abstract: Fungus growth has always been a problem in hot and humid areas. This particular problem is crucial for operating theatre as it could affect the success rate of operations. Many postoperative fungus infection cases had occurred in the past, and it is generally agreed that air-conditioning system play a very important role in resolving the fungus growth problem. Besides air quality, the energy consumption level of air-conditioning system is also very important. In this study, the operating theatre 3 in Putrajaya Hospital, Malaysia was chosen as the research subject. The air-conditioning system for OT3 was redesigned with the energy recovery wheel, desiccant dehumidifier and heat pipe heat exchanger to achieve the objectives of this study. A computer program called Transient system simulation program (TRNSYS) was utilized for analysis in this research. From the outcome of simulations, it was found that the heat pipe heat exchanger could reduce the most energy consumed by the air-conditioning system. It managed to reduce the energy consumption by 57.85%. Moreover, the payback period of the device is only 0.95 years, which is the shortest among all the systems studied. Therefore, applying heat pipe heat exchanger is a good choice to save energy and resolve fungus growth problem in hot and humid areas.