Counterintuitive phenomena arise from the interfacial and surface forces that operate in heat pipes. Amir faghri department of mechanical engineering, university of connecticut, storrs, ct 06269, u. Jun 18, 20 heat pipe applications electronics cooling small high performance componentscause high heat fluxes and high heat dissipation demands. The lengths of the evaporator, adiabatic and condenser sections are 500mm for each section. Validated trnsys model for forced circulation solar water.
A longer heat pipe transports less heat versus the same heat pipe with a shorter length. Other advantages of heat pipes are their passive operation, long life. Heat pipe test supplementary table 2 the data presented in this file is the transient air temperature formations downstream of the heat pipes in response to the source temperature in both conduction and convection modes. Recently heat pipe heat exchanger is widely used in solar applications for its high thermal performance. Introduction heat pipe is a capillary twophase heat transfer device. Pdf experimental investigation of the thermal performance of a. Used to cool transistors and high density semiconductors. The cvb represents a passive, wickless heat pipe ideally suited to obtain engineering and fundamental data on phase change heat transfer driven by interfacial phenomena. Bendable heat pipes advanced thermal solutions, inc. Heat pipe wick structures are constructed from various materials and methods. The pipes are dipped in a molten zinc bath at a temperature of 450o c to get the proper adherent coating.
Inwip innovative wickless heat pipe systems for ground. These parameters include global solar radiation intensity, inlet cooling water temperature, absorber plate material and thickness, ratio of pitch distance to wickless heat pipe diameter and ratio of condenser section length to total wickless heat pipe length. Additionally, cfd models can reduce the amount of experimental work. Optimization of a wickless heat pipe flat plate solar. Beginning with a definition of the problem, including the temperature.
The transient thermal behaviour of wickless heat pipe flat plate solar collectors has been analyzed with regard to various parameters. Pdf investigation on the performance of a wicklessheat. As reported in chapter 2, modification in the crosssectional area of a heat pipe resulted in the increase in thermal performance and heat transfer characteristics of wickless heat pipes and in. Transient temperature distributions in the heat pipe walls and wicks are presented. But, in practice, there is seldom any space available that can. The research and development activity in the heat pipe field allowed the company to develop an internal numerical model that, coupled with an optimization model, permits the design of heat pipes maximizing efficiency with the correct selection of macroscopic geometry tube diameter and length and microscopic groove. The heat pipe cooling system studies reported herein in cluded the following tasks.
Heat pipe wicklesssimulation on fluentmultiphase page. Their heat transfer coefficient in the evaporator and condenser zones is 103105 wm2 k, heat pipe thermal resistance is 0. Depending on the type of heat pipe, the liquid is recirculated to the evaporator via capillary, gravitational, or centrifugal forces. Wickless network heat pipes for high heat flux spreading. The result is less pumping of the wick with reduced heat transfer. Three cases with volume fraction 0, 1% and 4% for cuo are considered. The vapor travels along the heat pipe to the condenser, reliquifies and releases its latent heat, eventually returning to the evaporator, without any moving parts. Also heat pipe experiments were conducted aboard the applications technology satellite6, in which an ammonia heat pipe with a spiral artery wick was used as a thermal diode. Cfd study of the heat pipes with water nanoparticles mixture. Pdf performance investigation of a wickless heat pipe.
To enhance the thermal safety in case of station blackout, a wickless heat pipe is proposed as an alternative passive cooling system technology to remove decay heat generation in the nuclear spent. Heat pipes application to solar energy systems springerlink. A heat flux of 4 wcm2 is about two to three times of the value generally accepted as the limit by forced air cooling together with heat pipes kishimoto et al. Argotec is an aerospace engineering company based in turin whose research, innovation and product development activities use engineering and computing for space applications and renewable energy systems. A typical heat pipe is a cylindrical straight pipe which is easy to fabricate and has a low cost of production. A heat pipe is a twophase heat transfer device with a highly effective heat transfer rate through evaporating and condensing a fluid that is circulating in a sealed container. Performance of a wickless heat pipe operating with. Heat exchangers power industries use heat pipe heatexchangers as.
A wickless heat pipe, or a twophase closed thermosyphon, relies on gravitational forces to return the working fluid to the evaporator. As reported in chapter 2, modification in the crosssectional area of a heat pipe resulted in the increase in thermal performance and heat transfer characteristics of wickless heat pipes and in this context the present research aims to design and. In this chapter, design and manufacturing of wickless heat pipe is discussed. Heat pipes are widely used both to improve the outdated equipment, increase its efficiency, reliability. 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. The graph also shows that if the heat pipe is operated against the force of gravity, the liquid undergoes a larger pressure drop. Investigation on the performance of a wicklessheat pipe.
It consists of a vacuumtight copper tube containing a wick and a nontoxic working fluid. If heat pipe pa take out and let ai below sol end of a heatp ipe 1015 mm. If the pipe is half a meter, it can carry twice the wattage. This twodimensional, axisymmetric formulation accounts for the thin liquid condensate film on the inner surface of the rotating pipe wall, the vapor flow in the vapor space, and the unsteady heat conduction in the pipe wall. Heat pipe wicklesssimulation on fluentmultiphase cfd. The wickless heat pipe was designed to transfer the heat of 850 w at.
The system required can be as simple as a circular system with one half being heated and one half being cooled driving a flow. How should i go about designing a wickless heat pipe. Originally posted by repudaman please someone upload the mesh file for the heat pipe 2d. Some heat pipes can operate in any orientation, since they use the capillary pumping action of the wick structure to return working fluid from the condenser back to the evaporator. The water is then passed to the inlet of the condenser section. Heat pipe wicklesssimulation on fluentmultiphase page 2. The latent heat is a considerable factor in calculating the performance of the hphe in humid conditions.
Advanced cooling technologies yale eastman currently a director of act, a few years later describes the theory and history of the heat pipe technology in an article published in. A heat pipe is a heattransfer device that combines the principles of both thermal conductivity and phase transition to effectively transfer heat between two solid interfaces. The paper presents an overview of heat pipes, especially those used in different space missions. Jul 22, 2019 heat pipe characteristics are linked to the surface properties of the diabatic surfaces, and, in the evaporator, surface properties influence both the onset boiling temperature t onb and the critical heat flux chf. If a heat pipe length is less than 150 mm, at 40c it passes. Normally, heat pipes contain porous metal wicks that return liquid to the heated end of the pipe where it evaporates. Find support for a specific problem on the support section of our website.
But engineers are working to develop wickless heat pipes that are lighter and. Hence, a gap still exists for further cfd work to model a wickless heat pipe. Generally made up of copper tube having inner lining of wick structure in it. Hence the major component of the system is flat plate heat pipe solar collector with wickless heat pipe.
The oscillating heat pipe ohp is a novel, wickless heat pipe that relies on the phase change induced motion of a contained working fluid to transport heat between the evaporator and condenserthis paper investigates the effects of. Pdf cfd analysis of a wickless heat pipe researchgate. Heat pipe are device having very high conductivity can transfer large amount of heat away from source. The condensate returns to the evaporator as a liquid film on a tube wall. Acordingly in this case, reflux condensation heat transfer takes place between upgoing vapor flow and downcoming liquid film flow, as for example, in a vertical twophase thermosyphon, i.
They transfer heat from one point to another through an evaporationcondensation process and are used in everything from cell phones and laptops to air conditioners and spacecraft. An experimental study of smalldiameter wickless heat pipes. Aerospace cool satellite solar array, as well as shuttleleading edge during reentry. Jan 12, 2016 i do not have much experience with lab scale equipment, but can provide some points which might help. Apr 15, 2016 today widespread application of energysaving equipment based on heat pipes makes a significant contribution to the task of resources saving. Within the tests, the temperature dissemination on the wickless warm pipe surface and the temperature contrasts of the cooling water were measured. A schematic diagram of a heat pipe and the associated heat flow mechanismbthe two phase thermosyphon.
A heat pipe laser mirror was designed and fabricated in order to test the feasibility of this technology compared to watercool or uncooled mirrors for high power lasers 15. Loop heat pipe with coherent porous wick since the porous material used for current heat pipes is usually stochastic structure, it is hard to apply analytical or numerical methods for design optimization. The water is used as a base working fluid while the nanoparticles used in the present study are the copper oxide nanoparticles. The overall system performance of wickless heat pipe thermosyphon parabolic trough solar collector with evacuated glass tube and with tracking system has been. The results of this study are summarized in appendix a. If a heat pipe length is larger than 150 mm, at 5 oc it passes. As the vapour reaches the condensing area of the heat pipe, heat is released to the cooler air and the vapour condenses.
Also explore the seminar topics paper on heat pipe with abstract or synopsis, documentation on advantages and disadvantages, base paper presentation slides for ieee final year mechanical engineering me or production automobile students for the year 2019 2020. The loop heat pipe lhp was invented in russia in the early 1980s. The research study is focused on the numerical and experimental investigation of three different twophase heat transfer devices. Ats engineering ebook advanced thermal solutions, inc. Pdf experimental investigation of an inclinedcondenser. At the heat source, or evaporator, the liquid absorbs heat and vaporizes. Development of wickless heat pipe flat plate solar collector. Wind tunnel data of the analysis of heat pipe and wind. The minimum amount of working liquid fill volume in a wickless heat pipe for given working fluids acetone, ethanol, methanol and water depends upon the amount of heat to be transferred, vapor temperatures, working fluid properties and dimensions of the wickless heat pipe. The measurements were recorded at onesecond intervals for a total duration of 86,400 s on 24 h. Pdf on jan 1, 2018, sagar singhal and others published cfd analysis of a wickless heat pipe find, read and cite all the research. The im of the cooling capacity up to heat flux of 4 wcm2 was achieved. It is a twophase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat, and the capillary forces developed in fine porous wicks to circulate the fluid.
It is the prototype for a wickless heat pipe and is the first full scale fluids experiment as sketched in figure 3, flown on the us module of the iss. The heat pipe is made from copper tube with the outer diameter 8. Wickless heat pipes, also known as twophase closed ther mosyphons, are hermetically sealed tubes containing a working fluid in both the. New dynamics exposed in a nearweightless environment working with nasa, researchers expose dynamics in wickless heating pipes operating in a microgravity environment that. Wickless pulsating heatpipe systems engineering update. The amount of heat transfer decrease depends on the particular heat pipe.
Explore heat pipe with free download of seminar report and ppt in pdf and doc format. 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. One end of the heat pipe is an evaporator, the opposite end is a condenser. Other advanced heat pipe wick structures include arteries, bidispersed sintered powder and composite wick structures. A heat pipe is partially filled with a working fluid, such as water, and then sealed.
The present study is concerned with a cooling package system for electronic components such as multichip modules mcm which are used in many electronic system. It uses a cuvette pipe, which is a rectangularshaped glass tube made of quartz, filled with a fluid called pentane. The udf didnt work on ansys 16 due to some bug in the program, so you should use ansys 15 or 17 instead. Efficient heat transferefficient heat transfer boiling and condensationboiling and condensation small temperature difference between the heat source and. Wick structure problem description a heat pipe with minimum heat transport of 25 w is going to be used for cooling electronic components. Further, a cfd simulation of a wickless heat pipe that considers all the details of heat transfer phenomena inside the heat pipe has not yet been reported. Twodimensional rotating heat pipe analysis journal of heat. Inwip innovative wickless heat pipe systems for ground and.
Comparison between a heat pipe and a thermosyphon performance. If a heat pipe length is larger than 150 mm, at 5 oc it. New dynamics exposed in a nearweightless environment working with nasa, rensselaer researchers expose dynamics in wickless heating pipes operating in a microgravity environment that could advance heat pipe technology for space applications by scer staff. In fig 3, the unit of the yaxis is q maxl eff wm representing the amount of heat a pipe can carry per meter length. Experimental investigation of an inclinedcondenser wickless heat pipe charged with water and an ethanolwater azeotropic mixture. Rexus consists of a bended aluminium tube surrounded by metal foam and inserted into a metal box filled with paraffin wax.
Its one of two prototypes manufactured for the inwip project innovative wickless heat pipe systems in order to study the behaviour of a pulsating heatpipe system in microgravity conditions. Bendable heat pipes a capillary pumped heat pipe is a most efficient, and yet very simple, device. Twodimensional rotating heat pipe analysis journal of. Towards a durable polymeric internal coating for diabatic. The proposed study represents a basic scientific study in interfacial phenomena, microgravity fluid physics and thermodynamics, a basic study in thermal transport and an. Project description by means of knowledge about the theory of heat pipes, one is now able to carry out a basic calculation of a heat pipe. The driving mechanism in the heat pipe is the heat figure1. Heat pipes and its applications lunds tekniska hogskola. After washing the pipe is dipped in the solution of zinc chloride and ammonia chloride to give a base metal for better pickup of zinc on steel surface. The innovative wickless heat pipe systems for ground and space applications inwip project, funded by esa, aims at designing, manufacturing and testing innovative wickless heat pipes with enhanced performances and reliability for both space and ground applications. Experimental studies on porous wick flat plate heat pipe.
In this paper, a comprehensive cfd modelling was built to simulate the details of the twophase flow and heat transfer phenomena during the operation of a wickless heat pipe or thermosyphon, that. A copperwater heat pipe mirror was constructed, which was not affected by the problems associated with conventional mirrors due to the heat pipe action. While the best thermal performance was achieved at a filing ratio of 80 %, higher heat load, and higher coolant volumetric flow rate. An experimental study of smalldiameter wickless heat. The amount of heat transfer decrease depends on the particular heat. I am not able to separate the water and vapor regions and heat pipe wicklesssimulation on fluentmultiphase page 2 cfd online discussion forums. Several factors have contributed to the science and technology of the present stateofart heat pipe leading to the development of loop heat pipes, micro and miniature heat pipes and micro loop heat pipes. Applications of wickless heat pipe heat exchangers in hvac.
With the use5 of the space shuttle, flight testing of prototype heat pipe designs continued at a much larger scale. The liquid returns by gravity to complete the cycle. Transports heat from a heat source to a heat sink works as an isothermalizer why twophase thermal system. A detailed transient numerical simulation of rotating heat pipes is presented.
Heat pipe is a capillary twophase heat transfer device. Historical perspectives, principles of operations, types of heat pipes are discussed. In this work, the effect of surface wettability in pool boiling heat transfer is studied in order to understand if there could be a path to increment heat pipe thermal performance. Surface weapons center, 18 different heat pipe cooling system concepts were defined and evaluated. Heat pipes heat pipes how and where heat pipes work the dme heat pipe is a heat transfer device specifically designed for optimal performance in plastic injection moulds. Experimental investigation of the thermal performance of a. In this work, the effect of surface wettability in pool boiling heat transfer is studied in order to understand if there could. Particular attention is also given to the field of human space flight and operations as well as the development of space exploration systems. The information were utilized to calculate the warm resistance and heat. A heat pipe with no wick structure is often referred to as a thermosyphon. Tubes, condensation in atoz guide to thermodynamics, heat. The maximum heat flux achieved was more than 110 w cm 2 with a total heat input of about 393 w. The limitations of the capillary pumped heat pipes can be overcome through the use of. I do not have much experience with lab scale equipment, but can provide some points which might help.
A loop heat pipe with coherent pores integrated to the heat source is considered as a calculation model in this paperfig. Heat pipe characteristics are linked to the surface properties of the diabatic surfaces, and, in the evaporator, surface properties influence both the onset boiling temperature t onb and the critical heat flux chf. I succeeded in simulation of a 2d heat pipe using fluent 17 vof multiphase model with hooking udf with the case. The network heat pipe was a wickless heat pipe that is capable of spreading heat from a concentrated heat source to a large surface area with low manufacturing costs. On the basis of relative weight and volume, five concepts were selected for further evaluation. The entire heat transfer process occurs with a very small temperature difference along the pipe. Bstract a detailed overview of heat pipes is presented in this paper, including a historical perspective, principles of operations, types of. Using the heat pipes as heat transfer and heat exchange design elements allows creating new effective equipment generation for solar energy systems. Heat pipes are devices to keep critical equipment from overheating. The thermal resistance of vertical straight wicklessheat pipe using graphene nanofluid and demineralized water were 0.
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