Operational Limitations of Heat Pipes With Silver-Water Nanofluids

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Lazarus Godson Asirvatham ◽  
Rajesh Nimmagadda ◽  
Somchai Wongwises
Keyword(s):  
Silver Nanoparticles ◽  
Heat Pipe ◽  
Heat Load ◽  
Operating Temperature ◽  
Particle Diameter ◽  
Heat Pipes ◽  
Working Fluid ◽  
Limit Value ◽  
Capillary Limit ◽  
Nanoparticles Concentration

The paper presents the enhancement in the operational limits (boiling, entrainment, sonic, viscous and capillary limits) of heat pipes using silver nanoparticles dispersed in de-ionized (DI) water. The tested nanoparticles concentration ranged from 0.003 vol. % to 0.009 vol. % with particle diameter of <100 nm. The nanofluid as working fluid enhances the effective thermal conductivity of heat pipe by 40%, 58%, and 70%, respectively, for volume concentrations of 0.003%, 0.006%, and 0.009%. For an input heat load of 60 W, the adiabatic vapor temperatures of nanofluid based heat pipes are reduced by 9 °C, 18 °C, and 20 °C, when compared with DI water. This reduction in the operating temperature enhances the thermophysical properties of working fluid and gives a change in the various operational limits of heat pipes. The use of silver nanoparticles with 0.009 vol. % concentration increases the capillary limit value of heat pipe by 54% when compared with DI water. This in turn improves the performance and operating range of the heat pipe.

scholarly journals Improvement of Heat Pipe Solar Collector Thermal Efficiency Using Al2O3/Water and TiO2/Water Nanofluids

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sinan Ünvar ◽  
Tayfun Menlik ◽  
Adnan Sözen ◽  
Hafız Muhammad Ali
Keyword(s):  
Heat Pipe ◽  
Heat Exchangers ◽  
Base Fluid ◽  
Operating Temperature ◽  
Pure Water ◽  
Heat Pipes ◽  
Working Fluid ◽  
Solar Collectors ◽  
Instantaneous Power ◽  
Operating Temperature Range

Heat pipe solar collectors (HPSCs) are heat exchangers that carry heat based on the phase change of the heat pipe working fluid. It is aimed to increase the operating temperature range of solar collectors by changing the phase of the working fluid in the heat pipe at low temperature. For this reason, it has become widespread to use nanofluids obtained by mixing nanosized metal oxides with the base fluid in certain proportions in order to increase both the thermal conductivity of the heat pipe working fluids and to increase the specific heat closures. The main purpose of this study, which was conducted to evaluate the performance of HPSCs, is to increase performance, and an experimental study has been conducted in this direction. For this purpose, an HPSC designed and manufactured was used. Al2O3-water and TiO2-water nanofluids containing 2% nanoparticles were used in order to increase performance in the study. HPSC used in the study consists of 8 heat pipes with a length of 100 cm. The experiments were carried out for pure water and nanofluids, and their efficiency and strength were compared. The highest value of instantaneous efficiency was calculated as 48% when pure water was used as the working fluid, 58% for Al2O3-water nanofluid, and 64% for TiO2-water nanofluid. The instantaneous power obtained using pure water was determined as 135.66 W, 167.96 W for Al2O3-water nanofluid, and 184.03 W for TiO2-water nanofluid. The improvement in efficiency was determined as 20.8% for Al2O3-water nanofluid and 33.3% for TiO2-water nanofluid. Improvement in powers was found to be 23.8% for Al2O3-water nanofluid and 35.6% for TiO2-water nanofluid.

The Effect of Working Fluid Inventory on the Performance of Revolving Helically Grooved Heat Pipes

2000 ◽  
Vol 123 (1) ◽  
pp. 120-129 ◽  
Author(s):  
R. Michael Castle ◽  
Scott K. Thomas ◽  
Kirk L. Yerkes
Keyword(s):  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Maximum Heat ◽  
Limit Model ◽  
Filling Station ◽  
Capillary Limit ◽  
Helical Groove ◽  
Wick Structure ◽  
Evaporative Heat Transfer

The results of a recently completed experimental and analytical study showed that the capillary limit of a helically-grooved heat pipe (HGHP) was increased significantly when the transverse body force field was increased. This was due to the geometry of the helical groove wick structure. The objective of the present research was to experimentally determine the performance of revolving helically-grooved heat pipes when the working fluid inventory was varied. This report describes the measurement of the geometry of the heat pipe wick structure and the construction and testing of a heat pipe filling station. In addition, an extensive analysis of the uncertainty involved in the filling procedure and working fluid inventory has been outlined. Experimental measurements include the maximum heat transport, thermal resistance and evaporative heat transfer coefficient of the revolving helically grooved heat pipe for radial accelerations of |a⃗r|=0.0, 2.0, 4.0, 6.0, 8.0, and 10.0-g and working fluid fills of G=0.5, 1.0, and 1.5. An existing capillary limit model was updated and comparisons were made to the present experimental data.

Steady State Modeling of LHP and Analysis

2010 ◽  
Author(s):  
Yan Chen ◽  
Lin Cheng ◽  
Gongming Xin ◽  
Tao Luan
Keyword(s):  
Steady State ◽  
Ambient Temperature ◽  
Heat Pipe ◽  
Heat Sink ◽  
Heat Load ◽  
Operating Temperature ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Heat Sink Temperature ◽  
Transition Heat

The loop heat pipe (LHP) was invented in Russia in the early 1980’s. It is a two-phase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat, and the capillary force developed in fine porous wicks to circulate the fluid. The temperature of LHP evaporator as functions of the heat load, sink temperature, ambient temperature is an important parameter which can reflect the performance of an LHP. Many factors can affect the LHP operating temperature and which can be divided into two parts: external and internal. The external factors including heat sink temperature, ambient temperature, fluid forces, the position between heat source and heat sink and the heat exchange between LHP and ambient. The internal factors related to the design and structure of the LHP, for example, the charging amount of the working fluid and the distribution status of the liquid phase during the LHP operating. Based on Sinda/Fluint software an ammonia-stainless steel steady state model of loop heat pipe was established, the impacts on the LHP operating temperature induced by alterable heat loads under 3 operating cases (the different position between evaporator and condenser, the changing of ambient temperature and the changing of heat sink temperature) were analyzed and conclusions were made. Changing the position between evaporator and condenser has a significant influence on the LHP operating temperature. Anti-gravity operation will reduce the performance of the LHP, this phenomenon is obviously in low heat load range. Further more, increasing of fluid pressure drop in the loop will induce decreasing of the LHP performance. The temperature difference between ambient and heat sink will influence the transition heat load (from variable conductance mode to fixed conductance mode), the bigger the temperature difference the higher the transition heat load.

scholarly journals Thermal performance of Pulsating Heat Pipe on Electric Motor as Cooling Application

2018 ◽  
Vol 67 ◽  
pp. 03035 ◽  
Author(s):  
Nurhalimah Aprianingsih ◽  
Adi Winarta ◽  
Bambang Ariantara ◽  
Nandy Putra
Keyword(s):  
Heat Pipe ◽  
Thermal Management ◽  
Thermal Performance ◽  
Electric Motor ◽  
Management System ◽  
Operating Temperature ◽  
Heat Pipes ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Thermal Management System

Heat generated in an electric motor can increase the operating temperature. The excessive operating temperature will reduce the electric motor performance and shorten the service life. An appropriate thermal management system is required to reduce the electric motor operating temperature. The objective of this study is to determine the thermal performance of pulsating heat pipes which applied to the electric motor thermal management system. A prototype of electric motor thermal management system was made from an induction motor with a cartridge heater instead of a heat-generating rotor and stator. Six pieces of pulsating heat pipe were mounted using hexagonal heat pipe holder which placed inside the electric motor housing. The pulsating heat pipes are made of a copper capillary tube using acetone as working fluid with a filling ratio of 0.5. The electric power input was varied from 30 W to 150 W. The use of pulsating heat pipes can reduce the electric motor surface temperature by 55.3°C with the minimum thermal resistance of 0.151°C/W.

Heat Transport Limitation of a Triangular Micro Heat Pipe

2003 ◽  
Author(s):  
D. Sugumar ◽  
Kek Kiong Tio
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Operating Temperature ◽  
Working Fluid ◽  
Transport Capacity ◽  
Condenser Section ◽  
Micro Heat Pipe ◽  
Evaporator Section ◽  
Higher Temperature ◽  
Specific Temperature

A micro heat pipe will operate effectively by achieving its maximum possible heat transport capacity only if it is to operate at a specific temperature, i.e., design temperature. In reality, micro heat pipe’s may be required to operate at temperatures different from the design temperature. In this study, the heat transport capacity of an equilateral triangle micro heat pipe is investigated. The micro heat pipe is filled optimally with working fluid for a specific design temperature and operated at different operating temperatures. For this purpose, water, pentane and acetone was selected as the working fluids. From the numerical results obtained, it shows that the optimal charge level of the micro heat pipe is dependent on the operating temperature. Furthermore, the results also shows that if the micro heat pipe is to be operated at temperatures other than its design temperature, its heat transport capacity is limited by the occurrence of flooding at the condenser section or dryout at the evaporator section, depending on the operating temperature and type of working fluid. It is observed that when the micro heat pipe is operated at a higher temperature than its design temperature, the heat transport capacity increases but limited by the onset of dryout at the evaporator section. However, the heat transport capacity decreases if it is to be operated at lower temperatures than its design temperature due to the occurrence of flooding at condenser end. From the results obtained, we can conclude that the performance of a micro heat pipe is decreased if it is to be operated at temperatures other than its design temperature.

scholarly journals The effect of operating parameters on the heat transfer in the heat pipe

2021 ◽  
Vol 2119 (1) ◽  
pp. 012088
Author(s):  
A. A. Litvintceva ◽  
N. I. Volkov ◽  
N. I. Vorogushina ◽  
V. A. Moskovskikh ◽  
V. V. Cheverda
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Heat Pipes ◽  
Working Fluid ◽  
Operating Parameters ◽  
Temperature Stabilization ◽  
Ir Camera ◽  
Fluid Properties

Abstract Heat pipes are a good solution for temperature stabilization, for example, of microelectronics, because these kinds of systems are without any moving parts. Experimental research of the effect of operating parameters on the heat transfer in a cylindrical heat pipe has been conducted. The effect of the working fluid properties and the porous layer thickness on the heat flux and temperature difference in the heat pipe has been investigated. The temperature field of the heat pipe has been investigated using the IR-camera and K-type thermocouples. The data obtained by IR-camera and K-type thermocouples have been compared. It is demonstrated the power transferred from the evaporator to the condenser is a linear function of the temperature difference between them.

scholarly journals An investigation on effect of EDL on heat transfer of micro heat pipe with square and triangular cross section

2020 ◽  
Vol 21 (3) ◽  
pp. 309
Author(s):  
Maryam Fallah Abbasi ◽  
Hossein Shokouhmand ◽  
Morteza Khayat
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Double Layer ◽  
Electric Double Layer ◽  
Heat Pipes ◽  
The Body ◽  
Working Fluid ◽  
Two Phase ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Electronic industries have always been trying to improve the efficiency of electronic devices with small dimensions through thermal management of this equipment, thus increasing the use of small thermal sinks. In this study micro heat pipes with triangular and square cross sections have been manufactured and tested. One of the main objectives is to obtain an understanding of micro heat pipes and their role in energy transmission with electrical double layer (EDL). Micro heat pipes are highly efficient heat transfer devices, which use the continuous evaporation/condensation of a suitable working fluid for two-phase heat transport in a closed system. Since the latent heat of vaporization is very large, heat pipes transport heat at small temperature difference, with high rates. Because of variety of advantage features these devices have found a number of applications both in space and terrestrial technologies. The theory of operation micro heat pipes with EDL is described and the micro heat pipe has been studied. The temperature distribution have achieved through five thermocouples installed on the body. Water and different solution mixture of water and ethanol have used to investigate effect of the electric double layer heat transfer. It was noticed that the electric double layer of ionized fluid has caused reduction of heat transfer.

Metallic Mesh as Capillary Structure Applied in Heat Pipe Heat Exchanger for Heat Recovery

2014 ◽  
Vol 1082 ◽  
pp. 309-314 ◽  
Author(s):  
Diogo L.F. Santos ◽  
Larissa S. Marquardt ◽  
Paulo H.D. Santos ◽  
Thiago Antonini Alves
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Capillary Structure ◽  
Porous Wick ◽  
Metallic Mesh ◽  
Heat Loads ◽  
Pipe Heat

This work presents a theoretical and experimental analysis of a heat exchanger assisted by five heat pipes made of copper with a metallic mesh 100 of stainless steel which was used as capillary structure. All heat pipes used water as the working fluid and were designed based on the capillary limit model. The heat pipes were developed and tested under heat loads varying from 20 to 50 W before application into the heat exchanger. The theoretical and experimental results were compared and all heat pipes worked satisfactorily. Thereafter, it is presented the development of heat pipe heat exchanger which was tested under heat loads varying from 100 to 250 W. The highest temperature measured on the external surface of the heat pipes was 90 oC and the heat exchanger thermal efficiency varied from 74 to 80%. It is showed that the use of a stainless steel mesh as a porous wick was proved to work successfully in heat pipes.

Effect of Fluid Loading on the Performance of Wicked Heat Pipes

Volume 3 ◽  
2004 ◽  
Author(s):  
R. Kempers ◽  
A. Robinson ◽  
C. Ching ◽  
D. Ewing
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Heat Transport ◽  
Heat Pipes ◽  
Working Fluid ◽  
Fluid Loading ◽  
Maximum Heat ◽  
Horizontal Orientation ◽  
Maximum Heat Flux ◽  
Dry Out

A study was performed to experimentally characterize the effect of fluid loading on the heat transport performance of wicked heat pipes. In particular, experiments were performed to characterize the performance of heat pipes with insufficient fluid to saturate the wick and excess fluid for a variety of orientations. It was found that excess working fluid in the heat pipe increased the thermal resistance of the heat pipe, but increased maximum heat flux through the pipe in a horizontal orientation. The thermal performance of the heat pipe was reduced when the amount of working fluid was less than required to saturate the wick, but the maximum heat flux through the heat pipe was significantly reduced at all orientations. It was also found in this case the performance of this heat pipe deteriorated once dry-out occurred.

Production Stainless Gravitational Heat Pipes Filled with Distilled Water

2016 ◽  
Vol 832 ◽  
pp. 184-191 ◽  
Author(s):  
Marián Jobb ◽  
Ľuboš Kosa ◽  
Michal Holubčík ◽  
Radovan Nosek
Keyword(s):  
Heat Pipe ◽  
Operating Temperature ◽  
Heat Pipes ◽  
Distilled Water ◽  
Aisi 304 ◽  
Working Temperature ◽  
Essential Function ◽  
Aisi 316 ◽  
Process Measurements ◽  
Pipe Manufacturing

This article deals with the performance of heat pipes, depending on the operating temperature and positions (operation angle). There is described the essential function of the heat pipe manufacturing process. Measurements were carried at an operating temperature of 40 °C to 90 °C. Stainless heat pipes were made of three kinds of materials AISI 304, AISI 310, AISI 316 and filled with a distilled water, up to 20% of the heat pipe inner volume. For each material was selected heat pipe with the best results. The heat pipes were measured at various angles of vertical inclination (0 ° - 90 °), at the working temperature 90 ° C. The performance was measured on the experimental device. Presented results show the progress of individual measurements and the effect of operating parameters on the performance of heat pipes.

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