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.

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 Thermal analysis of heat pipe using self rewetting fluids

2011 ◽  
Vol 15 (3) ◽  
pp. 879-888 ◽  
Author(s):  
Rathinasamy Senthilkumar ◽  
Subaiah Vaidyanathan ◽  
Sivaramanb Balasubramanian
Keyword(s):  
Surface Tension ◽  
Heat Pipe ◽  
Heat Transport ◽  
Pure Water ◽  
Heat Pipes ◽  
The Self ◽  
Working Fluid ◽  
Surface Tension Gradient ◽  
Condenser Section ◽  
Maximum Heat

This paper discuses the use of self rewetting fluids in the heat pipe. In conventional heat pipes, the working fluid used has a negative surface-tension gradient with temperature. It is an unfavourable one and it decreases the heat transport between the evaporator section and the condenser section. Self rewetting fluids are dilute aqueous alcoholic solutions which have the number of carbon atoms more than four. Unlike other common liquids, self-rewetting fluids have the property that the surface tension increases with temperature up to a certain limit. The experiments are conducted to improve the heat-transport capability and thermal efficiency of capillary assisted heat pipes with the self rewetting fluids like aqueous solutions of n-Butanol and n-Pentanol and its performance is compared with that of pure water. The n-Butanol and n-Pentanol are added to the pure water at a concentration of 0.001moles/lit to prepare the self rewetting fluids. The heat pipes are made up of copper container with a two-layered stainless steel wick consisting of mesh wrapped screen. The experimental results show that the maximum heat transport of the heat pipe is enhanced and the thermal resistances are considerably decreased than the traditional heat pipes filled with water. The fluids used exhibit an anomalous increase in the surface tension with increasing temperature.

An Investigation of Flat-Plate Oscillating Heat Pipes

2010 ◽  
Author(s):  
Peng Cheng ◽  
Scott Thompson ◽  
Joe Boswell ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Transfer Performance ◽  
Operating Temperature ◽  
Pure Water ◽  
Heat Pipes ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Performance

The heat transfer performance of flat-plate oscillating heat pipes (FP-OHPs) was investigated experimentally and theoretically. Two layers of channels were created by machining grooves on both sides of copper plate, in order to increase the channel number per unit volume. The channels had rectangular cross-sections with hydraulic diameters ranging from 0.762 mm to 1.389 mm. Acetone, water and diamond/acetone, gold/water and diamond/water nanofluids were tested as working fluids. It was found that the FP-OHP’s thermal resistance depended on the power input and operating temperature. The FP-OHP charged with pure water achieved a thermal resistance of 0.078°C/W while removing 560 W with a heat flux of 86.8 W/cm2. The thermal resistance was further decreased when nanofluid was used as the working fluid. A mathematical model predicting the heat transfer performance was developed to predict the effects of channel dimension, heating mode, working fluid and operating temperature on the thermal performance of the FP-OHP. Results presented here will assist in optimization of the FP-OHP and provide a better understanding of heat transfer mechanisms occurring in an OHPs.

Utilization of Advanced Working Fluids With Biporous Evaporators

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Sean W. Reilly ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Operating Temperature ◽  
Temperature Drop ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Inorganic Aqueous Solution ◽  
Operating Temperature Range

A novel fluid for use as a working fluid in a heat pipe has been tested at UCLA. The fluid was discovered originally in use with a device consisting of a metal tube charged with the patented inorganic aqueous solution (IAS), which is evaporated when the tube is evacuated before use. According to the patent, this evaporation leaves a thin film that allows the tube to carry high heat flux loads with low temperature drop across the tube in a solid state mode. However, various experiments with these tubes have produced inconsistent results, and there are some questions as to whether the fluid is completely evaporated. The research on which this work is based is focused on testing whether the charging fluid will operate as the working fluid in a heat pipe, in order to determine the nature of the IAS fluid. A heat pipe apparatus was charged with a biporous wick in order to investigate if the fluid plays a role in heat transfer. There are extensive data for this experiment using water as the working fluid, which will be used to compare the two sets of results. Testing has shown a reduction of the superheat required to drive heat fluxes through a wick compared to water by approximately 40%. Some experiments have shown that the operating (temperature) range of the IAS is much larger than a standard heat pipe. It is theorized that the increase in performance of the IAS is due to an increased thermal conductivity of the wick and increased capillarity. If this fluid is proven to be effective, it would lead to more effective and tunable heat transfer devices.

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.

The Effect of CuO-Water Nanofluid and Biomaterial Wick on Loop Heat Pipe Performance

2014 ◽  
Vol 875-877 ◽  
pp. 356-361 ◽  
Author(s):  
Nandy Putra ◽  
Wayan Nata Septiadi ◽  
Rosari Saleh ◽  
Rardi Artono Koestoer ◽  
Suhendro Purbo Prakoso
Keyword(s):  
Heat Pipe ◽  
Pure Water ◽  
Sol Gel ◽  
Heat Pipes ◽  
Cuo Nanoparticles ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Gel Method ◽  
Loop Heat Pipes ◽  
Copper Pipe

The determinants of heat pipe performances are its wick and working fluid, instead of controlled by the material, dimension, and the shape of heat pipe. This study aimed to determine the effect of using nanofluid on the performance of Loop heat pipes (LHP) with CuO-water nanofluid that using biomaterials wick. LHP was made of 8 mm diameter copper pipe, with the diameter of evaporator and the condenser was 20 mm respectively and the length of the heat pipe was 100 mm. The wick was made of biomaterials Collaria Tabulate and the working fluid was CuO-water nanofluids where the CuO nanoparticles were synthesized by sol-gel method. The characteristic of the Tabulate Collaria biomaterial as a wick in LHP was also investigated in this experiment. The results of the experiments showed that the temperature differences between the evaporator and condenser sections with the biomaterial wick and CuO-water nanofluid were less than those using pure water. These results make the biomaterial (Collar) and nanofluids are attractive both as wick and working fluid in LHP technology. Keywords: loop heat pipe, wick, biomaterial, nanofluid.

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.

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