Influence of Working Fluid Thermophysical Property on Thermal Performance of Flat-Plate Closed Loop Pulsating Heat Pipe

2011 ◽  
Vol 130-134 ◽  
pp. 1799-1804 ◽  
Author(s):  
Qing Ping Wu ◽  
Rui Xiang Wang ◽  
Ya Jun Li ◽  
Rong Ji Xu ◽  
Yan Zhong Li
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Latent Heat ◽  
Thermal Performance ◽  
Thermophysical Properties ◽  
Closed Loop ◽  
Heat Pipes ◽  
Working Fluid ◽  
Heat Of Vaporization ◽  
Latent Heat Of Vaporization

Pulsating heat pipes are high efficiency heat transfer components having a great potential application in the field of electronic cooling and space applications. In this investigation, an experiment was conducted to study the influence of working fluid thermophysical properties on the thermal performance of flat-plate closed loop pulsating heat pipes (FCLPHP). The analysis of the forces acting on the liquid-vapor mixture shows that the surface tension, viscosity and latent heat of vaporization have important impact on the thermal performance of FCLPHP. The overall thermal resistance decreases with the decrease in surface tension, viscosity and latent heat of vaporization, leading to the heat transfer improvement of FCLPHP. An experimental correlation was developed to describe the relationship among the relative overall thermal resistance and the relative thermophysical properties. With the correlation, a sensitivity analysis was made. The results show that latent heat of vaporization is the prior factor to the all others to impact the thermal performance of FCLPHP.

Thermophysical Properties of Al2O3-Water Nanofluids

2011 ◽  
Vol 688 ◽  
pp. 266-271 ◽  
Author(s):  
Bao Jie Zhu ◽  
Wei Lin Zhao ◽  
Jin Kai Li ◽  
Yan Xiang Guan ◽  
Dong Dong Li
Keyword(s):  
Thermal Conductivity ◽  
Surface Tension ◽  
Vapor Pressure ◽  
Latent Heat ◽  
Thermophysical Properties ◽  
Volume Concentration ◽  
Saturation Vapor Pressure ◽  
Heat Of Vaporization ◽  
Latent Heat Of Vaporization ◽  
Saturation Vapor

Aqueous nanofluids composed of alumina nanoparticles with different sizes at a concentration from 0.1vol% to 0.5vol% were prepared by a two-step method. The suspension and dispersion characteristics were experimentally examined by zeta potential, average size and absorption spectrum. The thermophysical properties such as the viscosity, surface tension, thermal conductivity, saturation vapor pressure and latent heat of vaporization were measured. The influences of the particle size, particle volume concentration and temperature on the thermophysical property were investigated. It was found that the viscosity and thermal conductivity increased with decreasing nanoparticle size. In contrast, the surface tension, saturation vapor pressure and latent heat of vaporization decrease with decreasing nanoparticle size. The viscosity, thermal conductivity and saturation vapor pressure have an increasing tendency with increasing volume concentration. However, surface tension and latent heat of vaporization showed a reverse tendency. Furthermore, the temperature also showed had obvious influence on the nanofluids viscosity, thermal conductivity and surface tension.

scholarly journals Experimental investigation of higher carbon alcohols with low latent heat of vaporization as self rewetting fluids in closed loop pulsating heat pipes

2020 ◽  
pp. 347-347
Author(s):  
Sriram Chidambaranathan ◽  
Swaminathan Rangaswamy
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Heat Recovery ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Transfer Performance ◽  
Electronic Components ◽  
High Carbon ◽  
Heat Of Vaporization ◽  
Latent Heat Of Vaporization

Heat recovery plays an important role in all energy systems. The dissipation of heat is drastically increasing due to the advancement of electronic components. To cool the electronic components many heat recovery devices are introduced and out of which heat pipes play an important role. Pulsating Heat Pipe (PHP) is a new type of heat transfer device which was introduced by Akachi in mid-1990. It is used mainly in the cooling of electronic components because of its potential for removing high heat flux. An experimental study was made to investigate the heat transfer performance of PHP using self-rewetting fluids of high carbon alcohols. The latent heat of vaporization plays an important role in the heat transfer performance of PHP. It was observed that the high carbon alcohols showed a decrease in the latent heat of vaporization. The high carbon alcohols such as 1-Butanol, 1-Pentanol, 1-Hexanol, 1-Heptanol, and 1-Octanol were mixed with the deionized water to form a self-rewetting fluid. These self-rewetting fluids showed a unique behavior due to the inverse Marangoni effect. It was observed that the lower thermal resistance and higher heat transfer coefficient was obtained, especially in the dilute aqueous solution of 1- Octanol.

Effects of Surface Coating of Nanoparticles on Thermal Performance of Open Loop Pulsating Heat Pipes

2012 ◽  
Author(s):  
Mehdi Taslimifar ◽  
Maziar Mohammadi ◽  
Ali Adibnia ◽  
Hossein Afshin ◽  
Mohammad Hassan Saidi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Surface Coating ◽  
Heat Pipes ◽  
Open Loop ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Performance Of Heat Transfer

Homogenous dispersing of nanoparticles in a base fluid is an excellent way to increase the thermal performance of heat transfer devices especially Heat Pipes (HPs). As a wickless, cheap and efficient heat pipe, Pulsating Heat Pipes (PHPs) are important candidates for thermal application considerations. In the present research an Open Loop Pulsating Heat Pipe (OLPHP) is fabricated and tested experimentally. The effects of working fluid namely, water, Silica Coated ferrofluid (SC ferrofluid), and ferrofluid without surface coating of nanoparticles (ferrofluid), charging ratio, heat input, and application of magnetic field on the overall thermal performance of the OLPHPs are investigated. Experimental results show that ferrofluid has better heat transport capability relative to SC ferrofluid. Furthermore, application of magnetic field improves the heat transfer performance of OLPHPs charged with both ferrofluids.

A Comprehensive Experimental Investigation of the Performance of Closed-Loop Pulsating Heat Pipes

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
M. Halimi ◽  
A. Abbas Nejad ◽  
M. Norouzi
Keyword(s):  
Thermal Resistance ◽  
Flow Regime ◽  
Thermal Performance ◽  
Closed Loop ◽  
Heat Pipes ◽  
Filling Ratio ◽  
Working Fluid ◽  
Physical Parameters ◽  
Two Phase ◽  
Laboratory Conditions

Closed-loop pulsating heat pipes (CLPHPs) are a new type of two-phase heat transfer devices that can transfer considerable heat in a small space via two-phase vapor and liquid pulsating flow and work with various types of two-phase instabilities so the operating mechanism of CLPHP is not well understood. In this work, two CLPHPs, made of Pyrex, were manufactured to observe and investigate the flow regime that occurs during the operation of CLPHP and thermal performance of the device under different laboratory conditions. In general, various working fluids were used in filling ratios of 40%, 50%, and 60% in horizontal and vertical modes to investigate the effect of thermo-physical parameters, filling ratio, nanoparticles, gravity, CLPHP structure, and input heat flux on the thermal performance of CLPHP. The results indicate that three types of flow regime may be observed given laboratory conditions. Each flow regime exerts a different effect on the thermal performance of the device. There is an optimal filling ratio for each working fluid. The increased number of turns in CLPHP generally improves the thermal performance of the system reducing the effect of the type of the working fluid on the aforementioned performance. The adoption of copper nanoparticles, which positively affect fluid motion, decreases the thermal resistance of the system as much as 6.06–42.76% depending on laboratory conditions. Moreover, gravity brings about positive changes in the flow regime decreasing thermal resistance as much as 32.13–52.58%.

Circulation Effectiveness of Working Fluid in Inclined Micro Heat Pipes

2015 ◽  
Vol 789-790 ◽  
pp. 422-425
Author(s):  
Fun Liang Chang ◽  
Yew Mun Hung
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Operating Conditions ◽  
Circulation Rate ◽  
Working Fluid ◽  
High Heat Flux ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Micro heat pipe is a two-phase heat transfer device offering effective high heat-flux removal in electronics cooling. Essentially, micro heat pipe relies on the phase change processes, namely evaporation and condensation, and the circulation of working fluid to function as heat transfer equipment. The vast applications of micro heat pipe in portable appliances necessitate its functionality under different orientations with respect to gravity. Therefore, its thermal performance is strongly related to its orientation. By incorporating solid wall conduction, together with the continuity, momentum, and energy equations of the working fluid, a mathematical model is developed to investigate the heat and fluid flow characteristics of inclined micro heat pipes. We investigate both the favorable and adverse effects of gravity on the circulation rate which is intimately related to the thermal performance of micro heat pipes. The effects of gravity, through the angle of inclination, on the circulation strength and heat transport capacity are analysed. This study serves as a useful analytical tool in the micro heat pipe design and performance analysis, associated with different inclinations and operating conditions.

Experimental Investigation Into the Heat Transfer Mechanism of Oscillating Heat Pipes Using Temperature Sensitive Paint

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Matthew Francom ◽  
Jungho Kim
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Fluid Motion ◽  
Heat Pipes ◽  
Transfer Mechanism ◽  
Working Fluid ◽  
Temperature Sensitive ◽  
Heat Transfer Mechanism ◽  
Experimental Apparatus ◽  
Temperature Sensitive Paint

Abstract Oscillating heat pipes (OHPs) represent a promising passive mechanism for the removal or spreading of heat. While simple to construct, the fluid and thermodynamics of these devices are still poorly understood. There is debate over whether the primary heat transfer mechanism is due to sensible heating of the liquid phase or due to latent heat transfer through phase change. To answer this question, an experimental apparatus was constructed to provide time- and space-resolved temperature and heat transfer data across the face of an operating OHP with HFE-7000 as the working fluid. This experiment utilized temperature sensitive paint (TSP) alongside visual recording of the fluid motion in order to determine the relative latent and sensible contribution to the overall heat transfer. The OHP was tested with input powers ranging from 2.6 W to 10.1 W. It found that latent heat transfer was the dominant heat transfer mechanism, accounting for between 65% and 83% of the total heat transferred in all cases.

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