Heat transfer characteristic of an ultra-thin flat plate heat pipe with surface-functional wicks for cooling electronics

2019 ◽  
Vol 100 ◽  
pp. 12-19 ◽  
Author(s):  
Gong Chen ◽  
Yong Tang ◽  
Zhenping Wan ◽  
Guisheng Zhong ◽  
Heng Tang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Pipe ◽  
Heat Transfer Characteristic ◽  
Transfer Characteristic ◽  
Plate Heat ◽  
Flat Plate Heat Pipe

A211 Visualization experiment about effect of wettability on heat transfer of flat-plate heat pipe

2014 ◽  
Vol 2014 (0) ◽  
pp. _A211-1_-_A211-2_
Author(s):  
Masaru Ogasawara ◽  
Shota Yanagisawa ◽  
Takahiro Ito ◽  
Yoshiyuki Tsuji ◽  
Seiji Yamashita ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Pipe ◽  
Plate Heat ◽  
Visualization Experiment ◽  
Flat Plate Heat Pipe

A visualization study on flat plate heat pipe (FPHP)

2021 ◽  
pp. 095765092199022
Author(s):  
Wan Yu ◽  
Dan Gao ◽  
Gang Wang ◽  
Tao Hu ◽  
Qichao Gong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Flat Plate ◽  
Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Plate Heat ◽  
Transfer Characteristics ◽  
Flat Plate Heat Pipe ◽  
Vapor Liquid

With the aim to analyze the flow pattern and heat transfer characteristics of the working fluid in a flat plate heat pipe (FPHP) which was sealed by a transparent tempered glass plate, ethanol, acetone, and R141b were taken as the working medium, and visual experiments were performed at different heat flux when the inclination angle was 90°. The vapor-liquid distribution and the heat transfer characteristics of the FPHP were investigated at different liquid filling ratios. According to the experimental results and the recording of high-speed cameras, some important conclusions had been drawn as follows: (i) As the power increases, the vapor-liquid interface in the FPHP declines and the effects of dryout is significantly intnsified, leading to a sharp increase in temperature. The FPHP with a filling ratios of 25.7% owns better thermal performance than that with the filling ratios of 11.8% and 66% at different heating power; (ii) the bubble generation inside the FPHP became more intense with increasing heat flux, and various bubble movement patterns were found at different the liquid filling ratios; (iii) As the liquid film flowed downward, the thickness of the liquid film increased at first and then decreases. The condensation of steam was reduced due to the thickening of the liquid film on the wall. The liquid film became thinner when it was entrapped and evaporated in the downward flow.

An Experimental Investigation of the Transient Characteristics on a Flat-Plate Heat Pipe During Startup and Shutdown Operations

2000 ◽  
Vol 122 (3) ◽  
pp. 525-535 ◽  
Author(s):  
Y. Wang ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Heat Pipe ◽  
Temperature Rise ◽  
Input Power ◽  
Maximum Temperature ◽  
Plate Heat ◽  
Flat Plate Heat Pipe

This work presents an experimental investigation of the thermal performance of a flat-plate heat pipe during startup and shutdown operations. Using the analytical model developed in a previously study, analytical and experimental results on the effect of input power and cooling heat transfer coefficient on the thermal performance of the heat pipe are presented and discussed. The results indicate that the wick in the evaporator section provides the largest resistance to the heat transfer process followed by the wick in the condenser section. It is found that the heat transfer coefficient has an insignificant effect on the maximum temperature difference across the heat pipe where this difference refers to the maximum difference on the outside surfaces of the flat-plate heat pipe. However, as expected, the input heat flux has a substantial effect on the temperature rise where the temperature rise refers to the temperature increase on the outside surface of the heat pipe. It is found that the temperature difference across the heat pipe depends mainly on the input power. The heat transfer coefficient strongly affects the time it takes to reach steady state while input power has a substantially smaller effect. Empirical correlations for the maximum temperature rise, the maximum temperature difference and the time constants are obtained. The experimental results are compared with the analytical results and are found to be in very good agreement. [S0022-1481(00)01803-X]

Thermal Performance of a Flat Plate Heat Pipe With Gradient Wettability

2013 ◽  
Author(s):  
Ping-Hei Chen ◽  
Hung-Hsia Chen ◽  
Bo-Rui Huang ◽  
Long-Sheng Kuo
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Contact Angles ◽  
Plate Heat ◽  
Flat Plate Heat Pipe ◽  
Superhydrophilic Surface ◽  
Gradient Surface

Many studies have been performed on the flat-plate heat pipes with sintered wick. It was found that during the evaporation process, the heat transfer characteristics of hydrophilic surface performed better than hydrophobic surface. This work investigated the heat transfer characteristics of flat-plate heat pipes in which the bottom surface was modified with various gradient contact angles by a sol-gel method. This method was applied to create a gradient surface on copper-plate surface. The coated nanoparticles were immobilized on the surface after the surface was heated in a furnace at a working temperature of 120°C. The thermal resistance results of flat plate heat pipes with either homogeneous superhydrophilic surface or a gradient wettability are reported in this study. For the gradient wettability, the evaporation region was super-hydrophilic and the condense region was super-hydrophobic. The heat transfer ability was both increased in evaporation region and condense region. Furthermore, the reflux ability of the working fluid was performed better due to the unbalanced surface tension on the gradient surface and the impact of gravity force of inclination angle (α). By manipulating different surfaces with different contact angles (gradient surface, contact angle = 150 ° /110 ° /20 ° /10 ° and uniform surface, contact angle <10°) and different inclination angles (α = 0°, 10°), we managed to find the better combination to improve the thermal performance of flat-plate heat pipe. The results indicated that the thermal performance of flat plate heat pipe with a gradient wettability is better than homogeneous superhydrophilic surface. The evaporation resistance of gradient wettability surface (gradient & α = 10°) has achieved to 0.098 °C /W, and reduced 30% than homogenous superhydrophilic surface (CA <10° & α = 0°). The gradient wettability surface in this work performed as well as the traditional sintered wick flat-plate heat pipe.

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