The study on the difference of the start-up and heat-transfer performance of the pulsating heat pipe with water−acetone mixtures

Author(s):  
Yue Zhu ◽  
Xiaoyu Cui ◽  
Hua Han ◽  
Shende Sun
Author(s):  
Fu-Min Shang ◽  
Shi-Long Fan ◽  
Jian-Hong Liu

Abstract The pulsating heat pipe (PHP) is a passive cooling device, which has the advantages of simple structure, high heat transfer performance and low production cost. The complex vapor-liquid phase change occurs in the in the initial stage of PHP. In this work, we explore the start-up performance of PHP at different inclination angles and the experiment shows that start-up performance is respectively different when the angles are 0°, 45°, 90°, 135° and 180°. Since the gravitational auxiliary function, the working fluid in the communicating pipe which takes longer time to vaporize change phase earlier than that in PHP’s loop when the angles are 0° and 45°. Nevertheless, when the angle is 90°, the phase change of working fluid in communicating pipe and in the loop occurs at the same time. Meanwhile, the oscillating mode affects the stability of the starting and heat transfer performance of the PHP.


2021 ◽  
Vol 248 ◽  
pp. 01004
Author(s):  
Chongju Hu ◽  
Xiuxiang Zhang ◽  
Hongyan Wang ◽  
Bo Wu ◽  
Pinghua Zhang

Heat pipe may be affected by the high temperature heat source during operation, resulting in unsteady oscillation heating. In this paper, the influence of alternating power and period on the start-up and heat transfer performance of mercury heat pipe is studied by using the method of equivalent thermal resistance of heat pipe. The results are as follows:1) The start-up time of alternating power heating and steady-state power heating is basically equal; 2) For the alternating power heating, the steady-state temperature of heat pipe changes periodically, increasing the alternating period or the amplitude of alternating power will lead to the increase of the fluctuation amplitude of heat pipe temperature, and the influence of alternating period is greater than that of changing the amplitude of alternating power. 3) Under the condition of alternating power heating, the steady-state thermal resistance of heat pipe changes periodically. The fluctuation amplitude of steady-state thermal resistance of heat pipe increases with the increase of alternating period and alternating power amplitude, and the influence of alternating power amplitude is greater than that of alternating period.


Author(s):  
Guowei Xiahou ◽  
Hao Liu ◽  
Shun Zhang ◽  
Yecong He

Abstract A new type of array pulsating cold section heat pipe was proposed, which consists of a T-shaped hot section and an array pulsating cold section. The special structure is available to drain the hot section of the heat pipe, and the installation method of the cold section has an important influence on heat transfer. For this reason, a detailed experimental study of heat transfer performance was carried out in this paper. It was found in the study that a capillary lifting force exists at the outlet of the cold section channel, which prevents the condensate from returning to the hot section, therefore, the hot section has to be drained; the drainage methods are divided into hot-section liquid drainage and hot-section capillary drainage, the latter is significantly better than the former; appropriate increase of the filling rate can improve the drainage effect of liquid drainage. The new heat pipe can adopt two methods, i.e., inclined cold section and vertical cold section. The reflux and heat transfer performance of the inclined cold section outperforms that of the vertical cold section, but the difference between the two methods gradually decreases with the increase of power. Under the same working conditions, the average temperature of the heat source of the new stainless steel heat pipe with the capillary drainage vertical cold section is lower than that of the aluminum fin radiator by 5.79%-10.78%, and the decreasing amplitude increases with the increase of the heating power.


2020 ◽  
Vol 194 ◽  
pp. 01014
Author(s):  
Qingping Wu ◽  
Rongji Xu ◽  
Ruixiang Wang ◽  
Yanzhong Li

Flat-plat pulsating heat pipes (FCLPHPs) have a great potentiality in electronic cooling field and space application. In this investigation, three FCLPHPs (L1, L2, and L3) were built to study the influence of cross section shapes on the heat transfer performance of FCLPHP. One (L1) of them has asymmetric pipe, the others (L2, L3) have symmetric pipes. The results indicate that the FCLPHP L1 has the best heat transfer performance. Compared with the FCLPHPs L2 and L3, the start-up time reduces by 64% and the thermal resistance reduces by at most half respectively.


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