TY  - EJOU
AU  - Zhao, Zeyuan 
AU  - Zhang, Dong 
AU  - Li, Haixia 
AU  - Deng, Qingdong 
AU  - Ding, Yong 
AU  - Li, Zehao 
AU  - An, Zhoujian 

TI  - Effect of Vapor Pressure Difference on the Operating Characteristics of Pulsating Heat Pipe Using Non-Azeotropic Water/HFE-7100 Mixture
T2  - Energy Engineering

PY  - 
VL  - 
IS  - 
SN  - 1546-0118

AB  - Pulsating heat pipes (PHPs), as highly efficient heat transfer devices, have been widely employed in thermal management systems in recent years. However, their unique structural characteristics often lead to stagnation, intermittent oscillation, and dry-out, particularly at low inclination angles. In this study, a three-dimensional closed-loop PHP charged with a non-azeotropic mixture of water and HFE-7100 was designed with the aim of broadening the operational range of PHPs. Comparative experiments were conducted between the non-azeotropic mixture PHP and single-fluid PHP charged with either water or HFE-7100 under identical operating conditions, in order to evaluate the enhancement of heat transfer performance. The enhancement mechanism of the non-azeotropic working fluid was analyzed in detail from the perspective of its thermophysical properties. The experimental results demonstrate that, under low inclination angles, the water charged PHP is more susceptible to dry-out. The thermal resistance of the HFE-7100 PHP is consistently higher than that of the mixture PHP. The non-azeotropic mixture effectively extends the stable operating range of the PHP. However, due to the significant difference in the saturated vapor pressures of the two working fluids, the water-charged PHP exhibits superior heat transfer performance at 50% filling ratio under inclination angles of 70° and 90°. Therefore, this study comprehensively analyzes the operating characteristics of the HFE-7100/water mixture PHP based on thermophysical properties in conjunction with temperature and pressure data. Finally, recommendations are provided for the selection of non-azeotropic immiscible working fluids.
KW  - Non-azeotropic working fluids; three-dimensional structure; heat transfer limit; saturated vapor pressure; thermal performance; pulsating heat pipe

DO  - 10.32604/ee.2026.078035