Heat transfer performance of pulsating heat pipe with zeotropic immiscible binary mixtures

•Zeotropic immiscible binary mixtures were used as working fluids.•Emulsion was produced during the oscillation.•Zeotropic immiscible binary mixtures could widen the range of working temperature of pulsating heat pipe.•The lowest thermal resistance of the pulsating heat pipe is 0.1634 °C/W.•Pulsatin...

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Bibliographic Details
Published in:International journal of heat and mass transfer 2019-07, Vol.137, p.31-41
Main Authors: Xu, Rongji, Zhang, Chao, Chen, Hao, Wu, Qingping, Wang, Ruixiang
Format: Article
Language:English
Subjects:
Binary mixtures
Boiling points
Deionization
Flow pattern
Fluids
Heat flux
Heat pipes
Heat transfer
Heating
Immiscible binary mixtures
Inclination angle
Miscibility
Mixing ratio
Pulsating heat pipe
Thermal resistance
Vapor pressure
Working fluids
Zeotropic
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Summary:•Zeotropic immiscible binary mixtures were used as working fluids.•Emulsion was produced during the oscillation.•Zeotropic immiscible binary mixtures could widen the range of working temperature of pulsating heat pipe.•The lowest thermal resistance of the pulsating heat pipe is 0.1634 °C/W.•Pulsating heat pipe with binary mixtures can achieve a stable one-way pulsation cycle. Working fluid is an important influencing factor for the heat transfer performance of a pulsating heat pipe (PHP). In this study, zeotropic immiscible working fluid was proposed based on the difficult start and easy dry-out with large heat flux of PHP. Deionized water mixed with HFE-7100 was used as the working fluid. The volume mixing ratios used were 4:1, 2:1, 1:1, 1:2, and 1:4, and the heating power ranged from 20 W to 250 W with inclination angles of 30°, 45°, 60°, 75°, and 90°. The filling ratio was 50%. Result shows that at a high heating power (210 W, 250 W), the PHP with mixtures could quickly start and achieve a stable one-way pulsation cycle with low thermal resistance. Meanwhile, the dry-out phenomenon of the working fluid with high boiling point had been inhibited because of the working fluid with low boiling point and high saturation vapor pressure, thereby raising the heat transfer limit of the PHP. During operation, the two working fluids were pulped and stirred to form an emulsion, which promoted the heat transfer between them. When the mixing ratio was 1:1, the two working fluids could be uniformly mixed, the contact surface between them was large, and the heat transfer property performed well. The lowest thermal resistance achieved with mixing ratio of 1:2 was 0.1634 °C/W due to some of the HFE-7100 would exist in gaseous form when the heating power was high (250 W, with an inclination angle of 90°).
ISSN:0017-9310
1879-2189
DOI:10.1016/j.ijheatmasstransfer.2019.03.070