Experimental Study on the Impact of Lubricant on the Performance of Gravity-Assisted Separated Heat Pipe

Yiming Rongyang, Weitao Su, Zujun Mao, Wenlin Huang, Bowen Du and Shaozhi Zhang ()
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Yiming Rongyang: Power China Huadong Engineering Corporation Limited, Hangzhou 318050, China
Weitao Su: Power China Huadong Engineering Corporation Limited, Hangzhou 318050, China
Zujun Mao: Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China
Wenlin Huang: Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China
Bowen Du: Power China Huadong Engineering Corporation Limited, Hangzhou 318050, China
Shaozhi Zhang: Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China

Energies, 2024, vol. 17, issue 15, 1-12

Abstract: Gravity-assisted separation heat pipes (GSHPs) are extensively utilized in telecommunications base stations and data centers. To ensure year-round cooling, integrating GSHPs directly with a vapor compression refrigeration system is a viable solution. It is unavoidable that the refrigeration system’s lubricant will infiltrate the heat pipe loop, thereby affecting its thermal performance. This paper examines the performance of a GSHP, which features a water-cooled plate heat exchanger as the condenser and a finned-tube heat exchanger as the evaporator, when the working fluid (R134a) is contaminated with a lubricant (POE, Emkarate RL-46H). The findings are compared with those from a system free of lubricant. The experimental outcomes indicate that the presence of lubricant degrades the heat transfer efficiency, particularly when the filling ratio is adequate and no significant superheat is observed at the evaporator’s outlet. This results in a 3.86% increase in heat transfer resistance. When the charge of the working fluid is suboptimal, the average heat transfer resistance remains relatively constant at a 3% lubricant concentration yet increases to approximately 5.27% at a 4–6% lubricant concentration, and further to 12.32% at a 9% lubricant concentration. Concurrently, as the lubricant concentration fluctuates between 3% and 9%, the oil circulation ratio (OCR) varies from 0.02% to 0.11%.

Keywords: gravity-assisted separated heat pipe; lubricant; heat transfer performance; coupled system (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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