Investigation of a Gas-Pump-Driven Loop Heat Pipe

Abstract

A loop heat pipe (LHP) is an efficient method of conserving energy in data center cooling applications. In scenarios where the installation is constrained by height or distance limitations, pump driving is needed. This paper examines the performance changes induced by a gas pump both experimentally and theoretically. An adjustable, oil-free linear compressor is utilized as a gas pump. The evaporator is a finned-tube heat exchanger and the condenser is a water-cooled plate heat exchanger. When the filling ratio of the working fluid is insufficient, employing a gas pump can enhance the heat transfer performance. However, when the filling ratio of the working fluid is sufficient, while the gas pump can increase the flowrate of the working fluid, the heat transfer rate (HTR) does not change significantly. In fact, it may reduce the energy efficiency ratio of the heat pipe. Infrared thermography has proven to be an efficient tool for estimating the area ratio of different zones within the evaporator, which is crucial for the output regulation of the compressor. The area ratio of the two-phase zone is nearly linear to the HTR. Through the establishment of a physical model of a gas-pump-driven loop heat pipe (GPLHP), the impacts of the LHP size and gas pump operation on the heat transfer performance are analyzed. It is found that the gas pump can extend the application range of the LHP, although it has a minimal impact on the maximum HTR. How to select a gas pump for an LHP is discussed.

Keywords

• loop heat pipe
• gas pump
• experiment
• modelling
• infrared thermography