An experimental evaluation of the performance of a remote 2U loop thermosyphon

Abstract

In recent years, the increasing application and diversity of electronic systems have resulted in a significant demand for research and development in electronic cooling. Designing and evaluating thermal modules is crucial, especially for systems generating high heat flux levels. This study proposes a novel remote loop thermosyphons (RLTS) for high heat flux applications and cooling 2U servers, which has been assessed experimentally. Additionally, several critical factors are examined, including the filling ratio (FR), air flow rate, and heat load. The experimental study evaluated air flow rates range from 130 to 170 cubic feet per minute (CFM), and the filling ratios span from 40 % to 70 %. The heat load varied from 100 W to 700 W. Compared to the conventional loop thermosyphon, the remote loop thermosyphon exhibited superior performance and sustained higher heat flux. Specifically, this thermal module can effectively manage 640 W at an inlet air temperature of 28 °C with an airflow rate of 170 CFM. Moreover, compared to other available loop thermosyphons, the proposed thermal module demonstrated enhanced heat flux up to 94 W/cm2. These results suggest that the new remote loop thermosyphon is a promising solution for cooling high heat flux applications, such as 2U servers. Furthermore, among all the investigated FR effects the 50 % FR performed better than the other filling ratios. At this filling ratio, the thermal resistance reached a minimum value of 0.078 K/W. The findings indicated that increasing the heat load decreased thermal resistance to a certain threshold, beyond which thermal resistance started to increase. This increase in thermal resistance was caused by restricted space above the evaporator. The confined space effect in a loop thermosyphon system significantly influences the performance and should be considered as a crucial factor in future design endeavors.