Experimental study on heat transfer performance of micro-grooved I-shaped aluminum heat pipe for heat pipe heat exchangers

As fin-and-tube heat exchangers move towards miniaturization and lightweight development, achieving efficient heat transfer within mini-channels presents severe challenges. In this study, a novel micro-grooved I-shaped aluminum heat pipe (IAHP) embedded in mini-channels was fabricated. The IAHP, with a thickness of merely 2.8 mm, featured ribs on both sides to enlarge the heat transfer area and no welding process is required during assembly in channels. The heat exchanger based on IAHP was introduced and the impact of heat load, operating inclination, and cooling condition on the heat transfer characteristics of the IAHP was investigated through theoretical and experimental approaches. The results indicated that the fabricated IAHP exhibited excellent startup performance and thermal conductivity. Under high heat load conditions, IAHP operated at positive inclinations exhibited superior heat transfer characteristics with its thermal resistance decreasing as the heat load increased, reaching a minimum of 2.06 ℃/W. Conversely, under low heat load conditions, horizontal operation of IAHP was recommended to mitigate the performance degradation caused by working fluid accumulation. Besides, the cooling condition had little impact on the IAHP at vertical operation, requiring merely a minimal cooling cost to achieve better heat transfer performance. These studies provide guidance for the design and performance analysis of the heat pipe heat exchanger.