Improvements in performance and durability through surface modification of aluminum micro-pulsating heat pipe using water as working fluid

PHPs (pulsating heat pipes) using water are typically made of Cu and Si. Although Al is more sustainable than Cu and cheaper than Si (in addition to weight and durability advantages), water-Al PHPs have not been extensively investigated because noncondensable H-2 gas is generated during Al-water reactions at high temperatures, stopping the flow in PHPs and degrading the thermal performance. In this study, a nontoxic micro-nano surface treatment method that is cheaper and simpler than the only reported method for water-Al PHPs was applied to the internal surface of an Al PHP. This prevented H-2 gas production by forming Al(OH)(3), thereby eliminating possible reaction sites on the surface. The internal two-phase flows, which significantly affected the thermal performance of PHPs, were compared using a flow visualization technique. The dry-out region gradually expanded in the original PHP with increasing operation time. In contrast, the modified surface PHP exhibited flow regeneration, preventing dry-out, as well as a thermal resistance 45.8% lower than that of the original surface PHP. Further, the critical heat flux of the PHP remained at 4.57 W/cm(2) with the modified surface. Therefore, the proposed method improved the performance and durability of water-Al PHPs. (c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

A cheaper and simpler micro-nano surface treatment method was applied to improve the performance and durability of water-Al PHPs by preventing the production of H-2 gas during Al-water reactions. The modified PHP exhibited flow regeneration and a 45.8% lower thermal resistance compared to the original surface PHP.