Corner flow characteristics in a silicon-based ultra-thin flat-grooved heat pipe with double-end cooling

Abstract

This study delves into the exploration of flow and heat transfer characteristics within a silicon-based ultra-thin flat-grooved heat pipe (UFHP) featuring double-end cooling based on a visual experimental platform. Ethanol is chosen as the working fluid due to its hydrophilic properties with the silicon substrate. The investigation focuses on the analysis of corner flow phenomena within microgrooves. In contrast to prior research associating corner flow with the subsequent thermal performance degradation, our experimental findings demonstrate that proper corner flow has better heat transfer performance in comparison with axial flow in the UFHP with double-end cooling. Optimal thermal resistance in the UFHP is achieved when corner flow dominates in the evaporator, underscoring the pivotal role of thin film evaporation in enhancing overall thermal efficiency. Additionally, the thermal performance of the UFHP is systematically investigated under diverse operational conditions, including variations in filling ratio, groove depth, and vapor space thickness. While a slight excess in filling ratio exhibits a restrained impact on the heat transfer limit, it effectively mitigates the temperature rise following complete dry-out at the evaporator. Notably, reductions in groove depth and vapor space thickness detrimentally affect the heat transfer limit, albeit a decrease in groove depth contributes to a reduction in thermal resistance.