Polymer-based pin-fin microchannel heat exchangers: A comparative study of material and structural effects on performance

In this comprehensive study, the applicability and heat transfer dynamics of polymer pin-fin microchannel heat exchangers were investigated through a combination of experimental and numerical approaches. The findings revealed that enhancements in material thermal conductivity do not exhibit a linear correlation with improvements in heat transfer performance. Beyond a certain threshold, the impact of thermal conductivity on temperature stability diminishes significantly. Notably, polymer-based micro heat exchangers demonstrated remarkable temperature uniformity in comparison to other materials. To address the issue of localized thermal peaks in electronic chipsets, a heat exchanger featuring variable pin-fin sizes was designed. This design resulted in a significant reduction in the temperature of the heat source when compared to a constant-size pin-fin configuration. Specifically, variable-size pin-fin structures (the staggered-arrangement variable-size micro-needle-fin heat exchanger (VSPFS) and the inline-arrangement variable-size micro-needle-fin heat exchanger (VIPFS)) achieved temperature reductions in the range of 1.41–3.60K and 6.07–8.48K, respectively, when compared to their isometric counterparts (the staggered-arrangement constant-size micro-needle-fin heat exchanger (ISPFS) and the inline array of constant-size pin-fin microchannel heat exchanger (IIPFS)). Furthermore, these structures significantly decreased the average temperature difference across the heat source, effectively mitigating thermal hotspots by up to 3.23K and 5.73K, respectively. Among the tested configurations, VSPFS exhibited the highest Performance Evaluation Criterion (PEC) value and the smallest increase in entropy generation, highlighting its superior overall thermal management capability. Additionally, as the Reynolds number increased, convective heat transfer entropy generation decreased while fluid friction entropy generation increased, indicating that energy losses due to fluid friction gradually outweighed the benefits of enhanced heat transfer at higher Reynolds numbers.