Studies on heat transfer performance of miniature cross-flow heat exchangers with perforated fins for direct methanol fuel cells

Abstract

Despite the widespread industrial application of finned micro heat exchangers, there is still a need to enhance the heat transfer efficiency. This study focuses on fin perforation research to improve heat transfer efficiency. In this study, a miniature cross-flow heat exchanger (heat source is a heat stream at 351.35 K) was simulated. By employing a combination of experimental methods and numerical simulations, the investigation delves into the impact of mixed shapes and innovative spatial distributions of perforations on fin convective heat transfer characteristics. The findings demonstrate that square and square-and-diamond perforated fins exhibit a temperature drop increase of 10.1 % and 8.9 %, respectively, in comparison to unperforated fins during forced convection. Fin temperature drop is augmented by 12.3 % with differentially staggered perforations on adjacent fins (spatially staggered perforations) in contrast to parallel perforated fins, and by 23.6 % compared to non-perforated fins. Furthermore, the optimal performance of the fin heat transfer is observed at 5.74 % perforated area occupancy. The study reveals a positive correlation between the Nusselt and Reynolds numbers. Moreover, the spatial distribution of perforations significantly enhances the performance evaluation criteria compared to the perforation shape. Ultimately, the implementation of fin perforation technique is considered to offer more consistent power output and an extended range for direct methanol fuel cells.