Optimizing heat transfer in microchannel heat ex-changers: a comparative analysis of channel geometry and nanofluids through CFD and experimental approaches.

Abstract This study investigates the impact of channel geometry and nanofluid concentration on heat transfer performance in microchannel heat exchangers, using both CFD simulations and experimental methods. Results show that increasing nanoparticle concentrations and mass flow rates enhance heat transfer in both rectangular and circular channels. At a nanoparticle concentration of 0.05% and a Reynolds number of 500, circular channels demonstrated superior heat transfer performance compared to rectangular channels. Nusselt numbers increased by 18.16% for rectangular and 24.55% for circular channels on average. Pressure drops for both geometries also increased, with a 17.57% rise for rectangular and 16.74% for circular channels, relative to the base fluid. Additionally, the pressure drop was 4.72% higher in rectangular channels than in circular ones. Lower Reynolds numbers contributed to a significant reduction in friction factors, with the minimum friction observed at 0.01% nanofluid concentration. Circular channels exhibited lower friction factors compared to rectangular channels across different nanofluid concentrations. CFD and experimental results were in close agreement, particularly regarding pressure drop and temperature, confirming the accuracy of the analysis.