Numerical simulation of heat transfer and pressure drop in fluid flow through conical microchannels

This study presents a numerical investigation of laminar flow and heat transfer in conical microchannels using computational fluid dynamics (CFD). The performance of the microchannel is examined over a range of Reynolds numbers, as well as different inlet, outlet, and total channel lengths. The results show that the pressure drop exhibits a coupled dependence on both inlet length and Reynolds number. Increasing the inlet length leads to an average reduction of 19% in pressure drop for every 1-mm increase, whereas increasing the Reynolds number produces an average increase of 37.5% for every 300-unit increment. The heat-transfer coefficient decreases with increasing inlet length but increases with increasing Reynolds number. On average, a 300-unit rise in Reynolds number leads to a 10.17% increase in the heat-transfer coefficient, while a 1-mm increase in inlet length results in a 52.5% decrease. The temperature difference between the inlet and outlet is found to be primarily governed by the Reynolds number, with negligible sensitivity to inlet length; for every 300-unit increase in Reynolds number, this temperature difference decreases by approximately 25%. The outlet length also influences both pressure drop and heat-transfer coefficient, following similar trends: a 300-unit increase in Reynolds number results in an average increase of 55.73% in pressure drop and 10.32% in heat-transfer coefficient. Overall, the results demonstrate that geometric variations and flow conditions significantly affect the hydrodynamic and thermal behavior of conical microchannels, providing useful insights for the design and optimization of micro-scale thermal systems.