Flow and heat transfer enhancement of microchannel under non-uniform heat flux via topology optimization

• Different fins are formed via topology optimization method under non-uniform flux. • Adaptive shape and arrangement of topology optimized fin reduce pressure drop. • Heat transfer by topology optimized fins is superior compared to traditional fins. • Topology optimized microchannel with non-uniform flux owns best overall performance. Microchannel heat sink has emerged as a highly promising thermal management solution to deal with high heat flux for electronic devices. This study employs topology optimization (TO) method to develop adaptive fins in microchannels under non-uniform heat flux and investigates the thermal–hydraulic performance of TO microchannels. Different adaptive fins with long and narrow shape and staggered arrangement can be generated in microchannels under four non-uniform heat sources. Numerical results demonstrate that microchannels with TO fins have a slightly higher pressure drop than those with straight fins, but achieve 74%, 86%, 84% and 86% reductions in pressure drop compared to microchannels with circular fins under the four different heat sources, respectively. The average temperatures of channel base in microchannels with TO fins drop by at least 1.8 ℃, 2.5 ℃, 1.6 ℃ and 2.1 ℃, and the thermal resistances decrease by 23%, 17%, 22% and 12% under the four different heat sources, compared to microchannels with circular fins or straight fins, respectively. PEC in TO microchannels are the largest at varied inlet velocities, showing 68%, 119%, 98% and 114% improvements compared to microchannels with circular fins under the four heat sources, respectively. This proves that microchannels with TO fins exhibit superior comprehensive performance under all non-uniform heat fluxes. The underlying mechanism is that TO fins mitigate fluid stagnation and backflow, disrupt thermal boundary layer development and enhance fluid mixing.