A numerical investigation has been carried out to examine the hydrothermal performance and entropy generation in the Reynolds number range of 198–796 in rectangular microchannel heat sinks with central ribs. Six types of central ribs are designed: rectangular, hexagonal, triangular, fan-shaped, oval, and diamond-shaped ribs. The overall performance is evaluated by combining the performance evaluation criterion (PEC) with the augmentation entropy generation number (Formula: see text). The results indicate that rectangular microchannel heat sinks with central ribs demonstrate significant heat transfer enhancement and less irreversible loss but higher pressure drop. Compared to the straight rectangular microchannel heat sink, the rectangular microchannel heat sinks with central ribs exhibit a significant increase in the average Nusselt number (Nu) and PEC, along with a notable reduction in the total volumetric entropy generation rate (Formula: see text). Specifically, the increase in Nu ranges from 32 to 98%, the increase in the PEC varies between 4 and 48%, while the Formula: see text decreases by 25–42%. Notably, the overall performance of the microchannel heat sink with triangular ribs (MCHS-TR) exhibits the best overall performance, with a maximum PEC value of 1.47. Moreover, the Formula: see text reaches the minimum value of 0.583 for Formula: see text.
Li et al. (2026) studied this question.