Heat transfer enhancement on a microchannel heat sink with impinging jets and dimples

•A new idea of MIJ with dimples is designed.•Comparison on the heat transfer, pressure drop and overall performance of four different structure is presented.•MIJ with convex dimples have the best performance, both in heat transfer enhancement and pressure drop. The introduction of dimples to heat transfer surface can effectively improve the heat transfer performance of a microchannel heat sink with impinging jets (MIJ). MIJs with different dimple structures, including convex, concave, and mixed dimples, are compared with MIJs without dimples by numerical simulation and the application of the field synergy principle. Results indicate that (1) MIJs with convex dimples exhibited the best cooling performance, followed those without dimples, with mixed dimples, and with concave dimples; (2) the application of convex dimples could decrease flow resistance in MIJs; and (3) among all tested cases, MIJs with convex dimples exhibited the best overall performance, followed by MIJs without dimples, with mixed dimples, and with concave dimples.