Hybrid microchannel/multi-jet two-phase heat sink: A benchmark and geometry optimization study of commercial product

•An experimental test rig is developed to characterize and optimize performance of a commercial heat sink.•A variation in fin height can result in significant enhancement of heat transfer coefficient without changing pressure drop significantly.•Heat transfer coefficient increases as subcooling is reduced.•Heat transfer coefficient is highly dependent on flow rate in single-phase regime and convective boiling but weakly dependent on flow rate at nucleate boiling.•A new regression function of hydraulic diameter, heat flux, subcooling and Reynold number is developed to predict heat transfer coefficient values.