An experimental and computational study of water cooled heatsinks for HEV's

Power switching devices in dc/dc power converters for Hybrid Electric Vehicles (HEVs) are fluid cooled. Fluid cooled heatsinks make up nearly a third of the volume and weight of DC/DC converters. The design of heatsinks in automotive applications is therefore of paramount importance in order to gain high power-to-volume and high power-to-weight ratios. Literature on heatsink designs often present test results that are based on one set of input data only (e.g. fluid inlet temperature, flow rate and fluid mixture). The fluid inlet temperature and flow rate, however, can vary substantially in an automotive fluid cooled system and the heatsink may therefore not perform well. Fluctuation of theses parameters must therefore be considered in the design of fluid cooled heatsinks in order to allow optimal cooling performance under all conditions. This paper describes the design of a heatsink that is optimised for one set of parameters. The heatsink is then tested at temperature and flow rate variations to emulate the fluctuation in a vehicle cooling system.