Experimental Study on the Thermohydraulic Performance of Oil-Cooled Heat Sinks for Power Electronics

Using the lubrication oil in (hybrid) electric vehicles as both coolant and lubricant, thereby eliminating the need of a separate coolant circuit, can improve the overall efficiency of the cars. However, oil exhibits inferior heat transfer properties compared to conventional coolants (mainly higher viscosity, lower thermal conductivity and lower specific heat capacity). Therefore, it should be investigated whether the cooling of the drivetrain using oil is sufficiently performant. In this paper, the thermal and hydraulic performance of three oil-cooled heat sink designs (pin fin, straight fin and jet impingement) for power electronics are experimentally evaluated. It can be concluded that the straight fin heat sink exhibits the best hydraulic performance, but the pin fin heat sink has the best thermal and overall performance.