Effects of the pin-fins cooler roughness on the thermo-fluid dynamics performance of a SiC power module

The objective of this study was to develop a Computational Fluid Dynamics (CFD) 3D model for an industrial application, to investigate how surface roughness affected pressure drop and thermal performance in the ACEPACKTM DRIVE, a commercial SiC-based power module used in traction inverters, that features a pin-finned baseplate with cylindrical pin-fins. The surface roughness of the pin-fins was modelled by using a sand-grain model available in Ansys Fluent, which represents a novelty in the literature and can pave the way for the development of accurate and computationally efficient simulations. The CFD model exhibits an error from experimental data within the range 10%–22% when the flow rate varies from 2 l/min to 12 l/min (maximum error at 2 l/min), while the validation of the thermal behaviour was obtained with a maximum error of 2.5%. Subsequently, a parametric analysis was carried out, varying the flow rate of the coolant, in order to investigate the influence of pin-fins surface roughness on performance, by considering two possible design option featuring respectively a surface roughness equal to 1 μm and 6 μm. The results showed a reduction in pressure drop from 4% to 11% and a degradation of the thermal performance, less than the 2%, when the pin-fins roughness increases.