Design of light-weight, single-phase liquid-cooled heat exchanger for automotive power electronics

Efficient thermal management is critical to increasing power density, improving reliability, and reducing the cost of automotive power electronics. In this paper, we present a heat exchanger design based on impinging jets (with 50%-50% mixture by volume of water-ethylene glycol as coolant) on the copper base plate with and without microfinned/enhanced surfaces, and a plastic fluid manifold. Finite-element analyses as well as computational fluid dynamics (CFD) modeling were utilized for the design. The performance of the jet-based heat exchanger is compared to the baseline channel-flow heat exchanger via CFD modeling. We also characterized the thermal performance of the channel-flow-based heat exchanger experimentally to validate the CFD predictions. CFD results indicate that the jet-based heat exchanger can provide up to 45% lower thermal resistance, 79% increase in power density, and 118% increase in specific power with respect to the baseline channel-flow heat exchanger. We also initiated experimental characterization of the reliability of jet impingement on a plain surface as well as on microfinned/enhanced surfaces. Results to date suggest that jet impingement does not degrade the thermal performance of the enhanced surfaces after six months of near-continuous impingement on the surface.