Multi-objective optimization of micro-jets cooling with piezoelectrical actuator for heat transfer enhancement

Power devices play a crucial role in pure electric vehicles, with the on-board charger (OBC) requiring higher space and energy density compared to other components. Efficient thermal management of the inverter IGBT module significantly influences the stability and charging efficiency of the OBC. Based on the principle of multi-objective optimization, this study systematically implements an integrated design strategy that synergistically combines a single-cavity microjet array with piezoelectric ceramics. Consequently, a novel piezoelectric single-cavity microjet array cooling composite cold plate, designated as PCE-SCMJ-1, has been developed and proposed herein. Experimental results demonstrate that, at an initial flow rate of 0.95 L/min, the PCE-SCMJ-1 cold plate achieves an approximately 100% increase in the average heat transfer coefficient ( h _avg) along with a 52.1% reduction in thermal resistance, highlighting its superior heat dissipation capability compared to the optimized single-cavity microjet array cold plate (SCMJ-1 cold plate). First, the temperature uniformity of the single-cavity microjet array cold plate (SCMJ cold plate) was improved by optimizing the distribution of the coolant inlet cavity. Subsequently, the cooling structure's optimal performance parameters were identified through multi-objective optimization, and the heat dissipation was further enhanced by incorporating piezoelectric ceramics. The results indicate that, at a cooling rate of 1.5 L/min with three IGBTs/diodes dissipating 408 W, the SCMJ cold plate reduces the maximum temperature of the IGBT (IGBTs- T _max) by approximately 8 K compared to the conventional pin-fin cold plate. By altering the distribution of the coolant inlet cavity, the dual-chamber micro-spraying cold plate (TCMJ cold plate) reduced the IGBTs- T _max and the temperature difference (IGBTs-∆ T ) by 0.97 K and 0.59 K, respectively. In the multi-objective optimization, the SCMJ-1 cold plate reduces the IGBTs- T _max, IGBTs-∆ T , and total thermal resistance ( R _total) by 1.9 K, 5.76%, and 8.66%, respectively.