Two-Phase Minichannel Cold Plate for Army Vehicle Power Electronics

Army programs have focused on increasing the use of power-dense electronic components to improve system weight, fuel usage, design flexibility, and overall functionality, thus, stressing the thermal management requirements. Recent cooling designs focused on flowing 80–100 °C engine coolant through single-phase microchannel cold plates but concern over pumping power, heat dissipation, cold plate temperature inconsistency, and contaminate clogging have prompted interest in two-phase flow in a minichannel cold plate. In the course of this study, both single- and two-phase experiments were conducted with a 6.8 × 2.7 × 0.9 cm offset fin minichannel cold plate using 25 °C, 80 °C, and 99 °C de-mineralized water, respectively, with flowrates ranging from 0.33 cm³/s to 45 cm³/s. Heat dissipation using solder attached chip resistors was incrementally increased from 0 W to more than 1000 W while simultaneously measuring cold plate pressure drop, chip surface temperature, inlet and outlet fluid temperature, and flowrate. Preliminary results indicate that utilizing a minichannel cold plate with two-phase heat transfer offers the ability to significantly reduce clogging potential, flowrate, and associated pumping power, while improving thermal resistivity by more than a factor of 4 and temperature consistency by greater than a factor of 10. Single- and two-phase correlations were used to compare performance with theoretical values.