Enhanced pool boiling performance of cellular metal foams by electrostatic fields for high-power thermal management

Abstract

Pool boiling of cellular metal foams is a promising heat dissipation approach in high heat flux thermal management. Despite enormous efforts, developing an enhanced thermal strategy that could improve the nucleation site density for metal foam with low PPI, reduce bubble–releasing resistance for the ones with high PPI, and prevent the premature occurrence of CHF remains challenging. Herein, a powerful active reinforcement technique utilizing an electrostatic field to promote pool boiling of cellular metal foams is proposed. Results demonstrate the bubble–releasing density and ONB of metal foams are significantly improved with the increment of applied voltage. By employing a high–voltage electrostatic field, the CHF of metal foams could be increased by 48–65 % at 8 kV, in contrast to the field–free cases. In addition, visualization data reveal bubble departure frequency of metal foams might be increased by up to 5.41 times and the bubble departure diameter could be reduced by a maximum of 48.13 % under electrostatic fields. New correlations of enhancement ratio in BHTC and CHF for nucleate boiling on metal foams under electrostatic fields are constructed, taking into account the influences of surface tension, pore density, and voltage. The predicted results exhibit good validation against the experimental data.