Experimental analysis of pool boiling heat transfer on surfaces fabricated by electric discharge coating

Abstract

The recent advances in the growth of miniature high power devices have led to the increased need for dissipation of large amount of heat generated in those devices. Compared to single phase cooling techniques, boiling provides a more effective two-phase heat dissipation method. Micro-structures in the boiling surface help to enable higher rate of heat transfer by providing air pockets for bubble generation. The present experimental study involves fabrication of micro-structured surfaces by employing Electric Discharge Coating (EDC) process. The surfaces were prepared by depositing a composite coating of titanium and copper microparticles on a copper surface at different current settings. The surfaces obtained were hydrophobic in nature which resulted in a decrease in the surface superheat at boiling incipient. Pool boiling experiments and analysis were performing on it by using deionized water as the boiling fluid. The Critical Heat Flux (CHF) also improved in the modified surfaces due to the globular structures formed with increased cavity sizes and porosity. The average Nucleate Boiling Heat Transfer Coefficient (NBHTC) increased to 206% and the surface superheat decreased by 42% for the best performing surface.