Modification and pool boiling performance elevation of copper foam wicks for high power applications

Surface modification is an effective method to improve boiling heat transfer performance and has the feasibility of application in enhancing equipment cooling and energy conversion efficiency. A magnetron sputtering (MS) method is employed to modify the skeleton surface of copper foam for further maximizing the boiling performance in this study. After modification, the heat transfer coefficient (HTC) and critical heat flux (CHF) of copper foam wicks have been significantly improved, with a maximum increase of 75.6 % and 17.3 % compared to the original copper foam, respectively. The greatly enhanced boiling performance is attributed to the structure of “cauliflower-like” and gradational wettability along the thickness direction, which provide more nucleation sites and increase the bubble detachment frequency. Meanwhile, the heat transfer correlation for modification samples is developed, and the results show an average error equal to 11.2 %. In addition, the beat sample is assembled in the evaporator of heat pipe (HP) as wick which increased the heat transfer coefficient by 144.3 ∼ 333.4 %. All results demonstrated that the surface modification of copper foam based on MS can greatly increase heat and mass transfer performances, which is promising in the high power applications.