Experimental investigation of pool boiling heat transfer enhancement using electrodeposited open-cell metal foam

Abstract

Pool boiling is specified as boiling stemming from a heated surface that is submerged in a volume of liquid resulting in a phase transition to vapor. The subject of pool boiling heat transfer heat has continuously received attention due to its various applications among researchers. One of the avenues used to improve pool boiling is the employment of open-cell metal foams. In this study, an attempt has been made to study the effect of electrodeposited open-cell metal foam coating on pool boiling heat transfer under atmospheric conditions and deionized water. The foams have three pore densities of 5, 10, and 20 ppi and a constant porosity of 0.95. In each pore density of the open-cell foams with five different thicknesses, copper is deposited on the foams through electrodeposition, and thereafter pool boiling test is performed. Also, to evaluate the number of electrodeposition steps, 4 and 8-step electrodeposition is implemented on the best pore density foam sample from the preceding section. In addition, untreated foams in five different thicknesses and also nickel foams are tested for comparison with electrodeposited copper. The results reveal that 20 ppi 6-step electrodeposited copper open-cell foam with a thickness of 4 mm improves the pool boiling heat transfer in medium and high heat fluxes by up to 160% and 130%, respectively, and thence has the best performance among all the sample foams. However, at a pore density of 5 ppi, the 8-and 6-step electrodeposited open-cell foam with 8 mm thickness achieves the best performance and improves the pool boiling heat transfer at medium and high heat fluxes by approximately 150% and 100%, respectively. In addition, at a pore density of 10 ppi, the 6-step electrodeposited open-cell foam with 4 mm thickness, attained the best results and improved the pool boiling heat transfer at medium and high heat fluxes by 103% and 120%, respectively. SEM, microscopic, and aging images of the foams were carried to compare the structure and strength of the number of electrodeposition steps.