Experimental investigation on water drainage characteristics of open-cell metal foams with different wettabilities

For optimizing the metal foam heat exchangers used in dehumidification apparatus, the influence of surface wettability on drainage characteristics should be explicit. In the present study, the water drainage characteristics of metal foams with different wettabilities were experimentally investigated. The experimental results show that the stabilization time of the water drainage process for the hydrophobic sample is the shortest among the tested metal foam samples, and the water retention mass in the hydrophobic metal foam is much smaller than that in the other samples; the wettability impact factors for water retention are within 0.78-1.1 and 0.40-0.77 for the hydrophilic and hydrophobic samples, respectively. The water retention mass in the copper foam is 9.5%-52.6% smaller than that in the aluminum foam. For the hydrophobic copper foam, the water retention mass per unit volume in metal foams with PPI of 5-20 is 45%-66% smaller than that in fin-tube heat exchangers.