Effect of hydrophilicity and hydrophobicity on pool boiling heat transfer characteristics on metal foam

As aircraft and spacecraft continues to evolve toward higher performance, the compactness and heat dissipation efficiency of thermal control system need to be improved. Metal foam has great potential in the application of aviation and aerospace thermal control due to its large specific area and high thermal conductivity. The pool boiling heat transfer characteristics on hydrophilic and hydrophobic metal foam covers were studied experimentally, and compared with those of uncoated metal foams. The effect of hydrophilicity and hydrophobicity on the pool boiling heat transfer performance of metal foams with different pore densities and porosities is analyzed. The test samples are copper foams with pore densities of 5 PPI, 20 PPI and 40 PPI, and porosities of 85% and 95%. The results show that hydrophobic modification can reduce the incipient boiling superheated degree by 20%—30%, while hydrophilic modification has no significant effect on the onset of nucleate boiling. Hydrophobic metal foams and hydrophilic metal foams have the optimum pool boiling heat transfer performance under low heat flux ( q< 4×105 W/m2) and high heat flux ( q ≥4×105 W/m2) conditions, respectively. Surface modification has a more significant effect on pool boiling heat transfer enhancement for low porosity metal foams, and hydrophilic modification is more effective than hydrophobic modification in improving thermal performance. © 2021, Editorial Board of CIESC Journal. All right reserved.