A numerical study of multiphase flow boiling heat transfer of nanofluids in the horizontal metal foam tubes

The study aims to numerically investigate the flow boiling of Al2O3/H2O and CuO/H2O nanofluids and water in pipes filled with copper metal foams. Four different values of porosity and three values of pore density have been used. To perform numerical simulation, the mixture model has been developed. For the first time, the effects of nanoparticle deposition on the wettability of heating surfaces were considered with the help of user-defined functions. Besides, the effect of metal foams with different porosities on the onset of nucleate boiling was evaluated. The thermal performance of metal foam pipes has been compared with each other by comparing the increase in heat transfer and pressure drop. As a result, by reducing the porosity from 0.95 to 0.80, the heat transfer coefficient was increased by 59 %, while the pressure drop increased by 28 %. Finally, by comparing the increase in heat transfer and pressure drop, results show that the metal foam pipe with 80 % porosity and 5 pores per inch has the best thermal performance. The results of this study are expected to be used for the optimization of advanced phase change cooling technologies.