Latent heat of vaporization of nanofluids: Measurements and molecular dynamics simulations

This paper reports measured and calculated (through molecular dynamics simulations) latent heat of vaporization (H_fg) for water and ethanol based nanofluids. The experimental results showed that the addition of 3 wt. % Ag and Fe nanoparticles in water results in a substantial reduction in H_fg (25% and 17%, respectively). On the contrary, 3 wt. % Al addition slightly increases H_fg (3%). Similar trends were observed for ethanol based nanofluids: 3 wt. % addition of Ag and Fe resulted in a reduction in H_fg by 19% and 13%, respectively, whereas 3 wt. % Al addition resulted in an increases in H_fg by 2%. Molecular dynamics simulations, which determine H_fg by calculating the total enthalpy change of a system before and after vaporization from a molecular level, showed that the strength of bonding between the nanoparticles and the fluid molecules is the governing factor in the variation of H_fg upon particle addition. It was found that the strength of Al/water bonds was much greater than Ag/water, resulting in a reduction in H_fg for the Ag/water nanofluids.