Molecular dynamics simulation of condensation phenomenon of nanofluid on different roughness surfaces in the presence of hydrophilic and hydrophobic structures

In this paper, the thermal behavior and phase change process of Ar fluid/Ar-Cu nanofluid have been simulated using the molecular dynamics method. The results show that the thermal behavior of the structures is improved by adding roughness to the walls. The roughnesses studied in this research are square cubic, rectangular cubic, and spherical shape. The addition of nanoparticles to the base fluid leads to increases in potential energy in the structures. So copper nanoparticles cause intensify the condensation process. On the other hand, TiO2 as a hydrophilic structure and carboxylic acid as a hydrophobic structure are added to Pt nanosheets with different thicknesses of 5, 7, 10, 12, 15, 17, and 20 A. Obtained results show that adding hydrophilic structure to Ar-Cu nanofluid increases the rate of phase change from 2995 to 3218, 3001 to 3246, and 2990 to 3209 in square cubic, rectangular cubic, and spherical shape wall, respectively. Also, adding hydrophobic structure to Ar-Cu nanofluid leads to a decrease in phase change rate from 2800 to 2597, 2812 to 2605, and 2795 to 2591 in square cubic, rectangular cubic, and spherical shape wall, respectively. The maximum number of fluid/nanofluid particles condensed in the liquid phase in the platinum nanosheets in the presence of rectangular cubic roughness is estimated.