The effect of hydrophilic and hydrophobic surfaces on the thermal and atomic behavior of ammonia/copper nanofluid using molecular dynamics simulation

•Molecular dynamics method was implemented.•Simulated structure has a higher density in the presence of a hydrophilic surface.•Using hydrophilic surfaces, condensed nanofluid particles were reduced to 71 % in 2.83 ns.•The presence of a hydrophilic surface has led to an increase in thermal conductivity.•The presence of hydrophilic surfaces improves the thermal behavior of nanofluid. The formation of hydrophilic (HPI) and hydrophobic (HPO) surfaces on the walls of simulated aluminum nanochannels (NC) directly affects the thermal behavior and atomic behavior of nanofluid (NF) flows. In the present study, the thermal behavior and atomic behavior of ammonia/Cu NF in an aluminum NC with the walls that covered with HPI (TiO2) surface, HPO surface (Carboxylic acid), and a combination of these two atomic structures were studied using molecular dynamics simulation (MDS). The quantities of phase change time (PCT), aggregation time (AT) of nanoparticles (NPs), and thermal conductivity (TC) are studied to examine the atomic behavior and thermal behavior of structures. The simulated structure has a higher density (D) in the presence of HPI surface than HPO surface and combined surfaces. Also, using HPI surfaces on the inner surface of aluminum NCs, condensed particles were reduced to 71 % in 2.83 ns, which shows the highest percentage of phase-changed particles in the shortest time. Also, the HPI surface leads to an increase in the TC and AT. According to this simulation, the presence of HPI surfaces improves the thermal behavior of ammonia/Cu NF.