Droplet Condensation and Transport Properties on Multiple Composite Surface: A Molecular Dynamics Study

To investigate the microscopic mechanism underlying the influence of surface-chemical gradient on heat and mass recovery, a molecular dynamics model including droplet condensation and transport process has been developed to examine heat and mass recovery performance. This work aimed at identify optimal conditions for enhancing heat and mass recovery through the combination of wettability gradient and nanopore transport. For comprehensive analysis, the structure in the simulation was categorized into three distinct groups: a homogeneous structure, a small wettability gradient, and a large wettability gradient. The homogeneous surface demonstrated low efficiency in heat and mass transfer, as evidenced by filmwise condensation. In contrast, the surface with a small wettability gradient experienced a transition from dropwise condensation to filmwise condensation, resulting in a gradual decrease in the efficiency of vapor heat and mass transfer. Only a large wettability gradient could achieve periodic and efficient dropwise condensation heat and mass transfer which was attributed to the rapid droplet coalescence and transport to the nanopore after condensing on the cold surface.