Surface wettability effects on evaporating meniscus in nanochannels

Systematic investigations of self-regulation of evaporating menisci in nanochannels are conducted as a function of the surface wettability under various applied heat flux conditions. The simulation system is designed to result in steady-state response so that a stable meniscus region can be produced. Non-equilibrium molecular dynamics simulations are performed for argon fluid in platinum channels. Depending on the surface wettability and the applied heat flux the meniscus can be in the pinned regime or it can recede inside the channel. Adsorbed layer formation becomes evident for the latter case. Higher wettability enables the formation of a thicker adsorbed layer reducing the radius of curvature of the meniscus and the overall evaporation rate in the channel. Adsorbed layer reduces the thermal resistance of the evaporator, providing a higher critical heat flux. While evaporation from the adsorbed layer is negligible for macroscopic systems, it can contribute up to 80% of the total evaporating mass in nanoscale systems. The current work provides insights into the capillary-driven thin-film evaporation in ultra-small channels and the findings are meaningful for next-generation thermal management systems.