Boiling on nano-porous structures: Theoretical analysis and molecular dynamics simulations

Abstract

The nano-porous structures have been employed to enhance the boiling heat transfer. To optimize the nano-porous structures so as to improve the boiling heat transfer, it is necessary to disclose the impacts of the nano-porous structures on the characteristics of boiling. Experimentally, it is difficult to observe the phenomena of boiling inside the nano-porous structure. An alternative way is to resort the theoretical and modeling analysis. In the present study, we fist perform a theoretical analysis on boiling on the nano-porous structures from the macroscopic perspective. We find that the boiling inception time is proportional to the ratio of the void volume to the solid surface area; and that the critical heat flux is a power law function of the pore size, with the exponent of 1.5. To demonstrate these theoretical analysis, we then perform the molecular dynamics simulations on boiling of argon on the copper based nano-porous structures. The molecular dynamics simulations demonstrate the theoretical analysis. It is revealed that the boiling inception time is a power law function with respect to the ratio of the void volume to the solid surface area. The exponent for the power law relation between the critical heat flux and the pore size is 1.232. The critical heat flux occurs at the moment when the surface of the nano-porous structures is completely covered by the vapor film.