Effect of Vapor Bubble Size on Heat Transfer in Spray Cooling

Numerical modeling of multiphase flow using level set method is discussed. The 2-D model considers the effects of surface tension between liquid and vapor, gravity, phase change and viscosity. The two-phase flow modeling is done using the level set method to identify the interface of vapor and liquid. The modifications done to the incompressible Navier-Stokes equations in order to consider effects of surface tension, gravity and phase change are discussed in detail. The governing equations are solved using finite difference method. Recently, the effect of droplet velocity and density ratio on heat removal in a thin liquid film is investigated using the model. In the present work, a further investigation on the effect of vapor bubble size is investigated for the case of a thin liquid film of 44 mum in removing the heat when a liquid spray droplet is impacting. For different vapor bubble sizes the amount of heat removed is plotted in terms of average Nusselt number on the heated plate. The computed liquid and vapor interface is also visualized for better understanding of the heat removal.