Spray Cooling Modeling: Liquid Film Thickness Effect on Heat Transfer

Abstract

Spray cooling is a novel solution for high heat flux applications, whose need is becoming apparent with the advance of high power density electronic systems (lasers, radars, etc). The aim of this investigation is to explore thermal management solutions for space‐based systems and the effects of varying gravity on heat transfer. Previous modeling done by Selvam, Lin, and Ponnappan (2006) used a liquid film thickness of ≈ 40 μm on the heater wall. The two‐phase flow modeling is done using the level set method to identify the interface of vapor and liquid as explained in Selvam, Lin, and Ponnappan (2005; 2006). Modifications to the incompressible Navier‐Stokes equations for surface tension, viscosity, gravity and phase change are discussed in detail. The equations are solved using finite difference method. The computed heat flux in thick layers is compared with previous thin layer heat flux. The computed liquid and vapor interface and temperature distributions are also visualized for better understanding of the heat removal process. To understand the heat transfer mechanisms in thick liquid layer, droplet impact on a growing vapor bubble is used to study heat transfer in the liquid layer. The thickness has been varied from 100 μm to 200 μm. Also the impact of initial temperature distribution on heat flux is investigated. This will help us to know how to improve the heat transfer in spray cooling.