Free convection film boiling over a discrete flat heater with different surface orientations

Abstract

In the present numerical study, a two-dimensional, laminar, free convection saturated film boiling of water at near critical conditions over a discrete heater surface flush mounted over a flat plate has been investigated. For the numerical simulations, a multi-directional advection algorithm based Coupled Level Set and Volume of Fluid (CLSVOF) interface capturing method is used. In this study, both the flow and heat transfer characteristics are evaluated for various heater sizes, wall superheats, and the angle of orientations of the flat plate. The numerical modeling of the three phase moving contact lines is evaluated with the experimental data of a single droplet impact and spreading over a horizontal flat solid surface. From the numerical study, it is observed that the heat transfer rate from a small size discrete heater surface is higher compared to that of a large size heater surface. It is also observed that the variation of the plate orientation angle, α of the heater surface from upward facing horizontal position (α = 0°) to vertical position (α = 90°) shows increase in the magnitude of upward rising vapor velocity due to increase in the buoyancy force. It leads to higher rate of heat transfer at vertical position compared to that of horizontal position.