Numerical Simulation of a Single Bubble Dynamic in Nucleate Pool Boiling by using Finite Difference Method
Mateus Faria de Andrade Paschoal1; Elaine Maria Cardoso1; João Batista Campos Silva1
1 Universidade Estadual Paulista UNESP - Campus de Ilha Solteira
doi:10.20906/CPS/CILAMCE2017-1082
Resumo
Heat transfer with phase change is a very effective way to remove high rate heat flux from processes. In this way, nucleate pool boiling is used, for example, to refrigerate heated surfaces, when a fluid boils on the surface. High heat fluxes and high heat transfer coefficient are characteristics of pool boiling. The mechanism of pool boiling is very complex and motivates the interest of many researchers in understanding this process. The nucleation, growth and departure of bubbles from a heated surface have deserved attention and there are many papers in the literature concerning experimental, empirical or semi-empirical and numerical solutions to the problem. Experimental apparatus, generally, is expensive and several other difficulties are associated with this kind of solution. In the last decades, numerical solutions of bubble dynamics have appeared in the literature. Bubble dynamic involves moving contours which difficult the solution of the problem in predicting the form of bubble volume and the velocity of the bubble contour. For simplification, generally, the bubble is considered as spherical or hemispherical. In this work, an analysis is proposed to simulate the growth of a single bubble on a horizontal surface in which the temperature is changing in time. In many works, the temperature of the heater surface is considered constant in time. Considering a hemispherical bubble, the Navier-Stokes equations in spherical coordinates are the mathematical model to the problem and they are solved numerically by a finite difference method. Due to the variable temperature field on the surface, the equation of this governing problem must be also solved. Another simplification is not to take into consideration the microlayer underneath the bubble. Initially, is considered a correlation from the literature to predict the velocity of the bubble contour and the equations for the velocity field and the temperature field is solved for the adjacent liquid until the time of the bubble departure. After discretization, the al
Palavras-chave: Nucleate pool boiling; Bubble dynamics; Navier-Stokes equations; Finite difference method