A Three-Dimensional Numerical Modelling of Atmospheric Pool Boiling by the Coupled Map Lattice Method

Abstract

In the present paper, the characteristic atmospheric pool boiling curve is qualitatively reproduced for water on a temperature controlled thin copper strip having comparable length and breadth by the coupled map lattice (CML) method using a three-dimensional boiling field model. The basic objective of the work is to improve the prediction of the critical heat flux (CHF) with respect to the 2D CML model of Ghoshdastidar et al. [10]. The work models saturated pool boiling of water at 1 bar on a large (much larger than the minimum wavelength of 2D Taylor waves) and thin horizontal copper strip. The pool height is 0.7 mm, indicating thin film boiling. In the present model, it is assumed that boiling is governed by (a) nucleation from cavities on a heated surface, (b) thermal diffusion, (c) bubble rising motion and associated convection, (d) phase change and (e) Taylor instability. The changes with respect to 2D model are primarily with respect to 3D modelling of thermal diffusion and 2D distribution of nucleating cavity sizes. The predicted CHF is 1.57 MW/m2 as compared to the actual value of 1.3 MW/m2 and 0.36 MW/m2 predicted by the 2D CML model of Ghoshdastidar et al. [10]. It can be said that for the first time a coupled map lattice method which is essentially qualitative in nature has been able to predict the CHF of saturated pool boiling of water at 1 bar very close to the actual value.