Numerical modelling of atmospheric pool boiling by the coupled map lattice method

In the present paper, the characteristic atmospheric saturated pool boiling curve is qualitatively reproduced for water on a temperature-controlled long and thin copper strip using the coupled map lattice (CML) method known in non-linear spatio-temporal chaos dynamics. The pool height is 0.7 mm, indicating that the boiling is of the thin-film type. The work modifies the basic theoretical model proposed by Shoji in 1998 in terms of nucleation superheat distribution and mixing. The stirring action of the bubbles is modelled by increasing the fluid thermal diffusivity by an enhancement factor. 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 effectiveness of the enhancement factor approach in the present model is clearly seen in its capability of reproducing the saturated pool boiling curve well and predicting the critical heat flux (CHF) in the same order of magnitude of the actual value.