Heat transfer modelling of two-phase bubbles swarm condensing in three-phase direct-contact condenser

Abstract

An analytical model for the convective heat transfer coefficient and the two-phase bubble size of a three-phase direct contact heat exchanger was developed. Until the present, there has only been a theoretical model available that deals with a single two-phase bubble and a bubble train condensation in an immiscible liquid. However, to understand the actual heat transfer process within the three-phase direct contact condenser, characteristic models are required. A quasi-steady en-ergy equation in a spherical co-ordinate system with a potential flow assumption and a cell model configuration has been simplified and solved analytically. The convective heat transfer in terms of Nusselt number has been derived, and it was found to be a function to Pecklet number and a system void fraction. In addition, the two-phase bubble size relates to the system void fraction and has been devel-oped by solving a simple energy balance equation and using the derived convec-tive heat transfer coefficient expression. Furthermore, the model correlates well with previous experimental data and theoretical results.