Mass Transfer during Falling Film Evaporation Based on New Multi-Stage Flash Model

Abstract

Based on the studies about the mass transfer of a falling film flow and irreversible thermodynamics, a new multi-stage flash model is proposed to analyze the mass transfer process of falling film evaporation. The evaporation of a falling film is regarded as an interrelated multi-stage flash process in the model, and explains how to save energy during the separation of a binary-component system. By comparing the separation performance of different heating conditions and simulation, the multi-stage flash model is proven reasonable in explaining the mass transfer process of falling film evaporation. In the experiments, the mass transfer efficiency of uniform heating increases over 8% compared with concentrated heating. The multi-stage flash model provides a theoretical basis to improve energy efficiency, and provides a new research approach to analyze the mass transfer of falling film evaporation.