Numerical Simulation of Heat and Mass Transfer in Falling Film Absorption Generators

A two-dimensional analysis of heat and mass transfer during the evaporation of Li-Br aqueous solution on horizontal circular tube is performed. The study is based on the laminar flow of Li-Br aqueous solution over horizontal circular tube having a constant tube wall temperature. The effect of boiling has been ignored and free surface of Li-Br falling film is assumed to be saturated. A numerical investigation is carried out using a computational fluid dynamics (CFD) code, FLUENT, to calculate the heat transfercoefficient and the rate of evaporation. The results showed that the average heat transfer coefficient and evaporation mass flux is increased with increase in system pressure, degree of wall superheat, and also decreased with increase in inlet Li-Br concentration. The comparison between numerical results with the existing experimental and numerical data verify the validation of present model.

Keywords:

computational fluid dynamics , heat and mass transfer , Li-Br falling film , generator