A numerical study of heat and mass transfer in falling film absorber

Abstract

This paper describes a model of the absorption process in a falling film Lithium Bromide-Water absorber. Absorption of a gas or vapor into a laminar falling film on the surface of a vertical tube is taken into account. Necessary boundary conditions are provided to solve simultaneous parabolic partial-differential equation which are obtained by diffusion and energy equations characterizing absorption process. To solve these partial differential equations Crank-Nichelson Method was used. Solutions for temperature and concentration distributions were obtained by applying these equations in discretized flow field. Nusselt and Sherwood numbers are calculated for absorber. The coolant-side heat transfer coefficient may be calculated using standard correlations. The effect of varying coolant flow rate, solution flow rate and coolant temperature are also studied. Results which are found out from the model are compared with experimental data and analytical results. Agreement is found to be good.