This paper describes a model of the absorption process in a falling film ammonia-water absorber. The model consists of two ordinary, first-order differential equations with suitable inlet and interface conditions. The model was validated by comparing its predictions to experimental data. The objective of the work was to define strategies to enhance the absorption process in order to downsize absorbers. It was found that in most situations of practical interest, the mass transfer process in the falling film controls the absorption rate. The possibility of water evaporation and migration in the absorber is discussed, outlining how it can degrade performance.

Units: Dual