Design and experimental study of a plate-type falling-film generator for a LiBr/H2O absorption heat pumpConception et étude expérimentale d'un générateur à film tombant de type plaque pour une pompe à chaleur à absorption au LiBR/H2O

•Pate-type falling-film generator for LiBr/H2O absorption heat pump is presented.•A directly-connected overflow solution distributor for falling-film is proposed.•Visual vacuum solution falling-film flow pattern experiments were conducted.•The wetting rate increased when the plates were heated or wetted in advance.•Tested heat transfer coefficient range of the generator is 0.735~0.856 kW⋅m−2⋅K−1.

A novel plate-type falling-film generator for a LiBr/H2O absorption heat pump and the resulting generator/condenser unit prototype are presented in this paper. The generator consists of a directly-connected overflow solution distributor. This novel structure can ensure uniform solution distribution and stable falling-film flow; it is also more compact and provides greater feasibility to regulate capacity by plate assembly compared to conventional distributors for falling film. Visual flow pattern experiments were conducted in a vacuum atmosphere. Split flows and obvious parabolic dry areas were shown to exist. The method to improve the wetting rate was also investigated. Thermal performance tests show that the heat transfer coefficient of the generator ranged from 0.735 kW⋅m−2⋅K−1 to 0.856 kW⋅m−2⋅K−1. The flow and thermal experiment results demonstrate the feasibility of the plate-type falling-film generator for a LiBr/H2O absorption heat pump. The concept of the novel generator can be used for all absorption heat pump components and thus greatly increase the generalizability of the absorption technology.