Combined generator for an NH3-H2O absorption chiller

This study concerns the development of a combined generator for an NH3-H2O absorption chiller, integrating vapor generation and purification in a single component. The combined generator involves adiabatic and heated falling-film over flat plates. The lower part of the exchanger can be flooded and includes pool-boiling mechanisms. A model describing heat and mass transfer along the exchanger is developed. The model takes into account the plate's wettability and pool boiling. The ability of the model to predict the combined generator performance is investigated using experimental data obtained over a large range of operating conditions. The purity of the ammonia vapor produced is significantly higher than the one produced by the usual generator, and it depends on the operating mode and the temperature of the heat source. Finally, the combined generator effectiveness is examined for both operating modes. The optimum of the inlet HTF temperature is at T-gen = 110 ? for the mass and thermal effectiveness. The optimum of the inlet solution temperature corresponds to + 3.5 ? superheating. (c) 2022 Elsevier Ltd. All rights reserved.