Comparison between the optimum performance of different absorption systems

The various papers appeared in the literature regarding absorption systems often refer to different working conditions and assumptions, making the comparison of results not easy. This work searches for a fair comparison among the performances of different absorption cycle configurations using the same modelling approach and external conditions. A preliminary analysis of type, number and values of the independent design variables of each configuration is first performed. The purpose is identifying proper ranges of variations of these variables for the subsequent design optimization of each configuration. The attention focuses on the main absorption systems proposed in the literature, i.e. single and half effect systems, and GAX one. The goal is finding the optimal COP of each configuration when it operates in the proper range of the heat source temperature, for a fixed value of the evaporation temperature and a minimum allowed condensation temperature. Results confirm the higher coefficient of performance of the GAX cycle compared to the single effect one using ammonia-water mixture. Moreover, the half effect system using water-lithium bromide is suitable to exploit waste heat sources with temperatures too low to activate a single effect. New options of internal heat integration are analysed by applying the HEATSEP approach to foresee possible increases in the performance of the best existing configurations.