Absorption heat pump cycles using an ammonia-water mixture and linked in a material cascade

This study is devoted to the modelling of absorption heat pumps using an ammonia-water mixture, for air conditioning. The mixture is separated in a distillation column and the components are remixed in a number of evaporatiion-absorption cells, linked in a material cascade. We compare the performance of three structures, with one, two or three stages, and we determine the influence of various parameters: final desorption temperature, cold source temperature, the number of theoretical separation plates, and the thermal pinch of the main exchanger. This last factor exerts only a small influence, the two-stage cycle appears to be the most efficient: it is even more efficient than the three-stage cycle. The higher rectification losses and recirculations rates for athe three-stage cycle lower its performance. The three-stage cycle becomes the most efficient for the production of cold at a lower environmental temperature and with a greater number of theoretical separations plates. copyright 2001 Published by Elsevier Science Ltd and IIR. All rights reserved.