Energy and exergy analysis of a combined GAX- ejector absorption refrigeration cycle; specific ejector geometry

In this article، a combined GAX-ejector absorption refrigeration cycle is proposed and its performance is compared with those of combined single effect-ejector، simple GAX and single effect absorption refrigeration cycles. For the ejector، based on the Keenan''s theory، a new model is developed and validated and then is combined with the developed models in the EES software (for simulating the processes in the cycles). After obtaining the optimum critical area ratio for the ejector، three different ejectors، with the mentioned specification، are selected for the combined GAX-ejector and combined single effect-ejector cycles. The performance of these cycles is investigated through changing their evaporator and generator temperatures. Results indicate that، at identical conditions، the COP and second law efficiency of the combined GAX-ejector cycle are around 25% and 16% higher than those of the combined single effect-ejector absorption refrigeration cycle. In addition، it is observed that as the generator temperature increases from 140 oC to170oC، the COP and second law efficiency of combined GAX-ejector cycle are maximized at a particular generator temperature. However، at similar condition، an increase in generator temperature results in a decrease of the COP and second law efficiency of combined single effect-ejector refrigeration cycle.