Study of the Performance of a New Absorption Refrigeration System Incorporating Two Ejectors

摘要

This work presents a theoretical analysis of a new absorption refrigeration cycle incorporating two ejectors. Three mixtures were used in this study: NH_3-H_2O, NH_3-NaSCN and NH_3-IJNO_3. The idea of this new cycle is to combine two ejector absorption cycles in a single cycle. The first ejector absorption cycle contains an ejector "ej1" in place of the solution expander. The second cycle contains an ejector "ej2" between the generator, the condenser and the evaporator. By comparing these two cycles with the single effect cycles, several researches have found that the first cycle makes it possible to operate at lower temperatures at the generator. While the second cycle provides a good improvement in the coefficient of performance "COP," however, higher temperatures at the generator are required. The results showed that the new cycle made it possible to combine the desired effects of these two cycles. Indeed, a remarkable increase in the coefficient of performance of this cycle compared to that of the single effect cycle is seen for all three mixtures, it is the effect of the ejector "ej2." It has also been noticed that the use of the ejector "ej1" made it possible to operate at lower generator temperatures than when the ejector "ej2" is used alone. In addition, the cycle performance with two ejectors at elevated temperatures at the condenser and absorber and at low evaporator temperatures is considerably improved over those of the single effect cycle. The results also showed that the NH_3-LiNO_3 mixture provides the best performance at low temperatures at the generator and evaporator and at high temperatures at the condenser and absorber.