Optimal ammonia water absorption refrigeration cycle with maximum internal heat recovery derived from pinch technology

摘要

Absorption refrigeration technology has attracted more and more interests due to its advantages such as making good use of low grade thermal energy and using environmental friendly refrigerants. The internal heat recovery capacity of an ammonia water absorption refrigeration system has significant influence on the system performance. According to cascaded utilization of energy to reduce the internal irreversible loss, this paper presents the optimal cycle with maximum internal heat recovery which is derived from a comprehensive method of pinch technology. The derivation of the optimal cycle is introduced. The internal integration is clearly shown in a temperature-heat load diagram. The optimal cycle derived from this method when there is a temperature overlap between the absorption and generation processes is exactly the GAX cycle. Performance analysis is carried out to discuss the performance improvement of the optimal cycle. The results show that the performance of the optimal cycle is enhanced significantly by 20% at least compared with a traditional one under common operating conditions. The performance improvement of the optimal cycle is more significant at a lower evaporation temperature and a higher generation temperature while it has a maximal value with the coolant temperature increasing.