Comparison of an absorption-compression hybrid refrigeration system and the conventional absorption refrigeration system: Exergy analysis

Abstract

This paper presents an exergy analysis considering different operating conditions of an alternative configuration of an ammonia-water hybrid absorption refrigeration system, where part of condensation heat is recovered and supplied to generator (RCHG-ARS). In order to identify and quantify the irreversibilities in each component of the cycle and its variations, the exergy efficiency and the relative exergy loss of the system were evaluated. Moreover, the results obtained were compared with those obtained by the conventional ARS cycle. Furthermore, the effect of the internal heat exchanger effectiveness on the exergy efficiency and relative exergy loss was analyzed. The results indicate that the generation temperature and the exergy efficiency of the RCHG-ARS cycle decrease in 24 °C and 30%, respectively, it in comparison to ARS cycle at the conventional generation pressure (11.67 bar). However, to decrease the generator pressure at 5.94 bar, the evaporation temperature for the RCHG-ARS decreases in 19.3 °C and the exergy efficiency can be 0.20% higher than the obtained with the ARS cycle. It is also revealed that the exergy efficiency for the RCHG-ARS cycle become more significant at lower condensing and evaporating temperatures as well as lower generator pressures and higher internal heat exchanger effectiveness respect to ARS cycle. Moreover, the minimum values of relative exergy losses are obtained at higher generator temperatures or lower evaporating and condensing temperatures in the RCHG-ARS cycle. Finally, it can be concluded that the main components that increase the relative exergy destruction in the RCHG-ARS cycle are the generator, absorber and the compressors.