Comparative study on the energy performance of two different absorption-compression refrigeration cycles driven by low-grade heat

In this paper, performances of an absorption-compression refrigeration cycle with an evaporator-condenser (EC) and a novel absorption-compression cycle with an evaporator-subcooler (ES) are carefully compared and analyzed, which both have energy-saving potential. The comparison is based on three energy performance parameters-the COP of compression subsystem, low-grade heat transforming ratio, and global COP taking into account power cycle efficiency. Comparative investigation is carried out over evaporating temperature (Te) ranging from −20 to 10 °C, generating temperature (Tg) ranging from 90 to 120 °C, and condensing temperature (Tc) ranging from 35 to 45 °C. Based on the analysis of COP of compression subsystem, EC should be adopted when low-grade heat is free and absorption system cost is low. According to the analysis of low-grade heat transforming ratio, ES is recommended when low-grade heat cost much. Based on the analysis of global COP, EC saves more energy at low Te and high Tg, where the global COP of EC is 7.6% and 14.6% higher than that of ES, respectively. However, ES has a good performance at high Te and low Tg, where the global COP of EC is 18.6% and 8.8% higher, respectively. The better cycle is recommended for different working conditions.