Thermodynamic performance analysis of the double effect absorption-vapour compression cascade refrigeration cycle

Abstract

Absorption refrigeration cycles, the developed as an alternative to vapour-compression refrigeration cycles they are not effective at low temperatures. When the absorption and vapour compression cycles are combined as cascade the consumed compressor work can be reduced considerably, but it requires the use of heat energy at low temperature (solar energy, geothermal energy, waste heat). In this study, the absorption part has been designed to improve the performance of absorption-vapour compression cascade cycle as serial flow double effect. The detailed thermodynamic analysis has been made of the double effect absorption-vapour compression cascade refrigeration cycle. For the novel cycle working fluid used R-134a for vapour compression section and LiBr-H2O for absorption section. This cycle has been compared with single effect absorption-vapour compression cascade cycle and one stage vapour compression refrigeration cycle. The results indicate that the electrical energy consumption in the novel cycle is 73% lower than the one stage vapour compression refrigeration cycle. Also, the thermal energy consumption in the cascade cycle is 38% lower than the single effect absorption-vapour compression cascade refrigeration cycle. It is found that the the minimum and maximum exergy efficiency occurs in the cooling set and the low pressure generator (LPG) as 21.85% and 99.58%, respectively.

Keywords

• thermodynamic
• double effect absorption
• vapour compression
• cascade
• performance