Comparative thermodynamic analysis of a hybrid refrigeration system for promotion of cleaner technologies

Abstract

This article presents a comparative thermodynamic analysis based on numerical methods for a hybrid refrigeration system suitable to operate as vapour absorption system (VA), vapour compression–absorption system (VCA) and vapour compression system (VC). The working fluid employed for the first two systems is ammonia–water and it is pure ammonia in case of the third system. The system is being powered by waste energy and conventional energy depending on the mode of operation. The effect on performance parameters like COP and exergy efficiency during all modes of operation has been evaluated by keeping the uniform parametric conditions like condenser temperature (40 °C) and evaporator temperature (5 °C) for all the modes of operation. The effect of ambient temperature on the exergy loss in each component of the different modes of operation have also been evaluated and discussed. The results obtained indicate that COP and exergy efficiency for VCA mode initially increases and then decreases whereas for VA and VC mode the COP and exergy efficiency decreases with condenser temperature. The analysis also reveals that with the variation in evaporator temperature the COP and exergy efficiency for VC mode increases whilst for VA and VCA mode the COP shows a slight increase whereas exergy efficiency decreases. The variation of exergy efficiency and exergy loss in different components with condenser and evaporator temperature shows that exergy efficiency is found to be the highest in VC mode whereas the lowest in VCA mode for both the temperature variations. The variation of compressor work and exergy loss in compressors with evaporator and condenser temperature shows that compressor work and exergy loss is lesser for VCA mode when compared to VC mode.