Comparative Exergoeconomic Analysis of Various Transcritical R744 Commercial Refrigeration Systems

The interest in carbon dioxide (R744) as a refrigerant for supermarket applications has been remarkably rising thanks to its favourable thermo-physical, safety and environmental properties. Furthermore, R744 refrigerating plants are still prone to accomplishing large improvements in terms of cost-effectiveness, capability of heat recovery and energy efficiency. The main target of this paper is to compare the final cost of the product of different enhanced CO2 refrigeration supermarket configurations, with a marked emphasis on the one employing a two-phase ejector as an expansion device. The outcomes showed that the use of such technology leads to a drop in the final cost of the product at least by 22.7% over a basic single-stage solution for cooling medium temperatures ranging from 30 °C to 42 °C. The assessment was based on the assumption of three different values of the purchased equipment cost associated with the ejector. The efficiency of the diffuser was observed to influence the costeffectiveness of the system quite substantially. It could be concluded that the higher the heat sink design temperature, the more cost-effective an ejector as a refrigerant expander is.