Energy and advanced exergoeconomic analysis of a novel ejector-based CO2 refrigeration system and its optimization for supermarket application in warm climates

Abstract

Supermarkets' high refrigeration and air-conditioning energy use increases their carbon footprint. Thus, this sector must be encouraged to innovate to increase efficiency, reduce emissions, and support UN Sustainable Development Goals 11 and 13. In this study, we present a novel dual-ejector based CO2 refrigeration configuration. Real component data from manufacturers are utilised to make the theoretical evidence proximate to a controlled experiment. Mathematical model of the ejector is validated using published experimental data with a maximum deviation of 9.23%. Energetic performance of the proposed system is contrasted with a dedicated mechanical subcooling based CO2 system (DMS) and is found to be superior by 41.97% to 35.38% for operation within ambient temperature 28 °C − 40 °C. The year-round performance of the proposed system for various warm ambient locations in India, UAE and Spain is evaluated. Compared to a conventional R404A direct expansion system, a substantial annual energy savings, upto 11.35% is observed. Advanced exergy and exergoeconomic analysis, carried out at 40 °C ambient, provides an estimate of the limits up to which the irreversibilities and associated costs can be avoided for high ambient operation. The high-stage compressor in the configuration is found to have the highest potential of reducing the irreversibility by 36.08% and cost rate by 23.24%. Extent of mutual interactions among various components are also investigated using mexogenous analysis. A multi-objective optimization using genetic algorithm is employed to optimize exergoeconomic performance. The exergetic performance of the optimized system is found to be 6% higher than DMS system.