Energetic and economic analysis of trans-critical CO2 booster system for refrigeration in warm climatic condition

The performance of five CO2 booster refrigeration systems is analysed and compared in this paper for supermarket application. The investigated configurations include a standard booster system, abbreviated as BC1, a booster system with parallel compressor (BC2), a booster system with flooded low temperature evaporator (BC3), a booster system with work recovery expander (BC4) and a booster with parallel compressor along with flooded low temperature evaporator and work recovery expander (BC5). Annual hourly averaged temperature variations at four prominent cities across the world are taken as case study. Simulation indicates advantage of the proposed system BC5 over BC1 configuration. Work recovery unit is found to have the highest potential in the annual energy savings in BC5, followed by parallel compressor and flooded evaporator. The maximum annual energy savings is found to be 22.16% for BC5 in New Delhi. Economic analysis reveals recovery time of less than four years for the additional investment made in BC5. The slope of recovery time is found steeper at lower tariff compared to that at higher tariff.