Advanced exergetic analysis for design optimization of a CO2 refrigeration system using parallel compression

CO₂ is the most environmentally friendly alternative for the upcoming future industry of refrigerants. However, low Coefficient of Performance (COP) values result from its need to work under transcritical conditions. This disadvantage is being overcome by different modifications to the classical refrigeration system. The modification that has increased COP value the most, according to the latest literature, is parallel compression. The objective of this work is to find the component of a parallel compression refrigeration system that has the highest exergy losses and evaluate its potential modifications. The experimental data to validate this model are available in the literature. For this study an advanced exergetic analysis is proposed operating at ambient temperatures within the range of -5 to 40°C. The mathematical model solution was obtained using the software Engineering Equation Solver (EES). The results concluded that a high-pressure compressor is the one with the most avoidable endogenous exergy and gas cooler (or condenser) is the one with the most avoidable exogenous exergy.