Noticeable technological advances in transcritical R744 (or "CO2 only" or pure CO2) supermarket refrigeration systems have recently occurred. Consequently, the trend towards such technologies has been greatly intensifying, leading these solutions to take root in European commercial refrigeration sector. In this theoretical study, the performance of the present state-of-the-art pure CO2 refrigeration plants was extensively investigated for an average size food retail located in various European climate contexts. The results revealed that, compared to a R404A direct expansion unit, the energy efficiency limit commonly experienced by transcritical R744 refrigerating systems with rise in outdoor temperature disappears with the aid of the multi-ejector concept. Furthermore, depending on the selected solution, the current advanced commercial "CO2 only" configurations feature energy savings ranging from 3% to 37.1% across Europe over a R404A unit. At last, this investigation demonstrates that transcritical R744 ejector supported parallel systems are the most highly efficient and climate friendly technologies for European food retail industry. Moreover, noteworthy energy conservations can also be related to the solution combining parallel (or auxiliary) compression and medium temperature (MT) overfed evaporators.
Gullo, P., Tsamos, K., Hafner, A., Ge, Y., & Tassou, S. A. (2017). State-of-the-art technologies for transcritical R744 refrigeration systems - A theoretical assessment of energy advantages for European food retail industry. In Energy Procedia (Vol. 123, pp. 46–53). Elsevier Ltd. https://doi.org/10.1016/j.egypro.2017.07.283