Comparative analysis on the energy use and environmental impact of different refrigeration systems for frozen food supermarket application

In this paper the impact on the store's energy use by different refrigeration systems, remote and centralised, is investigated as well as their environmental impact. The study is performed using the energy simulation program EnergyPlus in a reference baseline model which has been verified against measured energy and environmental conditions data. The refrigeration system of the case study includes plugged-in display cabinets to serve both medium temperature (MT) and low temperature (LT) refrigeration loads. Centralised systems are compared with the remote plugged-in refrigeration cabinets. The different refrigeration systems studied are, a) two parallel centralised systems for MT and LT loads, b) two parallel cascade systems (R134a/CO2) for MT and LT loads and c) a transcritical CO2 booster. The study is performed for DSY London weather file to capture the risk of warmer than a typical year consequences in centralised refrigeration systems operation. Besides these refrigeration systems, the CO2 transcritical appears as the one of the most promising replacement in terms not only of energy use reduction due to its high efficiency in London climate but on its low contribution to global warming as well.