NRM30 as a possible substitute for R22 in marine vapour compression refrigeration systems

Abstract

The purpose of this paper is to investigate the possibility of using NRM30 in order to replace R22, in existing plants on board the ships. NRM30 is a refrigerant mixture of R134a/R1270/RE170 (55/37.5/7.5 by mass percentage). This approach is based on the better environmental behaviour of NRM30. The comparison between R22 and NMR30 has been developed on the basis of Coefficient of Performance (COP), temperature at compressor exit, power consumption per ton of refrigeration and volumetric refrigeration capacity variations, when evaporation temperature and condensation temperature increase. The above mentioned are calculated when the evaporation temperature varies in the range (-2, +10)° C and the condensation temperature varies in the range (40, 50)° C. The results reveal that COP increases with the increase of the evaporation temperature and the decrease of the condensation temperature- for both refrigerants. Although the ecological refrigerant (NRM30) shows an average COP value lower than the one of R22 (about 30% lower), NRM30 ensures an ecological operation of the plant and lower temperatures at compressor exit- which it is benefic for the long life of this machine. For the considered temperature ranges, the plant operates in efficient conditions for the higher value of the evaporation temperature (+10°C) and for the lowest value of the condensation temperature (40°C). For this conditions, it is seen that the vapours temperatures at the compressor exit are lowest, being ensured also the safe operation of the compressor.