A leakage monitoring method in a refrigeration system based on a theoretical model of refrigerant charge is proposed. In this method

a theoretical model based on a temperature signal is developed

and the refrigerant mass in each component of the refrigeration system can be calculated and the leakage in the refrigeration system can be monitored. For the theoretical model of refrigerant charge

a division criterion of control volumes and governing equation of the phase zone are established using the multi-zone method for the heat exchanger. A temperature-based calculation model of refrigerant mass in the heat exchanger is developed; the refrigerant mass models for the compressor and the connecting pipe are developed by establishing theory-based explicit equations. The validation results show that the maximum deviation is 3.18%.