Method for operating a refrigeration system with heat pump function for a motor vehicle based on the refrigerant mass flow and refrigeration system with control unit for carrying out the method

A method for operating a refrigeration system with heat pump function for a motor vehicle with at least partially electric drive, wherein the refrigeration system comprises:

• a refrigerant compressor,
• a first heat exchanger, in particular a gas cooler or condenser;
• at least one further heat exchanger, in particular an evaporator and/or a chiller and/or a heating register;
• a sensor device arranged on the low-pressure side upstream of the refrigerant compressor for detecting a first refrigerant pressure and/or a first refrigerant temperature;
• a sensor device arranged on the high-pressure side downstream of the refrigerant compressor for detecting a second refrigerant pressure and/or a second refrigerant temperature, the method comprising the following steps:
• detecting the first refrigerant pressure and/or the first refrigerant temperature;
• detecting the second refrigerant pressure and/or the second refrigerant temperature;
• detecting a speed of the refrigerant compressor;
• determining a refrigerant volumetric efficiency based on the pressure ratio of the first refrigerant pressure and the second refrigerant pressure and the speed of the refrigerant compressor;
• determining a refrigerant mass flow based on the refrigerant volumetric efficiency.