Apparatus and method for cooling milk by selectively activating a subset of compressors

A milk-cooling apparatus (1) for cooling down milk, comprising:

• a coolant circuit (51) arranged for circulating coolant, the coolant circuit (51) including a milk-cooling heat exchanger (2) configured for heat exchange between milk and the coolant;
• a chiller (4) including a refrigerant circuit (53) with a coolant-cooling heat exchanger (52) configured for heat exchange between a refrigerant and the coolant, and the refrigerant circuit (53) also including two or more compressors (12) arranged for compressing the refrigerant in a cool down process of the refrigerant;
• a first temperature sensing device (7) configured to measure an OUT-temperature indicative of a temperature of the coolant upstream of the milk-cooling heat exchanger (2) and downstream of the coolant-cooling heat exchanger (52);
• a second temperature sensing device (10) configured to measure an IN-temperature of the coolant indicative of the temperature of the coolant upstream of the coolant-cooling heat exchanger (52) and downstream of the milk-cooling heat exchanger (2);
• and
• a control circuitry (5) configured to operate the two or more compressors based on the measured OUT-temperature, in order to minimize a difference between the measured OUT-temperature and the desired OUT-temperature;
• wherein the control circuitry (5) is further configured to control a number of active compressors of the two or more compressors (12) at a given OUT-temperature based on the measured IN-temperature, the number of active compressors (12) being increased in response to an increase of the measured IN-temperature to reach or exceed a first threshold value of temperature.