On board chiller capacity calculation

A method of controlling operation an air conditioning system including two or more chillers, comprising:

• measuring a first compressor speed of a first compressor of a first chiller of the two or more chillers of the air conditioning system, the first chiller including:
• the first compressor;
• a first condenser operably connected to the first compressor;
• and
• a first evaporator operably connected to the first compressor and the first condenser, a first flow of refrigerant circulating through the first compressor, first condenser and first evaporator, and exchanging thermal energy with a heat transfer fluid at the first evaporator;
• measuring a second compressor speed of a second compressor of a second chiller of the two or more chillers of the air conditioning system, the second chiller including:
• the second compressor;
• a second condenser operably connected to the second compressor;
• and
• a second evaporator operably connected to the second compressor and the second condenser, a second flow of refrigerant circulating through the second compressor, second condenser and second evaporator, and exchanging thermal energy with the heat transfer fluid at the second evaporator;
• measuring a first refrigerant pressure of the first flow of refrigerant at the first evaporator of the first chiller of the two or more chillers of the air conditioning system;
• measuring a second refrigerant pressure of the second flow of refrigerant at the second evaporator of the second chiller of the two or more chillers of the air conditioning system;
• calculating a first chiller load of the first chiller using the first compressor speed and the first refrigerant pressure;
• calculating a second chiller load of the second chiller using the second compressor speed and the second refrigerant pressure;
• and
• making operational changes to one or more of the first chiller and the second chiller in response to the calculated respective first chiller load and second chiller load;
• wherein the first chiller is connected to the second chiller and to a common heat exchanger in a serial relationship via the heat transfer fluid to circulate the heat transfer fluid through the common heat exchanger;
• and
• selectably stopping the flow of heat transfer fluid through one or more of the first chiller or second chiller via operation of one or more valves at the first chiller or second chiller.