Learning device and inference device for state of air conditioning system

A learning device that learns a state of an air conditioning system in which refrigerant circulates, wherein

• the air conditioning system includes an outdoor unit and at least one indoor unit,
• the outdoor unit includes a compressor, a first heat exchanger, and a blower configured to blow air to the first heat exchanger,
• the at least one indoor unit includes an expansion valve and a second heat exchanger,
• the refrigerant circulates in order of the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger, or circulates in order of the compressor, the second heat exchanger, the expansion valve, and the first heat exchanger,
• the learning device comprises circuitry configured to:
• acquire operation data of the air conditioning system;
• and
• convert a specific model into a trained model by using the operation data,
• wherein the operation data includes a specific parameter and at least one of a temperature of air passing through the second heat exchanger, a temperature and a pressure of the refrigerant, a temperature outside a space where each of the at least one indoor unit is arranged, and at least one of a current value and a voltage value of an inverter of the compressor, a temperature of a heat sink included in the outdoor unit, and a temperature of a liquid pipe that connects the outdoor unit and each of the at least one indoor unit,
• the specific model estimates the specific parameter from the operation data other than the specific parameter, and
• the specific parameter includes at least one of a degree of opening of the expansion valve and an amount of air blown per unit time by the blower.