Abstract: An air conditioning system, which is a refrigeration apparatus that performs a refrigeration cycle in a refrigerant circuit, includes an outdoor heat exchanger, an indoor heat exchanger, a first control valve, a second control valve, a third control valve, and a pressure adjusting portion. The first control valve and the second control valve, which block flow of refrigerant when fully closed, are disposed in a gas-side refrigerant flow path. The gas-side refrigerant flow path is disposed between the outdoor heat exchanger and the indoor heat exchanger. The third control valve, which blocks flow of refrigerant when fully closed, is disposed in a liquid-side refrigerant flow path. The liquid-side refrigerant flow path is disposed between the outdoor heat exchanger and the indoor heat exchanger. The pressure adjusting portion adjusts the pressure of refrigerant in an indoor-side refrigerant flow path.

Abstract: Noise that is generated from an indoor unit is suppressed when performing two-phase transport of refrigerant by using a liquid-pressure-adjusting expansion valve in an air conditioner including an outdoor unit, a plurality of indoor units each including an indoor heat exchanger, a relay unit that switches the plurality of indoor heat exchangers so that the indoor heat exchangers individually function as an evaporator or radiator for refrigerant, and a liquid-refrigerant connection pipe and a gas-refrigerant connection pipe that connect the outdoor unit and the indoor unit via the relay unit. The relay unit includes a relay expansion valve that further decompresses the refrigerant that has been decompressed by the liquid-pressure-adjusting expansion valve.

Abstract: A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.

Abstract: A controller of an air conditioning apparatus performs a start/stop frequency-reducing rotation speed control in which the rotation speed of a compressor is controlled based on request values from indoor units requesting a decrease in air conditioning capacity, disregarding request values from indoor units requesting an increase in air conditioning capacity, when each indoor temperature at all indoor units performing air conditioning operation is within a scope of a prescribed threshold temperature range surrounding a target indoor temperature at each indoor unit performing air conditioning operation.

Abstract: A controller of an air conditioning apparatus performs a start/stop frequency-reducing rotation speed control in which the rotation speed of a compressor is controlled based on request values from indoor units requesting a decrease in air conditioning capacity, disregarding request values from indoor units requesting an increase in air conditioning capacity, when each indoor temperature at all indoor units performing air conditioning operation is within a scope of a prescribed threshold temperature range surrounding a target indoor temperature at each indoor unit performing air conditioning operation.

Abstract: In an air conditioning device (10) to which an outdoor unit (20) and indoor units (40) are connected, when a flow rate of a gaseous refrigerant in a gas main pipe (72a) is lower than a lower limit flow rate in main pipe, an amount of refrigerating machine oil accumulated in the gas main pipe (72a) is calculated. When gas branch pipes (72b) include a gas branch pipe (72b) having a flow rate lower than a lower limit flow rate in branch pipe even though the flow rate of the gaseous refrigerant in the gas main pipe (72a) is higher than the lower limit flow rate in main pipe, an amount of the machine oil accumulated in the gas branch pipe (72b) is calculated. When the amounts are integrated and the integrated value exceeds a set amount, oil collecting operation is performed.

Abstract: A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.