A refrigeration system includes an evaporator configured to receive a flow of refrigerant and transfer heat into the refrigerant within the evaporator to provide cooling for a temperature-controlled space, an expansion valve operable to modulate the flow of refrigerant into the evaporator, a liquid level sensor configured to measure a level of liquid accumulated within a component of the refrigeration system, and a controller configured to operate the expansion valve to increase the flow of refrigerant into the evaporator or decrease the flow of refrigerant into the evaporator based on the level of liquid measured by the liquid level sensor.

A refrigeration system includes an evaporator configured to receive a flow of refrigerant and transfer heat into the refrigerant within the evaporator to provide cooling for a temperature-controlled space, an expansion valve operable to modulate the flow of refrigerant into the evaporator, a liquid level sensor configured to measure a level of liquid accumulated within a component of the refrigeration system, and a controller configured to operate the expansion valve to increase the flow of refrigerant into the evaporator or decrease the flow of refrigerant into the evaporator based on the level of liquid measured by the liquid level sensor.

A vehicle air-conditioning device includes a compressor, a heating unit, an outside air heat exchanger, a wind speed regulation unit, and a controller. The heating unit includes a heating heat exchanger and heats ventilation air supplied to a space to be air conditioned using a high-pressure refrigerant as a heat source. The wind speed regulation unit regulates a wind speed of air supplied to the outside air heat exchanger. The control unit performs, as a defrosting operation of defrosting the outside air heat exchanger, a dry defrosting mode for evaporating and removing frost adhering to the outside air heat exchanger in a state where the outside air is at a low temperature. In the dry defrosting mode, the controller causes the wind speed regulation unit to supply air to the outside air heat exchanger at a wind speed in a range determined to promote evaporation and removal of frost.

A vehicle air conditioner includes a compressor, a heating unit, an outside air heat exchanger, a wind speed regulation unit, and a controller. The controller includes a melting control unit, a dry control unit, and a dry completion determination unit. In a dry defrosting mode, the melting control unit performs melting-defrosting to melt frost adhering to the outside air heat exchanger. The dry control unit performs a dry defrosting in which at least one of the amount of heat in a predetermined range or a wind speed regulated in a predetermined range by the wind speed regulation unit is supplied to residual water adhering to the outside air heat exchanger, due to melting of frost in the melting-defrosting, to dry the residual water. The dry completion determination unit determines whether drying of the residual water in the outside air heat exchanger is completed, in the dry defrosting.

An air-conditioning apparatus includes a four-way valve, a first three-way valve and a second three-way valve each having a closed port, a compressor, an indoor heat exchanger, an expansion valve, a first outdoor heat exchanger, a second outdoor heat exchanger, a bypass expansion valve, a check valve, a discharge temperature sensor, an indoor pipe temperature sensor, an indoor temperature sensor, a current sensor, and a controller configured to detect switching failure at the four-way valve, the first three-way valve, and the second three-way valve. The controller is configured to detect switching failure at the four-way valve, the first three-way valve, or the second three-way valve by using the temperatures measured by the discharge temperature sensor, the indoor pipe temperature sensor, and the indoor temperature sensor and the current in consideration of an operation status.

An air-conditioning apparatus includes a four-way valve, a first three-way valve and a second three-way valve each having a closed port, a compressor, an indoor heat exchanger, an expansion valve, a first outdoor heat exchanger, a second outdoor heat exchanger, a bypass expansion valve, a check valve, a discharge temperature sensor, an indoor pipe temperature sensor, an indoor temperature sensor, a current sensor, and a controller configured to detect switching failure at the four-way valve, the first three-way valve, and the second three-way valve. The controller is configured to detect switching failure at the four-way valve, the first three-way valve, or the second three-way valve by using the temperatures measured by the discharge temperature sensor, the indoor pipe temperature sensor, and the indoor temperature sensor and the current in consideration of an operation status.

A refrigeration cycle apparatus includes an indoor heat exchanger, a water heat exchanger, a pump, an outdoor heat exchanger, a compressor, an expansion valve, a four-way valve, a third pipe, and an open/close valve, and configured to enable hot-gas defrosting and reverse cycle defrosting. A controller selects, based on the indoor load, either one of the hot-gas defrosting and the reverse cycle defrosting to be performed. In this way, defrosting can be performed with a minimum decrease of the chiller water temperature.

A refrigeration cycle apparatus includes an indoor heat exchanger, a water heat exchanger, a pump, an outdoor heat exchanger, a compressor, an expansion valve, a four-way valve, a third pipe, and an open/close valve, and configured to enable hot-gas defrosting and reverse cycle defrosting. A controller selects, based on the indoor load, either one of the hot-gas defrosting and the reverse cycle defrosting to be performed. In this way, defrosting can be performed with a minimum decrease of the chiller water temperature.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.

An air-conditioning apparatus includes an outdoor heat exchanger. The outdoor heat exchanger includes a first heat exchanger and a second heat exchanger. A controller performs a heating operation and a heating-defrosting operation, in which one of the first heat exchanger and the second heat exchanger functions as an evaporator, an other one the first heat exchanger and the second heat exchanger functions as a condenser. When a temperature of the indoor heat exchanger by a temperature detection unit is treated as a first temperature, and a temperature of the indoor heat exchanger by the temperature detection unit is treated as a second temperature, the controller reduces a rotation speed of an indoor fan in a case where the second temperature is lower than the first temperature and where a difference between the first temperature and the second temperature is greater than or equal to a first setting value.