A refrigeration system includes a free cooling system having an air-cooled heat exchanger, where the air-cooled heat exchanger includes a fan configured to move air over coils of the air-cooled heat exchanger to remove heat from a coolant flowing through the air-cooled heat exchanger, and a mechanical cooling system with a refrigerant loop that includes an evaporator, a compressor, and a condenser disposed along the refrigerant loop, where the compressor is configured to circulate a refrigerant through the refrigerant loop, and wherein the evaporator is configured to receive the coolant and transfer heat from the coolant to the refrigerant. The refrigeration system also includes a controller configured to adjust a fan speed of the fan up to a threshold fan speed, to initiate operation of the compressor when the fan speed reaches the threshold fan speed, wherein the fan speed and a compressor speed of the compressor are based at least on an ambient air temperature and a cooling load demand.

In a case of a heating operation in which the use side heat exchanger functions as a condenser when an outside temperature is a predetermined low temperature, a low-outside-temperature heating operation start-up mode in which, while a refrigerant discharged from the compressor is caused to flow into the use side heat exchanger, a refrigerant is supplied to the injection port of the compressor via the injection pipe and part of the refrigerant that has transferred heat in the heat source side heat exchanger is supplied to the compressor, is followed by a low-outside-temperature heating operation mode in which the refrigerant discharged from the compressor is supplied to the injection port of the compressor via the injection pipe while the refrigerant being caused to flow into the use side heat exchanger.

An air conditioning apparatus includes, a first heat exchanger, a second heat exchanger configured to exchange heat between a first heat medium and a second heat medium, flow rate control valves, and a pump. In a heating mode, a controller is configured to open the flow rate control valve corresponding to a heat exchanger, of the third heat exchangers, to which a request for air conditioning has been made, and to close the flow rate control valve(s) corresponding to a heat exchanger(s), of the third heat exchangers, to which the request for air conditioning has not been made. In a defrosting mode, when a temperature of the second heat medium is lower than a first determination temperature, the controller is configured to open at least one of the flow rate control valve(s) corresponding to the heat exchanger(s) to which the request for air conditioning has not been made.

Heat pump system (100) comprising at least one heat medium circuit (210,220,230,240,250,310,320,410,420,430,440,450,460) in turn comprising a compressor (211), an expansion valve (232,242), at least two different primary heat sources or sinks selected from outdoor air, a water body, the ground or exhaust air, at least one of two different secondary heat sources or sinks selected from indoors air, pool water and tap water, a respective temperature sensor (412,432) at each of said primary heat sources or sinks, a valve means (421,431,451) for selectively directing the primary-side heat medium to at least one of said primary heat exchanging means, and a control means (500). The invention is characterised in that, in a secondary-side heating operating mode, the temperature of said primary heat sources or sinksis measured, and in that the primary-side heat medium is directed only to the primary heat exchanging means associated with the heat sources or sinks with the highest temperature. The invention also relates to a method.

A refrigeration cycle apparatus includes a refrigerant circuit, by pipes, connecting a compressor, a flow switching device, a first heat exchanger, an expansion device, and a second heat exchanger. As refrigerant to be circulated through the refrigerant circuit, any one of a refrigerant having saturated gas temperature under standard atmospheric pressure that is higher than that of R32 and a refrigerant mixture mainly composed of the refrigerant is used. The refrigerant circuit includes an internal heat exchanger configured to exchange heat between the refrigerant flowing through a refrigerant-inlet side of the second heat exchanger and the refrigerant flowing through a refrigerant-outlet side of the second heat exchanger.

A refrigerant condition detection device (40A) according to an embodiment includes: a temperature information acquisition unit (41) that acquires a temperature of a refrigerant flowing out from the condenser of a refrigeration circuit having a compressor, the condenser, an expansion valve, and an evaporator, and also acquires a temperature of a cooling fluid before it cools the refrigerant in the condenser; and a refrigerant condition determination unit (42) that determines that a leakage or shortage of the refrigerant occurs, when a difference between the temperature of the refrigerant and the temperature of the cooing fluid, which are acquired by the temperature information acquisition unit (41), exceeds a threshold value previously recorded.

A refrigerant leakage determination system capable of detecting leakage of refrigerant without requiring complicated processing is provided. A refrigerant leakage determination system is a refrigerant leakage determination system of a refrigeration cycle apparatus that includes a refrigerant circuit including a heat-source-side heat exchanger and has, as operating modes, a normal mode in which the heat-source-side heat exchanger is caused to function as an evaporator and a defrosting mode in which the heat-source-side heat exchanger frosted during a normal operation is defrosted. The refrigerant leakage determination system includes a processor configured to acquire defrosting information regarding a relationship between a normal operation period and the number of defrosting operations, and memory that stores the defrosting information. The processor is further configured to determine, based on the acquired defrosting information, leakage of refrigerant in the refrigerant circuit.

The determination of the refrigerant amount is facilitated. A refrigerant amount inference apparatus infers a refrigerant amount in an air conditioner in which a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a pressure reducing valve, and a use side heat exchanger are connected to piping. The supercooling heat exchanger is a heat exchanger that exchanges heat between refrigerant that passes through a supercooling bypass expansion valve provided in a bypass circuit and refrigerant in a mainstream circuit. The bypass circuit is connected to piping on a suction side of the compressor from a position between the heat source side heat exchanger and the supercooling heat exchanger or a position between the pressure reducing valve and the supercooling heat exchanger. The refrigerant amount inference apparatus includes an acquiring unit configured to acquire a state of refrigerant in first piping provided between the pressure reducing valve and the supercooling heat exchanger and an operation amount related to the state of the refrigerant in the first piping, and a training unit configured to perform training by associating the state of the refrigerant in the first piping and the operation amount related to the state of the refrigerant in the first piping with a refrigerant amount.

Systems and methods for controlled subcooling of working fluid in a heating, ventilation, air conditioning and refrigeration (HVACR) system through a suction line heat exchanger are disclosed. The suction line heat exchanger may receive a first fluid flow travelling to a suction of the compressor in the HVACR system and second flow of working fluid that is travelling from a heat exchanger receiving the discharge of the compressor to an expansion device. Superheating of the first working fluid may be determined based on temperature measurements prior to and following the suction line heat exchanger. The superheating may be used to control the quantity of the second flow of working fluid introduced into the suction line heat exchanger, for example to maintain superheat that is below a threshold value. These systems may include chillers and heat pump systems, and methods may be applied to chillers or heat pump systems.

This refrigeration device comprises: a high temperature side refrigerant circuit in which a high temperature side refrigerant circulates; a low temperature side refrigerant circuit in which a low temperature side refrigerant circulates; and a cascade heat exchanger that cools the low temperature side refrigerant with the high temperature side refrigerant. In the low temperature side refrigerant circuit, a low temperature side decompressor is disposed downstream of the cascade heat exchanger and a temperature sensor is installed in a piping portion between the cascade heat exchanger and the low temperature side decompressor.