A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a first portion of a refrigeration system within a building; and an isolation module configured to selectively open and close an isolation valve of the refrigeration system and to, via the isolation valve, maintain the amount of refrigerant within the first portion within the building below a predetermined amount of the refrigerant.

A cold source unit is connectable to an indoor heat exchanger and is provided for a refrigerant circuit. The cold source unit includes: a compressor; an outdoor heat exchanger having a gas header; an oil return path through which refrigeration oil is returned from the gas header to the compressor; an oil return adjusting unit configured to adjust a flow rate of refrigeration oil flowing through the oil return path; and a controller configured to control the refrigerant circuit. The controller is configured to control the oil return adjusting unit to prevent refrigeration oil from flowing through the oil return path when the compressor is driven at a frequency equal to or higher than a threshold value, and control the oil return adjusting unit to allow the refrigeration oil to flow through the oil return path when the compressor is driven at a frequency lower than the threshold value.

A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a refrigeration system of a building; a leak module configured to diagnose that a leak is present in the refrigeration system based on the amount of refrigerant; and at least one module configured to take at least one remedial action in response to the diagnosis that the leak is present in the refrigeration system.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device that connects the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor device and the heat exchanger.

A heat source controller performs a first operation when a compression element is in a stopped state and a pressure in a receiver exceeds a predetermined first pressure. The heat source controller allows an inlet of the compression element to communicate with the receiver, and drives the compression element in the first operation.

A refrigerant circuit has a liquid passage that allows a receiver to communicate with a utilization heat exchanger, and a first expansion valve provided in the liquid passage. The controller opens the first expansion valve when the compression element is in the stopped state and a pressure in the receiver exceeds a predetermined first pressure.

No studies have been made regarding what kinds of refrigerants should be used in a refrigeration cycle device for a vehicle. An air conditioner (1) for a vehicle includes a refrigerant circuit (10) and a refrigerant that is sealed in the refrigerant circuit (10). The refrigerant circuit (10) includes a compressor (80), a first heat exchanger (85), which serves as a heat dissipater in a dehumidifying heating mode, an outside-air heat exchanger (82), a cooling control valve (87), and a second heat exchanger (86), which serves as an evaporator in the dehumidifying heating mode. The refrigerant is a refrigerant having a low GWP.

Embodiments relate generally to subcooling control of a heating, ventilation, and air conditioning (HVAC) system. An HVAC system may include a first electronic expansion valve (EEV) fluidly coupled to an indoor coil, wherein the first EEV is adjacent to the indoor coil. The HVAC system may also include a second EEV fluidly coupled to an outdoor coil, wherein the second EEV is adjacent to the outdoor coil. A system controller may be configured to control the first and second EEVs to control a flow of refrigerant to control subcooling (SC) produced by the HVAC system. The second EEV remains open during a cooling mode, and the first EEV modulates during the cooling mode. The second EEV modulates during a heating mode, and the first EEV remains open during the heating mode.

A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a refrigeration system of a building; a leak module configured to diagnose that a leak is present in the refrigeration system based on the amount of refrigerant; and at least one module configured to take at least one remedial action in response to the diagnosis that the leak is present in the refrigeration system.

A method for air-conditioning of watercraft and the like using a device with: an electronically controlled variable-r.p.m. compressor, a main gas/water condenser (5), at least one environmental heat-exchanger (3) with an electronically controlled fan (14), at least one electronically controlled expansion valve (8), and at least one first electronic control unit (4) programmed for calculating continuously a temperature deviation detected (DeltaT=T_ad−T_a), and as a function of said temperature deviation regulating in combination, the r.p.m. of the compressor (1), opening of the flow valve (8), and the r.p.m. of the fan of the heat-exchanger (3).