A method and a correspondingly designed device are provided for controlling or regulating a coolant circuit of an air conditioning system, which includes at least one compressor, at least one condenser or gas cooler, and at least one evaporator. A controllable coolant expansion device is connected to the coolant inlet of the evaporator. It is detected when the coolant circuit is under filled with a coolant and, when an under filling of the coolant is detected, the control strategy of the expansion device is changed.

A refrigerant amount determining device includes: an operation data acquiring unit configured to acquire operation data of an air conditioning system; a calculating unit configured to calculate a refrigerant amount index value from the operation data acquired; an inferring unit configured to infer information regarding correction of the refrigerant amount index value using a correction model and at least one of the acquired operation data or the calculated refrigerant amount index value; and a determining unit configured to determine a refrigerant amount of the air conditioning system based on the information regarding correction of the refrigerant amount index value.

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air downstream of the indoor heat exchanger. The processor may be in communication with the return-air temperature sensor and the supply-air temperature sensor. The processor may be programmed to determine a working-fluid-charge condition of the heat-pump system based on the first and second air temperatures.

A dynamic receiver is included in parallel to an expander of a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The dynamic receiver allows control of the refrigerant charge of the HVACR system to respond to different operating conditions. The dynamic receiver can be filled or emptied in response to the subcooling observed in the HVACR system compared to desired subcooling for various operating modes. The HVACR system can include a line directly conveying working fluid from compressor discharge to the dynamic receiver to allow emptying of the dynamic receiver to be assisted by injection of the compressor discharge.

An air-conditioning device including multiple outdoor units and an indoor unit through a pipe includes a control section that obtains a degree of subcooling at an outlet of a subcooling circuit of each outdoor unit based on a temperature detected by a temperature sensor that detects the temperature of refrigerant having passed through the subcooling circuit of each outdoor unit, obtain a target value of the degree of subcooling based on the obtained multiple degrees of subcooling, and perform the control of increasing the rotation speed of a compressor of an outdoor unit having a higher degree of subcooling than the target value and decreasing the rotation speed of a compressor of an outdoor unit having a lower degree of subcooling than the target value such that a difference in the degree of subcooling at the outlet of the subcooling circuit of each outdoor unit is decreased.

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 dynamic refrigeration system may automatically, at pre-determined time periods on-the-fly, adjust a refrigerant system's refrigerant pressures to predetermined optimal efficiency pressures as the internal and external heat loads change over a range. This may result in the refrigerant system pressures closely operating within a range of predetermined optimal efficiency pressures. This system may automatically instantaneously fine tune and balance on all air conditioning, heat pump, and refrigeration systems as the internal and external heat loads are continuously changing dynamically. The system may include a small liquid refrigerant pump and refrigerant storage tank, one or more wired or wireless pressure transducers and temperature sensors, and a “brain” to make decisions to keep the system instantaneously set at factory specs all the time. The system may include a wireless communication means so it can instantaneously report its operating condition, loads, and cost of operating.

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 performance degradation diagnosis system includes a determining unit, and control unit. A refrigeration cycle apparatus includes a refrigerant circuit having a compressor, heat-source-side heat exchanger, and use-side heat exchanger. The determining unit determines, based on an index indicating an operation state of the refrigeration cycle apparatus, performance degradation of the refrigeration cycle apparatus with respect to each of a plurality of performance degradation factors. In a case in which the determining unit determines performance degradation, the control unit grasps an operation condition of the refrigeration cycle apparatus which is operating. In a case in which the operation condition of the refrigeration cycle apparatus is not suitable to determine performance degradation with respect to a performance degradation factor of a determination target, the control unit controls the operation condition of the refrigeration cycle apparatus so that the operation condition of the refrigeration cycle apparatus becomes an appropriate operation condition.

A refrigeration apparatus (1) includes a heat-source-side unit (10) using a refrigerant that works in a supercritical region. The heat-source-side unit (10) includes a compression element (20) configured to compress the refrigerant, a heat-source-side heat exchanger (24), an expansion valve (26) provided downstream of the heat-source-side heat exchanger (24), a receiver (25) provided downstream of the expansion valve (26), and a control unit (101). The control unit (101) performs a first operation for evaluating the amount of the refrigerant based on a high-pressure-side pressure, on a first condition that the internal pressure of the receiver (25) be equal to or less than a supercritical pressure.