A method for operating a cooling circuit. It is provided that a) the actuation signal ST of the coolant compressor is provided so as to increase over time from a minimum value (ST.sub.min) in order to generate a start-up phase of the coolant compressor, b) a control signal maximum value (ST.sub.max) and a control signal threshold (ST.sub.SW) are provided, where ST.sub.SW<ST.sub.max, c) the actuation signal (ST) is limited to the control signal maximum value (ST.sub.max) if the actuation signal (ST) reaches the control signal threshold (ST.sub.SW) and the measured high and/or low-pressure value (PHD, P.sub.ND) satisfies a condition.

During a first cooling operation, a compressor is in an operational state, a liquid pump is in a non-operational state, and an amount of refrigerant allowing for existence of a liquid surface of the refrigerant in a refrigerant tank is accumulated in the refrigerant tank. During a second cooling operation, the compressor is in the non-operational state, the liquid pump is in the operational state, and the amount of the refrigerant allowing for the liquid surface of the refrigerant in the refrigerant tank is accumulated in the refrigerant tank.

A method for determining system subcooling in a vapor compression system including a compressor, a condenser, an expansion device and an evaporator operatively connected in a serial relationship in a refrigerant flow circuit, the method including receiving information indicative of a compressor torque or compressor current; and determining a degree of system subcooling in response to the receiving of the information.

A refrigeration cycle apparatus is provided with a compressor, a condenser, a pressure-reducing device, and an evaporator. The refrigeration cycle apparatus comprises a refrigeration cycle configured to circulate refrigerant; and a control unit configured to control the refrigeration cycle. The control unit causes the refrigeration cycle to operate when an operation condition is satisfied, the operation condition including elapse of a preset time after the control unit stops the refrigeration cycle. The control unit detects abnormality of the refrigeration cycle based on state data indicating a state of the refrigeration cycle after the control unit causes the refrigeration cycle to operate.

Apparatuses, methods, and systems for adjusting scale(s) of a refrigerant recovery system (RRS) are described. The RRS can determine pressure and weight measurements of content within a refrigerant storage tank. The RRS can determine weight measurements of content within oil storage containers. The RRS can compare the pressure and weight measurements to thresholds to determine whether the scale(s) require adjusting, whether the RRS should be locked to prevent further use of the RRS until after servicing of the RRS, or whether additional functions of an operating state of the RRS should be performed. The RRS can comprise a processor to automatically adjust the scales, determine the pressure and weight measurements, and compare pressure and weight measurements to the thresholds. Locking the RRS can prevent the RRS from recovering refrigerant from a cooling system, such as an air conditioning system in a vehicle.

Provided is a air conditioner including high-and-low-pressure gas pipe expansion valves each of which is provided to a corresponding one of the cooling-heating switching units and adjusts feeding of high-temperature and high-pressure gas refrigerant to the corresponding indoor unit; and a refrigeration cycle controller which adjusts a valve opening degree of the high-and-low-pressure gas pipe expansion valve of the cooling-heating switching unit connected to one of the indoor units which is not in heating operation, in accordance with a determination result on excess or deficiency of refrigerant in a refrigeration cycle.

The various embodiments described herein include methods, devices, and systems for determining refrigerant charge level. In one aspect, a refrigeration system includes: (1) a compressor to compress a refrigerant; (2) a condenser disposed downstream of the compressor to condense the refrigerant; (3) an evaporator disposed downstream of the condenser to vaporize the refrigerant; (4) refrigerant lines fluidly connecting the compressor, the condenser and the evaporator in series to form a refrigerant circuit for circulating the refrigerant; (5) at least one sensor configured to measure temperature and pressure of the refrigerant in the refrigerant circuit; and (6) a controller communicatively coupled to the at least one sensor and configured to: (a) determine a sub-cooling level or super-heating level based on the temperature and/or pressure measured by the at least one sensor; and (b) facilitate operation of the refrigeration system based on the sub-cooling level or the super-heating level.

A heating, ventilation, and air conditioning system may include a refrigerant loop to circulate refrigerant, a first valve, a second valve, a sensor to measure parameters of the refrigerant, a refrigerant tank fluidly coupled to the refrigerant loop via the valves, and control circuitry communicatively coupled to the sensor, the first valve, and the second valve. The control circuitry may determine environmental conditions and detect whether an undercharge or overcharge condition is present in the refrigerant loop based at least in part on the environmental conditions and the measured parameters. The control circuitry may also instruct the first valve to open when the undercharge condition is detected to facilitate flowing refrigerant from the refrigerant tank into the refrigerant loop and instruct the second valve to open when the overcharge condition is detected to facilitate flowing refrigerant from the refrigerant loop into the refrigerant tank.

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.

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.