The refrigerant device includes a refrigerant circuit, an injection circuit, an inlet temperature sensor, an outlet temperature sensor, and a controller configured to control the operation of the refrigerant circuit. The controller includes an evaluation value calculation unit and a refrigerant amount detection unit. The evaluation value calculation unit calculates an evaluation value indicating a capability of a subcooling heat exchanger in accordance with an inlet temperature detected by the inlet temperature sensor and an outlet temperature detected by the outlet temperature sensor. The refrigerant amount detection unit determines whether there is a shortage of refrigerant in accordance with the evaluation value calculated by the evaluation value calculation unit.

A refrigeration system includes a subcooler configured to provide subcooling for a liquid refrigerant flowing through a first side of the subcooler by transferring heat from the liquid refrigerant to a gas refrigerant flowing through a second side of the subcooler. An expansion valve is located at an inlet of the second side of the subcooler and configured to control a flow of the gas refrigerant through the second side of the subcooler. A gas temperature sensor and a gas pressure sensor are configured to measure a temperature and pressure of the gas refrigerant. A liquid temperature sensor is configured to measure a temperature of the subcooled liquid refrigerant. A controller is configured to calculate a superheat of the gas refrigerant based on the measured temperature and measured pressure of the gas refrigerant and may compare the calculated superheat to a superheat threshold. If the calculated superheat is less than the superheat threshold, the controller may close the expansion valve. If the calculated superheat is equal to or greater than the superheat threshold, the controller may operate the expansion valve using a feedback control technique to drive the temperature of the subcooled liquid refrigerant to a subcooled liquid temperature setpoint.

A controller for a refrigeration system includes a processing circuit having one or more processors and memory. The processing circuit is configured to calculate a superheat of a gas refrigerant exiting a first side of a subcooler based on a measured temperature and a measured pressure of the gas refrigerant and compare the calculated superheat to a superheat threshold. In response to a determination that the calculated superheat is less than the superheat threshold, the processing circuit closes an expansion valve to restrict a flow of the gas refrigerant through a second side of the subcooler. In response to a determination that the calculated superheat is equal to or greater than the superheat threshold, the processing circuit operates the expansion valve to drive a temperature of a subcooled liquid refrigerant exiting the second side of the subcooler to a subcooled liquid temperature setpoint.

A two-stage refrigeration apparatus includes a high-stage refrigeration cycle including a high-stage-side refrigerant circuit including a high-stage-side compressor, high-stage-side condenser, high-stage-side expansion valve, and high-stage-side evaporator connected by pipes, a low-stage refrigeration cycle including a low-stage-side refrigerant circuit including a low-stage-side compressor, low-stage-side condenser, low-stage-side receiver, low-stage-side expansion valve, and low-stage-side evaporator connected by pipes, a cascade condenser including the high-stage-side evaporator and low-stage-side condenser, a receiver heat exchanging portion configured to cool the low-stage-side receiver, and a high-stage refrigeration cycle controller configured to perform controlling so as to activate the high-stage-side compressor when estimating a low-stage-side refrigerant will reach a supercritical state while the low-stage-side compressor is defrosted on the basis of the pressure of the low-stage-side refrigerant.

A two-stage refrigeration apparatus includes a high-stage refrigeration cycle including a high-stage-side refrigerant circuit including a high-stage-side compressor, high-stage-side condenser, high-stage-side expansion valve, and high-stage-side evaporator connected by pipes, a low-stage refrigeration cycle including a low-stage-side refrigerant circuit including a low-stage-side compressor, low-stage-side condenser, low-stage-side receiver, low-stage-side expansion valve, and low-stage-side evaporator connected by pipes, a cascade condenser including the high-stage-side evaporator and low-stage-side condenser, a receiver heat exchanging portion configured to cool the low-stage-side receiver, and a high-stage refrigeration cycle controller configured to perform controlling so as to activate the high-stage-side compressor when estimating a low-stage-side refrigerant will reach a supercritical state when the low-stage-side compressor is inactive on the basis of the pressure of the low-stage-side refrigerant.

An apparatus and method for cooling a computing system, comprising a plurality of electronic components, with a cooling system. The cooling system includes a closed loop for the two-phase coolant, wherein the two-phase coolant has a saturation temperature. The closed loop includes a valve fluidly connected between an outlet of a heat exchanger and an inlet of a plurality of evaporator structures configured to be thermally coupled to the plurality of electronic components, and a compressor fluidly connected between an outlet of the plurality of evaporator structures and an inlet of the heat exchanger. The apparatus and method for the cooling system are configured to monitor one or more system temperatures of the computing system and adjust an operation of at least one of the valve or the compressor to alter the saturation temperature based on the one or more system temperatures.

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.

The refrigeration system includes a compressor, a condenser, an evaporator, one or both of a receiver drier unit and an accumulator unit fluidly connected by refrigerant lines to form a refrigerant circuit. The receiver drier unit includes a receiver drier and a first sensor, and the accumulator unit includes an accumulator and a second sensor. A controller is electrically connected to the first and second sensors and in some cases electrically connected to an electrical valve. The electrical valve is fluidly connected to a refrigerant reservoir. The controller determines the refrigerant charge level, and selectively controls the electrical valve to allow the refrigerant to flow from the refrigerant reservoir to the refrigerant circuit when the refrigerant charge level is below the predetermined refrigerant charge level.

The refrigeration system includes a compressor, a condenser, an evaporator, one or both of a receiver drier unit and an accumulator unit fluidly connected by refrigerant lines to form a refrigerant circuit. The receiver drier unit includes a receiver drier and a first sensor, and the accumulator unit includes an accumulator and a second sensor. A controller is electrically connected to the first and second sensors and in some cases electrically connected to an electrical valve. The electrical valve is fluidly connected to a refrigerant reservoir. The controller determines the refrigerant charge level, and selectively controls the electrical valve to allow the refrigerant to flow from the refrigerant reservoir to the refrigerant circuit when the refrigerant charge level is below the predetermined refrigerant charge level.

A refrigeration and air-conditioning apparatus rapidly varies the pressure or the temperature inside a liquid reserve container to identify a liquid level position inside the liquid reserve container on the basis of the surface temperature of the liquid reserve container.