A transcritical R-744 refrigeration system with a medium temperature section having a plurality of circuits, at least one evaporator receiving an R-744 refrigerant in a medium-pressure liquid state from a receiver and feeding at least one transcritical compressor to compress the R-744 refrigerant from a low-pressure gaseous state into a high-pressure gaseous state to feed a gas cooler and a throttling device to partially condense the R-744 refrigerant into a medium-pressure gaseous-liquid state, the system comprising a pressure reducing valve connected to a discharge conduit of the at least one transcritical compressor and feeding hot gas to a defrost manifold to defrost one of the plurality of circuits of the medium temperature section, wherein the hot gas being fed to the defrost manifold has a pressure value less than or equal to a maximum operating pressure of the at least one evaporator.

A subcooling controller includes a sensor and a processor. The sensor measures one or more of a temperature external to a first heat exchanger that removes heat from carbon dioxide refrigerant, a temperature of the carbon dioxide refrigerant, and a pressure of the carbon dioxide refrigerant. The processor determines that one or more of the measured temperature external to the first heat exchanger, the temperature of the carbon dioxide refrigerant, and the pressure of the carbon dioxide refrigerant is above a threshold and in response to that determination, activates a subcooling system. The subcooling system includes a condenser, a second heat exchanger, and a compressor. The condenser removes heat from a second refrigerant. The second heat removes heat from the carbon dioxide refrigerant stored in a flash tank. The compressor compresses the second refrigerant from the second heat exchanger and sends the second refrigerant to the condenser.

A subcooling controller includes a sensor and a processor. The sensor measures one or more of a temperature external to a first heat exchanger that removes heat from carbon dioxide refrigerant, a temperature of the carbon dioxide refrigerant, and a pressure of the carbon dioxide refrigerant. The processor determines that one or more of the measured temperature external to the first heat exchanger, the temperature of the carbon dioxide refrigerant, and the pressure of the carbon dioxide refrigerant is above a threshold and in response to that determination, activates a subcooling system. The subcooling system includes a condenser, a second heat exchanger, and a compressor. The condenser removes heat from a second refrigerant. The second heat removes heat from the carbon dioxide refrigerant stored in a flash tank. The compressor compresses the second refrigerant from the second heat exchanger and sends the second refrigerant to the condenser.

Standalone and self-contained cooling systems using compressed liquid and/or gas CO.sub.2 containers positioned in an insulated or non-insulated vessel encompassing a container which is either vertically positioned in an upright or an upside-down position. The liquid and/or gas CO.sub.2 coolant is then released into a capillary system or flow metering system to allow the CO.sub.2 to enter a second body to where the CO.sub.2 coolant properties may be leveraged. The second body includes, by way of example, a plate, a cushion, a spot treatment pad for a person's muscle, or a cooler. The temperature is controlled by a metering CO.sub.2 releasing system encompassing an electronic control device which sends alerts when pre-defined thresholds are exceeded. The invention's metering CO.sub.2 releasing system may be triggered by an electronic or a thermostatic valve or may be triggered manually or by an electronic solenoid.

Heat pump systems with a gas bypass tank and that operate in both heating and cooling modes are disclosed. The systems include a first splitting valve that can route liquid refrigerant to either the indoor coil or the outdoor coil, depending on whether the heat pump system is in heating or cooling mode. An expansion valve in the system can lower the pressure of liquid refrigerant leaving a condenser, thereby creating a two-phase fluid comprising liquid refrigerant and vaporized refrigerant. The gas bypass tank can separate liquid refrigerant from vaporized refrigerant. The liquid refrigerant can be supplied to the evaporator of the system, while the vaporized refrigerant can be bypassed to a compressor. The first splitting valve can include a first plurality of switching paths that route the separated liquid refrigerant to either the outdoor coil or the indoor coil.

A pressure control system for a liquid-cooled electronic component cooling device. A cooling device cools an electronic component through a refrigerant moving along a pipe. A radiator is mounted on one side of the cooling device to exchange heat with the refrigerant, and has a vent hole extending outwardly. A head has discharge holes communicating with a plurality of first hollows formed therein in an outer circumferential surface thereof with a driver hole provided in an upper surface thereof. A body is coupled to a bottom side of the head and has a second hollow communicating with the first hollows in a lengthwise direction. A pressure controller extends outward from a bottom of the body with an inner portion thereof communicating with the second hollow, and includes a coupler having threads on one side of an outer circumferential surface thereof to be screwed into the vent hole.

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.

The present disclosure provides methods and systems for heat exchange, such as cooling a heat source. A cooling system of the present disclosure may comprise a first channel that is configured to direct a liquid coolant, a second channel that is configured to direct a vapor coolant generated from the liquid coolant, and a condenser that is configured to permit the vapor coolant to undergo phase transition to the liquid coolant. The cooling system may further comprise at least one cooling interface in fluid communication with the first channel and the second channel. The cooling interface may be configured to facilitate heat exchange between the liquid coolant and a heat source.

A refrigeration cycle apparatus in which a refrigerant having potential for disproportionation reaction circulates a first refrigerant flow path connected between a discharge side of the compressor and the condenser; a second refrigerant flow path connected between the condenser and the expansion valve; a third refrigerant flow path connected between the expansion valve and a suction side of the compressor; a jetting unit; a pressure measuring unit; and a temperature measuring unit. The jetting unit is configured to jet the refrigerant drawn from the second refrigerant flow path or the third refrigerant flow path to at least one of the compressor, the first refrigerant flow path and the second refrigerant flow path when at least one of a measured value of the pressure measuring unit and a measured value of the temperature measuring unit exceeds an allowed value.

A cryocooler includes a compressor, an expander that includes a motor and is driven by the motor, an inverter that controls an operation frequency of the motor, a high pressure line that connects the compressor to the expander such that a working gas is supplied from the compressor to the expander, a low pressure line that connects the compressor to the expander such that a working gas is collected from the expander to the compressor, a pressure measurement unit that is configured to measure pressures of the high pressure line and the low pressure line or to measure a differential pressure between the high pressure line and the low pressure line, and a controller that compares the differential pressure to a target pressure and controls the inverter such that the operation frequency of the motor is increased when the differential pressure exceeds the target pressure.