Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: Systems and method for operating a refrigeration system include a heat exchanger configured to remove heat from a refrigerant and discharge the refrigerant into a conduit. A temperature sensor, a pressure sensor, and a pressure control valve are located along the conduit. A controller is configured to determine that the refrigerant leaving the heat exchanger is outside of a subcritical region based on the measured temperature or measured pressure of the refrigerant. A target temperature is determined based at least in part on a pseudo-subcooling temperature value and the measured temperature of the refrigerant. A supercritical pseudo-saturated pressure is determined based on the target temperature. A pressure offset is determined based on the target temperature, a maximum operating pressure of the refrigeration system, and an offset factor. The pressure control valve is operated to drive the pressure to a target pressure based on the pressure offset and the pseudo-saturated pressure.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: Systems and method for operating a refrigeration system include a heat exchanger configured to remove heat from a refrigerant and discharge the refrigerant into a conduit. A temperature sensor, a pressure sensor, and a pressure control valve are located along the conduit. A controller is configured to determine that the refrigerant leaving the heat exchanger is outside of a subcritical region based on the measured temperature or measured pressure of the refrigerant. A target temperature is determined based at least in part on a pseudo-subcooling temperature value and the measured temperature of the refrigerant. A supercritical pseudo-saturated pressure is determined based on the target temperature. A pressure offset is determined based on the target temperature, a maximum operating pressure of the refrigeration system, and an offset factor. The pressure control valve is operated to drive the pressure to a target pressure based on the pressure offset and the pseudo-saturated pressure.

Abstract: Systems, methods, and devices for evaporative cooling include one or more heat exchanger coils, one or more evaporative pads external to the one or more heat exchanger coils, and one or more nozzle assemblies external to the one or more evaporative pads. The one or more nozzle assemblies can be coupled to a supply of liquid and configured to provide the liquid to at least one of the one or more evaporative pads. A basin can be configured to collect a portion of liquid from the one or more evaporative pads, and an injector disposed between the supply of liquid and the one or more nozzle assemblies. The injector includes a first inlet coupled to the supply of liquid, a second inlet coupled to the basin, and an outlet coupled to the one or more nozzle assemblies.

Abstract: A method of operating a cooling system having one or more evaporative pads includes: obtaining measurements of one or more ambient conditions associated with the cooling system; determining, based at least in part on at least one of the one or more ambient conditions and one or more characteristics of at least one of the one or more evaporative pads, an available evaporation rate; and controlling, based at least in part on the available evaporation rate, an application rate of water to at least one of the one or more evaporative pads.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: Systems and methods for controlling pressure in a CO2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

Abstract: An evaporative cooling device for a refrigeration system includes one or more heat exchanger coils, a first moisture panel, a second moisture panel, a first nozzle array, a second nozzle array, a moisture sensor, and a controller. The first moisture panel and the second moisture panel are separated by a distance and disposed external to the one or more heat exchanger coils. The first nozzle array is disposed external to the first moisture panel and the second nozzle array is disposed external to the second moisture panel. The first nozzle array and the second nozzle array are configured to provide an atomized spray of electrostatically charged droplets. The moisture sensor is configured to provide a signal representative of a moisture level. The controller is configured to receive the signal representative of the moisture level and control a supply of water.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: An evaporative cooling device for a refrigeration system includes one or more heat exchanger coils, a first moisture panel, a second moisture panel, a first nozzle array, a second nozzle array, a moisture sensor, and a controller. The first moisture panel and the second moisture panel are separated by a distance and disposed external to the one or more heat exchanger coils. The first nozzle array is disposed external to the first moisture panel and the second nozzle array is disposed external to the second moisture panel. The first nozzle array and the second nozzle array are configured to provide an atomized spray of electrostatically charged droplets. The moisture sensor is configured to provide a signal representative of a moisture level. The controller is configured to receive the signal representative of the moisture level and control a supply of water.

Abstract: An evaporative cooling device for a refrigeration system includes one or more heat exchanger coils, a first moisture panel, a second moisture panel, a first nozzle array, a second nozzle array, a moisture sensor, and a controller. The first moisture panel and the second moisture panel are separated by a distance and disposed external to the one or more heat exchanger coils. The first nozzle array is disposed external to the first moisture panel and the second nozzle array is disposed external to the second moisture panel. The first nozzle array and the second nozzle array are configured to provide an atomized spray of electrostatically charged droplets. The moisture sensor is configured to provide a signal representative of a moisture level. The controller is configured to receive the signal representative of the moisture level and control a supply of water.

Abstract: An evaporative cooling device for a refrigeration system includes one or more heat exchanger coils, a first moisture panel, a second moisture panel, a first nozzle array, a second nozzle array, a moisture sensor, and a controller. The first moisture panel and the second moisture panel are separated by a distance and disposed external to the one or more heat exchanger coils. The first nozzle array is disposed external to the first moisture panel and the second nozzle array is disposed external to the second moisture panel. The first nozzle array and the second nozzle array are configured to provide an atomized spray of electrostatically charged droplets. The moisture sensor is configured to provide a signal representative of a moisture level. The controller is configured to receive the signal representative of the moisture level and control a supply of water.

Abstract: Systems and methods for controlling pressure in a CO2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

Abstract: Systems and methods for controlling pressure in a CO2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

Abstract: A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Abstract: A secondary coolant refrigeration system powered primarily by a photovoltaic source and by an alternating current (AC) source as a backup is disclosed. The secondary coolant refrigeration system has a pump for pumping secondary coolant fluid through a secondary coolant fluid loop. The system includes a variable frequency drive for controlling the speed of the pump. The variable frequency drive includes drive circuitry configured to provide variable frequency power to the pump via an output interface. The variable frequency drive also includes a first interface configured to receive power from the photovoltaic source and a second interface configured to receive power from the AC source. The circuit is further configured to cause the variable speed drive to be powered by the photovoltaic source when the power received from the first interface is adequate and by the AC source when the power received from the first interface is not adequate.

Abstract: A cascade refrigeration system including an upper portion having at least one modular chiller unit that provides cooling to at least one of a low temperature subsystem having a plurality of low temperature loads, and a medium temperature subsystem having a plurality of medium temperature loads. The modular chiller unit includes a refrigerant circuit having at least a compressor, a condenser, an expansion device, and an evaporator. An ammonia refrigerant which may have entrained oil from the compressor circulates within the refrigerant circuit. An oil recycling circuit removes some oil from the ammonia refrigerant for return to the compressor. An oil pot collects oil accumulated in the evaporator and an oil return line drains oil from the oil pot to an ammonia accumulator or directly to the compressor.