US 10,208,985 B2Granted

Flash tank pressure control for transcritical system with ejector(s)

AssigneeHeatcraft Refrigeration Products LLC

InventorFardis Najafifard

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Abstract

In certain embodiments, a transcritical refrigeration system provides refrigeration by circulating carbon dioxide (CO2) refrigerant through the system. A flash tank of the transcritical refrigeration system is operable to supply the CO2 refrigerant, in liquid form, to a low temperature refrigeration case and a medium temperature refrigeration case. A low temperature compressor is operable to compress the CO2 refrigerant discharged from the low temperature refrigeration case. A medium temperature compressor, a parallel compressor, and an ejector are each operable to compress the CO2 refrigerant discharged from the medium temperature refrigeration case, the CO2 refrigerant discharged from the low temperature compressor, and/or CO2 flash gas discharged from the flash tank. A gas cooler is operable to cool the CO2 refrigerant discharged from the medium temperature compressor and the parallel compressor. A controller is operable to dynamically adjust a pressure set point for the flash tank.

Claims14

Dependent claims

A transcritical refrigeration system operable to circulate carbon dioxide (CO2) refrigerant through the transcritical refrigeration system in order to provide refrigeration, the transcritical refrigeration system comprising:

a flash tank operable to supply the CO2 refrigerant, in liquid form, to a low temperature refrigeration case and a medium temperature refrigeration case;
a low temperature compressor operable to compress the CO2 refrigerant discharged from the low temperature refrigeration case;
a medium temperature compressor operable to compress at least one of the CO2 refrigerant discharged from the medium temperature refrigeration case and the CO2 refrigerant discharged from the low temperature compressor;
a parallel compressor operable to compress CO2 flash gas discharged from the flash tank;
an ejector operable to compress at least one of the CO2 refrigerant discharged from the medium temperature refrigeration case and the CO2 refrigerant discharged from the low temperature compressor;
a gas cooler operable to cool the CO2 refrigerant discharged from the medium temperature compressor and the parallel compressor;
and
a controller operable to dynamically adjust a pressure set point for the flash tank, wherein the controller dynamically adjusts the pressure set point for the flash tank based on a temperature at an outlet of the gas cooler;
wherein in response to determining that the temperature at the outlet of the gas cooler has increased such that it exceeds a temperature threshold, the controller adjusts the pressure set point for the flash tank in order to increase Δp, wherein Δp is the difference between the pressure of the flash tank and suction pressure of the medium temperature compressor.

6 more elements

A controller for a refrigeration system, the controller comprising one or more processors and logic encoded in non-transitory computer readable memory, the logic, when executed by one or more processors, operable to:

dynamically adjust a pressure set point for a flash tank based on a temperature value, the temperature value determined from at least one of an ambient air temperature and a gas cooler outlet temperature;
determine that the temperature value has increased such that it exceeds a temperature threshold;
and
adjust the pressure set point for the flash tank in order to increase Δp, wherein Δp is the difference between the pressure of the flash tank and suction pressure of a compressor of the refrigeration system.

1 more element

A method of operating a refrigeration system, the method comprising:

determining a temperature associated with an outlet of a gas cooler that is operable to cool refrigerant received from one or more compressors and discharge the refrigerant to a flash tank via one or more ejectors;
performing a comparison that compares the temperature associated with the outlet of the gas cooler to a temperature threshold;
adjusting a pressure set point for the flash tank based on the comparison;
and
instructing one or more components of the refrigeration system to operate according to a configuration that causes a measured pressure of the flash tank to move toward the pressure set point for the flash tank.

2 more elements

Dependencies are inferred from the claim text.