Co2 refrigeration system with supercritical subcooling control

Abstract

A refrigeration system includes a gas cooler/condenser configured to remove heat from a refrigerant, a temperature sensor configured to measure a temperature of the refrigerant leaving the gas cooler/condenser, a pressure sensor located along the high pressure conduit and configured to measure a pressure of the refrigerant leaving the gas cooler/condenser, a pressure control valve operable to regulate the pressure of the refrigerant leaving the gas cooler/condenser, and a controller. The controller is configured to determine whether the refrigerant leaving the gas cooler/condenser is in a subcritical region based on at least one of the measured temperature of the refrigerant or the measured pressure of the refrigerant. If the refrigerant leaving the gas cooler/condenser is not in the subcritical region, the controller is configured to add a pseudo-subcooling temperature value to the measured temperature of the refrigerant to calculate a summed temperature, calculate a supercritical pseudo-saturated pressure as a function of the summed temperature, and operate the pressure control valve to drive the pressure of the refrigerant leaving the gas cooler/condenser to the supercritical pseudo-saturated pressure corresponding to the summed temperature.