| CPC F25B 47/022 (2013.01) [F25B 5/02 (2013.01); F25B 41/22 (2021.01); F25B 41/24 (2021.01); F25B 2400/23 (2013.01)] | 16 Claims |
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1. A refrigeration system comprising one or more compressors, a gas cooler located downstream from the one or more compressors, a defrost-mode expansion valve located downstream from the one or more compressors, at least one first evaporator unit located downstream from the gas cooler, and a controller communicatively coupled to the defrost-mode expansion valve, a first valve, and a second valve, wherein:
the one or more compressors are configured to compress a refrigerant;
the gas cooler is configured to receive at least a portion of the compressed refrigerant as a received refrigerant and facilitate heat transfer from the received refrigerant, thereby cooling the refrigerant;
the at least one first evaporator unit comprises an evaporator, an expansion valve located upstream of the evaporator when the at least one first evaporator unit is operated in a refrigeration mode, the first valve located upstream of the evaporator when operated in the refrigeration mode, the second valve located downstream of the evaporator when operated in the refrigeration mode, wherein the first valve is closed and the second valve is open when operated in the refrigeration mode, and wherein the expansion valve is configured to receive a portion of the refrigerant cooled by the gas cooler and the evaporator is configured to receive the refrigerant from the expansion valve when the at least one first evaporator unit is operated in the refrigeration mode;
the refrigeration system further comprises a pressure-relief valve disposed between the at least one first evaporator unit and the defrost-mode expansion valve, the pressure-relief valve configured to open when a pressure of an expanded portion of the refrigerant from the defrost-mode expansion valve is greater than a threshold value after passing through the defrost-mode expansion valve, and a sensor disposed adjacent a downstream side of the defrost-mode expansion valve, the sensor configured to provide at least one of temperature and pressure information of the compressed refrigerant to the controller;
the controller is configured to:
determine that operation of the at least one first evaporator unit in a defrost mode is indicated; and
after determining that operation of the at least one first evaporator unit in the defrost mode is indicated, cause the at least one first evaporator unit to operate in the defrost mode, wherein causing the at least one first evaporator unit to operate in the defrost mode comprises causing the defrost-mode expansion valve to at least partially open based on at least one of the temperature and pressure information from the sensor to adjust a flow of compressed refrigerant; and
the defrost-mode expansion valve is configured, when open, to divert a portion of the compressed refrigerant provided by the one or more compressors away from the gas cooler, expand the diverted portion of the refrigerant, and allow the expanded portion of the refrigerant to flow to the least one first evaporator unit, thereby defrosting the evaporator of the at least one first evaporator unit; and
the controller is further configured to cause the at least one first evaporator unit to operate in the defrost mode by causing the first valve to open and by causing the second valve to close, wherein the diverted portion of the refrigerant exiting the evaporator flows through the first valve when operating in the defrost mode.
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