US 12,078,395 B2
Hot gas defrost using dedicated low temperature compressor discharge
Saravana Vaithilingam Sakthivel, Chennai (IN); and Karthick Kuppusamy, Salem (IN)
Assigned to Heatcraft Refrigeration Products LLC, Stone Mountain, GA (US)
Filed by Heatcraft Refrigeration Products LLC, Stone Mountain, GA (US)
Filed on Oct. 18, 2023, as Appl. No. 18/489,131.
Application 18/489,131 is a continuation of application No. 17/466,017, filed on Sep. 3, 2021, granted, now 11,828,506.
Prior Publication US 2024/0044561 A1, Feb. 8, 2024
Int. Cl. F25B 47/02 (2006.01); F25B 41/22 (2021.01)
CPC F25B 47/022 (2013.01) [F25B 41/22 (2021.01); F25B 2400/23 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A refrigeration system, comprising a gas cooler, a heat exchanger located downstream from the gas cooler, a flash tank located downstream a first outlet of the heat exchanger, a defrost-mode compressor located downstream a second outlet of the heat exchanger, a first evaporator unit located downstream from the flash tank, and a controller communicatively coupled to the defrost-mode compressor, wherein:
the flash tank is configured to store refrigerant;
the gas cooler is configured to receive refrigerant and facilitate heat transfer from the received refrigerant, thereby cooling the refrigerant;
the controller is configured to:
determine that operation of the first evaporator unit in a defrost mode is indicated; and
after determining that operation of the first evaporator unit in the defrost mode is indicated, cause the first evaporator unit to operate in the defrost mode, wherein causing the first evaporator unit to operate in the defrost mode comprises causing the defrost-mode compressor to turn on;
the heat exchanger is configured, while the defrost-mode compressor is turned on, to:
receive a portion of refrigerant stored by the flash tank; and
transfer heat from the received portion of refrigerant to the refrigerant cooled by the gas cooler, thereby heating the received portion of refrigerant; and
the defrost-mode compressor is configured, while turned on, to provide the portion of the refrigerant heated by the heat exchanger to the first evaporator unit, thereby defrosting an evaporator of the first evaporator unit;
wherein:
the first evaporator unit comprises:
a first valve located upstream from the evaporator, wherein, when the first evaporator unit is operating in a refrigeration mode, the first valve is closed;
a second valve located downstream from the evaporator, wherein, when the first evaporator unit is operating in the refrigeration mode, the second valve is open; and
a pressure-activated valve disposed in a refrigerant conduit between the first valve and the evaporator, the pressure-activated valve configured to allow a flow of refrigerant after a threshold pressure is reached, wherein the threshold pressure is greater than a pressure of the flash tank; and
the controller is further configured to cause the first evaporator unit to operate in the defrost mode by causing the first valve to open and causing the second valve to close.