Low charge hydrocarbon refrigeration system

• Main Authors: Lee, Chiao, Shapiro, Doron, Street, Norman
• Format: Patent
• Language: English
• Published: 28.06.2019
• Subjects: BLASTING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; HEATING; LIGHTING; LIQUEFACTION SOLIDIFICATION OF GASES; MANUFACTURE OR STORAGE OF ICE; MECHANICAL ENGINEERING; REFRIGERATION MACHINES, PLANTS OR SYSTEMS; REFRIGERATION OR COOLING; WEAPONS

Merchandiser refrigeration systems that use a hydrocarbon refrigerant may be required to have no more than 150 grams of refrigerant per circuit to minimize the likelihood that leaked refrigerant will ignite and cause adverse conditions in the area surrounding the merchandiser. Low charge circuits can result in inefficiencies. A disclosed refrigeration system includes a first circuit that has a first heat exchanger, a second heat exchanger, and a pump fluidly connected to the first heat exchanger and the second heat exchanger to circulate a first coolant within the first circuit. The refrigeration system also includes a second circuit that circulates a fluid and a refrigerated merchandiser defining a product support area. An evaporator is in communication with the product support area to condition the area within a predetermined temperature range. The refrigeration system also includes a third circuit including the second heat exchanger, a chiller unit, and a compressor fluidly connected to the second heat exchanger and the chiller unit to circulate a hydrocarbon refrigerant in heat exchange relationship with the first coolant. Heat from the hydrocarbon refrigerant is absorbed by the first coolant within the second heat exchanger. The chiller unit is positioned in communication with the second circuit such that heat from the fluid is transferred to the hydrocarbon refrigerant in the chiller unit. The refrigeration system also includes a fourth circuit in heat exchange relationship with each of the second circuit and the third circuit. The second circuit includes a condenser and the fourth circuit includes the chiller unit and a pump circulating a second fluid through the condenser in direct heat exchange relationship with the fluid of the second circuit to extract heat from the fluid. The second fluid is further in direct heat exchange relationship with the hydrocarbon refrigerant within the chiller unit to discharge heat to the third circuit. The refrigeration system also includes a fifth circuit including a second condenser, a second evaporator, and a second compressor arranged in series relationship with each other. The second condenser defines a cascade heat exchanger between the first circuit and the fifth circuit. The second compressor circulates a second hydrocarbon refrigerant in direct heat exchange relationship with the first coolant within the second condenser. A second refrigerant charge of the fifth circuit does not exceed approximately 150 grams of hydrocarbon refrigerant. The third circuit has a refrigerant charge not exceeding approximately 150 grams of refrigerant.