Small-Diameter Copper Tubes with Alloying Elements Can Handle CO2 Refrigerant
ACHR News, January 15, 2015
Smaller-diameter copper tubes strengthened with low percentages of alloying elements can withstand the higher pressures of the new refrigerants such as CO2 (R-744), according to the International Copper Association.
Refrigerants with low global warming potential (GWP) typically must operate at higher pressures, and heat exchanger coils must be designed to withstand these higher pressures. An extreme case is carbon dioxide, or R-744, which has a very low GWP compared to other refrigerants, yet requires high operating pressures.
Smaller-diameter tubes naturally have higher burst pressures for a given wall thickness as a direct consequence of tube mechanics. Another way to increase burst pressure without increasing tube wall thickness is to use high strength alloys of copper, said the International Copper Association.