COLVILLE, Wash. – CO2 (R-744) has become a common refrigerant in Europe and is quickly gaining ground in the U.S. CO2 is a non-toxic, natural refrigerant that does not deplete the ozone layer. This makes it ideal for use in supermarket, food processing, and food storage applications.
All Colmac products that utilize an evaporator can be built for use with CO2 (R-744), including Colmac A+ Series™ air coolers, blast freezers, hydrocoolers, and bare coils for freezers and air handlers. Evaporators can be designed for pumped, DX, or brine operation to be compatible with all system types; transcritical or subcritical, cascade or single stage.
CO2 (R-744) systems operate at higher pressures than other refrigerant systems. The tubing and pipe used in the evaporator is the main determinant of its pressure bearing capability. Colmac offers construction in multiple tube materials, diameters, wall thicknesses and to fit any pressure requirement and application. Available materials include Stainless steel (standard), Hot Dip Galvanized and Copper (low pressure). All standard Colmac CO2 evaporators are designed for 970 psig (67 barg) MAWP.
Colmac CO2 (R-744) evaporators are available with defrost using water, hot gas, electric, or an interlaced glycol circuit. Water is the most common method for defrosting CO2 evaporators because it defrosts quickly, maintains lower pressures than hot gas defrost, and provides rinsing of the evaporator. Hot gas is an efficient defrost method, but requires a sufficient quantity of gas and typically requires special construction due to the high pressure of CO2 at defrost temperatures. Electric defrost is common for smaller systems where hot gas or water are not available in sufficient quantities. Interlaced glycol circuits offer energy savings when a separate chilled glycol system is present. Warm glycol is pumped through a circuit in the evaporator, defrosting the evaporator and cooling the glycol.