Co2 as a Refrigerant

Even though Hydrofluoro compounds (HFC) are widely used as refrigerants because of their environment friendly nature (no damage to ozone layer), CO2 is also a popular choice as refrigerant.

Some of the advantages of CO2 as a refrigerant are:

• widely available;
• high volumetric cooling capacity and heat transfer;
• no recovery or recycling required;
• non inflammable and non toxic;
• environment friendly;
• the compressors are compact in size

Some of the difficulties is using CO2 as refrigerant are: high working pressure and large pressure difference (3 to 5 times conventional refrigerants); low theoretical efficiency with normal refrigeration systems. Hence it requiresadvanced technology compressor and refrigeration system. The hoses need to be strong as well as the evaporators and gas coolers are used instead of condensers as there is no phase change of the refrigerant. They are widely used in vending machines.

One of the difficulties of CO2 as a refrigerant is its detection and level control.

Chemical sensor elements cannot reliably measure CO2 levels. Other alternate detectors include infrared sensors.