AMMONIA REFRIGERATION SYSTEM WITH CO2 AS A SECONDARYREFRIGERANT

摘要

Ammonia is one of the oldest refrigerants in industrial use today. It is a natural refrigerant withrnexcellent thermal properties. Most ammonia refrigeration systems, however, are of indirect typernusing secondary refrigerants. This is because of the flammable and toxic nature of ammonia. Mostrnof the secondary refrigerants have poor heat transfer characteristics and high pressure losses at lowrntemperatures thus offering low system COPs.rnCarbon dioxide is being promoted as a secondary refrigerant. This is because carbon dioxide is arnnatural refrigerant (ODP=0, GWP=1), non toxic, inflammable and has good transport propertiesrnwhich results in low pressure losses in the pipes. The COP of the system, therefore, can bernimproved.rnThe system is easy to maintain since it does not require secondary refrigerant concentration, PHrnand corrosion control.rnThis paper reports on the development of an ammonia refrigeration system using carbon dioxidernas a secondary refrigerant. The system was applied in a storage room and test results are reported.