Importance of refrigeration , type of refrigeration system , principle of working vapour compression refrigeration system , cop, cycle diagram . Type of compressors, open type , hermetic rotary. Type of condenser water cooled, air cooled , cooling towers etc. Type of common refrigerants Evaporator: function of evaporator , common type used in refrigeration system. Expansion devices: function of devices , different type of devices, capillary, thermostatic ex, Domestic refrigerator: diagrams of refrigerator deep freezer water cooler ,