WEL COME TO COE RAC SECTOR ITI UTTARSANDA

ADVANCE MODULE :-I Advance Module in Domestic, Commercial Refrigeration and Air Conditioning

LESSON :- 01 REFRIGERANTS

OBJECTIVES State their important properties. State the Environmental impact of refrigerant. Identify Alternative Refrigerants for CFC’S. Explain about Refrigerant cylinder-various types

REFRIGERANTS Refrigerants are the medium of heat transfer in a refrigerating system which picks up heat by evaporating at a low temperature and pressure and gives up heat by condensing at a higher temperature and pressure.

Identify refrigerants by number Methane & ethane based refrigerants are made by the substitution of halo carbon which are chlorine,fluorine, bromine. These refrigerants That contain fluorine & are currently used refrigerants which are known as Fluoro carbons Refrigerant 12 (R-12) Refrigerant 22 (R-22) Refrigerant 134-a (R-134-a)

PROPERTIES OF REFRIGERANTS 1.Low boiling point 2.High latent heat value 3.Easy to liquify at moderate pressure & temperature 4.Operation on a positive pressure 5.Mixes well with compressor oil 6.Non corrosive to metal / parts & motor winding insulation other insulation 7.Not affected by moisture 8.Non flammable and non toxic 9.High Di – Electric strength 10.Environmentally safe

ENVIRONMENTAL IMPACT OF CFC & OTHER REFRIGERANTS 1.Ozone Depleting Potential (ODP) The Chlorine atom in CFC & HCFC which gets freed in the stratosphere due to ultra violet rays of the sun, cause depleting of the protective ozone layer by converting the ozone into oxygen. One chlorine atom damages ozone molecules and ozone depletion potential of any refrigerants is stated with reference to the ODP of CFC 2.Global Warming Potential (GWP) The GWP of a substance is defined with ref. to CO 2 i.e. mass of CO 2 needed to create a same level of global warming as one unit mass of the substances. Thus R 12 has GWP of R 11 of 7300, R 22 of 1700 & R 134a of 1300.

Alternative Refrigerants Due to bad environmental impact of CFC, it is required to replace CFC by its alternatives. Alternative refrigerants are 1.Hydrocarbons 2.Ammonia 3.Carbon dioxide

Types of Refrigerant Cylinder Most refrigerants are supplied by refrigerants manufacturer and stored in by cylinder made by steel or aluminum. Types of Refrigerant Cylinders are 1.Storage Cylinder 2.Returnable Service Cylinder 3.Disposable Cylinder

Colors code for refrigerant cylinders Refrigerant numberCylinder color code The cylinder used for transporting refrigerant are color code to permit easy Identification of the refrigerant in the cylinders. This prevent accidentals mixing of Refrigerants within a system. Orange White Green Orchid Silver White R-11 R-12 R-22 R-502 R-717 R-134-a