This document discusses the desired properties of refrigerants and their environmental impacts. It describes how chlorofluorocarbons (CFCs) were previously used as refrigerants but deplete the ozone layer by releasing chlorine atoms when broken down by UV rays. CFCs react with ozone in the stratosphere, removing oxygen atoms and leaving it vulnerable to UV rays. Newer refrigerants like hydrofluorocarbons (HFCs) do not harm the ozone but are greenhouse gases that contribute to global warming. The document defines terms like ozone depletion potential and global warming potential used to measure environmental impacts.

1. Refrigerant – Environmental
Issue

2. Desired properties of refrigerant :
• Low cost and ease of handling.
• Easily available.
• Non toxic & poisonous.
• Non explosive , corrosive &
chemically stable.
• Non flammable.
• Leakages easily detectable.
• Moderate & low condensing
pressure – otherwise heavy
equipment & stronger piping
required.
• High specific heat of liquid –
reducing vaporization during
throttling.
• Low boiling point – to avoid high
vacuum.
• High latent heat of vaporization
- reduce mass flow of refrigerant
• Low specific volume in vapour
state – reduce size & increase
efficency.
• Stable under working condition.
• Oil miscible.
(capable of being mixed & dissolved)
• Environmental friendly

3. Ozone Creation :
• Chemical formula : 03 natural occurring gas found in the
stratosphere (10 - 50 km from earth surface).
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• On absorbing the UV (ultraviolet) ray, the 02 molecules
split to form individual oxygen atoms.
• The individual atom combines with remaining oxygen
molecules to form ozone, 03.
• OZONE IS A MOLECULE OF THREE OXYGEN ATOMS
: Oxygen atom
Oxygen molecule , 02
UV ray
Free oxygen
molecules
Cluster of ozone

4. • Ultraviolet (UV) light / ray / radiation is harmful to life.
• The ozone layer around the earth :
a) Keeps the planet warm.
In the lower atmosphere, ozone combines with the other greenhouse
gases (water vapour, carbon dioxide, methane, nitrous oxide).
b) In the upper atmosphere ,it blocks nearly all the sun’s UV rays from
reaching surface of the earth.

5. CFCs (Chlorofluorocarbon)
• Compound consisting of chlorine, fluorine and carbon.
Common CFCs : CFC-11,12, 113, 114 and 115.
• Found in refrigerants used previously, aerosols with
CFCs propellant.
• Easily broken down by strong UV rays in the
stratosphere, releasing chlorine atoms.
• Chlorine atoms deplete the ozone layer.
HOW ?

6. Ozone Depletion
UV ray
CFCI3
CFCI2
Oxygen
molecules
2.Chlorine atoms from the
CFCs attacks the ozone,
by taking one oxygen
atom away to form
chlorine monoxide.
Ozone
Oxygen
molecules
1. CFCs reacting with the
UV rays result in formation
of a chlorine atom.
chlorine atom
Chlorine
monoxide
Oxygen atom
Oxygen atom
3.The chlorine monoxide
then combines with
another oxygen atom to
form a new oxygen
molecule and a new
chlorine atom.
5. The chlorine atom goes
on to destroy more ozone
molecules.
4.The newly formed
oxygen molecules do not
block the UV rays,
allowing it to penetrate to
the surface of the earth.
Oxygen atom
Oxygen atom
Oxygen atom
chlorine atom
Oxygen
molecules

7. Glossary (part 1) :
1. Ozone Depletion Potential, ODP
A number which refers to the amount of ozone depletion caused by a
substance.
ODP = impact on ozone of a chemical / impact on ozone with CFC-11 of
similar mass.
ODPCFC-11 = 1.0 ; ODPHalon = 10 ; ODPHFC = 0 (No chlorine present)
2. Global Warming Potential, GWP
A number that’s refers to the amount of global warming caused by a
substance.
GWP = warming caused by a substance / warming caused carbon
dioxide of similar mass.
GWPCO2 = 1.0 ; GWPCFC-12 = 8,500 ; GWPCFC-11 = 5,000

8. Glossary (part 2):
• Chloroflurocarbon (CFC) : Compound consisting of chlorine,fluorine
& carbon.
• Halon : Not a refrigerant but included in the glossary as used
extensively as a extinguishing agent.
Contains Bromine, which is many time more effective in destroying
the ozone than chlorine.
ODP halon 1301 = 13 ; ODP halon 1211 = 4
• Hydrobromofluorocarbon (HBFC) : Compound of hydrogen, bromine
, fluorine and carbon.
• Hydrocarbon (HC) : Compound of hydrogen & carbon. Methane,
ethane, propane…… Although highly flammable, ODP=0;low GWP;
low toxicity.
• Hydrochlorofluorocarbon (HCFC) : Compound of hydrogen, chlorine,
fluorine & carbon. HCFCs to replace CFCs. Chlorine content is much
lesser than CFCs.

9. Glossary (part 3):
• Hydroflorocarbons (HFCs) : Compound of hydrogen, fluorine and
carbon. HFCs are to replace CFCs. Non existence of chlorine = zero
depletion of ozone.
Refrigerant 134a and R404 are classed HFCs group.
They do not attack the ozone layer BUT
are classified as GREENHOUSE gases.