Refrigeration may be defined as the process of
achieving and maintaining a temperature below that of the surroundings
temperature and the working fluid used for cooling is refrigerant.
In the present
environmental scenario, Refrigeration and Air Conditioning has translated from
a mere luxury to a desired necessity. With the growing demand of air
conditioner units, the demand for electricity has also increased drastically.
The primary means of electric power generation comes from the burning of fossil
fuels results in the release of more pollutants into the atmosphere. About 80%
of the impact of air conditioners comes from the production of electricity and
the remaining is due to refrigerant leakage.
It is a well-known fact that the short wavelength UV rays are
harmful for the life on the Earth. The thick ozone layer in the Stratosphere
filters these rays from reaching the Earth’s surface. CFC’s are more chemically
stable and have a larger atmospheric life. Due to which they reach the
stratosphere and the chlorine atom in the CFC gets activated due to the UV
rays. The chlorine atoms are highly reactive and react with the abundant ozone
in stratosphere reducing it to oxygen. This leads to ozone layer depletion. HCFC’s
and HFC’s were developed to replace CFC’s. Though HCFC’s had a substantial ODP
value, their use was continued. But later it was found that these refrigerants
have high potential as greenhouse gases. The surface temperature is balanced by
the Earth’s ability to send heat coming from the sun in the form of infrared
radiation back into the space. These refrigerants are responsible to increase
the surface temperature of the Earth forming a shield over the surface which blocks
the infrared radiation exiting the Earth. The major outcome of this is melting
of polarize caps raising the sea level globally.
The ODP is the relative effect of a compound on the ozone layer
compared to the effect caused by the same mass of CFC-11 whose ODP value is 1.
Ozone layer when reacted with chlorine in presence of sun light,
it decomposes into oxygen which results in destruction of ozone layer. As a
result the whole life on earth is subjected to harmful UV radiation.
To control the amounts of use of ozone depletion substances this
protocol came into existence on 16 September 1987 and came into force on 1
CFC’s are banned all over the world due to their adverse effects
on ozone layer depletion and HCFC’s are going to be phased out by 2025.
Recent scientific evaluation shows that Montreal protocol is
actually working, the hole on the ozone layer above the Antarctica is slowly
decreasing in size
Global Warming Potential
GWP is defined as the relative amount of heat that a greenhouse
gas traps in the atmosphere over a period of time as compared to a reference
compound. Carbon dioxide is considered as the reference greenhouse gas. The GWP
is measured for a period of 20, 100 or 500 years. It is the amount of heat
absorbed by a greenhouse gas with respect to carbon dioxide over a time period.
To control the global warming due to green house gases this
protocol came into existence on December 11 1997 and came into existence on
February 16 2005. HFC’S have very high GWP values making them super green house
gases. In future HFC’s will no longer be used for refrigeration and air
GWP (100 years)
CFC’s are fully halogenated carbon compounds. Halogenations is the
replacing all the hydrogen bonds in an organic compound with five
fluorine, chlorine, bromine, iodine and astatine. CFC’s are the
derivatives of methane,
ethane with halogens chlorine and fluorine.
CFC’s R-11, R-12 are very commonly used as refrigerants but they
were banned due to the chlorine content which cause ozone layer depletion.