OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
3. Need for Alternatives of R134a
3.1 Generation of Refrigerants:
• The first generation (1830-1930) of refrigerants was based on the availability. These refrigerants were
often highly toxic, flammable and some very highly reactive. Example – Ethers, CO 2 , NH 3 , CCl 4 etc.
• The second generation (1930-1990) of refrigerants focused on reducing toxicity and flammability.
Example: CFCs, HCFCs, HFCs, NH 3 , H 2 O etc.
• The third generation (1990-2010) of refrigerants focused on protecting the ozone layer. Example -
HCFCs, HFCs, HCs, NH 3 , H 2 O, CO 2 etc.
• The fourth generation (from 2010 onwards) focused on refrigerants that do not contribute to global
warming, ozone layer depletion, efficient, non flammable and non toxic with good stability. But the
outlook for discovery or synthesis of these ideal refrigerants is extremely unlikely. Therefore, trade -off
among desired objectives are necessary to achieve the balanced solution.
3.2 Montreal Protocol:
• In 1987 Montreal protocol established the requirements that began the world – wide phase out of CFCs.
Production of CFCs was phased out by the Montreal Protocol in developed countries in 1 st of January,
1996. Production in developing countries was phased out in 2010 [4].
• In 1992 Montreal protocol established the requirements that began the world – wide phase out of
HCFCs. Complete production of HCFCs will be phased out by Montreal protocol in 2030.
3.3 Kyoto Protocol:
• Kyoto protocol aims at phasing out of substances that will lead to global warming.
• R134a is used in domestic refrigerator and other vapour compression systems as it was identified as a
replacement to CFC-12, keeping in view its zero ozone depleting potential. R134a has 1300 global
warming potential per 100 year, which is very high. The sale of R134a reported to AFEAS 1970-2003
[13] is significantly increasing during the past two decades. The increased emission of R134a to the
atmosphere are steadily increasing the concentration of green house gases via leaks and mostly, in an
indirect way, via energetic performance of refrigeration plant. This will lead to adverse climatic
problem. Hence, R134a is one of the six chemicals in the “basket” that are to be phased out in the near
future under Kyoto protocol.
4. Environmental Concern
• The first major concern is depletion of ozone layer. Ozone layer is a layer which protects the earth from
ultraviolet rays. Ozone depletion potential is evaluated on a scale that uses CFC-11 as a benchmark. All
the other components are based on how damaging to the ozone they are in relation to CFC-11.
• The second major concern is global warming. Global warming is the increase in global earth surface
temperature due to the absorption of infrared emission from earth surface. Global warming potential is
evaluated on a scale that uses CO 2 as the bench mark i.e. CO 2 is assigned a value and other components
are compared to CO 2 .
5. Analysis of Vapour Compression Refrigeration Cycle
• Thermodynamic analysis is the analysis based on energy. Raising the efficiency of an energy system is
within the domain of thermodynamics.
• Thermoeconomic analysis is the analysis based on exergy and economic principles to provide system
designer or operator with information not available through conventional energy analysis and economic
evaluations but crucial to the design and operation of a cost effective system. Energy cannot be
destroyed-a first-law concept. The idea that something can be destroyed is useful in the design and
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