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
Ammonia
invapor
compression
systems
Carbon dioxide
in vapour
compression
systems
Yes, well tried
and proven Higher Better Yes (chiller only)
technology
Yes
principle)
(in
Porbably
higher
Currently
lower
No
Strict compliance with safety
standards & codes necessary to
minimize toxicity hazards.
More development needed to
overcome poor efficiency.
Might be best suited as a
secondary refrigerant.
2. CONCLUSION
We now have some very good alternatives for the CFCs but still a great improvement is required in this way to
achievethisLooking further down the road, carbon dioxide may someday replace today’s refrigerants. Though
carbon dioxide is a "greenhouse gas" that may contribute to global warming, it is non-toxic, non-flammable,
cheap and abundant. But to work as a refrigerant, carbon dioxide must be run at extremely high pressures - up to
several thousand psi! As long as the gas is safely contained at high pressure, it works pretty well as a refrigerant.
But such high pressures pose a potential danger to technicians who must ultimately work on such systems.
Someday a perfect air conditioner may use no refrigerant whatsoever. Some time back, the Rovac Corporation in
Rockledge, FL, announced it had developed a revolutionary A/C system that required no refrigerant at all, and
used air itself as the working medium. The Rovac system used a "circulator" that was essentially an expander
rather than a compressor. By expanding the volume of air, the drop in pressure produced a corresponding drop in
temperature. The system supposedly required 35 to 40% less power than a refrigerant-based A/C system and
provided equivalent cooling. Mitsubishi has licensed rights to the technology and was investigating it further.
That was 20 years ago. We’re still waiting.
Ten years ago, the Naval Postgraduate School in Monterey, CA, claimed it had developed a refrigeration process
using an acoustic generator. Sound waves were used to create pressure changes that had a chilling effect. No
word as to what ever happened to this technology.
Although there are a lot of substitutes for CFCs as refrigerants, scientists continue to research new substitutes,
which are less expensive, less destructive for ozone layer and more practical for industry. (16)
3. REFERENCES
1) Speth, J. G. 2004. Red Sky at Morning: America and the Crisis of the Global Environment New Haven:
Yale University Press, pp 95.
2) The Ozone Hole-The Montreal Protocol on Substances that Deplete the Ozone Layer
3) http://ozone.unep.org/Ratification_status
4) UNEP press release: "South Sudan Joins Montreal Protocol and Commits to Phasing Out Ozone-Damaging
Substances". Thomas Midgley, Jr and Albert L. Heene "Organic Fluorides as Refrigerants " I&EC, 1937,
22, 542-545.
6) Exemption Information - The Ozone Secretariat Web Site
7) Use of ozone depleting substances in laboratories. TemaNord
2003:516. http://www.norden.org/pub/ebook/2003-516.
8) The Technical and Economic Feasibility of Replacing Methyl Bromide in Developing Countries. Friends of
the Earth, Washington, 173 pp, 1996
9) Guidance on the DOE Facility Phaseout of Ozone-Depleting Substances.
10) 1995.http://homer.ornl.gov/nuclearsafety/nsea/oepa/guidance/ozone/phaseout.pdf
11) http://www.epa.gov/ozone/geninfo/benefits.html (accessed 03/19/2003
12) JasenNeese and Steve OravetzReplacing chlorofluorocarbon refrigerants U.S. Dept. of Agriculture, Forest
13) Service, Technology & Development Program: Missoula, Mont., 1998.
14) Protection of the ozone layer, U.S. Environmental protection Agency: Washington, D.C., 1995
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