| Overview: |
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have
been used as refrigerants since the 1930s. Because of their ozone-depleting effect
and the phaseout of the production of these chemicals
[production of Class I ozone-depleting substances (ODSs) was banned as of January 1, 1996], development
of alternative refrigerants and refrigeration and air conditioning
processes are becoming increasingly important.
Air conditioning and refrigeration use the principle of vapor
compression to achieve a cooling effect. This process has long relied on
CFCs and HCFCs as the refrigerant materials of choice for use in the vapor
compression process. The discovery of their probable effect on the ozone
layer has resulted in the development of alternative processes, as well as
development of new refrigerants.
The first substitute refrigerants for CFCs and HCFCs have been
developed and are known as hydrofluorocarbons (HFCs), since they do not
contain any chlorine atoms, HFCs are already beginning to be used. Due to
the concern for future regulation of HFCs for global warming, other
processes are being looked at to replace them in the long-term.
Applications for:
- Vapor compression using hydrocarbons, ammonia, carbon dioxide, or
water:
- Ammonia - refrigerated warehouses and industrial processes;
- Hydrocarbons - industrial applications and more recently small
appliances;
- Water - above 0o C applications only, such as air
conditioning;
- Carbon dioxide - stationary air conditioning and potentially
automobile air conditioning in the future; Being used in small
appliances in many parts of the world, but not in the U.S.
- Evaporative cooling (direct and indirect):
- Residential and industrial air conditioning systems
- Gas expansion:
- Transport of perishable substances
- Absorption: Industrial processes with excess waste heat but
also needing refrigeration, gas fired systems are often used in remote
areas where electrical costs are high or the supply of electricity will
not meet demand, often used in conjunction with electrically powered
vapor compression systems to reduce peak load power demands.
- Stirling Cycle: Practical only for small applications
- Air (Joule) Cycle: Not practical in many applications due to
high power requirements
- Thermoelectric Cooling: Small applications, not economically
viable in most larger applications due to its low efficiency, often used
in specialty applications where low noise or high reliability is
desirable e.g. on submarines
- Magnetic Cooling: Without cost considerations and very low
temperature requirements
|
| Compliance
Benefit: |
Use of non-ozone depleting air conditioning
and refrigeration techniques such as vapor compression using hydrocarbons,
ammonia, carbon dioxide or water; evaporative cooling; gas expansion; or
absorption will help facilities meet the requirements under 40 CFR 82,
Subpart D and Executive Order 13148 requiring federal agencies to
maximize the procurement and use of safe alternatives to Class I and Class II ODSs.
However, the use of certain
chemicals, such as ammonia and hydrocarbons, may cause the facility to
comply with other SARA-reporting issues.
The compliance benefits listed here are only meant to be used as general guidelines and
are not meant to be strictly interpreted. Actual compliance benefits will vary depending on
the factors involved, e.g., the amount of workload involved.
|
| Materials Compatibility: |
The chemical compatibility of plastics and
elastomers should be considered before retrofitting. Gaskets, shaft seals,
and o-ring materials should be reviewed with the equipment manufacturer
before retrofitting. Check with the appropriate authority prior to using a
new process.
|
| Safety and
Health: |
Consult your local industrial health
specialist, your local health and safety personnel, and the appropriate
MSDS prior to implementing any of these technologies.
|
| Benefits: |
- Vapor compression using hydrocarbons, ammonia, carbon dioxide, or
water - zero ozone depletion potential (ODP), zero global warming
potential (GWP) (except negligible for carbon dioxide and hydrocarbons),
widely available, and good thermal properties.
- Evaporative cooling (direct and indirect) - zero ODP and GWP,
high efficiency in dry climates, provides humidity, improves indoor air
quality, high air flow rates, commercially available, life cycle is cost
effective, adaptable to various energy sources.
- Gas expansion - zero ODP and GWP, simple mechanical design,
and low capital costs
- Absorption - zero ODP and GWP, can use waste heat, reliable
(few moving parts), commercially available, most economically viable
when waste heat is available.
- Adsorption - zero ODP and GWP, energy efficient, can use
waste heat.
- Stirling Cycle - zero GWP, can be used over wide temperature
range, theoretically high efficiency.
- Air (Joule) Cycle - zero ODP and GWP, non-toxic,
non-flammable, low installation and maintenance costs.
- Thermoelectric Cooling - zero GWP, immediately available,
high reliability, small, no moving parts, wide cooling range (-100 to
+125 degrees C).
- Magnetic Cooling - zero ODP and GWP.
- Thermoacoustic Cooling - zero ODP and GWP, no moving parts.
|
| Disadvantages: |
- Vapor compression using hydrocarbons, ammonia, carbon dioxide, or
water - Ammonia and hydrocarbons are flammable, ammonia is toxic,
and water and carbon dioxide systems are generally bigger and more
expensive.
- Evaporative cooling (direct and indirect) - high equipment
costs and service requirements; usually works poorly in high humidity
climates, new techniques such as indirect evaporative cooling and use of
desiccants are expanding evaporative cooling into more humid climates;
retrofits difficult for existing vapor compression systems.
- Gas expansion - low efficiency, high refrigerant costs,
limited applications.
- Absorption - less efficient than vapor compression, Lithium
Bromide (Li Br) can be toxic.
- Adsorption -low cooling efficiency, large equipment, high
cost, not available in short term.
- Stirling Cycle - low demonstrated efficiency, significant
materials development required.
- Air (Joule) Cycle - low efficiency, high power requirements.
- Thermoelectric Cooling - low efficiency, not efficient enough
for large applications.
- Magnetic Cooling - very high costs, low efficiency,
superconducting materials required, high magnetic fields require
shielding.
- Thermoacoustic Cooling - low efficiency, still requires long
term development.
|
| Economic
Analysis: |
The costs incurred will
vary significantly depending upon the alternative being used and the
system being installed or retrofitted. The economics of each alternative
must be looked at in a case by case basis.
|
| NSN/MSDS:
|
None identified.
|
| Approving
Authority: |
Appropriate authority for making process changes
should always be sought and obtained prior to procuring or implementing any of the technology identified herein.
|
| Points of
Contact: |
EPA:
The EPA publishes a complete
listing of all refrigerants that are authorized as substitutes for CFC and
HCFC refrigerants. A copy of this listing is available on the World Wide
Web at:http://www.epa.gov/ozone/snap/lists/index.html (requires
use of an Adobe Acrobat PDF viewer)
For more information
|
| Vendors: |
This is not meant to be a complete list, as there may be
other suppliers of this type of equipment.
Goettl Air Conditioning, Inc.
3830 East Wier
Avenue
P.O. Box 52029
Phoenix, AZ
85072-2029
Phone: (602) 275-1515
FAX: (602)
470-4275
URL: http://www.goettl.com
Service: Evaporative Cooling
York International Corporation
631 South
Richland Avenue
P.O. Box 1592
York, PA
17405
Phone: (717) 771-7890
FAX: (717) 771-7381
Service:
Absorption Cooling
McQuay International
13600 Industrial Park
Blvd.
Minneapolis, MN 55441
Phone: (763)
553-5330
Service: Evaporative
Cooling
|
| Related Links: |
None
|
| Sources: |
Ms. Alison Chirkis, Tinker AFB, January 1998.
Mr.
Pete Mullenhard, Shipboard Environmental Information Clearinghouse,
June 2002.
http://navyseic.dt.navy.mil/, January
1998. |
