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Liquid or gas used to absorb and reject heat
Ammonia
 A gas that is quite easily changed to a liquid at a low
temperature with a favorable latent heat of vaporization
 Naturally occurring and biodegradable
“Freon” type gases
 Manufactured
 Many have damaging side effects on the environment
Others
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Why AMMONIA as a Refrigerant?
• Energy Efficient
• Inexpensive, worldwide
availability
• Excellent Thermodynamic
Properties – low pressure
• Non-miscible with oil – energy
efficient, easy to manage
• Environmentally Friendly
IIAR Standards ● For the Safe and Efficient Use of Natural Refrigerants
Refrigerant
%
Ammonia
100
COP
4.76
Net Refrigerant Effect
BTU/lb
Refrigerant circulated)
(lbs/min
474
.12
R22
98
4.66
70
.81
CO₂
56
2.69
57
.51
Propane
95
4.50
120
.47
R507
88
4.18
47
.47
Example: @ +20°F suction, 95°F condensing
 Ammonia – 1.076 Horsepower/TR
 R410a – 1.228 hp/TR
 R32 – 1.194 hp/TR
 R1234yf – 1.212 hp/TR
 CO2 – 1.70 hp/TR
An Example Facility: about 100,000 sq. ft. cold storage, no freezing
functions or other process – 500 Tons of Refrigeration
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Ammonia = $369,935/year
R410a = $422, 195 / year
R32 = $410,505 / year
1234yf = $416,694 / year
CO2 = $584,472 / year
Compression power only, NOT including pumping power!
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Ammonia:
 toxic, “mild” flammability
 Regulations
 Shortage of Experienced
Technicians
 Expensive to build, maintain
Synthetics
 Not as efficient
 Toxic when burned
 Latest are also “mildly flammable”
 No smell – possible asphyxiants,
easy leaking
 High or higher GWP
 Expensive, unavailable
 Fractionation
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Hydrocarbons
 Very flammable
 Expensive – explosion proof
electrical equipment
Carbon Dioxide
 Limited efficiency range
 High pressure
 Very dependent on clean systems
 Tricky service procedures
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Largely because of odor and noxious
effects, ammonia has an image problem
Freon gases were regarded as the “safe”
refrigerants for years until environmental
issues of global warming and ozone
depletion took the forefront
Fatality rates of ammonia and Freon are
equal – by law, ammonia is reported, thus
adding to the image problem…also
ammonia is widely used in other
industries.
Ammonia WARNS !
Because Ammonia
STINKS !
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From 860 chemicals evaluated for refrigeration in the
space program, ammonia scored highest
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It’s as natural as water…simple molecule of nitrogen and
hydrogen
Superior physical properties
Stability
Relative toxicity
Relative flammability
Compatibility with materials, gaskets, etc.
Price, Availability
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Fatalities (average per year during the past 12
years for air conditioning and refrigeration
applications only) –
 Halocarbons ~ 2 per year
 Ammonia ~ 2 per year
Nitrogen is used for industrial pressure testing
and inerting processes with a fatality rate of 8 per
year. (ref. Chemical Safety Board)
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A relatively short time ago, many believed
natural gas was too dangerous for widespread
use
They added odorant to natural gas !
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Nevertheless, natural gas continues to have
safety issues…
And don’t forget propane…
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