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Ammonia
has been successfully used as a refrigerant in industrial refrigeration plants
for over 130 years. It is a colourless gas, liquefies under pressure, and
has a pungent odour. Ammonia has no ozone depletion potential (ODP = 0) and no
direct global warming potential (GWP = 0). Thanks to its high energy efficiency,
its contribution to the indirect global warming potential is also low. Ammonia
is flammable and is toxic to skin and mucous membranes when highly pressurised.
However, its ignition energy is 50 times higher than that of natural gas and ammonia
will not burn without a supporting flame. Due to the high affinity of ammonia
towards (air) humidity it is rated as "hardly flammable". Ammonia is
toxic, but has a characteristic, sharp smell which makes a warning below concentrations
of 3 mg/m³ ammonia in air possible. This means that ammonia is evident at
levels far below those which endanger health. Furthermore ammonia is lighter than
air and therefore rises quickly.
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Characteristics| ODP | 0 | | GWP | 0 | | Appearance | colorless | | Odor | distinctive,
biting | | Solubility
in water (20 ºC, 1 bar) | 0.517
kg or 650 l(g)/l water | | Heat
of solution | 36
kJ/mol | | Molecular
weight | 17.03
kg/kmol |
| Boiling
point (1.013 bar) |
-33,3
ºC |
| Density of saturated vapour (20 ºC) |
6.7025
kg/m³ |
| Thermic
decomposition | >
450 ºC | | Explosibility
limits | 15
Vol.-% to 34 Vol.-%
108,000 mg/m³
to 240,000 mg/m³ | | Ignition
temperature | 650
ºC | | Ignition
energy (20 ºC, 101 kPa) | 14
mJ | | Water
content in the cycle | of
minor importance | | Perception
threshold | 5
ppm 3,5 mg/m³ | | MAK-Value | 50
ppm 35 mg/m³ | | Nuisance
threshold | 250
ppm 175 mg/m³ | | Tolerance
threshold | 500-1,000
ppm 350 -700 mg/m³ | | Signs
of poisoning | 2,500
ppm 1,750 mg/m³ | | Fatal
dose | >
5,000 ppm 3,500 mg/m³ | | Long-term
effects | not
carcinogenic, not mutagenic | | Concentration
in human blood | 0,8-1,7
ppm | | Daily
production in the human body | 17
g ˜ 1 mol | | Water
hazard class | 2,
ID No. 211 |
| Evaporation
enthalpy at 0 ºC |
1,262
kJ/kg |
| Vapor
pressure at 0 ºC |
4.29
bar |
| Compression
ratio at 0 / 35 ºC |
3.15 |
Volumetric
refrigerating capacity
at 0 / 35 ºC |
3,798.2
kJ/ m³ |
| Isentropic
refrigerating capacity number 0 / 35 ºC |
6.75 |
| Isentropic
final compression temperature 0 / 35 ºC |
82.6 ºC |
Heat
conductivity of the liquid
at 0 ºC |
518.5 * 10-3
W/mK |
Kinematic
viscosity of the liquid
at 0 °C |
2.66 * 10-7 m²/s |
| Heat
transition (evaporation, condensation) | Very
high |
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