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| Carbon
dioxide has a long history in refrigeration, extending well into the 19th century.
It is a colourless gas that liquefies under pressure, with a slightly sour odour
and taste. Carbon dioxide has no ozone depletion potential (ODP = 0) and negligible
direct global warming potential (GWP = 1) when used as a refrigerant in closed
cycles. It is non-flammable, chemically inert and heavier than air. Carbon dioxide
is only narcotic and harmful to human health at very high concentrations. Because
carbon dioxide has a lower critical temperature than other refrigerants, recent
research has focused particularly on optimizing plant engineering, and more and
more effective refrigeration plants are being developed to close this gap. Carbon
dioxide is available in abundance, and there is no need for recycling or waste
disposal. |
|
Characteristics| ODP | 0 | | GWP | 1 | | Appearance | colorless | | Odor | slightly
sour | | Molecular
weight | 44.01
kg/kmol | | State
at 20 ºC | gaseous | | Triple
point | -56.6
ºC at 5.18 bar | | Boiling
point | -78.5
ºC | | Critical
temperature | 31
ºC | | Critical
pressure | 73.8
bar | | Explosibility
limit (in air) | n.a.
| | Ignition
temperature | n.a.
| | Density,
gaseous (15 ºC, 1 bar) | 1.85
kg/m³ | | Relative
density, gaseous (air = 1) | 1.53 | | Density,
liquid (-37.22 ºC, 11.146 bar) | 1,101.1
kg/m³ | | Solubility
in water (20 ºC, 1 bar) | 1,500
mg/l |
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