Fact Sheet: Hydrocarbons (natural refrigerants)

Refrigeration plants using hydrocarbons like propane (R290, C3H8), propene (R1270, C3H6) or iso-butane (R600a, C4H10) have been in operation all over the world for many years. Hydrocarbons are colourless and nearly odourless gases that liquefy under pressure, and have neither ozone depletion potential (ODP = 0) nor significant direct global warming potential (GWP < 3). Thanks to their outstanding thermodynamic characteristics, hydrocarbons make particularly energy efficient refrigerants. Hydrocarbons are flammable, however, with current safety regulations, refrigerant losses are near zero. Hydrocarbons are available cheaply all over the world; thanks to their ideal refrigerant characteristics they are commonly used in small plants with low refrigerant charges.

Characteristics:

Characteristics of propane

ODP 0
GWP 3
Appearance colorless
Odor nearly odorless
Molecular weight 44.09 kg/kmol
Physical condition at 20 ºC gaseous
Freezing point -186 ºC
Boiling point -42 ºC
Explosibility limit (in air) 2.2-10.0 %
Ignition temperature 470 ºC
Density (liquid, near boiling point) 0.585 g/cm³
Relative Liquid Density at 15 ºC 0.50-0.51
Relative Gaseous Density compared with air at 15 ºC and 1013.25 mbar 1.40-1.55

Characteristics of butane

ODP 0
GWP 3
Appearance colorless
Odor slightly sour
Molecular weight 58.12 kg/kmol
Physical condition at 20 ºC gaseous
Freezing point -135 ºC
Boiling point -0.5 ºC
Explosibility limit (in air) 1.8-9.0 %
Ignition temperature 365 ºC
Density (liquid, near boiling point) 0.601 g/cm³
Relative Liquid Density at 15 ºC 0.57-0.58
Relative Gaseous Density compared with air at 15 ºC and 1013.25 mbar 1.90-2.10