Propellant

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Under propellants understands gases compressed ( compressed gases ) or liquefied under pressure are used for to promote through their pressure liquids or solid powder, sometimes another gas - possibly to sputter - or from a liquid foam inflate.

They are used as a substance component in spray cans or as a foaming agent for foam and food.

A second meaning of propellant gas means gases that are used as fuel in piston or turbine engines to turn a drive axle.

Classic propellants

Propellant gases should not enter into chemical reactions with the other substances in the mixture. The best-known propellants include:

CFCs, which were previously used in spray cans, are now banned as they are considered to be extremely harmful to the environment.

Propellant gas can be used to pressurize liquid tanks to force the liquid in and out of a line. It is the easiest way to deliver propellant or recoil material in a liquid rocket. Helium has the advantage of a very low density and that it does not condense even when pumping cryogenic liquefied hydrogen .

Propellants in the food industry

Propellants can also be found among the officially approved food additives :

Propellant gases are also used to foam up pasty-creamy foods such as cream cheese or ice cream: This not only increases the creaminess and improves the taste intensity, but also increases its volume. In addition, z. B. foamed ice cream easier to portion even at low temperatures (frozen).

Propellant gases as drive energy

In the past, the term “propellant” was also used in general for the propane / butane mixture LPG . Today, the term “propellant gas” is used more as drive energy in connection with forklifts and industrial trucks. In order to drive these vehicles, liquid gas is often used as a propellant. The use of liquefied petroleum gas as a propellant has the advantage over alternatives such as electric or diesel propulsion that propellant-powered vehicles are the only ones that can be used in closed rooms despite an internal combustion engine, as they burn relatively cleanly. This form of drive energy is also considered to be efficient, low-noise, inexpensive, environmentally friendly and very practical in daily use.

Propellant gases are also used to power turbo pumps in liquid rockets. An example of this was the A4 rocket .

Overview

Overview of propellant gases
Propellant Abbreviation according to DIN 8960 Molecular formula molar mass (g / mol) Melting point (° C) Boiling point (° C) Vapor pressure at 20 ° C (bar) Vapor pressure at 30 ° C (bar) Vapor pressure at 50 ° C (bar) Ozone depletion potential ODP (R12 = 1) Global warming potential GWP (CO 2 = 1) source
Ethyl methyl ether C 3 H 8 O 60.1 −139.2 7.4 1.601 2.3 4.1
n-butane R-600 C 4 H 10 58.12 −138.29 −0.5 2.081 2.8 4.9 0 3
Isobutane (2-methylpropane) R-600a C 4 H 10 58.12 −159.42 −11.7 3.019 4.1 6.78 0 3
1,1,1,2,3,3,3-heptafluoropropane R-227ea C 3 HF 7 170.03 −131 −17.3 3.993 9.16 0 2900
Dimethyl ether C 2 H 6 O 46.07 −141.5 −24.82 5.102 6.9 11,431 0
1,1,1,2-tetrafluoroethane R-134a C 2 H 2 F 4 102.04 −101 −26 5.7 7.7 13.2 0 1300
Dichlorodifluoromethane R-12 CCl 2 F 2 120.91 −157.8 −29.8 5.7 7.5 12.2 1 8100
propane R-290 C 3 H 8 44.1 −188 −42 8.327 10.8 17.081 0 3

Nitrous oxide ("laughing gas")		 N 2 O 44.01 −90.8 −88.5 50.599 63.2 298
carbon dioxide R-744 CO 2 44.01 −56.57 −78.5 57.3 72.1 0 1

Demarcation

If compressed air is continuously blown into pipes for the transport of dry or moist bulk material (e.g. ready-made plaster, cement), which is continuously supplied from a compressor, then we usually do not speak of propellant gas, but of compressed air .

Aluminum or wood sawdust are used as a solid propellant for foam in the - hot - production of lightweight concrete or expanded clay . Aluminum decomposes water, wood releases its water content in gaseous form.

When baking bread and pastries, gases are released from baking powder when they are heated or a CO 2 content is generated by fermentation with yeast dough , which is deposited in gaseous form in bubbles. If egg white or some soda water is added to the dough , Kaiserschmarrn is baked until it is frothy.

See also

  • Blowing agents or foaming agents for the production of foams are described in the English Wikipedia in the article Blowing agent .

Remarks

  1. ↑ Destruction of the high-lying ozone layer in the earth's atmosphere and climate-effective as a greenhouse gas.
  2. ↑ Preparation: see whipped cream # procedure
  3. ↑ LPG

Individual evidence

  1. ^ Protection of the ozone layer - CFCs and halons ( Memento of July 7, 2013 in the Internet Archive ), Federal Environment Agency
  2. ↑ CFC-Halon Prohibition Ordinance
  3. ↑ Entry on ethyl methyl ether in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  4. ↑ Entry on n-butane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  5. ^ Entry on isobutane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  6. ↑ Entry on 1,1,1,2,3,3,3-heptafluoropropane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  7. ↑ Entry on dimethyl ether in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  8. ↑ Entry on 1,1,1,2-tetrafluoroethane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  9. ↑ Entry on dichlorodifluoromethane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  10. ^ Entry on propane in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  11. ↑ Entry on nitrous oxide in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)
  12. ↑ The greenhouse gases. German Federal Environment Agency, accessed on July 4, 2019 .
  13. ↑ Entry on carbon dioxide in the GESTIS substance database of the IFA , accessed on March 31, 2014 (JavaScript required)