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Nitrous oxide ?

  1. May 22, 2010 #1
    Instead of drag racers injecting nitrous oxide and extra fuel with it .
    Why don’t they just inject liquid oxygen with more fuel . for more power ,
    Any input will be much appreciated.
     
  2. jcsd
  3. May 23, 2010 #2

    alxm

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    So, the amount of energy available from complete combustion of a given amount of fuel in oxygen is constant. You can't do better than complete combustion, so having too much oxygen means less than optimal performance. Likewise, having too much fuel (for a given cylinder size) means more incomplete combustion, and also less than optimal performance.

    Now if you use N2O as your oxidant instead, you get even more energy, since you're essentially getting the original energy plus the energy from the decomposition of N2O into nitrogen and oxygen. So using nitrous as an oxidant increases performance in itself, as well as increasing the amount of oxidant/volume in your inflow and allowing you to use more fuel for a given cylinder size.

    Now your question seems to be: Why not add pure oxygen and more fuel instead? Well, that would work, but you'd only get the latter benefit.

    It's also impractical. Oxygen can't be stored efficiently. Oxygen has a boiling point of -182C, nitrous oxide −88C, and oxygen has a much higher vapor pressure. I.e. in practice, oxygen canisters contain compressed oxygen, whereas nitrous oxide canisters contain liquid nitrous, and thus store much much more gas per volume.

    So not only does nitrous oxide give you more energy than adding O2, it's also a lot more practical to do so.
     
  4. May 23, 2010 #3
    ok thanks for your answer , And when they inject N20 the cold nitrous condenses the air and makes it more dense so it can pack more oxygen into the cylinder , and then when the fuel burns and it gets hot enough the nitrous will decompose giving off more energy.
     
  5. May 24, 2010 #4

    alxm

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    Well, strictly speaking I don't think the nitrous only decomposes, it can oxidize the fuel directly as well, so there's a whole bunch of reactions going on.

    But thermodynamically you can simply calculate the total energy as the sum of N2O decomposition and the oxygen-fuel combustion energy. Conservation of energy is convenient that way.
     
  6. May 24, 2010 #5

    chemisttree

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    Pure oxygen would cause the fuel air mix to explode in the intake manifold. Too reactive.
     
  7. May 24, 2010 #6
    ya i think someone else told me liquid oxygen would blow the head off the motor.
     
  8. May 25, 2010 #7

    chemisttree

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    Where the oxygen comes into the intake manifold it would become an http://www.thermolance.com/Thermolance_Oxygen_Lance/thermolance_oxygen_lance.htm" [Broken] BAD JU JU!
     
    Last edited by a moderator: May 4, 2017
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