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The other consideration is that if you take out the nitrogen you will (as is presumably your plan) create an oxygen rich atmosphere. If I recall correctly, in a 40 % oxygen atmosphere meat (and therefore human flesh), once ignited, will sustain burning. Which is not necessarily a good idea.
I ask as I'd like to experiment with feeding a car engine this way!
Nitrogen gas is chemically pretty stable. Although nitrogen containing molecules are crucial to biology, relatively few organisms have evolved the ability to capture it and make it biologically available. I'm afraid the only way I know of extracting the stuff from air is to cool the air to below the boiling point of nitrogen (-196 oC ish), and then allow the liquid oxygen to boil off (b.p. about -182 oC). Pretty difficult without specialist cooling apparatus.
Anyone know a crude way of making air have a lower percentage of nitrogen?i.e A method that an amateur could setup.I ask as I'd like to experiment with feeding a car engine this way!
You will kill the engine but if you insist.http://www.nda.ox.ac.uk/wfsa/html/u01/u01_009.htmHave fun plugging it in.
The reasons I'm interested in such a process has several themes:firstly I'm currently running my (1960's) car with a smaller carb, which gives a leaner mixture & it works fine! However I'm aware I've probably increased my level of NOx in the exhaust. So, Idea 1: don't introduce nitrogen in the 1st place.
Second, weakening the mixture further or using a lower calorific fuel (get back to you this one!) plus a richer oxygen atmosphere should create an equal Bang in the cylinder (to a point - today's car engines use leaner burning mixtures anyway). Idea 2: remove the inert gas from the reaction - particularly as an old carburettor based car gives poor fuel/air mixing to start with.
Clearly, as mixture changes, so does ignition timing - which will have to be worked out as I go. Also I have no wish to damage the engine through the process, but my gut feeling is if there is less fuel - less heat can be created. I ought to mention that I am aware that weakening a car's mixture (slightly) has a tendency to make the engine hotter! - maybe someone could explain this to me also! (or should I start another thread..)
Quote from: peppercorn on 23/08/2007 14:48:57The reasons I'm interested in such a process has several themes:firstly I'm currently running my (1960's) car with a smaller carb, which gives a leaner mixture & it works fine! However I'm aware I've probably increased my level of NOx in the exhaust. So, Idea 1: don't introduce nitrogen in the 1st place.In this case you shouldn't use nitrogen at all, that is, you should use pure oxygen (or the amount of NOx wouldn't reduce, possibly would increase); but then you'll have detonation (even if the amount of O2/fuel mix is little to prevent engine breaking/melting).
Quote from: peppercorn on 23/08/2007 14:48:57Second, weakening the mixture further or using a lower calorific fuel (get back to you this one!) plus a richer oxygen atmosphere should create an equal Bang in the cylinder (to a point - today's car engines use leaner burning mixtures anyway). Idea 2: remove the inert gas from the reaction - particularly as an old carburettor based car gives poor fuel/air mixing to start with.It's better to reduce the compression ratio.
Quote from: peppercorn on 23/08/2007 14:48:57Clearly, as mixture changes, so does ignition timing - which will have to be worked out as I go. Also I have no wish to damage the engine through the process, but my gut feeling is if there is less fuel - less heat can be created. I ought to mention that I am aware that weakening a car's mixture (slightly) has a tendency to make the engine hotter! - maybe someone could explain this to me also! (or should I start another thread..)What does "weakening" mean? It means to lean it? In this case the reason is that the combustion's speed is reduced, so the spark it's too delayed and the heat produced cannot be efficiently converted into mechanical energy, so the engine heats up; it could also burn through the pistons.
Without the N2 the flame burns hotter (because it doesn't waste energy heating N2).The yield of NOx will rise with the temperature unless you totally remove the N2.I guess you could try adding Ar or something.