Quote:
Originally Posted by smallscaleH2
According to this site,
hydrogen has 50,000 Btu's per pound whereas Brown's gas has about 66,000 Btus per pound. So, that means it would (presumably) be 32% more energetic (etc) |
Since you derived the idea from my quote I feel entitled to comment, with trepidation.
That statement there is bunk; it is wrong at several levels. That whole website is complete nonsense. And here is why:
It does not matter if the oxygen comes from the air or is contained within the gas itself when it comes to calculating BTU's. Oxygen is just the reactant that oxydates (!) the hydrogen. Only the hydrogen counts as fuel.
Hydrogen has an atomic weight of about 1 unit per atom. Hydrogen gas consists of molecules made up with 2 hydrogen atoms, weighing 2 units per molecule.
Oxygen has an atomic weight of about 16. A molecule of oxygen is 16 times as heavy as a hydrogen molecule; as both are perfect gases, per volume oxygen is 16 times as heavy as hydrogen gas.
Browns gas is a mixture of 2 molecules of hydrogen for every molecule of oxygen. Therefore it is 2/3 + 16/3 = 6 times as heavy as hydrogen, and it only has 2/3 of the hydrogen molecules.
So Browns gas has just 1/9th or 11.111% of the BTU pure hydrogen gas has per weight, and just 2/3ds or 66.666% of the BTU per volume.
So while Brown's gas is less powerful as a combustible than you think, the real problem is that, in essence, it is not a combustible at all. It is an explosive, and as an explosive it has no equals when it comes to bang per weight.
When it explodes it will not complete the reaction; the temperature gets so high that some of the hydrogen and oxygen start to lose their bonds again, and the reaction will only complete when it can shed its heat or mix with the surrounding gases.
Hence the tendency of these mixtures to create a whistling sound when exploding; the gas blows out only partly fused to water molecules, creates a vacuum that though extremely hot, still sucks back in the gas, which lost some heat on the way out and back in, reacts again; blows out, new vacuum, etc.
It may seem strange that such an explosive gas contains only so much power. But a simple gasoline engine uses 14 times the weight of the gasoline it uses on air. That is a lot of air for a little bit of gasoline.
Compared to Browns gas, you exchange the non-combustible oxygen atoms with the same amount of carbon atoms, who are very much combustible - and lighter than oxygen to boot.
Now you wanted to use it as the sole fuel in a diesel engine.
Well, diesel engines ignite by pressurizing the air-diesel mixture to beyond the detonation point. But it won't fire all in one go; it burns slowly enough to spread the bang so it won't knock too hard. Because diesel is a mixture of long and short hydrocarbons it will not all react at once.
If you would get the detonation point right with Brown's gas (if that is possible!) then the reaction would complete or reach its plasma phase within a fraction of a millisecond. While diesel engines are sturdy, they may not be able to withstand that; and if they do, it would be very noisy indeed.
You'd need to mix in at least 3 times as much air than Brown's gas or you'd just be wasting the excess because it could not react completely. But the uncontrollable detonation remains problematic. The largest auto manufacturers break their heads trying to get the diesel-style combustion working for gasoline properly. Pure hydrogen, whether mixed with air or pure oxygen, would only be even harder.
So, it is not like your idea is sound with just a few problems to solve.
It is fundamentally wrong in all of its stages.
You should be aware that hydrogen and Brown's gas have already been researched to the bone. You cannot expect surprises there within existing fields of technology.
You certainly cannot expect to get anything useful without understanding the basics - but if you get to grips with that you'd abandon the project.
Better abandon it now, when you've not yet chanced to kill yourself nor wasted too much money.