Thread: a higher energy output for gasoline?

Here is a question that has kept my mind busy for a long time.

If you use an acetylene torch, and you only open the gasvalve and then light it, you will obtain a flame that is not very hot.
You open the oxygenvalve and now you wil have a flame hot enough to weld steel, you may even have to close the gasvalve a little because the flame is to big.
You get alot more energy out of it.
So my question is: Would this be possible to use with for example a car engine ? Mixing the gasoline with pure oxigen that is.

I am no scientist so I can't calculate it.
But if one presumes that is does have this effect, than I was thinking of the following construction.

Take a car engine with an output of 100 (Kw, HP, whatever)
To this engine is attached a large dynamo, this will use power from the engine, lets presume 20 from the hundred.
So you are left with an output of 80. The dynamo wil produce Hydrogyn and Oxygen through electrolyses of water.

The produced Hydrogyn will go to a smaller engine that acts as a generator, so this H is combusted with outside air.
The generator wil also electrolyse water, and the H it produces will be used as fuel for the generator, the generator will have its max output now.

The O produced by the ddynamo and the generator wil be fed into the car engine, so the gasoline intake can be reduced because of the
higher energy output that you get from a Gasoline and oxygen mixture.

OK everybody take out your shotguns and shoot the idea to smithereens.

By using pure oxygen in an internal combustion engine you will of course have a much higher combustion temperature and will have to redesign the materials and cooling system. You will also have a much smaller volume of combustion products (since you have removed the nitrogen which is 79% of the air you started with), so you will need tiny little pistons and cylinders. In other words you need a completely new design of engine, not a slightly tweaked existing one.

There are also safety issues with pure oxygen - a little oil in an oxygen transfer pipe will result in a fire.

The economics of pure oxygen seem highly dubious for a car engine. A more practical approach might be to consider moderate oxygen enrichment of the combustion air.

Turbo chargers and supechargers do something similar to what your talking about; increasing the air flow into the cylinders, thus increasing the oxygen. Pure oxygen would be too dangerous.

Thanks for your comments!

In rereading my post i saw that I gave the impression of a pure Oxygen and Gasoline mixture

As a matter of fact it should read like a mixture of Gasoline and Air with extra Oxygen added.

So I understand from your replies that such an engine configuration is more fuel efficient



If this is the case then there would be a lot of calculating would be needed to find a balanced configuration.

So I understand from your replies that such an engine configuration is more fuel efficient

It would probably be more thermodynamically efficient. However that doesn't take into account the inefficiencies of producing oxygen or of carrying an air separation plant around on the vehicle, or the cost of manufacturing engines that can handle higher temperatures, or of removing NOx which tends to be produced more at higher temperatures. In general the maximum amount of oxygen enrichment you can do before running into materials and safety issues is quite small (maybe up to about 29% O2). This is done all the time in some types of industrial furnace, usually with a cryogenic air separation plant over the fence selling oxygen to the plant.

a lot of calculating would be needed

Indeed.

look at the browns gas crew...........they always have to change the Lambda sensor to ignore the extra oxygen.......so make a cell and then you can experiment to use that extra oxygen

but yes it will burn hotter as essentially the fuel ignites with the oxygen and produces CO2 - so you will need to put in more fuel which will generate more heat and power..........just like a super/turbo charger.............

if you want to use different chemicals then that is a more interesting story.........

but I am afraid if you don't mind me saying you are not actually doing anything to get a higher output from any specific chemical...........just putting more stuff in :P

The idea of greater efficiency comes from the fact that you are not using chemical energy of the fuel to heat up lots of nitrogen and then spewing it out the tailpipe. This may or may not be beneficial. Maybe the mass flow of nitrogen provides more output than the higher temperature of a smaller volume. Maybe also the smaller size of cylinder needed makes flame propagation quicker and so uses the fuel more effectively (tending towards diesel efficiency). I dunno. Jes' speculatin'.

Originally Posted by stlekee

Turbo chargers and supechargers do something similar to what your talking about; increasing the air flow into the cylinders, thus increasing the oxygen. Pure oxygen would be too dangerous.

Turbochargers and superchargers basically put more gas/air mixture into the cylinder for each combustion stroke and thereby increase power. They also serve to assure adequate oxygen supply at altitude. They are not particularly effective at increasing efficiency, except in cases in which the air is sufficiently thin that a normal gas/air mixture is not possible without them.

Once you have a stoichiometric mixture in the cylinder you will extract all of the available chemical energy. If you eliminate the inert nitrogen, you get a small efficiency gain simply because you need not use some of that energy to heat the inert nitrogen and hence have a gas at a higher initial temperature to expand in the power stroke, and therefore there is potenatial for a small efficiency gain.

But the downside of using pure oxygen outweighs any potential efficiency gain. The downsides include: 1) a need to carry a supply of oxygen which adds weight to the vehicle 2) a need to produce the oxygen in the first place which will almost certainly make the entire cycle a net energy loser 3) the extreme danger of having pure oxygen on board in the event of a crash 4) the deleterious effect of pure oxygen in a hot environment on the engine.

yep - Apollo 1 was a disaster because of pure oxygen...........and a lack of basic chemistry safety it would seem...................

Forgive me if I am wrong but I would have said that the nitrogen makes the combustion more thermally efficient as the heat from the oxygen-petrol reaction causes expansion where it counts the most, then the rest of the heat goes out the exhaust.........

Dr. Rocket is correct but many people are working on basically getting more stuff to expand in the cylinder to use the heat energy more efficiently.........such as using plain old water in the reaction to get energy from its expansion..................

Originally Posted by fatman57

such as using plain old water in the reaction to get energy from its expansion..................

The energy you get from its expansion comes from cooling the combustion gases. It can stop pinging but overall probably won't increase efficiency.

there is a guy currently trying to get a patent..........fuel economy goes way up and emissions down..............the expansion of water into steam creates all this 'extra' energy..........

I'm sure he has a plan to do something for the catalytic converter as the exhaust gases are both much cooler and filled with water which apparently damages them..............

there is a guy in India doing it with Air - he has one engine leading into another and the hot exhaust from the fossil fuel engine expands fresh air in another - he is currently using it commercially.............

Originally Posted by fatman57

the expansion of water into steam creates all this 'extra' energy

No, the expansion of water into steam converts chemical energy into PV energy. No energy is being created.

thats why its in inverted commas, its what i meant.

Originally Posted by fatman57

yep - Apollo 1 was a disaster because of pure oxygen...........and a lack of basic chemistry safety it would seem...................

Forgive me if I am wrong but I would have said that the nitrogen makes the combustion more thermally efficient as the heat from the oxygen-petrol reaction causes expansion where it counts the most, then the rest of the heat goes out the exhaust.........

Dr. Rocket is correct but many people are working on basically getting more stuff to expand in the cylinder to use the heat energy more efficiently.........such as using plain old water in the reaction to get energy from its expansion..................

Water is not used to increase efficiecy. It is used to increase octane number and prevent detonation (knocking) -- this technology goes back at least as far as World War II where it was used in the engines on the B 17.

The key to increasing the efficiency of expansion from gas of a given temperature is to make the ratio of specific heats as close to 1 as possible. That will make the ability to extract work from the isentropic expansion of the combustion gasses as efficient as one can make it. The other means to increase thermodynamic efficiency is to maximize the temperature of those gasses.

Originally Posted by fatman57

thats why its in inverted commas, its what i meant.

OK then.

Originally Posted by DrRocket

Water is not used to increase efficiecy. It is used to increase octane number and prevent detonation (knocking) -- this technology goes back at least as far as World War II where it was used in the engines on the B 17.

The key to increasing the efficiency of expansion from gas of a given temperature is to make the ratio of specific heats as close to 1 as possible. That will make the ability to extract work from the isentropic expansion of the combustion gasses as efficient as one can make it. The other means to increase thermodynamic efficiency is to maximize the temperature of those gasses.

I know that you are correct - i'm just reporting what this guy is doing with it......apparently it works very well...........