Burning Pure Oxygen vs. "Air"

[gone-ot]

"...fill'er up with Gasoline, Oxygen, and Water please, Mr. Gas-station man!"

[jeff88]

Originally Posted by RedDevil

Hmm. Pure oxygen, atmospheric pressure, iron and heat equals Thermal lance.

Are you saying this scenario could potentially turn your engine into a thermal lance? What if we used ceramic, would that resolve that issue (take the iron out of that equation)?

Originally Posted by RedDevil

It would allow lean burn without nitrous oxide, but the unused oxygen would be a risk for the engine. If you reduce the pressure to near-vacuum then it could work, but you'd have massive pumping loss.

Lean burn means more efficient engine, right? How would oxygen end up being unused and how would it be a risk, explosion? How would pumping losses occur if the oxygen is DI? Obviously, there is an issue with exhaust still.

I wonder if water injection would be possible, with a condenser. How large of a storage tank would be needed to be able to store enough water to inject, "burn", exhaust, condense, repeat, without running out of water. Would the same amount of water need to be "injected" per cycle no matter what the speed of the engine is? In my mind, a system without water would be better, but how to do that without any associated risks. Would this system not work with a standard water/coolant and radiator system?

Originally Posted by jamesqf

There are engines that use pure oxygen: http://ecomodder.com/forum/showthrea...cle-25557.html Don't think anyone has ever done a smog check on one, though: [url]

I could just imagine NASA taking their rockets/shuttles to a local smog Check Only station!

Originally Posted by sheepdog 44

It seems the problem is oxygen storage. As a scuba tank full of pure oxygen could only give a 10% increase in oxygen over the course of one gallon of gasoline. In the case of a prius, since it's fuel efficient you get more bang for your oxygen buck. You can get a 125% increase in oxygen for 16 miles, or a 150% increase for 8 miles. Which means if there were no oxygen in the atmosphere at all (only nitrogen), you'd have enough oxygen in your scuba tank to drive your car for just 4 miles!

My idea is to not store the oxygen at all, but "produce" it on-demand.

Originally Posted by sheepdog 44

You wouldn't need a super strong engine per se to keep it from melting. You'd just need to run your engine 5X as lean as it normally runs. But if your'e only compressing and expanding oxygen, then there might be issues as RedDevil says.

So are you saying to run it at somewhere in the ballpark of 60:1? Wouldn't that also help make the engine more efficient? What else can you do besides compress and expand, are you referring to the intake and exhaust strokes?

Originally Posted by RustyLugNut

The direct injection of pure oxygen and fuel/water means you do not need an intake valve. You could run the engine as a two stroke.

The sub-idea of this scenario is definitely the use of direct injection. Much more efficient and if not, at the very least, more control. What would be the benefit of running it as a two stroke? Does the extra two strokes cause essentially a parasitic load on the engine, which is eliminated with two strokes?

Originally Posted by RustyLugNut

Yes, under full load, you can inject your oxy/fuel/water to maximize temperature and pressure. But, you then have the option under light load to inject the minimum oxy/fuel/water and derive as much energy from it by over expansion. By using over expansion, it makes it easier to condense the water and reuse it.

What is over expansion? A little research tells me that the piston arm is higher in the cylinder during the intake stroke and lower in the cylinder during the power stroke (which I assume means less oxy/fuel/water in the cylinder during the intake stroke and a larger turn of the drive shaft on the power stroke). Is that right? How does over expansion make it easier to condense the water?

Originally Posted by RustyLugNut

RedDevil's idea of a small single piston engine is very doable. Originally, ceramic pistons, cylinders and heads were specified. However, using water as our expansion fluid means we can control peak temperatures. Ceramic coated parts would probably work. With no nitrogen present in the combustion chamber, we can run hotter than the 2300 degrees C temperature of formation for NOx to achieve higher theoretical efficiency while tempering maximum heat load via our water flow.

If we have water in the equation, do we need a ceramic coating? How hot do you think we could go without causing issues (i.e. how much heat can the water take, along with standard cooling from the radiator)?

----------------------------------------
How do we eliminate the issue of hydrolock, or is it not an issue in this?

I've already started a little diagram of what I am thinking and will get it up shortly.

[RustyLugNut]

"My idea is to not store the oxygen at all, but "produce" it on-demand."

Jeff88, what are your thoughts on this oxygen on demand?

The rest of your post is far too broken and fractured to have a proper discussion.

[darcane]

Another concern with pure oxygen is that when mixed with gasoline it will autoignite, even at atmospheric pressures. So, if it mixes in the intake manifold, you would have a fire on your hands before it even got in the combustion chamber. Direct injection would be required.

Pure Oxygen has been used on certain internal combustion engines.... Diesels. I'm not sure if it's still allowed, but they used to inject oxygen into diesels for tractor pulls. It's essentially an extremely potent version of Nitrous Oxide (N2O is 33% oxygen, oxygen is obviously 100% oxygen). It can greatly increases how much torque you can get out of your engine if you put in enough fuel to match.

[jeff88]

Originally Posted by RustyLugNut

Jeff88, what are your thoughts on this oxygen on demand?

The rest of your post is far too broken and fractured to have a proper discussion.

I'm working on a little diagram, so I will post it, because I am a visual learner more than anything.

I hope after that the fractured response to each reply will be eliminated, I was merely hoping for a response from each individual.

Originally Posted by darcane

Another concern with pure oxygen is that when mixed with gasoline it will autoignite, even at atmospheric pressures. So, if it mixes in the intake manifold, you would have a fire on your hands before it even got in the combustion chamber. Direct injection would be required.

It can greatly increases how much torque you can get out of your engine if you put in enough fuel to match.

I was working on my diagram, which already included direct injection, when I realized, 'what about auto-ignition', so I was doing a little research about it and even had the question setup in a reply so I wouldn't forget to ask about it. I guess you just beat me to it! I like the idea of auto-ignition (in the cylinder, of course), because that eliminates the need of a spark plug (and the associated items.)

More torque would mean a smaller engine would be needed, right?

[RustyLugNut]

A two stroke engine means a power stroke for every piston cycle instead of a power stroke every other piston cycle as is found in a four stroke engine. This means your engine could potentially have twice the power of a four stroke for the same displacement, all else being equal.

Over expansion is just a term to reference the ratio of compression to expansion. For normally aspirated spark ignited engines, this is commonly called the Atkinson cycle - as found in the Toyota Prius. The Prius expands through a ratio about 1.3 times greater than it's compression volume, extracting more work from the gasses. The closer your exhaust is to ambient air pressure, the more work you have potentially extracted from your fuel. Also, in your oxy/water/fuel example, the water will be easier to condense as it will be at a lower temperature and pressure.

[jeff88]

So here is a basic start to my idea. Needless to say, in no way is it anywhere near complete, nor perfected, obviously.
Here is the basic idea:

1. An oxygen concentrator draws air from behind the radiator (or wherever you want)
2. OC will compress the air and create a near 100% oxygen content which will be directly injected into the cylinder
3. At the same time, fuel will be directly injected
4. During the compression stroke, the pressure from the piston will force the oxy/gas to ignite
5. Exhaust (which I think will be hotter than a standard engine) will run a turbo
6. Turbo runs a generator
7. Power from generator supplies battery
8. Battery powers OC

Some issues:

• I doubt the turbo will be able to supply all the power to the concentrator, but hopefully it can and maybe a little bit more.
• How to "vent" the exhaust from the cylinder, other than a standard exhaust valve?
• Is water injection still necessary?

[RustyLugNut]

Originally Posted by darcane

Another concern with pure oxygen is that when mixed with gasoline it will autoignite, even at atmospheric pressures. So, if it mixes in the intake manifold, you would have a fire on your hands before it even got in the combustion chamber. Direct injection would be required.

Pure Oxygen has been used on certain internal combustion engines.... Diesels. I'm not sure if it's still allowed, but they used to inject oxygen into diesels for tractor pulls. It's essentially an extremely potent version of Nitrous Oxide (N2O is 33% oxygen, oxygen is obviously 100% oxygen). It can greatly increases how much torque you can get out of your engine if you put in enough fuel to match.

At least at room temperature and pressure.

Can you expand on this phenomena?

[RustyLugNut]

Originally Posted by jeff88

So here is a basic start to my idea. Needless to say, in no way is it anywhere near complete, nor perfected, obviously.
Here is the basic idea:

1. An oxygen concentrator draws air from behind the radiator (or wherever you want)
2. OC will compress the air and create a near 100% oxygen content which will be directly injected into the cylinder
3. At the same time, fuel will be directly injected
4. During the compression stroke, the pressure from the piston will force the oxy/gas to ignite
5. Exhaust (which I think will be hotter than a standard engine) will run a turbo
6. Turbo runs a generator
7. Power from generator supplies battery
8. Battery powers OC

Some issues:

• I doubt the turbo will be able to supply all the power to the concentrator, but hopefully it can and maybe a little bit more.
• How to "vent" the exhaust from the cylinder, other than a standard exhaust valve?
• Is water injection still necessary?

The main hindrance will be the rate of production of your oxygen concentrator. Medical devices that use pressure swing adsorption can produce up to 10 L per minute of near pure oxygen. However, they are quite large in physical size and will require wall power levels to run ( hundreds of watts ). This small amount of oxygen could run a small single piston engine but that engine will not have the exhaust energy to power a substantial turbo

[Allch Chcar]

You should look into oxygenated fuels before you look at direct injecting oxygen. Specifically, alcohols like Ethanol and Methanol. Not only are they cleaner and more efficient than Gasoline but they make more power. Their biggest disadvantages are less energy in a gallon and cold starting problems with early FFVs. Newer higher compression engines work even better and current FFVs have special startup routines in addition to more Gasoline content in the winter. The earliest FFVs were designed to run on Gasoline, E85, or even M85. Methanol has an octane value of 112 while Ethanol has an octane value of 110. But it drops to about 96 octane in E85, M85 is unknown.

Newer Direct injection engines are perfectly suited to alcohols, tuning has shown some promising results. But the market is limited and competes directly with Gasoline for market share. Plus there just isn't enough positive information about them.