Oxygen generator on cooled EGR only inake?

[cRiPpLe_rOoStEr]

Why would anyone be willing to add more CO² than what an EGR already does?

[rmay635703]

Originally Posted by some_other_dave

Umm, how do you propose to remove all nitrogen from the air going into the engine? N2 is roughly 70% of what goes into the engine to start with. Even after adding hydrocarbons and then combusting them, you'll still have around 70% of it is nitrogen of one form or another, mostly N2.

Just routing exhaust gas (cooled or not) into the intake won't substantially change the amount of N2 going through the system, since you'll be displacing 70% N2 air with 70% N2 exhaust.

If you could eliminate NOx, that would enable lean mixtures for good fuel economy. But it's hard to see how this would accomplish it.

-soD

It is possible to separate polar/magnetic/charged substances in air from non polar ones with a charged stack of sorts. (Albeit not 100% effective)

One would need to question if the power draw to divide CO, CO2 and NOx (along with reactive compounds and h2o from the remaining exhaust would be excessive, ignoring the obvious cost and weight of equipment and potential to clog it with soot. The “polar” compounds could then be reintroduced to the intake stream.

Without a way to separate CO2 from the rest you would choke out the engine
Being polar and charged there may be a means to separate the NOx from uncharged materials like CO2, would have to think about it, NOx should be attracted more to a HV charged plate than CO2, not sure how that could be leveraged effectively.

[Isaac Zachary]

Originally Posted by cRiPpLe_rOoStEr

Why would anyone be willing to add more CO² than what an EGR already does?

My idea was to completely replace nitrogen based air with CO2 in order to completely eliminate NOx emissions.

The idea goes like this.

1. Feed CO2 (and water vapor) into the intake.
2. Add oxygen and fuel. (The hard part is getting pure oxygen efficiently to make up about 20% of the mix)
3. Burn in a traditional gasoline or diesel style combustion cycle.
4. Take exhaust and cool it, remove liquid water.
5. Feed cooled exhaust (now mostly CO2 and water vapor) back into the intake for an unlimited supply of CO2.

The theoretical result being able to run as high CR, lean bien, timing advance, etc, as possible without having to worry about NOx emissions.

[rmay635703]

High levels of oxygen can cause otherwise inflammable materials to spontaneously ignite.

CO2 chokes (retards) the flame in relatively small amounts , the two together would ???
There would need to be some happy medium

In effect you are building a rocket or welder the two gases are moderately expensive and onboard production would be $$$ and heavy, likely power intensive as welll.


That said because people are considered too incompetent to fill a water bottle on a car engineers are working on recovering water from exhaust to direct inject at various points during combustion to improve fuel economy and emissions.

https://journals.sagepub.com/doi/abs...68087420933124

https://www.greencarcongress.com/201...-20101015.html

[Isaac Zachary]

I think a lot aren't getting my idea.

Air is about 80% nitrogen and 20% oxygen.

The goal here would be to make an system that supplies 80% CO2 and 20% O2. The CO2 is an inert gas, just as nitrogen is an inert gas. The goal is NOT to make a highly oxygen enriched intake charge. The goal is NOT to make an extremely low oxygen level intake charge. Just keep it at 20% along with 80% inert gases like CO2.

CO2 is not hard to produce in an internal combustion engine. It's free. It's the product of burning hydrocarbons with oxygen. So is water. So the engine will continuously be supplying more than enough CO2 and water than we'll ever need. The main disadvantage is that it would require substantially more cooling.

The O2 would be the hard stuff to produce. O2 air separators are expensive, and require substantial power. But just like anything, this would start out first as an experiment. The question is, could the benefits of not having to deal with NOx outweigh the efficiency penalty of separating O2 out of the air. If that could be established, then the question becomes if cost can be reduced enough to make it feasible for mass production.

[cRiPpLe_rOoStEr]

Originally Posted by Isaac Zachary

The goal here would be to make an system that supplies 80% CO2 and 20% O2. The CO2 is an inert gas, just as nitrogen is an inert gas. The goal is NOT to make a highly oxygen enriched intake charge. The goal is NOT to make an extremely low oxygen level intake charge. Just keep it at 20% along with 80% inert gases like CO2.

CO2 is not hard to produce in an internal combustion engine. It's free. It's the product of burning hydrocarbons with oxygen. So is water. So the engine will continuously be supplying more than enough CO2 and water than we'll ever need. The main disadvantage is that it would require substantially more cooling.

Would be quite interesting if you could insert the purified O² inside the cabin and recover the CO² from it.

The O2 would be the hard stuff to produce. O2 air separators are expensive, and require substantial power. But just like anything, this would start out first as an experiment. The question is, could the benefits of not having to deal with NOx outweigh the efficiency penalty of separating O2 out of the air.

Considering it would probably require more energy than any increase it could lead the engine output to have, it might be as hard to justify as those HHO generators.

[Ecky]

The immediate issue I see with the practicality of this (and I know I'm late to the thread) is the volume of oxygen.

Peak, a 2.4L engine like as is in my car, pumps 2.4L of air through per revolution. Assuming we want to feed it pure oxygen at 20% of the volume of the air that would normally pass through it (0.48L per revolution), the oxygen generator would need to be able to produce over 200,000L per oxygen per hour.

A quick google search suggests that the typical home oxygen concentrator can produce 3L per minute and uses around 120w. This suggests that, to feed my engine pure oxygen, there would be an electrical cost of 150,000w, or approximately 200HP - the approximate full mechanical output of my engine when using that oxygen, without conversion losses accounted for.

[Isaac Zachary]

Originally Posted by Ecky

The immediate issue I see with the practicality of this (and I know I'm late to the thread) is the volume of oxygen.

Peak, a 2.4L engine like as is in my car, pumps 2.4L of air through per revolution. Assuming we want to feed it pure oxygen at 20% of the volume of the air that would normally pass through it (0.48L per revolution), the oxygen generator would need to be able to produce over 200,000L per oxygen per hour.

A quick google search suggests that the typical home oxygen concentrator can produce 3L per minute and uses around 120w. This suggests that, to feed my engine pure oxygen, there would be an electrical cost of 150,000w, or approximately 200HP - the approximate full mechanical output of my engine when using that oxygen, without conversion losses accounted for.

Is that a 2 stroke? Only 2 stroke engines pull in approximately their displacement per revolution if naturally aspirated. A 4 stroke only pulls in half. So only 0.24L would be needed per revolution. At 1,000 RPM you'd need 240L per minute. At 5,000RPM you'd need 1,200LPM.

Anyhow, you are still right to a point. A 1,200LPM VSA type industrial oxygen concentrator would still need about 40kW of power to put that much O2 out. Not to mention the huge size and cost. (PSA types would not work. A 1,200LPM PSA O2 concentrator would need about 80kW.)

[Ecky]

4 stroke, of course. It's late and I knew something was up with my math.