Ozone Enhanced Combustion of Water/Diesel Emulsion in CI Engines

[voltech444]

TL;DR Summary

Trying to determine the limits of how high a percentage of water it's possible to run a diesel engine on Water/Diesel Emulsion with ozone enhanced combustion.

I have a single cylinder 5kW diesel generator to use for fuel efficiency and emissions reductions improvement experiments. I built an emulsifier out of an old drill press and paint cans. It's basically just a spinning cylinder inside another cylinder to get a lot of shearing force.

The experiments I'm doing is seeing if I can get this diesel generator to run on water/diesel emulsions, with up to 70% water. I want to determine how much ozone is needed to support combustion of high water percentage Water/Diesel Emulsion.

I've found several papers going back over the last decades about improving the efficiency and emissions of compression ignition engines. It's well documented that water injection, Water/Diesel emulsions, and ozone can be very beneficial for CI engines when utilized properly.

I've read papers where they increased efficiency by 10% and significantly reduced emissions by using water injection or emulsions alone. I've seen similar results with ozone or oxygen enrichment. I've also found 2 papers that experimented with combining ozone enrichment and Water/Diesel emulsions; both had very encouraging results.

Combining these two methods together can produce some incredible results. There's a point of diminishing returns for both ozone and emulsions, however if you combine them together, their strengths are amplified and their weaknesses are reduced. Once you get to about 30% water in your emulsion, peak cylinder temperatures get too low and combustion takes too long to fully complete. Once you get to about 26% O2 the peak temperatures get too high resulting in high NOx emissions and engine damage. Combined together, the water keeps the temperatures down. What I want to know is, where's the limit? If you had over 30% O2 in your intake air, could you run up to 70% water in your emulsion while still producing the same amount of power?

Ok so I know I was just saying O2 above when this thread is about O3, ozone. Most of the papers I could find were about oxygen enriched combustion; I could only find a few about ozone assisted combustion. So I've had to borrow some things from those papers to fill in the gaps. Whether it's O2 or O3, we can still look at the total amount of just O entering the cylinder and use that to determine how many grams of O are in 1L of intake air and what percentage O it is.

Ok so for the chemistry part of my questions. Combustion of hydrocarbons with ozone is different than with O2. If my understanding is correct, it kind of splits the combustion into 2 phases, a cool combustion phase and regular combustion phase. The "cool" combustion was diesel and ozone combusting to acetylene, and then regular combustion happens. That acetylene helps more diesel molecules combust faster. There's actually several papers about acetylene enriched combustion of CI engines as well. In this way, the ozone is working as a partial catalyst to assist combustion; so it's not because were just adding more O into the intake air that we get improvements, it's because of the difference between how oxygen and ozone react.

I also found a paper talking about the solubility of ozone in different liquids. Ozone is 10 times more soluble in water than oxygen. I couldn't get a number for diesel, but I do know that they sell ozonated olive oil for topical use and that you can ozonate it until the oil starts solidifying.

I've found papers about using ozone to help clean up oil spills or even diesel spills. The ozone speeds up the decomposition of the hydrocarbons. For my experiment, I wanted to fully saturate the water and diesel with ozone before they go into the emulsifier while also feeding pure O2 gas into an ozone generator that goes to the intake manifold. What I can't figure out, is if it's even possible for me to ozonate diesel fuel or if I'm just decomposing it. I tried bubbling ozone gas through a gallon of diesel inside a little refrigerator for a few days. It turned brown, does have an ozone smell, but I have no idea what the composition is anymore! I asked some people on chemistry forums and they said that it's not possible to ozonate diesel, it will just decompose it.

So I guess my main question is, what is the limit for sustaining combustion of a Water/Diesel emulsion if the combustion is being enhanced with ozone?

Thank you so much for your time!

 

[Bystander]

Summary:: Trying to determine the limits of how high a percentage of water it's possible to run a diesel engine on Water/Diesel Emulsion with ozone enhanced combustion.

for sustaining combustion of a Water/Diesel emulsion if the combustion is being enhanced with ozone?

Generated in addition to the 20% atmospheric oxygen level or from it?

 

[jrmichler]

what is the limit for sustaining combustion of a Water/Diesel emulsion if the combustion is being enhanced with ozone?

This is a classic case where experimentation beats analysis. So that's for you to find out, and then tell us.

Do keep in mind that all efficiency measurements need to include the energy cost of making the emulsion and the ozone. If the ozone is made from concentrated oxygen, the energy cost of concentrating the oxygen is included in the energy cost of making the ozone.

Sounds like a fun project.

 

[Baluncore]

So I guess my main question is, what is the limit for sustaining combustion of a Water/Diesel emulsion if the combustion is being enhanced with ozone?

Interesting. It sounds like you understand the problem.

The CI field is complex and there will be many interactions where the study escapes it's bounds and influences parameters outside it's sharp silhouette. The emulsion technique may be useful in some specific situations, but how can you tell if your test engine will be capable of identifying those cases. For example, can you adjust the timing or the compression ratio of your engine during the tests?

Allowing fuel to contact ozone will almost certainly result in the formation of a hydroxide sludge that will block filters and injection systems with soap, it will define the bounds to possible problem solutions. That is all known chemistry and should be found in a literature review.

Water injection in SI engines is often considered. How has simple water injection been considered for use in CI engines? I would consider it important to review that literature.

Why inject the water with the fuel when the ozone-saturated water could be inducted as a mist in the air, like SI fuel through a carburettor. It is unlikely that it will precombust during the compression stroke, which is fundamentaly why in CI engines, the fuel is only injected as needed, allowing a higher compression ratio and improved efficiency. Why not have two separate injectors, one for the fuel and one for the water+O3. How many ways are there to use the injected water to carry more oxygen as dissolved ozone, into the combustion process?

An old slow tractor engine with a pool of water in the top of the piston can regulate the compression ratio and cool the piston by evaporation. The liquid water pool is maintained by induction of water with the air. Engine speed and combustion chamber geometry will be important in that more complex situation. You may need to prevent those confounding mechanisms in order to make your research consistent and tractable.

 

[voltech444]

This is a classic case where experimentation beats analysis. So that's for you to find out, and then tell us.

Do keep in mind that all efficiency measurements need to include the energy cost of making the emulsion and the ozone. If the ozone is made from concentrated oxygen, the energy cost of concentrating the oxygen is included in the energy cost of making the ozone.

Sounds like a fun project.

Thank you! Yes I've been wanting to run this experiment for years but just didn't have the disposable income to do it. Yes, I plan on determining the limits experimentally, I'm fully prepared to blow up this perfectly good diesel generator in the name of science!

Yes, all of the energy used to concentrate the O2, generate O3 must be taken into account. I believe this technology could be used on large commercial vehicles like semis, trains, ships. The main benefits are emissions reductions. Practically no PM is released and NOx can be controlled with water concentration. You could remove the diesel particulate filter DPF and no longer need diesel exhaust fluid DEF. DPF robs 10%-15% of engine power and reduces efficiency, DPF is expensive, replaced somewhat regularly and is a major PITA for drivers. DEF is another operating cost. If my system could eliminate those 2 things, that alone could sell it. Now yes, dealing with the EPA is a whole other can of worms, but it's not impossible, just highly improbable!

 

[voltech444]

Interesting. It sounds like you understand the problem.

The CI field is complex and there will be many interactions where the study escapes it's bounds and influences parameters outside it's sharp silhouette. The emulsion technique may be useful in some specific situations, but how can you tell if your test engine will be capable of identifying those cases. For example, can you adjust the timing or the compression ratio of your engine during the tests?

Allowing fuel to contact ozone will almost certainly result in the formation of a hydroxide sludge that will block filters and injection systems with soap, it will define the bounds to possible problem solutions. That is all known chemistry and should be found in a literature review.

Water injection in SI engines is often considered. How has simple water injection been considered for use in CI engines? I would consider it important to review that literature.

Why inject the water with the fuel when the ozone-saturated water could be inducted as a mist in the air, like SI fuel through a carburettor. It is unlikely that it will precombust during the compression stroke, which is fundamentaly why in CI engines, the fuel is only injected as needed, allowing a higher compression ratio and improved efficiency. Why not have two separate injectors, one for the fuel and one for the water+O3. How many ways are there to use the injected water to carry more oxygen as dissolved ozone, into the combustion process?

An old slow tractor engine with a pool of water in the top of the piston can regulate the compression ratio and cool the piston by evaporation. The liquid water pool is maintained by induction of water with the air. Engine speed and combustion chamber geometry will be important in that more complex situation. You may need to prevent those confounding mechanisms in order to make your research consistent and tractable.

Thank you so much for your reply! So I basically agree with everything you're saying there. Ok so I'll try to do a speed round here lol.

Yes there's a good amount of literature on the subject for both CI and SI engines. I've dug through them over the years. I've looked at papers where they only used water injection, emulsions, oxygen enrichment, ozone enrichment or combinations of these. The main takeaways were: 5%-20% increase in efficiency and power, drastic decrease in emissions (especially in CI), increased NOx (oxygen or ozone enrichment), decreased NOx (water injection/emulsion).

My diesel engine is very simple, all mechanical, I don't believe there's any way to adjust valve timing, definitely not on the fly! So I must make it work as is. I've already run it on 15% water in diesel emulsion without ozone, it didn't like that very much! My emulsion wasn't very good lol so it ran rough.

I am aware of pre combustion chambers used on older and some newer diesels, that may be something to consider.

The reason I wanted to run emulsion instead of adding a separate water injector was for simplicity of not having to add another injector. I was hoping this system could be adapted to any diesel engine to convert it without many large modifications. However, that may not be possible because of some of the reasons you mentioned.

Yes you could spray a mist of ozonated water into the intake manifold, that does work. The reason why I wanted to inject it directly into the cylinder is to try to turn the engine into a type of diesel/steam hybrid cycle engine. If you ever read about the 6 stroke engine concept, after the power stroke and exhaust stroke, superheated water was injected into the cylinder, waste heat in the cylinder flash vaporizes the water into steam and pushes the piston down for a second power stroke. My idea was to combine those 5th and 6th strokes into the 4th. So the Water/Diesel emulsion gets injected into the cylinder, there's already some ozone in the air in the cylinder from the intake stroke, the water flash vaporizes causing the diesel fuel to be nearly atomized (molecularized isn't a word is it?) and actually some of the hydrocarbon chains can be cracked. Enhanced combustion with the ozone happens while peak temperatures continue increasing, the water becomes a working fluid and part of the power stroke. At least, that's my hypothesis! Only one way to find out, experimentation!

Oh and one last question I have is what would be a good non toxic, inexpensive emulsifier for this? Any ideas on ones that wouldn't affect emissions too much? I need to know for sure that my emulsions are good and I can't really do that right now with my mechanical emulsifier. It's an easy variable to eliminate, so I must eliminate it!

 

[Baluncore]

My diesel engine is very simple, all mechanical, I don't believe there's any way to adjust valve timing, definitely not on the fly! So I must make it work as is.

I was referring to the fuel injection timing, simply done mechanically by rotating the pump on the motor. You might make that angle relative to TDC adjustable.

Oh and one last question I have is what would be a good non toxic, inexpensive emulsifier for this? Any ideas on ones that wouldn't affect emissions too much? I need to know for sure that my emulsions are good and I can't really do that right now with my mechanical emulsifier. It's an easy variable to eliminate, so I must eliminate it!

Therein lies your biggest problem.
A runny mayonnaise will need vinegar or another acid to stabilise the mix, which will counter somewhat the added ozone. It takes a huge quantity of surfactant to make a volume of emulsion.

Maybe look into how the paint industry stabilises paint.

I would consider premixing the water with alcohol, or a soluble oil.
It would be a waste to run the engine on an emulsion of pure Irish Cream.