Dual IP - Post Water Injection Madness - PeachParts Mercedes-Benz Forum

Cadin · #1 01-23-2015, 01:31 PM

Hey Gang,

So I've been doing some pretty interesting thinking about the OM617 and power vs efficiency; as well as water/methanol injection.

In my travels I came across this:
Six-stroke engine - Wikipedia, the free encyclopedia

Also, I had never heard of Crower's six-stroke; which was apparently nothing new at the time, just re-implemented.

So here is my imagination amalgamation into a 4-stroke:

The basic idea is to run 2- IP's since the timing will be preserved.

The second injectors are DI through the glow plug holes, and the timing would be retarded to inject water after combustion. Upon entering the chamber the water would turn to steam, both adsorbing heat and driving the piston downward, potentially reclaiming a decent amount of heat energy from the system.

Questions:

1. Would our nozzles be up to this task?

2. What PSI to run to avoid water jetting and deterioration of the nozzle?

3. Will our IP's work fine at an angle (clocked)? Or do they need up-down orientation for the oil from the motor?

4. Since our IP's use diesel as a lubricant would I need to use a lubricant with the water?

5. This is obviously a crazy idea, but just how crazy?

6. Our timing chains can be built to any length, correct? Would I just two master links?

7. Where would be the best location for the extra IP? The picture is just for fun, I think running a separate chain to the right might be best.

8. I understand there are a bajillion caveats to this that I haven't covered, what are a few that you see?

GregMN · #2 01-23-2015, 02:05 PM

The IP will not tolerate water. Under high pressure/heat the water will explode violently. These mico bursts are powerful enough to cause pitting in the barrels of the IP. The IP will be ruined in short order.

By "DI" do you mean direct injection ? The glow plugs are in the pre-chamber not the combustion chamber, so, not DI.

The best method of getting water into the cylinder is via the intake manifold after the turbo. You can set up a single injector into the intake manifold or an injector for each cylinder runner.

dude99 · #3 01-23-2015, 02:10 PM

It might be easier to use a high pressure electric pump with a set of electric injectors. If you put a crank sensor on the car you could probably program an arduino to fire the injectors at the right times. Just a thought.

I don't think the IP would do well with water, I imagine it would rust and seize solid in short order.

vstech · #4 01-23-2015, 03:12 PM

Even a little water would cut the nozzles and the prechamber if it ever made it through the pump... I don't think it would though.

Cadin · #5 01-23-2015, 03:43 PM

Thanks for the near immediate response!

I was thinking about the cutting/cavitating/destructive properties of water as well, and was coming to a similar conclusion. Water/Methanol injection seems to be the most reasonable approach; of which there is ample data on the forum.

-Does anyone have a major drawback to MeOH/H2O injection?

I think it would be interesting to see the result of introducing pure atomized water directly after combustion. It would have to be introduced to the cylinder directly while the valves are shut.

-Does anyone know a simple way to resolve this?

-Does anyone believe it would be different than water injection via the intake?

-Any other fuel for the fire?

GregMN · #6 01-23-2015, 08:54 PM

What is your objective ?

Cadin · #7 01-23-2015, 11:03 PM

Quote:

Originally Posted by GregMN

What is your objective ?

To scavenge waste heat --> into mechanical energy.

whunter · #8 01-24-2015, 01:16 AM

Quote:

Originally Posted by Cadin

Thanks for the near immediate response!

I was thinking about the cutting/cavitating/destructive properties of water as well, and was coming to a similar conclusion. Water/Methanol injection seems to be the most reasonable approach; of which there is ample data on the forum.

-Does anyone have a major drawback to MeOH/H2O injection?

I think it would be interesting to see the result of introducing pure atomized water directly after combustion. It would have to be introduced to the cylinder directly while the valves are shut.

-Does anyone know a simple way to resolve this?

-Does anyone believe it would be different than water injection via the intake?

-Any other fuel for the fire?

A reasonable R&D prototype program should not exceed "twenty eight months", and roughly $148,000,000.00 USD.

.

Cadin · #9 01-24-2015, 05:55 AM

Quote:

Originally Posted by whunter

A reasonable R&D prototype program should not exceed "twenty eight months", and roughly $148,000,000.00 USD.

.

Wow, I had no idea it was so lucrative! 28 months for the sum above?!? Yes, please!

Cadin · #10 01-24-2015, 06:14 AM

I've also found another interesting lead, though it is an oldie... 1975.

This is only the abstract, but I have the rest on order. I'm curious about the details of the Bosch pump and pencil injectors they mention utilizing...

(I've been checking it out a bit, and personally the standard water (or +MeOh) injection thing (Snow/AEM/Etc...) still seems like the way to go. I believe water introduced into the intake would still largely be in the liquid phase inside the cylinder (certainly under the pressure at combustion), and enter the gas phase after combustion; still converting heat to kinetic energy. I'm just really curious if anyone knows or can think of a difference between introducing water via the intake vs direct injection into the cylinder.)

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Direct water injection cooling for military engines and effects on the diesel cycle

R.B. Melton Jr., S.J. Lestz, R.D. Quillian Jr.

A study was conducted on the feasibility of totally cooling a single-cylinder diesel engine by direct injection of water into the combustion chamber. The term “total cooling” can be taken to mean stabilized cooling at all loads and speeds so as to eliminate need for conventional cooling jackets, cooling fins, or oil spray jets. The engine used was a CLR Direct Injection Diesel with 42.5 cubic inch displacement and a compression ratio of 16:1. Most of the running was at 1800 rpm and 92 psi IMEP.

Separate measurements were made of heat rejection to the cylinder head, liner, and crank-case oil to determine more accurately where the cooling effect was being applied. Water injection was by means of a Bosch pump and various pencil-type nozzles installed, adjacent to the fuel injector in the cylinder head. Port injection and port induction were also briefly investigated. A five-hole, 90° included angle nozzle was used, as was a three-hole, 30° included angle unit. For comparison, a nozzle directing one spray obliquely at the cylinder wall was also tested. Firing pressure was monitored using a piezo-electric transducer; both pressure-time and pressure-volume (indicator) records were obtained. In order to determine timing of both fuel and water injection, needle lift was monitored using a differential transformer pickup.

The results of this study indicate:

Optimum total engine cooling by direct water injection was accomplished over a wide range of water injection timings (from 450 to 720 CA degrees after TDC power stroke) at water/fuel ratios of 2.9 to 3.7 with output power and brake specific fuel consumption improved 5 to 20%, respectively, over that with the standard jacket-cooled CLR engine.
Emissions are affected in an expected manner by the presence of water: NOx is decreased, sometimes substantially, while the other emissions (HC, CO) tend to increase.
When cooling the exhaust, the condensate becomes an effective scrubber of sulfur oxides. NOx was not significantly reduced by scrubbing, but if the condensate is made sufficiently alkaline (pH>8), CO2 was unintentionally scrubbed out.
The quality of the uncondensed exhaust for turbocharging is attractive. A theoretical gain of about 17.5% in available exhaust energy due to generation of steam was calculated, along with a temperature decrease of several hundred degrees Fahrenheit.
Water contamination of the lubricating oil varies from negligible to extreme, depending on injection quantity, timing, and spray pattern. By not directing water at the liner wall, and by keeping the oil above 212°F, one can maintain the oil in a dry condition.
Based on this work, several pertinent recommendations have been made: (1) utilize water injection for short-duration, very high-output operation which would otherwise be destructive due to thermal overload; (2) use water induction cooling in event of loss of conventional liquid coolant; (3) utilize exhaust scrubbing in stationary applications to permit burning of high-sulfur fuels without producing sulfur oxide emissions; nitrogen oxides could likewise be reduced by the injection of small amounts of water; and (4) since 2-stroke-cycle engines are an important category of diesel engines, some work similar to this effort should be done to this engine type; prospects are good for success, but conditions are apt to be more restrictive.

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Mxfrank · #11 01-24-2015, 08:53 AM

Now that IS interesting.

Your biggest problem would be figuring out how much water to inject. Too much and you quench the fire, so to speak. Too little and it's an expensive waste of time. The R&D would be expensive and time consuming...as you can see, you need to be concerned about emissions and oil contamination, among other things. And you'd probably need some sort of ECU control, because you'd want to map an ideal water/fuel ratio curve as opposed to using a fixed percentage. If you actually intend to drive this on the road, you'll be wanting EPA and CARB certifications.

So the things you'll need are a well equipped prototype machine shop, an engine dynomometer, an exhaust test rig, EGT probes, an oil analysis lab, several test engines, a metallurgist (to evaluate corrosion), a mechanical engineer ( to design the injection mechanism), a chemist (to evaluate the impact on emissions, as well as to formulate test fuels and check oil degradation), and an automotive computer engineer (to design the control system). I think $148 billion is a high estimate for the basic R&D work, but maybe not by much. Add the cost of a few prototypes, and it's a good not-to-exceed number. Keep us informed of your progress.

eatont9999 · #12 01-24-2015, 10:45 AM

Quote:

Originally Posted by Cadin

To scavenge waste heat --> into mechanical energy.

That's what a turbo does with exhaust gasses.

I don't think your idea would work unless you spent tons of money and performed a lot of modifications to the engine. Water exposed to high temps in the cylinders is not good for longevity, in my opinion.

Tmadia · #13 01-24-2015, 01:07 PM

I think it's a great idea. Water has been used quite a bit in an effort to reduce NOx emissions since they are cause by the high heat of combustion when excess O2 is around, which is exactly what diesel engines do.

https://www.dieselnet.com/tech/engine_water.php

If the second pump were to inject a small quantity of water some short time after combustion has started it would absorb a great deal of heat that would have created NOx or been absorbed by the cooling system to turn to into steam, which expands some 1700 times its original size. This gives power and reduces NOx at the same time.

with enough water it is basically it is an internal combustion steam engine. Of course the complexity of adding another injection pump and injector and getting everything timed correctly would be non-trivial. Small amounts of oil can be added to the water to lubricate the water IP, that how steam engines did it.

http://www.econologie.info/share/partager/1251395965azE1K3.pdf

OM617YOTA · #14 01-24-2015, 02:12 PM

Neat stuff. I'd read up on Crower's six cycle engine before, really looking forward to whatever you come up with.

Cadin · #15 08-27-2015, 01:41 AM

Hey Gang,

I did a bunch of research a while ago when we were discussing this, and I realize I never posted a follow-up.

I found a lot of stuff on the six cycles as well as a lot of research papers on using water vaporization/expansion to convert heat into usable energy. It seems the true caveat is that water takes longer to do its thing completely, and thus would have to have a much slower compression cycle for the water stroke.

Perhaps some opposed piston design, or cam driven valved expansion chamber would do the trick, but it certainly wouldn't work in a normal combustion setup; I guess that answers the question!

Thanks to all that joined in!