Water injection and alcohol fuel 14

[KeithDyer]

For what it's worth . . . . . . . . ,

Back in the late 70's and early 80's, I built engines and was crew for the premier Drag Boat Racer of that era, Eddie Hill.

We held all four drag boat association ET and MPH records at the same time, bests of 5.60's at 226 / 229 MPH. Exceptional win percentage, the boat to beat anywhere we ran it.

Typical Keith Black 500" Aluminum Chrysler Nitro Hemi just like all of the Top Fuel / Funny Car engines of the day. 14-71 blower making about 30 - 32 psi on a pass. We ran a HIGH percentage of Nitromethane (about 96-97%), with a crude water injection in place. We used the blower pressure from the intake manifold and ran it to a small Moon tank to move the water to nozzles above the fuel injector butterflies. The harder the pass, the more water that was delivered to the engine. Average water consumption was 1.1 / 1.2 liters per pass.

We used this method to primarily keep from having to tear the engine down between runs as we had little money to spend on parts and a small crew to perform such maintenance like all of the other teams. The same guys that were detonating the guts out of their engines every time down the track.

This system did what we needed it to do at the time. Once at Bakersfield (Lake Ming) we tried to use methanol in the system instead of water. Huge fireball at half track!! Like all hot rod guys, trying to get a little more out of the engine!!

Not real scientific, but effective enough to keep us racing up front and continuing to dominate the sport until Ed's violent crash at Firebird (Phoenix) in 1984.

Like I said up front, "FWIW"!!

Take care, K

 

[140Airpower]

Keith, what it's worth is a lot. It is the most convincing account the I've heard of how effective water injection is at reducing mechanical loads on parts as well as reducing heat.

 

[140Airpower]

azmios, Your remark about textile engineers implies there is some flaw in that that lessens the value of an engineer’s opinions. This borders on a personal attack. One quality in a good engineer of any specialty is the ability to spot BS. Virtually all the contributors here appear to be giving their honest opinions and do not appear to be promoting scams.

You said the oxygen generator is of “high” efficiency. Of course anything less than 100% will diminish the overall efficiency of the engine. What is “high” in your estimate?
Oxygen from the air is free. Oxygen that has to be generated comes with a cost: a cost in energy, a cost in machinery and a cost in some starting material. There are only a few choices that come to mind. One is electrolysis of water. At least the starting material is cheap, but the efficiency of this is NEGATIVE. It costs more energy to do the electrolysis than you can get back by combining the oxygen and hydrogen with each other and even worse when you combine them with other reactants. Here we would be talking about using only the oxygen? A very big loser! Another method is to extract oxygen from some oxygen rich compound. The usual favorite is CONCENTRATED hydrogen peroxide. This material is relatively expensive, unstable and dangerous. At least the water is built-in. There are other compounds, but the best are also expensive, unstable and dangerous. A third method of providing oxygen is to use compressed oxygen gas in cylinders. I think the image of that speaks for itself. What method is proposed? It needs to provide oxygen at a high rate and have an overall total cost that is only marginally more than the cost of air. In my opinion, an oxygen generator like that is a much, much bigger and more important innovation than this proposed engine design.

Combining a steam engine with an IC engine is an very old idea. It’s obvious that you could boil water using exhaust heat and run a steam motor, extracting some additional energy from the fuel, increasing overall efficiency. Injecting water directly into the IC engine can also be done. The thermodynamic balance is questionable with respect to the amount of steam expansion compared to the reduced exhaust gas expansion. But there is no question that less heat is lost to the cooling system. Injecting water at any time during the burn will reduce NOx, but will increase HCs. It will also likely reduce the effectiveness of a catalytic converter due to greatly diminished exhaust temperature. It is also most problematic for lean-burn cruise where the effect of causing misfire (if injected early or in the intake tract) and of quenching the flame exacerbates the emissions problem and hurts efficiency.
Injecting water after the burn can be done. The steam expansion is now mostly in the exhaust tract and can be utilized by a bottom cycle motor like a turbocharger. The efficiency of this is not as good as a piston motor.
A very interesting use of the steam engine principle is the Crower 6-stroke engine. An extra crank rotation is used where water is sprayed into the hot cylinder after the normal 4-stroke cycle. The water extracts heat from the metal, cools the engine sufficiently to obviate the need of a cooling system, expands as steam, -applying pressure to the piston and adding torque to the crank. This is a pure plus for efficiency with virtually no effect on the normal burn and at the cost of very little extra mechanism. It will affect the catalytic converter, however.
The big problem for a mobile powerplant with bottom cycle engines that I can see is that they cannot be very efficient themselves because they are working with a greatly diminished starting temperature compared to the IC initial temperature AND they usually comprise a mechanism, like a steam motor, that is comparable to (maybe ¼ to ½) the mass and complexity of the IC engine. For example, the Crower 6-stroke adds a crank rotation to extract a small amount of power. So a 3 liter Crower is like an extra large and heavy 2 liter IC engine that is perhaps 10% more efficient. This is probably not a good trade off for a car engine even counting not needing much of, if any, cooling system. Steam engines like this also require that you carry water. I don’t believe a recondensing systems in a car makes a lot of sense. The amount of water the Crower would use needs to be about equal to or more than the amount of fuel by weight. So, when you get 10 gal of gas, you need at least 7 gal of water.

All the negative observations that apply to a mobile application do not necessarily apply to a stationary plant. In fact, even the oxygen generator problem could be very different in a stationary plant.

 

[azmios]

Air,

It's good that you made some comment about the personal attack. I hope that people who earlier wrote about the "blind squirrel" and accusing people with BS will take notice. Frankly I dont enjoy much responding to other people's personal attack but if it is necessary to make others realize, it should be justified. If you personally feel that I am scamming here, all it needs to prove so is to debate about the points that I brought up rather than just accusing others of scamming. it is so much easier to accuse others rather than to counter the so called scams with facts and figures.

Back to the debates. The idea of using oxygen to replace air is not new, there are many papers in public domain involving both piston and turbine engines. That 2009-01-2808 made a lot of references to submarine engine researches. French and Japanese engineers are still active pursuing the oxygen engine.

I know that many will think that why burn oxygen when we have air at no cost? Similarly, I can ask them why do we have to compress air that contains 78% (volumetric) nitrogen? The work needed to compress air up to 100 bar in diesel requires a lot of energy, furthermore, many diesel engine run lean thus the amount of air compressed is even more. Compressing this much of air up to 100 bar requires more energy than what it takes to generate oxygen from air. I personally feel that nitrogen does not belong in the combustion chamber. Water is a better heat absorber and gas expander.

As pointed out in that SAE paper, raising the cylinder temperature is best done by retaining some of the hot residual gases from the previous cycle. the compression work on the other hand is needed just to further raise the temperature slightly above what is needed for optimum fuel auto ignition to occur. When this happens, the work needed to raise the cylinder temperature is much lesser and the freed energy can be used to generate oxygen using PSA generator.

As proven by the coal power plants in China, the use of oxygen gives them advantage in terms of energy. Rather than having to spend a lot of energy to process the coal into something cleaner, the use of oxygen ensures that most of the complex hydrocarbon chain is broken and oxidized releasing intense heat. The irony is that, decades ago many american researchers have proven that the use of air with more than 21% oxygen content have enabled them to burn low quality fuel oil cleanly. Since not many read about the findings, many still feels that it is better to spend a lot of energy to process raw crude oil into clean fuel rather than to use oxygen to burn less refined fuels.

 

[Slim3]

I have a question for all of you as I have no engineering degree and ask it out of practical applications.

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

I know that when you adjust the fuel mixture leaner then stoichiometric, horse power goes down and temperature in the combustion chamber goes up. And when you adjust the mixture richer then stoichiometric, (as much as 30% richer) horse power goes up and combustion chamber temperature goes down. And according to papers I read from Champion Spark Plugs and from Ford Motor Co. the flame front is completely across the combustion chamber by from 15 degrees to 30 degrees depending on the engine design, mixture etc. And when the piston to rod to crankshaft is at 79 to 80 degrees crank, leverage is at it's best and piston velocity is at it's highest. I know that even though the flame front may be across the combustion chamber, there is still a continuing burn and a long process of expansion.

Without changing the fuel mixture at all and not advancing ignition timing at all to take advantage of any octane rate increase due to my added injection of 50/50 water/ethanol alcohol, why did I receive much additional power on two different engines that I tried it on? I know it was not a fluke as I made dozens of test runs all day long on the two vehicles.

I believed at the time it was a combination of vaporization in the intake manifold giving a lower intake temperature due to the high latent heat of vaporization of the alcohol, thus a more dense air charge going in and even though the combustion chamber temperatures were lowered too, I gained some power from the steam produced and the added combustion of the alcohol which contains a small portion of it's own oxygen necessary for it's own combustion.

In the late 70's I came to the conclusion that the Otto piston engine is not making good use of combustion other then trapping most of it in a chamber. So I am now experimenting with alternate geometry designs of a piston engine to attempt to make better use of combustion pressures.

Slim3

 

[azmios]

"Without changing the fuel mixture at all and not advancing ignition timing at all to take advantage of any octane rate increase due to my added injection of 50/50 water/ethanol alcohol, why did I receive much additional power on two different engines that I tried it on? I know it was not a fluke as I made dozens of test runs all day long on the two vehicles."

The first line of your sentence is the key to the question that you and I have been asking. As per my earlier reply, the phenomena has not been scientifically explained on why such power increases.

 

[winfieldblue]

Experimenting with used cooking oil gave me a few surprises, boiling off any water present in the oil after the filtering process resulted in a lower power output from the engine ,nothing startling but easily noticeable, I then realised that the worst thing to do when your frying pan catches on fire is to throw water onto it while attempting to put the flames out, if you've never tried this, oil sprays out in all directions spreading the flame with it. I don't know what happens when water is thrown onto a petrol fueled fire, but I think that much the same effect would be created, obviously that's why we have different fire extinguishers for liquid fires-water doesn't work well at all when trying to extinguish the flame!. A faster more complete burn would be more easily noticed in a large open hemi type chamber, maybe that's where some of your power increase came from Slim3!

 

[patprimmer]

slim3

by adding alcohol via the 50/50 mix, you made the mixture richer so the a:f was in fact changed unless you corrected for that and removed fuel from the main source.

Also increasing the amount of liquid entering the chamber, you effectively increase CR until the liquid evaporates. When it evaporates, you lose pressure from the loss of heat temperature going to supply latent heat of vaporisation, but you gain pressure from more gas molecules present.

You can't add energy to the closed system, so any pressure has to come from heat generated from a chemical reaction such as burning fuel or from latent energy from a change of state. The only change of state here is from liquid to gas which absorbs heat. It does not generate heat.

For further study, look up the gas laws and the laws of thermodynamics and latent heat.

Don't confuse temperature and heat, they are different.

Also, lean mixture does not increase chamber temperature, it increases exhaust temperature as it burns slower and more heat is generated later in the cycle.

To burn fuel in air, you need molecules of air and fuel aligned and enough heat there to trigger the reaction. Even though we try to mix air and fuel perfectly, even a very small well atomised drop of liquid fuel contains problably thousands of molecules or even millions of molecules. Also they are not perfectly distributed throughout the chamber so there will always be some oxygen molecules not close enough to some fuel molecules to burn.

For maximum economy we need to burn all the fuel, so we add air to increase the number of oxygen molecules potentially available to the fuel molecules so we burn as much of the fuel in the chamber as possible.

For maximum power we use an excess of fuel so that we burn as much of the oxygen available as possible.

There are limits where you get into diminishing returns re availability of molecules aligned close enough to react vs dilution with other non reacting molecules and coolants that then cause misfires or plug fouling if rich or erosion of metals from the chamber, like valves, pistons or earth straps on the plugs if lean.

Regards
Pat
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[patprimmer]

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

Further to the above.

As well as higher compression and more NOx, the reduced power comes from compromises to ignition and cam timing and EGR and often from changes to chamber design to open chamber with no quench to reduce hydrocarbons in the exhaust. This reduced quench also resulted in reduced squish so less turbulence across the flame kernel at neat TDC so a slower burn with more heat produced to late where it does less work so is hotter as it goes out the exhaust rather than hotter at TDC and just after.

Regards
Pat
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[patprimmer]

slim3
The combustion chamber is a very dynamic place and while the combined gas laws relate temperature and volume, it takes time to stabilise, so in fact we have higher and lower pressure and temperature areas constantly changing as the engine runs.

Ideally an engine should produce peak cylinder pressure about 12 deg ATDC. If the spark was say 30 deg BTDC, think how long that 42 deg takes at say 6000rpm.

Think about how long it takes the fuel droplets to evaporate and for the molecules to mingle and align with oxygen in air and exhaust and whatever else is in there.

The burning is releasing heat and generating temperature and pressure while evaporation is absorbing heat and reducing temperature and pressure but increasing volume which increases temperature and pressure.

At the same time the piston is moving which changes volume and therefore temperature and pressure.

It is exceptionally complex and dynamic.

Regards
Pat
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[patprimmer]

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

For one no one called you a blind squirrel. Hemi implied he could find something even if HE was a blind squirrel.

No one said you yourself where BS. I implied some of your statements where based on BS due to your incorrect interpretation of some terms. I stick by that. I even wonder if English is your first language as you seem to have some problems with the meanings of some words. Statements based on wrong meanings of words are inherently inaccurate which is commonly known as BS. If you wish to make statements based on errors and not be called on it, then you are in the wrong site.

Air, I have no problem with someone resorting to personal attack as it is evidence that they have run out of valid argument and it is a last desperate attempt at rebuttal without actually offering any credible evidence.

Regards
Pat
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[patprimmer]

Opps

A quote got pasted into the wrong post with a wrong attribution.

Obviously the quote attributed to azmios should be attributed to slim3 and applied to the post above.

Regards
Pat
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[patprimmer]

Back to the steam engine analogy, the issue with air instead of steam is the volume change.

A tonne of water occupies a lot less space than a tonne of steam, and when kept under enough pressure for the temperature it is heated to, can remain in liquid highly compacted form until released to drive the engine.

Unless air is liquified, the heater unit containing enough air in a closed system to do the work of a tonne of water would pretty much take up a city block at many stories high rather than easily fit into a small pick up truck.

Remember, while the system is pressurised, no more water or air can be added without depressurising first. At least not without an extra pump that also takes power to drive.

Regards
Pat
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[Slim3]

Pat, doesn't that confirm my tests on my straight 170 proof ethanol engine maintaining power with 15% content of water when compared to that same engine tests running on 200 proof?

With my 170 proof I had lost 15% of my fuel and using water to replace that 15% should have lost some heat vaporizing the water. This should have caused me to loose power but many 1/4 mile acceleration test runs showed the same between the 170 proof and the 200 proof ethanol.

Everything I did was real world and none of it came out of a book. True I didn't fully understand why I received some of the results that I did and I am only in here looking for answers.

You are correct that my English is not that great but it is because I have less then a high school education. But it was all American if that is important to you. As far as BS, my guess as to why I was receiving the results I did could have been thought of as BS but everything I did was done as I stated.
And don't worry about hurting my feelings as I use to race motorcycles professionally, spent two years in the US Army as an infantryman in a foreign country and 50+ years in the auto industry and built more high performance engines then most people have even seen. Don't worry about hurting my feelings as you can't. Not sure any one can any more as this old hide has long ago become rather thick and hard.

I'm just looking for real answers.

Slim3

 

[patprimmer]

Slim

The BS and English second language was not aimed at you.

Azmios claimed his slight as to the lower value of my degree and therefore opinion was a retaliation for the term blind squirrel being used and me calling some of his post BS. I was offering a rebuttal to that. Seeing as how I never even made the blind squirrel comment and as how the hemi who did make it was actually referring to himself, and some very unusual interpretations of some terms used in physics, I was wondering about his language skills. Innuendo and other figurative speech often mistranslates badly. Technical language also sometimes translates badly.

Regards
Pat
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[azmios]

pat, i feel sorry for you. I guess when people bring machine guns to a technical debate with the intention to shoot people that do not share the same opinions or belief as you do, other innocent bystanders tend to get hurt. Even people with the honest intention to debate will tend to fight back with their bare hands when being shot at. I do not know you and before I join this debate I had nothing against you. You're right, my english is not good and though I speak several languages, english is not my main one. Let's move on to the debate as I am interested to exchange information.

The beauty of water is that as what you pointed out, we can use it when it is needed. It can easily be manipulated using pressure and temperature to exist either in liquid or gaseous state. It should stay in liquid state so that it can absorb heat and carry it elsewhere. It should be turned into gaseous state to extract some kinetic energy from it. If logistic is an issue, we can even condense it and filter it for reuse. Piston engine has a lot of limitations in terms of expansion ratio but if we use gas turbine, we can increase the expansion ratio to really bring down the gases and steam temperatures. The lower the exhaust gas temperature, the easier to condense the steam for reuse.

 

[azmios]

Pat,

"Remember, while the system is pressurised, no more water or air can be added without depressurising first. At least not without an extra pump that also takes power to drive. "

typical DI injector injects at 150-200 bar. Water is best to be injected when the intense heat release is ongoing. Furthermore, water at 150-200 bar has its boiling point raised so it can first be heated using coolant heat and later exhaust heat. At Q=mcT, the energy being brought into the combustion chamber will easily pay up for the pump energy consumption.

 

[patprimmer]

And yet another slight.

And yet another reversal of the laws of thermodynamics.

And yet another off topic post switching to turbine when the subject is spark ignition, Otto cycle, automotive application.

Now back on topic sans BS

slim3

One aspect barely mentioned here that might explain your result.

I don't have the data at hand, but I remember reading somewhere, probably in an NACA report that water is one of the few liquids where when it evaporates into air, the gas produced does not fully compensate for the loss in volume of the air in the system due to the heat absorbed.

For alcohol, although it absorbs heat also as it evaporates, it displaces more air than the cooling compensates for. That is why alcohol fuel racing classes use down nozzles.

That means that if water evaporates in the manifold VE improves as the increase in air density from temperature drop is greater than the air displaced by the water vapour.

If alcohol evaporates in the manifold the cooling is not enough to compensate for the air displaced by the alcohol vapours so VE decreases.

If all other things remain equal (which they never do in the real world) the extra water will increase the VE due to extra charge cooling in the manifold. The improved VE could explain your results.

Regards
Pat
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[azmios]

Air,

"Injecting water after the burn can be done. The steam expansion is now mostly in the exhaust tract and can be utilized by a bottom cycle motor like a turbocharger. The efficiency of this is not as good as a piston motor."

It all depends, I am inclined to have water to be injected upward into the combustion chamber. This way, superheated water can be introduced into the combustion chamber right after the TDC without suppressing the fuel development in the piston bowl.

 

[azmios]

Slim3,

Our questions about the link between water+methanol and power have not been answered yet. Will it be possible for you to measure the exhaust gas temperature right after the exhaust port. If we can compare the exhaust temperature with and without the water injection, it will shed some light into this. I am expecting that the exhaust temperature to be decreased significantly when it involves water injection. If drop in exhaust gas is detected, theoretically, the heat energy has to go somewhere and if it doesnt end up as coolant or exhaust heat, it has to make more power at the crankshaft.

Furthermore, the combustion of methanol will have more water after the combustion. This water will also help in the heat absorption and gas expansion processes.