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Author Topic: The Engine,and then the gas  (Read 2269 times)

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There is nothing like hands on experience
Of course there isn't. That's why I am asking here about the max temperature of the gases inside the combustion chamber.

and when you see the exhaust inlet to a turbo and the turbo case glowing red hot at night as an engine screams at full power you begin to understand the reality of the situation.
From that I can gather only the temperature of the exhaust inlet.
I am not after that information. I am after the temperature of the flame inside the combustion chamber.

I had a 1600cc dual port head VW engine in a sand rail burning 90% methanol, 5% octane booster and 5% gas. It had 8" exhaust pipes bent upward like a dragster and when I bagged the throttle there were 8" blue flames coming from each pipe.
The spectrum of the flame is a better indicator of its temperature than the color of the stuff heated by that flame.
Flames usually start to become blue above 3000ºC (5400ºF).

The plugs had a white residue on them and you could literally smell the heat baking the engine.
Is that white residue a thermolysis product of some fuel ingredient (which one?) or the cylinder wall (aluminum) or the metals involved in the plug's construction ?

The engine would not have lasted 1 hour running that hot so I added water injection to cool the cylinders moderating the burn while still generating ungodly power for such a small engine. It generated so much torque when I dumped the clutch it started shearing the 5 hardened pins mating the crank to the flywheel.
This means that the torque generated was above the engine's design tolerances.

Keep in mind this was 37 years ago and I have leaned a few tricks since then.
Evidently you are very experienced with ICEs.

Googling stuff is fine but there is no replacing hands on experience like Tinman is doing.
I am not suggesting a replacement for hands-on experience of Tinman's or yours.
I just want to know what conditions the burning fuel/air mixture molecules have to endure (at the beginning of the power cycle)
I can Google the pressure in there but for the temperature I am asking here.

The fact is this is not an open flame nor can it be compared to one, it's apples and oranges. We are speaking of a very fast clean burn where the internal pressure rise generates excess heat. Not a slow burn and I have first hand experience with pulse jet engines and pulse detonation engines.
Yes, the slow open flame and the fast internal flame are very different.  In addition to the differences you listed, I can add that the open flame is laminar while the internal one is turbulent and the fuel/oxidizer that gives rise to the internal flame is prepressurized and premixed near the stochiometric ratio.
However, despite the different condition in which they take place, their temperature can be compared.

Which flame is hotter in your opinion?

If you ever achieved a true detonation with a lean burn your engine heads would be laying on the neighbors lawn and the crank embedded in your driveway...trust me on this. I achieved a few pulses with my pulse detonation engine and it was rattling peoples windows down the block. You cannot even possibly imagine the sound that thing made and I swear my bones were rattling. I ran that bad boy up achieving true detonation one time and I realized I was in way the hell over my head. Have you ever shot a .50 cal ?, a detonation engine is 1000 times as loud and makes a .50 cal look like a BB gun.
I have never done anything like this but I am curious if detonation converts a given grams of fuel/oxidizer mixture to more joules of energy than non-detonating reaction?   ...or it just converts it faster?

So it's probably easier you understanding there are things you may never understand because until you have actually seen it and felt it up close and personal words just fail to describe the reality of the situation.
What things?
Surely I do not need hands-on experience to learn about the gas temperature inside a combustion chamber (not the temperature of the combustion chamber).
« Last Edit: 2017-06-03, 13:29:05 by verpies »
   

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Anyway, taking the tidbit of info written by Allcanadian regarding the blue color of flame occuring somewhere down the exhaust path ...and running with it, I can reason out that the temperature of the gasses inside the combustion chamber is even higher than at the end of the exhaust pipe.
This probably means more than 3000ºC.

Note, that for the purpose of this analysis I don't care what the temperature of the solid engine parts is, although I could safely write that it is lower than the melting temperature of the metals involved. (e.g. 660ºC for aluminum)

So what happens to water molecules at 3000ºC.  The graph below leaves no doubts:



Of course heating water consumes some energy and lowers the temperature but even at 2500ºC thermolysis still happens.

of  course there have been claims of water contributing to combustion when certain metal soaps are added [extremely small quantities] it was claimed that the soaps lowered the temp of waters bond strength[disassociation] to approx 1000F.
the above was run on a dyno at 35KW load and 35-50% water [same output power as undiluted  fuel strength].
the Japanese also had/have a claim for this with some type of proprietary conditioning of the water [up to 50% in an oil burner /space heater
The exhaust flame color suggest that the temperature of the burning gasses in the combustion chamber is much higher than 1000ºF.
At 3000ºC (or even 2500ºC) some water will not survive and break down to di/monoatomic hydrogen, oxygen and OH radicals (see the graph above).

Adding metal soaps to water thermolysis products, puts you right into the Randall Mills' territory ;)



« Last Edit: 2017-06-03, 13:14:54 by verpies »
   
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Wow,i leave it for a couple of day's(due to long hours on the road),and there is a page full of post's.

OK,so i will try and answer all-1 at a time.

Grum
Quote: Could you post some pictures of the magneto please

Grum.
It is not a magneto as such,but just an ordinary coil,like those you speak of -like those in modern lawnmowers.
Difference being,this one uses points to trigger the HV coil,instead of the later solid state all in one units.
Points open-primary becomes open,and the collapsing magnetic field fires up the secondary.

TK quote: It allows the engine to be operated at higher manifold pressures

TK
I think you mean higher compression ratio's-higher compression pressures.

Quote Ronee: Brad, did you see this one?

What ever you do Ron,dont have anything to do with that Craig Westbrook.
He swindled a lot of people out of there hard earned cash with his lies.

Quote AC: If I remember correctly the magneto and points are behind the flywheel like most old dirt bikes. It's not fun breaking a rusted flywheel loose and less fun adjusting the points. As well the carb has no float or needle and seat so you turn on the gas with the main valve and start kicking before it floods. The fuel/air mixture is set at the carb with the knob on top which is a metering valve.

Indeed--spot on  O0

Quote verpies: Is it really true that adding water to the combustion chamber of an ICE, increases the mechanical power of that engine?
If "yes" - by what mechanism?


OK,this one has a couple of reasons as to why it works-or increases engine power to fuel ratio.

First off-not water,but water mist/vapor. You do not want water droplets going into the engine.

Doing this works in two ways--if you get it right.
1st- it allows you to increase the compression ratio--(which is what i think TK meant to say),and eliminate engine knock,or pre-detonation as some call it,while still using standard fuel.
As soon as you raise the compression ratio,you raise the power,and increase fuel efficiency.

2nd- As you know,most of the fuels energy is transformed into waste heat,where only about 34% is converted into mechanical energy.
When we add the water vapor,some of this waste that was used to heat the engine,is now used to heat the water vapor,which in turn converts it to steam. As we know,when this happens,we get a second expansion event within the cylinder. Done right,this expanding steam takes place after the fuel/gas mix has burnt,and so we get an extra force pushing down on the piston for a longer part of the power stroke.

Have you ever noticed that extra power your car has,when you plant your foot on a cold foggy morning  O0

Quote szaxx : I can recall an ultrasonic water/fuel emulsifier

Grum said : A good answer could be found by running a small motor with a friction brake ( rope over pulley and weight ) , adding weights until RPM's start to drop, and then using a " micro fogger " to allow the water mist into the manifold and see if the engine can drive exta load.

I just so happen to have a couple of these ultrasonic foggers   O0


verpies quote: .and how high does the temperature get in there?

The temperature will vary greatly,depending on your engine of course.
In a standard 5HP 4 stroke engine,under full load,the gas temperature can be as high as 1400*C-but cools fast throughout the stroke. Once you start to bump up compression ratio's,then you up the burn temperature,and so pre-detonation becomes a problem. I had the compression ratio that high on my racing quad,the engine would continue to run once hot,with the spark plug lead removed--it would diesel ,as we called it back then.


Brad
   
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Ah,you beat me to it verpies lol.
   
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Well,as hard as we have tried,it would seem that an OU power source is not yet in reach.

In saying that,whats say we see how efficient we can make the ICE ?,as this we can do..

I have everything we need to get the show on the road,and i dare say that Grum and AC would also have what is needed.

There is a slight problem with the little garden engine,which you will see in the video tomorrow.

But i do have a nice new 2.5HP chonda (chinese honda)motor.
I also have a ultrasonic fogger unit,and an alternator we could use as a load on the ICE.

We can just keep shaving the head,raising the compression ratio,until we hit the max compression ratio the motor can handle.

I would think a 30% increase in efficiency, is well within reach--if we worked together on this--and we havnt even started on intercoolers yet.

Then there is HHO  ;)


Brad
   
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Verpies
Randall Mills playground would be an amazing trip indeed

http://www.brilliantlightpower.com/wp-content/uploads/papers/Hydrino-Blast-Power-Paper-060117b.pdf

perhaps Arie De Geus was already playing there ,and Johan has done this for many years with the "soap"[I see his Links are now gone]

there is no doubt, this house holds the most talent to play here too.
   

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Water injection allows operation at _increased manifold pressure_ without detonation, in addition to the other effects noted by TinMan. 

Note the repeated references to its use in turbocharged and supercharged engines in the Wiki article below. The whole point of turbo/supercharging is to raise manifold pressure. This is similar to increasing compression ratios by shaving heads or increasing piston stroke but has further advantages.

https://en.wikipedia.org/wiki/Water_injection_(engine)

Quote
Due to the cooling effect of the water, Otto cycle aircraft engines with water injection can be made to produce more power through higher charge densities at the time of combustion. The additional charge density is typically achieved by allowing higher manifold pressures before the onset of detonation. This is normally done by adding or increasing the amount of forced induction or further opening of the throttle. However a similar result may be achieved via higher engine stoke. This has historically been the primary use of a water injection systems in aircraft.

Quote
However the most common use of water injection today is in vehicles with high performance aftermarket forced induction systems (such as turbochargers or superchargers); such engines are commonly tuned with a narrower margin of safety from detonation and hence benefit greatly from the cooling effects of vaporized water.



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@verpies
I apologize for my post and it was not directed at you but more so thinking out loud as I often do. As an engineer I tend to try to cram as much information into a post as is practical but often get off topic.

@Tinman
Quote
We can just keep shaving the head,raising the compression ratio,until we hit the max compression ratio the motor can handle.

When I was working with Somender Singh's squish band grooves on B&S engines I came up with a novel idea. I was taking away material on the head to make the grooves and I was getting really tired of having to shave them. So rather than shave the head I made a mild steel insert which was bolted to the inside of the combustion chamber. Think of a thick washer with two 1" bolts welded to it. Then I drilled two holes through the head with nuts on the outside of the head to hold the inner insert in place. The insert has now displaced a given internal volume which then raises the compression ratio. The insert controls the flow of combustion gasses within the cylinder and bumps the compression. It's a very easy way to shape the combustion space rather than welding the head with aluminum to build it up, grinding the head or shaving it. Hell I could drop different inserts into place in a matter of 10 minutes and the heads never gave any indication of undue stress or cracking around the holes I drilled. As well check your internal clearance between the valves and piston and the head before you light her up.


Quote
I would think a 30% increase in efficiency, is well within reach--if we worked together on this--and we havnt even started on intercoolers yet.

Now your thinking O0
At one point I wrapped my B&S engine with fibreglass insulation to retain the cylinder heat because the water vapor flashing to steam in the cylinder naturally cooled it. The engine cooling systems can be discarded and they are just a waste of time and energy. It then becomes a problem generating enough heat at which point an exhaust heat exchanger not unlike the GEET reactor is an option. We should retain the heat and use it in an internal process to generate more power and increase efficiency. Cracking some of the water vapor into HHO with a heated catalyst prior to combustion like the GEET reactor is a good start.


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Hi Brad.

Yes, over here your ignition system would be known as a flywheel magneto.

Don't forget that on damp and foggy days the barometric pressure is also lower.  ;)

" Induced swirl " was first looked at in the 1920's here in the UK by Harry Ricado he used an engine with Mica windows and a strobe and made some very simple changes to the cylinder heads of the early side valvers.

Cheers Grum.


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Water injection allows operation at _increased manifold pressure_ without detonation, in addition to the other effects noted by TinMan. 

Note the repeated references to its use in turbocharged and supercharged engines in the Wiki article below. The whole point of turbo/supercharging is to raise manifold pressure. This is similar to increasing compression ratios by shaving heads or increasing piston stroke but has further advantages.

https://en.wikipedia.org/wiki/Water_injection_(engine)

Ah,ok.
I thought we were talking about NA engine's here.

Added.

TK,i have to add this in,as there words bug me,and are some what misleading.

The way they word it,makes it sound like the water is being added,so as the manifold it self dose not detonate  ???
The only reason you need to increase manifold pressure,is to increase the compression ratio within the cylinder.
Manifold pressure has nothing to do with increased performance of the engine in a sense,as the engine would run just as well without the manifold,as in -you could remove the manifold,and have the turbo bolted directly to the inlet port of the head,and the engine's performance would be the same-even a little better.

So,it's not a mater of increasing the manifold pressure that increases engine performance,but more so a bi-product of the need to increase cylinder pressure.
The reason for the water injection in such cases,is to decrease the temperature of the compressed gases within the manifold-because as you know,an increase in gas pressure means an increase in temperature,and a decrease in gas density-hence the use of intercoolers.


Brad
« Last Edit: 2017-06-04, 02:56:19 by TinMan »
   
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Hi Brad.

Yes, over here your ignition system would be known as a flywheel magneto.

Don't forget that on damp and foggy days the barometric pressure is also lower.  ;)

" Induced swirl " was first looked at in the 1920's here in the UK by Harry Ricado he used an engine with Mica windows and a strobe and made some very simple changes to the cylinder heads of the early side valvers.

Cheers Grum.

Then that would include all such modern day ignition systems as such-like the simple modern day lawn mower that has no points-any system that has a magnet wizzing passed a coil.


Brad
   

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Ah,ok.
I thought we were talking about NA engine's here.

Added.

TK,i have to add this in,as there words bug me,and are some what misleading.

The way they word it,makes it sound like the water is being added,so as the manifold it self dose not detonate  ???
The only reason you need to increase manifold pressure,is to increase the compression ratio within the cylinder.
Manifold pressure has nothing to do with increased performance of the engine in a sense,as the engine would run just as well without the manifold,as in -you could remove the manifold,and have the turbo bolted directly to the inlet port of the head,and the engine's performance would be the same-even a little better.

So,it's not a mater of increasing the manifold pressure that increases engine performance,but more so a bi-product of the need to increase cylinder pressure.
The reason for the water injection in such cases,is to decrease the temperature of the compressed gases within the manifold-because as you know,an increase in gas pressure means an increase in temperature,and a decrease in gas density-hence the use of intercoolers.


Brad

Ah.... no, not quite.

Manifold pressure (or vacuum) refers to the pressure, or vacuum, in the intake manifold. When the throttle is closed the manifold pressure is low (a vacuum) and when the throttle is fully open, in a normally aspirated engine, the manifold pressure is at or close to the ambient air pressure. Turbo/supercharging increases the manifold pressure over ambient, forcing more fuel-air mix into the cylinders for combustion.  Manifold pressure is usually stated in inches of mercury, so the most you can get in a normally aspirated engine is 28 inches or so at sea level, and decreasing with increasing altitude above sea level. Turbo/supercharging boosts the manifold pressure so you can get, say, 40 inches at sea level. This is different from simply increasing compression ratio by permanently altering the size of the chamber and/or the piston stroke.
You don't actually need an "intake manifold" to have a manifold pressure. You could measure it directly at the intake valve(s) if you like. It is the pressure of the fuel-air mix as it is supplied to the combustion chamber (or in fuel injected engines the incoming air pressure). If it is below ambient (throttle closed or partially closed) you could call it "manifold vacuum" if you like, but the gauges that measure it are usually simply called "manifold pressure" gauges.
When you work the throttle on an engine you are controlling the manifold pressure, as well as fuel metering to match. This is why it is different from simply increasing the compression ratio: the CR is fixed or at least not readily adjustable in operation, whereas the manifold pressure is under the direct control of the operator or the engine control system. The purpose of turbo or superchargers is to raise the manifold pressure, thereby stuffing more fuel-air mix into the cylinder than it would normally draw simply by its own pump action. This of course increases the power in each power stroke.
This can cause detonation or pre-ignition, knocking and pinging, so water injection can be used to moderate the combustion. The water may be injected into the intake manifold or directly into the combustion chamber itself. Or indeed it may be mixed directly with the fuel along with an emulsifier such as a metal soap. Intercoolers function as you say, since compressing air heats it and this would contribute to the problem of preignition and detonation. Most modern automotive turbo systems don't use water injection any more since intercooling is enough, and they don't get into absurdly high MAPs anyway.


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Hi Guys.

Verpies linked this video recently to me......

https://youtu.be/jdW1t8r8qYc?t=62

IMO the guy has deliberately richened the mixture to make the combustion process visible to the camera but WOW who'd have thought Polycarbonate could stand such punishment?

For me it would have been better if he had copied the correct internal shape rather than the " old style " slab heads of the early 20's.

Cheers Grum.


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Ah.... no, not quite.

Manifold pressure (or vacuum) refers to the pressure, or vacuum, in the intake manifold. When the throttle is closed the manifold pressure is low (a vacuum) and when the throttle is fully open, in a normally aspirated engine, the manifold pressure is at or close to the ambient air pressure. Turbo/supercharging increases the manifold pressure over ambient, forcing more fuel-air mix into the cylinders for combustion.  Manifold pressure is usually stated in inches of mercury, so the most you can get in a normally aspirated engine is 28 inches or so at sea level, and decreasing with increasing altitude above sea level. Turbo/supercharging boosts the manifold pressure so you can get, say, 40 inches at sea level. This is different from simply increasing compression ratio by permanently altering the size of the chamber and/or the piston stroke.
You don't actually need an "intake manifold" to have a manifold pressure. You could measure it directly at the intake valve(s) if you like. It is the pressure of the fuel-air mix as it is supplied to the combustion chamber (or in fuel injected engines the incoming air pressure). If it is below ambient (throttle closed or partially closed) you could call it "manifold vacuum" if you like, but the gauges that measure it are usually simply called "manifold pressure" gauges.
When you work the throttle on an engine you are controlling the manifold pressure, as well as fuel metering to match. This is why it is different from simply increasing the compression ratio: the CR is fixed or at least not readily adjustable in operation, whereas the manifold pressure is under the direct control of the operator or the engine control system. The purpose of turbo or superchargers is to raise the manifold pressure, thereby stuffing more fuel-air mix into the cylinder than it would normally draw simply by its own pump action. This of course increases the power in each power stroke.
This can cause detonation or pre-ignition, knocking and pinging, so water injection can be used to moderate the combustion. The water may be injected into the intake manifold or directly into the combustion chamber itself. Or indeed it may be mixed directly with the fuel along with an emulsifier such as a metal soap. Intercoolers function as you say, since compressing air heats it and this would contribute to the problem of preignition and detonation. Most modern automotive turbo systems don't use water injection any more since intercooling is enough, and they don't get into absurdly high MAPs anyway.

I agree with all you posted except what I highlighted.  As you said inches of mercury is a measure of vacuum, but it cannot go to more than about 28  inches or so even at sea level like you said.  When you add a turbo charger or super charger you now have positive pressure in the manifold which is measured in pounds per square inch or PSI.



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Well,here is part two of the garden engine restore.

Not so good for the coil,nor the cam follower's (lifters)

Now leaning toward a plasma ignition system.

https://www.youtube.com/watch?v=9iKGamF4yyg


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I agree with all you posted except what I highlighted.  As you said inches of mercury is a measure of vacuum, but it cannot go to more than about 28  inches or so even at sea level like you said.  When you add a turbo charger or super charger you now have positive pressure in the manifold which is measured in pounds per square inch or PSI.

Did you not notice the image of the Manifold Pressure gauge I posted, that has its redline at 36 inches of mercury? Manifold pressure can get that high by the use of turbo/supercharging, and in engines that are controlled by the operator, with reference to a manifold pressure gauge, the readings are always cited in inches of mercury, or simply "inches".  And since it is disconnected for the photograph, it is indicating the normal near-sea-level pressure of around 28 inches. Do you think two gauges are needed, one reading in Inches HG and the other reading in PSI, depending on whether the manifold pressure is above or below ambient?

And for those who are disturbed somehow by the use of the term "pressure" when referring to manifold _vacuum_ (pressures below ambient) , I just have this to say: What is the MAP sensor in your automobile measuring, and what do the initials MAP stand for? 



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I wasn't referring to your use of the word pressure.  As you said pressure can be positive or negative.  I was just trying to clarify that boost is measured in psi and not inches of mercury.  Please see the attached picture of a vacuum boost gauge that shows the vacuum in inches of Hg. and the pressure in psi.

Respectfully,
Carroll


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While the gauge you show is calibrated as you say, you can see that it is displaying _relative_ pressure/vaccum : relative to the atmospheric pressure at sea level, which causes it to read "zero" at sea level pressure. Whereas the manifold pressure gauge I showed is calibrated in absolute pressure, so it shows sea level pressure as about 30 inches of mercury, the same as a barometer would show (although a barometer is usually calibrated in millibars, with 1013 mB (101.3 kiloPascals) being sea level pressure.) The automotive gauge is somehow "backwards" in its indications, and having two different measurement systems in use on the same gauge, whether above or below "zero relative pressure" is somehow confusing, to say the least.
Since even when the throttle is completely open in a normally aspirated system, there will still be some "vacuum" produced, the normal manifold pressure with fully open throttle will still be a little below ambient, or around 28-29 inches at sea level. When "blown", the pressure rises above this ambient value. Why change measurement systems at that point? It makes a lot more sense (to me anyway, as an operator of various high-performance turbocharged aircraft engines that are generally operated at ambient pressures well below that at sea level) to stay with a simple and consistent measurement system. By varying the throttle setting, directly controlling manifold pressure, the power level of the engine can be maintained at whatever is necessary for the current operation or maneuver, despite wildly varying ambient pressure or engine RPM.



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Hi TK,

Well I think your post explains why I was confused by what you posted and you were confused by what I posted.  The only turbo-charged engines I have operated are in automobiles.  And apparently you have only operated turbo-charged engines in aircraft.  I don't know why they use different measurement systems on the automotive gauges.  Maybe because most auto users understand psi better when dealing with above ambient pressure.  As you might agree I think most auto users today wouldn't even be able to start an aircraft engine much less be able to read the gauges.

Respectfully,
Carroll


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