Research Experimental 8
12-27-2011 | 10:06 AM
#27
If I correctly understand the relevant factors, they seem to be:
- Steam is used as a fluidic heat exchanger to improve vaporization of fuel, explaining the mild increase in vacuum at idle
- The steam needs to be moist, not dry, so that the additional heat does not result in preignition at higher throttle levels
- The steam helps to improve the atomization of the intermixed liquid water, producing an effect analogous to a pneumatic water injection system
Is that about right? What ambient temperatures are you seeing in your area as you do your testing? What is the steam temperature, either as it exits the heat exchanger or as it enters the manifold?
12-27-2011 | 11:35 AM
#28
Since the components of gas boil at 90-450F the objective shouldn't be to vaporize all the fuel, but instead to get enough to vaporize to spread the rest into a fine mist which can fully vaporize late in combustion instead of in the catalytic. That in itself should increase fuel economy, but would lead to hotter combustion temps (as you have less fuel to boil and remove heat during combustion) less margin to detonation and burn your side seals/springs to slag. If you heat the fuel you must also remove the heat the fuel would have removed. This is why running lean mixtures produces so much heat! All the fuel is burning, none of it is simply boiling without burning.
1) Vaporizing in the cat? Raw fuel there = burned up cat.
2) What is the evidence any raw fuel at all boils without burning in a modern engine, (at least in steady-state cruise)? NOx limits may require lowered combustion temps which in turn require running a bit rich which then requires the cat to work harder removing unburned hydrocarbons. Increasing combustion temps will indeed increase efficiency, but produce too much NO2. You'll get the same effect by leaning the a/f.
3) Leaner is not always hotter. There is a peak in the power output as the mixture is varied from rich to lean. There is a peak in the EGT as well. The EGT peak occurs on the lean side of the power peak. Leaning further from the EGT peak will cause temps to drop; they don't go up forever.
12-27-2011 | 11:52 AM
#29
The problem?
To quote from:
http://www.control.com/thread/1258022399
"Injecting water (or steam) is not cheap, in fact, it's downright expensive.
First, there must be a source of water, and usually that water must be purchased. The water must be treated to be boiler-quality water, and that is expensive. (In my experience, the water treatment plant of a combustion turbine equipped with wet low NOx is one of the weakest links in the plant, because it's usually built on the cheap and doesn't work very well without a lot of maintenance.)
Once injected to the combustor, that treated water (either in the form of steam or water) is exhausted to atmosphere, so it's not recuperable. That means, that a constant supply of boiler-quality water must be available for injection.
Lastly, injecting diluent (water or steam) into a combustor increases the dynamic pressure oscillations in the combustor, which increases the wear on the hot gas path parts (liners; seals; transition pieces; nozzles; etc.). So, no one would choose to inject water or steam unless it were not required in order to be able to build and operate the plant.
Yes, wet low NOx injection does have a slightly positive effect on the heat rate, but that still comes at a cost; there is no such thing as a free lunch in this world. Whether it's the treated water, the raw water, or the hot gas path parts, the performance increase is not free."
Anyone wish to predict what RWI (Random Water Injection) will do to a rotary's already-weird combustion dynamics?
12-27-2011 | 12:27 PM
#31
#50
Joined: Nov 2007
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From: Caput Mundi
12-27-2011 | 05:21 PM
#36
I'm curious how this compares to pneumatic water injection systems, particularly in conjunction with forced induction. If it improves idle conditions too, that would be a lovely side-efect.
12-27-2011 | 06:43 PM
#38
I disagree... In its current form the rotary isnt practical (burns oil, **** mpg) but its more simplistic and produces a ton of hp for its size and weight than say a conventional piston engine. Mazda just hasnt done a complete perfect job on the reliability part, and in this currently world, if your car isnt completely user friendly and maintanence free (Basically a Toyota Camry) it gets deemed a poor car. If the rotary were electric or hell even gas, was spinning at a constant speed would be much more practical and reliable than an conventional piston engine.
Last edited by WTBRotary!; 12-27-2011 at 06:48 PM.
12-27-2011 | 08:42 PM
#41
That being said, I am curious about this as I note that even Gale Banks, who makes no secret of his view that cool air makes power:
http://www.bankspower.com/techarticl...r-Equals-Power
and who noted:
Now comes the really interesting part of this article that raises all the questions. Twenty years ago, the late, great racing mechanic and inventor Henry "Smokey" Yunick left the automotive engineers shaking their heads when he invented and patented his hot vapor engine. Based on the familiar four-cycle piston engine concept, instead of cooling the intake air to improve efficiency, he used coolant heat and exhaust waste heat to significantly warm the intake air. The purpose was to fully vaporize the fuel and to make the intake air expand in the intake system to generate positive pressure, like a supercharger. A small turbocharger was used as a "mixer" and as a check valve to prevent the expanding intake air from backflowing out of the intake system. With the heated, pressurized, homogenous mixture, the engine ran at air/fuel ratios considered impossibly lean, such as 22:1, on pump gasoline. The hot vapor engine made incredible power and was highly efficient, responsive, surprisingly emissions clean, and delivered fuel economy of 45-50 MPG in a compact car, and it did it all without computers, smog pumps or catalytic converters. Although initially denounced by the automotive world as a hoax, several prominent SAE engineers later published papers validating Smokey's theories and design. It was no hoax to Smokey. He considered it his greatest achievement. However, the automotive giants had their own designs for increasing fuel economy and controlling emissions, and Smokey's simple and cost-efficient engine package was ignored. Today, Smokey's designs are buried somewhere in the U.S. Patent Office (www.uspto.gov, patent numbers: 4,503,833; 4,592,329; 4,637,365; 4,862,859) awaiting someone to take this technology to the next level. So just when you think you know the rules of how things work, somebody comes along and breaks the rules. It's only fitting that it was Smokey Yunick.
If this, or any line of experimentation finds a way to apply Smokey's methods to the wankel, then I believe that there will be little doubt of just how practical it can be.
12-27-2011 | 09:44 PM
#42
Well, I'm currently visiting my parents. Did 200 miles with vac drag steam injection. Got 19.1 mpg which is pretty good for 70-75mph. Changing the system again for the drive back. I think I almost have a handle on what flow rate I want and the parameters to monitor. I will report more when I have more info and am not typing on a cell phone.
12-27-2011 | 09:54 PM
#43
Well, I'm currently visiting my parents. Did 200 miles with vac drag steam injection. Got 19.1 mpg which is pretty good for 70-75mph. Changing the system again for the drive back. I think I almost have a handle on what flow rate I want and the parameters to monitor. I will report more when I have more info and am not typing on a cell phone.
12-27-2011 | 09:56 PM
#44
might not be practical running with gasoline. but it's great with hydrogen.
not trying to get into political but ...
point is, we have how many trillions of debt again ? and we just raise it by another trillion something, and we owe who money again?
if u think China is still 100% communism then you need to stop posting and start reading ...
point is, we have how many trillions of debt again ? and we just raise it by another trillion something, and we owe who money again?
if u think China is still 100% communism then you need to stop posting and start reading ...
12-28-2011 | 01:07 AM
#46
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Yea on long highway trips between 75 and 85 I average 22 mpg myself, so sounds like something may be wrong there.
12-28-2011 | 07:41 AM
#47
I have never broken 20 mpg actual pump to odometer milleage. Could be driving style, the engine, the o2 sensor, the ecu. I was just stating that I got the good end of normal milleage.
12-28-2011 | 07:51 AM
#48
^^^ Based on the large difference seen in idle vacuum w/ and w/o water, I'd guess that this is a high-functioning, low compression engine, say 85 psi. Back in the day, we used to temporarily recover some low-compression cylinders by spraying oil in the intake. I suspect water has the same effect.
One might also note that 20 mpg @ 60 mph is 3 gph of gasoline. 1 gph of water is a lot of water by comparison.
One might also note that 20 mpg @ 60 mph is 3 gph of gasoline. 1 gph of water is a lot of water by comparison.
Last edited by HiFlite999; 12-28-2011 at 07:54 AM.
12-28-2011 | 08:26 AM
#49
That being said, I am curious about this as I note that even Gale Banks, who makes no secret of his view that cool air makes power:
http://www.bankspower.com/techarticl...r-Equals-Power
and who noted: <snip> If this, or any line of experimentation finds a way to apply Smokey's methods to the wankel, then I believe that there will be little doubt of just how practical it can be.
Wrt hot vapor engines, the devil's in the details:
http://www.hotrod.com/techarticles/e...e/viewall.html
The have been dozens, hundreds, thousands maybe, of "new" ICE engines developed that do, in some sense, better than whatever standard is in effect at that moment in time.
12-28-2011 | 08:53 AM
#50
this is interesting.
I would recommend that you have a way of checking the air fuel ratios, your short long term fuel trims and do a used oil analysis. That would be good info to document real findings.
I do agree that is a lot of water being used.
Using the vacuum to draw the steam in would mean that the higher the vacuum the more steam that is being drawn in. I would think that is just the oppisite of what you want to do?
The steam needs to be under pressure with rpm/load dependant driver?
The jet air nozzles was a good thought, but you may want to alter their angle some? Steam will flow differently than air and the jet air was designed to be efficent at below 1.2K rpm. At higher rpms it may not be as helpful?
I would recommend that you have a way of checking the air fuel ratios, your short long term fuel trims and do a used oil analysis. That would be good info to document real findings.
I do agree that is a lot of water being used.
Using the vacuum to draw the steam in would mean that the higher the vacuum the more steam that is being drawn in. I would think that is just the oppisite of what you want to do?
The steam needs to be under pressure with rpm/load dependant driver?
The jet air nozzles was a good thought, but you may want to alter their angle some? Steam will flow differently than air and the jet air was designed to be efficent at below 1.2K rpm. At higher rpms it may not be as helpful?