Research Experimental 8
12-28-2011, 10:15 AM
#52
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?
I do like the idea of using the jet air system as the steam flow path so that the heat of the steam can be used to improve the velocity and atomization.
As far as the differences in flow, I think that will depend on what the ratio is of dry steam to wet steam. The suspended liquid would certainly flow differently; but I think that the percentage that is dry steam should flow the same as air at the same pressure and velocity.
12-28-2011, 10:28 AM
#53
You and I are getting about the same. I think if I could purchase pure gasoline, instead of that oxygenated (see also: adulterated or contaminated) stuff that they sell in the Metro NY City area, I might be able to match the 25 highway that OldDragger mentioned getting.
My hope, which I realize is a long shot, for this line of experimentation is that in combination with FI that it would allow a similar combination of power and efficiency as OldDragger is already achieving but with oxygenated fuel.
My hope, which I realize is a long shot, for this line of experimentation is that in combination with FI that it would allow a similar combination of power and efficiency as OldDragger is already achieving but with oxygenated fuel.
Last edited by longpath; 12-28-2011 at 11:47 AM. Reason: punctuation error I just noticed
12-30-2011, 03:33 PM
#55
Ok, back from my road trip. Highway mileage stayed about the same for the trip back. However my city/highway driving mileage without water injection while visiting my parents was about 16 MPG and plugs look black. I have never done city driving with the car before this and had no baseline to compare (I don't have much city to drive in!). So now I have clean plugs in and plan on pulling them in a week to read them. I may have had fuel economy issues to start with that I didn't even realize, or maybe my plugs were dirty and were causing the issues. Either way current data is worthless for comparison, but still usefull for honing in the system.
Yes, we are on the same page.
The ambient temperatures have been 50-60F. Steam is at saturation for slight vacuum so under 211F.
1. Depends on what the intended AFR is. At 14.7 and richer it is more correct to say that more fuel is added to increase the amount of aromatics (low boiling point petroleum) to increase the amount of energy that can be removed by boiling the fuel at low temperature. I'm guessing it has to do with heat transfer. The higher the boiling point the harder it is to transfer the heat from the air to the fuel so the hotter the combustion must get before it finds something to cool it. The actual physics behind burning gasoline is extremely complex. In the end the catalytic converter is a big ceramic sponge that provides enough heat and enough heat transfer time to vaporize and burn the remaining fuel (and air) while being powered by the fuel it burns. The actual catalysts inside are just to effect the burning chemistry.
2. Combustion temps only increase if there is not heat sink. Fuel can act as this heat sink, so can water. Water is cheap.
3. I'm not planning on going lean forever. The mixture in an engine is not homogenous. This is why you have the greatest power at around a 12.5 AFR and greatest fuel economy somewhere around 16+. At 12.5 you have the fuel burning all the air it is given, and any excess fuel going out the exhaust. At 16 you have the air burning all the fuel and any excess air going out the exhaust. The point I'm trying to make is that it is possible to get a better mixture by preheating and then to get it leaner without raising temperatures by providing a heat sink. Steam does both of these things.
http://www.otsg.com/section/view/?fnode=137
http://140.128.95.1/bitstream/987654...B%81%20J26.pdf
Steam injection does improve efficiency.
Not particularly expensive, and definitely cheaper than gas.
Evidently the person you quoted had an axe to grind. At least they admitted it improved efficiency. The pressure oscillations and increased stress come from retrofitting an existing plant for steam injection. There are plants designed for it initially that do not suffer from these problems.
So far it has had little effect on fuel economy. I'm not putting a garden hose in my intake manifold. I am metering less water than the fuel my engine injects, and I'm putting it in as wet steam. I do take offense to the to calling it Random. Yes I'm trying something new, but I am not trying to destroy my engine. As for weird combustion dynamics, I'm with you there. Tuning for this may prove impossible without a full blown lab and engine dyno. I'm just tinkering.
Agreed. Don't try this at home.
Smokey design wasn't practical at all. The model T had an vaporizing carburetor, and it worked great for a low compression, low power density engine. I have heard about several similar super carbs that did work, but burnt holes in valves/pistons or otherwise destroyed engines. The auto manufacturers won't build a super efficienct engine that destroys itself in 5k miles.
Well, YMMV. I'm happy with the results so far, but they do now point to a fundamental problem with the car in its stock configuration. Good thing I don't have any solid data or the control run done yet 
In closed loop the ECU indicates fuel trims of less than 5% (hover around 0) with both water injection and without, although my idle fuel trim without is around +8% long term. I'm investigating.
Think I have it fixed now and behaving. See below.
Here is my current design. I'm using a devils own pump and variable controller tied to MAF. I have a recirc line to allow the pump to actually modulate pressure instead of constantly bucking the internal pressure setpoint. This also keeps the line from acting like an accumulator and keeping pressure after the pump is turned off. The nozzle is still 1gph. The air drawn through keeps the nozzle from being at a vacuum and keeps the water moving quickly through the tubes to prevent water from remaining in the cold parts of the steam generator after shutdown. It seems to work quite nicely and does not suffer from watery startups/shutdowns. The biggest changes (possibly only useful changes) I have found between water injection on and off on the road are the EGT goes up about 50-100 degrees with steam injection working and the ECT drops about 5 degrees. This means that other than fixing my stock fuel economy issues I am ready to start tuning for steam injection.
Also as promised the NACA study on water injection which provides insight into the actual potential:
http://www.turbotuning.net/Artikel/naca-wr-e-264.pdf
It's not their only study, but it does show water vs water alky injection.
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?
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?
The ambient temperatures have been 50-60F. Steam is at saturation for slight vacuum so under 211F.
While experimentation can be fun, I'm not at all following the logic used.
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.
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.
2. Combustion temps only increase if there is not heat sink. Fuel can act as this heat sink, so can water. Water is cheap.
3. I'm not planning on going lean forever. The mixture in an engine is not homogenous. This is why you have the greatest power at around a 12.5 AFR and greatest fuel economy somewhere around 16+. At 12.5 you have the fuel burning all the air it is given, and any excess fuel going out the exhaust. At 16 you have the air burning all the fuel and any excess air going out the exhaust. The point I'm trying to make is that it is possible to get a better mixture by preheating and then to get it leaner without raising temperatures by providing a heat sink. Steam does both of these things.
http://140.128.95.1/bitstream/987654...B%81%20J26.pdf
Steam injection does improve efficiency.
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."
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."
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.
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.
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 opposite 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?
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 opposite 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 very much agree that ideally flow should be proportional to air flow (that is, a function of rpm and throttle opening). Perhaps a pressure regulator will be needed, either keeping a constant pressure and then using an injector with a pulse modulator controlling it in proportion to the MAF signal would be best, or perhaps the pressure should be varied in proportion to the MAF signal so that just a simple nozzle serves as the steam injector.
I do like the idea of using the jet air system as the steam flow path so that the heat of the steam can be used to improve the velocity and atomization.
As far as the differences in flow, I think that will depend on what the ratio is of dry steam to wet steam. The suspended liquid would certainly flow differently; but I think that the percentage that is dry steam should flow the same as air at the same pressure and velocity.
I do like the idea of using the jet air system as the steam flow path so that the heat of the steam can be used to improve the velocity and atomization.
As far as the differences in flow, I think that will depend on what the ratio is of dry steam to wet steam. The suspended liquid would certainly flow differently; but I think that the percentage that is dry steam should flow the same as air at the same pressure and velocity.
Also as promised the NACA study on water injection which provides insight into the actual potential:
http://www.turbotuning.net/Artikel/naca-wr-e-264.pdf
It's not their only study, but it does show water vs water alky injection.
12-30-2011, 10:01 PM
#57
EGTs going up is a normal side effect of water injection. Water slows the burn so more of it is still burning in the exhaust. Adding timing or going lean will compensate. Still about 1gal water for 3 gas, but I'm still playing with the controler. I was really hoping for the steam injection alone to have positive results, but I am willing to tune for it. Think my fuel economy may be evap system related since it gets much worse at low loads and my fuel tank burps a little gas every time I fill it. Gonna pull the canister and find a way to check the rollover valves maybe even do a DIY writeup. Also my indicate fuel economy went back into the realm of sanity after cleaning the plugs, go figure.
12-31-2011, 01:47 PM
#60
I think that a tune similar to Eric Meyer's will ultimately be needed to take full advantage of this. That is, a significantly leaner tune than OEM. I would also like to repeat Eric's recommendation that he made under another topic of get an EGT reading for rotors individually. As OldDragger mentioned, getting the steam flow equal to both rotors may not be straightforward. Likewise, I think it will be necessary to be able to confirm the a/f ratios for both rotors, at least indirectly by comparing EGT for each rotor.
12-31-2011, 03:19 PM
#61
So is this drifting toward water injection? Or is the test still about steam injection? Water injection has been done, tested, documented, etc, for at least 70 years. It's also been discussed in the forum extensively as water/meth injection. In general, it's an anti-detonation measure. Any power gains come from retuning in order to take advantage of the increased effective octane. I doubt if there are any surprises left with this technique.
Steam injection is likely to have different effects from water injection. (If it doesn't, there's no need to try it). Arguing that because water does X, steam will do X is rather unconvincing. One might also do a search on "steam corrosion and erosion" which is an effect known for a century or so. An argument that steam turbine components can be upgraded to mitigate the effects is utterly irrevalent unless one plans on remaking 13b components with similar materials. Expect damage from long term use.
Messing around with stuff this way can be great fun and a learning experience. That, however, doesn't make it research, nor does much of anything shown so far, support the rather exotic claims made. Of course, if you figure out a way to get a 30 mpg RX-8 reliably, the explanation of why such a thing might work, would hardly matter.
Steam injection is likely to have different effects from water injection. (If it doesn't, there's no need to try it). Arguing that because water does X, steam will do X is rather unconvincing. One might also do a search on "steam corrosion and erosion" which is an effect known for a century or so. An argument that steam turbine components can be upgraded to mitigate the effects is utterly irrevalent unless one plans on remaking 13b components with similar materials. Expect damage from long term use.
Messing around with stuff this way can be great fun and a learning experience. That, however, doesn't make it research, nor does much of anything shown so far, support the rather exotic claims made. Of course, if you figure out a way to get a 30 mpg RX-8 reliably, the explanation of why such a thing might work, would hardly matter.
12-31-2011, 04:18 PM
#62
This is still steam injection, however the results are as expected, and similar to water injection. Please re-read the previous pages if you want to know why I believe steam injection is a better choice. Again I don't have the control data yet nor a stable platform, so saying tuning is required for ANY gains is just a guess on your part.
Water does X, saturated steam is mostly water, saturated steam should do X as well. This is not rocket science.
Steam corrosion and erosion is a concern, but as previously stated it has shown little effect on most people running water injection, and their water does turn into steam. Damage from long term use is also a problem with turbochargers. Should I not put a turbocharger on my car for fear of engine damage?
Rather exotic claims? What claims are those? I'm giving the data as I get it. Most of it has been unsupportive of what I want to accomplish, but I'm adapting to try and prove my theories and the theories of others as well as reconciling with actual experimental data done by others. I admit that most of what I am doing is unoriginal and at the best runs parallel to the work of others, but that in itself is not a reason to stop.
In conclusion, it's my own damn engine. If I blow it up it's my problem. Can't you just sit back and enjoy the show?
Water does X, saturated steam is mostly water, saturated steam should do X as well. This is not rocket science.
Steam corrosion and erosion is a concern, but as previously stated it has shown little effect on most people running water injection, and their water does turn into steam. Damage from long term use is also a problem with turbochargers. Should I not put a turbocharger on my car for fear of engine damage?
Rather exotic claims? What claims are those? I'm giving the data as I get it. Most of it has been unsupportive of what I want to accomplish, but I'm adapting to try and prove my theories and the theories of others as well as reconciling with actual experimental data done by others. I admit that most of what I am doing is unoriginal and at the best runs parallel to the work of others, but that in itself is not a reason to stop.
In conclusion, it's my own damn engine. If I blow it up it's my problem. Can't you just sit back and enjoy the show?
01-03-2012, 11:51 AM
#64
Registered
I'm not going to comment much on this system or it's design but will speak about water injection quantities for all those concerned. I "steam clean" my engine from time to time. I do this by sticking a vacuum hose to the intake manifold with the other end in a container of water. Holding the engine at 2000 rpm, I will go through a gallon of water in about 2-3 minutes. That is FAR more water than gasoline. The steam out the exhaust pipe would lead you to believe it is actually powered by steam. It gives a nice clean engine but yes it does still run. The water doesn't turn to steam until the exaust phase so it's not going to push the rotors backwards. It isn't necessarily running on steam though. Keep in mind it isn't running smoothly but I'm only sitting there in one place with one purpose.
On highly boosted water injected engines, it isn't uncommon to top 30/70 of water to gasoline being injected into the engine and potentially up to 50% with the engine still running making good power.
My concerns with this idea are with the tubing around the exhaust in that there is no way to control how much heat ultimately gets absorbed into the system. It seems as though the concern is saturated steam as opposed to dry steam which is obviously temperature dependent. On old steam trains the original engines used saturated steam. The fire heated up the water in the boiler and the steam went through a valve in the steam dome directly down to the cylinders. The engine's fireman controlled the amount of heat and hence pressure in the boiler.
Later engines used dry steam. These engines added a superheater. After the steam left the steam dome, it traveled down several smaller tube back through the hot flame tubes that were carrying the firebox exhaust out to the smoke stack. There the tubes would pick up lots of wasted heat further heating the water. It's wasn't uncommon for steam to hit 700*F in the process hence the term super heated. This steam was very dry and had a high expansion rate. It also entered the cylinders at very high pressures. Superheated steam engines require a very different type of throttle to control this but I don't need to get into that here.
If there is determined to be a sweet spot when it comes to steam temperature then there needs to be a way to control the amount of heat going into the system and not only a way to meter the amount of steam going into the engine. You need both. I'm not sure exactly how I feel in regards to this experiment but I do know 2 things for sure. One is that you need to be able to control the amount of heat going into the system. The other thing I am sure of is that it's a good thing when people try to learn by doing things that others don't. I applaud that even if it fails.
On highly boosted water injected engines, it isn't uncommon to top 30/70 of water to gasoline being injected into the engine and potentially up to 50% with the engine still running making good power.
My concerns with this idea are with the tubing around the exhaust in that there is no way to control how much heat ultimately gets absorbed into the system. It seems as though the concern is saturated steam as opposed to dry steam which is obviously temperature dependent. On old steam trains the original engines used saturated steam. The fire heated up the water in the boiler and the steam went through a valve in the steam dome directly down to the cylinders. The engine's fireman controlled the amount of heat and hence pressure in the boiler.
Later engines used dry steam. These engines added a superheater. After the steam left the steam dome, it traveled down several smaller tube back through the hot flame tubes that were carrying the firebox exhaust out to the smoke stack. There the tubes would pick up lots of wasted heat further heating the water. It's wasn't uncommon for steam to hit 700*F in the process hence the term super heated. This steam was very dry and had a high expansion rate. It also entered the cylinders at very high pressures. Superheated steam engines require a very different type of throttle to control this but I don't need to get into that here.
If there is determined to be a sweet spot when it comes to steam temperature then there needs to be a way to control the amount of heat going into the system and not only a way to meter the amount of steam going into the engine. You need both. I'm not sure exactly how I feel in regards to this experiment but I do know 2 things for sure. One is that you need to be able to control the amount of heat going into the system. The other thing I am sure of is that it's a good thing when people try to learn by doing things that others don't. I applaud that even if it fails.
01-04-2012, 08:07 AM
#65
I'm not going to comment much on this system or it's design but will speak about water injection quantities for all those concerned. I "steam clean" my engine from time to time. I do this by sticking a vacuum hose to the intake manifold with the other end in a container of water. Holding the engine at 2000 rpm, I will go through a gallon of water in about 2-3 minutes. That is FAR more water than gasoline. The steam out the exhaust pipe would lead you to believe it is actually powered by steam. It gives a nice clean engine but yes it does still run. The water doesn't turn to steam until the exaust phase so it's not going to push the rotors backwards. It isn't necessarily running on steam though. Keep in mind it isn't running smoothly but I'm only sitting there in one place with one purpose.
Also, more as a curiosity, do you have any evidence that this cleans the engine better than Seafoaming, etc?
01-04-2012, 08:10 AM
#66
01-04-2012, 08:57 AM
#67
RG--good for you to post.
I concur--with my water meth system I have accidently ( when first installed) injected 1 gallon of water/meth (50/50) in about 7 miles of suburban driving. It was not injecting at idle.
The engine ran fine.
Steam/water cleaning is an old tried and true way of cleaning an engine. It is just as good if not better than seafoam.
I concur--with my water meth system I have accidently ( when first installed) injected 1 gallon of water/meth (50/50) in about 7 miles of suburban driving. It was not injecting at idle.
The engine ran fine.
Steam/water cleaning is an old tried and true way of cleaning an engine. It is just as good if not better than seafoam.
01-04-2012, 10:31 AM
#68
This is still steam injection, however the results are as expected, and similar to water injection. Please re-read the previous pages if you want to know why I believe steam injection is a better choice. Again I don't have the control data yet nor a stable platform, so saying tuning is required for ANY gains is just a guess on your part.
Water does X, saturated steam is mostly water, saturated steam should do X as well. This is not rocket science.
Steam corrosion and erosion is a concern, but as previously stated it has shown little effect on most people running water injection, and their water does turn into steam. Damage from long term use is also a problem with turbochargers. Should I not put a turbocharger on my car for fear of engine damage?
Rather exotic claims? What claims are those? I'm giving the data as I get it. Most of it has been unsupportive of what I want to accomplish, but I'm adapting to try and prove my theories and the theories of others as well as reconciling with actual experimental data done by others. I admit that most of what I am doing is unoriginal and at the best runs parallel to the work of others, but that in itself is not a reason to stop.
In conclusion, it's my own damn engine. If I blow it up it's my problem. Can't you just sit back and enjoy the show?
Water does X, saturated steam is mostly water, saturated steam should do X as well. This is not rocket science.
Steam corrosion and erosion is a concern, but as previously stated it has shown little effect on most people running water injection, and their water does turn into steam. Damage from long term use is also a problem with turbochargers. Should I not put a turbocharger on my car for fear of engine damage?
Rather exotic claims? What claims are those? I'm giving the data as I get it. Most of it has been unsupportive of what I want to accomplish, but I'm adapting to try and prove my theories and the theories of others as well as reconciling with actual experimental data done by others. I admit that most of what I am doing is unoriginal and at the best runs parallel to the work of others, but that in itself is not a reason to stop.
In conclusion, it's my own damn engine. If I blow it up it's my problem. Can't you just sit back and enjoy the show?
b) Steam is not water. Water pipes do not quickly plug or decay in normal use. Steam pipes can and do.
c) Your first post "By using a copper heat exchanger on the exhaust manifold fed by a water injection system to create steam, and then injection the steam into the intake manifold I have significantly increased my fuel economy while at the same time gaining a wider margin to detonation and the potential to advance timing and lean out the mixture." You claim to have significantly improved fuel economy (yeah!), though you later state in that same post that you have not actually measured it. None of the other claims in that list has been measured or tested by you. Similar is the physics "explanation" given without calculations, attribution, or line of reasoning.
d) You are of course free to blow up your engine. However, I wonder, if you are irritated at my questions/comments, what is the purpose of you posting this experiment at all? Adoration or entertainment or feedback? I'd assumed the latter, apologies if that's not the case.
Consider (a) treated water, (b) datalogger, (c) figuring out why your mpg sucks at present (probably compression), (d) pressure/temp sensors before and after injection, (d) accurate mass flow control on the steam injection side. I would also be prepared for the copper tubing to crack - the work hardening cause by exhaust sytem vibrations may deteriorate it quickly leaving you stranded with a massive vacuum leak unless you're prepared to disconnect and plug the system next to the road.
Or just pour stuff in. Whatever. unsubscribing.
01-04-2012, 12:12 PM
#69
b. Steam pipes erode, boilers plug. Both of which are caused by low quality feed water. I am using distilled water for this reason.
c. I saw increased Milleage on my OBD2. But had not evaluated real MPG. It's pretty damn hard to drive exactly the same through an entier tank of gas. Now I've had a couple tanks under my belt and it's inconclusive, but I have pinned down the most likely method for improving milleage.
I have been datalogging and tracking down other fuel economy issues. The biggest I have found is my foot. Compression may also be a slight issue, but I plan on rebuilding the engine/tranny in a couple of years anyway, regardless it should not prevent me from trying fuel economy mods. I use distilled water that is proccessed through a DU then RO and then Demin beds. I have never run tap water into my engine. I am prepared for the copper tubing to crack. This is not nor was it ever designed to be a permanent mod.
I did a datta run last night with both versions of the mod as well as no steam injection. I used the same strech of road for all three tests. I would start the steam injection, go all the way to the end of the road and turn around then start datalogging on the return trip. This was to allow the engine to reach an equilibrium with each method and prevent the influence of previous runs on results. I then scrubbed the reults and removed several spikes from the data where I had to adjust the cruise control, as well the begining of each run that wasn't steady state.My water injection pump was not set at full capacity for any run however it was pumping. I discovered this after my first run, and left it at the same seting to avoid invalidating my data. I will do annother run with the pump full on the whole time, and hopefully get more definitive results.
MPG First run with current injection setup: 28.2
MPG Second run with pump and no air slipstream: 29.05
MPG Third Run no steam: 28.7
This data is far from conclusive, but it does show a difference between my two injection methods. I beleive with a slipstream of air the water was being pushed through the steam generator and not allowed enough heat transfer time. Since highway time with that method has shown no increase in MPG I'm throwing it out. Next test is to try with/without injection at a higher flowrate and no slipstream (at engine vacuum). If that is efective I may move injection back to the Upper intake manifold and see what happens there.
c. I saw increased Milleage on my OBD2. But had not evaluated real MPG. It's pretty damn hard to drive exactly the same through an entier tank of gas. Now I've had a couple tanks under my belt and it's inconclusive, but I have pinned down the most likely method for improving milleage.
I have been datalogging and tracking down other fuel economy issues. The biggest I have found is my foot. Compression may also be a slight issue, but I plan on rebuilding the engine/tranny in a couple of years anyway, regardless it should not prevent me from trying fuel economy mods. I use distilled water that is proccessed through a DU then RO and then Demin beds. I have never run tap water into my engine. I am prepared for the copper tubing to crack. This is not nor was it ever designed to be a permanent mod.
I did a datta run last night with both versions of the mod as well as no steam injection. I used the same strech of road for all three tests. I would start the steam injection, go all the way to the end of the road and turn around then start datalogging on the return trip. This was to allow the engine to reach an equilibrium with each method and prevent the influence of previous runs on results. I then scrubbed the reults and removed several spikes from the data where I had to adjust the cruise control, as well the begining of each run that wasn't steady state.My water injection pump was not set at full capacity for any run however it was pumping. I discovered this after my first run, and left it at the same seting to avoid invalidating my data. I will do annother run with the pump full on the whole time, and hopefully get more definitive results.
MPG First run with current injection setup: 28.2
MPG Second run with pump and no air slipstream: 29.05
MPG Third Run no steam: 28.7
This data is far from conclusive, but it does show a difference between my two injection methods. I beleive with a slipstream of air the water was being pushed through the steam generator and not allowed enough heat transfer time. Since highway time with that method has shown no increase in MPG I'm throwing it out. Next test is to try with/without injection at a higher flowrate and no slipstream (at engine vacuum). If that is efective I may move injection back to the Upper intake manifold and see what happens there.
01-04-2012, 02:05 PM
#70
Registered
You are only getting a variation of about +- 1.5% in your numbers. Hardly conclusive. You need to find a way to run the car on cruise control for about 50+ miles for each run and even then your results need to be about 5% different to start to claim a trend.
01-04-2012, 02:14 PM
#71
Here is some very rough math showing why I think this should work:
Assume 35g/sec airflow.
Assume 14.7 AFR
35/14.7=2.38g/sec fuel
Latent heat of vaporization of gasoline: 900 BTU/gal=948kj/gal=146kj/lb=324kj/kg
Density: 6.0-6.5lb/gal= 6.25lb/gal
Boiling point: 80-473F (This is because the different parts of the blend boil at different temps.)
Source: http://www.afdc.energy.gov/afdc/pdfs/fueltable.pdf
Assume water injection rate of 1gph.
1gph= 3.79lph or kg per hour.
Latent heat of vaporization of water is:
2260kj/kg
Source:
http://en.wikipedia.org/wiki/Latent_heat
And of course 1l=1kg of water.
What does this mean?
2.38*60*60=8.57kg per hour fuel consumption.
8.57*324=2777kj of energy to vaporize fuel. (Only part of which I can provide with steam due to the low temperature.)
Energy provided by steam:
(assuming low quality steam and ignoring any energy provided by hot water content)
3.79*.3=1.137kg per hour of dry steam.
1.137*2260=2569 kj of energy from the steam.
Since the steam is at saturated temperature and pressure for around 18” Hg vac or 12”Hg absolute the temperature is around 187F.
The steam itself acts to preheat air/fuel, but it is limited to a maximum of 187 degrees. Even so this should be more than enough to vaporize part of the fuel and add thermal efficiency. On the flip side, the water content of the steam which for this example I will assume is still 70% (ignoring the steam that condensed to transfer heat in the first place) is now free to capture heat from combustion and the chamber walls and increase the margin to detonation.
3.79*.7=2.65kg/hour water
2.65*2260=5989 kj of energy in boiling the remaining water.
Since 2569<5989kj the end result should be cooler internal engine temperatures = increased margin to detonation.
Yes there are a lot of assumptions there. No I don't have a way of measuring the moisture content of my steam so 70% is pulled right out of my butt. Regardless the math show potential for preheating the air/fuel while at the same time removing heat.
I'm starting to feel that moving to the maintenance ports in the LIM has reduced effectiveness. The steam has less time to transfer heat to the air down there and may be part of my problem in recreating my initial results. I'm pretty timid about moving the injection back to the upper intake because of the potential of a water slug hiding behind my SSV but in order to fully test this I may have to try it.
01-04-2012, 02:27 PM
#72
Ok, found a flaw with my math. I was ignoring the air.
Air specific heat capacity= 1kj/kgk=1kj/kgc
35g/sec*60*60/1000=126kg/hour air.
Assume IAT of 55 degrees as it was last night.
Ignoring heat removed by the fuel:
2569kj/h from steam.
2569/126=20 degrees C increase.
Or from 55deg F to 91 deg F.
So either need a higher flow of water, or a higher quality of steam (which I may already be producing since the number is an estimate) in order to get the full effect from this.
Air specific heat capacity= 1kj/kgk=1kj/kgc
35g/sec*60*60/1000=126kg/hour air.
Assume IAT of 55 degrees as it was last night.
Ignoring heat removed by the fuel:
2569kj/h from steam.
2569/126=20 degrees C increase.
Or from 55deg F to 91 deg F.
So either need a higher flow of water, or a higher quality of steam (which I may already be producing since the number is an estimate) in order to get the full effect from this.
01-04-2012, 04:52 PM
#73
I just want to applaud you for actually having the nuts to test something. RG, I'm pretty sure it was you who several years ago had a thing in your sig that read something like one test is worth more than 1000 opinions. I think it's fantastic that you are actually doing something different.
But just out of curiosity, who the hell are you? You are not the run of the mill new guy that posts some crazy idea.
But just out of curiosity, who the hell are you? You are not the run of the mill new guy that posts some crazy idea.
01-04-2012, 05:22 PM
#74
Well, my real name is Harlan which should narrow it down to about 5 people in Texas. I may not be the run of the mill new guy, but I am the new guy who posts crazy ideas. I've been working in steam power generation commercially and in the military for a total of 12years, so the steam side of this is my bread and butter, but the combustion mechanics have proven quite complex. I just want to give this idea a complete fair shake before I bust it.
01-04-2012, 05:40 PM
#75
I went back and reread that and realized that could be read as hostile but I assure it wasn't meant that way. What I meant was mainly what made you choose a RX8 for this, and I can't help but actually agree with OD for once in my life, the similarities with this and W/M injection are there. At least in principle.