Fuel Vaporization + Adiabatic Engine?
09-07-2010, 04:12 PM
#21
If not in this section then where else on this website do you guys expect the OP to have his question answered?
My .02: I am tired of hearing people talk about recovering "wasted energy from heat" as if they seriously intend to harness it in the manner discussed and see returns of even a small percentage of the energy that was originally lost during combustion in the form of heat. Don't get me wrong, I do believe that higher temperature fuel carries the potential for better fuel atomization and a more complete burn but this trick isn't going to yield any magic results or help you recover a significant portion of the energy lost in the form of heat during combustion and it most certainly is not the new way of the future. This is bit off topic but the most effective way I can think of to harness wasted heat energy is running a 6 stroke gasoline steam hybrid engine like the one Bruce Crowler built.
BTW: People stop embarrassing yourselves by quoting Wikipedia.
09-16-2010, 04:45 PM
#22
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when the a/f mixture gets compressed as the piston goes to TDC, that mixture becomes homogeneous and "atomized", there is no liquid fuel present anymore because the mixture has been heated as a result of that pressurization. If there is liquid fuel still present, it's because too much fuel was added for the quantity of air, the a/f ratio is overly rich. The O2 sensors prove there is complete combustion. Preheating the air/fuel mixture prior does what exactly? All it does is decrease density of the mixture entering the cylinder, it does not change the spark ignited combustion process. If it does tell me how. It does not cause the oxidation of fuel vapor with oxygen to expand to a gas at any different rate. And it is this expansion of gasoline vapor from oxidation into a gas which is what is doing the work. The whole heat is lost energy concept is taken out of context.
the work done by the other cylinders in the engine.
as opposed to using the waste/exhausted heat to do the vaporizing.
what's easier to compress?
a less dense gas charge that is pre-atomized; or fuel air mixture that contains some liquid fuel spray (which vaporizes and expands taking yet more work to compress)
no it doesn't change combustion, but the mixture would be more homogeneous and lead to a shorter burn duration thus higher cylinder pressure.
seems like a simple way to increase efficiency, not power output.
same power/less fuel
09-16-2010, 10:00 PM
#23
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The yunick hot air engine reportedly, warmed the incoming air to around 220 degrees with engine water temp, then again capturing the heat off the turbo housing and exhuast, raising the incoming air to around 500 degrees......That mixed with a fuel ratio around 25 to 1, netted nearly 100% power gains and 100% fuel mileage gains compared to the same engine running lean and naturally aspirated. The egt reportly went far past 1700 degrees (melt down in most cases) to the area of 2700 degrees but due to undisclosed cam timing changes (and others) didnt melt down like you would expect it too.
Theoretically if yunick could have done it too an ls engine, it would get 40 mpg city 55-60 hiway and make around 600 hp......too bad gm took the idea, and put it to bed after almost bringing to the public in the early 90's.
Theoretically if yunick could have done it too an ls engine, it would get 40 mpg city 55-60 hiway and make around 600 hp......too bad gm took the idea, and put it to bed after almost bringing to the public in the early 90's.
09-29-2010, 01:46 AM
#24
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09-29-2010, 02:02 AM
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Propane Running a gaseous fuel with high mixer velocities is probably the closest approach to perfect fuel/air mixing. it does lead to some improvements, but with engines they way the are nowaday, not much.
10-06-2010, 02:50 PM
#26
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No one has yet to explain how complete atomization would eliminate detonation. It wouldn't. You know what they use completely atomized fuel for? Fuel-Air bombs.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
10-14-2010, 11:26 PM
#27
No one has yet to explain how complete atomization would eliminate detonation. It wouldn't. You know what they use completely atomized fuel for? Fuel-Air bombs.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
10-15-2010, 09:38 AM
#28
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No one has yet to explain how complete atomization would eliminate detonation. It wouldn't. You know what they use completely atomized fuel for? Fuel-Air bombs.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
Furthermore, no one has given any evidence as to why eliminating detonation would double the efficiency of an engine.
Complete atomization of course wouldnt eliminate detonation, I dont know why or who would have said that? Obviously there are many factors at play concerning the control of detonation. One being the best atomization possible for the most controlled combustion event.
Regarding the comment about the reported 2700 degree egt .....well it would seem that way, but its only relayed information. Perhaps that part is inaccurate? Perhaps there is something else going on that we are not privlidged too? Around 70% of the energy from the internal combustion engine is waisted heat energy anyways. Maybe by using less fuel via better atomization, causes higher temps which result in more power. 30% of 3000 degrrees of heat is more then 30% of 1500 degrees.....infact its double isnt it? hhmmmm
on the less fuel...
10-16-2010, 05:14 AM
#29
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It's important to remember that Smokey's setup evolved in the days of carbs.
Adequate vaporisation was always a challenge with carbs and intake manifolds which never could enable good cylinder to cylinder mixture distribution which limited fuel economy as there were limits to how lean an engine would run once a lone cylinder got into lean misfire. Pressuring the intake with a turbo setup (which regains density that the heating kills) improves cylinder to cylinder mixture distribution and increases lean limits.
Low energy points based ignition systems of the past also limited the lean levels. A single cylinder today arguably has more spark energy than the whole engine shared on points based distributors.
EFI does away with a lot of those issues and now we get more mpg from a 400HP engine than a 250HP engine would do 30 years ago.
Efficiency of an IC engine is limited by detonation limits of fuels. OEM's are getting this more under control with direct injection and multi shot direct injection to better control the burn. (both Diesel and Gasoline engines).
"Superheating" the air/fuel mix (the fuel is well into the gas phase instead of being just on/over the liquid/gas line) will increase detonation limits and variability as the fuel molecules are 100% equally distributed within the incoming charge and combustion chamber. Which they aren't even with modern EFI though direct injection makes a giant leap in this direction.
Generally fuel economy is limited by emissions limits. In effort to minimise emissions mixtures are run at the 14.7:1 magic number with gasoline. Best economy is still at around 16.5:1 but NOX is out of compliance at this level as burn temperatures get too high. Emissions laws over rule mileage at present.
Interestingly NOX comes back down again at 17.5 - 18:1.
Watch that space...
While Yunick's engine may have achieved its high power low emissions high mpg numbers, there is a fair chance the materials science of the day meant the engine had an unacceptable service life. Cast iron manifolds glowing orange with really high exhaust temps during normal use wouldnt have lasted
long not to mention under the hood temps that were non viable.
OEM's are getting there (i.e. with direct injection which enables higher comp ratios on the SAME fuel and increased use of turbos on smaller engines) but they generally dont acheive more than they have to unless they are pushed by the government and EPA, and when they are, they then spend the money on the technology innovation and can pass it on to the consumer as well as achieve the enormous scale which brings manufacturing costs of new technologies into an acceptable realm for the regular auto consumer.
Cheers!
Adequate vaporisation was always a challenge with carbs and intake manifolds which never could enable good cylinder to cylinder mixture distribution which limited fuel economy as there were limits to how lean an engine would run once a lone cylinder got into lean misfire. Pressuring the intake with a turbo setup (which regains density that the heating kills) improves cylinder to cylinder mixture distribution and increases lean limits.
Low energy points based ignition systems of the past also limited the lean levels. A single cylinder today arguably has more spark energy than the whole engine shared on points based distributors.
EFI does away with a lot of those issues and now we get more mpg from a 400HP engine than a 250HP engine would do 30 years ago.
Efficiency of an IC engine is limited by detonation limits of fuels. OEM's are getting this more under control with direct injection and multi shot direct injection to better control the burn. (both Diesel and Gasoline engines).
"Superheating" the air/fuel mix (the fuel is well into the gas phase instead of being just on/over the liquid/gas line) will increase detonation limits and variability as the fuel molecules are 100% equally distributed within the incoming charge and combustion chamber. Which they aren't even with modern EFI though direct injection makes a giant leap in this direction.
Generally fuel economy is limited by emissions limits. In effort to minimise emissions mixtures are run at the 14.7:1 magic number with gasoline. Best economy is still at around 16.5:1 but NOX is out of compliance at this level as burn temperatures get too high. Emissions laws over rule mileage at present.
Interestingly NOX comes back down again at 17.5 - 18:1.
Watch that space...While Yunick's engine may have achieved its high power low emissions high mpg numbers, there is a fair chance the materials science of the day meant the engine had an unacceptable service life. Cast iron manifolds glowing orange with really high exhaust temps during normal use wouldnt have lasted
long not to mention under the hood temps that were non viable.
OEM's are getting there (i.e. with direct injection which enables higher comp ratios on the SAME fuel and increased use of turbos on smaller engines) but they generally dont acheive more than they have to unless they are pushed by the government and EPA, and when they are, they then spend the money on the technology innovation and can pass it on to the consumer as well as achieve the enormous scale which brings manufacturing costs of new technologies into an acceptable realm for the regular auto consumer.
Cheers!
10-16-2010, 11:16 PM
#31
TECH Resident
Diesels are natively direct injection. In the last year or so GM (at the very least) has introduced direct injection on gasoline engines. i.e. the Camaro V6. Other OEM's have it too. Instead of firing a single shot of fuel from the intake manifold injector position into the intake port onto the back of the valve using 60psi of fuel pressure, DI engines inject directly into the combustion chamber at 3000-4000psi or more. This enables better atomisation/vaporisation, more complete combustion, improves emissions, enables higher comp ratios/less tendency to knock and more efficient fuel usage.
Newer technologies in materials like better injectors with very low inertia pintles with withstand combustion pressures, pumps capable of safely getting gasoline to really high pressures, fuel lines, and computing power enable things like this to make it into mainstream auto usage.
GM has had DI in pilot/testing with Gen IV V8's for 1-2 years. One of the features of the upcoming Gen V V8's.
10-18-2010, 09:14 AM
#33
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^^^ Yes in the case of the duramax it is called Pilot Injection. It adds a small shot of fuel prior to the initial detonation, it then adds the main "shot" at a specified time. And Diesel injectors inject at around 23K psi. My truck is EFI live tuned and I run around making well over 400 RWHP and nearly 1000 RWTQ and still turn 20 MPG in a 7000 LB truck.
10-20-2010, 02:46 AM
#35
TECH Resident
Cool! As Jon notes diesel = 2 shots (at least on the Duramax...stunning increases in power on those from EFI Live tunes). From memory IIRC with gasoline up to 4 shots are being used to optimise the combustion cycle. But my memory aint what it used to be.
1000RWTQ........that must haul nice!
As Jon notes diesel = 2 shots (at least on the Duramax...stunning increases in power on those from EFI Live tunes). From memory IIRC with gasoline up to 4 shots are being used to optimise the combustion cycle. But my memory aint what it used to be. 1000RWTQ........that must haul nice!
10-20-2010, 06:08 AM
#36
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Now if you warm the fuel that'd make sense. The molecules are further apart and less stable, and would react much easier. Kinda like how sugar gets mixed much easier with hot coffee than it does with cold water.
So if that's what needs to be done that'd be such a simple thing to do. Just warm up gasoline (not enough to make it explode) before its injected. Theoretically you should get better gas mileage proportional to how much to warmed it up. Why don't you try that?
10-20-2010, 08:56 PM
#37
Staging Lane
Regarding the comment about the reported 2700 degree egt .....well it would seem that way, but its only relayed information. Perhaps that part is inaccurate? Perhaps there is something else going on that we are not privlidged too? Around 70% of the energy from the internal combustion engine is waisted heat energy anyways. Maybe by using less fuel via better atomization, causes higher temps which result in more power. 30% of 3000 degrrees of heat is more then 30% of 1500 degrees.....infact its double isnt it? hhmmmm
on the less fuel...
on the less fuel...
Temperature isn't proportional to energy. Any well-insulated system with little to heat can become extremely hot with almost no energy input.
Last edited by ZMX; 12-16-2014 at 01:17 AM.
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