Gasoline VAPOR?

[tomi_k]

Using existing fuel injection lines would be handy way to introduce fumes / vapors to the cylinders as it is already there... fuel pump is just pumping liquid fuel into to lines so need to figure out and see how it works with fuel fumes / vapors. This approach may need fumes / vapors to be pressurized, just like liquid fuel...

If fumes / vapors are brought into cylinders some other path, i.e. via air intake manifold, then probably disabling fuel rail(s) and injectors should and leaving them in place should not cause any additional harm... they are just there as "plugs"... so I wouldn't take them out... naturally can be taken out... Using air intake channels to bring into cylinders, this has naturally "vacuum" so fumes / vapors" are drawn automatically in to cylinder so it shall need additional equipment, as long as fumes / vapors are introduced to the air intake...

That's my thoughts... haven't tested either options... and as said, not an expert on this area so don't know which path would be better... or if there is even better avenues to do the same....

[RustyLugNut]

By simply heating the fuel rail just before the injectors. If you look at the vapor diagram of C8H18 (octane) you can see that octane boils at approximately 130 degrees F. This is easy to achieve in an automobile engine as coolant is more than this at operating temperatures. In modern pressurized coolant systems that can run above the boiling temperature of water, you have the opportunity to heat your gasoline (octane makes up the bulk of gasoline). Modern fuel systems pressurize the fuel rail to 45 pounds per square inch (Psi) so you don't have much worry about vapor lock.

Also, if you are injecting into the intake at valve opening you will have a pressure drop across the injector causing more differential between the boiling point and the working point causing near instantaneous vaporization of the fuel droplets as they enter the cylinder.

[Isaac Zachary]

A few things come to mind, however.

1. Gasoline is comprised of several liquids that boil from some 35 °C or 95 °F to some 200 °C or 395 °F. So heating it to water temps of around 200 °F or 97 °C isn't going to boil everything, but still could cause vapor lock with the lower temp boiling liquids.
2. Yes, the fuel rail is at a high pressure, but the compression stroke creates even more pressure than the fuel rail. So what would happen to those liquids that were liquid at 45psi, vaporized at 14psi (or whatever atmospheric is) and then get compressed back to 150psi or so?
3. I still feel it is imperative to take into account the total heat energy in the air and fuel. The question is how much heat energy does the charge need to keep all or at least a certain percent of the gasoline in a vaporized form. For an example, boiling fuel also reduces temepratures. It takes a lot more heat energy to heat a liquid to a boil and boil it all out than to pressurize it and heat it up 10 or 20 degrees past it's boiling point. When such a pressurized liquid hits a pressure drop to atmospheric some of it boils off, but the rest just cools down to just under it's boiling point and stays a liquid.

[RustyLugNut]

Originally Posted by Isaac Zachary

A few things come to mind, however.

1. Gasoline is comprised of several liquids that boil from some 35 °C or 95 °F to some 200 °C or 395 °F. So heating it to water temps of around 200 °F or 97 °C isn't going to boil everything, but still could cause vapor lock with the lower temp boiling liquids.
2. Yes, the fuel rail is at a high pressure, but the compression stroke creates even more pressure than the fuel rail. So what would happen to those liquids that were liquid at 45psi, vaporized at 14psi (or whatever atmospheric is) and then get compressed back to 150psi or so?
3. I still feel it is imperative to take into account the total heat energy in the air and fuel. The question is how much heat energy does the charge need to keep all or at least a certain percent of the gasoline in a vaporized form. For an example, boiling fuel also reduces temepratures. It takes a lot more heat energy to heat a liquid to a boil and boil it all out than to pressurize it and heat it up 10 or 20 degrees past it's boiling point. When such a pressurized liquid hits a pressure drop to atmospheric some of it boils off, but the rest just cools down to just under it's boiling point and stays a liquid.

As to point number 1:

The majority of the gasoline is comprised of C8 to C9 carbon chains. A small percentage of heavier oils are contained but comprise such a small amount as to be immaterial to the discussion. The small amount of lighter carbon chains are bound by weak intermolecular bonds to the longer heavier chains (surface tension). These dominate and reduce the boil out of the light components. Think about how long it takes for pure rubbing alcohol to evaporate on a warm day. Mix it with water and it takes much longer. At only a few percent alcohol, the evaporation rate is dominated by the water. This is why you do NOT get vapor lock even if your fuel rail is at 40 C and the dissolved butanes, pentanes, propanes, etc. have far lower boiling temperatures than 40 C which is the typical fuel temperature on a normal summer day.

As to point number 2:

You are forgetting the ideal gas law. As you rapidly compress the fuel air mixture in the cylinder, the temperature rises too. You know this to be true for diesel engines to the point they auto ignite the fuel injected at the top of the compression stroke. Also, temperature is simply a measure of the vibrational kinetic energy of the gas. Gas turbulence is energy into the system. Most modern engines have both tumble and spin designed into their intake tracts resulting in additional energy contained in the fuel mixture to promote gasification as well as to prevent recondensation and drop out.

Also, recondensation takes TIME and CONCENTRATION. It is not as simple as reaching the condensation point (pressure and temperature) of a fuel and expect it to instantly drop out as liquid droplets. It takes time for the individual molecules to find another partner molecule to Coalesce into a pair, find another molecule to join them . . . and so on, until you get a droplet. Throw in the fact that the majority of the molecules (a factor of 14.7 parts by mass) are air molecules and you start to see how the fuel will stay in a vapor state well beyond the milli-seconds level event even an idling engine will experience.

As to point number 3:

Once the fuel is injected out of the orifice, the fuel stream experiences internal as well as external shear and collisions. This is added to the energy sum of the fuel/air mix. The velocity differential between the moving air stream and the fuel stream also adds to this sum. A well-designed injection system will take all of this into account and will result in a combustion mixture that is almost all in a vapor phase. As pointed out above, once in a vapor phase, there is not enough time for the fuel to coalesce, agglomerate and condense.

Do you want an everyday operational proof of what I have just stated? Direct injected spark ignited gasoline engines are now known to produce carbon soot particulates. They inject at bottom dead center or after the intake valves close. They don't have the time to evaporate the liquid droplets entirely. Just as you mentioned, the increasing cylinder pressure makes vaporization more problematical. It is only a small mass percent of the total fuel injected but that soot is a sign of incomplete vaporization. Instead of tens of PSI of fuel pressure, Direct Injection engines use thousands of PSI in an attempt to form smaller droplets that can evaporate more rapidly but the problem still remains. Port injected engines on the other hand, do not produce soot particulates AT ALL! This shows you that the vaporization is complete otherwise any droplets would turn into carbon with the heat from the flame front. They do produce partially burned hydrocarbons and carbon monoxide but that also shows that vapor is what is being incorrectly burned, not liquids. The small amount of carbon particulates collected in laboratory settings is attributed to oil slip - lubricating oil getting into the combustion chamber.

Do you want an interesting aside?

A company called Transonic Combustion used high pressure injectors (up to 8000 psi) with fuel heated (300 C) to put the hydrocarbons within the critical point. Critical liquids have unusually high diffusion rates. They claimed a reduction of 50% fuel use (reduced brake-specific-fuel-consumption)as well as claims of ultra-clean emissions without after treatment. Unfortunately, their website seems dead and maybe so is their company.

[pgfpro]

Great discussion guys, even though the chemistry is over my head lol.

I wish I could post video on here, I guess I could do a YouTube video.

When I tested with a simple Coleman lantern utilizing the gas generator tube and heated it to 400*F and simply turned the valve open and observed the fuel that came out all the while shooting it with an infra-red gun, it was visually 100% gas invisible until around 252*F, then it looked like smoke then in just a few seconds went to a fine fuel droplet as it cooled.

first pic 275*F invisible gas even used a mirror that was at room temperature to collect the gas to see if it would leave any small droplets on the mirror. I couldn't see any droplets at all.

second pic right around 125*F it goes from gas to small fuel droplets.

[cRiPpLe_rOoStEr]

Originally Posted by tomi_k

Yes, PCV is connected to the engine oil "fumes" but principle is same.... intent is to re-circulate "fumes / vapor", not liquids (i.e. not oils)... EVAP is designed to re-circulate evaporated fuel from the gas tank... again, principle is same... re-circulating "fumes / vapors" back to engine intake manifold.

But those fumes are released naturally, unlike what a gas vapor system would be supposed to do. Thermal energy to vaporize gas and eventually some oil too, should be accounted in order to find out how efficient it would be. Unless you'd resort to some sort of heat recovery from the exhaust, most likely there would be no improvement to the efficiency.

[Isaac Zachary]

Originally Posted by RustyLugNut

As to point number 1:

The majority of the gasoline is comprised of C8 to C9 carbon chains. A small percentage of heavier oils are contained but comprise such a small amount as to be immaterial to the discussion. The small amount of lighter carbon chains are bound by weak intermolecular bonds to the longer heavier chains (surface tension). These dominate and reduce the boil out of the light components. Think about how long it takes for pure rubbing alcohol to evaporate on a warm day. Mix it with water and it takes much longer. At only a few percent alcohol, the evaporation rate is dominated by the water. This is why you do NOT get vapor lock even if your fuel rail is at 40 C and the dissolved butanes, pentanes, propanes, etc. have far lower boiling temperatures than 40 C which is the typical fuel temperature on a normal summer day.

As to point number 2:

You are forgetting the ideal gas law. As you rapidly compress the fuel air mixture in the cylinder, the temperature rises too. You know this to be true for diesel engines to the point they auto ignite the fuel injected at the top of the compression stroke. Also, temperature is simply a measure of the vibrational kinetic energy of the gas. Gas turbulence is energy into the system. Most modern engines have both tumble and spin designed into their intake tracts resulting in additional energy contained in the fuel mixture to promote gasification as well as to prevent recondensation and drop out.

Also, recondensation takes TIME and CONCENTRATION. It is not as simple as reaching the condensation point (pressure and temperature) of a fuel and expect it to instantly drop out as liquid droplets. It takes time for the individual molecules to find another partner molecule to Coalesce into a pair, find another molecule to join them . . . and so on, until you get a droplet. Throw in the fact that the majority of the molecules (a factor of 14.7 parts by mass) are air molecules and you start to see how the fuel will stay in a vapor state well beyond the milli-seconds level event even an idling engine will experience.

As to point number 3:

Once the fuel is injected out of the orifice, the fuel stream experiences internal as well as external shear and collisions. This is added to the energy sum of the fuel/air mix. The velocity differential between the moving air stream and the fuel stream also adds to this sum. A well-designed injection system will take all of this into account and will result in a combustion mixture that is almost all in a vapor phase. As pointed out above, once in a vapor phase, there is not enough time for the fuel to coalesce, agglomerate and condense.

Do you want an everyday operational proof of what I have just stated? Direct injected spark ignited gasoline engines are now known to produce carbon soot particulates. They inject at bottom dead center or after the intake valves close. They don't have the time to evaporate the liquid droplets entirely. Just as you mentioned, the increasing cylinder pressure makes vaporization more problematical. It is only a small mass percent of the total fuel injected but that soot is a sign of incomplete vaporization. Instead of tens of PSI of fuel pressure, Direct Injection engines use thousands of PSI in an attempt to form smaller droplets that can evaporate more rapidly but the problem still remains. Port injected engines on the other hand, do not produce soot particulates AT ALL! This shows you that the vaporization is complete otherwise any droplets would turn into carbon with the heat from the flame front. They do produce partially burned hydrocarbons and carbon monoxide but that also shows that vapor is what is being incorrectly burned, not liquids. The small amount of carbon particulates collected in laboratory settings is attributed to oil slip - lubricating oil getting into the combustion chamber.

Do you want an interesting aside?

A company called Transonic Combustion used high pressure injectors (up to 8000 psi) with fuel heated (300 C) to put the hydrocarbons within the critical point. Critical liquids have unusually high diffusion rates. They claimed a reduction of 50% fuel use (reduced brake-specific-fuel-consumption)as well as claims of ultra-clean emissions without after treatment. Unfortunately, their website seems dead and maybe so is their company.

So compared with what we've been doing, heating the fuel reduces fuel use by 50%? I'm sorry but that doesn't sound correct. For one, there's still not that much difference between spraying in fuel without heating it to 300°C and not heating it. Most of it evaporates already, which is why it's called "gasoline." And if fully evaporating all of it produced such great results, then fuels like natural gas should produce similar efficiencies when comparing energy to energy.

[pgfpro]

1st pic. This is my Hot Air Intake Injection system.
2nd pic this is a pic of my type of intake looking at the ports where the hot air enters the intake port and is aimed straight at the fuel injector spray.

I did a test on this system a few years ago, where it really shined was during our winter months. With this system and a fuel heating system. I could see an improvement of 2mpg during the winter months only, in the Summer there was a very small gain.

This system really helps with increasing my IAT's 200*F plus to help with keeping the intake pressure at around 1psi. Even a difference of 150*F IAT to 250*F IAT keeping everything the same A/F, MAP, etc. will give me a 7mpg increase due to the PV=NrT equation.

[RustyLugNut]

Originally Posted by Isaac Zachary

So compared with what we've been doing, heating the fuel reduces fuel use by 50%? I'm sorry but that doesn't sound correct. For one, there's still not that much difference between spraying in fuel without heating it to 300°C and not heating it. Most of it evaporates already, which is why it's called "gasoline." And if fully evaporating all of it produced such great results, then fuels like natural gas should produce similar efficiencies when comparing energy to energy.

Modern engines burn pretty much all the fuel dispensed, within the power stroke. Simply vaporizing the fuel before it enters the engine does not gain you any additional efficiency unless your fuel system was primitive.

However, as mentioned in another Ecomodder Thread, HOW the fuel burns has tremendous room for improvement. The work that people such as Ivey and pfgPro have done show that there is room to improve thermal efficiency via the addition of energy to the fuel mix. Heating is just one variable. Tumble and swirl is another. Addition of oxidative or reactive elements or compounds is worth a closer look.

I mentioned the work by Transonic Combustion Technology because it does NOT make sense to most people on a simple precursory viewing. Their advertised gains are valid, however. Injection of gasoline heated to 300 degrees C while at 8000 psi puts it in a super-critical state whereas the fluid/gas has unusually high diffusion rate (something like three orders of magnitude greater than standard state) resulting in deep penetration into the combustion chamber BEFORE auto ignition can occur. When auto ignition does occur, the mixture is fully gaseous and HCCI (homogeneous charge compression ignition) comes into play. Their engine was tested by the Society of Automobile Engineers in Detroit and the fuel efficiency gains as well as the emission claims were validated and awards were given thus this technology is not snake oil. The engine ran as a throttle-less engine. Mazda's HCCI capable SkyActive engine can only use HCCI in a narrow band. The beauty of Transonic's Technology is the ability to run HCCI in the ENTIRE power band! The problem of their technology they were unable to overcome was that: a few psi extra pressure or a few degrees extra temperature and carbon would form. And not just soft fluffy carbon, but something akin to industrial diamonds. You can imagine the effect on injector longevity.

All this being said, the work of Ivey and pfgPro is sneaking up on the fabled Smokey Yunick Adiabatic Engine. From everything I can glean, his engine was on the threshold of HCCI combustion but, not quite. I think pfgPro's engine is leveraging the above discussed principles to approach the HCCI regime creating a faster burn than normal resulting in far less need for ignition lead time and wasted burn in the lagging portion of the power stroke. This is especially evident in the fact that when he is running 30:1 air/fuel ratios (AFR), his ignition lead is reasonable and his combustion stability is good.

Smokey used carburetors and eschewed electronics. pfgPro is leveraging modern electronic controls. We can see how advantageous that is. I think we can create a near HCCI engine that runs in a much broader range than Mazda's SkyActive system.

[Isaac Zachary]

Originally Posted by RustyLugNut

Modern engines burn pretty much all the fuel dispensed, within the power stroke. Simply vaporizing the fuel before it enters the engine does not gain you any additional efficiency unless your fuel system was primitive.

However, as mentioned in another Ecomodder Thread, HOW the fuel burns has tremendous room for improvement. The work that people such as Ivey and pfgPro have done show that there is room to improve thermal efficiency via the addition of energy to the fuel mix. Heating is just one variable. Tumble and swirl is another. Addition of oxidative or reactive elements or compounds is worth a closer look.

I mentioned the work by Transonic Combustion Technology because it does NOT make sense to most people on a simple precursory viewing. Their advertised gains are valid, however. Injection of gasoline heated to 300 degrees C while at 8000 psi puts it in a super-critical state whereas the fluid/gas has unusually high diffusion rate (something like three orders of magnitude greater than standard state) resulting in deep penetration into the combustion chamber BEFORE auto ignition can occur. When auto ignition does occur, the mixture is fully gaseous and HCCI (homogeneous charge compression ignition) comes into play. Their engine was tested by the Society of Automobile Engineers in Detroit and the fuel efficiency gains as well as the emission claims were validated and awards were given thus this technology is not snake oil. The engine ran as a throttle-less engine. Mazda's HCCI capable SkyActive engine can only use HCCI in a narrow band. The beauty of Transonic's Technology is the ability to run HCCI in the ENTIRE power band! The problem of their technology they were unable to overcome was that: a few psi extra pressure or a few degrees extra temperature and carbon would form. And not just soft fluffy carbon, but something akin to industrial diamonds. You can imagine the effect on injector longevity.

All this being said, the work of Ivey and pfgPro is sneaking up on the fabled Smokey Yunick Adiabatic Engine. From everything I can glean, his engine was on the threshold of HCCI combustion but, not quite. I think pfgPro's engine is leveraging the above discussed principles to approach the HCCI regime creating a faster burn than normal resulting in far less need for ignition lead time and wasted burn in the lagging portion of the power stroke. This is especially evident in the fact that when he is running 30:1 air/fuel ratios (AFR), his ignition lead is reasonable and his combustion stability is good.

Smokey used carburetors and eschewed electronics. pfgPro is leveraging modern electronic controls. We can see how advantageous that is. I think we can create a near HCCI engine that runs in a much broader range than Mazda's SkyActive system.

I see. Very interesting. And yes, I see what you're saying now.

Lean burn is one advantage that other gaseous engines have. I've heard of running 30:1 or leaner in propane and natural gas engines, and even way leaner in hydrogen engines. At those levels emissions almost dissapear as it can't get hot enough for NOx to form, although getting rid of any NOx in the exhaust becomes much more dificult with so much oxygen. The point is it's something that's obviously been proven.

Same with HCCI.

And yes, better ways of burning fuel is where it's at. There have been big improvements in intake design over the years that focus more on fuel atomization and trying to keep fuel from deatomizing.

I'm just trying to keep everyone's expectations in check. No offense to the OP, but some comments here seem to me to be overly optomistic and I might go a bit too far in trying to keep expectations in check.

Originally Posted by racprops

And the only other classic idea is Gasoline VAPOR.

Claims and reports of 100MPG are all over the place.

Fish Carb, Tom Ogal's system, etc.

I will see if I can do a proof of concept device.

Rich