A practical way to vaporize fuel for high MPG?

[tech99]

I am not sure we see unburnt fuel in a modern spark ignition engine, so I am doubtful abut the advantage of pre-vapourising the fuel.

 

[jack action]

I am not sure we see unburnt fuel in a modern spark ignition engine, so I am doubtful abut the advantage of pre-vapourising the fuel.

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

 

[Ranger Mike]

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

Absolutely brilliant reply, Jack!

 

[russ_watters]

I'm going to be lazy about this: Google AI tells me it's less than 1%.

 

[NTL2009]

I think this is a pretty good reason to believe there is next to no benefit:

Just being liquid vs vapor doesn't say much - it doesn't change the amount of energy available by more than a few percent (e.g., you could preheat a liquid fuel). In order for there to be much of a performance hit due to the fuel being liquid, it would have to be not burning or burning very late, and that just isn't happening.

Yes, but there is still a twist here. The author does state that running on vaporized fuel alone would have terrible performance. So modern engines set up with propane or LNG would be tuned differently, and not be talking (supposed) advantage of the lean ratio.

From my reading, it seems that the propane/LNG are delivered to fuel injectors as a liquid. So all the vaporization has to take place in or just before the cylinder. I'm guessing that still has time to vaporize, as it is vapor at normal atmosphere, but maybe not? But if it does have time to vaporize, and this allowed lean ratios, it would seem the computer could adjust for this, and provide lean ratio under light loads only (again, assuming there is a benefit)? So either there is no real benefit (as much of this conversations seems to point to), or there isn't a big enough market of propane/LNG vehicles to research leaner mixtures for low-load, or there are other problems with the lean mix - I think I've read you might need some unburnt fuel for the catalytic converter to handle other pollutants?

 

[NTL2009]

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

According to the Wikipedia article, it might sort of be the other way around?

https://en.wikipedia.org/wiki/Catalytic_converter

These "two-way" oxidation converters combine oxygen with carbon monoxide (CO) and unburned hydrocarbons (HC) to produce carbon dioxide (CO2) and water (H2O).

So reducing carbon monoxide. And...

"Three-way" converters, which also reduce oxides of nitrogen .... three-way-converters require fuel-rich or stoichiometric combustion to successfully reduce NO<em>x</em>.

reducing NOx - but some unburnt fuel is needed for the conversion. I think you can have very complete combustion, but with high NOx levels. So that would be a problem, and the 'solution' is - more unburnt fuel! Well, engineering is always a balancing act, right?

 

[FastForFun]

This thread is more and more reminding me of my very first thread, and the image that inspired it:

View attachment 366588

The image confused the hell out of me.

Smokey Yunick had the solution in 1984 with his Hot Vapor Cycle engine. By capturing and reusing heat normally dissipated, efficiency dramatically improves.

In his Pontiac 2.5 liter engine, he reduced the radiator size by 50% then applied the remaining heat energy via coolant to a heat exchanger surrounding and beneath the throttle body and single fuel injector, raising the air fuel mixture to 90-100 degrees C.

Air Fuel mixture then enters a homogenizer - basically a turbocharger. The homogenizer has a double wall where a controlled amount of hot exhaust acts to further heat the fuel air mixture to around 150 degrees C with simultaneous blending by the impeller.

Then the mixture enters the intake plenum and runners which are surrounded by another exhaust heat jacket bringing the mixture up to over 200 degrees C and past the heat of vaporization of gasoline. The turbocharger ran a low boost pressure, acting as a one way check valve while the mixture is heating and expanding.

Smokey made the observation that gasoline is a complex blend of compounds with different densities and heats of vaporization. Optimum combustion occurs with a unified homogeneous mixture. He noted much smoother engine running, more power and improved efficiency, netting 51 mpg and 250hp in the Fiero. He ran stoichiometric air fuel ratios of 14.7 to 1, but there are also accounts of his tinkering with leaner mixtures. The engine passed emissions regulations in effect in 1985. Likely issues were with Nitrogen Oxide emissions. This could be resolved now with electronic controls and reduction catalysts commonly used with diesel engines.

https://www.hotrod.com/features/the-next-step-june-1984-982-1238-26-1

 

[256bits]

Adding to this: a Mustang Mach-E gets about 3 mi / kWh, almost exactly equivalent to 100mpg, or 12 hp at 80% efficiency. It's in the ballpark of a fair comparison to a modern ICE sedan, since the efficiency of the ICE engine is probably below 25% when it is producing 10% power, and that doesn't include drivetrain losses (electric cars directly power the wheels whereas gas cars lose maybe another 15% between the engine and wheels).

For full hydrocarbon usage comparison, the coal fired power station efficiency, or other hydrocarbon fuel supplied, and transmission losses from power plant to charging station should be taken into account, when analyzing electric vs ICE. That 100mpg can drop significantly in the overall scheme of things.
I know that you speak of something else, and not that specifically.

 

[russ_watters]

For full hydrocarbon usage comparison, the coal fired power station efficiency, or other hydrocarbon fuel supplied, and transmission losses from power plant to charging station should be taken into account, when analyzing electric vs ICE. That 100mpg can drop significantly in the overall scheme of things.
I know that you speak of something else, and not that specifically.

Right, this thread is about how much power it takes to move a car, not where the "fuel" came from. But I agree we need a clean grid and are to some extent putting the cart before the horse with electric cars in the US.

 

[OmCheeto]

Has anyone done a 'miles per kg' analysis?
I have a strange feeling that we are all 'per gallon' biased.