Quote:
Originally Posted by racprops
So now to my idea, based on the idea and claim that part of the reason for so much waste IS the slow conversion of liquid gasoline to a vapor state within the combustion chamber and how no mater how find a mist is sprayed into it on 30/35% is converted to vapor in time to make power, the rest is burned after the power stroke, then during the exhaust stroke on its way out of the head and still burning going though the exhauset headers and to the first catalytic convertors.
The claim is IF we can convert gasoline 100% to vapor before it is fed into the combustion chamber six things will happen.
One, complete combustion.
Two, only say 30 or less of the fuel will be needed.
Three, engine will run MUCH cooler.
Four, four Exhaust gasses might be much cleaner perhaps below current requirements due to more complete combustion.
Five, Perhaps more power due to not compressing against expanding gasoline already burning during the last 30/40 degrees of crank rotation.
Six, using much less fuel could/should mean much better MPG.
Rich
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I spoke with my FIL about this a few Thanksgivings ago - he was a mechanical engineer at Ford, and signed off on the Mustang Mach E most recently before his retirement. We talk about cars a lot.
From our discussions, one thing I took away: It's true that getting gasoline to vaporize is an issue, but it's an issue that has already been solved with port injected engines. There isn't any low hanging fruit there anymore.
~
This next bit is my own take, and not from the mouth of a senior engineer from Ford with 35 years' experience working on combustion.
1) Combustion is already basically complete. Some engines burn the charge
faster (see Toyota's latest designs), which can improve fuel economy, but basically all modern engines have complete combustion.
2) Engineers are chasing the last 1-3%, not 70%.
3) This one is a bit complex but most of the energy lost from an internal combustion engine is not from fuel burning in the exhaust, but a function of the surface area inside the cylinder, and the amount of time it's exposed to the combustion charge. Inevitably, when you have 3-5000 degree gases inside a metal cylinder, some of that will conduct through the cylinder walls and end up in the cooling system. With a given expansion ratio, you can only extract so much energy (compare to a heat pump), which is part of why we're seeing compression ratios still going up, but once the gases have been expanded, anything left goes out the exhaust.
There is one other way to decrease heat loss, other than to increase compression ratios: Reduce cylinder counts. Larger and fewer cylinders results in a greater volume to surface area ratio, which reduces thermal losses. This is why we're now seeing 3 cylinder engines showing up in supercars.
5/6) Fuel burning later in the crank angle does still contribute to engine power, it isn't working against the engine. However, Mazda seems to have figured out the solution to this one: they have a compression ignition gasoline engine out now.
How it works: It has a very high (diesel level) static compression ratio AND a supercharger, and has sensors inside the combustion chamber. It compresses the gasoline and air mixture and times when it lights it off with a spark plug to
intentionally cause the contents of the cylinder to detonate, or "knock". Basically the entire fuel and air charge explodes all at once, rather than burning outward from the spark plug, the same way a diesel engine operates. This allows release of 100% of the energy instantaneously at an optimal crank angle. Mazda is claiming an approximate 20% reduction in fuel consumption over their previous generation engines, which were good, but not class-leading.
Aaaaand that's basically the end of the road for combustion improvements, once you have compression ignition. Anything past that and we'd be looking at harvesting exhaust heat with turbochargers attached to electric generators, or something along those lines. Or, maybe coating the insides of the combustion chamber with ceramics (if they'd survive) to reduce heat soaking through. Or, fractionally reducing friction.