That Wankel engines are thirsty is common knowledge. He's what the great Goo has to say about it:
All these except compression ratio become inherently worse as internal combustion engines decrease in size, regardless of type, due to square/cube effects. Seal length (therefore friction) scales linearly with size, surface area (therefore heat loss) scales with the square, but displacement scales as the cube. So energy losses hold up much much better than power as you scale down.
Thirsty:
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When a fuel and air mixture is "poorly quenched," it means the combustion process is not effectively stopped or cooled down quickly enough, resulting in unburned hydrocarbon molecules escaping into the exhaust system, essentially meaning that some of the fuel did not fully combust and is released as pollutants
That's not good!
I have some ideas on that I'm keeping under my hat for now.
I suspect that the power stroke in the same area of casing all the time results in overheating issues.
But doesn't in 2-strokes..? Added frictional heat from the apex seal? Surface Area.
Running Rich is a known and used method of cooling Turbo'd etc engines.
(The way to properly do it is water injection that has a
higher specific heat, and costs nothing.
Problem is water injection slows combustion, so the advantages in a piston engine are from increasing compression)
Spit balling:
But what happens if you run the air-fuel mixture through between the cooling fins over the hot area?
Evaporative cooling and evaporated, much faster burning charge..?
Aha!
Air-Cooled Rotary Engine: Compact Power for UAVs and Compact Systems
Also hotter intake area of the case, but not a hotter compression area.
Together that's a faster burning power stroke, cooler combustion area, a better heat spread and less uneven expansion.
But water cooling the the engine is still better IMHO.
As evaporation drops air temperatures sub ambient; perhaps a small post radiator, radiator in the intake after the fueling.
ie: Coolant cooled normally then some more with a sub ambient gas..?
Then Pyrolise the fuel completely with Exhaust heat and try for some steam reformation and/or Water-Gas Shift with catalytic surfaces to get a bit of Hydrogen..? (40% better fuel efficiency IIRC. Burn anything. Used in old tractors and such)
I want rotaries to work damn it!?
Surface Area to volume:
Hmmm...
Doubling all the dimensions of a cylinder increases its volume by 8X.
Its surface area by 4X
Inversely:
Halving all the dimensions of a cylinder decreases its volume by 8X.
Its surface area by 4X
So 8x less volume for 4X less surface means volume drops off faster than surface area, which means more surface area losing heat per cc...
So energy losses don't hold up with decreasing capacity...