Joe,
You are correct it was referring to BTUs, but lost BTUs is lost power,
isn't it. I was not saying that running hotter would give more HP with
the limitations we have to deal with. However, it still seems to me that
if you could use more of the heat produced, then you would have better
performance. It just isn't practical yet.
Tom, Redding CA - #216 D/CC
Joe & Lynne Lance wrote:
> Tom, I think what the old textbook really said was that only 30% of the BTU
> content of the FUEL is converted into engine power to drive the car, and all
> the other percentages are also percentages of the input fuel BTU content.
>
> Smokey Yunick's adiabatic engine, I believe, was intended to minimize the
> amount of fuel BTUs lost in waste heat in order to increase efficiency but
> that approach gets very complicated. Years ago (10-15?) some research was
> being done on ceramic engines along the lines of Smokey's idea, but I
> haven't heard anything about that lately.
>
> Sometimes equating high temperatures with high efficiency can be misleading
> because it deals with only the First Law of Thermodynamics. The Second Law
> of Thermodynamics deals with effectiveness or what percentage of Carnot
> efficiency you can get--which means that you want the lowest peak combustion
> temperature possible for a given power output from the fuel. All of this
> stuff is very important for fuel burning electric utility power plants, but
> don't think it means much for Land Speed engines (as long as friction and
> other parasitic losses are minimized) where the objective is to maximize the
> amount of fuel/oxygen pumped in to maximize horsepower and the hell with
> Carnot effectiveness! So I don't think trying to run at much higher engine
> temperatures will payoff.
>
> Lance
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