gruntguru wrote: ↑Thu Feb 03, 2022 9:12 am
Apart from the gamma issue raised by Tommy, there is also a volume issue due to the number of moles present. This will even vary for different fuels eg Ethanol or E85 combusts to form a greater number of moles (or molecules) of exhaust gas than normal petrol. This increases exhaust gas volume and increases turbine power for a given engine and operating point.
isn't this factor - 'a volume issue due to the number of moles present' in effect already covered ?
ie alcohol fuel's inherent (extra) heat value (ie 'power') for a given air mass is (broadly ?) an equivalent
this (stoichiometric-mass) heat value ie power of ethanol is c. 4% more than gasoline's - and methanol's is c.10% more
(though their heat value ie power per given fuel mass as in F1 is of course lower)
but except at the dragstrip .....
75% or more of the cylinder charge is an inert 'working medium' for heat and work flow ....
25% or less is involved in exothermic chemical changes ie combustion
(only c. 0.001% is involved in endothermic chemical changes eg NOx - these being self-limiting)