Combustion efficiency with E85
Combustion efficiency with E85
(OP)
Does anyone have any actual data of combustion efficiency vs equivalence ratio for E85? I have data for gasoline, but not E85.
Thanks in advance!
Thanks in advance!
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Combustion efficiency with E85
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RE: Combustion efficiency with E85
RE: Combustion efficiency with E85
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Combustion efficiency with E85
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers for professional engineers
RE: Combustion efficiency with E85
RE: Combustion efficiency with E85
So, guessing that you aren't just using an engine to warm water with, what do you actually want to know?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Combustion efficiency with E85
RE: Combustion efficiency with E85
You are probably looking for the shaft work /out/ for a given LHV of fuel in. =Wout/Qhv=(Qhv-Qout)/Qhv=BSFC/mdot/LHV
As Pat says, which fuel is your engine optimised for?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Combustion efficiency with E85
RE: Combustion efficiency with E85
- Steve
RE: Combustion efficiency with E85
RE: Combustion efficiency with E85
Qin/(mf*Qhv) is indicated fuel conversion efficiency
Would finding the adiabatic flame temp of gasoline VS ethanol at stoich combustion help you?
RE: Combustion efficiency with E85
For indicated fuel-conversion efficiency, I use the definition,
ηfi = ηt*ηc = Wc/(mf*Qhv)
where ηt = thermal-conversion efficiency, and ηc = combustion efficiency, i.e.,
ηt = Wc/Qin
ηc = Qin/(mf*Qhv)
I studied primarily from Heywood, so his are the definitions I tend to use.
Incomplete combustion reduces temps, and I'm interested in equiv ratios higher than stoich, so max adiabatic flame temp at AFRs does not help me, unfortunately. But I do really appreciate the offer to help!
Eric
RE: Combustion efficiency with E85
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Combustion efficiency with E85
I'd be tempted to grab an engine simulation program that uses thermochemical equilibrium as a basis for its gas properties and create some combustion bomb experiments.
- Steve
RE: Combustion efficiency with E85
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The combustion efficency should not be any different on the same engine that is capable of ingesting the fuel. What I mean by that is, if the engine is built with 11 to 1 compresion ratio to take advantage of e85 octane, when you put in 85 octane regular gasoline, there will be a loss in efficency due to retardation and the ECU running rich to keep from burning holes in the piston.
So a 9 to 1 compression ratio enegine tuned for each fuel should have the same thermal efficency or within tolerances of the measurement system.
RE: Combustion efficiency with E85
No, the fuel will affect the ratio of specific heats which will affect heat release and work, albiet not a great deal.