Dear all,
Burning mass fraction gives a strong indication of the validity of experimental pressure data. We need to start a discussion with researchers faced such a problem finding burning mass fraction has misleading value (higher than 100% or very low 50%) and how did they solve the problem.
According literature there are many errors that can lead to that:
1: Phasing angle error (very effective)
2: Pegging pressure error.
3. Noisy signals.
4. Error in intake air mass.
Calculating burning mass fraction for diesel combustion has a simple formula (Total heat release/ fuel energy) but it'snot an easy task to get logic results due to the last errors.
If u have some experience in that field, kindly share it with us. Because heat release analysis is a crucial tool in combustion science , we need more understanding of it.
Regards,
Mahmoud
I trust you have answered your own question regarding the reason for inaccuracy are the measuring errors as you have stated.
There should be a very close relationship between mass fraction burned and heat release. After all, that is chemistry and physics.
How are you defining the errors of 'higher (larger?) than 100% or very low of 50%' . Which are the nominator and divisor?
Thanks for your answer Dr. Rolf Pfeiffer . I calculate burning mass fraction by dividing the cumulative heat (integration of heat release curve) over the fuel energy (fuel mass* lower heating value). But I get the burnt mass fraction reach only 56%.maximum value I want to know if someone has experienced this problem before and how can I correct the experimental results so i can get right results .
You are obtaining too much heat for the mass fraction burned by a factor near 1.8. That seems odd. If you would reach half that heat near 0.9 of mass fraction burned would make more sense. It appears that your calculations or measurement for heat and or mass fraction burned contain errors. I know that does not really help you, but I have no way of knowing how you measure. Most likely it is based on the data input you use.
The mass fraction burned and heat release are accurate. Take this as correct and work you way backwards to determine the other factors.
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