EGR ratio from exhaust gas composition

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SUMMARY

The discussion centers on the calculation of the Exhaust Gas Recirculation (EGR) ratio from exhaust gas composition, specifically focusing on the mole ratios of CO2, H2O, and N2 in stoichiometric combustion. The participant concludes that molar ratios do not depend on the EGR ratio, even when excess air is present. They reference an SAE paper that suggests a relationship between the Fresh Air + EGR to Fuel ratio and exhaust concentrations, yet they find discrepancies in their results compared to the paper's findings.

PREREQUISITES
  • Understanding of stoichiometric combustion principles
  • Familiarity with exhaust gas composition analysis
  • Knowledge of EGR systems and their function
  • Ability to interpret SAE technical papers
NEXT STEPS
  • Review the SAE paper titled "2010-01-1285" for insights on EGR calculations
  • Study the relationship between exhaust gas concentrations and EGR ratios
  • Learn about the impact of excess air on combustion efficiency
  • Explore advanced methods for analyzing exhaust gas compositions
USEFUL FOR

Engineers, automotive researchers, and students studying combustion processes and EGR systems will benefit from this discussion.

mrcarbon4hydrohen

Homework Statement


given:-fuel and air mass flow, measured mole ratios of exhaust composition y_i. Let's assume stoichiometric combustion so we have only CO2, H20 and N2 as products.

Homework Equations


Can EGR ratio be calculated from available data?

The Attempt at a Solution


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I get result that molar ratios don't depend on EGR ratio.
 
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Your first equation already tells you this.
 
I have another question. I there is excess air, can EGR be determined? Folowing the same logic as before, it can't. This time I used a slightly different formula but result is the same.
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but..
I found a SAE paper in which (Fresh Air+EGR)/Fuel ratio is determined by exhaust concentrations. So I think there is connection between EGR and gas concentations in exhaust. This is the paper(you can see in preview of SAE paper what I am referring to, equation (3)): http://papers.sae.org/2010-01-1285/ .I tried to get solution as in paper, but got different result.
slika_3.png
 

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As best I can tell, the mole fractions of the gases in the exhaust are independent of the recycle ratio.
 

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