Relative Air-Fuel Ratio Formula

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Relative Air Fuel Ratio indicates whether the mixture is rich (< 1) or lean (> 1) compared to the ideal stoichiometric ratio. It is the ratio of air and fuel in a mixture that is ready for combustion. Check FAQs
Φ=RaRi
Φ - Relative Air Fuel Ratio?Ra - Actual Air Fuel Ratio?Ri - Stoichiometric Air Fuel Ratio?

Relative Air-Fuel Ratio Example

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With units
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Here is how the Relative Air-Fuel Ratio equation looks like with Values.

Here is how the Relative Air-Fuel Ratio equation looks like with Units.

Here is how the Relative Air-Fuel Ratio equation looks like.

1.088Edit=15.9936Edit14.7Edit
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Relative Air-Fuel Ratio Solution

Follow our step by step solution on how to calculate Relative Air-Fuel Ratio?

FIRST Step Consider the formula
Φ=RaRi
Next Step Substitute values of Variables
Φ=15.993614.7
Next Step Prepare to Evaluate
Φ=15.993614.7
LAST Step Evaluate
Φ=1.088

Relative Air-Fuel Ratio Formula Elements

Variables
Relative Air Fuel Ratio
Relative Air Fuel Ratio indicates whether the mixture is rich (< 1) or lean (> 1) compared to the ideal stoichiometric ratio. It is the ratio of air and fuel in a mixture that is ready for combustion.
Symbol: Φ
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.
Actual Air Fuel Ratio
Actual air fuel ratio is the actual mass of air mixed with actual mass of fuel that is present during combustion inside IC engine. It is a crucial parameter for good fuel economy in IC engines.
Symbol: Ra
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.
Stoichiometric Air Fuel Ratio
Stoichiometric air fuel ratio refers to a mixture that contains just enough air for complete combustion of all the fuel in the mixture. Achieving a stoichiometric ratio minimizes harmful emissions.
Symbol: Ri
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.

Other formulas in Air Standard Cycles category

​Go Mean Effective Pressure in Otto Cycle
PO=P1r((rγ-1-1)(rp-1)(r-1)(γ-1))
​Go Mean Effective Pressure in Diesel Cycle
PD=P1γrγ(rc-1)-r(rcγ-1)(γ-1)(r-1)
​Go Mean Effective Pressure in Dual Cycle
Pd=P1rγ((Rp-1)+γRp(rc-1))-r(Rprcγ-1)(γ-1)(r-1)
​Go Work Output for Otto Cycle
Wo=P1V1(rp-1)(rγ-1-1)γ-1

How to Evaluate Relative Air-Fuel Ratio?

Relative Air-Fuel Ratio evaluator uses Relative Air Fuel Ratio = Actual Air Fuel Ratio/Stoichiometric Air Fuel Ratio to evaluate the Relative Air Fuel Ratio, Relative Air-Fuel Ratio is a concept used to describe the actual air-fuel mixture present in an engine compared to the ideal or chemically correct mixture(Stoichiometric A/F ratio). It compares the actual air-fuel mixture in the engine to the stoichiometric ratio. A Relative AFR of 1 indicates a stoichiometric mixture. Values less than 1 represent rich mixtures, and values greater than 1 indicate lean mixtures. Understanding Relative A/F ratio is crucial for engine performance and emissions. Relative Air Fuel Ratio is denoted by Φ symbol.

How to evaluate Relative Air-Fuel Ratio using this online evaluator? To use this online evaluator for Relative Air-Fuel Ratio, enter Actual Air Fuel Ratio (Ra) & Stoichiometric Air Fuel Ratio (Ri) and hit the calculate button.

FAQs on Relative Air-Fuel Ratio

What is the formula to find Relative Air-Fuel Ratio?
The formula of Relative Air-Fuel Ratio is expressed as Relative Air Fuel Ratio = Actual Air Fuel Ratio/Stoichiometric Air Fuel Ratio. Here is an example- 1.088 = 15.9936/14.7.
How to calculate Relative Air-Fuel Ratio?
With Actual Air Fuel Ratio (Ra) & Stoichiometric Air Fuel Ratio (Ri) we can find Relative Air-Fuel Ratio using the formula - Relative Air Fuel Ratio = Actual Air Fuel Ratio/Stoichiometric Air Fuel Ratio.
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