What is equivalence ratio and lambda?

Φ (phi) = AFR_stoich/AFR_actual. Φ 1 is rich (excess fuel). Lambda λ = 1/Φ. Otto engines target λ = 1 for three-way catalyst; diesel runs lean (λ = 1.2-2+).

How is stoichiometric AFR calculated from fuel formula?

For C_nH_m: O₂ needed = n + m/4 moles per mole fuel. With air 23.2% O₂ by mass: AFR = (32(n+m/4))/M_fuel × (1/0.232). For CH₄: AFR = 32(1+1)/16 × 4.31 = 17.2.

What happens at rich vs lean combustion?

Rich combustion (Φ>1): unburned fuel, CO, reduced NOx, soot (diesel). Lean combustion (Φ<1): excess O₂, complete combustion, higher NOx, risk of misfire below Φ=0.5.

Stoichiometric Air-Fuel Ratio Calculator

Calculate stoichiometric air-fuel ratio from fuel composition. Natural gas: AFR ≈ 17.2:1, gasoline: AFR ≈ 14.7:1, diesel: AFR ≈ 14.5:1, hydrogen: AFR ≈ 34.3:1. Equivalence ratio Φ = AFR_stoich/AFR_actual.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How It Works

Each component has a specific meaning:

Fuel composition — The fuel composition recorded for the patient or scenario being assessed.

Note: Interpret the air-fuel ratio result against the clinical thresholds and context described above.

How to Use

Enter the fuel composition for the patient or scenario you are assessing. Calculate stoichiometric air-fuel ratio from fuel composition. Natural gas: AFR ≈ 17.2:1, gasoline: AFR ≈ 14.7:1, diesel: AFR ≈ 14.5:1, hydrogen: AFR ≈ 34.3:1. Equivalence ratio Φ = AFR_stoich/AFR_actual. Use the air-fuel ratio result to inform your clinical assessment.

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