The Air To Fuel Ratio Calculator (AFR), essential for various technologies like internal combustion engines and heating devices, determines the ratio of air to fuel needed for complete combustion. This ratio is crucial for efficient processes in systems such as cars, rockets, and power plants.

## Understanding Air-Fuel Ratio (AFR)

As discovered by Lavoisier, oxygen is vital for combustion. The AFR represents the amount of air required for the complete combustion of a specific amount of fuel. It is often expressed as the mass of air divided by the mass of fuel.

The AFR can also be calculated using molar ratios and molar masses, providing a more in-depth understanding of the combustion process.

## AFR of Common Fuels

Different fuels have distinct AFR values. Here are the AFR values for various hydrocarbon fuels, expressed in both mass and molar terms:

• Methane: 17.19 (mass), 9.52 (molar)
• Ethane: 16.95 (mass), 16.66 (molar)
• Propane: 15.64 (mass), 23.80 (molar)
• Butane: 15.42 (mass), 30.94 (molar)
• Pentane: 15.29 (mass), 38.08 (molar)
• Octane: 15.09 (mass), 59.50 (molar)
• Diesel: 14.6 (mass), 84.49 (molar)
• Hydrogen: 34.21 (mass), 2.38 (molar)

## Calculating Stoichiometric Air-Fuel Ratio

The stoichiometric air-fuel ratio represents the minimum air needed for complete combustion. The formula for the complete combustion of a hydrocarbon fuel with theoretical air involves balancing the chemical reaction. This requires determining coefficients based on the number of carbon and hydrogen atoms in the fuel.

## Using the AFR Calculator

To use the AFR calculator:

1. Choose a fuel from the list.
2. The calculator displays the AFR for the selected substance.
3. For instance, if selecting methane (CH4), with an AFR of 17.19:1, it means 17.19 kg of air is needed for the combustion of 1 kg of methane.
4. In the Mass of air and fuel section, enter the mass of fuel or air, and the calculator provides the mass of the other substance.

The AFR calculator operates bidirectionally, allowing users to input either the mass of air and fuel or both, obtaining the corresponding AFR as a result.

These comprehensive calculations and explanations facilitate a deeper understanding of combustion processes, aiding in the optimization of various technologies.