Flue Gas Water Vapor Calculator

Where Flue Gas Moisture Actually Comes From

Every fuel containing hydrogen produces water vapor when burned, since hydrogen combines with oxygen to form H2O. This water leaves with the flue gas unless the equipment is specifically designed to condense and recover it.

The Formula

Water Vapor Mass = 9 × Hydrogen Fraction × Fuel Mass

Each kg of hydrogen produces 9 kg of water, based on the molecular weight ratio of H2O (18) to H2 (2).

Worked Example

Burning 100 kg of a fuel that's 13% hydrogen by mass:

Water Vapor = 9 × 0.13 × 100 = 117 kg

How to Use This Calculator

Enter the fuel's Hydrogen percentage by mass.
Enter the Fuel Mass burned.
Select Calculate to get water vapor mass produced.

Related Calculations

Check whether this vapor will condense in the Dew Point of Flue Gas Calculator, or see its effect on heating value in the Lower Heating Value (LHV) Calculator.