Heat of Combustion Calculator

Heat of Combustion Calculator

The Heat of Combustion Calculator computes the higher heating value (HHV) of a fuel from its lower heating value (LHV) and the energy needed to condense water vapor produced during combustion.

$$H_c = LHV + H_v \cdot \frac{n_{H_2O}}{n_{fuel}}$$

where $H_c$ is the heat of combustion, $LHV$ is the lower heating value, $H_v$ is the heat of vaporization of water, $n_{H_2O}$ is moles of water vaporized, and $n_{fuel}$ is moles of fuel combusted.

Example: methane with LHV = 50 MJ/kg, $H_v$ = 2.257 MJ/kg, 5 mol water per 2 mol fuel gives $H_c = 50 + 2.257 \times (5/2) = 55.64$ MJ/kg.

Heat of combustion is used in engine design, fuel quality assessment, and energy recovery systems. The higher heating value includes energy from condensing water vapor, while the lower heating value assumes that vapor escapes.

Related tools: Combustion Analysis Calculator, Chemical Entropy Calculator, and Specific Heat Calculator.