Modification of Dulong's formula to estimate heating value of gas, liquid and solid fuels

• Extensibility of Estimation equations for the heating value of fuels were investigated.
• Reported estimation equations were not applicable to gaseous fuels.
• Modification of Dulong's formula was performed considering latent heat.
• Modified Dulong's formula well represents the heating value of various fuels.

Estimation equations for determining the heating value of hydrocarbon fuels were evaluated. Several types of estimation equations were proposed so far to determine the heating value on the basis of the elemental composition. The estimation equations were used to evaluate the elemental composition and the heating value of 406 standard gaseous organic compounds. As a result of the evaluation, Dulong's formula was appropriate for estimating the heating value; however, only a limited range of heating values can be determined, because Dulong's formula was developed for determining heating value of coals, which have unidentified structures. Another reason for the limitation was that the effect of latent heat. Therefore, Dulong's formula were modified with the lower heating values (LHV) of 406 standard gaseous organic compounds, which have identified structures, to obtain the following modified formula taking latent heat into account: