Mass-fraction of oxygen as a predictor of HHV of gaseous, liquid and solid fuels

Abstract

The higher heating value (HHV) of gaseous, liquid and solid fuels is demonstrated to be a strong function of the mass fraction of oxygen required for combustion, and suitable correlations are proposed to describe this relationship accurately. A 4th order correlation was found to be the best for estimating HHV as an all-purpose correlation with a root-mean-square error (RMSE) of 1.2 MJ/kg, coefficient of determination (R2) value of 0.9900 and mean bias error (MBE) of 0.40 %. A 3rd order correlation was as accurate with an RMSE of 1.2 MJ/kg, R2 value of 0.9898 and an MBE of – 0.16 %. In addition, the linear relationship between the HHV and oxygen required for combustion on a mole basis is demonstrated and an alternative mole-based correlation is proposed. A total of 311 HHV data from various sources are used to validate these correlations and 13 other correlations available in the literature are used for further comparison.