Standard thermodynamic properties for the energy grade evaluation of fossil fuels and renewable fuels

Abstract

Increasing development of future fuels, such as fossil fuels and renewable fuels, requires the evaluation method and data of fuels’ energy grade, which is derived from the enthalpy and exergy. However, few models can simultaneously and accurately predict the enthalpy and exergy. This work proposed prediction models to calculate the standard enthalpy and standard exergy of fuels. The models were established under the unified thermodynamic reference system, ensuring the thermodynamic consistency and the reliability of prediction result. The models need only value of the standard combustion heat and do not require composition of the fuel. The model functions are simple and easy for application. Model parameters were regressed based on the data of the standard enthalpy of formation and the standard Gibbs energy of formation of 194 typical fuel representatives. The high accuracy of new models was proved by comparison with 5 traditional models. Then, the new models were used to estimate the energy characteristics of 39 typical future fuels, including biodiesel, alcohol fuel, cellulosic fuel, marsh gas, and municipal refuse. Finally, the standard thermodynamic properties of these fuels were calculated, and some new opinions regarding the energy characteristics of future fuels were discussed.