Additivity of chemical exergies of alkanes

A standard thermochemical model is proposed for the reference environment. Chemical exergies of liquid and gaseous alkanes were calculated over a wide temperature range using the proposed model. The exergies of alkanes may be calculated using additive methods. Two additive schemes were studied: a scheme with effective bonds and a replacement scheme. The thermal dependence of the additive constants was investigated. Each compound in the liquid state has a different temperature range for the initial thermodynamic data. This fact limits exergy calculations for a wide temperature range. A new method for calculation of the additive constants over a wide temperature range using polynomials is proposed. This method allows the calculation of chemical exergies of gaseous and liquid alkanes from 200 to 1500 K and 150 to 370 K, respectively.