CHEMICAL EXERGY OF FUELS AND EFFICIENCY ANALYSIS OF ENERGY UTILIZATIONS

摘要

Many studies have investigated the chemical exergy of fuels. The results showed that it is equal to the negative standard free enthalpy change (SFEC) of the fuel combustion or the correction value. However, because the products of the combustion still have the chemical potentials of diffusion, the negative SFEC is not the whole of the chemical exergy of fuels. Because the accurate entropy of fuels cannot be obtained, the accuracy of the SFEC is doubtful and some corrections become necessary. But any correction risks misrepresenting the exergy balance of fuel-fired energy systems. In this paper, some important thermodynamic fundamental problems were studied, which showed that the chemical exergy of fuels should be equal to the negative standard enthalpy change. The formulas of total entropy generations and exergy efficiencies of energy utilizations were deduced, so that the exergy efficiency evaluation just needs heat balance data. The case studies were also given.