Energy quality factor of materials conversion and energy quality reference system

This paper aims to explore the standardized data system of the exergy function and energy quality analysis methods. The concepts of the energy grades of the material and process were proposed. These concepts indicate that the availability factor is the thermodynamic property of the process, whereas the energy quality factor is the thermodynamic property of the substance. By evaluating the difference in the energy quality factors between different substances in material conversion processes, the energy-exchange mechanisms and the features of energy grade of processes can be revealed. The reference substance system was created by defining 100 kPa and 298.15 K as the pressure and temperature of environmental reference state and choosing air with an appropriate composition derived from the US Standard Atmosphere 1976 as the reference substance for atmospheric elements, pure water as the reference substance for hydrogen, and the pure compounds in the geosphere as the reference substance for other elements. Thus, a new energy quality reference state system, which involves fundamental models, the reference substances system, and data about the standard exergy and standard enthalpy of 81 elements, was established. In order to show how the new proposals could be used for the real applications, the energy cascade utilizations of the thermodynamic mechanisms of 4 CO2-hydrogenation processes were analyzed to evaluate CO2 resource utilization routes, among which the CO and methanol routes are potential options.