The Thermodynamic Background of Exergy Transfer

In academic circles, there are some controversial issues at present, such as difference and relation between exergy analysis and exergy transfer, discipline belongingness of exergy transfer and so on. Taking theoretical research in depth on exergy transfer into consideration, it is necessary to clarify these problems. This paper starts with illustrating the scientific definition of energy, and then discusses double property of quantity and quality of energy. The first and second laws of thermodynamics reveal the change law of quantity and quality of energy in energy conversion and transfer process, namely energy quantity conservation and energy quality transmutation, while enthalpy, entropy and exergy are thermodynamic parameters used to describe these laws. Thermodynamics theory is applied to further demonstrate that exergy is a parameter to characterize energy quality. In a word, exergy transfer and energy transfer constitute the complete system of energy research.