During the time of carrying out cost analysis by using method of thermal economics

resonable structure of supplementary equation is a key factor for obtaining scientfic and correct results of products’ cost. The original supplementary equation consider that both the inlet and outler fuels have same unit price of exergy

regardless the level of their quality. In order to express the economic rule of different quality and different price

a concept of energy quality coefficient has been introduced and used in the structure of newly created supplementary equction

so as to make the cost analysis to be more scientific and resonable.