Entropic and exergy analysis of energy systems using geometric representations.

Summary At a time when people are becoming aware of the finitude of resources and the growing need for energy, the notion of sustainable development must take a central place in the evolution of society. To achieve this goal, it is now recognized that a profound change in consumption is necessary, whether it is energy consumption, food or finished products. We believe that this change of paradigm is only possible if all the actors move forward together on the different issues we are facing. Each one at its own level must be able to make the decisions that are necessary for all. This is the logic behind the exergo-graphy tool presented in chapter 3. In the tradition of Sankey diagrams, it allows exergy balances to be represented in graphic form in order to communicate the lessons more easily. We apply it to two cases of analyses carried out on the heating and DHW production installations of building A of the UPN. For each, we study the possibility of a sustainable heat production solution (geothermal heat pump and solar thermal). After having presented the analyses, we draw up the graphical representations which we compare with those of the current system. Beforehand, Chapter 1 introduces the basic concepts of exergy analysis, which are further developed in Chapter 2, through a modeling of static and dynamic fluid systems. Finally, in chapter 4, we introduce a toy model which, proposing a fractal representation of heat, tries to establish a conceptual link between the microscopic, statistical behavior of the heat carrier, and the macroscopic observables which characterize it.