Introduction and Fundamentals

Abstract

This chapter is introduced by a discussion of the relevance of environmental effects caused by humans and the concept of sustainability. These effects on a global scale are a major challenge for human societies. The second part of this chapter deals with the definition of systems, their balances, and their properties with special emphasis on dynamic and feedback situations. The third part describes how systems respond energetically to processes in them and changes of their surroundings. Classical thermodynamics distinguishes between different kinds of energies that can be interconverted without altering the sum of all energies. As different kinds of energy do not have the same quality and low-level energy cannot be completely transformed to higher levels, second-law analyses using the concepts of entropy and exergy are required. Non-equilibrium thermodynamics is devoted to real systems far away from equilibrium, where fluctuations and instability are of great importance. Entropy and irreversibility that destroy order near equilibrium can create order in systems far from equilibrium.