The world of small systems challenges standard knowledge. Can we use classical thermodynamics? The answer to that is no. The book discusses how Terrill Hill developed the field of nanothermodynamics, which applies perfectly well also to small systems, to address this problem. He introduced an ensemble of replicas of the small system and showed that the energy needed to add such a replica plays a crucial element in the description of the small system contribution.

The purpose of this book is to expand on and demonstrate Hill’s theory. His theory adds new terms to the thermodynamic equations, that are specific for system at the nanoscale. The new properties of these equations may be counter intuitive. The equation of state for a small system, for instance, is not given once and for all. It changes with the environmental variables and the shape that control the small system.

Within nanothermodynamics we can deal with single molecules, unlike in classical thermodynamics. Equilibrium conditions will change upon confinement. These features make nanothermodynamics very different from classical thermodynamics and relevant for the description of fluid transport in nanoporous media. Nanothermodynamics affects porous media on the micrometer scale. As soon as the system’s surface energy is sizable compared to the bulk energy, we need to consider small system effects. Scaling laws are presented which help to describe the small system over a range of sizes and to understand the large system limit better.