This work explores the concept of dissipative work and shows that such a kind of work is an invariant non-negative quantity. This feature is then used to get a new insight into adiabatic irreversible processes; for instance, why the final temperature in any adiabatic irreversible process is always higher than that attained in a reversible process having the same initial state and equal final pressure or volume. Based on the concept of identical processes, numerical simulations of adiabatic irreversible compression and expansion were performed, enabling a better understanding of differences between configuration and dissipative work. The positive nature of the dissipative work was used to discuss the case where the dissipated energy ends up in the surroundings, while the invariance of such work under a system–surroundings interchange enabled the resulting modification in thermodynamical quantities to be determined. The ideas presented in this study are primarily intended for undergraduate students with a background in thermodynamics, but they may also be of interest to graduate students and teachers.

This paper deals with subtleties and misunderstandings regarding the Clausius relation. We start by demonstrating the relation in a new and simple way, explaining clearly the assumptions made and the extent of its validity. Then follows a detailed discussion of some confusions and mistakes often found in the literature. The addressed points include the issue of temperature in the Clausius relation and closely related concepts, such as heat, reversibility and reservoir. The ideas presented in this study are primarily intended for graduate students and teachers, and may also be of interest to undergraduate students with a solid background in thermodynamics.

Starting from the concept of identical thermodynamical processes, we treat invariance under interchange of identical processes as a symmetry. We show the conservation of entropy in reversible processes to be intimately related to this symmetry. PACS Nos.: 44.60, 65.50

We stress the usefulness of the work reservoir in the formalism of thermodynamics, in particular in the context of the first law. To elucidate its usefulness, the formalism is then applied to the Joule expansion and other peculiar and instructive experimental situations, clarifying the concepts of configuration and dissipative work. The ideas and discussions presented in this study are primarily intended for undergraduate students, but they might also be useful to graduate students, researchers and teachers.