Remarks on thermodynamical terminology

Abstract

Registration Number 025 Often di‰culties in understanding thermodynamics arise from using di¤erent terminology or semantics. Therefore here some few remarks are made for tending towards a unified thermodynamical terminology. First of all one has to distinguish between two di¤erent description of thermodynamical systems: Such a system can be described as a discrete (or lumped) system or by field formulation. Discrete systems are separated from its environment by partitions. The interaction between the discrete system and its environment can be described by exchanges, namely by heat exchange, by power exchange and by material exchange (Schottky system) [1]. The discrete system itself is characterized by in general time-dependent quantities, the basic variables, belonging to the whole system [2]. This is of course a reduced model of a thermodynamical system. For a more detailed depiction of the system, it has to be described as a composite (or compound) system or by field formulation. The exchanges between the system and the environment depend on both their basic variables. Because naturally no gradients appear in the description of discrete systems, this concept is used in thermostatics. But also complex machines in engineering sciences are described by discrete systems, if mainly exchange quantities are of interest. Thus, for a reduced description of complex situations, the concept of a discrete system is a very useful one.

Second Law and Non-Equilibrium Entropy of Schottky Systems --Doubts and Verification--

“…Meixner's historical remark [23] "... it can be shown that the concept of entropy in the absence of equilibrium is in fact not only questionable but that it cannot even be defined" was the starting-point of a deliberation, if there is a possibility to introduce non-equilibrium entropies which are better founded than a primitive concept. Here, steps are done for a basic substantiation of non-equilibrium entropies for Schottky systems (concerning field formulation see [41,42]). The chain of reasoning is as follows:…”

“…vanishing material exchange (41) The quantities 2 ,0 marked by or zero are given thermostatic quantities of several equilibrium environments. The resulting contact quantities of (38) are determined by the following equations: (31) 1,2 and (37).…”

Entropy Production and Equilibrium Conditions of General-Covariant Spin Systems

“…The entropy identity results by multiplying Equations (5) 1 , (14) and (16) with the present arbitrary quantities κ, λ and Λ c , which are suitably chosen below; Equation (10) 1 becomes:…”

“…The basic ideas of relativistic material theory stem partly from the non-relativistic theory, from the special-relativistic TIP (thermodynamics of irreversible processes) and from general relativity [13][14][15][16][17][18].…”

Why so many “schools” of thermodynamics?

“…Its methods can be successfully applied in various different disciplines such as Physics and Physical Chemistry, Mechanical and Chemical Engineering, Heat and Steam Engine Engineering, Material Science, Bio-Sciences, Energy Conversion Techniques, Air Conditioning and Refrigeration. Consequently, it is impossible to mention the different terminologies [6], methods and schools completely in this brief survey.…”