Šesták’s proposal of term “tempericity” for non-equilibrium temperature and modified Tykodi’s thermal science classification with regard to methods of thermal analysis

Abstract

The equilibrium (thermodynamic) temperature of a body is defined by zeroth law of thermodynamics as a quantity obtained by thermometer as a result of thermal equilibrium between the body and the thermometer. However, the term temperature is also used for description of any instantaneous thermal state during processes where no thermal equilibrium is reached. The proposal of Tykodi to divide thermal science into three branches has been modified to express the dependence of temperature on time and position inside a system. The three branches have been called thermostatics (equilibrium thermodynamics), thermostatics (thermodynamics of steady = stationary states) and thermokinetics (thermal science dealing with unsteady—non-stationary states). Equilibrium temperature is used only at thermostatics. For other branches of thermal science where the Newton cooling law and/or any of both Fourier laws are applied, no equilibrium temperature with respect to zeroth law is expected. Thermal analysis studying unsteady states (temperature is a function of time t as well as of space coordinates x) should be subject of thermokinetics, and the appropriate kinetic models should include the local temperature changes evoked by self-cooling or self-heating due to process running inside sample.