In this paper we revisit the classic thermocouple model, as a Linear Irreversible Thermodynamic (LIT) energy converter. In this model we have two types of phenomenological coefficients: the first comes from some microscopic models, such as the coefficient associated with the electric conductivity, and the second comes from experimental facts, such as the coefficient associated with the Seebeck power. We show that in the last case, these coefficients can be related to the thermodynamic operation modes of the energy converter. These relations between the experimental phenomenological coefficients and the regimes of performance allow us to propose a first and a second Thomson-type relation, which give us 12 new relations between the Seebeck power, the Peltier heat and the Thomson heat. With this purpose we develop the idea of non-isothermal linear energy converters operated either “directly” (like a heat engine) or “inversely” (like a refrigerator). We analyze the energetics associated to these converters operating under steady states corresponding to different modes of performance, all of them satisfying the fundamental Onsager symmetry relations.
In this paper, a semiclassical approach is used to describe a kind of black-body which we will call a matte black-body. Although the frequency energy density of a black-body is deduced using a semiclassical method which includes the electromagnetic reaction force and the quantization of the energy, a phenomenological damping force, as in the explanation of the anomalous dispersion of some fluids, is considered in order to obtain the corresponding frequency energy density of the matte black-body. The concept of emissivity is incorporated into the new body in order to explain the experimental data of the radiation measured in the Earth's atmosphere. The purpose of this article consists of showing students the applicability of semiclassical approaches in obtaining physical results.
In this paper, a proposal is presented to determine the temperature profile obtained for an assemblage of non-isothermal linear energy converters (ANLEC) published by Jiménez de Cisneros and Calvo Hernández [1,2]. This is done without solving the Riccati's differential equation, needed by these authors to get the temperature profile. Instead of use Riccati's equation, we deduce a first order ordinary differential equation, through the introduction of the force ratio xD,I of an ANLEC's machine-element which operates at some optimal regime. Additionally, we used the integration constant, that comes from the solution of this differential equation, to deduce the general heat fluxes of the ANLEC and tuning the assamblage's operation as direct energy converter or inverse energy converter. The temperature profile will serve to obtain the energetic behavior of a nonisothermal energy converter as heat engine, cooler or heat pump. 05.20.-y Classical statistical mechanics; 05.70-Ln Nonequilibrium and irreversible thermodynamics; 84.60.Bk Performance characteristics of energy conversion system; figure of merit.
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