This paper presents a general property of endoreversible thermal engines known as the Semisum property previously studied in a finite-time thermodynamics context for a Curzon–Ahlborn (CA) engine but now extended to a simplified version of the CA engine studied by Agrawal in 2009 (A simplified version of the Curzon–Ahlborn engine, European Journal of Physics 30 (2009), 1173). By building the Ecological function, proposed by Angulo-Brown (An ecological optimization criterion for finite-time heat engines, Journal of Applied Physics 69 (1991), 7465–7469) in 1991, and considering two heat transfer laws an analytical expression is obtained for efficiency and power output which depends only on the heat reservoirs’ temperature. When comparing the existing efficiency values of real power plants and the theoretical efficiencies obtained in this work, it is observed that the Semisum property is satisfied. Moreover, for the Newton and the Dulong–Petit heat transfer laws the existence of the g function is demonstrated and we confirm that in a Carnot-type thermal engine there is a general property independent of the heat transfer law used between the thermal reservoirs and the working substance.

A non-endoreversible Curzon and Ahlborn cycle is analyzed by introducing afactor of non-endoreversibility. The form of power output and ecological function, andthe role of this factor is discussed. The Gutkowics-Krusin, Procaccia and Ross method tobuild a general expression for both the power output and the ecological function for thiscycle is used. A numerical analysis of these expresions is made and the results arecompared with other kind of approaches found in the literature of finite timethermodynamics.

Using a van der Waals gas as the working substance the so called Curzon and Ahlborn-Novikov engine is studied. It is shown that some previous results found in the literature of finite time thermodynamics can be written in a more general form, means of this gas and by taking a non linear heat transfer law.

In this paper, the methodology of the so-called Linear Irreversible Thermodynamics (LIT) is applied to analyze the properties of an energetic-converting biological process using simple model for an enzymatic reaction that couples one exothermic and one endothermic reaction in the same fashion as Diaz-Hernandez et al. (Physica A, 2010, 389, 3476–3483). We extend the former analysis to consider three different operating regimes; namely, Maximum Power Output (MPO), Maximum Ecological Function (MEF) and Maximum Efficient Power Function (MEPF), respectively. Based on the later, it is possible to generalize the obtained results. Additionally, results show analogies in the optimal performance between the different optimization criteria where all thermodynamic features are determined by three parameters (the chemical potential gap $\Delta =\frac{{\mu }_1-{\mu }_4}{RT}$ , the degree of coupling q and the efficiency $\eta$ ). This depends on the election that leads to more or less efficient energy exchange.

En este trabajo se discuten las principales ideas de la Educación en Valores, y la manera como aparece implícitamente cuando se enseña como se proponen y prueban las teorías sobre el comportamiento de la naturaleza. Primero se exponen los principios y objetivos de la Educación en Valores. Luego se muestran los principios básicos del Método Científico. Finalmente se observa cómo al poner en práctica el Método Científico, se aplican implícitamente los principios de la Educación en Valores. Para hacer explícita esta idea se utilizan diagramas de flujo, mostrando la influencia de las decisiones tomadas a partir de una hipótesis (Método Científico), y su relación con los principios básicos de la Educación en Valores. Así, se busca una posible relación biunívoca entre la Teoría de la Educación en Valores y el Método Científico, que permita utilizar este método para fortalecer la apropiación de valores en los estudiantes.

This paper presents a finite-time thermodynamic optimization based on three different optimization criteria: Maximum Power Output (MP), Maximum Efficient Power (MEP), and Maximum Power Density (MPD), for a simplified Curzon-Ahlborn engine that was first proposed by Agrawal. The results obtained for the MP are compared with those obtained using MEP and MPD criteria. The results show that when a Newton heat transfer law is used, the efficiency values of the engine working in the MP regime are lower than the efficiency values ( $\tau$ ) obtained with the MEP and MPD regimes for all values of the parameter $\tau =T_2/T_1$ , where $T_1$ and $T_2$ are the hot and cold temperatures of the engine reservoirs $\left(T_2<T_1\right)$ , respectively. However, when a Dulong-Petit heat transfer law is used, the efficiency values of the engine working at MEP are larger than those obtained with the MP and the MPD regimes for all values of $\tau$ . Notably, when $0<\tau <0.68$ , the efficiency values for the MP regime are larger than those obtained with the MPD regime. Also, when $0.68<\tau <1$ , the efficiency values for the aforementioned regimes are similar. Importantly, the parameter $\tau$ plays a crucial role in the engine performance, providing guidance during the design of real power plants.