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Local Stability Analysis of a Curzon-Ahlborn Engine without Ideal Gas Working at the Maximum Ecological Regime

Journal of Energy and Power Engineering 2013年第5期7卷 928-936页

作者： Ricardo Paiez Hernandez delfino ladino luna Pedro Portillo Diaz Marco A Barranco Jimenez Irreversible Processes Physics Research Group Basic Sciences Department Metropolitan Autonomous University CampusAzcapotzalco Distrito Federal 02200 Mdxico Basic Sciences Department Metropolitan Autonomous University Campus Azcapotzalco Distrito Federal 02200 M~xico Information Technology School of the National Polytechnic Institute Distrito Federal 07738 Mexico

In this work, the stability of an endoreversible Curzon-Ahlbom engine is analyzed, using Van der Waals gas as a working substance and the corresponding efficiency for this engine working at temperatures withinthe maximum ecological regime. By mean s of a local stability analysis we find that a critical point of an almost linear system is stable andanalytically expressed in eigenvalues. After an arbitrarily small perturbation, the system state exponentially decays to a critical point, with either of two characteristic relaxation times, which are a function of the thermal conductance （a）, heat capacity （C） and T=T2/T1. The behavior of relaxation times and solution of the systems are qualitatively shown by sketching its phase portrait, which results susceptible to operating regimes, i.e., the eigenvectors in the maximum ecological regime have a clockwise rotation with respect to the eigenvectors in the regime of maximumpower. Finally, it has to observe that afterto λvw = 1, approximation,ηVWE=4^-3ηC is obtained, where ηVWE is the Van der Waals efficiency atrnaximum ecological regime and r/c is Carnot＇s efficiency. Finally, it discussed the local stability and steady state of the energetic properties of the endoreversible engine.

关键词： Ecological regime dynamics Van der Waals equation stability steady state.

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Local Stability of Curzon-Ahlborn Cycle with Non-Linear Heat Transfer for Maximum Power Output Regime

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Journal of Modern Physics 2013年第7期4卷 22-27页

作者： delfino ladino-luna Pedro Portillo-Díaz Ricardo T. Páez-Hernández Universidad Autónoma Metropolitana-Atzcapotzalco Física de Procesos Irreversibles Cd. México México

The study of local stability of thermal engines modeled as an endoreversible Curzon and Ahlborn cycle is shown. It is assumed a non-linear heat transfer for heat fluxes in the system (engine + environments). A semisum of two expressions of the efficiency found in the literature of finite time thermodynamics for the maximum power output regime is considered in order to make the analysis. Expression of variables for local stability and power output is found even graphic results for important parameters in the analysis of stability, and a phase plane portrait is shown.

关键词： Local Stability Thermal Engines Non-Linear Heat Transfer

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On the Efficiency for Non-Endoreversible Stirling and Ericsson Cycles

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Journal of Modern Physics 2013年第12期4卷 1-7页

作者： delfino ladino-luna Pedro Portillo-Díaz Ricardo T. Páez-Hernández Universidad Autónoma Metropolitana-Azcapotzalco Física de Procesos Irreversibles México D.F. México

An analysis of the Stirling and Ericsson cycles from the point of view of the finite time thermodynamics is made by assuming the existence of internal irreversibilities in an engine modeled by these cycles, and the ideal gas as working substance is considered. Expressions of efficiency in both regimes maximum power output and maximum ecological function are also shown. Appropriate variables are introduced so that the objective functions, namely power output, ecological function and efficiency can be functions of the reservoirs temperatures ratio and certain “measurable” parameters as a thermal conductance, the general constant of gases and the compression ratio of the cycle. Several results from the finite time thermodynamics literature are used, so that the developed methodology leads directly to appropriate expressions of the objective functions in order to simplify the optimization process.

关键词： Thermal Cycles Efficiency Power Output Ecological Function

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Effects of Time Delays in a Dynamical Heart Model

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Journal of Chemistry and Chemical Engineering 2014年第3期8卷 320-323页

作者： Ricardo Paez-Hernfindez Maribel Zamora-Gomez Pedro Portillo-Diaz delfino ladino-luna Ruben Luevano-Enriquez Basic Sciences Department Metropolitan Autonomous University Campus Azcapotzalco Federal District 02200 M~xico Hospital General "Dr Gaudencio Gonzlez Garza" La Raza IMSS Federal District 02290 Mdxico

In this work, a dynamical model of the heartbeat is studied using nonlinear dynamics and considering the time delays inherent in the system. Two fixed points are associated to sustained oscillations which might be interpreted as the diastole and systole These parameters are associated with blood flow in human body called arterial pressure and are very important in the cardio-vascular diagnostic.

关键词：动力学模型心脏时滞非线性动力学时间延迟动脉血压持续振荡固定点

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