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首页> 外文期刊>International Journal of Heat and Mass Transfer >Finite-rate thermodynamics of power production in thermal, chemical and electrochemical systems
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Finite-rate thermodynamics of power production in thermal, chemical and electrochemical systems

机译：热，化学和电化学系统中发电的有限速热力学

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Power optimization approaches are unified for various energy converters, such like: thermal, solar, chemical, and electrochemical engines. Thermodynamics leads to converter's efficiency and limiting power. Efficiency equations serve to solve problems of upgrading and downgrading of resources. While optimization of steady systems applies the differential calculus and Lagrange multipliers, dynamic optimization involves variational calculus and dynamic programming. In reacting systems chemical affinity constitutes a prevailing component of an overall efficiency, so that power is analyzed in terms of an active part of chemical affinity. The main novelty of the present paper in the energy yield context consists in showing that the generalized heat flux Q( involving the traditional heat flux q plus the product of temperature and the sum products of partial entropies and fluxes of species) plays in complex cases (solar, chemical and electrochemical) the same role as the traditional heat q in pure heat engines.rnThe presented methodology is also applied to power limits in fuel cells as to systems which are electrochemical flow engines propelled by chemical reactions. The performance of fuel cells is determined by magnitudes and directions of participating streams and mechanism of electric current generation. Voltage lowering below the so-called idle run voltage is a proper measure of cells imperfection. The voltage losses, called polarization, include three main sources: activation, ohmic and concentration polarization. Examples show power maxima in fuel cells and prove the suitability of the thermal machine theory to chemical and electrochemical systems. The main novelty of the present paper in the FC context consists in introducing the effective or reduced Gibbs free energy change between products p and reactants s which take into account the decrease of voltage and power decrease caused by the incomplete conversion of the overall electrochemical reaction.
机译：功率优化方法适用于各种能量转换器，例如：热，太阳能，化学和电化学引擎。热力学导致转换器的效率和限制功率。效率方程用于解决资源升级和降级的问题。稳态系统的优化应用微积分和拉格朗日乘数，而动态优化则涉及变分微积分和动态规划。在反应体系中，化学亲和力是总体效率的主要组成部分，因此，根据化学亲和力的有效部分来分析功率。本文在能量产出方面的主要新颖之处在于，它在复杂情况下发挥了广义热通量Q（涉及传统热通量q加上温度乘积与部分熵和物种通量之和的乘积）的作用（太阳能，化学和电化学方面的作用与纯热机中的传统热量q相同。所提出的方法还适用于燃料电池的功率极限以及由化学反应推动的电化学流发动机的系统。燃料电池的性能取决于参与流的大小和方向以及电流产生的机理。降低到所谓的空转电压以下的电压是电池缺陷的适当度量。称为极化的电压损耗包括三个主要来源：激活，欧姆和浓度极化。实例显示了燃料电池的最大功率，并证明了热机械理论对化学和电化学系统的适用性。本文在燃料电池方面的主要新颖之处在于引入了产物p和反应物s之间有效或减少的吉布斯自由能变化，其中考虑了由于整体电化学反应的不完全转化而导致的电压降低和功率降低。

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