Abstract

Entropy production during hydrogen-air diffusion in the combustion chamber (СС) was studied. A two-dimensional axisymmetric combustion chamber is considered in this paper. The numerical simulation of combustion has been done by Fluent software. The entropy production per unit volume for heat conduction and convection, mass diffusion, viscous dissipation, and the chemical reaction was calculated by user-defined function (UDF) post-processing, while the entropy production for heat transfer radiation was determined by post-processing with the help of calculated data of temperature. The results reveal that the radiation entropy production cannot be omitted when second law analysis of thermodynamic is adopted in high-temperature conditions such as boilers, heat exchangers, furnaces, etc; in these devices, thermal radiation is the basic mode of heat transfer. The effects of parameters such as Boltzmann number and Reynolds number on entropy production and entropy production number are analyzed. It is shown that the total entropy production number first decreases with the increase Reynolds and Boltzmann numbers; and then gradually increases. The results provide a theoretical reference for the improvement of thermodynamic efficiency for heat transfer and energy utilization.

中文翻译：

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氢空气燃烧器燃烧过程中熵产生的数值分析

摘要

研究了氢-空气在燃烧室中扩散过程中的熵产生（СС）。本文考虑了二维轴对称燃烧室。燃烧的数值模拟已通过Fluent软件完成。通过用户定义函数（UDF）后处理计算出每单位体积的热传导和对流，质量扩散，粘性耗散以及化学反应的熵产生，而传热辐射的熵产生则通过后处理来确定借助温度的计算数据。结果表明，在高温条件下，如锅炉，热交​​换器，熔炉等，采用热力学第二定律分析时，不能忽略辐射熵的产生。在这些设备中 热辐射是热传递的基本方式。分析了玻尔兹曼数和雷诺数等参数对熵产生和熵产生数的影响。结果表明，总的熵产生数首先随着雷诺数和玻尔兹曼数的增加而减小；然后随着熵的增加而减小。然后逐渐增加。研究结果为提高热力传递和能量利用效率提供了理论参考。