A study of the local entropy generation rate in a porous media burner

IF 1.1 4区工程技术 Q3 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Archives of Mechanics Pub Date : 2020-06-30 DOI:10.24423/AOM.3416

I. Mohammadi, J. A. Esfahani, K. C. Kim

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引用次数: 0

Abstract

In this paper, the work and performance of the premixed methane-air porous axisymmetrical burner have firstly been simulated numerically using the CFD tools. For this purpose the set of governing equations has been enriched by an additional energy equation in porous solid, and the chemical species transport has been extended onto the multi-step mechanism (GRI-2-11). This numerical model has been verified on the base of available benchmark experiments. Next, we have studied the local entropy generation problem taking into account not only classical contributions like viscous and turbulent dissipation but also, the porous combustion of gases. The results showed that the greatest portion of entropy generation in the porous medium burner is related to chemical reactions, followed by heat transfer, mass diffusion (mixing) and friction (viscous dissipation), respectively. According to the results, as the excess air ratio increases, the local entropy generation rate due to heat transfer and friction increases and the local entropy generation rate due to chemical reactions is decreased. Also, by increasing the volumetric heat transfer coefficient, the local entropy generation rate due to heat transfer decreases and the local entropy generation rate due to friction and chemical reactions increases. Also, the local entropy generation rate due to mixing does not show a significant change with the changing excess air ratio and volumetric heat transfer coefficient.

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多孔介质燃烧器局部熵产率的研究

本文首次利用CFD工具对甲烷-空气预混多孔轴对称燃烧器的工作和性能进行了数值模拟。为此，通过在多孔固体中增加一个能量方程，丰富了控制方程集，并将化学物质输运扩展到多步机制(GRI-2-11)。该数值模型在已有基准试验的基础上得到了验证。其次，我们研究了局部熵生成问题，不仅考虑了粘性和湍流耗散等经典贡献，而且考虑了气体的多孔燃烧。结果表明:多孔介质燃烧器的熵产最大部分与化学反应有关，其次是传热、质量扩散(混合)和摩擦(粘性耗散)。结果表明，随着过量空气比的增大，传热和摩擦引起的局部熵产率增大，化学反应引起的局部熵产率减小。此外，通过增加体积换热系数，传热引起的局部熵产率降低，摩擦和化学反应引起的局部熵产率增加。混合引起的局部熵产率不随过量空气比和体积换热系数的变化而发生显著变化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Archives of Mechanics 工程技术-材料科学：表征与测试

CiteScore

1.40

自引率

12.50%

发文量

审稿时长

>12 weeks

期刊介绍： Archives of Mechanics provides a forum for original research on mechanics of solids, fluids and discrete systems, including the development of mathematical methods for solving mechanical problems. The journal encompasses all aspects of the field, with the emphasis placed on: -mechanics of materials: elasticity, plasticity, time-dependent phenomena, phase transformation, damage, fracture; physical and experimental foundations, micromechanics, thermodynamics, instabilities; -methods and problems in continuum mechanics: general theory and novel applications, thermomechanics, structural analysis, porous media, contact problems; -dynamics of material systems; -fluid flows and interactions with solids. Papers published in the Archives should contain original contributions dealing with theoretical, experimental, or numerical aspects of mechanical problems listed above. The journal publishes also current announcements and information about important scientific events of possible interest to its readers, like conferences, congresses, symposia, work-shops, courses, etc. Occasionally, special issues of the journal may be devoted to publication of all or selected papers presented at international conferences or other scientific meetings. However, all papers intended for such an issue are subjected to the usual reviewing and acceptance procedure.