A numerical study of propane-air combustion in meso-scale tube combustors with concentric rings
A numerical study of propane-air combustion in meso-scale tube combustors with concentric rings
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DOI：
10.1299/jtst.2015jtst0008
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发表时间：
2015
影响因子：
1.2
通讯作者：
F. Munir;M. Mikami
中科院分区：
文献类型：
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作者：
F. Munir;M. Mikami
与传统电池相比，能源资源的减少和对更好能源的强烈需求引发了对微型发电的研究兴趣。最先进的电子设备的发明需要更大的能量容量、更短的充电周期和更轻的重量，这些都是电池所缺乏的特性。因此，近年来，微型发电系统因其明显的优势而被视为电池的潜在替代品。充分认识影响中、微尺度燃烧室燃烧稳定性的潜在因素至关重要。检验这些因素的常用方法之一是进行数值模拟。本文用轴对称二维稳态数值模拟了丙烷-空气在中尺度同心环圆柱管燃烧室中的燃烧过程。管的内径设置为3.5 mm，壁厚指定为0.7 mm。同心环被放置在未燃烧和燃烧的气体区域之间。这些环的主要功能是作为一个火焰支架，一个稳定的火焰可以很容易地建立。未燃区和燃气区壁面导热系数从1 W/m/K到1000 W/m/K不等，并从燃气、内壁、外壁表面温度分布、井喷极限和燃烧效率等方面进行了分析和介绍。此外，还研究了进口速度和等效比的影响。结果表明，入口速度和等效比对火焰温度有显著影响，进而改变壁面温度分布。虽然壁面导热系数对火焰温度的影响很小，但内外壁面温度都受到很大的影响。因此，这种壁面温度的变化导致了井喷极限的显著变化。燃烧效率受燃烧室壁面导热系数的影响。
Dwindling energy resources and strong demand for better power sources as compared to conventional batteries have sparked research interest in micro power generation. The invention of state-of-the-art electronic devices requires more energy capacity, shorter charging period and light in weight, characteristics of which batteries lack. Therefore, in recent years micro power generation systems have been seen as a potential alternative to batteries owing to the obvious advantages that it has. It is essential to fully understand the underlying factors that affect the combustion stability in meso and micro-scale combustors. One of the popular methods to examine these factors is by performing numerical simulations. This paper demonstrates an axisymmetric two-dimensional steady state numerical simulation of propane-air combustion in meso-scale cylindrical tube combustors with concentric rings. The inner diameter of the tube is set to 3.5 mm and the wall thickness is specified to 0.7 mm. The concentric rings are placed between the unburned and burned gas region. The main function of these rings is to act as a flame holder where a stable flame can be easily established. The wall thermal conductivity in the unburned and burned gas region is varied from 1 W/m/K to 1000 W/m/K and the results in terms of gas, inner wall, outer wall surface temperature distribution, the blowout limits and combustion efficiency are analyzed and presented. In addition, the effect of the inlet velocity and the equivalence ratio is also investigated. The results show that the inlet velocity and equivalence ratio have significant impacts on the flame temperature, which in turn change the wall temperature distribution. Although the wall thermal conductivity has minimal effect on the flame temperature, both inner and outer wall surface temperature are greatly affected. Consequently, this variation of wall temperature contributes to the significant changes on the blowout limits. It is also shown that the combustion efficiency is influenced by the wall thermal conductivity of the combustors.