Investigation Over the Recirculation Influence on the Combustion of Micro Organic Dust Particles
-
摘要: 研究了热量再循环和不同式Lewis数,对有机尘埃微粒燃烧的作用.在微型燃烧室中,由于热量再循环的影响更加显而易见,所以建立更好的模拟微型燃烧室性能的计算模型显得十分必要.为了模拟有机尘埃微粒的燃烧,假定尘埃微粒首先被气化,氧化成为一种化学结构已知的气相,接着假定该可燃气体的化学结构为甲烷.为了研究火焰的结构和求解控制方程,认为火焰结构由3个区域组成,即预热气化区、反应区和后火焰区.通过从后火焰区到预热区的排热来评价再循环现象.问题如下分步求解:首先对各区域的控制方程无量纲化;接着对各区域应用必要的边界条件和协调条件;然后按分析模型,对控制方程以及必要的边界条件和协调条件,同时进行求解.表明,再循环和不同式Lewis数,对有机尘埃微粒的燃烧特性有着显著的影响,得到不同微粒半径时的燃烧速度曲线和温度曲线等.结果与已发表的试验数据吻合.Abstract: The role of recirculation and non-unity Lew is number on the combustion of organic dust particles were investigated. Since recirculation effect is more no ticeable in micro-combustors, it is necessary to propose a modeling approach of this phenomenon to better simulate the perform anceofmicro-combustors. In this research, in order to model the combustion of organic dust particles, it was assumed that the dust particles vaporize first to yield a known chemical structure which was oxidized in the gas phase, and the chemical structure of this gaseous fuel was assumed methane. To study the flame structure and solve the governing equations, it was considered that the flame structure consists of three zonestitled the prehea-tvaporization zone, the narrow reaction zone and finally the post flame zone. The recircu lation phenom enon was evaluated by entering the exhausted heat from the post flame zone in to the preheat zone. The solution was based on the following approach. First, the governing equations in each zone were nond imensionalized. Then the needed boundary and matching conditions were applied in each zone. A fter that, these equations and the required boundary and matching conditions were simultaneously solved with the analytical model. Consequently, the remarkable effects of recirculation and nonunity Lew is number on the combustion characteristics of the organic dust particles such as burning velocity and temperature profiles for different particle radiiare obtained. The results show reasonable agreement with published experimental data.
-
Key words:
- recirculation /
- non-unity Lew is number /
- organic dust particles /
- flame temperature /
- burning velocity
-
[1] Cashdollar K L. Overview of dust explosibility characteristics [J]. Journal of Loss Prevention in the Process Industries, 2000, 13(3/5): 183-199. doi: 10.1016/S0950-4230(99)00039-X [2] Han O-S, Yashima M, Matsuda T, Matsui H, Miyake A, Ogawa T. Behavior of flame propagating through lycopodium dust clouds in a vertical duct [J]. Journal of Loss Prevention in the Process Industries, 2000, 13(6): 449-457. doi: 10.1016/S0950-4230(99)00072-8 [3] Han O-S, Yashima M, Matsuda T, Matsui H, Miyake A, Ogawa T. A study of flame propagation mechanisms in Lycopodium dust clouds based on dust particles behaviour [J]. Journal of Loss Prevention in the Process Industries, 2001, 14(3): 153-160. doi: 10.1016/S0950-4230(00)00049-8 [4] Kurdyumov V N, Fernandez-Tarrazo E. Lewis number effect on the propagation of premixed laminar flames in narrow open ducts [J]. Combustion and Flame, 2002, 128(4): 382-394. doi: 10.1016/S0010-2180(01)00358-3 [5] Shamim T. The effect of Lewis number on radiative extinction and flamelet modeling[J]. International Journal of Heat and Mass Transfer, 2002, 45(6): 1249-1259. doi: 10.1016/S0017-9310(01)00223-X [6] Proust C. A few fundamental aspects about ignition and flame propagation in dust clouds [J]. Journal of Loss Prevention in the Process Industries, 2006, 19(2/3): 104-120. doi: 10.1016/j.jlp.2005.06.035 [7] Proust C. Flame propagation and combustion in some dust-air mixtures [J]. Journal of Loss Prevention in the Process Industries, 2006, 19(1): 89-100. doi: 10.1016/j.jlp.2005.06.026 [8] Eckhoff R K. Differences and similarities of gas and dust explosions: a critical evaluation of the European ‘ATEX’ directives in relation to dusts [J]. Journal of Loss Prevention in the Process Industries, 2006, 19(6): 553-560. doi: 10.1016/j.jlp.2006.01.001 [9] Babrauskas V. Ignition: a century of research and an assessment of our current status[J]. Journal of Fire Protection Engineering, 2007, 17(3): 165. doi: 10.1177/1042391507059434 [10] Chakraborty S, Mukhopadhyay A, Sen S. Interaction of Lewis number and heat loss effects for a laminar premixed flame propagating in a channel[J]. International Journal of Thermal Sciences, 2008, 47(1): 84-92. doi: 10.1016/j.ijthermalsci.2007.01.025 [11] Chen Z, Burke M P, Ju Y. Effects of Lewis number and ignition energy on the determination of laminar flame speed using propagating spherical flames[J]. Proceedings of the Combustion Institute, 2009, 32(1): 1253-1260. doi: 10.1016/j.proci.2008.05.060 [12] Daou J, Matalon M. Influence of conductive heat losses on the propagation of premixed flames in channels[J]. Combustion and Flame, 2002, 128(4): 321-339. doi: 10.1016/S0010-2180(01)00362-5 [13] Daou J, Matalon M. Flame propagation in channels: differential diffusion effects[C]3rd Joint Meeting of the US Sections of the Combustion Institute.Chicago, Illinois, 2003. [14] Ronney P D. Analysis of non-adiabatic heat-recirculating combustors[J]. Combustion and Flame, 2003, 135(4): 421-439. doi: 10.1016/j.combustflame.2003.07.003 [15] Leach T, Cadou C P, Jackson G. Effect of structural heat conduction and heat loss on combustion in micro-channels[J]. Combustion Theory and Modeling, 2006, 10(1): 85-103. doi: 10.1080/13647830500277332 [16] Leach T T, Cadou C P. The role of structural heat exchange and heat loss in the design of efficient silicon micro-combustors[J]. Proceedings of the Combustion Institute, 2004, 30(2): 2437-2444. [17] Deng W W, Klemic J F, Li X H, Reed M A, Gomez A. Liquid fuel microcombustor using microfabricated multiplexed electrospray sources[J]. Proceedings of the Combustion Institute, 2007, 31(2): 2239-2246. doi: 10.1016/j.proci.2006.08.080 [18] Bidabadi M, Rahbari A. Modeling combustion of lycopodium particles by considering the temperature difference between the gas and the particles[J]. Combustion, Explosion and Shock Waves, 2009, 45(3): 49-57. [19] Bidabadi M, Haghiri A, Rahbari A. The effect of Lewis and Damkohler numbers on the flame propagation through micro organic dust particles [J]. International Journal of Thermal Sciences, 2010, 49(3): 534-542. doi: 10.1016/j.ijthermalsci.2009.10.002
点击查看大图
计量
- 文章访问数: 1326
- HTML全文浏览量: 72
- PDF下载量: 766
- 被引次数: 0