Effect of oxygen concentration on homogeneous/heterogeneous coupled reaction characteristics of methane in microchannel

doi:10.11949/0438-1157.20221301

Abstract

Abstract:

Based on the detailed homogeneous and heterogeneous reaction mechanisms of methane, the catalytic combustion process of methane in a planar microchannel was simulated, and the effect of inlet oxygen concentration on the coupled reaction characteristics and its regulation mechanism were analyzed. The results show that the increase of oxygen concentration causes the exothermic position of the homogeneous and heterogeneous reactions of methane to move to the inlet side, shortening the homogeneous ignition distance and broadening the stable combustion range. At a fixed methane concentration at the inlet, increasing O₂ concentration lowers the equivalence ratio of mixture and changes the competition mechanism between homogeneous and heterogeneous reactions for reactant O₂; the combined effect of O₂ concentration and equivalence ratio changes the adsorption and desorption behavior of gas radicals. The increase of O₂ concentration promotes the homogeneous reaction consumption of CH₄ and H radicals and also inhibits the heterogeneous reaction rate of CH₄ and H on the catalytic surface. With the increase of O₂ concentration, the rates of O₂, and intermediate gas phase products CO and H₂ participating in the heterogeneous reaction first increase and then decrease.

Key words: microscale combustion, methane, catalysis, microchannels, oxygen concentration, reaction kinetics

摘要：

基于详细的甲烷均相与非均相反应机理，对平板微通道内甲烷催化燃烧反应过程模拟，探究入口氧浓度变化对耦合反应特性的影响与调控机制。结果表明，氧浓度升高导致甲烷均相与非均相反应放热位置向入口侧移动，缩短均相着火距离，拓宽稳燃范围。固定入口甲烷浓度，氧浓度升高导致化学当量比降低，同时也改变了均相/非均相反应对反应物O₂的竞争机制；氧浓度与化学当量比共同作用改变了气相自由基的吸附与脱附行为。增加O₂浓度促进CH₄和H自由基的均相反应消耗同时抑制CH₄和H的非均相反应速率。随着O₂浓度的升高，O₂以及中间产物CO和H₂参与非均相反应速率先升高后降低。

关键词: 微尺度燃烧, 甲烷, 催化, 微通道, 氧气浓度, 反应动力学

CLC Number:

TK 16

Xiao YANG, Rui DING, Mohan LI, Zhengchang SONG. Effect of oxygen concentration on homogeneous/heterogeneous coupled reaction characteristics of methane in microchannel[J]. CIESC Journal, 2022, 73(12): 5427-5437.

杨霄, 丁锐, 李墨含, 宋正昶. 氧浓度对微通道内甲烷均相/非均相耦合反应特性的影响[J]. 化工学报, 2022, 73(12): 5427-5437.

Figures/Tables 13

Fig.1 Schematic diagram of the planar catalytic microchannel structure

Fig.2 Schematic diagram of homogeneous/heterogeneous coupled reaction pathway for methane catalytic combustion over Pt

Table 1 Inlet flow conditions

工况	氧化剂		入口甲烷燃料体积分数/%	化学当量比
工况	O₂/%	N₂/%	入口甲烷燃料体积分数/%	化学当量比
1	19	81	9.5023	1.105
2	20	80	9.5023	1.050
3	21	79	9.5023	1.000
4	22	78	9.5023	0.955
5	23	77	9.5023	0.913

Fig.3 Normalized OH molar concentration distribution

Fig.4 Distribution of temperature and OH concentration along the centerline

Fig.5 Distribution of heat release rate of heterogeneous reaction on the catalytic surface and homogeneous reaction along the centerline

Fig.6 Distribution of inner wall temperature and gas temperature near inner wall （y=1.195 mm）

Fig.7 Distribution of flame location

Fig.8 Profiles of reaction rate of radical depletion by heterogeneous reaction in the catalytic surface

Fig.9 Profiles of some radical concentration along the centerline and near catalytic surface

Fig.10 Profiles of surface coverage at the inner wall

Fig.11 Average reaction rate of gas radical on the catalytic surface

Fig.12 Heat release contribution from some elementary reactions in homogeneous reaction

References 33

1	Kaisare N S, Vlachos D G. A review on microcombustion: fundamentals, devices and applications[J]. Progress in Energy and Combustion Science, 2012, 38(3): 321-359.
2	Qian P, Liu M H. Influencing factors of wall temperature and flame stability of micro-combustors in micro-thermophotovoltaic and micro-thermoelectric systems[J]. Fuel, 2022, 310: 122436.
3	E J Q, Ding J J, Chen J W, et al. Process in micro-combustion and energy conversion of micro power system: a review[J]. Energy Conversion and Management, 2021, 246: 114664.
4	Chen N G, Gan Y H, Luo Y L, et al. A review on the technology development and fundamental research of electrospray combustion of liquid fuel at small-scale[J]. Fuel Processing Technology, 2022, 234: 107342.
5	Fan Y, Guo J Q, Lee M, et al. Quantitative evaluation of wall chemical effect in hydrogen flame using two-photon absorption LIF[J]. Proceedings of the Combustion Institute, 2021, 38(2): 2361-2370.
6	Maruta K, Kataoka T, Kim N I, et al. Characteristics of combustion in a narrow channel with a temperature gradient[J]. Proceedings of the Combustion Institute, 2005, 30(2): 2429-2436.
7	Wang S X, Fan A W. Numerical investigation of CH₄/H₂/air flame bifurcations in a micro flow reactor with controlled wall temperature profile[J]. Combustion and Flame, 2022, 241: 112070.
8	Kim N I, Kato S, Kataoka T, et al. Flame stabilization and emission of small Swiss-roll combustors as heaters[J]. Combustion and Flame, 2005, 141(3): 229-240.
9	Kim N I, Aizumi S, Yokomori T, et al. Development and scale effects of small Swiss-roll combustors[J]. Proceedings of the Combustion Institute, 2007, 31(2): 3243-3250.
10	Tang A K, Cai T, Deng J, et al. Experimental investigation on combustion characteristics of premixed propane/air in a micro-planar heat recirculation combustor[J]. Energy Conversion and Management, 2017, 152: 65-71.
11	Wan J L, Su Z Y. Ultra-lean dynamics of a holder-stabilized hydrogen enriched flames in a preheated mesoscale combustor[J]. Physics of Fluids, 2022, 34(5): 057108.
12	Wan J L, Fan A W, Yao H. Effect of the length of a plate flame holder on flame blowout limit in a micro-combustor with preheating channels[J]. Combustion and Flame, 2016, 170: 53-62.
13	Li Q Q, Li J, Shi J R, et al. Effects of heat transfer on flame stability limits in a planar micro-combustor partially filled with porous medium[J]. Proceedings of the Combustion Institute, 2019, 37(4): 5645-5654.
14	Li J, Xiao H C, Li Q Q, et al. Heat recirculation and heat losses in porous micro-combustors: effects of wall and porous media properties and combustor dimensions[J]. Energy, 2021, 220: 119772.
15	Li L H, Yang W, Fan A W. Effect of the cavity aft ramp angle on combustion efficiency of lean hydrogen/air flames in a micro cavity-combustor[J]. International Journal of Hydrogen Energy, 2019, 44(11): 5623-5632.
16	Yan Y F, Liu Y, Li L X, et al. Numerical comparison of H₂/air catalytic combustion characteristic of micro-combustors with a conventional, slotted or controllable slotted bluff body[J]. Energy, 2019, 189: 116242.
17	Yang X, Yang W M, Dong S K, et al. Flame stability analysis of premixed hydrogen/air mixtures in a swirl micro-combustor[J]. Energy, 2020, 209: 118495.
18	Wan J L, Fan A W. Recent progress in flame stabilization technologies for combustion-based micro energy and power systems[J]. Fuel, 2021, 286: 119391.
19	徐露, 周俊虎, 张兴, 等. 贫氧条件下正癸烷在Pt/ZSM-5上的催化燃烧特性[J]. 化工进展, 2022, 41(1): 146-152.
	Xu L, Zhou J H, Zhang X, et al. Catalytic combustion characteristics of n-decane on Pt/ZSM-5 under oxygen deficient conditions[J]. Chemical Industry and Engineering Progress, 2022, 41(1): 146-152.
20	李凡, 姜奥林, 杨浩林, 等. 氧化锆基涂层壁面改善火焰稳定性研究[J]. 化工学报, 2021, 72(11): 5883-5892.
	Li F, Jiang A L, Yang H L, et al. Study on enhancing flame stability using zirconia-based coating walls[J]. CIESC Journal, 2021, 72(11): 5883-5892.
21	Yedala N, Raghu A K, Kaisare N S. A 3D CFD study of homogeneous-catalytic combustion of hydrogen in a spiral microreactor[J]. Combustion and Flame, 2019, 206: 441-450.
22	Wang Y F, Yang W J, Zhou J H, et al. Heterogeneous reaction characteristics and their effects on homogeneous combustion of methane/air mixture in micro channels (Ⅰ): Thermal analysis[J]. Fuel, 2018, 234: 20-29.
23	Mantzaras J, Sui R, Law C K, et al. Heterogeneous and homogeneous combustion of fuel-lean C₃H₈/O₂/N₂ mixtures over rhodium at pressures up to 6 bar[J]. Proceedings of the Combustion Institute, 2021, 38(4): 6473-6482.
24	Sui R, Mantzaras J, Bombach R, et al. Hetero-/homogeneous combustion of fuel-lean methane/oxygen/nitrogen mixtures over rhodium at pressures up to 12 bar[J]. Proceedings of the Combustion Institute, 2017, 36(3): 4321-4328.
25	Sui R, Mantzaras J, Bombach R. H₂ and CO heterogeneous kinetic coupling during combustion of H₂/CO/O₂/N₂ mixtures over rhodium[J]. Combustion and Flame, 2019, 202: 292-302.
26	潘剑锋, 卢志刚, 卢青波, 等. 催化微燃烧室内氢气/空气预混合燃烧特性[J]. 燃烧科学与技术, 2018, 24(5): 383-390.
	Pan J F, Lu Z G, Lu Q B, et al. Characteristics of premixed combustion of hydrogen and air in catalytic micro-combustor[J]. Journal of Combustion Science and Technology, 2018, 24(5): 383-390.
27	Pan J F, Miao N N, Lu Z G, et al. Experimental and numerical study on the transition conditions and influencing factors of hetero-/ homogeneous reaction for H₂/air mixture in micro catalytic combustor[J]. Applied Thermal Engineering, 2019, 154: 120-130.
28	Wang Y F, Yang W J, Zhou J H, et al. Heterogeneous reaction characteristics and its effects on homogeneous combustion of methane/air mixture in microchannels (Ⅱ): Chemical analysis[J]. Fuel, 2019, 235: 923-932.
29	Warnatz J, Maas U, Dibble R W. Combustion, Physical and Chemical Fundamentals, Modeling and Simulation[M]. New York: Springer-Verlag, 1996.
30	Deutschmann O, Maier L I, Riedel U, et al. Hydrogen assisted catalytic combustion of methane on platinum[J]. Catalysis Today, 2000, 59(1/2): 141-150.
31	Karagiannidis S, Mantzaras J, Boulouchos K. Stability of hetero-/homogeneous combustion in propane- and methane-fueled catalytic microreactors: channel confinement and molecular transport effects[J]. Proceedings of the Combustion Institute, 2011, 33(2): 3241-3249.
32	Karagiannidis S, Mantzaras J. Numerical investigation on the start-up of methane-fueled catalytic microreactors[J]. Combustion and Flame, 2010, 157(7): 1400-1413.
33	Khan A R, Anbusaravanan S, Kalathi L, et al. Investigation of dilution effect with N₂/CO₂ on laminar burning velocity of premixed methane/oxygen mixtures using freely expanding spherical flames[J]. Fuel, 2017, 196: 225-232.

[1]	Cheng CHENG, Zhongdi DUAN, Haoran SUN, Haitao HU, Hongxiang XUE. Lattice Boltzmann simulation of surface microstructure effect on crystallization fouling [J]. CIESC Journal, 2023, 74(S1): 74-86.
[2]	He JIANG, Junfei YUAN, Lin WANG, Guyu XING. Experimental study on the effect of flow sharing cavity structure on phase change flow characteristics in microchannels [J]. CIESC Journal, 2023, 74(S1): 235-244.
[3]	Yepin CHENG, Daqing HU, Yisha XU, Huayan LIU, Hanfeng LU, Guokai CUI. Application of ionic liquid-based deep eutectic solvents for CO₂ conversion [J]. CIESC Journal, 2023, 74(9): 3640-3653.
[4]	Wenzhu LIU, Heming YUN, Baoxue WANG, Mingzhe HU, Chonglong ZHONG. Research on topology optimization of microchannel based on field synergy and entransy dissipation [J]. CIESC Journal, 2023, 74(8): 3329-3341.
[5]	Linzheng WANG, Yubing LU, Ruizhi ZHANG, Yonghao LUO. Analysis on thermal oxidation characteristics of VOCs based on molecular dynamics simulation [J]. CIESC Journal, 2023, 74(8): 3242-3255.
[6]	Mengmeng ZHANG, Dong YAN, Yongfeng SHEN, Wencui LI. Effect of electrolyte types on the storage behaviors of anions and cations for dual-ion batteries [J]. CIESC Journal, 2023, 74(7): 3116-3126.
[7]	Yaxin CHEN, Hang YUAN, Guanzhang LIU, Lei MAO, Chun YANG, Ruifang ZHANG, Guangya ZHANG. Advances in enzyme self-immobilization mediated by protein nanocages [J]. CIESC Journal, 2023, 74(7): 2773-2782.
[8]	Xiaoling TANG, Jiarui WANG, Xuanye ZHU, Renchao ZHENG. Biosynthesis of chiral epichlorohydrin by halohydrin dehalogenase based on Pickering emulsion system [J]. CIESC Journal, 2023, 74(7): 2926-2934.
[9]	Chao NIU, Shengqiang SHEN, Yan YANG, Bonian PAN, Yiqiao LI. Flow process calculation and performance analysis of methane BOG ejector [J]. CIESC Journal, 2023, 74(7): 2858-2868.
[10]	Xiaoyang LIU, Jianliang YU, Yujie HOU, Xingqing YAN, Zhenhua ZHANG, Xianshu LYU. Effect of spiral microchannel on detonation propagation of hydrogen-doped methane [J]. CIESC Journal, 2023, 74(7): 3139-3148.
[11]	Tan ZHANG, Guang LIU, Jinping LI, Yuhan SUN. Performance regulation strategies of Ru-based nitrogen reduction electrocatalysts [J]. CIESC Journal, 2023, 74(6): 2264-2280.
[12]	Xiaowen ZHOU, Jie DU, Zhanguo ZHANG, Guangwen XU. Study on the methane-pulsing reduction characteristics of Fe₂O₃-Al₂O₃ oxygen carrier [J]. CIESC Journal, 2023, 74(6): 2611-2623.
[13]	Lei MAO, Guanzhang LIU, Hang YUAN, Guangya ZHANG. Efficient preparation of carbon anhydrase nanoparticles capable of capturing CO₂ and their characteristics [J]. CIESC Journal, 2023, 74(6): 2589-2598.
[14]	Tianhao BAI, Xiaowen WANG, Mengzi YANG, Xinwei DUAN, Jie MI, Mengmeng WU. Study on release and inhibition behavior of COS during high-temperature gas desulfurization process using Zn-based oxide derived from hydrotalcite [J]. CIESC Journal, 2023, 74(4): 1772-1780.
[15]	Zijian WANG, Ming KE, Jiahan LI, Shuting LI, Jinru SUN, Yanbing TONG, Zhiping ZHAO, Jiaying LIU, Lu REN. Progress in preparation and application of short b-axis ZSM-5 molecular sieve [J]. CIESC Journal, 2023, 74(4): 1457-1473.