Structural optimization of methane cracking solar tube reactor based on CFD simulation

doi:10.11949/0438-1157.20210322

Abstract

Abstract:

Solar cracking of methane has the advantages of high product purity and environmental protection. In this paper, flow field in a solar tube reactor for high-temperature cracking of methane is optimized through computational fluid dynamics (CFD) simulation by adjusting structure of the tube reactor under turbulent conditions. The carbon particle generation and aggregation model were introduced to calculate the heating effect of solar radiation more accurately. And the discrete-ordinates method (DO) model was used to solve radiation model. A jet flow and baffles were introduced to adjust and optimize the flow field. The baffle height, jet velocity and angle were optimized to enhance the reaction process. The Pareto optimal solution is screened through the definition method, and the Pareto optimal solution is encrypted with the machine learning prediction algorithm to obtain the actual operation encryption curve and corresponding operation parameters. As a result of the optimization, the conversion rate of methane is increased by about 8%. On the basis of the conversion rate, the viscosity dissipation, which represents the increase in strengthening costs, is used as an indicator to filter out the discrete Pareto optimal solution. The support vector regression (SVR) algorithm is used to interpolate the discrete Pareto optimal solution to obtain the operating curve, the corresponding jet angle and jet velocity.

Key words: methane, solar reactor, turbulence, structure optimization

摘要：

太阳能裂解甲烷具有产物纯度高且环保的优点。对湍流条件下的甲烷高温裂解太阳能管式反应器进行计算流体力学（CFD）模拟，为提高太阳能甲烷裂解反应器的转化率，通过调节反应器结构对流场进行优化。为了更加准确计算太阳能辐射的加热效应，在湍流反应扩散模型中引入碳颗粒的生成和聚集模型，并采用离散坐标（DO）模型进行辐射模型求解。然后，在太阳能管式反应器中引入射流及挡板进行流场调节，并对挡板高度、射流流速及角度进行优化，达到强化反应过程的目的。优化后的反应器中，甲烷转化率可以提高约8%。以反应转化率和代表强化成本的黏性耗散为指标，筛选出不同离散条件下的Pareto最优解，并用支持向量机回归（SVR）算法对离散的Pareto最优解进行插值，得到操作曲线和与之相对应的最优射流角度及流速。

关键词: 甲烷, 太阳能反应器, 湍流, 结构优化

CLC Number:

TQ 037⁺.1

Fan XIAO,Shengkun JIA,Yiqing LUO,Xigang YUAN. Structural optimization of methane cracking solar tube reactor based on CFD simulation[J]. CIESC Journal, 2021, 72(10): 5053-5063.

肖凡,贾胜坤,罗祎青,袁希钢. 基于CFD模拟的甲烷裂解太阳能管式反应器结构优化[J]. 化工学报, 2021, 72(10): 5053-5063.

Figures/Tables 14

Fig.1 Schematic diagram for a cell of solar reactor

Table 1 Model validation data

温度/K	转化率/%
温度/K	实验值	模拟值
1608	72	71.45
1693	95	95.03
1778	99	100
1793	99	100
1928	100	100

Fig.2 Optimization schematic diagram for a cell of solar reactor

Fig.3 Streamlines in the solar reactor for the base case (a) and optimization case (b)

Fig.4 Temperature profile in the solar reactor for the base case (a) and optimization case (b)

Fig.5 CH4 mass fraction profile in the solar reactor for the base case (a) and optimization case (b)

Fig.6 Comparison of temperature distribution for the base case(straight tube) and the optimization case in the reactor

Fig.7 Comparison of CH4 mole fraction distribution for the base case(straight tube) and the optimization case in the reactor

Table 2 The increase of methane conversion rate for different baffle heights at different jet flow rates

H/mm	增加的转化率/%
H/mm	1 m·s^-1	2 m·s^-1	3 m·s^-1	4 m·s^-1	5 m·s^-1	6 m·s^-1	7 m·s^-1	8 m·s^-1	9 m·s^-1
1.0	0.14	0.15	0.20	0.31	0.42	0.51	0.61	0.68	0.80
1.5	0.31	0.31	0.37	0.51	0.68	0.81	0.90	0.98	1.05
2.0	0.31	0.32	0.39	0.53	0.70	0.84	0.93	1.01	1.11

Fig.8 Increase of methane conversion rate in different angles and different jet flow rates

Fig.9 Comparison of temperature distribution in the reactor without optimization(0°) and after optimization(30°,45°,60°)at a flow rate of 5 m·s-1

Fig.10 Contour of viscous dissipation under different injection angles and injection flow rates

Fig.11 Relationship between increased methane conversion rate and viscous dissipation

Fig.12 Pareto optimal solution of increased methane conversion rate and viscous dissipation

References 34

1	Behzadi A, Habibollahzade A, Ahmadi P, et al. Multi-objective design optimization of a solar based system for electricity, cooling, and hydrogen production[J]. Energy, 2019, 169: 696-709.
2	Wang M Y, Wang Z, Gong X Z, et al. The intensification technologies to water electrolysis for hydrogen production — a review [J]. Renewable and Sustainable Energy Reviews, 2014, 29: 573-588.
3	张伶, 陈红梅, 魏子栋. 过渡金属氧化物催化析氧反应研究进展[J]. 化工学报, 2020, 71(9): 3876-3904.
	Zhang L, Chen H M, Wei Z D. Recent advance in transition metal oxide-based materials for oxygen evolution reaction electrocatalysts[J]. CIESC Journal, 2020, 71(9): 3876-3904.
4	常明, 陈爱平, 何洪波, 等. 层层组装修饰Ni片阳极的光催化辅助电解水制氢[J]. 化工学报, 2012, 63(7): 2195-2201.
	Chang M, Chen A P, He H B, et al. Ni anode modified by layer by layer assembly and its application in water electrolysis assisted by photocatalysis[J]. CIESC Journal, 2012, 63(7): 2195-2201.
5	钱宇, 杨思宇, 贾小平, 等. 能源和化工系统的全生命周期评价和可持续性研究[J]. 化工学报, 2013, 64(1): 133-147.
	Qian Y, Yang S Y, Jia X P, et al. Life cycle assessment and sustainability of energy and chemical processes[J]. CIESC Journal, 2013, 64(1): 133-147.
6	曾亮, 巩金龙. 化学链重整直接制氢技术进展[J]. 化工学报, 2015, 66(8): 2854-2862.
	Zeng L, Gong J L. Advances in chemical looping reforming for direct hydrogen production[J]. CIESC Journal, 2015, 66(8): 2854-2862.
7	Qiao C Z. Status and development of hydrogen production from carbonaceous energy sources[J]. Energy Conservation & Environmental Protection in Transportation, 2010, 2: 40-43.
8	Villafán-Vidales H I, Arancibia-Bulnes C A, Riveros-Rosas D, et al. An overview of the solar thermochemical processes for hydrogen and syngas production: reactors, and facilities[J]. Renewable and Sustainable Energy Reviews, 2017, 75: 894-908.
9	Abanades S, Flamant G. Experimental study and modeling of a high-temperature solar chemical reactor for hydrogen production from methane cracking[J]. International Journal of Hydrogen Energy, 2007, 32(10/11): 1508-1515.
10	Maag G, Zanganeh G, Steinfeld A. Solar thermal cracking of methane in a particle-flow reactor for the co-production of hydrogen and carbon[J]. International Journal of Hydrogen Energy, 2009, 34(18): 7676-7685.
11	Z'Graggen A, Haueter P, Trommer D, et al. Hydrogen production by steam-gasification of petroleum coke using concentrated solar power(Ⅱ): Reactor design, testing, and modeling[J]. International Journal of Hydrogen Energy, 2006, 31(6): 797-811.
12	Abanades S, Kimura H, Otsuka H. A drop-tube particle-entrained flow solar reactor applied to thermal methane splitting for hydrogen production[J]. Fuel, 2015, 153: 56-66.
13	Abanades S, Kimura H, Otsuka H. Hydrogen production from thermo-catalytic decomposition of methane using carbon black catalysts in an indirectly-irradiated tubular packed-bed solar reactor[J]. International Journal of Hydrogen Energy, 2014, 39(33): 18770-18783.
14	Rodat S, Abanades S, Sans J L, et al. A pilot-scale solar reactor for the production of hydrogen and carbon black from methane splitting[J]. International Journal of Hydrogen Energy, 2010, 35(15): 7748-7758.
15	Abanades S, Kimura H, Otsuka H. Hydrogen production from CO₂-free thermal decomposition of methane: design and on-sun testing of a tube-type solar thermochemical reactor[J]. Fuel Processing Technology, 2014, 122: 153-162.
16	Rodat S, Abanades S, Flamant G. Co-production of hydrogen and carbon black from solar thermal methane splitting in a tubular reactor prototype[J]. Solar Energy, 2011, 85(4): 645-652.
17	Valdés-Parada F J, Romero-Paredes H, Espinosa-Paredes G. Numerical simulation of a tubular solar reactor for methane cracking[J]. International Journal of Hydrogen Energy, 2011, 36(5): 3354-3363.
18	Patrianakos G, Kostoglou M, Konstandopoulos A. One-dimensional model of solar thermal reactors for the co-production of hydrogen and carbon black from methane decomposition[J]. International Journal of Hydrogen Energy, 2011, 36(1): 189-202.
19	Caliot C, Flamant G, Patrianakos G, et al. Two-dimensional model of methane thermal decomposition reactors with radiative heat transfer and carbon particle growth[J]. AIChE Journal, 2012, 58(8): 2545-2556.
20	Cao X P, Jia S K, Avellaneda J M, et al. An optimization method to find the thermodynamic limit on enhancement of solar thermal decomposition of methane[J]. International Journal of Hydrogen Energy, 2019, 44(31): 16164-16175.
21	McGillis W R, Carey V P. On the role of Marangoni effects on the critical heat flux for pool boiling of binary mixtures[J]. Journal of Heat Transfer, 1996, 118(1): 103-109.
22	Eastman J A, Choi S U S, Li S, et al. Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles[J]. Applied Physics Letters, 2001, 78(6): 718-720.
23	余徽, 印永祥, 戴晓雁. 等离子体射流裂解甲烷制乙炔的数值模拟[J]. 化工学报, 2006, 57(10): 2319-2326.
	Yu H, Yin Y X, Dai X Y. Numerical simulation of methane conversion to acetylene in plasma jet reactor[J]. Journal of Chemical Industry and Engineering (China), 2006, 57(10): 2319-2326.
24	Chen Q, Meng J. Field synergy analysis and optimization of the convective mass transfer in photocatalytic oxidation reactors[J]. International Journal of Heat and Mass Transfer, 2008, 51(11/12): 2863-2870.
25	Wang J L, Feng X Y, Yu T. A geometric approach to support vector regression and its application to fermentation process fast modeling[J]. Chinese Journal of Chemical Engineering, 2012, 20(4): 715-722.
26	Rodat S, Abanades S, Coulié J, et al. Kinetic modelling of methane decomposition in a tubular solar reactor[J]. Chemical Engineering Journal, 2009, 146(1): 120-127.
27	Hirsch D, Steinfeld A. Solar hydrogen production by thermal decomposition of natural gas using a vortex-flow reactor[J]. International Journal of Hydrogen Energy, 2004, 29(1): 47-55.
28	Nezzari B, Gomri R. Study of cracking of methane for hydrogen production using concentrated solar energy[J]. International Journal of Hydrogen Energy, 2020, 45(1): 135-148.
29	Kogan A. Production of hydrogen and carbon by solar thermal methane splitting(Ⅱ): Room temperature simulation tests of seeded solar reactor[J]. International Journal of Hydrogen Energy, 2004, 29(12): 1227-1236.
30	Ozalp N, Ibrik K, Al-Meer M. Kinetics and heat transfer analysis of carbon catalyzed solar cracking process[J]. Energy, 2013, 55: 74-81.
31	Ozalp N, Kanjirakat A. A computational fluid dynamics study on the effect of carbon particle seeding for the improvement of solar reactor performance[J]. Journal of Heat Transfer, 2010, 132(12): 1229-1241.
32	Seinfeld J H, Pandis S N, Noone K. Atmospheric chemistry and physics: from air pollution to climate change[J]. Physics Today, 1998, 51(10): 88-90.
33	Kostoglou M, Karabelas A J. Evaluation of numerical methods for simulating an evolving particle size distribution in growth processes[J]. Chemical Engineering Communications, 1995, 136(1): 177-199.
34	Jia S, Zhang C, Yuan X, et al. An optimization approach to find the thermodynamic limit on convective mass transfer enhancement for a given viscous dissipation[J]. Chemical Engineering Science, 2016, 146: 26-34.

[1]	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.
[2]	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.
[3]	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.
[4]	Junhua DING, Shurong YU, Shipeng WANG, Xianzhi HONG, Xin BAO, Xuexing DING. Flow simulation and sealing performance test of ultra-high speed dry gas seal under multiple effects [J]. CIESC Journal, 2023, 74(5): 2088-2099.
[5]	Jiyuan LI, Jinwang LI, Liuwei ZHOU. Heat transfer performance of cold plates with different turbulence structures [J]. CIESC Journal, 2023, 74(4): 1474-1488.
[6]	Han HU, Liang YANG, Chunxiao LI, Daoping LIU. Kinetics of methane storage in the natural tobacco leaching filtrate in the hydrate form [J]. CIESC Journal, 2023, 74(3): 1313-1321.
[7]	Xiaowan PENG, Xiaonan GUO, Chun DENG, Bei LIU, Changyu SUN, Guangjin CHEN. Modeling and simulation of CH₄/N₂ separation process with two absorption-adsorption columns using ZIF-8 slurry [J]. CIESC Journal, 2023, 74(2): 784-795.
[8]	Guojun XI, Zihan LIU, Guangping LEI. Enhanced adsorption and separation of low concentration coalbed methane based on synergistic effect between FeTPPs and CuBTC [J]. CIESC Journal, 2022, 73(9): 3940-3949.
[9]	Shanshan LIAO, Shaogang ZHANG, Junjun TAO, Jiahao LIU, Jinhui WANG. Numerical simulation analysis of vertical jet fire impinging on the pipeline [J]. CIESC Journal, 2022, 73(9): 4226-4234.
[10]	Limin WANG, Shuyu GUO, Xing XIANG, Shaotong FU. Research progress of energy-minimization multi-scale method for turbulent system [J]. CIESC Journal, 2022, 73(6): 2415-2426.
[11]	Cuiping TANG, Yanan ZHANG, Deqing LIANG, Xiang LI. Inhibition effect of chain end modified polyvinyl caprolactam on methane hydrate formation [J]. CIESC Journal, 2022, 73(5): 2130-2139.
[12]	Shuai YAN, Jiabao YANG, Yan GONG, Qinghua GUO, Guangsuo YU. Effects of CO₂ dilution on the structure of methane inverse diffusion flame [J]. CIESC Journal, 2022, 73(3): 1335-1342.
[13]	Baowen WANG, Gang ZHANG, Tongqing LIU, Weiguang LI, Mengjia WANG, Deshun LIN, Jingjing MA. Research on chemical looping reforming of CH₄ by CeO₂doped CuFe₂O₄oxygen carrier coupled with CO₂ thermocatalytic reduction [J]. CIESC Journal, 2022, 73(12): 5414-5426.
[14]	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.
[15]	Yi WU, Xiaoping WEN, Sumei ZHANG, Zhidong GUO, Haoxin DENG, Wentao JI. Study on combustion instability of hydrogen methane-doped in vertical circular tubes [J]. CIESC Journal, 2022, 73(10): 4780-4790.