Analysis of multi-physical field characteristics in a microwave reactor with a mode stirrer

doi:10.16085/j.issn.1000-6613.2021-1123

Abstract

Abstract:

As a new energy source, biodiesel has attracted widespread attention. Microwave heating is widely used to produce biodiesel due to its high efficiency. However, the non-uniform heating of microwave is the main problem that needs to be solved urgently. So, a mode stirrer was introduced into a microwave reactor with an interlayer, and the multi-physics field simulation of microwave heating process was carried out by coupling the Maxwell and heat transfer equations with COMSOL software. The arbitrary Lagrangian-Eulerian method was used to deal with the mode stirring, and the influence of different mode stirrer parameters on the microwave heating characteristics was discussed. The results showed that compared with the microwave heating model without mode stirring, the electric field distribution in the material was changed at all times by mode stirring, thus improving the heating efficiency and heating uniformity. With the increase of the height and length of the mode stirrer, the material average temperature and coefficient of variation (COV) showed a downward trend on the whole. The average temperature of material increased linearly with the increase of stirring speed, and COV showed an overall upward trend with the increase of stirring speed. Through response surface analysis, it was found that the primary and secondary order that affected the average temperature and COV was: stirrer height > stirrer speed > stirrer length, where the interaction between the stirrer height and the speed had a significant effect on the average temperature. Considering the average temperature and COV, the best stirring conditions obtained by response surface optimization were stirrer height λ_H of 0.164, stirrer length λ_B of 0.31, stirring speed N of 30r/min, COV of 0.11×10^-2, and average temperature of 22.15℃.

Key words: microwave reactor, biodiesel, mode stirrer, moving grid, heating uniformity, multi-physical field simulation

摘要：

生物柴油作为一种新能源已引起了广泛关注，微波加热因其高效性被广泛用于制备生物柴油。然而，微波的不均匀加热是目前亟须解决的主要问题，因此本文在微波夹层反应釜内引入一种模式搅拌器，通过COMSOL软件耦合麦克斯韦、传热方程，对微波加热过程进行多物理场仿真，并采用动网格技术处理模式搅拌，探讨不同模式搅拌器参数对微波加热特性的影响，发现：①与无模式搅拌的微波加热模型相比，模式搅拌时刻改变物料中的电场分布，从而改善加热效率和加热均匀性；②物料平均温度与温度变异系数（COV）随搅拌器高度和长度的增加，整体上呈下降趋势；③物料平均温度随搅拌转速的增加线性提高，COV随转速的增加整体上呈上升趋势；④通过响应面分析发现对平均温度和COV产生影响的因素为：搅拌器高度>搅拌转速>搅拌器长度，其中搅拌器高度与转速的交互作用对平均温度影响显著；最后综合考虑平均温度和COV，响应面优化后的最佳搅拌条件为：搅拌器高度λ_H=0.164、搅拌器长度λ_B=0.31、搅拌转速N=30r/min，此时COV=0.11×10^-2、平均温度为22.15℃。

关键词: 微波反应釜, 生物柴油, 模式搅拌器, 动网格, 加热均匀性, 多物理场仿真

CLC Number:

TQ052.5

ZOU Pengcheng, JIN Guangyuan, LI Zhenfeng, SONG Chunfang, HAN Taibai, ZHU Yulian. Analysis of multi-physical field characteristics in a microwave reactor with a mode stirrer[J]. Chemical Industry and Engineering Progress, 2022, 41(5): 2301-2310.

邹鹏程, 金光远, 李臻峰, 宋春芳, 韩太柏, 祝玉莲. 一种具有模式搅拌的微波反应釜内多物理场特性分析[J]. 化工进展, 2022, 41(5): 2301-2310.

Figures/Tables 23

腔体高度H₀/mm	底部高度c₀/mm	反应釜直径T/mm	波导高度h₀/mm	夹层厚度 d/mm	物料高度 /mm
390	60	260	344	20	240

密度 /kg·m^-3	动力黏度/Pa·s	相对磁导率	热导率 /W·m^-1·K^-1	恒压热容 /J·kg^-1·K^-1	比热率	相对介电常数	电导率 /S·m^-1
965	0.065	1	0.15	3000	1	2.73- 0.13j^［24］	0

试验号	A （搅拌器长度λ_B）	B （搅拌器高度λ_H）	C （搅拌转速N）/r·min^-1	Y₁（COV）	Y₂ （平均温度）/℃
1	0.31	0.06	18	0.164 $×$ 10^-2	21.890
2	0.46	0.06	18	0.196 $×$ 10^-2	22.005
3	0.31	0.32	18	0.187 $×$ 10^-2	21.421
4	0.46	0.32	18	0.146 $×$ 10^-2	21.401
5	0.31	0.19	6	0.074 $×$ 10^-2	20.665
6	0.46	0.19	6	0.064 $×$ 10^-2	20.660
7	0.31	0.19	30	0.121 $×$ 10^-2	22.026
8	0.46	0.19	30	0.117 $×$ 10^-2	21.761
9	0.385	0.06	6	0.243 $×$ 10^-2	20.955
10	0.385	0.32	6	0.185 $×$ 10^-2	20.733
11	0.385	0.06	30	0.252 $×$ 10^-2	22.791
12	0.385	0.32	30	0.140 $×$ 10^-2	21.917
13	0.385	0.19	18	0.126 $×$ 10^-2	21.290
14	0.385	0.19	18	0.126 $×$ 10^-2	21.290
15	0.385	0.19	18	0.126 $×$ 10^-2	21.290
16	0.385	0.19	18	0.126 $×$ 10^-2	21.290
17	0.385	0.19	18	0.126 $×$ 10^-2	21.290

试验号	A （搅拌器长度λ_B）	B （搅拌器高度λ_H）	C （搅拌转速N）/r·min^-1	Y₁（COV）	Y₂ （平均温度）/℃
1	0.31	0.06	18	0.164 $×$ 10^-2	21.890
2	0.46	0.06	18	0.196 $×$ 10^-2	22.005
3	0.31	0.32	18	0.187 $×$ 10^-2	21.421
4	0.46	0.32	18	0.146 $×$ 10^-2	21.401
5	0.31	0.19	6	0.074 $×$ 10^-2	20.665
6	0.46	0.19	6	0.064 $×$ 10^-2	20.660
7	0.31	0.19	30	0.121 $×$ 10^-2	22.026
8	0.46	0.19	30	0.117 $×$ 10^-2	21.761
9	0.385	0.06	6	0.243 $×$ 10^-2	20.955
10	0.385	0.32	6	0.185 $×$ 10^-2	20.733
11	0.385	0.06	30	0.252 $×$ 10^-2	22.791
12	0.385	0.32	30	0.140 $×$ 10^-2	21.917
13	0.385	0.19	18	0.126 $×$ 10^-2	21.290
14	0.385	0.19	18	0.126 $×$ 10^-2	21.290
15	0.385	0.19	18	0.126 $×$ 10^-2	21.290
16	0.385	0.19	18	0.126 $×$ 10^-2	21.290
17	0.385	0.19	18	0.126 $×$ 10^-2	21.290

References 28

1	蒋波, 张晓东, 孙立, 等. 微波促进生物柴油制备的研究进展[J]. 化工进展, 2010, 29(11): 2057-2065.
	JIANG Bo, ZHANG Xiaodong, SUN Li, et al. Advances in micowave promoted biodiesel synthesis[J]. Chemical Industry and Engineering Progress, 2010, 29(11): 2057-2065.
2	PARANGI T, MISHRA M K. Solid acid catalysts for biodiesel production[J]. Comments on Inorganic Chemistry, 2020, 40(4): 176-216.
3	ADAM D. Microwave chemistry: out of the kitchen[J]. Nature, 2003, 421(6923): 571-572.
4	KHEDRI B, MOSTAFAEI M, ARDEBILI S M S. A review on microwave-assisted biodiesel production[J]. Energy Sources A: Recovery Util. Environ. Eff., 2019, 41(19): 2377-2395.
5	VASUDEV H, SINGH G, BANSAL A, et al. Microwave heating and its applications in surface engineering: a review[J]. Materials Research Express, 2019, 6(10): 102001.
6	KELEN A, RESS S, NAGY T, et al. “3D layered thermography” method to map the temperature distribution of a free flowing bulk in case of microwave drying[J]. International Journal of Heat and Mass Transfer, 2006, 49(5/6): 1015-1021.
7	LIU S X, FUKUOKA M, SAKAI N. A finite element model for simulating temperature distributions in rotating food during microwave heating[J]. Journal of Food Engineering, 2013, 115(1): 49-62.
8	ZHOU J, YANG X Q, CHU Y, et al. A novel algorithm approach for rapid simulated microwave heating of food moving on a conveyor belt[J]. Journal of Food Engineering, 2020, 282: 110029.
9	ZHU H C, HE J B, HONG T, et al. A rotary radiation structure for microwave heating uniformity improvement[J]. Applied Thermal Engineering, 2018, 141: 648-658.
10	PITCHAI K, CHEN J J, BIRLA S, et al. A microwave heat transfer model for a rotating multi-component meal in a domestic oven: development and validation[J]. Journal of Food Engineering, 2014, 128: 60-71.
11	YE J H, HONG T, WU Y Y, et al. Model stirrer based on a multi-material turntable for microwave processing materials[J]. Materials, 2017, 10(2): 95.
12	YE J H, LAN J Q, XIA Y, et al. An approach for simulating the microwave heating process with a slow- rotating sample and a fast-rotating mode stirrer[J]. International Journal of Heat and Mass Transfer, 2019, 140: 440-452.
13	MENG Q, LAN J Q, HONG T, et al. Effect of the rotating metal patch on microwave heating uniformity[J]. Journal of Microwave Power and Electromagnetic Energy, 2018, 52(2): 94-108.
14	ZHU H C, YE J H, GULATI T, et al. Dynamic analysis of continuous-flow microwave reactor with a screw propeller[J]. Applied Thermal Engineering, 2017, 123: 1456-1461.
15	聂国宇, 金光远, 吴雁泽, 等. 一种带夹层釜式微波反应器加热效果模拟分析[J]. 化学工业与工程, 2020, 37(4): 49-57.
	NIE G Y, JIN G Y, WU Y Z, et al. Simulation analysis of heating effect of a microwave reactor with interlayer tank[J]. Chemical Industry and Engineering, 2020, 37(4): 49-57.
16	ZHOU J, YANG X Q, YE J H, et al. Arbitrary Lagrangian-Eulerian method for computation of rotating target during microwave heating[J]. International Journal of Heat and Mass Transfer, 2019, 134: 271-285.
17	HONG Y D, LIN B Q, LI H, et al. Three-dimensional simulation of microwave heating coal sample with varying parameters[J]. Applied Thermal Engineering, 2016, 93: 1145-1154.
18	GOLDBLITH S A, WANG D I. Effect of microwaves on Escherichia coli and Bacillus subtilis [J]. Applied Microbiology, 1967, 15(6): 1371-1375.
19	HUANG K M, LIAO Y H. Transient power loss density of electromagnetic pulse in debye media[J]. IEEE Transactions on Microwave Theory and Techniques, 2015, 63(1): 135-140.
20	PANDIT R B, PRASAD S. Finite element analysis of microwave heating of potato-transient temperature profiles[J]. Journal of Food Engineering, 2003, 60(2): 193-202.
21	PITCHAI K, BIRLA S L, SUBBIAH J, et al. Coupled electromagnetic and heat transfer model for microwave heating in domestic ovens[J]. Journal of Food Engineering, 2012, 112(1/2): 100-111.
22	朱铧丞, 兰俊卿, 吴丽, 等. 微波辅助生物柴油生产的一体化计算[J]. 四川大学学报(自然科学版), 2015, 52(6): 1285-1292.
	ZHU H C, LAN J Q, WU L, et al. Integrative calculation for microwave process of biodiesel production[J]. Journal of Sichuan University (Natural Science Edition), 2015, 52(6): 1285-1292.
23	HAROUCHE I P F, SHAFAI C. Simulation of shaped comb drive as a stepped actuator for microtweezers application[J]. Sensors and Actuators A: Physical, 2005, 123/124: 540-546.
24	宋睿, 金光远, 崔政伟, 等. 酯交换反应体系混合物料的介电特性[J]. 化工学报, 2018, 69(8): 3670-3677.
	SONG R, JIN G Y, CUI Z W, et al. Dielectric properties of mixed materials in transesterification reaction system[J]. CIESC Journal, 2018, 69(8): 3670-3677.
25	ZHANG M, JIA X, TANG Z, et al. A fast and accurate method for computing the microwave heating of moving objects[J]. Applied Sciences, 2020, 10(8): 2985.
26	YE J H, XIA Y, YI Q Y, et al. Multiphysics modeling of microwave heating of solid samples in rotary lifting motion in a rectangular multi-mode cavity[J]. Innovative Food Science & Emerging Technologies, 2021, 73: 102767.
27	HE J L, YANG Y, ZHU H C, et al. Microwave heating based on two rotary waveguides to improve efficiency and uniformity by gradient descent method[J]. Applied Thermal Engineering, 2020, 178: 115594.
28	TANG Z M, HONG T, LIAO Y H, et al. Frequency-selected method to improve microwave heating performance[J]. Applied Thermal Engineering, 2018, 131: 642-648.

[1]	JIN Xin, LI Yushan, XIE Qingqing, WANG Mengyu, XIA Xingfan, YANG Chaohe. Progress on solketal synthesis catalyzed by porous materials [J]. Chemical Industry and Engineering Progress, 2023, 42(2): 731-743.
[2]	QIN Zhenfang, LIAO Rihong, MA Weifang. Research progress on absorption-microalgae fixation of low concentration CO₂ and synchronous oil production in gas power plant [J]. Chemical Industry and Engineering Progress, 2023, 42(1): 94-106.
[3]	ZHAO Jianbing, YANG Dan, SHU Yuancao, ZHU Junbo, PU Shiping, SONG Xiaodan, LIU Shouqing, CHAI Xijuan, LI Xuemei. Preparation of Na₂CO₃/CF solid base and its catalytic transesterification of rapeseed oil [J]. Chemical Industry and Engineering Progress, 2022, 41(7): 3608-3614.
[4]	MA Xin, WANG Shuang, LI Fashe, ZHANG Yishui, JIANG Shang. Simulation and experimental research on the atomization characteristics of waste oil biodiesel [J]. Chemical Industry and Engineering Progress, 2022, 41(2): 655-665.
[5]	ZHU Changhui, ZHU Wenchao, LUO Jia, TIAN Baohe, SUN Jialin, ZOU Zhiyun. Recent advances in microwave-intensified transesterification for biodiesel preparation [J]. Chemical Industry and Engineering Progress, 2022, 41(10): 5145-5154.
[6]	JI Shulan, LI Xun, WANG Fei. Immobilization of Rhizopus oryzae onto loofah sponge as a whole-cell biocatalyst to preparation of biodiesel from Comus wilsoniana fruit oil [J]. Chemical Industry and Engineering Progress, 2022, 41(10): 5381-5389.
[7]	YUE Qianqian, GAO Lijing, XIAO Guomin, WEI Ruiping, LEI Yan. Process of the reactor and progress of biodiesel continuous production [J]. Chemical Industry and Engineering Progress, 2021, 40(S2): 81-88.
[8]	ZOU Shuai, LI Yuqin, MA Yiran, QI Zhenhua, JIA Quanwei. Diethanolamine strengthening CO₂ fixation and lipid accumulation in Coccomyxa subellipsoidea C-169 [J]. Chemical Industry and Engineering Progress, 2021, 40(9): 5222-5230.
[9]	BAO Wenjun, LI Zifu, WANG Xuemei, GAO Ruiling, CHENG Shikun, MEN Yu. Progress of oleaginous yeast utilizing low-cost substrates to synthesize lipids [J]. Chemical Industry and Engineering Progress, 2021, 40(5): 2484-2495.
[10]	Xinyu MENG, Jie XU, Jie WAN, Yanjun LIU, Xiaoli WANG, Jun ZHANG, Feng ZHENG, Jianfei KAN, Gongde WU. Research and industrialization progress in synthesis of glycerol carbonate [J]. Chemical Industry and Engineering Progress, 2020, 39(9): 3739-3749.
[11]	Hailiang XING,Xunzan DONG,Benyong HAN,Shuxiang GENG,Delu NING,Ting MA,Xuya YU. Cell growth and lipid accumulation of Monoraphidium sp. QLZ-3 in walnut shell extracts with carbon dioxide [J]. Chemical Industry and Engineering Progress, 2020, 39(4): 1575-1582.
[12]	Shuang WANG,Youhao WANG,Fashe LI,Wenchao WANG,Meng SUI. Analysis of oxidative degradation degree of biodiesel based on UV absorbance [J]. Chemical Industry and Engineering Progress, 2020, 39(2): 506-512.
[13]	Wen TENG, Yong CHEN, Meng SUI, Fashe LI. Effect of TEPA and [MI][C₆H₂(OH)₃COO] compound on antioxidant property of biodiesel [J]. Chemical Industry and Engineering Progress, 2020, 39(11): 4427-4434.
[14]	Zejian HUANG,Yiqing LUO,Xigang YUAN. Environmental impact assessment of water treatment integrated microalgae biodiesel life cycle system [J]. Chemical Industry and Engineering Progress, 2020, 39(1): 34-41.
[15]	YUAN Chuan, LU Houfang, LIU Changjun, JIANG Wei, LIU Yingying, LIANG Bin. Effects of water and free fatty acids on biodiesel production using DBU as catalyst [J]. Chemical Industry and Engineering Progress, 2018, 37(09): 3386-3392.