基于COMSOL的干燥箱物理场分析与结构优化

doi:10.13304/j.nykjdb.2021.0770

摘要/Abstract

摘要：

干燥箱是农业物料进行太阳能热风干燥的关键装置，其结构合理性直接影响物料干燥的品质和效率。为提升干燥效果，以太阳能热风干燥箱物理场分布的均匀程度为研究对象，采用试验和COMSOL数值模拟相结合的方法，对箱体内风速场、温度场的分布特点进行分析，并根据分析结果完成干燥箱结构优化。结果表明，COMSOL模拟仿真所得风速和温度的分布规律与试验结果一致，可用于准确模拟干燥箱内物理场。依托该模拟分析方法，提出了改变进风口位置、添加带孔挡流板、构建隔断式气室的优化设计方案，将干燥箱内风速场分布的不均匀系数降至了10%以下，有效保证了物料干燥的均匀性。上述结果可为太阳能热风干燥设备的结构改进提供参考。

关键词: 干燥箱, COMSOL, 风速场, 数值模拟, 结构优化

Abstract:

Drying box is the key device for solar drying agricultural material， and its structure rationality directly affect the material drying quality and efficiency. In order to improve drying effect， this paper took solar hot air drying box physical distribution uniformity as the research object to analyze the distribution of wind field and temperature field inside the box body characteristics by the combination of experiment and COMSOL numerical simulation method， and optimized drying box structure optimization based on the analysis. The results showed that the COMSOL simulation of the wind speed and temperature distribution was consistent with the experimental results， so it could be used to accurately simulate the physical field inside the drying chamber. Based on the simulation analysis method， this paper put forward optimization design scheme of changing air inlet location， adding a hole blocking flow board， and building partition type of air chamber， by which the uneven coefficient of wind velocity field distribution inside drying box was reduced to less than 10%， and effectively guaranteed the uniformity of material drying. The above results provided reference for the structure improvement of the solar hot air drying equipment.

Key words: solar dryer, numerical simulation, structural optimization, COMSOL, wind velocity field

中图分类号:

S214.4

郭文斌, 李瑶, 黄长华, 杜建强, 钱珊珠, 何泽民, 高晶晶. 基于COMSOL的干燥箱物理场分析与结构优化[J]. 中国农业科技导报, 2022, 24(10): 90-98.

Wenbin GUO, Yao LI, Zhanghua HUANG, Jianqiang DU, Shanzhu QIAN, Zemin HE, Jingjing GAO. Physical Field Analysis and Structure Optimization of Solar Hot Air Dryer Based on COMSOL[J]. Journal of Agricultural Science and Technology, 2022, 24(10): 90-98.

图/表 14

图1 太阳能热风干燥系统试验平台注：1—太阳；2—太阳能集热器；3—风管；4—鼓风机；5—干燥箱；6—多通道记录仪。

Fig. 1 Solar hot-air drying system test-bedNote： 1—Sun； 2—Solar collector； 3—Duct； 4—Blower； 5—Drying box； 6—Multichannel recorder.

图2 热风干燥箱结构注：1—透风托盘； 2—出风口； 3—箱体；4—进风口。

Fig. 2 Structural of hot-air drying boxNote： 1—Drafty tray； 2—Outlet； 3—Case； 4—Air inlet.

图3 干燥箱内传感器位置

Fig. 3 Positions of sensors drying box

表1 模型及边界条件参数设置

Table 1 Parameters of boundary conditions setting

对象 Object	参数 Parameter
进风口 Air inlet	风速Wind velocity：5， 7， 10 m·s^-1
出风口 Air outlet	压力 Pressure： 0 Pa
箱壁 Drying box wall	无滑移 No slip
进风口温度 Air inlet temperature	312 K（39 ℃）

图4 干燥箱内各层风速分布

Fig. 4 Wind velocity distribution at different layers of drying box

表2 干燥箱内各层风速、温度分布及其不均匀系数

Table 2 Distribution of wind velocity and temperature and their non-uniformity coefficients in different layers of drying box

进风口风速 Wind velocity/（m·s^-1）	层高 Layer height/mm	平均风速 Average wind velocity/（m·s^-1）	风速场不均匀系数M/%	平均温度 Average temperature/℃	温度场不均匀系数T_v/%
5	150	0.54	80.68	38.60	1.29
	450	0.76	79.70	38.55	1.30
	750	0.67	73.98	38.50	1.30
7	150	0.77	78.10	35.29	0.72
	450	0.85	63.31	35.60	1.40
	750	0.82	64.12	35.34	1.28
10	150	0.87	86.28	37.53	0.63
	450	0.75	86.32	37.50	0.56
	750	0.78	85.26	37.34	0.71

图5 干燥箱内横向截面风速分布

Fig. 5 Distribution of wind velocity in the transverse section of drying box

表3 COMSOL环境下干燥箱各层风速场不均匀系数

Table 3 Non-uniformity coefficient of wind velocity field of drying box under the COMSOL model

进风口风速 Air inlet wind velocity /（m·s^-1）	M：不均匀系数Non-uniformity coefficient/%
进风口风速 Air inlet wind velocity /（m·s^-1）	150 mm	450 mm	750 mm
5	77.7	61.4	66.6
7	85.0	56.1	55.9
10	84.2	55.8	55.7

表4 层高450 mm不同进风口风速下各测点风速实测值与模拟值对比

Table 4 Comparison of measured and simulated wind velocities at different measurement points at 450 mm layer

风速测点编号 Serial number	进风口风速 Air inlet wind velocity： 5 m·s^-1			进风口风速 Air inlet wind velocity： 7 m·s^-1			进风口风速 Air inlet wind velocity： 10 m·s^-1
风速测点编号 Serial number	实测值 Measured value/（m·s^-1）	模拟值Simulation value/（m·s^-1）	误差 Error /%	实测值 Measured value/（m·s^-1）	模拟值 Simulation value/（m·s^-1）	误差 Error /%	实测值 Measured value/（m·s^-1）	模拟值 Simulation value/（m·s^-1）	误差 Error /%
1	0.76	0.70	7.89	0.52	0.53	1.92	0.65	0.64	1.54
2	0.39	0.36	7.69	0.56	0.57	1.79	0.62	0.67	8.06
3	0.87	0.79	9.20	0.57	0.53	7.02	0.50	0.69	18.00
4	0.70	0.66	5.71	0.83	0.84	1.20	0.56	0.57	1.79
5	1.67	1.60	4.19	1.80	1.96	8.89	3.14	3.20	1.91
6	0.64	0.65	1.56	0.94	0.88	6.38	0.60	0.59	1.67
7	0.67	0.69	2.99	0.97	0.92	5.15	1.31	1.32	0.76
8	1.65	1.70	3.03	2.16	2.35	8.80	3.33	3.30	0.90
9	0.58	0.62	6.90	0.98	0.95	3.06	1.46	1.40	4.11
10	0.59	0.61	3.39	0.44	0.43	2.27	0.81	0.89	9.88
11	0.67	0.71	5.97	0.47	0.45	4.26	0.54	0.58	7.41
12	0.33	0.34	3.03	0.39	0.41	5.13	0.93	0.90	3.23
均值Mean	0.84	0.84	4.09	1.00	1.02	5.02	1.41	1.42	4.94

图6 过进风口中心纵向截面风速分布

Fig. 6 Wind velocity distribution in the vertical section through inlet center

图7 含隔断式气室的干燥箱注：1—进风口；2—出风口；3—箱体；4.带孔挡流板。

Fig. 7 Drying box with a partition-typeNote： 1—Air inlet； 2—Air outlet 3—Oven 4—Perforated baffle platechamber.

图8 改进后干燥箱纵向截面风速分布

Fig. 8 Wind velocity distribution in the vertical section of improved drying box

图9 改进后干燥箱横向截面风速分布

Fig. 9 Wind velocity distribution in the transverse section of improved drying box

表5 不同进风口风速下各层截面风速场分布不均匀系数

Table 5 Non-uniformity coefficients of wind velocity field under different inlet wind velocities

进风口风速 Air inlet wind velocity/（m·s^-1）	M：分布不均匀系数Non-uniformity coefficient/%
进风口风速 Air inlet wind velocity/（m·s^-1）	550 mm	850 mm	1 150 mm	1 450 mm
5	39.33	13.88	9.36	8.53
7	39.31	13.96	9.38	8.41
10	39.32	14.05	9.46	8.32

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