Structural Optimization and Moisture Content Simulation of Tea Residue Dual Axis Stirring Dryer

doi:10.13304/j.nykjdb.2023.0913

Abstract

Abstract:

The most important step of tea residue reuse is drying. In order to optimize the drying process of tea residue dual-axis stirring dryer， Euler-Euler multiphase flow model and component transport model of Fluent software was used to simulate. The results of structure optimization and water content analysis showed that： adding the diversion grille could greatly improve the uniformity and average temperature of the flow field inside the dryer. The change trend of the average temperature inside the dryer increased first and then decreased with the increase of the angle of the diversion grille， and increased first and then decreased with the increase of the number of grilles. The best effect was achieved when 5 grilles were arranged with a spacing of 1 030 mm， and the average internal temperature of the dryer was 429.23 ℃. When the hot air temperature was 500 ℃ and the spindle speed was 300 r·min^-1， the water content of the material at the discharge port of the dryer was the lowest， which was 12.91%. This simulation result provided technical parameters for the design of large double-shaft mixing dryer.

Key words: drying, double axis stirring, numerical simulation, structural optimization, tea residue

摘要：

茶渣重新利用的关键步骤就是干燥，为了优化茶渣双轴搅拌干燥机的干燥过程，利用Fluent软件采用欧拉-欧拉多相流模型和组分输运模型进行模拟。结构优化和含水率分析结果表明：增添导流格栅能较大程度地改善干燥机内部流场的均匀程度和平均温度，干燥机内平均温度的变化趋势随着导流格栅夹角的增加而先增加后下降，随着格栅数量的增加而先增加后下降；当导流格栅夹角在60°，布置方式为5个格栅间距1 030 mm时效果最好，此时干燥机内部平均温度为429.23 ℃；热风温度为500 ℃，主轴转速为300 r·min^-1时，干燥机出料口物料含水率最低，为12.91%。此模拟结果可为大型双轴搅拌干燥机的设计提供技术参数。

关键词: 干燥, 双轴搅拌, 数值模拟, 结构优化, 茶渣

CLC Number:

S226.6

Huapeng HU, Xukun ZHANG, Jiajun CHEN, Yangyang PAN, Peilin YANG, Zhi LU. Structural Optimization and Moisture Content Simulation of Tea Residue Dual Axis Stirring Dryer[J]. Journal of Agricultural Science and Technology, 2025, 27(4): 120-132.

胡华鹏, 张绪坤, 谌佳君, 潘杨杨, 杨佩林, 鲁志. 茶渣双轴搅拌干燥机结构优化及含水率模拟分析[J]. 中国农业科技导报, 2025, 27(4): 120-132.

Figures/Tables 18

Fig. 1 Three dimensional model of dual axis stirring dryerNote：1—Mixing shaft； 2—Air inlet； 3—Feed inlet； 4—Guide grille； 5—Air outlet； 6—Machine wall； 7—Discharge port.

Fig. 2 Fluid calculation domain of dual axis stirring dryer

Fig. 3 Grid model of dual axis stirring dryer

Table 1 The main parameters of numerical simulation

参数 Parameter	数值 Value
空气进口温度 Temperature at air inlet /℃	200~500
空气进口速度 Velocity at air inlet/（m·s^-1）	1
出口类型 Type of outlet	压力出口Pressure outlet
出口压力 Pressure of outlet/Pa	103 125
物料进口温度 Temperature at materiel inlet/℃	20
主轴转速 Spindle speed/（r·min^-1）	300~600
物料进口含水率 Moisture content of material inlet/%	84
物料出口含水率 Moisture content of material outlet/%	<14
物料密度 Material density/ （kg·m^-2）	367
绝干物料比热容 Specific heat capacity of absolute dry material/（kg·K^-1）	1.63^［21］
物料导热系数 Material thermal conductivity/（W·m^-1·K^-1）	0.0362^［22］

Fig. 4 Diversion grille structureNote：1—Guide plate； 2—Diversion hole.

Fig. 5 Size of air deflector grille

Fig. 6 Location and layout of monitoring points

Fig.7 Velocity cloud image of cross section X=0 at different angles of the flow grid

Fig. 8 Temperature cloud image of cross section X=0 at different angles of diversion grilles

Fig. 9 Average temperature of dryer under different grille angles

Table 2 Layout of each diversion grid

格栅数量 Number of grilles	格栅间距 Spacing of the grilles/mm
0	—
1	—
2	2 060
3	2 065
4	1 350
5	1 030
6	820

Fig. 10 Velocity cloud image of cross section X=0 under different diversion grid arrangement

Fig. 11 Temperature cloud image of cross section X=0 under different diversion grid arrangement

Fig. 12 Average temperature in dryer under different number of grilles

Fig. 13 Cloud map of material moisture content at the discharge interface Z=9 500 mm of the dryer under different hot air temperatures

Fig.14 Water content of outlet section under different hot air temperatures

Fig. 15 Cloud map of material moisture content at the discharge interface Z=9 500 mm of the dryer under different hot air temperatures

Fig. 16 Water content of outlet section under different spindle speeds

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