Heat transfer performance in stirred tank with four-pitched blade with stabilizing fins-Rushton combined impellers

doi:10.16085/j.issn.1000-6613.2022-2289

Abstract

Abstract:

The heat transfer performance of a stirred tank with the four-pitched blade with stabilizing fins-Rushton combined impellers and helical coils was studied based on the combination of computational fluid dynamics (CFD) simulation and heat transfer experiments. The flow distribution, temperature distribution, temperature boundary layer and Nusselt number outside the coil were obtained. The results showed that the error of temperature between experimental measurement and numerical simulation was less than 4K. The high temperature area in the stirred tank was located in the circulating large eddy current area at the coil, and the maximum temperature difference was kept within 3K. The stabilizer fins could improve liquid axial-flow performance and make the temperature distribution of the stirred tank more uniform. The average temperature boundary layer thickness of XZ plane and YZ plane outside the inner coil was 3.01mm and 2.70mm, respectively. According to experimental data and numerical simulation, it was found that the order of influence of different factors on the Nusselt number outside the inner coil was as follows: viscosity of the mixing medium>mixing speed>blade spacing>distance from the bottom. The maximum error of Nusselt number between experiment and simulation was 14.56%, and the minimum error was 4.23%, which verified the feasibility of numerical simulation well. The research results can provide a reference for the application of the four-pitched blade with stabilizing fins-Rushton combined impellers in the practical industry.

Key words: four-pitched blade with stabilizing fins-Rushton combined impellers, heat transfer, temperature distribution, temperature boundary layer, Nusselt number

摘要：

基于计算流体力学（CFD）模拟与传热实验相结合的方法，对带稳定翼四斜叶-Rushton组合桨在内加热盘管搅拌釜的传热性能进行研究，获得搅拌釜内的流场分布、温度分布、温度边界层和盘管外侧的努塞尔数。研究表明，实验与数值模拟的温度误差在4K以内。搅拌釜内高温区位于盘管处循环大涡流区，釜内最大温差保持在3K以内。稳定翼可提高流体轴向循环性能，能够使搅拌釜内温度分布更加均匀。内盘管外侧XZ平面和YZ平面的平均温度边界层厚度分别为3.01mm和2.70mm。通过实验与数值模拟方法得到不同因素对内盘管外侧努塞尔数的影响，其顺序为：搅拌介质黏度>搅拌转速>桨叶间距>离底距离，实验与模拟的努塞尔数最大误差为14.56%，最小误差为4.23%，实验结果很好地验证了数值模拟的可行性。研究结果可为带稳定翼四斜叶-Rushton组合桨应用于实际工业中提供参考。

关键词: 带稳定翼四斜叶-Rushton组合桨, 传热性能, 温度分布, 温度边界层, 努塞尔数

CLC Number:

TQ051

ZHAO Jinming, QIN Xiaobo, XU Yang, SHI Yihang, ZHOU Yongjun. Heat transfer performance in stirred tank with four-pitched blade with stabilizing fins-Rushton combined impellers[J]. Chemical Industry and Engineering Progress, 2023, 42(11): 5602-5611.

赵金明, 秦晓波, 徐阳, 史亦航, 周勇军. 带稳定翼四斜叶-Rushton组合桨搅拌釜内传热性能[J]. 化工进展, 2023, 42(11): 5602-5611.

Figures/Tables 16

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测温点	x	y	z
T₁	-240	10	450
T₂	-155	0	400
T₃	-155	0	350
T₄	-155	0	300
T₅	-155	0	250
T₆	-240	10	200
T₇	165	0	550
T₈	165	0	500
T₉	165	0	450
T₁₀	185	50	324
T₁₁	205	0	324
T₁₂	225	-50	324
T₁₃	165	0	201
T₁₄	165	0	151
T₁₅	165	0	101

测温点	x	y	z
T₁	-240	10	450
T₂	-155	0	400
T₃	-155	0	350
T₄	-155	0	300
T₅	-155	0	250
T₆	-240	10	200
T₇	165	0	550
T₈	165	0	500
T₉	165	0	450
T₁₀	185	50	324
T₁₁	205	0	324
T₁₂	225	-50	324
T₁₃	165	0	201
T₁₄	165	0	151
T₁₅	165	0	101

编号	μ/mPa·s	ρ/kg·m^-3	λ/W·m^-1·K^-1	c_p /kJ·kg^-1·K^-1	Pr
1	7.3	1010	0.64	4.180	4.77
2	14.6	1010	0.64	4.180	9.54
3	29.2	1010	0.64	4.180	19.07

编号	μ/mPa·s	ρ/kg·m^-3	λ/W·m^-1·K^-1	c_p /kJ·kg^-1·K^-1	Pr
1	7.3	1010	0.64	4.180	4.77
2	14.6	1010	0.64	4.180	9.54
3	29.2	1010	0.64	4.180	19.07

内盘管标记		XZ截面温度边界层厚度/mm	YZ截面温度边界层厚度/mm
1	a₁	4.78	4.89
	a₂	3.67	1.25
2	b₁	2.41	3.67
	b₂	1.22	2.45
3	c₁	2.43	2.47
	c₂	3.65	2.46
4	d₁	2.47	2.47
	d₂	4.66	2.46
5	e₁	1.25	1.23
	e₂	3.53	3.67
温度层平均厚度		3.01	2.70