分形翅片相变传热特性及优化

许泽; 邢玉明; 殷健宝; 侯煦; 王仕淞

doi:10.13224/j.cnki.jasp.20230454

分形翅片相变传热特性及优化

doi: 10.13224/j.cnki.jasp.20230454

许泽^1,,
邢玉明^1,*,,
殷健宝¹,
侯煦¹,
王仕淞²

1.
北京航空航天大学航空科学与工程学院，北京 100083
2.
北京航天长征飞行器研究所，北京 100076

详细信息

作者简介:
许泽（1999-），男，硕士生，主要从事相变材料、换热器和蓄热体方面研究。E-mail：yxdxz@buaa.edu.cn

通讯作者:
邢玉明（1966-），男，教授，博士生导师，博士，主要研究方向为制冷及低温工程。E-mail：补充

中图分类号: V259；TK124
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出版历程
- 收稿日期: 2023-07-14
- 网络出版日期: 2024-06-05

Heat transfer characteristics and optimization of fractal fin during phase change

1.
School of Aeronautics Science and Engineering，Beihang University，Beijing 100083，China
2.
Beijing Institute of Space Long March Vehicle，Beijing 100076，China

摘要

摘要:
相变材料的低导热率制约了潜热储热系统的效率，提出了一种新型分形翅片改善潜热储热系统的相变传热特性。建立二维管壳潜热储热系统模型，利用焓-多孔介质法进行瞬态模拟，研究了嵌入分形翅片对系统凝固性能的影响，分形翅片长度比和分支角对凝固过程影响显著，分形翅片加快了相变材料的凝固，使系统温度分布更加均匀。与直翅片相比，分形翅片显著强化了系统的换热性能，采用人工神经网络对数据进行拟合，以液相百分数为优化目标，通过遗传算法得到优化后的翅片结构:最佳长度比为1.425，两分支角分别为50°和30°；优化后分形翅片系统的凝固时间比直翅片系统减少76.9%。对分形翅片参数进行了敏感度分析，结果表明长度比对系统凝固时间的影响更大，1级分支角次之，更应关注这两个参数的变化对凝固时间的影响。
- 相变储能换热器 /
- 神经网络 /
- 遗传算法 /
- 分形理论 /
- 敏感度分析
Abstract:
The low efficiency of the latent heat storage system attributed to low thermal conductivity of phase change material. A novel fractal fin to strengthen the solidification property of latent heat storage(LHS) units was proposed. Firstly, the enthalpy-porosity technique was utilized to build a transient two-dimensional model of shell and tube LHS system. The results demonstrated that the length ratio and branch angle played an important role in solidification performance. The fractal structure improved the solidification speed and led to uniform temperature. The fractal fin displayed a remarkable heat transfer enhancement compared with a conventional fin. The structure optimization of fractal fin was conducted for solidification enhancement by artificial neural network and Genetic Algorithm. The optimized fin structure was obtained by genetic algorithm: the optimal fin length ratio was 1.425 and the two branch angles were 50° and 30° respectively, the solidification time of the LHS unit with fractal fin after optimization was 76.9% shorter than the system with conventional fin. The sensitive analysis was applied to explore the effect of the parameters of fractal fin on solidification time. The results indicated that the solidification time of the system was more affected by the length ratio, followed by the first-order branch Angle. More attention should be paid to the effect of the changes of these two parameters.
- phase change exchanger /
- artificial neural network /
- genetic algorithm /
- fractal theory /
- sensitive analysis.

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图 1 树状分形翅片的构建

Figure 1. Construction of fractal fin

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图 2 几何模型示意图

Figure 2. Schematic diagram of geometric model

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图 3 数值模拟与文献结果对比

Figure 3. Comparison between numerical simulation and literature result

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图 4 网格无关性和时间步长无关性分析

Figure 4. Grid independence and time step independence analysis

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图 5 计算域

Figure 5. Computational domain

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图 6 神经网络结构图

Figure 6. Structure of the neural network

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图 7 拟合结果

Figure 7. the fitting result

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图 8 遗传算法流程图

Figure 8. process of genetic algorithm

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图 9 分形翅片与直翅片液相及温度分布Fig.9solid phase and temperature distribution of fractal fin and radial fin

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图 10 分形翅片与直翅片液相百分数及温度变化曲线

Figure 10. liquid fraction and temperature of fractal fin and radial fin

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图 11 分形翅片与直翅片温度方差对比

Figure 11. the comparison diagram of temperature variance between fractal fin and radial fin

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图 12 翅片参数对熔化时间的一阶灵敏度

Figure 12. First order sensitivity index of fin parameters to the solidification time

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图 13 翅片参数对凝固时间的二阶灵敏度

Figure 13. Second order sensitivity index of fin parameters to the solidification time

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表 1 材料的热物理性质

Table 1. Thermophysical properties of materials

热物性参数	月桂酸	铝合金
密度/（kg/m³）	869	2703
比热容（J/（kg∙K））	1760（固）/2150（液）	963
熔点/（K）	315～317
潜热/（kJ/kg）	178.7
导热系数/（W/（m∙K））	0.22（固）/0.16（液）	180
黏度/（Pa∙s）	0.001

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表 2 翅片参数对凝固时间的一阶灵敏度

Table 2. First order sensitivity of fin parameters to solidification time

翅片参数	主效应指标	总效应指标
长度比	0.185	0.675 9
0级分支角	0.076 4	0.642 9
1级分支角	0.143 1	0.480 6

下载: 导出CSV

参考文献(18)

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