基于微通道液氮换热的脉冲磁体快速冷却方法研究

何勇; 孟昭男; 张鹏; 孙衢骎; 周星健

doi:10.11884/HPLPB202234.220069

基于微通道液氮换热的脉冲磁体快速冷却方法研究

doi: 10.11884/HPLPB202234.220069

1.
中国工程物理研究院流体物理研究所，四川绵阳 621900
2.
上海交通大学制冷与低温工程研究所，上海 200240
3.
武汉第二舰船设计研究院，武汉 430205

详细信息

作者简介:
何　勇，4045604@qq.com

中图分类号: TL331
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- 被引次数: 0
出版历程
- 收稿日期: 2022-03-14
- 修回日期: 2022-09-05
- 网络出版日期: 2022-09-05
- 刊出日期: 2022-09-20

Investigation on fast cooling method for pulsed magnet based on heat transfer of flowing liquid nitrogen in micro-channels

1.
Institute of Fluid Physics, CAEP, Mianyang 621900, China
2.
Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240, China
3.
Wuhan Second Ship Design and Research Institute, Wuhan 430205, China

摘要

摘要: 影响脉冲磁体重频运行能力的关键因素是磁体的冷却速度。提出了一种脉冲磁体快速冷却方法：在磁体导体内开微小通道，在通道内注入液氮，通过增大导体与液氮之间的直接接触面积（换热面积）、液氮单相流动换热、液氮流动沸腾换热这三个途径来大幅提高导体的冷却速度，与此同时尽可能减小对脉冲磁体性能（磁场强度、脉宽和内直径）的影响。阐述了基于微通道内液氮流动、沸腾换热的脉冲磁体快速冷却方法的原理，开展了数值模拟和验证性试验，结果表明，对于25 T的20 mm口径脉冲磁体，采用快速冷却方法，30 s即可冷却至初始温度，为磁体仅浸泡在液氮中的冷却时间（600 s）的5%，冷却速度提高了19倍。
- 脉冲磁体 /
- 重频运行能力 /
- 微通道 /
- 沸腾换热 /
- 对流换热
Abstract: The cooling-down time limits the capability of repetitive operation of the pulsed magnet. A fast cooling method for the pulsed magnet based on heat transfer of flowing liquid nitrogen (LN₂) in micro-channels formed inside the conductors of the pulsed magnet is presented. The large amount of heat produced during discharging of the pulsed magnet can be quickly dissipated by LN₂ inside the micro-channels through the enlarged contact areas between LN₂ and conductors, by single-phase LN₂ flow and/or flow boiling. Furthermore, the impacts of the micro-channels on the performances (strengthening of the magnetic field, pulse duration and diameter of inner bore) can be tolerable. The principles of fast cooling method based on single-phase LN₂ flow or flow boiling are elucidated. Numerical simulations and validation experiments of the fast cooling method indicate that pulsed magnet with inner bore diameter of 20 mm and magnetic field of 25 T can be cooled down in 30 s. The cooling speed of the pulsed magnet of the fast cooling method is increased by about 19 times compared with the conventional cooling method (600 s) where the pulsed magnet is simply immersed in LN₂.
- pulsed magnet /
- capability of repetitive operation /
- micro-channels /
- flow boiling /
- forced convection

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图 1 快速冷却脉冲磁体示意图

Figure 1. Structure of the designed magnet

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图 2 初始温度为77 K时，放电结束时磁体的温度分布

Figure 2. Temperature distribution of the magnet at the end of discharge, initial temperature is 77 K

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图 3 放电结束时各层导体沉积的热量

Figure 3. Deposited energy for each layer conductor of the magnet at the end of discharge

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图 4 磁体导体平均温度随时间的变化

Figure 4. Temporal evolution of average temperature of the magnet conductor during intermittent running process

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图 5 1~20层导体冷却情况计算模型

Figure 5. Model for the cooling processing simulation for the designed magnet (1^st～20^th layer)

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图 6 1 s加热(功率80 kW)后，1～20层导体温度分布

Figure 6. Temperature of the 1^st~20^th layer after 1 s heating with 80 kW

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图 7 磁体导体（1～20层模型）冷却过程

Figure 7. Cooling processing of magnet conductors (1^st~20^th layer model)

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图 8 1 s加热(功率12 kW)后，8～9层导体温度分布

Figure 8. Temperature of the 8^th~9^th layer after 1 s heating with 12 kW

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图 9 磁体导体(8～9层模型)冷却过程

Figure 9. Cooling processing of magnet conductors (8^th~9^th layer model)

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图 10 缩比型脉冲磁体

Figure 10. Scaled pulsed magnet

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图 11 缩比型脉冲磁体放电电流波形

Figure 11. Discharged current of the scaled pulsed magnet

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图 12 三种不同冷却方式下，磁体冷却过程

Figure 12. Cooling processing of the magnet with 3 kinds of cooling method

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表 1 铜和环氧树脂材料在不同温度下的热物性

Table 1. Thermal properties of copper and epoxy under different temperatures

thermal property/K	density of cooper/ (kg·m⁻³)	specific heat capacity of cooper/(J·kg⁻¹·K⁻¹)	thermal conductivity of cooper/(W·m⁻²·K⁻¹)	density of composite material/(kg·m⁻³)	specific heat capacity of composite material/(J·kg⁻¹·K⁻¹)	thermal conductivity of composite material/(W·m⁻²·K⁻¹)
95	8978	199.13	579.14	1560	246.40	0.22
77	8978	245.20	490.34	1560	304.00	0.29
135	8978	307.03	440.22	1560	432.00

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参考文献(14)

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