高温超导电机冷却系统中过冷氮的传热与流动研究
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摘要
随着高温超导技术的不断进步,超导临界温度已升至液氮温区,液氮温度下的临界电流密度已经达到实际应用水平。作为高温超导的研究热点之一,高温超导中过冷液氮的研究已经成为高温超导技术的一个重要研究方向。本文研究轴—径向磁通高温全超导低速同步电机冷却系统中过冷液氮的传热与流动,为电机冷却系统的设计提供理论依据。
本文以轴—径向磁通高温全超导低速同步电机为研究对象,首先根据高温超导电机的组成结构,运用理论公式计算出高温超导电机冷负荷。计算四线并绕情况下液氮循环流量、液氮循环流速及管道直径,对过冷液氮及线圈进行热—流体耦合场分析,得到磁体的稳态温度分布。为了简化结构,本文对液氮进出口同侧的情况进行分析,并与进出口异侧进行对比,发现改变进出口对温度影响很小,最终选择进出口同侧的方案。
低温换热器是过冷液氮低温系统的关键设备之一。本文选择两台AL600制冷机的冷却方案,运用理论公式求得到管道的换热系数,模拟出过冷换热器内液氮温度场。对过冷换热器进行设计,分析浸泡在液氮中的冷头高度对换热面积的影响以及冷头换热器上固着冷却板表面对有效热传导系数、传热率的影响。本文用FLUENT软件对换热器热-流体场进行了仿真,结果表明在假设液氮罐内温度均匀分布的条件下,管内速度保持在1.53m/s-1.54m/s之间,保持绕管换热器的换热面积和高度不变,仅改变盘管圈数不影响温度变化情况。当液罐内液氮温度为64.6K时,管内液氮温度在65K以下。
在高温超导电机低温冷却系统中,过冷氮在流动过程中会由于管道阻力作用产生压力损失,需要计算出总压力损失,并对管内压力损失进行补偿。研究了弯管压力损失,模拟了90°,75°,60°,45°四种角度下的压力损失和速度变化情况,得出当弯管角度越小压力损失越小的结论,但当角度变化到一定程度之后,减小角度对于降低压力损失的影响较小。
As the high temperature superconducting (HTS) technology progresses, the critical superconducting temperature rises from the liquid helium temperature to the liquid nitrogen temperature, and the critical current density in liquid nitrogen temperature range has reached the level of practical application. As one focus of the HTS researches, the research of sub-cooled liquid nitrogen in HTS motor has become an important research direction. The thesis researches heat transfer and flow in sub-cooled liquid nitrogen of cooling system in axial-radial flux all HTS low speed synchronous motor, which provides theoretical principle for the design of the motor’s cryogenic cooling system.
In this thesis, the HTS motor cooling load is calculated based on the structure of HTS motor. For the four-lane paralleled condition, the liquid nitrogen’s circulating flow, velocity and the diameter of the pipe are calculated, and the thermal-fluid coupling analysis on the coils and sub-cooled liquid nitrogen of the cooling flow channel is carried out, which obtains the steady temperature distribution. To simplify the structure, the schemes of import and export in the homonymy, and on the different sides are compared, the solution of import and export in the homonymy is adopted finally. Cryogenic heat exchanger is one of the key equipments in sub-cooled liquid nitrogen cryogenic cooling system. Two AL600 cryorefrigerators are used to cool the HTS motor. The heat transfer coefficient is calculated using the theoretical equation,and the liquid nitrogen temperature field in sub-cooled heat exchanger is simulated. The effects of the cool head’s height to heat exchange area and extended surface from a cryocooler to the effective heat transfer coefficient and coefficient of overall heat transmission are studied in detail. The simulation result using FLUENT software shows that the velocity value is 1.53m/s-1.54m/s. Temperature reminds unchanged when number of turns is changed but the heat exchange area and height of sub-cooled exchanger is unchanged. Assume the distribution of temperature is uniformity in the fluid reservoir, when the temperature in the fluid reservoir is 64.6K, the temperature of liquid nitrogen in the pipe is below 65K.
In the HTS motor’s cryogenic cooling system, there is pressure drop when liquid nitrogen flow in the pipe. In order to keep the flow rate steadily, it needs to calculate overall pressure loss to compensate the pressure drop in the pipe. Research on the pressure drop in the siphon pipe, the pressure drop and velocity distributions for different angles(90°,60°,45°, 75°) are simulated, the analysis result shows that when the angles decrease, the pressure drop becomes small, but difference value of it becomes smallbetween two low-angles .
本文以轴—径向磁通高温全超导低速同步电机为研究对象,首先根据高温超导电机的组成结构,运用理论公式计算出高温超导电机冷负荷。计算四线并绕情况下液氮循环流量、液氮循环流速及管道直径,对过冷液氮及线圈进行热—流体耦合场分析,得到磁体的稳态温度分布。为了简化结构,本文对液氮进出口同侧的情况进行分析,并与进出口异侧进行对比,发现改变进出口对温度影响很小,最终选择进出口同侧的方案。
低温换热器是过冷液氮低温系统的关键设备之一。本文选择两台AL600制冷机的冷却方案,运用理论公式求得到管道的换热系数,模拟出过冷换热器内液氮温度场。对过冷换热器进行设计,分析浸泡在液氮中的冷头高度对换热面积的影响以及冷头换热器上固着冷却板表面对有效热传导系数、传热率的影响。本文用FLUENT软件对换热器热-流体场进行了仿真,结果表明在假设液氮罐内温度均匀分布的条件下,管内速度保持在1.53m/s-1.54m/s之间,保持绕管换热器的换热面积和高度不变,仅改变盘管圈数不影响温度变化情况。当液罐内液氮温度为64.6K时,管内液氮温度在65K以下。
在高温超导电机低温冷却系统中,过冷氮在流动过程中会由于管道阻力作用产生压力损失,需要计算出总压力损失,并对管内压力损失进行补偿。研究了弯管压力损失,模拟了90°,75°,60°,45°四种角度下的压力损失和速度变化情况,得出当弯管角度越小压力损失越小的结论,但当角度变化到一定程度之后,减小角度对于降低压力损失的影响较小。
As the high temperature superconducting (HTS) technology progresses, the critical superconducting temperature rises from the liquid helium temperature to the liquid nitrogen temperature, and the critical current density in liquid nitrogen temperature range has reached the level of practical application. As one focus of the HTS researches, the research of sub-cooled liquid nitrogen in HTS motor has become an important research direction. The thesis researches heat transfer and flow in sub-cooled liquid nitrogen of cooling system in axial-radial flux all HTS low speed synchronous motor, which provides theoretical principle for the design of the motor’s cryogenic cooling system.
In this thesis, the HTS motor cooling load is calculated based on the structure of HTS motor. For the four-lane paralleled condition, the liquid nitrogen’s circulating flow, velocity and the diameter of the pipe are calculated, and the thermal-fluid coupling analysis on the coils and sub-cooled liquid nitrogen of the cooling flow channel is carried out, which obtains the steady temperature distribution. To simplify the structure, the schemes of import and export in the homonymy, and on the different sides are compared, the solution of import and export in the homonymy is adopted finally. Cryogenic heat exchanger is one of the key equipments in sub-cooled liquid nitrogen cryogenic cooling system. Two AL600 cryorefrigerators are used to cool the HTS motor. The heat transfer coefficient is calculated using the theoretical equation,and the liquid nitrogen temperature field in sub-cooled heat exchanger is simulated. The effects of the cool head’s height to heat exchange area and extended surface from a cryocooler to the effective heat transfer coefficient and coefficient of overall heat transmission are studied in detail. The simulation result using FLUENT software shows that the velocity value is 1.53m/s-1.54m/s. Temperature reminds unchanged when number of turns is changed but the heat exchange area and height of sub-cooled exchanger is unchanged. Assume the distribution of temperature is uniformity in the fluid reservoir, when the temperature in the fluid reservoir is 64.6K, the temperature of liquid nitrogen in the pipe is below 65K.
In the HTS motor’s cryogenic cooling system, there is pressure drop when liquid nitrogen flow in the pipe. In order to keep the flow rate steadily, it needs to calculate overall pressure loss to compensate the pressure drop in the pipe. Research on the pressure drop in the siphon pipe, the pressure drop and velocity distributions for different angles(90°,60°,45°, 75°) are simulated, the analysis result shows that when the angles decrease, the pressure drop becomes small, but difference value of it becomes smallbetween two low-angles .
引文
1严仲明等.导材料在电工领域的应用.电工材料, 2007, 2 :23~25
2郑陆海,金建勋.高温超导电机的发展与研究现状.电机与控制应用. 2007, 34(3): 1~6
3唐绍栋.温超导交流同步电动机—一种理想的舰船推进动力设备.船电技术. 2004 :4~8
4 S. S. Kalsi.HTS ship propulsion motors. Power Engineering Society General Meeting. 2004. IEEE. 2004, 2 :1~5
5 W. R. BUMBY.超导旋转电机.田成文等译.西安交通大学出版社. 1985 :1~4
6 S. S. Kalsi, H. Takesue, R. D. Blaugher. Development of status of rotating machines employing superconducting field windings. Proceeding of the IEEE. 2004, 92(10) :1688~1740
7陈彪等.高温超导电机的冷却技术综述. Cryogenics. 2007,5 :159~163
8 B. Chen, G.. B. Gu, Zhang G Q, et al. Alysis and simulation of cooling system in High Temperature Superconducting Synchronous Machines. IEEE Transactions on Applied Superconductivity, 2007, 17 (2) :1557-1560
9 Ho-Myung Chang, Min-Jee Kim, Jung Wook Sim, et al. A Compact Cryocooling System with Subcooled Liquid Nitrogen for Small HTS Magnets. Cryogenics. 2007, 4(9) :1~5
10 H. K. Kang, H. J. Kim, D. K. Bae, et al. Sub-cooled nitrogen cryogenic cooling for superconducting fault current limiter by using GM-cryocooler. Cryogenic. 2005, 45 :65~69
11 Choi YS. Cryogenic cooling system by natural convetion of subcooled liquid nitrogen for HTS transformers. PhD thesis, Florida State University, 2004
12陈国邦等.氦氮混合工质脉管制冷中的温度平台研究.低温与特气. 2001, 6 :6~10
13王建青等. ITER过渡馈线辅助支撑结构设计及传热计算.原子能科学技术. 2009, 8 :716~719
14 J. G. Bednorz and K. A. Miiller, Possible high Temperature Superconductivity in the Ba-La-Cu-O system, Z. Phys. 1987, 64B :189-193.
15张庆川.液氮超导发电机的探讨.电机技术. 1997 :36~37
16 T. Ishigohka. A Feasibility Study on a World-Wide-Scale Superconducting PowerTransmission System. IEEE Transactions on Applied Superconductivity. 1995 :949~952
17 S. Fuchino, M. Furse, N. Higuchi, M. Okano, and K. Agatsuma. Cooling Characteristics in Long Channels with Sub-Cooled Nitrogen. Advances in Cryogenic Engineering. American Institute of Cryogenics. 2007
18 Mitsuho Furuse, Shuichiro Fuchino, Noboru Higuchi. Counter flow cooling characteristics with liquid nitrogen for superconducting power cables. Cryogenics. 2002, 42 :405~409
19 Chang Ho Lee, Chun Dong Kim, Kyun Seok Kim, et al. Performance of heat transfer and pressure drop in superconducting cable former. Cryogenics. 2003, 43 :583~588
20 Huo H K, Xu Z, et al. Technical analysis on the application of HTS bulk in“permanent magnet”motor. IEEE Transaction on Applied Superconductivity. 2005,15(2):3172~3175
21 H.-M. Chang, Y. S. Choi, and S. W. Van Sciver. Optimization of operating temperature in cryocooled HTS magnets for compactness and efficiency. Cryogenics. 2002, 42 :787~794
22林良真.我国超导技术研究进展及展望.电工技术学报. 2005, Vol.20, No.1: 1~5
23吴远宽.液氮冷却技术在超导磁体中的应用.真空与低温. 1997 :26~28
24毕延芳等. 35kV/2kA高温超导电力电缆终端.低温物理学报. 2003, 25: 525~529
25施锦,丁怀况,席海霞,侯波.高温超导电缆液氮流道试验装置的设计计算.低温与超导. 2003 :1~3
26范宇峰,龚领会,徐向东,李来风,张亮,肖立业10米10.5kV/1.5kA三相交流高温超导电缆液氮冷却系统的设计.低温工程. 2004 :26~28
27孙玉凤,张鹏,王如竹,徐烈.高温超导电缆用波纹管内液氮流动特性的数值研究.低温与超导. 2002 :376~379
28 Suzuki Y, Yoshida S, Kamioka Y. Subcooled liquid nitrogen refrigerator for HTS power systems. Cryogenics. 2003, 43 :597~602
29 Y. J. Tang, J. D. Li, M. Y. Ye, et al. Applied Superconducting Technique in the Future Electric Power System. Automation of Electric Power Systems. 2001, 25(2) :70~75
30 H. F. Zhou, J. D. Li, Y. J. Tang, et al. Development of High Temperature Superconducting Cable. Automation of Electric Power Systems. 2001,25(8) :71~74
31 Y. Elkassabgi, J. H. Lienhard. Influences of subcooling on burnout of horizontal cylindrical heaters. Journal of Heat Transfer. 1988, 110 :479~486
32 H. J. Chad, F. S. Rich. Design and fabrication of HTS field coils for a demonstration DC motor. IEEE Trans on Applied Superconductivity. 1993, 3(1) :373~376
33张国民.高温超导带材及线圈的交流损失.博士学位论文.北京,中国科学院电工研究所, 2003
34 M. A. Green. Heat Transfer through a Multilayer Insulation System as a Function of Pressure in the Cryostat Vacuum Space. Advanced in Cryogenics Engineering. 1998, 43 :1313~1318
35王惠龄,汪京荣.超导应用低温技术.北京:国防工业出版社, 2008, chapter 9
36化学工业部第四设计院主编.深冷手册(下册).北京:化学工业出版社, 1979, 444
37杨世铭,陶文铨.传热学.北京,高等教育出版社. 2003 :130~132
38 V. Yakhot, S. A. Orszag. Renormalization group analysis of turbulence. Journal of Scientific Comptuing. 1986, (1) :3~5
39 A. Robinson. Nonstandard Analysis. Amsterdam :North-Holland, 1974, Chapter 1, 2, 10
40 J. Lehtonen, R. Mikkonen, J. Paasi, et al. Effective thermal conductivity in HTS coils. Cryogenics. 2000,(42):245~249
41 Chang HM, Choi YS, Van Sciver SW, Choi KD. Cryogenic cooling system of HTS transformers by natural convetion of subcooled liquid nitrogen. Cryogenics 2003, 43 :589~596
42杨世铭,陶文铨.传热学.北京,高等教育出版社. 2003 :162~168
43 R. F. Barron. Cryogenic Heat Transfer. Edwards Brothers, Ann Arbor, M1. 1999 :100~102
44 Yeon Suk Choi, Ho-Myung Chang, Steven W. Van Sciver. Performance of extended surface from a crylcooler for subcooling liquid nitrogen by natural convection. Cryogenics. 2006, 46 :396~402
45惠荣娜.通风管道局部构件阻力系数及减阻方法研究.硕士论文. 2007.6 : 6~15
46汪兴华,吴德怀.风管标准弯头和变径管的局部阻力试验.暖通空调. 1981 :22
47李涛.通风管道局部构件阻力系数的实验和数值模拟研究.西安建筑科技大学硕士学位论文. 2005
48 Shamir, C. D. D. Howard. Water distribution system analysis. J. H. yd. Div., Proc. ASCE. 1988, 94(1) :219~234
49 Pretot S, Zeghmati B, Palec GL. Theoretical and experimental study of natural convection on a horizontal plate. Appl Thermal Eng 2000, 20 :873~891
50王桂秋.管道系统中局部阻力计算.管道技术与设备. 2000. No.2 :5~8
51姜小放,曹西京,司震鹏. FLUENT技术在工业管道设计中的应用.化工设备与管道. 2009, 46(5) :46~47
2郑陆海,金建勋.高温超导电机的发展与研究现状.电机与控制应用. 2007, 34(3): 1~6
3唐绍栋.温超导交流同步电动机—一种理想的舰船推进动力设备.船电技术. 2004 :4~8
4 S. S. Kalsi.HTS ship propulsion motors. Power Engineering Society General Meeting. 2004. IEEE. 2004, 2 :1~5
5 W. R. BUMBY.超导旋转电机.田成文等译.西安交通大学出版社. 1985 :1~4
6 S. S. Kalsi, H. Takesue, R. D. Blaugher. Development of status of rotating machines employing superconducting field windings. Proceeding of the IEEE. 2004, 92(10) :1688~1740
7陈彪等.高温超导电机的冷却技术综述. Cryogenics. 2007,5 :159~163
8 B. Chen, G.. B. Gu, Zhang G Q, et al. Alysis and simulation of cooling system in High Temperature Superconducting Synchronous Machines. IEEE Transactions on Applied Superconductivity, 2007, 17 (2) :1557-1560
9 Ho-Myung Chang, Min-Jee Kim, Jung Wook Sim, et al. A Compact Cryocooling System with Subcooled Liquid Nitrogen for Small HTS Magnets. Cryogenics. 2007, 4(9) :1~5
10 H. K. Kang, H. J. Kim, D. K. Bae, et al. Sub-cooled nitrogen cryogenic cooling for superconducting fault current limiter by using GM-cryocooler. Cryogenic. 2005, 45 :65~69
11 Choi YS. Cryogenic cooling system by natural convetion of subcooled liquid nitrogen for HTS transformers. PhD thesis, Florida State University, 2004
12陈国邦等.氦氮混合工质脉管制冷中的温度平台研究.低温与特气. 2001, 6 :6~10
13王建青等. ITER过渡馈线辅助支撑结构设计及传热计算.原子能科学技术. 2009, 8 :716~719
14 J. G. Bednorz and K. A. Miiller, Possible high Temperature Superconductivity in the Ba-La-Cu-O system, Z. Phys. 1987, 64B :189-193.
15张庆川.液氮超导发电机的探讨.电机技术. 1997 :36~37
16 T. Ishigohka. A Feasibility Study on a World-Wide-Scale Superconducting PowerTransmission System. IEEE Transactions on Applied Superconductivity. 1995 :949~952
17 S. Fuchino, M. Furse, N. Higuchi, M. Okano, and K. Agatsuma. Cooling Characteristics in Long Channels with Sub-Cooled Nitrogen. Advances in Cryogenic Engineering. American Institute of Cryogenics. 2007
18 Mitsuho Furuse, Shuichiro Fuchino, Noboru Higuchi. Counter flow cooling characteristics with liquid nitrogen for superconducting power cables. Cryogenics. 2002, 42 :405~409
19 Chang Ho Lee, Chun Dong Kim, Kyun Seok Kim, et al. Performance of heat transfer and pressure drop in superconducting cable former. Cryogenics. 2003, 43 :583~588
20 Huo H K, Xu Z, et al. Technical analysis on the application of HTS bulk in“permanent magnet”motor. IEEE Transaction on Applied Superconductivity. 2005,15(2):3172~3175
21 H.-M. Chang, Y. S. Choi, and S. W. Van Sciver. Optimization of operating temperature in cryocooled HTS magnets for compactness and efficiency. Cryogenics. 2002, 42 :787~794
22林良真.我国超导技术研究进展及展望.电工技术学报. 2005, Vol.20, No.1: 1~5
23吴远宽.液氮冷却技术在超导磁体中的应用.真空与低温. 1997 :26~28
24毕延芳等. 35kV/2kA高温超导电力电缆终端.低温物理学报. 2003, 25: 525~529
25施锦,丁怀况,席海霞,侯波.高温超导电缆液氮流道试验装置的设计计算.低温与超导. 2003 :1~3
26范宇峰,龚领会,徐向东,李来风,张亮,肖立业10米10.5kV/1.5kA三相交流高温超导电缆液氮冷却系统的设计.低温工程. 2004 :26~28
27孙玉凤,张鹏,王如竹,徐烈.高温超导电缆用波纹管内液氮流动特性的数值研究.低温与超导. 2002 :376~379
28 Suzuki Y, Yoshida S, Kamioka Y. Subcooled liquid nitrogen refrigerator for HTS power systems. Cryogenics. 2003, 43 :597~602
29 Y. J. Tang, J. D. Li, M. Y. Ye, et al. Applied Superconducting Technique in the Future Electric Power System. Automation of Electric Power Systems. 2001, 25(2) :70~75
30 H. F. Zhou, J. D. Li, Y. J. Tang, et al. Development of High Temperature Superconducting Cable. Automation of Electric Power Systems. 2001,25(8) :71~74
31 Y. Elkassabgi, J. H. Lienhard. Influences of subcooling on burnout of horizontal cylindrical heaters. Journal of Heat Transfer. 1988, 110 :479~486
32 H. J. Chad, F. S. Rich. Design and fabrication of HTS field coils for a demonstration DC motor. IEEE Trans on Applied Superconductivity. 1993, 3(1) :373~376
33张国民.高温超导带材及线圈的交流损失.博士学位论文.北京,中国科学院电工研究所, 2003
34 M. A. Green. Heat Transfer through a Multilayer Insulation System as a Function of Pressure in the Cryostat Vacuum Space. Advanced in Cryogenics Engineering. 1998, 43 :1313~1318
35王惠龄,汪京荣.超导应用低温技术.北京:国防工业出版社, 2008, chapter 9
36化学工业部第四设计院主编.深冷手册(下册).北京:化学工业出版社, 1979, 444
37杨世铭,陶文铨.传热学.北京,高等教育出版社. 2003 :130~132
38 V. Yakhot, S. A. Orszag. Renormalization group analysis of turbulence. Journal of Scientific Comptuing. 1986, (1) :3~5
39 A. Robinson. Nonstandard Analysis. Amsterdam :North-Holland, 1974, Chapter 1, 2, 10
40 J. Lehtonen, R. Mikkonen, J. Paasi, et al. Effective thermal conductivity in HTS coils. Cryogenics. 2000,(42):245~249
41 Chang HM, Choi YS, Van Sciver SW, Choi KD. Cryogenic cooling system of HTS transformers by natural convetion of subcooled liquid nitrogen. Cryogenics 2003, 43 :589~596
42杨世铭,陶文铨.传热学.北京,高等教育出版社. 2003 :162~168
43 R. F. Barron. Cryogenic Heat Transfer. Edwards Brothers, Ann Arbor, M1. 1999 :100~102
44 Yeon Suk Choi, Ho-Myung Chang, Steven W. Van Sciver. Performance of extended surface from a crylcooler for subcooling liquid nitrogen by natural convection. Cryogenics. 2006, 46 :396~402
45惠荣娜.通风管道局部构件阻力系数及减阻方法研究.硕士论文. 2007.6 : 6~15
46汪兴华,吴德怀.风管标准弯头和变径管的局部阻力试验.暖通空调. 1981 :22
47李涛.通风管道局部构件阻力系数的实验和数值模拟研究.西安建筑科技大学硕士学位论文. 2005
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