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高温超导电流引线在EAST装置工程调试中投运 总被引:1,自引:0,他引:1
EAST全超导托卡马克核聚变实验装置有一对纵场磁体电流引线和12对极向场线圈电流引线,额定电流为14.5~16.3 kA,在第二轮装置工程调试中5对高温超导电流引线投入运行.这些电流引线的高温超导段系传导冷却,上端用79K液氮冷却,下端由4.5K超临界氦流迫冷;铜电流引线段采用氮蒸汽冷却.运行参数表明高温超导电流引线具显著的节冷效益.本文介绍这些电流引线的运行工况和安装前的接收试验结果. 相似文献
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对超导装置电流引线的一种新型冷却方式——超临界氦迫流冷却作了研究。发现对于一定的运行电流,存在着一种最佳工况,此时冷却超导装置制冷机的室温功耗最低。对于残余电阻比rrr=89的铜引线和温度T=5.2K,压强p=8×10~5Pa的超临界氦冷介质,最佳工况参数与运行电流间的函数关系已被求得并为实验证实。 相似文献
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EAST装置15kA高温超导电流引线研发 总被引:5,自引:0,他引:5
低温超导磁体采用高温超导电流引线能显著降低制冷系统的造价和运行费用.正在建造中的大型超导托卡马克核聚变试验装置(EAST)需要一对16kA和12对15kA电流引线.所研发的电流引线采用美国超导(AMSC)公司提供的Bi-2223/Ag-Au带材, 每5条超导带组成单元叠,与不锈钢支撑圆筒表面50个槽软钎焊成超导段.支撑筒两端铜接头,温端与铜电流引线段丝扣连接并低温钎焊;冷端与100根NbTi/Cu超导线直接锡铅钎焊.冷端采用4K超临界氦流冷却;温端正常运行温度为78K,用液氮冷却.设计要求在此冷却条件下的临界电流大于16kA.78~290K铜电流引线采用3头螺旋槽换热器,冷氮气冷却.为提高电流引线的安全性,在高温超导段温端贮存适量液氮作为热沉,大大增加电流引线被烧毁的时间常数. 相似文献
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低温超导磁体采用高温超导电流引线能显著降低制冷系统的造价和运行费用.正在建造中的大型超导托卡马克核聚变试验装置(EAST)需要一对16kA和12对15kA电流引线.所研发的电流引线采用美国超导(AMSC)公司提供的Bi-2223/Ag-Au带材,每5条超导带组成单元叠,与不锈钢支撑圆筒表面50个槽软钎焊成超导段.支撑筒两端铜接头,温端与铜电流引线段丝扣连接并低温钎焊;冷端与100根NbTi/Cu超导线直接锡铅钎焊.冷端采用4K超临界氮流冷却;温端正常运行温度为78K,用液氮冷却.设计要求在此冷却条件下的临界电流大于16kA.78-290K铜电流引线采用3头螺旋槽换热器,冷氮气冷却.为提高电流引线的安全性,在高温超导段温端贮存适量液氮作为热沉,大大增加电流引线被烧毁的时间常数. 相似文献
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气冷电流引线被广泛的应用于许多大型超导磁体及其它一些超导装置中.由于引线实际制作过程中的差异或者超导装置本身的一些问题,正负两个引线之间或者同一引线的不同流道之间都存在着冷却气流分配上的不均衡.超导装置中除电流引线外的其他低温热源也可能使流经引线的冷却气流处于非正常状态.所有这些都会使电流引线的实际工作状况偏离最优化设计.本文用数值模拟的方法对非最优化冷却气流条件下的电流引线运行状况进行了研究,分析了冷却气流偏离最优化程度与引线实际运行参数之间的影响关系. 相似文献
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EAST 装置电流馈线系统由13 对NbTi 材料CICC 超导母线组成,连接超导磁体系统和高温超导电流引线,为磁体系统的运行提供馈电通道和失超状态下能量的释放通道。馈线系统中超导母线由液氦制冷机通过低温分配阀箱提供的4.5K 超临界氦冷却,冷却通道进口压力为0.45MPa,出口压力不小于0.25MPa。通过对超导母线和接头内流道中的迫流氦的压降计算确定了冷却流程方案为1 对TF 超导母线单独串联组成1 个冷却通道, 12 对PF 超导母线分为6 个冷却通道,每个通道由2 对PF 超导母线串联组成。 相似文献
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An experimental investigation on the heat transfer effectiveness of solid and slit ribs mounted on the bottom surface of a rectangular channel has been carried out at Reynolds numbers of 13400, 22600, 32100 and 40800. The rib height to hydraulic diameter ratio (e/D h)set during experiment is equal to 0.0624. The surface Nusselt number results from transient liquid crystal thermography are presented. The heat transfer enhancement performance analysis has been carried out using entropy generation principle. The slit rib is superior to solid rib from both heat transfer augmentation and pressure penalty point of view. The performance of the slit rib is a function of the open area ratio (β) and the location of the slit (b) from the bottom test surface. The optimum open area ratio is 20% and the slit located symmetrically from the top and bottom surface of the rib is the optimum location of the slit. The heat transfer augmentation of the slit rib (β=20%) is 61% in comparison to 40% for the solid rib at Re=32100 and the pressure penalty for the slit rib is 7% lower than the solid rib. The entropy generation for the slit rib is 33% less than that of the solid rib. 相似文献
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分离式热管换热器传热特性的实验研究 总被引:1,自引:0,他引:1
本文在自行设计分离式热管实验装置的基础上,对其传热特性进行了实验研究。其工作温度为170~250℃,热流密度为25~50 kW/m~2。蒸发段和冷凝段构成相同,均是由7根直径30 mm的无缝钢管短管束组成,管长为160 mm,带有紧套的钢帛环形肋片结构尺寸为:外径45 mm、厚1 mm、片间距4 mm。实验结果表明,在本实验条件下,分离式热管的最佳充液率按管束总容量计为18%~38%。根据实验结果拟合了最佳充液率(24%)下蒸发段内部平均沸腾换热系数和冷凝段内部凝结换热努塞尔数综合关系式。 相似文献
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An experimental study was conducted to obtain a correlation for free convection heat transfer from isothermal elliptic tubes of minor to major axis ratios of ∈ = 0.53, 0.67, 0.8, and 1 confined between two adiabatic walls. Local and average Nusselt numbers were determined for several different tube axis ratios, Rayleigh numbers, and wall spacings by means of the Mach-Zehnder Interferometery (MZI) technique. For each tube axis ratio, the Rayleigh number varied from 1,000–2,750 and the wall spacing to tube minor axis ratio from 1.25–∞. For all the tube axis ratios, the periphery and length of the tubes were kept constant. Experimental data are presented with a correlation which gives the average Nusselt number as a function of the tube axis ratio, Rayleigh number, and wall spacing to tube minor axis ratio. As the tube axis ratio decreases the average heat transfer coefficient increases. Also, for a constant Rayleigh number and tube axis ratio there is an optimum wall spacing which maximizes the heat transferred from the tube. 相似文献
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An experimental study was performed to investigate the influence of Reynolds number (Re) and non-dimensional jet-to-jet spacing (S/Dh) on flame shape, structure and temperature field of an array of laminar premixed slot flame jets. Mach-Zehnder interferometry technique is used to obtain an insight to the overall temperature field between single, twin and triple slot flame jets. The slot jets with large aspect ratio (L/W), length of L=60 mm and width of W=6 mm were used to eliminate the three-dimensional effect of temperature field. The effect of jet-to-jet spacing was investigated on flame characteristics under the test conditions of 200≤Re≤400 and equivalence ratio (φ) of unity. The present measurement reveals that the variation of maximum flame temperature with increment of Reynolds number is mainly due to heat transfer effects and is negligible while the flame height is increased. For the cases of twin and triple flame jets by increasing Reynolds number and decreasing non-dimensional jet-to-jet spacing (S/Dh), the interferences between the jets are increased and the jets attracted each other. Strong interference was observed at S/Dh=1.15. For the case of triple jets at this S/Dh, the central jet was suppressed while the side jets deflected towards the inner jet. The interference between jets was found to reduce the heat flux in the jet-to-jet interacting zone due to incomplete combustion. Also the optimum jet-to-jet spacing of triple flame jets is obtained at each Reynolds number to enhance the heat transfer performance of the jets. 相似文献
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This article presents an investigation on heat transfer enhancement in a round tube inserted with a helically twisted tape. The effects of a helically twisted tape with alternate axis (HTT-A) on heat transfer, friction factor, and thermal performance factor behaviours are reported for the turbulent regime. HTT-A geometries are tape pitch to tube diameter, P/D = 1.0, 1.5, and 2.0; alternate length to pitch length, l/P = 1.0, 1.5, and 2.0; twisted length to tape width, y/W = 3.0; and tape width to tube diameter, w/D = 0.2. The experiment has been performed by varying the volumetric air flow rate in order to adjust Reynolds number ranging from 6 000 to 20 000. The wall of the testing tube is uniformly heated as a constant heat flux while the tests are covered with thermal insulations to reduce heat loss to surroundings. Thermal performance is evaluated by comparing the present experimental results with the results of the modified HTT-A and also those obtained from previous study (conventional helically twisted tape, HTT). The thermal performance of tested tube with HTT-A is evaluated to obtain the degree of heat transfer enhancement and friction factor induced by HTT-A with respect to the plain tube under the same test conditions. Evenly, it is interesting to observe that the tube with HTT-A consistently possesses higher heat transfer and thermal performance factor than those with the HTT around 14.1% and 1.9%, respectively. The HTT-A with the smaller pitch ratio and adjacent twist length provides higher heat transfer rate and friction factor than the one with larger pitch ratio and alternate length as a result of a larger contact surface area, stronger swirl intensity and, thus, better fluid mixing near the tube wall. In the range determined, the tubes with the largest pitch ratio (P/D = 2.0) and smallest alternate length (l/P = 1.0) give the highest thermal performance factor at around 1.35. In addition, the empirical correlations of the Nusselt number, friction factor, and thermal performance factor are also described. 相似文献
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为探究印刷电路板换热器(PCHE)Z型通道中超临界CO2的换热特性,在换热面积固定的前提下指导回热器优化设计,采用数值模拟方法对CO2-CO2耦合换热的局部和整体特性进行了分析,通过CFD计算得到典型PCHE结构和典型工况下回热器的换热特性,与实验结果进行对比,验证计算模型。并利用此模型计算具有相同换热面积、不同通道结构的回热器的局部和整体换热性能,厘清结构参数对换热性能的影响规律。研究表明,计算结果与实验结果吻合,当通道夹角从110°增加至115°时换热系数出现最大幅度的下降,根据不同的设计需求,最佳的夹角范围为110°~120°。 相似文献
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热电发电机驱动热电制冷机联合系统最优性能 总被引:1,自引:0,他引:1
用非平衡热力学与有限时间热力学相结合的方法,考虑装置内部的Seebeck效应、Peltier效应、焦耳热效应、傅立叶效应及装置与热源间传热损失,建立了牛顿传热规律下热电发电机驱动热电制冷机联合系统的有限时间热力学模型,得到装置制冷率和制冷系数的解析式.在装置热电单元总数和换热器总换热面积一定的条件下,优化热电单元和换热面积的分配,获得装置的最大制冷率和制冷系数,并着重分析了热电发电机高温热源温度和热电制冷机制冷空间温度对装置最优性能的影响.结果表明,优化可以有效地提高装置制冷率和制冷系数,增大装置极限制冷温差,拓宽装置工作范围. 相似文献