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管子—管板角焊缝自动超声波检测系统的研制 总被引:1,自引:0,他引:1
针对化工生产设备和核电站中列管式热交换器中的管子—管板角焊缝 ,研制了自动超声波检测系统。介绍了该系统的控制原理、总体结构、扫描图像获取、扫描机械手设计和系统软件开发等方面的关键技术。该系统采用计算机控制扫描机械手扫描管子—管板角焊缝 ,并采集相应的超声回波信号 ,经过一定的处理后 ,显示和打印图形化结果。扫描结果中显示了焊缝所存在的焊接缺陷及缺陷的准确位置。系统可以检测到直径为 0 .5 m m的缺陷 ,检测一个点的时间小于 0 .0 2秒。经实际应用表明该系统完全可以满足工业现场要求。 相似文献
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针对目前核电站用板式热交换器大型化、高参数化及高可靠性、安全性的要求,以 RCC-M 《压水堆核电厂核电机械设备设计和建造规则》为依据,阐述了核电行业典型的设备冷却水系统核安全3级板式热交换器的设计和制造要点,确保满足核电标准的设计要求,并能够安全稳定的运行。 相似文献
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In a nuclear power plant, the tubes of a component cooling water heat exchanger are frequently affected by cold and hot fluid shock waves. Thus, tubes are often found to be worn out. This wear may alter the dynamics of the tubes and introduce mode localization in the heat exchanger. This paper examines mode localization in a component cooling water heat exchanger. A heat exchanger, consisting of periodic cooling tubes is used to simulate as a coupled periodic structure system. Each tube is coupled to the adjacent one through the water, and so the system is weakly coupled. The Galerkin method is employed herein to derive the mode localization equations off the mistuned system, with reference to the fluid effect. Numerical results reveal that the wear may introduce mode localization into a mistuned heat exchanger with fluid. 相似文献
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Ho-Seong Lee Jong-Phil Won Choong-Won Cho Yong-Chan Kim Moo-Yeon Lee 《Journal of Mechanical Science and Technology》2012,26(7):2065-2071
The objective of this study is to investigate the performance characteristics of a stack coolant source heat pump using R744 with a stack coolant heat source for fuel cell electric vehicles under cold weather conditions. Electric heaters are currently used in fuel cell electric vehicles, and the high levels of energy consumption involved lead to lower fuel efficiency and a reduction in the vehicle??s driving range. In order to improve the efficiency of the fuel cell electric vehicles in this study, a heat pump using R744 as a refrigerant and making use of wasted heat from the stacks is developed to cover the heating capacity. This heat pump is tested and performance optimized for stack coolant heat recovery under the compressor speeds, air temperatures, and flow rates of the interior heat exchanger, as well as the coolant flow rates of the CO2-coolant heat exchanger. In addition, the heating capacity of the tested system was sufficiently attained over 5.0 kW at the coolant flow rate of 5.0 l/min under extremely cold weather conditions of ?20°C. 相似文献
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Kyeong Mo Hwang Tae Eun Jin Kyung Hoon Kim 《Journal of Mechanical Science and Technology》2006,20(11):1934-1941
As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes
increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics
and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed
in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling
resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged
tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation
method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate
future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness
of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a
Korean nuclear power plant. 相似文献
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For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd(2)SiO(5) (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required. 相似文献
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小通道平行流换热器是燃料电池汽车的主要散热部件。吸收了电堆废热的冷却液(50%乙二醇溶液),流过小通道换热管,由换热器外侧空气冷却。在进液温度、进风温度、冷却液流量以及风速变化的试验工况下,测试了换热器的传热流动性能。引入量纲一参数k,评估了各工况参数对换热量、阻力影响的强弱。接着,分析液侧努谢尔数Nu和摩阻系数f随雷诺数Re的变化趋势,结果显示:在小通道内(当量直径D=2.685 mm),冷却液从层流到湍流的转浪点Re_c=1 750,介于微尺度与常规尺度的临界值之间。在此基础上,通过多元回归法,拟合得到层流和湍流的液侧换热系数,摩阻系数的关联式,以及空气侧阻力f_a公式。Nu和f的计算值与试验值误差分别在[-7.06%,5.93%]和[-3.95%,4.11%]内,f_a的误差在[-2.22%,3.62%]内。基于这些关联式,建立数学模型,可在广泛多变的运行条件下,对换热器的运行性能进行理论预测和评估。 相似文献
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针对AP1000核电技术中反应堆冷却剂泵因所采用的屏蔽泵转动惯量小、泵的惰走时间短,在汽轮机跳机后,如何保持反应堆冷却剂泵电机3s供电时间的问题,结合AP1000核电厂系统固有特点,分析了“孤岛运行”、“机组满功率运行”、“机组满功率运行+ 500 kV外电网失去”、“机组满功率运行+外电网失去”4种极限工况特点.根据电网稳定性和堆芯偏离核态沸腾仿真结果,分析了汽轮机跳机后的电气系统响应和反应堆冷却剂系统响应.研究结果表明,在汽轮机跳机后系统能满足反应堆冷却剂泵3s供电时间要求,以增加冷却剂强迫循环时间,实现安全停堆. 相似文献
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随着核电、石油化工等行业需求的增长以及工艺复杂程度的提升,其关键设备状态的安全监测缺少直接、实时、在线的监测手段,难以实现故障的准确诊断与预警。本文选取石化和核电行业关键设备管壳式热交换器作为研究对象,通过分析热交换器换热管外结垢机理及对换热性能影响,应用总传热系数建立换热效率、传热平均温差与结垢厚度间的表征关系,提出了一种管壳式热交换器结垢故障虚拟感知方法,利用热交换器的温度、压力、流量等高精度、易获取运行数据,实现热交换器结垢厚度在线准确感知。最后,通过在热态功能试验台架回路上采用高压容器试验件开展了测试验证。结果表明,基于总传热系数的热交换器结垢虚拟感知模型能够在30%误差范围内实现在管径2.2%以上的垢层厚度监测。 相似文献
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Direct immersion cooling has been considered as one of the promising methods to cool high power density chips. A fluorocarbon
liquid such as FC-72, which is chemically and electrically compatible with microelectronic components, is known to be a proper
coolant for direct immersion cooling. However, boiling in this dielectric fluid is characterized by its small value of the
critical heat flux. In this experimental study, we tried to enhance the critical heat flux by increasing the nucleate boiling
area in the heat spreader (Conductive Immersion Cooling Module). Heat flux of 2 MW/m2 was successfully removed at the heat source temperature below 78°C in FC-72. Some modified boiling curves at high heat flux
were obtained from these modules. Also, the concept of conduction path length is very important in enhancing the critical
heat flux by increasing the heat spreader surface area where nucleate boiling occurs. 相似文献
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An experimental study of the effects of various factors (fin pitch, fin arrangement, air temperature, air humidity, and air velocity) on the frost growth and thermal performance of a fin-tube heat exchanger has been conducted under the frosting condition. It is found that the thermal performance of a heat exchanger is closely related to the blockage ratio of the air flow passages due to the frost growth. The maximum allowable blockage ratio is used to determine the criteria for the optimal operating conditions of a fin-tube heat exchanger. It is also shown that heat transfer rate of heat exchanger with staggered fin arrangement increases about 17% and the time required for heat transfer rate to reach a maximum value becomes longer, compared with those of an inline fin-tube heat exchanger under the frosting condition. The energy transfer resistance between the air and coolant decreases with the increase of inlet air temperature and velocity and with decreasing inlet air humidity. 相似文献
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Heat exchangers are widely used in the process engineering such as the chemical industries,the petroleum industries,and the HVAC applications etc.An optimally designed heat exchanger cannot only help the optimization of the equipment size but also the reduction of the power consumption.In this paper,a new optimization approach called algorithms of changes (AOC) is proposed for design and optimization of the shell-tube heat exchanger.This new optimization technique is developed based on the concept of the book of changes (I Ching) which is one of the oldest Chinese classic texts.In AOC,the hexagram operations in I Ching are generalized to binary string case and an iterative process,which imitates the I Ching inference,is defined.Before applying the AOC to the heat exchanger design problem,the new optimization method is examined by the benchmark optimization problems such as the global optimization test functions and the travelling salesman problem (TSP).Based on the TSP results,the AOC is shown to be superior to the genetic algorithms (GA).The AOC is then used in the optimal design of heat exchanger.The shell inside diameter,tube outside diameter,and baffles spacing are treated as the design (or optimized) variables.The cost of the heat exchanger is arranged as the objective function.For the heat exchanger design problem,the results show that the AOC is comparable to the GA method.Both methods can find the optimal solution in a short period of time. 相似文献
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三维裂纹仿真分析和防断裂设计问题一直是断裂理论和工程应用研究的主要课题。管道系统是核动力工程中的关键部件。运用三维有限元分析软件 ANSYS 和裂纹分析专用程序 Franc3D,针对中国实验快堆(CEFR)一段余热排放系统中的含裂纹管道进行了三维裂纹仿真模拟分析和LBB(Leak -Before -Break)评定。快堆管道工作时处于高温状态,因此,采用适用于高温环境下的材料和法国结构安全设计规范 RCC -MR.A16标准文件。研究的管道材料为9Cr1Mo 钢的改良型———T91/P91管材,分析模型为含裂纹的三维结构,且包括管道高温工况和蠕变效应。仿真计算结果表明,针对所研究的工况,蠕变较疲劳对三维裂纹扩展的影响更大。采用 T91钢的管路系统能够满足相关规范中的 LBB 设计准则。该研究为快堆管道选材、含缺陷管道安全评估和高温完整性评定提供设计参考。 相似文献
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E. L. Matveev A. L. Matveev A. Yu. Mishenin 《Journal of Machinery Manufacture and Reliability》2013,42(2):171-178
A new algorithm for locating a coolant leak through the analysis of temperature field values is presented. This algorithm is based on the measurements of air temperature at different points of the controlled area of the multiple forced circulation circuit of a nuclear power plant (NPP) and enables the determination of the dimension, location, and time of a coolant leak. 相似文献