共查询到17条相似文献,搜索用时 46 毫秒
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以孔径分别为4、10、16 mm的侧开孔I型喷洒器为实验件,对质量流速为300~1100 kg·m?2·s?1的饱和蒸汽浸没在温度为35~65℃的过冷水中的直接接触式冷凝开展实验研究。结果表明:孔径不变时,汽羽贯穿长度基本随蒸汽质量流速和池水温度的升高而增大;大孔径喷洒器的汽羽长度与直管式喷嘴的汽羽长度接近,拟合值与实验值的偏差在±15%以内;小孔径喷洒器的汽羽长度明显低于直管式喷嘴,拟合值与实验值的偏差最高达80%;采用收缩喷管流量公式对蒸汽质量流速进行修正,拟合值与实验值的偏差在±20%以内,由实验值拟合的新关系式的预测误差在±10%以内。 相似文献
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实验研究了不凝性气体(空气)含量、水温和蒸汽质量流速对蒸汽浸没射流冷凝压力振荡特性的影响,实验工况横跨冷凝振荡(CO)区和稳定冷凝(SC)区。结果表明:对于纯蒸汽射流,压力振荡主频随水温的升高而降低,振荡强度随水温的升高而升高;在CO区,振荡主频和振荡强度均随蒸汽质量流速的升高而升高;在SC区,振荡主频随蒸汽质量流速的升高而降低,振荡强度基本上不随蒸汽质量流速的变化而发生改变;对于含空气射流,随空气质量分数的增加,振荡主频总体呈下降趋势,振荡强度先迅速下降后小幅上升,在空气质量分数为0.05~0.1区域内振荡主频和振荡强度均存在极小值。 相似文献
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对含不凝结气体(空气)的蒸汽浸没射流压力振荡特性进行了实验研究。研究发现,含有少量不凝结气体时,蒸汽浸没射流凝结形态发生显著变化。含不凝结气体的压力振荡强度较纯蒸汽时明显变小,但含有少量不凝结气体的压力振荡强度随空气质量分数的增加整体呈缓慢上升趋势。压力振荡强度随径向距离的增加而单调减小,随轴向距离的增加先增大后逐渐减小,存在压力振荡峰值,且随空气质量分数的增加,压力振荡峰值位置沿轴向后移。压力振荡峰值位置在轴向无量纲距离X=3和X=12之间。不同过冷水温度下,压力振荡峰值随空气质量分数变化的趋势不同。压力振荡峰值的位置即压力振荡最强的位置位于核心汽羽的尾部。 相似文献
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为指导Ⅰ型鼓泡器排放管的结构设计,对常压工况下不同蒸汽质量流速(150~500 kg/(m2·s))、池水过冷度(18~68 ℃)、开孔直径(10、16 mm)和孔数(单孔、双孔)蒸汽浸没射流的压力振荡特性开展实验研究。结果表明:不同开孔结构下的振荡强度均随蒸汽质量流速的升高或池水过冷度的降低而先增大后减小;当孔径增大或孔数增多时,达到稳定冷凝所需的最小蒸汽质量流速降低,流型转变导致振荡强度减小。不同开孔结构下的振荡主频均主要受池水过冷度和开孔直径的影响,且随过冷度的降低或孔径的增大而减小。孔数变化对主频的影响是多重的,但总体效果弱于孔径变化。通过对主频实验值进行拟合,获得了由池水过冷度和排放孔径表征的半经验关系式,相对误差在±20%以内。 相似文献
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AC600非能动安全壳冷却系统冷凝传热系数评价 总被引:1,自引:0,他引:1
用AC600非能动安全壳冷却系统三维热工水力分析程序PCCSAC-MD,对几种常用的冷凝传热系数结构关系式进行了比较。这些结构关系式包括Uchida关系式,Gido-Koestl关系式,Tagami关系式和基于传热传质相似原理的关系式。 相似文献
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对含不凝性气体的蒸汽在竖直圆管外表面冷凝传热进行实验研究,分析过冷度、压力、不凝性气体质量分数以及氦气占比对蒸汽冷凝换热的影响,给出冷凝传热过程中的经验关联式并同经典公式进行对比。结果表明:在压力不变的条件下,壁面过冷度同冷凝传热系数的变化趋势相反;实验范围内,未发生氦气分层现象;所得到的经验关联式具有更广的适用范围,且其与实验值的误差在±20%以内。 相似文献
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蒸汽射流凝结压力振荡幅值研究 总被引:1,自引:1,他引:0
为了得到蒸汽在过冷水中浸没射流凝结引起的压力振荡特性,针对不同的蒸汽质量流率和过冷水温度对压力振荡的影响进行实验研究。通过高频压力传感器测量得到了不同测点位置的压力振荡幅值,并结合蒸汽射流凝结形态分析蒸汽质量流率和过冷水温度对压力振荡幅值的影响规律。结果表明,蒸汽射流凝结在凝结振荡区比较剧烈,在稳定射流区相对缓和,从凝结振荡向稳定射流的形态转变导致了压力振荡幅值随蒸汽质量流率出现先减小后增大的趋势;振荡幅值随水温的升高不断增大,特别是当水温大于40℃时,由于过冷度减小,射流凝结形态变得发散,导致凝结振荡幅值大幅增加。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(11):845-855
Heat transfer coefficients of steam condensation on the containment vessel wall at a LOCA are studied. As to the steady state heat transfer coefficients, though Sagawa's data are a little smaller than Uchida's data, they are very close to the analytical solutions by Mori-Hijikata. Transient heat transfer coefficients are represented by the steady state heat transfer coefficients multiplied by a factor. The factor expresses the agitation effect weakening with time during blowdown. Values of parameters in the factor are determined so as the heat transfer coefficients to fit Sagawa's data. These heat transfer coefficients are applied to the analyses of the experiment with the simulation apparatus of an integrated type marine water reactor. Values of the parameters are also determined so that the temperature transients on the containment vessel wall by analyses fit them of experiment. The differences of the values of parameters by the analyses and by Sagawa's data are discussed. 相似文献
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以水蒸气为工质,实验研究了水平管内纯蒸汽冷凝的局部换热特性。实验选取换热管内径为25 mm、换热管进口压力为0.15~0.4 MPa、局部蒸汽的Re=5756~92289,分析了蒸汽压力及流速、壁面过冷度对冷凝传热系数的影响,并将采用现有关系式计算的冷凝传热系数与实验结果进行了对比。结果表明:冷凝传热系数随壁面过冷度的增大而减小,随压力的升高和流速的增大而增大;采用现有关系式计算的冷凝传热系数与实验值的偏差较大,关系式有待进一步改进;在实验范围内,由拟合换热关系式计算所得冷凝传热系数与实验结果的相对偏差在15%左右。 相似文献
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FENG Li LU Daogang FU Jingpin LIU Lifang FU Xiaoliang YUAN Yonglong QIU Zhimin ZHANG Yuhao 《原子能科学技术》1959,54(9):1559-1567
The steam direct contact condensation of high-temperature steam in sub-cooled water is an important way to reduce the temperature and pressure in the primary circuit in the third generation of advanced pressurized water reactors such as AP1000 and CAP1400 in the event of accidental overpressure. Based on the system codes of RELAP5 and COSINE, the process of saturated steam injecting into large volume sub-cooled water through a double-hole nozzle was modeled, calculated and analyzed. The temperature distributions along the axial direction of the high-temperature steam ejected from the nozzle were obtained. At the same time, the visual experiments of steam jet condensation were performed. The thermocouple matrix and high-speed camera were used to measure the key thermal-hydraulic parameters to obtain the temperature distributions along the steam plume and the flow patterns of the steam jet, which were used to verify the accuracy of the system code to simulate the process of steam spraying and condensation. The results show that the system code RELAP5 can basically simulate the general trend of ADS steam condensation process under the simplified model. The average error of the simulation results is 2.97% compared with the experimental results. In addition, the COSINE code was used to further modify and improve the model of the spraying condensation process. Considering the influence of the overall flow in the water tank on the condensation characteristics, the simulation results fit well with the experimental results, with an average error of 1.89%. However, the actual double-hole spraying process is complex and has obvious three-dimensional characteristics, so the relevant condensation heat transfer model in the system code still needs to be further improved to simulate its local condensation characteristics more accurately. 相似文献
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高温蒸汽在过冷水中喷放直接接触式冷凝是AP1000、CAP1400等三代先进压水堆一回路在事故超压情况下重要的降温降压途径。本文基于系统程序RELAP5、COSINE对饱和蒸汽通过双孔喷洒器喷入大容积过冷水中进行直接接触冷凝这一过程进行建模、计算、分析,获得高温蒸汽从喷口喷出后沿轴向的温度分布。同时开展蒸汽喷放冷凝可视化实验,采用热电偶矩阵和高速摄像机等对关键热工参数进行测量,以获得蒸汽汽羽的温度分布和喷放流型等,用于验证系统程序对蒸汽喷放冷凝过程模拟的准确性。结果表明,采用RELAP5程序基本能模拟简化条件下的ADS蒸汽喷放冷凝总体变化规律,模拟结果与实验结果相比平均误差为2.97%。此外,采用COSINE程序对喷放冷凝过程模型进行了进一步修正和改进,考虑水箱内整体流动对喷放特性的影响,模拟结果与实验结果吻合较好,平均误差为1.89%。但由于实际双孔喷放过程较为复杂,并且存在明显的三维特性,所以仍需对系统程序中相关冷凝传热模型进行完善,以更精确地模拟其局部冷凝特征。 相似文献