共查询到16条相似文献,搜索用时 78 毫秒
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对环形通道内液态金属钠沸腾两相流动特性进行了实验研究。实验中,系统压力为3.6~110.0kPa,热流密度为11~600kW·m~(-2),流速为0.02~0.45m·s~(-1)。实验结果表明,液态金属钠沸腾传热系数与壁面热流密度和系统压力有强烈关系,而与入口过冷度和质量流速无关。在本文实验数据基础上,拟合得到了计算液态金属钠沸腾两相传热系数的关系式,通过与各组实验数据间的比较,证明本文关系式适用于计算环形通道内液态金属钠沸腾两相传热系数。 相似文献
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对液态金属钠在环形通道内的单相流动换热特性进行了实验研究。结合实验数据,将液态金属钠单相流动分为层流区(Re≤2 000)、过渡区(2 000Re≤4 000)及湍流区(Re4 000),分别拟合得到不同流态下摩擦系数的计算关系式,并拟合得到液态金属钠环形通道内换热特性的相应关系式。结果表明:液态金属钠单相流动特性与常规流体(如水)类似,其层流区摩擦系数略大于水,湍流区与水的很接近。液态金属钠对流换热过程中,导热项占较大份额,同时Nu随Pe的增大而略有增大。 相似文献
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对环形通道内金属钠起始沸腾壁面过热度进行实验研究。实验段长800 mm,环形通道外径10 mm,内径6 mm。电加热元件最高热流密度为846 kW/m2,进口过冷度为63.1~287.8 ℃,质量流量为7.2~122.0 kg/h,系统压力为0.85~28.79 kPa。实验结果表明,起始沸腾壁面过热度随热流密度和进口过冷度的增加而升高,随质量流量和系统压力的增加而降低。拟合得到了关于起始沸腾壁面过热度的半经验关系式,关系式计算结果与实验数据符合良好。 相似文献
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实验研究了横向均匀和非均匀(多项式和正弦分布)加热条件下垂直矩形通道(2 mm×60 mm×1 000 mm)的沸腾压降特性,实验段为双面加热,有效加热面尺寸为56 mm×700 mm。工作流体为去离子水,通过改变入口压力和流量边界开展不同参数工况下的实验研究。结果表明,两相压降梯度随饱和压力的增加而减小,随质量流速的增加而增大,含气率对两相压降的影响与质量流速有关,横向功率分布形式对流动沸腾压降也有重要影响。基于均匀加热实验数据对现有的两相压降预测模型进行了评价,发现使用等效黏度假设的均相模型极大低估了实验值,且预测结果的分散度较大;分相模型中Müller-Steinhagen和Heck、Li和Wu关系式预测效果最好,平均绝对误差分别为11.8%和12.3%,且大多数预测值在±20%误差带内。本文基于Müller-Steinhagen和Heck关系式形式引入邦德数Bo考虑表面张力的影响,拟合得到新的预测关系式,该关系式对实验数据的预测误差在±8%的误差范围内。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(7):493-500
Experiments of density wave instability in a sodium boiling two-phase flow in an annulus were carried out with the parameters of heat flux from 80 to 976kW/m2, inlet subcooling from 25.6 to 226.8°C, mass flow rate from 7.92 to 68.9 kg/h, and system pressure from 2,600 Pa to 0.06 MPa. It was found that the density wave instability occurred in the case of low exit quality, and the oscillation of flow rate was so large that the flow would be reversal. The lower inlet temperature, the higher system pressure and the larger mass flow rate could result in a more stable boiling two-phase flow. The oscillation period of the instability increased with the system pressure and the inlet subcooling, but it decreased with the mass flow rate. A correlation for the onset condition of the density wave instability was obtained from the experimental data. 相似文献
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SUN Rulei ZHANG Dalin ZHOU Jiancheng SONG Gongle TIAN Wenxi SU Guanghui QIU Suizheng 《原子能科学技术》1959,54(9):1537-1549
The flow boiling pressure drop characteristics of a vertical rectangular channel (2 mm×60 mm×1 000 mm) were studied under transverse uniform and non uniform heating. The test section was double-sided heating with an effective heating area of 56 mm×700 mm. Three kinds of heating power distributions (uniform, polynomial and sinusoidal) were selected, and the working fluid was deionized water. A wide range of operating conditions was obtained by varying the inlet pressure and mass flux. The results show that the pressure drop gradient decreases with the increase of saturation pressure and increases with mass flux. The influence of vapor quality on two-phase pressure drop is related to mass flux, and the transverse power distribution has an important effect on the flow boiling pressure drop. Based on the experimental data of uniform heating, the existing two-phase pressure drop prediction model was evaluated. The homogeneous model using the equivalent viscosity assumption significantly underestimated the experimental values, and the data dispersion is relatively large. The Müller-Steinhagen and Heck and Li and Wu formulas are found to be the best with mean absolute errors of 11.8% and 12.3%, and most of predicted values are within ±20% error band. In this study, a new correlation based on the form of Müller-Steinhagen and Heck formula was proposed, and the Bond number Bo was introduced to consider the effect of surface tension. The prediction error of the new correlation for experimental data is within 8% error band. 相似文献
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环形窄缝通道内流动不稳定性试验研究 总被引:3,自引:1,他引:3
设计了加热长度为1800mm,间隙尺寸为1.5mm的环形窄缝通道试验段;以去离子水为上质,进行了强迫循环下两相流动不稳定性试验研究。实验压力为1.5~3.0MPa,质量流量为3.0~25kg/h,加热功率为3.0~6.5kW,进口温度为20℃、40℃、60℃。实验发现,在一定加热功率和进口条件下,回路流量低于特定值,会发生不稳定现象。试验研究了进口过冷度、系统压力和质量流量等参数对不稳定性的影响,得到了环形窄缝通道内强迫循环下两相流动不稳定区间。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(11):774-790
This paper deals with local sodium boiling in the downstream of a six-subchannel blockage in an electrically heated LMFBR fuel subassembly mock-up. The first series of experiments were conducted to measure temperature distributions in the downstream of the blockage under non-boiling conditions. The measured temperature rise due to the blockage agreed fairly well with the calculation by the LOCK code. The second series of experiments were performed to investigate local boiling phenomena. In the local boiling region, no flow instability was observed since the sub-channels near the wrapper wall were still filled with sub-cooled liquid. In the nearly bulk boiling region, however, considerable upstream voiding occurred and then the inlet flow decreased, leading to final dryout. The boiling caused a considerable increase in acoustic noise intensity. The root-mean-square (RMS) noise level of approximately 20 mbar obtained in the present local boiling experiments with sodium was much higher than that (approximately 0.5 mbar) in the ordinary nucleate boiling experiments with water. The peak observed in the hertz ranges was due to the repetition of bubble formation and collapse. In the kilohertz ranges, however, resonance peaks were superposed on a smooth curve with a broad peak at approximately 7 kHz. The frequency (2.9 and 20.2 sec?1) of bubble formation decreased with the increase of the bubble size at its point of maximum development. The product of the bubble frequency and the equivalent diameter was found to be constant. 相似文献