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研究国产600 MW直流锅炉分配集箱在亚临界压力下的流量分配特性.试验段由φ42 mm×5.5mm的分配集箱、φ25 mm× 3 mm分配集箱径向引入管和φ10 mm×1.5 mm的垂直并联水冷壁管组成,材料为1Cr18Ni9Ti钢管;试验参数为:压力p=4 MPa~19 MPa,质量流速G=400 kg/(m2·s)~1 200 kg/(m2·s),质量含汽率x=0~1.0.试验研究了工质压力、质量流速和集箱入口质量含汽率对分配集箱垂直水冷壁管流量分配和质量含汽率分配特性的影响.随着分配集箱工作压力和分配集箱进口质量流速的增加,分配集箱并联支管之间的质量含汽率分配的偏差降低;在入口质量含汽率较小时,并联支管之间的质量含汽率的分配偏差随着质量含汽率的增加而增大;在入口质量含汽率>0.55时,并联支管之间质量含汽率的分配偏差随着入口质量含汽率的增加而减小. 相似文献
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研究了国产600 MW直流锅炉分配集箱水冷壁管在超临界压力下的流量分配特性。试验参数为:压力p=23~25MPa,质量流速G=400~1 200 kg/(m2.s),工质温度t=10~400℃。试验研究了工质压力、质量流速和工质温度对分配集箱垂直水冷壁管流量分配特性的影响。试验结果表明:随着质量流速的增加,垂直水冷壁管间流量分配的均匀性增加;在拟临界点附近,流量分配不均匀性有一阶跃增加,而且随着压力的增加,流量分配不均匀性在拟临界点的阶跃增加现象变弱。利用分配集箱并联支管的离散模型计算了分配集箱垂直水冷壁管内的流量分配,计算结果与试验数据吻合。 相似文献
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针对600 MW超临界锅炉炉膛下部的螺旋管圈水冷壁与炉膛上部垂直管水冷壁之间过渡联接的中间集箱的结构和参数特点,利用空气-水模拟了超临界锅炉在35%ECR、50%ECR和75%ECR负荷下气-液两相流在中间集箱中的分配特性.通过观察和高速摄影法,对分配集箱并联支管中的流型进行了测量和分析.采用快关阀门法和摩擦阻力法分别测量了各支管的含气率和流量.试验结果表明,在3种工况下,入口干度x=0.7-0.95的范围内,空气-水两相流通过分配集箱并联支管内的流量分配较为均匀,绝大多数情况下流量偏差小于10%. 相似文献
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为了解三通结构对过热器流量分配的影响从而解决三通集箱过热器的爆管问题,利用Fluent软件对过热器模型进行了数值模拟,研究了三通结构集箱过热器内的静压分布、速度分布、各支管流量分配及各支管入口处流体的流速分布和静压分布.结果表明:三通结构附近流体的压力低且速度大,而远离该区域的流体则压力高且速度小;三通中涡流区域的支管入口有小涡流,而其他区域的支管入口没有出现小涡流;集箱内涡流下部的支管流量偏小,正对集箱入口处的支管流量最大;将第7管屏和第11管屏的入口形状改为圆形,改造后支管的流量明显增大. 相似文献
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在模拟直流锅炉集箱系统的空气-水试验台上,对分配集箱入口装设加速管和不装设加速管的水平U型和Z型集箱系统的两相流流量分配特性进行了对比性实验研究。研究发现:在相同的两相流量条件下,在分配集箱入口装设加速管,能够有效地改进原有集箱系统的分配特性。当分配集箱入口的两相流流速达到破膜速度的0.45倍左右时,集箱系统的两相流量分配已基本均匀。 相似文献
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针对上海锅炉厂有限公司350 MW超临界循环流化床锅炉水冷屏的结构,建立了竖直集箱内空气-水两相流动试验平台.根据质量守恒、动量守恒和补充方程,建立了水冷屏竖直集箱内流量分配的数学计算模型,进行了35%额定负荷时不同干度试验工况下竖直集箱内流量分配的计算,得到了各支管内质量流量不均匀系数、最大质量流量偏差系数、体积流量含气率不均匀系数和最大体积流量含气率偏差系数,并将理论计算值与试验值进行了对比.结果表明:对于单一工况,从第1根支管到第4根支管,质量流量逐渐增加,质量流量偏差系数从负数增大为正数,体积流量含气率逐渐减小,体积流量含气率不均匀系数从正数减小为负数;计算所得数据的变化规律与试验结果一致,且随着干度的增大,计算值与试验值的偏差逐渐减小. 相似文献
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《International Journal of Hydrogen Energy》2022,47(63):26789-26797
The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO2 and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized. 相似文献
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Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined. 相似文献
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基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁(MgO),研究了该型MgO膨胀剂(MEA)细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析(TG DSC)分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。 相似文献
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使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。 相似文献
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M.R. Salimpour M. SharifhasanE. Shirani 《International Communications in Heat and Mass Transfer》2011,38(1):93-99
This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed. 相似文献
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本文对漫灰均温物体在常物性条件下对外辐射传热的Yong值计算建立了数学模型。通过与物体内能Yong公式的数值计算比较,得出了辐射能量的Yong值不大于内能Yong值的结论。从初步的热射Yong值计算公式发现。Yong与物体表面辐射率有关。 相似文献
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《International Journal of Hydrogen Energy》2022,47(83):35515-35526
The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%. 相似文献
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General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996 相似文献