高温电离式气体流量传感器的研制

概述了一种新型大管径高温含尘气体流量传感器，采用电离气体离子示踪技术测量气体流量，具有本质抗干扰、抗污染能力。针对管径３及流场速度分布特征而设计的一体化结构，对流场影响小，接收电极弧形，耐高温材料制造，适于高温测量，利用上述方法制成的传感器可测量局域流场，并可根据大管径流场分布计算整体流场速度，经实验室测量，精度为３％。     

汽水两相流体的单圆缺孔板双参数测量方法

提出了电站锅炉汽水两相流体质量流量和干度的测量方法 ,介绍了汽水两相流体质量流量和干度测量数学模型的建立和数据分析处理过程。在某电厂 6 70t/h锅炉上的测试结果表明 ,采用该方法测量汽水两相流体质量流量和干度是可行的。该方法能够有效地克服汽水两相流体流动不稳定性对测量精度的影响 ,显著地提高了测量精度。在试验范围内 ,汽水两相流体的质量流量测量误差小于± 5% ,最好的结果在±3%范围内     

气液两相流容积含气率的图像检测方法

研究开发了一种在线检测气液两相泡状流容积含气率的方法.该方法基于数字图像处理技术,采用高速摄像仪系统,对垂直上升管道中泡状流流动过程进行实时拍摄和图像采集,利用边缘检测和图像填充技术提取并计算气泡尺寸,从而计算容积含气率.对不同工况下的客积含气率进行了实时在线检测,实验结果表明:检测值与真实值比较,相对误差不超过15%,具有较高的测量精度,可以用于气液两相流参数的在线检测.     

小型天然气流量测量装置的研究与应用

根据文丘里管测量装置的基本原理,针对小流量天然气流量的测量,分析了影响测量范围及测量精度的主要因素,通过采用环形多点取压的方式,研究设计开发了一种适用于小流量测量的文丘里管测量装置,并通过实验检测证明该装置测量精度较高,能够满足工程测量的要求。     

微细通道CO_2流动沸腾换热临界热流密度研究

CO2在微细通道内流动沸腾换热过程所具有的临界热流密度(CHF)对于其换热系数有着重要影响。根据国内外现有发表的公开文献的实验数据分析了质量流量、饱和温度、管径等对临界热流密度的影响,并对理论模型与试验数据进行误差分析。发现Bowring预测关联式对小于3 mm管径内临界热流密度预测精度较高,在30%误差范围内可以达到70%预测精度,Wojtan预测关联式具有较小的平均绝对误差。提出了今后CO2在微细通道内沸腾换热CHF的研究方向。     

流动型量热器的数值模拟

为了探究流动型量热器的结构参数和加热功率对量热器内流体的温升的影响,采用Fluent软件建立流动型量热器模型对量热器内的流体进行模拟分析。设定内管径的尺寸Φ3 mm,模拟得出:管路外径的最佳范围为Φ4~7 mm;设置内管直径为3 mm,外管直径为6 mm,内管长度75 mm,外管长度为130 mm,温度为293.15 K,压力为0.1 MPa,流量为5 ml/min,模拟得出:纯水、乙醇、甲苯的最佳功率范围:0.124~0.371 W,0.170~0.507 W,0.354~1.064 W。     

平行流蒸发器内气液两相流分配均匀性实验研究

平行流蒸发器内气液两相(特别是液相)在各扁管间的分配对其传热性能影响较大,如果各扁管间的气液分配不均匀其传热性能将显著地下降.在不同气-液流量下实验研究了6种不同形式的平行流蒸发器的分支管液体流量分配情况,实验中观察到流型以环状流为主.研究发现,对于竖直向下流动和竖直向上流动,用通过增加管径的方法不能改善液体流量在各分支管的分配,而主管中气液入口的位置对于流量分配均匀性影响较大.     

高碱煤液态排渣燃烧条件下碱金属释放特性研究

采用液态排渣旋风燃烧技术可优先将煤中Na等碱金属以硅铝酸盐熔渣的形式从炉底排出,从而有效减缓燃高碱煤锅炉尾部受热面的强沾污、结渣问题。高温液态排渣燃烧条件下Na的迁移、释放特性对其在炉内渣膜的捕捉行为影响巨大。为此,在沉降炉上研究了3种典型高碱煤(地表高氯煤、将军庙煤、沙尔湖煤)在液态排渣高温热解—燃烧过程中,煤中Na的释放特性以及Ca、Fe等对Na释放行为的影响。研究结果表明：热解阶段,水溶性Na主要以Na₂SO₄、NaCl等形式释放,1 500℃下释放率为63.1%～68.6%;酸溶性Na主要通过分解或与自由基反应释放,1 500℃下释放率为64.4%～79.2%;高温下,部分水溶性Na、酸溶性Na会与灰中硅铝酸盐矿物反应转化为不可溶性Na。Ca、Fe在热解阶段对Na的释放影响并不显著;焦炭燃烧阶段,水溶性Na和酸溶性Na的释放率达95%以上,灰中不溶性Na分别为3种原煤中不溶性Na的2.64倍、2.28倍和5.6倍,表明高温液态排渣燃烧条件下,高温熔渣对Na具有一定的捕捉作用,且以不可溶性Na的形式固化于高温熔渣当中。     

气液两相流泵内气泡大小及分布规律研究

为了研究气液两相流离心泵内的气泡分布规律以及气泡大小对数值模拟的影响,采用高速摄像技术对泵内气液两相流动进行可视化试验,采用Fluent中的Eulerian模型和SST k-ω湍流模型对泵内的气液两相流动进行数值模拟.在转速为400 r/min、液相流量为10 m3/h和气相流量为0.5 L/min时,泵内流型为孤立泡...     

有机热载体锅炉导热介质超声波流量检测技术

有机热载体锅炉能效测试的关键是：住确测量高温导热介质的流量在锅炉运行条件下，利用高温超声波流量检测系统对导热介质的流量进行测量，不失为一种可靠的测量方法本文首先对高温超声波流量检测技术的原理及特点进行阐述，然后分析了运用该检测系统测量有机热载体锅炉介质流量的工艺要点，并对安装和调试方法及需要注意的问题进行了探讨，最后结合锅炉能效测试实践，给出了具体测试方法     

干式粒化熔渣余热初次回收实验研究

鉴于目前高炉渣显热不能得到有效的回收利用,以空气和水为换热介质,进行了干式粒化高炉渣显热的回收实验,研究了熔渣质量流量和空气体积流量对空气预热温度、水预热温度和余热回收率的影响.实验结果表明：随着熔渣质量的增加,空气预热温度和水预热温度均增加,同时余热回收率减小;当空气流量的增加时,虽然空气和水的预热温度都降低,但余热回收率升高.     

电弧炉用氧技术的多相流数值模拟研究

对150 t电弧炉冶炼过程中单支氧枪供氧流量分别为500,1 450,1 800,2 000 m<'3>/h时氧气射流冲击熔池进行了三维三相流数值模拟.模拟研究表明,随着供氧流量的增加,熔池中钢液和渣液的流动速度、裸露钢液面面积及射流的冲击深度均增大.由数值模拟和水模得到的供氧流量与射流冲击深度的规律得到了很好的吻合....     

Experimental study on factors that influence the diameter of dry granulated particles

The development of heat recovery methods for dry granulation processes from blast furnace slag in the iron and steel industry is limited because of the high consumption of granulation energy during these processes. To determine the factors that influence the diameter of granulated particles, a paraffin test platform for gas quenching granulation was established. The influences of air velocity, air flow rate, liquid mass flow rate, and liquid pipe diameter on the final particle size and mass distribution were studied. Experimental results showed that the final particle size decreased (from 1.07 mm to 0.81 mm) with increasing air velocity (from 28.3 m/s to 113.2 m/s). However, when air velocity was higher than 60 m/s, its influence on particle diameter decreased significantly. The experimental data were analyzed using SPSS Statistics software, which indicated that the effect of air velocity on particle diameter was the most significant, followed by those of air flow and liquid pipe diameter. The effect of liquid mass flow was the least significant.     

Experimental analysis on the effect of pipe and orifice diameter in inter tank hydrogen transfer

Hydrogen is an energy carrier which can be utilized in many sectors like stationary and transportation energy with nearly zero emission. Hydrogen energy is more efficient when compared to other energy sources. Hydrogen can be a replacement for fossil fuels in future as it emits only water when it is burned. In this work a mathematical model of transfer of hydrogen between two tanks has been developed using MATLAB simulink software version 21. Flow of hydrogen inside the pipe is controlled by orifice and diameter of this orifice and pipe diameter itself has some impact on outcome parameters such as inlet temperature of pipe, outlet temperature of pipe, heat transfer from one tank to other tank and hydrogen gas flow rate. The influence of orifice diameter as well as initial pressures on outcome parameters of hydrogen gas transfer model has analyzed in this work. From the simulation results it is inferred that when one initial pressure kept constant and other initial pressure keep on varying, no change in inlet temperature, decrease in outlet temperature, increase in heat transfer and increase in gas flow rate were observed when orifice diameter increase in size from 2 cm then 4 cm and then 6 cm. The research work has significant guidance for safety and efficient way of transporting hydrogen through pipeline from one tank to other tank.     

Dynamical and thermal performance of molten salt pipe during filling process

The dynamical and thermal performances of molten salt pipe during the filling process are numerically investigated using volume of fluid model. The whole filling process has three main stages, or the developing stage with the interface width quickly increasing, the fluctuating stage with the interface width fluctuating and the fully developed stage with stable interface, and then associated interface structures, flow and temperature fields are described in detail. Before the molten salt flows through a certain position, the fluid temperature will jump within a short time, while the wall temperature only linearly increases after that. The heat transport during the filling process is mainly dependent upon the pipe wall and molten salt flow, while natural convection outside can almost be ignored. The dimensionless interface temperature has similar evolution process under different surrounding temperatures, but it will apparently increase with the flow velocity rising. In addition, the pipe will be blocked when the interface temperature drops below the freezing point, so a model of penetration distance is derived by correlating the interface temperature evolution process, and it has a good agreement with available experimental results.     

Research on the inherent error of ultrasonic flowmeter in non-ideal hydrogen flow fields

For the widespread transmission, custody and utilization for hydrogen energy, accurate flow rate measurement is the precondition. The ultrasonic flowmeter has a prospect of wide application for the hydrogen flow measurement. To improve the measurement accuracy, this article researched the inherent error of the ultrasonic flowmeter in the non-ideal hydrogen gas flow. Computational fluid dynamics (CFD) had been used to simulate hydrogen flows downstream of the single right bend and an orifice plate at different Reynolds numbers. Based on the simulation results, this work investigated the inherent error of the ultrasonic flowmeter with different integrations and acoustic paths. The results show the errors become larger when the flowmeter position is closer to the disturbance sources. The increase in the number of acoustic paths can effectively reduce the error caused by the non-ideal flow. In the flow field downstream of the bend, the flowmeters adopting Tailored and Owics integration perform better than those with other integrations. Tchebychev and Owics integration cause less error in the front 4D (four times diameter) pipe downstream of the orifice plate, while Tailored and Owics cause less error in the rear 11D area.     

速度-高度-神经网络优化算法在水库用水计量中的应用

针对大口径非满圆型管超声波流量计量中存在精度差的问题,基于现有理论算法,提出了一种速度—高度—神经网络优化算法。首先通过多声路超声波流量计测量出圆形管道各层声路上的流速,然后通过液位计测得非满圆形管流态下的液位高度,再采用神经网络算法建立一个三层的BP神经网络,结合测得的流速、高度信息,计算出当前的流量,同时还通过高斯-雅可比数值算法确定了声路的数目及高度。仿真结果表明,该算法提高了大口径非满圆形管工况下用水测量精度。     

Flow control in a subcooled tube: an experimental investigation of the effects of crust formation

The flow control of molten liquids in tubes by manipulating the flow cross-sectional area using solidification has been investigated. Eicosane, because of its well characterised thermophysical properties, fixed melting point and known temperature dependent properties, was used as the test fluid. The eicosane data can be used to model the flow control of high temperature slag in the metallurgical industry and to verify the results of mathematical models of slag flow in tubes. Experimental results are presented in the form of pressure drop vs flow rate and dimensionless freezing parameter (Tw^*) vs flow rate. These are compared with a theoretical laminar flow model with solidification. The experimental results cover: 100 < Re < 1000, 0.3 < Tw^* < 5.4 and for cooled length to diameter ratios (L/D) of 41.9, 27.6, 26.3 and 19.8. For Tw^* < 4 the agreement between experiment and theory is within 20%. For Tw^* > 4 it was clearly observed that the experimental pressure drop is significantly lower than the theoretical predictions and can be attributed to either the breakdown of the laminar flow assumption and/or the formation of an air gap between the tube and the solidified crust.     

Investigation on ash deposition characteristics during Zhundong coal combustion

The reserves of Zhundong (ZD) coal in China are huge. However, the high content of Na and Ca induces serious slagging and fouling problems. In this study, the ZD coal was burned in a DTF (drop tube furnace), and the ashes collected at different gas temperature with non-cooling probe were analyzed to obtain the ash particle properties and their combination mode. The results showed that Na, Ca and Fe are the main elements leading to slagging when the gas temperature is about 1000 °C during ZD coal combustion, but their mechanisms are quite different. Some sodium silicates and aluminosilicates and calcium sulfate keep molten state in the ashes collected at 1000 °C. These molten ash particles may impact and adhere on the bare tube surface, and then solidified quickly. With the growth of slag thickness, the depositing surface temperature is increased. The molten ash particles might form a layer of molten film, which could capture the other high fusion temperature particles. The Fe₂O₃ sphere were captured by the formed molten slag and then they blended together to form a new molten slag with lower melting temperature.     

Flashing characteristics in a pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injection

The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two‐phase flow analysis. The following conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate M_c/M_h increased, the peak distance of the water temperature fluctuation moved from L/D = 1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. Because no problem occurred regarding the pipe material thermal fatigue, reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from the test and the analytical results, taking into consideration three factors: the depressurizing ratio in the tank; the cold water injection flow rate due to remaining subcooling; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and the drain pump. The cold water injection flow rate was minimized when the pipe length was about 15 to 20 times the pipe inner diameter. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 411–429, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10096