动水条件下含沙量对分离鳃水沙分离效率的影响

为探明含沙量对分离鳃水沙分离效率的影响,运用物理模型试验方法,对分离鳃和普通管开展了同一浑水进口流量下4组不同含沙量的水沙分离试验。试验结果表明,分离鳃中存在垂向和横向异重现象;当浑水进口流量为0.9m~3/h时,含沙量为10、30、50、80kg/m~3条件下,分离鳃的水沙分离效率均高于普通管;不同含沙量条件下分离鳃的水沙分离效率随时间的变化规律不同,当含沙量为10kg/m~3时,包含缓慢增大、快速增大、缓慢增大3个阶段,而其他含沙量时仅有缓慢增大阶段,且含沙量为10kg/m~3的水沙分离效率分别为30、50、80kg/m~3的1.13～3.81、1.34～3.99、1.61～5.77倍。     

不同进口位置下分离鳃的水沙流场数值模拟

为研究进口位置对分离鳃内水沙流场的影响,运用CFX软件并采用混合物模型和RNG κ-ε模型,对不同进口位置分离鳃的速度场及浓度场进行动水条件下的数值模拟。结果表明,相对于进口1、2、4,进口3分离鳃内部环境较为稳定,形成的异重流更明显;动水环境中,过滤出的清水循环位于远离进口的区域,在底部进口的分离鳃中,清水层位于分离鳃的上部,更有利于出口处清水的排出;动水条件下,进口位置位于底部的分离鳃在清水出口剖面上的泥沙体积分数最低,即分离鳃的水沙分离效率最高,达到72.45%,且分别是进口1、2、4的2.10、1.71、1.17倍。     

含沙量对分离鳃的水沙分离影响试验

为研究含沙量对分离鳃水沙分离效果的影响,通过对分离鳃与普通管进行9组不同含沙量的静水沉降试验,运用粘性颗粒的沉降特性分析了含沙量与沉速的关系。结果表明,含沙量对泥沙沉速影响很大,含沙量越大,泥沙下沉相同距离时所需的沉降时间越长,泥沙的沉速越小;在同一含沙量下分离鳃的沉速始终大于普通管沉速,当含沙量为10~80 kg/m3时,分离鳃沉速更大,水沙分离效果最佳。     

梭锥管混浊流体分离装置转角优化数值模拟研究

基于PIV实测的梭锥管内水沙两相流场的流速资料,对拟采用的数学模型及其参数进行了试算和比较,选出符合梭锥管内水沙两相流动的数学模型及其参数。建立了10种不同转角的梭锥管模型,模拟计算了泥沙平均粒径为0.045mm、含沙浓度为5kg/m3时各梭锥管内部的泥沙浓度和速度场,对比分析了不同转角下梭锥管内的速度场和浓度分布特性。结果表明,经过相同时间分离并沉降至梭锥管底部的泥沙平均体积分数值随转角的增大先增后减,在40°α45°范围内达到峰值,水沙分离效率最高;靠近清水溢流口附近的泥沙浓度随转角的增大先减后增,在40°α45°范围内达到最小值,即在该角度范围内,随水流上升的泥沙量最少,溢出水流的含沙量最低。     

两种新型分离鳃沉淀池沉淀试验及沉降效果研究

采用试验方法分别对封闭式与敞开式分离鳃沉淀池进行静水和动水的水沙分离沉降试验,发现两种沉淀池在静水沉淀时出水浊度随时间变化可分为浊度迅速减小阶段和浊度缓慢减小阶段;在动水沉降时,水力负荷对浊度变化有很大的影响,水力负荷愈小出水浊度值愈小,当水力负荷达到一定值时两种沉淀池里的分离鳃将失去作用,与普通沉淀池处理效果相同;但总体上封闭式分离鳃沉淀池的净水效果优于敞开式分离鳃沉淀池。     

加压液化输沙技术在浑水水力分离清水装置中运用的数值模拟

为解决浑水水力分离清水装置因高度问题难以应用的问题,采用重整化群两方程紊流（RNG κ ε）模型和简化的多相流混合模型,对应用加压液化输沙技术前后的浑水水力分离清水装置的水沙两相三维流场进行了数值模拟,并由FLUENT软件分析了运用加压液化输沙技术前后装置内部流场泥沙分布变化。结果表明,加压液化输沙技术在一定压力水头作用下,可避免装置锥体底部的泥沙淤积,说明该技术可解决装置由于降低锥体高度出现的底部泥沙淤积问题,为降低装置设计高度提供了理论依据。     

不同鳃片倾斜角下的分离鳃内部流场三维数值模拟

为研究鳃片倾斜角α、β对分离鳃水沙流场的影响,采用均匀试验设计理论设计数值模拟方案,通过采用Fluent软件提供的层流模型和欧拉模型,计算了不同鳃片倾斜角下的速度流场,并分析了鳃片上表面的泥沙受力情况和运动轨迹,初步探明了分离鳃水沙分离的力学机理,获得了不同鳃片倾斜角下分离鳃的速度流场分布规律。     

轴流式旋风分离器结构与分离特性数值模拟

依据轴流式旋风分离器的基本结构建立分析模型,通过CFD-DEM耦合计算获得运行时内部流场主要参数以及颗粒分布,提取了影响分离性能的主要结构参数,研究其在不同粒径、不同进口速度下与分离效率和压降的关系,并给出了分离效率与各参数的拟合关系式。结果表明：叶片出口角和排气管直径对轴流式旋风分离器的分离效率有显著影响,随着叶片出口角减小,静压逐渐增大,切向速度增大,同时分离效率提高;排气管直径增大,静压减小,当其为分离器筒体直径的0.6~0.7倍时分离效果最好;流速为20 m/s时,对4 μm的颗粒分离效率可达到92.3%,10 μm及以上颗粒可实现100%分离;并使用加权方法给出了在粒径dp≥4 μm,进口风速为4~20 m/s的工况下适用的分离效率计算模型。     

燃气轮机惯性级分离装置的分离特性研究

在25和33 mm两种导叶间距、进口流速分别为2.5、3.0和3.5 m/s的工况下,对燃气轮机的惯性级导叶进行盐雾分离特性的研究。首先由实验得出该惯性级导叶的分离特性数据,再通过离散相数值模拟定性分析装置流道内分离盐分的主要机理和影响分离特性的因素。比较实验数据和数值模拟结果得出:该惯性级分离装置分离效率约为97%,最大值为98.71%,最小值为95.90%,接近完全分离效果;导叶间距增大分离效率会有下降,分离效率会随初始进口速度增加有提升。     

初始浑水含沙量对沉淀池中流速分布的影响

为研究初始浑水含沙量对河水滴灌重力沉沙过滤池中沉淀池内流速分布规律的影响,对5种不同初始浑水含沙量下沉淀池内的水沙两相流流场进行了数值模拟。通过对比分析不同初始浑水含沙量下流速沿水流方向和沿水深方向的分布规律,可知不同初始浑水含沙量下浑水流速沿水流方向变化规律与水深方向不同;但初始浑水含沙量越大,流速沿水流和水深方向增加或减小的幅度也就越大,越容易在沉淀池尾部形成较大回流,从而导致水流将部分泥沙带出沉淀池,使沉淀池的水沙分离效率降低。     

石灰石一石膏湿法脱硫系统石膏旋流器分级效率的研究

针对提高脱硫效率和石灰石利用率、提高产品品质和降低厂用电率等问题,从优化分级效率的角度探索提高石膏旋流器性能的方法．采用试验的方法,寻找石膏旋流器结构和工作参数对分级效率的影响规律．结果表明：较高的入口压力、适中的溢流管壁厚和内径、较大的溢流管插入深度以及选用渐缩式阿基米德螺旋线入口结构等因素对石膏旋流器的分级效率有积极效果．     

Dynamic process of hydrogen and heat generation from reaction of Al–Li alloy powders and water vapor at moderate temperatures

As one of the alternative clean fuels, aluminum is suitable for generating hydrogen and power via metal hydrolysis. The reaction process characteristics were studied in a cylindrical reactor with 5 g of Al–Li alloy powder as fuel at moderate temperatures. The test performed good results with 1,130 mL/g alloy of H₂ yield, 86% of the reaction efficiency, and 54.5% of usable heat ratio. The dynamic change of temperature distribution was measured by 12 thermocouples in the reactor, and the maximum was not beyond 892°C. On the basis of the temperature characteristics, the reaction propagation speed was calculated and in the range of 0.57–0.95 mm/s. Moreover, the micromorphology and ingredients presented obvious differences between top product and bottom product, which was resulted from water vapor diffusion. The reaction of Al–Li alloy and steam was determined by both water vapor diffusion and heat transfer, which led to the distinct temperature trends near the vapor inlet, away from the vapor inlet, on the top and at the bottom. On the basis of the results, a mild and controllable hydrogen generation can be achieved at moderate temperatures by optimizing vapor inlet arrangement.     

小直径水滴分离特性的试验研究

针对湿法脱硫、烟气余热利用、湿法除尘等工业实践中常见的气流携带小直径水滴的分离特性进行了试验研究。分析了水滴的惯性分离机理以及各个因素对分离效率和流动阻力的影响。对正交实验的结果进行了正交实验的直观分析,理论分析与实验结果基本吻合。实验表明:在保证分离效率的前提下,含有小直径水滴的气体通过槽形或角形分离件时的流动阻力较小,其最大值不超过70Pa。实验结果对于低压降的小直径水滴分离设备的工程设计具有一定的指导意义。     

方形分离器结构优化试验研究

在冷态试验台上对特征尺寸D=300 mm的入口带加速段的方形分离器进行结构优化研究。结果表明:分离效率随着芯筒直径(d)、芯筒插入深度(s)的增大均呈先增大后减小的趋势;入口高宽比(a/b)与直段高度(h)对分离效率的影响存在交互作用;随着a/b的增大,分离效率先增大后减小;不同入口高宽比时,分离效率随直段高度的变化趋势不同,当a/b>5.92时,随着直段高度的增大,分离效率先减小后增大,在h/D=2.3时最低;当a/b<5.92时,分离效率随着直段高度的增大而减小;分离器阻力随着入口高宽比的增大而增大,随着直段高度的增大而减小。4个参数的最优值分别为:d=0.4D、s=0.6D、a/b=8和h=1.8D,此时对应的分离器阻力为1.22 kPa。     

MASS FLOW RATE DISTRIBUTION AND PHASE SEPARATION OF R-22 IN MULTI-MICROCHANNEL TUBES UNDER ADIABATIC CONDITION

The present study investigated mass flow rate distribution and phase separation of R-22 in multi-microchannel tubes under adiabatic condition. The test section consisted of inlet and outlet headers with the inner diameter of 19.4 mm and 15 parallel multi-microchannel tubes. Each microchannel tube had 8 rectangular ports with hydraulic diameter of 1.32 mm. The key experimental parameters were the orientation of the header (horizontal and vertical), flow direction of refrigerant into the inlet header (in-line, parallel and cross flow), and inlet quality (0.1, 0.2, and 0.3). The effect of inlet quality on the mass flow rate distribution and phase separation in the microchannel tubes was negligible. The effect of the orientation of the header on the mass flow rate distribution and phase separation was the largest among the test parameters. Horizontal header showed better mass flow rate distribution and phase separation characteristics than vertical header. Both parallel and cross-flow conditions showed better mass flow rate distribution and phase separation than in-line flow condition.     

Experimental investigation of energy separation in a counter-flow Ranque–Hilsch vortex tube with multiple inlet snail entries

The energy/temperature separation phenomenon and cooling efficiency characteristics in a counter-flow Ranque–Hilsch vortex tube (RHVT) are experimentally studied. The ascertainment focuses on the effects of the multiple inlet snail entries (N = 1 to 4 nozzles), cold orifice diameter ratios (d/D = 0.3 to 0.7) and inlet pressures (P_i = 2.0 and 3.0 bar). The experiments using the conventional tangential nozzles (N = 4), are also performed for comparison. The experimental results reveal that the RHVT with the snail entry provides greater cold air temperature reduction and cooling efficiency than those offered by the RHVT with the conventional tangential inlet nozzle under the same cold mass fraction and supply inlet pressure. The increase in the nozzle number and the supply pressure leads to the rise of the swirl/vortex intensity and thus the energy separation in the tube.     

Numerical investigations on flow characteristics and energy separation in a Ranque Hilsch vortex tube with hydrogen as working medium

In the last decades, the theory of energy separation in vortex tubes is debated broadly based on the heat transfer and work transfer between core and peripheral flow layers. Many parameters were considered in the literature. However, the present study involves the inlet energy considered collectively towards energy separation. In this paper, three-dimensional computational fluid dynamic simulations are discussed in vortex tube to analyze the energy separation phenomena in different cases by varying the working medium such as hydrogen and air having specific heat variation. The energy at the inlet is maintained same in both cases by adjusting the inlet mass flow rate. The results from this study are validated with recently published literature using hydrogen as a working medium. Vortex tube with hydrogen as working medium yields a temperature separation of 8 K lower than air as working medium. Further studies on vortex tube with hydrogen as a working fluid is explored at different inlet temperatures relative to the room temperature. Vortex tube with hydrogen at an inlet temperature of 400 K gives better temperature separation as compared to other inlet temperatures considered in this study.     

不同结构因素下方形旋风分离器分离性能的实验研究

通过改变分离器进气形式、排气芯管形状、管径及布置方式，对方形分离器的分离性能进行了实验研究。结果表明：正切向进气形式优于斜切式；排气管直径是重要的结构参数，且方排气管的分离性能要优于同等排气面积的圆排气管。研究结果为方形分离器结构的优化设计提供了依据。图5表4参6