颗粒物料传热传质过程的数值仿真与实验研究

转筒干燥器的主体是略带倾斜并能回转的圆筒体，是一种既受高温加热又兼输送的设备，它的应用十分广泛。该文较为系统地进行了转筒干燥器物料的传热传质过程的分析，并进行了试验研究。利用质量平衡方程、能量平衡方程、传热方程和传质方程，建立了颗粒物料在转筒干燥器干燥过程中的传热传质数学模型，该模型能够较好地预测干燥过程中物料颗粒的温度和含湿量的变化，仿真结果与实验结果吻合良好。该仿真程序对此类问题的研究具有参考价值。     

基于兰姆波谐振器和超表面的谐振式热红外探测器研究

设计了一种基于氮化铝(AlN)兰姆波谐振器和超表面的谐振式热红外探测器,基于超表面的吸收器用于对特定波长红外辐射的吸收,再利用AlN兰姆波谐振器的温度频率效应检测红外辐射。首先,对兰姆波谐振器的电极周期、电极宽度、AlN薄膜厚度和支撑轴尺寸进行优化设计,设计了电极周期分别为12μm和1.2μm的谐振器结构,其工作频率分别为365 MHz和2 544 MHz。其次,设计了方形结构超表面的等离子体吸收器,并研究分析其红外吸收机理及结构尺寸对吸收性能的影响规律。通过集成超表面红外吸收器并调节吸收结构尺寸,实现可调谐、近100%的双带吸收性能,在3μm～5μm和8μm～12μm处的吸收率均超过99.5%,谐振式热红外探测器的响应时间低于0.8 ms、热噪声等效功率低于10^-11 Hz/μW。     

喷雾干燥自动控制改进方案的设计及运行

喷雾干燥是一个传热传质过程,自控的目的旨在保证质量(主要指成品粉湿含量)、安全和节省油耗。杭州万里化工厂洗衣粉喷雾干燥过程1982年实现了自控。其方案见图1,包括:干燥塔温度串级控制和加热炉的燃烧油与雾化蒸汽配比调节。自控后取得了一定的经济收效。该系统经一年多的运行发现其中的温度串级控制有些不足之处,因而1983年作了改进,使自控系统在相当恶劣的条件下维持长期运行,并取     

基于神经网络的回转窑建模及其优化控制设计

实现水泥回转窑温度稳定性控制,水泥回转窑熟料煅烧是一个涉及传质、传热和物理化学反应的复杂多变量、多扰动非线性过程。为了稳定回转窑烧成温度以提高孰料烧成质量,降低能耗,传统的控制方法,存在干扰大,稳定时间长等问题。在分析水泥回转窑工艺的基础上,采用Elman神经网络建立回转窑系统的模型,提出BP神经网络的PID控制方法,根据系统的运行状态,调节PID控制器的参数,以达到性能指标,设计了回转窑温度优化控制器,具有超调量小、动态性好、收敛速度快和控制精度高等优点。进行仿真的结果表明,回转窑烧成带温度逐渐趋于稳定,实现了对水泥回转窑的优化控制。     

高空台喷雾水滴运动轨迹及流动换热规律数值研究

高空台因其结构特殊,喷雾参数测量较为困难.为探究喷雾水滴在高空台内的运动和传热规律,对喷雾水滴在高空台内的运动和沿程的传质传热过程进行了分析,采用仿真计算的方法,建立了相应的数学物理模型,发展了适用于求解高空台内喷雾水滴沿程速度、温度和粒径的计算方法,可预测水滴沿程相关参数随运动时间和路程的变化规律.通过数值计算结果表明,适当延长试验舱通道长度,可提高水滴的跟随性;气流参数对水滴运动轨迹存在一定影响;喷雾水滴运动过程中的传质传热作用对于水滴沿程粒径变化影响较为明显.研究结果为高空台进行进气结冰试验提供了理论依据.     

降膜蒸发过程的数值模拟和传热传质分析

利用CFD软件对逆流降膜蒸发过程进行了实验模拟研究,研究了速度边界层、热边界层和浓度边界层的变化对降膜蒸发传热传质特性的影响规律;通过建立一维逆流降膜蒸发的数学方程编程求解出了对流传热传质的Nu数和Sh数,利用Fluent软件模拟出的实验结果采用回归分析得出了气液流量比Raw、流道的长宽比αL、空气进口无量纲温度θai以及空气进口Re数与Nu数、Sh数之间的无量纲关系式,可为降膜蒸发换热器的设计提供参考。     

模拟移动床色谱分离体系模式与关键因子的计算机模拟研究

采用浮点编码遗传算法对模拟移动床色谱的分离系统模式进行了设计,并研究了,分离过程中传质和扩散对分离效果的影响。结果表明模拟移动床色谱中区2和区3的色谱柱的数目对提高生产强度起决定性的作用,而区1和区4的影响较小。同时改善分离过程中的传质与扩散可提高生产强度,在分离过程中传质所起的影响比扩散大得多。     

基于工业脱硫塔数值仿真的喷淋速度控制研究

研究工业用脱硫塔内的烟气流动轨迹优化控制问题,以准确控制脱硫液体的喷淋速度。在脱硫塔中对烟气进行脱硫液体喷淋时,受喷淋液体的冲击使得塔内液滴轨迹突变,运动轨迹特征极难被捕获,传统仿真方法无法有效捕获突变的液滴轨迹,造成SO2吸收识别不准确,不能准确控制喷淋速度。为此,提出采用统计分析法的数值仿真方法,选用液滴的路径特征来追踪液滴轨迹,并在Euler坐标系下处理流体相,根据统计分析法实现脱硫塔内的烟气液滴的数值仿真,通过建立SO2吸收模型,根据SO2吸收特性控制脱硫液体的喷淋速度。实验表明,改进方法能够有效捕获突变液滴的运动轨迹,完成脱硫塔内的烟气流动轨迹特点仿真,构造SO2吸收模型并准确控制脱硫液体的喷淋速度。     

平板式固体氧化物燃料电池的建模与仿真研究

基于气流模型以及热模型利用流体力学计算软件Fluent,建立平板式固体氧化物燃料电池（SOFC）的计算流体力学（CFD）模型。模型中采用电化学反应控制方程、质量、动量和能量守恒方程描述电池内的传热传质等物理过程,并对电池内部的运行电压、温度以及各种极化分布情况,进行了数值模拟。研究给出了顺流平板型SOFC与逆流平板型SOFC情况下,运行电压、温度和极化的分布。结果显示逆流平板型SOFC可获得更好的性能,具有更大的电功率密度和燃料利用率。     

蒸发冷却器的流场仿真与优化设计

针对蒸发冷却技术相关理论模型并未完全成熟的问题,通过计算流体力学方法模拟转炉煤气干法除尘系统中蒸发冷却器的工作过程.仿真采用离散相模型（Discrete Phase Model,DPM）,并在分散相液滴上应用蒸发换热模型.通过该数值方法优化该干法除尘系统中蒸发冷却器的喷淋布置方案,减少壁面的高温区域,提高温度的均匀性,使出口最高温度偏差由18.6%降低至3.4%.     

薄壁金属管吸能器的吸能特性分析

通过对薄壁金属管吸能特性的数值模拟总结出关于薄壁金属的吸能特性,利用吸能器的吸能能力、平均压溃载荷和理想吸能效率等3个吸能评价指标,对薄壁金属管的吸能特性进行综合评估;在此基础上,提出针对薄壁金属管吸能器的优化方案.通过对比分析可知,优化后的方案可以大大提高吸能器的理想吸能效率,减小缓冲力在工作过程中的波动.     

Effects of an absorber on impact characteristics in machine cushion design with area ratio modified guiding structure

A machine cushion with guiding structure can transfer impact and vibration waves into branches of balanced forces along pre-designed paths, to reduce the effects of those waves between the machine and the ground. To improve impact load absorption and vibration wave suppression, we designed a machine cushion with an attached absorber and “area ratio modified” (ARM) guiding structure. We compared variations in vibration using impulse responses of machine cushions as a performance index, of four alternative machine cushion designs: One was an ARM with absorber design; the second was the same machine cushion but without an absorber; the third and fourth were simple passive machine cushions with and without an absorber. The related dynamic equations for these structures were derived and the related transient responses and frequency responses were evaluated. The main objectives of the study were to demonstrate the capacity of our ARM with absorber structure to absorb impact forces and vibration waves, and to measure the effect of parameter variation on the absorption of impact forces and vibration waves. As expected, simulation results showed that under test conditions, the proposed ARM with absorber machine cushion had the best impact and vibration suppression capability.     

A photoexcited switchable tristate terahertz metamaterial absorber

In this study, we propose a photoexcited tristate terahertz metamaterial absorber which can switch between single‐/single‐/dual‐band absorption modes in terahertz regime. The unit cell of the absorber incorporates two kinds of photosensitive semiconductor materials filled the gaps between four asymmetric right‐angle wires and a cross wire. By applying different wavelengths of pump light on the absorber, two kinds of semiconductor materials can be excited to realize single‐/single‐/dual‐band switchable absorption characteristics. The distributions of electric fields and surface currents at absorption peak frequencies under three absorption states are demonstrated to elucidate the switchable mechanism of the proposed absorber. Moreover, the absorption performance of the proposed tristate absorber is discussed under different polarization and incidence angles. The proposed structure is expected to be applied in the terahertz devices such as tunable absorbers, modulators, filters, and switches.     

Transfer technology using inorganic separation layer and apparatus for fabricating flexible OLED displays

We established a fabrication process of flexible displays, adopting a transfer technology using an inorganic tungsten‐separation‐layer. Our separation process requires physical force and water. Tungsten oxide over tungsten in the separation layer plays a key role in separation: water injection into the tungsten oxide reduces the force necessary for separation. In this study, we describe the apparatus we built for the fabrication process of flexible displays. This apparatus fabricated an 8k (7680 × 4320 effective pixels) flexible organic light‐emitting diode display.     

Investigation on pressure drop characteristic and mass transfer performance of gas–liquid flow in micro-channels

Pressure drop characteristics and mass transfer performance of gas–liquid two-phase flow in micro-channels with different surface wettabilities were experimentally investigated. Side-entry T micro-channel mixers made of glass and polydimethylsiloxane were tested. Frictional pressure drop was found to decrease as the hydrophobicity of the channel surface increased. The flow patterns observed in the experiment were classified as slug flow and continuous gas phase flows. The modified Hagen–Poiseuille equation and Lockhart–Martinelli model were developed to predict the pressure drop for these two types of flow, respectively. The effect of surface wettability was heuristically incorporated in the present models which can correlate well the experimental results. Mass transfer performance was studied by the physical absorption of oxygen into de-ionized water. The results show that the volumetric mass transfer coefficients in hydrophobic micro-channels are generally higher than those in hydrophilic ones. The empirical correlations of overall volumetric mass transfer coefficients were proposed.     

煤与矸石在线分选系统设计

针对目前常用的原煤洗选方法存在设备复杂、需要大量的水等问题,设计了一种基于双能γ射线和数字图像识别技术的煤与矸石在线分选系统。单片机实时判断探测器下方的物料是煤或者是矸石,当判断为煤块时,喷枪无动作,煤块落入煤通道;当判断为矸石时,单片机控制喷枪喷出高压气体,将矸石吹入矸石通道;当有些煤中含杂质较多或者矸石含碳量较高时,则由图像识别模块根据煤与矸石在灰度上的差异来区分煤与矸石,并将识别结果传送给单片机。模拟实验结果表明,该系统能有效识别煤与矸石,识别精度满足工业生产要求。     

Simulation of carbon dioxide absorption process by aqueous monoethanolamine in a microchannel in annular flow pattern

The process of carbon dioxide absorption by aqueous monoethanolamine solvent was simulated in a microchannel in an annular flow pattern. This simulation has been carried out as a multiphase and three-dimensional process. The effects of different operating parameters such as temperature, superficial gas and liquid velocities, aspect ratio, and concentrations of solvent and solute have been investigated on the mass transfer flux and carbon dioxide conversion. The results of simulating mass transfer flux based on the calculated mass transfer coefficient were well consistent with the experimental data. The result of this study indicated that the mass transfer flux shall increase with the superficial gas and liquid velocities, temperature, concentration of solvent, and increment in the aspect ratio. It also revealed that increasing the concentration of solute would lead to an increase in the mass transfer flux and a decrease in the conversion.     

Polarization independent broadband metamaterial absorber for microwave applications

A new polarization independent broadband metamaterial absorber (MA) structure based on split ring resonators which are loaded with lumped elements and via connection lines is proposed. The designed structure shows a perfect absorption between 4 and 16 GHz which is validated by simulation studies. Experimental study is only made for the structure that has no via connections and no the lumped element resistors to show the importance of these entities in the proposed metamaterial structure. Both numerical and experimental study results show that broadband MA property depends on the resistors and via connections on the proposed structure. By having high absorption in a wideband range which is numerically demonstrated, the proposed structure can be used in energy harvesting or wireless power transfer applications with higher efficiencies.     

Broadband transparent metamaterial absorber in wireless communication band based on indium tin oxide film

In this article, a broadband optically transparent metamaterial absorber in wireless communication band is proposed. Indium tin oxide (ITO) film, a kind of resistive transparent thin film, is utilized to construct the absorber unit to realize optical transparency, and increase ohmic loss to broaden the absorption bandwidth. The proposed absorber is fabricated and measured. The measurement results are in good agreement with the simulations. It is demonstrated that the absorption rate of the proposed absorber is higher than 90% from 1.67 to 3.8 GHz. The full width at half maximum bandwidth is 5.11 GHz from 0.89 to 6 GHz. In addition, the absorption response of the absorber remains stable regardless of polarization and incidence angle of the electromagnetic waves.