共查询到17条相似文献,搜索用时 46 毫秒
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利用计算流体力学模拟软件对真空膜蒸馏过程进行模拟计算.通过自行编写UDF对实验结果进行验证,模拟结果表明,在不同进料温度、进料流量以及渗透侧真空度的影响下,模拟值与实验值均高度吻合,编写的UDF可用于膜组件放大化模拟.对平板真空膜蒸馏组件进行放大设计后模拟发现,当有效过滤面积为0.25 m~2时,平板膜组件最佳长宽比为1∶2,组件内通道高度为7.5 mm,此时渗透通量为6.08 kg/(m~2·h);通过在组件内部增加隔板以加快料液互相渗透,模拟结果表明,隔板最佳高度为3 mm,隔板间距为40 mm,优化后的膜组件渗透通量达到了6.53 kg/(m~2·h),相比初始膜组件提高了10.3%. 相似文献
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《膜科学与技术》2017,(2)
利用计算流体力学(CFD)软件,构造三维计算模型,对新型的热量回收板框气隙式膜蒸馏组件内部热质传递过程进行研究.分别考察了不同进料温度、流速和操作真空度条件下模型内部流体温度分布情况.模拟结果表明:提高进料侧料液流速或者减小渗透侧真空度,在同一位置的膜表面温度均增加;渗透侧换热中空纤维从下至上壁面温度呈现递增的趋势,各层中空纤维外表面温度均存在差异,距离膜侧位置越近,中空纤维表面温度越高.研究发现,在不同条件下渗透侧底部区域的蒸汽温度大于热料液主体温度,不利于膜蒸馏过程和热量回收利用;当增加料液温度或者下游侧真空度时,有效膜蒸馏面积增大.结果揭示了新型组件内部直观的参数分布规律,为内部结构进一步优化奠定了基础. 相似文献
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Fluent是一款常用CFD流场模拟软件,在湿电进口异形扩张烟道中增设导流板,采用CFD数值模拟不同导流板和均布格栅设置方案,能优化湿电除尘器进口处烟气流场分布.该文通过比较烟道系统中不同导流板和均布格栅组合设置方案流场模拟分析,不同方案模拟分析结果的比较,选取最优组合方案,使湿电进口处烟气流场分布均匀,从而提高湿电除... 相似文献
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布袋除尘为物理除尘,滤袋的稳定使用是布袋除尘器正常稳定运行的关键因素之一,且袋除尘器阻力也逐步成为布袋除尘器的主要考核指标之一,袋除尘在使用过程中若袋除尘器内流场较差、局部高风速、各个袋室分风不均等会影响到袋收尘的收尘效率及滤袋的使用寿命。本文通过对袋除尘器改造前运行情况分析及改造需求,有针对性的进行设备改造,并通过CFD数值模拟进行验证分析,针对其特性进行流场优化设计,确保改造方案的准确性及可行性,降低设备阻力,提高滤袋使用寿命,解决布袋除尘器常见的破袋、阻力大等问题,确保布袋除尘器的正常稳定运行,从根本上解决用户痛点,满足用户需求。 相似文献
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为较好地解决流量计量检测及工业过程控制中单座调节阀的流场扰动问题,基于CFD技术并通过建立数学模型的方法,对管道水平安装方式下流体流过单座调节阀时的流速分布(指阀前及阀后直管段中的流速分布)进行了数值模拟研究,得到了相同开度不同流量及相同流量不同开度下距离单座调节阀不同的位置处的流速分布(沿管道径向的垂直于管道的流速分布),分析了单座调节阀对流场扰动产生的原因。结果表明,单座凋节阀对其前直管段流体的扰动较小,对其后直管段流体流场的扰动不仅与单座调节阀的开度及流过单座调节阀的流体流量有关,而且与单座调节阀后直管段的长度有关;在此基础上,提出了削弱流场扰动对流量计计量性能影响的方法,该方法为易受流场扰动的流量计的安装、装置的设计及计量检定等提供了有力的参考依据。 相似文献
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用计算流体力学(CFD)方法模拟了桥梁跨中断面周围的风场特征,不仅能得到流场的压力、速度和涡旋的分布,还提取了箱梁断面的三分力系数。分别采用不同密度网格划分对主梁断面进行数值模拟,并将数值模拟结果与风洞试验值进行比较,选取最合理的网格划分方法。然后,对某一大跨度桥梁跨中断面的箱梁模拟了从-5°至+5°共11个整数度风攻角工况的三分力系数。并将数值模拟结果与风洞试验进行了对比,给出了不同攻角下的压强和速度分布,验证了采用CFD技术模拟桥梁三分力系数方法的可行性与可靠性。 相似文献
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对太阳能膜蒸馏热工质加热系统进行了简化,建立加装导流板的全玻璃太阳能膜蒸馏热工质加热系统的物理模型,该模型包括全玻璃太阳能集热系统和膜蒸馏热腔两部分,提出二者的耦合集成点,得出耦合边界条件及其非稳态流动的设定方法,建立了太阳能膜蒸馏系统的三维非稳态CFD(计算流体动力学)计算模型,得出求解方法及思路,得到太阳能集热器联接管出口流体温度和流量的变化规律,与膜蒸馏热腔模型耦合计算,得出非稳态情况下膜通量与太阳能辐照强度的变化规律,为下一步太阳能利用与膜蒸馏的耦合优化奠定基础. 相似文献
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High frequency operation of standing wave thermoacoustic heat engines is attractive for space applications due to compact size and high reliability. To expedite practical use, further improvement and optimization should be based on deep understanding and quantitative analysis. This article focuses on using computational fluid dynamics (CFD) to investigate nonlinear phenomena and processes of a 300 Hz standing wave thermoacoustic engine (SWTE). The calculated model was tested in detail, which indicated that the co-axially stacked tube model was suitable for the simulation of SWTEs. Two methods of imposing temperature gradient across the stack were studied, and the processes of mean pressure increasing, pressure wave amplification and saturation were obtained under the thermal boundary condition of applying heating power. The acoustic fields were given, and the flow vortices and their evolution in both ends of the stack and resonator were observed. Moreover, a comparison between the simulation and experiments was made, which demonstrated the validity and power of the CFD simulation for characterizing complicated nonlinear phenomenon involved in the self-excited SWTEs. 相似文献
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《Advanced Powder Technology》2020,31(4):1748-1758
The objective of the present study is to propose a novel design to improve the separation efficiency of the conventional square cyclone. For this purpose, the conical section of the conventional square cyclone with single-cone is modified to dual inverse-cone. In addition, the effect of second-cone length on the performance of cyclone is considered. A three-dimensional numerical simulation is done by solving the Reynolds averaged Navier-Stokes equations with the Reynolds Stress Model (RSM) turbulence model and applying the Eulerian-Lagrangian two-phase method. The turbulent dispersion of particles is predicted by the application of the Discrete Random Walk (DRW) model. The numerical results demonstrate that dual inverse-cone square cyclone although produces higher pressure drop but its separation efficiency is higher than the square cyclone with single-cone. This is due to a smaller separation zone and shorter path of particle movements which force the particles exit from the outlet section of the cyclone. Finally, using dual-inverse cone square cyclone reduces the 50% cut size about 10% and 30% for inlet velocities of 12 m/s and 28 m/s, respectively. 相似文献
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Zhanpeng Sun Longlong Liang Chunyu Liu Yufeng Zhu Linlin Zhang Guang Yang 《Advanced Powder Technology》2021,32(4):977-986
A new horizontal turbo air classifier equipped with two inclined air inlets has been introduced. The flow field and classification performance of the classifier have been investigated using CFD method and response surface methodology (RSM). Simulation results show that the flow field is composed of the primary swirling flow and the secondary upward washing air, and the uniformly distributed swirling flow occupies the classifying chamber. The tangential gas velocity reaches the maximum value on the outer surface of the rotor cage, generating strong centrifugal force for the particle classification. The discrete phase model (DPM) can predict the cut sizes, but cannot present the fish-hook phenomenon. The desirable experimental condition by targeting the cut size of 20 μm and minimizing the classifying accuracy index is, rotor speed of 1373.6 rpm, primary air volume flow rate of 261.8 m3/h and secondary air volume flow rate of 42.4 m3/h. The corresponding fine and coarse fraction loss are less than 1.42% and 7.24%, respectively. This study provides a new strategy to design the horizontal turbo air classifier. 相似文献
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Segregation of binary particle mixture in a rotating drum is numerically studied using the Eulerian multiphase computational fluid dynamics (CFD) simulations coupling the solid phase kinetic theory of granular flow model. The corresponding solid kinetic viscosities of the two particulate phases are determined by the previous granular bed surface fitting (BSF) method. The effects of the specularity coefficients used in the simulations on the segregation patterns in the rotating drums are systematically studied by using the specularity coefficient values ranging from 0.15 to 1.0. When using a smaller specularity coefficient value in the simulation, the momentum transferring from the drum wall to the particulate phase is poorer, lowering the kinetic energy of the particulate phase. The lower particulate phase kinetic energy causes slower particle motion in the bed and hence delays the segregation core/band formation. At the same simulation time, the concentration of the smaller particles in the segregation core increases with the increasing of the specularity coefficient value used in the simulation. When the specularity coefficient values larger than 0.4 are used in our simulations, the realistic three-dimensional segregation structures are well predicted. A proper specularity coefficient value should be adopted in Eulerian multiphase CFD simulations of granular flows. 相似文献
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An experimental cold-model of a simplified tangential firing boiler was established to investigate the mesoscale turbulent flow behaviors, including gas vortex structures, particle motions and interactions between two phases. A modified PIV technology, employing two pairs of lasers and cameras, was applied to measure the velocity and velocity gradient of turbulent flow in foursquare tangential jets alternatively. At a given initial gas velocity and particle mass loading, the interaction between gas and particles was studied at three different particle sizes. It was found that two main coherent vortex structures, circular eddy and hairpin eddy, distributed mainly in low speed area and heavy impingement area, respectively. The characteristics of particle motion in foursquare tangential jets correlated with gas turbulence dissipation, particle size, particle concentration and particle density. Small particles were easily entrained by gas vortex, so that they consumed more turbulence energy and attenuated the gas turbulence intensity. On the contrary, large particles had more inertia and led to heavier impingement in the chamber center, resulting in particle random distribution and complex momentum transfer between gas and particles. Moreover, large particles stretched the coherent vortex to be narrow and long, while small particles pulled down the vortices rotation intensity. 相似文献