湿法脱硫系统中折板式除雾器压降数值模拟

采用CFD软件对折板式除雾器的流场进行数值模拟.建立了数学模型,对气体相采用基于雷诺时均方程的SST κ-ω湍流模型封闭N-S方程,对液滴相采用基于Euler-Lagrange的DPM方法.通过改变除雾器的结构参数板间距和工作参数进口气速模拟气液两相流场,分析这两种参数对压降的影响,这对折板式除雾器的优化设计有一定的指...     

湿法脱硫系统弧形板带钩除雾器流场数值模拟与分析

采用计算流体力学方法对除雾器内流场进行数值模拟.除雾器内气液两相流动的数值计算主要用基于欧拉-拉格朗日方法的离散相模型.流体被当做连续相,其流场可通过时均N-S方程求得,而离散相液滴的轨迹则可通过已经计算的流场追踪得到.通过计算不同工作参数下除雾器的除雾效率和压降,分析并总结了不同参数对除雾效率和压降的影响规律,对除雾...     

折线型与流线型除雾器性能的数值模拟与分析

采用Fluent软件对折流板除雾器内气液两相流动进行数值模拟,分析了不同除雾器型式、叶片转折角对除雾器的分离效率和压降的影响。计算结果表明：Fluent软件可以成功地处理两相流动问题,为除雾器优化设计提供参考依据。     

一种具有负荷适应性的波纹板除雾器

采用低雷诺数k-ε模型,对带钩波纹板除雾器进行多工况数值模拟,通过大量的尝试、比较和筛选,得到高效带钩波纹板除雾器的结构参数。在此基础上,提出一种钩片可调的负荷适应性除雾器,并结合典型300MW火电机组脱硫除雾系统开展定量计算与案例分析。研究表明:新型除雾器在机组负荷或煤种发生变动时,仅通过调整钩片偏转角度即可使除雾效率平均提高4.10%,并且机组负荷偏离额定工况越多,钩片偏转角度的调整对除雾效率的改善效果越明显。最终建立钩片偏转角度与机组负荷及燃料成分等参数的定量关系。     

涡流空气选粉机分级性能模拟预测与实践结果的比较

利用计算流体力学CFD(Computational Fluid Dynamics)商用Fluent软件对涡流空气选粉机内部气固两相流动过程进行了数值模拟研究,采用三种方法(细粉收率法、Tromp曲线法及成品R-R粒度分布曲线法)对选粉机性能进行评价,并同实际标定结果进行比较,最后分析风量和转速对选粉机分级性能的影响。结果表明:(1)模拟预测曲线与实践结果基本吻合,验证了CFD技术在涡流空气选粉机研究过程中提供信息的可靠性,为进一步拓展CFD技术在选粉机领域中应用提供佐证;(2)转子转速对成品细度的影响远大于风量对成品细度的影响,同风量下转速降低14.3%,成品中大于60μm粗颗粒增加3.42倍,而同转速下风量增加59.5%,成品中大于60μm粗颗粒仅增加17.9%。     

不同波纹夹角的人字形板式热交换器数值模拟

建立了由波纹夹角60、120°人字形板片组成的3种换热流道的主换热区模型,利用计算流体力学软件对3种流道内流体的流动和传热进行了数值模拟,分析了流道内的速度场、温度场和压力场。结果表明:人字形波纹的夹角是影响板片间流体流动形态的因素之一,流道的换热性能和压力损失均随人字形波纹夹角的增大而增大,并且波纹夹角的改变对流道压力损失的影响比换热性能更明显。     

螺旋折流板换热器壳程流体流动的数值模拟

在对螺旋折流板管壳式换热器结构和操作条件进行简化的基础上,采用计算流体动力学分析方法建立数学模型,并利用CFD分析软件FLUENT模拟换热器壳程流动特性,得到了换热器壳程流场分布的直观信息。对流体传热特性做了初步探讨,并比较了弓形折流板换热器和螺旋折流板换热器的流动特性,为这种换热器结构的优化和产品的研究开发提供一定的依据。     

三维整体式喷动-流化床结构优化与流动数值模拟

为了对环隙区内的颗粒堆积层产生局部流化作用,提出了一种在喷动床锥体处开一定数量侧喷嘴的整体式多喷嘴喷动-流化床结构,并采用双流体模型(TFM)对三维整体式多喷嘴喷动-流化床内的气固两相流动行为进行了数值模拟。通过计算流体力学(CFD)模拟获得了喷动床内颗粒体积分数、颗粒速度及流场均匀度分布情况,并将模拟结果与传统喷动床进行了对比,同时对锥体处开孔直径等关键参数进行了优化分析。结果表明:与常规喷动床相比,三维整体式多喷嘴喷动-流化床结构能有效增强喷动床环隙区与喷射区颗粒的径向混合,特别是流化了喷动床环隙区底部颗粒的流动死区。颗粒流场均匀度(CV)值随着床层高度的增加而上升,表明多喷嘴对颗粒流场的均匀化效应主要体现在喷动床柱锥区,当A_i/A_z=0.67时,侧喷嘴对喷动-流化床内整体的颗粒流化作用达到最佳。     

气液两相流对板式换热器影响的模拟研究

用Fluent软件对人字形板式换热器冷流道中气液两相流的4组不同工况进行了模拟研究,分析了冷流道中两相流体的流动和换热特性以及气体在流道中的分布状况。结果表明,由于气相的扰动作用,使进出口连线一侧传热死区的换热状况有了很大改善;在一定含气率范围内,随着空气体积含气率的增大,增强了板式换热器的换热效果。     

离心式气液分离器分离性能的数值模拟

离心式气液分离器具有结构紧凑、体积小、高效等优点,被广泛的应用于石油、化工、等行业。文章基于CFD方法,使用Fluent软件对某种离心式气液分离器进行全三维数值模拟,采用正交试验设计方法安排模拟步骤,研究得到流量、气泡直径、含气量三因素对气液分离效率的影响规律,为离心式气液分离器的结构优化和高效性提供参考。     

螺旋片导流式分离器分离性能的数值模拟与试验研究

应用计算流体力学（CFD）方法对不同结构参数的螺旋片导流式气液分离器在湍流状态下的流体流动场进行了数值模拟,研究了螺旋个数和螺距对螺旋片导流式气液分离器分离性能的影响,并与试验测定结果对比,由此验证基于数值模拟方法设计螺旋片导流式气液分离器分离效率的可行性与准确性.分析结果表明,数值模拟结果与试验数据基本一致,可以作为螺旋片导流式气液分离器设计的有效工具.     

海水淡化用汽液分离元件研究进展

汽液分离元件是热法海水淡化装置中至关重要的组成部分,它的主要作用是除去蒸汽中的盐雾液滴,保证淡化产品水水质。通过优化研究汽液分离元件的结构和操作工况可以提高其分离性能,达到提升装置效率、提高产水水质和节约生产成本的目的。本论文综述了应用于海水淡化装置的折流板式和丝网式汽液分离元件的性能特点,总结了国内外研究进展及部分工程案例,并对其发展前景进行了展望。     

CFD模型在污水沉淀池数值模拟中的应用

本文介绍了沉淀池数值模拟中所运用的大量紊流模型,综述了计算流体力学（CFD）模型应用于污水沉淀池数值模拟的研究现状,讨论了不同边界条件、环境因素对模拟结果的影响,评述了CFC模型应用于污水沉淀池数值模拟的优劣.     

Multi-objective optimization of drainage-plates in wave-plate mist eliminators using experiment and data-driven modelling for lower water loss and energy requirement

Wave-plate mist eliminators are widely employed as gas–liquid separation devices to prevent the liquid escaping from thermal power plants or other cooling towers. In this study, the wave-plate mist eliminator with drainage plates was numerically analyzed and the effects between geometrical variables on two objectives, namely, pressure drop (ΔP) and separation efficiency (η), were revealed. Plate spacing, width, and length, as well as the relative position of the drainage plate, were thoroughly investigated. A combined strategy was developed for multi-objective optimization of the wave-plate mist eliminator by integrating computational fluid dynamics (CFD) simulation, response surface methodology (RSM), non-dominated sorting genetic algorithm-II (NSGA-II), and a technique for order of preference by similarity to ideal solution (TOPSIS) method. The results demonstrated that the relative position of drainage plates has a greater impact on the overall performance, whereas the width of drainage plates has the minimum effect. With the implementation of NSGA-II and the TOPSIS method, an optimal solution for the design of the mist eliminator was obtained. After comparing with the baseline case, the optimized case presents promising characteristics with high separation efficiency (enhanced by 3.6%~9.06%) and a low energy consumption coefficient (reduced by 72.30% at η = 45%).     

NUMERICAL SIMULATION OF VOLATILE ORGANIC COMPOUNDS EVAPORATION IN CLOSED SPACES

Abstract

This paper deals with the simulation of VOCs concentration dispersion, evaporated from flooring materials, with the purpose of understanding VOCs evaporation and dispersion mechanisms. A test chamber is examined whose flooring material emits a number of VOCs. Given the area specific ventilation rate and considering it as boundary conditions, experimental data for the examined compounds concentration, the dispersion of the VOCs concentrations is examined under steady state and transient conditions. The model developed is used in conjunction with a general - purpose CFD code, PHOENFCS, that can provide detailed information on the flow as well as concentration fields. The results of the above two simulation cases are used as a guide for two other cases, where faster restoration of the air indoor quality was investigated by changing the ventilation rate in the chamber. The simulation results were used as a basis for further analysis for VOC evaporation for other flooring materials; this will allow proper material selection as well as proper ventilation system for a more healthy and comfortable environment in a building.     

NUMERICAL SIMULATION AND ANALYSIS OF FLOW IN A DTB CRYSTALLIZER

This research numerically simulates the two-phase (liquid and vapor) flow in a 1 m³ draft tube baffle (DTB) crystallizer with fines removal streams. The computational fluid dynamics (CFD) commercial software ANSYS CFX-10.0 was employed to perform 3-D simulation using the finite volume method with an unstructured mesh topology. The influence of hydrodynamics in the crystallizer, as characterized by the momentum source strength and fines removal flow, on the flow characteristics and the classification of crystals are investigated. The results showed the liquid flow is fully uniform in the main body of the crystallizer studied for momentum sources larger than or equal to 19.63 kg · m/s². The uniformity of the suspension will strongly affect the product crystal size distribution. Momentum source strengths and fines removal flow rates also have a significant effect on the fines removal cut-size due to varying up-flow velocities in the fines removal section, altering the size at which particles are carried out in the fines removal stream. The CFD predictions are compared with the experimental results from the literature and can be used for the optimization of commercial-scale DTB crystallizer design.     

泡沫陶瓷内分形模型建立和燃烧数值分析

多孔介质（泡沫陶瓷）预混燃烧是一项新颖、独特的燃烧技术。本文将分形理论应用到多孔介质压降模型中,建立了分形模型。并且求解了多孔介质特性参数：粘性阻力系数与内部阻力系数。并针对实验条件进行燃烧数值模拟研究。通过和实验数据对比,发现数值模拟和实验能较好相符合,说明此模型具有一定的可靠性。     

热管换热器传热性能及温度场数值模拟

引　言热管换热器是工业领域中应用广泛、经济有效的换热设备之一 ,对其传热性能的研究一直是热管界学者普遍关注的课题 .采用传统换热器设计理论即对数平均温差法和有效度 传热单元法对热管换热器进行传热计算已有大量的文献报道[1～ 3] ,但采用数值分析的方法研究热管换热器传热性能还鲜见报道 .在热管换热器中 ,冷、热流体间的热量传递是与热管管内工作介质蒸发和冷凝的相变过程相耦合的 ,因此导致热管换热器的总体性能一方面取决于热管元件本身的性能 ,另一方面又取决于管壳间流体流动和传热的特性 ,这两方面的综合影响决定了热管换热器的数值模拟研究具有相当大的难度 .本文采用数值模拟计算方法重点研究热管换热器的传热性能及其温度场分布 ,为热管换热器内流场分布研究和工程应用提供参考1　数值计算模型的建立1 1　热管换热器传热模型假设热管换热器沿流体流动方向分成N段 ,每一段由一排性能相同的热管组成 .图 1为第j排热管传热计算示意图ig 1　Heartransfermodelofheatpipeheatexchang1 2　模型假设(1)热管换热器处于正常工况条件下2)热管换热器沿流动方向分成N段 ,每一段由一排性能相同的热管...     

NUMERICAL SIMULATION OF THE GAS-PARTICLE FLOW IN RISERS I: THE MACRO FLOW BEHAVIOR

The steady gas-particle flow in risers under variant operating conditions was predicted based on a k-?-k_p-?_p-Θ two-fluid model, which describes the dense turbulent gas-particle flow by the Eulerian method, considering the turbulence of both gas and particles as well as the particles' collisional effects. Much information on the macro flow behavior in risers, such as the profiles of local particle axial velocity, solids volume fraction, and solids mass flux in different operating regimes was obtained, and the predicted results show satisfactory agreement with experimental data. Further analysis of the predictions gives the comprehension of flow characteristics on the macro scale.     

NUMERICAL SIMULATION OF THE GAS-PARTICLE FLOW IN RISERS I: THE MACRO FLOW BEHAVIOR

The steady gas-particle flow in risers under variant operating conditions was predicted based on a k-ε-k_p-ε_p-Θ two-fluid model, which describes the dense turbulent gas-particle flow by the Eulerian method, considering the turbulence of both gas and particles as well as the particles' collisional effects. Much information on the macro flow behavior in risers, such as the profiles of local particle axial velocity, solids volume fraction, and solids mass flux in different operating regimes was obtained, and the predicted results show satisfactory agreement with experimental data. Further analysis of the predictions gives the comprehension of flow characteristics on the macro scale.