用于膜蒸馏的中空纤维组件中沟流效应的数值模拟研究

对用于膜蒸馏的中空纤维组件数学模型进行了求解 ,并用模拟计算结果分析组件中存在的沟流效应。结果表明 ,与纤维丝规则分布的理想组件相比 ,纤维丝随机分布的实际组件中存在的沟流效应使膜蒸馏组件通量大大降低 ;提高组件封装分率可以减轻沟流效应 ;提高膜两侧流体流量可以增加膜蒸馏推动力 ,削弱沟流效应带来的负面影响     

用于膜蒸馏的中空纤维组件中沟流效的数值模拟研究

对用于膜蒸馏的中空纤维组件数学模型进行了求解,并用模拟计算结果分析组件中存在的沟流效应,结果表明,与纤维丝规则分布的理想组件相比,纤维丝随机分布的实际组件中存在的沟流效应使膜蒸馏组件通量大大降低;提高组件封装分离可以减轻沟流效应;提高膜两侧流体流量可以增加膜蒸馏推动力,削弱沟流效应带来的负面影响。     

非平衡分子动力学在炭膜气体分离CH4/CO2中的模拟研究

通过建立单孔狭缝模型,采用非平衡分子动力学方法研究CH_4/CO_2二元气体混合物通过管状炭膜的传递和分离特性,考察了系统温度、气体组成和膜孔径对通量的影响。模拟过程中将膜低势,区压力取为更符合实际情况的非零值(大于零)。研究结果表明,在温度为20℃～160℃范围内,随温度升高,CH_4的通量增加,CO_2的通量则先降低后升高(80℃出现最低值);随混合气中CH_4组成的增加,CO_2通量下降、CH_4通量升高;随膜孔径增大,CH_4通量先增后减(9.77 (?)时出现最大值)、CO_2通量则呈下降趋势。以上模拟结果与实验数据相比较,吻合良好。在此基础上,本文还考察了跨膜压差对过程的影响,发现CH_4和CO_2的通量均随跨膜压差的增大而增大,膜的分离性能则随之降低。本研究结果充分表明,所建模型能够正确地描述CH_4/CO_2气体混合物的炭膜分离过程。     

模糊推理在MBR膜通量仿真中的研究

当前,将MBR大规模推广并加以应用的过程中最大的阻碍是膜污染问题。运用模糊推理方法将MBR系统的混合液污泥浓度(MLSS)、操作压力、温度等输入参数转换成模糊集,并用改进的基于梯度的实时学习算法进行模糊计算;将通过计算得到的膜通量的模糊值反模糊化,得出系统膜通量的明确评价值。这样就可以找出在膜通量最大情况下的输入参数,以便改进输入参数,达到更好的出水水质。该方法能够使传统的梯度下降方法中所存在的收敛速度和震荡之间的冲突问题从根本上得到解决,并且仿真计算结果与实际实验情况相符。     

SWRO系统膜污染动态过程建模与仿真研究

在反渗透海水淡化(SWRO)系统中,膜污染是一个导致渗透水性能降低和运营成本增加的重要因素。而关于反渗透海水淡化系统中的膜污染动态仿真的研究较少。本文以GAMS为建模工具,结合反渗透(RO)过程模型,建立卷式膜组件中膜内外部污染过程的动态模型,包括非平衡热力学、物料守恒等,并利用该模型仿真膜污染过程。仿真结果显示,膜组件上滤饼层的厚度变化、膜通量变化等和实际淡化厂的数据相吻合。而且该模型还能够较为准确地描述出卷式膜组件上各个位置的污染情况以及膜污染对RO过程变量的影响。表明该模型是准确有效的,对往后的SWRO系统研究或者对膜清洗的预测都有很好的借鉴意义。     

降雨条件下高速公路超高段水流特性仿真研究

为研究降雨下道路超高过渡段水流特性,利用Fluent流体仿真软件建立了高速公路路面水流的仿真模型,采用RNG k-ε模型求解流体域,DPM模型和EWF模型耦合计算实现降雨和降雨收集过程的模拟。在验证了模型可行性的条件下,分析了超高过渡段路面水膜厚度及水流路径长度随降雨强度、纵坡、超高渐变率等的变化规律。结果表明,路表水膜厚度随降雨强度的增大而增大,随纵坡和超高渐变率的增大而减小;最长水流路径长度随纵坡的增大而增长,随超高渐变率的增大而减小,但与降雨强度无关。在总体趋势上水膜厚度会随着水流路径的长度增加而增加。最后基于4mm的临界水膜厚度,给出了水流路径长度的控制值,在设计时可以通过设置超高段横向截水沟减少水流路径长度,以此来控制路面水膜厚度。     

基于改进极限学习机的MBR仿真预测研究

研究MBR膜通量,进行膜污染预测,是当今污水处理研究领域的重要课题之一。为了有效,准确地预测MBR膜通量,提出一种改进的极限学习机(PSO-ELM)预测模型。极限学习机(ELM)能够有效地克服反向传播(BP)算法的缺陷,并能以极快的速度获得很好的泛化性能。由于随机给定输入权值和隐层阈值,ELM通常需要较多隐含层节点才能达到理想精度。利用粒子群算法(PSO)对极限学习机(ELM)的权值和阈值进行优化,建立PSO-ELM预测模型,将提取的主成分作为该模型的输入,膜通量作为模型输出。研究结果表明,该模型对MBR膜通量预测具有较好的泛化能力和更高的预测精度。     

PDMS-铜膜复合电极的压力检测研究

本文报道了一种利用聚二甲基硅氧烷（PDMS）-铜膜复合电极进行压力检测的方法和系统。在PDMS-铜膜复合电极上施加压力时,PDMS发生形变并与之接触的铜膜进行摩擦,使铜电极表面电荷密度增加,PDMS-铜膜界面双电层（EDL）电容的电荷量也随之增加。由于双电层电容电容量不变,因此铜膜的电势会随之增加。通过检测铜膜电势的变化,可检测外界压力的变化情况。实验结果表明：检测系统输出电压的变化率正比于外加压力的变化率,输出电压的幅值反比于PDMS薄膜的厚度。因此,根据检测信号的幅值以及变化率,可以判定外加压力的大小以及变化率。本方法具有结构简单、灵敏度高和操作方便等特点,为发展新型柔性无源压力传感器提供了新的思路和方法。     

膜生物反应器膜污染的随机森林预测模型

生物反应器( MBR)工艺在现代污水处理中扮演着重要的角色,然而膜污染严重影响了MBR工艺的性能,膜污染导致的最直接的后果就是膜通量的下降,膜通量的下降直接影响MBR污水处理的效果。为了有效、快速地预测MBR膜通量,利用随机森林( RF)算法建立MBR膜通量预测模型。选取影响膜通量的主要因子作为随机森林预测模型的输入,膜通量作为输出,建立MBR膜通量影响因素和MBR膜通量之间的非线性关系。首先利用训练集在随机森林预测模型上进行训练,然后用训练好的随机森林预测模型进行膜通量预测。通过预测数据和实验数据的对比,得出该算法对膜通量有较高的预测精度;为了进一步验证该算法的有效性,建立了BP神经网络预测模型,将两者进行比较,对比结果表明随机森林预测模型具有更高的预测精度。     

管式SOFC数学模型及系统性能分析

固体氧化物燃料电池(SOFC)是一种高效低污染的新型能源。该文基于物质和能量守恒并耦合流体流动、热量产生和传递以及电化学知识建立了以天然气为燃料的管式固体氧化物燃料电池的数学模型,对模型进行求解,并分析系统参数(电流密度、工作压力、燃料的摩尔流量等)对系统性能(发电量、发电效率等)的影响。结果表明:SOFC系统的发电效率可以达到50.73%。通过增加单电池个数来减小电流密度可以增加系统发电量和发电效率,但是会增加系统投资;增大燃料电池的工作压力可以改善系统的性能;而增加燃料的摩尔流量(燃料利用率不变)会使系统的发电效率降低。     

Observer-based perturbation extremum seeking control with input constraints for direct-contact membrane distillation process

An observer-based perturbation extremum seeking control is proposed for a direct-contact membrane distillation (DCMD) process. The process is described with a dynamic model that is based on a 2D advection-diffusion equation model which has pump flow rates as process inputs. The objective of the controller is to optimise the trade-off between the permeate mass flux and the energy consumption by the pumps inside the process. Cases of single and multiple control inputs are considered through the use of only the feed pump flow rate or both the feed and the permeate pump flow rates. A nonlinear Lyapunov-based observer is designed to provide an estimation for the temperature distribution all over the designated domain of the DCMD process. Moreover, control inputs are constrained with an anti-windup technique to be within feasible and physical ranges. Performance of the proposed structure is analysed, and simulations based on real DCMD process parameters for each control input are provided.     

利用压力影响恒沸点由反应精馏精制THF

研究压力如何影响恒沸点,探索改变操作压力由反应精馏精制四氢呋喃（THF）可行性,模拟计算考察了压力对THF／水体系恒沸点的影响,结果表明体系压力增加,恒沸物中THF摩尔分率减少。通过两塔在不同压力下操作,利用反应精馏技术可从1,4－丁二醇制备高纯度的THF。     

Nonlinear observer-based Lyapunov boundary control of distributed heat transfer mechanisms for membrane distillation plant

This paper presents a nonlinear observer-based Lyapunov control for a membrane distillation (MD) process. The control considers the inlet temperatures of the feed and the permeate solutions as inputs, transforming it to boundary control process, and seeks to maintain the temperature difference along the membrane boundaries around a sufficient level to promote water production. MD process is modeled with advection diffusion equation model in two dimensions, where the diffusion and convection heat transfer mechanisms are best described. Model analysis, effective order reduction and parameters physical interpretation, are provided. Moreover, a nonlinear observer has been designed to provide the control with estimates of the temperature evolution at each time instant. In addition, physical constraints are imposed on the control to have an acceptable range of feasible inputs, and consequently, better energy consumption. Numerical simulations for the complete process with real membrane parameter values are provided, in addition to detailed explanations for the role of the controller and the observer.     

含苯酚废水的精馏处理

苯酚含量为0－1．9％的水溶液的汽液平衡数据表明苯酚在汽相中的浓度大于液相中的浓度,利用这一特点可以采用精馏的方法来脱除含酚废水中的苯酚并回收苯酚,本文对两个简单的精馏流程及一个热泵精馏流程进行了模拟分析及经济评价,结果表明采用简单精馏的能耗太大,经济上不合理,本文所分析的热泵精馏流程同一般的热泵精馏要比,没有再沸器,冷凝器,膨胀机,设备投资少,供热系数COP接近50,外部只需提供极少的直接蒸汽即可达到处理要求。     

Electrical equivalent thermal network for direct contact membrane distillation modeling and analysis

Membrane distillation (MD) is an emerging water desalination technology that offers several advantages compared to conventional desalination methods. Although progress has been made to model the physics of the process, there are two common limitations of existing models. Firstly, many of the models are based on the steady-state analysis of the process and secondly, some of the models are based on partial differential equations, which when discretized introduce many states which are not accessible in practice. This paper presents the derivation of a novel dynamic model, based on the analogy between electrical and thermal systems, for direct contact membrane distillation (DCMD). An analogous electrical thermal network is constructed and its elements are parameterized such that the response of the network models the DCMD process. The proposed model captures the spatial and temporal responses of the temperature distribution along the flow direction and is able to accurately predict the distilled water flux output. To demonstrate the adequacy of the proposed model, validation with time varying and steady-state experimental data is presented.     

大型煤化工甲醇精馏过程仿真系统的研究

研究构建大型煤化工甲醇精馏过程仿真平台问题.大型煤化工甲醇精馏过程操作复杂,为了能够更好地分析和预测该过程,本文开发了基于工艺过程机理模型的仿真系统.仿真系统的底层是流程模拟文件,提供过程机理模型和计算平台;顶层是仿真界面,提供人机交互窗口;二者通过Visual Basic接口程序链接.此仿真系统可以为实际的精馏操作提...     

热泵精馏流程构建策略及应用研究

基于蒸汽压缩式热泵精馏流程的特点及应用范围,提出了一个5层次策略来求解较优热泵精馏流程,并对每一层次分别求解,解决构建较优热泵精馏流程的复杂性。根据提出的构建热泵精馏的策略和原则,以粗苯乙烯精馏塔为例,利用流程模拟软件化工之星-ECSS,进行了热泵精馏流程的构建及模拟与优化设计。结果验证了根据本文所提出的策略进行优化设计,能够产生较优的热泵精馏流程。     

Modelling of the whole process of a university campus CHP power plant and dynamic performance study

Combined heat and power (CHP) refers to a process/system designed to utilize the waste or residual heat from a power generation process. Thus, a CHP plant can produce both electricity and heat. The nature of such a combination makes the process more complex than any single power generation process or boiler heating system. The paper focuses on modelling study and analysis of energy efficiency of the University of Warwick micro-CHP power plant. In this CHP modelling study, a gas turbine module is built to provide driving power and methane is used as fuel gas. Heat recovery system and auxiliary boiler modules are developed for thermal power generation. All the sub-systems are validated by comparing the simulation results with the operating data collected from the CHP plant. The dynamic performance of the key CHP process outputs is studied with respect to the variation of the input syngas stream, including electricity generation, thermal power output and water output temperature. Simplified controllers are also applied to the gas engineheat recovery subsystem and auxiliary boiler. Simulation results with/without feedback control are both analyzed. The study has highlighted the key factors which influence the plant performance and suggested the strategy for potential energy efficiency improvement.