酸浓度对水解液中葡萄糖分解反应的影响研究

研究了酸氛下葡萄糖的分解特性,考察了酸浓度(0.05～0.20mol/L)、温度(150～200℃)和反应时间(0～25min)对匍萄糖分解的影响.通过分析实验数据,运用数值计算方法对动力学参数进行估计,得到了该反应的表观活化能为136.83 kl/mol,建立了能反映H 浓度对葡萄糖分解速率影响的动力学方程,其计算值与实验值的平均残差平方和为0.00382.     

火灾中木耳燃烧特性及数值模拟

从基础研究角度出发,针对湖南衡阳“11．3”特大火灾事故的重要可燃物木耳,应用符合ISO 9705标准的ISO ROOM装置对其进行全尺寸实验研究,并测量包括热释放速率、质量损失速率、房间内温度场、组分浓度等多个参量．同时对该过程进行了计算机数值模拟,计算结果与实验数据具有较好的一致性,为下一步对衡阳“11．3”整个火灾场景进行数值模拟研究提供了基础．     

Green-Ampt入渗模型的一种显式近似解

为解决Green-Ampt(GA)入渗模型只有隐格式解的问题,给出了高精度的显格式近似解,该显格式构造一组幂函数作为基函数,通过最小化近似解与精确解之间的误差,达到对GA模型的逼近。在对误差函数最小化的过程中,首先证明优化解的存在性,同时采用自适应的优化分段方法,在满足精度的条件下减少基函数的级数,达到简化计算的目的。针对入渗时间趋于无穷导致近似解发散问题,建立了修正公式,确保了该逼近方法的全局收敛性。通过与其他近似解的比较,验证了该方法的稳定性和精确性。     

NOx热力反应生成实验关系式研究

在燃烧研究中，ＮＯＸ的实验关系式一直采用０阶近似来处理，当燃烧时间较大时，这种方法误差较大。本文基于Ｚｅｌｄｏｖｉｃｈ的燃烧理论，用近似方法来获得关于ＮＯＸ０阶近似和１阶近似的实验关系式，并提出用反问题中求正规解的思想来选择确定适用于０阶实验关系式的实验数据。     

燃烧超细颗粒声波团聚的谱分布数值模拟

在简要介绍声波团聚超细颗粒物的动力学机理的基础上,利用区域算法求解超细颗粒声波团聚的动力学方程(GDE),数值模拟了声波团聚前后的超细颗粒的谱分布变化,并同相关实验数据和数值算法进行了比较和分析．区域算法结果和实验数据以及数值解之间吻合较好,并且利用该算法研究了颗粒质量浓度、声波频率和声波强度对超细颗粒团聚效果的影响,结果表明颗粒质量浓度和声强的增加均有利于颗粒的团聚,而声波频率则存在一个最佳值．     

非传统动力学分析法解析生物质热解过程

将一种新方法引入到生物质热解过程的分析中,该方法利用不同升温速率下的热重实验数据,基于合理的假设和非线性最小二乘法,确定出生物质热解过程中的反应分布,并最终计算得到对应的活化能、指前因子以及反应比率.在本研究中,首先将其用以计算模拟DTG数据,所得结果与预设数值非常吻合.同时,对纤维素热重实验数据进行分析,发现对于符合一级反应机理的脱挥发分过程,可以很好地计算各反应相关参数.最终将该方法应用到生物质热解过程研究中,结果表明不同生物质的热解过程是由具有不同特征的众多一级反应所组成.不同生物质单元反应的活化能、指前因子以及所对应的反应比率可分为3个部分.各部分的动力学参数以及分布状态与生物质的种类相关.     

基于响应面近似模型的双层喷孔参数优化研究

在共轨柴油机上采用双层交错布置喷孔油嘴可以改善柴油机的经济性和排放性能。针对双层交错布置喷孔油嘴与燃烧室优化匹配问题,采用CFD软件,运用中心组合试验设计方法设计燃油系统参数的试验计算矩阵并进行数值计算;再以响应面近似模型构造燃烧和排放的优化目标函数;最后运用多岛遗传算法对该近似模型进行全局寻优,确定燃油系统参数的优化组合,并在试验台架上进行了优化方案的配机试验。结果表明:小的喷孔直径、较多的喷孔以及适当的上下层喷孔喷射夹角可提高油束的雾化质量。     

复杂换热器系统的动态特性计算

介绍了在国产２００ｔ／ｈ循环流化床锅炉建模与仿真工作中开发的复杂换热器系统动态特性的计算方法。该方法以近似解析解方法为基础,大大提高了运算速度,并解决了计算的不收敛问题,解耗算法的采用,令冷,热工质的平衡计算得以分离,从根本上避免了迭代计算。借助近似解析解方法和解耦算法,建立了一套通用的换热器动态特性模块化计算方法,从而为复杂换热器系统的动态特性计算提供了一个通用性强而且高效、简便的方法。     

油页岩流化床燃烧过程中挥发份火焰的平均温度计算

挥发份火焰温度是决定油页岩流化床燃烧过程的重要因素，在流化床燃烧条件下油页岩首先脱挥发份并形成扩散火焰，该火焰将部分热量反馈回油页岩颗粒表面，加速挥发份的进一步释放。本文通过考虑火焰层中的化学反应，以及耦合火焰层与颗粒表面的传热、传质，采用Ｓｃｈｗａｂ Ｚｅｌｄｏｖｉｃｈ变换求得火焰平均温度的分析解，计算结果与实验数据吻合良好。     

基于多体动力学的479Q发动机连杆载荷与强度分析

以479Q汽油机为研究对象,建立了曲轴、连杆和活塞的三维几何模型和多体动力学模型。载荷边界条件采用真实示功图和负载数据,得到了做功行程中作用于连杆两端的载荷谱。采用惯性释放技术计及惯性力对连杆应力的影响,计算得到了做功行程中任意时刻连杆的动态应力场。对静力计算方法和惯性释放方法进行了对比,后者得到的动态应力场更加接近真实情况。根据曲轴转速为2 000 r/min时的气缸压力测试曲线(最高燃烧压力4.6 MPa)和对应的发动机扭矩(165 N.m),计算得到连杆最大轴向载荷为26 kN,最大工作应力为259MPa。根据局部应力应变法,该工况下的寿命为2.941×1016转,连杆近似为无限寿命。     

A new method for analyzing VOCs emission from dry materials

An approximate integral method for volatile compounds emission from plate is presented in this paper. The gas-phase mass transfer resistance was neglected for simplifying computation. Compared to Laplace Transformation Method, the method suggested is simple, and emission flux, chamber concentration of volatile compounds and concentration distribution of volatile compounds in the material can be determined conveniently. Results of the present method show good agreement with experimental data. The influence of CO, D, K and N on concentration of total volatile organic compounds （TVOC） in the air is also calculated.     

Mass transfer of volatile organic compounds from painting material in a standard field and laboratory emission cell

The field and laboratory emission cell (FLEC) is becoming a standard method of characterizing pollutant emissions from building materials. It is significant to use the emission profiles from FLEC to scale the emissions of building materials in real buildings. The dynamics of mass transfer in such an FLEC are the key to perform this task. In this study, the mass transfer mechanisms of the total volatile organic compounds from a wet painting in an FLEC are experimentally and numerically investigated. A three-dimensional mass transfer model, which takes into account the convective mass transfer between the material and the air, the diffusion in the paint film and in the substrate, is developed. The emissions from a water-based emulsion paint are quantified to assess the model. The concentration fields in the film and substrate are calculated to demonstrate the processes of internal volatile organic compounds diffusion.     

Effects of preprocessing method on TVOC emission of car mat

The effects of the mat preprocessing method on total volatile organic compounds (TVOC) emission of car mat are studied in this paper. An appropriate TVOC emission period for car mat is suggested. The emission factors for total volatile organic compounds from three kinds of new car mats are discussed. The car mats are preprocessed by washing, baking and ventilation. When car mats are preprocessed by washing, the TVOC emission for all samples tested are lower than that preprocessed in other methods. The TVOC emission is in stable situation for a minimum of 4 days. The TVOC emitted from some samples may exceed 2500μg/kg. But the TVOC emitted from washed Polyamide (PA) and wool mat is less than 2500μg/kg. The emission factors of total volatile organic compounds (TVOC) are experimentally investigated in the case of different preprocessing methods. The air temperature in environment chamber and the water temperature for washing are important factors influencing on emission of car mats.     

恒温下准东煤及其混煤燃烧过程中NO释放特性研究

基于恒温热重-燃烧污染物在线监测系统,通过对NO瞬时释放曲线的分析,并结合燃烧反应动力学计算,研究了恒温条件下燃烧环境温度对准东煤燃烧过程中NO释放特性的影响。结果表明：随温度升高,单煤和混煤燃烧过程中NO的释放时间会显著降低,释放速度显著提高;煤种成分的差异会导致NO释放特性的差异,固定碳挥发分的质量分数对NO释放有影响,而灰分的质量分数对NO释放无影响,当高固定碳、高挥发分的煤与低固定碳、低挥发分的煤进行掺混燃烧时,混煤的NO释放量和释放速率会降低。当燃烧过程中掺混北山煤时,混煤NO释放量低,释放速率慢,可以看作是一个较为优良的混煤掺烧方案。     

聚丙烯装置尾气回收技术分析

对大连石化聚丙烯装置尾气排放和回收现状进行了分析,通过对全厂尾气排放管网进行优化设置,把全厂尾气中的可回收气体（主要是丙烯、丙烷等有机蒸气）和不可回收气体（主要是氮气、乙烷等不凝气）分开排放,可回收气体排人气柜。尾气升压冷凝回收后,有机蒸气回收率为89．73％,但升压冷凝后的排空气中仍含有58％左右的C3H6和C3H8,再利用膜分离技术对排空气中的有机蒸气进行回收,丙烯单体回收率达到96．21％。通过优化排空管网设置、升压冷凝回收和膜分离回收等3种技术手段的综合运用,聚丙烯装置尾气中有机蒸气的回收率达到了99．59％,避免了装置尾气排放造成的环境污染．同时优化了资源,降低了生产成本。     

Absorption process of a falling film on a tubular absorber: An experimental and numerical study

This paper describes an experimental and theoretical analysis of the combined heat and mass transfer processes that take place in the absorber of vapor absorption cooling systems. The effect of the main operating variables such as solution inlet temperature, solution flow rate, coolant inlet temperature, coolant flow rate and absorber vapor pressure on the performance of absorber is experimentally investigated. A mathematical model that takes account of the geometrical details of the solution and coolant flow is developed following the traditional heat exchanger analysis to obtain additional information on the performance of the absorber. The governing equations are solved analytically using Laplace Transformation technique. The variations of the concentration of solution and the temperature of the coolant and solution after each horizontal tube are analyzed. There is satisfactory agreement between the predictions of the analytical model and the experimental results. The serpentine arrangement of the coolant flow in the absorber tubes results in a temperature and concentration variation of the solution mainly along the height of the absorber.     

反应气氛对燃料氮析出规律的影响研究

在自行设计的试验装置上研究了HT、LC煤在不气氛下氮的析出特性.结果表明在混有CO的还原性气氛中NOx析出时间延迟,挥发分析与焦氮析出时间有融合的趋势,NOx生成量减少;在高氧浓度混有CO2的气氛中,氮析出时间提前,且在燃烧前期聚集释放,析出量大;在低氧浓度下挥发分氮与焦氮分阶段析出,NOx生成量减少.     

不同反应气氛下燃料氮的析出规律

在自行设计的试验装置上研究了黄台煤(HT)、莱城煤(LC)在不同气氛下氮的析出特性.结果表明:在混有CO的还原性气氛中,NOx析出时间延迟,挥发分氮析出与焦碳氮析出时间有融合的趋势,NOx生成量减少;在高氧浓度混有CO2的气氛中,氮析出时间提前,且在燃烧前期聚集释放,析出量大;在低氧浓度下,挥发分氮与焦碳氮分阶段析出,NOx生成量减少.     

Modeling transport of tau in an axon after a photobleaching experiment

The goal of this paper is to apply Laplace transform method to solving the problem of recovery of concentration of tau protein in an axon after a photobleaching experiment that is described in S. Konzack, E. Thies, A. Marx, E. Mandelkow, E. Mandelkow, Swimming against the tide: Mobility of the microtubule-associated protein tau in neurons, Journal of Neuroscience. 27 (2007) 9916-9927. The model accounts for two populations of tau molecules: those that are suspended in the cytoplasm, free to diffuse in the axon, and those that are bound to microtubules (MTs). The exchange of tau molecules between these two populations is modeled by first-order reactions. It is shown that governing equations for this model can be solved by Laplace transform method, although the last step of the solution, finding the inverse Laplace transform, has to be done numerically, which leads to a hybrid analytical and numerical solution technique. The numerical inversion of the Laplace transform is performed utilizing a method based on Fourier series expansion of the inverse transform.     

NUMERICAL ANALYSIS OF NON-FICKIAN DIFFUSION PROBLEMS IN A POTENTIAL FIELD

The primary difficulty encountered in the numerical solution of non-Fickian diffusion problems is numerical oscillations in the vicinity of sharp discontinuities. The present study applies a hybrid numerical scheme of the Laplace transform technique and the controlvolume method in conjunction with the hyperbolic shape functions to investigate the one-dimensional non-Fickian diffusion problems in the presence of a potential field for finite or semi-infinite geometry. The Laplace transform method used to remove the time-dependent terms in the governing differential equation and boundary conditions, and then the transformed equations are discretized by the control-volume scheme. To show the accuracy of the present numerical method, a comparison of the mass concentration distribution between the present numerical results and the analytic solutions is made. Results show that the present numerical results agree well with the analytic solutions and do not exhibit numerical oscillations in the vicinity of the jump discontinuity for various potential values. The potential gradient dV/dx has a great effect on the mass concentration distribution. The strength of the jump discontinuity is reduced as the value of the dimensionless potential gradient is increased.