Experimental study on prediction model of wet gas pressure drop across single-orifice plate in horizontal pipes in the low gas phase Froude number region

The pressure drop prediction of wet gas across single-orifice plate in horizontal pipes had been solved satisfactorily under an annular-mist flow in the upstream of orifice plates. However, this pressure drop prediction is still not clearly determined when the upstream is in an intermittent flow or stratified flow, which is corresponding to a region of low Fr_G (gas phase Froude number) in the flow pattern map of wet gases. In this study, the wet gas pressure drop across a single-orifice plate was experimentally investigated in the low Fr_G region. By the experiment, the flow pattern transition in the downstream of single-orifice plates, as well as the effects of Fr_G and Fr_L (liquid phase Froude number) on Φ_G (gas phase multiplier), were determined and compared when the upstream is in the flow pattern transition and the stratified flow region, respectively. Prediction performances were examined on the available pressure drop models. It was found that no model could be capable of jointly predicting the wet gas pressure drop in the low Fr_G region with an acceptable accuracy. With a new method of correlating Fr_G and Fr_L simultaneously, new correlations were proposed for the low Fr_G region. Among which the modified Chisholm model shows the best prediction accuracies, with the prediction deviations of Φ_G being within 7% and 3% when the upstream is in flow pattern transition and stratified flow region, respectively.     

长方体建筑长宽比对屋顶风力机微观选址的影响

采用CFD方法,对长宽比分别为0.25、0.30、0.40、0.50、0.60、0.70、0.80、0.90的8种长方体单体高层建筑物顶面的风流场特征进行模拟计算,确定长宽比对长方体建筑物顶面风力机微观选址的影响.结果表明:长宽比越大,建筑顶面低风速区域越大,且风速随高度增长得越慢,而迎风面拐点风速恢复最快;同时由于建...     

粗生物柴油真空精馏脱硫研究

针对采用废油脂为原料转化制备的生物柴油会含有一定量的硫化物的问题,采用真空精馏法脱除生物柴油中的硫化物,并对硫化物附存形态进行分析。结果表明：生物柴油中硫化物主要包括低沸点的硫化氢、硫醇、硫醚、硫胺素等,以及高沸点的苯并噻吩、二苯并噻吩等。采用控制精馏脱硫塔塔顶温度150 ℃、操作绝对压力300~500 Pa、回流比1的条件下,先对生物柴油中低沸点硫化物进行脱除,再将塔顶温度升至210 ℃,将中间馏分（生物柴油）从塔顶精馏出来,高沸点重馏分（生物重油、高沸点硫化物）留在塔釜底部,两步精馏切割法能将达标的生物柴油与其他馏分分离开来,可有效降低生物柴油的硫含量,脱硫率达97%,满足最新国Ⅵ柴油排放标准（GB 17930—2016）的硫含量≤10 mg/kg要求,且硫含量达标的生物柴油得率达到85%以上。     

乳液聚合法制备石蜡基相变储能材料及热物性研究

将石蜡真空浸渍于膨胀蛭石中,以其共同作为内相,丙烯酰胺水溶液作为外相,制得水包油乳液,引发剂使外相聚合,得到形状稳定的复合相变储热颗粒。测试结果表明：乳化剂和膨胀蛭石分别为石蜡质量的6%和2%时,熔融焓数值为128.79 J/g,石蜡的包覆率为72.80%;复合颗粒的形状是表面规整的球体,颗粒大小均匀;经过100次循环后,熔融焓只降低2.18%;复合颗粒在470 ℃以下有较好的热稳定性。膨胀蛭石与聚丙烯酰胺对石蜡的二次封装可有效提高复合体系防泄露能力,具有可靠的储能和温度调节性能。     

2014年我国热固性工程塑料进展

根据2014年国内公开发表的文献,综述了我国热固性树脂及其塑料的开发研究状况。2014年我国热固性工程塑料的研究开发集中在环氧树脂、聚氨酯和酚醛树脂等大品种树脂的增强增韧及功能化上。利用各种新型树脂或固化剂、无机纳米粒子或功能型助剂等对传统热固性工程塑料的改性取得了较多的成果。     

微化工过程中的传递现象

微化学工程是现代化学工程学科前沿,主要研究微时空尺度下流体流动、传热、传质现象与反应规律。着重介绍近十年来微通道内气-液、液-液两相流体流动、混合与传质的理论和实验的最新研究进展,并对微化工技术的发展进行展望。     

Kinetics,mechanism, and simulation of hydrogen transfer reaction of α, β-unsaturated aldehydes to allylic alcohols

Homogeneous hydrogen transfer reactions of methacrolein (MAL) and isopropanol to methallyl alcohol (MAA) were investigated in batch reactor (Conv. 89%, Select 93.1%) and tubular reactor (Conv. 88.1%, Select 95%) using aluminum isopropoxide (Al(OPrⁱ)₃) as catalyst. Kinetic experiments on hydrogen transfer reactions and reaction order were investigated in batch reactor and tubular reactor. Response surface methodology was applied to optimize the optimum reaction conditions of hydrogen transfer reaction. Purification process of MAA from product mixture after hydrogen transfer reaction was simulated with Aspen Plus software; theoretical stages, reflux ratio, and feed stage of distillation tower were optimized. Density functional theory was used to investigate viable reaction pathway and to probe the catalytic mechanism between reactants and catalyst, including dehydrogenation, coupling, and hydrogenation reaction. Microscopic mechanisms of hydrogen transfer reaction from MAA to MAL were acquired in detail and could be easily extended to other series of hydrogen transfer reaction.     

微尺度下液-液流动与传质特性的研究进展

微化学工程是现代化学工程学科的前沿,主要研究微时空尺度下流体流动、传热、传质现象与反应规律。着重介绍近十年来微通道内单相流体流动、互溶液-液两相流体流动与混合、互不相溶液-液两相流体流动与传质的理论和实验的最新研究进展。     

A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise

This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article.