空气通过浸没在水中的垂直、单一、矩形齿缝时,齿缝张开程度与空气流速的关系

与齿缝张开程度相当的液柱压力,是蒸气通过泡罩塔塔板压力降的主要组成之一。本文就空气-水系的实验,证实了前人提出的、根据孔口流出原理来计算齿缝张开程度与空气流速关系的理论公式;并得出孔口流出系数与Re准数间的函数关系,藉此可使该公式能普遍应用於常用操作条件的范围内。     

聚氯乙烯熔化程度与力学性能的关系

本文研究了PVC及其部分共混物的熔化程度与拉伸强度及韧性的关系。证明了uPVC及其所述共混物在一定剪切力的作用下,只有在适宜的熔体温度时,才具有良好的机械性能。uPVC只要在适宜的熔化程度(熔体温度下),即使在-30℃时,在5毫米/分钟的拉伸速度下仍具有良好的拉伸韧性。     

快速计算管道中空气流量的方法

在管道中安装一个园缺形的小孔板来测量流体穿过孔板的压力降,是一种测量管道中空气流量的简单方法。如下图所示。最好把这个孔板装在风管的上部,使得带压的连接管能自动排污。为保证测量的准确度和可重复性,所需要的上游直管最短长度为4倍直径,下游直管最短长度为1倍直径,在这种情况下可使用的孔板厚度为1/8吋到1/2吋。     

阿纽巴流量计用于空气流量测定

一、概况阿纽巴流量计也叫笛形均速管流量计,是六十年代后期发展起来的一种流量测量新技术。最近几年来,随着国外石化、化纤、化肥等成套工程项目的引进,在一些大型化肥厂中也开始使用这种流量计进行某些介质流量的测定。但是在小化肥厂中,至今还未有这方面的报导。我厂在第四设计院配合下开始进行节能改造项目试点,其中之一就是采用阿纽巴流量计代替孔板流量计,用于鼓风机出口总管空气流量的测定,以减少阻力、节省能耗。实践证明,采用阿纽巴流量计测量流量时,流体的阻力损失极小,节能效果明显。现将情况介绍如下。     

管道中空气流量快速估算法

<正> 美国《化学工程》杂志1983年5月号刊登署名文章,提出了利用测定孔口压差,然后直接查图,求得空气流量的方法。文中附有诺(?)图。此图使用方便,可供有关同志参考。现介绍如下。在管道的顶部装一孔板,并在该孔板前后各1英寸距离处设两只侧压管(见图1)。在已知压差的情况下,通过该孔板的     

膨胀机流量与振动的关系的探究

通过改变膨胀机入口流量的大小,来观察相应振动的变化情况,并对此进行分析评价。实验证明,膨胀机的振动随着入口流量的变化而变化。     

泡罩立体筛板的流体力学性能

将鼓泡传质和喷射传质有机结合,自主研发出泡罩立体筛板。以空气和水为介质,对新型泡罩立体筛板(NBTS)的流体力学性能进行研究,考察板孔动能因子、液相流量和堰高对其板压降、漏液和雾沫夹带的影响,并与泡罩立体筛板(BTS-1)进行对比。由结果可知:新型泡罩立体筛板的总板压降和雾沫夹带随板孔动能因子、堰高和液体流量的增大而增大;漏液点气速随堰高和液体流量的增大而增大,N-BTS的性能优于BTS-1,满足设计要求。     

泡盖式蒸馏塔的效率

<正>蒸馏塔的分离效率是评价这个塔好坏的指标之一。到目前为止已经有很多作者来探讨了影响蒸馏塔分离效率的若干因素并从而建立了估计分离效率的经验或半经验公式。所谓分离效率就是来衡量一个蒸馏塔实际的分离情况与理想的分离情况（每块塔板上达到平衡）间相差的程度。在一般文献上所载的分离效率通常有下列三种定义:     

EFFECT OF AIR FLOW RATE ON CARROT DRYING

The influence of air flow rate on the kinetics of drying 10x10x10 mm carrot cubes is presented. For this geometry kinetic equations are available, for the first falling rate drying period.

Drying air flows of 1000, 2000, 2500, 3000, 4000, 5000, 6000, 8000 and 9000 kg/m ² h were employed. It was found that for flow rates above 6000 kg/m² h the value of D/r² remains almost constant, thus indicating that when the air flow rate is higher it has no influence on the drying rate. The influence of air flow rate on carrot drying has been determined, hence allowing optimal flow rate calculation under economic constrictions.     

PP/PE熔体流动速率比与共混体系力学性能的关系

选择不同熔体流动速率(MFR)的乙-丙共聚型聚丙烯(PP)和聚乙烯(PE),分别配混出一系列不同熔体流动速率比(R_M=MFR_(PP)/MFR_(PE))的共混体系。深入探讨了共聚PP/PE共混体系的力学性能与PP和PE间R_M的关系。结果表明,在适宜的R_M范围內,PE能对乙-丙共聚型PP具有良好增韧增强效果。在025后,体系性能劣化。     

气泡釉的研制

研制了一种从石灰釉中分离出来的缺陷釉—气泡釉。气泡釉由于其特殊的性质,不适用于强度要求高的建陶,一般用于普通的日用瓷或艺术瓷。主要利用长石、高岭土、方解石、白云石和石英等常用原料,通过调整各种原料的用量,改变釉层厚度、烧成制度等方法来寻求最佳的气泡釉效果。     

CFD SIMULATION OF THE GAS-SOLID FLOW IN THE RISER OF A CIRCULATING FLUIDIZED BED WITH SECONDARY AIR INJECTION

A comprehensive investigation was carried out to study hydrodynamics aspects of secondary air injection in circulating fluidized beds. This article presents modeling and results of computational fluid dynamics simulations of gas-solid flow in the riser section of a laboratory-scale (ID = 0.23 m, height = 7.6 m) circulating fluidized bed with a radial secondary air injector. The gas-solid flow model is based on the two-fluid (Eulerian-Eulerian) approach, where both gas and solids phases are treated as interpenetrating continua. A granular kinetic theory model is used to describe the solids phase stresses. The simulation results are compared with measured pressure drop and axial particle velocity profiles; reasonable agreement is obtained. Qualitatively, excellent agreement is obtained in predicting the increase in solids volume fraction below secondary air ports, the accumulation of solids around the center of the riser due to momentum of secondary air jets, and the absence of the solids down-flow near the wall above the secondary air injection ports, which are the prominent features of secondary air injection observed in the experiments.     

CFD SIMULATION OF THE GAS-SOLID FLOW IN THE RISER OF A CIRCULATING FLUIDIZED BED WITH SECONDARY AIR INJECTION

A comprehensive investigation was carried out to study hydrodynamics aspects of secondary air injection in circulating fluidized beds. This article presents modeling and results of computational fluid dynamics simulations of gas-solid flow in the riser section of a laboratory-scale (ID = 0.23 m, height = 7.6 m) circulating fluidized bed with a radial secondary air injector. The gas-solid flow model is based on the two-fluid (Eulerian-Eulerian) approach, where both gas and solids phases are treated as interpenetrating continua. A granular kinetic theory model is used to describe the solids phase stresses. The simulation results are compared with measured pressure drop and axial particle velocity profiles; reasonable agreement is obtained. Qualitatively, excellent agreement is obtained in predicting the increase in solids volume fraction below secondary air ports, the accumulation of solids around the center of the riser due to momentum of secondary air jets, and the absence of the solids down-flow near the wall above the secondary air injection ports, which are the prominent features of secondary air injection observed in the experiments.     

STUDY OF THE AIR FLOW IN A WOOD DRIER

As the main condition of good wood drying is the uniformity of air velocity on the pieces, we focus in this paper on the problem of air flow in a wood drier loaded with stacks of planks. The case of the upper ventilation is mainly considerad A numerical study, based on the. resolution of movement equations for a turbulent flow, concerns the inlet and outer part of the stack. The result helped us to understand the part played by the space on each side of the stack, which differs for large or narrow distances from the wall. An experimental study gave us values for velocity distribution in the stack for given geometrical ratio of the drier and led us to recommend some rules for good loading.     

II,CORRELATION OF GLAZE THICKNESS WITH AIR PERMEABILITY*

An attempt was made to correlate the thickness of deposition of glazes with the air permeabilities of the bodies. The correlation was satisfactory under certain restricted conditions but not for general cases. An adequate correlation was obtained, independent of the type of body, between thickness of glaze deposition, glaze consistency (coherence value), and water receptivity.     

START-UP FLOW IN A PIPE FOLLOWING THE SUDDEN IMPOSITION OF A CONSTANT FLOW RATE

The transient flow in a long pipe following the sudden imposition of a constant flow rate is considered. An exact analytical solution of the axisymmetric Navier-Stokes equations in terms of an infinite series of Bessel functions is derived. Time-dependent velocity profiles, as well as time histories of the axial pressure-gradient and the wall-friction, are presented. It is observed that the start-up time required to reach steady state is significantly shorter than if the start-up flow results from a suddenly imposed constant pressure gradient. The “Annular Jet Effect” observed experimentally by Kataoka et al. (1975) is not exhibited by the present solution.