Performance characteristics of a packing with boundary layer turbulizers. IV. Gas-film controlled masstransfer

The gas-film controlled mass-transfer rate in a honeycomb packing, with stamped groove turbulizers (Turbo-Pack) which affect the region of the boundary layer, has been studied. An equation for determining the mass-transfer coefficient as a function of gas velocity and the geometrical dimensions of the packing has been derived. It is found that the effect of the height of packing blocks is far less than that forecast by Zhavoronkov's equation which was derived for packings with a much higher wall thickness. Comparison of experimental data relevant to the novel design with reference packings cited in the literature shows that as far as its low values of pressure drop per mass transfer unit are concerned the Turbo-Pack packing is superior to all other known packings.     

Performance characteristics of a packing with boundary layer turbulizers. III. Liquid film controlled mass transfer

Liquid film controlled mass transfer in a novel design of a honeycomb packing (Turbo-Pack) with turbulizers in the region of the boundary layer has been studied. For comparison, packings without turbulizers have also been investigated. Dimensionless equations for evaluation of mass transfer are proposed and their constants have been analyzed statistically. It is shown that the presence of turbulizers leads to an increase of the mass-transfer coefficient by up to 55% and to a decrease of up to 4.5-times in the packing pressure drop per mass transfer unit. A comparison over the most effective packings known from the literature shows that, as far as its low pressure drop per mass transfer unit is concerned, the novel packing is superior to all other packings.     

新型空分填料的压降及模型预测比较

采用空气-水物系,在直径600 mm的有机玻璃塔中对杭州杭氧填料有限公司开发设计的HYTL-750Y型空分填料进行了压降测试。测试数据显示该新型规整填料通量大,压降小,是一种具有较优流体力学性能的空分填料。同时使用填料测试数据对SRPⅡ和Delft压降模型预测结果进行了评估和比较。结果显示,SRPⅡ模型可以较为准确的预测HYTL-750Y型空分填料预载区压降,而Delft模型预测压降和实验结果相差较大,预载区偏小,载点区偏大。对于整个操作范围内的压降预测,SRPⅡ模型和Delft模型都还需做进一步改进。     

Pressure drop through a tapered die with optimized flow characteristics

The flow of power-law liquids through tapered dies has been analyzed in an earlier paper.¹ We now consider a taper which is additionally streamlined so as to make the transition from a broad and sluggish flow to a flow which is narrow and fast and as smooth as possible. This involves (1) the rational selection of an appropriate taper function within the relevant flow geometry and (2) the integration, between limits, of that function.     

Performance characteristics of a new structured packing

A new structured packing using carbon fibres, called Sepcarb^® 4D, is presented. This packing has several attractive properties, such as high voidage (ε=94%) and high effective area (a=420 m² m^?3). These properties are advantageous for packing used as a gas–liquid contactor for separation units. To determine the internal characteristics of this packing, we performed several experiments using a 150-mm-internal-diameter column. Firstly, hydrodynamics experiments were conducted using an air–water counter current flow to determine the pressure drop (for both dry and wet packing) and flooding point. Secondly, the mass transfer efficiency was determined in terms of HETP (height equivalent to theoretical plate) by total reflux experiments with an n-heptane/cyclohexane mixture at atmospheric pressure. Hydrodynamic performance and mass transfer efficiency were compared with those of packings generally used in distillation and absorption.     

Performance characteristics of a new spherical metal mesh packing

Various tests and analysis on hydrodynamics and mass transfer properties show that, the newly invented spherical metal mesh packing (SMMP) has excellent properties from three aspects: (i) high void space (∼99%) and lower material cost; (ii) high mass transfer efficiency; (iii) easy installation, good liquid distribution, and prevention of wall flow. Moreover, SMMP is a type of isotropic spherical unit with numerous hollow holes, which realizes the regularization of random packing. The results indicate the potential of developing high-efficiency and energy-saving SMMP-based equipment.     

Pressure drop of structured packing in pilot column and comparison to common correlations

Packed columns are widely used in the chemical industry such as absorption, stripping, distillation, and extraction in the production of e.g. organic chemicals, and pharmaceuticals. Pressure loss and pressure drop correlations are of special interest when it comes to the hydrodynamic properties of a column.The pressure loss across the column is of interest in the design phase when the size of the blower to drive the gas stream through the column has to be decided. The loading point and flooding ...     

Pressure drop characteristics of flow in a symmetric channel with periodically expanded grooves

Pressure drop characteristics of flow in a periodically grooved channel are investigated experimentally. It is well known that a self-sustained oscillatory flow occurs from a steady-state flow at a certain critical Reynolds number in such grooved channels. The oscillatory flow enhances fluid mixing and leads to an increase in pressure drop. We measure the pressure drop with a pressure transducer. It is found that the pressure drop increases near the critical Reynolds numbers where the two- and three-dimensional oscillatory flows occur. In addition, the three-dimensional flow is confirmed by flow visualization.     

气液两相并流下行通过堆叠筛板填料的压降特性

堆叠筛板填料已在核电站放射性气体除气塔中得到成功应用。针对这一新型填料的应用设计,在较广泛的气液流量下,对气液并流下行通过不同规格堆叠筛板填料的阻力特性进行了系统的实验。实验填料共6种规格,孔径参数包括6、10和14 mm,不同孔径填料对应不同的孔间距、板间距,每种孔径填料具有正方形和正三角形两种筛孔分布方式。通过压降数据分析,研究了流动参数和几何参数（孔径、开孔率、布孔方式、板间距）对气液两相并流通过填料的流动行为及压降特性的影响;结合多孔板阻力系数经验公式提出了堆叠筛板填料干板阻力系数的计算模型,模型很好地反映了不同几何参数对干板阻力系数的影响,预测偏差在5%范围以内;基于均相流模型提出了堆叠筛板填料气液两相压降的预测模型,模型预测偏差在10%范围以内。研究工作对堆叠筛板填料塔的应用设计及进一步的传质动力学研究有一定参考价值。     

Experimental study of characteristics of a laminar boundary layer with hydrogen combustion

Results of an experimental study of a laminar boundary layer with combustion of a hydrogen-nitrogen fuel mixture uniformly injected through a porous wall into an air flow are presented. Data characterizing the ignition conditions are obtained. Based on the recorded temperature distributions, streamwise changes in the location and temperature of the flame front are analyzed as functions of the free-stream velocity (1–4 m/s), injection intensity, and fuel composition. It is demonstrated that heat transfer can be adequately described by a “standard” dependence for the boundary layer with boundary conditions of the second kind.     

Periodic open-cell foams: Pressure drop measurements and modeling of an ideal tetrakaidecahedra packing

Periodic open-cell foams of ideal tetrakaidecahedron geometry were manufactured by selective electron beam melting (SEBM) and characterized with respect to the morphological parameters, namely strut diameter, window diameter and porosity. The pressure drop over these periodic foam samples of different pore size and porosity was determined experimentally. The basic form of the Ergun equation (which contains no empirical coefficients) was modified to develop a new correlation for the prediction of the pressure drop in periodic open-cell foams of ideal tetrakaidecahedron geometry. The correlation was successfully validated by the experimental results of the pressure drop measured for the periodic open-cell foam samples. With the new correlation it is possible to predict the pressure drop in periodic open-cell foams by using only two geometrical parameters, namely the open porosity and the window diameter.The applicability of the new correlation for a large range of porosities was examined by comparing the experimental and simulated friction factors for the porous media with both high (foam structure) and low porosities (packed beds) for a large range of the Reynolds number. It was demonstrated that the correlation can successfully predict the pressure drop of foam structures as well as packed beds.     

Pressure drop and saturation of nonwettable coalescing filters at different loading rates

The effect of layers on the pressure drop and saturation of nonwettable filters at different loading rates were investigated. It was found that both the jump and channel pressure drop depended on the loading rate. The total channel pressure drop of different filters seemed independent of the number of layers. At the same loading rate, more layers led to fewer channels per layer and larger size of each channel. Moreover, according to the evolution of channel number and size, there was a reorganization of channel structure in the filters. © 2017 American Institute of Chemical Engineers AIChE J, 63: 180–185, 2018     

Pressure drop and flowrate characteristics of a liquid phase spout-fluid bed at the minimum spout-fluid flowrate

Data on the minimum spout-fluid flowrates and the pressure drop in the annulus at that flowrate are presented as a function of bed height and nozzle diameter for a bed spout-fluidized with water. The column was 62.6 mm. in diameter and contained 3.09 mm. glass particles. The particle Reynolds number at the minimum fluidizing velocity was 91.6. A plot of the annular vs. the nozzle flowrate shows that the minimum spout-fluid flowrates fall on a straight line between the minimum fluidizing and minimum spouting flowrates. The annular pressure drop is explained using an extension of the theory of Mamuro and Hattori.     

Structure of a boundary layer with injection and combustion of ethanol

Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 3, pp. 29–36, May–June, 1992.     

Penetration and pressure drop of a HEPA filter during loading with submicron liquid particles

Experiments and a model have been made of the effects of mass loading of a HEPA fiber filter during filtration of submicron liquid aerosol particles. The measurements reveal that penetration of the test medium increased during clogging by a liquid aerosol, irrespective of particle size within the chosen range (0.02–0.5 μm). The physicochemical properties of the test aerosol did not seem to affect this phenomenon. Application of a non-stationary filtration model by Payet [1991, Thèse, Université Paris, 150 p] (based on the correlation of Liu and Rubow [1990, 5th World Filt. Congress, Nice 3, 112] showed that the increase in penetration can be explained in part by an increase in interstitial velocity and in part by a decrease in the number of fibers available for capture of particles.     

细小尺度下潜热型功能热流体压降与传热特性

实验研究了相变微胶囊颗粒(囊芯材料为正十六烷,壳材为尿素-甲醛树脂)和去离子水混合制成的潜热型功能热流体流过等热流细小圆管的流动与传热特性,同时以去离子水作为传热工质在相同条件下进行了对比实验。得到了压降随质量流量的变化规律,实验段出、入口温度以及量纲1出口温度随Reynolds数变化规律,量纲1壁面温度沿轴向的分布规律,平均Nusselt数随Reynolds数的变化关系。结果表明,相变微胶囊颗粒的加入会导致流动压降增大,但随着流量增加,流动压降逐渐与单相液体的接近;出口温度及壁面温度要比相同条件下单相液体的低;含有较小相变微胶囊颗粒浓度的潜热型功能热流体的平均Nusselt数是相同条件下单相液体的2.0～4.0倍。     

两级泡沫镍填料旋转填充床压降及精馏研究

在两级逆流式旋转填充床(TSCC-RPB)的基础上,采用简单结构的整体泡沫镍填料替代其相对复杂的动静环结构填料,从而构建新型两级整体泡沫镍填料旋转填充床(TSNF-RPB)。采用空气-水体系,研究了TSNF-RPB的压降特性,并以甲醇-水为工作体系,对TSNF-RPB进行了连续精馏实验研究。结果表明:虽然TSNF-RPB的湿床压降比TSCC-RPB高出了20%—30%,但TSNF-RPB的分离效率提高了20%,且TSNF-RPB结构简单、安装方便,更利于工业推广应用。     

Interaction of rarefaction waves with a finite-thickness layer near a rigid boundary. Equilibrium approximation

Interaction of a rarefaction wave with a layer of solid particles near the end face of a shock tube is considered. A one-dimensional unsteady approximation of mechanics of heterogeneous media with identical pressures of the phases and with allowance for a finite volume concentration of particles in the layer is used as a mathematical model. The wave pattern of the flow and the mechanism of wave interaction with the layer, including the dynamics of the layer boundary depending on the layer thickness and rarefaction-wave width, are determined. The mathematical model proposed is verified against the dependence of the layer-boundary coordinate on time and also the dependence of the velocity of upward motion of the layer on the difference in pressures between the high-pressure and low-pressure chambers. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 126–135, September–October, 2007.     

Performance characteristics of polymer photovoltaic solar cells with an additive-incorporated active layer

We have investigated the performance characteristics of bulk-heterojunction polymer solar cells based on poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C₆₁ butyric acid methyl ester by adding 1,8-octanedithiol as a processing agent in an active layer. The effects of the additive, 1,8-octanedithiol, on the device performance parameter characteristics have been discussed. The current density-voltage measurements, UV-Vis absorption spectra, X-ray diffraction spectra, and scanning probe microscope images have been used to discuss the performance characteristics of polymer solar cells.     

XD-1 新型锥度螺旋填料的流体力学特性与机理

XD-1型锥度螺旋填料独特的锥度螺旋结构能使气液二相由逆流接触转变为错流接触,使之与常规填料有完全不同的流体力学特性。在80 mm的冷模实验塔内,用空气-水物系测定了填料的流体力学特性,还与θ环、拉西环和丝网波纹填料进行了比较。实验结果表明,在相同喷淋密度下,锥度螺旋、拉西环、θ环和波纹丝网4种填料的空隙率之比为:0.823∶0.781∶0.947∶0.855时,单位填料层压降之比为:0.58∶1.35∶1.08∶0.65,泛点气速之比为:0.725∶0.280∶0.658∶0.703。