HEAT TRANSFER CHARACTERISTICS OF THREE PHASE FLUIDIZED BEDS

Heat transfer characteristics of two (liquid-gas, liquid-solid) and three (liquid-gas-solid) phase fluidized beds have been studied in a 15.2 cm-ID column fitted with an axially mounted cylindrical healer. Effects of gas velocity (0-12 cm/s). liquid velocity (0-16cm/s), particle size (1.7-8.0 mm) and liquid viscosity (0.001-0.039 Pa s) on heat transfer coefficient were determined. The heat transfer coefficient increased with fluid velocities and particle size and it decreased with liquid viscosity in two and three phase fluidized beds. The bed porosity at which the maximum heat transfer occurred decreased with particle size but increased with liquid viscosity. The coefficient were correlated in terms of experimental variables. Modified Nusselt number from the present and previous studies has been correlated with modified Prandtl and Reynolds numbers.     

多动程胶辊的开发和应用

探讨多动程胶辊开发与使用性能。通过分析细纱胶辊的应用现状,将过去的单一通道变为左中右三个通道,研制了多动程胶辊,并与传统胶辊进行了纺纱质量、磨砺周期、使用寿命及成本对比分析。结果表明:多动程胶辊对成纱质量无负面影响,磨砺周期及使用寿命明显增加,使用成本降低指出应用多动程胶辊时要调整好纱线通道位置和卡圈位置,以确保成纱质量稳定。     

Scleral lens wear: Measuring inflammation in the fluid reservoir

PurposeTo measure inflammatory mediators in the scleral lens fluid reservoir (FR) in healthy eyes and to compare them to basal tear samples after 8-hs (8h) and 4-days (4d) of scleral lens (SL) wear.MethodsFifteen normal, habitual soft contact lens wearers were fitted with 14.8- or 15.4-mm SLs (Zenlens, Alden Optical, USA). Basal ocular surface tears and FR samples were collected after 8h and 4d of daily SL wear. Levels of interleukin (IL) -4 and -8, matrix metalloproteinase (MMP)-7, -9, and -10, and tissue inhibitor of MMPs (TIMPs) 1–4 were measured in all samples using Luminex assays. Visual acuity, corneal and conjunctival staining, and comfort assessments were completed at the baseline, 8h and 4d time points.ResultsMMP-9 and MMP-10 were greater in FR than basal ocular surface tears. After 8h of SL wear, the median concentration of MMP-9 in the FR and basal tears were 62.7 and 15.2 ng/mL, respectively (p = 0.047). Likewise, MMP-10 was significantly greater in FR compared to basal tears, after 8h (25.8 ng/mL vs 2.8 ng/mL, p < 0.001) and 4d (2.1 ng/mL vs17.2 ng/mL, p = 0.047). IL-4 and IL-8 levels were greater in FR but not significantly at 8h (2.2 vs 3.1 ng/mL; and 0.1 vs 0.4 ng/mL, respectively) or 4d (0.9 vs 3.5 ng/mL; 0.0 vs 0.2 ng/mL). MMP-7 was not affected by SL wear after 8h (46.0 basal vs 54.4 ng/mL FR) or 4d (34.2 vs 87.5 ng/mL). Visual acuity, corneal and conjunctival staining did not change; comfort was reduced in SL compared to soft contact lens wear.ConclusionsThis is the first study to compare the FR with the basal ocular surface tears. MMP-9 and MMP-10 were elevated in the FR after several hours of SL wear, suggesting potential clinical implications of SL wear and deserves further investigation.     

A review on adsorption refrigeration technology and adsorption deterioration in physical adsorption systems

As one kind of environmentally friendly refrigeration, the adsorption refrigeration has attracted many attentions in resent decades. This paper introduces the researches of adsorption refrigeration systems with the commonly used working pairs, advanced adsorption cycles, heat and mass transfer enhancement and attempts of adsorption refrigeration applications. Poor heat and mass transfer problem is a bottleneck to prevent the improvements of the adsorption refrigeration technique. Two ways to enhance the heat and mass transfer are discussed in this paper. The adsorption deterioration of adsorbent, another obstacle to physical adsorption refrigeration applications, is also pointed out. And the possible reasons and the possible methods are analyzed.     

Heat and mass transfer and fluid flow in cryo-adsorptive hydrogen storage system

Compared to room temperature adsorption, cryo-adsorptive hydrogen storage capacity has been greatly improved, and has become the central issue of the hydrogen storage research. Accurate simulation and optimization for cryo-adsorptive hydrogen storage has important guidance and application value to the experimental research, and the finite element software Comsol Multiphysics™ and system analysis software Matlab/Simulink™ can be used to simulate the cryo-adsorptive hydrogen storage. However, the computational fluid dynamics (CFD) software Fluent™ can provide more information on the heat and mass transfer and the fluid flow than above softwares. Based on the mass, momentum and energy conservation equations, this paper uses the modified Dubinin–Astakhov (D–A) adsorption isotherm model, linear driving force (LDF) model and dynamic thermal boundary condition which are implemented by means of CFD software Fluent to simulate the hydrogen adsorption processes of charging and dormancy in the case of liquid nitrogen cooling. We study the variations of temperature and pressure during the processes of charging and dormancy. The results show that the experimental data is in good agreement with the simulation results. We also analyze the effect of variable specific heat and anisotropic thermal conductivity on the heat and mass transfer and the fluid flow in cryo-adsorptive hydrogen storage system.     

Study on lubrication performance of hydrostatic clearance oil film considering multi-factor coupling

The lubricating performance of the clearance oil film determines the machining accuracy of the hydrostatic thrust bearing and the stability of the oil film. From the perspective of working parameters and cavity structure, based on tribological principles and lubrication theory, the clearance oil film temperature rise equation, pressure equation, and viscosity-temperature equation are deduced, and the relationship between load-rotating speed-oil film thickness for different cavity shapes is matched. Through the combination of simulation and experiment, the multi-factor coupling influences on the lubricating performance of the clearance oil film are studied. The study found that the degree of influence on the clearance oil film temperature is in order: rotational speed, hydraulic oil viscosity, load, and cavity depth, and the degree of influence on the clearance oil film pressure is in order: load, hydraulic oil viscosity, rotational speed, and cavity depth. This work provides a theoretical basis for the research and optimization of the lubrication performance of hydrostatic thrust bearings, and provides a research direction for the machining accuracy and running stability of high-speed and heavy-duty CNC equipment.     

A review of impulse turbines for wave energy conversion

Oscillating Water Column based wave energy plants convert wave energy into low pressure pnuematic power in the form of bi-directional air flows. Air turbines which are capable of rotating uni-directionally in bi-directional air flow, otherwise also known as self-rectifying turbines, are used to extract mechanical shaft power which is further converted into electrical power by a generator. This paper reviews the state of the art in self-rectifying impulse air turbines. New results on optimum parameters for the fixed-guide-vane impulse turbine are also presented. Starting characteristics and conversion efficiencies of two types of impulse turbines are compared with the well known Wells turbine.     

对工作帮坡角的研究与探索

以南芬铁矿为基地,探索组合台阶开采的工作帮坡角变化规律。以作业模型为开采费用计算依据,在分层条带式矿床模型上进行模拟开采,并对剥岩量进行均衡。模拟结果指出:由于组合台阶的结构不同,开采费用是随工作帮坡角的增大在上下波动中逐渐减小,按等价原则分析,工作帮坡角有等价变化域并互有重叠。认为工作帮坡角的可靠优化结果为其最优等价控制域,在该域内的全部组合台阶结构方案均属最优。     

分散染料染色新工艺及理论（上）

较系统地介绍了近年来出现的两种分散染料染色新工艺及其理论,即超临界二氧化碳流体染色和助剂增溶染色。对这两种染色工艺的优缺点作了深入分析,并介绍了作者利用自己研制的专用助剂,用分散染料染羊毛纤维,证实了这种新工艺的可行性,开拓了羊毛染色的另一种途径,具有理论和实用价值。     

CHEMICALLY INDUCED MIGRATION OF PARTICLES ACROSS FLUID STREAMLINES

The velocity of a colloidal particle that moves because of a gradient of concentration of a molecular solute depends on the concentration field at the surface of the particle. Effects of macroscopic convection of the suspending fluid on two such transport phenomena, capillary-driven movement of fluid particles and diffusiophoresis of rigid particles, are considered here. In the case of fluid particles our results also apply to motion caused by a temperature gradient. If the particles are in a laminar flow with the solute gradient directed perpendicular to the direction of flow, as might arise in the boundary layer near a surface to which the particles are being deposited, the local solute concentration field around each particle is disturbed from that of pure diffusion of the solute. Using published results for these concentration disturbances in a simple-shear flow, we determine the effect of the imposed velocity gradient on the speed of the particles in the direction of the solute gradient. For both fluid and rigid particles, the correction due to macroscopic shear is 0(Pe^3/2:) where Pe is the Peclet number based on particle radius and fluid shear rate; this effect opposes the zero-shear particle velocity. A possible consequence of this result is that by increasing the shear rate in a laminar boundary layer in the hope of enhancing the rate of particle adsorption, one may actually be decreasing the rate.