Comparison of Solid-Liquid and Liquid-Liquid Mass Transfer

Abstract

Mass transfer from solutions of m-acetotoluide, phenacetin and salicylamide into a stationary solvent, water, was studied. A sharp concentration jump was found at the leading solute front for all three liquid-liquid systmes. A comparison was made between the mass transferred in solid-liquid and liquid-liquid systems. The dissolution of m-acetotoluide, phenacetin and salicylamide was compared with mass transfer of solute from solutions with concentrations C_i, 2C_i and C_s into the pure solvent. In all cases, the amount dissolved from the solid was approximated by the C_i or the 2C_i-solvent system with the amount transferred in the C_s-solvent system approximately 100 fold greater than was dissolved from the solid. It was concluded that a concentration much less than saturation exists at the solid-liquid interface and that dissolution of the three compounds studied is controlled by the rate of solvent interaction at the solid surface.     

Heat and Mass Transfer in Anisotropic Bodies

This review is aimed, on the one hand, at attracting the researchers' attention to the problems associated with heat transfer in anisotropic bodies and, on the other hand, at analyzing the scanty experience in investigating the heat transfer in anisotropic bodies that has been accumulated over the last 30 years. We treat conjugate heat transfer between boundary layers and anisotropic bodies, and heat transfer under conditions of simultaneous reciprocal influence of anisotropic thermal conductivity and anisotropic filtration upon film cooling of bodies with anisotropic properties. New effects are revealed during simulation of conjugate heat transfer; the law of nonlinear filtration in anisotropic bodies is identified; and the effect of individual components and of the orientation of the principal axes of thermal conductivity and penetrability tensors on stationary temperature fields and on the distribution of components of the filtration rate is investigated. The results of analytical investigation of heat transfer in anisotropic bodies enables one, under conditions of lack of adequate information, to exactly simulate nonstationary temperature in simplest anisotropic bodies, which may be used as test results. A number of recommendations are formulated for implementation of heat shielding of anisotropic bodies under conditions of their aerogasdynamic heating.     

湿膜加湿器热质交换过程分析

湿膜加湿器是利用直接蒸发加湿的工作原理,对空气进行加湿,只消耗风机和循环水泵的电耗,具有结构简单和节省能源的优点。本文根据热质交换理论对湿膜加湿的传质过程进行了理论分析,建立了湿膜加湿器的传热、传质微分方程,得出影响加湿量的主要因素,并讨论了它们的影响趋势。     

Nonstationary Heat and Mass Transfer in Molecular Gases

The analytical solution of the problem on a nonstationary heat source in a diatomic gas has been given. The characteristics of the temperature and sound waves excited by it have been obtained. The distribution of the pressure, temperature, and concentration of the gas molecules has been considered.     

Regularities of Hydrodynamics and Mass Transfer in Jet Apparatuses

Consideration is given to the influence of different (geometric and hydromechanical) parameters on ejection; an equation describing the ejection is proposed; a maximum possible ejection coefficient is calculated from this equation, and an attempt is made to experimentally calculate the coefficient of overall mass transfer from the evaporation of water from a jet apparatus.     

一次砝码国际比对

介绍了中国航空长城计量测试研究所质量校准实验室参加亚太地区国际实验室之间砝码比对的情况,给出了测量结果的不确定度分析。     

Heat and Mass Transfer Measurements for Tray-Fermented Fungal Products

In this study, heat and mass transfer in static tray fermentation, which is widely used in solid-state fermentation (SSF) to produce fungal products, such as enzymes or koji, is investigated. Specifically, kinetic models of transport phenomena in the whole-tray chamber are emphasized. The effects of temperature, moisture, and humidity on microbial growth in large-scale static tray fermentation are essential to scale-up SSF and achieve uniform fermentation. In addition, heat and mass transfer of static tray fermentation of Trichoderma fungi with two tray setups??traditional linen coverings and stacks in a temperature?Chumidity chamber is examined. In both these setups, the following factors of fermentation were measured: air velocity, air temperature, illumination, pH, carbon dioxide (CO₂) concentration, and substrate temperature, and the effects of bed height, moisture of substrate, and relative humidity of air are studied. A thin (1 cm) bed at 28 °C and 95 % relative humidity is found to be optimum. Furthermore, mixing was essential for achieving uniform fermentation of Trichoderma fungi. This study has important applications in large-scale static tray fermentation of fungi.     

溶剂小分子在高分子中的传质研究评述

溶剂在高分子中的传质涉及化工、材料、医药等多个领域,对其进行研究可扩充以研究小分子为主的传统传质理论,并可为传统产业、制药工业、资源利用和环境保护以及新能源开发带来直接经济效益。溶解性和扩散性是描述溶剂在高分子中传质现象的两个关键因素。文中分析了溶剂在高分子中传质研究的意义,结合该实验室的课题研究成果,对溶解性模型和扩散性模型的发展进行较为详细的综述,并指出其发展方向。     

Mass Transfer and Osmotic Phenomena in Swollen Organic Substances

The mechanisms of mass transfer under the action of the hydrostaticpressure, temperature, and dissolvedsalt concentration gradients and electroosmosis in swollen heterogeneous organic materials have been considered. Mass transfer is similar to the migration of water and solutes in ordinary solutions and represents discrete translational displacements of particles. It is accompanied by ionexchange processes and leads to a change in the structure of the material.     

质量计量标准传递信息反馈系统

着重介绍建立质量标准传递信息反馈系统的必要性、实施步骤、测量过程参数的建立与控制方法。     

添加纳米粒子的溴化锂溶液传质特性

建立了纳米溴化锂溶液二维降膜传热传质数学模型,以实验数据对模型进行验证。研究结果表明,在溴化锂溶液中加入纳米粒子可以显著增强溴化锂溶液对水蒸气的吸收速率,并且随着纳米粒子添加量的增大,纳米溴化锂溶液对水蒸气的吸收速率越大;在纳米粒子添加量相同时,纳米溴化锂溶液的水蒸气吸收速率随着溶液流量的增大而增大,且水蒸气吸收速率随溶液流量的变化趋势为对数曲线趋势;溶液的传质强化比随着纳米粒子添加量的增加而增大;在溴化锂溶液中加入纳米粒子后,吸收器的传质系数随着纳米粒子添加量的增大而增大,在溶液流量为1.2 L/min时,添加0.05%纳米粒子后,吸收器传质系数增加1.32倍,添加0.1%纳米粒子后,吸收器传质系数增加1.41倍,但是,传质系数增幅随着纳米粒子含量的增加而逐渐减弱。     

Action of Vibrations on Heat and Mass Transfer in Boiling

The state of the art of the works known in the literature and concerned with the influence of vibrations of structures of plants and artificially initiated vibrations in working liquids on the processes involving boiling is analyzed. The authors discuss theoretical and experimental results on the influence of frequencies and amplitudes on the internal characteristics of boiling, namely, the initiation of a vapor phase, the superheat in boiling, the growth and separation of vapor bubbles and the frequency of their occurrence, the density of nucleation sites, and also on the value of the heat fluxes and on the heattransfer coefficient. Application of vibrational actions for intensification of heat and masstransfer processes is shown to be promising.     

扩散渗析总传质系数计算式的推导与探讨

推导出大面积扩散渗析总传质系数K的计算式,该计算式由两部分组成,其中,Kc表示在溶液体积不发生变化时,仅由溶质浓度梯度引起的传质;Kw表示由水反渗导致的溶液体积变化引起的传质.除此之外,还通过卷式循环扩散渗析实验,定性的研究了流量对两种扩散渗析传质及总传质系数的影响.结果表明,扩散过程中Kc,基本占主导地位;随着流量的增加(100～300 mL/min),Kc逐渐减小,而Kw却不断增大;导致总传质系数K先略有增大,后逐渐减小;其中,流速为200 mL/min时,总传质系数最大.     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Influence of Heat and Mass Transfer on Wood Impregnation Kinetics

We have further developed the nonstationary mathematical model of twophase filtration in an anisotropic porous medium — wood — by a fluid, taking into account the temperature dependence of its viscosity. The results of the calculations of the temperature and kinetics of wood impregnation under the action of vacuum and excess pressure for the problem of internal and external heat transfer are presented. The process of preservative impregnation of woodworks with a wateroil emulsion for various degrees of filling of the autoclave, including the maximum one, has been simulated.     

Similarity of Heat‐ and Mass‐Transfer Processes in Drying

The possibility of the existence of a hydrodynamically invariant relation between individual parameters of the process of convective drying is studied. The presence of a relation of this kind is a consequence of the similarity of processes that is typical of regular modes of heat and mass transfer.     

Motive Force in a Complex Model of Mass Transfer

Relations for determining a motive force in a complex model of mass transfer as applied to concurrent, countercurrent, and cross motion of the vapor and liquid phases have been introduced. These forces have been compared for different forms of organization of the flow, and their comparison with similar quantities from the known Murphree and Hausen models is presented.