考虑管间液滴形成和下落过程的吸收器模拟及分析

针对以溴化锂水溶液为工质的水平管吸收器，考虑管底部液滴形成和管间下落过程，建立了描述管间滴状形成和下落吸收过程传热传质耦合数学模型。根据数值计算结果，分析了溶液温度、浓度和吸收速率沿管排不同位置和水平管管间的变化，分析了管间距对吸收器整体传热传质性能的影响。结果表明，滴状吸收过程约占总吸收量的30%。与实验数据的对比说明提出的数学模型是合理的。     

间隙距离对冷凝式换热器性能的影响

应用计算流体力学(CFD)方法,建立了盘管式冷凝换热器的三维数学物理模型;探讨了内部边界耦合的传热、传质过程,对换热器冷凝传热过程进行了三维数值模拟;在模拟数据的基础上,对不同盘管间隙下换热器传热过程进行了比较,并得到其性能变化情况.     

切片土豆干燥中传质过程模拟与分析

建立切片土豆内部传质模型，内部传热模型来研究土豆干燥过程的传质模拟，并进行了实验验证，验证结果表明：用整个物料平均水分来间接验证，模拟值和实测值十分接近，二者的最大相对偏差小于9．1％，模拟结果表明：土豆片表层水分在热风的作用下得到蒸发，水分下降很快，在表内水分差作用下内部水分向表层迁移，干燥过程中产生表低内高水分分布规律。     

关键部件湿化器性能的分析

建立了传热、传质微分方程以及能量、质量守衡方程,利用实验研究给出的传热与传质系数的经验关联式,沿湿化器高度积分,得到各参数及湿化器内传热传质推动力 焓差沿湿化器高度的变化,计算分析了湿化器的设计工况性能和变工况性能,为湿化器的设计和开发提供了理论依据     

对大体积混凝土的认识

大体积混凝土的主要特点就是体积大,一般实体最小尺寸大于或等于1m。它的表面系数比较小,水泥水化热释放比较集中,内部温升比较快。混凝土内外温差较大时,会使混凝土产生温度裂缝,影响结构安全和正常使用。     

管式降膜一效蒸发器的工艺设计

本文在给定的设计条件下介绍了蒸发器蒸发量、传热量、传热面积、总传质系数等参数的计算,并提出了蒸发器的节能方法。     

磁力驱动技术在超重力旋转床上的应用研究——温州市工业科学研究院成果推介

一、项目概况 温州市工业科学研究院成功研制了一种新型的过程强化设备：磁力驱动超重力旋转填料床。其工作原理是高速运转的填料转子会产生数百倍至千倍重力的离心力（即超重力）,由此液相在填料表面形成液膜,液膜快速向外环流动的同时厚度急剧减小,载体相界面积增加导致了由液相控制的传质、传热和反应过程得到极大的强化。     

错列翅片板翅式换热器速度场的数值模拟

由于错列翅片板翅式换热器的传热性能在很大程度上与内部流体的流速有关,本文采用ANSYS软件中的CFD模块,对换热器内流体的速度场进行数值模拟。定性地研究了在不同的翅片尺寸和不同的流动方式下,流体流速及其压降的变化,为错列翅片板翅式换热器的结构设计提供了有力依据。     

高温固液浸润行为研究取得新进展

中科院化学所有机同体重点实验室研究人员研究了特定温度下,液滴在高温固体表面发生的浸润／去浸润转变现象,并对相关机理进行了阐述。研究人员发现,对于浸润性为亲水性、疏水性和超亲水性的粗糙结构表面,当表面温度升高剑某一特定温度,水滴在滴剑同体表面时会发生南浸润铺展到去浸润弹起的转变,且液滴弹起温度（Tb）会随着表面粗糙度的改变而规律性变化。     

多孔介质传热传质研究的意义与现状

本文简要论述在我国支持开展多孔介质传热传质基本研究的重要性和必要性,不仅对我国工农业发展有着广阔的实际应用背景,也是形成交叉和边缘学科的一个潜在生长点。     

Development and evaluation of realistic microbioassays in freely suspended droplets on a chip

A novel technique for biomolecular detection in microliter droplets floating on the surface of high density oil is presented. Each droplet was captured and manipulated dielectrophoretically and was used as a site for a microscopic bioassay based on agglutination of antibody-conjugated particles. The results were read out by the pattern of unagglomerated gold nanoparticles collected on the droplet surface. Two formats of bioassays, namely gold only agglutination and gold and latex agglutination, were investigated experimentally by varying analyte concentration, particle size and concentration, number of antigen binding sites per particle, time for incubation, and rate of particle collection on the droplet surface. The microbioassays performance was also evaluated with ricin antibodies and compared to the ricin assays in field use. It is estimated that the droplet based assays require 100× smaller sample volume and are ten times more sensitive, though they require longer times to complete. The experiments were interpreted by modeling the kinetics of particle agglutination and mass transfer processes inside the droplets. The incubation time and antigen concentration values calculated by the model correlate well with the experimental results. The results could allow for development of efficient immunoassays on a chip requiring even smaller sample volumes.     

A novel actuation method of transporting droplets by using electrical charging of droplet in a dielectric fluid

We evaluate the feasibility of manipulating droplets in two dimensions by exploiting Coulombic forces acting on conductive droplets immersed in a dielectric fluid. When a droplet suspended in an immiscible fluid is located near an electrode under a dc voltage, the droplet can be charged by direct contact, by charge transfer along an electrically conducting path, or by both mechanisms. This process is called electrical charging of droplet (ECOD). This charged droplet may then be transported rapidly by exploiting Coulombic forces. We experimentally demonstrate electrical actuation of a charged droplet by applying voltage sequences. A charged droplet is two dimensionally actuated by following the direction of the electrical field signal. The droplet does not contact the surface of the microfluidic chip when it moves. This characteristic is very advantageous because treatments of the substrate surfaces of microfluidic chip become simpler. In order to test the feasibility of using ECOD in a droplet-based microreactor, electrocoalescence of two oppositely charged droplets is also studied. When two droplets approach each other due to Coulombic attraction, a liquid bridge is formed between them. We postulate that if the applied electric field is weaker than a certain critical level, the two droplets coalesce instantaneously when the charges are exchanged and redistributed through this liquid bridge.     

微型钢管外表面温度场可视化实验研究

为了准确测量微管外表面温度场的分布，并解决沿微管轴向导热对微管内部对流换热的影响，本文首次把非接触式测量温度方法引入到微尺度实验中。本次研究搭建了能够进行气体、液体流动与换热的微流动实验台，用蒸馏水作为工质，采用红外成像仪加专用红外放大镜头对微型钢管表面温度场作了可视化实验研究，得到了在Re数不变时，不同加热功率下内直径为168µm和外直径为406µm微型钢管外表面温度场的分布图，进而能得到了沿轴向温度对沿轴向长度的二次导数。建立简化的数学模型，并通过推导获得了沿轴向的导热对内部对流换热的关系式。实验与理论推导结果表明，在微圆管单相流情况下，其轴向的导热对管内对流换热影响很小，可以忽略不计。     

Thermal diffusion and diffusion thermo effects on unsteady MHD free convection flow over a stretching surface considering Joule heating and viscous dissipation with thermal stratification,chemical reaction and Hall current

The present investigation is concerned with the effects of thermal-diffusion and diffusion-thermo on an unsteady MHD free convection boundary layer flow with heat and mass transfer of an electrically conducting fluid over a stretching sheet in the presence of strong magnetic field with Hall current, thermal stratification, chemical reaction, heat generation, thermal radiation, Joule heating and viscous dissipation. The transformed nonlinear boundary layer equations are numerically solved by applying Keller-box method. The influence of various embedded flow parameters on the local skin friction, the local Nusselt number and the local Sherwood number has been carefully analyzed through graphs. It is found that the shear stress and the rate of mass transfer increase with an increasing of current density _Jh$J_h$ while the reverse trend is observed on the rate of heat transfer. It is also found that the shear stress and the rate of heat transfer increase with an increasing of Sr  , whereas the reverse trend is observed on the rate of mass transfer. Further, the shear stress and the rate of mass transfer increase with an increasing of Du$Du$ while the reverse trend is seen on the rate of heat transfer. The numerical results are compared and found to be in good agreement with previously published results under special cases.     

Study for optical manipulation of a surfactant-covered droplet using lattice Boltzmann method

In this study, we simulated deformation and surfactant distribution on the interface of a surfactant-covered droplet using optical tweezers as an external source. Two optical forces attracted a single droplet from the center to both sides. This resulted in an elliptical shape deformation. The droplet deformation was characterized as the change of the magnitudes of surface tension and optical force. In this process, a non-linear relationship among deformation, surface tension, and optical forces was observed. The change in the local surfactant concentration resulting from the application of optical forces was also analyzed and compared with the concentration of surfactants subjected to an extensional flow. Under the optical force influence, the surfactant molecules were concentrated at the droplet equator, which is totally opposite to the surfactants behavior under extensional flow, where the molecules were concentrated at the poles. Lastly, the quasi-equilibrium surfactant distribution was obtained by combining the effects of the optical forces with the extensional flow. All simulations were executed by the lattice Boltzmann method which is a powerful tool for solving micro-scale problems.     

A decomposition analysis on convecting–radiating rectangular plate fins for variable thermal conductivity and heat transfer coefficient

The present study concentrates to make a complete thermal analysis on a rectangular fin with its primary surface by taking into consideration of radiation heat exchange with the surrounding along with the convective mode of heat transfer. The one side of the primary surface is heated by a fluid with high temperature which may be required to dissipate heat quickly by a fin array system. To analyze an actual case study, the thermal conductivity of the fin material and convective heat transfer coefficient over the surface are treated as a variable and they are as a function of the local fin surface temperature. With the aforementioned condition, the energy equations for both the fin and primary surface become nonlinear. The decomposition method is suggested to solve these highly nonlinear equations to obtain a closed form temperature distribution. The result of temperature distribution determined by the present analysis is compared with that of the numerical values. With the adaptation of the simplified case, the present method is also compared with the exactly closed form results. From both of these comparisons, an exact matching of results is found. The fin performances, namely, fin efficiency, surface efficiency and augmentation factor are evaluated for a wide range of thermogeometric parameters.     

矩形微槽内水的流动沸腾换热及可视化实验研究

本实验以水为工质，对截面尺寸为0.4mm×0.4mm水平布置的不锈钢矩形微槽内流动沸腾进行换热特性和可视化研究.质量流速范围为G＝62.5～187.5kg/m2s，进口温度分别为Tin＝30、45、 60°C.实验结果表明，在较低干度下，换热系数随着干度的增加而增加；干度较大时，换热系数保持不变直至换热恶化.质量流速的增加使换热系数有较大增加，进口温度的变化对换热系数几乎没有影响.可视化研究发现低壁面过热度时，有大量气泡产生；在本实验范围内，微槽内沸腾的流型主要有塞状流和环状流两种.     

Effect of slippage on the thermocapillary migration of a small droplet

We conduct a numerical investigation and analytical analysis of the effect of slippage on the thermocapillary migration of a small liquid droplet on a horizontal solid surface. The finite element method is employed to solve the Navier-Stokes equations coupled with the energy equation. The effect of the slip behavior on the droplet migration is determined by using the Navier slip condition at the solid-liquid boundary. The results indicate that the dynamic contact angles and the contact angle hysteresis of the droplet are strictly correlated to the slip coefficient. The enhancement of the slip length leads to an increase in the droplet migration velocity due to the enhancement of the net momentum of thermocapillary convection vortices inside the droplet. A larger contact angle leads to an increase in the migration velocity which in turn enlarges the rate of the droplet migration velocity to the slip length. There is good agreement between the analytical and the numerical results when the dynamic contact angle utilizes in the analytical approach obtained from the results of the numerical computation, and the static contact angle is smaller than 50°.