查询词典 convection heat transfer

Firstly, the mechanism of heat transfer enhancement by oscillation heat surface is discussed in natural convection scene. For different oscillation amplitude and Rayleigh number, the frequency that the heat transfer rate of oscillation heat surface is higher than non-oscillation condition is found and called critical oscillation frequency. The limitation enhancement of similar physical model is still researched by this study in mixed and forced convection scenes for different amplitude and Grashof number.

首先探讨在垂直管道内振动高温面於自然对流领域内提升高温面热传效率的机制，并且针对不同的振幅与雷利数求得加入振动条件后，高温面散热效果可以优於稳态非振动高温面散热效果的临界振动频率；进而探讨当垂直管道流进入混合对流与强制对流范围时，在不同的振幅与葛瑞秀夫数下，亦可发现加入振动条件后，振动高温面之散热效果可以优於稳态非振动高温面散热效果的临界振动频率。

Water inside vacuum heat- collection tubes; since the hot medium inside vacuum tubes floats up and cold one goes down due to respective specific gravity, hot and cold mediums convections up and down to cause the heat conduction, furthermore transfer the heat to the related working medium in the heat tubes, the working medium sorbs the potential heat and becomes steam to rise up to the condensing section from the tube heat evaporating section; it emits the heat in condensing section to change again into liquid working medium; it flows back to evaporating section under the gravity action, the emitted heat is transferred into the water inside water tank or tube group by means of the heat-conduction through heat tubes condensing section; it makes the cold water in water tank into hot water in the repeated way.

阳光透过全玻璃真空集热管的外玻璃，照射到涂覆在内玻璃管外表面的选择性吸收涂层上，涂层将太阳的辐射能吸收并转化为热能，通过内玻璃管壁导热，传递给真空集热管内其液态传热介质，由于真空集热管内热的介质因比重小而上浮，冷的介质因比重大而下沉，冷热介质上下对流传热和导热，再通过热管的金属壁导热，将热量传递给热管内其相变工质，工质吸收汽化潜热而变成蒸汽，由热管蒸发段上升到冷凝段，在冷凝段放热冷凝，又变成液态工质，在重力作用下流回蒸发段，所放出的热量通过热管冷凝段金属管壁导热，传递给水箱或联集管内的冷水，周而复始，于是便将水箱内的冷水全部加热成热水。

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The heat generation curves of seven rubber materials used in tires with the changes of temperature have been obtained by using Dynamic Mechanics Analysis technique on NETZSCH DMA242 instrument, knowing that the heat generation of every other rubber materials except inner liner rubber changes lightly alone with the temperature within 10℃～80℃. According to the Fourier law, the heat transfer coefficients of tire rubber are measured by stable method on self-made experiment instrument. The coefficients changes lineally within 20℃～80℃ and the relation formulas λ=λ〓+bt are given out attached with λ〓 and b. The specific heat of tire rubber are measured on Differential Scanning Calorimeter NETZSCH DSC204 and the relations with temperature are linear and the formula is c=c〓+bT, where c〓 and b gained from experiment result data are presented in the paper. The heat convection coefficients on the surface of rolling tire are measured according to the principle of heat-mass transfer analogy principle after simplifying rolling tire into rotating disk with straight movement on wind channel. The relation with rotation speed of disk is linear as h=5. 399+0.0258n and the relation with straight line speed of tire is linear too, h=

论文采用动态力学分析技术，使用NETZSCH DMA 242型实验仪，获得了轮胎用七种胶料的生热率随温度变化曲线，确知除内衬层胶以外，其它各种胶料在一般胎温范围内（10℃～80℃）的生热率随温度变化不大；轮胎胶料的导热系数根据傅立叶定律的基本原理，采用稳态法在自行搭建的实验台上进行测试，结果表明，材料的导热系数在20℃～80℃的温度范围内随温度呈线性变化，论文给出了各种材料导热系数的线性变化的关系式λ=λ〓+bt及其λ〓和b的值；轮胎胶料的比热运用差式扫描量热原理，在NETZSCH DSC204型DSC实验仪上进行测试，结果表明，胶料的比热随温度的变化呈线性变化，其关系可用c=c〓+bT表示，文中给出了根据实验数据拟合的c〓、b的值；对轮胎表面的对流换热系数的测定，本文先将滚动的轮胎简化为有直线运动的旋转圆盘，而后采用萘升华热质比拟技术，在风洞中测量了滚动轮胎表面的对流换热系数，结果表明，圆盘表面对流换热系数与转速呈线性关系，即h=5.399+0.0258n，轮胎表面对流换热系数与其直线运动的速度呈线性关系，即h=

Studied present measuring methods" advantages and disadvantages, and presented the necessity and importance of researching propellant transient heat transfer.2.according to 130 and aeronautic 90 rocket projectiles" structure, analysed and acquired physical and mathematical models for propellant transient heat transfer, also designed propellant temperature field simulation units for test.3.acquired discrete transient heat balance equation and temperature calculation program, and gave contrasting curves between experimental temperature values and program calculating temperature values as well as maximum errors and average square root errors between them.4.by programs based on the first class boundary condition, worked out temperature distribution in propellant temperature field simulation units at different time, analysed temperature field distribution law and main elements affecting heat transfer, acquired propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.5.established transient heat transfer mathematical model and temperature calculation program for the third class boundary condition, drew contrasting curves between temperature experimental values and calculation values and gave maximum errors and average square root errors between them, got temperature distribution in the simulation unit at different time and main elements affecting heat conduction, figured out propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.

分析了现有测试方法的优缺点，提出了研究推进剂瞬态导热的必要性和重要性。 2。根据130和航90两种火箭弹的结构，分析得到了推进剂传热的物理模型和数学模型，设计了推进剂温度场模拟实验装置。 3。得到了离散形式的瞬态热平衡方程和温度场计算程序，给出了实验温度与程序计算温度值的对比曲线及其最大偏差与均方差。 4。利用程序求出了第一类边界条件下、不同时刻推进剂温度场模拟装置中的温度分布，分析了温度场的分布规律和影响传热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处的温度时间曲线并给出了两者之间的最大偏差与均方差。 5。建立了第三类边界条件下的瞬态导热数学模型和温度计算程序，求出了温度实测值与计算值的对比曲线并给出了两者之间的最大偏差与均方差，得到了不同时刻温度场模拟装置的温度分布与影响导热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处温度及两者之间的最大偏差与均方差，讨论并确定了能代表130和航90推进剂温度的特征点的位置。

The following points are emphasized:The operation models of adiabatic and diabatic distillation have been set up and the operation block, thermodynamics model and mathematical model in the simulation have been determined as well;(2)Based on the simulation and exergy analysis with Aspen Plus program, shortcut distillation design—DSTWU model and rigorous distillation design—RADFRAC model, the author has determined the heat duty, exergy losses and the distribution of exergy losses along the adiabatic column, which will help the simulation and optimization of the diabatic distillation;(3)Diabatic distillation under various operation conditions has been simulated by using energy balance method and exergy analysis;(4)How the different mixture and the various degree of separation, number of trays and feed location influence exergy saving in diabatic distillation have also been discussed;(5)On the basis of the total exergy losses along the column, different schema of the heat transfer distribution along the column have been compared and analyzed;they can be classified in three categories: heat duty equipartition approach, empirical approach, separation degree matching approach. In conclusion, different heat transfer distribution along the column will have effect on total exergy losses. In particular, most satisfactory results have been obtained by using separation degree matching approach. In order to diminish the exergy losses, heat transfer distribution should meet the needs of the request of separation degree.And on this premise, the author makes his suggestion in increasing the proportion of heat supplied to the tray with minimum exergy losses and decreasing the proportion of heat supplied to the tray with the maximum exergy losses.

本文对透热精馏过程进行了模拟并对其节能效果的影响因素做了较为全面的分析和深入的研究，主要研究内容如下：(1)建立了常规精馏和透热精馏过程的模拟操作模块、热力学模型以及数学模型；(2)利用化工模拟软件Aspen Plus并分别采用DSTWU简捷模型和RADFRAC严格计算模型对常规精馏进行模拟计算和有效能分析，确定常规精馏塔的公用工程热负荷、有效能损失及有效能损失在塔内的分布，为透热精馏的模拟和优化提供数据参考；(3)对不同物系在不同分离度条件下进行透热精馏的模拟，分别采用能量衡算法和有效能分析法进行计算和分析；(4)探讨了各种因素如物系的选择、不同分离度、塔板数、进料位置对透热精馏节能效果的影响；(5)以全塔总有效能损失为比较基准，对热量在塔内的三种分布方案即热负荷平均分配法、经验法和分离度匹配法进行了对比分析并得出结论：塔内热量的不同分布方案对于全塔总有效能损失会产生影响，其中以分离度匹配法的节能效果最为理想，为减少有效能的损失，应使塔内的热量分布满足各塔板的分离度要求，并在此前提下，尽量减小有效能损失大的塔板的热负荷和增加有效能损失小的塔板的热负荷。

Our results indicate that not only the poloidal convection patterns in uppermost mantle have good correlations to surface tectonic motion, but also the toroidal ones reveal important information of their horizontal motion and rotation for the first time. There is a SEE_NWW strong convection zone close to the equator in toroidal convection patterns, which probably correlates with the large_scale shear zone near the equator and is the deep dynamic background of strong earthquake occurrence in this zone. The opposite rotating large_scale convection rolls in the Southern and Northern hemispheres suggest that maybe there is differential rotation between them.

研究结果表明，不但地幔浅部的极型场对流图像显示出了与大地构造运动的相关性并揭示了其深部动力学过程，更重要的是，地幔浅部的环型场对流图像首次为我们认识和理解板块构造的水平与旋转运动提供了重要的信息：环型场速度剖面中在赤道附近存在一条大致南东东—北西西向的强对流条带，可能与环赤道附近大型剪切带的形成相关，进而表明可能是该带强震发生的深部动力学背景；在南北半球存在的旋转方向相反的对流环表明它们整体上可能存在差异旋转。

Any high Re number flow over bodies consists of three basic flows: the flow with convection-dominant in all spatial directions, the flow with convection-diffusion competition in all directions and the flow with convection-dominant in part directions and convection-diffusion competition in part directions, which is called the interacting shear flow; the features of the three basic flows are different; their simplest conservation equations, i.e. the Euler equations, Navier-Stokes equations and diffusion parabolized NS equations, have different mathematical characteristics; there is a great disparity in domains of the three basic flows and the domains of NS equations are very small. Therefore, adopting Euler-DPNS-NS equation system to analyze and compute high Re number flows over bodies is a logical approach. There exists a mutual examined-complemented relationship of this approach with the usual one of adopting only NS equations.

主要内容如下：（1）高Re数绕流包含3种基本流动：所有方向对流占优流动、所有方向对流扩散竞争流动和部分方向对流占优部分方向对流扩散竞争流动，3个基本流动的特征彼此不同且在流场中所占领域大小彼此相差悬殊，NS方程区域很小，它们的最简单控制方程组Euler、Navier-Stokes和扩散抛物化NS方程组的数学性质彼此不同，因此利用Euler-DPNS-NS方程组体系分析计算高Re数绕流流动就是一个合乎逻辑的选择，该法与利用单一NS方程组的常用方法可以彼此检验和补充。

The effects of variable properties on flow and heat transfer were also studied. 1. SIMPLEC algorithm was used to simulate the laminar natural convection flow in horizontal concentric annuli with the assumption of constant properties. Numerical studies range are as follows: Ra〓 number 100～10〓, radius ratio 1. 2～10.Velocity and temperature distribution profile and the heat transfer result were derived. The comparison of heat transfer results under the boundary condition of constant heat flux and constant wall temperature was also made.

对水平同心套管内层流自然对流采用SIMPLEC算法进行了数值模拟，在〓，半径比1.2～10范围内使用定物性假设进行了计算，得到有关温度和速度的分布以及相应的换热结果，并比较了内壁面分别处于定热流和定壁温条件下换热结果的差异，根据换热计算的结果整理并拟合有关的换热关联式。

In this paper, research is focused on the heat and mass transfer features during absorption process on the two-scale corrugation plate surfaces of plate-shell heat exchangers. This new Kind structure has vertical large corrugations and horizontal small ones, which can enhance the convection heat transfer of cooling water at internal plate channel side and make the liquid falling film uniformly distributed and turbulent by twisting path, so that the heat and mass transfer characteristics at both sides can be enhanced while sufficient flow area for adequate resistance requirement is also met.

本论文围绕一种新型交叉双尺度波纹板片组成的板壳式吸收器进行研究，这种新型传热元件的相邻板片的竖直大波纹相顶靠，形成曲折的板内通道和菱形板外通道，可强化板内侧冷却水的对流传热，而其水平小波纹则可对布膜的溴化锂浓溶液和冷剂蒸汽产生连续的扰动，使液膜分布均匀，传热传质得到强化。

Listen,point and check your answers.

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