Explicit analytical solutions of transport equations considering non-Fourier and non-Fick effects in porous media

Based on the method of separation variables with addition developed in recent years, new methods of separation variables are proposed, and two algebraically explicit analytical solutions to the general partial differential equation set of non-Fourier and non-Fick heat and mass transfer in porous media drying are derived. The physical meaning of these solutions is simple and clear, and they are valuable for computational heat and mass transfer as benchmark solutions.     

Explicit analytical solutions of transport equations considering non-Fourier and non-Fick effects in porous media

Based on the method of separation variables with addition developed in recent years, new methods of separation variables are proposed, and two algebraically explicit analytical solutions to the general partial differential equation set of non-Fourier and non-Fick heat and mass transfer in porous media drying are derived. The physical meaning of these solutions is simple and clear, and they are valuable for computational heat and mass transfer as benchmark solutions.     

非线性拟抛物粘性扩散方程的显式精确解

研究了出现在人口动力学和稳定分层粘性湍动慢剪切流中热与质量传输理论的一类非线性拟抛物粘性扩散方程.借助于分离变量方法获得了所研究方程的一些精确解,包括整体光滑解和精确爆破解.这些解有助于定性或数值分析非线性拟抛物粘性扩散方程解的性态.     

Explicit analytical solutions of the coupled differential equations for porous material drying

Some explicit analytical solutions are derived for the coupled partial differential equation set describing porous material drying with two extraordinary methods proposed by the authors, i.e. the method of separating variables by addition and the method of evaluating the source term in reverse order. Besides their theoretical meaning, these solutions can also be the standard solutions for the computational solutions of heat and mass transfer.     

空气间隙式膜蒸馏的传质机理

空气间隙式膜蒸馏是一种新型膜分离技术。采用一维定常流动及空气间隙层中不冷凝的假定,对空气隙膜蒸馏系统的传质传热机理进行了理论研究,数学推导中对相关物理量进行了量阶分析,提出小量假设,导出了计算蒸馏通量的理论公式。还通过膜蒸馏实验测定自来水、盐水、染色水和碱溶液等４ 种不同溶液的膜蒸馏通量,理论分析和实验结果的比较表明所提出的理论公式能正确预测蒸馏通量     

单组分体系质量交换网络和换热网络同步综合

为实现单组份体系质量交换网络(mass exchanger network,MEN)和换热网络(heat exchanger network,HEN)同步综合,提出一种新的综合方法,并针对过程系统中质量交换网络和换热网络耦合关系强、连接参数(传质温度)作为优化变量在两网络同步优化时难度大的问题提出了解决方案。采用质量夹点法综合质量交换网络、虚拟温焓图法综合换热网络来构造总网络数学模型,并通过提出连接参数与总网络同时优化的策略,实现质量和换热总网络(com-bined mass and heat exchanger network,CM&HEN)全局同步优化。采用实例对所提方法进行验证,结果表明:该方法所需的年度总费用更低,说明该方法不仅能够实现同步综合,而且能获得更优解。     

利用Bessel函数求解波动方程的定解问题

分离变量法是求解波动方程定解问题的一种重要方法。分离变量法的重点在于求特征值及其对应的特征函数。Bessel函数是应用很广泛的一种特征函数,运用Bessel函数的有关性质可以很方便地求解波动方程的定解问题。     

场协同原理强化管外降膜吸收传热特性实验研究

对基于场协同原理设计的两种强化传热管型进行了LiBr降膜吸收水蒸气过程的传热实验研究,并与光滑铜管作比较,考查该传热管型在吸收过程中的强化作用.实验测量参数包括;溶液进出口温度、浓度,流量,冷却水进出口温度、流量等.实验结果表明,两种强化传热管型在低雷诺数时对LiBr降膜吸收传热的强化比分别为20%和50%,而且随着雷诺数的增大而增大.利用场协同理论和降液膜流动的波动特性分析了强化降膜吸收过程传热特性的物理机制,发现速度矢量与温度梯度的夹角及降液膜厚度形成的阻力对对流换热有一定影响.     

具有低渗流壁的圆管中的层流传质

提出了具有低渗流壁圆管中对流传质的数学模型，将传热伟质的经典Ｇｒａｅｔｚ问题扩展到圆管中Ｋ２＜０情况下的二维层流传质问题，并采用分离变量法进行了解析求解。此还以膜超滤和血液透析滤过过程为例讨论了模型的应用。     

一种时域精细算法求解二维双曲热传导问题

采用一种时域精细算法来求解二维双曲热传导正问题，在离散时间段内将各变量展开，能够对各变量更精确地进行描述，对于非线性问题不需要进行迭代，给出了数值验证，并与其它算法进行了比较。     

地板辐射供暖系统传热的简化解析计算

对地板辐射供暖系统传热的一般数字模型做了简化处理 ,应用分离变量法得到简化模型的解析解 ,并给出算例     

传热过程中的某些优化控制问题

考察了工程热物理研究和设计过程中提出的一类传热过程的热流量优化控制问题，这归结为偏微分方程约束下的泛函变分问题。在区域具有一定对称性，同时传热系数具有分离变量结构的假定下，利用分离变量直接求解所给出的信息，分别导出了边值最佳选取和传热系数最佳选取问题的最优解。这对于一般情况下缺乏对称性的问题的研究也具有启发意义。     

Explicit analytical solutions of the coupled differential equations for porous material drying

Some explicit analytical solutions are derived for the coupled partial differential equation set describ-ing porous material drying with two extraordinary methods proposed by the authors, I.e. The method of separating vari-ables by addition and the method of evaluating the source term in reverse order. Besides their theoretical meaning, these solutions can also be the standard solutions for the computational solutions of heat and mass transfer.     

稳态胞晶生长控制方程的解析解及其传输行为

建立了稳态胞晶生长温度场数学模型.通过在复数域内应用分离变量法对控制方程进行求解,得到了问题的解析解.讨论了在某些特定情形下的能量传输特性.     

DOP生产中脱醇塔操作与控制的实现

邻苯二甲酸二辛酯脱醇过程是一个复杂的传质传热过程,过程变量多,被控变量多,可操纵的变量也多,过程动态和机理复杂。通过物料平衡、热量平衡、相平衡3个方面对脱醇操作的稳定性进行了分析,实现了脱醇塔各工艺参数的控制。     

Analysis of the effects of mass transfer on heat transfer in the process of moisture exchange across a membrane

A theoretical study was conducted to investigate the effects of mass transfer on heat transfer in the process of moisture exchange across a membrane and a mathematical model describing the heat transfer with consideration of the effect of mass transfer was developed.A dimensionless variable,ψi,which presents the degree to which the mass transfer affects the heat transfer,was proposed through theoretical analysis.With calculating of this dimensionless variable,the heat transfer coupled with mass transfer can...     

航天器热控回路的质量全局优化

为了减小载人航天器热控和环境控制生命保障系统的质量 ,在建立的单回路和内外耦合回路流动换热和质量构成的物理数学模型基础上 ,对系统进行了全局轻量化的计算和分析。结果表明 :系统质量全局优化结果不同于其局部优化结果 ;综合考虑各种影响因素 ,对系统进行的质量全局优化可以大幅度地减小单回路和内外耦合回路系统的质量     

Applications of membrane distillation technology in energy transformation process-basis and prospect

Membrane distillation technology is a new type of efficient separation technology that combines traditional distillation technology and membrane separation technology. In the study, applications of membrane distillation technology in thermal engineering and refrigerating engineering with typical energy transformation process were presented. Desorption and regeneration process of saline solution by vacuum membrane distillation was proposed on the basis of the concentration and separation properties of membrane distillation. Membrane distillation technology could be used in lithium bromide absorption refrigeration system, energy storage system, and the regeneration process of liquid desiccant solution in temperature-humidity independent control air-conditioning system. The aim of the applications was to use the low-grade energy such as waste heat, solar energy and geothermal energy adequately and to improve the available temperature difference of heat source. According to latent heat transfer and thermal conduction across the membrane in direct contact membrane distillation process, a novel membrane heat exchanger with both heat transfer and mass transfer processes was proposed. The heat exchanger could be used as the solution heat exchanger of lithium bromide absorption refrigeration system and as the special heat exchanger that recovered heat and pure water simultaneously. Some feasible process flows about the applications of membrane distillation technology to energy transformation process were listed and analyzed. Finally, future research emphases were indicated.     

对广义二阶流体介质中平板的突然起动引起的流动分析

研究了广义二阶流体介质中由于一突然起动的无限平板引起的流动，同时在板上伴有恒定的热量和质量传输．采用Laplace变换法得到了流体速度与板面摩擦力的精确解；给出了速度和板面摩擦力的剖面图并考察了不同的参数对它们的影响．     

大体积混凝土湿热耦合研究

从传热传湿的机理出发,结合水工混凝土特点,建立了以温度和含水量为基本变量,含内热源和内湿源的大坝混凝土湿热耦合传导模型,实现了基于交替变量的伽辽金(Galerkin)法的混凝土湿热传导耦合模型的有限元求解.该方法可用于大坝混凝土湿热耦合传导过程的仿真计算与分析,为混凝土坝采用保温保湿的方式来防止混凝土裂缝提供科学依据.