能量系统热经济寿命的决策模型与方法

提出了热经济寿命的新概念 ,基于此研究能量系统在何时更新其热经济性最佳的问题 ,并建立了单元系统的热经济寿命确定模型 ,尤其提出了复合系统确定热经济寿命的方法和决策模型 ,从而形成了能量系统热经济寿命的决策理论 .一个能量系统更新的实例 ,表明在它的热经济寿命时更新系统 ,可使系统创造更大的经济收益 .本文的工作为能量系统的设备更新提供了一种普遍适用的理论和方法 .     

动静态研究体系中CaCO_3沉积规律的理论分析及实验研究

本文针对冷却水系统污垢研究的两种测试体系 ,对 Ca CO3 沉积规律进行了理论分析与相应的实验研究 ,探讨了两种体系存在差别的根本原因。     

电渗强化多孔介质孔内流动及传质

建立了电场中多孔介质孔内流动模型 ,通过计算比较了Poiseuille流和电渗流对孔内流动的贡献 ;提出“有效扩散系数”来定量描述电渗对多孔介质孔内传质过程的强化作用 ;建立了电色谱理论塔板高度模型 ,比较了Poiseuille流和电渗流对色谱理论塔板高度的影响 .计算结果表明采用Poiseuille流强化孔内传质的方法仅适用于孔径大于 5 0 0nm的大孔颗粒 ;而电渗流则可提高不同孔径的介质孔内的传质 ,降低色谱分离理论塔板高度 ;依据Yoshida模型计算了不同的有效扩散系数下的吸附穿透曲线以揭示电场强度对电色谱吸附行为的影响 ,理论预期与实验结果一致     

RESIDENCE TIME DISTRIBUTIONS AND MICROMIXING

This review is concerned primarily with the Lagrangian approach to mixing. First, the concepts of residence time and residence time distribution are introduced and defined. After a general treatment of this topic in the second chapter, the concept of micromixing is discussed in the third chapter with due emphasis on the application to chemical reactors. The final chapters extend the theory and applications to unsteady stale systems and to systems which are non-isothermal or non-homogeneous.     

RESIDENCE TIME DISTRIBUTIONS AND MICROMIXING∗

This review is concerned primarily with the Lagrangian approach to mixing. First, the concepts of residence time and residence time distribution are introduced and defined. After a general treatment of this topic in the second chapter, the concept of micromixing is discussed in the third chapter with due emphasis on the application to chemical reactors. The final chapters extend the theory and applications to unsteady stale systems and to systems which are non-isothermal or non-homogeneous.     

CORRELATION AND PREDICTION OF LIQUID DIFFUSION COEFFICIENTS IN BINARY SYSTEMS

A theoretical model to correlate and predict the liquid diffusion coefficients in binary sys-tems has been developed.Based on this mode1 the diffusion coefficient of 73 binary systems have beencorrelated,the overall average deviation of the correlation for diffusion coefficients is 0.009.Forbinary systems the diffusion coefficients have been predicted from vapor liquid phase equilibrium(VLE)and vice versa.     

多孔介质对流干燥机理及其模型

在对现有的多孔介质对流干燥传热、传质模型归类分析的基础上,从介质内部热湿迁移机制出发,建立了能较完善、较准确地描述多孔介质在恒速段及降速段热质传递规律的“三耦合-六场量”混合理论模型.同时针对干燥问题数值模拟中的移动边界问题,提出了一种迭代修正的思想,并发展了相应的数值计算方法.对砖的干燥模拟计算结果表明,本文的模型较其他模型具有更好的精确性.     

Membrane assisted crystallization using reverse osmosis: Influence of solubility characteristics on experimental application and energy saving potential

Membrane assisted crystallization is a promising concept to improve control over the generation of supersaturation and to reduce energy consumption of conventional solvent evaporation. In this work both the practical and theoretical feasibility of membrane assisted crystallization using reverse osmosis (MaC-RO) is investigated with an emphasis on the influence of solubility characteristics. An experimental setup is presented tailored towards reduction of the two main sources of risk for the concept, which are concentration polarization and scaling on the membrane surface. The performance is investigated for two model systems with different solubility behaviour, which are ammonium sulphate and adipic acid both crystallized from water. The latter system shows a much better operational performance. In addition, a model of a continuously operated MaC-RO process is developed and optimized, and the energy consumption as function of solubility characteristics is systematically compared to that of conventional evaporative crystallization. Both the experimental and theoretical study show that MaC-RO has potential for many applications and is economically and practically most suitable for components with a moderate solubility, high molecular weight, and a strong dependency of solubility on temperature.     

概念与其表达式的热力学一致性研究

指出火用本性上不是严格意义上的状态函数,给出了在无限大环境参考态下多相系统火用函数一般表达式。该表达式可以被推广应用于无限大的热源和物质源,体现了火用定义和火用函数表达式的唯一性和热力学一致性。将火用和“火用变化”严格区分,避免了关于火用概念热力学本性的误解和争论,结束了现行教材中火用的模型、类别和表达式的多样化局面。最后为任意状态下的均相系统火用函数的数值计算提供了一般思路和基本公式。     

概念与其表达式的热力学一致性研究

指出(火用)本性上不是严格意义上的状态函数,给出了在无限大环境参考态下多相系统(火用)函数一般表达式.该表达式可以被推广应用于无限大的热源和物质源,体现了(火用)定义和(火用)函数表达式的唯一性和热力学一致性.将(火用)和"(火用)变化"严格区分,避免了关于(火用)概念热力学本性的误解和争论,结束了现行教材中(火用)的模型、类别和表达式的多样化局面.最后为任意状态下的均相系统(火用)函数的数值计算提供了一般思路和基本公式.     

Dynamics and control of integrated microchemical systems with application to micro-scale fuel processing

Microchemical systems are a new generation of miniature chemical systems that carry out chemical reactions and separations in precisely fabricated three dimensional microreactor configurations in the size range of a few microns to a few hundred microns. Typical microchemical systems combine fluid handling and reaction capabilities with electronic sensing and actuation, are fabricated using integrated circuit (IC) manufacturing techniques and use silicon and related IC industry materials, polymers, ceramics, glass or quartz as their material of construction. The use of such systems for in situ and on-demand chemical production is gaining increasing importance as the field of microreaction engineering transitions from a theoretical concept to a technology with significant industrial applications. In this paper, we present a review of our work on MEMS-based microfabrication, modeling and control of micro-reformers for hydrogen delivery systems in micro-fuel cells and put it in the context of a number of reported studies in the literature on this topic. The paper concludes by suggesting possible areas of future research.     

CLATHRATE HYDRATE FORMATION ENHANCES NEAR-CRITICAL AND SUPERCRITICAL SOLVENT EXTRACTION EQUILIBRIA

Pre-concentration of dilute aqueous solutions by hydrate formation can improve the effective distribution coefficient and selectivity of solvent extraction. Many solvents can serve simultaneously to promote solution concentration by hydrate formation and also to extract non-polar solutes from the resulting concentrated solution. This concept is illustrated for systems with supercritical ethylene and with near-critical liquid carbon dioxide, and its application to conventional solvents is discussed.     

CORRELATION OF DIFFUSION COEFFICIENTS FOR LIQUIDS AND DENSE FLUIDS WITH TEMPERATURE AND PRESSURE

On the basis of the free volume theory and activation energy concept,a fundamental equation whichtakes into account the effects of temperature and pressure has been developed.By introducing differentexpressions for the free volume and activation energy,several equations for fluid diffusion coefficients were derivedaccordingly.With the van der Waals free volume and intermal energy formula,a three-parameter model for fluiddiffusion coeffficients at moderate pressure was obtained.The grand average absolute deviation percent of 345data points (44 systems)for self-and infinite dilute inter-diffusivities is 2.32,against the results of the model ofCohen and Turnbull,4.13.In particular,by means of the modified Carnahan-Starling free volume equation,afour-parameter model with average abosolute deviation percent 2.64(30 systems,644 data points)for theestimation of dense fluid inter-and self-diffusivities at high pressures and in supercritical conditions was derived.The derived model is superior to the method of L     

关于多孔电极理论数模及非线性分析

从一般工程理论的基本衡算概念出发,用累积项、散度和化学源（反应项）的概念解释了反应工程理论数模的普遍微分形式,并指出,反应系统中与化学动力学相关的物理量分布,即质量场和能量场,决定了表观的反应结果。作者认为,具有电化学源及传荷过程是电化学反应系统的特点,据此,经合理简化可导出多孔电极稳态操作的普遍化理论数模,其形式为量纲1的非线性二阶微分方程组的边值问题,以描述多孔电极内浓差极化、欧姆极化和活化极化耦联的非线性理论关系;所归纳出的4个量纲1参数s、μ、α和γ,可给出系统动力学和传递过程相似的依据。扼要介绍了非线性数模逼近解析的Adomian分解法,以及自编的符号运算自动执行程序PAMC（parameterized ADM mathematica code）,并例举了柱状和环状多孔电极理论极化曲线的计算结果。总之,非线性和复杂性研究将成为反应工程理论深入探索的方向之一。     

MASS AND MOMENTUM TRANSFER WITH NON-NEWTONIAN FLUIDS IN FLUIDIZED BEDS

A new model for non-Newtonian fluid flows through fluidized beds is developed by extending the Richardson-Zaki concept. In the proposed model, the existing correlations for an isolated single sphere are simply extended to those for a fluidized bed by incorporating a voidage function. The model is found to be in a good agreement with other correlations for flows of a non-Newtonian fluid through multi-particle systems. The model is also applied to interpret mass transfer in fluidized beds.     

MASS AND MOMENTUM TRANSFER WITH NON-NEWTONIAN FLUIDS IN FLUIDIZED BEDS

A new model for non-Newtonian fluid flows through fluidized beds is developed by extending the Richardson-Zaki concept. In the proposed model, the existing correlations for an isolated single sphere are simply extended to those for a fluidized bed by incorporating a voidage function. The model is found to be in a good agreement with other correlations for flows of a non-Newtonian fluid through multi-particle systems. The model is also applied to interpret mass transfer in fluidized beds.     

Microgels for the Intensification of Liquid-Liquid Extraction Processes – Feasibility and Advantages

Microgels are cross-linked polymers with a high application potential in liquid-liquid systems due to their surface activity and switchable stabilization properties. A process concept utilizing microgels in extraction processes is presented. The microgels are located at the drop surface and prevent coalescence, enabling monodisperse operation. At the column top, the stabilization is switched off by temperature shift. The switchable stabilization and the absence of additional mass transfer resistance are crucial requirements for the concept and tested experimentally. The results provide the basis for the model-based evaluation of the process performance, revealing a broader operating window, capacity increase at equal height equivalent of theoretical stage (HETS) for high loads, and reduced HETS for small loads.     

CONJUGATE HEAT AND MASS TRANSFER IN CONVECTIVE DRYING OF MULTIPARTICLE SYSTEMS. PART I: THEORETICAL CONSIDERATIONS

This is the first of two papers concerning conjugate transport in convective drying of multiparticle systems. In this study, a methodology for the solution of conjugate transport problems is proposed. The theoretical aspects and relevant assumptions are briefly discussed and the results for convective heat and mass transfer in assemblages of spheres are presented. It is shown that both heat and mass transfer rates for an assemblage of two spheres in tandem arragement are significantly different from those of a single sphere case, and that care should be taken when modeling multiparticle systems by means of single-particle analysis.