化工热力学课件--01章

Advanced Chemical Engineering Thermodynamics江成发教授、博士高等化工热力学四川大学化工学院E-mail:jiangcf6208163.com热力 学(thermodynamics)作为一门科学诞生于19世纪，最初用于研究和描述蒸汽机(steam engine)的操作以及蒸汽机工作的极限，后来上升到热机(heat engine)的研究和应用。“热力学”名称的本身就意味着“来自热的能量”，因为thermo代表热，dynamics代表动力。热力学在研究热机工作的基本原理过程中，总结、归纳出了著名的热力学第一定律和热力学第二定律。热力学第一定律和热力学第二定律没有任何数学意义上的证明，它是自然界基本规律的总结，迄今为止，没有任何人对这二个定律提出异议（除了一些科学狂人），自然界发生的过程或出现的现象也都遵循这二个定律。热力学第一和第二定律奠定了热力学科学的理论基础。从热力学第一和第二定律出发，通过一系列数学推导，建立了一整套的热力学公式，形成了完整的热力学理论体系。这就是我们今天所认识的热力学。伴随热力学科学的形成和发展，产生了一批著名的数学家和化学家，其中，贡献最大的是美国数学家Josiah Willard Gibbs。下面是Josiah Willard Gibbs的介绍。Josiah Willard Gibbs (1839 - 1903)Josiah Willard Gibbs (1839 - 1903) has been reckoned as one of the greatest American scientists of the 19th century. He provided a sound thermodynamic foundation to much of Physical Chemistry. “Gibbs Phase Rule” is well known to all in the field today. Yale educated, he was awarded the first Doctor of Engineering in the U.S., and was appointed Professor of Mathematical Physics at Yale in 1871. In 1873 he published his first major works, “Graphical Methods in the Thermodynamics of Fluids“. In 1876 came his most famous paper: “On the Equilibrium of Heterogeneous Substances.“ John M. PrausnitzThe research purpose of Prausnitz is to obtain, interpret and correlate thermodynamic properties of a variety of mixtures as required for process and product design in the chemical and related industries, including biotechnology. Toward that end, we obtain experimental data, perform Monte-Carlo molecular simulations and develop molecular- thermodynamic models based on the statistical mechanics of fluids and solids. Attention is given to crude oils, natural gas, polymers and protein solutions. While these research studies contribute to our fundamental understanding of condensed matter, their primary application is for economic, industrial- scale chemical engineering design.目前Prof Prausnitz 的研究领域和研究方法Kenneth S. Pitzer (1914-1997)另一个近代热力学著名学者Kenneth S. Pitzer was born in Pomona, California, in 1914. He received his B.S. in 1935 from Caltech and his Ph.D. in chemistry from UC Berkeley in 1937. He was immediately appointed to the faculty of the Department of Chemistry at Berkeley, where he spent most of his distinguished career. Professor Pitzer took leave to serve in Washington, D.C., during World War II and again from 1949 to 1951, when he was Director of Research for the Atomic Energy Commission. Upon returning to Berkeley, he was appointed Dean of the College of Chemistry, a position that he held until 1960. He subsequently became President first of Rice University (1961- 1968) and then of Stanford University (1969-1971). In 1971, he returned to Berkeley, becoming Professor Emeritus in 1984.Professor Pitzer was the founder of modern theoretical chemistry at Berkeley. He not only used quantum and statistical mechanics to explain the thermodynamic and conformational properties of molecules, but he also pioneered quantum scattering theory for describing chemical reactions at the most fundamental level. He also made contributions to relativistic effects in chemical bonding and the theory of fluids and electrolyte solutions.化工热力学面临的问题化工热力学面临的最大问题是：理论研究多,实际应用少。美国 University of California, Berkeley 的Prausnitz 教授是近代化工热力学领域最著名的一位学者，下面引用他在论文 “Thermodynamics and Other Chemical Engineering Sciences: Old Models for New Chemical Products and Processes”（Fluid Phase Equilibria 158-160,1999）中的一段话 ，说明目前化工热力学存在的问题。“Chemical engineering thermodynamics has many talented researchers working on a wide variety of projects. But all too often when I read erudite articles in the literature, the author seems to be saying: “I have an answer. But I dont know the question.”“Do the best work in Thermodynamics that you possibly can and enjoy it thoroughly. But dont lose sight of the goal. Thermodynamics comes second. First comes Chemical Engineering.” 热力学问题的分类1. For a given process with prescribed (or idealized ) internal constraints and boundary conditions, how do the properties of the system vary? 2. To cause given changes in system properties, what external interactions must be imposed?(This is the inverse of Type 1.)3. Of the many alternative processes to effect a given change in a system, what are the efficiencies of each with respect to the resources at our disposal?How to solve these problems?Type 1 和 Type 2 二类问题的解决需要应用热力学第一定律(the First Law)，如在物理化学课程中学习的封闭体系第一定律在化工热力学课程中学习的稳流体系第一定律热力学第一定律可以广义地写成如下形式：Internal changes = interactions occurring at boundaries第一定律中体系的能量变化可以同体系其它的一些性质 ，如 T、P 、V 等相关联，因此，可以通过改变体系的T、P 、V 等性质，实现体系的状态变化。Type 3 问题的解决，需要热力学第二定律（the Second Law）。这时，引入一个被称为可逆过程（reversible process）的理想化过程，作为比较实际过程效率的标准。任何一个热力学问题，原则上都可以用下面的三步法解决。1. Problem definition and modelingThe real-world situation must be modeled by specifying the internal constrains and boundary conditions. Idealizations must frequently be introduced to make the problem tractable. Is a boundary permeable, semipermeable, or impermeable