熵的定义和过程熵变的计算  

Definitions of Entropy and Calculations of Process Entropy Changes

作　　者：江振西[1] Jiang Zhenxi(School of Chem.Engineering,Zhengzhou University,Zhengzhou City,Henan Province 450001)

机构地区：[1]郑州大学化工学院,河南郑州450001

出　　处：《黄河科技学院学报》2023年第5期48-56,共9页Journal of Huanghe S&T College

摘　　要：在热-焓转换中,熵变与过程路径有关,温度是吸收热量的函数。基于这两个事实提出了修正的熵的定义式。在可逆热-功转换中,通过边界传递的机械功只改变体系的焓但不改变体系的熵。所以基于热-焓转换过程推导出来的定义式,同样适用于热-功转换过程。还提出了体系的熵、过程的熵变和不可逆过程的熵产的定义。根据熵的定义式推导出一系列计算简单过程熵变的公式。把过程按可逆性分为本质不可逆过程和具有可逆性的过程。具有可逆性的过程进一步分为可逆过程和不可逆过程。按照过程是否有中间状态或中间反应把过程分为简单过程和连串过程。针对不同类型的过程给出了计算过程熵变的方法,探讨了熵变与过程路径,过程途径和可逆系数的关系。提出把不可逆热-功转换过程的熵变分为两部分分别计算的方法。把热量造成的热量熵变和热产引起的熵产分别计算然后相加。提出了计算绝热过程总熵变的方法。探讨了过程路径和过程途径的区别。对于绝热过程,熵变与过程有关,因为可逆系数影响过程的终态。对于连串过程,熵变与过程无关,因为过程的始态和终态被完全给定。修正了第二定律的熵增原理的陈述。修正的陈述是:只要过程发生,无论过程自发与否,总熵变都大于0。总熵变不能作为判据预测自发过程的方向。证明了不可逆绝热过程的熵变和可逆绝热过程的熵变不同。In the heat-enthalpy conversion,the entropy change is related to the process path and the temperature is a function of the heat absorbed.Based on these two facts,a modified defining equation for entropy is proposed.In reversible heat-work conversion,the mechanical work transferred across the boundary only changes the enthalpy but not the entropy of the system.Therefore,the equation derived based on the heat-enthalpy conversion process is also applicable to the heat-work conversion process.The definitions of the entropy of the system,the entropy change of the process and the entropy generation of the irreversible process are also proposed.According to the definitions of entropy,a series of formulas for calculating the entropy change of simple processes are derived.According to reversibility,the processes are divided into essentially irreversible processes and processes with reversibility.Processes with reversibility are further divided into reversible processes and irreversible processes.According to whether the process has intermediate state or intermediate reaction,the process can be divided into simple process and chain-process.The method of calculating process entropy change is presented for different types of process,and the relationships between entropy change with process path,process route and reversibility coefficient are discussed.A method of dividing the entropy change in the irreversible heat-work conversion process into two parts is proposed.The heat entropy change caused by heat amount and the entropy generation caused by heat generation are calculated separately and then added.A method for calculating the total entropy change in an adiabatic process is proposed.The differences between a process path and a process route is discussed.For an adiabatic process,the entropy change is process dependent because the reversibility coefficient affects the final state of the process.For a chain-process,the entropy change has nothing to do with the process because the initial state and final state of the process

关 键 词：热-焓转换 连串过程 熵变 熵产 卡诺循环 熵增原理 

分 类 号：O414.1[理学—理论物理]