摘要
提出了过程可逆性这一概念。依据过程是否具有可逆性,过程被分为两类:具有可逆性的过程和没有可逆性的过程。没有可逆性的过程为本质不可逆过程。状态函数的变化与过程是否有关取决于过程的类型。按照可逆性的物理意义,热-焓转换是本质不可逆过程。本质不可逆过程的状态函数变化与过程无关。这样,对于传热过程是否可逆,热力学和传热学有了一致的观点。热-功转换是具有可逆性的过程,分为可逆过程,不可逆过程和完全不可逆过程。所以热-功转换过程的状态函数变化与过程的可逆程度有关。基于对不可逆过程功耗散的分析,提出了热产这一概念。给出了热产与损失功之间的关系以及热产对过程的影响。阐述了“可逆”的本质是热-功转换效率。定义了可逆系数用于定量描述过程的可逆程度。提出了两个热力学第一定律通用方程式,分别适用于活塞型热机和涡轮型热机的热-功转换过程。“通用”是指方程式既适用于可逆过程也适用于不可逆过程,既适用于产功过程也适用于压缩过程。在两个通用方程式中,使用可逆系数和理想功代替实际功。因为理想功是始态和终态的状态量,可逆系数是热机的性能参数,所以通用方程式能够定量表述可逆程度对过程的影响。当表征始态、终态和多变指数的5个变量中的4个变量已知时,通用方程式能够用于计算在不同可逆程度的条件下过程的热量、热产、实际功、终态和状态函数变化。讨论了热-功转换过程中焓变、热量和机械功三者之间的制约关系,给出了表述热和功之间关系的公式。
The concept of process reversibility is proposed.According to their reversibility,processes are divided into two categories:processes with reversibility and processes without reversibility.A process without reversibility is inherently irreversible.Whether the change in the state function is process-dependent or not depends on the type of process.According to the physical significance of reversibility,the heat-enthalpy conversion is an inherently irreversible process.The change of state function of the inherently irreversible process is independent of the process.In this way,thermodynamics and heat transfer science have a consistent view on whether the heat transfer process is reversible.The heat-work conversion is a process with reversibility,which can be divided into reversible,irreversible and completely irreversible process.So the change of the state function of the heat-work conversion is related to the degree of reversibility of the process.Based on the analysis of work dissipation in irreversible processes,the concept of heat generation is presented.The relationship between heat generation and lost work and the effect of heat generation on the process are given.The essence of"reversible"is explained as the efficiency of heat-work conversion.A reversibility coefficient is defined to quantify the degree of reversibility of the process.Two generalized equations of the first law of thermodynamics are presented for the heat-to-work conversion processes of piston-type heat engines and turbine-type heat engines,respectively.The term"general"means that the equations are applicable to both reversible and irreversible processes,and to both work-producing and compression processes.In the two general equations,reversibility coefficients and ideal work are used instead of actual work.Since the ideal work is the state quantity of the initial and final states and the reversibility coefficient is the performance parameter of the heat engine,the general equations are able to express quantitatively the effect of the degree o
作者
江振西
Jiang Zhenxi(School of Chemical Engineering,Zhengzhou University,Zhengzhou City,Henan Province,450001)
出处
《黄河科技学院学报》
2022年第11期6-14,共9页
Journal of Huanghe S&T College
关键词
可逆性
本质不可逆
热-功转换
损失功
热产
可逆系数
reversibility
inherent irreversible
heat-work conversion
lost work
heat generation
reversibility coefficient
