卡诺循环的H-T图——基于统计热力学探析焓与定压热容  

The H-TDiagram of Carnot Cycle——Analysis of Enthalpy and Constant Pressure Heat Capacity Based on Statistical Thermodynamics

作　　者：张琪 高文亮[1] 李军[1] Zhang Qi;Gao Wenliang;Li Jun(College of Chemistry and Chemical Engineering,Chongqing University,Chongqing 401331,China)

机构地区：[1]重庆大学化学化工学院,重庆401331

出　　处：《广东化工》2023年第1期213-217,共5页Guangdong Chemical Industry

基　　金：重庆大学校级教改项目(20210629、2021Y42);重庆大学化学工程与技术学科水平提升计划(0220005403001)。

摘　　要：探讨了卡诺循环过程的H-T图。首先根据经典热力学公式,推导出理想气体在等温可逆过程中焓不变,在绝热可逆过程中的H-T图的斜率实为定压热容。再通过统计热力学推导不同结构类型理想气体的定压热容的具体表达式,作出卡诺循环中焓与温度的关系的简单示意图。并利用量化计算绘制几种典型理想气体(He、CO、CO_(2)、CH_(3)OH)的H-T图,发现H-T图整体呈线性,而低温段偏离直线程度相对较大,这主要是由于振动的影响。本文将理论推导与量化计算相结合,有利于学生理解卡诺循环过程中的物理图像,也有利于学生强化热力学与统计热力学间的知识连贯。The H-T diagram of Carnot cycle is discussed.Firstly,according to the classical thermodynamic formula,it is deduced that the enthalpy of ideal gas is constant in isothermal reversible process,and the slope of H-T graph in adiabatic reversible process is the heat capacity at constant pressure.Then the specific expressions of constant pressure heat capacities of ideal gases with different structure types are derived by statistical thermodynamics and a simple schematic diagram of the relationship between enthalpy and temperature in Carnot cycle is obtained.The H-T plots of several typical ideal gases(He,CO,CO_(2),CH_(3)OH)are drawn by quantitative calculation.It is found that the H-T plots are linear overall,while the deviation degree of the low-temperature section is relatively large,which is mainly due to the influence of vibration.In this paper,the combination of theoretical derivation and quantitative calculation is helpful for students to understand the physical images in the Carnot cycle process and to strengthen the knowledge coherence between thermodynamics and statistical thermodynamics.

关 键 词：卡诺循环 经典热力学 统计热力学 量化计算 

分 类 号：TQ[化学工程]