热力学中等压热容和等容热容定义方法的修正  

Investigation of the Definition Method of Isobaric and Isochoric Heat Capacities in Thermodynamics

作　　者：江振西[1] Jiang Zhenxi(School of Chemical 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》2022年第8期46-52,70,共8页Journal of Huanghe S&T College

摘　　要：等压热容和等容热容的定义存在两个缺陷。第一个是认为热容和过程的路径有关。经等压路径升温1 K需要的热量比经等容路径升温1 K需要的热量多。第二是没有考虑传入体系的功对热容的影响。根据能量守恒定律,等容条件下温度升高1 K需要的能量与等压条件下温度升高1 K需要的能量相同。体系的焓增量等于传热过程中传递给体系的热量,与传热过程的路径没有关系。提出了压体能、体积能和压强能3个新术语,给出了相应的物理意义和计算公式,以及与焓和内能之间的关系。使用压体能、体积能和压强能,解释了在过程中理想气体各种能量函数的变化。根据焦耳实验,功可以转换为热从而引起体系的温度改变。所以在热-功转换过程中不仅要考虑传给体系的热,还要考虑传给体系的功。体系的焓增量等于在过程中传给体系的热和功以及连带的其他形式的能量。提出了热容的定义方法,修正了等压热容和等容热容的定义。分别使用焓增量和内能增量定义等压热容和等容热容。把热力学第一定律第零、第一和第二方程式分别代入焓热容的定义式,建立了热容与热和功之间的关系。提出两个新术语:焓热容和内能热容。使用新术语以避免“等压热容”和“等容热容”字面意义引起的概念上的混淆。There are two flaws in the definitions of isobaric heat capacity and isochoric heat capacity.The first is that the heat capacity is considered to be related to the path of the process.Therefore,the heat quantity required for one degree of temperature rise through the isobaric path is more than that through the isochoric path.The second is that the effect of work transferred into the system on heat capacity is not considered.According to the law of conservation of energy,the energy required for a temperature rise of one degree under isochoric condition is the same as that required for a temperature rise of one degree under isobaric condition.The enthalpy increment of the system is equal to the heat transferred to the system during heat transfer,independent of the path of the process.Three new terms,namely pressure-volume energy,volume energy and pressure energy,are proposed,their physical signifcance and calculation formulas,as well as their relations with enthalpy and internal energy are given.Using pressure-volume energy,volume energy and pressure energy,the changes of various energy functions of ideal gas in the process are explained.According to the Joule experiment,work can be converted into heat to cause the temperature change of the system.Therefore,in the process of heat-work conversion,not only the heat transferred to the system,but also the work transferred to the system should be considered.The enthalpy increment of a system is equal to the heat and work transferred to the system and other forms of energy associated with it.The definition method of heat capacity is proposed,and the definitions of isobaric heat capacity and isochoric heat capacity are corrected.The isobaric and isochoric heat capacities are defined using enthalpy increments and internal energy increments,respectively.Substituting the zeroth、first and second equations of the first law of thermodynamics into the definition of enthalpy heat capacity respectively establishes the relationships between heat capacities with heat and work.Two

关 键 词：热容 焓 内能 热 功 热力学 

分 类 号：O414.1[理学—理论物理]