西安建筑科技大学：《工程热力学 Engineering Thermodynamics》课程双语教学资源（PPT课件讲稿）第三章 热力学第一定律 The first law of thermodynamics

第三章热力学第一定律 Chapter 3. The first law of thermodynamics 3.1系统的宏观和微观储存能 Macroscopic and microscopic energy of system 432热量、功量及质量引起的能量传递--传专递中的能量 Energy transfer by Heat, Work and Mass 43.3热力学第一定律与闭口系统的能量平衡方程 The first law of thermodynamics and Energy balance equation of closed system 43.4开口系统的能量平衡方程 Energy balance equation of open system 3.5稳态稳定流动的能量平衡 Energy balance for steady-flow systems 3.6工程中的几种稳态稳定流动装置 Some steady-flow engineering devices

第三章 热力学第一定律 Chapter 3. The first law of thermodynamics 3.1系统的宏观和微观储存能 Macroscopic and microscopic energy of system 3.2热量、功量及质量引起的能量传递------传递中的能量 Energy transfer by Heat, Work and Mass 3.3热力学第一定律与闭口系统的能量平衡方程 The first law of thermodynamics and Energy balance equation of closed system 3.4开口系统的能量平衡方程 Energy balance equation of open system 3.5稳态稳定流动的能量平衡 Energy balance for steady-flow systems 3.6工程中的几种稳态稳定流动装置 Some steady-flow engineering devices

热力学第一定律的本质 Essence of the first Law of Thermodynamics 本质:能量转换及守恒定律在热过程中的应用 ●18世纪初,工业革命,热效率只有1% 1842年,JR, Mayer闻述热一律,但没有 引起重视 1840-1849年, Joule用多种实验的一致性 证明热一律,于1850年发表并得到公认 1909年,C. Caratheodory最后完善热一律

热力学第一定律的本质 Essence of the First Law of Thermodynamics • 1909年，C. Caratheodory最后完善热一律 本质：能量转换及守恒定律在热过程中的应用 • 18世纪初，工业革命，热效率只有1% • 1842年，J.R. Mayer阐述热一律，但没有 引起重视 • 1840-1849年，Joule用多种实验的一致性 证明热一律，于1850年发表并得到公认

能量守恒定律 能量守恒定律阐明能量既不能被创造,也不能消灭, 它只能从一种形式转换成另一种形式,或从一个系统 转移到另一个系统,而其总量保持恒定 Conservation of energy principle states that energy can be neither created nor destroyed; it can only change from one form to another but the total amount off energy remains constant

能量守恒定律阐明能量既不能被创造，也不能消灭， 它只能从一种形式转换成另一种形式，或从一个系统 转移到另一个系统，而其总量保持恒定。 Conservation of energy principle states that energy can be neither created nor destroyed; it can only change from one form to another but the total amount of energy remains constant. 能量守恒定律

热力学第一定律 热力学第一定律主要说明热能与机械能在转换过 程中的能量守恒 The first law of thermodynamics is viewed as the Conservation of energy principle which governs the energy transfer process from thermal energy to mechanical ones

热力学第一定律主要说明热能与机械能在转换过 程中的能量守恒 The first law of thermodynamics is viewed as the Conservation of energy principle which governs the energy transfer process from thermal energy to mechanical ones. 热力学第一定律

系统能量的变化量等于加给的热量与系统对外所 作功量之差。 The change in energy of a system is equal to the difference between the heat added to the system and the work done by the system △E=Q-W “第一类永动机是不可能制成的” Perpetual-motion machine of the first kind

系统能量的变化量等于加给的热量与系统对外所 作功量之差。 The change in energy of a system is equal to the difference between the heat added to the system and the work done by the system. ⚫ ΔE = Q - W “第一类永动机是不可能制成的” Perpetual –motion machine of the first kind

Perpetual-motion machine of the first kind 汽轮机 电加热器 net 发电机 凝汽器 给水泵 cout

Q Perpetual –motion machine of the first kind 锅 炉 汽轮机 发电机 给水泵 凝 汽 器 Wnet Qout 电 加 热 器

§3.1系统的宏观和微观储存能 Macroscopic and microscopic energy of system energy is a property of every system It is denoted as e for a system, or e for a system with a unit mass. E= internal energy t kinetic energy potential energy 1热力学能U Microscopic energy-----Internal energy U 热力学能指系统所有微观形式的能量之和 Internal energy is defined as the sum of all the microscopic forms of energy of a system

§3.1系统的宏观和微观储存能 Macroscopic and microscopic energy of system Energy is a property of every system. It is denoted as E for a system, or e for a system with a unit mass. E = internal energy + kinetic energy + potential energy 1.热力学能U Microscopic energy-----Internal energy U 热力学能指系统所有微观形式的能量之和. Internal energy is defined as the sum of all the microscopic forms of energy of a system

热力学能的微观组成 microscopic forms of internal energy 「移动 translation √分子动能转动 动 rotation 振动 vibration √分子位能 binding forces 热力学能化学能 nemicalenergy 核能 nuclear energ

热力学能的微观组成 分子动能 分子位能 binding forces 化学能 chemical energy 核能 nuclear energy 热力学能 microscopic forms of internal energy   移动 translation 转动 rotation 振动 vibration

(1)分子的动能和势能 Kinetic and potential energies of the molecules 热力学能=内动能+内位能 T T u is a function of the state of the system u =u(p, T),or u =u(p, v, or u= u(v,T)

（1）分子的动能和势能 Kinetic and potential energies of the molecules u is a function of the state of the system. u = u (p, T), or u = u (p, v), or u = u(v,T). 热力学能＝内动能＋内位能 T T, v

(2)理想气体热力学能的物理解释 n=f(T)理想气体n只与7有关 热力学能=内动能+内位能 T 1, 理想气体无分子间作用力,热力学能只决定于内 动能 ?如何求理想气体的热力学能u

(2)理想气体热力学能的物理解释 热力学能＝内动能＋内位能 T, v 理想气体无分子间作用力，热力学能只决定于内 动能 ? 如何求理想气体的热力学能 u u f T = ( ) T 理想气体u只与T有关