上海交通大学：《材料热力学》教学资源_07电子教案（英文课件）lecture 2 first law II

Contents of Today S.J.T.U. Phase Transformation and Applications Review previous 1th law continuous Adiabatic process:Joule-Thomson expansion Equations of state Adiabatic compression or expansion Enthalpies of formation Enthalpy changes in chemical reactions Adiabatic temperature change in chemical reactions etc. SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II Contents of Today Review previous 1th law continuous Adiabatic process: Joule-Thomson expansion Equations of state Adiabatic compression or expansion Enthalpies of formation Enthalpy changes in chemical reactions Adiabatic temperature change in chemical reactions etc

Index of nomenclature S.J.T.U. Phase Transformation and Applications Adiabatic绝热 Equations of State.状态方程 Non-ideal Gases非理想气体 Enthalpies of Formation生成k焓 Exothermic:放热 Endothermic:吸热 Enthalpy of combusion: 燃烧焓 Enthalpy Change in Chemical Reactions化学反应的焓变 AFT:adiabatic flame temperature?绝热燃烧温度 SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II Index of nomenclature Adiabatic绝热 Equations of State状态方程 Non-ideal Gases非理想气体 Enthalpies of Formation生成焓 Exothermic: 放热 Endothermic: 吸热 Enthalpy of combusion：燃烧焓 Enthalpy Change in Chemical Reactions化学反应的焓变 AFT: adiabatic flame temperature绝热燃烧温度

Review Key points S.J.T.U. Phase Transformation and Applications The first law of thermodynamics is simply the principle of conservation of energy:that is, energy can be neither created or destroyed.To derive the practical benefits of knowing this principle,we must construct an accounting system for energy,sometimes called an energy balance.This system must handle flows of energy,such as heat and work,as well as the various forms of energy that matter possesses. To operate this accounting system,we will need to understand a series of basic notions and definitions. SJTU Thermodynamics of Materials Spring 2006 X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II Review / Key points • The first law of thermodynamics is simply the principle of conservation of energy: that is, energy can be neither created or destroyed. To derive the practical benefits of knowing this principle, we must construct an accounting system for energy, sometimes called an energy balance. This system must handle flows of energy, such as heat and work, as well as the various forms of energy that matter possesses. To operate this accounting system, we will need to understand a series of basic notions and definitions

热力学 S.J.T.U. Phase Transformation and Applications 热力学的研究内容 平衡状态的体系 ·各种形式能量之间转换/能量守恒基础上 转换的方向及其限度 热力学的用处 解释变化过程的原因“为什么”的问题 SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II 热力学 热力学的研究内容 •平衡状态的体系 •各种形式能量之间转换/能量守恒基础上 •转换的方向及其限度 热力学的用处 解释变化过程的原因 “为什么”的问题

Review Key points S.J.T.U. Phase Transformation and Applications System/surroundings.系统环境 Open/close/isolated systems敞开封闭孤立 ·Thermal equilibrium/steady state平衡稳态 ·Heat/work热功 Internal energy内能热力学能 State function状态函数 Intensive/extensive properties强度容量性质 Enthalpy焓 ·Heat capacity热容 SJTU Thermodynamics of Materials Spring 2006 X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II Review / Key points • System / surroundings系统环境 • Open / close / isolated systems敞开封闭孤立 • Thermal equilibrium / steady state平衡稳态 • Heat / work热功 • Internal energy内能热力学能 • State function状态函数 • Intensive / extensive properties强度容量性质 • Enthalpy焓 • Heat capacity热容

Review /Key points S.J.T.U. Phase Transformation and Applications Systems can be classified as open,close and isolated systems 0th law 1st law energy conservation 。Heat/work Internal energy enthalpy heat capacity State function Mechanical energy Equilibrium/steady state SJTU Thermodynamics of Materials Spring 2006 X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II Review / Key points • Systems can be classified as open, close and isolated systems • 0th law • 1st law / energy conservation • Heat / work • Internal energy / enthalpy / heat capacity • State function Mechanical energy Equilibrium / steady state

1.14 Adiabatic flow through a valve: S.J.T.U. Joule-Thomson expansion Phase Transformation and Applications Adiabatic:no heat is added or removed from the system. Adiabatic fluid flow through a valve:insulated or the flow is so fast System:valve at steady state H,oin,-H,i。+dg+δW=dU Steady state w =0 System boundary Adiabatic 89=0 Sm; im,=dim。 H,=H。 Adiabatic process Isenthalpic expansion 绝热过程 SJTU Thermodynamics of Materials Spring 2006 ©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II 1.14 Adiabatic flow through a valve: Joule-Thomson expansion Adiabatic: no heat is added or removed from the system. Adiabatic fluid flow through a valve: insulated or the flow is so fast System boundary δmi δmo System: valve at steady state Hiδmi − Hoδmo +δQ +δW = dU Adiabatic δQ = 0 Steady state δW = 0 δmi = δmo Hi = Ho Adiabatic process Isenthalpic expansion 绝热过程

1.14 Joule-Thomson Coefficient S.J.T.U. Phase Transformation and Applications Joule-Thomson Coefficient defined as the change of temperature with pressure at constant enthalpy. ot System boundary H 温度计 P:.T 777777777 Adiabatic process SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II 1.14 Joule-Thomson Coefficient Joule-Thomson Coefficient : defined as the change of temperature with pressure at constant enthalpy. System boundary δmi δmo H JT P T ⎟⎠⎞ ⎜⎝⎛ ∂∂ η = Adiabatic process

1.15 Equations of State (1) S.J.T.U. Phase Transformation and Applications Equations of state the relationship among the physical variables that describe the condition of a material. For gases the relationship between pressure (P),volume (V). temperature (T)and number of moles(n). PV=ART PV-RT R:the universal gas constant:8.314 J/(mol.K) One mole of gas at 273.15 K and one atmosphere V=22.4L/mol 状态方程 理想气体的状态方程 SJTU Thermodynamics of Materials Spring 2006 ©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II 1.15 Equations of State (1) Equations of state : the relationship among the physical variables that describe the condition of a material. For gases : the relationship between pressure (P), volume (V), temperature (T) and number of moles (n). = nRTPV = RTVP R : the universal gas constant: 8.314 J/(mol•K). = /4.22 molLV One mole of gas at 273.15 K and one atmosphere 状态方程 理想气体的状态方程

P-V-T surface of ideal gas S.J.T.U. Phase Transformation and Applications ·No phase change ·Single value of specific volume for every pressure ·No discontinuities ·A smooth surface Volume- Temperature 等容线 等温线 SJTU Thermodynamics of Materials Spring 2006 ©X.J.Jin Lecture 2 First Law ll

Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II P-V-T surface of ideal gas • No phase change • Single value of specific volume for every pressure • No discontinuities • A smooth surface 等容线 等温线