Heat Engine(热机): the devices converting heat to workcanbe characterized as- Receive heat (Qμ) from a high temperature source (solar energy,furnace)- Convert part of these heat to work (W) (usually rotating shaft)-Reject theremaining waste heat (Q,)to a low-temperaturesink(theatmosphere,rivers,etc.)-Operateona cycle.- Usually involves a fluid, called working fluid(工质),E.GInternalcombustionengine（内燃机：汽油机和柴油机等）ExternalcombustionEngine（蒸汽发电厂系统等）
• Heat Engine(热机)：the devices converting heat to work, can be characterized as – Receive heat (QH) from a high temperature source (solar energy, furnace) – Convert part of these heat to work (W) (usually rotating shaft) – Reject the remaining waste heat (QL ) to a low-temperature sink (the atmosphere, rivers, etc.) – Operate on a cycle. – Usually involves a fluid, called working fluid(工质). E.G Internal combustion engine（内燃机：汽油机和柴油机等） External combustion Engine（蒸汽发电厂系统等） 6
ThermalEfficiency(热机效率）：等于做功W除以吸收热量QConservation of EnergyPrinciple(能量守恒定律）吸收热量Q.=做功W+放出热量Q热机最高效率?？：20??=1Nth, rev =W/Qμ=1-100Q
• Thermal Efficiency(热机效率): 等于做功W除以吸收热量QH。 • Conservation of Energy Principle(能量守恒定律) 吸收热量QH =做功W+放出热量QL • 热机最高效率??： 7 QL QH TL TH η = 1 - th, rev =W/QH=1- 20 100 ??= 1 - 可逆
AuthorsProfessorYunusA.CengelUniversity ofNevada,RenoDr.Michael A. BolesNorth Carolina State University·Turkey（土耳其）turkey（火鸡）烤火鸡，必须具备一定的热力学常识
Authors • Professor Yunus A.Cengel—University of Nevada, Reno • Dr. Michael A. Boles— North Carolina State University 8 •Turkey（土耳其） turkey（火鸡） 烤火鸡，必须具备一定的热力学常识
Thermodynamics is not an easy subject. Thermodynamics is a funny subject.- The first time you go through it: you don't understandit at all; The second time you go through it, you think youunderstand it, except for one or two points;- The third time you go through it, you know you don'tunderstand it, but by that time you are so used to thesubject, it doesn't bother you anymore.---ArnoldSommerfeld
Thermodynamics is not an easy subject • Thermodynamics is a funny subject. – The first time you go through it: you don’t understand it at all; – The second time you go through it, you think you understand it, except for one or two points; – The third time you go through it, you know you don’t understand it, but by that time you are so used to the subject, it doesn’t bother you anymore. – -Arnold Sommerfeld
Thermodynamics ? ?FromGreekwords:Therme→heat →热thermo(-)dynamics热力学Dynamispower→动力热情激情热力学努力科学教学学习
Thermodynamics ？？ 热 力 学 From Greek words: Therme→heat →热 thermo(-)dynamics Dynamis→power →动力 热力学 热情 激情 努力 科学 教学 学习