Chapter 18 Second law of thermodynamics §18-3 Reversible and irreversible process(可逆 过程与不可逆过程):p433 Reversible process可逆过程) 无摩擦的准静态过程. Reversible process is carried out infinitely slowly, so that the process can be considered a series of equilibrium states, and the whole process could be done in reverse with no change in magnitude of the work done or heat exchanged
Chapter 18 Second Law of Thermodynamics §18-3 Reversible and irreversible process (可逆 过程与不可逆过程): p433 Reversible process(可逆过程) ----无摩擦的准静态过程. Reversible process is carried out infinitely slowly, so that the process can be considered a series of equilibrium states, and the whole process could be done in reverse with no change in magnitude of the work done or heat exchanged
Chapter 18 Second law of thermodynamics ◆可逆过程:在系统状态变化过程中,如果 逆过程能重复正过程的每一状态,而不引起其 他变化,这样的过程叫做可逆过程 准静态等温过程P4 执 源 (P2,V2,7) T 准静态无摩擦过程为可逆过程
Chapter 18 Second Law of Thermodynamics 准静态无摩擦过程为可逆过程 可逆过程 : 在系统状态变化过程中,如果 逆过程能重复正过程的每一状态, 而不引起其 他变化, 这样的过程叫做可逆过程
Chapter 18 Second law of thermodynamics Irreversible process is one that can not be reversed by means of small changes in the environment 在不引起其他变化的条件下,不能使逆过程重 复正过程的每一个状态的过程称为不可逆过程 (自然过程都是不可逆的) All real process are irreversible 非准静态过程为∵ 不可逆过程
Chapter 18 Second Law of Thermodynamics Irreversible process is one that can not be reversed by means of small changes in the environment. 在不引起其他变化的条件下,不能使逆过程重 复正过程的每一个状态的过程称为不可逆过程. (自然过程都是不可逆的) All real process are irreversible. 非准静态过程为 不可逆过程
Chapter 18 Second law of thermodynamics 818-2 Heat Engines P430 The working substances absorb heat from high temperature resource, High ternperature one part of energy becomes work. and Steam Water the other part release Intake valve Boiler (open dluring to the low expansIon) temperature resource After a cycle, the Exhaust valve Piston (closed during ekpilnsltlll working substances Pum resume their original ( wate Condenser state。 Low tcmpcraturc
Chapter 18 Second Law of Thermodynamics §18-2 Heat Engines P430 The working substances absorb heat from high temperature resource; one part of energy becomes work, and the other part release to the low temperature resource. After a cycle, the working substances resume their original state
Chapter 18 Second law of thermodynamics 1热机发展简介 历史上热力学理论最初是在研究热机工作过程的基 础上发展起来的。热机是利用热来做功的机器。1698 年萨维利和1705年纽可门先后发明了蒸汽机,当时蒸 汽机的效率极低.1765年瓦特进行了重大改进,大大 提高了效率.人们一直在为提高热机的效率而努力,从 理论上研究热机效率问题,一方面指明了提高效率的 方向,另一方面也推动了热学理论的发展 各种热机的效率 液体燃料火箭=48%柴油机7=37 汽油机 7=25%蒸汽机m=8%
Chapter 18 Second Law of Thermodynamics 历史上热力学理论最初是在研究热机工作过程的基 础上发展起来的。热机是利用热来做功的机器。1698 年萨维利和1705年纽可门先后发明了蒸汽机，当时蒸 汽机的效率极低 . 1765年瓦特进行了重大改进 ，大大 提高了效率 .人们一直在为提高热机的效率而努力，从 理论上研究热机效率问题， 一方面指明了提高效率的 方向， 另一方面也推动了热学理论的发展 . 各种热机的效率 液体燃料火箭 柴油机 汽油机 蒸汽机 = 48% = 8% = 37% = 25% 1 热机发展简介