蒸汽机的应用,已经有大约两百年的历史,可是,直到现在,蒸汽机在各种热机当中,在很多生产部门和变通运输工具上,依然保持着相当的地位。这是因为蒸汽机和其它热机比起来具有很多的优点,主要是:构造简单,价格低廉、可以使用不同的燃料,容易管理,不大会发生故障。所有这一切,表明蒸汽机也很适合农村的工作条件,成为我国农业大发展中一种很重要的动力机器。不过,蒸汽机也有一些缺点,它的工作效率较低,机身也比较笨重。工作效率是衡量机器经济性的准绳,在蒸汽机内部蒸汽的工作能力有种种损失,因而使燃料的利用不够经济。在中学物理课本中,有 The application of steam engines has been around for about two hundred years. However, up to now, the steam engines have maintained a considerable position in many production sectors and alternative transportation vehicles among various heat engines. This is because the steam engine has many advantages compared with other heat engines, mainly because of its simple structure, low price, use of different fuels, easy management and failure of the general assembly. All this shows that the steam engine is also suitable for rural working conditions and has become a very important power plant in the great development of agriculture in our country. However, the steam engine also has some disadvantages, its work efficiency is low, the fuselage is also relatively bulky. Work efficiency is the yardstick for measuring the economy of the machine, resulting in various losses in the working capacity of the steam inside the steam engine, thereby rendering the use of fuel less economical. In high school physics textbook, there is