【正文】 s the surface exerts a pressure on the surface of the fluid and, as the temperature of the water is raised, enough energy is eventually gained to overe the blanketing effect of that pressure and the water starts to change its state into that of a vapour (steam). Further heat added at this stage will not cause any further detectable change in temperature: the energy added is used to change the state of the fluid. Its effect can no longer be sensed by a thermometer, but it is still there. For this reason it is called latent, rather then sensible, heat. The temperature at which this happens is called the 39。.As more heat is applied to the liquid, some of the molecules gain enough energy to escape from the surface, a process called evaporation (whereby a pool of liquid spilled on a surface will gradually disappear). What is happening during the process of evaporation is that some of the molecules are escaping at fairly low temperatures, but as the temperature rises these escapes occur more rapidly and at a certain point the liquid bees very agitated, with large quantities of bubbles rising to the surface. It is at this time that the liquid is said to start 39。? To study this we must consider the three basic states of matter: solids, liquids and gases. (A plasma, produced when the atoms in a gas bee ionised, is often referred to as the fourth state of matter, but for most practical purposes it is sufficient to consider only the three basic states.) In its solid state, matter consists of many molecules tightly bound together by attractive forces between them. When the matter absorbs heat the energy levels of its molecules increase and the mean distance between the molecules increases. As more and more heat is applied these effects increase until the attractive force between the molecules is eventually overe and the particles bee capable of moving about independently of each other. This change of state from solid to liquid is monly recognised as 39。I engineer with enough understanding of the subject to deal safely with practical controlsystem design, operational and maintenance problems. Boiling: the change of state from water to steamWhen water is heated its temperature rises in a way that can be detected (for example by a thermometer). The heat gained in this way is called sensible because its effects can be sensed, but at some point the water starts to boil. But here we need to look even deeper into the subject. Exactly what is meant by the expression 39。The basics of steam generation and use Why an understanding of steam is neededSteam power is fundamental to what is by far the largest sector of the electricitygenerating industry and without it the face of contemporary society would be dramatically different from its present one. We would be forced to rely on hydroelectric power plant, windmills, batteries, solar cells and fuel cells, all of which are capable of producing only a fraction of the electricity we use.Steam is important, and the safety and efficiency of its generation and use depend on the application of control and instrumentation, often simply referred to as Camp。林肯,他對卡諾循環(huán)提出了修改，在這個基礎上發(fā)展形成的理論在火力發(fā)電廠被廣泛使用。卡諾循環(huán)設定一個汽缸絕緣墻和可以隨意由導體轉換成絕緣體的氣缸蓋，它可能仍然是一個科學的概念并沒有實際應用中得到運用?；钊_始驅動，然后壓縮介質。當介質的壓力和容積已達到B點時，氣缸蓋由理想導體轉換成一個絕緣體，而介質允許繼續(xù)擴大，而沒有熱的增減，這就是所謂的絕熱膨脹。結果是，中期開始擴大，如果它被允許自由擴大，玻意耳定律（其中指出，在任何溫度之間關系的壓力和容量是常數）中規(guī)定的溫度不會上升，但將留在其初始溫度（T1） 。 ，顯示了壓力/容積關系的流體在汽缸內的整個循環(huán)周期。氣缸的一端，可以自由的從理想導體切換為絕緣體。活塞沒有遇到任何摩擦，內氣缸完全由絕緣材料制成。第一，焦耳定律，與機械能做功有關：卡諾定律定義了