火電廠自動(dòng)化_電氣自動(dòng)化畢業(yè)論文中英文資料外文翻譯-資料下載頁
2025-03-04 00:55本頁面
【導(dǎo)讀】對(duì)于目前為止最大的發(fā)電工業(yè)部門來說，蒸汽動(dòng)力是最為基礎(chǔ)性的。若沒有蒸汽動(dòng)力，社會(huì)的樣子將會(huì)變得和現(xiàn)在大為不同。我們將不得已的去依靠水力發(fā)電廠、風(fēng)車、電池、太陽能蓄電池和燃料電池，這些方法只能為我們平日用電提供很小的一部分。此書旨在在發(fā)電廠的工程規(guī)程和電子學(xué)、儀器儀表以。及控制工程之間架設(shè)一座橋梁。的基本原則的概述。這看似簡(jiǎn)單的課題實(shí)際上卻極為復(fù)雜。得到的熱量因?yàn)樵谀硶r(shí)水開始沸騰時(shí)其效果可被察覺，因而被稱為感熱?！胺序v”究竟是什么含義？子氣體經(jīng)常被認(rèn)為是物質(zhì)的第四種狀態(tài)，但在實(shí)際應(yīng)用中，只需考慮以上三種狀態(tài)）固態(tài)，使得分子之間的間隙增大。這種由固態(tài)到液態(tài)的狀態(tài)變化通常被稱之為熔化。為蒸汽的過程，也就是液體處于汽化狀態(tài)。使這一現(xiàn)象發(fā)生的溫度被稱。必須被加熱到一百零二度才可以使之沸騰。如前所述,熱量補(bǔ)充給已開始沸騰的水不會(huì)引起溫度的進(jìn)一步變化。于增加每公斤流體過熱程度。
【正文】 plying to the conversion of heat energy into mechanical energy. He saw that if this process were to be made reversible, heat could be converted into work and then extracted and reused to make a closed loop. In his concept (Figure ), a piston moves freely without encountering any friction inside a cylinder made of some perfectly insulating material. The piston is driven by a 39。working fluid39。. The cylinder has a head at one end that can be switched at will from being a perfect conductor to being a perfect insulator. Outside the cylinder are two bodies, one of which can deliver heat without its own temperature ( T1 ) falling, the other being a bottomless cold sink at a temperature (T2) which is also constant. The operation of the system is shown graphically in figure , which shows the pressure/volume relationship of the fluid in the cylinder over the whole cycle. As the process is a repeating cycle its operation can be studied from any convenient starting point, and we shall begin at the point A, where the 11 cylinder head (at this time assumed to be a perfect conductor of heat), allows heat from the hot source to enter the cylinder. The result is that the medium begins to expand, and if it is allowed to expand freely, Boyle39。s law (which states that at any temperature the relationship between pressure and volume is constant) dictates that the temperature will not rise, but will stay at its initial temperature (Tl). This is called isothermal expansion. When the pressure and volume of the medium have reached the values at point B, the cylinder head is switched from being a perfect conductor to being a perfect insulator and the medium allowed to continue its expansion with no heat being gained or lost. This is known as adiabatic expansion. When the pressure and volume of the medium reach the values at point C, the cylinder head is switched back to being a perfect conductor, but the external heat source is removed and replaced by the heat sink. The piston is driven towards the head, pressing the medium. Heat flows through the head to the heat sink and when the temperature of the medium reaches that of the heat sink (at point D), the cylinder head is once again switched to bee a perfect insulator and the medium is pressed until it reaches its starting conditions of pressure and cycle is then plete, having taken in and rejected heat while doing external work. The Rankine cycle The Carnot cycle postulates a cylinder with perfectly insulating walls and a head which can be switched at will from Being a conductor to being an insulator. Even with modifications to enable it to operate in a world where such things are not obtainable, it would have probably remained a scientific concept with no practical application, had not a Scottish professor of engineering, William Rankine, proposed a modification to it at the beginning of the twentieth century [I]. The concepts that Rankine developed form the basis of all thermal power plants in use today. Even todays binedcycle power plants use his cycle for one of the two phases of their operation. Figure illustrates the 12 principle of the Rankine cycle. Starting at point A again, the source of heat is applied to expand the medium, this time at a constant pressure, to point B, after which adiabatic expansion is again made to occur until the medium reaches the conditions at point C. From here, the volume of the medium is reduced, at a constant pressure, until it reaches point D, when it is pressed back to its initial conditions.
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