專業(yè)英語動力工程

1、Unit Four Lesson 13 Thermodynamic Principles of RefrigerationLesson 14 Mechanical Refrigeration PrinciplesLesson 15 EvaporationLesson 16 Condensation1-2專業(yè)英語Unit Four Lesson 13 Thermodynamic Principles of RefrigerationNew Words & ExpressionsTextNotes to the TextExercise1-3專業(yè)英語Unit Four New Words

2、& ExpressionsLesson 13(使)循環(huán),流通 principle of operation工作原理, 操作原理refrigeration n.冷藏, 致冷, 冷卻refrigerant n.制冷劑certain adj.;pron.確定的, 必然的,/ 某些equivalent n.等(當)量heat equivalent of work熱功當量gather vt.聚集,吸引substance n.物質(zhì), 實質(zhì), 主旨circulate vi.;vt.1-4專業(yè)英語Unit Four Lesson 13New Words & Expressions:蒸汽噴射式u

3、tilize vt.利用compression n.壓縮compression-type壓縮式vapor-compression蒸汽壓縮subdivide vt.;vi.再(細)分subdivideinto把再分成absorption n.吸收jet n.射流,噴射噴射器vapor-jet type1-5專業(yè)英語Unit Four Lesson 13New Words & Expressions:相反的,可逆的achieve vt.完成, 達到extract vt.抽(取,排)出,萃(提)取repeated a.反復的perform vt.完成cycle n.循環(huán),一個操作過程reve

4、rse a.1-6專業(yè)英語Unit Four Text Para1The principle of operation of refrigeration machines is based on the second law of thermodynamics. A certain amount of work has to be done to transfer heat from a cold body to a hot body. Lesson 131-7專業(yè)英語Unit Four Text:Para2 The second law of thermodynamics is mathem

5、atically expressed as Qk =Q0+L, J; (Qk = Q0+AL, kcal),Where Qk is the quantity of heat transferred to the hot body;Q0is the quantity of heat given out by the cold body; L is the work done to transfer the heat;A=1/427 is the heat equivalent of work.Lesson 131-8專業(yè)英語Unit Four Text:Para3 Machines that g

6、ather heat from a cold body and give it to a hot body are called refrigeration machines. Heat is transferred form a body at a lower temperature to a body at a higher temperature by a working substance (fluid) circulating in the refrigeration machine.1 Lesson 13 1-9專業(yè)英語Unit Four Text:Para4 Refrigerat

7、ion machinery in which mechanical energy is utilized is called compression-type refrigeration machine; refrigeration machines in which heat energy is utilized are subdivided into the absorption and vapor-jet type machines.Lesson 13 1-10專業(yè)英語Unit Four Text:Para5 The working substance used in cooling m

8、ay be refrigerants or air. In the first case the cooling effect is achieved as a result of a change in the state of the working substance-boiling of a liquid are called vapor-compressing machines. In the second case cooling is achieved as a result of transfer of heat from the cooled product to cold

9、air. Refrigeration machines working on this principle are called air refrigerators. Lesson 13 1-11專業(yè)英語Unit Four Text:Para6 Figure13-1 shows the working principle of a refrigeration machine. The working substance extracts a quantity of heat Q0 from the cold body (surrounding medium) and gives it to t

10、he heated one, which is the surrounding air or water. According to the second law of thermodynamics, work equal to L has to be expended for such a transfer, so that the heat given to the heated body equals. 2 Qk = Q0+L after giving heat Qk to the heated body the working substance is once again ready

11、 to extract heat Q0 from the cold body and the process is repeated. 3 Thus the working substance performs a cycle. To carry out this cycle work is expended so that heat from a cold body is given to a hot body, i.e.a reverse cycle. Lesson 13 1-12專業(yè)英語Unit Four 譯文：Para1制冷機的工作原理是根據(jù)熱力學第二定律。要把熱量從低溫物體傳向高溫物

12、體就必須消耗一定量的功。 Para2熱力學第二定律的數(shù)學表達式為： Qk =Q0+L, J; (Qk = Q0+AL, kcal), 式中 Qk是熱量傳向高溫物體向高溫物 體放出熱量. Q0 是由低溫物體放出熱量。 L 是所做的功轉換成熱。 A = 1/427 是熱功當量.1-13專業(yè)英語Unit Four Para3從低溫物體吸取熱量并把熱量傳遞給高溫物體的機器叫做制冷機。將熱從溫度較低的物體傳遞到溫度較高的物體的工作是由在制冷機中循環(huán)的工質(zhì)（流體）來完成的。 Para4利用機械能的制冷機叫做壓縮式制冷機。利用熱能的制冷機可再分為吸收式和蒸氣噴射式兩種。1-14專業(yè)英語Unit Four P

13、ara5用于制冷的工質(zhì)可以是制冷劑或空氣。第一種情況，由于低溫下液體制冷劑的工質(zhì)汽化狀態(tài)的變化而達到制冷效果。這樣的機器叫做蒸氣壓縮機。第二種情況，把熱量從冷卻物體轉移到冷卻空氣進行制冷，依據(jù)這樣原理工作的制冷機叫做空氣制冷機。Para6圖13-1 說明了制冷機的工作原理。工質(zhì)從低溫物體（冷源）吸取熱量Q0,并把熱量傳遞給高溫物體（熱源）。這種高溫熱源通常是周圍的空氣和水（環(huán)境介質(zhì)）。根據(jù)熱力學第二定律，為完成這種傳遞必須消耗相當于L的功，致使傳給高溫物體的熱等于 Qk = Q0 + L.把熱量Qk傳遞給高溫物體后，工質(zhì)重新對冷源吸熱Q0 ，這種過程反復進行。于是工質(zhì)完成了一個循環(huán)。要進行這樣

14、的循環(huán)，要利用工質(zhì)膨脹到較低的溫度，才能把熱量從低溫物體傳向高溫物體，也就是逆向循環(huán)。1-15專業(yè)英語Unit Four Notes to the TextLesson131-16專業(yè)英語Unit Four Notes to the Text 1.Heat is transferred from a body at a lower temperature to a body at a higher temperature by a working substance (fluid )circulating in the refrigeration machine.Lesson 13 將熱從溫度

15、較低的物體傳遞到溫度較高的物體是在制冷機中循環(huán)的工質(zhì)(流體)來完成的.circulating in the refrigeration machine，是現(xiàn)在分詞短語,做substance的定語 ，意為“在制冷機中循環(huán)的”。 1-17專業(yè)英語Unit Four Notes to the Text 2.According to the second law of thermodynamics, work equal to L has to be expended for such a transfer, so that the heat given to the heated body equa

16、ls Qk =Q0+L .Lesson 13 根據(jù)熱力學第二定律,為完成這種傳遞必須耗費相當于L的功,致使傳給熱物體的熱等于Qk =Q0+L . 此句為帶有一個結果狀語從句的主從復合句. equal to L 相當于L的(形容詞短語,做work的定語).according to 意為“按照; 根據(jù).所說; 隨.而”。例如：according to all accounts 照大家所說的act according to circumstances隨機應變from each according to his ability, to each according to his work 各盡所能,

17、按勞分配。1-18專業(yè)英語Unit Four Notes to the Text 3.After giving heat Qk to the heated body the working substance is once again ready to extract heat Q0 from the cold body and the process is epeated.Lesson 13 工質(zhì)把熱Qk傳給了受熱的物體后,又立即從冷物體抽取熱Q0,此過程便反復進行.連詞and在本句中表示連貫關系.可譯成“就,便,于是”等等。例如： The two men lay down and soo

18、n fell asleep.那兩人躺下,很快就入睡了(或“不久便睡著了”)。1-19專業(yè)英語Unit Four ExerciseExerciseLesson 13Decide whether the following statements are true (T) or false (F) according to the text.1-20專業(yè)英語Unit Four ExerciseExercise(T)(F)(T)(F )Lesson 13 1.Engineers use thermodynamics in the design of engines and propulsion (n.推進，推進力)systems. 2. There are some processes which destroy entropy. 3. It is possible to calculate the maximum amount of useful power that can be obtained from a given energy source on the b