畢業(yè)設(shè)計(jì)外文資料翻譯-空冷熱交換器和空冷塔-全文預(yù)覽

　　

【正文】 ecirculation in cooling tower consisting of two rows of three cells separated by one cell width. Figure : Re, circulation in a row consisting of twelve hybrid cooling tower cells. The lowest recirculation is observed when the wind blows in the direction of the major axis of the cell row. The influence of the number of cells under these conditions is shown in figure . 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 20 Figure : Recirculation as a function of number of cells in row. The influence of the ratio of wind speed to plume exhaust speed Vw/Vp on recirculation is shown in figure . A maximum recirculation occurs at a wind speed of 5 m/s. Figure : Recirculation as function of speed ratio. When two rows of six ceils each are placed next to each other with their major axes in parallel, the resultant average interference for different spacings between them is shown in figure . The interference for rows of twelve cells are shown in figure . 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 21 Figure : Interference for two rows of six cells at different spacings. Figure : Interference for two rows of twelve ceils at different spacings. Recirculating plume air increases the effective wetbulb temperature at the inlet to the cooling tower as shown in figure . Since this increase is not only a function of the wetbulb temperature of the ambient air, but also of the thermodynamic state of the plume air, figure is at best an indication of the trend in wetbulb temperature change. 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 22 Figure : Increase in wetbulb temperature due to recirculation. 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 1 空冷熱交換器和空冷塔 (本文譯自 MR KROGER 的空冷熱交換器和空冷塔一書 包括 ， ， ） 回流： 熱空氣在空冷換熱器中會(huì)出現(xiàn)回流現(xiàn)象，因此，會(huì)降低冷卻效率，圖 所示，為一個(gè)“ X”型空冷熱交換器，在無風(fēng)的情況下，有浮力的水蒸氣在換熱器中垂直上升。 （ 二 〇 〇 七 年 六 月 本科畢業(yè)論文 外文翻譯 題 目： 空冷熱交換器和空冷塔 學(xué) 生 姓 名 ： 學(xué) 院 ： 電 力 學(xué) 院 系 別： 能 源 與 動(dòng) 力 工 程 專 業(yè)： 熱 能 與 動(dòng) 力 工 程 班 級(jí) ： 動(dòng) 本 2021 ② 指 導(dǎo) 教 師 ： 學(xué)校代碼： 10128 學(xué) 號(hào)： 031203060 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 1 Aircooled Heat Exchangers and Cooling Towers . (MIT) (This text is a part of MR KROGER39。s equation between the tower outlet at the top of the wind wall and the elevation Hi. 221 2/ awooooa pgHvp ??? ?? () But woaaa gHpp ??? 12 () Substitute equation () into equation () and find ])(2[2 gvH oaoowo ??? ?? () If it is assumed that the recirculation decreases approximately linearly with increasing wind wall height, equation (8,) may be extended as follows: )1()(321 3 wowia io HHaFrHWr ?? ?? () Since the recirculation is assumed to be essentially zero at Hw = Hwo, find a = 1. Substitute equation () into equation () and find ]21[)(321])(21[)(161 3223wiaiooowoaioiaio F r DFrHWv gHgWvHWr ????? ??? ???? () where ])/[(2 woaoow gHvF rD ??? ?? is the densimetric Froude number based on the wind wall height. It is important to determine the effectiveness of the system when recirculation occurs. Effectiveness in this case, is defined as e rr ?? i onre c i rc ul a t nofe r w i t h he a t t ra ns i onre c i rc ul a tfe r w i t h he a t t ra ns () The interrelation between the recirculation and the effectiveness is plex in a real heat exchanger. Two extremes can however be evaluated analytically . 1. No mixing The warm recirculating air does not mix at all with the cold ambient inflow, resulting in a temperature distribution as shown in figure (a). The recirculating stream assumes 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 5 the temperature of the heat exchanger fluid heT . Figure : Recirculation flow patterns. This in effect means that the part of the heat exchanger where recirculation occurs, transfers no heat. The actual heat transfer rate is thus given by )( aopar TTcmQ ?? () resulting in an effectiveness due to recirculation of rm mmTTcmm TTcme raopra aopar ?????? ?? 1)()()( )( () Substitute equation () into equation () and find ])(21[)(1611 223oowoaioiaior v gHgWvHWe ? ???? ???? () 2. Perfect mixing The recirculating air mixes perfectly with the inflowing ambient air, resulting in a uniform increase in both the effective inlet air temperature and the outlet air temperature as shown in figure (b). If for purpose of illustration, it is assumed that the temperature of the heat exchanger, heT ,is constant, it follows from equation () that the effectiveness under crossflow conditions is )/e xp (1)( )()( )( pirhe irorirhep irorp mcUATT TTTTmc TTmce ????????? () or )/e x p ()( pirheheor mcUATTTT ???? () Furthermore the enthalpy entering the heat exchanger is 內(nèi)蒙古工業(yè)大學(xué)本科畢業(yè)論文 6 orprapairp TcmTcmTmc ?? or oraorrarir rTTrmTmm TmmT ?????? )1()( () Substitute equation () into equation () and find )/e xp (1 )/e xp (])1([)/e xp (])1([ p paheheporaheheor mcUAr mcUATrTTmcUArTTrTTT ?? ??????????? () In this case the effectiveness due to recircuiation is given by aoiroraopirorpr TT TTTTmc TTmce ?????? )( )( From equation () and (), substitute the values of Tir and Tor into this equation, to find the effectiveness of the heat exchanger. ])/e xp (1 )/e xp (})1({[)( )1( ap pahehearorr TmcUAr msUA