【正文】 第一篇：過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)翻譯 19Reading Material19ShellandTube Heat ExchangersShellandtube exchangers are made up of a number of tubes in parallel and series through which one fluid travels and enclosed in a shell through which the other fluid is shell side is provided with a number of baffles to promote high velocities and largely more efficient cross flow on the outsides of the versatility and widespread use of this equipment has given rise to the development of industrywide standards of shich the most widely observed are the TEMA typical shellandtube exchanger is presented on pitch , or distance between baffles, normally is ~ times the inside diameter of the the heat transfer coefficient and the pressure drop depend on the baffle pitch, so that is selection is part of the optimization of the heat window of segmental baffles monly is abort 25%, but it also is a parameter in the thermalhydraulic design of the order to simplify external piping, exchangers mostly are built with even number of tube reduces the number of the tubes that can be acmodated in a shell of a given tube pitch in parison with triangular pitch acmodates fewer tubes but is preferable when the shell side must be cleaned by shell passes are obtained with a longitudinal than two shell passes normally are not provided in a single shell, brt a 4~8 arrangement is thermally equivalent to two 2~4 shells in series, and higher binations is obtainable with shelland –tube exchangers, in particular: ● Single phase, condensation or boiling can be acmodated in either the tubes or the shell, in vertical or horizontal positions.● Pressure range and pressure drop are virtually unlimited, and can be adjusted independently for the two fluids.● Thermal stresses can be acmodated inexpensively.● A great variety of materials of construction can be used and may be different for the shell and tubes.● Extended surfaces for improved heat transfer can be used on either side.● A great range of thermal capacities is obtainable.● The equipment is readily dismantled for cleaning or considerations may influence which fluid goes on the tube side or the shell tube side is preferable for the fluid that has the higher pressure, or the higher temperature or is more tube side is less likely to leak expensive or hazardous fluids and is more easily pressure drop and laminar heat transfer can be predicted more accurately for the tube , when these factors are critical, the tube side should be selected for that flow is obtained at lower Reynolds numbers on the shell side, so that the fluid with the lower mass flow preferably goes on that Reynolds numbers are obtained by multipassing the tube side, but at a substantial number of parameters is involved in the design of a shelland –tube heat exchanger for specified thermal and hydraulic conditions and desired economics, including: tube diameter, thickness, length, number of passes, pitch, square or triangular。size of shell,number of shell baffles, baffle type, baffle windows, baffle spacing, and so even a modest sized design program, it is estimated that 40 separate logical designs may need to be made which lead to ? different paths through the such a number is entirely too large for normal puter process, the problem must be simplified with some arbitrary decisions based on as much current practice as 管殼式換熱器管殼式換熱器是由一定數(shù)量的內(nèi)有液體流動(dòng)的平行管子和將其包圍住的內(nèi)有另一種液體的殼體組成的。殼內(nèi)有一定數(shù)量的折流板以提高管外液體的流速和橫流效率。由于換熱器的廣泛使用及其功能的多樣性，使它成為最受TEMA標(biāo)準(zhǔn)關(guān)注的工業(yè)標(biāo)準(zhǔn)的設(shè)備。換熱系數(shù)和壓力降均由折流板的間距決定，所以其選取對(duì)于換熱器的選擇至關(guān)重要。弓形擋板的橫截面積通常是殼體截面的25%，但也是在熱力液壓設(shè)備設(shè)計(jì)中的一個(gè)參數(shù)。為了簡(jiǎn)化管道，換熱器通常采用多管程。在固定的殼體容積中通過(guò)分層可以減少管子的數(shù)量。方形分布和三角形分布比起來(lái)能容納的管子更少些，但若殼體需經(jīng)常清洗的話(huà)前者更常用。雙管程是由縱向分布的折流板構(gòu)成的。多于雙管程的話(huà)通常不僅僅需要單個(gè)殼體，24個(gè)殼體就相當(dāng)于48管程，連接更多殼體就可得到更多管程。管殼式換熱器可以有多種設(shè)計(jì)方案和適用于多種條件，尤其是：● 單殼程結(jié)構(gòu)冷凝或蒸發(fā)可在管中或殼內(nèi)進(jìn)行，換熱器可水平或垂直放置● 壓力分布和壓力降不受限制，并可以單獨(dú)由兩種液體控制● 熱應(yīng)力較小● 用多種材料且殼體和管道使用不同種材料時(shí)● 可在殼程或管程內(nèi)增大表面積以增加熱交換系數(shù)● 需獲得更大范圍的熱容量● 設(shè)備易拆卸以便于清洗和維修一些因素會(huì)影響何種液體走管內(nèi)還是管外高壓、高溫、強(qiáng)腐蝕性的液體更適合走管內(nèi)。在管內(nèi)，貴重液體不容易泄露，毒性液體也更容易清洗。管內(nèi)的壓力降和換熱系數(shù)能得以更精確的估算。因此，如果對(duì)這些條件有嚴(yán)格的要求的話(huà)，液體應(yīng)走管內(nèi)。液體在殼體中流動(dòng)的雷諾數(shù)較低時(shí)形成湍流，因此低密度的液體更適于在殼體內(nèi)流動(dòng)。采用多管道可獲得較高的雷諾數(shù)，但造價(jià)高。設(shè)計(jì)管殼式換熱器時(shí)，在考慮一定的熱力、壓力條件和經(jīng)濟(jì)性的情況下需要參照涉及到大量的參數(shù)，包括：管道直徑、管壁厚度、長(zhǎng)度，管程數(shù)量，間距、方形分布或三角形分布；殼體的尺寸、折流板的數(shù)量、類(lèi)型、橫截面積等等。假設(shè)僅僅是一個(gè)中型的設(shè)計(jì)，據(jù)估計(jì)都有種40種方案，邏輯上由此產(chǎn)生240=。鑒于這樣的數(shù)字對(duì)于一般的電腦程序來(lái)說(shuō)太龐雜，問(wèn)題必須根據(jù)現(xiàn)有實(shí)際情況盡量簡(jiǎn)化。第二篇：過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)翻譯In our parison of the net electrical power output of both bined heat and power(CHP)and poweronly plants, the electrical output of the CHP plants is assumed to be the output that could the oretically be produced if there were no heat electrical power凈電力bined heat and power熱電聯(lián)供Plant設(shè)備be assumed to be假設(shè)為T(mén)heoretically理論地；理論上在我們的熱電聯(lián)供和只供電的設(shè)備的凈電力輸出比較中，熱電聯(lián)供設(shè)備的電力輸出是看做理論上如果沒(méi)有熱輸出時(shí)產(chǎn)生的輸出量。The lower heating value is defined here as the higher heating value(HHV)minus the energy necessary to evaporate the water that is created by the bustion of the hydrogen in the fuel and minus the energy needed to evaporate the moisture that was already part of the fuel before value熱值Evaporate [?39。v230。p?ret]……蒸發(fā)；使……脫水；使……消失，揮發(fā)；消失，失蹤C(jī)ombustion [k?m39。b?st??n] ，氧化；騷動(dòng)moisture [39。m??st??] ；濕度；潮濕；降雨量低熱值在這里定義為高熱值減去使水分蒸發(fā)所需要的能量，這些能量包括使燃料中的氫燃燒產(chǎn)生的水分蒸發(fā)所必需的能量和使燃料燃燒前所含有的水分蒸發(fā)所需要的能量。In the case of biomass bustion , however, this will be possible on only very large scales, whereas atmospheric biomass gasification is projected to attain these efficiencies on considerably smaller scales。biomass [‘ba??(?)m230。s] biomass bustion 生物質(zhì)能large scales 大規(guī)模gasification [,ɡ230。sifi39。kei??n] 可是對(duì)于生物質(zhì)能，它將可能僅在非常大的范圍內(nèi)獲得，然而在大氣中的生物質(zhì)氣化將在相當(dāng)小的范圍內(nèi)獲得這些效能。In developing countries like Ghana where solid waste disposal is increasingly an environmental burden with its attendant health hazards, the idea of converting the organic fraction of municipal solid waste into energy for the national grid is a wele proposition towards reducing volumes of domestic waste to be disposed of or —；burden—；attendant—隨員、伴隨的；hazard—；convert—；organic fraction—有機(jī)部分；municipal—市政的；the national grid—國(guó)家電網(wǎng)；proposition—提議volumes of—