外文翻譯--燃料電池及其發(fā)展前景

1、<p><b>　　文獻翻譯</b></p><p><b>　　英文原文：</b></p><p>　　Fuel Cells and Their Prospects</p><p>　　A fuel cell is an electrochemical conversion device. It produce

2、s electricity from fuel (on the anode side) and an oxidant (on the cathode side), which react in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the elect

3、rolyte remains within it. Fuel cells can operate virtually continuously as long as the necessary flows are maintained.</p><p>　　Fuel cells are different from electrochemical cell batteries in that they consu

4、me reactant from an external source, which must be replenished--a thermodynamically open system. By contrast batteries store electrical energy chemically and hence represent a thermodynamically closed system.</p>

5、<p>　　Many combinations of fuel and oxidant are possible. A hydrogen cell uses hydrogen as fuel and oxygen (usually from air) as oxidant. Other fuels include hydrocarbons and alcohols. Other oxidants include chlorin

6、e and chlorine dioxide. </p><p>　　Fuel cell design</p><p>　　A fuel cell works by catalysis, separating the component electrons and protons of the reactant fuel, and forcing the electrons to trav

7、el though a circuit, hence converting them to electrical power. The catalyst typically comprises a platinum group metal or alloy. Another catalytic process takes the electrons back in, combining them with the protons and

8、 oxidant to form waste products (typically simple compounds like water and carbon dioxide).</p><p>　　A typical fuel cell produces a voltage from 0.6 V to 0.7 V at full rated load. Voltage decreases as curren

9、t increases, due to several factors:</p><p>　　Activation loss </p><p>　　Ohmic loss (voltage drop due to resistance of the cell components and interconnects) </p><p>　　Mass transport

10、 loss (depletion of reactants at catalyst sites under high loads, causing rapid loss of voltage) </p><p>　　To deliver the desired amount of energy, the fuel cells can be combined in series and parallel circu

11、its, where series yield higher voltage, and parallel allows a stronger current to be drawn. Such a design is called a fuel cell stack. Further, the cell surface area can be increased, to allow stronger current from each

12、cell.</p><p>　　Proton exchange fuel cells</p><p>　　In the archetypal hydrogen–oxygen proton exchange membrane fuel cell (PEMFC) design, a proton-conducting polymer membrane, (the electrolyte), s

13、eparates the anode and cathode sides. This was called a "solid polymer electrolyte fuel cell" (SPEFC) in the early 1970s, before the proton exchange mechanism was well-understood. (Notice that "polymer ele

14、ctrolyte membrane" and "proton exchange mechanism" result in the same acronym.)</p><p>　　On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates into protons and

15、electrons. These protons often react with oxidants causing them to become what is commonly referred to as multi-facilitated proton membranes (MFPM). The protons are conducted through the membrane to the cathode, but the

16、electrons are forced to travel in an external circuit (supplying power) because the membrane is electrically insulating. On the cathode catalyst, oxygen molecules react with the</p><p>　　In addition to this

17、pure hydrogen type, there are hydrocarbon fuels for fuel cells, including diesel, methanol (see: direct-methanol fuel cells and indirect methanol fuel cells) and chemical hydrides. The waste products with these types of

18、fuel are carbon dioxide and water.</p><p>　　The materials used in fuel cells differ by type. In a typical membrane electrode assembly (MEA), the electrode–bipolar plates are usually made of metal, nickel or

19、carbon nanotubes, and are coated with a catalyst (like platinum, nano iron powders or palladium) for higher efficiency. Carbon paper separates them from the electrolyte. The electrolyte could be ceramic or a membrane.<

20、;/p><p>　　Oxygen ion exchange fuel cells</p><p>　　In a solid oxide fuel cell design, the anode and cathode are separated by an electrolyte that is conductive to oxygen ions but non-conductive to el

21、ectrons. The electrolyte is typically made from zirconia doped with yttria.</p><p>　　On the cathode side, oxygen catalytically reacts with a supply of electrons to become oxygen ions, which diffuse through t

22、he electrolyte to the anode side. On the anode side, the oxygen ions react with hydrogen to form water and free electrons. A load connected externally between the anode and cathode completes the electrical circuit.</p

23、><p>　　Fuel cell design issues</p><p><b>　　Costs</b></p><p>　　In 2002, typical cells had a catalyst content of US$1000 per-kilowatt of electric power output. In 2008 UTC Po

24、wer has 400kw Fuel cells for $1,000,000 per 400kW installed costs. The goal is to reduce the cost in order to compete with current market technologies including gasoline internal combustion engines. Many companies are wo

25、rking on techniques to reduce cost in a variety of ways including reducing the amount of platinum needed in each individual cell. Ballard Power Systems have experiments w</p><p>　　The production costs of the

26、 PEM (proton exchange membrane). The Nafion membrane currently costs €400/m². In 2005 Ballard Power Systems announced that its fuel cells will use Solupor, a porous polyethylene film patented by DSM.</p><

27、p>　　Water and air management (in PEMFC). In this type of fuel cell, the membrane must be hydrated, requiring water to be evaporated at precisely the same rate that it is produced. If water is evaporated too quickly, t

28、he membrane dries, resistance across it increases, and eventually it will crack, creating a gas "short circuit" where hydrogen and oxygen combine directly, generating heat that will damage the fuel cell. If the

29、 water is evaporated too slowly, the electrodes will flood, preventing the re</p><p>　　Temperature management</p><p>　　The same temperature must be maintained throughout the cell in order to pre

30、vent destruction of the cell through thermal loading. This is particularly challenging as the 2H2 + O2 =2H2O reaction is highly exothermic, so a large quantity of heat is generated within the fuel cell.</p><p&

31、gt;　　Durability, service life, and special requirements for some type of cells</p><p>　　Stationary fuel cell applications typically require more than 40,000 hours of reliable operation at a temperature of -3

32、5°C to40°C, while automotive fuel cells require a 5,000 hour lifespan (the equivalent of 150,000 miles) under extreme temperatures. Automotive engines must also be able to start reliably at -30 °C and have

33、 a high power to volume ratio (typically 2.5 kW per liter).</p><p><b>　　History</b></p><p>　　The principle of the fuel cell was discovered by German scientist Christian Friedrich Sch

34、önbein in 1838 and published in one of the scientific magazines of the time. Based on this work, the first fuel cell was demonstrated by Welsh scientist Sir William Robert Grove in the February 1839 edition of the P

35、hilosophical Magazine and Journal of Science, and later sketched, in 1842, in the same journal. The fuel cell he made used similar materials to today's phosphoric-acid fuel cell.</p><p>　　In 1955, W. Tho

36、mas Grubb, a chemist working for the General Electric Company (GE), further modified the original fuel cell design by using a sulphonated polystyrene ion-exchange membrane as the electrolyte. Three years later another GE

37、 chemist, Leonard Niedrach, devised a way of depositing platinum onto the membrane, which served as catalyst for the necessary hydrogen oxidation and oxygen reduction reactions. This became known as the“Grubb-Niedrach fu

38、el cell”. GE went on to develop this technolo</p><p>　　United Technologies Corporation's UTC Power subsidiary was the first company to manufacture and commercialize a large, stationary fuel cell system f

39、or use as a co-generation power plant in hospitals, universities and large office buildings. UTC Power continues to market this fuel cell as the PureCell 200, a 200 kW system (although soon to be replaced by a 400 kW ver

40、sion, expected for sale in late 2009). UTC Power continues to be the sole supplier of fuel cells to NASA for use in space vehicles, </p><p>　　Fuel cell efficiency</p><p>　　The efficiency of a fu

41、el cell is dependent on the amount of power drawn from it. Drawing more power means drawing more current, which increases the losses in the fuel cell. As a general rule, the more power (current) drawn, the lower the effi

42、ciency. Most losses manifest themselves as a voltage drop in the cell, so the efficiency of a cell is almost proportional to its voltage. For this reason, it is common to show graphs of voltage versus current (so-called

43、polarization curves) for fuel cells. A</p><p>　　For a hydrogen cell operating at standard conditions with no reactant leaks, the efficiency is equal to the cell voltage divided by 1.48 V, based on the enthal

44、py, or heating value, of the reaction. For the same cell, the second law efficiency is equal to cell voltage divided by 1.23 V. (This voltage varies with fuel used, and quality and temperature of the cell.) The differenc

45、e between these numbers represents the difference between the reaction's enthalpy and Gibbs free energy. This difference </p><p>　　Fuel cells do not operate on a thermal cycle. As such, they are not cons

46、trained, as combustion engines are, in the same way by thermodynamic limits, such as Carnot cycle efficiency. At times this is misrepresented by saying that fuel cells are exempt from the laws of thermodynamics, because

47、most people think of thermodynamics in terms of combustion processes (enthalpy of formation). The laws of thermodynamics also hold for chemical processes (Gibbs free energy) like fuel cells, but the maximum t</p>

48、<p>　　In practice, for a fuel cell operating on air (rather than bottled oxygen), losses due to the air supply system must also be taken into account. This refers to the pressurization of the air and dehumidifying i

49、t. This reduces the efficiency significantly and brings it near to that of a compression ignition engine. Furthermore fuel cell efficiency decreases as load increases.</p><p>　　The tank-to-wheel efficiency o

50、f a fuel cell vehicle is about 45% at low loads and shows average values of about 36% when a driving cycle like the NEDC (New European Driving Cycle) is used as test procedure. The comparable NEDC value for a Diesel vehi

51、cle is 22%. In 2008 Honda released a car with fuel stack claiming a 60% tank-to-wheel efficiency.</p><p>　　Fuel cells cannot store energy like a battery, but in some applications, such as stand-alone power p

52、lants based on discontinuous sources such as solar or wind power, they are combined with electrolyzers and storage systems to form an energy storage system. The overall efficiency (electricity to hydrogen and back to ele

53、ctricity) of such plants (known as round-trip efficiency) is between 30 and 50%, depending on conditions. While a much cheaper lead-acid battery might return about 90%, the electro</p><p><b>　　參考譯文：<

54、;/b></p><p>　　燃料電池及其發(fā)展前景</p><p>　　燃料電池是一種電化學轉(zhuǎn)換裝置。它產(chǎn)生的電流來自于燃料（陽極側(cè)）和氧化劑（陰極側(cè)）在電解液作用下的化學反應。反應物（燃料）源源不斷地流入電池，而反應產(chǎn)品（也就是電能）則從電池中流出，同時電解液依然保留在電池內(nèi)部。只要保持必要的燃料供給,燃料電池幾乎可以持續(xù)不斷地產(chǎn)生電能。</p><p>　

55、　燃料電池是一種特殊的電化學電池，因為它們的反應消耗來源是從外部獲得，所以必須加以補充，這是一個開放的熱力學系統(tǒng)。相比之下，電池儲存的是化學電能，因此代表的是一個封閉的熱力學系統(tǒng)。</p><p>　　有許多種燃料和氧化劑的組合都是可行的。氫燃料電池使用氫作為燃料，而用氧氣（通常來自于空氣）作為氧化劑。其它燃料包括碳氫化合物和醇類。其它氧化劑包括氯和二氧化氯。</p><p><b&

56、gt;　　燃料電池設(shè)計</b></p><p>　　燃料電池是通過催化作用進行工作的，催化劑通常包括鉑族金屬或合金。在催化作用下將反應燃料的組成部分電子和質(zhì)子分離，并迫使電子沿回路移動，從而將其轉(zhuǎn)化為電流。另一種催化過程需要將電子與質(zhì)子和氧化劑相結(jié)合，形成廢物產(chǎn)品（通常是簡單的化合物，像水和二氧化碳）。</p><p>　　一個典型的燃料電池在額定負載下所產(chǎn)生的電壓從0.6伏至

57、0.7伏不等。電壓會隨電流的增大而減小，主要取決于以下幾個因素：</p><p>　　（催化劑）活性的損失</p><p>　　歐姆損失（由于電池元件的自身電阻以及接觸電阻引起的電壓降）</p><p>　　大量傳輸損失（催化劑在高負荷下反應后枯竭,造成電壓迅速降低）</p><p>　　為了提供所需的大量能源，燃料電池可以串聯(lián)或者并聯(lián)使用，

58、串聯(lián)可以產(chǎn)生較高的電壓而并聯(lián)可以獲得較大的電流。這種設(shè)計通常被稱為燃料電池堆。此外，還可以通過增加電池的表面積來獲得更為強大的電流。</p><p><b>　　質(zhì)子交換膜燃料電池</b></p><p>　　在氫氧質(zhì)子交換膜燃料電池（PEMFC）的原型中，一個質(zhì)子導電聚合物膜（電解質(zhì)），將燃料電池的陽極和陰極分開在兩邊。這就是在20世紀70年代初期質(zhì)子交換原理還沒有

59、被廣泛認識之前，被人們稱為的“固體聚合物電解質(zhì)燃料電池”（SPEFC）。（請注意，“聚合物電解質(zhì)膜”和“質(zhì)子交換機制”）</p><p>　　在陽極側(cè)，氫擴散到陽極,催化劑分裂成質(zhì)子和電子。這些質(zhì)子常常會與氧化劑反應使之成為通常被人們稱作的簡易化質(zhì)子膜（MFPM）。質(zhì)子是通過交換膜向陰極移動的，但電子則被迫沿著外部電路穿行（提供外電流），因為質(zhì)子膜是絕緣的。在陰極催化劑的作用下，氧分子與（已穿過外部電路返回的）電

60、子和質(zhì)子發(fā)生化學反應形成水。在這個反應模式中唯一的廢物產(chǎn)品，要么是液體（水）要么是蒸汽。</p><p>　　除了這種純粹的氫型燃料電池外，還有以碳氫作為燃料的燃料電池，包括柴油，甲醇（分直接甲醇燃料電池和間接甲醇燃料電池）和化學氫化物燃料電池。這些類型燃料電池的廢料產(chǎn)品是二氧化碳和水。</p><p>　　不同類型的燃料電池使用的不同的反應材料。在一個典型的膜電極裝置中，電極的兩個極板通

61、常都是采用金屬制造的，鎳或碳納米管，并涂有催化劑（如鉑，納米鐵粉或鈀），從而使其具有更高的效率。復寫紙將它們與電解質(zhì)分開，電解質(zhì)可以是陶瓷材料或者交換膜。</p><p><b>　　氧離子交換燃料電池</b></p><p>　　在固體氧化物燃料電池的設(shè)計中，陽極和陰極是由能夠傳導氧離子但是不能傳導電子的電解質(zhì)分隔開來。電解質(zhì)通常是由參雜氧化釔的氧化鋯材料組成。&l

62、t;/p><p>　　在陰極一側(cè)，氧氣與電子通過催化反應成為氧離子，它通過電解液擴散到陽極側(cè)。在陽極一側(cè)，氧離子與氫反應形成水和自由電子。于是連接在陽極和陰極之間的外接負載形成了電流的完整通路。</p><p><b>　　燃料電池設(shè)計問題</b></p><p><b>　　燃料電池的費用</b></p>&l

63、t;p>　　2002年，典型的燃料電池催化劑包含在電力輸出中的費用約為1000美元每千瓦。在2008年美國聯(lián)合技術(shù)公司安裝400千瓦燃料電池的費用是100萬美元。我們的目標是降低發(fā)電成本，以便于同當前市場上的常規(guī)發(fā)電方式比如汽油內(nèi)燃機等競爭。許多公司正致力于提高技術(shù)，試圖通過各種方式減少成本，包括減少鉑在每個電池中的使用量。巴拉德動力系統(tǒng)曾經(jīng)采用增強型碳絲催化劑做過實驗，實驗表明在不影響電池性能的情況下可減少30％（1毫克/ CM

64、2降至0.7毫克/ CM2）的鉑金使用量。</p><p>　　PEM（質(zhì)子交換膜）的生產(chǎn)成本費用。目前的Nafion膜費用＄400 /平方米。在2005年巴拉德動力系統(tǒng)宣布，該公司的燃料電池將使用Solupor膜，一種由DSM研制并擁有專利權(quán)的多孔聚乙烯薄膜。</p><p>　　質(zhì)子交換膜燃料電池中水和空氣的管理。在此類型的燃料電池中，膜必須含水，水的蒸發(fā)速度要與該膜生產(chǎn)過程中的蒸發(fā)速

65、度嚴格一致。如果交換膜中水的蒸發(fā)過快，膜就會太干燥，阻值增大，并最終裂縫，導致氫氣和氧氣直接結(jié)合形成天然氣短路的現(xiàn)象，這樣會產(chǎn)生大量的熱量損壞燃料電池。如果水的蒸發(fā)速度太慢，電極將被淹沒，從而阻止了反應物與催化劑的結(jié)合，化學反應停止。用電水泵流量控制的方法來管理燃料電池交換膜中的水是側(cè)重點，正如在內(nèi)燃機中保持反應物和氧氣穩(wěn)定的比例是非常重要的一樣，從而保持燃料電池有效地運作。</p><p><b>　

66、　溫度管理</b></p><p>　　必須保持整個電池維持相同的溫度，以防止熱負荷對電池的破壞，這是特別具有挑戰(zhàn)性的。2H2 + O2 =2H2O的反應會在燃料電池中產(chǎn)生大量的熱，損壞燃料電池。</p><p>　　特種類型的電池要求耐用性和使用壽命</p><p>　　固定式燃料電池應該能夠在－35℃至40℃的溫度下穩(wěn)定運行超過4萬小時，而汽車的燃料

67、電池需要在極端溫度下有5千小時的壽命（相當于行駛15萬英里）。</p><p>　　汽車發(fā)動機也必須能夠可靠地運行在－30℃溫度下，并且具有較高的升功率（通常為2.5kw/升）。</p><p><b>　　歷史</b></p><p>　　燃料電池的原理最初是由德國科學家Christian Friedrich Schönbein于1

68、838年發(fā)表在當時的一本科學雜志上。在此基礎(chǔ)上，由威爾士科學家威廉·羅伯特·格羅夫在1839年2月版的哲學雜志和科學期刊上首次論證了燃料電池，并于1842年在同一期刊上提出了設(shè)計原理圖。他設(shè)計的燃料電池使用的材料類似于今天的磷酸燃料電池。</p><p>　　1955年，在通用電氣公司（GE）工作的化學工程師托馬斯·格拉布，進一步修改了原來的燃料電池設(shè)計方案，采用磺化聚苯乙烯離子交換

69、膜作為電解質(zhì)。三年后，另一位通用電氣的化學工程師萊昂納多·涅德拉茨發(fā)明了一種方法，在膜上沉積鉑作為氫與氧的氧化還原反應所必需的催化劑，這被稱為格拉布-涅德拉茨燃料電池。通用電氣公司繼續(xù)與美國航空航天局和麥道飛機公司合作研發(fā)這種技術(shù)，使其應用在了雙子星項目上。這是燃料電池的第一次商業(yè)性使用。此后直到1959年，英國工程師托馬斯·弗朗西斯·培根才成功地開發(fā)出了5千瓦固定式燃料電池。1959年，哈里·艾

70、琳格所領(lǐng)導的設(shè)計小組為愛麗絲·查爾莫斯研制了一臺15千瓦的燃料電池拖拉機，該機在美國國家博覽會上進行了展出。該系統(tǒng)采用氫氧化鉀作為電解質(zhì)，壓縮氫氣和氧氣為反應物。后來在1959年，培根和他的同事們研制出了一臺實用的5千瓦燃料電池機組，能夠為電焊機提供電能。在20世紀60年代，普拉特和惠特尼獲得美國政府特許將培根的專利用于美國在太空計劃中的供電和飲用水供應（氫氣和氧氣在太空艙可以輕松的得到）。</p><p&

71、gt;　　聯(lián)合技術(shù)公司的子公司UTC電力公司是首家生產(chǎn)商業(yè)化大型固定式燃料電池系統(tǒng)的公司，主要用于為醫(yī)院，大學和大型辦公樓提供備用電站。UTC繼續(xù)以純凈電池200的名字在市場上推銷這款200千瓦的產(chǎn)品（雖然很快就要更換400千瓦的版本，預計將在2009年末上市銷售）。目前UTC電力公司仍然是美國宇航局太空車輛燃料電池的唯一供應商，并曾經(jīng)在阿波羅登月和近年來的太空船項目中為宇航局提供幫助。該公司正在開發(fā)燃料電池汽車，公共汽車和手機基站；該

72、公司已經(jīng)展示了第一臺能在冰點以下啟動的質(zhì)子交換膜電動汽車燃料電池。</p><p><b>　　燃料電池的效率</b></p><p>　　燃料電池的效率依賴于從它得出的功率。因此，輸出的功率越多、電流越大，電池的損耗也就越大，效率也就越低。而大多數(shù)損耗都是以電壓降的形式體現(xiàn)出來的，故而電池的效率幾乎和它的輸出電壓成正比。出于這個原因，廠家通常都會給出任何一款電池的伏

73、安特性曲線（所謂的極化曲線）。一個典型的運行在0.7伏輸出電壓的燃料電池的效率約為50％，也就是說氫燃料中的50％的能量轉(zhuǎn)化為了電能，其余的50％將轉(zhuǎn)換成熱量散失掉了。（根據(jù)燃料電池系統(tǒng)的設(shè)計，一些燃料會散失掉并沒有參與反應，從而構(gòu)成了另外一部分額外的損失）</p><p>　　對于一個工作在額定條件下并且沒有反應物流失的氫燃料電池，其發(fā)電效率等于電池電壓除以1.48伏，這是基于熱焓或反應熱值的影響。對于同一塊電

74、池，另一種計算效率的公式是將電池電壓除以1.23伏（此電壓比值會隨所用燃料類型、質(zhì)量和溫度而變）。上述兩種計算方法之間的差異反應了熱焓和吉布斯自由能之間的差異。這種差異似乎總是以發(fā)熱的形式體現(xiàn)出來，伴隨著其它的電轉(zhuǎn)換效率損失。</p><p>　　燃料電池不是在熱循環(huán)方式下運行的。因此，它們不會像內(nèi)燃機那樣受到熱力學限制，比如卡諾循環(huán)效率。有時人們會錯誤地說：燃料電池免受熱力學定律的限制。因為至少大多數(shù)人單就燃燒

75、過程生成熱焓而言是這樣認為的。熱力學定律同樣適用于類似燃料電池這樣的化學反應過程（吉布斯自由能），但是其理論熱效率（在熱力學溫度298K時的熱效率為83%）要高于奧托循環(huán)熱效率（在壓縮比為10，絕熱系數(shù)為1.4時的熱效率為60%）。比較帶有限制條件的熱力學不是對實際應有效率的好的預測。同樣，如果是用于電力拖動，那么燃料電池的輸出不得不再次轉(zhuǎn)換為相應低效率的機械功率。關(guān)于上文中提到的豁免要求，正確的說法是：“熱力學第二定律對于燃料電池的工

76、作所施加的限制要比對常規(guī)的能量轉(zhuǎn)換系統(tǒng)所施加的限制小得多”。 因此，燃料電池在將化學能轉(zhuǎn)化成電能的過程中具有很高的效率，尤其是當它們運行在低功率密度下，并且利用純氫氣和氧氣作為反應劑。</p><p>　　在實際使用過程中，使用空氣（而不是瓶裝氧氣）的燃料電池，在送風系統(tǒng)中造成的損失也必須加以考慮，這是指為空氣增壓和除濕。這大大降低了效率，使得燃料電池的效率和壓縮點火式內(nèi)燃機非常接近。此外燃料電池的效率隨負荷的增

77、加而降低。</p><p>　　燃料電池汽車在低負荷時的油箱到車輪效率為45％左右，在被用作測試工況的NEDC（新歐洲行駛工況）下運行時所顯示的效率平均值為36％。對比同樣行駛在NEDC工況下的柴油機車輛，其效率僅為22％。在2008年本田公司推出了一款聲稱油箱到車輪效率可達60%的使用燃料堆棧的概念汽車。</p><p>　　燃料電池不可能像電池一樣儲存能量，但在某些應用場合，比如說建立