【正文】 2003). PEM FCs operate in the temperature range of 50–which allows fast startup and shutdown. Due to their benefits and advanced stage of development, PEMFC was used for the toy bus and is the focus of this paper.有不同類型的FCs(美國能源部化石能源辦公室和國家能源技術實驗室,2004)杰出主要由類型的電解質(zhì)用于細胞,包括聚合物電解質(zhì)FC(質(zhì)子交換膜燃料電池,也稱為質(zhì)子交換膜FCs),堿性FC(AFC)、磷酸FC(PAFC)、熔融碳酸鹽FC(MCFC)和固體氧化物FC(SOFC)(圖4)。不同的細胞特征,細胞材料、操作溫度和燃料需要被考慮為不同的應用程序。操作低于或接近沸騰的溫度的水,PEMFCs和AFCs依賴質(zhì)子或羥基離子作為主要的電荷載體在電解液中,而在高溫FCs(MCFC和SOFC)碳酸根離子和氧離子的電荷載體。固體氧化物燃料電池的能力和操作MCFC碳酸根離子和氧離子使他們?nèi)剂响`活。相反,質(zhì)子交換膜燃料電池依賴高純度氫氣反應物氫生成和存儲要求新穎技術。PEMFCs有高功率密度、固體電解質(zhì)、壽命長,以及低腐蝕(Larminie amp。迪克斯,2003)。PEM FCs操作溫度范圍50 它允許快速啟動和關閉。由于他們的福利和高級階段的發(fā)展,質(zhì)子交換膜燃料電池是用于玩具公共汽車,是本文的重點。Fig.4.Fuel cell types.。PEMFCs utilize the chemical energy from the reaction of hydrogen and oxygen (referred to as “fuel” from this point on) to produce electricity, water and heat. As shown inFig. 5, fuel travels through inlet manifolds to the flow fields. From the flow fields, gas diffuses through porous media to the membrane. The membrane, sandwiched in the middle of the cell, typically contains catalyst and microporous diffusion layers along with gaskets as a single integrated unit. One side of the membrane is the anode and the other is the cathode. The anode and cathode are more generally described as electrodes. The catalyst layer at the anode separates hydrogen molecules into protons and electrons (2H2→4H++4e). The membrane permits ion transfer (hydrogen protons), enabling the electrons to flow through an external circuit before rebining with protons and oxygen at the cathode to form water(O2+4H++4e→2H2O). This migration of electrons produces electricity, which is the useful work. The overall reaction of the FC is therefore2H2+O2→2H2O+heat.PEMFCs利用化學能量從反應的氫氣和氧氣(稱為“燃料”從這點上)來產(chǎn)生電力,水和熱。見圖5,燃料穿過入口集合管的流場。從流場、氣體通過多孔介質(zhì)擴散到膜。膜,夾在中間的細胞,通常包含催化劑和微孔擴散層以及墊片作為一個單一的集成單元。膜的一側(cè)是陽極,另一個是陰極。陽極和陰極更通常描述為電極。在陽極催化劑層分離氫分子變成質(zhì)子和電子(h2→4 h + 2 + 4 e )。膜允許離子轉(zhuǎn)移(氫質(zhì)子),使電子流過外部電路重組之前與質(zhì)子和氧氣在陰極形成水(O2 + 4 h + + 4 e →2水)。這個電子遷移產(chǎn)生電力,這是有用的工作。整個反應的FC因此2 h2 + O2→2水+熱。Fig.5.Fuel cell ponent description.。The electrical characteristics of FCs are normally given in the form of a polarization curve, as shown inFig. 6, which is a plot of cell voltage versus cell current density (current per unit cell active area) at different reactant pressures and flows. Stack temperature and membrane water content also affect the FC voltage. The difference between the actual voltage and the ideal voltage3represents the loss in the cell which turns into heat. As more current is drawn from the FC, the voltage decreases, due to FC electrical resistance, inefficient reactant gas transport, and low reaction rate. Lower voltage indicates lower efficiency of the FC, hence, low load (low current) operation is preferred. However, operation at low load requires a large FC stack, which adversely affects the overall volume, weight, and cost.電特性的FCs通常的形式給出了極化曲線,見圖6,這是一塊電池電壓與電池電流密度(當前單位細胞活動區(qū)域)在不同反應物壓力和流動。煙囪溫度和膜水含量也影響FC電壓。實際電壓之間的差異和理想的voltage3代表損失細胞變成了熱。隨著越來越多的電流是從FC,電壓降低,由于FC電阻,低效率的反應物氣體運輸和低反應速率。低電壓指示效率低的足球俱樂部,因此,低負荷(低電流)操作優(yōu)先。然而,操作在低負載需要一個大的FC堆棧,其中的不利影響整體的體積、重量和成本。Fig.6.Polarization curves for different cathode pressures.。Instead of oversizing the FC stack, a series of actuators such as valves, pumps, blowers, expander vanes, fan motors, humidifiers and condensers shown inFig. 7are used to control critical FC parameters for a wide range of current, and thus, power setpoints. The auxiliary actuators are needed to make fine and fast adjustments to satisfy performance, safety and reliability standards that are independent of age and operating conditions (Yang, Bates, Fletcher, amp。 Pow, 1998). The resulting multivariate design and control synthesis task, also known as balance of plant (BOP), is plex because of subsystem interactions, conflicting objectives, and lack of sensors. The main control tasks are summarized next with an emphasis on the interactions and conflicts among the main FC subsystems: (i) reactant supply system, (ii) heating and cooling system, (iii) humidification system, and (iv) power management system.而不是在上漿FC堆棧,一系列的致動器如閥門、泵、風機、膨脹機葉片,風機,增濕器和冷凝器顯示在圖7是用來控制臨界FC參數(shù)大范圍的電流,因此,功率設定控制量。輔助執(zhí)行器需要細和快速調(diào)整以滿足性能、安全性和可靠性標準,獨立于年齡和操作條件(楊,貝茨,弗萊徹,1998)。由此產(chǎn)生的多元設計和控制合成的任務,也稱為平衡的植物(BOP),是復雜的子系統(tǒng)交互,因為沖突的目標,和缺乏傳感器?？刂频闹饕蝿帐强偨Y(jié)下強調(diào)交互和沖突中主要FC子系統(tǒng):(i)反應物供應系統(tǒng),(ii)加熱和冷卻系統(tǒng),(iii)加濕系統(tǒng),及(4)電源管理系統(tǒng)。Fig.7.Fuel cell powertrain system.。. Reactant flow management. 反應物流管理The reactant flow subsystem is necessary to rapidly replenish the depleted hydrogen and oxygen associated with the current drawn (load) from the anode and cathode. A low partial pressure of oxygen (hydrogen) in the cathode (anode) causes oxygen (hydrogen) starvation that can damage the FC or significantly reduce its life (Yang et al., 1998). The hydrogen and air supply must be coordinated so that the pressure difference across the FC membrane is small enough to prevent membrane damage. To minimize resistive losses, membranes are very thin. The desired air pressure is slightly lower than the hydrogen pressure to avoid air leaks towards the anode which can form bustible mixture. Issues associated with the hydrogen generation or storage are not discussed in this paper. Models, controllers, and references for a natural gas fuel processor can be found inPukrushpan, Stefanopoulou, and Peng (2004b). Details for hydrogen generation using aqueous borohydride solutions are found inAmendola et al. (2000). Information on hydrogen storage using metalhydride tanks can be found inJeong and Oh (2002).反應物的流動子系統(tǒng)需要迅速補充耗盡的氫氣和氧氣與當前繪制相關(負載)的陽極和陰極。一個低氧的分壓(氫)在陰極(陽極)導致氧氣(氫)流失,會損害FC或顯著降低它的壽命(楊et al。,1998)。氫氣和空氣供給必須協(xié)調(diào),以便跨膜壓差FC足夠小,防止膜損傷。以最小化電阻損失,膜很薄。所需的空氣壓力略低于氫壓力以避免空氣泄漏向陽極可以形成可燃混合物。相關的問題與氫或存儲不是本文討論的。模型、控制器和參考一個天然氣燃料處理器中可以找到,Stefanopoulou Pukrushpan,彭(2004 b)。細節(jié)使用水性硼氫化氫生成解決方案被發(fā)現(xiàn)在斯考特?阿曼德拉et al。(2000)。Jeong和Oh發(fā)現(xiàn)可以儲氫氫化(2002)。Passive FC systems such as the PEMFC used in the toy bus project, rely on convective flow with low power density. In low cost F