【摘要】：微型直接甲醇燃料電池(Micro Direct Methanol Fuel Cell)是一種具有廣闊前景的電源,具有能量轉(zhuǎn)換效率高、環(huán)境友好、室溫工作、快速加燃料以及低噪聲等顯著優(yōu)點。氣液兩相混流是影響μDMFC性能的關(guān)鍵因素之一,表現(xiàn)為陽極CO2氣泡占據(jù)流場和陰極易發(fā)生水淹等阻塞反應(yīng)物傳輸?shù)膯栴}。本文圍繞這一重要問題,在鈦基底上設(shè)計、制備了具有極端潤濕(超親水/超疏水)特性的微結(jié)構(gòu)輔助通道以實現(xiàn)氣液分流,研究了新型流場中氣液分相輸運特性及其對電池性能的影響。通過一步陽極氧化法在鈦基底上產(chǎn)生微納分級結(jié)構(gòu)表面,獲得了接觸角為0°的超親水特性的鈦基板表面。研究了不同工藝參數(shù)對超親水特性的影響,發(fā)現(xiàn)氧化電壓越高,超親水性越強；電解液溫度對超親水性的影響在不同電壓區(qū)間有不同表現(xiàn),氧化電壓為20-40V時,鈦表面的超親水性隨著電解液的溫度升高而增強,但是這種趨勢在60-80V的電壓區(qū)間發(fā)生逆轉(zhuǎn)。經(jīng)氟硅烷修飾后,超親水的氧化鈦表面變成超疏水,結(jié)果表明,本實驗獲得的超疏水鈦表面接觸角、滾動角以及接觸滯后角分別為160°、2°和1.7°。本文制備的極端潤濕表面在酸性、中性、堿性水溶液以及大氣環(huán)境下均具有良好的穩(wěn)定性。分別設(shè)計了帶超疏水排氣微通道的新型陽極流場和帶超親水排液微通道的新型陰極流場,利用ANSYS軟件計算了微通道的合理深度,結(jié)合流場開孔率等要素確定流場溝道寬度及其它結(jié)構(gòu)參數(shù)。試驗確定了具有極端潤濕微結(jié)構(gòu)的鈦基流場板微細加工工藝流程,結(jié)合光刻與濕法蝕刻技術(shù),通過陽極氧化法獲得超親水輔助溝道,再經(jīng)氟化可得到超疏水排氣通道。最后,通過二次光刻與濕法刻蝕工藝形成燃料或氧氣進給的主通道,制備出新型流場板。設(shè)計制作包含親水燃料溝道和超疏水氣體通道嵌套排布的聚碳酸酯模擬流場板,以雙氧水溶液的分解反應(yīng)模擬氣液兩相流過程,流場壓降測試結(jié)果表明,新流場中的平均壓降比參比流場減小了37%,可視化觀察表明輔助氣體通道加速了氣泡的釋放。將具有超疏水通道的新型陽極流場組裝成電池并研究其陽極流場氣液輸運特性,結(jié)果表明,在相同的電流密度下,壓降特性與可視化觀察的變化趨勢與模擬流場實驗吻合。再者,采用具有40和80μm深排氣通道兩種新陽極,其峰值功率密度分別比采用參考陽極流場的電池提高了33.3%和41.4%。新型陰極流場對μDMFC的影響測試發(fā)現(xiàn),經(jīng)長期放電后,普通點陣流場的最大功率密度減小幅度約是排液通道深度為80μm新陰極流場的2.3倍,說明新型陰極流場提高了μDMF C陰極的水管理能力。
[Abstract]:Micro direct methanol fuel cell (Micro Direct Methanol Fuel Cell) is a promising power supply with many advantages such as high energy conversion efficiency, environmental friendliness, room temperature operation, fast fueling and low noise. The gas-liquid two-phase mixing is one of the key factors affecting the performance of 渭 DMFC, which is characterized by the flow field occupied by anodic CO2 bubbles and the problems of blocking reactants such as water flooding. Around this important problem, microstructural auxiliary channels with extremely wetting (super hydrophilic / super hydrophobic) properties have been designed on titanium substrate to realize gas-liquid separation. The gas-liquid phase transport characteristics in a new flow field and their effects on the performance of the battery were studied. The surface of titanium substrate with super hydrophilic property with contact angle of 0 擄was obtained by one-step anodizing method. The influence of different process parameters on superhydrophilicity was studied. It was found that the higher the oxidation voltage, the stronger the super hydrophilicity. The effect of electrolyte temperature on superhydrophilicity is different in different voltage ranges. When the oxidation voltage is 20-40 V, the superhydrophilicity of titanium surface increases with the increase of electrolyte temperature. But this trend is reversed in the 60-80 V voltage range. After modification with fluorosilane, the surface of superhydrophilic titanium oxide becomes superhydrophobic. The results show that the contact angle, rolling angle and contact lag angle of superhydrophobic titanium surface are 160 擄, 2 擄and 1.7 擄, respectively. The extremely wetted surface prepared in this paper has good stability in acidic, neutral, alkaline aqueous solution and atmospheric environment. The new anode flow field with super hydrophobic exhaust microchannel and the new cathode flow field with super hydrophilic drain microchannel are designed respectively. The reasonable depth of microchannel is calculated by ANSYS software. The channel width and other structural parameters of the flow field are determined by combining the flow field opening rate and other factors. The micromachining process of titanium substrate flow field plate with extremely wetting microstructure was determined. The super-hydrophilic auxiliary channel was obtained by anodic oxidation combined with lithography and wet etching, and the superhydrophobic exhaust channel was obtained by fluorination. Finally, a new type of flow field plate was prepared by secondary lithography and wet etching to form the main channel of fuel or oxygen feed. A polycarbonate simulated flow field plate consisting of hydrophilic fuel channel and superhydrophobic gas channel was designed and fabricated. The decomposition reaction of hydrogen peroxide solution was used to simulate the gas-liquid two-phase flow process. The average pressure drop in the new flow field is 37% smaller than that in the reference flow field. Visual observation shows that the auxiliary gas channel accelerates the bubble release. The new anode flow field with superhydrophobic channel is assembled into a cell and the gas-liquid transport characteristics of the anode flow field are studied. The results show that the pressure drop characteristics are consistent with the simulated flow field experiments at the same current density. Furthermore, the peak power density of the new anode with 40 渭 m and 80 渭 m deep exhaust channels is increased by 33.3% and 41.4% than that of the cell with reference anode flow field, respectively. The effect of the new cathode flow field on 渭 DMFC is measured. It is found that the maximum power density of the common lattice flow field decreases by about 2.3 times than that of the new cathode flow field with 80 渭 m discharge channel depth after long-term discharge. The new cathode flow field improves the water management ability of 渭 DMF C cathode.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM911.4

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相關(guān)期刊論文 前1條

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本文編號：2386069