【摘要】：隨著微能源技術(shù)的迅速發(fā)展，基于微電子機械系統(tǒng)(Micro Electro Mechanical System，MEMS)技術(shù)的微型直接甲醇燃料電池(Micro Direct Methanol Fuel Cell，μDMFC)具有能量密度高，環(huán)保高效等優(yōu)點，具有廣闊的應(yīng)用前景。相對于傳統(tǒng)尺寸的電池，特征尺寸的減小使得μDMFC微尺度效應(yīng)在內(nèi)部氣液兩相物質(zhì)傳輸上的作用愈發(fā)明顯。針對此問題，本文從陽極多孔介質(zhì)，陽極流道和運行參數(shù)三個方面研究了μDMFC氣液兩相傳輸和輸出特性。首先，，提出了μDMFC氣液兩相三維全電池傳質(zhì)模型，對μDMFC陽極多孔介質(zhì)的甲醇傳質(zhì)和氣液兩相傳輸進行了系統(tǒng)的研究；其次，結(jié)合了陽極流場的微尺度效應(yīng)，采用介觀模擬方法對陽極微流道內(nèi)的氣液兩相流動進行模擬，并利用高速攝像機進行實驗分析，從而對理論模型進行驗證；然后，采用響應(yīng)面分析方法研究了運行參數(shù)對μDMFC性能和陽極氣液兩相動態(tài)特性的影響；最后，基于響應(yīng)面分析結(jié)果，研制了μDMFC系統(tǒng)的陽極自適應(yīng)供給系統(tǒng)。 μDMFC工作時，陽極催化層產(chǎn)生的CO2首先傳輸?shù)疥枠O多孔介質(zhì)區(qū)域，陽極多孔介質(zhì)內(nèi)結(jié)構(gòu)參數(shù)的變化會影響內(nèi)部的兩相傳輸及電池的輸出功率。因此，本文首先建立了μDMFC的全電池三維兩相傳質(zhì)模型，通過模型全面分析了陽極多孔介質(zhì)內(nèi)的甲醇傳質(zhì)和氣液兩相傳輸。仿真結(jié)果表明：甲醇濃度，工作溫度等運行參數(shù)對電池性能有明顯的影響；當(dāng)陽極多孔介質(zhì)特性(親疏水，壓縮特性)變化時，對應(yīng)區(qū)域的甲醇傳質(zhì)和氣液兩相傳輸也隨之變化，并且呈現(xiàn)一定的規(guī)律性；基于研究結(jié)果，提出一種梯度擴散層結(jié)構(gòu)，能夠有效改善兩相傳輸特性和提高電池性能輸出。以上研究結(jié)果為μDMFC運行參數(shù)的優(yōu)化研究提供了理論依據(jù)。 隨著特征尺寸的不斷減小，當(dāng)CO2經(jīng)過多孔介質(zhì)傳輸?shù)疥枠O流場后，宏觀流動下可以忽略的微尺度效應(yīng)變得越發(fā)明顯。針對此問題，結(jié)合介觀分析理論，利用晶格-波爾茲曼方法對μDMFC陽極流場內(nèi)部的主要微尺度效應(yīng)進行分析，研究了截面效應(yīng)，親疏水效應(yīng)對微流道內(nèi)氣液兩相流運動過程及電池性能的影響。仿真結(jié)果表明：相對于傳統(tǒng)結(jié)構(gòu)，長寬比為2:1的親水微流道對CO2的運動具有明顯的優(yōu)勢；為了驗證仿真結(jié)果，制備了具有不同微結(jié)構(gòu)的鋁基極板，組裝成單體電池進行測試。實驗結(jié)果表明：陽極微流道優(yōu)化后的電池性能得到明顯提升，與仿真結(jié)果相互吻合。以上研究結(jié)果能夠為μDMFC陽極流道內(nèi)部的微尺度效應(yīng)研究提供依據(jù)。 μDMFC工作時所對應(yīng)的運行參數(shù)直接影響電池內(nèi)部的氣液兩相傳輸，而且，參數(shù)之間的相互作用也會影響μDMFC的輸出性能。針對這一問題，采用響應(yīng)面分析方法研究了運行參數(shù)對電池性能和CO2動態(tài)運動的影響，輸入變量為甲醇濃度，陽極流速，電池工作溫度，輸出函數(shù)為最大輸出功率密度和開路電壓，通過測試數(shù)據(jù)對響應(yīng)面分析的參數(shù)進行訓(xùn)練，從而獲得更精確的分析結(jié)果。這種方法不僅可以表征運行參數(shù)對電池特性的影響，而且可以分析不同運行變量之間的相互交疊作用，能夠為μDMFC系統(tǒng)的便攜式應(yīng)用提供有效的數(shù)據(jù)支持。測試表明：陰極自呼吸式μDMFC單體在工作溫度為60℃時達到最大功率密度105.41mW/cm2，在室溫下最高功率密度為50.59mW/cm2。 基于響應(yīng)面分析的研究成果，提出并設(shè)計了陽極自適應(yīng)供給方式，并將其應(yīng)用于空氣自呼吸式μDMFC單體及電池組，組成便攜式應(yīng)用系統(tǒng)。對自適應(yīng)供給模塊功能，系統(tǒng)動態(tài)性能及穩(wěn)定性進行了全面的測試與分析。結(jié)果表明：基于自適應(yīng)供給方式的μDMFC單體動態(tài)特性得到明顯改善。制作的便攜式應(yīng)用電池組由6節(jié)單體組成，整體尺寸僅為13.25cm3，重量僅為24.075g。測試結(jié)果表明：優(yōu)化供給模式后的電池組具有最大的輸出功率。在此供給方式下，電池組中單池輸出均勻，在動態(tài)測試中體現(xiàn)出良好的響應(yīng)特性，并成功應(yīng)用于家用小風(fēng)扇的長時間工作，研究結(jié)果能夠為微型直接甲醇燃料電池系統(tǒng)的便攜式應(yīng)用提供有效的依據(jù)。
[Abstract]:With the rapid development of micro-energy technology, Micro Direct Methanol Fuel Cell (DMFC) based on Micro Electro Mechanical System (MEMS) technology has the advantages of high energy density, high efficiency and the like, and has wide application prospect. Compared with the traditional size cell, the reduction of the feature size makes the effect of the micro-scale effect of the. mu. DMFC on the transmission of the internal gas-liquid two-phase substance more obvious. In this paper, the gas-liquid two-phase transmission and output characteristics of the micro-DMFC are studied from the three aspects of the anode porous medium, the anode flow channel and the operating parameters. In this paper, the mass transfer model of the three-phase three-phase three-phase three-phase system for gas-liquid two-phase of the DMFC is put forward, and the methanol mass transfer and the gas-liquid two-phase transfer of the nano-DMFC anode porous medium are systematically studied. Secondly, the micro-scale effect of the anode flow field is combined. The gas-liquid two-phase flow in the anode micro-channel is simulated by a mesoscopic simulation method, and the experimental analysis is carried out by using a high-speed camera, so that the theoretical model is verified; and then, The effect of operating parameters on the dynamic characteristics of the two-phase gas-liquid two-phase was studied by means of the response surface analysis method. Finally, the self-adaptive feed system of the micro-DMFC system was developed based on the results of the response surface analysis. When the micro-DMFC is working, the CO2 generated by the anode catalyst layer is first transmitted to the anode porous medium area, and the change of the structural parameters in the anode porous medium can affect the internal two-phase transmission and the output work of the battery. In this paper, the three-dimensional model of all-cell three-dimensional (3-D) generation of the DMFC is established, and the mass transfer and gas-liquid transfer in the porous media of the anode are comprehensively analyzed through the model. The simulation results show that the operating parameters such as methanol concentration and operating temperature have a significant effect on the performance of the battery. When the characteristics of the porous medium (such as the water and the compression characteristics) of the anode change, the methanol mass transfer and the gas-liquid two-phase transmission of the corresponding region also change, and a certain rule is presented. Based on the results of the study, a gradient diffusion layer structure is proposed, which can effectively improve the two-phase transmission characteristics and improve the performance of the battery. The results of the above research provide the theoretical basis for the optimization of the operation parameters of the. According to the decrease of the feature size, the more the micro-scale effect that can be neglected in the macroscopic flow after the CO2 passes through the porous medium to the anode flow field In this paper, the main micro-scale effect in the flow field of the micro-channel is analyzed by using the lattice-Boltzmann method, and the cross-sectional effect and the affinity of the water-repellent effect on the movement of the gas-liquid two-phase flow in the micro-flow channel and the performance of the cell are studied. The simulation results show that the hydrophilic micro-channel with the aspect ratio of 2:1 has a distinct advantage over the traditional structure. In order to verify the simulation results, an aluminum-based plate with different microstructures is prepared and assembled into a single cell. The results of the experiment show that the performance of the battery after the optimization of the anode micro-flow channel is obviously improved, and the result of the simulation is similar to that of the simulation results. The results of the above study can be used to study the micro-scale effect of the micro-scale effect inside the micro-DMFC anode flow channel. The operating parameters corresponding to the operation of the. mudfc directly affect the gas-liquid two-phase transmission inside the battery, and the interaction between the parameters can also affect the mudfc. The response surface analysis method is used to study the effect of operating parameters on the performance of the battery and the dynamic motion of the CO2. The input variable is the methanol concentration, the anode flow rate, the operating temperature of the battery, and the output function is the maximum output power density. and the test data is used for training the parameters analyzed by the response surface, so that a more accurate method is obtained, The method can not only characterize the effect of the running parameters on the characteristics of the battery, but also can analyze the mutual overlapping effect between different operating variables, and can provide the portable application of the. The results show that the maximum power density is 105.41 mW/ cm2 at 60 鈩

本文編號：2436573