【摘要】：隨著微能源技術(shù)的迅速發(fā)展，基于微電子機(jī)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(diǎn)，具有廣闊的應(yīng)用前景。相對(duì)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(duì)此問(wèn)題，本文從陽(yáng)極多孔介質(zhì)，陽(yáng)極流道和運(yùn)行參數(shù)三個(gè)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(duì)μDMFC陽(yáng)極多孔介質(zhì)的甲醇傳質(zhì)和氣液兩相傳輸進(jìn)行了系統(tǒng)的研究；其次，結(jié)合了陽(yáng)極流場(chǎng)的微尺度效應(yīng)，采用介觀模擬方法對(duì)陽(yáng)極微流道內(nèi)的氣液兩相流動(dòng)進(jìn)行模擬，并利用高速攝像機(jī)進(jìn)行實(shí)驗(yàn)分析，從而對(duì)理論模型進(jìn)行驗(yàn)證；然后，采用響應(yīng)面分析方法研究了運(yùn)行參數(shù)對(duì)μDMFC性能和陽(yáng)極氣液兩相動(dòng)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(yáng)極自適應(yīng)供給系統(tǒng)。 μDMFC工作時(shí)，陽(yáng)極催化層產(chǎn)生的CO2首先傳輸?shù)疥?yáng)極多孔介質(zhì)區(qū)域，陽(yáng)極多孔介質(zhì)內(nèi)結(jié)構(gòu)參數(shù)的變化會(huì)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(guò)模型全面分析了陽(yáng)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(yùn)行參數(shù)對(duì)電池性能有明顯的影響；當(dāng)陽(yáng)極多孔介質(zhì)特性(親疏水，壓縮特性)變化時(shí)，對(duì)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(kuò)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(yùn)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(guò)多孔介質(zhì)傳輸?shù)疥?yáng)極流場(chǎng)后，宏觀流動(dòng)下可以忽略的微尺度效應(yīng)變得越發(fā)明顯。針對(duì)此問(wèn)題，結(jié)合介觀分析理論，利用晶格-波爾茲曼方法對(duì)μDMFC陽(yáng)極流場(chǎng)內(nèi)部的主要微尺度效應(yīng)進(jìn)行分析，研究了截面效應(yīng)，親疏水效應(yīng)對(duì)微流道內(nèi)氣液兩相流運(yùn)動(dòng)過(guò)程及電池性能的影響。仿真結(jié)果表明：相對(duì)于傳統(tǒng)結(jié)構(gòu)，長(zhǎng)寬比為2:1的親水微流道對(duì)CO2的運(yùn)動(dòng)具有明顯的優(yōu)勢(shì)；為了驗(yàn)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(jìn)行測(cè)試。實(shí)驗(yàn)結(jié)果表明：陽(yáng)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?yàn)棣藾MFC陽(yáng)極流道內(nèi)部的微尺度效應(yīng)研究提供依據(jù)。 μDMFC工作時(shí)所對(duì)應(yīng)的運(yùn)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(huì)影響μDMFC的輸出性能。針對(duì)這一問(wèn)題，采用響應(yīng)面分析方法研究了運(yùn)行參數(shù)對(duì)電池性能和CO2動(dòng)態(tài)運(yùn)動(dòng)的影響，輸入變量為甲醇濃度，陽(yáng)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(kāi)路電壓，通過(guò)測(cè)試數(shù)據(jù)對(duì)響應(yīng)面分析的參數(shù)進(jìn)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(yùn)行參數(shù)對(duì)電池特性的影響，而且可以分析不同運(yùn)行變量之間的相互交疊作用，能夠?yàn)棣藾MFC系統(tǒng)的便攜式應(yīng)用提供有效的數(shù)據(jù)支持。測(cè)試表明：陰極自呼吸式μDMFC單體在工作溫度為60℃時(shí)達(dá)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(jì)了陽(yáng)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(duì)自適應(yīng)供給模塊功能，系統(tǒng)動(dòng)態(tài)性能及穩(wěn)定性進(jìn)行了全面的測(cè)試與分析。結(jié)果表明：基于自適應(yīng)供給方式的μDMFC單體動(dòng)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?jī)H為24.075g。測(cè)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(dòng)態(tài)測(cè)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(zhǎng)時(shí)間工作，研究結(jié)果能夠?yàn)槲⑿椭苯蛹状既剂想姵叵到y(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(hào)：2436573