微型直接甲醇燃料电池阳极气液两相流研究
发布时间：2019-03-07 23:50
【摘要】：随着微能源技术的迅速发展，基于微电子机械系统(Micro Electro Mechanical System，MEMS)技术的微型直接甲醇燃料电池(Micro Direct Methanol Fuel Cell，μDMFC)具有能量密度高，环保高效等优点，具有广阔的应用前景。相对于传统尺寸的电池，特征尺寸的减小使得μDMFC微尺度效应在内部气液两相物质传输上的作用愈发明显。针对此问题，本文从阳极多孔介质，阳极流道和运行参数三个方面研究了μDMFC气液两相传输和输出特性。首先，，提出了μDMFC气液两相三维全电池传质模型，对μDMFC阳极多孔介质的甲醇传质和气液两相传输进行了系统的研究；其次，结合了阳极流场的微尺度效应，采用介观模拟方法对阳极微流道内的气液两相流动进行模拟，并利用高速摄像机进行实验分析，从而对理论模型进行验证；然后，采用响应面分析方法研究了运行参数对μDMFC性能和阳极气液两相动态特性的影响；最后，基于响应面分析结果，研制了μDMFC系统的阳极自适应供给系统。 μDMFC工作时，阳极催化层产生的CO2首先传输到阳极多孔介质区域，阳极多孔介质内结构参数的变化会影响内部的两相传输及电池的输出功率。因此，本文首先建立了μDMFC的全电池三维两相传质模型，通过模型全面分析了阳极多孔介质内的甲醇传质和气液两相传输。仿真结果表明：甲醇浓度，工作温度等运行参数对电池性能有明显的影响；当阳极多孔介质特性(亲疏水，压缩特性)变化时，对应区域的甲醇传质和气液两相传输也随之变化，并且呈现一定的规律性；基于研究结果，提出一种梯度扩散层结构，能够有效改善两相传输特性和提高电池性能输出。以上研究结果为μDMFC运行参数的优化研究提供了理论依据。 随着特征尺寸的不断减小，当CO2经过多孔介质传输到阳极流场后，宏观流动下可以忽略的微尺度效应变得越发明显。针对此问题，结合介观分析理论，利用晶格-波尔兹曼方法对μDMFC阳极流场内部的主要微尺度效应进行分析，研究了截面效应，亲疏水效应对微流道内气液两相流运动过程及电池性能的影响。仿真结果表明：相对于传统结构，长宽比为2:1的亲水微流道对CO2的运动具有明显的优势；为了验证仿真结果，制备了具有不同微结构的铝基极板，组装成单体电池进行测试。实验结果表明：阳极微流道优化后的电池性能得到明显提升，与仿真结果相互吻合。以上研究结果能够为μDMFC阳极流道内部的微尺度效应研究提供依据。 μDMFC工作时所对应的运行参数直接影响电池内部的气液两相传输，而且，参数之间的相互作用也会影响μDMFC的输出性能。针对这一问题，采用响应面分析方法研究了运行参数对电池性能和CO2动态运动的影响，输入变量为甲醇浓度，阳极流速，电池工作温度，输出函数为最大输出功率密度和开路电压，通过测试数据对响应面分析的参数进行训练，从而获得更精确的分析结果。这种方法不仅可以表征运行参数对电池特性的影响，而且可以分析不同运行变量之间的相互交叠作用，能够为μDMFC系统的便携式应用提供有效的数据支持。测试表明：阴极自呼吸式μDMFC单体在工作温度为60℃时达到最大功率密度105.41mW/cm2，在室温下最高功率密度为50.59mW/cm2。 基于响应面分析的研究成果，提出并设计了阳极自适应供给方式，并将其应用于空气自呼吸式μDMFC单体及电池组，组成便携式应用系统。对自适应供给模块功能，系统动态性能及稳定性进行了全面的测试与分析。结果表明：基于自适应供给方式的μDMFC单体动态特性得到明显改善。制作的便携式应用电池组由6节单体组成，整体尺寸仅为13.25cm3，重量仅为24.075g。测试结果表明：优化供给模式后的电池组具有最大的输出功率。在此供给方式下，电池组中单池输出均匀，在动态测试中体现出良好的响应特性，并成功应用于家用小风扇的长时间工作，研究结果能够为微型直接甲醇燃料电池系统的便携式应用提供有效的依据。
[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
本文编号：2436573
[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
本文编号：2436573
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