质子交换膜燃料电池装配力学及其对性能影响的研究
发布时间：2019-04-18 22:19
【摘要】：质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell,PEMFC)是一种通过电化学反应将燃料的化学能直接转化成电能的能源转换装置,由于其燃料来源广泛、清洁无污染、工作电流大和常温下启动快等优点,被认为是最有发展前景的清洁能源转换装置之一。PEMFC各组件之间需要通过从外部施加压力进行组装,由于气体扩散层(Gas Diffusion Layer,GDL)为多孔结构且弹性模量相对较小,施加压力时,若装配压力过大,会造成GDL的过度变形甚至是不可逆的破坏,导致气体传输通道减小,传质阻力增加,同时也可能会损坏燃料电池部件,缩短使用寿命;相反,若装配压力过小,会因为双极板与GDL之间接触不良,导致接触电阻增大,使燃料电池的工作效率降低,且不能保证气体的密封性,燃料气体存在泄漏的危险。本文采用数值模拟的方法,对不同装配压力下GDL的变形进行模拟,并对由装配压力引起的GDL孔隙率、渗透率等传输参数的变化及其对PEMFC性能的影响进行深入研究,以期得到最佳装配压力,使得燃料电池性能最优。论文主要工作和成果如下:建立单通道PEMFC几何模型,采用数值模拟的方法进行仿真计算,并参考经验公式分别计算单通道PEMFC在不同装配压力下孔隙率、渗透率等传输参数和接触电阻的变化。当装配压力为0-3.0 MPa时,孔隙率从初始值0.78下降到0.38左右;渗透率也发生了一个数量级之多的变化;虽然接触电阻随着装配压力的增加不断减小,但电阻减小的幅度在逐渐降低;采用有限元分析法(Finite Element Analysis,FEA)分析不同装配压力对GDL变形的影响。研究结果显示,在不同装配压力的作用下,位于双极板两侧脊部下方的GDL会发生不同程度的变形,两侧变形情况相似且明显,而且变形程度随着装配压力的增加而变大,但位于流道下方的GDL则几乎没有变化,且GDL在X轴方向上的孔隙率随装配压力的变化趋势与GDL的形变趋势相近;通过模拟仿真,分析比较不同装配压力下单通道PEMFC阴、阳极流道内组分浓度的分布状况以及各装配压力下的极化曲线。由于流道内的反应气体在催化层(Catalyst Layer,CL)中会发生化学反应,因此在不同装配压力下气体浓度均沿着流动方向减小。对于极化曲线而言,当装配压力为0.5-1.0 MPa时,相同工作电压下,单通道PEMFC的电流密度大于其他压力下的情况,且该装配压力下单通道PEMFC的功率最高。因此,当装配压力为0.5-1.0 MPa时,单通道PEMFC的性能最优。
[Abstract]:Proton exchange membrane fuel cell (Proton Exchange Membrane Fuel Cell,PEMFC) is an energy conversion device that converts the chemical energy of fuel directly into electric energy by electrochemical reaction. Because of its wide source of fuel, it is clean and non-polluting. The advantages of large working current and fast start-up at room temperature are considered to be the most promising clean energy conversion devices. The components of PEMFC need to be assembled by applying pressure from the outside, because of the gas diffusion layer (Gas Diffusion Layer,. GDL) is a porous structure with relatively small elastic modulus. If the assembly pressure is too large, it will cause the excessive deformation or irreversible destruction of GDL, resulting in the reduction of the gas transport channel and the increase of mass transfer resistance. At the same time may also damage fuel cell components, shorten the service life; On the contrary, if the assembly pressure is too low, the contact resistance will increase due to the poor contact between the bipolar plate and the GDL, and the working efficiency of the fuel cell will be decreased, and the sealing property of the gas will not be guaranteed, and the leakage of the fuel gas will occur. In this paper, the deformation of GDL under different assembly pressures is simulated by numerical simulation method, and the change of transmission parameters such as porosity and permeability of GDL caused by assembly pressure and its influence on the performance of PEMFC are deeply studied. In order to obtain the optimal assembly pressure, the fuel cell performance is the best. The main work and achievements of this paper are as follows: the geometric model of single-channel PEMFC is established, and the porosity of single-channel PEMFC under different assembly pressures is calculated by means of numerical simulation, and the porosity of single-channel PEMFC under different assembly pressures is calculated according to the empirical formula. Changes in transmission parameters such as permeability and contact resistance. When the assembly pressure is 0 / 3.0 MPa, the porosity decreases from the initial value of 0.78 to about 0.38, and the permeability changes as much as an order of magnitude. Although the contact resistance decreases with the increase of assembly pressure, the extent of resistance decrease gradually. Finite element analysis (Finite Element Analysis,FEA) is used to analyze the effect of different assembly pressure on the deformation of GDL. The results show that under different assembly pressure, the deformation of GDL under the ridge of bipolar plate is similar and obvious, and the degree of deformation increases with the increase of assembly pressure, and the deformation of the two sides is similar and obvious, and the deformation degree increases with the increase of assembly pressure, and the deformation of the two sides is similar and obvious with the increase of assembly pressure. However, the GDL under the channel has almost no change, and the porosity of GDL in the direction of X-axis is similar to that of GDL in the direction of assembly pressure. Through simulation, the distribution of component concentration in PEMFC negative and anode channels and polarization curves under different assembly pressures were analyzed and compared. Because the reaction gas in the channel will react in the catalytic layer (Catalyst Layer,CL), the gas concentration decreases along the flow direction at different assembly pressures. As far as the polarization curve is concerned, when the assembly pressure is 0.5 MPa, the current density of the single channel PEMFC is higher than that of the other pressure at the same operating voltage, and the assembly pressure sends out the highest power of the order channel PEMFC. Therefore, when the assembly pressure is 0.5 / 1.0 MPa, the performance of single channel PEMFC is the best.
【学位授予单位】：浙江科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4
本文编号：2460338
[Abstract]:Proton exchange membrane fuel cell (Proton Exchange Membrane Fuel Cell,PEMFC) is an energy conversion device that converts the chemical energy of fuel directly into electric energy by electrochemical reaction. Because of its wide source of fuel, it is clean and non-polluting. The advantages of large working current and fast start-up at room temperature are considered to be the most promising clean energy conversion devices. The components of PEMFC need to be assembled by applying pressure from the outside, because of the gas diffusion layer (Gas Diffusion Layer,. GDL) is a porous structure with relatively small elastic modulus. If the assembly pressure is too large, it will cause the excessive deformation or irreversible destruction of GDL, resulting in the reduction of the gas transport channel and the increase of mass transfer resistance. At the same time may also damage fuel cell components, shorten the service life; On the contrary, if the assembly pressure is too low, the contact resistance will increase due to the poor contact between the bipolar plate and the GDL, and the working efficiency of the fuel cell will be decreased, and the sealing property of the gas will not be guaranteed, and the leakage of the fuel gas will occur. In this paper, the deformation of GDL under different assembly pressures is simulated by numerical simulation method, and the change of transmission parameters such as porosity and permeability of GDL caused by assembly pressure and its influence on the performance of PEMFC are deeply studied. In order to obtain the optimal assembly pressure, the fuel cell performance is the best. The main work and achievements of this paper are as follows: the geometric model of single-channel PEMFC is established, and the porosity of single-channel PEMFC under different assembly pressures is calculated by means of numerical simulation, and the porosity of single-channel PEMFC under different assembly pressures is calculated according to the empirical formula. Changes in transmission parameters such as permeability and contact resistance. When the assembly pressure is 0 / 3.0 MPa, the porosity decreases from the initial value of 0.78 to about 0.38, and the permeability changes as much as an order of magnitude. Although the contact resistance decreases with the increase of assembly pressure, the extent of resistance decrease gradually. Finite element analysis (Finite Element Analysis,FEA) is used to analyze the effect of different assembly pressure on the deformation of GDL. The results show that under different assembly pressure, the deformation of GDL under the ridge of bipolar plate is similar and obvious, and the degree of deformation increases with the increase of assembly pressure, and the deformation of the two sides is similar and obvious, and the deformation degree increases with the increase of assembly pressure, and the deformation of the two sides is similar and obvious with the increase of assembly pressure. However, the GDL under the channel has almost no change, and the porosity of GDL in the direction of X-axis is similar to that of GDL in the direction of assembly pressure. Through simulation, the distribution of component concentration in PEMFC negative and anode channels and polarization curves under different assembly pressures were analyzed and compared. Because the reaction gas in the channel will react in the catalytic layer (Catalyst Layer,CL), the gas concentration decreases along the flow direction at different assembly pressures. As far as the polarization curve is concerned, when the assembly pressure is 0.5 MPa, the current density of the single channel PEMFC is higher than that of the other pressure at the same operating voltage, and the assembly pressure sends out the highest power of the order channel PEMFC. Therefore, when the assembly pressure is 0.5 / 1.0 MPa, the performance of single channel PEMFC is the best.
【学位授予单位】：浙江科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4
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