多孔薄膜电极内传热传质机理及对Na-AMTEC电特性的影响

It is of both scientific and practical importance to make studies on how the microstructure,the heat and mass transfer characteristics of the porous thin film electrode influence the electrode performance and the thermal-to-electric converting efficiency of Na-AMTEC..The porous thin film electrodes with different microstructures (the thickness of 2-10μm and the average aperture of 20-100nm) are made by the magnetron sputtering technique in this project, and the electrode microstructure is measured by the scanning probe microscope. UBI-QEP and DCV-GCMD are used to calculate the average surface activity of the porous thin film electrodes and sodium atomic diffusion trace on or in the thin film surface, respectively. Some microstructures characteristics, which can promote heat and mass transfer enhancements of the porous thin film electrodes, are selected based on theoretical study. The electrical output performances of Na-AMTEC with different electrode microstructures are tested and the heat and mass transfer mechanism of the porous thin film electrodes are understood. At the same time, the effect of the electrode microstructures on the electrical output performance and the thermal-to-electric converting efficiency of Na-AMTEC are also obtained. Finally, optimum microstructure of the porous thin film electrode should be achieved to meet the purpose of decrease of polarizing overvoltage and improvement of the thermal-to-electric converting efficiency of Na-AMTEC.

多孔薄膜电极的微观形貌特征及其内部传热传质特性对Na-AMTEC的电极性能及其热电转换效率有重要影响，开展相关研究有重要科学意义与实用价值。.本项目拟采用磁控溅射技术制备厚2-10μm、平均孔径20-100nm具有不同形貌特征的多孔薄膜电极，利用扫描探针显微镜监测多孔薄膜电极表面形貌；结合单位键指标-二次指数势方法（UBI-QEP）及双控制区域巨正则分子动力学法（DCV-GCMD）分别计算多孔薄膜表面的平均活性及多孔薄膜表面及孔隙中钠原子的扩散轨迹，从理论上选择出有利于强化传热传质形貌特征的多孔薄膜。测试不同形貌特征多孔薄膜电极对Na-AMTEC电输出特性，掌握多孔薄膜电极的传热传质机理及其对Na-AMTEC电输出特性和热电转换效率的影响规律，得到具有最佳形貌特征的多孔薄膜电极，最终达到减小电极过电压并提高Na-AMTEC热电转换效率的目的。

AMTEC是一种能够直接将热能转化为电能的装置，具有无运动部件、无噪声及与温度在900K-1200K的热源随意结合的优点，而且其热电转化效率在30%以上，对于能源高效利用和节能环保具有重要意义。. 本项目以AMTEC中多孔薄膜电极为研究对象，研究其制作工艺及其微观形貌特征对内部传热传质特性的影响，进而研究其电学性能，这对于AMTEC的利用具有有重要科学意义与实用价值。项目采用磁控溅射及丝网印刷法对TiN多孔薄膜电极进行了制备，得到了具有不同形貌特征和厚度的TiN多孔薄膜电极；项目利用混联模型对于多孔薄膜电极的热传导进行了模拟研究；最后对所得到了不同的多孔薄膜电极的方阻进行了测试计算，研究了其电性能。. 研究发现，在采用磁控溅射方法制备电极时，溅射电压及时间对所得薄膜电极的质量影响较大；采用丝网印刷法制备电极时淡化时间和温度对电极质量影响较大。通过本项目的研究，从理论上选择出有利于强化传热传质形貌特征的多孔薄膜，掌握多孔薄膜电极的热传导规律以及其电性能。