纳米化对热电材料优值以及器件产热和传热过程影响的机制研究

Thermoelectric generation technique has great application prospects in solar energy, industrial waste heat utilization field, etc. However, the practical applications of this technique are still limited due to its relatively low conversion efficiency. The advancement of the nanotechnology has provided new promising approaches for developing thermoelectric materials with high performance. In this study, the bulk nanostructured thermoelectric materials with different structures will be designed and prepared. By means of testing the thermoelectric properties including thermal conductivity, power factor, and figure of merit, etc., combining with the further microstructure characterization, the influencing mechanism of nano scale effect on the performance of thermal and electrical transport will be explored. The devices based on the as prepared nanostructured thermoelectric materials will be fabricated. The heat generation processes including Thompson effect, Peltier effect, and Joule effect and heat transfer in the devices under different working conditions will be investigated. The influence of the nano scale on the coupling relation between the heat generation and heat transfer and the temperature distribution inside the thermoelectric devices will be clarified. By analyzing the correlation of the nanosize and interface on the transport and conversion processes of the energy carriers including electron and phonon etc., the affecting mechanism of nano scale on the figure of merit of thermoelectric materials, heat generation and heat transfer in the devices, and thermoelectric conversion performance will be established. The approaches for synergistically optimizing the thermoelectric conversion performance will be explored. These studies are aimed to provide theoretical guidance and technical approaches for optimally designing and manufacturing nanostructured thermoelectric materials with high performance. Also the scientific basis for utilizing the devices based on the nanostructured thermoelectric materials will be provided.

热电发电技术在太阳能、工业余废热利用等领域应用潜力巨大，但因其转换效率较低，限制了该技术的实际推广。纳米技术的发展为提高热电性能开辟了新的途径。本项目拟设计制备具有不同纳米结构的纳米化块体热电材料，通过测试分析热导率、功率因子和优值系数等性能，结合微结构表征，探明纳米化对热输运和电输运性能的影响机制。进一步构建基于纳米热电材料的器件，研究不同工作条件下器件内汤姆逊热、帕尔贴热、焦耳热等产热效应以及传热过程，厘清纳米化对热电器件内部产热和传热与其温度分布之间耦合关系的影响。分析纳米尺度、界面等结构特性与电子、声子等能量载流子输运及转换过程的关联，建立纳米化对热电材料优值系数、器件产热和传热以及热电转换性能的作用机制，探寻协同优化热电转换性能的方法。旨在为优化设计高性能纳米热电材料提供理论指导和技术途径，同时为基于纳米热电材料的器件的应用提供必要的基础性科学依据。

热电发电技术在太阳能、工业余废热利用等领域应用潜力巨大，但因其转换效率较低，限制了该技术的实际推广。纳米技术的发展为提高热电性能开辟了新的途径。通过掺杂和纳米化方式，增加热电材料内声子散射，降低热导率的同时，优化载流子浓度和迁移率，提升了热电材料的优值系数。分析了结构特性对纳米热电材料热导率、功率因子以及优值系数等的影响规律，探索了通过纳米化提高热电优值的有效途径。研究了Thomson效应对热电发电器件性能的影响，形成了Seeback效应与温度的对应关系对热电器件产热效应的不同影响规律，为协同优化热电优值和器件内部产热效应奠定了基础。研究了热电腿与冷热端界面热阻的匹配关系对TEG性能的影响。形成了TEG的输出功率和转换效率随界面总热阻的变化趋势。分析了P型热电材料腿与冷热端的接触热阻和N型热电材料腿与冷热端的接触热阻匹配度对热电器件的输出功率和转换效率的影响规律。总结出了优化P型热电材料腿与冷热端界面的热阻和N型热电材料腿与冷热端界面的热阻的匹配度有效提高TEG的性能的技术途径。进一步研究了热电器的输出功率和转换效率随器件位形、尺寸、排列方式等持续改变而变化的规律，为优化设计热电器件提供了新思路。同时研究了冷热端换热能力对热电发电性能和稳定性的影响，探寻了提高冷端的换热能力、降低冷端温度进而提高热电发电系统效率的基本途径。开发了提高冷端换热能力的技术路径，分析了提升热端换热和储热能力的基本方法。分析了各因素对热电性能的影响规律，形成了协同调控多因素提升器件性能的基本原则。为优化设计高性能纳米热电材料提供理论指导和技术途径，同时为基于纳米热电材料的器件的应用提供必要的基础性科学依据。