温差发电器非均温界面热电输运机理及尺度效应

With the improvement of high performance thermoelectric materials, the automobile exhaust temperature difference generation technology presents a good application prospect. Currently, many important achievements have been made in the research, but many are based on the assumption of the uniform temperature interface of thermoelectric generator. For the automobile exhaust heat flux has the high temperature and limited flow characteristics, in order to recover waste heat fully, the final exhaust temperature is low and the generator is bound to appear large temperature gradient in the fluid flow direction. Therefore, the thermoelectric system reflects the typical non-inform temperature interface characteristics. To reveal the internal thermoelectric coupling mechanism under non-inform temperature characteristics is the key to realize high thermoelectric conversion from exhaust gas residual heat. At present, only a few studies have focused on this feature, and only revealed the appearance characteristics with a single factor considered. The theoretical basis is lack of universality and quantization. Therefore, this topic takes the qualitative decoupling and quantitative analysis among multi-factors and multi-parameters under non-uniform temperature interface condition as the key breakthrough, to carry out the researches of thermal-electric transport characteristics and high-efficient thermoelectric conversion mechanism on basis of multiple physical quantity optimization, aimed at comprehensive reveal heat-electricity-structure coupling and improve the non-uniform temperature interface thermoelectric theory in mechanism. Research contents include thermoelectric performance analytical under multi-factor and multi-parameter coupling, temperature gradient and model criterion analysis, the internal scale effect and structure optimization theory, the performance matching of optimal “structure scale - load resistance - connecting circuit”, etc. The applicant has been engaged in thermoelectric research for many years, which can provide powerful guarantee for this research.

随着高性能热电材料的开发，汽车尾气温差发电技术展示出很好的应用前景。目前研究已取得很多重要成果，但多基于热电器均温界面假设。而实际应用中，为充分回收高温有限流尾气余热，排气温度较低，热电系统沿程上存在很大的温度梯度，由此，体现出典型非均温界面特征。揭示该特征下热电耦合机理是实现尾气余热高效热电转换的关键。目前非均温界面热电理论研究较少，且只揭示了单因素影响下的表象特征，理论依据缺乏通用性和定量化。因此，本课题以非均温界面多物理量多参数间的定性解耦和定量解析为关键突破点，展开热电输运特性和基于多物理量优化的高效热电转换机理研究，旨在全面深入揭示“热-电-结构”多场耦合作用，从机理上完善非均温界面热电理论。研究包括多因素多参数耦合下热电性能解析、温度梯度及模型判据分析、内在尺度效应及结构优化理论、最优“结构尺度-负载电阻-联接电路”性能匹配等。申请人多年热电科研经验可为本课题研究提供有力保障。

为完善基于汽车尾气余热能应用的非均温界面热电理论，本项目主要建立了双向温度梯度热电模型,并揭示了相应的热电优值尺度特征，最终提出针对高温废气余热能利用的高效热电转换理论。考虑流体沿程温度梯度，采用有限元法建立非均温界面热电器模型，分析了热阻、流阻、电流、流体物性、换热结构、热电材料之间多因素多参数耦合下热电性能，提出多因素多参数的解耦方法，并给出优化结构以及峰值功率的一般关联式。基于模拟和实验，分析基于各类不同工况的温度梯度特征，提出温度梯度量化关联式，并揭示温度梯度对热电材料温度依存性的影响，为有限元模型的科学选择给出理论判据。考虑热电偶臂方向上的温度梯度，揭示了热电模块PN结内部各类不同热边界条件对热电性能的影响，实现电偶臂结构优化，进一步基于场协同理论提出热电结构优化理论。对比分析了采用各种强化换热型式的热电器优化性能，获得内部热阻和流阻平衡点，并提出分段串段电路联接方式，揭示了非全串联电路的内在热电耦合机理。理论研究成果可为高效热电转换提供定性和定量化指导，实验研究成果可为热电器制造、热电试验台搭建以及热电性能测试等提供相关实践经验。此外，也对原项目内容作了进一步拓展和未来展望。共发表论文14篇，其中SCI检索论文7篇，EI检索论文1篇，会议论文6篇；申请国家发明专利4项，其中授权2项。完成了任务书的既定目标。