圆柱形热集中器理论、仿真和实现

Cylindrical thermal concentrator: theory, simulation,and implement

作为一种高效的热能收集与俘获技术,热集中器最近引起了研究者的关注.本文从热传导方程和坐标变换关系出发,导出了圆柱形热集中器温度分布的解析表达式,并通过与COMSOL数值仿真结果比较证实了表达式的正确性.分析了热集中器性能与材料各向异性和器件几何结构二者之间的联系,结果表明,包层热超材料的各向异性越大,集中器的热集中性能越好;包层与内核的半径比越大,集中器的热聚焦能力越强.利用包层与背景媒质之间的温度关系,进一步研究了用常规材料实现热集中器的方法,通过将两种常见的天然材料沿角向按周期交替排列并调整各自面积的大小,可观察到不同程度热集中现象.

As a kind of ultra-efficient thermal energy harvesting cell, thermal c.oncentrator has recently attracted great attention from researchers. An analytical expression which describes the temperature distribution in the concentrator is deduced from the heat conduction equation and coordinate transformation relations. The expression is validated by numerical experiments based on COMSOL. Influence of the anisotropy due to cladding and device geometry on the performance of the thermal concentrator is analyzed. It is demonstrated that the greater the anisotropy, the better the thermal concentration effect. Besides, increasing the aspect ratio between the cladding and the core radius also gives rise to a better performance. Based on the temperature distribution relations between the core and the background region, we further explore a method to practically realize such a thermal concentrator by using naturally available materials. It is suggested that different levels of thermal concentration can be achieved by arranging alternately two isotropic conductivities along the azimuth direction and tuning their thermal localizations respectively.