Utilizing the heat energy of exhaust gases is a promising application of thermoelectric generator (TEG), which can convert low grade thermal energy into electricity. The annular thermoelectric generator (ATEG) is thought to be much more feasible for cylindrical heat source compared to the flat-plate thermoelectric generator (FTEG) in reference to the compatibility. Nevertheless, the quantitative comparison is lacking to clarify the prevalent geometry of TEG for cylindrical heat source. In this work, the performances of ATEG and FTEG are compared in detail with varying inlet temperature, velocity and the convective heat transfer coefficient when cylindrical heat source is applied. The turbulent heat source is described by the standard - functions together with the two-equation heat transfer model, while the output power and conversion efficiency of the ATEG and FTEG are calculated by solving the coupled thermo-electric equations. Our results showed that the output powers and the conversion efficiencies of ATEG and FTEG both increase with the increase of the inlet velocity, temperature, and the convective heat transfer coefficient. The conversion efficiency of ATEG is always higher than that of FTEG. The conversion efficiency of ATEG becomes even larger than that of FTEG when inlet temperature and/or convective heat transfer coefficient are relatively larger. In contrast, the output power of ATEG has no obvious difference with that of FTEG. This study addressed the condition when the ATEG has obvious advantage compared to the FTEG with cylindrical heat source applied. Our results suggest the annular TEG is better choice for cylindrical hot source especially when the inlet temperature and/or convective heat transfer coefficient are relatively larger. It could be a helpful guide for choosing suitable geometry of TEGs for energy harvesting in complex condition.

中文翻译：

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圆柱形热源环形与平板温差发电器性能比较

利用废气的热能是热电发电机（TEG）的一个有前途的应用，它可以将低品位热能转化为电能。就兼容性而言，与平板热电发电机（FTEG）相比，环形热电发电机（ATEG）被认为对于圆柱形热源更可行。然而，缺乏定量比较来阐明圆柱形热源 TEG 的普遍几何形状。在这项工作中，当应用圆柱形热源时，ATEG 和 FTEG 的性能在不同的入口温度、速度和对流换热系数下进行了详细比较。湍流热源由标准函数和二方程传热模型描述，而ATEG和FTEG的输出功率和转换效率通过求解耦合热电方程计算。我们的结果表明，ATEG 和 FTEG 的输出功率和转换效率均随着入口速度、温度和对流传热系数的增加而增加。ATEG的转换效率始终高于FTEG。当入口温度和/或对流传热系数相对较大时，ATEG的转换效率甚至变得比FTEG更大。相比之下，ATEG的输出功率与FTEG没有明显差异。本研究解决了ATEG与采用圆柱形热源的FTEG相比具有明显优势的情况。我们的结果表明，环形 TEG 是圆柱形热源的更好选择，尤其是当入口温度和/或对流换热系数相对较大时。它可以为选择合适的 TEG 几何形状以在复杂条件下进行能量收集提供有用的指导。