Recent development in structural designs and thermal enhancement technologies of thermoelectric generator with different types of heat sources: A review

The thermoelectric generator (TEG) as a noise-free, pollution-free and environmentally friendly energy-conversion device has been intensively investigated in the last few decades. For different TEG applications, the characteristics of their heat sources determine the structural designs of the TEG systems. In this work, we categorized TEG heat sources into three types: body heat, natural sources of heat energy, and industrial waste heat. The up-to-date three maim structural designs of wearable TEGs including film TEG, micro-bulk TEG, and yarn TEG were reviewed. For TEG using natural heat sources, the major structural designs of TEG using solar energy, geothermal energy, and ambient heat energy were summarized. In terms of TEG using industrial waste heat, the structures of TEG systems applied in automotive, household stoves, and factories were concluded. Meanwhile, key thermal enhancement technologies including different heat exchangers, heat pipes, and phase change material (PCM) to improve the performance of these TEG systems, as well as challenges of each TEG system were also concluded. This review is expected to provide inspiration for the structural designs of TEG systems with different types of heat sources and to offer potential performance enhancement technologies for engineers and researchers in this field.