Comprehensive review in waste heat recovery in different thermal energy-consuming processes using thermoelectric generators for electrical power generation

This paper presents a comprehensive review of recent studies in electrical power generation from various thermal-consuming processes. In particular, the paper concentrates on TEG technology in recovering waste heat from industrial applications such as chimneys and automotive engines. Studies conclude that TEGs have a lower conversion efficiency (ranging between 5% and 10%), leading to low power output. Also, they state that most of the available TEGs have low operating temperatures limiting their commercial use. Therefore, an effort is taken to understand the key parameters that influence the performance of a thermoelectric generator. It is shown that a large temperature difference across the module, high heat dissipation from the cold side of the TEG and using thermoelectric materials with a high figure of merit generally improve the performance of the thermoelectric generator system. TEG module's cold-side temperature has a large effect on the power output than the hot-side temperature. Several geometric optimization methods, such as flaps and heat spreaders under natural convection resulted in a 129% and 42% increase in TEG power output, respectively. The survey also shows that forced cooling using side-mounted fans produces 58.6% more power compared to the top-mounted fan on the heat sink. However, optimization in fan selection is required to ensure that the power produced by forced cooling is sufficient to run the fans and output higher than the natural convection cooling case. Several studies also show that most of the commercially available TEG modules made from Bismuth telluride suffer from low operating temperature (maximum of 2600 C) and have figure of merit of 1.2 maximum and low conversion efficiency (up to 5%). Recommendations are made to further research alternatives like SiGe alloys, clathrates, skutterudites, and complementary metal-oxide semiconductors with better temperature ranges and figures of merit. (C)& nbsp;2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.