Enhanced thermoelectric waste heat recovery power generation through an innovative energy-free cooling strategy for the heatsink side

This research investigates the performance of a waste heat recovery thermoelectric generator (TEG) designed to enhance power generation through a novel energy-free cooling technique. While one side of the TEG is in contact with hot waste fluid, the other side must be effectively cooled to maximize the temperature differential and thus power output. An innovative method of creating a continuous, extra-thin water film (approximately 0.1 mm) on the TEG surface is introduced, leveraging the enthalpy of vaporization for significant cooling in which the evaporated water is replenish spontaneously meaning no need for external power. This is achieved using an ultrathin hydrophilic self-wicking sheet (UHSS) consisting of a polyvinyl chloride layer, 0.1 mm thick, coated on one side with a micro-sized wool layer to enhance hydrophilicity. When UHSS is immersed in water, the water rises vertically along the coated side due to capillary action, leading to a uniformly very thin wet surface. The other non-hydrophilic dry side is attached to the TEG surface. The idea is examined under various hot side fluid temperatures (55, 65, and 75 °C) and cold side ambient air temperatures (20, 30, and 40 °C), and compared with the conventional heatsink/fan cooling method. Experimental results indicate that the UHSS technique leads to a substantial increase in generated electrical current compared to lower values for conventional heatsink-fan methods, particularly at higher ambient temperatures. The cooling performance of the UHSS was consistently superior, yielding power output improvements of 50 %–150 % compared to common fan-heatsink. Additionally, the maximum conversion efficiency for the UHSS method ranged from 4 % to 6 %, exceeding the 1 %–4 % efficiency observed for the heatsink method. These findings highlight the UHSS technique's potential as an effective cooling strategy for thermoelectric power generators, especially in environments with high ambient temperatures and low humidity. • Ultrathin hydrophilic self-wicking sheet is tested as a cooling way for TEG. • A very thin layer of water is spread on the cold side by natural wicking. • No external power is required is this new idea to distribute the water. • The idea was tested under various heat source temperatures and air temperature. • 50–150 % more generated ampere was observed compred to the heatsink/fan method.