Concentrated solar thermoelectric power generator equipped with a novel ultrathin wet porous membrane cooling technique; experimental study

Abstract

One side of any thermoelectric power generator (TEG) is hot while the other side should always stay cold. The higher the temperature difference, the greater the power generation. This paper offers a particular ultrathin wet porous membrane (UWPM) as a new cooling method for a solar thermoelectric power generator. According to the graphical abstract, the membrane has a capillary-wicking feature on one side, making it possible to be soaked spontaneously and create a steady thin water film on the ceramic layer of the thermoelectric, thereby serving as an energy-free, enthalpy of vaporization-based cooling method (surface vaporization). Interestingly, water is replenished spontaneously as long as the water exists in the tank. The suggested mechanism is tested under two weather conditions: one hot, dry day (ambient air around 40 °C) and one moderate day (ambient air around 30 °C) with different air speeds between 1.5 and 4.5 m/s to simulate different wind speeds in real applications. Power, cold side surface temperature, maximum conversion efficiency, etc., are measured, evaluated, discussed, and compared with the common fin-pin heatsink/fan thermal management tool. Notably, the implementation of the UWPM demonstrates a substantial enhancement in thermoelectric generator performance. It is noted that the lowest temperature that can be obtained through vaporization can be colder than ambient air temperature, approaching the wet-bulb temperature. The UWPM keeps the cold side temperature up to 10 degrees colder than that achieved in the heatsink method. This is why the generated power by the TEG is around 2.5 times higher when utilizing the UWPM. Furthermore, unlike the fin-pin heatsink (FPH) thermal management tool, warmer weather conditions do not diminish the cooling quality of the UWPM method. Indeed, the cold side temperature on a hot, dry day is almost the same as that on a moderate day using the UWPM technique. This is because hot ambient temperature induces greater and easier vaporization, leading to a higher cooling effect.