Modified phase change materials used for thermal management of a novel solar thermoelectric generator

Abstract

How to produce electricity safely and without pollution is an important issue to our world. The solar thermoelectric generator can realize direct solar­electric energy conversion. However, the output power of the traditional solar thermoelectric generator is instability because of the instantaneity of the solar energy. In this paper, the paraffin/expanded graphite phase change materials were used in the solar thermoelectric generator to realize the thermal management of the solar energy. Expanded graphite improves the thermal conductivity and the anti-leakage ability of the paraffin; therefore, the prepared phase change materials have higher thermal response speed and wider application than the pure paraffin. As a result, when the temperatures of the phase change materials with different melting points (50 °C, 60 °C, 70 °C, and 80 °C) enter their own phase transition regions, the open circuit voltages of the corresponding systems also enter the stable output platforms. This verifies the excellent thermal management performance of the phase change materials on solar thermoelectric generator. In addition, the output voltage is considerable and the maximum value is 2.697 V for 80 °C PCMs. When the solar irradiation disappears, the latent heat of paraffin can still keep the system operating. Meanwhile, a mathematical model with high accuracy was also proposed.