A novel 24-h day-night operational solar thermoelectric generator using phase change materials

Abstract

To improve the energy matrix using solar energy, the intermittency and variation of the solar resource must be resolved for effective implementation of solar operated electricity generation systems. Solar thermoelectric generators (STEG) can be used for electricity generation in non-grid and grid connected applications. However, to use the STEG systems extensively, the limitations of lower conversion efficiency of around 7%, effective passive thermal management of the thermoelectric generator (TEG) and storage of residual heat of the thermoelectric generator need to be solved. In this study, a conceptual theoretical model of latent heat storage and cooling system (LHSCS) is proposed for the effective thermal management and enhanced electricity generation from the solar thermoelectric generator. The numerical model of the proposed system has been developed in COMSOL Multiphysics software for the climatic conditions of the Atacama Desert, Chile. The effect of phase change material (PCM) volume, heat sink and container geometry on the performance of the system has been studied. It is found that the desert locations are the best geographical locations for operating the solar thermoelectric generator coupled latent heat storage and cooling system due to higher solar radiation resource and favorable environmental conditions. The results showed that with 6 kg of phase change material, a temperature difference of 120 °C has been achieved between the hot and cold sides of the thermoelectric generator without using an active cooling system and the stored residual heat in phase change material generated 0.6% more electricity during the off-sunshine hours. Further, it has been found that the natural convection has a relevant impact on the melting of the phase change material and must be considered in the designing of a latent heat container. This proposed numerical model can be used to demonstrate the solar thermoelectric generator coupled latent heat storage and cooling system for any geographical location.