Numerical analysis of a solar driven thermoelectric generator brick with phase change materials: Performance evaluation and parametric investigations

Thermoelectric generator (TEG) integrated with phase change material (PCM) has attracted increasingly wide attentions in the past few years, such as PCM applied on the hot side to stabilize the temperature fluctuations or applied on the cold side to strengthen the heat dissipation. However, the dynamic characteristics and energy conversion potential of TEG with PCM on both sides have not been systematically investigated, especially in low carbon buildings. In the present work, a three-dimensional model of an innovative solar thermoelectric generator brick with double phase change materials (STEGB-DPCM) applied on the hot and cold sides simultaneously has been conducted, aiming to identify the energy conservation potential of the proposed system. This study is carried out with variable solar radiations, convective heat transfer coefficients and PCM thicknesses to illustrate the mechanism of different parameters on the STEGB-PCM from multiple indicators, including temperature difference, output power, energy and exergy efficiencies, and heat flux. Furthermore, the performance of STEGBDPCM has been compared with solar thermoelectric generator brick with PCM on the hot side or cold side (STEGB-HPCM or STEGB-CPCM) and solar thermoelectric generator brick without PCM (STEGB). The results show that the output power of STEGB-DPCM can be enhanced by 138.5% for solar radiation of 600-1000 W/m2. Meanwhile, the energy and exergy efficiencies of STEGB-DPCM are positive in proportion to the convective heat transfer coefficient with the energy efficiency of 0.113% and exergy efficiency of 0.122% at 3600 s for h = 15 W/ (m2 K). Although the output power of STEGB-DPCM decreases with the PCM thickness, the heat flux and the brick temperature can be effectively reduced by 92.1 W/m2 and 18.49 K, indicating a diminished demand for indoor cooling implement. This study will provide a worthwhile design assistance for building envelope system on improving thermal technology performance and indoor thermal environment.