Experimental investigation of an Auto-Switching SH TEG/PCM unit for consistent All-Day electric power generation

Abstract

In the pursuit of sustainable energy solutions, combining a thermoelectric generator (TEG) with a phase change material (PCM) powered by solar energy shows promise for consistent electricity generation (EG). Despite extensive research on solar-heating TEG/PCM systems, there is a lack of studies directly utilizing sunlight, with heaters commonly used as substitutes, thus overlooking the influence of solar radiation spectrum and intensity. This study examines auto-switching SH TEG/PCM unit performance under simulated solar irradiation, presenting an experimental setup and theoretical model for system analysis. Results show that the total EG over 24 h relies on the EG during the lighted operation phase (LOP). Once the PCM in the aluminum box (AB) fully melts, a secondary temperature rise near the bottom of the top cover occurs during the transition to static phase (TSP). Unit 80-AB achieves the highest total EG under a total solar irradiance of 4 kW⋅h/m², with values of 3.72 and 0.15 W⋅h/m² for the LOP and TSP, and when exposed to 8 SSs for 5 h, it peaks at 4.4 and 0.19 W⋅h/m² for the LOP and TSP, respectively. Additionally, the EG for unit 80-AB is maximal after almost 10-hour exposure, with the insulated unit featuring a film achieving a total EG of 8.78 W⋅h/m², exceeding the bare unit and insulated unit by 1.06 and 1.54 W⋅h/m², respectively. During the LOP, the experimental unit 80-AB can achieve a maximum increase in EG of 7.71 W⋅h/m² in the bare mode compared to the control unit. The open-circuit voltage of unit 80-AB reaches approximately 110 mV, with the maximum output power amounting to 0.34 W/m² when the load resistance is 5 Ω. The proposed units present a practical solution for continuous EG throughout the day, guaranteeing a reliable energy provision and heralding an environmentally sustainable energy paradigm.