Transient real-time 4E analysis for an auto-switching solar-heating TEG/PCM unit

The global shift towards sustainable energy sources to mitigate greenhouse gas emissions has propelled innovative technologies. Although thermoelectric generators (TEGs) offer a promising solution to convert waste heat into electricity, their efficiency remains a challenge. The integration of solar-driven TEG/PCM (phase change material) units presents a pathway for continuous clean power generation. This study centers on auto-switching solar-heating TEG/PCM units, incorporating a comprehensive 4E (energy, exergetic, environmental, and economic) analysis by exploring solar parameters, investigating cooling methods, and assessing the enhanced environmental benefits resulting from PCM integration. Our results demonstrate that despite consistent total solar irradiation, higher irradiation intensities correspond to increased power generation. Unit 80-AB achieves a maximum exergetic efficiency of approximately 0.124 % under approximately 968 W/m² solar irradiance from 8 solar simulators (SSs), with and a minimum dollar-per-watt (DPW) value of around 0.5 $/(W⋅m²), resulting in an annual reduction of 0.43 kg/year in carbon dioxide emissions. The DPW values fall below 20 $/(W⋅m²) during the lighted operation phase, range between 10 and 10⁴ $/(W⋅m²) at the transition to static phase, and span from 10⁴ to 10⁶ $/(W⋅m²) during the full static state. Once solar irradiation intensity is set, the initial maximum power outputs for each unit are fixed. Unit 80-AB maintains an average maximum power output of 0.84 W/m² under 8 SSs. It shows the lowest DPW among all units, ranging from around 0.43 to 0.67 $/(W⋅m²) over various durations, with a peak after 10 h. Additionally, it achieves the highest annual CO₂ savings, approximately 1.11 kg/year for 10 h of irradiation. Experimental unit 80-AB consistently saves 2 to 3 times more CO₂ annually than control unit 80-ABC across all conditions. By providing valuable insights into the 4E performance of the proposed units, this study illustrates their efficacy in sustainable energy generation and environmental impact mitigation.