Modeling and thermal characterization on the energy production of a renewable solar thermoelectric generator unit

Atalay T., Yakut Y., Özbektaş S., Köysal Y., Bülbül H.

JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING, cilt.48, sa.11, 2026 (SCI-Expanded, Scopus)

Özet

This study experimentally and numerically investigates the effects of different cooling fluids and operating conditions on electrical energy production in a solar collector-integrated thermoelectric generator (SC-TEG) system. The manufactured system provides thermal conversion by storing the thermal energy from the solar collectors and transferring it to the TEGs positioned within the system. A large number of TEGs were employed in the system to ensure that the generated electrical energy was maintained at a usable level. A custom-designed heat sink with an embedded planar cooling channel was employed to actively cool the TEG modules. Experimental measurements were made at 41 degrees 14' N, 36 degrees 26' E at sea level on 31 August (nitrogen gas coolant) and 5 September (water coolant), 2024. The data was collected from 10 a.m. to 2 p.m. Based on the acquired measurements, the highest open-circuit voltages measured experimentally were 9.78 V and 8.94 V for water and nitrogen gas coolants, respectively. Furthermore, a numerical model was developed and validated to evaluate a broader range of coolants and operating conditions beyond the experimental limits. In this context, water-alcohol mixtures (50% ethylene glycol and 50% propylene glycol) and NiFe2O4 nanofluids (0.1, 0.3, and 0.5 wt%) were systematically simulated across varying mass flow rates (10-30 g/s). In addition, the effect of different wind speeds (1-5 m/s) and hot-surface temperatures (100-150 degrees C) on SC-TEG was examined. The results showed that coolant type, mass flow rate, and hot-surface temperature significantly affected the system's electrical energy production. The highest open-circuit voltage of 10 V was achieved with the 0.5 wt% NiFe2O4 nanofluid. Additionally, increasing the hot surface temperature to 150 degrees C enabled the system to reach 21 V. This study contributes to the literature by evaluating the effects of advanced nanofluids and operating conditions on the electrical energy production of an SC-TEG, combining an experimentally validated numerical model with direct outdoor daytime experiments.