Hybrid TiO2–Fe3O4 nanofluid and hinged bending turbulators for high-efficiency PVT flat-plate collectors: Experimental assessment of heat transfer, energy, and exergy performance

This study presents a combined enhancement approach to improve the thermal and electrical performance of a photovoltaic–thermal collector by utilizing a 50% TiO 2 –50% Fe 3 O 4 hybrid nanofluid at 0.5% concentration and perforated twisted tape turbulators with different twist ratios. An experimental investigation was conducted to evaluate heat transfer effectiveness, energy efficiency, exergy efficiency, and hydraulic performance. The results indicate that a twist ratio of the two provides the best overall performance, achieving a heat transfer enhancement exceeding 67% compared to the baseline system. Maximum energy and exergy efficiencies of 82% and 30%, respectively, were obtained. These improvements are attributed to enhanced thermal conductivity and intensified fluid mixing. Although the proposed method increases pressure drop, the overall thermo-hydraulic performance remains favorable, as confirmed by the performance evaluation criterion. The findings demonstrate that the proposed configuration is an effective and practical solution for advanced photovoltaic–thermal applications.