Optimizing the Thermo-Hydraulic Performance of Baffled Air-Based Photovoltaic-Thermal Collectors Under Transient Conditions

Air-based photovoltaic–thermal (PVT) collectors simultaneously generate electricity and recover heat, but limited convective heat transfer restricts their performance. Internal baffles enhance heat extraction while increasing pressure losses, requiring combined energetic and hydraulic assessment. This study develops a transient three-dimensional computational fluid dynamics model to investigate these competing effects over a daytime cycle from 08:00 to 17:00. Two complementary parametric analyses isolate baffle inclination and density under identical boundary conditions: inclinations of 30°, 45°, and 90° are compared with four baffles, while zero, two, four, and six baffles are evaluated at 30°. Thermal predictions are validated against published experimental measurements, yielding root-mean-square errors of 1.99 °C for outlet-air temperature and 1.14 °C for photovoltaic-cell temperature. Smooth-channel pressure losses are verified against the Darcy–Weisbach–Blasius correlation. The 30° inclination provides the most favorable thermo-hydraulic performance among the investigated angles. Increasing baffle density raises the energy-weighted daily equivalent overall efficiency from 58.54% for the smooth channel to 59.56%, 60.65%, and 61.09% for two, four, and six baffles, respectively. Corresponding mean total-pressure losses increase from 1.616 Pa to 7.806, 12.980, and 17.688 Pa, while average thermo-hydraulic performance factors reach 0.616, 0.591, and 0.571. Six baffles maximize gross equivalent energy performance, whereas two baffles at 30° provide the best compromise among baffled configurations. However, all baffled cases remain below unity under the constant-pumping-power criterion, favoring the smooth channel and highlighting the importance of hydraulic penalties in PVT design.