Effect of Film Cooling on Surface Temperature and Thermal Performance of Solar Thermal Collector Featured With Hybrid Nanofluid

ABSTRACT Flat plate collectors (FPCs) are common in solar‐based thermal systems, including heat exchangers, heat pipes, water heaters, and dryers, due to their simple construction, improved heat transfer, and reliable operation. However, it has lower thermal efficiency due to uneven thermal distribution and reduced heat dissipation. This study aims to enhance the thermal performance of FPC by integrating a 50:50 nanofluid of magnesium oxide (MgO) and titanium dioxide (TiO 2 ) and a film‐cooling technique at 0.5, 1, and 1.5 velocity ratios. Using Fourier transform infrared spectrometer analysis, the stability of the hybrid (MgO/TiO 2 ) nanofluid is assessed and found to be better, leading to improved thermal performance of the FPC. The FPC operated with a hybrid nanofluid, achieving a higher fluid temperature of 94.9°C. The film‐cooling technique reduced the surface overheat to 50.8°C. A higher velocity ratio led to a more uniform temperature distribution, a higher heat transfer coefficient of 473.9 W/m2K, and an optimum thermal efficiency of 66.1%. These performance metrics are notably better than those of the FPC operated without film cooling.