Short Review on Thermohydraulic Performance Enhancement of Solar Flat Plate Air Heaters Using Novel Turbulators

Solar flat plate air heaters (SFPAHs) are extensively used for applications which demands thermal power as source. However, their thermal efficiency is mainly limited by unstable or low convective heat transfer and stable boundary layer formation along the absorber surface.  This study compares and present insights from critical review on the available heat transfer enhancement methods (geometrical modifications, artificial roughness, turbulator integration etc.) of the SFPAHs.  From the observed literatures, it is clearly inferred that the integration of turbulators offers significant improvement. In specific, cylindrical turbulators aligned vertical to the absorber plate recorded the best heat transfer coefficient, Nusselt Number, thermal efficiency and thermohydraulic performance factor in comparison with remaining turbulator geometries. Also, this study recommends a novel cylindrical turbulator that provides improved contact surface length and promotes repeated boundary layer redevelopment. This configuration enhances mixing and heat transfer while moderating excessive pressure drop typically associated with sharp-edged inserts.