Effect of discrete V-fin array on thermal performance of solar air heater system - A CFD study

The influence of discretely placed V-fins on the solar air heater performance for Re = 5000-15000 under same heat flux state is presented. The analysis is carried out using numerical methodology and the simulation is done using ANSYS Fluent software. The design parameters of V-fins such as the V-fin altitude is varied between 1 mm and 4 mm while the non-dimensional V-fin height (h/D) is varied as 0.08, 0.16 and 0.32 which corresponds to the fin height values of 4 mm, 8 mm & 16 mm respectively. Longitudinal pitch of V-fin is fixed as 60 mm throughout the analysis. The results reveal that the presence of V-fins augments heat transfer by introducing flow turbulence in the air stream around the V-fin region. The V-fin altitude of 2 mm exhibits the maximum rise in Nusselt number is about 1.3 times compared to smooth duct at Re = 9000 for a specified V-fin height. The V-fin altitude of 4 mm exhibits a maximum increase in friction factor of 1.6 times that of the smooth duct at Re = 15000 for a given V-fin height. Greater fin heights are found to provide improved heat transfer with a maximum Nusselt number rise of 1.38 times that of smooth duct for Re = 5000 for a specified V-fin altitude. Corresponding peak friction factor for Re = 5000 is estimated to be 1.83 times compared to that of smooth duct.