Experimental investigation of the twist angle effects on thermo-hydraulic performance of a square and hexagonal pin fin array in forced convection

This research deals with an experimental investigation to manage the thermo-hydraulic performance of the heat sink with pin fin array under forced convection at various design factors and operating conditions. Experimentation tests were performed on two pin fin section shapes of a square and hexagonal with four various twist angles (0, 30, 60, and 90 degrees) at constant heat flux with air Reynolds number (Re) ranging from 3182 to 9971. The enhancement in Nusselt number (Nu) and heat transfer coefficient increased with the increase of twisting angle for the whole tested range of Re. The hexagonal cross-section produced an increment of Nu more than a square shape. The hexagonal fins with theta = 90 degrees have higher Nu than other values of twisting angle. The enhancement in heat transfer and heat dissipation performed by square fin was more than hexagonal fins for all values of twisting angle. A decrease in the thermal resistance was recorded with the increase of Re, also, the twisted fins have lower thermal resistance than that of non-twisted pins. The friction factor and pressure drop reduces with an increase of twisting angle. The twisted fins have lower efficiency compared to no twisted fins. The HTPF of the hexagonal pin has the maximum value at twisting angle (theta) = 90 degrees and the lowest value for the square pin at twisting angle (theta) = 30 degrees. Dimensionless empirical general correlations were extracted from the experimental results of the current investigation with maximum deviations about +/- 8.9%, +/- 6.3%, and +/- 10.6% for Nusselt number, fin efficiency, and friction factor, respectively.