Hydrodynamic and Thermal Performance of Microchannels With Different In-Line Arrangements of Cylindrical Micropin Fins

This study presents results on the hydrodynamic and thermal characteristics of single-phase water flows inside microchannels (MCs) with different micropin fin (MPF) configurations. Different inline arrangements of micropin fins were considered over Reynolds numbers ranging from 20 to 160. The computational studies were performed using the commercial software ansys 14.5. The hydrodynamic performances of the configurations were compared using two parameters, namely, pressure drop and friction factor while the comparison in their thermal and thermal-hydraulic performances were based on Nusselt number and thermal performance index (TPI). Wake-pin fin interactions were carefully analyzed through streamline patterns in different arrangements and under different flow conditions. The results showed strong dependencies of all four evaluated performance parameters on the vertical pitch ratio (S_T/D). Weaker dependencies on height over diameter ratio (H/D), horizontal pitch ratio (S_L/D), and minimum available area (A_min) were observed. With an increase in the Reynolds number, extension of the wake regions behind MPFs was observed to be the paramount factor in increasing pressure drop and Nusselt number. Regarding TPI, two adverse trends were observed corresponding to different S_T/D ratios, while the effect of S_L/D ratio was unique. For friction factors, H/D and S_L/D ratios of 1 and 1.5, respectively, led to minimum values, while different S_T/D ratios are needed for each diameter size for the maximum performance. Moreover, a twofold increase in Reynolds number resulted in about 40% decrease in friction factor in each configuration.