HYDRODYNAMIC AND THERMAL CHARACTERISTICS OF THE FLOW INSIDE A RECTANGULAR MICROCHANNEL WITH DIFFERENT CYLINDRICAL MICRO PIN FINS

This article presents a computational study to investigate the hydrodynamic and thermal characteristics of the flow inside a rectangular microchannel with the dimensions of 5000 x 1500 x 100 mu m(3) (1 x w x h') with different inline arrangements of cylindrical micro pin fins. A parametric study is performed on the effect of different geometrical specifications of micro pin fms on the wake-pin fin interaction. Three values of (50, 100 and 200 mu m) are considered for the pin fm diameters (D) while the overall height (H) of the system is set to be constant (100 mu m). For the first two cases, two longitudinal and vertical pitch ratios (SL/D and S-T/D) of 1.5 and 3 are considered while for H/D ratio of 0.5, only S-T/D ratio of 1.5 and S-L/D ratios of 1.5 and 3 are considered. As a result, a total number of ten different geometries are analyzed in five different Reynolds numbers of 20, 40, 80, 120 and 160. A constant heat flux is applied through the bottom surface of the microchannel as well as the micro pin fms surfaces. All other surfaces are assumed to be thermally isolated. Thermodynamic properties of water are set to vary with temperature and it is assumed that the working flow remains in the liquid form in all operating conditions. ANSYS commercial package v14.5 with an academic license is utilized to generate the 3D models, applying the appropriate grid networks and simulating the flow fields for each configuration. Results show major dependencies of pressure drops, friction factors, Nusselt numbers and Thermal Performance Index values on S-T/D ratio and Reynolds number while minor dependencies of these parameters on S-L/D and H/D ratios are observed.