Thermo-hydraulic performance of wavy microchannel heat sink with oblique grooved finned

Abstract

• The combination of wavy and oblique grooves finned was analyzed numerically. • Wetted area governs the appropriate pattern type. • Nu max occurs in case of P = 375 and l = 250 µm. • Maximum pressure drop is created in case of P = 375 and l = 250 µm. • The secondary flow is one of the main contributors to heat transfer enhancement. • The performance index determined the effective pattern. One of the crucial phenomena to enhance the heat transfer of microchannel heat sinks is the flow mixing and wall interaction through the secondary flow. In the present study, a combination of the wavy and the oblique grooved microchannel patterns was investigated to improve the performance of the microchannel heat sink. The oblique grooves with a pitch of 375 µm were combined with the wavy microchannel. The effect of fins with widths of 250 and 125 µm on thermal performance was investigated (Type-1 and Type-2). The amplitude of 250 µm and wavelength of 2500 µm were considered for wavy microchannels. Furthermore, the effect of pitches on the heat transfer was studied; subsequently, pitches of 750 and 1500 µm were analyzed (Type-3 and Type-4). Nusselt number, pressure drop, and performance evaluation criteria index were reported as the results. The results showed that secondary flow generation causes the thermal boundary layer to re-develop at each fin, continually developing fluid flow. Type-2 had the maximum average Nusselt number of approximately 80 and a pressure drop of approximately 50 kPa at Re = 850 compared to the other three cases. The performance evaluation criterion index (ƞ) was calculated for all cases to achieve a comprehensive conclusion about the performance of a heat sink. The results showed that in Type-2, the heat transfer increase exceeded the pressure drop penalty, and its eta was almost 2.5. Fluid flow patterns were investigated in detail as the most significant reason for efficiency improvement, and the wetted area was studied, which their maximum value equaled 1.2 at Type-2.