Heat transfer enhancement of microchannel heat sink with longitudinal vortex generators and bypass jet flow

Aiming to enhance the heat transfer characteristics of microchannel heat sink, the present study firstly proposes a method to construct 45° ribs on lower surface of the channel wall. The ribs could induce longitudinal vortices, and cause drastic mixing of the coolant fluid. Furthermore, a bypass channel with an opening located at downstream region is set up on upper walls of the channels. The bypass jet flow would augment furtherly the mixing of coolant fluid. The effects of rib number (N), rib height (Rh) and bypass channel configuration on flow structure, thermal field, pressure drop and hot spot temperature of the heat sink are investigated detailed. Results show that the reduction in hot spot temperature of the heat sink is larger for a higher Rh. For a given Rh, there is an optimum N for minimizing hot spot temperature. The influences of bypass channel height on heat transfer characteristics are more significant than the opening width and location. The maximum reduction in hot spot temperature is 30.81% for ribs constructed on channel wall. While it can be up to 49.97% when the ribs and a bypass channel are constructed simultaneously.