Mostafa Fathi - Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran;
Mohammad Mahdi Heyhat - Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran;
Mohammad Zabetian Targhi - Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran;
Sajjad Bigham - Faculty of Mechanical Engineering, Michigan Technological University, Michigan, United States,

This study investigates the fluid flow and heat transfer characteristics of diverging microchannel heat sinks numerically using the conjugate heat transfer approach. Diverging microchannels include width divergent and height divergent channels. The effect of divergence ratio and coolant flow rate on the thermal performance of the heat sinks are assessed. Results show that the heat transfer coefficient degrades in diverging channels compared to parallel channel at the same coolant flow rate. On the other hand, diverging channels have the advantage of lower pressure drop. Comparison of the surface temperature of the channels shows that height divergent channels have lower temperature than parallel channels, while the surface temperature of width divergent channels is higher than other cases. Furthermore, the height divergent channel with a higher divergence ratio has the lowest total thermal resistance compared to other cases. Although the heat transfer coefficient decreases in height divergent channels, the cooling performance of the heat sink increases due to the increase in heat transfer area and better fluid mixing.

Diverging microchannel, Height divergent channel, Width divergent channel