Cooling performance study of coplanar counterflow microchannels

Embedded microfluidic cooling improves cooling efficiency by avoiding interfacial thermal resistance. However, the temperature rise of the fluid along the flow direction leads to an uneven axial temperature of the straight parallel microchannels (SPMCs), which then causes the degradation of microfluidic cooling uniformity, especially at the outlet position with the greatest thermal resistance. Counterflow microchannels (CFMCs) heat exchangers can be realized by adjusting the flow direction of adjacent channels to the opposite direction. In this paper, a one-dimensional thermal resistance model of CFMCs heat exchangers is established, and the surface temperature distribution characteristics of heat exchangers are studied. Under the assumption of a constant convective heat transfer coefficient, the equivalent neutral plane and the equivalent adiabatic line are defined, and the temperature distribution of the heating surface is analyzed by using the temperature rise characteristics of the working fluid after heat absorption. Both theoretical and numerical results show a quadratic distribution of the surface temperature in CFMCs. Compared with the SPMCs, CFMCs result in a higher average surface temperature but a lower maximum surface temperature, while the temperature standard deviation is reduced by more than 60%.