Heat transfer characteristics of Cu-based microchannel heat exchanger fabricated by multi-blade milling process

A Cu-based double-layer compact counter-flow microchannel heat exchanger has been designed, fabricated, and evaluated. A manufacturing method called multi-blade milling is used for cost-effective fabrication of rectangular microchannel with height of 0.5-2 mm, width of 0.2-0.8 mm and spacing of 0.4-1 mm. Theoretical analysis of structural characteristics of microchannels based on specific surface area is conducted. The experimental and numerical investigations on the effect of microchannel size on fluid flow and heat transfer characteristics for optimization of microchannel size and their implementation in heat exchanger are performed. Nusselt number and Poiseuille number at a range of Reynolds numbers are presented and compared using deionized water as the coolant. The velocity and temperature distribution through numerical simulation provide better understanding on the fluid flow and heat transfer characteristics. Based on the experimental and numerical results, the optimal geometric parameters of microchannel with height of 0.5 mm, width of 0.4-0.6 mm, and spacing of 0.4 mm are recommended to achieve the enhancement of heat transfer and the compactness of microchannel heat exchanger.