New design of U-turn type minichannel cold plate with hybrid fins for high temperature uniformity

The thermo-hydraulic performance of cold plates is strongly influenced by the channel profiles and fin shapes. First, a shape optimization of U-turn type liquid cold plates is performed employing a discrete adjoint method in this work. The better uniformity of flow rate in minichannel cold plates is obtained by applying the optimized design of structures for entrance and baffle regions. Compared with the baseline design, the standard deviation of the flow rate for the optimal design decreases by 82.76%. The temperature uniformity of liquid cold plates can be further improved by using an asymmetric design of the double flow paths. The standard deviation of the temperature of the heating wall surface in the optimal design decreased by 20.75% compared with that of the conventional design. Furthermore, the roles of fin shape (rectangular, discontinuous, and wavy), fin thickness, and amplitude, wavelength and phase difference of sinusoidal wavy fin on the thermal performance of liquid cold plates having the asymmetric design with the curved baffle proposed are evaluated in detail. The results reveal that the larger amplitude, the smaller wavelength, the greater phase difference of wavy units may contribute to the greater heat transfer performance and the better temperature uniformity of cold plates. The heat transfer augmentation is attributed to the formation of vortices in the channel caused by the wavy fins and the increase of heat transfer surface area caused by the corrugated walls. As a result, two novel designs of minichannel cold plate were presented. New design of minichannel cold plate with wavy fins exhibits better heat transfer performance, while the other design with hybrid fins has more advantages to enhance temperature uniformity. The obtained results demonstrate that the new designs proposed have better temperature uniformity than the initial design of cold plates having straight rectangular minichannels.