Numerical Study of Multi Hot Spot GaN Cooling in a Cold Plate Considering Different Flow Networks

As electronic technology develops continuously, space and power allocated for cooling demands increase with time. Therefore, it becomes necessary to develop effective approaches to decrease the cooling power spent and allocated space to obtain low SWAP (Size Weight and Power) values. In this study, the application of T-Shaped branching is studied numerically in detail to get uniform temperature distribution and low-pressure drop as far as the chip junction temperature (GaN MMIC- Monolithic Microwave Integrated Circuit) is kept below the allowable temperature limit. The hotspot has a very challenging value with over 300W/cm2. The cooling liquid temperature is 45°C and the hot spot case temperature has to be kept below 100°C. In the analysis, the %60 ethylene glycol water mixture (EGW) is used as a cooling fluid and all analyses are done using constant thermal properties of materials. The microchannel heatsink has been already designed according to the given allowable volume and it is kept unchanged throughout the study. Since there are 8x2 heat sources, it is essential to guide the flow for uniform flow and temperature distribution. Because of size limitation in the cold plate, the inlet and outlet of the manifold are squeezed to a small area. It consists of two main lines, one is distributing and the other is collecting. They are designed to distribute the fluid as much as equal among the hotspots. All analyses are carried out with different flow rate input and branching is applied both free design and using the rule of Hess Murray (Construction Law) and the results of the solutions are compared and evaluated in terms of pressure drop, temperature uniformity, pumping power, flow balance.