Considerations and Challenges for Large Area Embedded Micro-channels with 3D Manifold in High Heat Flux Power Electronics Applications

Embedded microchannel with 3D manifold heat sinks (EMMCs) offer two primary advantages over conventional microchannel heat sinks: increased thermal performance and decreased pressure loss. The unique 3D fluid routing mechanism of the manifold reduces pressure losses and, resultantly, reduces required pumping power. Previous simulations and experimental studies have been limited to cooling of small footprint electronics, typically on the order of 5×5mm2. This work explores the effects of scaling up the footprint of the cooling area using single phase water. A constant heat flux is applied at the top of the microchannel cold plate and the manifold routes fluid in and out of this cold plate. Achieving similar thermal performance with a larger footprint necessitates scaling flow rate approximately proportional to area. Therefore, significantly higher pressure losses are expected as the heater area is scaled up from 5×5mm2 to 20×20mm2. For example, in order to achieve a target performance of 0.078 cm2-K/W, pressure drops from the inlet to outlet are 2 and 35 kPa for the 5×5mm2 and 20×20mm2, respectively. In addition, increasing the flow rate of liquid results in the location of the hottest spot on the device shifting away from the center of the device. Finally, this paper discusses ongoing and future experimental work and methods of improving thermal and pressure performance in large-scale EMMCs.