Development of a Manifold Microchannel Heat Sink for the Electrification of Aircraft

The miniaturization of microprocessors and power electronics is leading to critical thermal management challenges. For instance, the heat flux generated in modern computer chips is at the order of 100W/cm², which is well beyond the limit of air cooling. This high heat generation can cause a variety of thermal or mechanical failures in electronic devices. As such, there is a pressing need to devise effective cooling strategies for these microelectronic devices. Liquid cooling with microchannel heat sinks is a promising technology for high power loads. Nevertheless, traditional heat sinks with straight microchannels suffer from two critical challenges: high pressure drop and low-temperature uniformity. To address these challenges, this paper presents a 3D manifold microchannel heat sink developed using metal additive manufacturing. The flow structure and the microchannels help reduce the flow length in the across the device, reducing pressure drop, and minimizing temperature imbalances throughout the heat sink. To enable the fabrication of 3D flow structures, this novel heat sink is printed using direct metal laser sintering with 6005 aluminum alloy. The heat transfer coefficient and pressure drop of the 3D manifold microchannel heat sink were characterized by flow tests using an in-house liquid test loop. The final manifold design had a thermal resistance as low as 0.51 K/W and a pressure drop of 1.5 kPa. The manifold structure helped reduce the pressure drop for flowrates less than or equal to 0.4 L/min. This heat sink will lead to improved performance and reduced costs of thermal management systems in various industries and applications, including wafer-scale engines for supercomputing, amplifiers in radar systems, and high-voltage, high-frequency converters, inverters, and transformers in power grids and electrical propulsion systems.