Effect of Manifold Design on Flow Distribution in Parallel Micro-Channels

Gas or liquid flow in multiple, parallel micro-channels is of interest for Micro-Electro-Mechanical Systems (MEMS) cooling applications. The published data for friction in 10-to-400μm hydraulic diameter, single micro-channels show good agreement with the conventional equations in the laminar and turbulent regimes. However, investigators of flow in multiple, parallel micro-channels in the same range of channel sizes report significantly different results. They report significant disagreement with the conventional equations and argue that transition occurs at Reynolds numbers as small as 200, dependent on the channel shape. This paper proposes that the apparent discrepancies of friction in multiple micro-channels can be attributed to flow mal-distribution. Flow mal-distribution is expected in multi-channels, because of manufacturing tolerances and poor manifold design. It can be minimized by proper header design and better manufacturing tolerances.