A heat exchanger header for receiving a first fluid includes a tubular primary fluid channel oriented along a first axis and having a first cross-sectional area. A first branched region adjacent to the primary fluid channel fluidly connects to a plurality of tubular secondary fluid channels, each having a second cross-sectional area, and a second branched region adjacent to each of the secondary fluid channels fluidly connects to a plurality of tubular tertiary fluid channels, each having a third cross-sectional area. The second cross-sectional area is greater than the third cross-sectional area.