Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided which include manifold configurations designed to promote mixing of vapor phase and liquid phase refrigerant. The manifolds contain flow mixers such as a helical tape, sectioned volumes, and partitions containing apertures. The flow mixers direct the flow of refrigerant within the manifold to promote a more homogenous distribution of fluid within the multichannel tubes.