The present disclosure is directed to heat exchangers with flow distribution manifolds divided into an inlet section and a distribution section by a distributor. The inlet section may have a relatively small cross-sectional area that promotes mixed phase flow of liquid and vapor refrigerant. The manifolds may be used with multichannel tubes with flow path inlet sections that allow refrigerant to enter the flow paths through an outer wall of the tubes. In certain embodiments, a portion of the outer wall is removed to expose the flow paths to a distribution chamber within the inlet manifold. The multichannel tubes extend into the distribution section to partition the distribution section into a series of distribution chambers defined by a pair of adjacent tubes, the distributor, and the inlet manifold. Within each distribution chamber, the refrigerant may be directed into the multichannel tubes through the inlet sections of the multichannel tubes.