A heat exchanger includes a first header and a second header and a plurality of heat exchange tubes extending therebetween. Each heat exchange tube has an inlet end opening to one of the headers and an outlet opening to the other header. Each heat exchange tube has a plurality of channels extending longitudinally in parallel relationship from its inlet end to its outlet end, each channel defining a discrete refrigerant flow path. The inlet end of each of the plurality of heat exchange tubes is positioned with the inlet opening to the channels disposed in spaced relationship with and facing an opposite inside surface of the header thereby defining a relatively narrow gap between the inlet opening to the channels and the facing opposite inside surface of the header. The gap may function either as a primary expansion device or as a secondary expansion device.