A heat exchanger includes a shell, a refrigerant distribution assembly and a heat transferring unit. The refrigerant distribution assembly includes a first tray part and second tray parts. The first tray part continuously extends generally parallel to the longitudinal center axis of the shell to receive a refrigerant that enters the shell. The second tray parts are disposed below the first tray part to receive the refrigerant discharged from first discharge apertures such that the refrigerant accumulated in the second tray parts does not communicate between the second tray parts. The second tray parts are aligned along a direction generally parallel to the longitudinal center axis of the shell. The heat transferring unit is disposed below the second tray parts so that the refrigerant discharged from second discharge apertures of the second tray parts is supplied to the heat transferring unit.
