Abstract: Embodiments are disclosed to help create longitudinal refrigerant streams, for example, in a shell and tube type evaporator, so as to manage refrigerant and/or lubricant in the evaporator. In some embodiments, the shell side of the evaporator may include a plurality of longitudinally extended pans stacked in a vertical direction. In some embodiments, refrigerant can be directed onto a top pan. The refrigerant can form a longitudinal refrigerant stream along the pan and flow down to the next pan in the vertical direction and form another longitudinal refrigerant stream. Each of the pans may form a refrigerant pool to help exchange heat with a process fluid carried in heat exchanger tubes. By forming longitudinal refrigerant streams in the pans, heat exchange efficiency may be improved and a lubricant content in refrigerant streams may be concentrated toward a bottom of the evaporator.