A heat exchanger is adapted to be used in a vapor compression system, and includes a shell, a distributing part and a tube bundle. The tube bundle includes a plurality of heat transfer tubes arranged in a plurality of columns extending parallel to each other when viewed along the longitudinal center axis of the shell. The heat transfer tubes has at least one of: an arrangement in which a vertical pitch between adjacent ones of the heat transfer tubes in at least one of the columns is larger in an upper region of the tube bundle than in a lower region of the tube bundle; and an arrangement in which a horizontal pitch between adjacent ones of the columns is larger in an outer region of the tube bundle than in an inner region of the tube bundle.