A collecting pipe comprising: an axially extending inner chamber comprising a refrigerant inlet chamber and a refrigerant distribution chamber which are separated from each other and in fluid communication with each other, a refrigerant entering said refrigerant inlet chamber and being distributed to heat exchange tubes at said refrigerant distribution chamber; and a plurality of axially extending individual components (11, 12; 11, 12, 13), characterized in that at least one of said refrigerant inlet chamber and refrigerant distribution chamber or said collecting pipe is formed by successively placing and connecting the plurality of axially extending individual components (11, 12; 11, 12, 13) in an assembling direction perpendicular to the axial direction, wherein said plurality of axially extending individual components (11, 12) comprises individual first and second components, the first component comprises one of said refrigerant inlet chamber and refrigerant distribution chamber, and at least a portion of a wall of said first component and the second component form the other of said refrigerant inlet chamber and refrigerant distribution chamber by placing and connecting the first and second components (11, 12) in said assembling direction, and wherein viewed in cross section, said first component comprises: a first U-shaped wall part, step parts extending outwardly from two ends of the first U-shaped wall part, and second wall parts extending from outer ends of said step parts towards the side remote from the first U-shaped wall part, or wherein said plurality of axially extending individual components (11, 12, 13) comprise individual first, second and third components, and by means of successively placing and connecting the first component, the third component and the second component in said assembling direction, the refrigerant inlet chamber is formed between said first component and third component, and the refrigerant distribution chamber is formed between the third component and second component, and wherein when viewed in cross section, said first component comprises: a first U-shaped wall part, step parts extending outwardly from two ends of the first U-shaped wall part, and second wall parts extending from outer ends of said step parts towards the side remote from the first U-shaped wall part. an axially extending inner chamber comprising a refrigerant inlet chamber and a refrigerant distribution chamber which are separated from each other and in fluid communication with each other, a refrigerant entering said refrigerant inlet chamber and being distributed to heat exchange tubes at said refrigerant distribution chamber; and a plurality of axially extending individual components (11, 12; 11, 12, 13), characterized in that at least one of said refrigerant inlet chamber and refrigerant distribution chamber or said collecting pipe is formed by successively placing and connecting the plurality of axially extending individual components (11, 12; 11, 12, 13) in an assembling direction perpendicular to the axial direction, wherein said plurality of axially extending individual components (11, 12) comprises individual first and second components, the first component comprises one of said refrigerant inlet chamber and refrigerant distribution chamber, and at least a portion of a wall of said first component and the second component form the other of said refrigerant inlet chamber and refrigerant distribution chamber by placing and connecting the first and second components (11, 12) in said assembling direction, and wherein viewed in cross section, said first component comprises: a first U-shaped wall part, step parts extending outwardly from two ends of the first U-shaped wall part, and second wall parts extending from outer ends of said step parts towards the side remote from the first U-shaped wall part, or wherein said plurality of axially extending individual components (11, 12, 13) comprise individual first, second and third components, and by means of successively placing and connecting the first component, the third component and the second component in said assembling direction, the refrigerant inlet chamber is formed between said first component and third component, and the refrigerant distribution chamber is formed between the third component and second component, and wherein when viewed in cross section, said first component comprises: a first U-shaped wall part, step parts extending outwardly from two ends of the first U-shaped wall part, and second wall parts extending from outer ends of said step parts towards the side remote from the first U-shaped wall part.