A refrigerant guide tube used in a heat exchanger, the refrigerant guide tube comprising a tube body having passages extending through a wall of the tube body, wherein the tube body comprises two or more bar-shaped plates and two or more longitudinal joints, wherein each of the two or more bar-shaped plates comprises two longitudinal side edges, wherein each of the longitudinal side edges is angled outward away from a central portion of the tube body to define a jointing surface, wherein each longitudinal joint comprises two abutting longitudinal side edges which abut along their jointing surfaces and are jointed together, wherein the two abutting longitudinal side edges include one of the longitudinal side edges of one of the two or more bar-shaped plates and one of the longitudinal side edges of another one of the two or more bar-shaped plates, wherein the two abutting longitudinal side edges of at least one of the longitudinal joints are provided with grooves extending in a depth direction perpendicular to a longitudinal direction of the at least one longitudinal joint, wherein the grooves are formed between the two abutting longitudinal side edges of the at least one longitudinal joint such that the two abutting longitudinal side edges are spaced apart from one another at the grooves to form the passages, the passages having the shape of cylinders or rectangular cuboids, and wherein said passages extend from an inside of the guide tube to an outside of the guide tube such that a fluid communicates between the inside and outside of the guide tube through the passages.