Heat exchanger

A heat exchanger, comprising:

• at least three heat exchange tube groups, wherein the heat exchange tube groups are communicated in sequence, and at least two heat exchange tube groups of the at least three heat exchange tube groups are superposed mutually along a direction in which a heat exchange airflow flows, a medium sequentially flows through each heat exchange tube group and forms a U-shaped trajectory;
• an intermediate adapter portion, wherein the at least two heat exchange tube groups are communicated with each other by the intermediate adapter portion, the intermediate adapter portion comprises at least two adapters and an adapter tube communicated with the two adjacent adapters, wherein each adapter comprises a first plate and a second plate, the adapter tube is an extrusion-formed flat tube, and a width direction of the adapter tube is perpendicular to a width direction of the heat exchange tube groups;
• and
• an end adapter portion, wherein the end adapter portion is located at an end of heat exchange tube groups which are mutually superposed away from the intermediate adapter portion, and the heat exchange tube groups which are mutually superposed are communicated with each other by the end adapter portion.