wherein an air return louver (2) is arranged on the housing (1) corresponding to the air return region, and a blower (4) is arranged in the air return region;

wherein a separator (9) is arranged horizontally in the air supply region, and an air duct (10) is arranged vertically in the air supply region; a baffle (13) is arranged on the separator (9), an opening angle of the baffle (13) is adjustable, and a connecting hole is arranged in a middle of the baffle (13); the air duct (10) comprises a straight pipe section and a tapered pipe section, an end of the straight pipe section is connected to the connecting hole, a tapered edge of the tapered pipe section is connected to a bottom edge of the housing (1); and an air supply louver (11) is arranged on the housing (1) corresponding to the air supply region, and a slidable orifice plate (12) is arranged on an inner side of the air supply louver (11);

wherein a coiled pipe (6), a concave orifice plate (7) and a condensate tray (8) are horizontally arranged in the heat exchange region;

wherein an outlet and an inlet of the coiled pipe (6) are located on the same side, and a bottom of the coiled pipe (6) is connected to the concave orifice plate (7);

wherein the concave orifice plate (7) is in contact with an inner wall of the housing (1), a plurality of holes are arranged in a middle portion of a bottom of the concave orifice plate (7), and the plurality of holes are just aligned with the condensate tray (8); and

wherein a gap exists between the condensate tray (8) and the inner wall of the housing (1) and is configured to facilitate flowing of air therethrough, a bottom of the condensate tray (8) is provided with a condensate water outlet pipe (14), and the condensate water outlet pipe (14) extends outside the housing (1) through the air duct (10).