Abstract: A plate fin heat exchanger 1 includes a corrugated fin 3 and tube plates 2. An intermediate portion 33 of the corrugated fin between crest and trough portion 31 and 32 thereof has a plurality of protruding ribs 34 protruding beyond a surface of the corrugated fin and arranged in a first direction. Surfaces of the crest and trough portions being in contact with the tube plates are configured as contact surfaces 310, 320 with no protruding rib. Gently sloping portions 341 are provided between the protruding ribs and the contact surfaces of the crest and trough portions to gradually protrude from the surface of the corrugated fin with increasing distance from the contact surfaces, and are continuous with the protruding ribs.

Abstract: Two or more cores (2a, 2b) in each of which two more types of passage layers through which two or more fluids flow are layered alternately are welded together. The entire bottom portions of the cores (2a, 2b) are covered with a lower header tank (3), thereby making the fluids flow into the cores (2a, 2b). A dummy layer (14) through which none of the fluids flow is provided beside a weld side face of each core (2a, 2b). A weld spacer (18) is welded to the entire peripheral edge of a side plate (16) of the dummy layer (14). A through-hole (16a) for draining water in the dummy layer (14) is made near the lower end of the side plate of the dummy layer (14). Further, a liquid drain hole (20) through which water is drained is made at a lower corner of the weld spacer (18).

Abstract: A plate fin heat exchanger 1 includes a corrugated fin 3 and tube plates 2. An intermediate portion 33 of the corrugated fin between crest and trough portion 31 and 32 thereof has a plurality of protruding ribs 34 protruding beyond a surface of the corrugated fin and arranged in a first direction. Surfaces of the crest and trough portions being in contact with the tube plates are configured as contact surfaces 310, 320 with no protruding rib. Gently sloping portions 341 are provided between the protruding ribs and the contact surfaces of the crest and trough portions to gradually protrude from the surface of the corrugated fin with increasing distance from the contact surfaces, and are continuous with the protruding ribs.

Abstract: Two or more cores (2a, 2b) in each of which two more types of passage layers through which two or more fluids flow are layered alternately are welded together. The entire bottom portions of the cores (2a, 2b) are covered with a lower header tank (3), thereby making the fluids flow into the cores (2a, 2b). A dummy layer (14) through which none of the fluids flow is provided beside a weld side face of each core (2a, 2b). A weld spacer (18) is welded to the entire peripheral edge of a side plate (16) of the dummy layer (14). A through-hole (16a) for draining water in the dummy layer (14) is made near the lower end of the side plate of the dummy layer (14). Further, a liquid drain hole (20) through which water is drained is made at a lower corner of the weld spacer (18).