In a plate heat exchanger, a bypass passage and a main passage are formed upstream of first passages and second passages between adjacent ones of first heat transfer plates and second heat transfer plates. The bypass passage allows first fluid flowing from an inflow port of the first fluid or second fluid flowing from an inflow port of the second fluid to pass a side farther than a corresponding one of adjacent holes while spreading in a vertical direction in a front view and then flow into an inner fin or a corrugated heat transfer surface. The main passage allows the first fluid flowing from the inflow port of the first fluid or the second fluid flowing from the inflow port of the second fluid to directly flow toward the inner fin or the corrugated heat transfer surface without routing through the bypass passage. A flat space is formed around an entire circumference of each of the adjacent holes, and the first fluid or the second fluid flowing through the main passage and the first fluid or the second fluid flowing through the bypass passage merge in the space between a circumferential wall and the inner fin or the corrugated heat transfer surface.
展开▼
