Method of manufacturing plate heat exchanger and plate heat exchanger

Abstract

In a plate heat exchanger, it is aimed to enhance strength, such as the pressure resistance and the internal pressure fatigue resistance, by increasing the joint area of a joint portion joined by brazing in a wave-patterned portion. Before a brazing process of the plate heat exchanger, a plurality of plates are stacked and pressure is applied thereto. By this pressure process, indentations of approximately “0.05 mm to 0.1 mm” are formed at contact points 9 of wave patterns in adjoining lower and upper plates. By brazing the plates after this pressure process, the joint area of the joint portion joined by brazing is increased. The increased joint area enhances the joint strength, and thus the strength of the plate heat exchanger such as the pressure resistance and the internal pressure fatigue resistance can be enhanced.

1 . A method of manufacturing a plate heat exchanger, the plate heat exchanger including a plurality of plates stacked and configured in a rectangular shape having a long side and a short side, each of the plurality of plates having formed therein a wave pattern waving in a stacking direction, wherein
 when one side of the stacking direction is defined as a lower side and an other side is defined as an upper side, a lower side plate and an upper side plate adjacent to each other have between them a plurality of intersecting portions at intersections of a plurality of bottom ridge lines representing a bottom of a wave of the upper side plate and a plurality of top ridge lines representing a top of a wave of the lower side plate, and the bottom of the wave of the upper side plate and the top of the wave of the lower side plate are joined by a brazing process at the plurality of intersecting portions,   the method of manufacturing the plate heat exchanger, comprising:   a pressure process of forming indentations on the bottom of the wave of the upper side plate and the top of the wave of the lower side plate at least at some of the plurality of intersecting portions by stacking the plurality of plates before the brazing process in a same order as in a completed state and applying pressure thereto in the stacking direction to compress the plurality of stacked plates.   
     
     
         2 . The method of manufacturing the plate heat exchanger of  claim 1 , wherein
 each plate of the plurality of plates has formed therein, near each of the short side at both ends, two openings arranged side by side across the short side, and the each plate also has formed therein the wave pattern between both pairs of the two openings respectively formed near the each of the short side at both ends, and,   in the wave pattern on the each plate of the plurality of plates, a distance H 1  of the stacking direction between the bottom of the wave and the top of the wave of the wave pattern in an area near the openings, which is an area near each of the two pairs of the two openings, is longer by a “size a” than a distance H 2  of the stacking direction between the bottom of the wave and the top of the wave of the wave pattern in an area other than the area near the openings, and   the pressure process forms the indentations that approximately offset the “size a”.   
     
     
         3 . The method of manufacturing the plate heat exchanger of  claim 2 , wherein
 in the each plate, a bottom position of the wave in a direction from the upper side to the lower side of the stacking direction in the area near the openings is lower by the “size a” toward the lower side than a bottom position of the wave in the direction from the upper side to the lower side of the stacking direction in the area other than the area near the openings.   
     
     
         4 . The method of manufacturing the plate heat exchanger of  claim 2 , wherein
 in the each plate, a top position of the wave in a direction from the lower side to the upper side of the stacking direction in the area near the openings is higher by the “size a” toward the upper side than a top position of the wave in the direction from the lower side to the upper side of the stacking direction in the area other than the area near the openings.   
     
     
         5 . The method of manufacturing the plate heat exchanger of  claim 2 , wherein
 the “size a” is 0.05 mm≦a≦0.1 mm.   
     
     
         6 . A plate heat exchanger including a plurality of plates stacked and configured in a rectangular shape having a long side and a short side, each of the plurality of plates having formed therein a wave pattern waving in a stacking direction,
 wherein when one side of the stacking direction is defined as a lower side and an other side is defined as an upper side, a lower side plate and an upper side plate adjacent to each other have between them a plurality of intersecting portions at intersections of a plurality of bottom ridge lines representing a bottom of a wave of the upper side plate and a plurality of top ridge lines representing a top of a wave of the lower side plate, and the bottom of the wave of the upper side plate and the top of the wave of the lower side plate are joined at the plurality of intersecting portions, and   wherein indentations are formed on the bottom of the wave of the upper side plate and the top of the wave of the lower side plate at least at some of the plurality of intersecting portions.