Abstract: A heat exchanger includes: first plates; second plates disposed at intervals with each between a pair of the first plates adjacent to each to alternately form first flow paths and second flow paths; and a heat exchange promoting member in the first flow paths. At least one of the first plates and each second plate includes a plurality of protruding portions each of which is formed in a V shape in a plan view such that the protruding portion recesses in a corresponding one of the first flow paths and projects in a corresponding one of the second flow paths. Each protruding portion has a tip end portion and an opening portion arranged in a flow direction in the second flow path, and one of a pair of free end portions is positioned on a first inflow port side and the other is positioned on a first outflow port side.

Abstract: A cooling device has a flat flow path formed between a first wide surface and a second wide surface, the second wide surface including protrusion portions protruding into the flow path, extending in a flow path width direction, and arranged side by side in a fluid flow direction. The first wide surface has no protrusion portions. The protrusion portions each include a first inclined surface inclined to come close to the first wide surface from upstream to downstream in the fluid flow direction, and a second inclined surface disposed alternately with the first inclined surface in the fluid flow direction and inclined to be distanced from the first wide surface from upstream to downstream in the fluid flow direction. The protrusion portions are formed such that a virtual first circle is inscribed at three points on the first wide surface, the second inclined surface, and the first inclined surface.