Heat exchanger with corrugated plate

A heat exchanger comprising:

• a first tube defining therein a first passage through which a first fluid flows, the first tube having a first inner side wall and a second inner side wall opposite to each other;
• a second tube defining therein a second passage through which a second fluid flows, the second tube being joined to an outer surface of the first tube for performing heat exchange between the first fluid and the second fluid;
• and
• a corrugated plate housed in the first tube, wherein
• the corrugated plate has intermediate walls for partitioning the first passage, the intermediate walls include first walls, second walls, and third walls, each defining a first end and a second end opposite to each other,
• each of the first walls is disposed such that the first end is proximate to the first inner side wall of the first tube and the second end defines an opening between itself and the second inner side wall of the first tube,
• each of the second walls is disposed such that the first end and the second end are separate from the first inner side wall and the second inner side wall of the first tube for defining openings,
• each of the third walls is disposed such that the first end defines an opening between itself and the first inner side wall of the first tube and the second end is proximate to the second inner side wall of the first tube, and
• the first walls, the second walls, and the third walls are reiterative in an order of the first wall, the second wall, the third wall and the second wall.