Reactor

A reactor for causing a reaction of a first fluid by a heat exchange between the first fluid and a second fluid to generate a product, the reactor comprising:

• a plurality of first structures each including:
• first side walls provided on both sides in a first direction on one surface of a first base plate and extending in a second direction perpendicular to the first direction;
• a plurality of first middle walls arranged at intervals in the first direction between the paired first side walls on the one surface of the first base plate and extending in the second direction;
• and first flow channels provided between each first side wall and the adjacent first middle wall and between the respective first middle walls adjacent to each other so that the first fluid flows therethrough;
• a plurality of second structures coexisting with and stacked on the plural first structures in a third direction perpendicular to the first direction and the second direction, the second structures each including:
• second side walls provided on both sides in the first direction on one surface of a second base plate and extending in the second direction;
• a plurality of second middle walls arranged at intervals in the first direction between the paired second side walls on the one surface of the second base plate and extending in the second direction;
• and second flow channels provided between each second side wall and the adjacent second middle wall and between the respective second middle walls adjacent to each other so that the second fluid flows therethrough;
• and
• a lid structure provided on the second structure located on one end side in the third direction to cover the plural second flow channels,
• wherein end surfaces of the first side walls and end surfaces of the first middle walls are joined to the adjacent second structure,
• end surfaces of the second side walls and end surfaces of the second middle walls are joined to the adjacent first structure or the lid structure,
• a thickness of the first side walls is greater than or equal to a thickness of the first middle walls, and
• a thickness of the second side walls is greater than or equal to a thickness of the second middle walls.