Abstract: A heat exchanger includes: a first flow path through which a first fluid can flow; and a second flow path through which a second fluid can flow, the second flow path having an annular flow path portion extending along an axial direction of the first flow path on an outer peripheral side of the first flow path. A honeycomb structure having an outer peripheral wall and partition walls disposed on an inner side of the outer peripheral wall, the partition walls defining a plurality of cells each extending from a first end face to a second end face, is housed in the first flow path. A heat storage material is retained in some of the cells of the honeycomb structure.

Abstract: A heat exchanger includes: a hollow heat recovery member having an inner peripheral surface and an outer peripheral surface in an axial direction, and an inflow end face and an outflow end face for a first fluid in a direction perpendicular to the axial direction; a first outer cylindrical member having an inflow port and an outflow port for the first fluid; a first inner cylindrical member having an inflow port and an outflow port for the first fluid, the first inner cylindrical member being fitted to the inner peripheral surface of the heat recovery member; and a second inner cylindrical member having an inflow port and an outflow port for the first fluid, the outflow port being located on an upstream side of the inflow end face of the heat recovery member based on the flow direction of the first fluid as a reference.

Abstract: A butterfly valve 100 provided in a flow path for a first fluid flowing through a heat exchanger. The butterfly valve 100 includes: a valve plate 110 provided in the flow path; a shaft 120 for rotatably supporting the valve plate 110 in the flow path; and at least one valve plate auxiliary member 130 in contact with at least one plate surface 111a, 111b of the valve plate 100, the valve plate auxiliary member 130 having an extending portion 131 extending radially outwardly from an outer peripheral surface 112 of the valve plate 110. The valve plate auxiliary member 130 is made of a material having a lower Young's modulus than that of the valve plate 110.