A fin has a plurality of insertion holes in an elliptical shape through which a heat transfer tube is inserted and contains stainless steel as a material. The plurality of insertion holes are disposed as being aligned in a single row in a first direction. The fin has a first slit extending from a first end portion toward a second end portion and a second slit extending from the second end portion toward the first end portion. The second slit has a first edge portion where a cut and raised wall portion is disposed and a second edge portion where no cut and raised wall portion is disposed.

A staged high temperature heat exchanger (HEX) may comprise a first stage made from a first material and a second stage made from a second material. The first stage may comprise an inlet manifold configured to receive a flow of fluid. The second stage may comprise an outlet manifold whereby the flow of fluid exits the HEX. The first stage is configured to withstand the temperature of the flow of fluid entering the inlet manifold and configured to reduce the temperature of the flow of fluid to an intermediate temperature before the flow of fluid reaches the second stage. In various embodiments, the first material may comprise a nickel-based superalloy having at least 40% of a Ni.sub.3(Al,X) precipitate phase, X being a metallic or refractory element other than Al.

A connection block facilitates connection between circular pipes with excellent fracture withstand pressure and has flow holes to allow fluid movement between pipes, a header connector connecting the connection block to a header pipe, and a condenser including of the same and a plurality of connection tubes in a plurality of rows. The connection block includes a first surface, a second surface spaced apart from the first surface, a pair of curved portions connecting ends of the first surface and ends of the second surface, and a plurality of flow holes penetrating through the curved portions, wherein the pair of curved portions have the same curvature in cross section, perpendicular to a longitudinal direction.

A heat exchanger includes a flow passage pipe that has a flat shape having a predetermined thickness, a heat medium flowing in the flow passage pipe, the heat medium exchanging heat with a heat exchange target, and an inner fin located inside the flow passage pipe. The inner fin includes a wavy fin that partitions a main passage into multiple partitioned passages, and a guide wall connected to the wavy fin. An x-direction is a lengthwise direction of the flow passage pipe, a z-direction is a thickness direction of the flow passage pipe, and a y-direction is a direction perpendicular to both the x-direction and the z-direction. The wavy fin includes a first convex portion convex to a first side in the y-direction, and a second convex portion convex to a second side in the y-direction. The wavy fin has an opening portion through which two partitioned passages adjacent to each other communicate with each other. The guide wall protrudes from the wavy fin into the partitioned passage. The heat exchanger is capable of enhancing a heat transfer and improving a thermal performance of the heat exchanger.

A first heat exchanger is a heat exchanger that exchanges heat between refrigerant and gas. The first heat exchanger includes a first group of first heat transfer tubes, a second group of first heat transfer tubes, a first group of second heat transfer tubes, and a second group of second heat transfer tubes. The first group of first heat transfer tubes are arranged side by side in a third direction and connected to each other in series. The second group of first heat transfer tubes are arranged side by side in the third direction and connected to each other in series. The first group of second heat transfer tubes are arranged side by side in the third direction and connected to each other in series. The second group of second heat transfer tubes are arranged side by side in the third direction and connected to each other in series.

A distributor, a heat exchanger, and a heat pump apparatus each includes an outer wall portion having a cylindrical shape and extending in a transverse direction and a plurality of cylindrical portions extending in the transverse direction, the plurality of cylindrical portions being provided in the outer wall portion or in a hollow portion inside the outer wall portion and each having a flow passage having a circular cross-section inside the cylindrical portion. The plurality of cylindrical portions are provided parallel to each other. The outer wall portion has a plurality of connecting ports formed in an upper or lower part of the outer wall portion and spaced apart from each other in the transverse direction. Each of the plurality of cylindrical portions has a plurality of orifices provided in the cylindrical portion and spaced apart from each other in the transverse direction.

A heat exchanger assembly includes a combustion assembly having a combustion chamber, a first heat exchanger, a flue gas passage having a condensation chamber, and a second heat exchanger. The first heat exchanger is located in the combustion chamber. The flue gas passage is configured to receive flue gas from the combustion chamber and to discharge the flue gas out of the heat exchanger assembly. The second heat exchanger is disposed in the condensation chamber and is configured to exchange heat with the flue gas entering the flue gas passage.

A heat exchanger for an air conditioner includes a plurality of flat heat transfer tubes through which a refrigerant flows; first and second headers disposed on opposite ends of the plurality of flat heat transfer tubes; at least one baffle disposed in at least one of the first and second headers and to partition an inner space of the at least one header; and a refrigerant flow control device disposed on the at least one baffle, to allow the refrigerant to selectively pass through the at least one baffle. The refrigerant flow control device is configured to prevent refrigerant from passing through the refrigerant flow control device when the refrigerant flows in one direction in the header, and to allow the refrigerant to pass through the refrigerant flow control device when the refrigerant flows in a direction opposite to the one direction in the header.

A heat exchanger includes a plurality of principal heat exchange sections and auxiliary heat exchange sections. Each of the auxiliary heat exchange sections is in series connection to a corresponding one of the principal heat exchange sections. The number of the flat tubes constituting each of the heat exchange sections is compared to the number of the flat tubes constituting a corresponding one of the auxiliary heat exchange sections, creating a tube number ratio, wherein the first principal heat exchange section, which is lowermost, has the smallest tube number ratio. Consequently, discharge of liquid refrigerant from a lower portion of the first principal heat exchange section is accelerated during defrosting, thereby shortening the time required for defrosting.

A heat exchanger includes a plurality of principal heat exchange sections and auxiliary heat exchange sections. Each of the auxiliary heat exchange sections is in series connection to a corresponding one of the principal heat exchange sections. Of tube number ratios of the number of the flat tubes constituting each of the heat exchange sections to the number of the flat tubes constituting a corresponding one of the auxiliary heat exchange sections, the first principal heat exchange sections which is the lowermost one has the smallest tube number ratio. Consequently, discharge of liquid refrigerant from a lower portion of the first principal heat exchange section is accelerated during defrosting, thereby shortening the time required for defrosting.