A heat exchanger includes a tube expansion portion provided on a heat transfer tube such that an outer peripheral surface of the heat transfer tube is pressed against an inner peripheral surface of a first hole provided in a side wall portion of a case, and a first concave surface portion that is provided in a part of an outer surface of the tube expansion portion and forms a first gap, into which brazing material of a first brazed portion advances, between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. Thus, the attachment strength of the heat transfer tube can be improved by means of a simple configuration.

A flooring underlayment includes a base membrane and a cover membrane. The base membrane is configured to be installed between a subfloor and floor tiles to allow movement of the floor tiles relative to the subfloor. The base membrane includes a base layer and studs projecting from the base layer. The studs have free ends that define pockets therein. The cover membrane is configured to be coupled to the base membrane to form a flat surface for supporting the floor tiles. The cover membrane includes a cover layer and studs projecting from the cover layer. The studs on the cover membrane are configured to fit within the pockets in the base membrane to couple the cover membrane to the base membrane.

A fluidized bed heat exchanger with a chamber (24) comprises a solid particles inlet port (22), a solid particles outlet port (30), arranged at a distance to the inlet port (22), means (46) for introducing a fluidizing gas from a bottom area into the chamber (24). The heat exchanger further comprises at least two heat transfer means (28) within the one chamber (24), each being provided with a heat transfer medium inlet port (42) and a heat transfer medium outlet port (44), wherein a first heat transfer means (28) is designed as a reheater and second heat transfer means (28) is designed as a superheater to achieve a heat transfer medium temperature and a heat transfer medium pressure above that of the reheater. At least one of the reheater or superheater is made of a multiplicity of heat transfer tubes arranged in a meandering fashion for conveying a heat transfer medium.

A secondary heat exchanger includes a case and a first heat transfer tube portion. The case includes a box body and a first closing member. The box body is provided with a second opening on one side in a third direction. A first assembly in which the first heat transfer tube portion and the first closing member are assembled integrally is mounted to the box body so that a plurality of first heat transfer tubes are is inserted into the box body from the second opening and so that the second opening is closed by the first closing member.

A heat exchanger includes tube expansion portions provided respectively on a plurality of heat transfer tubes such that outer peripheral surfaces of the heat transfer tubes are respectively pressed against inner peripheral surfaces of a plurality of first holes provided in a side wall portion of a case, and a plurality of first concave surface portions provided in an outer surface of the tube expansion portion so that first gaps, into which brazing material of a first brazed portion advances, are formed between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. At least one of the plurality of first concave surface portions is positioned in an outside peripheral surface portion of the outer peripheral surface of the heat transfer tube. According to this configuration, the strength with which the heat transfer tubes are attached to the case can be increased while simplifying a manufacturing operation and reducing the manufacturing cost.

A method of assembling a heat exchanger includes the steps of fluidly connecting a plurality of first heat exchanger tubes to a first connecting tube portion at an assembly location to form a first subassembly, fluidly connecting a plurality of second heat exchanger tubes to a second connecting tube portion at the assembly location to form a second subassembly, transporting the first subassembly and the second subassembly from the assembly location to an installation location, and connecting the first subassembly to the second subassembly at a single connection point between the first connecting tube portion and the second tube connecting portion.

A heat exchanger for an apparatus including a burner has at least one tube extending along a centerline from an inlet end adjacent the burner to an outlet end. A plurality of indentations is formed in the tube adjacent the inlet end and extend radially inward towards the centerline. The indentations are formed in opposing pairs extending towards one another to a depth sufficient to create turbulent fluid flow through the inlet end of the tube.

An indirect heat exchanger has two airflow paths and an airflow generator to draw air through the airflow paths. A fluid conduit passes through the heat exchanger such that a cooling region is positioned within each of the flow paths. A dispenser is positioned to dispense evaporative liquid on one of the cooling regions. The dispenser operates in a wet mode and a dry mode. A controller regulates airflow through the first flow path and the second flow path, and also controls the operation of the dispenser. In this way, the controller may operate the airflow paths independently such that the airflow through a flow path operating in the dry mode is greater than that of the flow path operating in the wet mode.

An indirect heat exchanger has two airflow paths and an airflow generator to draw air through the airflow paths. A fluid conduit passes through the heat exchanger such that a cooling region is positioned within each of the flow paths. A dispenser is positioned to dispense evaporative liquid on one of the cooling regions. The dispenser operates in a wet mode and a dry mode. A controller regulates airflow through the first flow path and the second flow path, and also controls the operation of the dispenser. In this way, the controller may operate the airflow paths independently such that the airflow through a flow path operating in the dry mode is greater than that of the flow path operating in the wet mode.

A heat exchanger includes a tube expansion portion provided on a heat transfer tube such that an outer peripheral surface of the heat transfer tube is pressed against an inner peripheral surface of a first hole provided in a side wall portion of a case, and a first concave surface portion that is provided in a part of an outer surface of the tube expansion portion and forms a first gap, into which brazing material of a first brazed portion advances, between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. Thus, the attachment strength of the heat transfer tube can be improved by means of a simple configuration.