A heat exchanger and methods of manufacturing and assembling a heat exchanger, and more particularly to an air-flow heat exchanger having a mechanically assembled header for use in a motor vehicle. The heat exchanger comprises an all-metal bonded matrix including a plurality of substantially parallel metallic tubes and a plurality of metallic fins. The tubes have a heat transfer portion that is elongate in cross-sectional shape, and which comprises two opposing, longer sides, and two opposing shorter sides. At least one of the tubes is mechanically joined at a first end portion thereof to a first header of the heat exchanger by at least one compliant member. The compliant member extends around the first end portion of the tube to provide a seal and to permit relative movement between the mechanically joined tube and the first header due to thermal expansion and contraction of the matrix.

Systems and methods for pressure expanding a tube to fit a heat exchanger fin are disclosed. The systems can include one or more pressure relief devices, and each pressure relief device can be configured to release at least some pressurized fluid via a respective auxiliary flow path in response to a pressure of the pressurized fluid being greater than a predetermined pressure relief threshold.

Plate-shaped fins of a heat exchanger each include, at circumferential portions thereof defining a notch in which a heat transfer tube having a flattened shape is disposed, fin collars formed by being raised from the circumferential portions. Each of the fin collars includes, in a position that faces a long axis side surface of the heat transfer tube, at least one reflare section bent in a direction opposite to the side surface. At least one of the reflare sections defining fin pitches between the adjoining plate-shaped fins is formed so that a reflare tip portion, which is a tip portion of the reflare section, is drawn apart from a contact side surface of the plate-shaped fin with which the reflare section comes into contact.

Plate-shaped fins of a heat exchanger each include, at circumferential portions thereof defining a notch in which a heat transfer tube having a flattened shape is disposed, fin collars formed by being raised from the circumferential portions. Each of the fin collars includes, in a position that faces a long axis side surface of the heat transfer tube, at least one reflare section bent in a direction opposite to the side surface. At least one of the reflare sections defining fin pitches between the adjoining plate-shaped fins is formed so that a reflare tip portion, which is a tip portion of the reflare section, is drawn apart from a contact side surface of the plate-shaped fin with which the reflare section comes into contact.

What is described is a method for manufacturing an electrical heating device, wherein electrical heating resistors are disposed in tubes of an extruded profile, and openings are cut into a plate of the extruded profile connecting the tubes. According to this disclosure, fastening sections of the extruded profile are plastically deformed and, by means thereof, heat sinks are fastened on the extruded profile. A corresponding electrical heating device is also described.

What is described is a method for manufacturing an electrical heating device, wherein electrical heating resistors are disposed in tubes of an extruded profile, and openings are cut into a plate of the extruded profile connecting the tubes. According to this disclosure, fastening sections of the extruded profile are plastically deformed and, by means thereof, heat sinks are fastened on the extruded profile. A corresponding electrical heating device is also described.

A flat heat transfer tube is used for a cross fin tube type heat exchanger including the flat heat transfer tube having a bending portion and a plurality of holes extending in a direction parallel with an axis direction of the flat heat transfer tube, and a plurality of plate fins bonded by welding to the flat heat transfer tube, wherein an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a small curvature during bending is larger than an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a large curvature during bending in a cross section of a portion of the flat heat transfer tube which corresponds to the bending portion before bending.

A flat heat transfer tube is used for a cross fin tube type heat exchanger including the flat heat transfer tube having a bending portion and a plurality of holes extending in a direction parallel with an axis direction of the flat heat transfer tube, and a plurality of plate fins bonded by welding to the flat heat transfer tube, wherein an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a small curvature during bending is larger than an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a large curvature during bending in a cross section of a portion of the flat heat transfer tube which corresponds to the bending portion before bending.

Methods for expanding a tube to create a tight fit or an interference fit with one or more fins for the manufacture of a heat exchanger are disclosed. The methods can include providing an internal pressure to the tubes in a successive pulsing manner with each pulse having a short duration. The methods can include creating a temperature differential between the bend sections of the tubes and the straight sections of the tubes such that the bend section has a lower temperature than the straight sections. The methods can include creating an external pressure differential between the bend sections of the tubes and the straight sections of the tubes such that the external pressure acting on the bend sections is greater than the external pressure acting on the straight sections.

A method for manufacturing a heat exchanger is provided. The heat exchanger includes a plurality of plate-like fins that are stacked with a predetermined fin pitch, and a plurality of flat heat exchanger tubes that are disposed with a predetermined spacing from one another along the longitudinal direction of the plate-like fins and extend through the plate-like fins along the stacking direction. The plate-like fins each have a plurality of notches provided in an end portion along the long side. The plate-like fins have a shape corresponding to the cross-sectional shape of the flat heat exchanger tubes, and the flat heat exchanger tubes are inserted into the notches. The manufacturing method includes disposing the flat heat exchanger tubes with a predetermined spacing from one another, and attaching the plate-like fins to the flat heat exchanger tubes one by one by inserting the flat heat exchanger tubes into the notches of each of the plate-like fins.