Abstract: The use of relatively heavy, large profile headers in a heat exchanger are avoided through a header construction wherein headers (20, 22) are formed of header plates (34) tapped with tank plates (36) having a concave surface (38) facing the header plate (34). The header plates (34) include a plurality of flanges (82) directed away from the tank plates (36) surrounding elongated slots (48). Each of the flanges (82) includes a pilot surface (80) extending about the associated slot (48) for receiving the end (90) of a flattened tube (20). The construction prevents the ends (90) of the tubes (28) from entering the header chambers (42) to a location whereat they could disrupt the flow of a heat exchange fluid therein to prevent uniform distribution of the same throughout the associated header (20, 22).

Abstract: Poor brazed joints in a heat exchange caused by improper venting during the brazing process are eliminated through the use of a baffle for disposition in a slot 32 in a tubular header 10, 12 which is formed of a plate-like metal piece having first and second peripheral sections 36, 40 of approximately the same extent. The first section 36 has a size at least as large as the outer dimension of the tubular header 10, 12 while the second section 40 has a size and shape approximately equal to a corresponding interior section of the tubular header 10, 12 and a notch 46 is disposed in the first section 36 and extends inwardly a distance 2t greater than the wall thickness t of the tubular header. The notch 46 provides a vent path during the brazing process which is subsequently filled by the capillary flow of molten braze metal 52 into the bottom 50 of the notch.

Abstract: A tube having a plurality of hydraulically parallel fluid passages for use in a heat exchanger can be made by forming an elongated, undulating insert and disposing the same within a flattened tube. A noncorrosive brazing flux is adhered to at least one of the interior of the tube and the crests on the undulating insert. Braze alloy is also located at the interface of the crests of the insert and the interior wall of the tube. Thereafter, the insert is located within the tube without disturbing the flux and the tube deformed along its length to bring the interior of the tube into contact with the crests on the insert. The assembled tube and insert construction is then heated to braze joints between the interior wall of the tube and the crests of the insert along the entire length of the latter.