An improved modular
heat exchanger suitable for automotive applications, and particularly radiators for
heavy duty equipment, and methods for forming the modular
heat exchanger. The modular
heat exchanger construction incorporates a brazed core
assembly composed of flat-type cooling tubes and sinusoidal centers. The ability to use a brazed core
assembly within a modular heat exchanger construction promotes
enhanced heat transfer efficiencies associated with the use of flat tubes and sinusoidal centers, as compared to mechanically-joined round tubes and fins. The required positional tolerances of the tubes for
mating with the remainder of the heat exchanger are maintained within the brazed core
assembly by eliminating core shrinkage attributable to the use of clad aluminum
alloy components to construct the core assembly. In two embodiments, core shrinkage is physical suppressed through the use of an expandable
brazing fixture or the inclusion of sub-headers in the brazed core assembly. In a third embodiment, a clad
slurry containing a
braze alloy is deposited prior to
brazing on a core assembly composed of unclad tubes and centers.