A Hard Look at New Cooling Systems for Clean Diesel Engines
OEMs Face Significant Changes,Aggressive Deadlines

Carl Kiser spoke at an environmental symposium in Tokyo. Kiser is renowned for pioneering work on charge air coolers. His work encompasses a deep understanding of combustion processes as well as turbochargers and cooling systems.The crux of Kiser’s presentation in Tokyo was to sound an alarm that OEM truck makers will need to make significant changes in their choices of heat exchangers and that they are facing aggressive deadlines.

New Designs of Charge Air Coolers Increase Performance and Durability (Two Parts)

Part 2
Laboratory Testing Aids in Design Improvements

The testing of heat exchangers for performance and durability is critical function. Durability testing is especially important in the development of CACs made of brazed copper-brass. Until very recently, nearly all CACs were made from aluminum. In the last few years,however, thanks in a large part to the work performed at the Brazing Center,a large number of practical copper-brass CAC designs have been developed.

New Designs of Charge Air Coolers Increase Performance and Durability (Two Parts)

Part 1
Laboratory Testing Verifies Claims of Durability and Efficiency

Experiments Demonstrate Durability of Brazed Brass Joints
Fatigue Testing at Various Temperatures Proves Superiority of Copper-Brass for Heat Exchanger Applications

Fatigue is a process by which a material is weakened by cyclic loading. The fatigue stress may be below the ultimate tensile stress, or even the yield stress of the material, yet still cause catastrophic failure. Recently, Anders Falkenö conducted an important series of experiments at the Brazing Center of Luvata Sweden AB in Västerås, Sweden. An apparatus was constructed that was capable of fatigue testing at temperatures up to several hundred degrees Celsius. Falkenö and his associates then measured fatigue failures rates of components made from brazed copper-brass, soft-soldered copper-brass, silver-brazed copper-brass and brazed aluminum.

CuproBraze Proves Versatile in the Design of Heat Exchangers
Key Advances Include “One-Shot” Brazing and New Tube Designs

CuproBraze has long been considered a versatile and flexible materials system. Typically, heat exchanger cores of different sizes and designs are processed on the same production line, unlike other processes such as brazed aluminum. For the latter, because of the difficulty of establishing the correct processing parameters, high volume production lines dedicated to identical products are the rule. For the CuproBraze process, flexible manufacturing is the rule. The underlying reason why the CuproBraze process is suitable for flexible manufacturing is that it allows for more latitude or leeway in temperature cycling than other processes. In other words, the temperature cycle that melts the brazing material can be varied significantly without damaging the bulk metals. This simple fact has important consequences for the production environment as well as design.