Thermal Management

It is common practice to use brazed plate-fin and shell-tube heat exchangers in aerospace applications. Unison has focused on the development of innovative, advanced, superior performance heat exchangers such as our “Surface Coolers”.

A major weakness common in all plate-fin heat exchangers is that they are joined by brazing. Brazing creates small voids in the metal-to-metal interfaces. Those voids are inevitable, create structural weaknesses, and more importantly, act as resistances to high heat transfer levels. These braze voids have also been attributed to performance variations from one supposedly identical heat exchanger to the next. Furthermore, the braze alloys used are often brittle in nature which makes the forming of the heat exchanger into any shape other than cubic or “brick” shape to be difficult and expensive. As an alternative to this conventional brazed plate-fin style of heat exchanger, Unison-Dayton has developed an alternative known as a conformal “integrally finned extrusion” ACOC “surface cooler” heat exchanger. The “integral” fins that make up the heat exchanger’s extended surface are mechanically cut from the base metal of the extrusion. Therefore, there are no voids at all to negatively affect the heat transfer or structural performance.

In addition, since no brittle braze is used, the “integrally finned extrusions” can be bent into many non-cubic forms. Thus far, we have formed them in cylindrical, helical, arched, conical and cubic forms. The “integrally finned extrusions” can be used to produce ACOC’s in either the conventional or “surface cooler” configuration.

Extrusions Offer Extreme Flexibility In Design Including Fin Density, Fin Height, Oil Port Size and Overall Geometry

Further, in a surface mount configuration, there is significantly less air flow constriction as compared to a traditional brick type cooler. This results in a demonstrated reduction in specific fuel consumption. This benefit is in addition to its reduced weight, and greater design & mounting flexibility.