An All-Polyamide Intercooler for Turbo-Charged Engines

An all-nylon intercooler for automotive applications has been shown to be possible. The heat rejecting element (cooling core) can be made employing the latest developments in plastic tubing, and the joining of the tanks to the tubes can be accomplished by advanced plastic welding techniques. The resultant part is similar in performance and environmentally robust compared to the aluminum parts made today. This paper will discuss assembly techniques and thermal performance, including test data and results.

Increasing the robustness of the design is the recent development of extrusion grade polyphthalamide plastic tubing. The feasibility of production has been enhanced by the commercialization of laser welding of plastics using diode lasers. Computer modelling of the heat exchange process shows that the thermal resistance of a thin plastic tube is not a major problem when compared to metal tube; it is the boundary layers between the tube material and the fluids which are the major components of the thermal resistance.

The advantages of a plastic Intercooler include the following: corrosion resistance; mechanical robustness (no fatigue failures); lighter weight and potential for lower cost. Metal intercoolers today are primarily aluminum alloys which contain special alloy to support the brazing process used in manufacture. Thin-walled metal alloys have potential to corrode very quickly and aluminum alloys suffer from a finite fatigue life. Most plastics do not corrode when exposed to the normal automotive environment: salt water, antifreeze and lubricants.