Review of polymers for heat exchanger applications: Factors concerning thermal conductivity

•Thermoplastics are promising for heat exchangers due to their corrosion resistance, low density and lower-cost processing.•Polymer thermal conductivity can be enhanced through addition of conductive filler, such as carbon or metal particles.•Particle type, size, shape, and compounding method affect composite thermal and mechanical properties.•Highly filled polymer composites encounter processing challenges limiting design options for thermoplastic heat exchangers. Polymeric materials hold several advantages over metal components in heat exchangers such as cost savings, lighter weight and corrosion resistance. However, it is challenging to engineer plastics with good heat transfer characteristics, processability and required strength. Neat polymer resins have inferior mechanical and thermal properties relative to metals, requiring careful consideration of the entire heat exchanger system from materials to system design, to achieve sufficient performance. This review summarizes the physical parameters governing polymer and composite thermal conductivity, as well as the latest research on augmenting thermal conductivity. Highly filled composites containing carbon or metal have achieved thermal conductivity an order of magnitude higher than that of neat polymers. The effects of critical additive characteristics, such as interfacial compatibility, filler shape factor, loading level and processing technique, are reviewed. In addition to lower material costs, high volume processing technologies such as injection molding and extrusion are responsible for the cost savings of polymers over metals. Thus, the manufacturing considerations for the most promising high thermal conductivity polymer composites are also reviewed.