Plastics cannot conduct heat very well. They can however, transfer heat extremely well when it is below a certain thickness.

Plastics cannot be used as an extended surface (fin) because they do not conduct heat well.

Wall resistance is a very small percentage of overall heat transfer resistance.

The heat transfer coefficient of a gas flowing past a solid surface is about two orders of magnitude less then that of a liquid.

Overall Resistance to Heat Transfer:

Water side                                                     Wall                                      Air side
0.036mm Alu      5.0E-3 (6.94%)                   9.0E-6 (0.01%)                         6.7E-2 (93.05%)
0.02mm   Nylon  5.0E-3 (6.5%)                     4.4E-3 (6.5%)                           6.7E-2 (87.7%)

Overall Heat Flux:           Alu = 1250 Btu/hr ft2        Nylon = 1178 Btu/hr ft2

Thermal Conductivity:  130/0.15 = 867x   but, heat flux only 6.1% greater

Conductive Resins can increase thermal conductivity ten-fold therefore nylon ---> 1243 Btu/hr ft2    (only 1% greater)

Wall resistance is a function of thermal conductivity of the material, wall thickness and effective wall area.  Therefore we make use of thin-walled nylon film &/or tubing and increase the primary heat transfer area within a given volume.

Chemical compatibility will depend on what material the exchanger is made from.

Most PolyCoil exchangers are made from Polyamide (Nylon) and are compatible with:

• City Water / Sea Water / Distilled water
• Salts
• Hydrocarbons / Oils
• Propylene Glycol
• Ethylene Glycol (<90% solutions)

The PolyCoil Heat Exchanger is built from small special nylon tubes with thin walls and has a comparable thermal performance as a conventional aluminum Heat Exchanger. A PolyCoil Heat Exchanger keeps its performance however after many years, this as a Aluminum Heat Exchanger looses already 10% of its efficiency after a few months as a result of corrosion and fowling. As a result of the anti-fouling and corrosion resistance of the PolyCoil Heat Exchanger a lot of energy can be saved compared to a Aluminum Heat Exchanger.