The president of IndyCar radiator supplier Mezzo explains the advantages of micro tube technology, how the science is still progressing and why it?s now also finding applications outside of motorsport.
Cooling is paramount in all forms of motorsport, but it?s a delicate balance and too many surfaces will mean an aero disadvantage. This is why in racing where drag reduction is vital, such as IndyCar, solutions like micro tube heat exchangers are always very welcome.

The definition of a micro tube heat exchanger is one that is made using hundreds to many thousands of small tubes, usually stainless-steel, having outer diameters in the range of 0.5-1.0mm. Micro tube heat exchangers can be considered a subset of micro channel heat exchangers, where the characteristic dimension of the fluid channels are small and the surface area/unit volume is high. Exchanging numbers
The scaling laws of micro tube heat exchangers relating heat transfer/volume to tube diameter are relatively straightforward. The surface area/volume of a micro tube heat exchanger scales with 1/Dtube, where Dtube is the outer tube diameter. The heat transfer coefficients on both the inside and outside of the tube also scale with tube diameter (1/Dtube for the case of laminar flow, ~ 1/Dtube0.5 for turbulent flow). ?So, the overall heat transfer coefficient/unit volume (W/K-m3), which is the product of heat transfer coefficient and surface area/unit volume, scales as 1/Dtube1.5 to 1/Dtube2.

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