The corrugated surfaces obtained with internal helical ridging has revealed a successful method in enhancing heat transfer in tubes, and therefore, in reducing the heat exchanger size. There is a particular interest in a wide variety of engineering situations, also including heat exchangers for viscous liquids in chemical process and food industry. The helical corrugation has revealed a type of roughness very suitable in dairy products, since fouling reduction.
In the spirally enhanced geometries, the transition to the turbulent flow can occur at Reynolds number values much lower than 2000. This early transition is accompanied by a significant heat transfer enhancement which assumes values between 1.1 and 6 in the Reynolds number range 300-1800.
Immediate advantages of corrugated tubes are shorter process time because of quicker heat transfer, more homogenous thermal treatment because of the mixed capacity, lower fouling levels because of the high turbulence levels generated and longer running times among cleaning periods.
