Sizing a corrugated tube heat exchanger for a high-viscosity fluid is different from sizing one for water or a light hydrocarbon, because viscosity changes both the flow regime inside the tube and the achievable pressure drop budget. Getting this wrong either undersizes the heat transfer area or drives pumping costs far above what the process can tolerate.
Why Viscosity Changes the Design Basis
Viscous fluids are more likely to stay in laminar or transitional flow at typical process velocities, which reduces the heat transfer coefficient compared to a turbulent, low-viscosity fluid. Corrugated tubes help here because their geometry promotes turbulence at lower Reynolds numbers than a straight tube, partially offsetting the viscosity penalty.
Balancing Pressure Drop Against Turbulence
Because corrugation increases friction factor, a viscous fluid pushed through a corrugated tube at high velocity can quickly exceed the available pump head. Sizing correctly means finding the velocity that achieves turbulent, self-cleaning flow without exceeding the plant’s pressure drop allowance, which usually requires iterating tube length, diameter, and corrugation pitch together.
Fouling Behavior in Viscous Service
Viscous streams often carry suspended solids or have a tendency to form deposits at low wall shear, which is the exact failure mode corrugated tubes are designed to avoid. A correctly sized corrugated tube exchanger can maintain performance on viscous, fouling-prone fluids for far longer than a straight-tube unit of the same duty.
Getting the Sizing Right
Viscosity-driven sizing is not something to estimate from a generic chart. GreyTec’s corrugated tube heat exchangers are sized against actual process rheology data by our engineering and consultancy team, so the final design matches the real fluid behavior rather than a textbook assumption.