Rifled Tubes

Rifled tubes are used in boilers to provide highly energy efficient means of heat transfer. The presence of the internal rifling induces centrifugal forces in the mass flow thereby separating the water from the steam fraction and forcing the water towards the tube wall. As a result of this phenomenon and the increase in internal surface the following advantages accrue:
Improved heat transfer rate even at higher steam quality levels
Very good heat transfer even at low mass flux levels
Reduction in mean metal temperature of the tube wall
Ability to increase heat transfer rate by optimizing rifling geometry