Buoyancy forces consistently improve heat transfer to SCW in IRT at Bo < 3 × 10⁻³.

Rotational flow is the dominant cause for Heat Transfer Enhancement (HTE) in helically IRT.

HTE results from turbulence intensification in the forepart of the log-law region.

HTE also occurs in transversely rib-roughened tubes where no rotational flow exists.

Webb–Narayanamurthy Correlation can accurately predict frictional pressure drop of IRT.