Comparative analysis of thermal hydraulics in once-through steam-generating channels of helical and straight tubes

This study presents a comparative analysis of the performance of helical and straight-tube steam-generating channels heated by liquid metals. In the straight-tube model, an unsteady heat transfer crisis was observed. Under specific operating conditions, dead zones were documented in both the economizer and superheater sections. The unsteady heat transfer crisis can be eliminated by installing throttling devices at the tube inlet, while the dead zones can only be eliminated by intensifying heat transfer. One approach to enhancing heat transfer is the use of helical tubes. In the helical steam-generating channel, no thermohydraulic instability was detected during longitudinal flow of the coolant along the heat exchange tubes. The findings indicate that helical steam-generating tubes exhibit a substantially higher efficiency when operated with transverse flow than with longitudinal flow.