Experimental and numerical investigation on the flow and heat transfer behavior of double-side heating once-through steam generator with helical tubes
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The double-side heating once-through steam generator with helical tubes adopts a narrow-channel and doublesided heat transfer design, reducing equipment volume and enabling integrated placement inside reactors. A test rig for the double-side heating once-through steam generator with helical tubes was constructed using high-speed cameras to study the bubble flow behavior in the secondary channel at different flow velocities and air void fractions. The Eulerian two-fluid model was employed for simulation of the double-side heating once-through steam generator with helical tubes, validated with experimental data. The results showed that bubbles become flattened upon entry and ascend along the wider side of the channel in a helical pattern. When the air void fraction is relatively high, the bubbles converge into a continuous air zone, which can remove the liquid film and lead to wall drying up along the wider side. The vapor void fraction on the pipe wall exhibits a spiral striped distribution, and the distribution characteristics of the spiral stripes result in different occurrences of wall dryout. Furthermore, the wall temperature exhibits a spiral striped distribution, causing fluctuations in wall temperature and heat transfer coefficient along the length of the pipe and resulting in significant circumferential differences in wall heat flux.
Abstract
The double-side heating once-through steam generator with helical tubes adopts a narrow-channel and doublesided heat transfer design, reducing equipment volume and enabling integrated placement inside reactors. A test rig for the double-side heating once-through steam generator with helical tubes was constructed using high-speed cameras to study the bubble flow behavior in the secondary channel at different flow velocities and air void fractions. The Eulerian two-fluid model was employed for simulation of the double-side heating once-through steam generator with helical tubes, validated with experimental data. The results showed that bubbles become flattened upon entry and ascend along the wider side of the channel in a helical pattern. When the air void fraction is relatively high, the bubbles converge into a continuous air zone, which can remove the liquid film and lead to wall drying up along the wider side. The vapor void fraction on the pipe wall exhibits a spiral striped distribution, and the distribution characteristics of the spiral stripes result in different occurrences of wall dryout. Furthermore, the wall temperature exhibits a spiral striped distribution, causing fluctuations in wall temperature and heat transfer coefficient along the length of the pipe and resulting in significant circumferential differences in wall heat flux.