An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical sliding-pressure operation once-through boiler |
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Authors: | Tang Renhu Yin Fei Wang Haijun and Chen Tingkuan |
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Affiliation: | (1) The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049, China |
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Abstract: | Within the pressure range of 9–28 MPa, mass velocity range of 600–1 200 kg/(m2·s), and heat flux range of 200–500 kW/m2, experiments were performed to investigate the heat transfer to water in the inclned upward internally ribbed tube with an
inclined angle of 19.5 degrees, a maximum outer diameter of 38.1 mm, and a thickness of 7.5 mm. Based on the experiments,
it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at
the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure,
the temperature difference between the wall and the fluid increased near the pseudo-critical temperature, but the increase
of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure is closer
to the critical pressure, the temperature difference between the wall and the fluid increased greatly near the pseudo-critical
temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated
near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Because the rotational
flow of the internal groove reduced the effect of natural convection, the internal wall temperature of internally ribbed tube
uniformly distributed along the circumference. The maximum internal wall temperature difference of the tube along the circumference
was only 10 degrees when the fluid enthalpy exceeded 2 000 J/g. Considering the effect of acute variety of the fluid property
on heat transfer, the coreelation of heat transfer coefficient on the top of the internally ribbed tube was provided.
Translated from Proceedings of CSEE, 2005, 25(16): 90–95 译自: 中国电机工程学报] |
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Keywords: | thermal power engineering heat transfer supercritical pressure boiler internally ribbed tube departure from nucleate boiling |
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