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<p>To research the heat dissipation technology of the International Thermonuclear Experimental Reactor (ITER) deflector, a new type of composite heat transfer tube (CHTT) was presented. Twisted tape (TT) with twist ratios(<i>y</i>) of 2, 5 and 8 were inserted into the internally ribbed tube (IRT) with pitches (<i>t</i>) of 1.5 and 2&#xa0;mm to form the CHTT. Supercooled flow boiling heat transfer experiment was carried out in plain tubes (PT), tubes inserted with twisted tape (TWTT), internally ribbed tube (IRT) and CHTT. The hydraulic parameters covered mass fluxes(<i>G</i>) from 992 to 4960&#xa0;kg m<sup>−2</sup> s<sup>−1</sup>, pressures (<i>P</i>) range of 0.4 to 2&#xa0;MPa, the inlet subcoolings of 87.01–119.21&#xa0;°C and the heat fluxes (<i>q</i>) of 1 to 17.2&#xa0;MW m<sup>−2</sup> for vacuum adiabatic conditions. The results revealed that firstly, the coupling structure of TT inserts and internal rib could strengthen the heat transfer characteristics in the subcooled flow boiling state than the individual technique. Meanwhile, it was obtained the best heat transfer performance and highest performance evaluation criterion (PEC) from the CHTT with <i>y</i> = 2 and <i>t</i> = 2&#xa0;mm. Secondly, the effects of <i>y</i>, <i>G</i> and <i>P</i> on heat transfer characteristics were analyzed in CHTT. Heat transfer coefficient (<i>h</i>) was positively proportional to the <i>G</i> but inversely proportional to the <i>y</i> and <i>P</i>. The influences of <i>G</i> and <i>P</i> on onset of nucleate boiling (ONB) point were also discussed in detail. Lastly, based on the results of the present experimental data, a new correlation for Nusselt number (<i>Nu</i>) was developed for predicting the heat transfer characteristics of CHTT within ± 10% prediction error. The mean absolute error (MAE) and the root-mean-square error (RMSE) were 4.03% and 5.04%, respectively, associated with the new correlation.</p>

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Studies on the heat transfer and pressure drop characteristics in compound heat transfer tubes for subcooled flow boiling

  • 期刊论文

  • 发表日期：

    2025年6月19日

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  • Shaobin Chen,
  • Shiming Sang,
  • Guangjin Qin

摘要

To research the heat dissipation technology of the International Thermonuclear Experimental Reactor (ITER) deflector, a new type of composite heat transfer tube (CHTT) was presented. Twisted tape (TT) with twist ratios(y) of 2, 5 and 8 were inserted into the internally ribbed tube (IRT) with pitches (t) of 1.5 and 2 mm to form the CHTT. Supercooled flow boiling heat transfer experiment was carried out in plain tubes (PT), tubes inserted with twisted tape (TWTT), internally ribbed tube (IRT) and CHTT. The hydraulic parameters covered mass fluxes(G) from 992 to 4960 kg m−2 s−1, pressures (P) range of 0.4 to 2 MPa, the inlet subcoolings of 87.01–119.21 °C and the heat fluxes (q) of 1 to 17.2 MW m−2 for vacuum adiabatic conditions. The results revealed that firstly, the coupling structure of TT inserts and internal rib could strengthen the heat transfer characteristics in the subcooled flow boiling state than the individual technique. Meanwhile, it was obtained the best heat transfer performance and highest performance evaluation criterion (PEC) from the CHTT with y = 2 and t = 2 mm. Secondly, the effects of y, G and P on heat transfer characteristics were analyzed in CHTT. Heat transfer coefficient (h) was positively proportional to the G but inversely proportional to the y and P. The influences of G and P on onset of nucleate boiling (ONB) point were also discussed in detail. Lastly, based on the results of the present experimental data, a new correlation for Nusselt number (Nu) was developed for predicting the heat transfer characteristics of CHTT within ± 10% prediction error. The mean absolute error (MAE) and the root-mean-square error (RMSE) were 4.03% and 5.04%, respectively, associated with the new correlation.