In this work, discrete double inclined ribs (DDIR) are introduced into the horizontal flow of supercritical R134a to improve the thermal performance of vapor generators in the trans-critical Organic Ranke Cycle. Effects of operating and geometric parameters are investigated after model validation against experimental data. Results show that DDIR are adaptable to changes in operating conditions because spiral flow maintains the dominant position of forced convection heat transfer. DDIR enhance the PEC of horizontal ST by at least 70% and reduce circumferential thermal non-uniformity by up to 90%. Rib pitch has the most significant effect on heat transfer, followed by rib height and inclination angle. The optimal values for the three geometric parameters are 20 mm, 0.8 mm, and 60°. Finally, the mechanism of rib-induced enhancement is analyzed. Average heat transfer is improved by the strengthened mixing between bulk and near-wall fluid instead of suppressing the buoyancy effect. DDIR-induced enhancement is superior to subcritical cases owing to the integral effect of sharp variations in specific heat at supercritical conditions.

在这项工作中，离散双斜肋 (DDIR) 被引入到超临界 R134a 的水平流中，以提高跨临界有机朗克循环中蒸汽发生器的热性能。在根据实验数据验证模型后，研究操作参数和几何参数的影响。结果表明，DDIR 适应操作条件的变化，因为螺旋流保持强制对流传热的主导地位。DDIR增强PEC水平 ST 至少降低 70%，并将周向热不均匀性降低高达 90%。肋间距对传热的影响最显着，其次是肋高度和倾角。三个几何参数的最佳值为 20 mm、0.8 mm 和 60°。最后，分析了肋骨增强的机制。通过加强散装流体和近壁流体之间的混合而不是抑制浮力效应来改善平均传热。由于超临界条件下比热急剧变化的整体效应，DDIR 诱导的增强优于亚临界情况。