Numerical analysis on flow and heat transfer performance of sCO2 in a vertical helically U-tube

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer Pub Date : 2025-05-19 DOI:10.1016/j.ijheatmasstransfer.2025.127265

Yunlei Wu , Tingting Ren , Lu Huang , Xiantao Zhang , Yingni Yu , Peng Liu

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Abstract

Developing compact exchanger is of great significance for the design of efficient supercritical carbon dioxide (sCO₂) cycles. In this study, a vertical helically U-tube (VHUT) is proposed and the numerical model is established to investigate flow and heat transfer performance (FHTP) of sCO₂ in VHUT. Flow pattern and heat transfer mechanism are analyzed in detail though comparing with vertical U-tube (VUT). The results indicate that vortex is generated because of the centrifugal force inducing by helix structure, and the elongate local high temperature areas are appeared on the inside wall of helix structure. In addition, the heat transfer deterioration is almost completely suppressed. Consequently, the average heat transfer coefficient (h_avg) of VHUT is significantly enhanced by 46.49 %-56.97 % when compared to that of VUT, accompanied by 41.65 %-1785.57 % increase in pressure drop per unit length (∆P_u). Moreover, the effect of geometric parameters including coil diameters (D), pitches (p) and bend diameters (d_bend), operational conditions (heat flux q, pressure P, mass flux G) on FHTP are examined. Results demonstrate that h_avg increases as decreasing D, p, d_bend and q and increasing G and P, while ∆P_u increases as increasing D, q and G and declining p, d_bend and P.

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二氧化硅在垂直螺旋u型管内流动及传热性能的数值分析

开发紧凑型换热器对于设计高效的超临界二氧化碳循环具有重要意义。本文提出了一种垂直螺旋u型管（VHUT），并建立了数值模型来研究sCO2在垂直螺旋u型管中的流动和换热性能。通过与垂直u型管（VUT）的对比，详细分析了其流态和传热机理。结果表明：涡流是由螺旋结构诱导的离心力产生的，螺旋结构内壁出现了细长的局部高温区；此外，传热恶化几乎完全被抑制。因此，与VUT相比，VHUT的平均换热系数（hag）提高了46.49% ~ 56.97%，单位长度压降（∆Pu）增加了41.65% ~ 1785.57%。此外，还考察了线圈直径(D)、节距(p)、弯头直径（dbend）等几何参数、运行条件（热流密度q、压力p、质量通量G）对FHTP的影响。结果表明，随着D、p、bend、q的减小和G、p的增大，hav增大，而∆Pu随着D、q、G的增大和p、bend、p的减小而增大。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Heat and Mass Transfer 工程技术-工程：机械

CiteScore

10.30

自引率

13.50%

发文量

1319

审稿时长

41 days

期刊介绍： International Journal of Heat and Mass Transfer is the vehicle for the exchange of basic ideas in heat and mass transfer between research workers and engineers throughout the world. It focuses on both analytical and experimental research, with an emphasis on contributions which increase the basic understanding of transfer processes and their application to engineering problems. Topics include: -New methods of measuring and/or correlating transport-property data -Energy engineering -Environmental applications of heat and/or mass transfer