Numerical investigation on characteristics and correlation development for supercritical CO2 heat transfer in internally ribbed tubes

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences Pub Date : 2025-09-05 DOI:10.1016/j.ijthermalsci.2025.110256

Xinyi Zhang, Weijie Jiang, Chenshuai Yan, Yan Zhang, Yaying Zhao

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引用次数: 0

Abstract

Internally ribbed tubes (IRT) have a potential to enhance supercritical heat transfer, being regarded as one of the excellent options for heat transfer channels in supercritical heat exchanger. In contrast to internally smoothed tube (IST), the characteristics of supercritical CO₂ (sCO₂) heat transfer in vertical heated IRT is numerically studied in this paper. Numerical results are processed according to the viewpoint of supercritical pseudo-phase transition, including a core liquid-like region in the tube and a vapor-like film near the heated wall. Then, the distribution characteristics of vapor-like and liquid-like phases, thermo-physical properties, and flow parameters are respectively discussed. The mechanism of sCO₂ heat transfer enhanced in IRT is revealed through the thermal resistance R_VLF for vapor-like layer near the heated surface, which reflects the synergistic effects of pseudo-film thickness, vapor-like property, and turbulence intensity on heat transfer. The results show that the level of thermal conductivity, specific heat, and turbulent intensity within and near the vapor-like film formed in IRT are higher than that in IST. As a result, R_VLF corresponding to IRT is also smaller, reducing the heat transport barrier between the heated surface and the core fluid. According to the mechanism of sCO₂ heat transfer enhanced in IRT, we newly develop a modified Dittus-Boelter heat transfer correlation to forecast the heat transfer behavior of sCO₂ (and supercritical water) upward flow in the vertical IRT. The mean relative error, mean absolute relative error, and root mean-square relative error between Nu_pre predicted by the modified correlation and Nu_exp calculated by experimental data are only 2.2 %, 16.0 %, and 23.1 %, respectively. Compared with five typical correlations in existing literature, the new correlation demonstrates the highest prediction accuracy. The present study can provide in-depth insight on supercritical heat transfer in IRT and theoretical guidance for heat exchanger design.

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内肋管超临界CO2换热特性及相关关系的数值研究

内肋管（IRT）具有增强超临界传热的潜力，被认为是超临界换热器中优良的换热通道之一。与内光滑管（IST）相比，本文对垂直加热IRT中的超临界CO2 （sCO2）传热特性进行了数值研究。根据超临界伪相变的观点对数值结果进行了处理，包括管内的核心类液区和加热壁附近的类汽膜。然后分别讨论了类气相和类液相的分布特征、热物性和流动参数。通过近受热面类蒸汽层的热阻RVLF揭示了在IRT中sCO2强化换热的机理，反映了伪膜厚度、类蒸汽性质和湍流强度对换热的协同作用。结果表明，IRT形成的气相膜内部和附近的热导率、比热和湍流强度均高于IST。因此，IRT对应的RVLF也更小，减少了受热表面与核心流体之间的传热屏障。根据sCO2在IRT中强化换热的机理，我们建立了修正的Dittus-Boelter换热关系式来预测垂直IRT中sCO2（和超临界水）向上流动的换热行为。修正相关预测的Nupre与实验数据计算的Nuexp的平均相对误差、平均绝对相对误差和均方根相对误差分别仅为2.2%、16.0%和23.1%。与已有文献中的5种典型相关相比，新相关的预测精度最高。本文的研究可以为深入了解红外热场的超临界传热提供理论指导，并为换热器的设计提供理论指导。

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 Thermal Sciences 工程技术-工程：机械

CiteScore

8.10

自引率

11.10%

发文量

531

审稿时长

55 days

期刊介绍： The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review. The fundamental subjects considered within the scope of the journal are: * Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow * Forced, natural or mixed convection in reactive or non-reactive media * Single or multi–phase fluid flow with or without phase change * Near–and far–field radiative heat transfer * Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...) * Multiscale modelling The applied research topics include: * Heat exchangers, heat pipes, cooling processes * Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries) * Nano–and micro–technology for energy, space, biosystems and devices * Heat transport analysis in advanced systems * Impact of energy–related processes on environment, and emerging energy systems The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.