倾斜棒束通道过冷沸腾传热模型研究. (Chinese)

Study on Sub-cooled Boiling Heat Transfer Model in Inclined Rod Bundle Channel. (English)

Due to the existence of phase transition, sub-cooled boiling, as an efficient heat exchange mode, is widely used in most heat exchange equipment. Under specific application conditions, the rod bundles will work under inclined conditions. For example, some heat exchangers need a certain inclination angle for installation due to space constraints, different positions in the elbow area of the U-tube steam generator have different inclination angles, and some rod bundles in marine nuclear power floating platforms or ship nuclear power plant also experience long-term inclination under ocean conditions with large-period waves. Therefore, it is crucial to research the sub-cooled flow boiling heat transfer characteristics on the surface of inclined heating rod bundles. In this paper, combining with the content of bubble dynamics and according to the characteristics of inclined bubble detachment, the bubble detachment criterion under inclined conditions was formulated. The force calculation of the bubble was then carried out, and the correlation parameters such as the diameter of the bubble detachment were obtained. In the calculation process, it is considered that the bubbles detachment judgment condition on the upper surface of the inclined heating rod bundles is that the force balance in the direction of bubble buoyancy is broken. Additionally, under inclined heating rod bundles, a calculation model of the heat flux on the heating wall was also established adopting the wall heat flux partitioning model in conjunction with the bubble dynamics. Traditional wall heat partitioning models are mostly based on vertical or horizontal heating walls, however, the applicability for inclined conditions is still being investigated. In comparison to traditional heating conditions, the bubble behavior on the heating surfaces of the inclined heating rod bundles is different, resulting in a different heating transfer process. Therefore, the traditional wall heat partitioning model was improved to adapt to the working conditions of inclined heating rod bundles. The calculation results of the model show that 81.25% of the data can be captured within ±20% of the error line, and the average relative error is roughly 13.07%. The model has good applicability to calculate the heat flux of inclined heating rod bundles. However, the model is more applicable to low sub-cooled boiling than high sub-cooled boiling. During the high sub-cooled boiling, the heat flux calculated by the model is too low, which is because of the slowly rising wall temperature in high sub-cooled boiling. During low sub-cooled boiling, since the change of wall temperature is relatively smaller, the model is more applicable compared with that under high sub-cooled boiling. [ABSTRACT FROM AUTHOR]

摘要:过冷沸腾由于相变的存在导致传热大幅增强而广泛应用于多数换热设备中,棒束中过冷沸腾的应 用十分广泛。在特定应用条件下,棒束会在倾斜条件下进行工作,因此,倾斜加热棒束壁面过冷流动沸 腾传热特性的研究十分重要。本文结合汽泡动力学,根据倾斜工况下汽泡脱离特点,制定了倾斜条件下 汽泡脱离准则,并对汽泡进行受力计算,得到了汽泡脱离直径等相关参数。此外,以力平衡模型作为汽 泡参数计算基础,考虑倾斜壁面汽泡行为特征——只存在脱离汽泡,建立了倾斜棒束壁面热流分配机理 模型,实现了对壁面热流密度的计算。模型计算结果表明,在误差线±20%以内可捕捉81.25%的数据, 平均相对误差约为13.07%。 [ABSTRACT FROM AUTHOR]

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