A moving-boundary based dynamic model for predicting the transient free convection and thermal stratification in liquefied gas storage tank
A moving-boundary based dynamic model for predicting the transient free convection and thermal stratification in liquefied gas storage tank
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DOI：
10.1016/j.ijthermalsci.2020.106690
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发表时间：
2021-02
影响因子：
4.5
通讯作者：
Zhongdi Duan;Haoran Sun;Cheng Cheng-Cheng;Wenyong Tang;Hong-xiang Xue
中科院分区：
文献类型：
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作者：
Zhongdi Duan;Haoran Sun;Cheng Cheng-Cheng;Wenyong Tang;Hong-xiang Xue
由于不可避免的热泄漏或突如其来的热冲击，液化气体储罐经常发生热分层现象，对设备安全有重要影响。为了预测液化气的热分层，建立了液化气储罐内热力学过程的综合动力学模型。在该模型中，储罐壁面附近的瞬时自由对流由一组积分方程组采用移动边界法模拟，热分层根据自由对流和界面热质传递的耦合效应来预测，储罐内的压力恢复由液化气的热非平衡响应来计算。模型预测与实验结果的比较表明，在不同热流密度和液体填充水平下，热分层和压力响应的趋势是一致的。结果表明，在储罐升温初期，边界层的发展促进了自由对流，而热层结的发展则阻碍了自由对流的发展；随着外部热流密度的增加，热力层结的穿透时间缩短，而以等效热扩散率表示的无量纲穿透时间在不同的外部热流密度下几乎保持不变。
Thermal stratification occurs frequently in liquefied gas storage tank due to inevitable heat leak or unexpected thermal attack, and has vital influence on equipment safety. For predicting the thermal stratification of liquefied gas, a comprehensive dynamic model of the thermodynamic process in liquefied gas storage tank is proposed in this paper. In the model, the transient free convection in the vicinity of tank walls is simulated by a set of integral equations using the moving boundary method; the thermal stratification is predicted based on the coupling effects of the free convection and interfacial heat-mass transfer; the pressure build-up in storage tank is calculated according to the thermal non-equilibrium response of the liquefied gas. Comparisons of model predictions and experimental results show consistent trends of the thermal stratification and pressure response under different heat fluxes and liquid fill levels. The results indicate that the free convection is enhanced by the development of boundary layer at the initial phase of tank heat-up, and subsequently impeded by the thermal stratification development; the penetration time for thermal stratification will be shortened with the increase of external heat fluxes, while the dimensionless penetration time expressed by the equivalent thermal diffusivity maintains almost constant under various external heat fluxes.