To enhance the thermal performance of the shell-tube phase change thermal storage equipment, the transient two-dimensional mathematical models of the RT35 melting were established. The transient evolution of temperature and velocity distribution and the effect of the positions of the inner tube on the intensity of natural convection for the RT35 and the melting times were analyzed. The results showed that the evolution process of the liquid fraction of RT35 could be divided into two stages: the natural convection stage and the conduction stage. In the natural convection stage, due to the buoyancy effect, the RT35 with high-temperature flowed upward and convectively heat transferred with the solid RT35 on the upper side of the inner tube, resulting in the promotion of the melting of RT35 on the upper side of the inner tube. With the increase in the eccentricity ratio (ε), the gradual increase in the mass of RT35 on the upper side of the inner tube enhanced the effect of natural convection on the melting of RT35, leading to a significant reduction in melting time. When the heat exchange temperature differences (ΔT) ranged between 9 °C and 21 °C, increasing ε from 0 to 0.8 could shorten the melting time by 87.3 %–89.73 %.

中文翻译：

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自然对流诱导壳管相变蓄热装置石蜡强化熔融模拟

为了提高壳管式相变蓄热设备的热性能，建立了RT35熔化的瞬态二维数学模型。分析了RT35温度和速度分布的瞬态演化以及内管位置对自然对流强度和熔化时间的影响。结果表明，RT35液体部分的演化过程可分为自然对流阶段和传导阶段两个阶段。在自然对流阶段，由于浮力作用，高温的RT35向上流动，与内管上侧的固体RT35进行对流换热，从而促进上侧的RT35熔化内管的。随着偏心比(ε)的增加，内管上侧RT35质量逐渐增加，增强了自然对流对RT35熔化的影响，导致熔化时间显着缩短。当热交换温差（ΔT）在9℃~21℃之间时，将ε从0增加到0.8可以使熔化时间缩短87.3%~89.73%。