To investigate the effect of heat flux on the enhanced heat transfer in phase change materials (PCMs) composed of copper metal foam (CMF) and paraffin wax (PX), a semi-cylindrical visualized heat storage device with a varied heat flux of 7.3 kW/m, 8.5 kW/m, 9.7 kW/m, and 10.9 kW/m was established in this paper. Moreover, a 3-D mathematical model of composite phase change materials (CPCMs) was established using hybrid grid to study the temperature distribution, imbalance effect, flow, heat transfer mechanisms, and heat storage performance during the melting process. The results showed that the melting time of the CPCMs decreased as the heat flux increased. Compared with a heat flux of 7.3 kW/m, the melting time was shortened by 10.05 %, 20.71 %, and 27.21 %, respectively. In addition, the Rayleigh number (Ra) increased with the increase in heat flux, and the amplitudes of Ra were 1.45×10,1.54×10,1.61×10, and 1.74×10, respectively, which indicated that the higher the heat flux, the larger the amplitudes. Moreover, the heat transfer mechanism during the melting process was dominated by conduction; however, with the increase in heat flux, the maximum flow velocity of the liquid paraffin increased, which caused the proportion of natural convection to increase from 27.80 % to 31.30 %. Hence, the integrated heat transfer coefficient of CPCMs increased from 5.69 W/(m·K) to 5.81 W/(m·K). However, the temperature imbalance effect of the CPCMs was exacerbated, as evidenced by the increased maximum temperature difference in the vertical direction of the center of the CPCMs from 24.7 K to 35.6 K. Besides, the heat storage performance was enhanced. Compared with a heat flux of 7.3 kW/m, the heat storage capacities of the CPCMs increased by 4.21%, 9.46%, and 12.66 % with increasing heat flux, and the heat storage rates of the CPCMs increased by 15.3 %, 34.9 %, and 52.3 %, respectively. Furthermore, the relative error of the overall melting time was 3.4 %, indicating that the model provided reasonable predictions.

中文翻译：

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热流密度对泡沫铜金属复合石蜡熔化过程强化传热机理的影响：实验与模拟研究

为了研究热通量对由泡沫铜 (CMF) 和石蜡 (PX) 组成的相变材料 (PCM) 中强化传热的影响，这是一种具有 7.3 kW 不同热通量的半圆柱形可视化储热装置本文确定了 10.9 kW/m、8.5 kW/m、9.7 kW/m 和 10.9 kW/m。此外，利用混合网格建立了复合相变材料（CPCM）的3D数学模型，以研究熔化过程中的温度分布、不平衡效应、流动、传热机制和蓄热性能。结果表明，CPCM 的熔化时间随着热通量的增加而缩短。与7.3 kW/m的热流密度相比，熔化时间分别缩短了10.05%、20.71%和27.21%。此外，瑞利数（Ra）随着热通量的增加而增大，Ra的幅值分别为1.45×10、1.54×10、1.61×10和1.74×10，表明热通量越高，振幅越大。而且熔化过程中的传热机制以传导为主；然而，随着热通量的增加，液体石蜡的最大流速增加，导致自然对流的比例从27.80%增加到31.30%。因此，CPCM的综合传热系数从5.69 W/(m·K)增加到5.81 W/(m·K)。然而，CPCM的温度不平衡效应加剧，CPCM中心垂直方向的最大温差从24.7 K增加到35.6 K就证明了这一点。此外，蓄热性能也得到增强。与7.3 kW/m热流密度相比,随着热流密度的增加,CPCM的蓄热能力分别提高了4.21%、9.46%和12.66%,CPCM的蓄热率分别提高了15.3%、34.9%、分别为 52.3% 和 52.3%。此外，总体熔化时间的相对误差为3.4%，表明该模型提供了合理的预测。