Departamento de Ciencias, Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey Campus Estado de México, Atizapán de Zaragoza, Estado de México 52900, México.
Molecules. 2019 Mar 30;24(7):1254. doi: 10.3390/molecules24071254.
Density changes produced by pressure increments during melting of a spherically confined phase-change material have an impact on the thermal energy absorbed by the heat storage unit. Several authors have assumed incompressible phases to estimate the volume change of the phase-change material and the thermal balance at the liquid⁻solid interface. This assumption simplifies the problem but neglects the contribution of density changes to the thermal energy absorbed. In this work, a thermal balance at the interface that depends on the rate of change of the densities and on the shape of the container is found by imposing total mass conservation. The rigidity of the container is tuned through the coupling constant of an array of springs surrounding the phase-change material. This way, the behavior of the system can be probed from the isobaric to the isochoric regimes. The sensible and latent heat absorbed during the melting process are obtained by solving the proposed model through numerical and semi-analytical methods. Comparing the predictions obtained through our model, it is found that even for moderate pressures, the absorbed thermal energy predicted by other authors can be significantly overestimated.
在球型相变材料熔化过程中，压力增量引起的密度变化会影响储能单元吸收的热能。一些作者假设不可压缩相来估算相变材料的体积变化和液-固界面的热平衡。这一假设简化了问题，但忽略了密度变化对吸收热能的贡献。在这项工作中，通过施加总质量守恒，在界面处找到了一个依赖于密度变化率和容器形状的热平衡。容器的刚性通过围绕相变材料的弹簧阵列的耦合常数来调整。通过这种方式，可以从等压状态到等容状态来探测系统的行为。通过数值和半解析方法求解所提出的模型，可以得到在熔化过程中吸收的显热和潜热。通过比较我们模型的预测结果，发现即使在中等压力下，其他作者预测的吸收热能也可能被显著高估。
