带有空穴的相变胶囊蓄热过程分析

摘要

相变蓄热是一种高效的蓄热方式,为太阳能、风能等可再生能源的高效转化和利用提供了保障.本文建立了带有空穴的相变蓄热胶囊的二维模型,应用Fluent软件中的多相流模型(VOF)和凝固融化模型对带有空穴的相变蓄热胶囊的蓄热过程进行了模拟计算.在计算过程中考虑了空穴、重力及相变材料融化过程中浮升力对蓄热过程的影响,同时分析了外部导热流体的流速、相对于重力方向的流向及由于相变蓄热胶囊不同的排布密度导致的不同阻塞率等因素对相变蓄热胶囊蓄热过程的影响.结果表明:相变蓄热胶囊内部空穴的存在使蓄热过程变缓,适当增加外部导热流体的流速和阻塞率可以加快蓄热过程的进程,而导热流体的流向对蓄热效果的影响很小.研究结果为相变蓄热胶囊研究与应用提供了一定的参考依据.%Phase change energy storage technology is an efficient way of energy storage which guarantees the the efficient conversion and utilization of renewable energy, such as solar and wind energy. A two dimensional model of the encapsulated phase change materials(EPCM)with an air void is developed in this paper. The numerical simulation of the thermal energy storage process was conducted for the EPCM model using the enthalpy-porosity method and volume of fluid method(VOF) of the Fluent software. The effect of gravity,buoyancy-driven convection and the air void in the capsule, on the thermal energy storage process was considered. At the same time, the effect of various velocities and flow directions relative to gravity of the heat transfer fluid(HTF)and the blockage ratios on encapsulated phase change were studied. The results showed that the flow direction of HTF had little effect on the thermal energy storage process. However, the air void in capsule had negative effect on the thermal energy storage process. With the proper ratios of velocity to the blockage, the thermal energy storage process of the EPCM would be accelerated. The results provide a reference for the future research and application of the EPCM.