纳米颗粒强化相变蓄冷特性的数值模拟（英文）

Numerical analysis on cold storage characteristic of nanoparticle-enhanced phase change material for energy saving

采用Fluen软件对纳米颗粒强化相变蓄冷特性进行了数值模拟,重点分析纳米粒子添加量和Gr数对蓄冷性能的影响,并解释其换热机理。研究结果表明:纳米颗粒的体积分数是影响纳米颗粒强化相变材料结冰时间的一个主要因素,但Gr数对其结冰时间影响不大。对于一给定的Gr数,随着纳米粒子体积分数的增加,结冰时间减少,纳米粒子体积分数为1.0%时,纳米颗粒强化相变材料的结冰时间降低了16.3%。这是由于纳米颗粒强化相变材料具有较高的导热系数。另一方面,由于纳米颗粒强化相变材料融解潜热降低,则纳米颗粒强化相变材料结冰时,每单位质量的纳米颗粒强化相变材料需要的能量较少,所以纳米颗粒强化相变材料具有较高的热释放率,在相变储能应用中具有巨大优势。

The cold storage characteristic of nanoparticle-enhanced phase change material （NEPCM） was investigated by using numerical simulation method with Fluent software. The influence of Grashof num- ber and particle concentration on the cold storage performance was discussed . The numerical results indi- cate that the cold storage characteristic of the NEPCM largely depends on the volume fraction of nanoparti- cles,while exhibits little sensitivity to Grashof number. As the volume fraction increases,the freezing time of the NEPCM is lowered for a given initial Grashof number. The total freezing time of the NEPCM can be low- ered by 16.3% with Cu nanoparticles volume fraction is 1.0%. The reduction of the freezing time is attrib- uted to the higher thermal conductivity of the NEPCM. At the same time,less energy per unit mass of the NEPCM is needed for freezing the NEPCM because of the lower latent heat of fusion.