石墨泡沫/石蜡储热装置的凝固过程分析

Solidification process analysis of a heat storage device containing graphite foam and paraffin

石蜡相变材料的导热系数较小,严重影响了其传热速率和凝固速率。通过对填充石墨泡沫/石蜡的储能系统进行凝固过程的模拟,确定了石墨泡沫对相变储能系统性能的影响。研究结果表明石墨泡沫不仅大大缩短了相变凝固时间,也使储能系统的温度分布更加均匀;通过分析冷却水进口速度和温度对复合相变材料的凝固过程的影响,说明随着冷却水进口速度的增大和温度的降低,传热速率加快,凝固时间缩短。分析了复合材料相变区的自然对流对相变过程的影响,模拟结果证明自然对流能在一定程度上加快相变材料的凝固过程。

Paraffin wax based phase change material（PCM） has a low thermal conductivity, which may significantly affect the heat transfer and solidification rates. Simulations are carried out to investigate the solidification behavior of a paraffin based thermal storage device containing graphite foam. The results show a more even temperature distribution and a significantly reduced solidification time due to the use of the high thermal conductivity graphite foam. Analyses are performed on the influence of fluid operating conditions including inlet temperature and velocity, on the solidification process of the paraffin/graphite foam. The results demonstrate that the solidification time decreases with increasing the inlet velocity and/or reducing the temperature of cooling water. Moreover, it is found that natural convection of the PCM can accelerate the solidification rate of the PCM.