熔渣颗粒空冷相变换热的三维数值模拟

利用VOF方法结合凝固和熔化模型对熔渣颗粒在空气流中的冷却相变过程进行了三维数值模拟，讨论了熔渣颗粒直径和空气速度对冷却凝固过程演变的影响。结果表明：空冷方法能够实现熔渣颗粒表面的快速凝固成型，但同时也造成了颗粒内部的非均匀凝固。熔渣直径越小，完全凝固时间越短；空气流速越大时， 其表面换热越强， 完全冷却时间越短。颗粒初温为1673.15 K、直径为0.5~2 mm，风速为1~5 m·s^-1条件下熔渣颗粒在2 s内释放出全部凝固热，后续空气最高温度能达到900 K以上。

Three-dimensional simulation of solidification and heat transfer for air-cooling molten blast furnace slag droplet

Solidification and heat transfer of an air-cooling molten blast furnace slag droplet is numerically simulated by the volume of fluid (VOF) method coupling with the solidification/melting model. The effects of droplet diameter and air velocity are investigated on the dynamic solidification evolution and heat transfer of the slag droplet, respectively. The results show that it is available for the air-cooling technique to realize fast solidification of the molten slag droplet surface, while non-uniform solidification evolution is found to occur inside the slag droplet. The solidification process of the molten slag droplet is expedited with decreasing droplet diameter and increasing air velocity due to the enhancement in the heat transfer. The optimum slag droplet diameter and air velocity should be comprehensively determined for a practical heat recovery system. As for a droplet with diameter of 0.5-2 mm at initial temperature of 1673.15 K, it releases the heat of solidification within 2 s under air velocity of 1-5 m·s^-1, and the highest air outflow temperature as a result can reach above 900 K.