载气与玻璃微球间热传递系数的影响因素

为实现干凝胶法制备空心玻璃微球工艺中载气与微球间传热过程的有效控制,建立了载气与微球之间综合热传递系数的计算模型,研究了载气环境参数(组分、温度和压力)和微球几何参数(直径和壁厚)对热传递系数的影响。结果表明:在常用的工艺参数范围内,热传递系数对载气温度、压力以及微球壁厚的变化不敏感,但热传递系数随微球直径的增大显著降低、随载气中氦气含量的提高而显著增加,且这种递减趋势随载气中氦气含量的增加而趋于显著。

Effect Factors of Heat Transfer Coefficient Between Hollow Glass Microsphere and Furnace Atmosphere

In order to achieve an effective control of the heat transfer coefficient(h_q)(between) microsphere and furnace atmosphere in the fabrication of hollow glass microsphere by sol-gel technology,the effects of component percentage,temperature and(total) pressure of gas mixture on h_q are studied.Further,the influences of diameter and wall thickness of hollow glass microsphere on h_q are also investigated.The results show that in the range of component percentage,temperature and pressure of gas mixture commonly used in the fabrication of hollow glass microsphere by sol-gel technology,the temperature and total pressure of gas mixture and the wall thickness of hollow glass(micros)phere have little influence on h_q,but h_q significantly increases with the volume fraction of helium in the furnace atmosphere and significantly decreases with increasing of microsphere diameter.