前驱体液滴在射频感应等离子体中的蒸发和传热传质

Evaporation,Heat and Mass Transfer of the Precursor Liquid Drops in the Radio Frequency-induced Plasma

建立液滴在RF(高频感应)等离子体射流中的运动蒸发模型,模拟前驱体液滴的蒸发、传热和传质。通过时变系统控制方法的质量守恒方程、动量守恒方程和能量守恒方程来预测射频电感耦合等离子体内液滴的运动和蒸发,得到了液滴半径和液滴表面温度的变化以及液滴内部温度分布。研究结果表明:随着液滴初始尺寸的增大,在热等离子体低温区的停留时间越长,液滴表面缓慢而均匀的受热,因此表面溶质浓度到达饱和浓度的时间较长,半径变化率变小。液滴初始入射速度越大,所经历的环境温度越高,液滴表面蒸发速度越快,半径变化越小,溶质结晶析出所需时间越短。

A movement and evaporation model for liquid drops in a radio frequency-induced plasma jet flow was established to simulate the evaporation,heat and mass transfer of the precursor liquid drops. According to the mass,momentum and energy conservation equations,a method for controlling time-changing systems was used to predict the movement and evaporation of the liquid drops inside the plasma induced and coupled by radio frequencies and obtain the changes in the radii of the liquid drops and temperature on the surface of liquid drops as well as temperature distribution inside the liquid drops. With an increase of the initial sizes of the liquid drops and their residence time duration in the low temperature zone of the hot plasma,the surface of the liquid drops will be slowly and uniformly heated,thus the time required by the surface solute concentration to reach its saturated concentration becomes longer and the changing rate of the radius smaller. With an increase of the initial speed of the liquid drops and the environmental temperature experienced by the liquid drops,the evaporation speed of the liquid drops on the surface becomes quicker,the change in the radius smaller and the time required by the solute to be crystallized and separated becomes shorter.