内部温度及浓度梯度对液滴蒸发模型精度的影响

Effects of Internal Temperature and Concentration Gradient on the Precision of the Droplet Evaporation Model

为研究液滴蒸发过程中内部温度及浓度梯度对蒸发速率计算的影响,该文建立快速混合模型及有效扩散模型。采用两种模型分别计算不同工况下的蒸发过程,得到快速混合模型的相对误差。结果表明,内部温度梯度对蒸发速率计算的影响主要体现在初始阶段,而对蒸发总时间的影响较小。对于含盐液滴的蒸发,虽然析盐之前液滴内部可能具有较大浓度梯度,但对蒸发速率的计算影响较小。总体来看,计算纯水液滴在700℃以下环境中蒸发总时间时可采用快速混合模型;而有效扩散模型可以更好地处理含盐液滴蒸发时盐分析出的过程。

To study the effect of internal temperature and concentration gradient on the evaporation rate calculation, a rapid mixing model and an effective diffusion model are established. The evaporation process under different conditions are calculated using the two models, and the relative error of the rapid mixing model is presented. It shows that the internal temperature gradient has an impact on the evaporation rate calculation in the initial stage, but it has little effect on the calculation of droplet lifetime. For the evaporation of saline water droplets, although there may exist large concentration gradient inside droplets before salt crystallize, the error of calculated evaporation rate is small. In general, the rapid mixing model can be used to calculate the lifetime of pure water droplets evaporating in an environment below 700℃. When dealing with the evaporation of saline water droplets, the effective diffusion model can calculate the salt crystallizing process more precisely.