基于高速膨胀的气体液化成核模型修正

Modification of condensation nucleation model for high-speed expansion gas

关键词:  成核率  ICCT  化学势差  表面张力  高速膨胀 

Key words:  nucleation  internally consistent classical theory  chemical potential difference  surface tension  high-speed expansion

摘要:

当前基于高速膨胀的气体液化研究仍处于理论探索阶段,所用成核模型多为内部一致经典成核理论(ICCT),不过该理论应用于低温真实气体时偏差较大。针对理论推导过程的忽略因素,作如下修正:采用逸度求解化学势差,液滴曲率对表面张力影响的修正优选Tolman模型,状态方程优选SRK、低温表面张力推荐LD公式。将模型修正前后的理论结果与水、烷烃的实验数据对比发现,低温时ICCT预测值偏高,最大偏差3~4个数量级；而修正后偏差可降低1~2个数量级,预测偏差降至2个数量级以内,特别对烷烃类偏差均在1个数量级以下。修正后的模型能获得较好的预测结果,可作为天然气高速膨胀液化研究的成核基准公式。 

Abstract:

The study of condensation for high-speed expansion gas is still on the stage of exploration, and the popular nucleation model may be Internally Consistent Classical Theory(ICCT). However, satisfied results can be gained for real-gas in low temperature. As far as theory’s defects, the model is modified as follows:computing chemical potential difference with fugacity and using Tolman model to solve the relation between droplet curves and surface tension; SRK and LD formula were recommended respectively for state equation and surface tension in low temperature. Compared the modified model and ICCT model with the experiment data, it is found that ICCT predictive value is higher than experiment value about 3-4 order of magnitude while deviation of modified model can be reduced to 1-2 order of magnitude, especially for alkane the deviation under 1 order of magnitude. For modified model, more satisfied results can be gained, it can be recommended as standard formula for the study of nucleation.