分形理论结合相变动力学的冷表面结霜过程模拟

Simulation of frost formation process on cold plate based on fractal theory combined with phase change dynamics

运用分形理论并结合相变动力学模拟冷表面上结霜过程.在相变动力学基础上成功模拟了结霜初始阶段水蒸气在冷表面上凝结、液滴生长及冻结过程,随后运用分形理论的有限制的扩散凝聚(diffusion limited aggregation,DLA)模型模拟了霜晶在冻结液滴表面上的形成生长过程.模拟结果与实验结果取得良好的一致,模拟过程中凝结液滴出现及冻结的时间与实验结果几乎完全符合;液滴冻结之前其表面接触半径随时间变化的模拟结果与实验结果基本一致,同时模拟霜层厚度与实验测得霜层厚度也非常接近.研究结果对于探讨分形理论与动力学理论的结合方法具有一定的指导意义,对于建立一种更合理、精确的结霜模型提供了可靠的理论基础.

Simulation of frost formation process on cold surface is carried out based on fractal theory combined with phase change dynamics.Before frosting,the phenomena of vapor condensation,droplet growth and frozen on cold plate are successfully simulated based on phase change dynamics and then a fractal simulation of the frost formation and growth process over the frozen droplets is carried out based on diffusion limited aggregation （DLA） model.The simulation results accord well with the experimental results.The time when the condensation droplets are present and frozen on the surface during simulation process is nearly the same as the experimental result.Before the droplets are frozen,the trend that the surface contact radius of the droplet varies with condensation time is similar to actual one.The simulation results also show that the thickness of frost layer is nearly equal to the measured value.By that means,the feasibility of this method of simulating the frost formation is verified and the new attempt made to foster the combination between fractal theory and phase change dynamics is of great significance.This study also provids a foundational theory work for a more reasonable and accurate frosting process model.