基于分形论的深冷翅片管气化器结霜数值模拟

利用分形理论DLA模型,建立翅片管气化器深冷表面霜层生长模型,通过控制程序循环次数模拟了深冷表面霜层生长不同阶段。结合实验观测到的深冷表面霜层生长过程,从分形维数和霜层密度两个方面验证数值模拟的合理性。结果表明,结霜初期随着初始霜枝晶上不断长出分枝晶,霜层密度随厚度的增大而减小,且深冷表面上霜层分形维数较一般冷表面分形维数大,说明深冷表面霜的生长更加复杂,充满空间的能力更大。这对进一步理解空温式深冷翅片管气化器表面结霜机理,探索有效除霜方法,提高气化器换热特性有重要意义。

Numerical Simulation on Frost of Cryogenic Finned-Tube Vaporizer Based on Fractal Theory

A model of frost formation and growth on the cryogenic surface of finned-tube vaporizer was proposed based on Diffusion Limited Aggregation (DLA) model, and through controlling the times of program running, the simulation on the different stages of frost formation and growth on the cryogenic surface was carried out in this paper. Combined with frost formation and growth on the cryogenic surface obtained by experimental observations, the rationality of numerical simulation was verified from fractal dimension and frost layer density. The result shows that frost layer density decreases with the increase of thickness in the early frosting stage as initial frost dendrite constantly grows branch crystal, and the fractal dimension of frost layer on the cryogenic surface is larger than the fractal dimension of frost layer on the general cold surface. The frost growth on the cryogenic surface is more complex, and it has a bigger ability of filling space. This investigation is significant to further understand the frosting mechanism on the surface of cryogenic finned-tube vaporizer, explore the effective defrosting methods, and enhance heat transfer characteristics of the vaporizer.