To simulate the non-uniform frost growth in flow direction for humid air flowing through a freezing channel, a 2D numerical frosting model based on dynamic meshes technique is developed in the current work via the secondary development of commercial ANSYS Fluent. The computation domain consists of both frost layer and humid air regions, and the local heat and vapor fluxes at the surface of frost layer are determined by numerical temperature and vapor fraction fields in the humid air region rather than by empirical correlations. The frost layer is treated as a growing packed bed with heat and mass transfer dominated by molecular diffusion, where local absorption coefficient of vapor desublimation and local vapor fraction are both determined by solving the pseudo steady vapor diffusion equation with a source term theoretically. The interface of frost layer and humid air regions is treated as two walls for the iteration of its temperature, of which the humid air side is specified with the temperature equal to the frost-side counterpart and the frost side takes the heat flux including the extra latent heat caused by vapor deposit. User-defined functions are compiled to implement the above treatments to ANSYS Fluent. Frosting experiments in the literature are simulated with the current model for validation. How the profile of frost layer evolves with time in the frosting process is explored. The contours and profiles of velocity, temperature and vapor fraction are presented to discuss the effects of heat and mass transfer on frost formation. Numerical results demonstrate that the proposed CFD model can predict the frost growth and densification with a relative deviation less than 5% compared with experiments. Besides, the computation load of current model is small due to no solution of complex multiphase flow. In addition, dynamic meshes help current model to capture the interface of frost layer and humid air regions accurately.

为了模拟流经冻结通道的湿空气在流动方向上的霜冻不均匀增长，通过商业化ANSYS Fluent的二次开发，在当前工作中开发了基于动态网格技术的二维数值化霜冻模型。计算域由霜层和湿空气区域组成，并且霜层表面的局部热和蒸汽通量由湿空气区域中的温度和蒸汽分数场的数值确定，而不是由经验相关性确定。霜层被视为具有分子扩散支配的传热和传质的增长的填充床，其中蒸汽脱升华的局部吸收系数和局部蒸汽分数均通过理论上用源项求解拟稳态蒸汽扩散方程来确定。霜层和湿空气区域的界面被视为两层壁，用于温度的迭代，其中指定的湿空气侧的温度等于霜侧的对应温度，而霜侧吸收包括额外热量在内的热通量。由蒸气沉积引起的潜热。编译用户定义的函数以对ANSYS Fluent实施上述处理。使用现有模型对文献中的结霜实验进行了仿真，以进行验证。探索了结霜过程中结霜层的轮廓如何随时间演变。给出了速度，温度和蒸气分数的轮廓和轮廓，以讨论热量和质量传递对霜形成的影响。数值结果表明，与实验相比，所提出的CFD模型可以预测霜冻的生长和致密化，相对偏差小于5％。此外，由于没有复杂的多相流解，当前模型的计算量很小。此外，动态网格有助于当前模型准确捕获霜层和潮湿空气区域的界面。