结霜工况下变片距空气冷却器性能仿真与试验

以结霜工况下的变片距空气冷却器为研究对象,对空气冷却器建立分布参数计算模型,采用分子扩散理论建立霜层的生长模型。在计算过程中,采用空气冷却器迎风面的霜层厚度平均值作为变量迭代求解空气冷却器的风量。研究了变翅片间距结构对空气冷却器结霜工况下性能的影响,并进行了实验验证。实验结果表明:空气冷却器的风量、换热量变化趋势的实验值和计算值基本一致,偏差在5%左右。与定翅片间距空气冷却器相比,变翅片间距空气冷却器在结霜工况下具有较长的除霜周期和更好的传热性能。

Simulation and experiment on performance of air cooler with variable fin pitch in frosting conditions

A two-dimensional transient model for frost formation phenomenon on an air cooler with variable fin pitch has been developed to calculate and optimize the performance of the air cooler under frosting conditions. The proposed model is based on the molecular diffusion model. In the model, the mean frost thickness at the windward side of the control volume of the evaporator is taken as a variable for iterative calculations of the air volumetric flow rate to improve numerical accuracy. The numerically and experimentally obtained performance of the air cooler with variable fin pitch and constant fin pitch was compared. The results show a good agreement between the calculated values and the experimental data of the volumetric flow rate and the heat transfer rate of the air cooler with the relative difference less than 5%. Compared to air coolers with constant fin pitch under the same operating condition, the decrease in the volumetric flow rate of the air cooler with variable fin pitch is smaller. Therefore, it corresponds to a longer defrost cycle and larger heat transfer rate.