低温工况下蒸发器结霜特性的数值模拟及试验研究

Numerical analysis and experiment of frosting quality of finned-tube evaporators in low temperature condition

结合CFD模拟和试验两种方法,研究制冷过程中蒸发器结霜这一常见的问题。提出了修正的组分传输和有限速率化学反应模型来对蒸发器的结霜过程进行CFD模拟,用升华潜热来替代化学反应的活化能,使H2O(g)H2O(s)这一物理反应变成有限速率的化学反应。考察了低温工况下(-20℃以下),湿空气进口速度分别为v=2 m/s,1.2 m/s,0.8 m/s;相对湿度分别为60%,80%时蒸发器结霜量的大小。低温工况下,蒸发器的结霜量随着蒸发器迎面风速的增大而增大,随着空气进口相对湿度的增加而增加,模拟结果和试验结果符合得很好。

Frosting of evaporator was researched based on CFD simulation and test, The correctional species transport and finite-rate reaction model to simulate the frosting of evaporator was put forward, With substitued latent heat of sublimation for activation energy of chemical reactions, the physical reaction H2O （g）←→ H2O （s） was changed into chemical reaction. In low temperature condition （blow -20 ℃ ）, the quantity of evaporator frosting was studied when the inlet velocity of humid air was 2.0 m/s, 1.2 m/s, 0.8 m/s and the relative humidity was 60% , 80% respectively. The results show that the quantity of frost increases with the inlet velocity and the relative humidity and the numerical simulation results accord with the test results very well.