冷藏陈列柜风幕卷吸特性的数值分析

Numerical Analyses of Entrainment Characteristics of Air Curtains in Multi-Deck Refrigerated Display Cases

应用数值方法分别对不同射流速度分布(均匀分布、2种线性分布和抛物型分布)的垂直冷风幕的卷吸特性进行了研究,对体积卷吸率、温度分布及热卷吸系数进行了分析比较.结果表明,速度分布对风幕的卷吸特性有着重要影响,内侧较大的线性速度分布是其中性能最优的,对外部空气的卷吸量最小,对柜内空气的卷吸量最大.因此,在保证柜内温度的前提下,通过在出风口设置合适的整流装置,使外侧速度尽可能减小,可以显著降低对外界空气的卷吸,从而减小冷藏陈列柜的热负荷.

Numerical analysis are performed to study the entrainment characteristics of cold air curtains with different initial velocity profiles including uniform profile, two kinds of linear profile, and parabolic profile. Volumetric entrainment rates, temperature differences between returned and discharged air and thermal entrainment factors are compared and analyzed. The results show that the initial velocity profiles have striking influences on the entrainment characteristics of cold air curtains. In the studies the linear profile with higher velocity adjacent to inside case has the best performance, and it has the lowest entrainment rate from ambient and the highest from inside case. Therefore adjusting velocity profiles properly by setting up deflectors at the discharge grille can reduce entrainment from ambient and thus the cooling load of refrigerated display cases can be decreased.