圆柱形及圆锥形混合室气体喷射器的适用参数区探讨

Applicability analysis on ejectors with cylindrical and conical mixing chambers

分别以水、氨、R290、R22、R134a为工质,计算分析了在不同膨胀比压缩比条件下圆柱形及圆锥形混合室两种结构喷射器的喷射系数,并定义了等喷射系数压缩比、等喷射系数参数线和参数区。膨胀比恒定,压缩比小于等喷射系数压缩比时,圆柱形混合室的喷射系数较圆锥形的大;压缩比大于等喷射系数压缩比时,圆锥形混合室喷射系数较圆柱形的大。由等喷射系数参数线知,随膨胀比增大,等喷射系数压缩比减小。在等喷射系数参数区内,两种结构喷射器效率相当;在等喷射系数参数区左边,宜使用圆柱形混合室;在等喷射系数参数区右边,宜使用圆锥形混合室。绝热指数对等喷射系数参数区的分布具有决定作用。

Considering expansion and compression ratios, the entrainment ratio was analyzed for ejectors with cylindrical and conical mixing chambers using water, ammonia, R290, R22 and R134a as working fluid separately. The equivalent compression ratio, equivalent parameter line and equivalent parameter region of entrainment ratio were defined. At a constant expansion ratio, the cylindrical mixing chamber can reach a higher entrainment ratio than the conical chamber when the compression ratio is smaller than the equivalent compression ratio of entrainment ratio, and different case will occur when the compression ratio is less than the equivalent one of entrainment ratio. The equivalent parameter line of entrainment ratio shows that the equivalent compression ratio decreases with the increase of expansion ratio. In the equivalent parameter region of entrainment ratio, the two types of ejectors have almost the same efficiency. A cylindrical mixing chamber ejector is prior when compression ratio and expansion ratio locate in the left of the equivalent parameter region of entrainment ratio, while a conical mixing chamber ejector is preferable when they are in the right. The location of equivalent parameter region is determined by the adiabatic exponent.