Abstract:

A helical mixer with contraction-expansion connections combines helical pipes and sudden expansion and contraction array, which was optimally designed in this paper for enhancing the mixing in the regular helical mixer. The effect of the number of mixed elements, the pitch and curvature, the ratio of the lengths of contraction part to expansion part and Reynolds number on the mixing efficiency of the contraction-expansion helical mixer, was experimentally investigated by use of a fast competitive-consecutive diazo coupling reaction. It is found that: the radius of curvature of the helical mixer, ratio of the lengths of the contraction part to expansion part and the Reynolds number affect significantly the mixing efficiency, while the pitch of helical mixer had little influence. The best mixing performance is achieved by the contraction-expansion helical mixer with the radius of the curvature R 10.5 mm, the ratio of the lengths of contraction part to expansion part 4:1, the numbers of mixed elements 40 in the ranges of Reynolds number from 1000 to 1575. The mixing efficiency of the optimized contraction-expansion helical mixer is superior in comparison to both of the regular helical mixer and contraction-expansion straight mixer.

Key words: contraction-expansion, helical pipe, mixing, efficiency

摘要：

为了增强普通螺旋管的混合效率,在普通的螺旋管结构中引入突放突缩结构,设计制造出缩放螺旋混合 器。以竞争串连反应的离集指数为指标,对缩放螺旋混合器的结构进行了优化设计,考察了缩放螺旋混合器的几何参数——混合单元数、粗细段长度比、螺距、曲率半径以及Reynolds数对混合器的混合效率的影响。结果表 明:缩放螺旋混合器的粗细段长度比为1/4,曲率半径为10.5 mm,混合单元数为40,Reynolds数在1000～1575时混合效率最佳;参数优化后的缩放螺旋混合器比普通螺旋管混合器以及具有缩放结构的直管混合器中的混合效率更高。

关键词: 缩放, 螺旋管, 混合, 效率