本文对一冷却塔中的7根螺纹管进行了长时间污垢实验研究.螺纹管几何参数范围:螺纹数18～45,螺纹角25°～45°,螺纹高0.33～0.55 mm.污垢是颗粒污垢和析晶污垢的混合物.本文基于普朗特类比,引入修正因子β(β=(A_w/A_(wp))/(A_c/A_(cp)),A_w为润湿面积,A_c为截面积,下标p表示光管),对半经验污垢预测模型进行修正,证明了螺纹管内参数对污垢热阻的形成影响很大,并建立了不同结构参数的螺纹管的统一结垢模型,对工程实际有一定指导意义.
The experiments on fouling resistant of the seven different helical-rib tubes in cooling tower have been carried by US for a long time.The ranges of geometric parameters were number of rib starts(18～45),helix angle(25～45 deg.),and height(0.33～0.55 mm).The fouling mechanism is a combination of precipitation fouling and particulate fouling.Based on the Prandtle analogy,β factor (β=(A_w/A_(wp))/(A_c/A_(cp)),A_w is the wetted area,A_c is the cross section area,and the subscript p means the plain tube) was introduced to revise the semi-theoretical fouling model.The geometric parameters were proved to affect the fouling growing strongly.A new unified theoretical fouling correlation has been developed for all the tubes.The new correlation can be directly used to assess the fouling potential of enhanced tubes in actual cooling water situations.
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