Abstract: A new flat strip-insert with elliptical teeth and notches was developed to solve the problem of rapid fouling growth and reduced heat transfer coefficient at a low flow rate in heat transfer tubes. The notches were distributed and staggered on both sides of the strip. An oblique tooth followed each tooth. Thus, the fluid flowed spirally. It was just like the flow when twisted strip with oblique teeth was inserted in tubes. Such spiral flow enables the flat strip-insert to self-rotate and remove fouling on tube wall at a low flow rate. Much strong vortex was produced behind each elliptical tooth, which were distributed uniformly, so convective heat transfer was enhanced greatly. The tube side heat transfer film coefficient increased by two times in comparison with that without any insert. The enhancement was more than simple twisted strip by over 5 times. The flow resistance coefficient was much higher than that of simple twisted strip, but the overall equipment resistance was not high and was in the range of engineering application. The new flat strip- insert with elliptical teeth and notches can be made through injection molding. The manufacture cost was low and the quality was quite good. It can be put into mass production and used widely in heat transfer equipment.

摘要： 针对较低流速下传热管内容易生长污垢和低传热系数问题，本文提出一种具有旋流口椭圆齿的新型平带。在平带的椭圆齿前两侧设计交错排布的旋流口，使传热管内的液体形成类似斜齿螺旋扭带那样的螺旋线液流，从而使旋流口椭圆齿平带同样具有斜齿螺旋扭带能够在较低流速下可靠自转清洗防垢的功能。由于平带上轴向等距离排布的椭圆齿齿后产生大量强烈的涡流，使管内的对流传热得以非常有效的强化，管内侧传热膜系数比空管时提高近一倍，其强化幅度达到光滑扭带的6倍以上。虽然流体阻力远高于光滑扭带，但是设备阻力仍然在一般工程容许的范围内。这种新型结构的旋流口椭圆齿平带可以注塑成型，制造费用低、制品质量好，便于大批量生产和推广应用。