外螺旋塑料管自动清洗及其传热强化技术的研究

研究的外螺旋塑料管由自动清洗与传热强化需要的塑料外螺旋和刚性固定塑料外螺旋的塑料管组成，塑料管内可以填装液体或其它滚动体，使整体密度与管程液体相同，保持悬浮同心旋转，且利用其运动惯性提高自动清洗功效。组装在传热管内后，管程液体被导流成快速的螺旋线液流，螺旋线液流给外螺旋塑料管的反作用力使其自转清洗，且使管内的对流传热得到有效强化。通过理论计算研究，得到了外螺旋塑料管动力矩计算式，按此得到结构设计的基本原则。试验结果表明：自转动力矩比扭带增大141％，能够在04m／s以上的流速下实现自动清洗防垢；传热系数比光滑扭带平均提高50％左右；设备的流体阻力不大，在工程容许范围内。

Study on Techniques to Enhance Heat Transfer and Remove Fouling in the Plastic Tube-insert with outside Spiral

The plastic tube-insert with outside spiral is composed of exterior spiral and rigid inner tube. The exterior spiral can enhance heat transfer and remove or prevent fouling. The tube-insert can be filled with liquid or other substance to make its average density equal to the flowing fluid in heat transfer tubes, thus it can float and spin concentrically with axis. The fluid flows guided by the exterior spiral moves more quickly and acts a counteracting force on the plastic inserts to increase the cleaning efficiency. The formula of the driving force moment can be obtained based on theoretical calculation, and the driving force moment is increased by 141% over the smooth twisted strip. Fouling can be removed or prevented at low velocity of even less than 0.4 m/s, and heat transfer coefficient is increased by 50%.