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对比实验研究4种强化管(波纹管、缩放管Ⅰ、缩放管Ⅱ和弧线管)和光管在相同工况(人工硬水入口温度、流速、硬度及水浴温度)下的CaCO3污垢特性。通过分析强化管污垢热阻Rf与几何参数等,基于冯.卡门类比法,以φ和ψ为强化管传热性能评价因子,ηφ和ηψ为其综合性能评价指标,构建强化管污垢数据分析模型,并逐一分析各强化管的抗垢机理。研究结果表明:波纹管因管内的二次扰流及沿轴线方向的流速周期性脉动冲刷近壁面流体,显著增强污垢剥蚀率,且不易结垢甚至实现自清洗;由于管内流体的周期性扰动削弱污垢沉积,喉部剧增的壁面剪切应力可显著增强污垢剥蚀并实现弧线管抗垢;缩放管因轴向压力梯度交替切换引发流体剧烈周期性扰动以及喉部回旋涡流双重增大污垢剥蚀率而实现抗垢。
Comparative experiments were carried out to study the characteristics of CaCO3 fouling under the same working conditions (artificial hard water inlet temperature, flow rate, hardness and water bath temperature) for four kinds of reinforced pipes (bellows, tube Ⅰ, tube Ⅱ and arc tube) and light pipe. Based on the von Karman analogy method, φ and ψ are considered as evaluating factors of heat transfer performance of pipe, ηφ and ηψ are their comprehensive performance evaluation indexes, and the analysis model of fouling resistance of reinforced pipe is established , And analyze the anti-scaling mechanism of each strengthened pipe one by one. The results show that the corrugated tube can flush the near-surface fluid periodically due to the secondary turbulence in the tube and the pulsation of fluid near the wall in the axial direction, which can greatly enhance the rate of soil erosion and prevent scaling and even self-cleaning. Due to periodic turbulence of fluid in the tube, Dirt deposition and sharp wall throat shear stress can significantly enhance the denudation of dirt and achieve anti-scaling of the arc tube. The scaling of the scaling tube due to the alternating axial pressure gradient leads to the drastic periodic perturbation of the fluid and the double increase of the vortex of the throat. Rate and achieve anti-scaling.