基于冯·卡门类比的强化管污垢模型及抗垢机理
来源期刊：中南大学学报(自然科学版)2012年第10期
论文作者：张仲彬 李煜 徐志明
文章页码：4093 - 4099
关键词：强化管；冯·卡门类比；污垢模型；抗垢机理
Key words：enhanced tubes; von Karman analogy; fouling model; anti-fouling mechanism
摘 要：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。
Abstract: The comparative experiments on the CaCO3 fouling characteristics of four enhanced tubes (including the corrugated tube, convergent-divergent tubeⅠ, convergent-divergent tubeⅡ and arc-line tube) and a plain tube under the same operating conditions, such as the inlet temperature, flow velocity and hardness of artificial hard water and bath temperature of tubes, were carried out. Based on the von Karman analogy, φ and ψ were regarded as their performance evaluation factors of heat transfer, ηφ and ηψ were used as their comprehensive performance evaluation indexes, and then a fouling model of enhanced tubes was established through the analysis of experimental data, such as their fouling resistance Rf and geometric parameters. The anti-fouling mechanisms of each enhanced tube were analyzed. The results show that it is the secondary turbulence and periodic pulse along the axis of flow velocity direction in the corrugated tube scouring near-wall flow that enhances the removal mass rate of fouling dramatically so that it is difficult for the tube to cause fouling and even realize automatic cleaning. The arc-line tube has the anti-fouling performance in which the periodic disturbance of flow in it weakens fouling deposition and the sharp increasing laryngeal wall shear stress boosting fouling removes greatly. The convergent-divergent tube can resist fouling because the fouling removal mass rate is enhanced doubly by fluid’s intensive periodic disturbance caused by the alternate switch of axis pressure gradient and the swing eddy current at the laryngeal.
张仲彬，李煜，徐志明
(东北电力大学 能源与动力工程学院，吉林 吉林，132012)
摘 要：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。
关键词：强化管；冯·卡门类比；污垢模型；抗垢机理
ZHANG Zhong-bin, LI Yu, XU Zhi-ming
(School of Energy and Power Engineering, Northeast Dianli University, Jilin 132012, China)
Abstract:The comparative experiments on the CaCO3 fouling characteristics of four enhanced tubes (including the corrugated tube, convergent-divergent tubeⅠ, convergent-divergent tubeⅡ and arc-line tube) and a plain tube under the same operating conditions, such as the inlet temperature, flow velocity and hardness of artificial hard water and bath temperature of tubes, were carried out. Based on the von Karman analogy, φ and ψ were regarded as their performance evaluation factors of heat transfer, ηφ and ηψ were used as their comprehensive performance evaluation indexes, and then a fouling model of enhanced tubes was established through the analysis of experimental data, such as their fouling resistance Rf and geometric parameters. The anti-fouling mechanisms of each enhanced tube were analyzed. The results show that it is the secondary turbulence and periodic pulse along the axis of flow velocity direction in the corrugated tube scouring near-wall flow that enhances the removal mass rate of fouling dramatically so that it is difficult for the tube to cause fouling and even realize automatic cleaning. The arc-line tube has the anti-fouling performance in which the periodic disturbance of flow in it weakens fouling deposition and the sharp increasing laryngeal wall shear stress boosting fouling removes greatly. The convergent-divergent tube can resist fouling because the fouling removal mass rate is enhanced doubly by fluid’s intensive periodic disturbance caused by the alternate switch of axis pressure gradient and the swing eddy current at the laryngeal.
Key words:enhanced tubes; von Karman analogy; fouling model; anti-fouling mechanism
