U形污水换热管中颗粒污垢沉积特性研究
摘要：分析了不同污水流速、污水黏度、颗粒浓度及颗粒粒径下颗粒污垢在换热壁面上的沉积、剥蚀及热阻的变化情况。结果表明：污水的流速、黏度及颗粒的浓度对颗粒污垢的沉积情况影响较大，在其他参数不变的情况下，当流速由0.5 m/s增大到1.5 m/s时，沉积速率增大了2.3倍，剥蚀达到稳定的时间缩短为原来的1/6,污垢热阻减小56%;当污水的黏度由0.001 0 Pa·s增大到0.003 0 Pa·s时，剥蚀达到稳定的时间延长1.27倍，污垢热阻增大1.25倍；当颗粒浓度由400 mg/L增大到800 mg/L时，剥蚀达到稳定的时间增加约1倍，污垢热阻增大约1倍；颗粒粒径对污垢沉积特性的影响较小，当颗粒粒径由1μm增大到40μm时，沉积速率仅增大14%,污垢热阻仅增加12.8%。研究结果可供污水换热器设计、运行及除垢参考。
关键词：U形污水换热管颗粒污垢沉积特性剥蚀热阻数值模拟
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Study on deposition characteristics of particulate fouling in U-shaped sewage heat exchange tubes
Abstract: This paper analyses the changes of deposition, denudation and thermal resistance of particulate fouling on the heat exchange wall under different sewage flow rate, sewage viscosity, particle concentration and particle size. The results show that the sewage flow rate, the sewage viscosity and the particle concentration have a great influence on the deposition of particle fouling, and when the velocity increases from 0.5 m/s to 1.5 m/s under the condition that other parameters remain unchanged, the deposition rate increases by 2.3 times, the time for denudation to reach stability is shortened to 1/6 of the original, and the fouling thermal resistance decreases by 56%. When the sewage viscosity increases from 0.001 0 Pa·s to 0.003 0 Pa·s, the time for denudation to reach stability increases by 1.27 times, and the fouling thermal resistance increases by 1.25 times. When the particle concentration increases from 400 mg/L to 800 mg/L, the time for denudation to reach stability increases by about 1 time, and the fouling thermal resistance increases by about 1 time. The particle size has little effect on the fouling deposition characteristics, when the particle size increases from 1 μm to 40 μm, the deposition rate increases by only 14%, and the fouling thermal resistance increases only 12.8%. This study's results can be used as a reference for the design, operation and descaling of sewage heat exchangers.
Keywords: U-shaped sewage heat exchange tube; particulate fouling; deposition characteristic; denudation; thermal resistance; numerical simulation;
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