Numerical simulation and experimental study of the growth characteristics of particulate fouling on pipe heat transfer surface
Numerical simulation and experimental study of the growth characteristics of particulate fouling on pipe heat transfer surface
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DOI：
10.1007/s00231-018-2451-y
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发表时间：
2018-08
影响因子：
2.2
通讯作者：
Ning Zhang;Xin Wei;Qirong Yang;Nan-nan Li;Erren Yao
中科院分区：
文献类型：
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作者：
Ning Zhang;Xin Wei;Qirong Yang;Nan-nan Li;Erren Yao
城市污水经二次处理后，仍然存在换热表面积聚颗粒污垢的问题，恶化了换热性能，增加了运行成本。因此，对换热管内壁颗粒结垢机理的研究具有重要意义。本文采用数值模拟和实验相结合的方法，研究了流速、颗粒浓度、入口温度、颗粒尺寸、管壁粗糙度、工质粘度和颗粒类型等因素对颗粒污垢热阻和污垢速率的影响。结果表明，工质流速、颗粒浓度和颗粒大小是影响颗粒污垢热阻的三个重要因素。随着流速的增大，污垢热阻的渐近值减小，而颗粒浓度和颗粒尺寸的增大，污垢热阻的渐近值增大。为了减缓污垢速率，应提高流速和入口温度，降低颗粒浓度、颗粒大小、管壁粗糙度和工质粘度。颗粒在换热表面的净沉积速率随颗粒密度的增大而增大。然而，颗粒类型的影响并不确定，本研究中的结垢速率和渐近值从小到大依次为：MgO、CaSO4、CaCO3和SiO2，且不随密度的增加而增加。不同颗粒污垢的协同作用使混合污垢热阻的渐近值减小，但这也与不同颗粒的性质有关。
The problem of particulate fouling accumulating on the heat exchange surface in urban effluent still exists after secondary treatment which deteriorating the heat transfer performance and increasing operational cost. Therefore, it is significant to study the fouling mechanism of particulate fouling on the inner wall of heat exchange tube. In this paper, the effects of flow velocity, particle concentration, inlet temperature, particle size, roughness of pipe wall, viscosity of working fluid and type of particle on the thermal resistance and fouling rate of particulate fouling were investigated by numerical simulation and experimental methods. The results show that the working fluid velocity, particle concentration and particle size are three significant factors that affect the thermal resistance of particulate fouling. The increase of flow velocity causes the asymptotic value of fouling thermal resistance to decrease, while the increase of particle concentration and particle size causes it to increase. To slow down the fouling rate, the flow velocity and inlet temperature should be increased, while the particle concentration, particle size, roughness of pipe wall and viscosity of working fluid should be decreased. The net deposition rate of particles on the heat exchange surface increases with the increasing particle density. However, the effect of particle type isn’t definite, the fouling rates and asymptotic values from small to large are MgO, CaSO4, CaCO3and SiO2in this study, which does not increase with the increase of density. The synergistic effect of different kinds of particulate fouling make the asymptotic value of mixed fouling thermal resistance decrease, but it is also related to different particle properties.