直埋球墨铸铁热力管道热动态传热特性分析及保温优化

Thermal Dynamic Heat Transfer Characteristics Analysis and Insulation Optimization of Direct Buried Ductile Iron Heat Pipes

相比焊接钢制热力管道,球墨铸铁管道基材防腐蚀性优越,可有效提升管道使用寿命,采用柔性承插式接口,可以提升管道施工效率,并且能够通过自然补偿轴向热伸长而避免设置补偿器,因此球墨铸铁热力管道能够成为集中供热领域革新性技术元素。然而,在球墨铸铁热力管道接口处,由于承口凸起造成保温层厚度减薄,形成保温性能薄弱的热桥,不仅会增加整体管线的热损失,还可能会造成接口处外护管温度高于安全约束值50℃。为此,本文建立直埋双线球墨铸铁热力管道三维数学模型,用于分析管道热动态传热特性;建立球墨铸铁热力管道工程试验线实验平台,采集实验数据来检验数学模型。通过数学模型分析,确定了球墨铸铁热力管道接口处热桥的影响强度,提出通过适当增加经济保温层厚度的方法,来克服接口处热桥的不利影响,进而实现了新型热力管道保温的优化设计。

Compared with welded steel pipes,ductile iron pipes have superior corrosion resistance,and can effectively extend the service life.The use of a flexible socket interface improves the installation efficiency and avoids the use of a compensator by naturally compensating for the axial thermal elongation.Therefore,ductile iron heat pipes can be an innovative technological element in centralized heating.However,at the interface of ductile iron heat pipes,the thickness of the insulation layer is thinned due to the protrusion of the socket,forming a thermal bridge with weak insulation.It not only increases the overall pipeline heat loss,but can also causes the temperature of the outer sheath at the interface to be potentially higher than the safety constraint value of 50℃.To this end,this paper established a three-dimensional mathematical model for analyzing the heat transfer characteristics of the direct buried two-line ductile iron heat pipe.An experimental platform for ductile iron heat pipe engineering pipelines was established to collect experimental data and test the mathematical model.The strength of the influence of thermal bridges at the interface was determined,and the corresponding countermeasure of properly increasing the thickness of the economic insulation layer was proposed,thus realizing the optimal design of the new heat pipe insulation.