供暖输热管道的非稳态热损失分析

Analysis of unsteady-state heat loss of heating pipe

建立了包含对流换热系数和周期性气温模型的供暖管道非稳态传热模型,采用有限差分法运用MATLAB进行编程求解,并将所得的结果与实验值进行对比,结果表明:程序计算结果与实验结果间的线性相关系数呈强相关,验证了模型的准确性,对连续作业管道或准稳态传热的输热管道热平衡计算具有重要的参考价值;考虑管内介质与管道内壁间、空气与保温层外壁间对流换热系数,更加精确地反映了第三类边界条件下传热过程中的热损失;管道热损失与保温层厚度呈现出的并非是简单的线性关系,仅依靠增加保温层厚度不是最有效的管道保温方法.

The unsteady-state heat-transfer model of heating pipes, including the convective heat exchange coefficient and periodic air temperature model, was constructed. The model was solved by means of finite difference method and program ming with MATLAB and then its calculation result as compared with the experimental result. The result showed that a strong linear correlation of the calculation result to the ex- perimental result would exhibit, so that the accuracy of the model was verified and would have a significant reference value for the heat balance calculation of heat-transfer pipes, working under continuous operation condition or quasi-steady heat transfer condition. Taking into account of the convective heat-exchange coef- ficient between the medium and inner wall of pipes and between the air and outer wall of heat-insulating layer, the model could even precisely reflect the heat loss in heat transfer process under the third-category boundary condition. The relationship of heat loss of pipes to insulating layer thickness would be not a sim- ple linear correlation, so that merely increasing the thickness of the insulating layer would be not the most effective method of heat insulation of pipe.