The insulation thickness (IT) of double pipes buried in the soil (DPBIS) for district heating (DH) systems was optimized to minimize the annual total cost of DPBIS for DH systems. An optimization model to obtain the optimum insulation thickness (OIT) and minimum annual total cost (MATC) of DPBIS for DH systems was established. The zero point theorem and fsolve function were used to solve the optimization model. Three types of heat sources, four operating strategies, three kinds of insulation materials, seven nominal pipe size (NPS) values, and three buried depth (BD) values were considered in the calculation of the OIT and MATC of DPBIS for DH systems, respectively. The optimization results for the above factors were compared. The results show that the OIT and MATC of DPBIS for DH systems can be obtained by using the optimization model. Sensitivity analysis was conducted to investigate the impact of some economic parameters, i.e., unit heating cost, insulation material price, interest rate, and insulation material lifetime, on optimization results. It is found out that the impact of sensitivity factors on the OIT and MATC of DPBIS for DH systems is different.

优化了用于区域供热（DH）系统的埋在土壤（DPBIS）中的双管的隔热厚度（IT），以最大程度地减少用于DH系统的DPBIS的年度总成本。建立了一种用于获得DH系统的DPBIS的最佳绝缘厚度（OIT）和最小年度总成本（MATC）的优化模型。使用零点定理和fsolve函数求解优化模型。在计算DH系统的DPBIS的OIT和MATC时，分别考虑了三种热源，四种工作策略，三种保温材料，七个标称管道尺寸（NPS）值和三个埋入深度（BD）值。 。比较了以上因素的优化结果。结果表明，通过优化模型可以得到DHB系统的DPIT的OIT和MATC。进行了敏感性分析，以研究某些经济参数（如单位供热成本，隔热材料价格，利率和隔热材料寿命）对优化结果的影响。发现对于DH系统，敏感度因素对DPBIS的OIT和MATC的影响是不同的。