Thermo-economic Analysis for Directly-buried Pipes Insulation of District Heating Piping Systems

Energy losses in district heating pipeline networks can be reduced considerably using insulation materials. In this study, the optimum insulation thickness of direct burial laying used in district heating pipeline networks, energy savings, and payback periods are calculated for various pipe diameters, fuel types and soil depth in the city of Xi'an/China by software MATLAB depending on Life Cycle Cost Analysis (LCCA) method. The results show that optimum insulation thicknesses vary between 0.060 and 0.121 m, energy savings vary between 36.395 $/ m and 194.682 $/m, and payback periods vary between 0.445 and 1.691 years. When the rock wool is used as the insulation material and the soil depth is 1 m, the highest value of energy savings is reached in 500 mm nominal pipe size for fuel-oil fuel type, while the lowest value is obtained in 100 mm for geothermal energy. Therefore, the selection of optimum thickness for different pipes diameters and fuels types is particularly vital for the economic and environmental advantages.