Pipeline insulation optimization in district heating networks

District heating networks are critical for energy delivery in megacities, but significant heat loss undermines their efficiency and cost-effectiveness. While pipeline insulation is a known solution, existing models often oversimplify the system by neglecting key real-world components like pipe elbows and their associated turbulent losses, leading to suboptimal design. This study introduces a comprehensive numerical framework to bridge this gap. Using COMSOL Multiphysics, we investigate four insulation scenarios—no insulation, perfect insulation, optimal insulation, and factory-insulated—for a 31.5 km network. Our key innovations include: first, integrating a 90° pipe elbow to accurately capture turbulence-induced pressure drops, a factor typically overlooked; second, determining the optimal insulation thickness using the Nelder-Mead optimization method to maintain a constant pipeline temperature; and third, conducting a lifecycle cost analysis to evaluate the economic viability of different insulation materials and fuel types. The results provide detailed temperature, pressure, and flow distributions, yielding practical, cost-effective guidelines for district heating design. Our work demonstrates that optimized insulation, accounting for realistic geometry, can significantly reduce heat loss and operational costs, offering a more robust tool for sustainable urban energy planning.