Heat transfer characteristics and thermal insulation optimization of buried ductile iron heat-supply pipeline

Abstract

ABSTRACTThis study investigates heat transfer in a ductile iron heat-supply pipeline and develops a mathematical model through a comparative assessment of different techniques. The goal is to accurately describe non-steady state heat transfer in buried pipelines. A high-precision model is established by considering assumptions, equations, boundary conditions, calculation domain, geometry, and grid number. Calculation time is reduced, and accuracy is improved, providing a foundation for optimizing the thermal insulation layer. ANSYS software is used to simulate and optimize the thermal insulation of the pipeline. Results show a maximum error range of 1.20% to 10.20% with consistent temperature trends, verifying the model’s accuracy. The heat-affected zone of the thermal bridge is evaluated and optimized, and preventive measures are proposed to reduce the impact of heat bridges in joint areas. The study also compares nodular cast iron pipes with conventional steel thermal pipes under the same conditions. It reveals that the economic thickness of the thermal insulation layer for nodular cast iron pipes increases from 31 mm to 39 mm due to the thermal bridge effect, which is significant.

Keywords

• Directly buried pipeline
• thermal bridge effect
• economic thickness of thermal-insulating layer
• soil temperature field
• simulation