Analysis of Influencing Factors and Sensitivity Analysis of the Design Length of Buried Pipe Ground-Source Heat Pump

To address the issue of unreasonable buried pipe length design in ground-source heat pump projects, a three-dimensional dynamic simulation platform was developed. The reasonableness of the buried pipe length was evaluated by comparing the simulated outlet temperature with the designed outlet temperature based on specifications. Using a building in Beijing as a case study, the effects of soil thermal properties and borehole-related parameters on the design error in buried pipe length were analyzed. A sensitivity analysis further examined the impact of these factors. Results indicate that the relative error in buried pipe design length increases with rising soil thermal conductivity, soil volumetric heat capacity, borehole depth, and borehole spacing. Relative error ranges were 10.7%-27.3%, 8.0%-23.8%, 7.3%-12.5%, and 12.5%-17.4% for the respective factors. Sensitivity analysis revealed soil thermal conductivity as the most significant factor influencing pipe length, with a quantitative index of 0.909. Other influential factors, in descending order, were soil volumetric heat capacity, borehole spacing, number of borehole columns, and borehole depth.