Simulation-Based Analysis of a Novel CO₂ Ground Source Heat Pipe (GSHP) to Reduce Temperature Fluctuations in Pavements in Different Climatic Conditions

Abstract

A fully wicked ground source heat pipe (GSHP) is numerically employed and simulated to transfer thermal energy from the subsurface to ground surface pavements to reduce the environmental temperature fluctuations in the pavement, thereby reducing thermal stresses and increasing pavement life. The GSHP can also reduce or eliminate snow and ice buildup on pavement surfaces. Each single GSHP was modeled in a two-dimensional axisymmetric cross-section using COMSOL software, which employs a finite element method. The modeled GSHP consisted of two parts: a disk shape buried below the pavement surface, connected to a cylindrical part embedded in a vertical underground borehole. The GSHP finite element model was validated against published experimental heat pipe data. The simulation results demonstrated that the thermal behavior of the heat pipe system during the cold season could reduce the temperature fluctuations on the pavement surface in six various climate zones. The addition of insulation along the vertical length of the heat pipe was found to significantly reduce heat loss between the heated and unheated pavement surfaces. The low thermal conductivity of the pavement material decreases the performance of the GSHP system. Finally, the maximum-minimum normalization method was applied to the parametric analysis to normalize and compare results for future use.

Keywords

• ground source heat pipes
• temperature fluctuation
• pavement
• finite element