Heat transfer simulation for ground heat exchangers with varying heat fluxes

Based on the superposition principle and uniform inlet fluid temperature assumption, the semi-analytical solution to heat transferring of ground heat exchangers (GHEs) with varying heat fluxes was built and validated. The effects of load imbalance and heat interference were further examined. Results indicate that the heat transfer capacity for individual boreholes in GHE depends on the strength of heat interference. If the heat rejected into the ground is greater than the heat absorbed from the ground, the outlet fluid temperature of GHE increases gradually every year. Case study indicates that the outlet fluid temperature of GHE, compared with that in the first year, increases about 0.8 ℃ in the 10th year. The capacity of heat rejection for the GHE becomes smaller with stronger heat interference.