Cold energy recovery and reuse in artificial ground freezing for large-scale projects: Experiments and numerical modeling

Artificial ground freezing (AGF) is widely used for temporary support in subsurface construction. Current practice allows the frozen ground to thaw naturally once structural support is no longer required, leading to uncontrolled and inefficient dissipation of stored cold energy. Large-scale, multi-phase construction projects, where frozen-ground requirements shift across spatial locations over time, offer an opportunity to conserve energy by reusing residual cold energy across the site. This study proposes a cold-energy recovery and reuse framework for sequential AGF, in which cold energy from a decommissioned frozen zone is extracted and repurposed to pre-cool or freeze adjacent ground. The approach uses a heat transfer fluid loop to recover cold energy from frozen ground and transfer it to unfrozen ground. In this study, a laboratory-scale experimental setup is established, and a transient numerical model is developed, validated, and exploited to simulate cold-energy recovery and reuse under various operating and ground conditions. The results show that between 11– 15 MWh of energy can be recovered from frozen ground under representative field conditions, which can significantly reduce the energy utilized to cool adjacent unfrozen ground by up to 80%. Furthermore, the study reveals an imbalance between the energy recovered and utilized, arising from the predominance of sensible energy recovery in frozen ground and the combined sensible and latent energy storage in unfrozen ground.