Thermal response and inlet water temperature estimation for a geothermal bridge deck deicing system

Shallow geothermal energy provides a low-carbon approach to winter bridge-deck heating, but methods for matching heat-supply parameters to meteorological and icing loads remain limited. Field thermal-response tests were conducted on a demonstration bridge in Wuhan, China, and the measured data were used to validate a three-dimensional transient heat-transfer model. An equivalent latent-heat sink was subsequently used to represent the thermal demand associated with ice-layer phase change. Field observations showed continuous warming in the wheel-track zones, while the simulations identified three stages: structural preheating, equivalent latent-heat absorption, and subsequent pavement warming. Lower ambient temperatures delayed phase-change initiation, thicker ice layers prolonged heat absorption, and stronger winds intensified surface heat loss, whereas higher inlet water temperatures enhanced heat input. The applicability assessment of representative icing-heat-supply combinations showed that low ambient temperature and strong wind progressively narrowed the conditions under which the prescribed latent-heat demand could be satisfied within 12 h. Under the enhanced heat-supply condition, the prescribed latent-heat demand of a 15-mm ice layer was satisfied within 12 h at wind speeds up to 8 m/s under near-freezing conditions. Finally, a regression relationship for the average phase-change heat-absorption flux was coupled with the latent-heat demand to derive an inlet water temperature estimation equation under a target equivalent phase-change duration. For the fixed bridge-deck configuration investigated, this approach links discrete numerical applicability assessment with heat-supply parameter estimation under prescribed environmental, icing, and flow conditions.