Feasibility study on bridge deck cooling system using natural ground cooling energy

Based on the existed bridge deck hydronic snow-melting system using ground source heat pump, a new concept of using natural ground cooling of thermal energy directly to lower the upper surface temperature of bridge deck in summer was presented in the paper. Mathematical and physical model of such cooling system was developed by coupling bridge deck cooling sub-model and geothermal heat exchanger sub-model. Its numerical solution in two-dimensional transient-state was obtained by using finite-element analysis method. The parameters, such as the upper surface temperatures of the bridge deck in Beijing with cooling or not, cooling load of unit hole depth for geothermal heat exchanger, absorbing heat for unit surface of a bridge, and hole wall temperature of geothermal heat exchange were analyzed using the model. Results indicate that the hours of deck temperature above 60°C and between 55-601 were reduced 88% and 45%, respectively, and the temperature of hole wall was increased by 3.9°C. Therefore, this system not only can decrease the hours of high temperature on the bridge deck surface in summer effectively, but also can improve operational performance of snow-melting system in winter.