Design and Numerical Analysis of an Externally Heated Geothermal Bridge Deck

Abstract

In winter, ice and snow on pavement slabs and bridge decks cause serious driving conditions to motorist both in safety and ability to accelerate and clime grade. Geothermal energy has gradually emerged as a new heating source for heating bridge decks and pavements to keep bridges and roads free of snow and ice in winter. However, current geothermal bridge deicing design and studies mostly focus on new bridges that hydronic loops are embedded in concrete deck during construction phase, which is considered as internal heating. This paper presents a conceptual design and numerical analyses of external geothermal bridge deck heating that the hydronic loops are attached to the bottom of bridge deck and encapsulated in a layer of geofoam. A series of parametric analyses is performed to investigate the principles of external heating process. The controlling factors, such as ambient temperature, inlet temperature, wind speed, flow velocity, and foam thickness are considered. The results show that the temperature of the proposed external heated bridge deck can rise above freezing in mild winters through heating for at least 3 h. Limitations of the design are also discussed that the proposed heating system would be unfeasible in the area where the ambient temperature and inlet temperature are lower than −2 and 12 °C, respectively, and wind speed is higher than 6 m/s. It is also found that foam thickness slightly affects the heating process.