Ground-Source Bridge Deck Deicing Systems Using Energy Foundations: Fid-Bau Portal

Ground-Source Bridge Deck Deicing Systems Using Energy Foundations

Bowers, Jr., G. Allen / Olgun, C. Guney

Ground-source heating of bridge decks can be an alternative to the use of salts and chemicals to deice bridge decks. Energy foundations, geothermal boreholes, shallow trenches, or the approach embankment can be utilized as energy storage media and heat exchange pathways to utilize the ground as a heat source. Coupling the energy foundation with a ground-source heat pump can provide higher inlet fluid temperatures and result in more effective bridge heating but at the expense of greater energy consumption and increased system complication. Circulating the fluid directly from the energy foundation to the bridge deck relies heavily on the in situ ground temperatures. This paper outlines the operational principles and how these are related to the design parameters of bridge-deck deicing systems. A series of parametric analyses was performed to investigate the bridge-deck heating process. The analyses considered a variety of tube spacings, inlet fluid temperatures (i.e., ground temperatures), flow rates, wind speeds, ambient temperatures, and thicknesses of concrete cover over the circulation tubes. The results serve as a benchmark to gauge the operational conditions and the energy requirements for designing ground-source bridge deck deicing systems. Ground temperatures serve as a baseline for heating of bridge decks with passive heating in the winter, and this study underlines its limitations at colder environments. This can be overcome by collecting heat from the bridge deck in the summer and injecting the collected heat into the ground to raise the ground temperatures. This stored energy can be reclaimed in the winter when needed. The issues related to heat collection and ground storage are part of a broader study and fall outside the scope of this paper.