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Evaluation of an earth heated bridge deck.

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Details:

  • Creators:
  • Corporate Creators:
    University of Wyoming
  • Corporate Contributors:
    United States. Federal Highway Administration
  • Subject/TRT Terms:
  • Publication/ Report Number:
    FHWA-WY-84-001
  • Resource Type:
    Tech Report
  • Geographical Coverage:
    Wyoming
  • Edition:
    Final report.
  • Corporate Publisher:
    Wyoming. State Highway Department
  • Abstract:
    The design, construction, performance and analysis of the first ground heat pipe

    system to heat an entire bridge deck are detailed. Each of the sixty heat pipes in

    this system is comprised of a 6 em (2.4") diameter, 31 m (lOO')_long vertical ground

    evaporator, and a condenser that was forme~ by manifolding 2.5-cm (1") pipe on 15 ~m

    (6") centers to heat 7.6 m2 (82 ft2 ) of deck surface. Ammonia vaporizes in an

    evaporator anytime the encompassing ground is warmer than the bridge deck, and this

    vapor ascends into the condenser section where it releases its heat of vaporization

    to the deck.

    The integration of the heat pipes into the bridge deck did not have a

    significant impact on the bridge construction. The heat pipes increased the deck's

    weekly averaged surface temperature up to l0°C (l8°F), preventing preferential

    freezing of the deck relative to the adjacent road. Sno:w cover duration was decreased·

    by 50% despite a ground temperature of only soc (46°F). The m~n~mum dynamic

    conductance of this system during major heating events appears to be between 8 and 11

    watts per m2 of deck per oc temperature difference between the far-field ground and

    the deck surface. A thermal model was developed to accurately handle the complex •

    dynamic interactions between the heat pipes, the deck, and the ·ground. Parametric:

    studies based on this model were used to formulate a heat pipe system thermal design•

    procedure which is presented in the design manual. The heat pipes accounted fo.r 59% ,

    of the total bridge cost with the evaporators generating 69% of the system's expense;'

    but it wo~ld be economically viable to utilize a few ground source heat pipes to heat

    only the tire tracks and gutters.

  • Format:
    PDF
  • Funding:
    DTFH61-80-C-00053
  • Collection(s):
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