Experimental investigation of solar heating bridge decks. Final report 1 Apr 77-30 Jun 79

The addition of monomers or the inclusion of wax within highway bridge decks are two methods being used to prevent salt penetration during winter deicing. Both of these methods require the addition of heat until the upper two inches of bridge deck reaches from 160-190 F. This study investigated the potential for using solar energy as a means of providing the required heat. The bridge was modeled analytically and the time varying temperature distribution was determined for both a flat plate type cover collector and focusing tracking solar collection schemes. The models indicated the flat plate approach for typical summer conditions in Oklahoma was at best marginal but that the focusing collector scheme did show promise for providing the required heat. Both models suffered from lack of accurate thermal properties data for the concrete. Experimental studies were conducted on a simulated bridge deck using flat plate covers and Northrup focusing Fresnel Lens collectors. Neither scheme was able to provide the desired temperatures. A major difficulty encountered was the design of an appropriate heat exchanger to transfer the collected energy from the heat transfer fluid to the bridge deck. Several different designs were tested, but none of the methods used wouldmore » provide the desired bridge deck temperatures for the collector area used. The collectors did not perform up to their expectations.« less