Simulation Based Investigation on the Design of Hydronic Snow Melting System

Hydronic heating systems that circulate a heated fluid through pipes embedded in a bridge deck or roadway may be used to eliminate or reduce dangerous driving conditions caused by snow and ice. The first important task in sizing such a system is determining the required heat flux. Current guidance in the ASHRAE HVAC Applications Handbook for required surface heat fluxes is based on a one-dimensional steady-state heat balance of the snowmelting surface. For a range of locations, the required heat flux to maintain a specified surface condition for a statistically-determined percentage of hours with snow fall has been tabulated. This approach is limited by the fact that real systems are almost never operated continuously through the winter. Also, two-dimensional effects, such as pipe spacing and bottom losses are clearly important, but neglected by the procedure used to develop the design heat fluxes. This paper describes a parametric study to investigate the impact of idling time, heating capacity, pipe spacing, bottom insulation, and control strategies on system snow melting performance. An experimentally validated hydronic snow melting system simulation has been run for several different North American locations, using up to ten years of weather data. With all parametric variations, 528 simulations were run. TRB 2004 Annual Meeting CD-ROM Paper revised from original submittal.