Citation

Williams GP. Transp. Res. Rec. 1976; 576: 20-32.

Copyright

(Copyright © 1976, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

METHODS of calculating design heat requirements of embedded snow-melting systems are assessed, particularly for those operating in cold climates. Formulas for estimating design heat requirements developed from snow-melting tests carried out during three winters at Ottawa, Canada, are compared with those recommended in the Guide and Data Book of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the only comprehensive guidelines available in North America. The relation between convective coefficients and wind speed at an exposed site compares reasonably well with that recommended by ASHRAE, provide adjustments are made for the size of the heated area, the exposure to wind, and the height at which wind speeds are measured. Evaporative coefficients recommended by ASHRAE also need to be adjusted for the size of heated area and the exposure to wind. Radiative coefficients need to be adjusted for cloud conditions. The design heat requirements for systems operating in cold climates are determined by the maximum rate of surface heat loss from bare, wet pavements for weather conditions that will probably prevail immediately after snowstorms. Design heat requirements calculated for an exposed site at Ottawa by using the heat transfer coefficients obtained are 170 Btu/square foot-hour (536 W/m square). This agrees quite well with current practice in this region. Two case histories of snow-melting tests are presented to illustrate that the use of insulation will practically eliminate ground heat loss and the need to allow for it in design calculations.

Language: en