Snow-Melting on Sidewalks with Ground-Coupled Heat Pumps in a Heavy Snowfall City

Abstract

The authors along with others have developed the Gaia Snow-Melting System. This system consists of vertical ground heat exchangers, a heat pump and heating pipes embedded in a pavement body. This system utilizes geothermal heat and summer time solar heat for melting snow.
In 2002, two Gaia Snow-melting systems were completed in Aomori City, Japan, for melting snow on sidewalks. This city is said to be the snowiest city in the world among cities with populations of about 300 thousand or more. Annual snowfall sometimes exceeds 10m. The formation at the snow-melting site is a complex of unconsolidated sedimentary formations along the total length of the heat exchangers (151.4m long). The measured in-situ thermal capacity and effective thermal conductivity of the formation as determined by a thermal response test were 2.2 MJ/m3?K and 1.25 W/m?K, respectively, for the total section of the heat exchangers. The heat transfer mechanism in the formation indicated by the test was almost pure conduction.
Through two winters of operation, these snow-melting systems have demonstrated a snow-melting ability comparable to or more than that of electric heating cable systems. The annual electric power consumption was about 14% that of the electric heating cable systems adjacent to these Gaia Snow-Melting Systems.