DEVELOPMENT OF A HEAT-PUMP SNOW-MELTING SYSTEM COUPLED WITH EXHAUST WATER FROM GROUND WATER SPRINKLER

摘要

The most commonly used snow-melting system in Japan is the groundwater sprinkler system. Groundwater at approximately 15°C is pumped from the ground and then run through a sprinkler to melt snow covering the ground. Since the temperature of the water from the melted snow is approximately 4°C, this water may be used as a heat source of the heat pump system to melt snow in other areas, such as pedestrian walkways. The performance of a road heating system that uses a heat pump coupled with exhaust water from a snow-melting sprinkler is experimentally investigated. A prototype heat collection unit was assembled from 10 steel pipes having a length of 4 m and a diameter of 15 mm, placed in a U-shaped ditch of 400 mm in width along the roadside. A heat collection unit was connected to a 6.2 kW heat pump unit, and heated water was fed to a snow-melting radiator having an area of 31.2 m~2. A practical experiment was carried out from February 6 to March 7, 2013. For 4°C water flowing at 92 ??/min, the amount of heat collected in the ditch was 4.8 kW, and that radiated from the snow-melting panel was 6.0 kW. The average COP of the system was 5.8, and 10 cm of natural snowfall was cleared over three hours. A heat collector of unit length (1 m) can achieve a heat per unit length of 775 W/m.