Heat-pump road-heating system
A heat pump consists of a compressor, an expansion valve, pipes and a heat exchanger. This device generates heat by compressing the fluid in the pipe and generates cold by evaporating the compressed fluid. The high temperature achieved by compression provides heat for heating, and the low temperature achieved by decompression provides cooling.
When the available heat source has a temperature that’s too low for snow melting, the heat pump raises the temperature of medium high enough to melt snow. In the figure, the heat pump raises the ambient air at -1.2 degrees Celsius to 18 degrees Celsius. A heat exchanger extracts heat and uses it to raise the temperature of a liquid antifreeze that circulates through the heat radiation pipe installed under the pavement. This melts snow. Heat sources for heat pump systems include ambient air, ground heat and groundwater. Heat pump systems rely on electricity.
Heat-pump road-heating system
A heat pipe is a heat-transfer device. A vacuum is created inside a metal pipe, and then the pipe is filled with a coolant, such as a CFC substitute. When one end of the pipe is heated, the coolant evaporates and travels at high speed to the cold end. Vapor releases latent heat while traveling. The coolant vapor condenses and returns to the liquid phase. Gravity returns the re-liquefied coolant to the hot end.
Heat pipes don’t need electricity or fossil fuels to run, and they require little in the way of operation and maintenance costs. Common heat sources are ground heat, groundwater heat and hot spring heat. It’s feasible to use heat pipes when the temperature of the heat source is high enough to melt snow. Heat pipe snow melting systems are very eco-friendly.