Hydronic Pavement Using Low Temperature Borehole Thermal Energy Storage
Paper in proceedings, 2016
Winter conditions on roads are a challenge for road administrators in cold climates and with increased public demands on safety, winter maintenance activities will increase. The most common winter maintenance activity in Scandinavia is anti-icing, which is performed when it is a risk for ice formation on the road surface. Commonly a truck is utilized for spreading freeze point depressant, like salt, on the pavement thereby lowering the freezing point and preventing ice formation on the surface. This method has been questioned for a number of reasons e.g. salts have negative effects on the local environment. An alternative method for de-icing is to use hydronic pavement (HP). HP consists of a pipe network, embedded inside the pavement, in which a fluid is circulated. The fluid collect solar energy during summer days and transports heat back to the road surface during icy winter days. The harnessed and released energy should be in balance, otherwise an additional heat sources is needed. This study has investigated the possibility of developing an alternative strategy to heat the pavement surface with stored low temperature fluids. By using the methodology, and software BRIDGESIM, a preliminary design of a hydronic pavement system have revealed that it is not feasible to design a system for the cold climate of Ö stersund (Sweden); only relying on harnessing solar energy and store the energy in a borehole thermal energy storage. However it was revealed that it is possible to design HP system for low supply temperatures of about 7 °C. Which is far below the supply temperature of about 35 °C, recommended by manufacturers of HP system. The prospect of utilizing low-temperature heat sources would make HP system more energy efficient which could make it an alternative to traditional winter maintenance methods.