Hydronic Heating Pavement with Low Temperature: The Effect of Pre‐Heating and Fluid Temperature on Antiicing Performance

A renewable method to mitigate the slippery condition on road surfaces is to use Hydronic Heating Pavement (HHP) system. The HHP system consists of embedded pipes in the road which a fluid as thermal energy carrier circulates through the pipes. The aim of this study it to evaluate the effects of pre-heating the road surface and different fluid temperatures on the anti-icing performance of the HHP system. A two- dimensional numerical simulation model was developed using finite element method in order to calculate the annual required energy and remaining hours of the slippery conditions on the road surface. The numerical simulation was validated by an analytical solution associated with an infinite region bounded internally by a pipe with a constant temperature. The validation result related to the heat flow and integrated heat loss from the pipe showed that for the running time longer than 20 minutes, the maximum relative error is less than 4% between the numerical simulation and the analytical solution. In order to evaluate the anti-icing performance of the HHP system, the climate data from 6stersund, an area in middle of Sweden with cold and long winter period, were selected. Results showed that pre-heating the road considerably shortened the slippery hours of the road surface

Preliminary study of an Energy Harvesting System for Road Pavements made with Marginal Aggregate

The progressive reduction of available energy resources and the continuous increase in demand are providing strong incentives for the use of renewable energies. Asphalt solar collectors are efficient energy harvesting systems for roads, able to extract thermal energy from pavements and convert the heat collected by their surfaces. Indeed, the possible reuse of waste materials in road construction, converted into valuable resources, has a strategic importance and could surely enhance the envi-ronmental sustainability of road pavement applications. This paper presents a pre-liminary experimental study aimed at evaluating the feasibility of a pipe-based en-ergy harvesting system, which allows fluid circulation on a coil embedded in asphalt concrete manufactured with marginal aggregates. For this purpose, two-layer dense-graded asphalt slabs (AC8) were prepared in the laboratory, using different aggre-gate types (limestone and steel slag). A steel coil positioned at the interface was uti-lized to establish water circulation below the wearing course. The collected thermal energy was measured varying the water flow characteristics; the system was moni-tored through thermographic analysis while being subjected to a selected radiative power. Main results indicated that water flow rate was crucial in determining the temperature mitigation effect on asphalt concrete surfaces and the efficiency of the energy harvesting system. Some concerns about the operative approach were evinced (mainly related to the scale of the test); however, steel slag inclusion did not seem to compromise nor enhance the thermal conductivity of mixtures