Development of long-term underground thermal energy storage roadway snow-melting system Isobe, Etsuhiro et al
Language: English Language: French Series: ; topic IV-82Publication details: XIth international winter road congress 2002. Sapporo [Japan] / XIe congres international de la viabilite hivernale 2002, Sapporo [Japon]. Paper, 2002Description: 10 sSubject(s): Bibl.nr: VTI 2002.0071Location: Abstract: The cold, snow-covered regions in Japan account for nearly 61% of the total area of the slender Japanese archipelago extending from north to south. The expansion of distribution networks in recent years has been driving up the demand for non-water spraying type snow-melting systems, ensuring mobility and creating a safe living environment even in extreme snow-belt and mountainous areas during the winter months. The authors have been actively involved in the technical development of snow-melting systems that make effective use of natural energy, aiming to construct an eco-friendly snow-melting system and to cut down running costs of non-water spraying type snow-melting systems. Among its projects, The authors have developed the new snow-melting system incorporating long-term (seasonal) thermal energy storage technology that harnesses solar energy, which has no detrimental effects on the region's ecology, and which can be collected in adequate amounts in the summer season. The features of the new snow-melting system are: (1) A snow-melting system in which road heating pipes buried under roads are used for collecting solar energy during the summer season and for raising the temperature of the water circulating in them. Thus, the solar energy is collected and stored as thermal energy under the ground. In winter, the heat stored underground is recovered effectively and used to melt the snow on the road through the heating pipes; (2) Borehole thermal energy storage (BTES) that is very economical and generally unaffected by constraints of the installation location and the excavation cost. Multiple boreholes are excavated vertically into which heat exchanger pipes are inserted for exchange of heat between hot water and underground heat; and (3) By backfilling the space between the heat exchanger pipe and the borehole with a heat-transfer filler (filler containing grout mixed with carbon or iron particles) having high thermal conductivity, effective heat exchange becomes possible. Results as given below were obtained from tests carried out to evaluate this system: (1) The amount of solar energy collected by the asphalt pavement was 3.4 (MJ/m2) in August, 1.2 (MJ/m2) in September and -0.2 (MJ/m2) in October. The amount of solar energy collected by the asphalt pavement was about 20 per cent of the unobstructed solar radiations received by the pavement; (2) The borehole heat recovery rate varies depending on the input temperature of the heat exchange pipes but this rate was stable over the long term; and (3) It is possible to improve the heat transfer rate underground by using a heat-transfer filler. Compared to conventional fillers, the heat recovery performance increases by a factor of about 1.16 when mixed with carbon particles and by a factor of 1.43 when mixed with iron particles.Current library | Call number | Status | Date due | Barcode | |
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Statens väg- och transportforskningsinstitut | Available |
The cold, snow-covered regions in Japan account for nearly 61% of the total area of the slender Japanese archipelago extending from north to south. The expansion of distribution networks in recent years has been driving up the demand for non-water spraying type snow-melting systems, ensuring mobility and creating a safe living environment even in extreme snow-belt and mountainous areas during the winter months. The authors have been actively involved in the technical development of snow-melting systems that make effective use of natural energy, aiming to construct an eco-friendly snow-melting system and to cut down running costs of non-water spraying type snow-melting systems. Among its projects, The authors have developed the new snow-melting system incorporating long-term (seasonal) thermal energy storage technology that harnesses solar energy, which has no detrimental effects on the region's ecology, and which can be collected in adequate amounts in the summer season. The features of the new snow-melting system are: (1) A snow-melting system in which road heating pipes buried under roads are used for collecting solar energy during the summer season and for raising the temperature of the water circulating in them. Thus, the solar energy is collected and stored as thermal energy under the ground. In winter, the heat stored underground is recovered effectively and used to melt the snow on the road through the heating pipes; (2) Borehole thermal energy storage (BTES) that is very economical and generally unaffected by constraints of the installation location and the excavation cost. Multiple boreholes are excavated vertically into which heat exchanger pipes are inserted for exchange of heat between hot water and underground heat; and (3) By backfilling the space between the heat exchanger pipe and the borehole with a heat-transfer filler (filler containing grout mixed with carbon or iron particles) having high thermal conductivity, effective heat exchange becomes possible. Results as given below were obtained from tests carried out to evaluate this system: (1) The amount of solar energy collected by the asphalt pavement was 3.4 (MJ/m2) in August, 1.2 (MJ/m2) in September and -0.2 (MJ/m2) in October. The amount of solar energy collected by the asphalt pavement was about 20 per cent of the unobstructed solar radiations received by the pavement; (2) The borehole heat recovery rate varies depending on the input temperature of the heat exchange pipes but this rate was stable over the long term; and (3) It is possible to improve the heat transfer rate underground by using a heat-transfer filler. Compared to conventional fillers, the heat recovery performance increases by a factor of about 1.16 when mixed with carbon particles and by a factor of 1.43 when mixed with iron particles.