成果報告書詳細
管理番号20150000000509
タイトル*平成26年度中間年報 再生可能エネルギー熱利用技術開発 地中熱利用トータルシステムの高効率化技術開発及び規格化 共生の大地への地中蓄熱技術の開発
公開日2015/9/1
報告書年度2014 - 2014
委託先名国立大学法人福井大学 三谷セキサン株式会社
プロジェクト番号P14017
部署名新エネルギー部
和文要約
英文要約Title: Renewable Energy Heat Utilization Technology / Development and Standardization of Efficiency Increasing Technology of Total System for Geo-Heat Utilization / Development of Underground Heat Storage Technology in Symbiotic Ground
Foundation piles are employed for most of the buildings and houses in the urban cities in Japan. Utilizing such foundation piles will make it possible to reduce the installation cost of geothermal heat exchange piles. We will aim for coexistence of urban cities and the global environment and the symbiotic ground through the coexistence with technologies that support buildings, geothermal heat exchange piles, and further with air conditioning, hot-water supply, etc. The objective shall be to reduce 20% of the installation cost and the maintenance cost, respectively, by developing the following items:
(1)Development of heat exchanger pile intended for use with buildings
The installation cost will be reduced by utilizing the Prestressed High strength Concrete (PHC) foundation piles, which are most frequently used for buildings, also as the heat exchanger piles. The bottom of the pile is blocked with a steel plate, water is pooled in the cavity within the pile wall, and the water is circulated to the heat exchanger with a pump, thereby collecting the geothermal heat. Since a pile having the length exceeding about 15 m is hard to transport, several piles are jointed with bolts and nuts at the job site. When water is stored, the water leaks from the bolt joints. Therefore, water leakage was eliminated by inserting the water-swelling rubber between the upper and the lower joint. The work to bury a PHC pile having the length of about 30 m or over will become difficult because of the buoyance force. Therefore, for a long pile, it was decided to fix polyethylene pipes on the inner surface side of the pile wall. We considered it would be good to fix the polyethylene pipes and turn the polyethylene pipes around at the upper and the lower ends of the pile. At many of such turned-around portions, the polyethylene pipes are inserted into steel pipes having slightly larger diameter than the polyethylene pipes, and the steel pipes are bent with the bending machine.
(2)Technology development of heat exchanger pile intended for family houses to mid-sized facilities
The installation cost will be reduced by utilizing the foundation piles or the columnar improvement method also as the heat exchanger piles. Since the pile length here will become shorter to 5 m to 10 m, the impact of the heat on the surface of the ground becomes larger. We developed the numerical simulation software in which the ground surface heat balance beneath the building or road was taken into consideration.
(3)Development of underground heat storage system
Regarding the development of a system where refrigerated air conditioning in summer and hot-water supply are added to the floor panel heating utilizing air and geothermal heat, we built an experimental facility along with the new construction of a nursery school.
(4)Development of groundwater circulation and utilization technology
Although the shallow groundwater in an alluvial plain contains much iron and free carbon dioxide, the oxygen insulation in the circuit and the well and the floating and discharging of free carbon dioxide in the tank resulted in continued operations without any problem. We developed the investigation technique to estimate the well capacity.
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