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成果報告書詳細
管理番号20170000000365
タイトル*平成27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2017/6/15
報告書年度2015 - 2015
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.
(1)Development of heat exchanger pile intended for use with buildings
The combined use of PHC(Prestressed High Strength Concrete)foundation piles which are the most often used in buildings reduces the cost in installing heat exchanger piles. In the construction of PHC piles, the pre-boring method, in which a hole is dug with auger drilling while cement milk is poured from the tip, and after the digging is complete, PHC piles are laid into the cement milk mixture, has increased, accounting for 75% as of today. We fixed the polyethylene heat exchanger pipe to the spiral reinforced columns mass produced with PHC piles, inserted it into the inner side of the pile wall, transported it to the site together. When the pile length is 15m or longer and transport is not possible and there are upper and lower piles, we developed a method of fusing together 2 spots on the polyethylene pipes in a short time. Regarding the occurrence of heat stress accompanying the combined use of foundation piles with heat exchangers, we developed a numerical simulation software.
(2)Technology development of heat exchanger pile intended for family houses to mid-sized facilities 
In family houses and mid-scale facilities, soil stabilization or concrete piles are often used to achieve bearing capacity. When constructing these, by conducting underground insertion of U-tube, installation costs are drastically reduced compared to boring methods. In H-shape prestressed concrete pile, by laying the U-tube with the outer depressions of the H-shape, we were able to press-fit the pile with the U-tube in the ground without damaging the U-tube and the pile.
(3)Development of system
At a nursery school in Fukui city, using a ground source heat pump system underground heat pump (rated value 3 kW) which obtains underground heat from the aforementioned U-tube using H-shape concrete piles and an air-source heat pump (rated value 5 kW), we constructed a floor heating system. This system uses the air source heat pump when the air temperature is about 3℃ or higher, uses the underground heat pump when it is about 3℃ lower, and uses both when there is a large burden. This system reduces installation costs by about 35% and reduces electricity costs by about 20% compared with a floor heating system powered by ground source heat pump system using U-tube bore hole heat exchanger.
(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 well and the floating and discharging of free carbon dioxide in the tank resulted in continued operations without any problem.
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