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成果報告書詳細
管理番号20170000000367
タイトル*平成28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2016 - 2016
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 (FY2014-FY2018) FY2016 Annual Report
 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 exchanger piles.
(1) Development of heat exchanger pile intended for use with buildings
 The combined use of Prestressed High Strength Concrete foundation piles which are the most often used in buildings of 25 floors or less reduces the cost. We fixed the polyethylene U-tube to the spiral reinforced columns, inserted it into the inner side of the pile wall, transported it to the site together. This year, the measured water temperatures brought back from the exchange piles were in accordance with the calculated values. This verifies the performance of the simulation software and the heat exchange piles. Regarding the heat stress of foundation piles, the heat stress is strongest at the center of the pile depth, but we confirmed that at that point the loading axial force was reduced and there was no strength insufficiency from the measured values and numerical simulations.
(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. 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. This method reduced the construction cost by 40% compared to boring methods.
(3) Development of system
At a nursery school in Fukui city, using a 3 kW ground source heat pump system using H-shape concrete piles and an 5 kW air-source heat pump, we constructed a floor heating system. This system uses the air source heat pump when the air temperature is 3℃ or higher, uses the underground heat pump when it is 3℃ lower, and uses both when there is a large burden.
 The Coefficient Of Performance of floor heaters was 3.3 in 2016. By replacing the heat exchanger of the geothermal heat pump this year, the COP has raised from 3 to 4. In summer cooling, we drained the waste heat from the geothermal heat pump into the heat exchange coils inside the hot water supply tank. The COP including the hot water supply rose from 3.4 to 3.9. We conducted hot water supply preheating in October using the heat pump, and obtained a COP of 4.2. Considering all of this comprehensively, going from floor heating and cooling with the 8 kW bore hole geothermal heat pump to the hybrid heat pump floor heating and cooling and hot water supply use will reduce installation costs and operation costs over 15 years by 40% in total.
(4) Development of groundwater circulation and utilization technology
Although the shallow groundwater in an alluvial plain contains much iron, the oxygen insulation in the well resulted in continued operations without any problem.
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