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成果報告書詳細
管理番号20170000000247
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、および再生可能エネルギー熱利用のポテンシャル評価技術の開発 地下水を利活用した高効率地中熱利用システムの開発とその普及を目的としたポテンシャルマップの高度化
公開日2018/6/2
報告書年度2015 - 2015
委託先名日本地下水開発株式会社 国立大学法人秋田大学 国立研究開発法人産業技術総合研究所
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: Development of high performance geothermal heat pump system using groundwater and Advancement of the potential map for popularization. (FY2014-FY2016)FY2015 Annual Report

The results of a sealing up-style injection test shows that injection quantity was made to double than injection method sealing up-type and we confirmed that the method of making well was effective. We modified groundwater and heat transfer model, it based on geological feature data and the pumping test result. Using this model, we tried to simulate for 6 ways of combinations with injection temperature and the injection quantity that injected aquifer. As a result that the one that made injection temperature as high as possible became advantageous was provided. According to the results of visual comparison and water quality test, a method using electromagnetical field has an inhibitory effect on scale formation on the inner surface of a heat exchanger from groundwater. A high-efficiency heat pump was designed, which provides function of scale prevention. The heat pump has a cooling capacity of 30kW and a heating one of 30kW. Incubation studies at seven temperature conditions were performed to estimate the influence of change in temperature on subsurface bacteria using groundwater collected from four wells. There is no difference of the changes in pathogenic bacteria and related spaces, microbial communities and chemical compositions of groundwater between 15°C and other temperature. We drilled three test wells in Akita University testing site and built the semi-open loop system. Field test was performed by changing the operating conditions of the pumping and injection pump. In each test, 5 days’ resting period followed the operating period of 2 days. As a result, COP increased by 5% between the cases of pumping and injection rate of 0L/min and 15L/min since the water temperature at the heat pump inlet were maintained high as the pumping and injection rate increased. Similar SCOP was observed between the base case and 15L/min case. Also, the COP of intermittent pumping and injection rate is 15L/min was almost same as continuous pumping and injection 10L/min. Thermal properties of geological core samples obtained by all-core drilling were measured. Thermal response tests(TRT) were also carried out at the study sites in Akita City and Koriyama City. As the results of TRTs, the effective thermal conductivities were 2.01 and 1.77 W/(mK). Potential maps of Akita and Tsugaru plains were produced using the groundwater and heat transfer simulation. In the maps, optimum length of the ground heat exchanger(GHE) was estimated to be 60-90 m for Akita Plain and 30-70 m for Tsugaru Plain. In order to develop the TRT approach for groundwater well, field experiments were carried out at Akita. As the result, the normal TRT approach can be applied to the TRT using groundwater well with diameter less than 100 mm.
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