2004 Fiscal Year Final Research Report Summary
Groundwater survey and heat transport, modeling for optimum design of geothermal heat pump systems in Akita Plain
| Project/Area Number |
15560701
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Earth system and resources enginnering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
FUJII Hikari KYUSHU UNIVERSITY, Fujii Faculty of Engineering, Associate Professor, 工学研究院, 助教授 (80332526)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIDA Youhei Institute for Geo-Resources and Environments, AIST, 地圏資源環境研究部門, 研究員 (90356577)
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| Project Period (FY) |
2003 – 2004
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| Keywords | groundwater / geothermal heat pump / numerical modeling / Akita plain / Field survey |
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| Research Abstract |
For the efficient use of Ground Coupled Heat Pump (GCHP) systems on shallow deposits, the understanding of the local groundwater flow system is highly important. This research was conducted in Akita Alluvial Plain, Japan, to clarify the following items : (1) analysis of groundwater flow systems using field survey result, (2) development of field-wide groundwater flow model in Akita Plain, (3) prediction of long-term operation performance of a large-scale GCHP system.
In field surveys, groundwater samplings were carried out in deep and shallow boreholes. In shallow boreholes, groundwater levels were measured to draw groundwater level maps. In deep boreholes, groundwater temperatures were measured every 21n to collectt groundwater flow profiles along wells. PH and EC were measured at well sites.
For groundwater flow modeling, 3D groundwater and heat transport software "FEFLOW" was used to construct a field-wide groundwater model in Akita Plain. Numerical simulations showed that the average groundwater velocity in the central part of Akit.a Plain is 1. 38X 10-4 (m/d), from east to west. The field survey results showed good agreements with numerical simulation results. The model of a single Ground Heat Exchanger (GHE) showed that heat extraction rates are enhanced if groundwater flows with Peclet numbers equal or higher than 0.1 exist in the aquifer under exploitation. With the multi-well model, the importance of heat storage operation of att least two months per year was determined. The multi-well model also showed that larger spacing between GHEs is preferable in GCHP system that will not include heat storage operations during the summer months.
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