再生エネルギー研究センターパンフレット（英語）

15/20

14●Technology development for GSHP systems optimization　The team is evaluating optimal heat exchange system that can efficiently utilize shallow (depth: 1-2 m) or deep (depth: about 100 m or less) heat exchanger and is developing a more efficient heat exchange system using site specific hydrogeological condition. At GSHP experiment field of FREA and at the Geological Museum of AIST in Tsukuba City, identical GSHP systems combining various types of horizontal heat exchangers and vertical heat exchangers are installed to investigate and evaluate the differences of two areas, having different hydrogeological settings, in optimal heat exchange method and their efficiency, by long-term monitoring and numerical simulation. Through “visualization” of GSHP system, with a real-time display of the operating state and exposition of heat exchange borehole, the team aims to promote and diffuse GSHP system.A numerical model of a heat exchangerA sheet-type heat exchanger (buried at a depth of 1-2 m)Main Research FacilitiesFREA Ground-Source Heat Pump System Demonstration AreaThis is a GSHP system using a sheet-type heat exchanger and a Slinky-type heat exchanger installed at a depth of 1-2 m and a vertical-type (borehole type) heat exchanger installed to a depth of about 40 mA ground source heat pump (GSHP) system installed at the Chulalongkorn University, ThailandA facility at the Chulalongkorn University in Thailand was used to demonstrate the possibility of cooling operation through the GSHP system in Bangkok.※GSHP: Ground Source Heat PumpHeat exchanger (sheet type)Heat exchanger (slinky type)Heat exchanger(borehole type)Activities and Achievements①GSHP suitability evaluation of the Tsugaru Plain　The team constructed a groundwater-flow and heat-transport model with the result of the incorporated thermal response test (TRT) [Fig. 1]. The team estimated effective thermal conductivity distribution based on the results of flow simulation and TRT, and overlapped the effective thermal conductivity on a subsurface temperature distribution map with Geographic Information System (GIS) to invent a totally new suitability map (for heating) [Fig. 2]. Combining the existing observation well data with the results of the TRT, a high-precision map could be created from few observation well data (original technology of AIST).②Analysis of hydro-geological structure of the Aizu Basin　Through a joint research with the Fukushima University, the team conducted an analysis of geological structures of the Quaternary layers and of hydraulic structure (including subsurface temperature structure) in the Aizu district, Fukushima Prefecture to reconstruct the basic data to assess the suitability of the GSHP systems.③Performance evaluation of a closed-loop GSHP air-conditioning system using an artesian well　The team constructed a closed-loop GSHP system using an artesian well by a joint research project with Japan Ground Water Development Co., Ltd. through “Program for Promoting Technologies Invented by Industry in Disaster Areas in Tohoku.” The team built a system to control the natural flow by the well temperature. COP greater than seven in the cooling operation and COP greater than five in the heating operation were observed, which depends on the operating condition, though.Fig. 1: Three-dimensional groundwater-flow 　　　 and heat-transport model of the Tsugaru PlainFig. 2: A new suitability mapDrilling site