• 한국지열·수열에너지학회논문집
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• 제13권2호
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• pp.9-15
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• 2017

When applying geothermal systems in cities such as seoul where high density development prevails, the selection of geothermal system capable of obtaining a large capacity in the limited grounds is necessary. In this study, an easy-to-use design tool is developed in the form of spreadsheet by applying the calculation theory of existing closed-loop vertical ground heat exchanger that can be used in the early design stage of the open-loop ground heat exchanger. By only using the maximum cooling and heating load, it is possible to calculate optimal design open-loop ground heat exchanger. Further research is needed, we are plan to improve the program considering the heat loss of groundwater flowing in the inner casing, G-Function for Open-Loop, and verification by applying actual projects.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.9-14
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• 2006

Open loop or ground water heat pump systems are the oldest of ground-source systems. Standing column wells can be used as highly efficient ground heat exchanger in geo-thermal heat pump systems, where hydrological and geological conditions are suitable. These systems require some careful considerations for well design, ground water flow, heat exchanger selection etc This paper describes 9round water temperature variations, performances in heat ins and cool ing mode and the results of ground water analysis.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권5호
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• pp.23-29
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• 2017

This study was conducted to evaluate performance of geothermal heat exchanger (GHE) in the combined well and open-closed loops geothermal (CWG) systems. The CWG systems were designed to combine open loop geothermal heat pumps and closed loop geothermal heat pumps for high energy efficiency. GHE of the CWG systems could be installed at pumping wells for agricultural usage. To get optimal heat exchange capacity of GHE of the CWG systems, 4 GHEs with various materials and apertures were tested at laboratory scale. Polyethylene (PE) and stainless steel (STS) were selected as GHE materials. The maximum heat exchange capacity of GHEs were estimated to be in the range of 33.0~104 kcal/min. The heat exchange capacity of STS GHEs was 2.4~3.2 times higher than that of PE GHE. The optimal cross section area of GHE and flow rate of circulating water of GHE were estimated to be $2,500mm^2$ and 113 L/min, respectively. For more complicated GHE of the CWG systems, it is necessary to evaluate GHEs at various scales.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.701-706
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• 2006

Groundwater heat pump systems are the oldest of the ground-souce systems and it has various type. Standing column well type are must be located in hard rock geology site and produce sufficient water for the conventional open loop system. These system are indirect type(the building circulating loop and ground water are intercept). Existence of the exchanger the foundation protect water quality to use of open loop. The design of open loop system are concern on the power requirements. An experimental study was analysis the extremely heating operation COP of ground water heat pump system. Operation efficiency of the 50RT systems shows that, COP $2.9{\sim}5.0$ in heating operation. And generally it shows 3.4.

• 한국지열·수열에너지학회논문집
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• 제10권2호
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• pp.13-18
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• 2014

This paper proposes an optimum pipe material (PVC vs. PE) design & selection for open loop ground heat exchangers. Heat exchange efficiency and/or workability, and the need for trench insulation were investigated by comparing EWT (cooling mode) of each system. CFD simulations for the PVC and PE pipe with the same inner diameter show similar EWT. This is because the PVC pipe has a small thickness but a low thermal conductivity as compared to the PE pipe, and thus these two properties tend to offset each other. However, a hypothetically insulated pipe led to a meaningful drop of EWT. This means pipe insulation is of importance in performance of ground heat exchangers. From analyzing climate data and system operation, it is not advantageous to insulate trench pipes due to construction difficulties and ground temperature characteristics that are seasonally varied.

• 지질공학
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• 제24권4호
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• pp.487-499
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• 2014

최근 지열에너지 활용 증가 추세와 더불어 지하수 부존량이 풍부한 지역에서 수직개방형의 효율이 더 높다는 연구결과가 제시됨에도 불구하고, 국내 지열냉난방시스템의 열교환 방식은 수직밀폐형 방식이 주를 이루고 있다. 따라서, 본 연구에서는 지하수 부존량이 풍부한 지역에서 수직개방형 방식의 효율성을 검증하기 위하여, 수리지질 및 열적 특성을 반영한 최적의 지열에너지 활용 방식을 수치 모의하였다. 1차 모의 결과, 지하수 부존량이 풍부한 지역에서 지열냉난방시스템을 활용하는 경우 수직밀폐형보다 지하수를 직접 이용하는 수직개방형이 더욱 효과적인 것으로 분석되었으며, 수직개방형 중에서는 SCW (standing column well)형 보다는 주입정과 추출정이 분리된 복수관정형에서 지반과 열교환을 통해 얻을 수 있는 주입수와 추출수의 온도차 (${\Delta}$)가 커 더욱 효율적인 것으로 나타났다. 2차 모의에서는 수직개방형 지열에너지 공급방식인 단일관정형, SCW형, 복수관정형을 대상으로 열 이송, 이격거리 및 유량, 지하수 수리경사 등을 고려한 최적의 활용 방식을 검토하였으며, 이를 바탕으로 지열냉난방시스템의 지중 열교환 방식 선정 시 활용할 수 있는 흐름도를 제시하였다. 본 연구결과 제시된 다양한 선정 기준을 기초로 실제 선정 시에는 전체 지열냉난방 시스템에 대한 COP (coefficient of performance) 계산 및 세부적인 타당성 검토가 필요할 것으로 판단된다.