• 한국지열·수열에너지학회논문집
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• 제4권2호
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• pp.1-7
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• 2008

GSHP(Ground Source Heat Pump) has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the system reliability has been key issues and barriers to insure a better system performance as designed originally in ISO (international standard organization) standard. This paper introduces a systematic method to verify its intended design target so called as ISO performance data based commissioning technology for a water to air GSHP system. The commissioning technology starts from are to the international standard ISO performance data of a GSHP model and to compare its installed operation data and to calibrate and tune to the target optimum operation parameters. Results indicated that cooling capacity could be raised up to 76.6% from 46.6% from this proposed commissioning technology.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.3-32
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• 2008

The potential deep geothermal resources span a wide range of heat sources from the earth, including not only the more easily developed, currently economic hydrothermal resources; but also the earth's deeper, stored thermal energy, which is present anywhere. At shallow depths of 3,000~10,000m, the coincidence of substantial amounts heat in hot rock, fluids that heat up while flowing through the rock and permeability of connected fractures can result in natural hot water reservoirs. Although conventional hydrothermal resources which contain sufficient fluids at high temperatures and geo-pressures are used effectively for both electric and nonelectric applications in the world, they are somewhat limited in their location and ultimate potential for supplying electricity. A large portion of the world's geothermal resource base consists of hot dry rock(HDR) with limited permeability and porosity, an inadquate recharge of fluids and/or insufficient water for heat transport. An alternative known as engineered or enhanced geothermal systems(EGS), to dependence on naturally occurring hydrothermal reservoirs involves human intervention to engineer hydrothermal reservoirs in hot rocks for commercial use. Therefore EGS resources are with enormous potential for primary energy recovery using an engineered heat mining technology, which is designed to extract and utilize the earth's stored inexthermal energy. Because EGS resources have a large potential for the long term, United States focused his effort to provide 100GW of 24-hour-a-day base load electric-generating capacity by 2050.

• 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 2008년도 하계학술발표대회 논문집
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• pp.782-787
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• 2008

The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2002년도 춘계 공동학술발표회
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• pp.458-462
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• 2002

• 한국지열·수열에너지학회논문집
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• 제13권4호
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• pp.14-20
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• 2017

Refrigerant having high global warming potentials will be phased out due to environmental protection issues. R410A has been widely used in geothermal heat pump. However, it has a little high GWP by 2088 value. One of the recommended substitute for R410A refrigerant is R452B which having a GWP by 698 value. In this paper, the heating and cooling performance of the water-to-water geothermal heat pump unit with R452B was experimentally investigated. The performance of the heat pump adopting R452B was also compared with the system applying R410A. The heating and cooling capacity of R452B heat pump system showed a slightly lower values within 2% comparing with R410A system. However, the R452B system's coefficient of performance was enhanced by 5.2% and 13.7% at heating and cooling mode, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.171.2-171.2
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• 2010

Geothermal effects on the underground water conveyance pipe system have been investigated through the multiregional water supply system from Paldang water intake station. To make an investigation of raw water thermal energy, temperature sensors are installed the surface of the pipes of metropolitan area water supply system. In 2009 winter and early spring seasons, the monthly averaged temperatures at Paldang 2 intake stations are $1.94^{\circ}C$ in February, $4.96^{\circ}C$ in March, and $10.56^{\circ}C$ in April. After the transfer in 26.0 km distance of tunnel and buried pipe, the raw water temperatures are raised to $3.13^{\circ}C$, $6.04^{\circ}C$, and $11.39^{\circ}C$ respectively. As the temperature difference between the raw water and the air reduces, the temperature increasement is reduced by $1.19^{\circ}C$ in Feb., $1.08^{\circ}C$ in Mar., and $0.83^{\circ}C$ in Apr. Since the flowrate is over 1,150,000 $m^3$/day, it is estimated that the water exchanges a huge amount of heat over 1.0 Tcal a day with the ground.

• 한국지열·수열에너지학회논문집
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• 제4권2호
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• pp.9-14
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• 2008

400RT geothermal system which is consist with vertical-typed 112 geothermal heat exchangers is measured and evaluated in spring, 21st${\sim}$24th May 2008. As the results, the average temperature difference between inlet and outlet of geothermal pipes is $1{\sim}2^{\circ}C$ and that of cool water supply is $2{\sim}6^{\circ}C$, when being normally operated. Despite temperature fluctuations by cooling loads, the average temperature difference between main pipes of inlet and outlet of geothermal heat exchangers is measured as $3^{\circ}C$. The geothermal system COPs are calcluated as 2.92${\sim}$3.92 in every 12 hours.

• 자원환경지질
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• 제39권5호
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• pp.537-554
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• 2006

유성지구 지열수의 산출 특성 및 수리적 연결성을 파악하기 위하여 2002년 3월부터 2005년 6월까지 장기 수위 관측을 실시하였다. 관측된 수위 자료를 이용하여 수위변동 주기 분석을 실시한 결과, 대부분의 관측공에서 0.5일, 1일, 7일 주기성이 확인되었다. 7일 주기성은 온천지대에서의 독특한 양수 행태로 인해 발생되는 인위적 현상으로서, 연구 지역내 관측공들의 수리적 연결성이 양호한 것을 반영하였다. 수위 영향 관계를 분석한 결과, E-W 방향성과 N-S 방향성의 지질구조가 지열수 저류체의 발달 및 지열수 유동에 중요한 규제 요소로 작용되고 있음이 확인되었다. 전반적으로 지열수의 열원과 대수층의 수리적 연결성과는 상호 연관성이 있을 것으로 해석된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.485-488
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• 2007

Riverbank filtration is a kind of artificial aquifer recharge for the fresh water supply. By construction of several production wells penetrating the riverbank, surface water withdrawn from the river would pass riverbed. This extracted water is well known to be cooler than surface water in summer and warmer than surface water in winter, showing more constant water temperature. This characteristic of extracted water is applied to geothermal energy utilization. Prediction of the annual temperature variation of filtrated water is the major concern in this study. In Daesan-myeon, Changwon-si, Gyeongsangnam-do, South Korea, riverbank filtration facility has been on its operation for municipal water supply and thermal energy utilization since 2006. Appropriate hydraulic and thermal properties were estimated for flow and heat transfer modeling with given pumping rate and location. With the calibrated material properties and boundary conditions, we numerically reproduced measured head and temperature variation with acceptable error range. In the numerical simulation, the change of saturation ratio and river stage caused by rainfall was calculated and the resulting variation of thermal capacity and thermal conductivity was considered. Simulated temperature profiles can be used to assess the possible efficiency of geothermal energy utilization using riverbank filtration facility. Influence of pumping rate, pumping location on the extracted water temperature will be studied.