• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3164-3169
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• 2013

In this study, a series of CFD analysis was performed in order to predict the leaving water temperature and the slope of in-situ thermal response tests of the vertical-type geothermal heat exchangers. The geothermal heat exchanger and surrounding ground formation were modeled using GAMBIT and simulation was used by utilizing FLUENT which is commercial CFD code. Comparing with the results of CFD and in-situ thermal response tests, the results of CFD was presented good agreement with $0.5^{\circ}C$ difference of Leaving Water Temperature and with 1.6% difference of the Slope.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.42-49
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• 2012

신경망방법은 공학, 경영 그리고 정보기술과 같이 다양한 분양에서 널리 사용되어지고 있다. 신경망방법은 기본적으로 예측, 제어, 식별과 같은 기능을 가지고 있는데, 본 논문에서는 신경망방법을 이용하여 C사의 모델 T의 히트펌프 전기부하를 예측하였다. 부하예측은 시스템을 더욱 효율적이고, 적절하게 만들기 위해 필요하다. 본 논문에서 사용된 히트펌프는 지열원 히트 펌프 시스템이다. 이 지열 히트 펌프의 부하는 사전에 미리 예측되어진 외기온도 및 건물 열부하에 따라 측정 학습된 전력 소비량으로 겨울에는 난방, 여름에는 냉방에 대한 전력 부하를 예측할 수 있다. 이 신경망방법은 신경망 학습 순서를 통해 부하 예측을 위해 히트펌프의 성능데이터를 필요로 한다. 이 부하 예측 인공지능망 방법으로 외기 온도별 건물 통합형 지열 히트 펌프 부하가 예측되어질 수 있다.

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.19-25
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• 2013

In this study, the cooling experiment was carried out in $1,650m^2$ area of the seedling greenhouse from June 6, 2011 to september 18, 2011 with the vertical type geothermal heat pump system of 350 kW scale (175 kW ${\times}$ 2 units) installed in the greenhouse, cooling effects were analyzed and we tried to find more effective operation methods of the geothermal heat pump system. In case of one unit heat pump (175 kW) operation, when evaporator inlet water temperature changed from $13.0^{\circ}C$ to $15.5^{\circ}C$, cooling COP of the system was in 1.1~1.8 range and in case of two unit heat pump (350 kW) operation, when evaporator inlet water temperature changed from 13.0 to 15.5, cooling COP of the system was in 2.0~2.7 range. The accumulated cooling heat quantity of June, July, August and September was 14,718.6, 26,765.1, 28,437.2 and 10,065.0 kWh, respectively.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.4 no.2
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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.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.1
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• pp.9-16
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• 2020

In this study, a numerical study was conducted to evaluate the performance improvement when CuO nanofluid was used in the plate heat exchanger. As a result, the heat transfer amount is increased by 5.45% when 2 vol% CuO nanofluid is used. The influence on the CuO nanofluid on the performance of heat exchanger is decreased by increasing the flow rate of working fluid. In addition, the overall heat transfer coefficient using 2 vol% CuO nanofluid decreased compared to the base fluid. However, the pressure drop and the consumption of the pump power is increased as the concentration of CuO nanofluid increased because the increase of the viscosity. These are increased up to 15.4% compared to those of the base fluid. Moreover, the performance index of CuO nanofluid is decreased by 12.6% compared to that of the base fluid.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.69-76
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• 2010

In this study, the solar thermal and geo-source heat pump(GSHP) hybrid system for heating and cooling of Zero Energy Solar House(ZESH) was analyzed by experiment. The GSHP in this hybrid system works like as aback-up device for solar thermal system. This hybrid system was designed and installed for Zero Energy Solar House (KIER ZeSH) in Korea Institute of Energy Research. The purpose of this study is to find out that this system is optimized and operated normally for the heating load of ZeSH. The analysis was conducted as followings ; - the thermal performance of facade integrated solar collector - the on/off characteristics of solar system and GSHP - the contribution of solar thermal system. - the performance of solar thermal and ground source heat pump system respectively. - the meet of thermal load (space and water heating load). This experimental study could be useful for the optimization of this system as well as its application in house. This hybrid system could be commercialized for the green home if it is developed to a package type.

• KIEAE Journal
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• v.17 no.3
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• pp.119-124
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• 2017

Purpose: Groundwater heat pump (GWHP) system has high coefficient of performance than conventional air-source heat pump system and closed-loop type geothermal system. However, there is problem in long-term operation that groundwater raise at the diffusion well and reduced at the supply well. Therefore, it is necessary to accurately predict the groundwater flow, groundwater movement and control the groundwater level in the wells. In this research, in consideration of hydrogeological characteristic, groundwater level and groundwater movement were conducted analysis in order to develop the optimal design method of the two-well system using the pairing pipe. Method: For the optimum design of the two-well system, this research focused on the design method of the pairing pipe in the simulation model. Especially, in order to control the groundwater level in wells, pairing pipe between the supply well and diffusion well was developed and the groundwater level during the system operation was analyzed by the numerical simulation. Result: As the result of simulation, the groundwater level increased to -2.65m even in the condition of low hydraulic conductivity and high pumping flow rate. Consequently, it was found that the developed system can be operated stably.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.1
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• pp.7-13
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• 2014

This study intends to analyse the economical aspect of a GSHP(Ground Source Heat Pump) system compared to the conventional system which is consisted with a boiler and a chiller. This study has simulated four systems in Incheon. It developed and analyzed for applications in a residential and an office building which was based on the hourly EPI(Energy Performance Index, $kWh/m^2yr$). Case 1 is utilizing a boiler and a chiller to meet heating and cooling demand of a house. Case 2 is utilizing the same conventional set up as Case 1 of a office. Case 3 is summation of Case 1(house) and 2(office) systems and loads. And Case 4 is utilizing a GSHP to meet the combined loads of the house and office. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask-C SPB(Simple Payback) method. The SPB calculated the economic balanced year of the alternative system over the reference system. The SPB of the alternative systems (GSHP) with 10%, 30% and 50% initial incentive has been calculated as 9.38, 6.72 and 4.06 year respectively while the SPB without initial incentive of systems was 10.71 year.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.19 no.4
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• pp.39-52
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• 2023

This study analyzes the energy performance of a elderly care center building and the applicability of a ground source heat pump (GSHP) system through simulation approach. For this purpose, a building information modeling (BIM) program and an energy performance calculation program were used. The impact of the mechanical ventilation system on the energy requirements of the heating and cooling system and the indoor environment was also analyzed, focusing on the change in indoor carbon dioxide (CO₂) concentration, which is a representative indicator of the indoor environment (air quality). The simulation results showed that the target building exceeds Level 7 in terms of simulated primary energy consumption or actual energy consumption. In addition, it was analyzed that the target building could not maintain the indoor CO₂ concentration below the standard concentration by natural ventilation through window opening alone. Combining the GSHP system with the mechanical ventilation system (Case B and Case C) can further reduce the overall energy consumption by reducing the amount of outdoor air introduced by opening windows. The cost savings compared to the baseline case are estimated to be 67.3% for Case A, 63.7% for Case B, 65.5% for Case C, and 42.5% for Case D. It is necessary to analyze the impact of various renewable energy technologies and passive ones on the energy performance and indoor environment of elderly care centers.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.1-6
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• 2022

Ground source heat pump (GSHP) system is highly efficient and environment-friendly and supplies heating, cooling and hot water to buildings. For an optimal design of the GSHP system, the ground thermal properties should be determined to estimate the heat exchange rate between ground and borehole heat exchangers (BHE) and the system performance during long-term operating periods. However, the process increases the initial cost and construction period, which causes the system to be hindered in distribution. On the other hand, much research has been applied to the artificial neural network (ANN) to solve problems based on data efficiently and stably. This research proposes the predictive performance model utilizing ANN considering local characteristics and weather data for the predictive performance model. The ANN model predicts the entering water temperature (EWT) from the GHEs to the heat pump for the modular GHEs, which were developed to reduce the cost and spatial disadvantages of the vertical-type GHEs. As a result, the temperature error between the data and predicted results was 3.52%. The proposed approach was validated to predict the system performance and EWT of the GSHP system.