• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.36-39
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• 2006

To evaluate the effect of groundwater flow on the outlet temperature of a geothermal heat pump, 3 dimensional numerical simulations are performed considering both groundwater flow and pipe flow in the U-tube using TOUGHS, The present study involved the following 4 simulation cases (1) no groundwater flow, (2) slow groundwater flow (hydraulic conductivity: $1.0{\times}10^{-9}m/s)$, (3) fast groundwater flow (hydraulic conductivity, $1.0{\times}10^{-7}m/s$), and (4) groundwater flow varying with the depth (hydraulic conductivity: $1.0{\times}10^{-7}-1.0{\times}10^{-10}m/s$). The effect of groundwater flow on the outlet temperature is significant where hydraulic conductivity of aquifer is $1.0{\times}10^{-7}m/s$. Where hydraulic conductivity of aquifer is $1.0{\times}10^{-10}m/s$, however, that effect is negligible.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.5-8
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• 2006

The Alternative energy has lately attracted considerable attention due to the high oil price and environment problem. In this study, pilot test facility for using the geothermal energy source from riverbank filtration was constructed and monitoring devices are installed to estimate the efficiency of this system. Initial installation cost can be saved efficiently by connect ing a heat pump system into the exist ing pumping well in Changwon riverbank filtration site. One set of monitoring results during summer was presented and analyzed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.289-296
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• 2012

The aim of this study is to investigate the performance of a heating and cooling system with aquifer thermal energy storage(ATES heat pump system) known as one of the underground thermal energy storage application systems. The ATES system was composed of heat pump unit and ATES, which was installed in a factory building located in Anseoung. The system represented very high heating and cooling performance, and showed nearly constant COP at each heating and cooling season due to the stability of EWT. The economic analysis about an ATES system and a conventional system was also executed. The conventional system adopted an air-conditioner in the summer season and a LNG boiler in the winter season. The payback period of the ATES system was estimated by 6.62 years.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.2
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• pp.36-47
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• 2012

Time-series variation of groundwater temperature in Mongolia shows that maximum temperature is occured from end of October to the first of February(winter time) and minimum temperature is observed from end of April to the first of May(summer time). Therefore ground temperature is s a good source for space heating in winter and cooling in summer. Groundwater temperatures monitored from 3 alluvial wells in Ulaabaatar at depth between 20 and 24 m are $(4.43{\pm}0.8)^{\circ}C$ with average of $4.21^{\circ}C$ but mean annual ground temperature(MAGT) at the depth of 100 m in Ulaanbaatar was about $3.5{\sim}6.0^{\circ}C$. Bore hole length required to extract 1 RT's heat energy from ground in heating time and to reject 1 RT's heat energy to ground in summer time are estimated about 130 m and 98 m respectively. But in case that thermally enhanced backfill and U tube pipe placement along the wall are used, the length can be reduced about 25%. Due to low MAGT of Ulaabaatar such as $6^{\circ}C$, the required length of GHX in summer cooling time is less than the one of winter heating time. Mongolia has enough available property, therefore the most cost effective option for supplying a heating energy in winter will be horizontal GHX which absorbs solar energy during summer time. It can supply 1 RT's ground heat energy by 570 m long horizontally installed GHX.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.1
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• pp.45-50
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• 2011

Hybrid desiccant cooling system(HDCS) consists of desiccant rotor, regenerative evaporative cooler, heat pump and district heating hot water coil. In this study, TRNSYS and EES, dynamic and steady simulation programs were used for studying hybrid desiccant cooling system which is applied to an apartment house from June to August. The results show that power consumption of the hybrid desiccant cooling system is 70 kWh in June, 199 kWh in July and 241 kWh in August. Sensible and latent heats removed by the hybrid desiccant cooling system are 300 kWh, 301 kWh in June, 610 kWh, 858 kWh in July and 719 kWh, 1010 kWh in August. COP of the hybrid desiccant cooling system is 8.6 in June, 7.4 in July and 7.2 in August. COP of the hybrid desiccant cooling system decreases when latent heat load increases. Operation time of the system is 70 hours in June, 190 hours in July and 229 hours in August. Since the cooling load is largest in August, the operation time of August is longest for maintaining the indoor temperature at $26^{\circ}C$. Due to the characteristics of hybrid desiccant cooling system for efficiently handling both sensible and latent loads, this system can handle sensible and latent heat loads efficiently in summer.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.143.2-143.2
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• 2011

Energy foundations and other thermo-active ground structure, energy wells, energy slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and heat sink in summer season. The system represented very high heating and cooling performance due to the stability of EWT from energy slab. Maximum heat pump unit COP and system COP were 4.9 and 4.3.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.87-93
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• 2018

Ground source heat pump(GSHP) system is one of the high efficiency heat source systems which utilizes the constant geothermal energy of a underground water or soil. However, the design of conventional GSHP system in the domestic market is dependent on the experience of the designer and the installer, and it causes increase of initial installation cost or degradation of system performance. Therefore, it is necessary to develop a guideline and the optimal design method to maintain stable performance of the system and reduce installation cost. In this study, in order to optimize the GSHP system, design factors according to ground heat exchanger(GHX) type have been examine by simulation tool. Furthermore, the design factors and the correlation of a single U-tube and a double U-tube were analyzed quantitatively through sensitivity analysis. Results indicated that, the length of the ground heat exchanger was greatly influenced by grout thermal conductivity for single U-tube and pipe spacing for double U-tube.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.139-140
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• 2013

Ground source heat pump systems can achieve the energy saving of building and reduce CO₂ emission by utilizing stable ground temperature. However, they have many barriers such as high cost of installation, incompletion of design tool, lack of recognition as heating and cooling systems. In order to solve the problems, the building integrated geothermal system (BIGS) developed by several researches which use building foundation as a heat exchanger. In order to establish the optimum design tool of BIGS with the horizontal heat exchanger, the prediction method of ground heat exchange rate developed with numerical simulation model. In this study, the economic analysis for BIGS was conducted based on simulation results and the optimal design method was suggested. As a result, it was found that the case of 32 A, piping space 0.3 m, piping deep 0.5 m and flow rate 9.52 L/min was the best case as 50.1 W/m2 of heat exchange rate. In this case the initial cost was reduced to 115 million won.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.170.2-170.2
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• 2010

The amount of the heating and cooling energy of water source heat pump using the raw water from the Paldang water intake station is investigated in the study. The Han river water is conveyed in the large-size shallowly buried pipe. Averaged water temperature at the position, 27 km from the Paldang water intake station, is increased by $1.11^{\circ}C$ due to the geothermal energy transfer under the ground, therefore the raw water has more thermal energy than the river water. To estimate of the thermal energy for the raw water, it is assumed that the water source heat pump is used for the heating and cooling ventilation. When $5.0^{\circ}C$ temperature difference energy of the raw water is used in the heat pump system all the year except for the January and February in which $3.0^{\circ}C$ temperature difference energy is used. It is predicted that total 5,766.3 Tcal could be used in the metropolitan area a year, which is about 3.0% of the river water unutilized energy resources.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.3
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• pp.103-109
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• 2016

The purpose of this study is to perform comparative economic evaluation for the systems of ground source heat pump (GSHP) and district heating and cooling (DHC) by focusing on the analysis of operation case of GSHP. The adapted research object is a public office building located in Seoul. The capacity of ground source pump is about 3,900 kW. Ground heat exchanger is closed loop type. The analysis period for life cycle cost is 30 years. Economic evaluation is assessed from the viewpoints of the following four parts: initial cost, energy cost, maintenance and replacement cost, and environment cost. The total life cycle cost of GSHP is approximately 8,447 million won. The cost of the DHC System is approximately 3,793 million won. The cost of the DHC is approximately 46% lower than GSHP system under the condition of current rate for GSHP and DHC.