• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.460-465
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• 2007

유출지하수는 지하공간이 깊고 넓게 분포하는 건물에서 자연적으로 유출되어 배출되는 낮은 심도의 지하수이다. 본 연구에서는 신축된 교회건물에서 유출되는 지하수를 열원으로 밀폐형태와 개방형태의 열교환기를 활용하여 각각 5RT급 히트펌프시스템을 난방모드로 운전한 결과를 정리하였다. 실험은 난방순환수의 온도를 $43{\sim}49$ $^{\cdot}C$ 범위에서 제어하면서 진행하였으며, 시스템 COP에 있어서 밀폐형은 $4.12{\sim}4.75$, 개방형은 $3.42{\sim}3.98$의 범위에서 측정되었다. 이는 기존의 지열히트펌프시스템의 COP와 대동 소이한 우수한 성능이라고 판단된다. 또한 펌프동력을 제외한 히트펌프 자체 난방COP에 있어서 밀폐형은 $4.69{\sim}5.81$, 개방형은 $4.38{\sim}5.43$의 범위에서 나타났다. 유출지하수의 온도가 겨울철에도 약 $12{\sim}14^{\cdot}C$를 유지하므로 히트펌프와 시스템전체의 COP가 매우 우수한 값을 나타내고 있음이 확인되었다.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.544-549
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• 2009

The purpose of this study is to investigate the field Operation Characteristics of a sea water heat source cascade heat pump system and system applicable to Building. Cascade heat pump system is composed R410A compressor, R134a compressor, EEV, cascade heat exchanger, Plate heat exchanger etc. Building area is $890m^2$ and has five floors above ground. R410A is used for a low-stage working fluid while R134a is for a high-stage. The system could runs at dual mode. One is mode of general R410A refrigeration cycle in summer and the other is cascade cycle. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. The filed test results show that the sea water heat source heat pump system exhibits a COP of about 5.5 in cooling mode along with a heating COP of about 4.0 in 1-stage heating mode. Cascade 2-stage heat pump system is enough to supply $60^{\circ}C$ water and heating COP is about 3.0

• Journal of the Korean Solar Energy Society
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• v.36 no.3
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• pp.45-52
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• 2016

Remarkable air temperature increases in urban areas are known as heat island phenomenon. In this study, we analyzed the effects of renewable energy on the heat island phenomenon in urban area by numerical method. The results showed that the use of renewable energy reduces the building energy use in urban area and contributes the alleviation of the Urban Heat Island Effects.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.695-701
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• 1998

Researches on unused energy are being continued because of the limited fossil fuel and the destruction of environment. Therefore this study was peformed as follows. The collectable amount of exhausted heat for an air-conditioning was calculated by the subway thermal environment prediction program. And the electric power needed by conventional heat source equipments was compared with one by unused heat source equipments when the exhausted heat was used by heat pump in heating and hot water supplying. The results are summarized as follows; 1) Forced ventilation should be conducted to keep optimal temperature in subway tunnel in summer as well as in winter. According to the simulation, temperature in tunnel was higher than that on the ground in summer when the forced ventilation was conducted only in winter. 2) Ventilating time should be calculated out to the optimal condition for not only saving power of ventilation fan but reusing exhausted heat. By the simulation, it is certain that the exhausted heat should be eliminated in air-conditioning time. 3) The use of exhausted heat source heat pump could save 8% of electric power per hour in comparison with existing heat pump. It was based on a present heat generation and traffic for ventilating time of general air-conditioning, but could be different by ventilating time. 4) As the traffic increases up to 1.5 or 2 times, electric power consumption of the conventional heat pump increases to 11% or 13.5% per mean hour in comparison with that of the exhausted heat source heat pump, though all-day ventilation.

• Land and Housing Review
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• v.9 no.4
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• pp.25-32
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• 2018

Application of geothermal energy in buildings has been gaining popularity as it provides the benefits of both heating and cooling a building. Among the various types of geothermal energy systems, ground-coupled heat pump system is the most commonly applied one in South Korea. A ground heat exchanger plays an important role as a heat source in winter and a heat sink in summer. For the stable operation of a ground-coupled heat pump system, a ground heat exchanger should be sized so that it provides sufficient heating and cooling energy. Heating and cooling energies generated in ground heat exchangers mainly depend on the temperature difference between the heating medium in ground heat exchangers and the surrounding ground. In addition, the performance of ground heat exchangers influences the change in ground temperature. Therefore, it is necessary to consider this interrelation between the change in the ground temperature and the performance of ground heat exchanger for an accurate estimation of its performance. However, previous thermal analysis models for ground heat exchangers are not competent enough to allow a complete understanding of this interrelation. Therefore, this study proposes a three-dimensional equivalent, transient ground heat exchanger analysis model. First, a previous thermal analysis model for ground heat exchangers, including an analytical model, a g-function, and a numerical model are analyzed. Next, to overcome the limitations of the previous models, a three-dimensional equivalent, transient ground heat exchanger model is proposed. Finally, this study validated the proposed model with the measurement data of the thermal response test, sandbox test, and TRNSYS DST model. All validation results showed a good agreement. These findings helped us to investigate the thermal performance of ground heat exchangers more accurately than the analytical models, and faster than the numerical models. Furthermore, the proposed model contributes to the design of ground heat exchangers by considering the different operation conditions of buildings.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.1
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• pp.7-16
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• 2016

This paper presents the measurement and analysis results for the cooling performance of ground-coupled heat pump (GCHP) system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from May 1 to October 30, 2014. The results showed that the entering source temperature of brine returning from the ground heat exchanger was in a range of design target temperature. Leaving load temperatures to building showed an average value of $11.4^{\circ}C$ for cooling season. From the analysis, the daily performance factor (PF) of geothermal heat pumps ranged from 4.4 to 5.2, while the daily PF of hybrid GCHP system varied from 3.0 to 4.0 over the entire cooling season.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.201.2-201.2
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• 2011

A water-source heat pump system has been developed for cooling and heating of a green house on the waterfront in Jinju. In order to supply a heat source/sink of water in alluvium aquifer to the heat pump system, the riverbank filtration facility (two pumping wells and one recharge well) for water intake and injection has been constructed. To pump and recharge water sufficiently, the geometric design such as depth and diameter for the wells have been completed, and details of the well such as slot size and length of the screen and filter pack size have been designed based on the practical and theoretical design method including D30 technique. For the investigation of the hydrogeological characteristics, step-drawdown test, long-term pumping test, and recovery test have been carried out for two developed pumping wells. Step-drawdown test has been performed on 4 step flowrates of 150, 300, 450, $600m^3$/day for 1 hour, and long-term pumping test on flowrate of $500m^3$/day for 24 hours, and recovery test for 6 hours. Since the underground water filtrated by riverbank is flowing smoothly into the well, the water level goes down slightly for the long-term test. Consequently, the stable pumping flowrate for two pumping well has been predicted at least over $1,647m^3$/day which is larger than the flowrate of $1,000m^3$/day for a 60 RT heat pump system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.196-203
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• 2012

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 a heat sink in summer. The geothermal heat pump system with energy-slab represented very high heating and cooling performance due to the stability of EWT from energy slab. However, the performance of it seemed to be affected by the atmospheric air temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.588-591
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• 2009

Ground source heat pump system; GSHPs is close to most practical use for early stage investment cost and energy efficiency in new renewable energies, and currently considered utilizing to the heat and cooling system of a building. Particularly, the case to utilize 'Standing Column well heat source gathering method' in the open standards process to have the excellent capability of gathering geothermal source is increased. But the research for the optimal design technology and the assessment of a pollution level of the ground to utilize a single well for gathering geothermal is insignificant and the design is insufficient. The heating and cooling system and the equipment to utilize a large size residential development to have over 1000 households have not developed yet. Therefore, our company developed 'geothermal hybrid system' which can construct the heat and cooling system using geothermal energy for a large size residential development of over 1000 households and conducted the evaluation of economic feasibility. Moreover we developed automatic equipment for gathering geothermal source and PLC (Programmable logic controller) to have optimal efficiency and FCU (fan coil unit) considering the floors of large size apartments.

• Journal of the Korean Solar Energy Society
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• v.40 no.2
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• pp.1-10
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• 2020

Korea government published renewable energy obligation policy that public building must be supplied some part of total consumption energy (2019: 27%, 2020: 30%). RETScreen is freely available global energy tool that developed by Canadian National Energy Laboratory to quantify energy saving to compare conventional system. This program can be performed energy modeling, cost analysis, greenhouse gas emission analysis and financial analysis. In this study, GSHP (Ground source heat pump) heating and cooling system were studied for the energy deliverly and ROI (Return On Investment) in an office building. Three cases were studied according to the number of HP (Heat pump) units for the 1,000㎡ office building located in Daejeon. Results indicated that the energy delivery of the case 1 (1 HP unit) covered 57% of the office building heating and cooling energy consumption. The case 2 (2 HP units) covered 87.8% and the case 3 (3 HP units) covered 96.8% of the office building energy consumption. The ROI of the case 1 indicated 7.9 years. While 8.2 years for the case 2 and 9.7 years for the case 3.