• 지질공학
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• 제28권3호
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• pp.475-488
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• 2018

본 연구에서는 지하수 관정을 활용하고 밀폐형-개방형이 결합된 복합지열시스템(CWG 시스템)을 시설재배지에 적용하여 열원측 및 부하측의 열교환량과 투입된 전력량 대비 효율을 평가하였다. 또한, 운전 과정에서의 외기온도 및 시설재배지 온도를 평가하여 복합지열시스템 적용시의 냉난방 효과를 분석하였다. 냉방운전시 열원측 열교환량 평가결과, 약 235 L/min의 지하수가 유입되는 개방형에서 평균 90.0 kW/h, 약 85 L/min의 순환수가 유동하는 밀폐형에서 40.1 kW/h의 열교환량이 발생하였으며, 전체 열교환량은평균 130.1 kW/h로 분석되었다. 부하측에서 실질적으로 전달되는 열교환량은 평균 110.4kW/h로 평가되었다. 복합지열시스템의 냉방효율을 분석한 결과, 평균 EER는 5.63으로 분석되었다. 난방운전 시 열원측 열교환량 평가결과, 약 266 L/min의 지하수가 유입되는 개방형에서 평균 60.4 kW/h, 약 86 L/min의 순환수가 유동하는 밀폐형에서 22.4 kW/h의 열교환량이 발생하였으며, 전체 열교환량은 평균 82.9 kW/h로 분석되었다. 부하측에서 실질적으로 전달되는 열교환량은 평균 112.0 kW/h로 평가되었다. 복합지열시스템의 난방효율을 분석한 결과, 평균 COP는 3.92로 분석되었다. 외기온도와 CWG 시스템을 적용한 시설하우스 및 비교 시설하우스 내부온도와의 상관관계를 분석한 결과 30RT 용량의 CWG 시스템 하우스가 비교 하우스에 비해 외기온도 $20^{\circ}C$인 경우 $3.4^{\circ}C$, 외기온도 $25^{\circ}C$인 경우 $6.8^{\circ}C$, 외기온도 $30^{\circ}C$인 경우 $10.1^{\circ}C$, 외기온도 $35^{\circ}C$인 경우 $13.4^{\circ}C$의 온도가 저감되는 것으로 평가되었다. 이러한 결과를 볼 때, 본 시스템을 적용할 경우 일반적으로 외기온도가 $30^{\circ}C$ 이상을 보이는 여름철에 CWG 시스템을 적용하지 않은 시설재배지에 비해 약 $10^{\circ}C$ 이상의 냉방효과가 나타낼 수 있을 것으로 판단된다. 이와 같은 결과는 시설재배지의 복합지열시스템 설계에 활용될 수 있고, 다양한 조건에서의 시험성과와 종합하여 복합지열시스템의 냉난방 효과에 대한 보다 명확한 규명이 가능할 것으로 판단된다.

• 한국지열·수열에너지학회논문집
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• 제12권2호
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• pp.7-12
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• 2016

This study have an objective to suggest basic data and measured result of heating performance on water-water type horizontal geothermal heat pump which is based on heating and cooling load calculation result of small residential house. The average temperature during measured periods is $9.4^{\circ}C$ on primary EWT and is $7.6^{\circ}C$ on primary LWT. The temperature difference shows $1.8^{\circ}C$ as average temperature. Because the average outdoor temperature of peak is lager than on December and than on January, the temperature difference between EWT and LWT is bigger that on January than that on December. The system COP is 3.62.

• KIEAE Journal
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• 제12권4호
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• pp.89-95
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• 2012

At present, many countries are trying to reduce green gas emissions to mitigate the effects of these gases on climate change. Year after year, there have been efforts to cut energy use for heating and cooling. Heating and cooling systems, common in all forms of housing, are increasing due to the constant supply of new housing resulting from improvements in economic growth and the quality of life. Thus, studies related to the design of cooling and heating systems to improve energy efficiency are expanding. Among the new designs, radiant floor cooling and heating systems which use capillary tubes are becoming viable means of reducing energy use. Radiant floor cooling and heating systems which use capillary tubes are creative and sustainable systems in which cool and hot water is circulated into capillary tube which has small diameter. In this study, the cooling and heating performance of this type of capillary tube system is investigated in an experimental study and a simulation using TRNSYS. The results of the experimental study show that under a peak load, a capillary tube radiant floor cooling system using geothermal energy can achieve desired indoor temperature without an additional heat source. The set room air temperature is maintained while the floor surface temperature, PMV and PPD remain within the comfort range. Also, this system is more economic than a packaged air conditioner system due to its higher COP. The results of the simulation show that the capillary tube radiant floor heating system maintains set temperature more stable than a PB pipe radiant floor heating system due to its lower supply temperature of hot water. In terms of energy consumption, the capillary tube radiant floor heating system is more efficient than the PB pipe radiant floor heating system.

• 설비공학논문집
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• 제21권8호
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• pp.468-474
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• 2009

Ground water source heat pump system is the oldest one of the ground source heat pump systems. Despite of this, little formal design information has been available until recently. The important design parameters for open system are the identification of optimum ground water flow, heat exchanger selection and well pump. In this study, the capacity of 50 RT system of two well type ground water heat pump system was used. As a result, static water level was -7 m and the level during the heating operation was -32 m, cooling operation was -40 m. The initial static water level recovered within 48 hrs. The temperature of ground water is $15.6^{\circ}C$ for heating season and $16.2^{\circ}C$ for cooling season and does not depend on the outdoor temperature. Operation efficiency of the system shows that, COP 3.1 for heating and COP 4.2 for cooling.

• 설비공학논문집
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• 제29권3호
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• pp.119-126
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• 2017

Recently, ground source heat pump systems are being used in buildings for cooling and heating to reduce greenhouse gas and save energy. However, ground source heat pump systems mainly use the vertical closed-loop geothermal system design rather than the open-loop geothermal system design. This is due to a lack of knowledge and few research feasibility studies. In this research, a dynamic thermal analysis numerical simulation based on a standard house model was conducted for an open-loop geothermal system. Based on heating load analysis results, the life cycle costs of a standard house using an open two-well geothermal system were analyzed and compared with a vertical closed-loop geothermal system, and a diesel boiler. As a result, it was found that using an open two-well geothermal system shows economic return on investment after three years.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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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

• 한국주거학회논문집
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• 제19권5호
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• pp.11-18
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• 2008

Geothermal heat pump system using sanding column well type with their ground heat exchanger can be used as a highly efficient source of heating and cooling in massive buildings. But there is no case of a small scale residential house. So in the residential house this study estimated heating coefficient of performance (COP) of geothermal heat pump system using sanding column well type which is excellent in heat recovery. As a result of analysis, The COP of heat pump is over average 6 and is excellent. And in consequence of making a comparative study according to the bleeding, the COP is higher in the case of bleeding. Therefore, bleeding affects the performance of the system. This study has shown performance result that stands on actual data. Therefore, this study provides ground data that needs when a low capacity of system designs for a residence with confidence elevation.

• 한국지열·수열에너지학회논문집
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• 제13권2호
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• pp.22-29
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• 2017

This study is performed to performance of the combined system the GSHP (Ground Source Heat Pump) system with the Earth tube system using EnergyPlus program. The Earth tube system using fan is characteristics as supply lower (higher) air temperature than outdoor air temperature in cooling and heating seasons, the GSHP system is characteristics as small indoor air temperature variation range. As the results of Earth tube + GSHP system simulation, GSHP power can be reduced than the GSHP single operation as 17.3% in cooling seasons and 32.5% in heating seasons, the GSHP design capacity can be replaced more small size.

• 설비공학논문집
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• 제25권3호
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• pp.156-163
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• 2013

Ground Source Heat Pump (GSHP) systems utilize geothermal energy as a thermal source or sink, for heating, cooling and domestic hot water. It is well known that GSHP is environmentally friendly, and saves energy dramatically. For this reason, many investigative researches have been conducted on commercial and governmental buildings. However, studies on residential GSHP are few, because of the small capacity and cost. In this study, we experimented with the characteristic performance of heating, cooling and seasonal performance factor for a residential GSHP system, which consisted of two 180 m deep u-tube ground heat exchangers, a heat pump and measurement instruments. The installed capacity of the heat pump was 5RT, and the conditioning area was $62.23m^2$. From the experimental results, the cooling COP of the heat pump was 4.13, and the system COP was 3.51, while the CSPF was 3.32. On the other hand, the heating COP of the heat pump was 3.87, and the system COP was 3.39, while the HSPF was 3.39. Also, in-situ cooling COP and capacity were 93.7% and 96.4% compared with the EWT certification data, respectively, and that of heating were 98.3% and 95.7%, respectively.

• 한국지역사회생활과학회지
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• 제27권2호
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• pp.281-294
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• 2016

This study was conducted to promote consumer interest in Geothermal Heat Pump (Ground Source Heat Pump, GSHP) and district heating and cooling (District Heating & Cooling, DHC) systems, which are competing with each other in the heating and cooling field. Considering not only the required cost data of energy itself, but also external influence factors, the optimal mix ratio of these two energy systems was studied as follows. The quantitative data of the two energy systems was entered into a database and the non-quantitative factors of external influence were applied in the form of coefficients. Considering both of these factors, the optimal mix ratio of GSHP and DHC systems and minimum Life Cycle Cost (LCC) were obtained using an algorithm model design. The Optimal Energy Mix of GSHP & DHC (OEMGD) algorithm was developed using a software program (Octave 4.0). The numerical result was able to reflect the variety of external influence factors through the OEMGD algorithm. The OEMGD model found that the DHC system is more economical than the GSHP system and was able to represent the optimal energy mix ratio and LCC of mixed energy systems according to changes in the external influences. The OEMGD algorithm could be of help to improve the consumers' experience and rationalize their energy usage.