• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.2
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• pp.7-11
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• 2015

Recently, as the demand for sustainable energy sources is increasing, ground-source heat pump (GSHP) systems are receiving growing attention. However, the initial cost of GSHP system is higher than it of the conventional systems, especially, in small-size buildings. Therefore, for the application to the small-size building, it is necessary to develop small-size ground heat exchanger with small-size buildings. In this study, analysis of unit-type heat exchanger due to grouting materials. As a result, 1492.14 W of heat exchange rate was acquired in the condition of cement-silica sand-graphite materials.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.138-145
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• 2012

Because of the climate changes and the development of building technologies, the cooling loads have been increased. Among the various renewable energies, geothermal energy is known as very useful and stable energy for heating and cooling of building. This study proposes a road snow-melting system of which heat is supplied from GSHP(Ground source heat pump) in viewpoint of the initial investment and annual running performance, which is also operating as a main facility of heating and cooling for common spaces. The results of this study is as followings. From the site measurement, it is found out that the road surface temperature above the geothermal heating pipe rose up to $5^{\circ}C$, which is the design temperature of road snow-melting, after 2 hours' operation and average COP(Coefficient of performance) was estimated as 3.5. The reliability of CFD has confirmed, because the temperature difference between results of CFD analysis and site measurement is only ${\pm}0.4^{\circ}C$ and the trend of temperature variation is quite similar. CFD analysis on the effect of pavement materials clearly show that more than 2 hours is needed for snow-melting, if the road is paved by ascon or concrete. But the road paved by brick is not reached to $5^{\circ}C$ at all. To evaluate the feasibility of snow-melting system operated by a geothermal circulation which has not GSHP, the surface temperature of concrete-paved road rise up to $0^{\circ}C$ after 2 hour and 40 minutes, and it does never increase to $5^{\circ}C$. And the roads paved by ascon and brick is maintained as below $0^{\circ}C$ after 12 hours geothermal circulation.

• Journal of Energy Engineering
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• v.15 no.3 s.47
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• pp.160-165
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• 2006

Ground source heat pump (GSHP) or geothermal heat pump systems (GHPs) are recognized to be outstanding heating and cooling systems. Most of GSHP systems installed and studied in korea are vertical GSHP systems. A horizontal GSHP system was installed in greenhouse and investigated for the performance characteristics. The results of the study showed that the heating coefficient of performance of the heat pump was 3.64 and the overall heating coefficient of performance of the system was 3.31. The pumping power was obtained as 28.0 W/kW and the required ground heat exchanger length was 53.3 m/kW of rejection heat of condenser. The heat extraction rate was, on average, 14.58 W/m of ground heat exchanger length and trench length is 27.7 m/kW of rejection heat of condenser.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.200.2-200.2
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• 2011

This study was carried out in order to estimate the greenhouse performance for Ground filtration water source heat pump which was installed for supplying the heat to the paprika greenhouse in Jinju city. Experimental area of Greenhouse was $3,300m^2$, For keeping the heat from greenhouse, single plastic covering and double thermal screen was installed. With considering all of greenhouse insulation condition and designed heatng temperature, heating capacity for experimental greenhouse was calculated as 320,000kcal/hr. Coefficient of performance(COP) of Ground filtration water source heat pump was gauged and greenhouse heating performance was tested from Febuary 1 to Febuary 28 in 2011. The result showed that COP of heat pump was in the range of 3.7~4.7 and COP of heating system was in the range of 3.0~3.5. The vaule of COP was very high and the temperature inside greenhouse was well corresponded to the setting temperature of greenhouse environment controlling system. lots of Ground filtration water made the the number of well fewer and the expense for installing heating system cheaper than that of geothermal system used custmarily. and this system went beyond the limitation of intaking amount of groundwater in normal Groundwater source heat pump.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.364-369
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• 2005

An experimental study was conducted on the thermal conductivity of various grouting materials for geothermal heat exchanger which is used as a heat sink or source in the heat pump system. The grouting of the vertical heat exchanger is important for environmental and heat transfer reasons and is generally accomplished by the placement of a low permeability material into the annular space between the borehole wall and the pipes suspended in the borehole. In this study, a lab scale test apparatus was made and measured the thermal conductivity of four grouting materials. As a result, the temperature rising tendency was similar among them, but the increasing rate was different. Thus the thermal conductivity showed a maximum difference of $27\%$ among grouting materials.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.439-444
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• 2002

Geothermal or ground source heat pumps(GSHPs) are electrically powered systems that take advantage of the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and commercial buildings. The buried pipe, or ground loop, is the most recent technical advance in heat pump technology. The idea to bury pipe in the ground to gather heat energy began in the 1940s. Only recently, however, have new heat pump designs and improved buried pipe materials been combined to make GHP systems the most efficient heating and cooling systems available. The aim of the study is application of the GSHP system in korea. Our environments for economy, politics and society are different from other countries. For a case, the progressive tax rate of home electricity is represented.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.148-154
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• 2005

Ground-source (Geothermal) heat pump (GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump (ASHP) systems. However, GSHP systems are not widespread in Japan because of their expensive boring costs. The authors have developed a GSHP system that employs the cast-in-place concrete pile foundations of a building as heat exchangers in order to reduce the initial boring cost. In this system, eight U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes and heat pump performance were investigated in a foil-scale experiment. As a result, the average values for heat rejection were 186${\sim}$201 W/m (for pile, 25 W/m per Pair of tubes) while cooling. The average COP of this system was 4.6 while cooling; rendering this system more effective in energy saving terms than the typical ASHP systems. The initial cost of construction per unit for heat extraction and rejection is ${\yen}$72/W for this system, whereas it is f300/W for existing standard borehole systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.9
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• pp.641-647
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• 2010

Ground-source(Geothermal) heat pump(GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump(ASHP) systems. However, GSHP systems are not widespread because of their expensive installation costs. The authors have developed a GSHP system that employs the cast-in-place concrete pile foundations of a building as heat exchangers in order to reduce the initial cost. In this system, eight U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes and heat pump performance were investigated in a full-scale experiment. As a result, the average values for heat rejection were 186~201 W/m(per pile, 25 W/m per pair of tubes) while cooling. The average COP of this system was 4.6 while cooling; rendering this system more effective in energy saving terms than the typical ASHP systems.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.4
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• pp.9-14
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• 2013

A ground loop heat exchanger for the ground source heat pump system is the important equipment determining the thermal performance and initial cost of the system. The length and performance of the underground heat exchanger is dependent on ground thermal conductivity, operation hours, ground loop diameter, grout, ground loop arrangement, pipe placement and design temperature. In this study we find out heat exchanger length with various design factor.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.2
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• pp.10-15
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• 2011

A ground loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system The length and performance of the heat exchanger is dependent on the ground thermal conductivity, the operation hours, the ground loop diameter, the grout, the ground loop arrangement, the pipe placement and the design temperature. The result of this simulation shows that higher thermal conductivity of grouting materials leads to the decrease length of geothermal heat exchanger from 100.0 to 84.4%.