• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.30-37
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• 2005

Cycle simulation of Ground Source Heat Pump[GSHP] system was carried out to determine the design specification of basic components such as turbo compressor and heat exchangers. Part load operation characteristics of the designed GSHP system was estimated using the compressor and heat exchanger performance data. A 50RT class turbo compressor for GSHP system is now under development, in which R134a refrigerant is adopted as working fluid. The compressor with variable cascade diffusers is designed to work both in cooling and heating modes so that it can actively keep up with the climate change with high efficiency. The normal running speeds of the compressor are 59000rpm for heating mode and 70000rpm for tooling mode respectively. It has two identical impellers at both ends of the rotor so as to minimize aero-induced thrust force effectively. GSHP system was coupled with a vortical type heat exchanger, and heat gain and heat loss from ground were evaluated per a bore hole. For the optimal integration of the heat pump system, its header for circulating fluid was combined with the ground heat exchangers in parallel and series configuration.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2117-2122
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• 2004

The main objective of the present study is to investigate the performance characteristics of a ground source heat pump (GSHP) system with a 130 m vertical 60.5 mm nominal diameter U-bend ground heat exchanger. In order to evaluate the performance analysis, the GSHP system connected to a test room with 90 $m^2$ floor area in the Korea Institute of Construction Technology ($37^{\circ}39'$ N, $126^{\circ}48'$ E) was designed and constructed. This GSHP system mainly consisted of ground heat exchanger, indoor heat pump and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July to January in cooling and heating season of $2003{\sim}2004$. The cooling and heating performance coefficients of the system were determined from the experimental results. The average cooling and heating COPs for the system were obtained to be 4.82 and 3.02, respectively. The temperature variations in ground and the ground heat exchanger surface at different depths were also measured.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.1
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• pp.17-22
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• 2007

The growth of domestic energy demand is rapidly increased for the industrialization and the improvement of the living standards. It is also recognised that the importance of the use of environmentally friendly energy and high efficient equipment. Ground Source heat pumps (GSHP) using earth as heat source or sink are outstanding environmentally friendly energy systems which have high thermal efficiency when compared to conventional heating and cooling system. So government employs a policy and increase investment for expanding renewable energy market volume. Especially is established a system for obligatory usage of renewable energy to achieve 5% renewable energy diffusion rate by 2011. And the market demand for the ground source heat pump is rapidly growing due to its strong advantages. However domestic situation usually have been depended on the import of ground source heat pumps. In this paper, the results of development of a ground source heat pump using refrigerant R410A are reported.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.99-102
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• 2008

The growth of domestic energy demand is rapidly increased for the industrialization and the improvement of the living standards. It is also recognised that the importance of the use of environmentally friendly energy and high efficient equipment. Ground Source heat pumps(GSHP) using earth as heat source or sink are outstanding environmentally friendly energy systems which have high thermal efficiency when compared to conventional heating and cooling system. So government employs a policy and increase investment for expanding renewable energy market volume. Especially is established a system for obligatory usage of renewable energy to achieve 5% renewable energy diffusion rate by 2011. And the market demand for the ground source heat pump is rapidly growing due to its strong advantages. However domestic situation usually have been depended on the import of ground source heat pumps. In this paper, the results of development of a ground source heat pump using refrigerant R410A are reported.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.230-239
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• 2012

Ground-coupled heat pump (GCHP) systems utilize the immense renewable storage capacity of the ground as a heat source or sink to provide space heating, cooling, and domestic hot water. The main objective of the present study is to investigate the cooling and heating performance of a small scale GCHP system with horizontal ground heat exchanger (HGHE). In order to evaluate the performance, a water-to-air ground-source heat pump unit connected to a test room with a net floor area of 18.4 m2 and a volume of 64.4 m3 in the Korea Institute of Construction Technology ($37^{\circ}39'N$, $126^{\circ}48'E$) was designed and constructed. This GCHP system mainly consisted of slinky-type HGHE with a total length of 400 m, indoor heat pump, and measuring devices. The peak cooling and heating loads of the test room were 5.07 kW and 4.12 kW, respectively. The experimental results were obtained from March 15, 2011 to August 31, 2011 and the performance coefficients of the system were determined from the measured data. The overall seasonal performance factor (SPF) for cooling was 3.31 while the system delivered heating at a daily average performance coefficients of 2.82.

• 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.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.58-63
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• 2014

A vertical closed loop ground source heat pump (GSHP) is used to produce heat from the low-grade energy source such as the outside air and ground source. It is known that a heat pump system type has better efficiency comparing to the electric heating system. This study only demonstrates that the vertical closed loop GSHP system is a feasible choice for space cooling of air conditioning. The coefficient of performance (COP) is the ratio of heat output to work supplied to the system in the form of electricity. For the vertical closed loop GSHP system in a cooling mode, the COP is the most commonly used way for judging the efficiency. For the purpose of this experiment, vertical closed loop GSHP system was installed in the laboratory and the experiment was executed. As a result, an average COP of vertical-closed loop GSHP system was 3.62 when the outside average temperature was $33^{\circ}C$.

• 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.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.109-116
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• 2008

Ground temperature restoration characteristics are the crucial factors to evaluate whether a ground source heat pump system can keep long time steady operation. They are mainly dependent on soil thermal properties, layout of pile group, operation/shutoff ratio, cooling/heating load, thermal imbalance ratio and so on. On the one hand, several types of vertical pile foundation heat exchangers are intercompared to determine the most efficient one by performance test and numerical method. On the other hand, according to the layout of pile group of a practical engineering and running conditions of a GSHP system in Shanghai, the temperature distribution during a period of five years is numerically studied. The numerical results are analyzed and are used to provide some guidance for the design of large-scale GSHP system.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.82-87
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• 2007

In the present study, the simulation on the annual performance evaluation of a renewable energy systems with fuel cell driven compound source hybrid heat pump systems is applied to the heating and cooling of large community building. The large community building has the economical advantage to apply heat pump cooling and heating systems the long period operation. If air and ground source hybrid heat pump systems are combined, COP of the system can be increased largely. Fuel cell driven compound source hybrid heat pump system can reduced the fuel cost as well as thermal storage tank sharply.