• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.4 no.2
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• pp.1-7
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• 2008

GSHP(Ground Source Heat Pump) has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the system reliability has been key issues and barriers to insure a better system performance as designed originally in ISO (international standard organization) standard. This paper introduces a systematic method to verify its intended design target so called as ISO performance data based commissioning technology for a water to air GSHP system. The commissioning technology starts from are to the international standard ISO performance data of a GSHP model and to compare its installed operation data and to calibrate and tune to the target optimum operation parameters. Results indicated that cooling capacity could be raised up to 76.6% from 46.6% from this proposed commissioning technology.

• 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.

• Journal of Biosystems Engineering
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• v.21 no.4
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• pp.436-448
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• 1996

An earth tube soil air heat exchange system was designed, installed and operated as a single pass heat exchanger to utilize the geothermal energy as an natural energy source. This study was undertaken to investigate the potential of the heating and cooling, energy gain, heat exchange efficiency and coefficient of performance of the system. The system consisted of 30m in length and 30cm in diameter polyethylene pipes buried 2m deep in soil. Maximum heating and cooling performance were 2.51㎾ and 1.26㎾ at the air mass rate of 21cmm. Energy gain and coefficient of performance were the function of temperature difference between outside air and soil temperature. They were expressed as Q=0.33$ imes$$Delta T_{max}$+0.134(㎾) for energy gain and COP=0.44$ imes$$Delta T_{max}$+0.178 for coefficient of performance with correlation factor of 0.95. The mean of heat exchange efficiencies was 85.6%.

• Solar Energy
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• v.17 no.2
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• pp.3-11
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• 1997

In conventional heat and vent dryer, both sensible and latent heat could not be recovered from the exhaust air, but this problem could be solved by introducing a heat pump to a conventional dryer, having a connection with cooling, dehumidifying and heating of heat pump. In this work, HFC134a as a substitute refrigerant of CFC12 adopted in heat pump and a batch type is also introduced. The variables affected on the system performance are holding temperature of a drying chamber, bypass air ratio, degree of superheat and refrigerant flowrate, etc. The moisture contents were decreased curvilinearly in the range of $86{\sim}75%$ on the wet basis. Under the constant drying temperature, the face velocity plays an important role to the drying performance. The COPs are increased in accordance with the air velocity, on the other hand the SMERs are gradually decreased.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.159-164
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• 2000

In this paper a new type refrigerant liquid subcooling system which adopts ice storage system is proposed. And the cycle characteristicso of a new system was investigated. Since this system subcools a refrigerant in the daytime using the ice storaged by electric power in the night it is high efficiency heat pump system which have the merit of ice storage system and possible to improve the performance of the heat pump. The running to storage the ie was carried out for 10 hours in the night and th evaporating temperature was set on $-5^{\circ}C.$ Subcooling operation stayed as 430^{\circ}C$ subcooling degree and perfomed till the water in the IST(Ice storage tank) was reached $12^{\circ}C$. The experimental result showed that a new system was superior to the existing refrigeration system generally. The total cooling capacity of a new system was about 11% higher than that of the existing refrigeration system. And the COP of a new system was improved by 22% compared to the existing refrigeration system.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.150-157
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• 2008

The main objective of this paper is to investigate the performance characteristics of a $CO_2$ air conditioning system for fuel cell electric vehicles (FCEV). The present air conditioning system for FCEV uses the electrically driven compressor and electrically controlled expansion valve for $CO_2$ as a working fluid. The experimental work has been done with various operating conditions, which are quite matching the actual vehicle's driving conditions such as different compressor speed and high pressure to identify the characteristics of the system. Experimental results show that the cooling capacity and coefficient of performance (COP) were up to 6.3kW and 2.5, respectively. This paper also deals with the development of optimum high pressure control algorithm for the transcritical $CO_2$ cycle to achieve the maximum COP.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.39-46
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• 2005

The present study concerns an experimental study of a R-22 heat pump system consisted of liquid and liquid heat exchangers. The test was performed for various systems of a single-, tandem-, and two stage-cycle at the same environmental conditions of temperature. Various experiments of the heat pump system were peformed to compare the heating capacity and COP, when the outdoor temperature is near $-15^{\circ}C$ and the indoor temperature is $20^{\circ}C.$ As the results of the present study, the system of Tandem(parallel) cycle showed the best heating performance, while the discharge temperature of refrigerant was too high. In case of the system of two stage cycle, the performance characteristics were significantly improved by employing the inter cooler.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.25-30
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• 2012

Ground source heat pumps(GSHPs) are among the most efficient and comfortable heating and cooling technologies currently available, because they use the earth's natural heat to provide heating, cooling, and often, water heating. And Building Integrated Geothermal System(BIGS) is one of GSHPs which install ground heat exchanger(GHE) in energy pile without borehole to save the investment cost. Therefore, the experiment is to evaluate the heating performance of BIGS in Korea. The experimental results indicate that the average heat pump COP and overall system's COP values are approximately 4.4 and 3.0 in one week. This study shows that the BIGS could be used for heating in Korea.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.4
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• pp.14-20
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• 2017

Refrigerant having high global warming potentials will be phased out due to environmental protection issues. R410A has been widely used in geothermal heat pump. However, it has a little high GWP by 2088 value. One of the recommended substitute for R410A refrigerant is R452B which having a GWP by 698 value. In this paper, the heating and cooling performance of the water-to-water geothermal heat pump unit with R452B was experimentally investigated. The performance of the heat pump adopting R452B was also compared with the system applying R410A. The heating and cooling capacity of R452B heat pump system showed a slightly lower values within 2% comparing with R410A system. However, the R452B system's coefficient of performance was enhanced by 5.2% and 13.7% at heating and cooling mode, respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2012-2021
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• 1995

An experimental study was performed for the analysis of dynamic characteristics of refrigeration system by controlling the evaporator superheat. Experimental data have been taken utilizing two different devices, thermostatic expansion valve(T.E.V.) and electronic expansion valve(E.E.V.), for the control of the evaporator superheat. The ranges of parameters, such as superheat, mass flow rate of refrigerant and inlet temperature of evaporator were 5-30.deg. C 90-170 kg/h and 10-25.deg. C, respectively. The data taken from the T.E.v.and E.E.v.were discussed with the control of the superheat, pressure drop, refrigerating capacity, compression work, evaporating temperature, condensing temperature and COP affecting performance characteristics of refrigeration system. In case of the refrigerant flow control with T.E..V., the superheat and pressure drop of the evaporator varied periodically, but the control with E.E.V., the parameters were very stable. In E.E.v.control, refrigerating capacity, compression work and evaporating temperature were decreased with increasing superheat, and the highest COP was obtained in the range of superheat from 5.deg. C to 15.deg. C.