• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.66-72
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• 2008

In this study, the ground source heat pump was installed at a research center in Jeju Island to verify the performance of the system and to give an information for a economic feasibility. The performance test was conducted until the heat storage tank temperature reached at $5^{\circ}C$ from $50^{\circ}C$ in the cooling operation, and until the storage temperature goes up to $50^{\circ}C$ from $10^{\circ}C$ in the heating mode. As results, the system performance shows that $2.2{\sim}3.5$ for the cooling operation and $2.5{\sim}3.5$ for heating operation. It is found that the underground is good heat source for the heat pump with $3{\sim}10^{\circ}C$ variation range. The ground source heat pump could be connected one of air conditioning system without any problem in system performance. Based on the economic analysis, the initial cost for the ground source heat pump will be compensated after 4 years operation. If the system runs 20 years, approximately 300 million Won will be saved when the air conditioning system adapt the ground source heat pump based on Life Cycle Cost analysis.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.357-362
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• 2008

The present study has been conducted variable refrigerant flow system applied building. Multi air-conditioning system has some benefits : easier building management and maintenance and energy saving. Recently, the system heat pump has been employed in medium-sized and tall buildings. However, the performance data and design method for system heat pump are limited in literature due to complicated system parameters and operating conditions. In the present study, case study of a system heat pump applied various building. The aim of this paper is to application multi air-conditioners and to inform the benefits of multi air-conditioners.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1175-1182
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• 2004

Installations of vertical boreholes for the ground source heat pump system are expensive to install. One way to reduce the initial cost is to increase the specific heat extraction rate of borehole system. However, as the specific heat extraction rate increases the temperature of borehole fluid decreases with the resultant lower Coefficient Of Performance in Heating(COPH) of heat pump system. The purpose of this study is to provide the basic informations about the performance of heat pump system with the specific heat extraction rate and soil thermal properties such as thermal conductivity and temperature. It is shown that the specific heat extraction rate is the most important parameter for the ground source heat pump system. To obtain the reasonable COPH value (COPH > 3) the heat extraction rate should be about 25 W/m or less. Accurate measurements of soil thermal properties are also very important to design the system properly. The effects of borehole thermal resistances are also examined in this study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.4
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• pp.180-186
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• 2013

An electric vehicle is an environment-friendly automobile which does not emit any tailpipe pollutant. In a conventional vehicle with an internal combustion engine, the internal cabin of the vehicle is usually heated using waste heat from the engine. However, for an electric vehicle, an alternative solution for heating is required because it does not have a combustion engine. Recently, a heat pump system which is widely used for residential heating due to its higher efficiency has been studied for its use as a heating system in electric vehicles. In this study, a heat pump system utilizing air source and waste heat source from electric devices was investigated experimentally. The performance of the heat pump system was measured by varying the mass flow rate ratio. The experimental results show that the heating capacity and COP in the dual heat source heat pump were increased by 20.9% and 8.6%, respectively, from those of the air-source heat pump.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.821-827
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• 2010

Study on the performance characteristics of the solar hybrid system with heat pump operating temperature during winter season has performed by using an experimental test. The system performance and operating characteristics with the heat pump operating temperature, hour and load condition were investigated and analyzed. As a result, the hot water temperature was significantly affected by the heat pump operating temperature at the morning(time 1) and noon(time 2). However, hot water temperature was set by the radiation quality and collecting operation hour at the afternoon(time 3). In addition to the solar fraction was decreased for the high heat pump operating temperature because the heat pump operated with a long operating time and short operating period.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.6
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• pp.431-439
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• 2001

Recently, multi-room type heat pump system has aroused much attention, because it can achieve much reduction of installation cost and space as well as energy saving in companion with the single room type heat pump system. In the present study, performance characteristics of a 3 room type inverter driven heat pump system, which is widely spread in Japanese market, are measured.. In the single room operation, performances of a heat pump system such s the difference of compressor outlet and inlet pressures and the mass flowrate may increase with the increase of cooling capacity so that COP of the system decrease with the increase of cooling capacity. However, in the 2 room operation, mass flowrate and COP of the total system increase markedly as compared with the single room operation.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.59-67
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• 2012

In this study,the compact type solar thermal and ground coupled heat pump hybrid system for space heating/cooling and hot water supply has been developed. This hybrid system was installed in Zero Energy Solar House(ZeSH) in KIER for the demonstration. The thermal performance and operational characteristics of this hybrid system were analysed especially. The results are as follows. (1) This hybrid system was designed in order to address the existing disadvantages of solar thermal/ground coupled heat pump system. For this design, all parts except solar collector and ground coupled heat pump were integrated into a single product in a factory. The compact type unit includes two buffer tanks, an expansion tank, pumps, valves, a controller, etc. This system has an advantage of easy installation with simple plumbing work even in narrow space. (2) The thermal charging and discharging time of the buffer tanks and its characteristics by ground coupled heat pump, and heat pump COP according to geo-source temperature and buffer storage temperature have been studied. This system was found to meet well to the heat load without any other auxiliary heating equipment. (3) The operating hours of the ground coupled heat pump as a backup device of solar thermal can be reduced significantly by using solar heat. It was also found that the minimum heating water supply setting temperature and maximum cooling water supply setting temperature make an influence on the heat pump COP. The lower heating water and the higher cooling water temperature, the higher COP. In this respect, the hybrid system's performance can be improved in ZeSH than conventional house.

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.155-162
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• 2001

The greenhouse heating system with heat pump was built for development of simulation model and validation. The computer simulation model for the system to predict temperature of air and soil and moisture content of soil in the greenhouse were developed, and its validity was justified by actual data. From the analysis of experimentally measured data and the simulation output, following results were obtained. 1. The expected values of inside air temperature for the heating system with heat pump were very much close to the experimental values. 2. In the heating system with heat pump, the expected values of day time surface temperature of soil by computer simulation were very much similar to the measured values, but those of night time were higher than the measured value by at most 2.0$\^{C}$. 3. The simulation model predicted temperature of greenhouse film as of 1$\^{C}$ below than the mean value of ambient air and greenhouse air temperature. 4. Heat loss value of daytime was found to be larger than that of nigh as much as 1.3 to 2.3 times for the heating system with heat pump. 5. In the heating system with heat pump, when the lowest ambient temperature was -8$\^{C}$∼-7$\^{C}$ the air temperature of greenhouse was 5$\^{C}$∼6$\^{C}$, thus the heat pump heating system contributed in greenhouse heating by 13$\^{C}$.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.634-637
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• 2008

Ground source heat pumps are clean, energy-efficient and environment-friendly systems cooling and heating. Although the initial cost of ground source heat pump system is higher than that of air source heat pump, it is now widely accepted as an economical system since the installation cost can be returned within an short period of time due to its high efficiency. In the present study, performances of ground source compound hybrid heat pump system applied to a large community building are simulated. The system design and operation process appropriate for the surrounding circumstance guarantee the high benefit of the heat pump system applied to a large community building. If among several renewable energy sources, ground, river, sea, waste water source are chosen as available alternative energies are combined, COP of the system can be increased largely and hybrid heat pump system can reduced the fuel cost.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.538-541
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• 2007

An expansion device plays an important role in optimizing the heat pumps by controlling refrigerant flow and balancing the system pressures. Conventional expansion devices are being gradually replaced with electronic expansion valves due to increasing focus on comfort, energy conservation, and application of a variable speed compressor. In addition, the amount of refrigerant charge in a heat pump is another primary parameter influencing system performance. In this study, the flow characteristics of the expansion devices are analyzed, and the effects of refrigerant charge amount on the performance of the heat pump are investigated at various operating conditions. Cooling capacity of the heat pump system is strongly dependent on load conditions. The heat pump system is very sensitive with a variation of refrigerant charge amount. But, the performance of it can be optimized by adjusting the flow rate through expansion device to maintain a constant superheat at all test conditions.