• 한국지열·수열에너지학회논문집
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• 제9권3호
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• pp.1-10
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• 2013

Open loop geothermal heat pumps have great potential where the groundwater resources are sufficient. Performance of open loop geothermal heat pump systems is considered higher than that of ground source heat pumps. Head and power calculation of submersible pumps, heat pump units, and piping are numerically based on regression data. Results shows that the system performance drops as the water level drops, and the lowest flow rates generally achieve the highest system COPs. The highest achievable cooling system COPs become 6.34, 6.12, and 5.95 as the groundwater levels are 5m, 15m, and 25m. The highest heating system COPs also become 4.59, 4.37, and 4.20. Groundwater level and submersible pump selection greatly influence the system performance of open loop geothermal heat pumps. It needs to be analysed during the design process of open loop geothermal heat pump system, possibly with analysis tools that include wide range of pump product data.

• 한국지열·수열에너지학회논문집
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• 제7권2호
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• pp.1-9
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• 2011

Geothermal heat pumps are known as the most efficient and environment-friendly heating and cooling system, and are also gaining acceptance in buildings. Building energy simulation program, EnergyPlus is used to calculate the energy consumption of residential buildings. This simulated energy consumption is essential for accurate economic analysis. Residential buildings with geothermal heat pumps have complex energy price structure. Electricity rates for residential buildings increase rapidly as the monthly use increases. This complex energy price structure makes the economic analysis complicated. The purpose of this study is to conduct economic comparison of residential geothermal heat pumps and provide a feasible approach in finding their economically feasible capacity.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.294-298
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• 2008

The major threats that human being is facing nowadays are the Climate change, depletion of the fossil fuels at a rapid rate and energy costs. A significant portion of world energy consumption is consumed by domestic heating and cooling. And heat pumps, due to their higher utilization efficiencies as compared to conventional heating and cooling systems, offer an attractive solution to this problem. Among the types of heat pumps, the Geothermal heat pump or Ground-source heat pump is a highly efficient, renewable energy technology for space heating and cooling. The Ground-source heat pump uses the Earth as a heat sink in the summer and a heat source in the winter. And the Earth, having a relatively constant temperature, warmer than the air in winter and cooler than the air in summer, offers an excellent heat source in winter and heat sink in summer.. This paper will discuss an overview of the types of heat pumps, its operation, benefits of using geothermal heat pumps, soil characteristics, and overview of some experimental works. Finally it will briefly discuss the opportunity of using these energy efficient systems (EES) in the HVAC market of South Korea.

• 한국지열·수열에너지학회논문집
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• 제16권4호
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• pp.31-38
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• 2020

The investment in the technology of using a combined heat source is insufficient, which utilizes the advantages of various heat sources to maximize the potential energy and at the same time increases the performance of the heat pump. In this study, as basic data for the development of a high-efficiency hybrid heat pump system that actively connects and uses various heat sources, simulations were conducted for the heat pumps in two cases where geothermal and hydrothermal heat were applied respectively. In May, COP increased by about 27.3% compared to geothermal heat. In February, the COP percentage decrease of hydrothermal heat compared to geothermal heat is -6.9%. In May, total energy consumption can be reduced by 21.1% when hydrothermal is applied compared to geothermal heat. In February, the total energy consumption increases by 3.4%.

• 한국지열·수열에너지학회논문집
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• 제5권2호
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• pp.13-19
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• 2009

This study describes energy and exergy analysis of the Maeeum-Ri Geothermal District Heating System(MGDHS) of Ganghwa Island, Incheon, Korea. Design data are used to assess the performance of the geothermal district heating system. Geothermal resources of MGDHS are found to be low quality with specific exergy index of 0.029. Exergy losses occur in the pumps and heat exchangers as well as in the geothermal Quid and direct discharge. As a result, the total exergy losses accounts for 5.2% in pumps, 47% in the discharge, and 3.3% in heat exchanger based on the total exergy input to the entire MGDHS. The overall energy and exergy efficiencies of the system are found to be 28.8% and 44.5%, respectively.

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.103-109
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• 2014

It is important to control the amount of supply water flow rate at all kinds of HVAC systems in order to maintain IAQ and energy efficiency. The most of buildings installed geothermal heat pumps is using fixed water flow rate in spite of the excellent performance of geothermal heat pumps. Especially when the air-conditioning load is low, the flow rate control may be possible to save energy to operate. However, it is effective to apply the variable flow control system in order to reduce energy consumption. Therefore, the purpose of this study, change a water flow rate and improve the whole performance of the geothermal heat pump. Geothermal heat pump system is modeled after the selection of the applied building, by setting the flow rate control to be analyzed through a simulation of performance evaluation. Building energy saving according to the flow rate of the ground circulating water analyze quantitatively and to investigate the importance of the flow control.

• 한국지열·수열에너지학회논문집
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• 제9권2호
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• pp.1-7
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• 2013

Most researches done on heat pumps have been on heat pumps for refrigeration, cooling and heating. There is therefore the need for more research on hot water heat pumps, especially for high temperature. Even though the cascade heat pump cycle has a great potential more efficient hot water generation even at low evaporating temperatures, it has been researched least for this purpose. In this study, the heating performance of a variable speed cascade heat pump was investigated by varying operating conditions. For the same heating capacity values, it was found that increasing the low stage compressor speed was more suitable for enhancing the performance of the system to get a higher temperature.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권5호
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• pp.23-29
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• 2017

This study was conducted to evaluate performance of geothermal heat exchanger (GHE) in the combined well and open-closed loops geothermal (CWG) systems. The CWG systems were designed to combine open loop geothermal heat pumps and closed loop geothermal heat pumps for high energy efficiency. GHE of the CWG systems could be installed at pumping wells for agricultural usage. To get optimal heat exchange capacity of GHE of the CWG systems, 4 GHEs with various materials and apertures were tested at laboratory scale. Polyethylene (PE) and stainless steel (STS) were selected as GHE materials. The maximum heat exchange capacity of GHEs were estimated to be in the range of 33.0~104 kcal/min. The heat exchange capacity of STS GHEs was 2.4~3.2 times higher than that of PE GHE. The optimal cross section area of GHE and flow rate of circulating water of GHE were estimated to be $2,500mm^2$ and 113 L/min, respectively. For more complicated GHE of the CWG systems, it is necessary to evaluate GHEs at various scales.

• 한국지열·수열에너지학회논문집
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• 제10권3호
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• pp.1-7
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• 2014

Heat pumps have received a fair amount of attention all over the world for their high efficiency and low environmental impact. Employing heat pumps for residential heating and cooling produces only about 2038 kg-$CO_2$/year, an amount which is less than half that of conventional boiler systems. However, the use of single-stage heat pumps becomes uneconomical when they are operated at very low evaporating temperature or high condensing temperature. Two-stage heat pumps systems can be used successfully for low or high temperature applications. In this paper, the experimental study on the performance of two-stage heat pump with an economizer was executed in heating mode. When the secondary fluid inlet temperature to the indoor heat exchanger increased, the COP enhancement rate of two-stage heat pump with an economizer was increased. For all outdoor inlet temperature conditions, the performance of the heat pump with an economizer was higher than it without an economizer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.452-455
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• 2007

The geothermal heat pump system is designed for cooling and heating for three stories building (2,435 $m^2$) includes total 79 heat pumps. Therefore, the monitoring system is installed for each floor and the data is automatically transmitted to the monitoring system. Heat exchange rate and temperature of a geothermal heat pump system have been monitored for a long period. The seasonal operation of geothermal heat pump shows the different shape of heat exchange rate for cooling and heating. Ground water flow can influence on heat exchange rate and thermal storage of the system. In order to define the hydraulic characteristics and groundwater temperature variation, the relationships among air temperatures, groundwater temperatures, water table, and precipitation are analysed.