• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.2
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• pp.9-15
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• 2012

The objective of this study is to investigate the influence on the heating performance for a water-to-water 10RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The heating capacity and COP of the heat pump increased with increasing ground heat source temperature. As a result, compared to a refrigerant switching method, the water switching method with counter flow improves the heating capacity and COP by approximately 5% in average, respectively.

• 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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.8
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• pp.605-611
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• 2012

The objective of this study is to investigate the influence of the cooling performance for a water-to-water 10 RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The cooling capacity and refrigerant mass flow rate of the heat pump increased with increasing ground heat source temperature. But COP of the heat pump decreased with increasing ground heat source temperature. As a result, the water switching method with counter flow, compared to a refrigerant switching method, improves the cooling capacity and COP by approximately 6~9% in average, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.9-14
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• 2006

Open loop or ground water heat pump systems are the oldest of ground-source systems. Standing column wells can be used as highly efficient ground heat exchanger in geo-thermal heat pump systems, where hydrological and geological conditions are suitable. These systems require some careful considerations for well design, ground water flow, heat exchanger selection etc This paper describes 9round water temperature variations, performances in heat ins and cool ing mode and the results of ground water analysis.

• KIEAE Journal
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• v.15 no.3
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• pp.57-63
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• 2015

Purpose: Ground source heat pump system has been attracted in the horticulture industry for the reduction of energy costs and the increasing of farm income. Even though it has higher initial costs, if it uses in combination with heat storage, it is able to reduce the initial costs and operate efficiently. In order to have significant effect of heat storage type ground source heat pump system, it is required to design the capacity considering various conditions such as energy load pattern and operating schedule. Method: In this study, we have designed heat storage type ground source heat pump system in 5 cases by the operating schedule, and examined the system to find the most economic and having superb performance regarding the system COP(Coefficient of Performance) and energy consumption, using dynamic energy simulation, TRNSYS 17. Result: Conventional ground source heat pump system has lower energy consumption than heat storage type, but following the result of LCC(Life Cycle Cost) analysis, the heat storage type was more economic due to the initial costs. In addition, it has the most efficient performance and energy costs in the case of the smallest heat storage time.

• KIEAE Journal
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• v.14 no.4
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• pp.127-131
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• 2014

The ground source heat pump (GSHP) system is a kind of the temperature differential energy system using relatively stable underground temperature as heat source of space heating and cooling. This system can achieve higher performance of system than it of conventional air source heat pump systems. However, its superiority of the system performance is different according to installation location or local climate, because the system performance depends on the underground condition which is decided by annual average air temperature. In this study, in order to estimate the feasibility of the ground source heat pump system according to the local climate, numerical simulation was conducted using the ground heat transfer model and the surface heat balance model. The case study was conducted in the condition of Seoul, Daejeon, and Busan, In the result, the heat exchange rate of Busan was 34.33 W/m as the largest in heating season and it of Seoul was 40.61 W/m as the largest in cooling.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.4
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• pp.22-32
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• 2022

To reduce energy consumption and CO₂ emission in building sector, a ground source heat pump system has been highly adopted due to its high efficient by many regulation. A certification system has been operated to distribute reliable and high-efficient heat pump units. In this study, the performance status of the recently certified ground source heat pump unit with components was investigated. All heat pump units certified from 2015 to 2020 were water to water heat pump types. Compared to the past, higher capacity systems over 400 kW have been certificed. The cooling COP of the heat pump unit based on certification criteria showed higher value than the heating COP. It is highly recommended to revise the certified criteria values considering operating conditions individually. Most of ground source heat pump units have employed scroll type compressors and plate type heat exchangers with HFC refrigerant.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.4
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• pp.59-67
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• 2021

In this study, the performance of the single heat source system and the hybrid system was comparatively analyzed. Case 1 is a ground heat source system, and Case 2 is a water heat source system. Case 3, a hybrid system, reduced the capacity of the ground heat source and applied a water heat source as an auxiliary heat source, and Case 4 was composed of a system that applied a water heat source as an auxiliary heat source to the ground heat source system. As a result of the simulation, in case 3, energy consumption was reduced by up to 2.67% compared to ground sources for cooling. In Case 4, COP was improved by up to 10.02% compared to ground sources during cooling, and EST was calculated to be 2.42℃ lower. During heating, 0.83% was improved compared to the water heat source. At this time, the EST was calculated to be 2.25℃ higher than the water heat source.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.3
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• pp.8-16
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• 2020

This paper presents the heating performance analysis results of a ground-source heat pump (GSHP) system using hybrid ground heat exchanger (HGHE). In this paper, the HGHE refers to the ground heat exchanger (GHE) using both a surface water heat exchanger (SWHE) and a vertical GHE. In order to evaluate the system performance, we installed monitoring sensors for measuring temperatures and power consumption, and then measured operation data with 4 different load burdened ratios of the HGHE. During the entire measurement period, the average heating capacity of the heat pump was 37.3 kW. In addition, the compressor of the heat pump consumed 9.4 kW of power, while the circulating pump of the HGHE used 6.7 kW of power. Therefore, the average heating coefficient of performance (COP) for the heat pump unit was 4.0, while the system including the circulating pump was 2.7. Finally, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further researches are needed to optimize the design data for various load ratios of the HGHE.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.11-19
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• 2021

In this study, combined heat source heat pump system was implemented with 4 single heat source heat pumps each applied with a geothermal source and a water source. Five cases (Case1~Case5) were configured to conduct a performance comparison and analysis of the combined heat source heat pump system. First of all, as a result of analyzing the heat source, the case when 4 ground heat sources were applied (Case1) showed a uniform EST(Entering Source Temperature) distribution throughout the year since it is less affected by outside air compared to the case when 4 water heat sources were applied (Case5). In both winter and summer, the ground heat source maintained higher EST than the water heat source. Therefore, the system with high ratio of geothermal sources is advantageous for heating, and with high ratio of water heat sources is advantageous for cooling.