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토양 및 지하수 조건이 지열공조시스템의 성능에 미치는 영향에 관한 수치 해석적 연구
남유진(Yujin Nam) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.5
Recently, ground source heat pump (GSHP) systems have been introduced in many modern buildings which use the annually stable characteristic of underground temperature as one of the renewable energy uses. However, all of GSHP systems cannot achieve high level of energy efficiency and energy-saving, because their performance significantly depends on thermal properties of soil, the condition of groundwater, building loads, etc. In this research, the effect of thermal properties of soil on the perfomance of GSHP systems has been estimated by a numerical simulation which is coupled with ground heat and water transfer model, ground heat exchanger model and surface heat balance model. The thermal conductivity of soil, the type of soil and the velocity of groundwater flow were used as the calculation parameter in the simulation. A numerical model with a ground heat exchanger was used in the calculation and, their effect on the system performance was estimated through the sensitivity analysis with the developed simulation tool. In the result of simulation, it founds that the faster groundwater flow and the higher heat conductivity the ground has, the more heat exchange rate the system in the site can achieve.
공기 및 지열 이용 Dual-Source 히트펌프 시스템의 성능실험 및 경제성 분석
남유진(Yujin Nam),채호병(Ho-Byung Chae) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.5
Recently, the use of renewable energy has been increased due to growing concern on the energy-saving at buildings and the reduction of CO2 emission. In the field of architecture, to reduce the energy consumption of heating, cooling and hot water supply, heat pump systems with renewable energy has been developed and used in various applications. However, there have been many of researches on the large-scale commercial heat pump systems, but the research and the field application of a compact heat pump system is rare. Therefore, in order to develop the compact heat pump for the small-scale residential building, this study conducted the performance test and feasibility study for a hybrid heat pump using the heat source of air, solar and ground. In the results of experiments through a trial product, the average COP of cooling mode with ground heat source was 4.75, and it of heating mode was 4.03. Furthermore, the average COP of cooling mode with air heat source was 2.60, and it of heating mode was 2.92. Finally, payback period of the system was calculated as 9.2 years.
지중열 이동 시뮬레이션을 이용한 수평형 지열시스템의 채열성능 예측
남유진(Yujin Nam),채호병(Ho-Byung Chae) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.6
The ground source heat pump (GSHP) system has attracted attention, because of its stability of heat production, and the high efficiency of the system. However, there are few studies on the prediction method of the heat exchange rate for a horizontal GSHP system. In this research, in order to predict the performance of a horizontal GSHP system, coupled simulation with a ground heat transfer model and a heat exchanger circulation model was developed, and calculation of heat exchange rate was conducted by the developed tool. In order to optimally design the horizontal GSHP system, the flow rate of circulation water, and the depth and buried spaces of heat exchangers were considered by the case study. As a result, the temperature of circulation water and the heat exchange rate of the system were calculated in each case.