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지열 시스템의 도입이 지중온도환경에 미치는 영향에 대한 해석적 검토
남유진(Yujin Nam) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.8
Ground heat pump systems utilize the annually stable underground temperature to supply heat for space heating and cooling. The underground temperature affects not only the underground ecosystem, but also the performance of these systems. However, in spite of the widespread use of these systems, there have been few researches on the effect of the systems on underground temperature. In this research, case studies with numerical simulation have been conducted, in order to estimate the effect of ground heat pump systems on underground temperature. The simulation was coupled with the ground water-ground heat transfer model and the ground surface heat transfer model. In the result, it was found that the underground change depends on the heat transfer from the ground surface, the heat exchange rate, and the heat conductivity of soil.
지반,지하수 조건을 고려한 지하수 이용 공조 시스템의 이용 수법에 관한 연구
남유진 ( Yu Jin Nam ),( Ryozo Ooka ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.4
Groundwater heat pump (GWHP) system has been expected to achieve the higher coefficient of performance (COP) and more energy-saving than the conventional air-source heat pump (ASHP) system. Its performance significantly depends on the characteristics of groundwater and the underground thermal properties. Furthermore, there is a large difference of COP in utilizing groundwater between as a heat resource and as a thermal storage medium. For properties of groundwater there is suitable utilizing system. However, many of GWHP systems have not been considered sufficiently such properties. This research describes optimization of G WHP system according to the properties of groundwater based on 3D numerical heat and water transport simulation.
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.
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.
태양열 및 지중열원을 이용한 히트펌프 시스템의 최적이용법에 관한 연구
남유진(Yujin Nam) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.6
In this research, a heat pump system with a heat source network is suggested which utilizes solar heat and ground heat as heat source for cooling and heating. This paper describes the summary of the suggested system and the results of the annual energy simulation. The heating and cooling loads, the electric consumption and the COP were calculated by TRNSYS 16 and evaluated in the cases of different local conditions and different system compositions. In the results, the superiority of the suggested system has been quantitatively evaluated comparing with the conventional heat pump system using one heat source. Furthermore, it was more significant in cold climate, in which the heating COP was 146% increased compared the air source heat pump system, than it in subtropical climate, 119% increased.
CFD 해석을 통한 하이브리드 공조시스템의 인체 온열감의 불균일성에 관한 연구
남유진(Yujin Nam),성민기(Minki Sung),송두삼(Doosam Song) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.3
Recently, hybrid air-conditioning system has been proposed and applied to achieve building energy saving. One example is a system combining radiation panel with natural windinduced cross-ventilation. However, few research works have been conducted on the non-uniformity of thermal comfort in such hybrid air-conditioning system. In this paper, both thermal environment and non-uniform thermal comfort of human thermal model under various air-conditioning system, including hybrid system, were evaluated in a typical office room using coupled simulation of computation fluid dynamics, radiation model and a human thermal model. The non-uniformity of thermal comfort was evaluated from the deviation of surface temperature of human thermal model. Flow fields and temperature distribution in each case were represented.