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주광조명제어의 건물최대냉방부하 감소효과에 주광조명가능면적비가 미치는 영향에 대한 해석적 연구
김원욱(Wonuk Kim),박홍희(Honghee Park),이주성(Jooseong Lee),김용찬(Yongchan Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
The objective of this paper is to investigate the relation between daylight-induced peak cooling load saving and daylight area ratio in a medium office building. The first step to achieve for this purpose is building energy simulation. We used DOE-2, energy simulation program, to demonstrate the energy performance of several midium sized office building. 56 simulation results were used for the following step. The second is regression analysis. It was used to know the relation between the independent variables which comprises gross area and window-to-wall ratio(WWR) and the dependent variable, daylight area ratio(DAR). Moreover, peak cooling load saving ratio and daylight area ratio are in a logarithmic proportion. Important building features for daylighting schemes are highlighted.
김원욱(Wonuk Kim),박홍희(Honghee Park),김용찬(Yongchan Kim) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.4
Several numerical or analytical models have been proposed to analyze the thermal response of vertical ground heat exchangers (GHEX). However, most models are valid only after several hours of operation since they neglect the heat capacity of the borehole. Recently, the short time response of the GHEX became important in system simulation to improve efficiency. In this paper, a simple new method to evaluate the short time response of the GHEX by using an analogy model of electric circuit transient analysis was presented. The new transient heat exchanger model adopting the concept of thermal capacitance of the borehole as well as the steady-state thermal resistance showed the transient thermal resistance of the borehole. The model was validated by in-situ thermal response test and then compared with the DST model of the TRNSYS program.
김원욱(Wonuk Kim),엄지영(Jiyoung Eum),김용기(Yongki Kim) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
This study compared the heating energy of the apartment reference model with 26 Korean cities. The apartment reference model was developed using the Performance Evaluation of Eco-friendly Homes data of new apartment houses from 2012 to 2015. The heating energy of the reference model were shown by the maximum heating load and heating energy demand, which were calculated based on 26 cities’ standard weather data and the regional thermal insulation performance of building envelope standards. Averagely in the central, southern and Jeju region, heating energy demand of the model using the energy-saving design standards is 31.9, 26.4 and 22.4 kWh/㎡․yr, and heating energy demand of the model using the alternative design standard is 21.7, 16.8 and 13.1 kWh/㎡․yr, respectively. The heating energy of the model with 26 cities shows that the regional thermal insulation performance of building envelope standards has to be enhanced to meet the requirement of the passive house.
물대물 열펌프 부분부하운전 물유량제어에 대한 실험적 연구
김원욱(Wonuk Kim) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
This study shows the performance of water to water heat pump on partial cooling/heating load with various water flow rates. The water to water heat pump was tested in Korea Refrigeration and Air-conditioning Assessment Center by applying KS B 8292 with necessary modifications. The power of water pump is about 10~20 percents of the power of heat pump. The heat pump shows 1.7 times system COP and almost the same net capacity with the water flow rates showing the best system COP compared with constant water flow rates. The water flow control of water to water heat pump are important to make good efficiency on partial load condition.
온실난방을 위한 태양열 지중 계간축열시스템의 최적 운전 방안
김원욱(Wonuk Kim),김용기(Yong-Ki Kim) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.1
태양열은 지구에서 가장 풍부한 재생에너지 중의 하나이지만, 일반적으로 태양열이 풍부한 계절과 열부하가 큰 계절이 서로 달라 사용에 제한이 있다. 유럽과 캐나다에서는 하절기의 풍부한 태양열을 저장하고 그 열을 동절기 난방부하에 활용하여 에너지를 절감하는 태양열 계간축열시스템을 활용하고 있다. 최근 물탱크방식 및 지중축열방식의 태양열 계간축열시스템이 국내에 소개되어 실증연구가 활발히 진행 중이다. 본 연구에서는 연간 2,164 GJ의 난방부하를 가진 경기도 화성시의 유리온실 1개동에 2,000㎡의 평판형 태양열 집열기, 20,000㎥의 지중 계간축열조를 사용하고 단기축열조를 사용하지 않는 보어홀 방식의 태양열 지중 계간축열시스템을 모델링하여, 운전제어조건에 따른 태양열 이용률을 평가하였다. 시간에 따른 태양열 지중 계간축열시스템의 동적성능예측을 위하여 TRNSYS 18 프로그램을 이용하여 시뮬레이션 하였다. 결과적으로 본 연구에서 제안한 태양열 지중 계간축열시스템은 태양열 집열과 지중 계간축열조 방열에 각각 차온 제어 하였을 때, 5년간 평균 약 60%의 태양열 이용률을 나타내었다. 본 연구에서 제안된 시스템은 태양열 지중 계간축열시스템의 구성과 제어방법을 단순화하고 성능을 확보하였다. Solar energy is one of the most abundant renewable energy sources on Earth but there are restrictions on the use of solar thermal energy due to the time-discrepancy between the solar-rich season and heating demand. In Europe and Canada, a seasonal solar thermal energy storage (SSTES), which stores the abundant solar heat in the summer and uses the heat for the winter heating load, is used. Recently, SSTES has been introduced in Korea and empirical studies are actively underway. In this study, a 2,000㎡ flat plate type solar collector and 20,000㎥ of borehole thermal energy storage (BTES) were studied for a greenhouse in Hwaseong City, which has a heating load of 2,164 GJ/year. To predict the dynamic performance of the system over time, it was simulated using the TRNSYS 18 program, and the solar fraction of the system with the control conditions was investigated. As a result, the solar BTES system proposed in this study showed an average solar fraction of approximately 60% for 5 years when differential temperature control was applied to both collecting solar thermal energy and discharging BTES. The proposed system simplified the configuration and control method of the solar BTES system and secured its performance.
실외 시험결과를 이용한 평판형 태양열 집열기의 집열효율 측정
김원욱(Wonuk Kim),김용기(Yong Ki Kim) 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.11
The use of renewable energy is increasing to reduce global warming. Solar energy is the biggest renewable energy source, used in the form of solar thermal and photovoltaic system. Solar thermal system is used as a good alternative to heating systems using fossil fuels, but it has a weakness that solar thermal energy is changing with weather conditions. Therefore, to use solar energy for heating, it is very important not only determining thermal efficiency of solar collector, but also predicting the amount of solar thermal energy. In this study, thermal efficiency of flat-plate solar thermal collectors from three manufacturers was investigated using outdoor steady-state thermal performance test with three water flow rates and various inlet water temperatures in Goyang city of Gyeonggi-do. As a results, the higher water flow rate showed the higher thermal efficiency and the small deviations of collector efficiency between manufacturers are observed.
회로의 과도해석방법을 이용한 수직밀폐형 지중열교환기의 해석 연구
김원욱(Wonuk Kim),박홍희(Honghee Park),전종욱(Jongug Jeon),김용찬(Yongchan Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Most of ground coupled heat pump systems are usually controlled by ON/OFF control of a heat pump with typical cycling frequencies of 1-4 cycles per hour. The start up losses (cycling losses) of heat pumps normally cannot be neglected. The transient behavior of the system in Short time steps might be calculated' properly when we design and analyze a ground coupled heat pump system. It is important that the model of a vertical ground heat exchanger (GHEX) is able to predict the transient behavior correctly. Several numerical or analytical models have been proposed to analyze the thermal response of the vertical GHEX. Most of the models are valid after few hours of operation since they neglect the heat capacity of the borehole. In this paper, we present a simple algorithm to evaluate Short time step responses of the GHEX. This paper focuses primarily on the simplifications and modifications of the dynamic borehole model (TRNSYS Type 451) by using analogy of electric circuit transient analysis.