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냉각수 급수온도에 따른 직팽식 AHU-수랭식 VRF 민감도 분석
연상훈(Sang Hun Yeon),이제헌(Je Hveon Lee),문진우(Jin Woo Moon),이광호(Kwang Ho Lee) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
Recently, VRF(Variable Refrigerant Flow) system has been attracting attention in commercial buildings due to its energy efficiency and capability to control characteristics and load of each room. VRF heat pump system can be actively controled under part load operation and it is possible to control the flow rate of the refrigerant individually according to the load by connecting a large number of indoor units to a single outdoor unit. This study is to assess a direct expansion (DX) air handling unit (AHU)-water source VRF system through co-simulation between EnergyPlus and Matlab and to perform the sensitivity analysis of cooling energy depending on the entering condenser fluid temperature. As a result, when condenser fluid temperature was elevated from 28 ℃ to 34 ℃, there was a tradeoff between outdoor unit energy reduction and cooling tower energy increase and thus the total cooling energy variation was only around 4%.
연상훈(Sang Hun Yeon),이광호(Kwang Ho Lee) 대한설비공학회 2018 설비공학 논문집 Vol.30 No.6
An underfloor air distribution (UFAD) system is an air conditioning system that enables the maintenance of indoor temperature with a relatively small supply-return air temperature gap and at a low supply air flow rate. UFAD offers a variety of advantages compared to conventional overhead systems, including improvements in comfort, health, work efficiency, indoor air quality, and ventilation efficiency for occupants, and improvements in life cycle cost decrease and lay-out flexibility for building services. In addition, using a UFAD system reduces the floor height because the duct space becomes unnecessary. A key factor for the improved energy performance of the UFAD system is stratification, which refers to the inconsistent vertical temperature distribution from the floor to the ceiling resulting from the buoyant effect of air. Stratification plays a critical role in determining the heat, ventilation, and energy performance of a system. However, based on a domestic literature review, research into the stratification of UFAD is insufficient, reflected by a lack of understanding of stratification and a lack of detailed research related to UFAD. Therefore, this study, by using the EnergyPlus simulation and Phi-Gamma formula, aims to assess variations in stratification according to diffuser condition.
UFAD 급기구의 유효면적 변화에 따른 온도 성층화 및 에너지 성능평가
연상훈(Sang-hun Yeon),손정은(Jeong-Eun Son),이광호(Kwang Ho Lee) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.6
Recently tendency to introduce a UFAD system for environmentally friendly buildings as an alternative to OH systems clearly increased. Also LEED which is a green building certification system developed by the U.S. Green Building Council proposes UFAD to be the system having improved control and efficiency. Room air stratification is a key feature for energy saving in UFAD systems. It is a vertical temperature distribution due to the difference in relative density of the air, which separates occupied space ino lower occupied zone and upper mixed zone in EnergyPlus. The upper mixed zones do not need to be conditioned and thus air stratification has great potentials to reduce HVAC energy in UFAD. This study, by using the Phi-Gamma formula, aims at assessment of the energy performance and temperature stratification according to the size of a design effective area of diffuser. As a result, stratification was improved with an increase in the effective area of diffuser and thus cooling load was reduced during the summer. However, the energy saving effect was insignificant due to the fact that the mixed air temperature is increased despite the reduction of AHU supply air volume.
AHU 고장감지 및 진단을 위한 냉수코일밸브 고착에 따른 열환경 및 에너지 성능 분석
김철호(Kim, Chul Ho),연상훈(Yeon, Sang Hun),이광호(Lee, Kwang Ho) 대한건축학회 2021 대한건축학회 학술발표대회 논문집 Vol.41 No.2
This study simulated chilled water valve stiction (ratio 30, 60%) by EnergyPlus in order to develop a fault detection and diagnosis algorithm for Air Handing Unit (AHU) based on machine learning. The abnormal zone temperature and AHU power consumption generated by the chilled water valve stiction ratio were reviewed. It was determined that the chilled water valve stiction errors reduced the chilled water flow and increased energy consumption through temperature changes at each node point in the HVAC while also creating an unsuitable thermal environment. In the future, we will generate the fault data of various elements of AHU and develop AHU fault detection and diagnosis algorithms through machine learning.
바닥공조 시스템에서 슬래브의 단열재 설치에 따른 바닥공간 온도상승 및 에너지 사용량 변화
권혁주(Hyuk-Ju Kwon),연상훈(Sang-Hun Yeon),유병호(Byeong-Ho Yu),이광호(Kwang Ho Lee) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.6
Generally, the UFAD (Under Floor Air Distribution) system used in office buildings, as compared with the CBAD (Ceiling Based Air Distribution) system, have many advantages such as reduced floor height as well as the improvement of the indoor air quality. Moreover, UFAD has great potentials to possibly save energy by conditioning only occupied zone due to stratification. However, the thermal decay which is defined as the increase of the supply air temperature in the supply plenum can adversely affect the energy performance. Therefore, this study, by installing insulations in the slab to reduce thermal decay and enhance cooling performance, analyzed the potential of the cooling energy performance improvement using the EnergyPlus simulation. As a result, thermal decay was reduced when installing insulation on the slab, but the cooling load of the interior zone increased. Nevertheless, the building was able to slightly reduce the total cooling energy. The results indicate that impact of cooling load change in supply plenum is larger than that in occupied zone.
AHU 토출온도에 따른 일반 공조시스템의 에너지 소비량 및 실내 온열환경 분석
김민지(Min Ji Kim),연상훈(Sang Hun Yeon),이광호(Kwang Ho Lee) 대한설비공학회 2018 설비공학 논문집 Vol.30 No.2
Recently, global warming has been a serious issue on the worldwide, and the importance of energy conservation is increasing. In most buildings, energy consumption increases due to cooling, heating, and ventilation. Because of these issues, researches have been carried out to reduce building energy. However, in most conventional forced-air system, the guidelines for the Air Handling Unit (AHU) discharge air temperature are not fully established. The purpose of this study is to assess the impact of AHU discharge air temperature, which is one of the important control variables, on the overall energy consumption and thermal comfort characteristics by modeling conventional forced-air system using EnergyPlus. In addition, recommendations for energy reduction in conventional AHU is provided.
기상 데이터를 활용한 LSTM 기반 일사량 예측모델 개발
박지원(Jiwon Park),홍성협(Sung Hyup Hong),전호성(Ho Seong Jeon),연상훈(Sang Hun Yeon),이광호(Kwang Ho Lee) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
To stably operate EMS(Energy Management System) that systematically manages energy in the building, there is a need for predicting energy consumption and production in advance. In this study, we used hourly observed meteorological data from January, 2018 to December, 2020 provided by the Seoul branch of the Korea Meteorological Administration. The solar altitude data are calculated through the solar angle calculator provided by One Energy. The collected data are converted into available data set by data processing strategy. The correlation analysis between each meteorological data type and solar radiation after one hour proceeded to select the input parameters on the developed model. Selected meteorological data sets are used in the learning stage of the developed LSTM structure prediction model. The predictive performance of each model were analyzed through MAE(Mean Average Error), NMBE(Normalized Mean Bias Error), CV(RMSE)(Coefficient of Variation of Root Mean Square Error), R²(Coefficient of Determination) and computational time. The model with a window size of 24 was selected by performance evaluation criteria. Valid predictive performance of solar radiation after one hour in Busan was derived also from the selected model.