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건물의 침기율 모델링에 따른 지중 열교환기 용량 산정의 불확실성
백승효 한국건축친환경설비학회 2022 한국건축친환경설비학회 논문집 Vol.16 No.1
The length of ground heat exchangers is a key factor in the stable operation of ground-source heat pump systems. Different design variables or parameters such as the thermal properties of the ground and heat pump efficiency are considered in sizing ground heat exchangers. Among these, building heating and cooling loads are one of the most significant. However, a variety of uncertain parameters in the building simulation process makes it difficult to reliably estimate building heating and cooling loads. This study investigated the effects of uncertainty in estimating building heating and cooling loads on the sizing of ground heat exchangers, by considering the impact of changes in infiltration rate on these load and consequently on the size of the heat exchanger. EnergyPlus 9.4 was used to estimate the heating and cooling loads of a mid-rise residential building and GLHEpro 5.0 was used to determine the total length of ground heat exchangers. The results show that an increase in the infiltration rate caused an increase in peak building heating and cooling loads. Consequently, the required length of ground heat exchangers calculated by each zone and model differ. Additionally, sensitivity of the size of ground heat exchangers to changes in infiltration rate varied with different patterns of peak and yearly building loads. Therefore, sensitivity analysis of the major parameters used for estimating building heating and cooling loads is needed to ensure that the sizing of ground heat exchangers is robust.
백승효 한국건축친환경설비학회 2021 한국건축친환경설비학회 논문집 Vol.15 No.2
The application of Solar Hot Water (SHW) systems is essential for implementing zero-energy buildings. Various faults in these systems, however, can cause performance degradation, which has led some HVAC engineers or building facility managers to avoid applying such systems. In particular, detection of sensor faults is more difficult than detection of other types of faults. Accordingly, the present study investigates the effects of sensor faults on the performance of SHW systems. Negative and positive biases are artificially injected into the system, and the performance of fault-free and faulty conditions are compared by TRNSYS 17. The simulation results demonstrate that negative bias causes a decrease in solar heat gain in the system. In addition, it is found that the system is operated more intermittently in a negative bias condition and more continuously in a positive bias condition. This finding can be effectively used to propose fault detection and diagnosis in SHW systems.
백승효,남현민,최문정,오혜원,여명석,김광우 한국퍼실리티매니지먼트학회 2012 한국퍼실리티매니지먼트학회지 Vol.7 No.1
To maximize benefits due to the application of the renewable energy systems, the system should be designed in most energy efficient way. Energy efficient renewable energy systems could be designed by understanding the performance of the renewable energy systems, which can be accomplished by using computer program. The purpose of the proposed research is to develop dynamic simulation program of new & renewable energy systems. This research has the three main tasks. The first task is developing energy production calculation methods of renewable energy systems. The second task is developing simulation program by using Visual Basic 2010. The third task is accomplished by validating the program. To validate the developed program, program output calculated by developed program are compared with the results obtained by detailed simulation programs.
백승효,정창호,이진영,여명석,김광우 한국퍼실리티매니지먼트학회 2012 한국퍼실리티매니지먼트학회지 Vol.7 No.1
In Korean residential buildings, the packaged air-conditioner(PAC) has been widely used as a cooling system. However, the PAC creates a negative effect on the environment since this system uses CFCs(chlorofluorocarbon), also apparently causes a problem of day-time peak of electric power demand in summer. In order to reduce problems caused by the PAC, district cooling system has been suggested. This study aims to determine cooling system which is installed in occupied zone for district cooling in residential buildings. LCC analysis is used to evaluate cooling system. Fan coil unit system and the radiant floor cooling system are selected as an alternative. LCC analysis results show that the radiant floor cooling system is most economical cooling system.
건물의 냉난방 운전을 고려한 3차원 동적 지중 열교환기 열해석 모델
백승효,Baek, Seung Hyo 한국토지주택공사 토지주택연구원 2018 LHI journal of land, housing, and urban affairs Vol.9 No.4
Application of geothermal energy in buildings has been gaining popularity as it provides the benefits of both heating and cooling a building. Among the various types of geothermal energy systems, ground-coupled heat pump system is the most commonly applied one in South Korea. A ground heat exchanger plays an important role as a heat source in winter and a heat sink in summer. For the stable operation of a ground-coupled heat pump system, a ground heat exchanger should be sized so that it provides sufficient heating and cooling energy. Heating and cooling energies generated in ground heat exchangers mainly depend on the temperature difference between the heating medium in ground heat exchangers and the surrounding ground. In addition, the performance of ground heat exchangers influences the change in ground temperature. Therefore, it is necessary to consider this interrelation between the change in the ground temperature and the performance of ground heat exchanger for an accurate estimation of its performance. However, previous thermal analysis models for ground heat exchangers are not competent enough to allow a complete understanding of this interrelation. Therefore, this study proposes a three-dimensional equivalent, transient ground heat exchanger analysis model. First, a previous thermal analysis model for ground heat exchangers, including an analytical model, a g-function, and a numerical model are analyzed. Next, to overcome the limitations of the previous models, a three-dimensional equivalent, transient ground heat exchanger model is proposed. Finally, this study validated the proposed model with the measurement data of the thermal response test, sandbox test, and TRNSYS DST model. All validation results showed a good agreement. These findings helped us to investigate the thermal performance of ground heat exchangers more accurately than the analytical models, and faster than the numerical models. Furthermore, the proposed model contributes to the design of ground heat exchangers by considering the different operation conditions of buildings.
백승효(Baek, Seung Hyo) 한국건축친환경설비학회 2020 건축환경설비 Vol.14 No.2
Ground temperature recovery has a considerable impact on the performance of ground heat exchangers and ground-coupled heat pump systems. Some studies have found that consideration of ground temperature recovery in the design of ground heat exchangers allows for a reduction in the size thereof. Based on this finding, this study first investigates whether previous design methods and thermal analysis models for ground heat exchangers are appropriate for the design considering ground temperature recovery. We find that assumptions regarding heat extraction made in previous design methods make it difficult to consider ground temperature recovery. Simplified thermal analysis models for ground heat exchangers are also required to support the design. For these purposes, this study proposes an equivalent thermal analysis model for ground heat exchangers. This model is validated against measurement data of a sand-box test, and validation results demonstrate good agreement. We expect that the proposed model contributes to proposing design methods considering ground temperature recovery.