Yong-Ki Kim

An Analysis of the Energy Saving Effect Through the Retrofit and the Optimal Operation for HVAC Systems

ABSTRACT:The major goal of building energy management is to minimize the energy consum-ption while maintaining the comfortable environment condition. Nowadays building energy mana-gement to save HVAC energy and so on is the most critical issue for existing building service branch with high efficiency equipments and their optimal operation. The effects on the building energy savings of the building equipment retrofit and the improvement of its operation method, especially in the field of HVAC system, were analyzed in this study for domestic small and/or medium sized buildings. Over 8.8% of energy saving was achieved compared withe total energy consumption in commercial building. These results could be used for reasonable maintenance and efficient management of the various building service equipments and related systems.Keywords:Building retrofit(개보수), Optimal control(최적 운전), Energy saving(에너지 절약), Maintenance(유지관리), Air conditioning system(공조시스템) †Corresponding author Tel.: +82-31-910-0587; fax: +82-31-910-0246 E-mail address: twlee@kict.re.kr

Optimization of the Community Energy Supply System for D-Cube City, Multi Purpose Building

D-Cube City is a recently completed multi purpose building consisting of four types of facilities; offices, a department store, a hotel, and congregation spaces. A community energy supply system(CES) has been installed to supply this building with electricity, steam, heat, and cold water. The BEMS, building energy management system, is currently being designed to reduce building energy consumption through the efficient operation of the various pieces of building service equipment. In this study the optimal methods for operating the CES of D-Cube City were considered. This system includes three combined heat and power systems, seven steam boilers, two hot water boilers, two absorption chillers, and four turbo chillers, and various other pieces of equipment. In result, the optimal methods of operating the CES for various energy demand levels were obtained along with the seasonal effects on the economic efficiency of the operation. The effect of the amount of energy demanded by the various facility areas on the total energy consumption was also analyzed.

A Study on the Heating Characteristics of Radiant Floor Panel Using Heat Pipes with the Double Wick

ABSTRACT:Most of the domestic residential buildings have used the traditional radiant heating system, circulating hot water through the cross-linked polyethylene(PE-X) pipe buried in the floor panel of the heating space. New type of the heating panel was recently developed using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal charac-teristics of this heating system at the unit heating space which surrounded by outer space whose temperature of air be maintained scheduled value with time. Through the various experiments with several parameters, such as flow rate, inlet and outlet temperatures of hot water and the heating duration and so on, we found that the floor heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4～31% compared with the conventional panel heating system using PE-X pipe. These results could be used for optimal design and efficient operation of the heating system as well as improvement of thermal comfort.Keywords:Heat pipe(히트파이프), Cross-linked polyethylene(PE-X) pipe(가교화 폴리에틸렌관), Heating characteristic(난방특성), Radiant heating panel(복사난방패널), Thermal comfort(온열 쾌적도)

A Study on the Optimal Design of Urban Energy Supply Systems

Recently many efforts have been carried out on the development of energy-efficient and environment-friendly systems in order to preserve natural environment and to reduce environmental loads in the branch of the urban planning and the building design. In this study, a mathematical method was developed and a numerical analysis was carried out with various parameters to provide substantial data for optimal design and operation of urban energy supply systems. Components of the system and their specifications, such as a co-generation system and other heating and cooling systems, could be obtained through this analysis for various resource and energy requirements in urban area. In this study, the system constituents and operating characteristics, and their economic performances such as the value of objective function, the amount of energy consumption were discussed for various load patterns and power load ratios. Also, it turns out that the optimal energy supply system can save energy by in comparison with the conventional energy supply system.

A Study on Improved Heating Performance of an Apartment Housing Unit

Most hot water heating valves for apartments are constant-flow types, which limit the flow rate through an individual household for even distribution of heating water to other households. The constant-flow type is implemented by an on-off control. As a result, heating water is supplied intermittently and hence, indoor air temperature also fluctuates. Returning water temperature is also high, which reduces energy efficiency. To implement continuous feedback control, the indoor temperature dynamics was simulated to fit a measured temperature history by a state-of-the-art physical model. From the model, it was found that the most important disturbance is outdoor temperature and its effect on indoor temperature lasts about an hour. To cope with the slow response and the significant disturbance, a prediction control with proportional feedback is proposed. The control was found to be successful in implementing continuous heating water flow and improved indoor temperature control.