• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1078_1079
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• 2009

본 논문에서는 태양열 온수급탕에 관한 모티너링 연구를 해석하고 이론을 바탕으로 실 시스템을 적용 운용시 시스템의 운전특성을 비교 분석하였다. 장기 적인 일사량 측정 데이터 수집을 통하여 그래프화, 모티터링 시스템에 관한 연구를 살펴보았다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.859-866
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• 2010

This study examined the economics of a solar water heating system for an office building using life cycle cost (LCC) optimization simulations. The numerical simulations were conducted with TRNSYS and GenOpt employing the Hooke-Jeeves algorithm. The solar collector area, slope, mass flow rate per collector area and storage tank volume were selected as the main design parameters of the solar water heating system. The LCC optimization simulations of the system were carried out for cases where water temperature was $60^{\circ}C$ and $50^{\circ}C$. The results showed that for water temperature at $60^{\circ}C$ and $50^{\circ}C$ the collector area could be decreased by 17% and 28%, storage tank volume could be decreased by 49% and 54%, and mass flow rate per collector area increased by 5% and 9% respectively compared to a non-optimized system. The LCC of the system was reduced by 4% for $60^{\circ}C$ and 7% for $50^{\circ}C$. The initial installation cost of the system was reduced by 24% for $60^{\circ}C$ and 34% for $50^{\circ}C$. However, the operating cost of the system increased by 16% for $60^{\circ}C$ and 36% for $50^{\circ}C$ compared to a traditional solar water heating system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.232-242
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• 2005

It has been recognized that solar water heating systems are economically inferior to conventional gas water-heaters and boilers using light oil as fuel in spite of having practical possibilities among other alternative energy facilities in Korea. The solar system, however, should be revaluated due to the sharp rise of oil prices recently. We have calculated the energy amount and cost through a series of research projects for the system by experiment and simulation, which lead to analyzing reliable life cycle costs. For the economic analysis, the gas water-heater and light oil boiler were taken as base cases while the solar systems implemented with these facilities were compared as alternatives. As a result, the solar system using the light oil as an auxiliary fuel surpassed the light oil boiler in economics. And a $50\%$ government subsidy for the initial cost is needed to maintain competitiveness with the gas hot-water heater. With this support, the simple payback period of the system can approach 12.8 years under $20\%$ additional curtailment of expenditure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.5
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• pp.225-232
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• 2013

Heat pump systems have been widely adopted in buildings for cooling and heating, due to their higher energy efficiency. Recently, the demand for hot water supply from the heat pump system has been increasing. To increase the water supply temperature with higher system efficiency and reliability, a heat pump water heater adopting cascade cycle was investigated in this study. The cascade heat pump water heater consisted of a low-stage cycle using R410A, and a high-stage cycle using R134a. A simulation program for the cascade heat pump water heater was developed, and verified by comparison with experimental data. The performance of the cascade heat pump water heater was optimized, by varying the compressor rotating speeds of the low- and high-stage cycles. At low ambient temperatures, the performance of the cascade cycle was compared with that of the single-stage cycle. The system efficiency of the cascade cycle was higher than that of the single-stage cycle, showing a lower compression ratio and compressor discharge temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.394-399
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• 2008

There are many attempts to use a fuel cell system as a residential power generation system. The purpose of this study is to investigate the optimal design of a water tank for a hot water system when the fuel cell co-generation system is combined with a domestic hot water supply system. The demands of hot water supply per month per home are investigated in Busan for a year. It showed somewhat large differences between the actual demand and the designed demand of hot water, but the actual capacity of hourly averaged hot water demands is analyzed as $60{\ell}/h$ in this study based on the actual demand. The experiments are performed in the various inlet and outlet locations of nozzles, and the hot water consumption rates. The experimental results are showed that the optimal capacity of the water tank is $200{\ell}$ when the thermal efficiency, the storing capacity of hot water and the space for installation are considered.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1088-1094
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• 2003

Case study was peformed to analyze energy load for department stores and develop energy load model to be applied to a cogeneration system. Energy loads of 14 departments were analyzed based on energy load sheets written by operators and energy load of one department store was measured through modem communication for a year. Energy load of department stores shows various variations depending on when they are opened or closed and, hours, days and months. In this paper, the measurement was compared with data in energy load sheets and resolved, and energy load model for a department store was built. It is important to use an accurate energy load model for an accurate feasibility study applying a cogeneration system to buildings.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.6
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• pp.461-470
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• 2003

The purpose of this study is to investigate the performance of a transcritical cycle for hot water heating using $CO_2$ as a working fluid. Some of the main parameters that affect the practical performance of the $CO_2$ system are discussed; the performance on the variation of refrigerant charge, changes in flow conditions of secondary fluids, and that with or without internal heat exchanger, The experimental results show that the optimum charge is approximately the same for various mass flow rates of the secondary fluid at gas cooler. The experimental results on the effect of secondary fluids are in general agreement with the experimental results of transcritical cycle in the open literature and show similar trend for conventional subcritical vapor compression cycles. The heat exchanger effectiveness increases with an increase of the heat exchange area of the internal heat exchanger regardless of the mass flow rate at the gas cooler.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.5
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• pp.404-414
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• 1991

The purpose of this study is to compare the amount of heating, domestic hot water, and cooking fuel consumption with that of heating fuel consumption by the existing calculation method and to provide rational heating system design and energy conservation through presenting the simplified equation which can anticipate the amount of heating, domestic hot water, and cooking and the load mechanical equipments. The affecting factors to the amount of energy consumption are the case of Heating, Domestic Hot Water and Cooking in addition to the energy conservation intention.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1418-1423
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• 2009

This study describes experimental study on the performance characteristics with load condition in hybrid solar heating system during spring season. The room temperatures, the hot water conditions and the lower part temperatures of heat storage tank were changed to analyze the system performances. As a results, the hot water was significantly affected by the ambient temperature. The indoor setting temperature affected the solar fraction. When the low part temperature of the storage tank increased, the temperature of the hot water rose and the temperature of the hot water in morning was affected by the ambient temperature.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1215-1219
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• 2009

In this study, the performance of solar assisted hybrid heat pump system with cloud cover were analyzed by using experimental method in spring season. It was consisted of concentric evacuated tube solar collector, heat medium tank, heat storage tank, heat pump, and so on. As a result, the solar radiation should be maintained over $4.1\;MJ/m^2$ in order to operate solar heating system for heating. Solar heat of collector wasn't affected by ambient temperature, but cloud cover has a big effect to collector efficiency. In addition, the collector efficiency is about 50-60%, and solar fraction is 40% for this system.