• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.579-589
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• 1985

The storage tank of the natural-circulation-solar-hot-water system equipped with flat-plate solar collectors is located at higher elevation than the solar collectors. Therefore, the heat loss from the system due to a reversed flow during the night-time is an important factor as well as the day-time thermal performance of the system. The thermal performance of the natural-circulation-solar-hot-water system with flat-plate solar collectors during the day-time depends mainly on the heat collecting efficiency of the solar collectors, whereas its thermal performance during the night-time depends on the system configuration , such as the elevation of the water storage tank with respect to the solar collectors and the piping connections between the storage tank and the solar collectors, as well as thermo-physical properties of the circulating fluid. In the present work, a computer program has been developed to simulate a typical natural-circulation-solar-hot-water-system, and a series of simulation tests have been carried out with the computer program to examine the thermal performance of the system during the day-time as well as the hight-time. In addition , a series of experiment have been conducted under a real sun condition using a natural-circulation-solar-hot-water-system constructed and installed at the KAIST building to compare with the results obtained from computer simulations.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.167-173
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• 2007

This study analyzed by simulation using TRNSYS as well as by experiment on the solar district heating system installed for the first time for the district heating system in Bundang. Simulation analysis using TRNSYS focused on the thermal behavior and long-term thermal efficiency of solar system. Experiment carried out for the reliability of simulation system. This solar system where the circuits of two different collectors, flat plate and vacuum tube collector, are connected in series by a collector heat exchanger, and the collection characteristics of each circuit varies. Therefore, these differences must be considered for the system's control. This system uses variable flow rate control in order to obtain always setting temperature of hot water by solar system. Specifically, this is a system that heats returning district heating water (DHW) at approximately $60^{\circ}C$ using a solar collector without a storage tank, up to the setting temperature of approximately $85{\sim}95^{\circ}C$ To realize this, a flat plate collector and a vacuum tube collector are used as separate collector loops. The first heating is performed by a flat plate collector loop and the second by a vacuum tube collector loop. In a gross collector area basis, the mean system efficiency, for 4 years, of a flat plate collector is 33.4% and a vacuum tube collector is 41.2%. The yearly total collection energy is 2,342GJ and really collection energy per unit area ($m^2$) is 1.92GJ and 2.37GJ respectively for the flat plate vacuum tube collector. This result is very important on the share of each collector area in this type of solar district heating system.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.27-33
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• 2014

To well design the solar energy system using solar energy, the correlation to calculate solar irradiation is basically needed. So, this study was performed to reveal the relationships between the solar irradiation and four meteorological observation data(dry bulb temperature, relative humidity, sunshine duration, and cloud cover) which are different from previous other researches. And then, we finally proposed the first order non-linear correlation from the measured solar irradiation using four meteorological observation data with MINITAB. To show the deviation of the solar irradiation between measured and calculated, this study compared using the daily total solar irradiance and the maximum peak value. From those results, the calculation error was estimated about maximum 25.4% for the daily total solar irradiance. The error of the solar irradiation between measured and calculated was made from the curve fitting error. So, solar irradiation prediction correlation with higher accuracy can be obtained using 2nd or higher order terms with four meteorological observation data.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.888-889
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• 2011

As new one of superconducting power supplies, we proposed an HTS flux pump utilized a solar energy system. As an eternal electric energy can be converted by the solar system, the solar energy system is promisingly applied as an energy source in the power applications. A solar energy system is comprised of solar panel, photo-voltaic (PV) controller, converter and battery. The HTS flux pump consists of an electromagnet, two thermal heaters and a Bi-2223 magnet. In this paper, we describe the possibility the fusion technology between superconducting power supply and solar energy system. As a fundamental step, the fabrication, structure and experimental results are explained.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2198-2204
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• 2003

In order to make a match of the insufficient direct solar radiation, in this study, the target output is lowered to 9 kW smaller than 25 kW in former studies. It is also necessary to match the collector/receiver with engine/generator systems to accomplish the power level of a system. The simulation analyses of a dish solar power system with stirling engine are totally carried out to predict the system performance with the designed values. In addition, an influence of direct solar radiation on system performance and operation control is discussed in simulation. It is found that the diameter of concentrator could be made small to 8 m regardless of slope errors with 2.5 and 5.0 mrad radiation, and the operation range of mean pressure control. is wide even if the direct solar radiation is a quit low.

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.75-81
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• 2008

Thermal performance of passive solar Trombe wall system which is applied on the south wall of KIER Zero energy Solar House has been monitored for 6 months of heating season. Based upon the long-term measurement results, extensive statistical analysis was conducted to investigate temperature profiler and heat flow pattern in Trombe wall system under actual operating condition. Heat flow characteristics depending on the time variation of day and month was clearly revealed. Heat gain and loss on the inner surface of the Trombe wall was calculated base upon measured temperature data. Those results would be utilized to improve the efficiency of new type solar storage wall system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.2
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• pp.92-98
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• 2002

It is necessary to measure the solar cell parameter fur understanding characteristic of solar cell and applying to many other fields. Since photovoltaic system consists of solar cell module, which are connected each other in series and parallel, it is not proper to apply a solar cell parameter to photovoltaic system. Therefore, to estimate the solar tell module and to solve the problem of the established algorithm is on demand. In this paper the authors have improved the accuracy of solar cell module Parameter estimation by compensating series and Parallel resistance, and developed a new parameter estimation algorithm, which can be applied to photovoltaic system without high cost measuring equipment. And the validity of proposed algorithm is verified by the simulation and experimentation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.396-400
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• 2005

Solar cell and battery capacity are very important for stable design of stand-alone solar photovoltaic power generation system. If capacity computation of solar cell and battery is a wrong, operation of the solar system becomes unstable and results in breakdown. Therefore, in this paper, a solar cell and battery capacity calculation method considering the load characteristics has been proposed for the stable operation of the solar photovoltaic power generation system.

• Journal of the Korean Solar Energy Society
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• v.28 no.4
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• pp.43-49
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• 2008

The purpose of this study is to present the simulation results and an overview of the performance assessment of a solar heating & cooling system by means of the $200m^2$ evacuated tube solar collector. The simulation was carried out using the thermal simulation code TRNSYS with new model of a single-effect LiBr/$H_{2}O$ absorption chiller developed by this study. The calculation was performed for yearly long-term thermal performance and for two design factors: the solar hot water storage tank and the cold water storage tank. As a result, it was anticipated that the yearly mean system efficiency is 46.7% and the solar fraction for the heating, cooling and hot water supply are about 84.4 %, 41.7% and 72.4%, respectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.156-161
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• 2004

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar hot water heater with high efficiency has been used for the house and the industrial process on business, advanced nations were reached up the experimental stage of solar generation system. But, the actual circumstance of the domestic has been not accomplished the popularization of solar hot water heater and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar hot water heater, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar hot water heater, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid for the enlargement and the popularization on solar energy.