• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.9 no.2
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• pp.93-103
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• 1980

A small domestic solar water heating system in thermosyphonic flow was tested in Seoul. The system consisted of four flat plate aluminium roll bond type collectors of total effective area $3.28m^2$ and a $280{\iota}$ storage tank. It was tilted $52^{\circ}$ relative to the horizon. And the collector plate, collector tube and storage tank were equiped with 14 thermocouples. As the results, the following facts were found; 1) To provide water at $55^{\circ}C$ for a family of four in Seoul, a collector area of $3-4m^2$ and a storage capacity of $180{\iota}- 200{\iota}$ are suggested. And this system can supply hot water at above $45^{\circ}C$ day about. 2) In the late afternoon hours, it might be advantageous to stop the flow in the system as heat losses to the environment increase unduly. 3) Without any hot water consumption throughout the day, water temperature distributions inside the storage tank was found almost linear. This indicates essentially no mixing inside the storage tank. 4) In case of a small domestic solar water heating system, it is better to employ a single transparent cover rather than double one.

• Solar Energy
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• v.9 no.3
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• pp.44-54
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• 1989

Heat transfer phenomena during inward melting process of the phase change material were studied experimentally. N-docosane paraffin [$C_{22}H_{46}$] is used for phase change material and its melting temperature is $42.5^{\circ}C$. Experiments were performed for melting of an initially no-sub cooled or subcooled solid in a horizontal cylinder, in order to compare and investigate the radial temperature distribution, ratio of melting and melted mass, various energy components stored from the cylinder wall, figure of the melting front in the horizontal cylinder. The solid-liquid interface motion during phase change was recorded photographically. The experimental results reaffirmed the dominant role played by the conduction at early stage, by the natural convection at longer time during inward melting in the horizontal cylinder. Ratio of melting and melted mass are more influenced by wall temperature, rather than by the initial temperature of solid. The latent energy is the largest contributor to the total stored energy.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.85-92
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• 2014

This study carried out experimental on the cooling characteristics of clathrate compound including TMA(Tri-Methyl-Amine ; $(CH_3)_3N$) as a low temperature latent heat storage material. And additive was used for subcooling improvement of TMA-water clathrate compound. The conclusion of above study is as following ; TMA 25wt%-water clathrate compound is shown stable phase change and low subcooling degree. The subcooling was improved in the case ethanol($CH_3CH_2OH$) 0.5wt% is added to TMA 25wt%-water clathrate compound.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.89-96
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• 2003

In planning a building retrofit, energy conservation, thermal comfort and economic benefits should be considered. In this study, retrofit effects of exterior insulating method on preventing condensation, saving energy were analyzed through the heat transfer simulation, energy simulation in the apartment house retrofitted by exterior insulating method cheaper than other retrofit methods. The results of this study show that the retrofit using exterior insulating method can prevent the condensation at the corner walls and save about 20% of annual heating load. The LCC analysis revealed to be effective to select a dryvit system for a building retrofit.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.40-49
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• 2000

The flow and heat transfer characteristics of the exhaust airflow window system were studied numerically by a finite volume method. Attention was paid to see the decrease in indoor cooling load. The exhaust air flow rate, solar energy power and aspect ratio of window were considered as main variables. From the result of the comparison between the exhaust airflow window and the enclosed window, the indoor heat gain was reduced remarkably by 76%. It is also suggested that in the design of the exhaust airflow window optimum values of aspect ratio, H/W and exhaust air flow rate, Re were about 0.05 and 600, respectively.

• Journal of the Korean earth science society
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• v.39 no.1
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• pp.1-22
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• 2018

Eight different data sets are examined in order to gain insight into the surface heat flux traits of the East Asian marginal seas. In the case of solar radiation of the East Sea (Japan Sea), Coordinated Ocean-ice Reference Experiments ver. 2 (CORE2) and the Objectively Analyzed Air-Sea Fluxes (OAFlux) are similar to the observed data at meteorological stations. A combination is sought by averaging these as well as the Climate Forecast System Reanalysis (CFSR) and the National Centers for Environmental Prediction (NCEP)-1 data to acquire more accurate surface heat flux for the East Asian marginal seas. According to the Combination Data, the annual averages of net heat flux of the East Sea, Yellow Sea, and East China Sea are -61.84, -22.42, and $-97.54Wm^{-2}$, respectively. The Kuroshio area to the south of Japan and the southern East Sea were found to have the largest upward annual mean net heat flux during winter, at -460- -300 and at $-370--300Wm^{-2}$, respectively. The long-term fluctuation (1984-2004) of the net heat flux shows a trend of increasing transport of heat from the ocean into the atmosphere throughout the study area.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.255-259
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• 2012

BIPV/T (Building Intergrated PhotoVoltaic/Thermal) is combined system produces electricity and thermal energy. The heat from PV modules should be removed for better electrical performance, and can be converted into useful thermal energy. The test system is installed to top floor of the experimental house in the KEPCO Research Institute. The experimental performance is executed from 13th February to 13th March, 2012. The expected system's thermal performance is 1.9kWh under the horizontal solar radiation is $600W/m^2$ and the air flow in the system is $20CMH/m^2$.

• Journal of the Korean Solar Energy Society
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• v.22 no.2
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• pp.11-17
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• 2002

This paper is concerned with the development of a new method for making, separating ice and storage floated ice by installing an evaporation plate at under-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating an ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. Developed new harvest-type method shows good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, however these components are not necessary in a new method. In this study ice storage systems are experimentally investigated to study the charge and discharge of thermal energy. The results show the applicable possibility and performance enhancement of a new type.

• Journal of Biosystems Engineering
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• v.36 no.3
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• pp.217-222
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• 2011

This study was carried out in order to reduce the amount of underground water which is used in the double layered single span plastic greenhouse for retaining heat. For this research, two plastic green houses of the double layered single span plastic greenhouse were installed. There was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50 cm in diameter filled with subsurface water. The surplus solar energy in the greenhouse was stored in the water in the PVC duct. Four FCUs (Fan Coil Unit), which has the capacity of 8,000 kcal per hour, were installed in the middle of the house, and a circulation motor in heat storage water tank was operated from 10:30 a.m. to 16:00 p.m. in order to circulate water between the water tank and the FCUs. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of lower than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. To prevent the water freezing, mixing antifreezing liquid in the water or operating FCU continuously was needed. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Considering the amount of water used in the house with water-curtain-heating system is 150~200 ton per day, using the system mentioned in this research showed that reducing the underground water more than 80% in order to maintain the internal temperature as the level of 5 degree celsius at the extreme temperature of minus 5 degrees celsius.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.15-22
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• 2011

It is a great interest to convert more energy in the heat source into the power and to improve the efficiency of power generating processes. Since the efficiency of power generating processes becomes poorer as the temperature of the source decreases, to use an ammonia-water mixture instead of water as working fluid is a possible way to improve the efficiency of the system. In this work performance of ammonia-water regenerative Rankine cycle is investigated for the purpose of extracting maximum power from low-temperature waste heat in the form of sensible energy. Special attention is paid to the effect of system parameters such as mass fraction of ammonia and turbine inlet pressure on the characteristics of system. Results show that the power output increases with the mass fraction of ammonia in the mixture, however workable range of the mass fraction becomes narrower as turbine inlet pressure increases and is able to reach 16.5kW per unit mass flow rate of source air at $180^{\circ}C$.