• Solar Energy
• /
• v.20 no.1
• /
• pp.55-62
• /
• 2000

An experimental study on the stratified fluids with water and silicon oil of same volume in the cavity with upper cooling surface was carried out to investigate the flow characteristics, heat transfer through the interface of fluids, and the applications of thermal behaviors in a square cavity. The experiments were performed with variation of initial temperature and cooling surface temperature. The temperature drop of oil was faster than that of water and freezing was initiated from the interface of oil and water and propagated downward. For the water above $4^{\circ}C$, the cooling rate was faster than that below $4^{\circ}C$ and showed almost same temperature distribution but for the water that of below $4^{\circ}C$, it showed the stable stratified temperature distribution. The lower the initial temperature and the higher the cooling surface temperature was, the longer the supercooling duration.

• Proceedings of the SAREK Conference
• /
• 2005.11a
• /
• pp.173-178
• /
• 2005

Recently. we interested in renewable energy due to cost increase of the crude oil, etc. In this study solar assisted hybrid heat pump system that uses the solar heat and air as heat source analyzed by experimentally.'rho system could runs at dual mode. One is thermal storage mode of solar energy at day time and the other is heat pump mode with low temperature air as heat source at night time. In case of setting temperature over the limited range. high temperature water heated at the solar energy collecting tubes supplied to the storage tank. As results. it is founded that the heat pump performance Is higher than general heat pump which using the only air as a heat source. The developed system could be used as main healing equipment for the panel heating for the residential house.

• Journal of Environmental Science International
• /
• v.26 no.12
• /
• pp.1363-1374
• /
• 2017

Global climate change caused by industrialization has caused abnormal weather conditions such as urban temperatures and tropical nights, urban heat waves, heat waves, and heavy rains. Therefore, the study tried to analyze climate conditions and weather conditions in the streets and analyze climate factors and meteorological factors that lead to inconvenience to citizens. In the case of trees, the overall temperature, surface temperature, solar irradiance, and net radiation were measured low, and the temperature was lower in the Pedestrian road than in roads. The dry bulb temperature, the black bulb temperature, and the wet bulb temperature for the thermal evaluation showed the same tendency. In the case of thermal evaluation, there was a similar tendency to temperature in WBGT, MRT, and UTCI, and varied differences between types. Although the correlation between the meteorological environment and the thermal environment showed a statistically significant significance, the difference between the measured items was not significant. The study found that the trees were generally pleasant to weather and thermal climate in the form of trees, and the differences were mostly documented.

• The Journal of Sustainable Design and Educational Environment Research
• /
• v.4 no.4
• /
• pp.19-24
• /
• 2004

The thermal effect of a transparent insulated opake wall with solar energy was investigated theoretically. The heat gain through transparent insulated opake wall was studied for relative simple conditions. The stationary heat transport effect was studied for layer which is built on the opake wall. This study shows that a relative low solar radiation intensity causes a great heat reduction through the transparent insulated opake wall. Because the transparent insulation layer is mostly transparent to solar radiation, it is opaque to heat radiation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.7
• /
• pp.322-328
• /
• 2014

Return piping is used in a solar combi-system for heating and hot water supply. When the temperature of the lower side of a storage tank is low due to hot water usage, the returned hot water after heating is mixed with the lower side cold water of the tank, and the useful energy is reduced. We studied the degree of thermal stratification in the tank, using either a diffuser or a manifold to prevent mixing. Using the diffuser, mixing starts from the bottom of the storage tank. On the other hand, the manifold has the marked effect of preventing mixing. As a result of experiments with changing the diameter and number of holes in the manifold, the optimum condition is 8.5 mm diameter and 96 holes, under the condition of 0.3 lpm.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.04a
• /
• pp.142-147
• /
• 2009

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be tested under vacuum condition and very low temperature in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels such as north and south panels. They will be controlled from 90K to 273K by circulating GN2 and LN2 alternatively according to the test phases, while the shroud of the vacuum chamber will be under constant temperature, 90K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.2
• /
• pp.44-52
• /
• 2014

The main purpose of this paper is to develop the new BIPV module equipped with vacuum glass. Beacuse BIPV module has a function of architectural materials, thermal and PV performance should be simultaneously evaluated. To improve the thermal performance of BIPV module, this study developed BIPV module equipped with a vacuum glass. Those BIPV module was tested with a variety of encapsulants. The results are as follows. When a vacuum glass is laminated with EVA or PVB, it was broken. The reason seems to be bending by unbalance of heat expansion with center and edge of vacuum glass. In case of lamination with resin, there is no breakage and no bending of vacuum glass. Because production was conducted in low pressure & low temperature conditions. And it was also found that vacuum glass does not interfere with the UV curing process.

• Solar Energy
• /
• v.7 no.1
• /
• pp.61-74
• /
• 1987

This review evaluates the state of art in the field of high-temperature energy storage materials and systems. The physical and chemical properties, corrosion data and practical applications of the phase change materials, especially the inorganic salts applicable to storage temperature in the range of $100-850^{\circ}C$ have been summarized. Fluoride salts have excellent thermal storage properties, but these are less attractive in terms of cost and corrosion problem of container materials. The nitrate and nitrite have attractive properties in the temperature range up to $600^{\circ}C$, at which the rate of decomposition becomes unacceptable. Carbonates euteutic salts can be considered as the most promising energy storage material on the basis of their low cost and excellent material compatibility for corrosion in the temperature range up to $850^{\circ}C$.

• Solar Energy
• /
• v.20 no.4
• /
• pp.61-67
• /
• 2000

The purpose of this study is to improve heat transfer by attaching rectangular fins to tube. Experiments were carried out under the following conditions - Aspect ratio$(W_f/R_f)$ is 0.7, 1.2 and 1.8. Temperature conversion between high and low positions of water in the thermal storage appeared because maximum density point of water is about $4^{\circ}C$ and inlet direction of working fluid influenced conductive heat transfer Compared with the unfinned tube(bare tube), the rectangular tube increased the ice thermal storage energy and the ice thermal storage energy was increased as aspect ratio was increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.10
• /
• pp.387-393
• /
• 2016

A ground source heat pump system maintains a constant efficiency due to its stable heat source and radiant heat temperature which provide a more effective thermal performance than that of the air source heat pump system. As an eco-friendly renewable energy source, it can reduce electric power and carbon dioxide. In this study, we analyzed one year of data from a web based remote monitoring system to estimate the thermal performance of GSHP with the capacity of 3RT, which is installed in a low energy house located in Daejeon, Korea. This GSHP system is a hybrid system connected to a solar hot water system. Cold and hot water stored in a buffer tank is supplied to six ceiling cassette type fan coil units and a floor panel heating system installed in each room. The results are as follows. First, the GSHP system was operated for ten minutes intermittently in summer in order to decrease the heat load caused by super-insulation. Second, the energy consumption in winter where the system was operated throughout the entire day was 7.5 times higher than that in summer. Moreover, the annual COP of the heating and cooling system was 4.1 in summer and 4.2 in winter, showing little difference. Third, the outlet temperature of the ground heat exchanger in winter decreased from $13^{\circ}C$ in November to $9^{\circ}C$ in February, while that in summer increased from $14^{\circ}C$ to $17^{\circ}C$ showing that the temperature change in winter is greater than that in summer.