• Journal of the Korean Solar Energy Society
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• v.37 no.2
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• pp.67-75
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• 2017

We have investigated the operating characteristics of $1,600m^2$ large-scale solar thermal system installed in an eco-friendly energy town in Chungbuk Innovation City. The operation criteria of the collecting pump and storage pump were different from the existing standard, and it was confirmed that each pump works well according to the changed criteria. Based on the data of the representative day, the daily collecting heat (efficiency) and the production (storing) heat (efficiency) were estimated. It was confirmed that the daily collecting heat (efficiency) of the flat plate type was higher than that of the evacuated tube type, but the useful heat production was more in evacuated tube type collector.

• Solar Energy
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• v.12 no.2
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• pp.9-17
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• 1992

This is an experimental work concerning about an application of a heat pipe to an evacuated-glass-tube solar collector system. A methanol heat pipe with length of 0.7 m and diameter of 8 mm was manufactured and tested to compare its performance with that of freon thermosyphon which was originally used in a solar collector system fabricated at Thermomax Co.. Then this methanol heat pipe was utilized to be one component, i.e. heat transfer element, of the present experimental model of a solar collector. This model was performed the operation test as its absorber plate was irradiated by infrared lamps. The following results were obtained. (1) The methanol heat pipe was showed a stable operation when the variation of axial heat transport was $0{\sim}40$ watts and that of inclination angle was $30{\sim}90^{\circ}$. (2) The heat transport capability of the heat pipe was proved to be higher than that of the thermosyphon, because the heat transport limitation of the latter was occured at about 30 watt. (3) The heat pipe in a solar collector was also showed good performance as it transmitted absorbed energy.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1542-1547
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• 2003

This paper represents the solar collector performance with type of an evacuate double glass, and a copper tube was installed in center of collector to get a solar thermal energy. The one module of solar collector and artificial sun were used in this experiment The distance between artificial sun and solar collector was fixed at 0.5m, and this experimental condition was focused on winter season. The experiments were carried out. three times for getting a accurate data and the heat amount of one module evacuate d solar collector was estimated at out. 48 kcal/hr.

• Journal of the Korean Solar Energy Society
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• v.22 no.1
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• pp.43-53
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• 2002

This study has been carried out to study the thermal performance of an all-glass type solar collector tube when a heat transfer medium is used with a heat storage unit capable of preventing pressure build-up within the tube. The heat storage unit is devised such that it performs the dual function of relieving excessive pressure and storing solar thermal energy. Different types of heat storage medium are tested under heat-up phase of a collector tube. It is found that the proposed unit could be used quite effectively if one wishes to capitalize more aggressively in harnessing the solar energy.

• Journal of Environmental Science International
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• v.7 no.5
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• pp.669-677
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• 1998

A porous $\alpha$-alumina tube of 2.5 mm O.D. and 1.9 mm I.D. was used as the support of an inorganic membrane. Macropores of the tube, about 150 nm in size, were plugged with silica formed by thermal decomposition of tetraethylorthosilicate at $600^{\circ}C$. The forced cross-flow CVD method that reactant was evacuated through the porous wall of the support was very effective in plugging macropores. The H$_2$ permeance of the prepared membrane was of the order of $10^{-8}/ molㆍs^{-1}/ㆍm^{-2}/. Pa{-1}$/, while the $N_2$ permeance was below $10^{-11}/ molㆍs^{-1}/ㆍm^{-2}/ㆍPa^{-1}$/ at $600^{\circ}C$. This was comparable to that of silica-modified Vycor glass whose size was 4 nm.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1005-1009
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• 1999

Wustite with NaCl structure is successfully synthesized in a quartz tube sealed under vacuum ( ≒1×10 -3 torr). Hematite in an evacuated quartz tube progressively loses oxide ion at 1373 K. XRD patterns disclose that α-Fe2O3 is transformed into the Fe3O4 after heat treatment at 1373 K for 32 h, and the poorly crystallized FeO is appeared after heat treatment for 48 h. Finally, α-Fe2O3 is completely transformed into the well crystallized Fe 0.935O after heat treatment for 84 h. The electrical resistivity, ac-susceptibility measurement, Mossbauer spectroscopy, and x-ray absorption spectroscopy corroborate the structural phase transition on the iron oxides prepared in a sealed quartz tube depending on the heating time at 1373 K.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.324-331
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• 2013

All evacuated tube collector is being constantly studied since it can reduce the conductive heat loss in absorber by using vacuum technology and has advantage of heat transport capacity and quick thermal response in comparatively small temperature difference. This study investigated the dynamic thermal performance of the solar collector with the control condition of solar irradiance and fluid temperature by using performance experimental apparatus which is combined with solar collector and refrigerator, examined the thermal characteristics in definite temperature range of fluid in constant temperature tank by simultaneously measuring refrigerating performance. As a result of it, I deducted the related equation of collector efficiency and found that mean collector efficiency has increased through quick heat transfer characteristics according to increase of outdoor temperature and irradiance in case of outlet temperature of constant temperature tank $22^{\circ}C$ when set outlet temperature of solar collector $25^{\circ}C$ with outlet temperature of constant temperature tank $18^{\circ}C$ & $22^{\circ}C$. Also COP of refrigerator was acquired value of 6.2~7.1 at outlet temperature of constant temperature tank $18^{\circ}C$.

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.129-129
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• 2005

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.152-152
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• 2004

• Progress in Medical Physics
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• v.27 no.4
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• pp.272-276
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• 2016

To investigate the optimum x-ray tube design for the dental radiology, factors affecting x-ray beam characteristics such as tungsten target thickness and anode angle were evaluated. Another goal of the study was to addresses the anode heel effect and off-axis spectra for different target angles. MCNPX has been utilized to simulate the diagnostic x-ray tube with the aim of predicting optimum target angle and angular distribution of x-ray intensity around the x-ray target. For simulation of x-ray spectra, MCNPX was run in photon and electron using default values for PHYS:P and PHYS:E cards to enable full electron and photon transport. The x-ray tube consists of an evacuated 1 mm alumina envelope containing a tungsten anode embedded in a copper part. The envelope is encased in lead shield with an opening window. MCNPX simulations were run for x-ray tube potentials of 70 kV. A monoenergetic electron source at the distance of 2 cm from the anode surface was considered. The electron beam diameter was 0.3 mm striking on the focal spot. In this work, the optimum thickness of tungsten target was $3{\mu}m$ for the 70 kV electron potential. To determine the angle with the highest photon intensity per initial electron striking on the target, the x-ray intensity per initial electron was calculated for different tungsten target angles. The optimum anode angle based only on x-ray beam flatness was 35 degree. It should be mentioned that there is a considerable trade-off between anode angle which determines the focal spot size and geometric penumbra. The optimized thickness of a target material was calculated to maximize the x-ray intensity produced from a tungsten target materials for a 70 keV electron energy. Our results also showed that the anode angle has an influencing effect on heel effect and beam intensity across the beam.