• 대한기계학회논문집B
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• 제37권9호
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• pp.799-805
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• 2013

본 논문에서는 나노유체를 사용한 평판형 집열기의 효율을 예측하기 위한 이론적인 연구를 수행하였다. 평판형 태양열 집열기 내부의 온도분포에 관한 해석적 해를 구하기 위해 무차원화된 2 차원 열 확산방정식을 풀었으며, 이 과정에서 흡광계수와 복사강도는 파장에 독립적이라고 가정하였다. 이렇게 주어진 식을 바탕으로, 물-기반 단일벽 탄소나노혼 나노유체를 작동유체로 사용할 경우 나노입자의 부피비, 열손실의 크기, 집열기의 높이에 따른 무차원 온도분포를 파악해 보았다. 마지막으로 나노유체 기반 평판형 집열기의 효율을 예측해 본 결과 일정 형상조건 이내에서 나노유체 태양열 집열기가 기존 집열기 보다 높은 효율을 가질 수 있음을 파악하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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• pp.215-220
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• 2008

This study shows the results on thermal performance test with domestic solar collector for low-temperature applications using KS, then reveals the efficiency difference between KS and EN standard. Using the test results, this study presents the status of thermal performance with domestic solar collector including flat-plate, single evacuated, and double evacuated (with mirror or U-tube) solar collector.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.376-383
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• 2019

This paper presents of thermal performance analysis by using mathematical models for a compound parabolic collector (CPC) system employing heat storage tank. The thermal performance including insolation energy, heat loss from collector system, useful energy, collector efficiency, and temperature of storage tank were theoretically investigated through a year using monthly-average meteorological data at Seoul. The simulated results showed that the CPC systems are suitable for the applications of higher temperature than flat plate collector (FPC) systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1956-1958
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• 1999

The analysis of hole injection efficiency at the p+/n-drift layer junction in non-punchthrough IGBT structure is presented. This analysis takes into account carrier concentration variations by conductivity modulation. Good agreement between this analysis and simulation is found over a wide range of carrier lifetime and current density. The proposed analytical model of the hole injection efficiency as a function of collector width, collector concentration has been verified by device simulator, ATLAS.

• 전기학회논문지
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• 제60권9호
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• pp.1721-1726
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• 2011

Recently, interest in renewable energy is increased due to exhaustion of fossil fuel and environmental pollution all over the world, therefore the solar power generation using solar energy is many researched. The solar power generation is required solar tracking control and high concentration solar thermal collector because generation performance is depended on concentrator efficiency. This paper proposes high efficiency solar power generation with two-axis tracking control using dish-type solar thermal collector that has excellent thermal collector performance and tracking algorithm that can be accurately tracked solar position. This paper proves validity through analysis with accuracy of tracking algorithm and generating efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.130.2-130.2
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• 2011

The application of solar energy in residential building is general and natural in today. And application methods of solar thermal energy is divided in two kind of form, single evacuated tube and flat-plate form. Then in this study, the efficiency of single evacuated tube and flat-plate system is compared by total and effective area considering the time receiving the solar radiation between 24 hours and the specific time(10:00~15:00). As a result of the experiment, single evacuated tube and flat-plate collector's efficiency is varied by the quantity of solar radiation. And especially, the flat-plate system is more affected by outdoor temperature. Therefore the application of solar thermal system should be considered the solar radiation and outdoor temperature.

• 한국입자에어로졸학회지
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• 제10권4호
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• pp.155-162
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• 2014

The internal temperature will change depending on operation conditions and material of cyclone dust collector. This study compares the results of collection efficiency and temperature distribution on the different heat flux at wall of dust collector. The previous researcher's experiment results were used to confirm the reliability of CFD(Computational Fluid Dynamics) model. Based on this verified CFD model, we extended the analysis on the cyclone dust collectors. In CFD study, we used RNG k-epsilon model for analysis of turbulence flow, fluid is air, the velocity at inlet is 10 m/s, the temperature of air is $600^{\circ}C$. Because of the difference of outer vortex and inner vortex temperature, the collection efficiency will reduce with the increase of heat flux, showed the highest collection efficiency at heat insulation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.65.1-65.1
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• 2010

Thermal performance tests of solar thermal collectors include determination of coefficient parameters in an efficiency equation. The parameters can be estimated using regression method to minimize an objective function as sum of differences between measured efficiency data and regressed efficiency equation. However, this conventional approach doesn't consider measurement uncertainties. In this presentation, a method to determine regression parameters in the efficiency equation and uncertainties of the parameters is described with mainly mathematical expressions based on literature reviews. In the method, parameters in the equation for collector efficiency can be determined using regression analysis with a weighting factor in the objective function. The weighting factor can be uncertainties of the differences between measured and fitted efficiencies. To evaluate the approach, performance estimation of a solar collector using the efficiency equation with uncertainties is compared to the result using the conventional efficiency equation by a simulated way for a case in one of previous studies.

• Korean Chemical Engineering Research
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• 제52권2호
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• pp.182-186
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• 2014

두 종류의 집전체(BP, bipolar plate)를 사용하여 바나듐 레독스-흐름 전지(V-RFB, vanadium redox-flow battery)의 성능을 평가하였다. V-RFB의 성능평가는 $60mA/cm^2$의 전류밀도에서 진행하였다. A 집전체를 사용한 V-RFB의 기전력(SOC 100%에서의 OVC)은 1.47V, B 집전체를 사용한 V-RFB의 기전력은 1.54V를 나타냈다. A 집전체를 사용한 V-RFB의 셀 저항은 충전시에 $4.44{\sim}5.00{\Omega}{\cdot}cm^2$을, 방전시에 $3.28{\sim}3.75{\Omega}{\cdot}cm^2$를 보였으며, B 집전체를 사용한 V-RFB의 셀 저항은 충전시에 $4.19{\sim}4.42{\Omega}{\cdot}cm^2$, 방전시에 $4.71{\sim}5.49{\Omega}{\cdot}cm^2$를 나타냈다. 각 집전체를 사용한 V-RFB의 성능은 5회 충방전 실험을 진행하여 평가하였다. A 집전체를 사용한 V-RFB는 평균 전류효율 93.1%, 평균 전압효율 76.8%, 평균 에너지효율 71.4%를 나타냈으며, B 집전체를 사용한 V-RFB는 평균 전류효율 96.4%, 평균 전압효율 73.6%, 평균 에너지효율 71.0%를 나타냈다.

• 한국태양에너지학회 논문집
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• 제39권6호
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• pp.83-91
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• 2019

Photovoltaic thermal (PVT) collectors are devices that simultaneously produce electricity and heat. Research on conventional air-type PVT collector focuses on installing baffles to enhance the collector's thermal performance. However, the baffles have pressure drop inside the collector which degrades the thermal performance. Thus, it is necessary to design baffles to smoothen the flow inside the air-type PVT collector. Alternatively, installing perforated baffles in air-type PVT collectors can reduce the collector weight, but parameters such as the diameter of the perforated holes and the height of the perforated plates should be considered. Therefore, the main aim of this study was to analyze thermal characteristics of each variable of perforated baffles installed inside air-type PVT collector. For this purpose, the uniformity of air flow in the collector was compared through NX program, and the resultant heat gain and thermal efficiency of the air-type PVT collector were compared and analyzed. Therefore, the main aim of this study was to analyze thermal characteristics of each variable (Baffle angle, length, height, pitch, perforated ratio) of perforated baffles installed inside air-type PVT collector. For this purpose, the uniformity of air flow in the collector was compared through CFD program, and the resultant heat gain and thermal efficiency of the air-type PVT collector were compared and analyzed. As a result, the maximum outlet temperature was increased by 1.45 times and the heat gain was increased by 193.8 Wth, depending on the perforated baffle plate, compared to the collector without the baffle. The heat transfer performance showed that the maximum internal velocity was 1.61 times higher and the Reynolds number was 1.06 times higher depending on the parameters of the baffle plate.