• 태양에너지
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• 제18권4호
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• pp.59-66
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• 1998

It was compared with experimental data to verify TRNSYS Model of the thermosyphon hot water system and the various simulations were conducted to optimize the component parameters of the system. To obtain consistent simulation results the system model, which could accurately describ the thermal storage tank temperature stratification and the friction head for mass flow rate, was used. The optimization of collector parameters(collector aspect ratio, riser numbers per header unit length), thermal storage tank parameters(ratio of tank length to tank diameter, heat exchanger type), system parameters(ratio of tank volume to collector area) was simulated by TRNSYS program. The simulation results indicate that the system performance is more effected by collector aspect ratio and the ratio of tank volume to collector area than the othor parameters.

• 에너지공학
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• 제23권4호
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• pp.189-195
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• 2014

신재생에너지 분야 중 특히 태양에너지를 이용하는 분야는 자원의 무한 및 청정성 때문에 그 사용량이 증가 추세에 있다. 우리나라에서 태양열에너지의 이용률이 전체 에너지 사용량 중 아직 미미한 실정이지만, 근래 정부의 정책적 지원에 힘입어 이 분야에 대한 연구가 활발히 이루어지고 있다. 본 연구는 태양열집열기의 형상 변화에 따른 집열효율을 조사하기 위하여 단일진공관 태양열집열기를 이용한 실험 및 이중진공관 태양열집열기와의 비교 실험을 수행하였다. 그 결과, 본 실험장치에서 히트 파이프의 최고온도의 차이로부터 태양열집열기 형상 변화에 따른 집열효율의 변화를 확인할 수 있었다. 또한 본 연구대상 태양열집열기의 히트파이프의 온도가 비교대상 태양열집열기보다 높음에도 불구하고 방열핀의 온도가 낮게 관측되었다. 이것은 본 연구대상의 태양열집열기는 히트파이프 방열부인 헤드부와 방열핀 사이의 접촉저항이 비교대상의 접촉저항보다 크다는 것을 나타내며, 집열효율을 높이기 위해서는 태양열집열기의 여러 부분의 성능개선뿐만 아니라 접촉저항에 의한 집열손실도 감소시켜야 함을 확인할 수 있었다.

• 대한기계학회논문집
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• 제7권4호
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• pp.392-397
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• 1983

In the present study, improvement of the solar collector performance by utilizing honeycomb structures is being investigated. Installation of honeycomb structures inside of the collector induces the suppression of would-be natural convection phenomena within the collector enclosure spacing. It also minimizes infrared radiation heat loss from the collector absorber plate to the surrounding. Experiments have been carried out a collector with 40*20mm rectangular honeycombs, 20*20mm square honeycombs and without honeycombs. The results are presented for the three cases for comparisons. The collector model has been installed at various tilt angle from 15.deg. to 60.deg. measured from the ground. The influence of the tilt angle to the heat performance of the collector is also presented.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.27-33
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• 2007

In this research, to develop the practical application system of fresh water generation system with plate-type fresh water generator using low pressure evaporation method is the main object, and to do that, this study used the evacuated solar collector with operating range of about $50-85^{\circ}C$ as thermal energy source and solar photovoltaic as electric energy source. To achieve that object, this study set up the demo-plant, then estimated and analyzed the usefulness, the safety, and the reliability through pre-tests during short time ahead of the long-time operation. This study showed that the pumps, which are including sea water supply, ejector, hot water supply, and fresh water pumps, were operated one after another. And, the fresh water yield was closely related with the solar irradiance and lower supply temperature of hot water was revealed more reasonable for the solar energy desalination system. That is due to the insufficient area than the solar collector area being required that was estimated through the performance tests of the fresh water generator.

• 태양에너지
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• 제5권2호
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• pp.28-34
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• 1985

There are two kinds of irradiation intensity deviation, depending on time and position, on illuminated plane when thermal performance of solar collector is tested by using solar simulator. In this study we measured only position deviation of irradiation intensity using 45-cds photosensors and data acqusition system and found the point of average value. By this result we can improve the accuracy of irradiation measurement in indoor test of solar collector.

• Journal of the Korean Wood Science and Technology
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• 제20권1호
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• pp.5-14
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• 1992

Experimental external collector type solar lumber dryer of $1m^3$ of maximum capacity with $1.6m^3$ of collector area was designed and constructed. The seasonal performance of solar dryer, including air-conditions, energy efficiency, and drying characteristics of 3cm-thick red pine and douglas-fir lumber was investigated. Also, the economic analysis was carried out. Annual average solar drying rate was about 2 times faster than air-drying rate with no significant difference in the amount of drying defects. But in initial drying stage air-drying rate in winter was much faster and those in spring and autumn were slightly slower than solar drying rate in each season. Annual average energy efficiency of solar-dryer and-collector was 25% and 57%, respectively. Fuel savings were over 50% at 15% of energy inflation rate and the payback period was estimated as 6.10 years at 30% of energy inflation rate.

• 대한설비공학회지:설비저널
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• 제12권1호
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• pp.2-11
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• 1983

The solar energy retention rate of a flat plate collector can be increased by increasing water flow rate through the collector which also increases the pumping energy incurred in obtaining that solar energy. The problem of optimal flow rate is formulated to fit within the framework of pontryagin's maximum principle and with a few simplifying assumptions, an optimal solution that can be easily implemented is obtaincd, The optimal solution is used in the simulation of a solar heating system using actual climatological data and the results are compared with that of on-off control. The result that not only the object function but, In some cases, also the solar energy retention rate the collector is increased. In is also found that the optimal control gets more advantageous as the solar insolation level gets lower, and also as tile cost of auxiliary heating fuel gets higher.

• Advances in Energy Research
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• 제5권1호
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• pp.31-55
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• 2017

In the present study, PV/T collector was modeled via analysis of governing equations and physics of the problem. Specifications of solar radiation were computed based on geographical characteristics of the location and the corresponding time. Temperature of the collector plate was calculated as a function of time using the energy equations and temperature behavior of the photovoltaic cell was incorporated in the model with the aid of curve fitting. Subsequently, operational range for reaching to maximal efficiency was studied using Genetic Algorithm (GA) technique. Optimization was performed by defining an objective function based on equivalent value of electrical and thermal energies. Optimal values for equipment components were determined. The optimal value of water flow rate was approximately 1 gallon per minute (gpm). The collector angle was around 50 degrees, respectively. By selecting the optimal values of parameters, efficiency of photovoltaic collector was improved about 17% at initial moments of collector operation. Efficiency increase was around 5% at steady condition. It was demonstrated that utilization of photovoltaic collector can improve efficiency of solar energy-based systems.

• 한국태양에너지학회 논문집
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• 제23권2호
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• pp.81-90
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• 2003

UTAC(unglazed transpired air collector) system has unique advantage for space heating and tempering ventilation air over the conventional collector system such as flat plate and vacuum collector. UTAC can improve radiative and convective loss due to nonglazed component and enhanced plate surface configuration. and heating energy and its equivalent green house emission performance can be improved from the use of this like collector in building application. The Option D Calibration simulation approach of IPMVP(International Performance Measurement and Verification Protocol) in ESCO businesses has been recommended to use of the calibrated computer modules like these Energy-10. DOE2.1E and TRNSYS(transient system simulation). This study is to develop subroutine type-203 of TRNSYS15.2 program and appraise thermal performance of UTAC. With newely addeded subroutine type-203. 1) Thermal performance of unglazed transpired collector could be possible based on dimensionless variables such as efficiency and heat exchanger effectiveness. and 2) Assessement of energy consists of solar useful and insulation saving for UTAC could be possible.

• Applied Biological Chemistry
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• 제25권3호
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• pp.111-118
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• 1982

밀폐식(密閉式)물 교환태양(交換太陽) 열집열건조장치(熱集熱乾燥裝置)를 이용(利用)하여 홍삼(紅蔘)을 건조(乾燥)할때의 집열효율(集熱?率), 건조효율(乾燥?率). 건조특성(乾燥特性) 및 제품(製品)의 품질(品質)을 각각(各各) 조사(調査)하였다. 건조기간(乾燥期間)은 태양열집열장치(太陽熱集熱裝置)를 이용(利用)한 것이 관행법(慣行法)보다 3분(分)의 1정도(程度)를 더 단축(短縮)할 수 있었다. 건조기간중집열기(乾燥期間中集熱機)의 최대효율(最大?率)은 14.42% 최저효율(最低?率)은 4.73%였고 건조효율(乾燥?率)은 집열장치(集熱裝置)를 이용(利用)한 것이 28.34%, 대조구(對照區)가 13.45%로서 순수건조효율(純粹乾燥?率)은 14.89%이었다. 홍삼(紅蔘)의 건조율곡석(乾燥率曲線)은 감율건조기(減率乾燥期)만을 나타내었으며, 이때의 식(式)은 $Y=50.7023t^{-0.4138}$이었다. 건조홍삼(乾燥紅蔘)의 색도(色度)는 관행법(慣行法)과 비교(比較)하여 더 높았으며, diphenyl picryl hydrazyl 환원능(還元能)도 같은 경향(傾向)을 보였다.