• 한국농공학회지
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• 제40권6호
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• pp.46-56
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• 1998

This study was performed to investigate thermal performances of two different types of flat-plate solar collector systems; natural circulation system and forced circulation system. Conclusions obtained from this study are summarized as follows; 1) In the natural circulation system, the total heat amounts retrieved by starting recovery soon after sunrise were ranged from 10.28 to 17.20MJ/m$^2$, while the total heat amounts retrieved by starting recovery after sunset were ranged from 5.31 to 10.77MJ/m$^2$. 2) The collector efficiency in natural circulation system were ranged from 51.1% to 54.1% when the collected heat was retrieved after sunrise and were 65.8~78.0% when the collected heat was retrieved soon after sunset. 3) According to the regression analysis between fluid flow rates and fluid temperature difference at inlet and outlet of collector pipe, there was high regressive corelations with regression coefficient, r, of 0.982. 4) The collector efficiencies estimated for forced circulation system were 73.1~88.6%, and 78.4~94.8%, and 64.2%~74.5%, respectively when fluid circulation rates were 4.2 l/min, and 7.0 l/min, respectively.

• 한국태양에너지학회 논문집
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• 제36권4호
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• pp.49-56
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• 2016

The objective of this work is to analyze the variation in energy performance for each flat plate collector connected in series. In this study, it was assumed that solar water heating system with annual solar fraction of 60% was installed in an office building in Seoul, South Korea. The transient energy performance corresponding to four cases, which are selected using different solar radiation and outdoor air temperature, is studied by analyzing the variation in outlet temperature, solar useful heat gain, and thermal efficiency of each collector. It is observed that the useful heat gain and the collector efficiency decrease continuously, and outlet temperature increases when increasing the number of collector connected in series. The long-term performance is assessed by evaluating the thermal efficiency of each collector for two solar radiation conditions ranging from 780 to $820W/m^2$ and from 380 to $420W/m^2$. It is found that the differences between the intercept and slope of the efficiency curves for first and eighth collectors are 3.68% and 6.74% for solar radiation of $800{\pm}20W/m^2$ and 8.57% and 12.90% for solar radiation of $400{\pm}20W/m^2$, respectively. In addition, it is interesting to note that annual useful heat gain and collector efficiency are reduced with similar rate of about 6.13% when increasing the collector area by connecting the collectors in series.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.316-321
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• 2000

In this study, heat collecting performance was study of flat plate solar collector by the angle. A method of study on were made turn out artificial sun by the angle of 0, 15, 30 degrees. The heat performances were measured the tube array surface temperature by thermo-couple. The winter season natural condition for 4 times on the angles of various general and emboss glass at optimum distance(0.68m) calculated of between sun and solar collector. To sum up temperature rise is appear more or less that emboss glass is all the better for general glass. The temperature variable at below of 30 degree was appear very less. The maximum performance of this system at that it is tilt angle of 30 with general glass is appear Q:11.54(kcal/min) and ${\Delta}T=18.9^{\circ}C$.

• Journal of Biosystems Engineering
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• 제3권2호
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• pp.114-125
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• 1978

The use of petroleum fuels in grain drying causes problems of high cost and management. To solve these problems, it is required to study on soLar energy as an alternative to petroleum fuels for grain drying. The purposes of this study were to find out the optimum received area and air flow rate of a flat-plate solar air collector for grain drying and to assess its effects on grain drying with a small grain bin. The results of this study are summarized as follows ; 1. The calculated optimum tilt angles of the collector in the summer and autumn drying seasons were 20 and 50 degress, respectively, in suwon area. 2. The outlet temperature of the collector was $36^\circ C$ on the daily average with the maximum of $36^\circ C$ at 12:00 o clock. Solar radiation on the collector surface was 1.04 ly( 1 langley = 1 cal/$cm^2$) per minute on the daily average and 1.30 ly per minute on the maximum at 11:00am. The thermal efficiency of the collector was 62.4 percent on the daily average, and the air flow-rate per unit receiving are was 1.03 $m^3$/min/$m^2$.4. The calculated optimum receiving area and the air flow-rate per unit cubic volume for paddy in autumn drying season was 2 $m^2$ and 2$m^3$/min , respectively. 5. not significantly difference in the collector efficiency was appeared between the rotating and fixed type of solar collector. 6. For drying of wheat with 0.6 meter of the depth in the bin, approximately 9 hours were required to reduce the moisture content from 21.6% to 13% with air follow rate of 5 $m^3$/min an initial moisture per cubic meter of wheat and with air temperature of $52^\circ C$. 7. In the drying test of rough rice with a turning operation in a grain bin approximately 21 hours were required to reduced the moisture from 21% to 14.5% with airflow rate of 2 $m^3$/min per cubic meter of rice and the air temperature of $43.5^\circ C$. 8. Over-drying at the bottom and less -drying at the top of the grain mass was resulted from the high -temperature of drying air which was obtained from the flat-plate solar collector in this test. An appropriate operation should be prepared for the uniform moisture of the grain in the bin.

• 한국태양에너지학회 논문집
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• 제35권4호
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• pp.1-7
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• 2015

The operation of the natural circulation type solar heating systems with facade integrated collector was analyzed by experiment. Two different types of flat plate solar collectors were used for these experiments. One was for the normal flat plate solar collector with the size of 1m*2m and the other was for the large size solar collector with $4m^2$(1m*4m). The experiments were carried out to investigate the effect of the series or parallel connection method on the performance of the collectors. As a result, the solar thermal system which is installed on the wall or facade would be applicable for the natural circulation type if the system design reflects various parameters, including collector connecting method(series or parallel), to provide enough vertical height between collector and storage tank, and to reduce pressure loss due to collector and piping network, etc. The natural circulation type of solar thermal system as proposed in this study can increase the system reliability by removing or minimizing the use of the components such as pump, controller, sensors which may cause serious troubles of the system for a long-time operation

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.49-56
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• 2014

Research about hybrid solar air-water heater that can make heated air and hot water was conducted as a part of improving efficiency of solar thermal energy. At this experiment, ability of making heating air and hot water was investigated and compared with traditional solar air heater and flat plate solar collector for hot water when air or liquid was heated respectively. Comparing hybrid solar air-water heater that used in this experiment to other solar air heater studied already, it has a lower efficiency at same mass flow rate. Air channel structure, fin's shape and arrangement in the air channel result in these difference then the ability of air heating need to be improved with changing these thing. In case of making hot water, performance was shown as similar with traditional system although the air channels were established beneath absorbing plate. But the heat loss coefficient was shown higher value by installing of air channel. Also the performance of hot water making was shown lower value at same liquid mass flow rate with traditional flat plate solar collector for hot water. So the necessity of performance improvement at lower mass flow rate of each heating medium can be confirmed.

• 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.

• 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.

• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.21-27
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• 2008

In this study, the design of the solar heating system for district heating as well as it's operating characteristics and the performance analysis was carried out. This solar district heating system was composed of two different types of solar collector circuit, flat plate and vacuum tube solar collector, in a system. This system supply constant temperature of hot water without solar buffer tank. For this, the proportional(variable flow rate) control was used. The experimental facility for this study was used the Bundang district solar heating system which was installed in the end of 2006. The operating characteristics and behaviour of each collector circuits are investigated especially for the system design and control. The yearly solar thermal efficiency is 47.5% on the basis of aperture area and 39.8% on the basis of gross area of collector. As a result this solar heating system without solar buffer tank and with proportional controller was testified a very effective and simplified system for district heating. It varied especially depend on the weather condition like as solar radiation and ambient temperature.

• 생물환경조절학회지
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• 제9권3호
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• pp.166-170
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• 2000

자연열(태양열)을 효율적으로 이용하기위해 1999년부터 2000년 까지 2년간 상면적이 100$m^2$인 3동의 유리온실에 각기 다른 집열시스템을 설치하였다. 즉, 집열면적과 경사도가 각각 24$m^2$, 50$^{\circ}$로서 현재 시판되고 있는 태양열 집열기(평판형, Solar hart Inc.)를 이용하는 방법, 직경과 송풍량이 각각 1m, 2.5m$^{-3}$.m$^{-2}$ .min로서 라디에이터가 부착된 2개의 유동팬을 천장부에 설치하고 천창을 밀폐한 후 온실상부의 열을 집열하는 방법, 온실의 중도리 전부를 물이 순환되는 각관 (75x45x3t, 1m 간격x10줄x온실길이 12m=120m)으로 설치하여 집열하는 방법 등으로 하였다. 각 동마다 지하에 26톤의 저수 능력을 갖는 D2000xW1500xL8600의 축열조를 설치한 후 중간을 막아 저온수조와 고온수조로 구분하였고, 수조 중간 1.5m 높이에 통수로를 내어 일정량의 물(약 15톤)이 지속적으로 순화될 수 있도록 하였다. 최저기온 9$^{\circ}C$로 설정하여 1,000$m^2$를 공간 난방할 경우 난방연료 절감율은 태양열 집열기, 유동팬 및 각관에서 각각 7%, 19%, 28%로 나타났다. 태양열 집열기를 이용하는 대부분의 농가에서는 40~50$m^2$ 정도의 집열면적을 갖는 집열기를 이용하고 있는데 이 경우 년간 난방연료 절감율은 14% 정도로서 경제성이 없으며, 유동팬도 집열효율에 비해 제작, 설치 및 유지비가 과다하게 소요되므로 경제성이 없다. 각관의 경우 관 자체의 자재비나 설치비에 추가부담이 적으면서 집열효율이 비교적 높기 때문에 관의 부식, 골조 표면적 증가에 의한 시설내 차광 증가, 중도리의 각형 구조로 인한 강도저하 등의 문제가 해결되면 집열 방법으로 고려될 수 있을 것이다.