• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.2
• /
• pp.191-196
• /
• 2014

The solar water heating system is one of the seven green campus items installed at the Gangneung campus of Gangneung-Wonju National University. The solar water heating system has two types of solar collectors, four storage tanks and monitoring equipment. Fixed and azimuth-tracking solar collectors were installed to collect heat from the sun. The amount of heat collected by the two different types of solar collectors was calculated from the temperature of the monitored storage tanks. Our results showed that the amount of solar heat collected by the azimuth-tracking solar collector was 19% greater on a sunny day and 23% greater on a rainy day than that collected by the fixed solar collector; therefore, the azimuth-tracking solar collectors are, on an average, 21% more efficient than the fixed solar collectors.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.6
• /
• pp.122-127
• /
• 2011

In this study, it was compared collecting performance according to contact types between heatpipe and manifold of vacuum tube type solar collector. Between two types, direct contact type is better in collecting performance. On the other hand, Indirect type have advantage in maintenance. In the result of numerical analysis, As the temperature of heatpipe and flow rate of working fluid increased, difference of outlet mean temperature of two types became large. Also, it could be confirmed, as contact resistance between heatpipe and copper tube in indirect type increased, the difference increased too. Useful data in selection and design in vacuum tube type solar collector were proposed by the results of numerical analysis.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.4
• /
• pp.411-420
• /
• 2016

Efforts have continued in recent years to research and develop new alternative energy sources to replace coal and oil. These days interest is exploding in new pollution-free renewable energy due to the rising prices of finite energy sources. In the field of solar energy, one of new renewable energy that has been actively researched and commercialized, research efforts have been focused on solar light energy, whose efficiency has, however, reached a saturation point already. Thus, this paper proposed a solar tracking-type parabolic heat collection device to utilize solar thermal energy rather than solar light energy. The proposed device was designed in a parabolic form to collect solar heat effectively. The investigator made its prototype by incorporating a five-axis censor-based solar tracking technology in it to sense changes to the location of the sun according to the seasons and periods. In addition, an administrator interface was designed and implemented for the efficient management of heat collection device.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.122-126
• /
• 2017

The aim of this study was to develop a device for solving the heating problem of living space using heated air, utilizing a simple air heater type collector for solar energy. At the present time, this study assessed the possibility of a development system through theoretical calculations for the amount of available energy according to the size change of the air-heated solar energy collector. To produce and supply hot water using the heat energy of the sun, hot water at $100^{\circ}C$ or less was produced using a flat or vacuum tube type collector. The purpose of this study was to research the air heating type solar collector that utilizes heating energy with heating air above $75^{\circ}C$, by designing and manufacturing an air piping type solar collector that is a simpler type than a conventional solar collector system. The analysis results were obtained for the generated air temperature ($^{\circ}C$) and the production of air (kg/h) to determine the performance of air heating by an air-heated solar collector according to the heat transfer characteristics in the collector of the model when a specified amount of heat flux was dropped into a solar collector of a certain size using PHOENICS, which is a heat flow analysis program applying the Finite Volume Method. From the analysis result, the temperature of the air obtained was approximately $40.5^{\circ}C$, which could be heated using an air heating tube with an inner diameter of 0.1m made of aluminum in a collector with a size of $1.2m{\times}1.1m{\times}0.19m$. The production of air was approximately 161 m3/h. This device can be applied to maintain a suitable environment for human activity using the heat energy of the sun.

• KIEAE Journal
• /
• v.16 no.4
• /
• pp.63-69
• /
• 2016

Purpose: This preliminary study investigated a potential of the water wall systems that provide heat storage and natural lighting control simultaneously. Method: In order for transparency of the water wall to be controlled, the study first proposed two measures: to adjust transparency of the water wall; to control transparency of water wall surface. The performance of two measures then was verified and compared by experiments. In addition, a trade-off between heat collect and heat storage resulting from using additive for adjusting transparency was investigated. Result: The experiment showed that the two measures are similar in performance. The investigation of trade-off relation showed the additive should have the same heat storage as the water to prevent decrease in thermal performance of the water wall. As an economical measure to control transparency of the water wall, this study suggested a measure of secondary heat transfer systems using shading device that first absorbs solar radiation and then transfers heat to the water wall. The experiment show that performance of the proposed measure is similar to controlling transparency of water wall surface. In conclusion, it is expected that the performance of the water wall can be economically maximized by using the proposed mean in terms of heating, cooling and lighting energy saving.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.28-34
• /
• 2019

Solar energy is one of the most abundant renewable energy sources on Earth but there are restrictions on the use of solar thermal energy due to the time-discrepancy between the solar-rich season and heating demand. In Europe and Canada, a seasonal solar thermal energy storage (SSTES), which stores the abundant solar heat in the summer and uses the heat for the winter heating load, is used. Recently, SSTES has been introduced in Korea and empirical studies are actively underway. In this study, a $2,000m^2$ flat plate type solar collector and $20,000m^2$ of borehole thermal energy storage (BTES) were studied for a greenhouse in Hwaseong City, which has a heating load of 2,164 GJ/year. To predict the dynamic performance of the system over time, it was simulated using the TRNSYS 18 program, and the solar fraction of the system with the control conditions was investigated. As a result, the solar BTES system proposed in this study showed an average solar fraction of approximately 60% for 5 years when differential temperature control was applied to both collecting solar thermal energy and discharging BTES. The proposed system simplified the configuration and control method of the solar BTES system and secured its performance.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.3
• /
• pp.17-24
• /
• 2006

최근에 에너지절약 차원에서 종래의 공조방식을 대신할 새로운 냉난방시스템 개발이 요구되고 있는데, 본 논문에서는 태양열 집열기를 이용하는 데시컨트 시스템 중 제습역할을 실질적으로 담당하는 제습기의 충진층 부분에서의 열 및 물질전달에 관한 일련의 해석 결과를 발표하고 있다. 제습과정에서 액체흡수제는 충진층에서 열 뿐만 아니라 물질전달을 수반하게 되는데, 이 결과 건물에 냉방 및 난방효과를 가져다 준다. 따라서 이 충진층의 최적 설계가시스템의 효율을 극대화하기 위해서는 무엇보다도 중요한데, 이를 위해서는 충진층에서의 열 및 물질전달 양상을 규명하여야 한다. 따라서 금번 실험에서는 공기와 액체흡수제와의 접촉면적을 넓히기 위해서 충진재로써 3cm(직경) ${\times}$ 3cm(높이)인 시판중인 플라스틱 재질을 사용하고, 실질적으로 40cm(너비)${\sim}$40cm(깊이)${\times}$40cm(높이)의 충진층을 직접 제작하여 실험을 행하였다. 그 결과, 공기측 열 및 물질전달 계수는 공기 온도와 밀접한 관계를 갖고 있으며, 또한 물질전달계수는 열전달계수와 같은 경향을 보이고 있음을 알 수 있었다.

• Journal of the Korean Solar Energy Society
• /
• v.28 no.5
• /
• pp.21-27
• /
• 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.

• Journal of agriculture & life science
• /
• v.50 no.2
• /
• pp.175-185
• /
• 2016

In this study, manufactured experimental pig house (two pig house) and compared the changes in internal temperature and energy depending on the application of UTC control system for their utilizing of them as basic data for maintaining proper conditions for feeding environment and reducing heating energy depending on the UTC control system and program development, prior to applying the UTC system into pig house, representative agricultural facility. The control system ranges T1~T4 which is made to control a total of five output signals O1~O5 in the way of On/Off by using the algorithms of the program after measuring temperature scored 4 of total. Temperature setting was controlled with 28.0℃ in experimental pig house and 34.0℃ in UTC plenum, and output signal was controlled by comparing it with the measured temperature. During 3 days, the maximum temperature were measured at an average 31.8℃ when operated the control system in pig house. At the same time, the maximum temperature were measured 36.6℃ in comparison pig house, it was low temperature at 4.8℃ in experimental pig house than comparison pig house. Also, UTC plenum temperature was showed that rose at an average 50.5℃ by operation of the control program.

• Journal of Energy Engineering
• /
• v.10 no.1
• /
• pp.24-32
• /
• 2001

본 축열탱크 열전달에 관한 실험적 연구는 국내에서 개발하고 있는 태양열 온수기용으로 현재 널리 이용되고 있는 탱크-코일 방식의 문제점을 해결하면서 열전달 효율이 높은 2중 축열탱크를 개발하기 위한 것이다. 2중 축열탱크의 용량은 100리터로서 수평 및 수직형으로 설치하여 실험이 가능하도록 설계.제작하였고 탱크내부의 온도는 길이방향 및 반지름 방향으로 각각 등간격으로 설치하여 측정하였고 집열매체의 입.출구온도를 동시에 측정하였다. 실험결과는 (1) 축열탱크의 형태에 관계없이 축열탱크와 열교환을 하는 열매체의 유량이 증가할수록 열전달량은 증가한다. (2) 축열탱크의 형태에 따른 탱크내부 물의 온도 상승속도는 수직형(b)인 경우가 가장 크고, 그 다음 수직형(a), 수평형의 순으로 나타났다. 따라서 이중탱크형의 축열탱크는 수평형 보다 수직형이 동일한 용량의 축열매체 온도를 신속히 상승시킬 수 있다. 아울러 열성층화에 의하여 고온의 축열매체를 이용할 경우 수직형 축열탱크가 더욱 우수한 결과를 나타낸다. (3) 축열탱크 열전달계수(UA) 값은 ( $T_{in}$ - $T_{out}$)/$\Delta$ $T_{m}$ 의 크기에 좌우되며, 열전달계수를 설치방법에 따라 비교하면 수직형(b)>수직형(a)>수평형의 순서로 나타났다.다.