• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.221-225
• /
• 2009

A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. A flat plate is the most common type of solar thermal collector, and is usually used as a solar hot water panel to generate solar hot water. A flat plate collector consists basically of an insulated metal box with a glass or a plastic cover and a dark-colored copper absorber plate. Solar radiation is absorbed by the copper absorber plate and transferred to water that circulates through the collector in copper tubes. Ultrasonic welding is an industrial technique whereby high-frequency ultrasonic acoustic vibrations are locally applied to work pieces being held together under pressure to create a solid-state weld. In this study, we developed solar collector ultrasonic welding machine with digital controlled power supply and tested various welding conditions such as welding pressure, welding amplitude, welding speed. Welding speed was considered in 2~12m/min. The width of ultrasonic welds was increased with welding amplitude by 2.2~2.5mm. The fracture load of ultrasonic welds showed 20% higher than domestic products.

• Solar Energy
• /
• v.4 no.2
• /
• pp.29-36
• /
• 1984

This paper reviews the current status of R&D work on selective absorber materials. For the efficient utilization of solar energy, various types of selective absorber materials are being used for solar hot water heaters. Many selective absorbers which have been proposed and designed up to data are classified according to the absorption mechanisms. Temperature-time cycle method is often recommended for the measurement of solar absorptance. In addition, conversion efficiency of the solar collector with selective surface is compared with one with black paint surface.

• Solar Energy
• /
• v.4 no.2
• /
• pp.37-42
• /
• 1984

A computer code for an optimum design of solar space and domestic hot water heating system has been developed. The f-chart method developed by S.A. Klein et al. has been incorporated in the present computer code. The main conclusions obtained from the present work may be summarized as follows: (1) In Seoul area, about 46% of the total heating load can be obtained from the solar collectors whose total surface area is about one-third of the total heating floor area. (2) In Pusan area, total area of solar collectors should be about half of the total heating floor area in order to obtain an equivalent solar fraction of Seoul. (3) In cheju area, on the other hand, only about 42% of the total heating floor area of solar collectors is needed to get the same solar fraction as in Seoul and Pusan. (4) In order to get the first 50% solar fraction, only about 10-14 collectors ($4'{\times}8'$ collectors) are required, whereas about 48 collectors are needed to obtain the solar fraction of 100%. That is, roughly 3.5-4.5 times greater number of collectors are required to increase the solar fraction from 50% to 100%. Therefore, it can be concluded that it is relatively inefficient and less economical to build a solar system whose solar fraction exceeds more than 50%.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.780-785
• /
• 2009

The photovoltaic/thermal collectors (PV/T collectors) combine the solar thermal collector and photovoltaic modules. They can produce thermal energy in the form of hot air or hot water, and converts solar radiation into electricity. The collecctors can improve the electrical performance of PV modules as the heat from the PV module carried away by the thermal part of the system keeping temperatures lower. The basic water cooled PVT collector has metallic water pipes attached to the back of a PV collector. There are main parameters affecting the performance (electrical and thermal) of PVT collectors. This paper analyzed the experimental performance of glazed water PVT module, considering the parameters of solar radiation, inlet water temperature and ambient temperature. It found that solar radiation is the dominant factor for the electrical performance of the collector, and for the thermal performance the inlet water temperature and ambient temperature appeared to be more related.

• Solar Energy
• /
• v.10 no.2
• /
• pp.18-27
• /
• 1990

The hot water producer by the combination of the solar thermal energy and freon gas compression heat has been developed. Freon R-12 gas was circulated through the system including the solar absorption panel, which has no glassing and no insulation, and the frozen and burst problems were intrinsically eliminated. The manufacturing and running costs may go further down than the regular solar hot water systems.

• Solar Energy
• /
• v.8 no.2
• /
• pp.46-56
• /
• 1988

This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

• Journal of the Korean Solar Energy Society
• /
• v.39 no.6
• /
• pp.41-54
• /
• 2019

The purpose of this study is to analyze the performance of solar thermal system according to regional weather conditions and feedwater temperature. The performance analysis of the system was carried out for the annual and winter periods in terms of solar fraction, collector efficiency and it's optimal degree. The system is simulated using TRNSYS program for 6 cities, Seoul, Incheon, Gangneung, Mokpo, Gwangju, and Ulsan. Simulation results prove that the solar fraction of the system varies greatly from region to region, depending on weather conditions and feedwater temperatures. Monthly average solar fraction for winter season from November to February, a time when heat energy is most required, indicated that the highest is 73.6% in Gangnueng and the lowest is 56.9% in Seoul. This is about 30% relative difference between the two cities. On the other hand, the collector efficiency of the system for all six cities was analyzed in the range between 40% and 42%, indicating small difference compare to the solar fraction. The annual average solar fraction is rated the highest at 40 collector degree, while monthly average solar fraction during winter season is rated at 60 degree.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.12
• /
• pp.821-827
• /
• 2010

Study on the performance characteristics of the solar hybrid system with heat pump operating temperature during winter season has performed by using an experimental test. The system performance and operating characteristics with the heat pump operating temperature, hour and load condition were investigated and analyzed. As a result, the hot water temperature was significantly affected by the heat pump operating temperature at the morning(time 1) and noon(time 2). However, hot water temperature was set by the radiation quality and collecting operation hour at the afternoon(time 3). In addition to the solar fraction was decreased for the high heat pump operating temperature because the heat pump operated with a long operating time and short operating period.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.7 no.3
• /
• pp.241-248
• /
• 1983

In the present work a time-dependent reliability model for a typical solar domestic hot water and heating system is developed using the method of Fault Tree Analysis and existing mathematical techniques. The reference system used in this analysis is a typical solar heating system. The system reliability structure has been identified with the aid of Fault Tree methods. In addition, a simulation of the solar system reliability has been performed employing the Monte Carlo method. In the computer simulation, failure rate data such as WASH-1400, MIL-HDBK-217B, and Green and Bourne are used as input data. These results show that the developed reliability model is capable of expressing the primary failure phenomena of the solar heating and domestic hot water system.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.2
• /
• pp.61-69
• /
• 2007

The final energy consumption in the building sector in Korea represents almost 20% of the total energy consumption. Besides, Space heating and hot water generation in Korea are based on fossil fuels, with a serious environmental impact. Despite the popularity of simple solar domestic hot water systems, active solar space heating remains, for various reasons, marginal. And thus, the aim of this paper is to demonstrate potentialities of solar assisted space heating systems, both technically and economically. From this study found that the solar heating system with CPC solar collectors integrated the roof of a single-story residential building shares $50{\sim}55%$ of the annual heating load.