• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.581-586
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• 2015

In this study, an analysis was performed on the performance of the solar water heating system with geo-thermal heat pump for a detached house. This system has a flat plate solar collector ($8\;m^2$) and a 3 RT heat pump. The heat pump acts as an auxiliary heater of the solar water heating system. These systems were installed at four individual houses with the same area of $100\;m^2$. The monitoring results for one year are as follows. (1) The average daily operating time of the solar system appeared to be 313 minutes in spring (intermediate season), and 135 minutes and 76 minutes in winter and summer respectively. The reason for the short operating time in summer is the high storage temperature due to low water heating load. The high storage temperature is caused by a decrease in collecting efficiency as well as by overheating. (2) The geothermal heat pump as an auxiliary heater mainly operates on days of poor insolation during the winter season. (3) Despite controlling for total house area, hot water consumption varies greatly according to the number of people in the family, hot water usage habits, etc. (4) The yearly solar fraction was 69.8 to 91.5 percent, which exceeds the maximum value of 80% as recommended by ASHRAE. So the solar collector area of $8\;m^2$ appeared to be somewhat greater for the house with an area of $100\;m^2$. (5) The observed annual efficiency of solar systems was relatively low at 13.5 to 23.6%, which was analyzed to be due to the decrease in thermal efficiency and the overheating caused by a high solar fraction.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.597-601
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• 2006

The advantages of solar energy are that it is renewable, infinite supplied and environmentally safe energy source. However, solar energy related products have the problems such as the limitation for installation, problems in maintenance and insufficient reliability which have been the barrier to consumers to satisfy the purchase need for solar heat related products. In this regard, in order to support the solar energy related companies the necessity for various technical information required for the commercialization of new products such as various performance test necessary for the certification of solar energy system, standardization for facilities and products, performance evaluation method and the measurement of performance is suggested. The purpose of this paper is to design the monitoring system for positive tests of system linked household hot water system using solar heat out of various solar energy systems, to establish an analysis and monitoring system for performance maintenance and operation technique, and to configure the centralized detection network by utilizing remote monitoring system. This research also aims at conducting monitoring for operation and performance evaluation in relation to database establishment and analytical evaluation and at describing the method of enhancing the reliability of solar energy system through the development of performance evaluation program.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.517-525
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• 1984

This paper presents a typical solar domestic hot water system and estimates their performances with variance of collector size, storage volume, collector tilt and other factors. The analysis is performed by th computer simulation for which conceptual system against 8760 hourly solar intensities and ambient temperature for a model year stored in the computer has been running. System performance is analyzed on hourly, monthly and yearly basis respectively and at the same time, the economics of various systems are evaluated. And also, this paper shows how an optimized design can be selected for any locality for which solar data and collector performance are provided. The results of this study are as follows. (1)Storage volume of 45 liter per square meter of solar collector lead to the best design. (2)Tilting the collectors to the same angle of the latitude is generally the best (3)Optimal size of collector is approximately 6.68-8.35m$^{2}$ when the latitude is 37.6 .deg. N and storage volume is 300 liter. (4)The performances of a solar domestic hot water system does not depend on the hourly usage but the daily usage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.327-333
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

• Solar Energy
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• v.18 no.3
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• pp.107-112
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• 1998

Basic design of a solar driven absorption cooling machine(SDACM) with a cooling capacity of 5 USRT was carried out. The SDACM is a single effect cycle driven by low temperature hot water from solar collectors. The SDACM design data were calculated by the steady state simulation program which was developed in this study The variation of COP and cooling capacity of the SDACM were investigated at different off-design conditions. Both the cooling capacity and the system COP were improved with decreasing cooling water temperature. If hot water temperature was increased, the cooling capacity was improved but the system COP was found to be decreased. The decrease of the system COP were basically caused by increased thermal loads in the system components.

• Solar Energy
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• v.7 no.1
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• pp.3-13
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• 1987

A batch type passive solar water systems, which perform the dual function of absorbing the solar energy and storing the heated water, have been designed and fabricated for the purpose of side-by-side testing at KIER. The test models included an A, B and C type batch systems which were classified according to the design of box and arrangement of tanks. The year-round performance tests show that B type batch system taken the step-wise tank arrangement indicates 55.7% yearly-average collection efficiency factor and 61% yearly-average maximum collection efficiency factor. Computer-aided-experimental results show that the sufficient hot water can be obtained in the early morning if the glazing is supplemented by a reflector/insulation cover. The thermal performance equation has been developed for the prediction of hourly variation of the water temperature in tank.

• Solar Energy
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• v.20 no.2
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• pp.9-17
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• 2000

To obtain thermal performance data, an experiment was performed with the two selected thermosyphon systems. The system parameters obtained by experimental data were used to perform TRNSYS simulation and verified TRNSYS model of thermosyphon solar hot water system. The thermosyphon solar hot water system was TYPE 145 which is modified from non-linear model. This model can describe heat exchange type and non-linear efficiency equation. It is possible to analyze the annual energy rate with efficiency equation and system specification. In this paper, we could compare the annual performance of the coil heat exchanger with that of the tank-in-tank heat exchanger. Under the same efficiency and parameter, heat exchange, drain, initial tank temperature, ratio of tank volume over collector area(V/Ac), regional annual performance rating were performed.

• Solar Energy
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• v.20 no.3
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• pp.51-60
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• 2000

This paper deals with the design, construction and operation of a direct solar hot water heating system developed to harness the solar energy more effectively. The system introduced here uses a unique network of riser tubes and header pipes apart from the existing concept to exploit the physical properties of water which expands when it freezes. It also employs a special pressure relief mechanism for the header to prevent its breakage due to freezing. A number of tests are made to assure its functional reliability during frigid weather conditions and its superior performance over indirect systems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.3
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• pp.241-248
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• 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
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• v.39 no.6
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• pp.41-54
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• 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.