• Solar Energy
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• v.6 no.1
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• pp.47-59
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• 1986

This paper presents the establishment of optimum design conditions and economic evaluation for solar hot water system. The aim of this study is to present thermal performance of solar heating systems and to determine their performance as a function of collector size, storage capacity, tilting of collector and other factors. By analyzing its performance under the various conditions, optimum design of solar heating system can be obtained. System performance are obtained monthly and yearly basis respectively. At the same time the economics of various systems are evaluated. For the computer simulation Mokpo, Kangnung, Chupungnyong and Seoul are selected for particular installation places. As a result, the optimal design condition of solar heating system considering the following factors such as installation angle of collector, capacity of storage tank, collector size in each place can be obtained as follows; (1) Installation angle of collector Tilt = lattitude (2) Capacity of storage tank Solar domestic hot water system : $45\;1/m^2$ Multifamily solar domestic hot water system : $35\;1/m^2$ (3) Collector size i) Solar domestic hot water system Seoul & Chupyungyong area : $11.52\;m^2$ Mokpo area : $8.64\;m^2$ ii) Multifamily solar domestic hot water system Seoul, Chupyungyong & Mokpo area : $345.6\;m^2$ Kangnung area : $259.2\;m^2$

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.203-208
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• 2009

This paper presents demonstration study results derived through field testing of a solar assisted cooling and heating system for the library of a cultural center building located in Gwangju, Korea. The area of demanded cooling and heating for building was about 350m2. Solar hot water was delivered by means of a 200m2 array of evacuated tubular solar collector (ETSC) to drive a single-effect (LiBr/H2O) absorption chiller of 10RT nominal cooling capacity. From March in 2008 to February in 2009, demonstration test were performed for solar cooling and heating system. After experiments and analysis, this study found that solar thermal system was 84% for the solar hot water supply and 12% for space heating and 4% for space cooling.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.2
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• pp.68-82
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• 2018

Radiant floor heating systems with capillary tubes are energy saving systems in which hot water is circulated into capillary tube with a small diameter. In this study, the heating performance of capillary tube system is investigated in an experimental study and a simulation model. The results of the study showed that, the capillary tube radiant floor heating system maintains a more stable floor surface temperature in comparison a PB pipe system. In terms of energy consumption, the capillary tube radiant floor heating system proved to be more efficient than the PB pipe heating system at $40^{\circ}C$ of low temperature hot water supply. The difference between water temperature and room temperature can be held low for heating which saves energy. Low temperature radiant floor heating system with capillary tubes have significant advantages such as health improvement, low energy cost, optimum use of heat source(boiler) and higher operational efficiency.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.183-189
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• 2012

Most of the domestic residential buildings have used the traditional radiant heating system, circulating hot water through the cross-linked polyethylene(PE-X) pipe buried in the floor panel of the heating space. New type of the heating panel was recently developed using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal characteristics of this heating system at the unit heating space which surrounded by outer space whose temperature of air be maintained scheduled value with time. Through the various experiments with several parameters, such as flow rate, inlet and outlet temperatures of hot water and the heating duration and so on, we found that the floor heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4~31% compared with the conventional panel heating system using PE-X pipe. These results could be used for optimal design and efficient operation of the heating system as well as improvement of thermal comfort.

• 연구논문집
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• s.30
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• pp.15-23
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• 2000

In this study, develop the thermal pump using water evaporation and condensation. Vapor from heating room moves up to pumping room and press the water of pumping room. Consequently water is pumped out to water tank. Then hot vapor direct contact with cold water in condensing room after pumping process. At this time, pressure of condensing room is down to-5kPa and suck in water of tank. This pump executes self ping and good durability because of no mechanical moving parts. Thermal pump is pumped cyclic so that, this pump is not used single. Therefore thermal pump of hot water boiler used to multi-stage for stable pumping rate. As the result of performance test, the developed thermal pump proves pumping action of water evaporation/condensation. And total volume flow rate is 500liter during one hour. If three thermal pump is installed parallel, this pump can use to the hot water boiler in the 300,000kcal/h class.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.297-302
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• 2011

According to the standards for district heating substation established by Korea District Heating Corporation, water heating supply systems at over 150 Mcal/h capacity must employ the 2-stage heat exchanger that improves the system efficiency by reusing the heat included in the return water of district heating system already used for space heating. In this paper, the operating characteristics of the system in accordance with the load distribution of two heat exchangers for pre-heating and re-heating cold city water are investigated. The results including mass flow rate, return temperature etc. help to manage district heating system economically.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.572-578
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• 2014

Heating energy was measured in an apartment housing unit with a district heating system, varying the kind of hot water distributors. Ondol coils passing through a living room raised the temperature of the room where the heating was turned off. Including this characteristic of Ondol heating into the modeling, we performed simulations and showed a verification by comparison with the results of measurements. As a result, a main flow control method, which changes hot water flow rate supplied to a housing unit according to the thermal load, can reduce the supplied flow rate and lower the return temperature, compared with a constant flow method. That can result in decreased heat loss in utility-pipe conduits even though the heating energy supplied is almost the same. An outdoor reset control that raises the temperature of the supplied hot water if the outdoor temperature falls has the effect of a quicker response in heating than the reduced flow rate and return temperature.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.4
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• pp.6-18
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• 1982

The performance of two typical types of solar hot water heating system was tested in Seoul. Types of systems studied are single-tank internal external heat exchanger system and single-tank internal heat exchanger system. Comparing to experimental results, a transient system simulation program was made to analyze the performance of the selected system. The climate data, Standard Weather Year for Seoul, required for the simulation was provided. Computer simulations were used to estimate the effect of significant parameters upon system performance. The followings are obtained. 1. In the domestic solar water Heating system, the value $20-40kg/m^2\;h$ for flow rate through the collector is much better than the recommended value $72kg/m^2\;h$ in the solar heating system. 2. The effectiveness of collector heat exchanger and storage tank size are found to have only a small effect upon system performance. 3. The hot water draw pattern has a significant effect on system performance. A higher system efficiency achieved when draw-off occurred around noon than when it occurred around early morning. Using the above results, the reference solar hot water system which provides $300\ell$ of hot water per day, was selected as a guide for designer. And simplified graphical method was developed based on the modified f-chart method to determine required collector area. When the system design parameters of the proposed system differs from the reference system, required collector area can be calculated from area adjustment factors.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.360-363
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• 2012

A solar air heating has low efficiency compared with the solar water heating because the heat capacity of the air is small. The heat received by solar collector plate is not fully transferred to the air and then a part of them became the losses to the environment through conduction and convection process. This research is focusing on a design of better combined multi-purposed system suggested by us and aims to secure the more efficient solar energy utilization by combining the hot water and air heating system. The result in this paper has shown that the proposed design has better thermal performance than that of the common design. Furthermore, it was found that the performance of the combined air - water heating system increases the efficiency from 30% to 35%-40%.