• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.58-66
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• 2019

Static compound parabolic collectors (CPCs) have advantages such as ease for fabrication and lower cost compared with other concentrating collectors. In this study, thermal performance analysis of CPC employing heat storage tank was carried out. The clearness index and capacity of heat storage tank are taken as the main parameters for numerical simulation. The effects of the parameters on the hourly and daily system performances ncluding the useful energy, heat loss, and collector efficiency were numerically investigated. Results showed that the system has a potential for efficient recovery of solar thermal energy.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.630-636
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• 2020

This paper presents a experimental study on the performance of the heat pump. Uncertainty of measurement means the degree of uncertainty in the measurement. Therefore, it estimates a section where expected value of the measurement might be within a certain confidence level and suggests a range where measured representative value might be incorrect. Uncertainty of measurement is a parameter that shows characteristics of dispersion of measured value that was reasonably estimated from measured quantity. Measurement result of performance experiment is not a true value but estimated value that was estimated reasonably. Therefore, uncertainty of measurement needs to be calculated and presented with the result of measurement.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1109-1118
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• 2021

The construction of STELLA-2 facility is on-going to demonstrate the safety system of PGSFR and to provide comprehensive understanding of transient behavior under DBEs. Considering that most events are single-phase natural circulation flow with slow transient, STELLA-2 was designed with reduced-height of 1/5 length scale. The ratio of volume to surface area in the vessel can relatively increase resulting in excessive heat transfer. Therefore, a steady-state thermal-hydraulic analysis was performed and the effect of design change to reduce the heat transfer through redan was investigated. The heat transfer through single wall redan in STELLA-2 was 3% of the core power, comparable to 1% of the core power in PGSFR. By applying the insulated redan, about 70% of decrease effect was observed. The effect on transient behavior was also evaluated. The conclusion of this study was directly applied to the STELLA-2 design and the modified version is under construction.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.604-607
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• 2009

The geothermal energy have been developed as the pro-environmental and the substantial long-term energy. Recently energy foundations and other thermo-active ground structures have been developed to enhance the use of geothermal energy. In this research, a tunnel wall is focused as a source of geothermal energy. If the tunnel wall can be used for geothermal source, it can provide relatively lower cost because it is not necessary to make a deep borehole like in case of closed-loop vertical ground heat exchanger. For analyzing efficiency of heat exchanger in tunnel, laboratory tests and the numerical analyses are performed.

• Transactions of the Korean hydrogen and new energy society
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• v.6 no.1
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• pp.11-16
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• 1995

Chemical heat pump is one of the energy conversion technologies, which enables to use waste heat as a source of high grade heat. In 2-propanol/acetone system, the dehydrogenation of 2-propanol is an endothermic(heat absorption) reaction, and can be used to generate hydrogen because 2-propanol can be converted to acetone and hydrogen at low temperature(about $8^{\circ}C$) using catalyst. For the dehydrogenation of 2-propanol 5% Ru catalyst based on activated carbon is the best one at the reaction temparature of $83^{\circ}C$.

• Land and Housing Review
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• v.9 no.4
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• pp.25-32
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• 2018

Application of geothermal energy in buildings has been gaining popularity as it provides the benefits of both heating and cooling a building. Among the various types of geothermal energy systems, ground-coupled heat pump system is the most commonly applied one in South Korea. A ground heat exchanger plays an important role as a heat source in winter and a heat sink in summer. For the stable operation of a ground-coupled heat pump system, a ground heat exchanger should be sized so that it provides sufficient heating and cooling energy. Heating and cooling energies generated in ground heat exchangers mainly depend on the temperature difference between the heating medium in ground heat exchangers and the surrounding ground. In addition, the performance of ground heat exchangers influences the change in ground temperature. Therefore, it is necessary to consider this interrelation between the change in the ground temperature and the performance of ground heat exchanger for an accurate estimation of its performance. However, previous thermal analysis models for ground heat exchangers are not competent enough to allow a complete understanding of this interrelation. Therefore, this study proposes a three-dimensional equivalent, transient ground heat exchanger analysis model. First, a previous thermal analysis model for ground heat exchangers, including an analytical model, a g-function, and a numerical model are analyzed. Next, to overcome the limitations of the previous models, a three-dimensional equivalent, transient ground heat exchanger model is proposed. Finally, this study validated the proposed model with the measurement data of the thermal response test, sandbox test, and TRNSYS DST model. All validation results showed a good agreement. These findings helped us to investigate the thermal performance of ground heat exchangers more accurately than the analytical models, and faster than the numerical models. Furthermore, the proposed model contributes to the design of ground heat exchangers by considering the different operation conditions of buildings.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.935-940
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• 1998

The Korea Superconducting Tokamak Research (KSTAR) tokamak will have 6 MW of radio-frequency (rf) heating in the ion cyclotron range of frequencies (ICRF). The response of the antenna to the heat loads is analyzed and the resulting stresses in the Faraday shield during the normal operation is calculated. Various heat loading conditions including in the analyzes are the heat loads from the plasma, the ripple-trapped beam particles and the rf loss.

• Journal of Bio-Environment Control
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• v.1 no.1
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• pp.14-20
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• 1992

For the high quality and low cost agricultural crops in greenhouse cultivation, it is necessary to use natural energy as much as possible. In order to reduce the fossil fuel consumption and maximize the solar energy utilization in greenhouse heating, a latent heat storage material was developed as a relatively highly concentrative solar energy storage medium. And a solar energy-latent heat storage system was designed and constructed. The experimental research on greenhouse heating effect of the system was performed.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.277-282
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• 2009

A temperature equation which is derived from an enthalpy transport equation by using an assumption of a constant specific heat is very attractive for analyses of heat and fluid flows. It can be used for an analysis of a solid-fluid conjugate heat transfer, and it does not need a numerical method to find temperature from a temperature-enthalpy relation. But its application is limited because of the assumption. A new method is derived in this study, which is a temperature-explicit formulation of the energy equation. The enthalpy form of the energy equation is used in the method. But the final discrete form of the equation is expressed with temperature. It can be used for a solid-fluid conjugate heat transfer and multiphase flows. It is found by numerical tests that it is very efficient and as accurate as the standard enthalpy formulation.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.199-204
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• 1998

To analysis the failure character of Low-Heat concrete which is used to prevent the thermal crack caused by hydration heat, static loading test was performed by this test method, "Determination of the Fracture Energy of Motar and Concrete by Means of Three-Point Band Tests on Notched Beam" (suggested by RILEM 50-FMC Committe). This study compared and analysised the fracture energy of Mode I (opening mode), the most general pattern in the view of water-cemente ratio(W/C), compressive strength and age of Ordinary Portland Concrete and Low-Heat Concrete under the same mixture. The test results show that the case of Ordinary Portland Concrete and Low-Heat Concrete, low Water-Cemente ratio(W/C) cause the increase of fracture energy, and high failure-strength decrease failure-deflection, and the fracture energy of Low-Heat Concrete is similar to Ordinary Portland Concrete as the age increase. increase.