• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1530-1535
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• 2003

The utilization of unused energy is important because it can afford to offer a chance to increase energy efficiency of a heat pump system. One of the promising unused energy sources is river water. It can be used as a heat source in both heating and cooling effectively with its superior features as a secondary working fluids. In this study, the performance of a 5HP heat pump system using river water as a heat source is investigated by both experiment and simulation. According to system simulation results, performance improvement of condenser seems more effective than that of evaporator for better $COP_H$. The serial connection is also preferred among several methods to improve plate type heat exchanger performance. The experimental results show that the hot water of $50{\sim}60^{\circ}C$ can be acquired from water heat source of $5{\sim}9^{\circ}C$ with $COP_H$ of $2.7{\sim}3.5$.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.11-16
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• 2010

Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity and each other from physically-bond at specially temperature and pressure condition. $1m^3$ of methane hydrate can be decomposed into the maximum of $216m^3$ of methane gas under standard condition. If these characteristics of hydrate are utilized in the opposite sense, natural gas can be fixed into water in the form of a hydrate solid. Therefore the use of hydrate is considered to be a great way to transport and store natural gas in large quantity. However, when methane hydrate is formed artificially, the amount of gas that is consumed is relatively low, due to the slow reaction rate between water and methane gas. Therefore for practical purposes in the application, the present investigation focuses on increasing the amount of gas consumed by adding chemically oxidized OMWCNTs to pure water. The results show that when 0.003 wt% of oxidation multi-walled carbon nanotubes was added to pure water, the amount of gas consumed was almost four times more than that of pure water indicating its effect in hydrate formation and the hydrate formation time decreased at alow subcooling temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1776-1783
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• 2001

Heat recovery from boiler exhaust gas with multi-stage water-fluidized-bed heat exchanger is analyzed in this study. The recovered energy here is not only sensible heat but also latent heat contained in the exhaust gas. In this system direct contact heat transfer occurs while exhaust gas passes through water bed and the thermal energy recovered this way is again delivered to the water circulating through heat exchanging pipes within the bed. Thus the thermal energy of exhaust gas can be recovered as a clean hot water. A computer program developed in this study can predict the heat transfer performance of the system. The results of experiments performed in this study agree well with the calculated ones. The heat and mass transfer coefficients can be fecund through these experiments. The performance increases as the number of stage increases. However at large number of stages the increasing rate becomes very low.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1062-1067
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• 2015

Floating architecture is a type of building that is geographically located on a sea or a river. It floats under the influence of buoyancy, and does not have an engine for moving it. Korea is a peninsula surrounded by sea except on the north side, so floating architectures have been mainly focused on two points: solving the issue of small territory and providing various leisure & cultural spaces. Floating architectures are expected to save energy effectively, if they use sea water heat, which is known to be clean energy with infinite reserves. To use sea water heat as the heat source and/or heat sink, this study proposes a model in which a sea water heat exchanger is embedded in the concrete structure in the lower part of the floating architecture that is submerged under the sea. Based on the results of performance evaluations of the sea water heat exchanger using CFD (computational fluid dynamics) analysis and mock-up experiments under various conditions, it is found out that the temperature difference between the inlet and outlet of the heat exchanger is in the range of $3.06{\sim}9.57^{\circ}C$, and that the quantity of heat transfer measured is in the range of 3,812~7,180 W. The CFD evaluation results shows a difference of 5% with respect to the results of mock-up experiment.

• KIEAE Journal
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• v.7 no.5
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• pp.81-86
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• 2007

The research analyzes the arrangement of boiler and hot water header, the method of radiator pipe setting, hot water supply control, hourly heating situation of each room for underfloor radiant heating systems in Korea and suggests an alternative to improve to efficient heating method. One of the best options for install position of hot water distributor is under kitchen sink which is center point of all rooms, according to previous research of the energy saving strategies. When the radiator pipes are arranged to each individual room instead of bedrooms through livingroom and kitchen, it has energy saving effects. For rooms without occupancy according to a time period, hot water supply method should be intermittent heating rather than continuous heating. For this intermittent heating method, individual control of hot water supply is more practical, and it can lead to massive energy savings. The intermittent heating system has time-lag, so it is more effective in energy saving with mild and comfort condition if the spaces are preheated by automatic control equipment prior to required time.

• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.14-26
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• 2024

Global efforts continue with the goal of transition to a "carbon neutral (net zero)" society with zero carbon emissions by 2050. For this purpose, the technology of water electrolysis is being developed, which can store electricity generated from renewable energies in large quantities and over a long period of time as hydrogen. Recently, various research and large-scale projects on 'green hydrogen', which has no carbon emissions, are being conducted. In this paper, a comparison of water electrolysis technologies was carried out and, based on data provided by the International Energy Agency (IEA), large-scale water electrolysis demonstration projects were analyzed by classifying them by technology, power supply, country and end user. It is expected that through the analysis of large-scale water electrolysis demonstration projects, research directions and road maps can be provided for the development/implementation of commercial projects in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 1992.07a
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• pp.383-396
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• 1992

본 연구는 조력을 검토하고 그 포장력을 Energy로 사용할 수 있도록 연구 고안함에 있어 각종 Energy의 추출방법을 분석, 비교, 검토하여 새로운 방법의 연구와 실질적 이론과 위치변동에 의한 수력을 분석하고 과거에 전연사용하지 않았던 새로운 Energy를 연구개발하여 우리 인류가 사용하기에 편리하도록 분명한 이론을 정립한 것이 특징이다. 본 연구는 다음과 같이 증명이 되었다. 1. 조력발전의 방법은 여러 조건의 방향이 있을 수 있다. 2. 현재까지의 방법중에는 중력 및 부력을 이용한 방법이 가장 유능한 방법이었다. 3. 조력발전의 중력 및 부력발전에 있어 Energy를 투입함으로 생성되는 신 Energy의 강력한 결과를 증명하였다. 4. 그러한 Energy는 해면 1m2당 1일 300ton/m 이상의 Energy를 얻을 수 있는 방법을 고안했다. 5. 이러한 Energy는 우리나라 조력해면 60,000km2에서 평균 7억KWH 이상의 상시출력발전을 할 수가 있고 70만 KWH원자력발전소 1,000기와 같은 대용량의 Energy가 개발이 될 수가 있다. 본 연구는 수문학에 있어 위치변동에 의한 수면운돌을 중력과 부력에 의하여 많은 힘을 얻게하고 자연 Energy를 투입하여 더욱 증대된 강력한 Energy를 획득하는 연구분야의 문을 열었다는 데에 그 의의가 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.129-130
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1088-1089
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• 2005

• Journal of Korea Water Resources Association
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• v.33 no.S1
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• pp.465-470
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• 2000