• Economic and Environmental Geology
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• 제51권1호
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• pp.67-76
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• 2018

This study reviews three eco-friendly energy towns with hybrid thermal energy supply systems and borehole thermal energy storage (BTES) in Canada and Denmark. The district heating and cooling systems were designed by using multi-source energy for the higher efficiency and reliability as well as environment. ADEU (Alexandra District Energy Utility) located at the developing area in the city of Richmond, Canada was designed to supply district energy with the installation of 726 borehole heat exchangers (BHEs) and a backup boiler using natural gas. DLSC (Drake Landing Solar Community) located in the town of Okotoks, Canada is a district system to store solar thermal energy underground during the summer season by seasonal BTES with 144 BHEs. Brædstrup Solpark district heating system located in Denmark has been conducted energy supply from multiple energy sources of solar thermal, heat pump, boiler plants and seasonal BTES with 48 BHEs. These systems are designed based on social and economic benefits as well as nature-friendly living space according to the city based energy perspective. Each system has the energy center which distribute the stored thermal energy to each house for heating during the winter season. The BHE depth and ground thermal storage volume are designed by the heating and cooling load as well as the condition of ground water flow and thermophysical properties of the ground. These systems have been proved the reliance and economic benefits by providing consistent energy supply with competitive energy price for many years. In addition, the several expansions of the service area in ADEU and Brædstrup Solpark have been processed based on energy supply master plan. In order to implement this kind of project in our country, the regulation and policy support of government or related federal organization are required. As well as the government have to make a energy management agency associated with long-term supply energy plan.

• Journal of the Korean Vacuum Society
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• 제18권4호
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• pp.318-330
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• 2009

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to $2{\sim}3\;mm$. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of $0.2{\sim}0.5$ ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제20권1호
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• pp.278-283
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• 2019

3 kinds of fine powder, Fe-2%Ni alloy powder(N Ltd.) and Fe+2%Ni mixed powder(B Ltd. and S Ltd.), were fabricated into sintered compacts of bending strength specimens and ring type specimens by metal injection molding, debinding and controlling sintering conditions (reduction and sintering atmospheres, sintering temperature, sintering time and cooling rates). Density and magnetic properties of the sintered compacts were evaluated with the following conclusions. (1) When each compact was hold at 1123K for 3.6ks in H2 and sintered at 1623K for 14.4ks in Ar, the density of N, B and S Ltd.'s sintered compacts were measured as 96, 99 and 99%, and oxygen/carbon contents were measured as 0.0041%O/0.0006%C, 0.0027%O/0.0022%C, and 0.160%O/0.0026%C, respectively. (2) Magnetic characteristics of B Ltd. compact in Ar with the best results showed $B_{25}=14.3KG$, $B_r=7.75KG$, and $H_c=2.1Oe$, but not enough as those made by melting process. (3) Magnetic properties of B Ltd. compact which were sintered at 1673K for 14.4ks in Ar gas, and cooled at $0.83Ks^{-1}$ to 1123K and then cooled at $0.083Ks^{-1}$ down to room temperature were measured as $B_{25}=14.8KG$, $B_r=8.3KG$, and $H_c=1.3Oe$, almost similar to those made by melting process. Objected soft magnetic materials properties were obtained through sintering process by controlling sintering conditions (reduction condition, sintering atmosphere, sintering temperature and sintering time) and cooling rates.

• Journal of Climate Change Research
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• 제1권3호
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• pp.189-203
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• 2010

The objective of this study is the estimate of $CO_2$ emissions by the energy consumption of functional technology introduced by classifying energy use in households according to functions as well as energy resources. This study also intends to provide the practical basis data in order to establish specific alternatives for GHG mitigation in residential sector with examining the cause analysis affecting $CO_2$ emission increases from 1995 to 2007. The results of this study show a 6.6% increase in the total $CO_2$ from 60,636 thousand tons in 1995 to 64,611 thousand tons in 2007 by using energy in residential sector. Heating is the greatest $CO_2$ emission sector by use, followed electric appliances, cooking, lighting and cooling. Heating sector shows 56.6% reductions from 71.5% in 1995 and as do cooling and electric home appliances, with a 2.4% increase from 0.6% and a 21.8% increase from 14.2% respectively. To analyze factors resulted in $CO_2$ emissions in residential sector, the relevant indicator change rate from 2005 to 2007 was examined. The results find that population, the number of household, housing areas, family patterns, and family income resulted in the $CO_2$ emissions increase in residential sector from 1995 to 2007. On the other hand, carbon intensity and energy intensity contribute to $CO_2$ reduction in residential sector with -2% and -38.7% respectively because of the energy conversion and the improvement of energy efficiency in electronic appliances. This study can be used as a reference when taken account of the reality and considered the introduction of highly effective measures to increase the possibility of mitigation potential in residential sector hereafter.

• Transactions of the KSME C: Technology and Education
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• 제3권4호
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• pp.241-248
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• 2015

Most of the Stirling cryocoolers used for infrared detector cooling in domestic is imported. Because the cooler has a high price, short life and poor durability, demand for the coolers continues steadily. However, the cooler is highly related to defense and space technology, technology transfer or co-development with the countries having experties in cooler design is very limited. The pulse tube cooler to be developed in this study is such that the mechanical piston in low temperature actuating part is replaced by the gas piston and linear compressor is adopted, which results in low vibration, long life and better durability. It is expected that development of the pulse tube cooler will not only improve our technology to the level of advanced countries, but also enhance the skills in designing and manufacturing of the infrared detector.

• Fire Science and Engineering
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• 제34권2호
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• pp.147-155
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• 2020

This paper presents a study on the development of a fire extinguishing agent and extinguishing system for an energy storage system (ESS) fire. The fire extinguishing agent designed to extinguish an ESS fire is a highly permeable fire extinguisher that reduces the surface tension and viscosity while bringing about cooling action. This is the main extinguishing effect of this type of wetting agent, which displays the characteristics of fire extinguishing agents used for penetrating the battery cells inside the ESS module. For the fire extinguishing system, a local application system was designed to suppress fire on a rack-by-rack basis. A 360° rotating nozzle was inserted into the rear hall of the ESS module, and general nozzles were installed in the rack to maximize the fire extinguishing effect. The fire extinguishing agent was strongly discharged by virtue of the gas release pressure. Experiments on fire suppression performance with ESS module 1 unit and module 3 units showed that all visible flames were extinguished in 8 s and 9 s, respectively, by the fire extinguishing agent. In addition, based on confirming reignition for 600 s after the fire extinguishing agent was exhausted, it was confirmed that the ESS fire was completely extinguished without reignition in all fire suppression performance experiments.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.644-651
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• 2011

Storing hydrogen in solid state hydride is one of the best promising methods for the future hydrogen economy. The total performance of such systems depends on the rate at which the amount of mass and heat migration is supplied to solid hydride. Therefore, an accurate modeling of the heat and mass transfer is of prime importance in optimizing the design of such systems. In this work, Hydrogen storage in Pt-CNTs hydrogen reactor has been intensively investigated by solving 2 dimensional mathematical models. Using a CFD computer software, systematic studies have been performed to elucidate the effect of heat and mass transfer during hydrogen charging periods. It was revealed that the optimized design of hydrogen storage vessel can prevent the increase of system temperature and the charging time due to the convective cooling effects inside the vessels at even high charging pressure. Because none has reported the critical issues of heat and mass transfer for CNT based hydrogen storage system, this work can support the first insight of the optimal design for solid state hydrogen storage system based on CNT in the near future.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제34권6호
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• pp.587-597
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• 2010

Air-staged combustion is known to be one of the techniques of NOx reduction. The objective of this study is to determine the optimal ratio of air flow distributed for CCOFA and SOFA; at this optimal ratio, the combustion and exhaust emission characteristics of a pulverized coal-fired boiler are maintained at a satisfactory level. A numerical investigation was performed at various airflow ratios of 16.7/83.3%, 25/75%, 50/50%, 75/25%, and 83.3/16.7%. An inert gas was considered as a substitute for air to isolate the effects of the cooling process and chemical reaction on NOx reduction; during NOx reduction in air-staged combustion, both the effects typically occur simultaneously. The results of our study show that the optimum condition, under which the maximum NOx reduction and highest boiler efficiency can be obtained, corresponds to the equal splitting of the over-fire air between CCOFA and SOFA.

• Journal of Advanced Marine Engineering and Technology
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• 제8권1호
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• pp.17-36
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• 1984

Since 1973, the competition on the development of fuel saving type internal combustion engines has become severe by the two times oil shock, and new type engines are reported every several months. Whenever these new type engines are developed, new designs are required and they will be offered in the market after performing the endurance test for a long time. But the engine market is faced with a heavy burden of finance, as the developing of a new engine requires tremendous expenses. For this reason, the computer simulation method has been lately developed to cope with it. The computer simulation method can be available to perform the reasonable research works by the theoretical analysis before carrying out practical experiments. With these processes, the developing expenses are cut down and the period of development is curtailed. The object of this study is the development of simulation computer program for the small naturally aspirated four-stroke diesel engine which is intended to product by the original design of our country. The process of simulation is firstly investigated for the ideal engine cycle, and secondly for the real engine cycle. In the ideal engine cycle, each step of the cycle is simulated by the energy balance according to the first law of thermodynamics, and then the engine performance is calculated. In the real cycle imulation program, the injection rate, the preparation rate and the combustion rate of fuel and the heat transfer through the wall of combustion chamber are considered. In this case, the injection rate is supposed as constant through the crank angle interval of injection and the combustion rate is calculated by the Whitehouse-Way equation and the heat transfer is calculated by the Annand's equation. The simulated values are compared with measured values of the YANMAR NS90(C) engine and Mitsubishi 4D30 engine, and the following conclusions are drawn. 1. The heat loss by the exhaust gas is well agree with each other in the lower load, but the measured value is greater than the calculated value in the higher load. The maximum error rate is about 15% in the full load. 2. The calculated quantity of heat transfer to the cooling water is greater than the measured value. The maximum error rate is about 11.8%. 3. The mean effective pressure, the fuel consumption, the power and the torque are well agree with each other. The maximum error is occurred in the fuel consumption, and its error rate is about 7%. From the above remarks, it may be concluded that the prediction of the engine performance is possibly by using the developed program, although the program needs to reform by adding the simulation of intake and exhaust process and assumping more reliable mechanical efficiency, volumetric efficiency, preparation rate and combustion rate.

• Journal of Energy Engineering
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• 제8권2호
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• pp.242-247
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• 1999

The characteristics of waste heat effluents from 11 industrial complexes of 7 areas were analyzed to investigate the possibility of waste heat recovery of huge amount of waste heat producing from various industrial complexes. This study presents a part of the research work for the industrial waste heat for development of energy integrated network system in broad city area, which will utilize industrial waste heat for residential and commercial areas, where they are located at some distances from the complexes. The amount of waste heat from the investigated complexes was detected as 148,913 TOE/year. However, It was analyzed 83% of the waste heat was analyzed the temperature range from 0$^{\circ}C$ to 200$^{\circ}C$. Also, it was evaluated that 82% of waste heat was exhausted by flue gases. Especially, the characteristics of waste heat for the areas where most heat concentrated, such as Tae-gu industrial complex, Ul-san petrochemitry complex, Yio-chun petrochemistry complex, and Chun-ju industrial complex were investigated more precisely. Total amount of waste heat discharged from these four areas were analyzed 114,402 TOE/year, which was occupied as 77% of the total waste heat for the studied areas, and 87% of the waste heat from the industries was exhausted by flue gaseous phase and temperature range was from 0$^{\circ}C$ to 200$^{\circ}C$ 18.1 million TOE/year waste heat was released from the fossil fuel power plants, however 95% of waste heat was analyzed as cooling water from surface condensers at power plants. The temperature range was measured from 27$^{\circ}C$ to 34$^{\circ}C$, which are unable to utilize due to its low temperature. Otherwise, 5% (894,800 TOE/year) waste heat released from power plants were observed as flue gas, which temperature ranged from 90$^{\circ}C$ to 170$^{\circ}C$.