• 한국지열·수열에너지학회논문집
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• 제10권3호
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• pp.8-16
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• 2014

Heating and hot water supply energy consumption of medium and multi boiler systems applied to military officer housing are compared with in-situ experiment and TRNSYS dynamic simulation program. In a multiple boiler system, small capacity boilers are connected in parallel to meet the required capacity. For handling partial loads, medium capacity boiler relies on on-off control, while multi boiler adopts PI control. Since multi boiler has higher efficiency and better control strategy, the results show that energy consumption can be reduced significantly with the multi boiler system.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.452-459
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• 2010

This study is aimed to investigate changes of combustion characteristics and heat efficiency when syngas from gasification process using low-rank fuel such as waste and/or biomass is applied partially to an industrial boiler. An experimental study on syngas co-combustion was performed in a 0.7 MW (1 ton steam/hr) water tube boiler using heavy oil as a main fuel. Three kinds of syngas were used as an alternative fuel: mixture gas of pure carbon monoxide and hydrogen, syngas of low calorific value generated from an air-blown gasification process, and syngas of high calorific value produced from an oxygen-blown gasification process. Effects of co-combustion ratio (0~20%) for each syngas on flue gas composition were investigated through syngas injection through the nozzles installed in the side wall of the boiler and measuring $O_2$, $CO_2$, CO and NOx concentrations in the flue gas. When syngas co-combustion was applied, injected syngas was observed to be burned completely and NOx concentration was decreased because nitrogen-containing-heavy oil was partially replaced by the syngas. However, heat efficiency of the boiler was observed to be decreased due to inert compounds in the syngas and the more significant decrease was found when syngas of lower calorific value was used. However, the decrease of the efficiency was under 10% of the heat replacement by syngas.

• 한국분무공학회지
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• 제28권1호
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• pp.43-48
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• 2023

The waste-heat-recovery boiler with water spray (HR-B/WS) applies the heat exchange between the inlet air and exhaust gas with the water spray into the inlet air. The evaporation of water in the inlet air promotes heat recovery from the exhaust gas so that thermal efficiency can be improved by the enhanced condensing effect. The NOx emission can also be reduced by lowering the flame temperature due to the dilution effect of the water. In this study, the validity of this concept is examined by the practical boiler test performed with a 24 kW condensing boiler under the full load condition according to the water injection amount. The theoretical amount of water injection is calculated under the assumption of full evaporation of the sprayed water, which is calculated as 50 g/min. Since the injected water cannot evaporate fully in the actual system, the maximum water spray amount is set as 100 g/min. The results showed that the water injection can increase the thermal efficiency up to 95.59% and reduce NOx and CO emissions simultaneously to 8.9 ppm and 35 ppm at 0% of O₂. Although the heat energy loss increased due to the unevaporated water, the increase in water injection amount caused higher thermal efficiency due to the increased amount of the evaporated water.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.476-482
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• 2019

본 기후변화협약, 온실가스배출규제와 같은 규제적 규약들은 고효율 에너지 기자재 개발과 에너지의 효율적 이용을 촉진하는 촉매로 작용하고 있다. 에너지소비가 큰 분야 중 전열기기가 효율이 좋지 못한 편이다. 전기보일러는 히터에 물을 접촉시켜 순환시키는 방식을 주로 사용하고 있다. 기존 전기보일러를 활용할 경우 물의 미네랄이 고온의 히터와 접촉하여 탄화되어 흡착되는 과정에서 히터의 부식을 촉진시키고 히터의 효율을 저하시킨다. 이러한 이유로 에너지 효율이 높고, 전도나 대류가열보다 피가열물을 균일하게 가열시킬 수 있는 유도가열방식을 보일러에 적용시킨 전기유도보일러가 각광을 받고 있는데, 이 방식은 물이 담겨 있는 보일러 관로를 유도가열방식으로 가열하여 직접가열시 발생하는 문제를 해결시킬 수 있는 대안으로 인정받고 있다. 비교적 오랜 기간 유도가열에 대한 연구가 이루어졌음에도 불구하고 유도가열을 이용한 전열기술에 대한 연구결과는 그리 많지 않은 실정이다. 따라서 본 논문에서는 전기유도보일러의 발열효율을 개선하기 위하여 매개변수연구방법을 통하여 권선의 단면적, 권선의 수 및 권선의 겹수에 의한 영향을 유한요소법을 이용하여 해석하고 발열의 요소가 되고 있는 동손과 철손을 분석하여 발열을 극대화시킬 수 있는 권선설계방법으로 총손실이 최대가 되는 설계점을 찾는 방법을 제시하였다.

• 에너지공학
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• 제23권3호
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• pp.211-220
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• 2014

본 연구에서는 목재펠릿의 연소 시 발생되는 타르, 재, 클링커의 생성 특성 분석과 더불어, 1등급 목재펠릿의 함수율에 따른 목재펠릿보일러의 성능 분석이 수행되었다. 타르는 목재펠릿이 연소됨에 따라 생성되어 연소실 전열면에 부착되었고, 전열면에 부착되거나 배기가스와 함께 배출되지 못한 재의 경우, 바닥면에 축적되었으며, 클링커는 3등급 목재펠릿의 연소 중에 버너부에서 생성, 고형화되는 것으로 나타났다. 목재펠릿의 등급이 결정되는 요인으로써 함수율은 중요한 요인으로 작용된다. 벌채부산물을 이용한 목재펠릿은 불균일한 함수율로 인해, 연소 생성물의 발생량이 증가되는 경향을 나타내었으며, 이에 따른 연소시스템에서의 효율 저하, 시스템 작동 오류 등의 문제점이 발생되었다. 특히, 목재펠릿의 함수율에 따른 목재펠릿보일러의 성능 분석에서, 1등급 목재펠릿의 함수율이 6.6%p 증가하였을 때, 보일러효율이 약 27.08%p 감소되는 것으로 나타났다.

• 한국분무공학회지
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• 제26권2호
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• 한국지열·수열에너지학회논문집
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• 제11권3호
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• pp.13-19
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• 2015

This study was aimed at the heating tank with a screw-rotation device for improving the thermal efficiency of electric boiler. In the proposed system, analysis items were the heater rod surface temperature variation, reaching time for set temperature and thermal efficiency. The following conclusions are obtained from this experimental study. (1) When screw speed increases, the time reaching for set temperature tended to be shorter. (2) When the rotation speed becomes 300 rpm, the surface temperature difference between the right and left heater rod decreases by 49%, from $19.7^{\circ}C$ to $9.7^{\circ}C$ in average. (3) When the rotation speed is over 250 rpm, proposed heating tank structure appeared to be effective in terms of thermal efficiency. Thermal efficiency with the rotation speed 300 rpm is improved by 3.8% compared to the case of rotation speed 0 rpm.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.260-264
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• 2003

The application of solar energy, in the field of alternative energy, was on the increase tendency. In the case of advanced nations, through continuous R&D, solar-heat hot-water-boiler with high efficiency has been used for the house and the industrial process on business, advanced nations on reached up the experimental stage of solar generation system. But the actual circumstance of the domestic has been not accomplished the popularization of solar-heat hot-water-boiler and the settlement of it which is the fundamental stage of the solar energy usage. This trouble, the domestic was flooded with small enterprise for producing solar-heat hot-water-boiler, was caused by the popularization and the production without verification of performance. To supply the monitoring program for evaluating solar-heat hot-water-boiler, this research was purpose to improve the technical development of the enterprise for producing solar-heat hot-water-boiler and served as an aid f3r the enlargement and the popularization on solar energy.

• 동력기계공학회지
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• 제8권3호
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• pp.18-22
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• 2004

Boiler is one of the most important utilities providing steam to turbine in order to supply mechanical energy in thermal power plant. It is composed of thousands of tubes for high efficient heat transfer. The material for boiler tubes is used in such high temperature and pressure condition as $540^{\circ}C$, 22MPa. The boiler tube material is required to resist creep damage, fatigue cracking, and corrosion damages. 2.25%Cr-1Mo steel is used for conventional boiler tubes, and austenitenite stainless steel is used for higher temperature boiler tubes. But the temperature and pressure of steam in power plant became higher for high plant efficiency. So, the property of boiler tube material must be upgaded to fit the plant property. Several boiler tube material was developed to fit such conditions. X20CrMoV12.1 steel is also developed in 1980's and used for superheater and reheater tubes in supercritical boilers. The material has martensite microstructures which is difficult to evaluate the degradation. In this thesis, degrade the X20CrMoV12.1 steel at high temperatures in electric furnace, and evaluate hardness with Vickers hardness tester and strengths with Indentation tester.

• Journal of Forest and Environmental Science
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• 제23권2호
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• pp.79-85
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• 2007

This survey was carried out to investigate the utilization situation of fire-wood boiler by the questionnaire and personal interview on rural and mountain households of Gangwon province from 1998 to 2005. The questionnaire include 7 questions on installation, 7 questions on fuel, 3 questions on use, and 3 questions on improvement. Each question was analyzed by percentage to investigate the use situation. This survey indicated that the general problems in use of fire-wood boiler are fuel purchase, collection and transportation, that the development of the household heating boiler using wood-based forming fuel which is cheap, small volume, easy handling, convenient purchase and high heat efficiency could be an alternative to improve the problems and that the continuous expansion of the supply of fire-wood boiler can prevent the devastation of forest through the regulation of imprudent fuel supply. Although the financial aid plan on the installation of fire-wood boiler is in active, many petty households in rural and mountain areas lose a chance to install the fire-wood boiler due to the unsatisfactory information. Thus, it will be desirable for municipal government to prepare the information plan to offer the equal chance and condition to all households in rural and mountain areas and to increase the financial aid for the continuous supply of fire-wood boiler.