• 제목/요약/키워드: Fuel flow control

검색결과 385건 처리시간 0.024초

Numerical investigation of the high pressure selective catalytic reduction system impact on marine two-stroke diesel engines

  • Lu, Daoyi;Theotokatos, Gerasimos;Zhang, Jundong;Tang, Yuanyuan;Gan, Huibing;Liu, Qingjiang;Ren, Tiebing
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제13권1호
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    • pp.659-673
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    • 2021
  • This study aims to investigate the impact of the High Pressure Selective Catalytic Reduction system (SCR-HP) on a large marine two-stroke engine performance parameters by employing thermodynamic modelling. A coupled model of the zero-dimensional type is extended to incorporate the modelling of the SCR-HP components and the Control Bypass Valve (CBV) block. This model is employed to simulate several scenarios representing the engine operation at both healthy and degraded conditions considering the compressor fouling and the SCR reactor clogging. The derived results are analysed to quantify the impact of the SCR-HP on the investigated engine performance. The SCR system pressure drop and the cylinder bypass valve flow cause an increase of the engine Specific Fuel Oil Consumption (SFOC) in the range 0.3-2.77 g/kWh. The thermal inertia of the SCR-HP is mainly attributed to the SCR reactor, which causes a delayed turbocharger response. These effects are more pronounced at low engine loads. This study supports the better understanding of the operating characteristics of marine two-stroke diesel engines equipped with the SCR-HP and quantification of the impact of the components degradation on the engine performance.

고리1호기 계통제염을 위한 원자로냉각재내 유동 특성 평가 (Flow Characteristics Evaluation in Reactor Coolant System for Full System Decontamination of Kori-1 Nuclear Power Plant)

  • 김학수;김초롱
    • 방사성폐기물학회지
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    • 제16권3호
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    • pp.389-396
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    • 2018
  • 국내 가동원전 중 2-루프 가압경수로인 고리1호기는 약 40년 운전한 후, 2017년 6월 18일 영구정지되었다. 영구정지된 고리 1호기는 주요 해체작업을 수행하기전에 계통내 선량률을 저감시켜 작업자피폭을 최소화하기 위한 계통제염을 수행할 예정이다. 일반적으로, 계통제염 범위는 원자로압력용기, 가압기, 증기발생기, 화학 및 체적제어계통, 잔열제거계통 및 원자로 냉각재계통 주요배관을 포함한다. 이러한 계통 및 기기 등을 효율적으로 제염하기 위해서는 제염과정에서 원자로냉각재계통내 유동특성을 평가할 필요가 있다. 계통제염을 위해 순환유량을 제공하는 방법은 다양하나, 본 논문에서는 잔열제거펌프 운전에 따른 고리1호기 원자로냉각재계통내 유동특성을 평가하였다. 잔열제거펌프를 이용한 계통제염은 원자로냉각재 내 유량의 불균형을 초래하여 계통내 기기 및 배관 등에 불순물을 침적시켜 제염이 효율적이지 않다는 것으로 평가되었다.

Feasibility Study on Long-Term Continuous Ethanol Production from Cassava Supernatant by Immobilized Yeast Cells in Packed Bed Reactor

  • Liu, Qingguo;Zhao, Nan;Zou, Yanan;Ying, Hanjie;Liu, Dong;Chen, Yong
    • Journal of Microbiology and Biotechnology
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    • 제30권8호
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    • pp.1227-1234
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    • 2020
  • In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

석탄 노즐내 미분탄 분리장치의 입자 분리 효과에 관한 실험적 연구 (An Experimental Study on the Separating Effect of Pulverized Coal at Coal Nozzle with Coal Separator)

  • 김혁제;송시홍;이건명;김상현;이익형
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.764-769
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    • 2001
  • Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutant emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle. Basically, a mixed flow of gas and particle in coal nozzle is required to have appropriate injection and concentration distribution at exit to achieve flame stability and low pollutant, but it is very difficult to obtain that without help of a coal separating device within nozzle. In this study, each distribution of air and coal flow rate is measured for the coal nozzle with coal separator developed by us. The coal concentration at exit is various according to inlet swirl values and positions of coal separator. Also pressure drop is measured for various operating conditions of this nozzle. From these results, we can find the separation characteristic of new developed coal separator, and select proper operation range of coal nozzle. When this coal nozzle is applied to actual plant, these investigations will be very useful to confirm the shape of coal separator to have efficient particle injection.

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Ro-Ro 구역용 미분무 소화설비의 개발을 위한 실험적 연구 (An experimental study on development of water mist fire-fighting systems for Ro-Ro spaces)

  • 곽지현;김영한
    • Journal of Advanced Marine Engineering and Technology
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    • 제37권8호
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    • pp.946-952
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    • 2013
  • 선박의 Ro-Ro 구역이나 특별범주구역의 화재방호를 위해 설치하는 고정식 수계소화설비의 개발 및 실용화를 위해, 특히 방수량이 적으며 관련기준에서 요구하는 성능요건을 만족하는 미분무 노즐을 개발하고자 실물화재실험을 수행하였다. 본 설비의 화재시나리오는 크게 두 가지로 트럭화물화재와 승용차화재로 구분되며, 각각 고정 설치된 미분무 노즐과 화원과의 세 가지 위치에 대한 시나리오로 이루어져 있다. 모든 화재실험은 30분간 진행되었으며 천장부의 가스온도와 우드펠릿의 손상율, 타깃합판의 착화여부로 판단되었다. 본 논문은 두 가지 화재실험 중 조건이 더욱 까다로운 트럭화재용 미분무 노즐의 결과를 위주로 방수압력과 방수량, 미분무수의 유동특성에 따른 화재실험결과와 화재진압특성을 고찰하였으며, 수십 회의 반복실험 결과 분당 약 40 L의 유량을 가지는 저압 미분무 노즐로 Ro-Ro구역의 화재진압이 가능한 것으로 나타났다.

화장로 형상 최적화를 통한 에너지효율개선을 위한 실증연구 (Field Scale Study for Energy Efficiency Improvement of Crematory System by the Shape Optimization of Combustion Chamber)

  • 원용태;이승목
    • 공업화학
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    • 제30권5호
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    • pp.546-555
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    • 2019
  • 본 연구는 국내 화장로 설비의 주류를 이루는 대차방식 화장로의 성능개선을 목표로 하였다. 주연소실 형상 변화를 통해 용적을 증대시키고, 버너연소제어 최적화를 통한 화장시간 단축 및 에너지 사용량 절감기술을 실증설비 기반으로 연구하였다. 1차적으로 열유동해석을 통해 최적화된 구조설계로 주연소실의 체적을 약 70% 증대시키므로 연소배가스의 체류시간이 증대되는 효과를 얻을 수 있었고, 이를 통해 설계한 파이로트 화장로를 제작하여 다양한 운전조건에서 연소거동을 실험하고 주연소실 형상별 최적의 운전방안을 도출하였다. 이렇게 도출된 결과를 반영하여 실증 화장로를 설계하고, P시 Y화장장에 설치하였다. 실증 화장로 조업을 통해 최적 연소조건을 도출할 수 있었고, 고온의 연소배가스의 체류시간 증대에 따른 에너지 효율의 증대효과로 기존대비 화장시간 및 연료사용량을 최소화할 수 있었다. 즉, 화장시간은 기존 화장로 조업대비 44.1% 단축된 38 min이었고, 연료사용량은 기존 화장로 대비 54.4% 절감된 $21.8Nm^3$이었다.

설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제29권6호
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Aerodynamic control capability of a wing-flap in hypersonic, rarefied regime: Part II

  • Zuppardi, Gennaro;Vangone, Daniele
    • Advances in aircraft and spacecraft science
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    • 제4권5호
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    • pp.503-514
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    • 2017
  • The attitude control of an aircraft is usually fulfilled by means of thrusters at high altitudes. Therefore, the possibility of using also aerodynamic surfaces would produce the advantage of reducing the amount of fuel for the thrusters to be loaded on board. For this purpose, Zuppardi already considered some aerodynamic problems linked to the use of a wing flap in a previous paper. A NACA 0010 airfoil with a trailing edge flap of 35% of the chord, in the range of angle of attack 0-40 deg and flap deflections up to 30 deg was investigated. Computer tests were carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km of Earth Atmosphere. The present work continues this subject, considering the same airfoil and free stream conditions but two flap extensions of 45% and 25% of the chord and two flap deflections of 15 and 30 deg. The main purpose is to compare the influence of the flap dimension with that of the flap deflection. The present analysis is carried out in terms of: 1) percentage variation of the global aerodynamic coefficients with respect to the no-flap configuration, 2) increment of pressure and heat flux on the airfoil lower surface due to the Shock Wave-Shock Wave Interaction (SWSWI) with respect to the same quantities with no SWSWI or in no-flap configuration, 3) flap hinge moment. Issues 2) and 3) are important for the design of the mechanical and thermal protection system and of the flap actuator, respectively. Under the above mentioned test and geometrical conditions, the flap deflection is aerodynamically more effective than the flap extension, because it involves higher variation of the aerodynamic coefficients. However, tests verify that a smaller deflection angle involves the advantage of a smaller increment of pressure and heat flux on the airfoil lower surface, due to SWSWI, as well as a smaller hinge moment.

설비공학 분야의 최근 연구 동향 : 2007년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2007)

  • 한화택;신동신;최창호;이대영;김서영;권용일
    • 설비공학논문집
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    • 제20권12호
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    • pp.844-861
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    • 2008
  • The papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during the year of 2007 have been reviewed. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro nano fluid, micropump and fuel cell. Traditional CFD was still popular and widely used in research and development. Studies about fans and pumps were performed in the field of fluid machinery. Characteristics of flow and fin shape optimization are studied in the field of piping system. (2) The research works on heat transfer have been reviewed in the field of heat transfer characteristics, heat exchangers, and desiccant cooling systems. The research on heat transfer characteristics includes thermal transport in pulse tubes, high temperature superconductors, ground heat exchangers, fuel cell stacks and ice slurry systems. For the heat 'exchangers, the research on pin-tube heat exchanger, plate heat exchanger, condensers and gas coolers has been cordially implemented. The research works on heat transfer augmenting tubes have been also reported. For the desiccant cooling systems, the studies on the design and operating conditions for desiccant rotors as well as performance index are noticeable. (3) In the field of refrigeration, many papers were presented on the air conditioning system using CO2 as a refrigerant. The issues on the two-stage compression, the oil selection, and the appropriate oil charge were treated. The subjects of alternative refrigerants were also studied steadily. Hydrocarbons, DME and their mixtures were considered and various heat transfer correlations were proposed. (4) Research papers have been reviewed in the field of building facilities by grouping into the researches on heat and cold sources, air conditioning and air cleaning, ventilation and fire research including tunnel ventilation, flow control of piping system, and sound research with drain system. Main focuses have been addressed to the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies were mostly focused on analyzing the indoor environment in various spaces like cars, old tombs, machine rooms, and etc. in an architectural environmental field. Moreover, subjects of various fields such as the evaluation of noise, thermal environment, indoor air quality and development of energy analysis program were researched by various methods of survey, simulation, and field experiment.

가연성 건설폐기물의 자원화 제고를 위한 방안 (A Study on the Promotion of Combustible Construction Waste Recycling)

  • 박지선;이세현
    • 한국건설순환자원학회논문집
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    • 제4권1호
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    • pp.89-95
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    • 2009
  • 현행 "건설폐기물의 재활용 촉진에 관한 법률" 시행령 별표1에서는 다양한 성상으로 배출되는 건설폐기물의 종류를 17가지로 구분하고 이중 제17호의 혼합폐기물은 건설폐토석을 제외한 나머지 15가지 성상의 건설폐기물중 둘 이상의 건설폐기물이 혼합된 것으로 정의하고 있다. 이중 폐콘크리트, 폐아스콘과 같은 건설폐재류는 대부분이 순환골재와 같이 재활용되고 있으며 폐금속과 같은 유가성 자재류는 대부분 분리 판매되어 2차 제품 제조등에 활용되고 있다. 그러나 폐목재, 폐합성수지, 폐섬유 등과 같은 가연성 폐기물의 경우 발열량이 높고 인체에 해로운 중금속 함유량이 적어 RDF나 RPF와 같은 에너지 연료로 활용이 가능하지만 상당량이 혼합폐기물 형태로 배출되어 단순 소각 및 매립되고 있는 실정이다. 그러므로 본 연구에서는 단순하게 외관상의 분류만을 고려하여 설정한 현행 "건폐법"과는 달리 최초 발생단계에서부터 최종처리까지 건설폐기물의 흐름을 보다 효율적으로 제어할 수 있도록 건설폐기물의 분류를 크게 가연성, 불연성, 가연성 불연성 혼합, 기타 등으로 분류하였다. 가연성 폐기물의 경우 기존의 소각 폐기물을 중심으로 폐목재, 폐섬유 등 기존의 소각 폐기물을 중심으로 분류를 하고 불연성은 재활용이 원활한 건설폐재류와 기타로 구분, 혼합건설폐기물은 발생 자체부터 서로 다른 물질이 결합되어 있어 분리 자체가 어려운 폐기물을 대상으로 하였다. 또한 이상에서 폐기물은 지정폐기물을 제외하고 모든 기타 폐기물로 분류하도록 하였으며 기본적으로 건설현장에서 발생하는 폐기물은 1차적으로 가연성, 불연성, 혼합폐기물로 분류하여 배출하는 시스템이 되도록 폐기물의 분류를 실시하였다.

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