가솔린 엔진의 흡기밸브 리프트 변화에 따른 개별실린더 당량비 추정 및 제어 알고리즘에 관한 연구

김준수(Junsoo Kim),오승석(Seungsuk Oh),이민광(Minkwang Lee),선우명호(Myoungho Sunwoo) 한국자동차공학회 2011 한국 자동차공학회논문집 Vol.19 No.5

In a spark ignition engine, a variable valve lift (VVL) system has been developed for high fuel efficiency and low power loss. However, changes in valve lift cause deviations of cylinder air charge which lead to individual cylinder equivalence ratio maldistribution. In this study, in order to reduce the maldistribution, we propose individual cylinder equivalence ratio estimation and control algorithms. The estimation algorithm calculates the equivalence ratio of each cylinder by using a mathematical engine model which includes air charging, fuel film, exhaust gas, and universal exhaust gas oxygen sensor (UEGO) dynamics at various valve lifts. Based on the results of estimated equivalence ratio, the injection quantity of each cylinder is adjusted to control the individual cylinder equivalence ratio. Estimation and control performance are validated by engine experiments. Experimental results represented that the equivalence ratio maldistribution and variation are decreased by the proposed algorithms.

바이오디젤 연료 압축착화 엔진의 당량비 변화가 연소 및 배출물특성에 미치는 영향

강민구(Mingu Kang),권석주(Seokjoo Kwon),차준표(Junepyo Cha),임영관(Young-Kwan Lim),박성욱(Sungwook Park),이창식(Chang Sik Lee) 한국연소학회 2011 한국연소학회지 Vol.16 No.3

The purpose of this paper is to investigate the effect of equivalence ratio on the combustion and emission characteristics of a compression ignition engine fueled with biodiesel. In this research, a single-cylinder direct injection engine with 373.3 cc of displacement volume was tested on DC dynamometer. In order to investigate the effect of biodiesel equivalence ratio on combustion characteristics, the experiments were conducted at various equivalence ratios and injection pressures of 40~120 MPa. For investigating engine performance, lambda meter was connected and equivalence ratios was varied from 0.6 to 1.0. In addition, the exhaust emissions such as oxides of nitrogen(NOx), hydrocarbon(HC) and carbon monoxide(CO) were measured by exhaust gas analyzer under the various air/fuel ratios. The experimental results show that maximum IMEP was measured at the 0.8 of equivalence ratio. Furthermore, NOx emission was rapidly decreased as the increase of equivalence ratio. However soot emission was significantly increased according to the increase of equivalence ratio.

CO₂를 포함한 Simulated-EGR 압축착화엔진에서 당량비 변화에 따른 성능 예측

서현규 ( Hyun Kyu Suh ) 한국액체미립화학회 2020 한국액체미립화학회지 Vol.25 No.1

The objective of this work is to numerically reveal the effect of equivalence ratio change on the simultaneous reduction of NO_X and soot emissions from the simulated-EGR compression ignition engine containing CO₂. An experiment was conducted by using a single-cylinder common-rail injection system engine, an intake control system, and exhaust emissions analyzers. The numerical analysis results were validated under the same experimental conditions. To investigate the effect of equivalence ratio by simulated-EGR containing CO₂, the O₂, N₂, and CO₂ mole fraction were changed in the initial air conditions to the cylinder. The results were analyzed in terms of peak cylinder pressure, indicated mean effective pressure, indicated specific nitrogen oxide, and indicated specific soot. It was revealed that ignition delay characteristics and heat release rate (ROHR) characteristics were not significantly different according to the equivalence ratio. However, as the equivalence ratio increased from 0.68 to 0.83, the maximum combustion pressure and IMEP decreased by about 6.5% and 9.4%, respectively. In the case of ISFC, as is well known, the trend is opposite of IMEP. In the case of ISNO, as the equivalence ratio increased, less NO was generated, and as the equivalence ratio increased by 0.05, the ISSoot value of about 10% increased.

CI엔진에서 공연비 변화가 바이오디젤의 연소 특성에 미치는 영향

강민구(Mingu Kang),권석주(Seokjoo Kwon),차준표(Junepyo Cha),임영관(Young-Kwan Lim),박성욱(Sungwook Park),이창식(Chang Sik Lee) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42

The effect of air/fuel ratio on combustion characteristics was investigated in a compression ignition engine fueled with biodiesel. For investigating the effect of biodiesel air/fuel ratio on combustion characteristics, the experiments were performed at various equivalence ratios and 120㎫ of injection pressure. In addition, lambda meter were equipped to measure air/fuel ratio, which is varied from 0.6 to 1.0 as using various EGR ratio. The results were compared with those results without EGR. For analyzing exhaust emission characteristics, nitrogen oxidies(NOx), hydrocarbon(HC), and carbon monoxide(CO) are measured under the various air/fuel ratios. The experimental results show that NOx emission gradually decreased according to the decrease of equivalence ratio, and HC and soot emissions significantly increased as advanced injection timing. The soot and HC emissions generally decreased and NOx emission was almost zero level according to retarded injection timing cases.

원형 RC 기둥의 내진성능과 휨 초과강도

고성현 한국구조물진단유지관리공학회 2013 한국구조물진단유지관리공학회 논문집 Vol.17 No.5

Eight small scale circular reinforced concrete columns were tested under cyclic lateral load with constant axial load. Test specimens were designed with 4.5 aspect ratio. The selected test variables are longitudinal steel ratio, transverse steel ratio, yielding strength of longitudinal steel and axial load ratio. The test results of columns with different longitudinal steel ratio, transverse steel ratio and axial load ratio showed different seismic performance such as equivalent damping ratio, residual displacement and effective stiffness. It was found that the column with low strength of longitudinal steel showed significantly reduced seismic performance, especially for equivalent damping ratio and residual displacement. The regulation of flexural over-strength is adopted by Korea Bridge Design Specifications (Limited state design, 2012). The test results are compared with nominal strength, result of nonlinear moment-curvature analysis and the design specifications such as AASHTO LRFD and Korea Bridge Design Specifications (Limited state design).

모사 배기가스 재순환을 이용한 압축착화 엔진 성능 및 배기 특성

강민구(Mingu Kang),권석주(Seokjoo Kwon),차준표(Junepyo Cha),박성욱(Sungwook Park),이창식(Chang Sik Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

The effects of equivalence ratio on combustion and emissions characteristics were investigated in a compression ignition engine using simulated-EGR by diesel fuel. In order to analyze the effects of simulated exhaust gas recirculation, as a diluent almost pure carbon dioxide gas was supplied to reduce oxygen concentration at a surge tank. For investigating the effects of simulated-EGR on the combustion and emissions characteristics, the combustion characteristics for the variation of equivalence ratio were measured and analyzed in a single-cylinder diesel engine with a compression ratio of 17.3 and a displacement volume of 373.3cc. With the exhaust emission characteristics, nitrogen oxides (NOX), carbon monoxide (CO) and hydrocarbon (HC) were measured by exhaust gas analyzer under the various simulated-EGR ratios. The experimental results show that maximum IMEP was measured at BTDC 5° and the IMEP was gradually reduced as advanced injection timing. NOX emissions decreased dramatically with the increase of equivalence ratio and it was almost not produced at the range from 0.8 to 1.0 of equivalence ratio.

압력과 당량비에 따른 미지 오일의 자연발화 온도 변화 예측 : 수치적 접근

임준석(Jun Seok Lim),최효현(Hyo Hyun Choi),손채훈(Chae Hoon Sohn) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41

Auto-ignition temperature of various fuels is presented in several literatures. However, the majority of data are measured at atmospheric pressure and arbitrary equivalence ratio. In addition, auto-ignition temperature of a pure substance is well known, but that of mixture is not. In this paper, thermodynamic and chemical data of unknown mixture ,which is lubricating oil, are estimated approximately. Then, auto-ignition temperature is calculated numerically for various pressures and equivalence ratios. Flammability limit as a function of temperature, pressure and equivalence ratio is presented from numerical results. Auto-ignition temperature tends to decrease with increasing pressure and increase with decreasing equivalence ratio. Furthermore, auto-ignition temperature is found to be more sensitive to pressure variation than equivalence-ratio variation.

An experimental study on the performance optimization of a radiant burner with a surface flame structure

Seung Wan Cho,김영수,전충환,장영준 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.4

An experimental study was carried out on a newly developed, gas-fired radiant burner to optimize its performance for three different conditions of firing rate (80.5, 107.4, and 134.2 kW/m2). The operational equivalence ratios ranged from 0.6 to 1.3. Gas temperatures along the mat and upstream/downstream of the ceramic mat were obtained to investigate the effects of firing rate and equivalence ratio. The temperature of the unburned mixture in the burner port decreased as the firing rate increased. The opposite trend appeared in response to change in the equivalence ratio. This was mainly due to mixture velocity and residence time. The mechanism of temperature variations in the mat with the equivalence ratio and firing rate was described in detail. Results on flue gas emissions, such as the concentrations of EINO and CO, were also presented. It was confirmed that in lean-mixture conditions, the concentration of CO remains below 100 ppm for all firing rates. Lastly, radiation and water-boiling efficiencies were measured as functions of the equivalence ratio, firing rate, cookware diameter (Dp), and height of the burner housing (H). It was observed that conduction heat transport dominated the radiation effect less as the firing rate increased. From these observations, the effective heat input in the present radiant burner was determined to optimize its performance.

화염의 정량적 당량비 및 soot 측정을 위한 Plasma Diagnostics에 관한 연구

이석환(Seok Hwan Lee),여재익(Jai-ick Yoh) 한국연소학회 2014 KOSCOSYMPOSIUM논문집 Vol.2014 No.5

The strongly related combustion parameters, soot and equivalence ratio, are measured by the plasma spectroscopy in propane and gasoline flames. C2 intensity is almost zero in the non-sooting region of the flames, and it increases linearly with equivalence ratio in the sooting region of the flames. H/O ratio also increases linearly with increasing equivalence ratio. Thus we confirm that the Laser-induced Breakdown Spectroscopy (LIBS) can detect the carbonic particulates (soot) and the equivalence ratio in propane and gasoline flames.

연료-공기 혼합도와 당량비에 따른 NOx 배출 특성

박덕봉(Deok Bong Park),조봉국(Bong Kug Cho),장영준(Young June Chang),전충환(Chung Hwan Jeon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Lean premixed combustors are effective for significant NOx reductions compared to convectional gas turbine combustor. The objective of this research is to characterize the effects of the Unmixedness of fuel-air and equivalence ratio on the NOx emission in a lean premixed combustor. Experiments were conducted in a dump combustor at one atmosphere using commercial grade methane. At the same swirler angle of 45°, the degree of fuel-air mixing was varied from 0, 50, 100 and equivalence ratio ranged from 0.5 to 0.8. Inlet temperature on the first and second experimental condition was 570K. The resalts show when the degree of fuel-air is increased, NOx emission is decreased at the constant equivalence ratio. When equivalence ratio is increased, NOx emission is increased. Finally, an increase of the inlet temperature leads to NOx emission decrease.