• Title/Summary/Keyword: Volumetric Ratio

Search Result 386, Processing Time 0.023 seconds

Experimental Study on Comparison of Flame Propagation Velocity for the Performance Improvement of Natural Gas Engine

  • Chung Jin Do;Jeong Dong Soo
    • Journal of Environmental Science International
    • /
    • v.14 no.1
    • /
    • pp.15-22
    • /
    • 2005
  • Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

Axial Behavior of High Performance Fiber Reinforced Cementitious Composite Columns with PVA Fibers (PVA섬유를 사용한 고인성 시멘트 복합체 기둥의 압축거동)

  • Byun Jang-Bae;Jeon Su-Man;Jeon Esther;Kim Sun-Woo;Hwang Sun-Kyung;Yun Hyun-Do;Lim Byung-Hun
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2005.11a
    • /
    • pp.29-32
    • /
    • 2005
  • An experimental investigation on the strength and behavior of High Performance Fiber Reinforced Cement Composite(HPFRCC) column with Polyvinyl alcohol(PVA) fibers under axial load have been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of PVA, and the volumetric ratio of transverse reinforcement. Test results showed that the fibers, when used in PVA2.0, could result in superior composite performance compared to their individual fiber reinforced cement composites.

  • PDF

Removal of Organics and Nirtogen in Wastewater Using 2 Stage A/O(RBC) Process (RBC 반응조를 이용한 2단 A/O 공정에서 유기물질 및 질소제거)

  • 최명섭;손인식
    • Journal of Environmental Health Sciences
    • /
    • v.29 no.3
    • /
    • pp.59-64
    • /
    • 2003
  • This study was conducted to investigate anoxic-RBC-anoxic-RBC process and its application to remove biologically organics and nitrogen. BOD and total-nitrogen(T-N) removal efficiencies were decreased as volumetric loading rate increased. But, the removal efficiency changes of T-N were little, as compared to BOD. Increase of internal recycle rate had few affect of BOD and T-N removal rates. Also, influent allocation(to 2nd anoxic reactor) had few affect of BOD removal efficiency rate. However, when the influent allocation rate was 30%, T-N removal efficiency was increased to 84.1 %. BOD/N ratio applied to 2nd anoxic reactor was increased to range of 3.65-4.37 as influent allocation rate increased to range 20∼35%. But, it might also cause adverse effect such as decrease of denitrification rate in excessive influent allocation rate.

Analyses on Consolidation Characteristics of Dredged and Reclaimed Soils in Busan Area (부산지역 준설매립지반의 압밀거동 특성 분석)

  • Yoo, Nam-Jae;Kim, Dong-Gun;Hwang, Hee-Seok
    • Journal of Industrial Technology
    • /
    • v.32 no.A
    • /
    • pp.87-94
    • /
    • 2012
  • For soils with high void ratios, the inverse method of utilizing results obtained from centrifuge model test was used to find the constitutive relation of effective stress - void ratio - permeability whereas conventional oedometer test and constant rate of strain consolidation(CRS) test about settlement of interface and pore pressure and distribution with time were compared with numerically estimated values to confirm such a constitutive relation as obtained from the inverse method. As results of numerical method, the volumetric ratio and reclamation velocity were obtained for the reclamation condition.

  • PDF

An Behavior of RC Columns Using High Performance Fiber Reinforced Cement Composites under Axial Loads (일정축력을 받는 고인성 섬유보강 시멘트 복합체 기둥의 거동)

  • Hwang Sun-Kyoung;Yun Hyun-Do;Han Byung-Chan;Park Wan-Shin;Yang Il-Seung;Cheon Esther
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2005.05a
    • /
    • pp.87-90
    • /
    • 2005
  • An experimental investigation on the strength and behaviour of reinforced concrete columns using high performance fiber reinforced cement composites has been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of steel cord(SC) and Polyethylene (PE), and the volumetric ratio of transverse reinforcement Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber reinforced cement composites.

  • PDF

Strength and Ductility of High-Strength Reinforced Concrete Columns under Uniaxial Loads (중심 축력을 받는 고강도 철근 콘크리트 기둥의 내력 및 연성에 관한 연구)

  • 이강건;이재연;김성수;이리형
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1990.10a
    • /
    • pp.57-62
    • /
    • 1990
  • This paper is to study the effect of rectilinear confinement in high-strength concrete subjected to a monotonically increasing compressive axial loads. To investigate behavior of columns rectilinearly confined with lateral ties and longitudinal rebars, twelve specimens including two plain concrete specimens were tested. The main variables in this study are volumetric ratio of lateral ties, cistribution of lateral ties, yield strength of logitudinal steel, ratio of area of longitudinal steel to the area of cross section. The test results were not only compared with an empirical model for the stress-strain curve of rectilinearly confined high-strength concrete but also the existing model. The empirical model used calculating column capacity shows better agreement with the test results tham the existing model.

  • PDF

An Experimental Study on RC Columns Using High Performance Fiber Reinforced Cement Composites (고인성 섬유보강 시멘트 복합체를 사용한 콘크리트 기둥의 실험적 연구)

  • Hwang Sun-Kyoung;Yun Hyun-Do;Han Byung-Chan;Park Wan-Shin;Jeon Esther;Yang Il-Seung
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2004.11a
    • /
    • pp.631-634
    • /
    • 2004
  • An experimental investigation on the strength and behaviour of reinforced concrete columns using high performance fiber reinforced cement composites has been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of steel cord(SCI) and polypropylene(PP), and the volumetric ratio of transverse reinforcement Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber reinforced cement composites.

  • PDF

A Study on the Improvement of Heat Transfer Performance in Low Temperature Closed Thermosyphon

  • Han, Kyu-Il;Yee, Seok-Su;Park, Sung-Hyun;Lee, Suk-Ho;Cho, Dong-Hyun
    • Journal of Mechanical Science and Technology
    • /
    • v.16 no.9
    • /
    • pp.1102-1111
    • /
    • 2002
  • The study focuses on the heat transfer performance of two-phase closed thermosyphons with plain copper tube and tubes having 50, 60, 70, 80, 90 internal grooves. Three different working fluids(distilled water, methanol, ethanol) are used with various volumetric liquid fill charge ratio from 10 to 40%. Additional experimental parameters such as operating temperature and inclination angle of zero to 90 degrees are used for the comparison of heat transfer performance of the thermosyphon. Condensation and boiling heat transfer coefficients, heat flux are obtained using experimental data for each case of specific parameter. The experimental results are assessed and compared with existing correlations. The results show that working fluids, liquid fill charge ratio, number of grooves and inclination angle are very important factors for the operation of thermosyphons. The relatively high rate of heat transfer is achieved when the thermosyphon with internal grooves is used compared to that with plain tube. The optimum liquid fill charge ratio for the best heat transfer performance lies between 25% and 30%. The range of the optimum inclination angle for this study is 20$^{\circ}$~30$^{\circ}$ from the horizontal position.

A Study for the Effect of Liquid Droplet Impingement Erosion on the Loss of Pipe Flow Materials (배관 재질 손상에 미치는 액적충돌침식의 영향에 대한 연구)

  • Kim, Kyung Hoon;Cho, Yun Su;Kim, Hyung Joon
    • Journal of ILASS-Korea
    • /
    • v.18 no.1
    • /
    • pp.9-15
    • /
    • 2013
  • Wall thinning of pipeline in power plants occurs mainly by flow acceleration corrosion (FAC), cavitation erosion (C/E), liquid droplet impingement erosion (LDIE). Wall thinning by FAC and C/E has been well investigated; however, LDIE in plant industries has rarely been studied due to the experimental difficulty of setting up a long injection of highly-pressurized air. In this study, we designed a long-term experimental system for LDIE and investigate the behavior of LDIE for three kinds of materials (A106B, SS400, A6061). The main control parameter was the air-water ratio (${\alpha}$), which was defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). In order to clearly understand LDIE, the spraying velocity (${\nu}$) of liquid droplets was controled larger then 160 m/s and the experiments were performed for 15 days. Therefore, this research focuses relation between erosion rate and air-water ratio on the various pipe-flow materials. NPP(nuclear power plant)'s LDIE prediction theory and management technique were drawn from the obtained data.

Characterization of a carbon black rubber Poisson's ratio based on optimization technique applied in FEA data fit

  • Lalo, Debora Francisco;Greco, Marcelo;Meroniuc, Matias
    • Structural Engineering and Mechanics
    • /
    • v.76 no.5
    • /
    • pp.653-661
    • /
    • 2020
  • The paper presents a study regarding rubber compressibility behavior. The objective is to analyze the effect of compression degree of rubber on its mechanical properties and propose a new methodology based on reverse engineering to predict compressibility degree based on uniaxial stretching test and Finite Element Analysis (FEA). In general, rubbers are considered to be almost incompressible and Poisson's ratio is close to 0.5. Since this property is intimately related to the rubber packing density, little changes in Poisson's ratio can lead to significant changes regarding mechanical behavior. The deviatory hyperelastic constants were obtained through experimental data fitting by least squares method for the most relevant constitutive models implemented in commercial software Abaqus, such as: Neo-Hooke, Mooney-Rivlin, Ogden, Yeoh and Arruda-Boyce, whereas the hydrostatic part was determined through an optimization algorithm implemented in the Abaqus environment by Python scripting. The simulation results presented great influence of the Poisson's ratio in the rubber specimen mechanical behavior mainly for high strain levels. A conventional pure volumetric compression test was also carried out in order to compare the results obtained by the proposed methodology.