Application of a Supercharger in a Two-Stage Boosting System for a Gasoline HCCI Engine: A Simulation Study

2011 ◽  
Author(s):  
Prasad Shingne ◽  
Dennis Assanis ◽  
Aristotelis Babajimopoulos ◽  
Alan Mond ◽  
Hakan Yilmaz
Keyword(s):  
High Load ◽  
Two Stage ◽  
Engine Simulation ◽  
Engine Model ◽  
Load Limit ◽  
High Pressure Stage ◽  
Stage System ◽  
Intake Pressure ◽  
Better Than ◽  
Fresh Charge

Recently, a number of studies have demonstrated that boosting can extend the high load limit of HCCI. This paper compares two two-stage boosting systems for a 4-cylinder, 2.0 liter engine, within the framework of a 1D engine simulation. A series two-stage boosting system wherein both high and low pressure stages are turbochargers (TCTC) is compared with another series two-stage system, where the high pressure stage from TCTC is replaced with a small supercharger (TCSC). The engine model in these configurations is operated in steady state at high load boosted HCCI points (∼ 6.5 bar BMEP) over a range of engine speeds. The comparison has been carried out by two methods: in Method I the intake pressure to the engine has been matched for both TCTC and TCSC; and in Method II, the amount of fresh charge into the engine has been matched for both systems. A detailed energy balance shows that the performance in terms of BSFC for the TCSC system is worse for Method I. However, this changes for Method II, and the TCSC system is comparable or even better than the TCTC system. This is achieved by greatly reducing the pumping losses associated with the TCTC system, while the parasitic losses of the supercharger are minimized by having to boost to lower intake pressures due to lowered back pressures in the TCSC system.

scholarly journals Numerical Simulation of Two-Stage Variable Geometry Turbine

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5349
Author(s):  
Dariusz Kozak ◽  
Paweł Mazuro ◽  
Andrzej Teodorczyk
Keyword(s):  
Combustion Engine ◽  
Three Dimensional ◽  
High Load ◽  
Operating Conditions ◽  
Two Stage ◽  
Variable Turbine Geometry ◽  
Low Load ◽  
Variable Geometry Turbine ◽  
Stage System ◽  
Maintenance Requirements

The modern internal combustion engine (ICE) has to meet several requirements. It has to be reliable with the reduced emission of pollutant gasses and low maintenance requirements. What is more, it has to be efficient both at low-load and high-load operating conditions. For this purpose, a variable turbine geometry (VTG) turbocharger is used to provide proper engine acceleration of exhaust gases at low-load operating conditions. Such a solution is also efficient at high-load engine operating conditions. In this paper, the result of an unsteady, three-dimensional (3D) simulation of the variable two-stage turbine system is discussed. Three different VTG positions were considered for those simulations, along with three different turbine speeds. The turbine inlet was modeled as six equally placed exhaust pipes for each cylinder to eliminate the interference of pressure waves. The flow field at the outlet of the 1st stage nozzle vane and 2nd stage rotor was investigated. The simulations showed that the variable technologies significantly improve the efficiency of the two-stage turbine system. The highest overall efficiency of the two-stage system was achieved at 60,000 rpm and 11o VTG position.

Model-Based Estimation of Turbocharger Requirements for Boosting an HCCI Engine

2010 ◽  
Author(s):  
Sotirios Mamalis ◽  
Aristotelis Babajimopoulos
Keyword(s):  
High Pressures ◽  
Simulation Software ◽  
Exhaust Gas ◽  
University Of Michigan ◽  
Hcci Engine ◽  
Engine Simulation ◽  
Hcci Combustion ◽  
Load Limit ◽  
Intake Pressure ◽  
The University

Turbocharged Homogeneous Charge Compression Ignition (HCCI) has been modeled and has demonstrated the potential to extend the engine’s upper load limit. A commercially available engine simulation software (GT-Power®) coupled to the University of Michigan HCCI combustion and heat transfer correlations was used to model a single cylinder boosted HCCI engine including a phenomenological turbocharger model. The scope of this study is to explore the upper load limits of boosted HCCI operation and to identify turbocharger requirements for boosting the HCCI. The results of this study are consistent with the literature: Boosting helps increase the HCCI upper load limit, but matching of turbochargers is a problem. In addition, the low exhaust gas enthalpy resulting from HCCI combustion leads to high pressures in the exhaust manifold and increased pumping work. It is shown that loads as high as 17 bar NMEP can be reached at low engine speeds, when the intake pressure is 3 bar.

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

scholarly journals A Comparison of Ethanol, Methanol, and Butanol Blending with Gasoline and Its Effect on Engine Performance and Emissions Using Engine Simulation

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1322
Author(s):  
Simeon Iliev
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Exhaust Emissions ◽  
Engine Simulation ◽  
Engine Model ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Blended Fuels

Air pollution, especially in large cities around the world, is associated with serious problems both with people’s health and the environment. Over the past few years, there has been a particularly intensive demand for alternatives to fossil fuels, because when they are burned, substances that pollute the environment are released. In addition to the smoke from fuels burned for heating and harmful emissions that industrial installations release, the exhaust emissions of vehicles create a large share of the fossil fuel pollution. Alternative fuels, known as non-conventional and advanced fuels, are derived from resources other than fossil fuels. Because alcoholic fuels have several physical and propellant properties similar to those of gasoline, they can be considered as one of the alternative fuels. Alcoholic fuels or alcohol-blended fuels may be used in gasoline engines to reduce exhaust emissions. This study aimed to develop a gasoline engine model to predict the influence of different types of alcohol-blended fuels on performance and emissions. For the purpose of this study, the AVL Boost software was used to analyse characteristics of the gasoline engine when operating with different mixtures of ethanol, methanol, butanol, and gasoline (by volume). Results obtained from different fuel blends showed that when alcohol blends were used, brake power decreased and the brake specific fuel consumption increased compared to when using gasoline, and CO and HC concentrations decreased as the fuel blends percentage increased.

Performance Analysis of the Test Results on a Two-Stage Transonic Fan

1983 ◽  
Vol 105 (1) ◽  
pp. 125-129
Author(s):  
Baoshi Chen ◽  
Tianyi Zhang
Keyword(s):  
Mach Number ◽  
Performance Analysis ◽  
Radial Distribution ◽  
Flow Separation ◽  
High Load ◽  
Test Results ◽  
Two Stage ◽  
Stall Margin ◽  
High Incidence ◽  
Transonic Fan

Test results obtained from a two-stage fan are analysed and the reasons that caused the design performance target not to be attained are presented in this paper. Addition of a partspan shroud on rotor 1 caused higher losses and changed radial distribution of parameters. Modification on the flowpath and chord length of stator 1 resulted in excessively high inlet Mach number and flow separation in the hub region. The high load and high incidence at the hub of rotor 2 caused higher losses and reduced stall margin of the fan.

Effect of female executives on Chinese cultural media enterprise efficiency

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ying Li ◽  
Yung-Ho Chiu ◽  
Tai-Yu Lin ◽  
Hongyi Cen
Keyword(s):  
Boards Of Directors ◽  
Company Performance ◽  
Tobit Regression ◽  
Female Executives ◽  
Two Stage ◽  
Content Type ◽  
Female Directors ◽  
The Impact ◽  
Cultural Media ◽  
Better Than

Purpose As more women are now being appointed to senior and top management positions and invited to sit on boards of directors, they are now directly participating in strategic company decision-making. As female directors have been found to provide new ideas, increase company competitiveness, efficiency and performance and bring a greater number of external resources to a company than male directors, this paper aims to put female directors as a variable into the data envelopment analysis (DEA) and statistical models to explore the effect of female directors on operating performances. The DEA first quantified and measured the company efficiencies, after which the statistical model analyzed the correlations between the variables to specifically identify the impact of female decision makers on the operating efficiencies in state-owned and private enterprises. Design/methodology/approach A novel two-stage, meta-hybrid dynamic DEA was developed to explore Chinese cultural media company efficiencies under optimal input and output resource allocations, after which Tobit Regression was applied to determine the effect of female executives on these efficiencies. Findings From 2012 to 2016, the overall efficiencies in Chinese state-owned cultural media enterprises were better than in the private cultural media enterprises. The overall technology gaps (TGs) in the state-owned cultural media enterprises were better than in the private cultural media enterprises. Originality/value Previous research has tended to focus on the causal relationships between female senior executives and business performances; however, there have been few studies on the relationships between female executives and company performance from an efficiency perspective (optimal resource allocation). This paper, therefore, is the first to develop a novel two-stage, meta-hybrid dynamic DEA to examine Chinese cultural media enterprise efficiencies, and the first to apply Tobit Regression to assess the effect of female executives on those efficiencies.

Two-stage system for robust neutral/lombard speech recognition

2007 ◽  
Author(s):  
Hynek Bořil ◽  
Petr Fousek ◽  
Harald Höge
Keyword(s):  
Speech Recognition ◽  
Two Stage ◽  
Stage System

Analysis of Variable Intake Runner Lengths and Intake Valve Open Timings on Engine Performances

2014 ◽  
Vol 663 ◽  
pp. 336-341 ◽  
Author(s):  
Mohd Farid Muhamad Said ◽  
Zulkarnain Abdul Latiff ◽  
Aminuddin Saat ◽  
Mazlan Said ◽  
Shaiful Fadzil Zainal Abidin
Keyword(s):  
Engine Performance ◽  
Intake Manifold ◽  
Intake Valve ◽  
Si Engine ◽  
Engine Simulation ◽  
Engine Model ◽  
Optimum Parameters ◽  
Comparison Results ◽  
Variable Valve ◽  
Engine Development

In this paper, engine simulation tool is used to investigate the effect of variable intake manifold and variable valve timing technologies on the engine performance at full load engine conditions. Here, an engine model of 1.6 litre four cylinders, four stroke spark ignition (SI) engine is constructed using GT-Power software to represent the real engine conditions. This constructed model is then correlated to the experimental data to make sure the accuracy of this model. The comparison results of volumetric efficiency (VE), intake manifold air pressure (MAP), exhaust manifold back pressure (BckPress) and brake specific fuel consumption (BSFC) show very well agreement with the differences of less than 4%. Then this correlated model is used to predict the engine performance at various intake runner lengths (IRL) and various intake valve open (IVO) timings. Design of experiment and optimisation tool are applied to obtain optimum parameters. Here, several configurations of IRL and IVO timing are proposed to give several options during the engine development work. A significant improvement is found at configuration of variable IVO timing and variable IRL compared to fixed IVO timing and fixed IRL.

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