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Investigation of knock suppression characteristics in a boosted methane : gasoline blended fuelled SI engine

Yang Z., Miganakallu N., Rao S., Harsulkar J., Naber J., Lonari Y., Szwaja S.

Journal of KONES

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2018

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Vol. 25, No. 3

517--525

EN

Natural gas has a higher knock suppression effect than gasoline which makes it possible to operate at higher compression ratio and higher loads resulting in increased thermal efficiency in a spark ignition engine However, using port fuel injected natural gas instead of gasoline reduces the volumetric efficiency from the standpoints of the charge displacement of the gaseous fuel and the charge cooling that occurs from liquid fuels. This article investigates the combustion and engine performance characteristics by utilizing experimental and simulation methods varying the natural gas-gasoline blending ratio at constant engine speed, load, and knock level. The experimental tests were conducted on a single cylinder prototype spark ignited engine equipped with two fuel systems: (i) a Direct Injection system for gasoline and (ii) a Port Fuel Injection (PFI) system for compressed natural gas. For the fuels, gasoline with 10% ethanol by volume (commercially known as E10) with a research octane number of 91.7 is used for gasoline via the DI system, while methane is injected through PFI system. The knock suppression tests were conducted at 1500 rpm, 12 bar net indicated mean effective pressure wherein the engine was boosted using compressed air. At 60% of blending methane with E10 gasoline, the results show high knock suppression. The net indicated specific fuel consumption is 7% lower, but the volumetric efficiency is 7% lower compared to E10 gasoline only condition. A knock prediction model was calibrated in the 1-D simulation software GT-Power by Gamma Technologies. The calibration was conducted by correlating the simulated engine knock onset with the experimental results. The simulation results show its capability to predict knock onset at various fuel blending ratios.

2

Wiebe function parameter determination for mass fraction burn calculation in an ETHANOL-GASOLINE fuelled SI engine

Yeliana, Cooney C., Worm J., Michalek D., Naber J.

Journal of KONES

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2008

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Vol. 15, No. 3

567-574

EN

The Mass Fraction Burn (MFB) and Heat Release Rate (HRR) reflect the amount of fuel burned and the rate of burning throughout the combustion process in an internal combustion engine. These parameters play a crucial role in research and development endeavours focused on engine efficiency, emissions, and overall operating performance. Analytically in a Spark-Ignition (SI) engine, these parameters are often modelled with the Wiebe function, a well known mass fraction burn formulation, which is a function of "a" (efficiency parameter), "m" (form factor), crank angle, and the duration of combustion. This function is a simple but powerful correlation model that is well suited for zero and one dimensional engine cycle simulations. In this work, the Wiebe function parameters are determined over a range of fuel compositions and compression ratios by fitting the Wiebe function curve to the experimentally obtained MFB data from a single-zone HRR analysis. The Wiebe function parameters are determined using a curve fitting model by finding the minimum of a scalar function of several variables. This functionality has been built into the single-zone mass fraction burned model. Experiments with five ethanol-gasoline fuel blends: E0 (gasoline), E20, E40, E60, and E84 were conducted on a SI Cooperative Fuels Research (CFR) engine while holding a constant load of 330 kPa Net Indicated Mean Effective Pressure (Net IMEP). There were five methods introduced to fit the Wiebe function parameters, which utilized a combination of least square method and direct algebraic solution. This paper details the process used to determine the Wiebe function parameters, and compare the results obtained using these methods for the ethanol-gasoline mixture concentrations.

3

Property determination for ethanol-gasoline blends with application to mass fraction burn analysis in a spark ignition engine

Yeliana, Worm J., Michalek D., Naber J.

Journal of KONES

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2008

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Vol. 15, No. 2

553-561

EN

The Mass Fraction Burn (MFB) and Heat Release Rate (HRR) reflects the amount of fuel burned, and the rate of burning throughout the combustion process in an internal combustion engine. These parameters play a crucial role in research and development endeavors focused on engine efficiency, emissions, and overall operating performance. They are computed by analyzing measured pressure data and applying thermodynamic principals to determine the energy released during the combustion process. Thus, the properties of the fuel-air and combusted gas mixtures play an important role in the analysis. Engine pressure data were taken from a Spark-Ignition Cooperative Fuels Research (CFR) engine operating at a constant load of 330 kPa Net Indicated Mean Effective Pressure (Net IMEP) and using five ethanol-gasoline fuel blends: E0 (gasoline), E20, E40, E60, and E84. The fuels were assumed to be in a non-reacting state throughout the mixing process. Once the fuel mixture properties were known, the fuel-air and burned mixture properties were determined using the fuel-air mass ratio. The analysis presented within this paper details the process by which the fuel, fuel-air, and burned mixture properties can be determined. The MFB of five different fuel blends at a chosen operating condition was also presented along with the pressure trace, the temperature and the gamma profile at the end of this paper.