Pressure Sensitivity of HCCI Auto-Ignition Temperature for Primary Reference Fuels

Truedsson, Ida; Tunér, Martin; Johansson, Bengt; Cannella, William

doi:10.4271/2012-01-1128

Cited by 45 publications

(21 citation statements)

References 6 publications

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“…The range of fuels investigated here is similar to that studied by Truedsson et al [23,[50][51][52] in their experiments on the compression ratio required for autoignition; however, unlike the current computational approach those experiments held equivalence ratio and engine speed constant. Following the general procedure first introduced by Niemeyer et al [42], we performed driving cycle simulations for a typical light-duty passenger vehicle to generate steady-state operating points in terms of engine speed and torque, and also obtained the corresponding baseline SI engine fuel consumption for these operating points.…”

Section: Introductionmentioning

confidence: 66%

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

Niemeyer

Daly

Cannella

et al. 2015

Fuel

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A new metric for ranking the suitability of fuels in LTC engines was recently introduced, based on the fraction of potential fuel savings achieved in the FTP-75 light-duty vehicle driving cycle. In the current study, this LTC fuel performance index was calculated computationally and analyzed for a number of fuel blends comprised of n-heptane, isooctane, toluene, and ethanol in various combinations and ratios corresponding to octane numbers from 0 to 100. In order to calculate the LTC index for each fuel, computational driving cycle simulations were first performed using a typical light-duty passenger vehicle, providing pairs of engine speed and load points. Separately, for each fuel blend considered, single-zone naturally aspirated HCCI engine simulations with a compression ratio of 9.5 were performed in order to determine the operating envelopes. These results were combined to determine the varying improvement in fuel economy offered by fuels, forming the basis for the LTC fuel index. The resulting fuel performance indices ranged from 36.4 for neat n-heptane (PRF0) to 9.20 for a three-component blend of n-heptane, isooctane, and ethanol (ERF1). For the chosen engine and chosen conditions, in general lower-octane fuels performed better, resulting in higher LTC fuel index values; however, the fuel performance index correlated poorly with octane rating for less-reactive, higher-octane fuels.

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Section: Introductionmentioning

confidence: 66%

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

Niemeyer

Daly

Cannella

et al. 2015

Fuel

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“…A temperature model according to Ref. [13], accounting for heating from mixing with hot residuals and from pipes in the intake, was used to calculate Tivc (shown in Fig. 1) from the inlet air temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The start of combustion (SOC), which is the point of auto-ignition, was defined as when the reaction rate had reached a threshold value. This value was chosen to be 0.2 J/ CAD, corresponding to a rate of heat release when early combustion can be seen [13]. This definition is preferred since it indicates the onset of the chemical reactions.…”

Section: Resultsmentioning

confidence: 99%

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Pressure Sensitivity of HCCI Auto-Ignition Temperature for Oxygenated Reference Fuels

Truedsson

Tunér

Johansson

et al. 2013

Journal of Engineering for Gas Turbines and Power

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The current research focuses on creating a homogeneous charge compression ignition (HCCI) fuel index suitable for comparing different fuels for HCCI operation. One way to characterize a fuel is to use the auto-ignition temperature (/UT). The AIT can be extracted from the pressure trace. Another potentially interesting parameter is the amount of low temperature heat release (LTHR) that is closely connected to the ignition properties of the fuel. The purpose of this study was to map the ATT and the amount of LTHR of different oxygenated reference fuels in HCCI combustion at different cylinder pressures. Blends of n-heptane, iso-octane, and ethanol were tested in a cooperative fuels research (CFR) engine with a variable compression ratio. Five different inlet air temperatures ranging from 50 °C to 150 °C were used to achieve different cylinder pressures and the compression ratio was changed accordingly to keep a constant combustion phasing, CA50, of 3 ± 1 deg affer top dead center (TDC). The experiments were carried out in lean operation with a constant equivalence ratio of 0.33 and with a constant engine speed of 600 rpm. The amount of ethanol needed to suppress the LTHR from different primary reference fuels (PRFs) was evaluated. The AIT and the amount of LTHR for different combinations of n-heptane, iso-octane, and ethanol were charted.

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“…One possible reason is that the locally richer mixture zones exists in the E0 combustion. In addition, recent studies showed the fact that ethanol also acted as a hydroxyl radical scavenger during the initial ignition process in the homogenous charge compression ignition (HCCI) [33,34]. Although this scavenging effect is still unclear in the whole combustion process, it may play a significant role on the lower OH* emission in ethanol-gasoline blends compared with the gasoline.…”

Section: Flame Propagation Under Different Ignition Location and Timingmentioning

confidence: 96%

Effect of Ethanol Ratio on Ignition and Combustion of Ethanol-Gasoline Blend Spray in DISI Engine-Like Condition

Chen

Okazumi

Nishida

et al. 2015

SAE Int. J. Fuels Lubr.

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To reduce carbon dioxide emission and to relieve the demand of fossil fuels, ethanol is regarded as one of the most promising alternative fuels for gasoline. Recently, using ethanol in the state-of-the-art gasoline engine, direct-injection spark-ignition (DISI) engine, has become more attention by researchers due to less knowledge of the ignition and combustion processes in that engine.In this study, different ethanol-gasoline blended fuels, E0 (100% gasoline), E85 (85% ethanol and 15% gasoline mixed in volume basis) and E100 (100% ethanol) were injected by a valve-covered-orifice (VCO) hole-type nozzle. The experimental environment was set to the condition similar with the near top dead center (TDC) in DISI engine. The high-speed imaging of shadowgraph, OH* chemiluminescence and flame natural luminosity were used to clarify the characteristics of the ignition process, flame development and propagation. Results revealed that the flame propagation was directed towards the downstream of spray but not the upstream where the local mixture became diluted. In comparison to the pure gasoline, adding ethanol increased sensitivity to the spark energy. The good burn showed a fast flame growth and larger flame radius. While the poor combustion revealed a long-narrow flame shape and inferior development of the flame radius. Also, the E85 and E100 demonstrated a moderate natural luminosity or nearly transparent-like appearance. Different ignition position and timing were investigated in this study. The ethanol-gasoline blend showed a potential favorable combustion when the fuel was ignited at advanced timing and the middle to downstream of spray.

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Pressure Sensitivity of HCCI Auto-Ignition Temperature for Primary Reference Fuels

Cited by 45 publications

References 6 publications

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

Pressure Sensitivity of HCCI Auto-Ignition Temperature for Oxygenated Reference Fuels

Effect of Ethanol Ratio on Ignition and Combustion of Ethanol-Gasoline Blend Spray in DISI Engine-Like Condition

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