The NOx and N2O Emission Characteristics of an HCCI Engine Operated With n-Heptane

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.ijhydene.2013.06.084International Journal of Hydrogen Energy, 38, 26, pp. 11429-11437, 2013-07-17 The effect of hydrogen addition on combustion and emission characteristics of an n-heptane fuelled HCCI engine Guo, Hongsheng; Neill, W. Stuart The Effect of Hydrogen Addition on Combustion and EmissionCharacteristics of an n-Heptane Fuelled HCCI Engine AbstractThe mechanisms of the influence of hydrogen enrichment on the combustion and emission characteristics of an n-heptane fuelled homogeneous charge compression ignition (HCCI) engine was numerically investigated using a multi-zone model. The model calculation successfully captured most available experimental data. The results show that hydrogen addition retards combustion phasing of an n-heptane fuelled HCCI engine due to the dilution and chemical effects, with the dilution effect being more significant. It is because of the chemical effect that combustion duration is reduced at a constant compression ratio if an appropriate amount of hydrogen is added. As a result of retarded combustion phasing and reduced combustion duration, hydrogen addition increases indicated thermal efficiency at a constant combustion phasing. Hydrogen addition reduces indicated specific unburned hydrocarbon emissions, but slightly increases normalized unburned hydrocarbon emissions that are defined as the emissions per unit burned n-heptane mass. The increase in normalized unburned hydrocarbon emissions is caused by the presence of more remaining hydrocarbons that compete with hydrogen for some key radicals during high temperature combustion stage. At a given hydrogen addition level, N 2 O emissions increases with overly retarding combustion phasing, but hydrogen addition moderates this increase in N 2 O emissions.

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“…Although the experiment in [22] did not collect N 2 O emissions data, an earlier experiment study [29] …”

Section: Resultsmentioning

confidence: 99%

The effect of hydrogen addition on combustion and emission characteristics of an n-heptane fuelled HCCI engine

Guo

Neill

2013

International Journal of Hydrogen Energy

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“…The low boiling point of n-heptane makes it easier to form a homogeneous fuel-air mixture in the combustion chamber without having to preheat the fuel or intake air. The extremely low PM emissions reported earlier [14,33,34] provide evidence that the fuel/air/diluent mixture inside the combustion chamber of the research engine was reasonably homogeneous prior to the initiation of combustion. The high cetane number of n-heptane makes it possible to obtain HCCI combustion with a relatively low compression ratio.…”

Section: Experimental Apparatus and Data Analysismentioning

confidence: 67%

“…3-10, combustion stability is a complex function of the bulk fuel/air/diluent mixture properties and the engine operating parameters. In previous papers [14,33,34], HCCI combustion performance and emissions were shown to be a strong function of the combustion phasing, particularly the location of 50% heat release. The infiuence of CA50 combustion phasing on combustion stability will now be examined for the experimental data presented in this paper.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 is a schematic diagram of the research engine facility. Detailed information about the experimental set-up, intake and exhaust system, EGR control, fuel and air flow measurement, data acquisition system, and experimental procedure can be found in the literature [14,33,34]. Following is a brief description of the intake and exhaust systems, configuration of the EGR system, and measurement and analysis of cylinder pressure data, which are specifically related to this research.…”

Section: Experimental Apparatus and Data Analysismentioning

confidence: 99%

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An Experimental Investigation of HCCI Combustion Stability Using n-Heptane

Neill

Chippior

2012

Journal of Energy Resources Technology

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The combustion stability of a single-cylinder homogeneous charge compression ignition (HCCI) engine operated with n-heptane was experimentally investigated over a range of engine speeds (N), intake temperatures and pressures, compression ratios (CR), air/fuel ratios (AER), and exhaust gas recirculation (EGR) rates. These parameters were varied to alter the combustion phasing from an overly advanced condition where engine knock occurred to an overly retarded condition where incomplete combustion was observed with excessive emissions of carbon monoxide (CO) and unburned hydrocarbons (UHC). The combustion stability was quantified by the coefficients of variation in indicated mean effective pressure (COVj^ep) and peak cylinder pressure (COVp^ax)-Cycle-to-cycle variations in the HCCI combustion behavior of this engine were shown to depend strongly on the combustion phasing, defined in this study as the crank angle position where 50% of the energy was released (CA50). In general, combustion instability increased significantly when the combustion phasing was overly retarded. The combustion phasing was limited to conditions where the COV¡,,^i, was 5% or less as engine operation became difficult to control beyond this point. Based on the experimental data, the combustion phasing limit was approximately a linear function of the amount of fuel inducted in each cycle. Stable HCCI combustion could be obtained with progressively retarded combustion phasing as the fuel fiow rate increased. In comparison, stable HCCI combustion was only obtained under very advanced combustion phasing for low load operating conditions. Investigation of the experimental data reveals that the cyclic variations in HCCI combustion were due to cycle-to-cycle variations in total heat release (THR). The combustion completeness of the previous cycle affected the in-cylinder bulk mixture conditions and resultant heat release process of the following engine cycle.

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“…The N 2 O mass fraction is 2 × 10 –6 , which corresponds to the volume fraction of 1.3 ppm. It should note that the significant increase of N 2 O was detected experimentally in a HCCI engine fueled with n -heptane when incomplete combustion occurs. The N 2 O peak concentration of 1.7 ppm was observed when the combustion efficiency dropped to ∼70%.…”

Section: Resultsmentioning

confidence: 85%

Numerical Study of the Influence of the Photochemical Activation of Oxygen Molecules on Homogeneous Charge Compression Ignition Performance

2017

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Numerical analysis of the possibility of the combustion enhancement in a homogeneous charge compression ignition (HCCI) engine operating on methane via the production of O2(a1Δg) molecules or O atoms by resonance laser radiation in the 5 mm thickness layer, located near the cylinder head, is conducted for both the nominal- and low-load regimes. It is shown that the abundance of both singlet delta oxygen and atomic oxygen in such a layer substantially accelerates ignition phasing, enhances the combustion, and reduces the pollutant emission. Moreover, the advance in the specific work in these cases is higher than the energy put into the gas for producing O2(a1Δg) molecules or O atoms. In doing so, the production of O2(a1Δg) molecules is more effective for the combustion enhancement in a HCCI engine. At a low-load regime, the production of O2(a1Δg) molecules makes it possible to extend the range of stable combustion, to increase notably the engine power (by a factor of 1.4), and to reduce by a few times the emissions of CO, unburnt hydrocarbons, and organic compounds.

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The NOx and N2O Emission Characteristics of an HCCI Engine Operated With n-Heptane

Abstract: This paper presents the oxides of nitrogen (NO x

Cited by 13 publications

References 20 publications

The effect of hydrogen addition on combustion and emission characteristics of an n-heptane fuelled HCCI engine

The effect of hydrogen addition on combustion and emission characteristics of an n-heptane fuelled HCCI engine

An Experimental Investigation of HCCI Combustion Stability Using n-Heptane

Numerical Study of the Influence of the Photochemical Activation of Oxygen Molecules on Homogeneous Charge Compression Ignition Performance

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