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

Abstract

/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.

The effects of hydrogen addition on the auto-ignition delay of homogeneous primary reference fuel/air mixtures in a rapid compression machine

“…It has been widely reported [32,48] that the increase in the ignition delay at low temperatures is primarily caused by the following reaction:…”

“…Hongsheng et al Heat capacity k Thermal conductivity, W/mK g Heat capacity ratio E Energy, MJ/kg i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 0 ( 2 0 1 5 ) 1 3 9 9 4 e1 4 0 0 5 [31,32] investigated the effects of hydrogen enrichment on the combustion and emission characteristics of a diesel-fueled HCCI engine experimentally using a cooperative fuel research (CFR) engine. Their results showed that enrichment with hydrogen retards the combustion phase and reduces the duration of combustion.…”

“…To achieve stable HCCI combustion, appropriate control of each region is required. There have ben several reports of investigations of the effects of reformed gas or hydrogen addition on n-heptane fueled HCCI combustion [10,21,31,32,37,38,40,41]. However, these experiments and simulations were performed over a limited range of conditions, and there has been insufficient study of the effects of hydrogen on each region of the combustion process.…”

Investigating various effects of reformer gas enrichment on a natural gas-fueled HCCI combustion engine

“…The chemical effects of RG blending in natural gas-fueled HCCI combustion were investigated in a way similar to the analysis done by Guo and Neil [21] for n-heptane.…”

“…Guo et al also investigated the influence of hydrogen enrichment on the combustion characteristic of n-heptane by using a multi-zone model. They reported that hydrogen addition retarded combustion phasing due to the dilution and chemical effects, and the dilution effect is more dominant because of the introduction of the methods of an artificial inert component [21].…”