An HCCI Engine Fuelled with Iso-octane and Ethanol

Gnanam, G.; Sobiesiak, Andrzej; Reader, Graham T.; Zhang, C.

doi:10.4271/2006-01-3246

Cited by 13 publications

(10 citation statements)

References 10 publications

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“…In both cases, a single direct-injected pulse was used [23]. The effect of fuel stratification on combustion development is well described in the work performed by Sjöberg et al [23], Dec et al [24] and Yang et al [25][26][27]. The multizone chemical-kinetics modeling study carried out in [23] demonstrates that, for fuels with sufficient sensitivity to the local φ (diesel-like fuels), fuel stratification promotes a staged combustion event with reduced pressure rise rates (PRR), which allows increasing the load limits of HCCI operation.…”

Section: Fuel Stratification Using Direct Injectionmentioning

confidence: 80%

“…In particular, this concept operates combining PCCI combustion at low load with diffusive diesel combustion at high load conditions [27]. The authors of that work found that this type of combustion process allows reducing cooling losses from the typical values of 35% [28] up to only 20% of the total fuel energy.…”

Section: Piston Geometry Modificationmentioning

confidence: 99%

“…In particular, the great evolution of the injection systems has enabled the use of higher injection pressures, lower nozzle holes diameters, higher number of orifices and multiple injections, which have had a key role on improving the mixture formation [24,25]. Also, the optimization of the piston shape for improving the spraybowl interaction and the air flow movement inside the combustion chamber has contributed greatly to soot formation reduction [26,27].…”

Section: In-cylinder Strategies For Soot Emissions Controlmentioning

confidence: 99%

“…Thus, in order to reduce the convective heat transfer, several piston designs aimed at suppressing reversed squish flow, which promotes the high temperature gas flowing along the side wall of the cavity to the squish region during the descent of the piston, were explored. The different approaches studied in [27] are shown in figure 5.6. As can be seen, the stepped geometry proposed by Toyota is similar to the chamfered re-entrant bowl resulting from the CFD optimization work performed in [25,26].…”

Section: Piston Geometry Modificationmentioning

confidence: 99%

“…The next subsections present a brief description of the modeling methodology, highlighting its different steps and the submodels used in the code. Nevertheless, the reader is invited to consult the literature to deepen on this computational code [27].…”

Section: -D Computational Fluid Dynamics Modelmentioning

confidence: 99%

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Dual-fuel compression ignition: towards clean, highly efficient combustion

Monsalve¹

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The more and more stringent emissions regulations, together with the greater fuel economy demanded by vehicle users, impose a clear objective to researchers and engine manufacturers: look for the maximum efficiency with the minimum pollutant emissions levels.The conventional diesel combustion is a highly efficient process, but also leads to high levels of NOx and soot emissions that require using aftertreatment systems to reduce the final levels released to the environment. Since these systems incur in higher costs of acquisition and operation of the engine, the scientific community is working on developing alternative strategies to reduce the generation of these pollutants during the combustion process itself.The literature shows that the new combustion modes based on promoting low temperatures during this process, offer high efficiency and very low NOx and soot levels simultaneously. However, after years of investigation, it can be concluded that these techniques cannot be applied in the whole engine operating range due to, among others, factors like the low control of the combustion process. In recent years, it has been demonstrated that the dual-fuel combustion technique allows to overcome this limitation thanks to the additional degree of freedom provided by the capacity of modulating the fuel reactivity depending on the engine operating conditions. This characteristic, together with the near-zero NOx and soot levels obtained with this technique, has encouraged the scientific community to deeply investigate the dual-fuel combustion. In this sense, former works confirm the advantages previously described, concluding that still exist some limitations to be tackled, as well as some margin for improving the potential of this combustion concept.The general objective of the present doctoral thesis is to contribute to the understanding of the dual-fuel combustion mode, with the particular aim of exploring different ways to improve its efficiency. For this purpose, it has been experimentally evaluated different options such as the modification of the engine operating parameters, specific designs of the piston geometry or the use of alternative fuels.With the aim of answering some of the questions found in the literature, the first part of each study has been dedicated to perform a detailed analysis of the influence of each particular strategy on the dual-fuel operation at low load. Later, it has been checked the ability of each option to extend the dual-fuel operating range towards higher engine loads. It is interesting to note that the analysis of some results has been supported by CFD calculations, which have allowed to understand some local phenomena occurring during the dual-fuel combustion process, which cannot be confirmed only from the experimental point of view.Finally, taking into account the knowledge acquired during the different studies performed, the last chapter of results has been devoted to evaluate the ability of the dual-fuel concept to operate over the whole engine map, as well as to iden...

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