Study on Improvement of Natural Gas Fueled Spark Ignition Engines -Effect of EGR Utilization-

Sakonji, Tatsuo; Shoji, Fujio

doi:10.4271/971714

Cited by 14 publications

(1 citation statement)

References 2 publications

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“…This can be accomplished by changing the charge composition and thus changing the flame speed. Grandin and co-workers [6,7] and Sakonji and Shoji [8] investigated changing the composition by cooled exhaust gas recirculation (EGR) in a turbocharged engine. It was found that knock occurred at a higher indicated mean effective pressure (i.m.e.p.)…”

Section: Introductionmentioning

confidence: 99%

A study of the influence of exhaust gas recirculation and stoichiometry on the heat release in the end-gas prior to knock using rotational coherent anti-Stokes-Raman spectroscopy thermometry

Grandin

Denbratt

Bood³

et al. 2002

International Journal of Engine Research

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Heat release in the end-gas prior to autoignition was investigated using different experimental methods including transducers for heat flux and pressure as well as rotational coherent anti-Stokes-Raman spectroscopy, which is a laser-based method for non-intrusive instantaneous thermometry of the gas. The time history was examined in the cases of mixtures of various stoichio-metries, where some were diluted with exhaust gas recir-culation (EGR). The measured temperature history was compared with the isentropic temperature calculated from the cylinder pressure trace. This comparison revealed a difference in heat release from low-temperature reactions in the end-gas for the various mixtures tested at a constant indicated mean effective pressure and a fixed position of 50 per cent burnt charge. It is shown that lean mixtures tend to exhibit the highest knock intensity, mainly due to a decrease in specific heat, as compared to the richer mixtures, which result in an earlier knock onset and as a consequence higher knock intensity. Furthermore, the comparison of temperatures indicates that the rich mixtures have a high heat release from low-temperature chemistry, which to some extent negates the higher specific heat of the charge. As a consequence, a slight enrichment of the charge can lead to higher knock intensity in comparison with a stoichiometric mixture. In spite of the lower specific heat of the charge when a stoichiometric charge was diluted with cooled EGR, these mixtures showed a very low tendency to knock.

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Section: Introductionmentioning

confidence: 99%