Optimum Control of an S.I. Engine with a λ=5 Capability

Lumsden, Grant; Watson, Harry C.

doi:10.4271/950689

Cited by 42 publications

(24 citation statements)

References 5 publications

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“…While the diesel truck and gasoline passenger car models are validated versus engine dynamometer data, the LPG truck model is not validated because the DI-JI engine concept is still in a preliminary stage with funding for prototyping and experimental testing still unavailable. However, considering that the predicted fast rates of combustion of the DI-JI engine concept are in line with previous experiments with inhomogeneous charge [19] and homogeneous charge [15][16][17][18][19][20][21] configurations, they are therefore quite reliable; the brake efficiency predictions just follow these fast rates of combustion and share their reliability. The predicted top brake efficiencies, but even more so the predicted part-load efficiencies of the DI-JI LPG engine, are very significant, because they show the opportunity to achieve not only the diesel top brake Computed brake efficiency map of a 4-l, naturally aspirated, stoichiometric gasoline engine for a passenger car (BMEP versus engine speed for various brake efficiencies (per cent)) efficiencies but also the diesel part-load brake efficiencies on igniting with reacting jets controlled by a spark discharge to produce a slightly lean mixture within part of the in-cylinder volume.…”

Section: Previous Experimental and Latest Computational Resultssupporting

confidence: 84%

Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels

Boretti

Paudel

Tempia

2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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Jet ignition and direct fuel injection are potential enablers of higher-efficiency, cleaner internal combustion engines (ICEs), where very lean mixtures of gaseous fuels could be burned with pollutants formation below Euro 6 levels, efficiencies approaching 50 per cent full load, and small efficiency penalties operating part load. The lean-burn direct-injection (DI) jet ignition ICE uses a fuel injection and mixture ignition system consisting of one main-chamber DI fuel injector and one small jet ignition pre-chamber per engine cylinder. The jet ignition pre-chamber is connected to the main chamber through calibrated orifices and accommodates a second DI fuel injector. In the spark plug version, the jet ignition pre-chamber includes a spark plug which ignites the slightly rich pre-chamber mixture which then, in turn, bulk ignites the ultra-lean stratified main-chamber mixture through the multiple jets of hot reacting gases entering the in-cylinder volume. The paper uses coupled computer-aided engineering and computational fluid dynamics (CFD) simulations to provide better details of the operation of the jet ignition pre-chamber (analysed so far with downstream experiments or stand-alone CFD simulations), thus resulting in a better understanding of the complex interactions between chemistry and turbulence that govern the pre-chamber flow and combustion.

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Section: Previous Experimental and Latest Computational Resultssupporting

confidence: 84%

Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels

Boretti

Paudel

Tempia

2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…However, the extent to which swept volume can be reduced in any downsized application is combustion limited. If the combustion in high speed, small bore engines could be better understood or even enhanced to promote faster burning [20,23,26], the severity of end-gas knock could be minimized. This would allow further increases in CR and/or MAP, resulting in increased performance and efficiency.…”

Section: Discussionmentioning

confidence: 99%

Comparing the Performance and Limitations of a Downsized Formula SAE Engine in Normally Aspirated, Supercharged and Turbocharged Modes

Attard¹,

Watson²,

Konidaris³

et al. 2006

SAE Technical Paper Series

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This paper compares the performance of a small two cylinder, 430 cm 3 engine which has been tested in a variety of normally aspirated (NA) and forced induction modes on 98-RON pump gasoline. These modes are defined by variations in the induction system and associated compression ratio (CR) alterations needed to avoid knock and maximize volumetric efficiency (η VOL). These modes included: (A) NA with carburetion (B) NA with port fuel injection (PFI) (C) Mildly Supercharged (SC) with PFI (D) Highly Turbocharged (TC) with PFI The results have significant relevance in defining the limitations for small downsized spark ignition (SI) engines, with power increases needed via intake boosting to compensate for the reduced swept volume. Performance is compared in the varying modes with comparisons of brake mean effective pressure (BMEP), brake power, η VOL , brake specific fuel consumption (BSFC) and brake thermal efficiency (η TH). The test engine used in experiments was specifically designed and configured for Formula SAE, SAE's student Formula race-car competition. A downsized twin cylinder in-line arrangement was chosen, which featured double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. Experimental results showed BSFC or η TH values in the order of 240 g/kWh or 34% could be achieved. TC BMEP values in the region of 25 bar were also achieved, the highest recorded for small engines on pump gasoline [1]. The engine was installed into successive Melbourne University Racing (MUR) vehicles in 2003 and 2004, where it was very competitive, finishing first in the fuel economy event at the 2004 Australasian competition.

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“…There are reports in the literature with a special type of hydrogen addition enabling stable operation at λ=5 [2]. Interesting to note is that in the experiments, the hydrocarbon emissions continued to rise as a function of λ from the minimum at λ=1.3 past the normal lean limit at 1.8, all the way up to 5.0.…”

Section: Basic Effect Of Hydrogenmentioning

confidence: 92%

Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Burning Natural Gas Combustion Chambers

Tunestål¹,

Christensen²,

Einewall³

et al. 2002

SAE Technical Paper Series

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One way to extend the lean burn limit of a natural gas engine is by addition of hydrogen to the primary fuel. This paper presents measurements made on a one cylinder 1.6 liter natural gas engine. Two combustion chambers, one slow and one fast burning, were tested with various amounts of hydrogen (0, 5, 10 and 15 %-vol) added to natural gas. Three operating points were investigated for each combustion chamber and each hydrogen content level; idle, part load (5 bar IMEP) and 13 bar IMEP (simulated turbocharging). Air/fuel ratio was varied between stoichiometric and the lean limit. For each operating point, a range of ignition timings were tested to find maximum brake torque (MBT) and/or knock. Heatrelease rate calculations were made in order to assess the influence of hydrogen addition on burn rate. Addition of hydrogen showed an increase in burn rate for both combustion chambers, resulting in more stable combustion close to the lean limit. This effect was most pronounced for lean operation with the slow combustion chamber.

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Optimum Control of an S.I. Engine with a λ=5 Capability

Cited by 42 publications

References 5 publications

Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels

Experimental and computational analysis of the combustion evolution in direct-injection spark-controlled jet ignition engines fuelled with gaseous fuels

Comparing the Performance and Limitations of a Downsized Formula SAE Engine in Normally Aspirated, Supercharged and Turbocharged Modes

Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Burning Natural Gas Combustion Chambers

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