Lean Burn Combustion

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Lean burn refers to the use of lean mixtures in an internal combustion engine. The air-fuel ratios can be as high as 65:1, so the mixture has considerably less fuel in comparison to the stoichiometric combustion ratio (14.7:1 for petrol for example). Contents[hide] * 1 Principle * 2 Chrysler Lean Burn computer * 3 Heavy-duty gas engines * 4 Honda lean burn systems * 4.1 Applications * 5 Toyota lean burn engines * 5.1 Applications * 6 Nissan lean burn engines * 6.1 Applications * 7 Mitsubishi Vertical Vortex (MVV) * 8 Diesel engines * 9 See also * 10 Footnotes * 10.1 Citations * 10.2 References |
[edit] Principle
A lean burn mode is a way to reduce throttling losses. An engine in a
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Heavy-duty lean burn gas engines admit as much as 75% more air than theoretically needed for complete combustion into the combustion chambers. The extremely weak air-fuel mixtures lead to lower combustion temperatures and therefore lower NOx formation. While lean-burn gas engines offer higher theoretical thermal efficiencies, transient response and performance may be compromised in certain situations. Lean burn gas engines are almost always turbocharged, resulting high power and torque figures not achieveable with stoichiometric engines due to high combustion temperatures.
Heavy duty gas engines may employ precombustion chambers in the cylinder head. A lean gas and air mixture is first highly compressed in the main chamber by the piston. A much richer, though much lesser volume gas/air mixture is introduced to the precombustion chamber and ignited by spark plug. The flame front spreads to the lean gas air mixture in the cylinder.
This two stage lean burn combustion produces low NOx and no particulate emissions. Thermal efficiency is better as higher compression ratios are achieved.
Manufacturers of heavy-duty lean burn gas engines include GE Jenbacher, MAN Diesel & Turbo, Wärtsilä, Mitsubishi Heavy Industries and Rolls-Royce plc.
[edit] Honda lean burn
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