Here is the complete information about Lean burn engines. Here we provide Lean burn engines working principle, Advantages and Disadvantages ect.
Lean-burn refers to the burning of fuel with an excess of air in an indoor combustion engine. In lean-burn engines the air:fuel ratio could also be as lean as 65:1 (by mass). The air / fuel ratio needed to stoichiometrically combust gasoline, by contrast, is 14.64:1. the surplus of air during a lean-burn engine emits far less hydrocarbons. High air–fuel ratios also can be wont to reduce losses caused by other engine power management systems such as throttling losses.
Lean Burn Engine
Lean-burn means pretty much what it says. It is a lean amount of fuel supplied to and burned in an engine’s combustion chamber. Normal air-to-fuel ratio is on the order of 15:1 (15 parts air to 1 part fuel). True lean-burn can go as high as 23:1.
Lean-burn engines (both gasoline and diesel) enjoy higher fuel economy and cleaner emissions than conventionally tuned engines. by nature they use less fuel and emit fewer unburned hydrocarbons and greenhouse gases while producing equivalent power of a like-sized “normal” combustion engine. They achieve leanburn status by employing higher combustion chamber compression ratios (higher cylinder pressure), significant air intake swirl and precise lean-metered direct fuel injection.
Working of Lean Burn Engine
Lean-burn engines (both gasoline and diesel) enjoy higher fuel economy and cleaner emissions than conventionally tuned engines. by nature they use less fuel and emit fewer unburned hydrocarbons and greenhouse gases while producing equivalent power of a like-sized “normal” combustion engine. They achieve leanburn status by employing higher combustion chamber compression ratios (higher cylinder pressure), significant air intake swirl and precise lean-metered direct fuel injection.
- A lean burn mode is a way to reduce throttling losses.
- An engine in a typical vehicle is sized for providing the power desired for acceleration, but must operate well below that time in normal steady-speed operation. Ordinarily, the power is cut by partially closing a throttle.
- However, the extra work done in pumping air through the throttle reduces efficiency.
- If the fuel/air ratio is reduced, then lower power are often achieved with the throttle closer to fully open, and the efficiency during normal driving (below the maximum torque capability of the engine) are often higher.
- The engines designed for lean burning can employ higher compression ratios and thus provide better performance, efficient fuel use and low exhaust hydrocarbon emissions than those found in conventional petrol engines.
- Ultra lean mixtures with very high air-fuel ratios can only be achieved by direct injection engines.
- the most drawback of lean burning is that a posh converter system is required to reduce NOx emissions.
- Lean burn engines don’t work well with modern 3-way converter which needs a pollutant balance at the exhaust port in order that they can carry out oxidation and reduction reactions so latest engines run at or near the stoichiometric point.
- Alternatively, ultra-lean ratios can reduce NOx emissions
Engine management
To this end, some car manufacturers are fitting engine management systems where sophisticated electronics control both the ignition and therefore the fuel delivery systems. This makes it possible to form sure that the spark plugs fire at just the proper moment to ignite a fresh fuel/air charge, which can rather be reluctant to ignite.
Also under development are engine parts made from new materials that have greater heat resistance, like pistons made from ceramics. But most development goes into ensuring that the air and fuel are well mixed.
Advantages of lean burn engine
- Higher fuel economy
- Emit fewer unburned hydrocarbons and greenhouse gases
- A lean burn mode may be a way to reduce throttling losses
Disadvantages of lean burn engine
- Lean burning is that a complex catalytic converter system is required to reduce NOx emissions.
- High relatively cost
