![]() ![]() ![]() On diesel engines, the lambda number can be used as the basic value for setting the smoke limit at full load. The lambda number represents the setpoint control value for both exhaust recirculation and catalytic exhaust gas scrubbing. The residual NO x in the stream of exhaust gas can be held in the NO x storage catalytic converter, until it can be reduced to nitrogen during phases of rich combustion. Exhaust gas recirculation is a means of reducing the combustion temperature, along with the NO x proportion of emitted exhaust gases. Diesel engines or gasoline engines with direct injection are operated with a lean combustion across a wide load range, with the nitrogen oxide (NO x) content of emissions steeply rising in conjunction with the increasing combustion temperature. The process enriches the exhaust gases in a proportion suitable for optimal processing by three-way catalytic converters. The classic lambda closed-loop control provides a stoichiometric air-fuel mixture for combustion in spark ignition engines. A reading of λ 1 indicates an excess of air (lean mixture). When λ=1, ideally balanced combustion conditions result in neither oxygen starvation nor excess. The air-fuel ratio, or lambda number (λ) determines the mass ratio of air and fuel in the combustion chamber, as it relates to the stoichiometric air-fuel ratio. Oxygen probes – also referred to as lambda sensors – measure the oxygen contained in automotive exhaust emissions. ![]()
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