Oxides of nitrogen in Petrol engine exhaust can be reduced by the following methods: 1. Use of 5% lean mixture 2. Advancing the spark timing 3. Recirculating a fraction of exhaust gas 4. Using an oxidation catalyst in the exhaust manifold Which of the above statements is/are correct?

1 and 2
2 only
3 and 4
3 only

LohaHridoy

4 views

2025-01-04 04:42

1 Answers

AhmedNazir

Option 4 : 3 only

Formation of oxides of Nitrogen: Oxides of nitrogen, nitric oxide (NO) and nitrogen dioxide (N0₂) are formed by the oxidation of the nitrogen in the combustion chamber. (NO) The formation is favored by high temperatures and pressures found in the combustion chamber as well as lean (oxygen-rich) fuelling conditions.

Technologies to control the emission of oxides of nitrogen in petrol engines

Control of combustion: The quantity of NO formed in a petrol engine depends upon the combustion parameters and, to a certain extent it can be controlled by adjustment of the engine operation. The NO formation in petrol engines can be controlled by retarding the spark timing.
Exhaust gas recirculation: Exhaust gas recirculation is NO_x-reduction technique, it works by redirecting a portion of the engine exhaust gas back into the combustion chamber where it is mixed with the fresh fuel-air mixture. It is done by adjusting the exhaust valve timing so that some of the combusted gas is trapped in the cylinder. This residual gas acts as a diluent for the next combustion cycle, hence lowering the combustion temperature.
Three-way reduction catalytic convertor: The TWC is a robust technology for reducing emissions of No_x, carbon monoxide (CO) and hydrocarbons (HC) (hence the name "three-way").

4 views Answered 2022-09-04 04:29

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