EGR & NOx Emissions: Test Results & Explanation

  • Thread starter Ali Durrani
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In summary, the speaker has conducted tests on Exhaust Gas Re circulation (EGR) on their engine test bench and noticed unusual results at 8% loading conditions. The trendlines on the graph showed an increase in NOx with EGR, which the speaker is looking for an explanation for. The suggestion is made to check the fuel map for the engine and consider the impact of volumetric efficiencies and AFR on NOx production. Additionally, the speaker recommends running tests with a wide band O2 sensor and an Exhaust Gas Temperature sensor to further evaluate and understand the results.
  • #1
Ali Durrani
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Hello
i have done tests on Exhaust gas re circulation on my engine test bench and these are the results, i don't know what's wrong? but at 8% loading conditions i am getting some weird results
the trendlines in the graph shows an increase in NOx with EGR
is there any explanation for this ? thanks
 

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  • #2
Do you have access to the fuel map for the engine you are using? NOx production is indirectly related to the Stoichiometric ratio. At different volumetric efficiencies the AFR tends to migrate. This is often due to the Map used in the Engine Control Unit. Some of them use a grid as small as 16x16 to cover all load and RPM conditions. This can lead to wandering results which are occasionally cyclic.
I would suggest running tests with a wide band O2 sensor to evaluate mixture and again with an Exhaust Gas Temperature sensor to look for variations and effects that may be contributing.
 

Related to EGR & NOx Emissions: Test Results & Explanation

1. What is EGR and why is it important for emissions?

EGR stands for Exhaust Gas Recirculation, and it is an emission control technology used in vehicles to reduce the production of harmful nitrogen oxides (NOx). It works by recirculating a portion of the exhaust gases back into the engine, which lowers the combustion temperature and reduces the amount of NOx produced.

2. How is EGR and NOx emissions tested?

EGR and NOx emissions are typically measured using a dynamometer test, where the vehicle is placed on a treadmill-like machine and driven through a standardized driving cycle. The exhaust gases are then analyzed to determine the levels of NOx emissions. Alternatively, some vehicles may have on-board diagnostic systems that continuously monitor and report the emissions levels.

3. What factors can affect EGR and NOx emissions?

The amount of EGR used in the engine, the driving conditions, and the engine operating temperature can all affect the levels of EGR and NOx emissions. Other factors that may impact emissions include the type of fuel used, the quality of the engine's combustion, and the condition of the vehicle's emission control system.

4. What levels of EGR and NOx emissions are considered acceptable?

The acceptable levels of EGR and NOx emissions vary by country and region, as each has its own regulations and standards. In general, newer vehicles are required to have lower emissions levels than older vehicles, and diesel engines usually have stricter standards than gasoline engines.

5. How can high levels of EGR and NOx emissions be reduced?

There are several ways to reduce EGR and NOx emissions, including using a catalytic converter, improving engine design and combustion efficiency, and using alternative fuels. Regular maintenance and tuning of the vehicle's emission control system can also help to keep emissions levels within acceptable limits.

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