Biodiesel is an oxygenated fuel which contains 10–15% oxygen by weight. These facts lead biodiesel to total combustion and less exhaust emissions than diesel fuel.But how does NOx emission only increased? Not CO,CO2, HC emissions.what are the technologies are followed to minimize the NOx emission?
Use of biodiesel produces more NOx because biodiesel contains oxygen within it. When sufficient oxygen is present, complete combustion takes place which in turn will raise the temperature of products above a certain Adiabatic Flame Temperature level. Thermal NOx is mainly responsible due to presence of fuel bound oxygen in it. So higher the oxygen higher the NOx.
Dear Lucas,
please follow this older thread
https://www.researchgate.net/post/Any_suggestions_on_why_some_biodiesels_emit_higher_NOx_compared_to_Diesel
it explains nicely reasons why and actions to reduce NOx
best regards
Johannes
Biodiesel contains oxygen atoms, it is said to be oxygenated, which is not the case for commercial diesel. The combustion in diesel engines is done in poor diet (more oxygen than gazole ). Burning in poor conditions generates high temperatures. The combustion of biodiesel sufficiently oxygenated generates high temperatures which favor the production of NOX. It is therefore the high temperature of the combustion chamber which, in the presence of hight quantity of air, favors the production of NOX. To reduce NOx in this case it is necessary to:
1- Use the microemultion technic(the use of sulphactants is recommended as an anhydrous alcohol)
2- Inject a cloud of water during combustion to lower the temperature of the combustion chamber
3- Using the technic of burned gases recirculation EGR
4- Blends Biodiesel with ethanol
Because of its higher oxygen content. the oxygen content acts in two different ways;
1. Reducing carbon emissions except CO2
2. Increasing the NOx emissions
CI engines work on lean mixtures that means more O2 and N2.
In CI engines, the tendency to get soot is high and these soot particles act as hot spots that radiate heat and increase NOx
The higher oxygen content of biodiesel encourages the formation of NOx .
NOx formation in diesels is dominated by the Zeldovich mechanism
https://www.researchgate.net/publication/357737638_Effects_of_Physico-Chemical_Properties_of_the_Blended_Diesel_and_Waste_Cooking_Oil_Biodiesel?_sg%5B0%5D=252Bx9TOIqecjgLbiBFGFMcN4E_IE7kAT-cZTw8712DOcQaonJDowTTwhF6-YPky_E9LuG2IdThQU_FZFrZ3YC1mFJrRb4We6jyRJ3yE.bHwkXyQwBEXygNcSC9gn_7_NVQI_pNr8n_Xd9RD-Tq5yPVaKmZL976gc0rTJOy6mjIbLdd1TazPSbiJmf8S33Q
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