Diesel Exhaust Pollutants

Basics

• This page lists the various directly harmful (ie not: nitrogen, oxygen, argon, co2) emissions from diesel engines (and many other ice's)
• This is mainly as a lead in for Catalytic Converters , Diesel Particulate Filters, and Diesel Exhaust Fluid + Selective Catalytic Reduction systems
• Isn't too much of a small scale issue, but with a highway full of cars etc, it builds up
• IS FIXABLE, but there are many issues involving a Developer-User Disconnect Issues (may need better name) where it works on paper, but not i certain real life situations, or logistical issues of the supplies/maintenance needed, or hard to maintain systems etc

Emissions

Nitrogen Oxides

• Nitrogen Oxides
• Often Abbreviated as NOx
• Caused by nitrogen and un-combusted oxygen being heated in the combustion chamber and reacting to form nitrogen dioxide, tridoxide etc\
• Main solution is Catalytic Converters, although others can be implemented depending on the predicted amounts produced (a sort of balancing act for the others)
  • The type of catalytic converter that does this "three way converter" doesn't work with high exhaust oxygen, as it would react with the catalyst

Soot

• Caused by incomplete combustion due to too little oxygen
• Mainly Carbon Black , but due to the impure nature of the fuel, and the combustion environment, it can often contain heavy metals, and other pollutants
• Balancing act here is lower oxygen in the ratio means less "pre-treatment system" NOx but more soot etc
• Thus either a perfect to lean fuel-oxygen ratio, or a Diesel Particulate Filter is needed
• For more in depth information on this, see Atmospheric Particulate Matter

Misc

• Other combustion products
• Various hydrocarbons

Solutions

• Unlike Spark Ignition Engines , Compression Ignition Engines run too lean to use standard Catalytic Converters (known as "Three Way Catalytic Converters")
  • This issue also exists for Lean Spark Ignition Engines
• Thus alternative Pollution Control Systems are needed
• Both systems control Particulate Matter via a Diesel Particulate Filter
• How they handle NOx emissions varies, but these mainly include:
  • Diesel Oxidation Catalysts
  • Selective Catalytic Reduction
    • Which necessitates a continuous (albeit rather small) supply of Diesel Exhaust Fluid

also tend to not work well with diesel engines due to the exhaust oxygen percentage

Diesel Oxidation Catalyst

• These typically also include a NOx Absorber allowing it to run in a cyclical manner similar to that of a Three Way Catalytic Converter
• These utilize a reducing agent, typically Carbon Monoxide / Unburnt Hydrocarbons from a rich mixture to oxidize the NOx to Nitrogen and CO2

Selective Catalytic Reduction

• Essentially a Gas Scrubber but scaled down to car etc sized
• Some SERIOUS logistical issues (no nearby places to buy the fluid, no "emergency" mode due to software locking etc)
• Some design issues (design allowing for easy accidental mixing, little storage, no way of knowing if the fluid is "not expired" ie all the ammonia has evaporated off)
• If improperly managed can emit ammonia gas (this is an issue of management of the system however)
• Educational Issues (people don't know what it does, think it's a gimmick, using expired fluid etc)
• It is a workable solution, just needs better design (WITH user feedback), logistical fixes, and ease of use (that or use another system if this proves to be the more difficult option)

Exhaust Gas Recirculation

• Does work, is commonplace, main issue is lower efficiency?

Internal Links

• Biodiesel
• Diesel Engines
• Diesel Exhaust Fluid

External Links

• The Wikipedia Page on Diesel Exhaust Pollutants
• The Wikipedia Page on "Clean Diesel Technologies" (A group making emissions control systems for heavy duty and light duty diesel vehicles) (May make a page on this group later?)
• On why three way converters are hard to use in diesel engines
• Moreso A Testament to the tech in said pickup truck, BUT "Leaf Blower's Emissions Dirtier than High-Performance Pick-Up Truck's, Says Edmunds' InsideLine . com"