Reducing NOX emissions in gasoline engines. 1

[bayislandsdiver]

I am an automotive technician specializing in European performance cars including but not limited to Porsche, Mercedes, BMW, Jaguar, Volvo, etc..

In Houston, Texas the emissions testing for cars now includes a "dyno test" under load while measuring exhaust emissions.

The "dyno" runs at low speed during the test and tends to load the engine as if the vehicle was climbing a steep hill in high gear.

Some of the performance cars I am working on (Porsche, Turbo Volvo, Jaguar) have a hard time passing the NOX emission standard.

If I add a small amount of alcohol while the engine is running under load can it reduce the combustion temperature and reduce the NOX output?

As I have also been toying with a water injection system to increase mileage, wouldn't this water injection system also reduce the NOX?

Any comments on my questions, or any other thoughts or experience with this problem are welcome.

Bay Islands Diver

 

[joshisb]

as asked about water injection, during second world war this water injection help to reduce temperature of combustion naturally decrease the NOx emission.NOx depends on temperature

 

[alochin]

I used water injection in my car, and it can be done simply for about $20.
My car was dieseling all the time. Now it runs smooth.
I live in the woods, I don't have to pass emissions, but I can tell you that the engine runs much better. Just for that, you can always try water injection and see if it helps for NOx (it should).

How I did it for $20:
A water bottle
A 1/8" check valve
Two 1/8" brass needle valves, a 1/8" brass tee.
A plastic Tee that will fit your PCV line with a 1/8" barb in the center.
A length of 1/8" ID plastic tubing.

The 1/8" tubing goes directly to the bottom of the water bottle, with the check valve at the end in the water.
I use 2 needle valves and a tee to mix water and air, it makes it easier to adjust the water flow (compared to just one needle valve). The water inlet (from the bottle) goes into 1 branch of the tee. A needle valve draws air in another branch, and the water+air mix exits through the second needle valve, to the tee connected to the PCV line.

This is a $20 ghetto system. You can buy a system quite similar, professionally build, on line for $400 (check Aquatune.com).

Just with that, you will not feel much difference in how the engine is runing, but you will greatly decrease combustion temperature (assuming the water/air mix is correct). You can also advance your timing (I advance mine by ~6°) and get more power and mileage, but this might put you back where you were in term of temperature and NOx.

 

[Charles]

To reduce NOx and SOx in my car, I use a fuel catalyst additive by the name of Green Plus. They have a website:

http://www.biofriendly.com

- the site will give you contact information for both the US and UK.

In addition to reduced emissions, I also get a ~5% reduction in fuel consumption under normal driving conditions.

Charles

http://www.polarchem.com

 

[enginead]

Bayislandsdiver,

The chemistry and physics of NOx formation in internal combustion engines is well understood to be a rate controlled reaction (ie it never gets to equilibrium conditions) variable as a function of temperature and component availability (i.e. N, N2, O & O2). Although the activation temperatures for these reactions are normally very high (>1000°C), in the presence of a catalyst like Rhodium this temperature drops to ~<300°C. This means that NOx is constantly being created and destroyed in a rate controlled way as described earlier. One thing that is clear is under rich conditions there is insufficient O2 available to oxidise all of the carbon and hydrogen to CO2 & H2O. Thus under these conditions, the rate controlled formation/destruction of NOx that determines the overall concentration will be geared towards destruction as the formation will be limited by the ever decreasing availability of O & O2 (i.e. this will be used to oxidise HC and CO) hence you reduce (in absolute terms as well as chemically) NOx emissions. What's not so well understood (at least by me) is the detailed chemistry and interactions between different catalyst formulation/washcoat/loading combinations and their effect on NOx reduction (LEVII propoed emission limits planned for MY2007 will put pressure on this lack of information as NOx emission limits are very low)