Bruce Amacker Posted October 19, 2010 Share Posted October 19, 2010 Hay Guys: There's a good video on YouTube regarding DEF usage that you could play for your customers who refuse to RTFM. http://www.youtube.com/watch?v=GF5Oggb7gUk Have fun! Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 20, 2010 Share Posted October 20, 2010 Good find Mr Bruce. It is not technical but definitely informative - I am sure it is intended for the general public. I thought it would be good to share with our readers so I embedded the video on the DTS front page. (1170) Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted October 21, 2010 Share Posted October 21, 2010 Keith, Can you refresh one who isn't fully versed? I read the front page and I thought the DEF is water and Urea, which is then converted to Ammonia in the SCR cat which separates the nitrogen and oxygen to eliminate the NOx. Please enlighten me. Thanks Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 21, 2010 Share Posted October 21, 2010 Fred, did you mean the DTS front page? It does not state that SCR converts urea into ammonia. Urea is ammonia but depending on what you read you may discover descriptions that state urea is a compound mixture of ammonia and nitrogen which I believe is for agricultural use. I have never read anything (in Ford related materials) that there is any process that "converts" DEF into ammonia. The only real question I have at this moment is what role the water plays if any other than to make the fluid less hazardous to us humans? I am assuming that "chemically pure urea" means ammonia which is pretty nasty stuff! The chemical conversion I continually see for SCR is NH3 + NOx = N2 + H2O and a trace amount of CO2. [*]NH3 = Ammonia [*]NOx = Oxides of Nitrogen (the bad stuff) [*]N2 = Nitrogen [*]H20 = Water [*]CO2 = Carbon Dioxide I have read references to "hydrolyzing" but that is as far as it goes with no additional explanation. I myself am not sure if the process is as simple as I have described above or if there is more to it... which is why for now i am keeping anything I write as simple as I can. Call it dummed down if you want. DEF, ammonia, urea and Reductant are all words that seem to be generally interchangeable. I chose the word ammonia because that is the chemical that is reacting with the NOx. If there is a large enough consensus that urea would be a better choice of a word I have no problem changing it. If I am wrong about any of this someone please correct me. Anyone with additional references or materials on this subject please feel free to share. I am glad we are diving into this. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted October 21, 2010 Author Share Posted October 21, 2010 The chemical conversion I continually see for SCR is NH3 + NOx = N2 + H2O and a trace amount of CO2.I'm not a chemist but this is also what I understand-NH3 and NOx into the SCR cat, N2 and H2O come out the end DEF and Nitric Oxide go into the SCR cat, Nitrogen and water come out A page from my Diesel Emissions book: Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 21, 2010 Share Posted October 21, 2010 So I understand this correctly AND it really is that simple. Yes? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted October 21, 2010 Author Share Posted October 21, 2010 I don't see any reason to complicate it, and yes, I think it's that simple. Quote Link to comment Share on other sites More sharing options...
rlchv70 Posted October 21, 2010 Share Posted October 21, 2010 Yes and no. Greatly simplified, it is true. However, the details are more complicated. First, Urea is not ammonia. It is (NH2)2CO. It has to be heated by the exhaust gasses to break down into ammonia. The reactions are more complicated than shown and require the SCR catalyst to occur. More info: http://en.wikipedia.org/wiki/Selective_catalytic_reduction Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 21, 2010 Share Posted October 21, 2010 I knew it was too simple to be true. Thank you for chiming in. I guess then urea would actually be the most accurate term then. Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted October 22, 2010 Share Posted October 22, 2010 Thanks for the links and descriptions. I'm trying to keep up as best I can with all the new technology coming out. Since I was looking around, why doesn't this work with all diesels? Or is this catalyst technology just too expensive. It doesn't require any urea injection. Its from '06 as well. http://world.honda.com/news/2006/c060925DieselEngine/ Quote Link to comment Share on other sites More sharing options...
rlchv70 Posted October 22, 2010 Share Posted October 22, 2010 I believe that this is a NOx absorber. The issue with it is expense of the catalyst and additional fuel consumption since you have to regen it like a DPF. Also, it only works well on light load factor usage. The Dodge Ram 2500 and 3500 pickups use this technology. More info: http://en.wikipedia.org/wiki/NOx_Absorber Quote Link to comment Share on other sites More sharing options...
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