Hi Thor: I suspect because it was not heated, as far as I can determine. Thicker oil, poor atomization, less complete combustion....higher emissions. Like all emission studies, there are a lot of variables, and some are discussed in the report (engine type, test cycle used, etc.). Even something as simple as the order in which you test the fuels might affect outcome. For example, start with a "clean" engine, do the diesel tests first, then the biodiesel, then the rapeseed, then rapeseed, biodiesel, diesel (if running just two runs per fuel, for example). You will likely get somewhat different results than in some other order, if the test cycles go long enough that the unheated oil can produce some coking....and so on...everyone tries to do good emission tests, but there are quite a few variables to deal with.
You see in the report, for example, that the authors were quite surprised to find reduced PAH emissions, by a wide margin, for some situations, when the prior literature suggested they would get a large increase instead. So, that was a good finding. Then we get into further discussions of course, such as the fact that a slight timing change can give different results, maybe better for some and worse for others. An obvious but interesting finding (as a reminder) is how emissions decrease nicely on steady-state tests. Which only goes to show that good driver habits can have much to do with emission reductions - maybe more than a particular fuel! (It would be nice to know the correlation between a driver's decision to use a fuel such as SVO and tendency toward also keeping tires inflated, oil changed, keeping the foot off the fuel (except during "tuneups"), and choosing a more fuel efficient vehicle to minimize the need to hunt-and-gather some fuel! It also points to the desirability to run a diesel ..well, any engine on any fuel, actually, at a steady state if possible for most of the time...and use more and closer gearing, CVT's, and finally diesel-electric hybrids. Finally, we can also keep in mind that an engine on SVO, since there is no sulfur in the fuel, is an ideal and easy candidate for fitting of further emission controls - catalytic converters and particulate traps...if we choose. Those won't be ruined and/or plugged up, respectively, like they would by use of high sulfur/higher soot fuel such as fossil diesel in most of USA and Canada at this time at least. Note that while things like acrolein can increase, the authors note that this is not such a cause for concern, in terms of health risk (since it is not persistent, and breaks down very rapidly in the atmosphere, and since the dose would be minimal over time) but might be actually more of a concern in terms of smog formation, but again, that's a result of interactions among a whole host of tailpipe and industrial emissions, VOC's HC, on and on, to form ground level ozone. This is just a quick look at the study, not a proper analysis of it, that's not my intention here, but I'm writing just to give some indication of what I see in it from a quick read. Thanks Edward Beggs On Friday, August 29, 2003, at 02:36 PM, Thor Skov wrote: > WOW!*! > > I just glanced at some of the emissions data in the > Missouri study and was shocked at how poorly SVO > performs. I can't see why I would want to install an > SVO system from an environmental perspective, although > certainly I see the cost savings if you can get your > used oil for free. Biodiesel just seems the much > cleaner alternative. > > Any counter-arguments? Am I missing something? Why > is SVO so darn dirty? > > thor > > -------------------------------------------- > Message: 9 > Date: Thu, 28 Aug 2003 18:16:00 +0100 > From: "Darren Hill" <[EMAIL PROTECTED]> > Subject: RE: UPDATE: Use of vegetable oil in a diesel > engine > > Detrick, > > I just compiled this list for somebody else, I know > you have seen Ed Beggs thesis already but here are the > other sources I could think of. > > For SVO emission data try:- > > http://bengal.missouri.edu/~pavt0689/ > Review_Utilization_of_Rapeseed_Oil.pdf > This is a good source, outrageously big file size due > to bad file formatting. > > Also a part translation of the German page > http://www.biocar.de/download a thesis report > examining emissions from a vehicle equipped with a > Biocar conversion is available from my site:- > www.vegburner.co.uk/biocar if this does not work let > me know. > > http://www.nf-2000.org/secure/Fair/F484.htm > Widely regarded as one of the best PPO technical > papers, has some information on particulate emissions. > > http://www.biodiesel.org/reports/GEN-162.doc > If I remember correctly also contains relevant info. > > Hope these help. > > Darren > > > __________________________________ > Do you Yahoo!? > Yahoo! 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