Hi Pierre >I just viewed the Iowa state U biodiesel web site video: > >http://www.me.iastate.edu/biodiesel/ > >At one point in the video, the narrator states that reaction will >complete at room temp, as long as stirring is longer (1-2 hours at >140 F, 2-4 hours at 105 F, 4-8 hours at room temp.) > >If so, why bother with heating? just stir it longer? > >Pierre
You might like to have look at this, as well as the two papers with it: The modelling of the biodiesel reaction http://journeytoforever.org/biofuel_library.html#macromodel Kinetics of Transesterification of Soybean Oil http://journeytoforever.org/biofuel_library.html#nour Kinetics of Palm Oil Transesterification in a Batch Reactor http://journeytoforever.org/biofuel_library.html#kinetics The macromodel is a spreadsheet of the various parameters in a reaction. Lower the temp and the time goes up etc. I think there are some spikes and dips though. For instance, what's room temperature, 77F? The lower it gets, the higher the viscosity, which could have a bearing on your mixing, perhaps meaning longer times than you'd think. Or perhaps it just might not mix as thoroughly. Look at the time variations they gave you, all with a 100% variation - there's a rather large difference between four hours and eight hours. The various methods say various things about mixing times, 1 hour at 55 deg C for single-stage base is common, but they're just ballpark figures really, there for guidance - what size is the reactor? What shape is it? What sort of mixer? There are a lot of variables. In the end you have to work it out for yourself, according to your particular set-up, using all these figures as guidance. So: >If so, why bother with heating? just stir it longer? Give it a try. It might not work out quite as you expect. On the other hand, it might. That's not meant to be discouraging, we've worked at room temperature and lower and had good results. But it might not be as simple as it looks. There definitely are people who process at room temperature and lower and do not get good results, poor conversion for instance. Best wishes Keith ------------------------ Yahoo! Groups Sponsor ---------------------~--> Yahoo! Domains - Claim yours for only $14.70 http://us.click.yahoo.com/Z1wmxD/DREIAA/yQLSAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
