(please note, this is not my work, just a copy from elsewhere on the internet)
The properties of canola oil and diesel are very similar, except a significant difference in viscosity, with canola oil having 12 times the viscosity of diesel. Even after heating to around 80 deg C it is still six times as viscous as diesel. This leads to problems with flow of oils from the fuel tank to the engine, blockages in filters and subsequent engine power losses. Even if preheating is used to lower the viscosity, difficulties may still be encountered with starting due to the temperatures required for oils to give off ignitable vapours. Further, engines can suffer coking and gumming which leads to sticking of piston rings due to multi-bonded compounds undergoing pyrolyses. Polyunsaturated fatty acids also undergo oxidation in storage causing gum formation and at high temperatures where complex oxidative and thermal polymerisation can occur.
To date there have been many problems found with using vegetable oils directly in diesel engines (especially in direct injection engines).
1. Coking and trumpet formation on the injectors to such an extent that fuel atomisation does not occur properly or is even prevented as a result of plugged orifices,
2. Carbon deposits,
3. Oil ring sticking,
4. Thickening and gelling of the lubricating oil as a result of contamination by vegetable oils, and
5. Lubricating problems.
Other disadvantages to the use of vegetable oils and especially animal fats, are the high viscosity (about 11 to 17 times higher than diesel fuel), lower volatilities content which causes the formation of deposits in engines due to incomplete combustion and incorrect vaporisation characteristics... At high temperatures there can be some problems with polymerisation of unsaturated fatty acids, this is where cross-linking starts to occur between other molecules, causing very large agglomerations to be formed and consequently gumming occurs.
-- From "Research into Biodiesel Kinetics and Catalyst Development", by Adam Karl Khan, Department of Chemical Engineering, University of Queensland, 17 May 2002 -- Acrobat file, 432Kb:
http://www.cheque.uq.edu.au/ugrad/ch...han_Thesis.pdf
MrMoMo
DD, WVO soon!
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Linear Mode
