Waste Vegetable Oil As A Diesel Replacement Fuel

Index of Waste Vegetable Oil As A Diesel Replacement Fuel
Introduction
Properties of Triglycerides as Fuels
Oils and their melting point and Iodine Values
In Car installation
Problems Costs Exhaust emissions and Cost efficiency
Saturated oils and possible improvements

Saturated oils:

The use of saturated (solid) fats in cooler months would require significant improvements to the heat exchanger in the oil tank. Palm oil tended to solidify in the filter (prior to a glow plug heater being installed) and in the front half of the tank while travelling, reducing useable capacity. This may be less of a problem if a 6 port solenoid valve were to be used, circulating heated oil back to the tank, and improving the heating of the oil in the tank.
Carbon build up causing wear: Reports have been made of accelerated engine wear due to increased carbon deposits in combustion chambers. As the engine condition at the start of the test was not accurately measured, no proper evaluation of the wear can be made. However, at the end of the vehicle life, the engine will be dismantled and evaluated for any abnormal evidence of wear or damage.
Galvanised Fuel tank: The oil tank was made from scrap galvanised steel sheet metal. It was found that the oil reacted with the zinc plating and this resulted in globules of reacted oil blocking the fuel filter on many occasions. The oil tank was consequently removed, cleaned and acid etched to remove the zinc coating.
No reacted fuel globules have been observed since.

Possible improvements

Solenoid Valve: The use of a six port solenoid valve and an alterative fuel line set-up would reduce the shutdown delay requirement, as the return line would not be fed back into the fuel pump.
Fuel filter: The provision of a heated fuel filter, using filter elements giving 5 micron filtration would protect the fuel pump from the possible 5 – 30 micron particles not removed by the Ryco Z30 filter. Filter heating would be most effective if heated by engine coolant.
Biodiesel: Starting the vehicle on biodiesel would further enhance the environmental benefits obtainable.

Conclusion

Many vegetable and animal oils can be used as diesel replacement fuels. The two ways of doing this are to either use the oil as a straight fuel or to convert the oil to a methyl or ethyl ester (biodiesel). Both of these ways have various advantages and disadvantages. One of the authors (Clark) converted a Mazda 626 to operate on straight vegetable oil and has done over 7500 km using this method. The other author (Calais) has been using biodiesel in an unmodified Toyota Corolla for over 20,000 km.
In converting the Mazda 626 to operate on straight oil, a small tank was fitted under the bonnet of the vehicle. In order to minimise fuel ‘ cold-plugging’ problems due to high fuel viscosity, both the tank, filter and fuel lines are heated.
The vehicle is first started on diesel and then when the engine has reached normal operating temperature and the oil has been heated, a solenoid valve is operated which switched the fuel system over to the oil.
To date there has been no evidence of increased engine wear, lubricating oil dilution or other problems. However the experience of others has shown that increased engine wear may occur but as yet it is still too early to determine whether or not this will occur in this example. Even so, the economic benefits obtained by using waste canola oil may more than offset any extra engine maintenance costs.
It is hoped that continuing research on this project may provide more information about this in the future.

<< last page - index - next pvage >>