Straight Vegetable Oil (SVO) systems
For diesel engines, there are two main fuel alternatives to diesel. The first approach is to modify the fuel to run in the vehicle (which is bio-diesel) and the second approach is to modify the fuel delivery system to use Straight Vegetable Oil. (SVO).
With a SVO system it is necessary to reduce the viscosity of the vegetable oil by heating the vegetable oil.
Generally the main components of a SVO system are:
1- A second fuel tank
2- A fuel solenoid valve to switch between the main tank (diesel/bio-diesel) and secondary tank (vegetable oil)
3- A method for heating the oil
There are a number of SVO systems available worldwide, that have been in use for a number of years. The idea of using heated vegetable oil as an alternative fuel is not a new one and has been used successfully in Europe for a number of years. In Germany, there are actually small groups of farmers (2-4) who grow rapeseed, crush the oil themselves with their own oil expeller, feed the meal to their own livestock, and then use the oil in their farm machinery.
It was at the World Exhibition in Paris in 1900, that Dr Rudolph Diesel showed his diesel engine, an engine that was capable of running on a variety of fuels including peanut oil. Later on, Dr Diesel went on to say, “the diesel engine can be fed with vegetable oils and would help considerably in the development of agriculture of the countries that use it.” Rudolph also believed that it was possible vegetable oil as a fuel would be as important as petroleum and coal tar products.
In his book, “From the Fryer to the Fuel Tank”, Joshua Tickell outlines the operation of a SVO kit, what parts are necessary, and how to install a kit in a car. That particular conversion uses radiator fluid for heating the vegetable oil.
I became interested in fitting a SVO (dual fuel) system in my Ute, primarily because I believe there appropriate applications for both systems. Bio-diesel has the convience that you use it just the same as diesel. SVO however, requires a little more effort. To successfully use vegetable oil as a fuel, you first need a warm up stage and then also a shut down stage. To use a SVO system, you start your engine on diesel, and once the engine has reached operation temperature, and the oil is hot, you change from diesel to vegetable oil. You then continue on vegetable until you are 10 minutes or so from your destination and then switch back to diesel to allow the lines to clear. Shutting down too late, will leave more vegetable oil in the fuel system, which may make it harder to start the engine once it has cooled. It is simply a matter of heating the glow plugs longer, or cracking the bleed valve on the fuel filter assembly and hand pumping some diesel through.
Instead of using the radiator fluid for heating the oil, I preferred a simpler system that uses an in-line electric heater. By using an in line heater, you keep a regulated temperature and don’t run the risk of contaminating your fuel system with radiator fluid. It is also a lot simpler and quicker to install an electrically heated conversion. The down side of an in-line electrically heated system, is that you are limited to using oil that is liquid at room temperature. You are unable to use solid oil, tallows or fats as a fuel.
There is a lot of debate about the long term effects of SVO on diesel engines. Research has shown poor engine performance, coking, engine wear and engine failure, while other research has shown that properly heated oil is quite suitable as an alternative fuel. Internationally, there are a large number of people using SVO systems quite successfully.
A research project, Advanced Combustion Research for Energy from Vegetable Oils (ACREVO)
( www.nf-2000.org/secure/Fair/F484.htm) was conducted by a consortium of eight European research Institutes and Universities. The objective was to look at the burning characteristics of vegetable oil droplets under high pressure and high temperature conditions, and to try and address problems such as poor atomisation, coking and to understand the mechanics of deposit formation associated with vegetable oil combustion.
The paper reads, “the flames have been studied with particular regard to stable gasses (CO, CO2, NOx, 02 and hydro carbons), temperature, soot formation and burnout at different rapeseed oil preheating temperature. All the data have been compared with those obtained from a classic diesel oil under the same burning…The overall combustion performance of the rapeseed oil are very satisfactory in comparison with the diesel fuel while the rapeseed produces almost 40% less soot than diesel fuel…It has been established that an addition of 9% ethyl alcohol (95%) bring a great benefit regarding the pre-heating oil temperature. In fact, the presence of alcohol allows a reduction in the inlet oil temperature from 150 degrees C, to 80 degrees C. Moreover, the combustion of the emulsion produces less soot and at the exhaust, the amount is almost one half less than that produced by the rapeseed oil.”
Iam a stockist of the ‘G3” SVO kit. This kit is the result of a thesis by Edward Beggs BES, www.biofuels.ca examining “Renewable oil fuels and diesel engines as components of a sustainable system design”. The heart of the SVO kit is a self-regulating, in line, electric heater. This in-line heater heats to and maintains a constant 70 degrees C, which is very close to the recommendations of the ACREVO report. To date I have travelled a few thousand kilometres and have had no instances of poor performance. I am quite confident in the suitability of both bio-diesel and SVO as legitimate diesel fuel alternatives.
Straight vegetable oil conversion
Fuel valve and pre-filter
Electric in-line heater
Vegetable oil tank
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