EFFECT OF VEGETABLE OILS ON ENGINE

S.I.SRIDHAR – BTG-10-025R.V.JAYAPRASANTH – BTG-10-008

Vegetable oil sources Sunflower oil

High linoleic sunflower oil High oleic sunflower oil

Soybean oil Rapeseed oil Coconut oil Jatropha oil Palm oil

Introduction SVO – Straight Vegetable Oil

Not a new idea

Rudolf diesel – designed for peanut oil

The advent of the injection pump, high pressure fuel systems, and various high tolerance parts required less viscous fuel to be employed.

Problems encountered due to veg.oil

Diesel engines with vegetable oils offer acceptable engine performance and emissions for short-term operation. Long-term operation results in operational and durability problems.

This reduced engine life is caused by the build up of carbon deposits inside the engine

Effect on engines Running a diesel engine on Straight

Vegetable Oil can cause the residue to crystallize in the cylinder and can cause problems.

During cold weather the vegetable oil crystallizes at higher temperatures than conventional diesel. This can cause cold starting problems and the crystals can block the fuel filter and adversely affect fuel atomization.

Problems encountered due to veg.oil

Vegetable oils are much more viscous, are more reactive to oxygen, and have higher cloud point and pour temperatures.

Higher ranges of viscosity can block filters, clog fuel lines and adversely affect fuel atomization.

Room temperature viscosity of vegetable oils varies between 30-90 centistokes.

Effect of viscosity

For eg: rapeseed oil has its viscosity as 34 centistokes at room temperature. But when heated to 100 C its viscosity is reduced to 7.8 centistokes

Effect of viscosity Two theory of overcoming this problem

The first is to blend vegetable oil in with diesel or kerosene up to a ratio of about 20%.

Preheating the SVO.

the tendency to form carbon deposits increases with blending of a vegetable oil into a diesel fuel.

PREHEATING SVO:

The second school of thought is to use a two tank system where the vehicle is started up on a thin, highly combustible fuel such as fossil diesel and then switched over to a second tank when the engine is nice and hot.

Impact of SVO properties on engine performance and durability

Advantages Environmentally friendly.

Waste oil is cheaper.

Smoother engine running - no 'knock'.

Better lubrication.

Less reliance on petro-chemicals.

Disadvantages May cause engine choking if misused. May invalidate vehicle warrantee. Exhaust smells of chips (unless cat.

converter fitted). Have to pay tax to customs and excise

certain countries. Harder to start the engine in the morning Will destroy some injector pumps

Veg oil Vs Biodiesel For the environmentalist, running a vehicle

on veg oil should be preferred over bio diesel.

The reason being that vegetable oil, as a fuel, has greater carbon neutrality.

To make bio diesel you start off with vegetable oil and then put it through a chemical process that requires energy and other chemical reactants, some of which are usually produced from fossil fuel bases.

Veg oil Vs Biodiesel So when vegetable oil is such a good

fuel, why go through the bother of chemically modifying it?

Veg oil Vs Biodiesel Bio diesel has the advantage over veg oil

in that it can be used by any unconverted diesel engine, provided that the fuel lines are of synthetic rubber.

Bio diesel is corrosive to natural rubber.

Because bio diesel can be used essentially like conventional diesel it seems more likely to become the environmentally fuel of the average motorist

Veg oil Vs Biodiesel In fact some countries are encouraging a

standard percentage of bio diesel in all mineral diesel.

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