The use of fuel additives to improve biodiesel quality characteristics

Modern fuel additives are very important both for improving fuel properties, as well as to increase engine longevity and improve technical characteristics. Effective characteristics of the engine also depend on the engine design, the materials and production technology of its components.

On the other hand, even the engines are being constantly improved during operation of a great number of extraneous factors such fuel, oil, coolant; various sealing elements reduce their economy. Engine parts and elements wear and rub themselves during chemical and thermal processes. Although the intervals between the vehicle services are becoming longer because of improved technologies, the engine still remains one of the key elements for service. So the lengthening of the engine durability is the main object of interest for users as well as for manufacturing or service organizations. For this reason the view that the application of additives in improving fuel properties is a way to solve a number of issues related to the motor operating characteristics improvement is becoming stronger.

In the recent year’s multifunctional additives which act systemically improving lubrication, cleaning, burning, corrosion and other properties are becoming more popular. These accessories appeal to consumers as they improve some fuel properties and have multiple effects. They accelerate the combustion in the cylinder of the engine as make fuel burn more smoothly.

Τhe biodiesel physical properties can be uplifted by using different additives including metal based additives, antioxidants and oxygenated additives, cold flow improver etc. into biodiesel to solve the problem of cold flow properties for their large number of usage in diesel engines. Some additives were used to improve the performance and reduce exhaust emissions from diesel engines.

The range of benefits accruing from fuel additives is very significant and includes:

- Protection of fuel tanks, pipe lines and other from massively expensive corrosion.

- Protection of fuel system equipment in the diesel engine from catastrophic premature wear.

- Reduced pumping costs and energy use in long-distance fuel pipelines.

- Reduced refinery processing needed to meet fuel cetane and specifications.

- Cold flow improvement in middle distillates, maximizing use of bio fuel.

- Stability improvement to prolong storage life of fuels throughout the operating theatre.

- Fuel saving from optimized vehicle performance and economy.

- Emission reduction from fuel system cleanliness and combustion optimization.

Biodiesel is non-explosive, nontoxic, non-flammable and biodegradable fuel which provides reduction of many detrimental exhaust emissions. It has no SO_X emission, particulate and soot and it can be reduced polycyclic aromatic hydrocarbons emissions.

However there are some disadvantages associated with the use of biodiesel fuels.

Some biodiesel fuel increases NO_X emission, which have rigorous environmental regulations and relatively poor low temperature flow properties compared to conventional diesel. Another demerit is the oxidation stability of biodiesel because of containing the double bond molecules in the free fatty acid. Fuels containing bio-components present special challenge in use, for which a range of additives provide valuable benefits. Aspect includes:

- Reduce oxidation stability.

- Potential for increased injector deposit formation.

- Corrosion in long term storage.

- Adverse effect on cold flow characteristics.

- Increased microbial contamination.

It is considered that fuel physical properties (density, viscosity and cooking area) do not change. However, their influence on engine performance and durability requires further studies.

The quality of biodiesel can be bettered by improving the technological processes, production, careful selection and processing of raw materials. However, their properties can also be improved by use of special additives which affect each characteristic or the entire set of them. Consequently, the composition of biodiesel and the use of additives directly affect such properties as viscosity, density, behavior at low temperatures, Volatility, and the cetane number. Popularity of complex (multifunctional) additives which act systemically improving lubrication, cleaning, burning, corrosion and other properties have been growing recently. Their influence on the properties of biodiesel and engine efficiency and durability requires further studies.