ADDITIVES

What you mean by fuel Additive?  Any substance added in small amounts to something else to improve, strengthen, or otherwise alter it.  Fuel additive?  Fuel additive is defined as they are compounds formulated to enhance the quality and efficiency of the fuels used in motor vehicle

Requirements of additives?  it must be effective in desired reaction  it should be soluble in fuel under all condition.  it should be stable in storage and have no adverse effect on fuel stability.  it should be in the liquid phase at normal temperature,and volatile to give rapid vaporization in manifold  it must not produce any harmful deposits.  its water solubility must be maintain to minimize handling loses

Types of Additives

1.Tetra ethyl Lead (TEL)  significantly improve octane rating  poisonous, oily liquid, Pb(C 2 H 5 ) 4, was added to gasoline for internal-combustion engines as an antiknock agent.  It will delay auto ignition and allow it to occur at a high temperature.

How TEL works ?  Lead is heavy element and can exist in a number of different oxide forms  able to absorb the energy released within the end gas during chain branching reaction of fuel and oxygen prior to ignition  delay the process of spontaneous ignition,and permit the spark –ignited flame to travel normally

Disadvantage of Tel  Lead clogs catalytic converter  The Earth became covered in a thin layer of lead  increase the NO x levels in the exhaust  It also requires an increase in fuel consumption

2. Methyl Tertiary Butyl Ether (MTBE)  MTBE is the principal oxygenate and octane boosting additive  It is an oxygenate meaning that it adds oxygen to the reaction when it burns. Ideally, an oxygenate reduces the amount of unburned hydrocarbons and carbon monoxide in the exhaust.  It boosts octane

Disadvantage of methyl Tertiary butyl ether  MTBE is that it is thought to be carcinogenic  it mixes easily with water and low sorption onto soils

3. Antiknock additives  Knocking is due to chain branching reaction which produce highly energized particles or radicals.  result of breaking of chain reaction, thereby delaying the auto-ignition of the end mixture and permitting the normal flame to pass through it without combustion knock.  increase octane number

4. Carburetor Detergent Additives  The dust, soot, and smoke carried into the engine with the incoming air  tend to cause deposition in manifold and carburetor  prevent formation of these deposit and remove existing deposits.

5.Ethanol  extend the life of our oil reserves  Ethanol is soluble in gasoline  addition of ethanol helps the combustion process  Disadvantage  ethanol makes the engine leaner  production of pure anhydrous ethanol is difficult and expensive 

Some of the additives and there function  Additive  Antiknock compounds  Scavengers  Combustion chamber  Function  -Increases octane number  -Removes combustion products of antiknock compounds  -Suppresses surface ignition and spark plug deposit modifiers fouling

Some of the additives and there function  Antioxidants  Metal deactivators  Anti-rust agents  Anti-icing agents  Detergents  -Provides storage stability  -Supplements storage stability  -Prevents rusting in gasoline-handling systems  -Suppresses carburetor and fuel system freezing  -Controls carburetor and induction system cleanliness

Some of the additives and there function  Upper cylinder lubricants  Dyes  -Lubricates upper cylinder areas and controls intake system deposits  -Indicates presence of antiknock compounds and identifies makes and grades of gasoline

Commonly used fuel additives are  Ether -extensively as starting fluid for many difficult-to-start engines, especially diesel engines Ether  Nitrous oxide- or simply nitrous, is an oxidizer used in auto racing Nitrous oxide  Nitromethane,- high-performance racing fuel Nitromethane  Acetone - a vaporization additive, mainly used with methanol racing fuel to improve vaporisation at start up Acetone  Butyl rubber- (as polyisobutylen succinimi, detergent to prevent fouling of diesel Butyl rubber  fue l injectors  Picrate- improves combustion, increases fuel mileage Picrate  Silicone - an anti-foaming agent for diesel fuel, but may damage oxygen sensors in gasoline engines Silicone  Tetranitromethane - can increase the cetane number of diesel fuel, improving its combustion properties Tetranitromethane

Benefits associated with the use of fuel additives.Alter the engine performance - boost the octane level. Less Engine maintenance -preventing the buildup of sludge and other deposits in different areas of the engine.. Minimize corrosion -antiknock agents to ease the stress on engine piston

HEALTH EFFECTS OF ADDITIVES  _ Cardiovascular or Blood Toxicant  _ Gastrointestinal or Liver Toxicant  _ Neurotoxicant  _ Respiratory Toxicant  _ Skin or Sense Organ Toxicant