Octane Rating

Octane Rating
Octane rating is a fuel's ability to resist detonation and is classified by three main rating types. Octane rating is the measure of how resistant is gasoline and other fuels in the combustion engines to automatic ignition. It is the measure of a fuel’s burning characteristics. It is a standard measure of the performance of a motor or aviation fuel, the higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance. Fuels with higher octane ratings tend to have higher activation energies meaning that it takes a long time for auto-ignition to take place. When fuels with lower octane rating are used, the efficiency and the power output of the engine decreases. When fuels with higher octane rating are used, higher compression can be achieved; however the power output of an engine depends on the energy density of the fuel contained in it.

Octane rating is specified in octane numbers. There are different standards followed in different countries. However the most common method of octane rating is specifying the Research Octane Number (RON). This is determined by comparison of the performance of a fuel and the mixture of iso-octane and heptane.

-1- Pollutants Obtained in burning gasoline
Pollutants are obtained when burning gas from cars, the process of burning gas in Auto-motive vehicles is called Combustion. Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame.. Some pollutants obtained by burning gasoline are

-Carbon monoxide
Every poison has a particular trait that causes it to be poisonous. In the case of carbon monoxide, the trait has to do with hemoglobin in the blood.
Hemoglobin is made up of complex proteins that bind to iron atoms. The structure of the protein and its iron atom causes oxygen to bind to the iron atom very loosely. When blood passes through the lungs, the iron atoms in the hemoglobin bind to oxygen atoms. When the blood flows into areas of the body that are lacking in oxygen, the iron atoms release their oxygen.. Carbon monoxide, on the other hand, binds very strongly to the iron in hemoglobin. Once carbon monoxide attaches, it is very difficult to release. So if you breathe in carbon monoxide, it sticks to your hemoglobin and takes up all of the oxygen binding sites. Eventually, your blood loses all of its ability to transport oxygen, and you suffocate. Because carbon monoxide binds to hemoglobin so strongly, you can be poisoned by carbon monoxide even at very low concentrations if you are exposed for a long period of time. Concentrations as low as 20 or 30 parts per million (PPM) can be harmful if you are exposed for several hours. Exposure at 2,000 PPM for one hour will cause unconsciousness. Gasoline Carbon Monoxide Oxygen Lungs Blood Red Blood Cells

-2- Nitrogen Oxide
Nitrogen Oxide, also known as NOx, is a group of different gases made up of different levels of oxygen and nitrogen, it is formed when certain fuels (oil, gas and coal) are burned at a high temperature, such as combustion. Two of the most common nitrogen oxides are Nitrogen Dioxide and Nitric Oxide. Nitrogen Oxide is given off in many forms such as smog (a type of air pollution, combining words smoke and fog); and particles. Nitrogen Oxide helps form acid rain. It contributes to global warming and It hampers the growth of plants. NOx can form with other pollutants to form toxic chemicals Small levels of NOx can cause nausea, irritated eyes and/or nose, fluid forming in lungs and shortness of breath Breathing in high levels of NOx can lead to: rapid, burning spasms; swelling of throat; reduced oxygen intake; a larger buildup of fluids in lungs and/or death NOx, plus other ground-level ozone, can cause other major respiratory problems in high levels can react with aerosols from aerosols cans and also cause respiratory problems NOx can cause visual impairment in the area affects by NOx.
Gasoline Nitrogen Oxide Smog (smoke and fog) Lungs Blood Skin

Unburned Hydrocarbons
Unburned hydrocarbons are the hydrocarbons emitted after petroleum is burned in an engine. Any fuel entering a flame will be reacted Hydrocarbons, when they are a vapourised in car engines and pollute the atmosphere, are toxic and carcinogenic to humans. Also, when they are in the atmosphere they react with nitrogen oxides, oxygen and water vapour if they come into contact with sunlight. They create ozone in this reaction. When ozone is in the troposphere (a lower layer of the atmosphere) in very high concentrations it is toxic to humans and attacks the lung tissue. Ozone in the troposphere (rather than the insulating layer in the stratosphere) acts as a green house gas, causing global warming.

Gasoline Unburned Hydrocarbons Atmosphere ozone Lung Tissue

-3- Purpose in Adding Lead in Gasoline
Tetraethyl lead was extensively used as an additive to gasoline, wherein it served as an effective antiknock agent and prevented exhaust valve and seat wear.

-As valve wear preventive
Tetraethyl lead works a buffer against micro-welds forming between the hot exhaust valves and their seats. Once the valves would reopen, the micro-welds would pull apart and leave the valves with a rough surface that would abrade the seats, leading to valve recession. When lead began to be phased out of motor fuel, the automotive industry began specifying hardened valve seats and upgraded exhaust valve materials to prevent valve recession without lead.
-As antiknock agent An engine requires fuel of sufficient octane rating to prevent uncontrolled combustion known as engine knocking ("knock" or "ping").[4] Antiknock agents allow the use of higher compression ratios for greater efficiency[5] and peak power. Adding varying amounts of TEL to gasoline allowed easy, inexpensive control of octane ratings; aviation spirits used in WWII reached 150 octane to enable supercharged engines such as the Rolls-Royce Merlin and Griffon to produce 1500 HP at altitude.[6] In military aviation, TEL manipulation allowed a range of different fuels to be tailored for particular flight conditions, and ease and safety of handling. TEL's biocidal properties helped prevent fuel contamination and degradation from bacterial growth. Contribution of burning gasoline in greenhouse effect
Gas itself is a greenhouse gas more potent than carbon dioxide. Although natural gas is released into the atmosphere in much smaller quantities, methane is oxidized in the atmosphere, and hence natural gas affects the atmosphere for approximately 12 years, compared to CO2, which is already oxidized, and has effect for 100 to 500 years. Natural gas is composed mainly of methane, which has a radiative forcing twenty times greater than carbon dioxide. Based on such composition, a ton of methane in the atmosphere traps as much radiation as 20 tons of carbon dioxide; however, it remains in the atmosphere for 8–40 times less time. Carbon dioxide still receives the lion's share of attention concerning greenhouse gases because it is released in much larger amounts. Still, it is inevitable when natural gas is used on a large scale that some of it will leak into the atmosphere. (Coal methane not captured by coal bed methane extraction techniques is simply lost into the atmosphere -4-.

Diagram of greenhouse effect

Reflections I can help in minimizing the greenhouse effect by lessening the consumption of gasoline in vehicles an example of this is by taking Pubic Utility Vehicles like jeeps and buses instead of using private vehicles cause if you use private vehicles you are consuming more gasoline because you are only transporting few people and producing more smoke from cars but if you ride the public vehicles your are lessening the consumption of gasoline and lessening the smoke coming from vehicles because by taking Public transportations less cars are used which means less smoke and less consumption of gasoline. I can also minimize the greenhouse effect by conserving gasoline at home for example when the LPG tank is not in use I should turn it off so I would not waste gasoline and help in minimizing the green house effect.
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