ALCOHOL AS AN ALTERNATIVE FUEL IN I.C ENGINES

ALCOHOL AS AN ALTERNATIVE FUEL IN IC ENGINES In this century, it is believed that crude oil and petroleum products will become very scarce and costly. Day-to-day, fuel economy of engines is getting improved and will continue to improve. However, enormous increase in number of vehicles has started dictating the demand for fuel. With increased use and depletion of fossil fuels, alternative fuel technology will become more common in the coming decades. Because of the high cost of petroleum products, emission problems some developing countries are trying to use alternate fuels for their vehicles.

DIFFICULTIES: 1. Extensive research and development is difficult to justify until the fuels are accepted as viable for large numbers of engines. 2. Most alternate fuels are very costly at present since the quantity used is very less. 3. There is lack of distribution points (service stations) where fuel is available to the

public.

ALCOHOL: Alcohols are attractive alternate fuels because they can be obtained from both natural and manufactured sources. Methanol and ethanol are two kinds of alcohols that seem most promising.

ADVANTAGES: 1. It is a high octane fuel with anti-knock index numbers of over 100.Engines using high octane fuel can run more efficiently by using higher compression ratios. Alcohols have higher flame speed. 2. It produces less overall emissions compared to gasoline. 3. When alcohols are burned, it forms more moles of exhaust gases, which gives higher pressure and more power in the expansion stroke. 4. It has high latent heat of vaporization which results in a cooler intake process. This raises the volumetric efficiency of the engine and reduces the required work input in the compression stroke.

5. Alcohols have low sulphur content in the fuel. 6. Reduced petroleum imports and transportation.

DISADVANTAGES: 1. Alcohols have low energy content or in other words the calorific value of the fuel is almost half. This means that almost twice as much as gasoline must be burned to give the same energy input to the engine. With equal thermal efficiency and similar engine output usage, twice as much fuel would have to be purchased, and he distance which could be driven with a given fuel tank volume would be cut in half. Automobiles as well as distribution stations would require twice as much storage capacity, twice the number of storage facilities, twice the volume of storage at the service stations, twice as many tank trucks and pipelines, etc. Even with the low energy content of the fuel, engine power for a given displacement would be about the same. This is because of the lower air-fuel ratio needed by alcohol. Alcohol contains oxygen and thus requires less air for stoichiometric combustion. More fuel can be burned with the same amount of air. 2. Combustion of alcohols produces more aldehydes in the exhaust. If as much alcohol fuel was consumed as gasoline. Aldehyde emissions would be a serious problem. 3. Alcohol is much more corrosive than gasoline on copper, brass, aluminum, rubber, and many plastics. This puts some restrictions on the design and manufacturing of engines to be used with this fuel. Fuel lines and tanks, gaskets, and even metal engine parts can deteriorate with long-term alcohol use (resulting in cracked fuel lines, the need for special fuel tank, etc). Methanol is very corrosive on metals. 4. It has poor cold weather starting characteristics due to low vapor pressure and evaporation. Alcohol-fuelled engines generally have difficulty in starting at temperatures below 10 C. Often a small amount of gasoline is added to alcohol fuel, which greatly improves cold-weather starting. However, the need to do this greatly reduces the attractiveness of alcohol. 5. Alcohols have poor ignition characteristics n general. 6. Alcohols have an almost invisible flame, which is considered dangerous when handling fuel. A small amount of gasoline removes this danger.

7. There is the danger of storage tank flammability, due to low vapor pressure. Air can leak into storage tanks and create combustible mixtures. 8. There will be less NOx emissions because of low flame temperatures. However, the resulting lower exhaust temperatures take longer time to heat the catalytic converter to efficient operating temperatures. 9. Many people find the strong odor of alcohol very offensive. Headaches and drizzles have been experienced when refueling an automobile. 10. There is a possibility of vapor lock in fuel delivery systems.

METHANOL: Of all the fuels being considered as an alternate to gasoline, methanol is one of the most promising and has experienced major research and development. Pure methanol and mixtures of methanol and gasoline in various percentages have been extensively tested in engines and vehicles for a number of years. The most common mixtures are M85 (85% methanol and 15% gasoline). The data of these tests which include performance and emission level levels are compared with pure gasoline (M0) and pure methanol (M100). Some smart flexible fuel (or variable fuel) engines are capable of using any random mixture combination of methanol and gasoline ranging from methanol to pure gasoline. Two fuel tanks are used and various flow rates of the two fuels can be pumped to the engine, passing through a mixing chamber. Using information from sensors in the intake and exhaust, the electronic monitoring systems (EMS) adjust to the proper air-fuel ratio, ignition ratio, ignition timing, injection timing, and valve timing (where possible) for the fuel mixture being used. Methanol can be obtained from many sources, both fossil and renewable. These include coal, petroleum, natural gas, biomass, wood, landfills, and even the ocean. However, any source that requires extensive manufacturing or processing raises the price of the fuel. Emissions from an engine using M10 fuel are about the same as those using gasoline. The advantage (and disadvantage) of using this fuel is mainly 10% decrease in HC and CO exhaust emissions. However, there is an increase in NOx and a large (500%) increase in formaldehyde emissions.

Methanol is used some dual-fuel CI engines. Methanol by itself is not a good CI engine fuel because of its high octane number, but if a small amount of diesel oil is used for ignition, it can be used with good results. This is very attractive for developing countries, because methanol can often be obtained from much cheaper source than diesel oil. Methanol fuel has received less attention than ethanol fuel as an alternative to petroleum based fuels.[1]

Use as internal combustion engine fuel Both methanol and ethanol burn at lower temperatures than gasoline, and both are less volatile, making engine starting in cold weather more difficult. Using methanol as a fuel in spark ignition engines can offer an increased thermal efficiency and increased power output (as compared to gasoline) due to its high octane rating (114) and high heat of vaporisation. However, its low energy content of 19.7 MJ/kg and stoichiometric air fuel ratio of 6.42:1 mean that fuel consumption (on volume or mass basis) will be higher than hydrocarbon fuels. The extra water produced also makes the charge rather wet (similar to hydrogen/oxygen combustion engines)and combined with the formation of acidic products during combustion, the wearing of valves, valve seats and cylinder might be higher than with hydrocarbon burning. Certain additives may be added to motor oil in order to neutralize these acids. Methanol, just like ethanol, contains soluble and insoluble contaminants. These soluble contaminants, halide ions such as chloride ions, have a large effect on the corrosivity of alcohol fuels. Halide ions increase corrosion in two ways; they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electric, galvanic, and ordinary corrosion in the fuel system. Soluble contaminants, such as aluminium hydroxide, itself a product of corrosion by halide ions, clog the fuel system over time. Methanol is hygroscopic, meaning it will absorb water vapor directly from the atmosphere. Because absorbed water dilutes the fuel value of the methanol (although, it suppresses engine knock), and may cause phase separation of methanol-gasoline blends, containers of methanol fuels must be kept tightly sealed.

Toxicity Methanol is poisonous; ingestion of only 10 ml can cause blindness and 60-100 ml can be fatal, and it doesn't have to be swallowed to be dangerous since the liquid can be absorbed through the skin, and the vapors through the lungs. US maximum allowed exposure in air (40 h/week) is 1900 mg/m³ for ethanol, 900 mg/m³ for gasoline, and 1260 mg/m³ for methanol. However, it is less volatile than gasoline, and therefore decreases evaporative emissions. Use of methanol, like ethanol, significantly reduces the emissions of certain hydrocarbon-related

toxins such as benzene and 1, 3 butadiene. But as gasoline and ethanol are already quite toxic, safety protocol is the same.

Safety Since methanol vapour is heavier than air, it will linger close to the ground or in a pit unless there is good ventilation, and if the concentration of methanol is above 6.7% in air it can be lit by a spark, and will explode above 54 F / 12 C. Once ablaze, the flames give out very little light making it very hard to see the fire or even estimate its size, especially in bright daylight. If you are unlucky enough to be exposed to the poisonous substance through your respiratory system, its pungent odor should give you some warning of its presence. However, it is difficult to smell methanol in the air at less than 2,000 ppm (0.2%), and it can be dangerous at lower concentrations than that.[3]

ETHANOL Ethanol has been used as automobile fuel for many years in various countries of the world. Brazil is probably the leading user, where in the early 1990s. About 5 million vehicles operated on fuels that were 93% ethanol. For a number of years gasohol (gasoline+alcohol) has been available at service stations in the United States. Gasohol is a mixture of 90% gasoline and 10% ethanol. As with methanol, the development of systems using mixtures of gasoline and ethanol continues. Two mixture combinations that are important are E85 (85% ethanol) and e10 (gasohol). E85 is basically an alcohol fuel with 15% gasoline added to eliminate some of the problems of pure alcohol (i.e., cold starting, tank flammability, etc.E10 reduces the use of gasoline with no modification needed to the automobile engine. Flexible-fuel engines are being tested which can operate on any ratio of ethanol-gasoline.[1]

Butanol and Propanol Propanol and butanol are considerably less toxic and less volatile than methanol. In particular, butanol has a high flashpoint of 35 °C, which is a benefit for fire safety, but may be a difficult for starting engines in cold weather. The concept of flash point is however not directly applicable to engines as the compression of the air in the cylinder means that the temperature is several hundred degrees Celsius before ignition takes place.

The fermentation processes to produce propanol and butanol from cellulose are fairly tricky to execute, and the Weizmann organism (Clostridium acetobutylicum) currently used to perform these conversions produces an extremely unpleasant smell, and this must be taken into consideration when designing and locating a fermentation plant. This organism also dies when the butanol content of whatever it is fermenting rises to 7%. For comparison, yeast dies when the ethanol content of its feedstock hits 14%. Specialized strains can tolerate even greater ethanol concentrations - so-called turbo yeast can withstand up to 16% ethanol. However, if ordinary Saccharomyces yeast can be modified to improve its ethanol resistance, scientists may yet one day produce a strain of the Weizmann organism with a butanol resistance higher than the natural boundary of 7%. This would be useful because butanol has a higher energy density than ethanol, and because waste fibre left over from sugar crops used to make ethanol could be made into butanol, raising the alcohol yield of fuel crops without there being a need for more crops to be planted. Butanol combustion is: C4H9OH + 6O2 → 4CO2 + 5H2O + heat[4]

ALCOHOL FOR SI ENGINES: Alcohol have higher antiknock characteristic compared to gasoline. As such with an alcohol fuel, engine compression ratios between 11:1 and 13:1 are usual. Today’s gasoline engines use a compression ratio of around 7:1 or 9:1, much too low for pure alcohol. Alcohol does not vaporize as easily as gasoline. Its latent heat of vaporization is much greater. This affects cold weather starting. If the alcohol liquefies in the engine then it will not burn properly. Thus, the engine may be difficult or even impossible to start in extremely cold climate. To overcome this, gasoline is introduced in the engine until the engine starts and warms up. Once the engines warms, alcohols when introduced will vaporize quickly and completely and normally. Even during normal operation, additional heat may have to be supplied to completely vaporize alcohol. Alcohol burns at about half the speed of gasoline. As such, ignition timing must be changed, so that more spark advance is provided. This will give the slow burning alcohol more time to develop the pressure and power in the cylinder. Moreover, corrosion resistant materials are required for fuel systems since alcohols are corrosive in nature.

WATER-GASOLINE MIXTURE FOR SI ENGINES: The development of the spark-ignition engine has been accompanied by the desire to raise the compression ratio for increased efficiency and fuel economy. One obstacle to this gain in economy at

times has been the octane quality of the available gasoline. To circumvent this limitation, water was proposed as an antiknock additive. Water addition to gasoline slows down the burning rate and reduces the gas temperature in the cylinder which probably suppresses detonation. Engine combustion chamber deposit reductions have also been reported when water was added to the intake charge. With respect to nitric oxide emissions, dramatic reductions were reported. Conversely, water addition probably increases hydrocarbon emissions. Finally, with respect to carbon monoxide emissions, water additions seem to have minimal effect. Only a very limited work has been carried out with the addition of water via an emulsion with the fuel rather than independently. Emulsion could eliminate the need for a separate tank, provide improved atomization and increase fuel safety. However, a water-fuel separation problem may exist.

ALCOHOL FOR CI ENGINES: Techniques of using alcohol in diesel engines are 1. Alcohol/diesel fuel solutions. 2. Alcohol diesel emulsions. 3. Alcohol fumigation 4. Dual fuel injection 5. Surface ignition of alcohols 6. Spark ignition of alcohols 7. Alcohols containing ignition improving additives.

Both ethyl and methyl alcohols have high self ignition temperatures. Hence, very high compression ratios (25-27) will be required to self ignite them. Since this would make the engine extremely heavy and expensive, the better method is to utilize them in dual fuel operation. In the dual fuel engine, alcohol is carbureted or injected into the inducted air. Due to high self ignition temperature of alcohols three will be no combustion with the usual diesel compression ratios of 16 to 18. A little before the end of compression stroke, a small quantity of diesel oil is injected into the compression stroke, a quantity of diesel oil is injected into the combustion chamber through the normal diesel pump and spray nozzle. The diesel oil readily ignites and initiates combustion in the alcohol air mixtures also.

SURFACE-IGNITION ALCOHOL CI ENGINES:

A slab of insulator material, wound with a few strands of heating wire is fixed on the combustion chamber with the wire running on the face exposed to the gases. The fuel injector is located such that a part of the spray impinges head on this surface. Ignition is thus initiated. The combustion chamber, which is in the cylinder head, is made relatively narrow so that the combustion spreads quickly to the rest of the space. Since a part of the fuel burns on the insulator surface and the heat losses from the plate are low, the surface after some minutes of operations reaches a temperature sufficient to initiate ignition without the aid of external electrical supply. The power consumption of the coil is about 50W at 6 volts. The engine lends itself easily to the use of wide variety of fuels, including methanol, ethanol and gasoline. The engine was found to run smoothly on methanol with a performance comparable to diesel operation. The engine operates more smoothly at lower speeds than at higher speeds. [1]

Flexible-fuel vehicle A flexible-fuel vehicle (FFV) or dual-fuel vehicle (colloquially called a flex-fuel vehicle) is an alternative fuel vehicle with an internal combustion engine designed to run on more than one fuel, usually gasoline blended with either ethanol or methanol fuel, and both fuels are stored in the same common tank. Flex-fuel engines are capable of burning any proportion of the resulting blend in the combustion chamber as fuel injection and spark timing are adjusted automatically according to the actual blend detected by electronic sensors. Flex-fuel vehicles are distinguished from bi-fuel vehicles, where two fuels are stored in separate tanks and the engine runs on one fuel at a time, for example, compressed natural gas (CNG), liquefied petroleum gas (LPG), or hydrogen. The most common commercially available FFV in the world market is the ethanol flexible-fuel vehicle, with around 18 million automobiles and light duty trucks on the roads by 2009, and concentrated in four markets, Brazil (9.3 million), the United States (around 8 million), Canada (600,000), and Europe, led by Sweden (181,458). Also a total of 183,375 flexible-fuel motorcycles were sold in Brazil in 2009. In addition to flex-fuel vehicles running with ethanol, in Europe and the US, mainly in California, there have been successful test programs with methanol flex-fuel vehicles, known as M85 flex-fuel vehicles. Though technology exists to allow ethanol FFVs to run on any mixture of gasoline and ethanol, from pure gasoline up to 100% ethanol (E100), North American and European flexfuel vehicles are optimized to run on a maximum blend of 15% gasoline with 85% anhydrous ethanol (called E85 fuel). This limit in the ethanol content is set to reduce ethanol emissions

at low temperatures and to avoid cold starting problems during cold weather, at temperatures lower than 11 °C (52 °F). The alcohol content is reduced during the winter in regions where temperatures fall below 0 °C (32 °F) to a winter blend of E70 in the U.S. or to E75 in Sweden from November until March. Brazilian flex fuel vehicles are optimized to run on any mix of E20-E25 gasoline and up to 100% hydrous ethanol fuel (E100). The Brazilian flex vehicles are built-in with a small gasoline reservoir for cold starting the engine when temperatures drop below 15 °C (59 °F). An improved flex motor generation was launched in 2009 which eliminated the need for the secondary gas tank.

Flexible-fuel vehicles by country Brazil After the 1973 oil crisis, the Brazilian government made mandatory the use of ethanol blends with gasoline, and 100% ethanol powered cars (E100 only) were launched to the market in 1979, after testing with several prototypes developed by four carmakers. Brazilian carmakers modified gasoline engines to support ethanol characteristics and changes included compression ratio, amount of fuel injected, replacement of materials that would get corroded by the contact with ethanol, use of colder spark plugs suitable for dissipating heat due to higher flame temperatures, and an auxiliary cold-start system that injects gasoline from a small tank in the engine compartment to help starting when cold. Flexible-fuel technology started being developed only by the end of the 1990s by Brazilian engineers. The Brazilian flexible fuel car is built with an ethanol-ready engine and one fuel tank for both fuels. The small gasoline reservoir for starting the engine with pure ethanol in cold weather, used in earlier ethanol-only vehicles, was kept in the first generation of Brazilian flexible-fuel cars, mainly for users of the central and southern regions, where winter temperatures normally drop below 15 °C (59 °F). An improved flex motor generation that will be launched in 2009 will eliminate the need for this secondary gas reservoir tank The flexibility of Brazilian FFVs empowers the consumers to choose the fuel depending on current market prices. As ethanol fuel economy is lower than gasoline because of ethanol's energy content is close to 34% less per unit volume than gasoline, flex cars running on ethanol get a lower mileage than when running on pure gasoline. However, this effect is partially offset by the usually lower price per liter of ethanol fuel. As a rule of thumb,

Brazilian consumers are frequently advised by the media to use more alcohol than gasoline in their mix only when ethanol prices are 30% lower or more than gasoline, as ethanol price fluctuates heavily depending on the result of seasonal sugar cane harvests. The rapid success of flex vehicles was made possible by the existence of 33,000 filling stations with at least one ethanol pump available by 2006, a heritage of the early Pró-Álcool ethanol program. These facts, together with the mandatory use of E25 blend of gasoline throughout the country, allowed Brazil in 2008 to achieve more than 50% of fuel consumption in the gasoline market from sugar cane-based ethanol. According to two separate research studies conducted in 2009, at the national level 65% of the flex-fuel registered vehicles regularly use ethanol fuel, and the usage increases to 93% in São Paulo, the main ethanol producer state where local taxes are lower, and prices at the pump are more competitive than gasoline.

Latest developments The latest innovation within the Brazilian flexible-fuel technology is the development of flexfuel motorcycles. In 2007 Magneti Marelli presented the first motorcycle with flex technology, adapted on a Kasinski Seta 125, and based on the Software Fuel Sensor (SFS) the firm developed for flex-fuel cars in Brazil. Delphi Automotive Systems also presented in 2007 its Multifuel injection technology for motorcycles. Besides the flexibility in the choice of fuels, a main objective of the fuel-flex motorcycles is to reduce CO2 emissions by 20 percent, and savings in fuel consumption in the order of 5% to 10% are expected. AME Amazonas Motocicletas announced that sales of its motorcycle AME GA (G stands for gasoline and A for alcohol) were scheduled for 2009, but the first flex-fuel motorcycle was actually launched by Honda in March 2009. Produced by its Brazilian subsidiary Moto Honda da Amazônia, the CG 150 Titan Mix is sold for around US$2,700. Because the CG 150 Titan Mix does not have a secondary gas tank for a cold start like the Brazilian flex cars do, the tank must have at least 20% of gasoline to avoid start up problems at temperatures below 15 °C (59 °F). The motorcycle’s panel includes a gauge to warn the driver about the actual ethanol-gasoline mix in the storage tank.

United States By early 2009 there are almost 8 million E85 flex fuel vehicles running on the US roads, up from almost 5 million in 2005. The E85 blend is used in gasoline engines modified to accept such higher concentrations of ethanol, and the fuel injection is regulated through a dedicated sensor, which automatically detects the amount of ethanol in the fuel, allowing adjusting both fuel injection and sparking timing accordingly to the actual blend available in the vehicle's tank. The American E85 flex fuel vehicle was developed to run on any mixture of unleaded gasoline and ethanol, anywhere from 0% to 85% ethanol by volume. Both fuels are mixed in the same tank, and E85 is sold already blended. In order to reduce ethanol evaporative emissions and to avoid problems starting the engine during cold weather, the maximum blend of ethanol was set to 85%. There is also a seasonal reduction of the ethanol content to E70 (called winter E85 blend) in very cold regions, where temperatures fall below 0 °C (32 °F) during the winter. In Wyoming for example, E70 is sold as E85 from October to May. E85 flex-fuel vehicles are becoming increasingly common in the Midwest, where corn is a major crop and is the primary feedstock for ethanol fuel production. Also the US government has been using flex-fuel vehicles for many years.

Latest developments In 2008 Chrysler, General Motors, and Ford pledged to manufacture 50 percent of their entire vehicle line as flexible fuel in model year 2012, if enough fueling infrastructure develops. In early 2010 GM reaffirmed its commitment to bio fuels and its determination to deliver more than half of its 2012 production in the U.S. market as E85 flex-fuel capable vehicles. GM will begin introducing E-85-capable direct-injected and turbocharged power trains, and urged the deployment of more E85 stations, as "ninety percent of registered flex-fuel vehicles don't have an E85 station in their zip code, and nearly 50%, don't have E85 in their county." In 2008 Ford delivered the first flex-fuel plug-in hybrid as part of a demonstration project, a Ford Escape Plug-in Hybrid capable of running on E85 or gasoline. General Motors announced that the new plug-in hybrid electric vehicle Chevrolet Volt, expected to be launched in the North American market in 2010, will be flex-fuel-capable about a year after it is introduced. The Volt propulsion architecture allows adapting the propulsion to other world markets such as Brazil’s E100 or to Europe’s commonly using clean diesel.

On May 2009, President Barack Obama signed a Presidential Directive with the aim to advance biofuels research and improve their commercialization. The Directive established a Biofuels Interagency Working Group comprises of three agencies, the Department of Agriculture, the Environmental Protection Agency, and the Department of Energy. This group will develop a plan to increase flexible fuel vehicle use and assist in retail marketing efforts. Also they will coordinate infrastructure policies impacting the supply, secure transport, and distribution of biofuels in order to increase the number of fueling stations throughout the country.

OTHER COUNTRIES: 1. Sweden 2. France 3. Germany 4. Ireland 5. Spain 6. United Kingdom 7. Australia 8. Canada 9. Colombia

CONCLUSION As the demand for alternative power source is on the rise due to various reasons , Alcohol forms a good substitute for the rising needs in the use of IC and SC engines.