Since the middle of s, the enthusiasm for using alcohols as alternate convenient fuels in internal combustion engine IC has been increased and it has reached peak stage by the middle of s. The usage of alcohol as an alternate fuel, due to its minimal undesired effects on atmosphere, has gained importance. Harmful effects on environment are caused by various fossil fuels and their exhaust emissions such as carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides and particulate matter. Alcohol type of fuels is alternative to petroleum-based fuels due to reduced greenhouse gas emission, toxic exhaust emission and enhancement of overall energy efficiency.
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Alcohol and cotton oil as alternative fuels for internal combustion engines 5. The fuel properties of alcohol and basic principles of engine conversion 5. Studies on using vegetable oil for diesel engine 5. Field test system for evaluating a tractor. This study was launched with the circumstances that the research on refining a alcohol from sweet sorghum had made such enormous strides that the source of raw material for alcohol production was expanded and the technology for alcohol production improved, moreover, the resource of cotton oil was abundant in the northeast regions of China, which promised increased output and reduced the price of alcohol.
The goals of the study were to better understand the fuel properties of alcohol and basic principles of conversion in order to provide the representative cross section of converting diesel engine and gasoline engine to blended fuel. Finally, a microcomputer based system for evaluating tractor performance was presented. As is known to all, the alcohol molecule has one or more oxygen, which contributes to the combustion. Theoretically, any of the organic molecules of the alcohol family can be used as a fuel.
The list is somehow more extensive, however, only two of the alcohols are technically and economically suitable as fuels for internal combustion engines. These alcohols are those of the simplest molecular structure, i. It is not the purpose of this paper to discuss the production of the alcohols, however, it can be said that: A. Methanol is produced by a variety of process, the most common are as follows: Distillation of wood; Distillation of coal; Natural gas and petroleum gas.
Ethanol is produced mainly from biomass transformation, or bioconversion. It can also be produced by synthesis from petroleum or mineral coal. Economic reasons dictate, however, the process which can produce the alcohol at the minimum cost. Each country around the world has found the best compromise in the production of an alternative fuel to replace petrol.
In this process, it can be said that solar energy is stored in the plants by the photosynthesis process. Ethanol from a bio-conversion is therefore "solar energy in a liquid state". Ethyl alcohol, or ethanol has been used in Germany and France as early as by the then incipient industry of internal combustion engines. Brazil has utilized ethanol as a fuel since By that time, the production of ethanol was 70 times bigger than the production and consumption of petrol.
There have been times when the push for alternatives to petrol were more vigorous, mainly dictated by strategic and economic reasons. It is interesting to note that in Brazil, there was an intense use of ethanol in the year , , , , and Unfortunately, petroleum has always been considered abundant, almost limitless in availability.
It was cheap and versatile, so the industry has always been very keen in the intensive use of this apparently miraculous fuel. All the development effort was toward the use of petrol and so the engines were developed for this fuel. In those countries with large territorial areas, ethanol has been the alternative fuel choice to replace petrol.
The reason is the fact that alcohol is a renewable source of energy. Currently, ethanol is produced from sugar beets and from molasses. A typical yield is Modern crops yield 60 tonnes of sugar cane per hector of land.
An area of 1km 2 of sugar cane crop can yield tonnes per year in a tropical country like Brazil. Other crops can be used for the production of ethanol. In China, for instance, it has been demonstrated that sweet sorghum "Shennong No.
It has also been shown that 1 tonne of corn can produce nearly liters of alcohol. Fuel properties of alcohols The fuel properties of alcohols are shown in Table 5. Fuel properties of alcohols Item Isoctane Methanol Ethanol 1. Molecular weight Density Higher heating value b.
Lower heating value Research octane number Flash point temp. Auto-ignition temp. Lower 1. Higher 7. Cetane number - 5 8 b. Combustion characteristics There are some important differences in the combustion characteristics of alcohols and hydrocarbons. Alcohols have higher flame speeds and extended flammability limits. Also, alcohols produce a great number of product moles per mole of fuel burnt, therefore, higher pressure are achieved. The alcohols mix in all proportions with water due to the polar nature of OH group.
Low volatility is indicated by high boiling point and high flash point. Alcohols burn with no luminous flame and produce almost no soot, especially methanol.
The tendency to soot increases with molecular weight. Therefore, methanol produces less soot than ethanol. Combustion of alcohol in presence of air can be initiated by an intensive source of localized energy, such as a flame or a spark and also, the mixture can be ignited by application of energy by means of heat and pressure, such as happens in the compression stroke of a piston engine.
The energy of the mixture reaches a level sufficient for ignition to take place after a brief period of delay called ignition delay, or induction time, between the sudden heating of the mixture and the onset of ignition formation of a flame front which propagates at high speed throughout the whole mixture. The high latent heat of vaporization of alcohols cools the air entering the combustion chamber of the engine, thereby increasing the air density and mass flow. This leads to increased volumetric efficiency and reduced compression temperatures.
Blending ethanol with gasoline at 0. Power continues to rise steadily as the mixture is enriched to an equivalence ratio of about Because of the low proportion of carbon in alcohols, soot formation does not occur and therefore alcohols burn with low luminosity and therefore low radiation. The lower flame temperature of alcohols results in much lower NOx Nitrogen Oxides emissions. The wider flammability limits of alcohols permit smooth engine operation even at very lean mixtures.
But aldehyde emissions are noticeably higher. For ethanol, emissions are acetaldehydes and for methanol, emissions are of formaldehydes. The oxygen contents of alcohols depresses the heating value of the fuel in comparison with hydrocarbon fuels. The heat of combustion per unit volume of alcohol is approximately half that of isooctane. However, the stoichiometric fuel-air mass ratios are such big that the quantity of energy content based on unit mass of stoichiometric mixture become comparable with that of hydrocarbons.
Methanol is not miscible with hydrocarbons and separation ensues readily in the presence of small quantities of water, particularly with reduction in temperature.
Anhydrous ethanol, on the other hand, is completely miscible in all proportions with gasoline, although separation may be effected by water addition or by cooling. If water is already present, the water tolerance is higher for ethanol than for methanol, and can be improved by the addition of higher alcohols, such as butanol.
Also benzene or Acetone can be used. The high heat of vaporization and constant boiling point make cold starting very difficult with neat alcohols. The problem is not as severe as in case of alcohols blended with gasoline. Gasoline which has a high vapor pressure therefore highly volatile can be used for cold start. Nitride and neoprene rubbers, generally satisfactory as elastomers in contact with methanol and polyacetal plastics, are very resistant. Silicon rubber as well as vinyl can be used for gasket material.
Ethanol always contains acetic acid and is particularly corrosive to aluminum alloys. Also certain alloys containing lead are attacked with general result of the lead being leached out, leaving a porous surface. The zinc is leached out as a white zinc oxide, which clogs the small orifices and jets. Carburettors are normally made of zamac alloy. Experience has shown that if the carburettor is protected with a coat of Nickel the corrosion problem is overcome.
The process recommended is electrolysis Nickel plating. In this process, the carburettor parts are immersed in a bath of hot Nickel, which due to its very low viscosity, covers evenly all the surfaces without clogging the orifices. The floats on the carburettor float-bowl are generally made of porous plastics which are attacked by the ethanol and the end result is swelling and cracking.
It is found that nylon floats arc more durable. All bronze parts shall be brass or stainless steel. Fuel filters used for gasoline are not recommended for the many alcohols. The internal element collapses after the glue that bonds it together is softened by the alcohol. Special filters are necessary. Also due to the higher flows, filters have to be bigger. The filter body must be made of Nylon or Teflon. Drive ability and Performance Engine Performance and durability on alcohol depends almost entirely upon mixture preparation.
Existing gasoline inlet manifold and hot-spot systems cannot provide the necessary amount of heat since the demand is 6 times greater than that for gasoline, and the extra heat must be taken either from the cooling system of the engine, or from the exhaust gases. There are advantages and disadvantages. Exhaust gas systems warm up more rapidly, but require relatively bulky ducts to carry the necessary volumes of air with minimal pressure drops. Water-heated systems can prove inadequate during warm-up at low ambient temperature, and cylinder wall wetting is then inevitable over long periods.
Alcohol and ether as alternative fuels in spark ignition engine: A review
Alcohol and cotton oil as alternative fuels for internal combustion engines 5. The fuel properties of alcohol and basic principles of engine conversion 5. Studies on using vegetable oil for diesel engine 5. Field test system for evaluating a tractor. This study was launched with the circumstances that the research on refining a alcohol from sweet sorghum had made such enormous strides that the source of raw material for alcohol production was expanded and the technology for alcohol production improved, moreover, the resource of cotton oil was abundant in the northeast regions of China, which promised increased output and reduced the price of alcohol. The goals of the study were to better understand the fuel properties of alcohol and basic principles of conversion in order to provide the representative cross section of converting diesel engine and gasoline engine to blended fuel.
Alcohol Fuels as an Alternative Fuels - Bringing New Heights in Sustainability
Various alcohols are used as fuel for internal combustion engines. The first four aliphatic alcohols methanol , ethanol , propanol , and butanol are of interest as fuels because they can be synthesized chemically or biologically, and they have characteristics which allow them to be used in internal combustion engines. Most methanol is produced from natural gas, although it can be produced from biomass using very similar chemical processes. Ethanol is commonly produced from biological material through fermentation processes. There is no chemical difference between biologically produced and chemically produced alcohols. One advantage shared by the four major alcohol fuels is their high octane rating.