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Q. From what is it obtained?
A. Alcohol may be derived from any substance that contains either starch or sugar, and it can be produced from various fruits, grains and vegetables. Such materials as beets, potatoes, wheat, rye, corn, sugar-cane, barley, rice, and even decaying fruit or other refuse which could not be utilized otherwise may be distilled and alcohol derived therefrom.
Q. Can it be used as fuel?
A. While alcohol has been used for ten years or more abroad in engines designed especially for its use, it cannot be utilized economically in motors intended for gasoline. Alcohol vapor can be compressed much more than gasoline gas, and as the heat units liberated from a burning fuel vary with the amount of compression prior to ignition, even though alcohol gives out less heat when burned under the same conditions as gasoline, equal or higher engine efficiency may be obtained by compressing the alcohol vapor more. Alcohol is used in some form of carburetor adapted to heat the mixture before it is supplied to the cylinders. An engine designed for gasoline will use nearly twice as much alcohol as it does the other liquid to develop the same amount of energy. One of the disadvantages of alcohol that is shared in common with kerosene is that it is difficult to start a cold engine, and the motor must be heated up before alcohol can be used. Owing to the presence of oxygen in the alcohol, which is not a part of gasoline, only about one third as much air is needed with alcohol vapor and twice the amount of compression before ignition can be used with alcohol gas. It is claimed that the range of explosive mixture proportions of air and alcohol is much greater than that possible with gasoline and air.
Q. Describe the alcohol-acetylene process.
A. This is a recently devised process developed with the object of enabling one to use alcohol with engines of present design with no change except a special form of vaporizer. The alcohol vapor is passed through calcium carbide before it enters the cylinder and the water present in commercial alcohol, which normally lowers its efficiency as a fuel, is absorbed by the carbide and as a chemical action results, acetylene gas is liberated and this very inflammable gas increases the thermal value of the alcohol vapor. When this combination gas is employed, it is necessary to add water to the alcohol to obtain the same thermal efficiency as procured with gasoline gas. The solution used as fuel contains 17 per cent water and 83 per cent alcohol; as water costs nothing to speak of, the increase in the bulk of fuel nearly pays for the carbide. It is estimated that one pound of carbide is used per gallon of liquid. This combination of alcohol and acetylene has proved efficient on motors employing compression as low as 60 pounds to the square inch and running as high as 2,000 revolutions per minute. If used alone, alcohol vapor burns
Fig. 60.—Bowser Gasoline Storage System Utilizing Underground
Tank Outside of Building and Fuel Pump in Building. slowly and it is more efficient on slow speed, high compression motors than on engines of the present form.
Q. What are the advantages of alcohol?
A. Alcohol has the great advantage that the fire risk is less than with gasoline. A gasoline fire or any burning petroleum product is only spread by water, but burning alcohol is extinguished by it. It is claimed that the exhaust gases from alcohol are cooler and cleaner than those from gasoline vapor and they will deposit less carbon in the combustion chamber. As alcohol is obtained from vegetable substances there is no likelihood of fuel famine because the raw materials are not only found in all parts of the earth, but are reproduced each cycle of seasons and in fact, in tropical countries, there is no cessation to the growth of the vegetation. There has been no serious attempt to date to produce alcohol in large quantities and even the removal of the government tax on the denatured product has not stimulated the production of the liquid.
Q. Is alcohol dangerous?
A. Alcohol is much less dangerous than either kerosene, benzol or gasoline under ordinary conditions. Alcohol used for fuel purposes must be rendered unfit for drinking by substances such as benzine or other distillates of crude petroleum in order to make it unpalatable. As denatured alcohol is poisonous to a degree, it is very dangerous if the chauffeur takes it internally.
Q. How are fuels carried in automobiles ?
A. Liquid fuels are carried in tanks conveniently disposed at various parts of the automobile, depending upon the type of fuel supply system used. In many cars it is carried in a tank under the front seat when a chassis is fitted with a touring body or in a large container back of the seat (Fig. 58) and at the rear end if the car a roadster or two passenger type. On some very powerful machines where it would be difficult to store enough gasoline in a tank under the seat, a large container is carried at the rear end of frame back of the rear axle.
Q. What is the best system of fuel storage?
A. The safest method of handling gasoline and other liquids of like nature when stored in large quantities is to use underground tank outfits as outlined at Figs. 59 and 60. This is a very economical method, because the danger from fire is reduced to a minimum and there is no loss of fuel by evaporation. The liquid may be pumped up from the tank by any simple form of hand pump, some of which are so designed that they will pump only measured quantities of the l.quid.
THEORY OF CARBURETION AND ITS APPLICATION
Q. What is combustion a manifestation of?
A. Combustion always indicates a chemical combination between certain elements which have a great attraction or affinity for each other.
Q. Is combustion always rapid?
A. The rusting of metals or the rotting of wood, cloth and similar materials are examples of slow combustion.
Q. Give an example of rapid combustion.
Ą. Burning gas, wood, coal or oil are examples of rapid combustion.
Q. Give an example of instantaneous combustion.
A. The explosion of gunpowder or of the compressed gas in the automobile engine cylinder may be considered as practically instantaneous combustion.
Q. What is a vacuum and could anything burn in vacuo?
A. A vacuum is a space in which there is no air or other gas present. A vacuum may be nearly complete, but it is almost impossible to obtain a perfect vacuum. If a burning candle is placed under the receiver of an air pump and the air exhausted from the chamber in which the candle burns, it will be noticed that as the degree of exhaustion becomes greater, the flame burns dimmer until it finally goes out.
Q. What is necessary to support combustion?
A. Combustion cannot take place unless air or the element oxygen of which it is partly composed is present.
Q. What is gasoline composed of?
A. Gasoline is composed of carbon and hydrogen. The former is a solid material while the latter is the lightest known gas. When combined chemically, owing to the great affinity that exists between them, they will form a liquid if mixed in the correct proportions.
Q. How much of each element is there in gasoline?
A. The ordinary gasoline used for fuel is said to contain 84% carbon and 16% hydrogen.
Q. What is air composed of?
A. The oxygen has a great affinity or combining power with the two constituents of the hydrocarbon liquids, and it is the oxygen which supports combustion. Nitrogen is an inert gas that is mixed with the air in order to act as a deterrent and prevent too rapid combustion.
Q. How much oxygen is needed to burn carbon?
A. One pound of carbon requires two and one third pounds of oxygen to insure its combustion.
Q. How much air is needed to burn a given weight of carbon?
A. As air is composed of one part of oxygen to three and one half portions of nitrogen by weight, for each pound of oxygen one needs four and one half pounds of air. It requires about ten pounds of air to burn one pound of carbon.
Q. Has air any weight?
A. While one does not consider air as having much weight, fourteen cubic feet of air at a temperature of 62 degrees F. will weigh about a pound.
Q. How much oxygen is needed to burn a given weight of hydrogen?
A. One pound of hydrogen requires 8 pounds of oxygen to burn it. This means that 6 pounds of air will be needed to insure combustion of the hydrogen component of gasoline.