Alcohol

ALCOHOL

ALCOHOL SUBJECT : ALTERNATE FUELS & ENERGY M.E. (I.C. ENGINE & AUTOMOBILE) 1st SEM.L.D.C.E. AHMEDABAD

PREPARED BY : VIVEK DHAMELIYA HARDIK BAMBHANIA 1. INTRODUCTION

There is nothing new in the use of alcohol as a fuel. In 1872, when Nikolaus Otto invented the internal combustion engine, gasoline was not available. Ethyl alcohol was the specified fuel. The model T Ford was designed to run on the available crude gasoline, alcohol, or any combination of two.2. CLASSIFICATION

Generally two types of alcohol are used as a fuel, Methanol and Ethanol. Methanol (CH3OH) is an alcohol with one carbon, Ethanol (CH3CH2OH) is an alcohol with two carbons.A) METHANOL

Methanol, also known asmethyl alcohol, wood alcohol,wood naphthaorwood spirits, is a chemical with theformulaCH3OH Methanol acquired the name "wood alcohol" because it was once produced chiefly as a byproduct of the destructive distillationof wood.Production

i) From synthesis gas Carbon monoxide and hydrogen react over a catalyst to produce methanol.

CO + 2 H2 CH3OH

Today, the most widely used catalyst is a mixture of copper, zinc oxide, and alumina

ii) From methane

A direct catalytic conversion of methane to methanol using Cu-zeolites or other catalysts is an alternative process for the efficient production of methanol.

Properties

It has very high latent heat of vaporization (volatility) (474 Btu/lb) which is around three time higher than the volatility of gasoline (140 Btu/lb)Combustion of Methanol required less stoichiometric air ratio (6.45 : 1) whereas in case of gasoline combustion it is 15 : 1.Boiling temperature 1450 F ( 620 C)It has high octane number (106)It is a light, colorless and toxic in natureAdvantages

Due to high latent of vaporization methanol and air mixture cool down three times more than gasoline air mixture which increase the volumetric mass efficiency and hence power output.Due to very high octane number it has good antiknock characteristic and it can allow the use of high compression ratio.Only slight change is required for conversion of gasoline system to methanol system.Water injection is possible to increase the power.It has very less sulphur content.

Disadvantage

Calorific value is low compared to gasoline so reach fuel mixture is required.It is more corrosive than gasoline so special oil additives are necessary in order to protect the engine.It is a toxic in nature.Methanol flame is colorless so present of fire cannot be easily detected.Methanol, being a pure chemical compound, has a single boiling point, so that it can cause cold-start problems in cold weather or vapor lock in hot.

B) ETHANOL

Commonly referred to simply as alcohol orspirits,ethanolis also calledethyl alcohol,it is used as asolvent, as anantiseptic, as afueland as the active fluid in modern (post-mercury)thermometers. It is avolatile,flammable, colorless liquid with the structural formulaCH3CH2OH, often abbreviated asC2H5OH or C2H6O.Production

i) FermentationEthanol is produced bymicrobial fermentationof the sugar(From sugar cane) and starch( From corn). Microbial fermentation currently only works directly withsugars.

C12H22O11+H2O 4CH3CH2OH + 4 CO2 C6H12O62CH3CH2OH + 2 CO2

ii) Ethylene hydration

Ethanol for use as an industrial feedstock or solvent is made frompetrochemicalfeed stocks, primarily by theacid-catalyzedhydration of ethylene, represented by thechemical equation.

C2H4 + H2OCH3CH2OH

The catalyst is most commonlyphosphoric acid

Properties

It has very high latent heat of vaporization (volatility) (361 Btu/lb) which is around 2.5 time higher than the volatility of gasoline (140 Btu/lb)Combustion of ethanol required less stoichiometric air ratio (9 : 1) whereas in case of gasoline combustion it is 15 : 1.Boiling temperature 173.3 0 F (78.5 0 C)It has high octane number (106).

Advantages

Regular cars can handle up to 10% ethanol without engine reconstruction.Unlike gasoline, ethanol is renewable resource.Ethanol burns more cleanly in air than petroleum, producing less carbon (soot) and carbon monoxide.Due to very high octane number it has good antiknock characteristic and it can allow the use of high compression ratio.

Disadvantages

Ethanol has lower calorific value.Large amount of land are required to produce crops to obtain ethanol.It is corrosive in nature.Typical current engine require modification to use high concentration of ethanol.There is a danger of storage tank due to lower vapor pressure.

4. METHODS OF UTILISATION

A) Alcohol blends

Alcohol blends have the advantage that up to 10 % concentration of alcohol may be used without modification to the engine. The main disadvantage is that the alcohol you use must be perfect dry. However drying the alcohol does require a separate manufacturing step and expenditure of additional energy.

B) Pure alcohol

The advantages of burning relatively pure 80 to 95% alcohol are several. First of all, because the drying step is unnecessary overall cost is less than the gasoline. Secondly, you can leave 5 to 15% water in the alcohol and you get advantage of water injection.The only disadvantage is the trouble and expense of modifying the engine.

C) Diesel engine

Generally diesel engine can be run on pure alcohol, but the main problem is in the lubrication of the injectors. This is solved by the addition of 5 to 20% vegetable oil to the alcohol.

QUESTIONS

Explain the advantages and disadvantages of using Methanol in I.C. engine.Explain the advantages and disadvantages of using Ethanol in I.C. engine.Explain the production process for Methanol and Ethanol.What are the methods for utilization of alcohol in I.C. engine ? Explain it.What do you mean by water injection in case of I.C. engine ?THANK YOU