Automobile Engineering Problems on “Alternative Fuels for IC Engines”.
1. Which of the following statements is not correct with respect to alcohols as alternate fuel?
a) Anti-knock characteristics of alcohol are poor
b) Alcohol contains about half the heat energy of gasoline/liter
c) Alcohol does not vaporize as easily as gasoline
d) Alcohols are corrosive in nature
Clarification: Alcohol is a high octane fuel. It has an anti-knock index number of over 100. The engines which use the high octane fuel run more efficiently by using higher compression ratios.
2. Why a small amount of gasoline is added to alcohol?
a) To reduce the emission
b) To increase the power output
c) To increase the power efficiency
d) To improve cold-weather starting
Clarification: When a small amount of gasoline is added to alcohol, it improves cold-weather starting. Alcohols have low energy content. This means that almost twice as much alcohol as gasoline must be burned to give the same energy input.
3. What is gasohol?
a) 90% ethanol + 10% gasoline
b) 10% ethanol + 90% gasoline
c) 40% ethanol + 60% gasoline
d) 50% ethanol + 50% gasoline
Clarification: Gasohol is 10% ethanol and 90% gasoline. Gasohol is also known for E10. E10 reduces the use of gasoline with no modification needed to the automobile engine. E10 is basically an alcohol fuel with 90% gasoline added to eliminate some of the problems of pure alcohol.
4. Which of the following is a disadvantage of hydrogen as a fuel in IC engine?
a) Storage is easy
b) Low NOx emissions
c) Detonating tendency
d) Easy handling
Clarification: The disadvantage of hydrogen fuel is that the detonating tendency. The other disadvantages of hydrogen fuel are high NOx emissions because of high flame temperature and difficult to refuel.
5. Which of the following is the advantage of the hydrogen as a fuel?
a) High volumetric efficiency
b) Low fuel cost
c) No HC and CO emissions
d) Relatively safe
Clarification: The advantage of hydrogen fuel is no hydrocarbon and CO emissions. The most exhaust gases would be H2O and N2 and NOx.
6. What is the major disadvantage of LPG as a fuel in the automobile?
a) Reduction in the life of the engine
b) Less power compared to gasoline
c) Reduction in the life of the engine and less power compared to gasoline
d) Knocking tendency
Clarification: The major disadvantage of LPG is the reduction in the life of the engine and less power compared to gasoline. The other disadvantage of LPG is a special fuel feed system is required for liquid petroleum gas (LPG).
7. Why alcohols cannot be used in CI engines?
a) Alcohols have a high self-ignition temperature
b) The latent heat of vaporization is low
c) Alcohols have high self-ignition temperature and low latent heat of vaporization
d) High efficiency
Clarification: Alcohols have high self-ignition temperature and low latent heat of vaporization. That is why they cannot be used in CI engines.
8. Which of the following is the major constituent of natural gas?
Clarification: Methane is the major constituent of natural gas. The composition varies from place to place and from time to time. Natural gas is a mixture of components, consisting, mainly of methane (65-95%) with small amounts of other hydrocarbon fuel components.
9. Why methanol is not used in CI engine?
a) Its octane number is high
b) Its cetane number is low
c) Its octane number is high and the cetane number is low
d) Its octane number is low and the cetane number is high
Clarification: Methanol is not used in CI engines because of its high octane number and low cetane number. Pure methanol and gasoline in various percentages have been extensively tested in engines and vehicles for a number of years.
10. What is octane number of natural gas?
Clarification: The octane number of natural gas ranges between 80 and 100, due to which it is used as SI engine fuel. The advantages of natural gas are low engine emissions.