UNIT- 5 (2 MARKS QUESTIONS)

ALTERNATIVE ENERGY SOURCES

1. List the advantages of hydrogen fuel used in automobiles.

o It can be manufactured from water through electrolysis process

o It does not contain carbon. Hence, CO and unburned HC emissions
are not present
o The flame speed is highest. Hence it results in high thermal
efficiency
o It has wide ignition limits.

2. What is a hybrid vehicle?

A hybrid vehicle is a vehicle that uses two or more distinct power sources to move
the vehicle. The term most commonly refers to hybrid electric vehicles (HEVs),
which combine an internal combustion engine and one or more electric motors.

3. What is a fuel cell?

A fuel cell is an electrochemical device that converts a source fuel into an

electrical current and water. It generates electricity inside a cell through reactions
between a fuel and an oxidant, triggered in the presence of an electrolyte.

4. Define detonation and pre-ignition.

The abnormal combustion occurring in IC engines is called as detonation. This
results in sudden rate of pressure rise, abnormal heat release, heavy vibrations of the
engine and loud noise operation.

The ignition of the air-fuel mixture before the introduction of the spark in the
combustion chamber is called as pre-ignition.

5. What are the advantages of an electric car?

o No emissions from an electric car
 It does not depend upon the availability fossil fuels
6. State the advantages of fuel cell.
o Higher efficiency than diesel or gas engines.
o Quiet operation.
o Fuel cells can eliminate pollution problems

o Don’t need conventional fuels such as oil or gas and can therefore reduce
economic dependence on oil producing countries, creating greater energy
security for the user nation.
o The maintenance of fuel cells is simple since there are few moving parts in the
system.

7. What are the types of fuel cell?

o Proton exchange membrane fuel cell
o Alkaline fuel cell
o Phosphoric acid fuel cell
o Direct methanol fuel cell
o Solid oxide fuel cell
o Molten carbonate fuel cell

8. What are the alternative fuels?

Alcohols, Hydrogen, Natural Gas, CNG, LNG, LPG, Bio Gas, Producer Gas, Coke
oven Gas, Water Gas, Gasohol, Biodiesel

9. What are the various properties of gaseous fuel?

Advantages
Gaseous fuels due to erase and flexibility of their applications possess the following
advantages over solid or liquid fuels:

(a) They can be conveyed easily through pipelines to the actual place of need, thereby
eliminating manual labour in transportation.
(b) They can be lighted at ease.
(c) They have high heat contents and hence help us in having higher temperatures.
 (d) They can be pre-heated by the heat of hot waste gases, thereby affecting economy
in heat.
(e) Their combustion can readily by controlled for change in demand like oxidizing
or reducing atmosphere, length flame, temperature, etc.
(f) They are clean in use.
(g) They do not require any special burner.
(h) They burn without any shoot, or smoke and ashes.
(i) They are free from impurities found in solid and liquid fuels.
Disadvantages

(a) Very large storage tanks are needed.

(b) They are highly inflammable, so chances of fire hazards in their use is high

10. What is CNG?

Compressed Natural Gas. It is typically stored in a tank at a pressure of 3,000 to
3,600 pounds per square inch

11. . What is BIO- DIESEL? State its advantages.

Biodiesel is a non-petroleum based diesel fuel which consists of the mono

alkyl esters of long chain fatty acids derived from vegetable oil and animal fats.

Advantages

o Domestically produced from non-petroleum, renewable resources

o Can be used in most diesel engines, especially newer ones
o Less air pollutants (other than nitrogen oxides)
o Less greenhouse gas emissions (e.g., B20 reduces CO2 by 15%)
o Biodegradable
o Non-toxic
o Safer to handle

12. What are advantages of LPG over conventional fuels?

o LPG contains less carbon than petrol
o LPG mixes with air at all temperatures
 o In multi cylinder engines, a uniform mixture can be supplied to all cylinders
o Since the vapour in the form of vapour, no crankcase dilution
o Automobile engines can use propane if they use high compression ratio.
o LPG has better antiknock characteristics
o Running on LPG produces fuel saving cost of about 50%
o The engine will have 50% longer life.

13. What are the disadvantages of using alcohol as an alternative fuel?

o A larger quantity of fuel is required to produce a specified power output. For
example, in an automobile, more fuel is required for each mile driven.
o Low boiling points and high vapor pressures of methyl and ethyl alcohol
indicate that vapor lock could be a serious problem, particularly at high
altitudes on warm summer days.
o The relatively high latent heats of methyl and ethyl alcohol cause problems in
mixing these alcohols with air and transporting them through the intake
manifold of the engine. Heating the intake manifold may be necessary in cold
weather or before the engine reaches operating temperatures.
o Without external heat to more completely vaporize the fuel, the engine may
be difficult to start and sluggish for a considerable time after starting.
o All of the alcohols are soluble in water, but butyl alcohol is relatively
insoluble compared to methyl and ethyl alcohol. Less engine power is
produced as the water content of an alcohol increases. Further, vapor lock,
fuel mixing and starting problems increase with water.

14. Define flame speed.

The speed at which flame travels inside the combustion chamber is called as flame
speed. The unit is m/s

15. List out the various forms of natural gas.

o Natural Gas (NG)
o Compressed Natural Gas (CNG)
o Liquefied Natural Gas (LNG)
 16. Write down the components of LPG equipment.
o Converter
o Mixer
o Gas Injector
17. Write down the parts of a fuel cell.
o Anode
o Cathode

o Electrolyte

o Fuel

18. What are the properties of CNG?

o Colourless
o Odourless

o Lighter than air

o Non - toxic

19. What are the two types of LPG used for automotive-engine fuel?
o Propane based LPG
o Butane based LPG

20. What are the main components of electric and hybrid vehicles?
o Gasoline engine
o Fuel tank

o Generator

o Electric motor

o Battery

o Transmission elements

21. What are the advantages of fuel cell?

o The only by product from the fuel cell is either water or CO2, which can be safely
disposed.
o It is compact in size
 o As long as there is a supply of fuel, there will be generation of electricity.

22. What are the advantages of Gasohol?

Gasohol – It is the mixture of 10 % Ethanol + 90 % unleaded gasoline

o 10 % fuel savings in terms of consumption of petrol

o Less emissions than conventional petrol fuelled vehicles

PART-B

1. How bio diesel is produced? Explain and its usage in automobiles.

ANSWER:
Biodiesel is made through a chemical process called transesterification whereby
the glycerin is separated from the fat or vegetable oil. The process leaves behind two
products -- methyl esters (the chemical name forbiodiesel) and glycerin (a valuable
byproduct usually sold to be used in soaps and other products).

The key elements of the regulatory control are as follows:

(a) Motor vehicle biodiesel specifications (Sections 2, 10 and Schedule 3)

Motor vehicle biodiesel includes pure biodiesel and biodiesel blends that are
blended from pure biodiesel and motor vehicle diesel and their respective
specifications are

(i) pure biodiesel that is supplied or sold for motor vehicle use has to comply
with the specifications as stipulated in Schedule 3 of the Regulation. The
specifications are in general comparable with European Union standard EN14214;
and

(ii) biodiesel blends that are supplied or sold for motor vehicle use must be
blended from pure biodiesel and motor vehicle diesel, the specification of which is
stipulated in Schedule 1 of the Regulation (i.e. Euro V standard for motor vehicle
diesel).

(b) Labelling requirements (Sections 11, 12 and Schedule 4)

 (i) a label (sample given below) is required for selling the motor vehicle
biodiesel with biodiesel content over 5%; and

(ii) the biodiesel content in the motor vehicle biodiesel expressed in

percentage should not deviate from the percentage of biodiesel content indicated on
the label by more than one percent (For example, a motor vehicle biodiesel with its
biodiesel content of 15% specified on the label should have its biodiesel content
between 14% and 16%, both inclusive).

2. Explain the operation of hydrogen fueled vehicle with neat sketch.

ANSWER:

A hydrogen vehicle is a vehicle that uses hydrogenas its onboard fuel for motive power.
... The power plants of such vehicles convert the chemical energy of hydrogen to
mechanical energy either by burninghydrogen in an internal combustion engine, or by
reacting hydrogen with oxygen in a fuel cell to run electric motors.

WORKING:

Hydrogen fuel cell vehicles combine the range and refueling of conventional cars
with the recreational and environmental benefits of driving on electricity.

Refueling a fuel cell vehicle is comparable to refueling a conventional car or truck;

pressurized hydrogen is sold at hydrogen refueling stations, taking less than 10 minutes to
fill current models. Some leases may cover the cost of refueling entirely. Once filled, the
driving ranges of a fuel cell vehicle vary, but are similar to the ranges of gasoline or
diesel-only vehicles (200-300 miles). Compared with battery-electric vehicles—which
recharge their batteries by plugging in—the combination of fast, centralized refueling and
longer driving ranges make fuel cells particularly appropriate for larger vehicles with
long-distance requirements, or for drivers who lack plug-in access at home.

Like other EVs, fuel cell cars and trucks can employ idle-off, which shuts down
the fuel cell at stop signs or in traffic. In certain driving modes, regenerative braking is
used to capture lost energy and charge the battery.
3. Explain the working principle of fuel cell with neat sketch.

ANSWER:

A fuel cell is an electrochemical device that produces electricity without

combustion by combining hydrogen and oxygen to produce water and heat.
Working Principle
A fuel cell is a device that uses hydrogen (or hydrogen-rich fuel) and oxygen to
create electricity by an electrochemical process.
A single fuel cell consists of an electrolyte sandwiched between two thin
electrodes (a porous anode and cathode) Hydrogen, or a hydrogen-rich fuel, is fed to
the anode where a catalyst separates hydrogen's negatively charged electrons from
positively charged ions (protons) At the cathode, oxygen combines with electrons
and, in some cases, with species such as protons or water, resulting in water or
hydroxide ions, respectively.
The electrons from the anode side of the cell cannot pass through the membrane to
the positively charged cathode; they must travel around it via an electrical circuit to
reach the other side of the cell.
This movement of electrons is an electrical current. The amount of power
produced by a fuel cell depends upon several factors, such as fuel cell type, cell size,
the temperature at which it operates, and the pressure at which the gases are supplied
to the cell Still, a single fuel cell produces enough electricity for only the smallest
applications.
 Therefore, individual fuel cells are typically combined in series into a fuel cell
stack. A typical fuel cell stack may consist of hundreds of fuel cells. Fuel cells are
classified primarily by the kind of electrolyte they employ. This determines the kind
of chemical reactions that take place in the cell, the kind of catalysts required, the
temperature range in which the cell operates, the fuel required, and other factors.

4. Discuss the operation of an LPG propelled vehicle with neat sketch.

ANSWER:
WORKING:

The process of converting a car to run on propane is fairly demanding and requires
a good knowledge of automotive systems in general to accomplish.* Several companies
offer kits that include all the needed parts to perform the conversion. Those without the
necessary know-how should try to find a local mechanic with experience in LP-gas
conversions to get the job done. Although propane is very safe as an automotive fuel, if
the system is not installed correctly, there can be safety problems.

The first step is choosing a tank. Most conversions are dual-fuel conversions,
meaning you won't be replacing your old fuel system, you'll simply be adding a second.
As a result, the propane tank will take up some of the storage space in your car, usually in
the trunk.
 A solenoid valve (LPG valve in the above diagram) must be installed on the fuel
line in between the tank and the engine. This valve cuts the flow of LP gas when the car is
running on gasoline and when the engine is shut off. It also has a filter built in that
removes any dirt that may be in the fuel.

The next major component is called a regulator, also referred to as a vaporizer.

This device performs one of the functions that a carburetor handles in a gasoline engine -
it uses heat from the car's cooling fluids to vaporize the propane into gas form. Another
safety check occurs at the regulator, as well. It includes an electronic circuit that cuts the
flow of gas if the engine stops or stalls. The regulator is usually smaller than a regular
carburetor, so finding space for it in the engine compartment shouldn't be a problem.

5. Explain the concept of hybrid vehicles with neat sketch.

ANSWER:
WORKING:

In mild hybrid cars, the electrical motor is used only when additional power is needed.
The conventional engine is used to provide most of the power. The electrical motor alone
cannot operate the vehicle. Whenever power is needed the electric motor acts as a side-kick
to the conventional engine. Some vehicles that carry this concept is the Honda Civic and
Insight.
 In a full hybrid car, the electrical energy is used while the car needs less
power. The gasoline energy is used when the car needs less power. Thus at lower
speeds the battery drives the vehicle and at higher speed the gasoline drives the
vehicle. This technology has been used in cars like Toyota Prius and Ford Escape.

Both of them though have a little different mode of operation provide the same
amount of efficiency.

Advantages Of Hybrid Cars

 Very less pollution.

 Better mileage.
 More reliable and comfortable.

Disadvantages Of Hybrid Cars

 The initial cost will be very high – higher than other cars.
 Since a lot of batteries will be needed, the car will be very heavy.