Question 1

Fuel oil consumption guarantees for I .C. engine are usually based on

Accepted Answer

A)  low heat value of oil
B)  high heat value of oil
C)  net calorific value of oil
D)  calorific value of fuel B

Question 2

The amount of heat liberated by complete combustion of unit quantity of fuel is known as ________

Accepted Answer

A)  Agitation
B)  Combustion
C)  Calorific value
D)  Thermogenesis C

Question 3

Diesel fuel, compared to petrol is

Accepted Answer

A)  less difficult to ignite
B)  just about the same difficult to ignite
C)  more difficult to ignite
D)  highly ignitable C

Question 4

The Bomb calorimeter is used to determine the calorific value of:

Accepted Answer

A)  solids and liquid fuels
B)  solid and gaseous fuels
C)  liquid fuels that can be easily vaporized
D)  solid fuels only

Question 5

The major loss in a SI engine is due to

Accepted Answer

A)  exhaust blow down
B)  pumping
C)  incomplete combustion
D)  variation in specific heat and chemical equilibrium

Question 6

The major loss in a CI engine is

Accepted Answer

A)  direct heat loss
B)  loss due to incomplete combustion
C)  rubbing friction loss
D)  pumping loss

Question 7

The ratio of the actual efficiency and the fuel-air cycle efficiency for CI engines is about

Accepted Answer

A)  0.2-0.3
B)  0.5-0.6
C)  1.0
D)  0.6-0.8

Question 8

Which calorimeter is used to find calorific values of solid and liquid fuels?

Accepted Answer

A)  Boy's calorimeter
B)  Bomb calorimeter
C)  Junker's calorimeter
D)  Calvet-type calorimeter

Question 9

What is the factor on which, difference between the two heating values of fuel depends on?

Accepted Answer

A)  Physical properties
B)  Reactants
C)  Chemical composition
D)  Products

Question 10

All heat engines utilize

Accepted Answer

A)  low heat value of oil
B)  high heat value of oil
C)  net claorific value of oil
D)  calorific value of fuel

Question 11

Dissociation can be considered as

Accepted Answer

A)  disintegration of combustion products at high temperature
B)  reverse process of combustion
C)  heat absorption process
D)  all of the above

Question 12

Fuel-air cycle efficiency is less than air-standard cycle efficiency by an amount equal to

Accepted Answer

A)  pumping loss
B)  friction loss
C)  loss due to specific heat variation and chemical equilibrium
D)  exhaust blow down loss

Question 13

Combustion in compression ignition engines is

Accepted Answer

A)  homogeneous
B)  heterogeneous
C)  both (a)  and (b) 
D)  laminar

Question 14

If the intake air temperature of I.C. engine increases, its efficiency will

Accepted Answer

A)  increase
B)  decrease
C)  remain same
D)  unpredictable

Question 15

Time loss factor in actual cycle is due to

Accepted Answer

A)  Progressive combustion
B)  heat loss through cylinder walls
C)  gas leakage
D)  friction

Question 16

Which gas has the highest calorific value among given option?

Accepted Answer

A)  Oxygen
B)  Helium
C)  Hydrogen
D)  Nitrogen

Question 17

The volumetric efficiency is affected by

Accepted Answer

A)  the exhaust gas in the clearance volume
B)  the design of intake and exhaust valve
C)  valve timing
D)  all of the above

Question 18

In a typical medium speed, 4-stroke cycle diesel engine

Accepted Answer

A)  fuel injection starts at 10° before to dead center and ends at 20° after tor dead center
B)  fuel injection starts at top dead center and ends at 20° after top dead center
C)  fuel injection starts at just before top dead center and ends just after top dead center
D)  may start and end anywhere

Question 19

The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is

Accepted Answer

A)  same
B)  less
C)  more
D)  more or less depending on power rating

Question 20

What is the significance of calorific value?

Accepted Answer

A)  Helps in deciding which fuel is good
B)  Helps in locating fuel
C)  Helps in deciding ignition temperature
D)  Helps in deciding fire point

Exam 3: Combustion and Efficiency in Engines