Applications of Thermodynamics by NEGI10
NTPP & PYQs - 01
Chapter : I.C.ENGINE CYCLES
Topic : Cold air – Standard Otto - Cycle
5. [MCQ, ]
1. [MCQ, ]
Compression ratio (r) of an internal combustion
engine is defined as ______ where, Vs = Swept
Volume & Vc = Clearance volume
A.
Vc +Vs
B.
Vc
C. V
Vc
Vc +Vs
Vs
V
D. Vc
s +Vc
s
The crank radius of a single cylinder I C Engine is
60 mm and the diameter of the cylinder is 80
mm. The swept volume of the cylinder in cm3 is
A. 48
B. 96
C. 302
D. 603
[GATE-2011-ME]
6. [MCQ, ]
2. [NAT, ]
If the stroke volume is 600 cc and the clearance
volume is 60 cc, then the compression ratio will
be ______ (round off to nearest integer).
3. [NAT, ]
The bore and stroke of the cylinder of a six
cylinder engine working on Otto cycle are 17 cm
Which of the following is NOT a correct
assumption for the Cold air-standard analysis
A. All processes are internally reversible.
B. There are no Intake and exhaust processes
as in actual engine.
C. The combustion processes is always constant
volume heat addition process.
D. The working fluid, air is an ideal gas with
constant specific heats.
and 30 cm respectively. If the total clearance
volume of 6 cylinders is 9225 cm3 , then the
compression ratio is ______ (round off to one
decimal place).
4. [NAT, ]
An engine having three cylinders with total
displacement
volume
of
770 cc.
If
the
compression ratio is 8.7, then each cylinder has
a clearance volume of _____ cc (round off to
two decimal place).
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7. [MSQ, ]
Choose the correct statement(s) regarding
reciprocating internal combustion engines
A. Reciprocating internal combustion engines
are primarily external combustion engines.
B. Minimum volume contained within the
cylinder is known as clearance volume.
C. The reciprocating motion of piston is
converted into rotary motion by a crank
mechanism.
D. Inner diameter of the cylinder is known as
stroke.
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8. [MCQ, ]
9. [MCQ, ]
Choose the correct statement regarding internal
combustion engines
A. Internal combustion engines undergoes both
mechanical cycle & thermodynamic cycle.
B. Internal
combustion
engines
neither
undergoes
mechanical
cycle
nor
thermodynamic cycle.
C. Internal combustion engines undergoes
mechanical cycle but not thermodynamic
cycle.
D. Internal combustion engines undergoes
thermodynamic cycle but not mechanical
cycle.
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For the reciprocating internal combustion
engines bore is 0.25 m while stroke length is
0.675 m. If the minimum volume of the cylinder
is 10000 cm3 then the most appropriate
statement is
A. Clearance ratio is 0.3 Compression ratio is
3.3.
B. Clearance ratio is 3.3 & Compression ratio is
4.3.
C. Clearance ratio is 0.3 & Compression ratio is
4.3.
D. None of the above
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Answer Key
1.
2.
3.
4.
5.
(A)
(11 to 11)
(5.2 to 5.6)
(33.05 to 33.65)
(D)
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6.
7.
8.
9.
(C)
(B & C)
(C)
(C)
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Solutions
1. Answer: (A)
Solution:
4. Answer: (33.05 to 33.65)
Solution:
Compression ratio (r) =
Vc + Vs
Vc
r
Vc  Vs
Vc
8.7 
2. Answer: (11 to 11)
Solution:
Vc  Vs
Vc
VS  600cc ; Vc  60cc
8.7Vc  Vc  Vs
V  Vs
Compression ratio r  c
Vc
7.7Vc  770
r
60  600 660

 11
60
60
 r  11
Compression ratio r 
Vmax
Vmin
 2
V

D L n
c
Vc  Vs
4


Vc
Vc

Each cylinder 
100
3
Vc  33.33cc
3. Answer: (5.2 to 5.6)
Solution:
9225 
 Vc  100

2
17  30 6
4
9225
5. Answer: (D)
Solution:
π
Vs = D2 L
4
π 2
Vs = D (2rc )
4
π
Vs = (0.08)2 (2 × 0.06)
4
Vs = 6.031 × 10−4 m3
Vs = 603.1 cm3
r  5.4
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