Engineering Thermodynamics Multiple Choice Questions
MCQ
Q.
Choose
the
correct answer for each branch below (only
5):
1.
What
is the use of reheat cycle in steam turbines
?
a)
To
remove the moisture from the
steam
b)
To
increase the steam
temperature
c)
To
increase steam
pressure
d)
None of the
mentioned
2.
In
rankine cycle
with
reheat
how
mny
turbines
work
?
a)
1
b)
2
c)3
d)
4
3.
Ideal Rankine Cycle
is
a
process.
(a)
Reversible
(b)
Irreversible
(c)
Both of the
mentioned
(d)
none of
the
me
n
t
i
o
n
e
d
4.
Carnot cycle
comprises of ........
(a)
two
isentropic processes
and two constant
volume
processes
(b)
two isentropic processes and two constant pressure
processes
(e) two isothermal processes and
three constant
pressure
processes
(d) none of the
above
5.
Rankine cycle operating on
low pressure
limit
of
p1 and high pressure
limit
of
p2
a)
has higher
thermal
efficiency than the Carnot cycle
operating between same
pressure
limits
b)
has lower thermal efficiency than Carnot cycle operating between
same
pressure
limits
c)
has
same
thermal
efficiency
as
Carnot
cycle
operating
between
same
pressure
limits
d)
may
be
more
or less depending upon the magnitudes of p1 and
p2
6.
In
Rankine cycle, the
work
output from the turbine is given
by
a)
change of internal energy between inlet and
outlet
b)
change of enthalpy between inlet and
outlet
c)
change of entropy between inlet and
outlet
d)
change of temperature between inlet and
outlet
7.
Match the
following:
a)
Boiler
b)
turbine
c)
Condenser
d)
pump
1.
reversible adiabatic expansion
of
steam
2.
constant pressure
heat
heat
addition
3.
reversible adiabatic
compression
4.
constant pressure
heat
rejection
Answer: a-2 b-1
c-4
d-3
8.
A
simple Rankine cycle operates the Boiler at
3
MPa
with
an outlet
temperature
of
350°C
and the Condenser at
50
kPa. Assuming ideal operation and
processes,
what
is the thermal
efficiency of this
cycle?
a)
7.7
b)
17.7
c)
27.7
d)
37.7
h1
=
340.5
kJ/kg,
h2
=
h1
+
v1
(P2 –
P1)
=
343.5
kJ/kg,
h3
=
3115.3
kJ/kg, s3 =
6.7428
kJ/kg – K,
x4
=
0.869, and h4
=
2343.9
kJ/kg.
Thus,
η = 1 –
Qout
/
Qin
= 1 –
(h4
–
h1)
/
(h3
–
h2)
=
27.7%.
9.
For analytical
purposes,
the Rankine Cycle
is
assumed
to
be
in?
a)
Unsteady
flow
operation
b)
Turbulent
flow
operation
c)
Steady
flow
operation
d)
Laminar
flow
operation
10.
Carnot engine
follows
a)
Isothermal
process
b)
Isoentropic
process
c)
Isothermal and Isoentropic
process
d)
None of the
mentioned
11.
Working fluid
of rankine cycle
usually
a)
Water
b)
Methane
c)
Hard
water
d)
None of the
mentioned
12.
Steam
turbines
work
on
a)
Rankine
cycle
b)
Carnot
cycle
c)
Dual
cycle
d)
None
13.
W
h
a
t
i
s
t
h
e
p
u
r
p
o
s
e
o
f
r
e
h
e
a
t
c
y
c
l
e
?
a.
to
limit
the
pump
work
b.
to
decrease
heat
input in
the
Rankine
cycle
c.
to
limit
the
quality
of
steam
to
0.85
at
the
turbine exhaust
d.
none
of
the
above
14.
The
below diagram is
the
T-s
diagram
of
the
Rankine cycle with
reheat.
W
h
i
c
h
p
r
o
c
e
s
s
r
e
p
r
e
s
e
n
t
s
t
h
e
r
e
h
e
a
t
?
a.
process
1 –
2
b.
process
2 – 2
′
c.
process
2 ′ – 2
″
d.
process
2 – 3
′
1
5
.
T
h
e
r
e
h
e
a
t
c
y
c
l
e
a
l
l
o
w
s
s
t
e
a
m
p
o
w
e
r
p
l
a
n
t
a.
to use
higher
pressure
ratio
b.
to
maintain required quality
of
steam
at the
exit
of
the
turbine
c.
to
increase
the turbine
work
d.
all
of
the
above
Answer
1.
a
2.
b
3.
a
4.
b
5.
a
6.
b
7.
a-2 b-1
c-4
d-3
8.
c
9.
c
10.c
11.a
12.a
13.c
14.c
15.d
This content covers various topics related to engineering thermodynamics through multiple-choice questions. It includes concepts such as the use of reheat cycles in steam turbines, ideal Rankine cycles, Carnot cycles, and the efficiency of different cycles. Questions on the Rankine cycle, working fluids, steam turbines, and more are addressed in this comprehensive set of MCQs.
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MCQ Q. Choose the correct answer for each branch below (only 5): 1.What is the use of reheat cycle in steam turbines ? a) To remove the moisture from the steam b) To increase the steam temperature c) To increase steam pressure d) None of the mentioned 2. In rankine cycle with reheat how mny turbines work ? a) 1 b) 2 c)3 d) 4 3. Ideal Rankine Cycle is a process. (a) Reversible mentioned (b) Irreversible (c) Both of the mentioned (d) none of the 4. Carnot cycle comprises of ........ (a) two isentropic processes and two constant volume processes (b) two isentropic processes and two constant pressure processes (e) two isothermal processes and three constant pressure processes (d) none of the above 5. Rankine cycle operating on low pressure limit of p1 and high pressure limit of p2 a)has higher thermal efficiency than the Carnot cycle operating between same pressure limits b)has lower thermal efficiency than Carnot cycle operating between same pressure limits c) has same thermal efficiency as Carnot cycle operating between same pressure limits d) may be more or less depending upon the magnitudes of p1 and p2 6. In Rankine cycle, the work output from the turbine is given by a) change of internal energy between inlet and outlet b) change of enthalpy between inlet and outlet c) change of entropy between inlet and outlet d) change of temperature between inlet and outlet 7.Match the following: a) Boiler b) turbine c) Condenser d) pump 1. reversible adiabatic expansion of steam 2. constant pressure heat heat addition 3. reversible adiabatic compression 4. constant pressure heat rejection Answer: a-2 b-1 c-4 d-3
8.A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle? a) 7.7 b) 17.7 c) 27.7 d) 37.7 h1 = 340.5 kJ/kg, h2 = h1 + v1 (P2 P1) = 343.5 kJ/kg, h3 = 3115.3 kJ/kg, s3 = 6.7428 kJ/kg K, x4 = 0.869, and h4 = 2343.9 kJ/kg. Thus, = 1 Qout / Qin = 1 (h4 h1) / (h3 h2) = 27.7%. 9.For analytical purposes, the Rankine Cycle is assumed to be in? a) Unsteady flow operation b) Turbulent flow operation c) Steady flow operation d) Laminar flow operation 10.Carnot enginefollows a) Isothermal process b) Isoentropic process c) Isothermal and Isoentropic process d) None of the mentioned 11. Working fluid of rankine cycle usually a) Water b) Methane c) Hard water d) None of the mentioned 12.Steam turbines work on a) Rankine cycle b) Carnot cycle c) Dual cycle d) None 13.What is the purpose of reheat cycle? a. to limit the pump work b. to decrease heat input in the Rankine cycle c. to limit the quality of steam to 0.85 at the turbine exhaust d. none of the above
14. The below diagram is the T-s diagram of the Rankine cycle with reheat. Which process represents the reheat? a. process 1 2 b. process 2 2 c. process 2 2 d. process 2 3 15. The reheat cycle allows steam power plant a. to use higher pressure ratio b. to maintain required quality of steam at the exit of the turbine c. to increase the turbine work d. all of the above
Answer 1. a 2. b 3. a 4. b 5. a 6. b 7. a-2 b-1 c-4d-3 8. c 9. c 10.c 11.a 12.a 13.c 14.c 15.d
