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2
3.
4
d) What are the various types
of
plain carbon steel? List important mechanical properties and
their common industrial applications.
20
a)
b)
a)
b)
a)
15
30
SECnON
5. Answer any three of the following:
a) During orthogonal machining with an HSS Tool, the r ke angle w s 50, the unreformed chip
thickness was 0.2 5 mm and width of cut w s 4 mm. Assuming shear strength of work
material to be 350 N/mm
2
and coefficient of friction to
be
0.5, estimate cutting force and
thrust force.
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' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ~
20
b) List various types of chips that are formed
in
cutting and the conditions
in
which they occur.
20
(c) Following is information regarding a manufacturing enterprise:
d)
6.
a)
b)
Total fixed costs= Rs. 4,500
Total variable costs= Rs. 7,500
Total
sales=
Rs. 15,000
Uru
ts sold= 5,00 0
Ftnd out
t)
Break-even
pomt
m umts
(u)
(tv) Volume of sales to earn a profi t of Rs 6,00 0
111) Profit
A
work
measurement study was conducted
t
a manufactunng com any for 8 hours and
following observations were made: . .
Idletime: 15
CJ '
Performance rating: 120
Allowance tune: 12 of standard t ime flj
Number ofunits produced: 320
Calculate the standard
time
for the task.
20
Prove that
in
ing esistance-cap acitance relaxation circuit with a constant DC source,
for maximum p ' fe ' v , the discharge voltage should be
72 of
supply voltage.
How is th
MR
R ted by variation
in
resistance, mean current, capacitance and spark
gap?
M1 M1 M
M4 MS
Ob
Jt
30
7 4
28
4
J
4
24
Z7
21 Stl
J3
4
S2
33 3 35
J4
25 58 to
36
36
S
9
62 41 34 99
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I
P A P i : ~
mil
SEC11 NA
Answer any three of the following -
(a) With the help
of
Maxwell's relation
of
thermodynamics, prove
b)
c)
coefficient,
IJ J of
a gas is given by the foll
w i n ~
expression:
~ J = ~ ) k = ~ : [ ; ; ) J ~
A 0 8
kg
metal
bar
kept initially at
50
0C is removed sudden y fro an o en and quenched
by immersing
it in
a closed tank containing 12 kg
of
water keptin iti
li
00C.
The
metal
and water can be modeled
as
incompressible and the
s p e i f i ~ t e r
and metal are 4.18
kJ/kg-K and
05
kJ kg-K respectively. The heat transfer
o
tank may
be
neglected.
Work out the following
J
20
(i) Draw the system and system boundary ~ ~
u m p t o n s
made
(ii) The final temperature
of
metal bar T
(iii)
The
entropy produced
Draw the characteristic curves b etw the o ng parameters for an SI engine
(i)
Air
standard efficiency v mp sion ratio
(u) Relative effictency
~
ratio
111)
Brake thermal ef, ten vs oad
(tv) Volumetnc
~
~
ngme speed
(v)
P e a k e
ature vs Equtvalence ratto
Dtscuss
st
m f i n each case m the
hght
of destgn parameters
4 5
(d) A
rect
co
tp
er plate I0 em
x 50
em, having a mass of I kg and at a temperature of
I
0
C, st
ded vertically in still air at 20 C so that 50 em side is vertical. Neglecting
feet, find heat transfer coefficient due to natural convection and initial rate of
of
th
e plate
in
C/minute
for copper=
38
3 Jlkg-K
\. -n?e
properties
of
air at mean temperature 0C are
p
=
106
kg/m
3
,
v = 18.97
x
1
6
m
2
/s
Pr = 0.696, Cp = 1.005 kJ kg-K
k = 28.96
x
1
3
W/m-K
IJ = 20.1 x 1
6
N-s/m
2
.
You may
use
the following correlation:
Nu 0.1 (Cr
Pr)
113
Will the result change
if I
0 em side
is
vertical? Why?
20
.:;
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2 (a)
(b)
3. (a)
(b)
A counterflow heat exchanger acting as a recup erator,
of
gas turbine receives compressed air
operating
at
steady state at 65 0 K, 12 bars and exits at 850 K, 11.6 bars. Hot combustion from
the exhaust of gas turbine enters as a separate stream at I 000 K, 1 1 bars and comes out at I
bar. The mass flow rate of each stream is 200 kg/s. The heat transfer from the outer surface of
the heat exchanger
to
surroundings may be neglected. The changes in kinetic and potential
energy are negligible. Take To = 228 K and
Po
= I bar. Assume ideal gas model for
combustion gas. Work out the following:
30
(i) Draw the system and show the temperature distribution for each stream
(ii) The exit temperature
of
combustion gas
(iii) The net change in the flow energy rate from inlet to outlet for each stre
(iv) The energy distribution rate
0
(v) Comment on the results
During summer to cool water for drinking purpose, 2 kg of iceGt
-3
t
an insulated
container which is subjected to atrno spheric pressure of I bar.
Assume sp ectfic heat of tee ts 2 09 3 kJ kg-K and Iatent hea0 ~ 5 kJ kg Work out the
followmg
.
30
(u) The temperature of the mtxture
(1)
Draw the system and showtheprocessrB
Q ~
t c e and water
111) The change of entropy for mstant, usp c
Derive an expression for air-fuel
r a t i o
y
a simple carburetor, neglecting the effect
of
compressibility Discuss the
t m p l e carburetor. What are the modifications
incorporated for its use in
e s ?
1
O+ IO+I
0
A four-stroke petrol engin 30
kW at 2600 r.p.m. The compression ratio of the
engine is 8 and its fuel o is 84 kglh with calorific value
of 44
MJ kg. The air
consumption
of
the
a.
easured by means
of
a sharp edge orifice
is
2m
3
per
mm.
If
the ptston d i s p l
v
ume ts 2 hters, calculate
(1) etnc ctency
el ra
lio
....
e a n
effective pressure
B - e thermal efficiency
~ " ' : : l l . Relative efficiency
6 X 5
e
ambient temperature of air can be taken as 27C, R for air as 287 J/kg-K
andy=
14. The
barometer reads 755 mm ofmercury.
4.
A counterfoil, concentric tubes heat exchanger is designed to heat water from
20 C
to 80c
using hot oil flowing through the annulus. The oil temperature gets reduced from
160 C
to
140 C.
The nominal diameter
of
the inner tube
is 20 mm
and the corresponding overall heat
transfer coefficient is 500 W/m
2
-
K. The heat transfer rate from the oil is 30 00 watts.
Determine the length
of
the exchanger. Because
of
fouling after some days
the
outlet
temperature of water reduced to 65 C for the same flow rates and same inlet conditions.
Determine the outlet temperature
of
oil, the fouling factor and the new heat transfer rate.
Sketch the heat exchanger arrangement and the temperature pro files.
30
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6. (a)
(b)
and flows at a velocity of I 0 m/s. If the steam mass flow rate is 90 kg/s, find the number and
length of coils.
For steam at
60
bars, take the following values-dry saturated steam h = 2784.3 kJ/ kg, at
500e superheated steam temperature=
3422.2
kJ/ kg and specific volume
Vrop
=
0.05665
m
3
1kg. The steam enters the superheater as ry and saturated.
20
A v refrigerating machine using R-12 refrigerant pro duces I 0 tonnes
of
refrigeration at I 0
oe
when the ambient is at
35e.
A
temperature difference
of
minimum
5e
is required at the
evaporator and condenser for spontaneous heat transfer The refrigerant 1s ry s t u r
the
outlet and to the 1nlet
of
compressor The ad1abattc effic1ency
of
the
c o m p r e s s o ...
enthalpy at the end of1sentrop1c compression 1s estimated to be 370 kJ/
kg
:)eternu::p p
20
ii)
-J
Explain
cooling load estimation for comfort air-conditioning in the
~ b i ~
concept
of
different Sensible Heat Factors SHFs) and Importance m
atr-condittonmg system
30
7
. l
P n the concept
of
types
of
s1m1lanttes between model and prototype What do you mean
6y"d1storted model? What are 1 s advantages? It 1s proposed to
des1gn
a ship The proposed
ship prototype)
1s
havmg a length
of
50
m and a wetted surface area
of
2
00
0
m
2
wtth a
speed of 40 kmlh
A
model of
I
2 0 1s to be tested m the
Iab
oratory at a velo a ty
correspondmg to the w Ne resistance The total drag of the model 1s
50
N Deternune the
following:
15 25
i) Wave resistance drag of the model
ii) Wave resistance drag
of
the prototype
iii) Friction drag of he prototype
Give,
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8.
(b)
(a)
(b)
. . d I
2
Fncllon rag,
R
1
= C JPAV
2
where
A= Wetted surface area
CD =Average friction drag coefficient
0
074
for Re