Total no. of Pages 01
VISEM
Roll no....
MECHANICAL ENGINEERING
ME-311:
(B.Tech.)
Heat and Mass Transfer
(July-2021)
TIME:3 hrs.
Max. Marks: 70
Attempt any five Questions
O1 Derive the expression of rate of heat transfer and temperature distribution in () Hollow
Cylinder (i)sphere with constant heat generation
(14)
Q-2 Explain the reasons that overall heat transfer coefficient is different in composite cylinder
and composite sphere . Aiso Derive the expression for overall heat transfer coefficient in three
layered(i) composite hollow cylinder and (ii) three layered composite sphere.
(1+6+7)
Q-3Define critical thickness of insulation. Explain the utility. Derive the expression for critical
thickness of Insulation for(i) Sphere (i)cylinder
(2+12)
Q4(a) Derive the expression for energy stored, Rate of heat transfer and temperature distribution
(6)
using Lumped capacity method
(b) Define intensity of radiation and also derive the expression for radiation exchange between
(8)
two surfaces and prove the reciprocal theorem
Q-5 Define the terms with physical significance of fin efficiency and fin effectiveness . also
Derive the expression for temperature distribution and rate of heat transfer for fin when (i) fin is
too
long
(ii)
fin
is
well
insulated
(ii)
fin
is
open
to
surroundings.
Q6 (a)Define the terms with physical significance:
(i)
(iv)
(2+12)
Sherwood number, (ii) Schmidt Number, (iii) Mass Stanton Number
Nusselt Number (v)
Biot Number (vi) Fourier Number
Number
(vii) Geometric Number (viii) Prandtl Number (ix)Stanton
(10)
(x) Thermal diffusivity
dimensional
(b) What are the methods for fining convective heat transfer coefficient. Using
number in
analysis , prove that Nusselt number isa function of Reynold number and Prandtl
Groshief number andPrandl
forced convection mode or Nusselt number is afunction of
(4)
number innatural convection mnode
heat
0-7(a) Define beat exchangers. How can you classified. How you can compute overall
transfer coefficient
(2)
exchanger in paralle] fo
(b) Derive the expression for LMTD and effectiveness of heat
counter flow arrangement
(4+8)
determin
lavyer of insulation (K=0.2 WImk).
thick
cm
5
with
covered
is
it
pipe
() 10reduce heat loss from the
(4)e
the rate of heat transfer per unit length of pipe.
Water enters the centre tube at 16(0C)
exchanger.
heat
tvpe
flow
parallel
tube
2D.0l 1s being cooled by water in a
from 130(0C) to60 (0C).
and is heated to S0(oC). The oil floy in annulus and cooled
exchanger was swatted to counter Ilow operation (ii
heat
existing
ifthe
fuid.
each
of
temperature
Find () The exit
rlowoperatio
cooled by increasing the tube length with(2) parallel
be
may
oil
which
to
temperature
minimum
Ihe
effectiveness in (a) Parallel îow operation (b) Count
possible
maximum
The
(ii)
operation.
and (b)Counter flow
cold fuid also.
flow operation. Also find outlet the temperature of hot fluid and
surface and verify reciprocal theorem
two
between
exchange
heat
of
rate
for
Q6(a) Derive the expression
located at a distanc
A,
disc
parallel
large
and
dA,
disc
small
very
a
(b)Detemine the geometric shape factor for
(4+4
plane)
horizontal
in
placed
are
.(Both
one
smaller
L directlyabove the
water at 20 (oC) is passed through thetu
and
(oC)
100
at
maintained
is
diameter
inner
Q-7(a)A tube of30 mm
density of water at temperature of 40(oC) as: Densi
Assume:
(oC).
60
to
heated
and
(m/sec)
of0.5
with a velocity.
(Kg/m3)=1000, Specific Heat(J/Kg/K)-4200, Thernal
conductivity (W/mK)=0.63,
to the water, convective heat trans
transferred
heat
of
amount
the
Find
Viscosity (Kg/m-sec)=0.00065.
coefficient and length of the tube.
of boiling
(b) Discuss the resume
Total no. of pages: 02
Roll No...
SIXTH SEMESTER
B. Tech. [ME]
END SEMESTER EXAMINATION
May- 2019
ME-311 Heat and Mass Tranfer (Transport Phenomena)
Max. Marks: 7O
Time: 3:00 Hours
aitable
Note: Attempt Any Five Questions. Assume
suitable data iif any.
any.
Q1(a )Derive the expression of rate of heat transfer and temperature distribution
(4)
in cylinder with constant heat generation.
(b) Derive the expression for energy stored, Rate of heat transfer and temperature
(4)
distribution using Lumped capacity method
(c) 3000 kg of water is heated per hour from 30°C to 70°C by pumping it through
a certain heated section of a 25 mm diameter tube. If the surface of the heated
section is maintained at 110°C. Estimate length of heated section and the rate of
heat transfer from tube to water.The thermo-physical properties of watèr are:
Density (kg/m)=971.6 , Dynamic viscosity =0.000335
(W/mK)
kg/m-sec. K=0.667
(6)
Q2 ( a) Define the terms with physical significance:
(i)
Sherwood number,(ii) Schmid Number (iii) Nusselt Number (iv) Prandtl
Number (v) Stanton Number(vi) Number of transfer units.
(6)
(b) Using dimensional analysis, prove that Nusselt number is a function of
Grashofnumber & PrandtlNumber in a natural convection Mode.
(8)
Q-3(a) Define fin efficiency and fin effectiveness. Also derive the expression for
temperature distribution and rate of heat Transfer for (i) fin of well insulated and
(ii) fin is open to surroundings.
(14)
04 Explain the reasons that overall heat transfer coefficient is different in
composite cylinder.
Also derive the expression for overall heat transfer coefficient in three layered
()composite hollow cylinder (ii) composite hollow sphere and (ii) three layered
composite slab.
(14)
PT.0.
b] Derive the functional relationship using the Buckinghum t theorem
and prove that the Nusselt number is a function of (i) Reynold number
and Prandtl number in a force convection mode and (i) Grashoff
Total No. of Pages
Number and Prandtl number in a free convection mode.
a] Explain the various regimes in boiling heat transfer.
transfer in a constant heat generation problems in a (i) hollow cylinder
(ii) hollow sphere.
5+5
B.E (PTJ
ENDSEMESTER EXAMINATION
6+6
4
b] Derive the expression for temperature distribution and rate of heat
Roll No.
FOURTH SEMESTER
MAY-2012
PT-215 HEAT TRANSFER
Time: 3:00 Hours
Note :
Answer
Max. Marks : 70
any five questions.
Assume suitable missing data, if any.
1fa] Derive the expression for rate of heat transfer and temperature
distribution in (i) in the hollow sphere and (ii) hollow cylinder.
6+6
[b] Why analogy is used in heat exchanger explain its importance.
2[a] Derive the expression for critical thickness of insulation for (i) hollow
sphere and (ii) hollow cylinder.
6+6
[b] Why overall heat transfer coefficient in a composite hollow cylinder &
in a composite hollow cylinder differ. Explain the reasons.
2
3[a] Derive the expression for temperature distribution and rate of heat
transfer in a fins when, fin is well insulated.
6
b] Derive the expression for energy stored, temperature distribution and
rate of heat transfer in unsteady state heat conduction using lumped
parameter method.
4
Define the following terms with physical significance (i) LMTD (1)
Heat exchanger effectiveness/ efficiency, (ii) NTU (IV) Thermal
diffusivity (v) Biot Number (vi) Nusselt number (vi) Stanton Number.
14
S[a] Derive the expression for overall heat transfer coefficient in (i)
composite three layered hollow cylinder (ii) composite three layered
hollow sphere.
6+6
relation between them.
2
[b] Define intensity of radiation and emissive power and explain the
6[a] What are the methods for finding the convector heat transfer
coefficient?
2
OLD
Total no. Ofpages :1
SIXRTH SEMESTER
Roll No.
B.Tech.
(Branch -Mechanical-)
END SEMESTER EXAMINATION MAY2018 (Old scheme)
ME 311
HEAT AND MASS TRANSFER
Time :3 hr
Max Marks: 70:
Answer any FIVEquestions. Assume missing data suitably if any.
Derive the expression for critical thickness of insulation for (i)
1.(a)
cylinder and (ii) sphere.
Consider radiative heat transfer between two large parallel planes of
(b)
surface emissivities of 0.8. How many radiation shields of emissivity of
exchange
0.05 are placed between the surfaces to reduce the radiation heat
(7,7)
by a factor of 75?
S(a)
Explain the dimensional analysis applied to free convection heat
transfer.
(b)
Explain the Reynolds analogy and Colburn analogy.
(7,7)
surface of brick is at 900 K and the steel is surrounded by air at 300 K with
heat transfer coefficient of 5 W/m2/K. Determine the heat flux through the
(7,7)
wall and outside surface temperature of steel.
6(a) Define effectiveness of heat exchanger and derive the expression for
effectiveness of parallel flow heat exchanger.
A counterflow heat exçhanger is to be designed to cool 3600 kg/hr
(b)
of oil (C, = 2 kJkg/K)from 150° Cto 80° Cwith l800 kg/hr of water (C, =
4.18 kJkg/K) available at 25° C. Determine the heat exchanger surface
area. Take U=500 W/m2/K.
(7,7)
cylindrical wall and also develop the expression for overall heat transfer
2(a) Derive the expression for heat flow rate for a three layered composite
7
Explain the following:
coefficient for the composite cylindrical walls.
(a)
(b)
(c)
Dimensionless parameters in convective mass transfer
(b)
A furnace wall comprises of two layers of fire clay 80mm thick
(k=1.2 W/m/K) and mild steel of 6 mm thick (k-35 W/mK). The inside
(b)
Saturated steam at i15° C flows inside a copper pipe (k=450
W/m/K) having ID of l0 cm and OD of 12 cm. The heat transfer coefficient
pipe is
on the steam side is 12 kW/m/K and that on the outside surface of
space
a
at
located
is
it
if
pipe
the
from
loss
heat
the
Determine
18 W/m/K.
with
lagged
is
pipe
the
if
affected
be
would
loss
heat
this
How
at 30° C.
(7,7)
insulating material (k-0.22 W/m/K) having thickness of 5 cm.
distribution and heat
3.(a) Derive the expression for temperature
dissipation from an infinitelylong fin.
(b)
expression for
What is transient heat conduction ? Derive the
4.(a)
State andexplain various laws relating to thermal radiation.
capacity
temperature distribution and rate of heat transfer in lumped heat
(7,7)
system.
Significance of Biot number and Fourier number
Boiling heat transfer
(4,5,5)
Q-5: Derive the expression for critical thickness of insulation for
()
Sphere (i) cylinder
Assume inner convection and outer convection also
P.TO,
(4+4)
Q6.(a)Explain the boiling resume with various sub divisions in detail
(2)
alsn
and
surfaces
two
between
(b) Derive the expression for radiation exchange
(3)
prove reciprocal theorem.
r
radius
(c) Derive the expression for the radiation shape factor between a disc of
3)
located at a distance ffrom the centre of small sphere.
in
Q7. Derive the expression for LMTD and effectiveness of heat exchanger
(3+5)
counter flow heat exchanger
Total no. of pages: 02
SIXTH SEMESTER
Roll No..
B. Tech. [ME]
END SEMESTER EXAMINATION
May- 2019
ME302 Heat and Mass Tranfer
Time: 3:00 Hours
Max. Marks: 40
Note: Attempt Any Five Questions. Assume suitable data if any.
Q1.(a )Derive the expression of rate of heat transfer and temperature distribution
in sphere with constant heat generation.
(2)
(6) Derive the expression for energy stored, Rate of heat transfer and temperature
distribution using Lumped capacity method.
(2)
(c) A 12 mm diameter mild steel sphere of thermal conducti vity=42.sW/mK is
exposed to cooling air flow at 27°C resulting in the convective coefficient (h)=114
(W/m²K).
Determine (1) time required to cool the sphere from 540°Cto 95°C.
() Instantaneous heat transfer rate of 2 minutes after the start of cooling and
(i)Total energy transferred from the sphere during the first 2 minutes. The
relevant properties of mild steel are; Density (kg/m'), specific heat (Cp)= 475
(JkgK) and thermal diffusivity=-0.043 (m/hr).
(4)
Q2. (a)Define the terms with physical significance:
(i)
Sherwood number, (ii) Schmidt Number, (iii) Mass Stanton Number (iv)
Reynold Number (v) Grashof. Number (vi) Nusselt Number (vii) Prandtl
Number (viii) N.T.U.
(4)
(b) Using dimensional analysis, prove that Nusselt number is a function of
Reynold number & Pràndtl Number in forcëd convection Mode.
(4)
03. Derive the expression for tempe¿ratüre distribution and rate of heat
Transfer
for () fin of well insulated and (ii) fin is exposed to
and
surroundings
(iii) fin
is too long.
(2+3+3)
Ö4 Explain the reasons that overall heat
transfer
is different in
composite sphere. Also derive the expression for overallcoefficient
heat transfer coefficient
in three layered.
(1) composite hollow cylinder and (ii)
three layered composite sphere (iii)
Composite Slab
(1+5+2)
Total no. Ofpages : 2
SIXTH SEMESTER
Roll No.
END SEMESTER EXAMINATION
ME -302
B.Tech. (Branch -Mech)
MAY 2018
HEAT AND MASS TRANSFER
Time: 3 hrs
Max Marks: 40
Answer any five questions, Assume
missing data suitably if any.
Q-1(a)
What are the methods for
finding convective heat transfer
coefficient. Using dimensional analysis , prove
that Nusselts number is a a
function of Reynold number and Prandtt
Number in the forced convection mode. (5)
(b) Derive the expression for
temperature distribution and rate of heat transfer, and heat
parameter capacity method.
energy stored using
lumped
(3)
Q2 Derive the
expression for critical thickness of insulation for
(i)sphere and (ii) cylinder. State the
optimality. Assume inner and outer convection also.
condition for
(b) A Rectangular duct of size
(2+2)
(400mm X 30Omm) carries air at 25 (oC) to the
room. The velocity of air is
600m/min. find the inside heat transfer
coefficient, if the heat transfer coefficient on the outer
is 20 (W/m2K) and
surface of the duct
of
temperature the
metre length of the duct. Neglect the atmosphere surrounding the duct is 10 (oC). Find the heat lost by the
air per
resistance of the duct wall. The properties of air
at 25 (oC) are :
(Kg/m3)=1.02, Specific Heat(J/Kg/K)=1000, Themal
conductivity (W/mK)-0.0256, Viscosity Density
sec)=0.0000182
(Kg/m
O3(a). Why fins are used. Define Fin
efiiciency and Fin Bfectiveness . Derive the
transfer when fin is not
insulated.
(b)Define following terms with physical
significance:
Thermal Difusivity, Biot Number, Fourier
expression for rate of heat
(4)
Number, Geometric Number,
(7)
J(4): An Al pipe carries steam at
110 (oC) the pipehas
f10cm andan outer
conductivity of 185 W/nmK has an inner diameter
diameter of l.2 Cm. lhe pipe 1S thermal
in
a room when the
located
OC) andconvective heat
ambient air
transfer coefficient is 1500
is 30
(W/m2K). determine the rate of heat transfertenmperature
fpipe.
per unit length
(4)
Number Grashof Number
Reynold
of
significance
O-5(a) Discuss the physical
each 15 cm outer diameter and 1.5 cmfins,
10
of
consists
cylinder
Amotor cycle Calculate the rate of heat dissipation from the cylinder fins when
inside diameter.
running. Assume atmospherio.
iS
cycle
motor
())
and
stationary
(i) motor cycle is
°C. The thermo-physical
480
is
temperature
fin
average
air is at 20°C and the
are: K=0.427 (W/mK), Prand
°C
250
of
temperature
average
properties at the
)=0.674 , kinemati
Number-0.677, Specific heat=1038 (J/kgK), Density(kg/m
(10
viscosity (m²/sec)= 40.61*106.
various sub
(b) Explain the boiling resume with
divisions in detail
0-6: Why critical insulation is used. Derive the
expression for critical thickness o
(4)
insulation for :
cylinder
() Sphere (ii)
outer convection also.
Assume Inner and
(1+7+
heat exchanger
Q7. (a) Derive the expression for LMTD and effectiveness of
(4+4
counter flow heat exchanger.
surfaces and al
(b) Derive the expression for radiate exchange between two
(6
prove reciprocal theorem.
******