Course Code: 18ME0320 R18

SIDDHARTH INSTITUTE OF ENGINEERING & TECHNOLOGY:

PUTTUR (AUTONOMOUS)
Siddharth Nagar, Narayanavanam Road – 517583

QUESTION BANK (DESCRIPTIVE)

Subject with Code: Heat& Mass Transfer Course & Branch: B. Tech - ME
(18ME0320)
Regulation: R18
Year &Sem: III-B.Tech& I-Sem

UNIT –I
BASIC CONCEPTS

1 a What is Heat Transfer [L1][CO1] [2M]

b How is Heat Transferred [L1][CO1] [2M]
c What is Conduction? [L1][CO1] [2M]
d What is Convection Equation [L1][CO1] [2M]
e What is Fourier's law [L1][CO1] [2M]
2 a) List the basic laws which govern the heat transfer [L1][CO1] [5M]
b) Name and explain the mechanism of heat transfer [L1][CO1] [5M]
3 a) What is Fourier’s law of conduction? State the assumption and essential feature of [L1][CO1] [5M]
it
b) Define the following terms. [L1][CO1] [5M]
i).Thermal Conductivity ii).Thermal Resistance
4 a) Distinguish between conduction, convection and radiation modes of heat transfer [L3][CO1] [5M]
b) Calculate the rate of heat transfer per unit area through a copper plate 45 mm [L4][CO1] [5M]
thick, whose one face is maintained at 350 0C and the other face at 50 0C. Take
thermal conductivity of copper as 370 W/m 0C.
5 a) What is conduction heat transfer? Explain its parameters [L1][CO1] [5M]
b) A plane wall is 150 mm thick and its wall area is 4.5 m2. If its conductivity is 9.35 [L4][CO1] [5M]
W/m 0C and surface temperature are steady at 150 0C and 45 0C, determine i).Heat
transfer across the plane wall, ii).Temperature gradient in the flow direction
6 a) What is convection heat transfer? Explain its parameters [L1][CO1] [5M]
b) A wire 1.5 mm diameter and 150 mm long is submerged in water at atmospheric [L4][CO1] [5M]
pressure. An electric current passed through the wire and is increased until the
water boils at 100 0C. Under the condition, if convective heat transfer coefficient is
4500W/m20C. Find how electric power must be supplied to the wire to maintain
the wire surface at 120 0C
7 a) Write the laws of radiation? Explain its parameters [L1][CO1] [5M]
b) A surface having an area of 1.5 m2 and maintained at 300 0C exchanges heat by [L4][CO1] [5M]
radiation with another surface at 40 0C. The value factor due to the geometric
location and emissivity is 0.52. Determine
i).Heat loss by radiation ii).The value of thermal
resistance
iii).The value of equivalent convection coefficient
8 Derive the general heat conduction equation in Cartesian coordinate [L3][CO1] [10M]
9 Derive the general heat conduction equation in Cylindrical coordinate [L3][CO1] [10M]
10 Derive the general heat conduction equation in Spherical coordinate [L3][CO1] [10M]
Course Code: 18ME0320 R18
UNIT –II
ONE DIMENSIONAL STEADY STATE HEAT CONDUCTION, EXTENDED SURFACES
&TRANSIENT HEAT CONDUCTION
1 a Define overall heat transfer co-efficient [L1][CO2] [2M]
b What is critical radius of insulation [L][CO2] [2M]
c Define Fin efficiency [L][CO2] [2M]
d Define Fin effectiveness [L][CO2] [2M]
e What is lumped heat analysis [L][CO2] [2M]
2 a) Derive an expression for heat conduction through a composite wall [L3][CO2] [5M]
b) A reactor’s wall, 320 mm thick, is made up of an inner layer of fire brick (k = [L4][CO2] [5M]
0.84W/m 0C) covered with a layer of insulation (k = 0.16 W/m 0C). The reactor
operates at a temperature of 1325 0C and the ambient temperature is 25 0C.
Determine the thickness of fire brick and insulation which gives minimum heat
loss.
3 A steam pipe of outside diameter 80 mm and 25 m long conveys 800 kg of steam per [L4][CO2] [10M]
hour at a pressure of 22 bar. The steam enters the pipe with a dryness fraction of 0.99
and is to leave the other end of the pipe with the minimum dryness fraction of 0.97.
This is to be accomplished by using a lagging material (k = 0.2 W/m 0C), determine its
minimum thickness to meet the necessary condition, if the temperature of the outside
surface of lagging is 25 0C. Assume that there is no pressure drop across the pipe and
the resistance of the pipe material is negligible.
4 a) Obtain the expression of heat conduction through hollow cylinder [L3][CO2] [5M]
b) A spherical shaped vessel of 1.4 m diameter is 90 mm thick. Find the rate of heat [L4][CO2] [5M]
leakage, if the temperature difference between the inner and outer surface is 220 0C.
Thermal conductivity of the material of the sphere is 0.083 W/m 0C.
5 a) Derive the expression for the overall heat transfer coefficient for a composite wall. [L3][CO2] [4M]
b) A cold storage room has walls made up of 220 mm of brick on outside 90 mm of [L4][CO2] [6M]
plastic foam and finally 16 mm of wood on the inside. The outside and inside air
temperatures are 25 0C and -3 0C respectively. If the inside and outside and heat
transfer coefficients are 30 and 11 W/m2 0C respectively the thermal conductivity
of brick, plastic foam and wood are 0.99, 0.02 and 0.17 W/m 0C respectively. Then
determine
i. The rate of heat removal by the refrigeration, if the total wall area is 85 m2
c) ii. The temperature of the inside surface of the brick
6 a) Derive an expression for heat conduction through a plane wall [L1][CO2] [5M]
b) Calculate the critical radius of insulation for asbestos (k = 0.172 W/m K) [L4][CO2] [5M]
surrounding a pipe and exposed to room air at 300 K with h = 2.8 W/m K.
Calculate the heat loss from a 475 K, 60 mm diameter pipe when covered with the
critical radius of insulation and without insulation.
7 a) What is lumped system analysis? Derive the expression for it [L2][CO2] [4M]
b) A 50 cm x 50 cm copper slab 6.25 mm thick has a uniform temperature of 300 0C. [L4][CO2] [6M]
Its temperature is suddenly lowered to 36 0C. Calculate the time required for the
plate to reach the temperature of 108 . Take ρ = 9000 kg/m3, c = 0.38 kJ/kg 0C, k =
370 W/m 0C and h = 90 W/m20C.
8 a) Write short note on transient heat conduction [L1][CO2] [4M]
0
b) A steel ingot (large in size) heated uniformly to 745 C is hardened by quenching it [L4][CO2] [6M]
in an oil bath maintained at 20 0C. Determine the length of time required for the
temperature to reach 595 0C at a depth of 12 mm. The ingot may be approximated
as a flat plate. For steel ingot take α(thermal diffusivity) = 1.2x10-5 m2/s.
9 a) Sketch various types of fins. Give examples of use of fins in various engineering [L3][CO2] [5M]
applications
b) Calculate the amount of energy required to solder together two very long pieces of [L4][CO2] [5M]
bare copper wire 1.5 mm diameter with solder that melts at 190 0C. The wires are
positioned vertically in air at 20 0C. Assume that the heat transfer coefficient on the
Course Code: 18ME0320 R18
wire surface is 20 W/m20C and thermal conductivity of wire alloy is 330 W/m 0C
10 a) Explain the fin effectiveness and fin efficiency [L2][CO2] [5M]
0
b) A longitudinal copper fin (k = 380 W/m C) 600 mm long and 5 mm diameter is [L4][CO2] [5M]
exposed to air stream at 20 0C. The convective heat transfer coefficient is 20 W/
m20C. If the fin base temperature is 150 0C, determine
i. The heat transferred, and
ii. The efficiency of the fin

UNIT –III
FREE CONVECTION & FORCED CONVECTION
1 a Define convection. [L1][CO3] [2M]
b What is meant by free or natural convection [L1][CO3] [2M]
c What is forced convection? [L1][CO3] [2M]
d What are the dimensionless parameters used in forced convection [L1][CO3] [2M]
e What is meant by laminar flow and turbulent flow? [L1][CO3] [2M]
2 a) What is convective heat transfer? Distinguish between free and forced convection [L1][CO3] [5M]
b) Derive the expression for Reynolds number and how flows are determined by [L3][CO3] [5M]
Reynolds number?
3 Air at 20 0C and at a pressure of 1 bar is flowing over a flat plate at a velocity of 3 [L4][CO3] [10M]
m/s. If the plate is 280 mm wide and at 56 0C. Calculate the following quantities at x =
280 mm, given that properties of air at the bulk mean temperature 0C are ρ = 1.1374
kg/m3, k = 0.02732 W/m 0C, cp = 1.005 kJ/kg K, υ = 16.76x10-6 m2/s, Pr = 0.7
i. Boundary layer thickness ii. Local friction coefficient
iii. Average friction coefficient iv. Thickness of the boundary layer
v. Local convective heat transfer vi. Average convective heat transfer
vii. Rate of heat transfer by convection viii. Rate of convective heat transfer
4 a) What is the physical significance of the Nusselt number? How is it defined [L1][CO3] [4M]
b) Assuming that a man can be represented by a cylinder 350 mm in diameter and [L4][CO3] [6M]
1.65 m high with a surface temperature of 28 0C. Calculate the heat he would lose
while standing in a 30 km/h wind at 12 0C.
5 a) Define Nusselt number, Prandtl number and their significance [L1][CO3] [4M]
b) Air stream at 24 0C is flowing at 0.4 m/s across a 100 W bulb at 130 0C. If the bulb [L4][CO3] [6M]
is approximately by a 65 mm diameter sphere. Calculate
i. The heat transfer rate,
ii. The percentage of power lost due to convection
6 In a straight tube of 60 mm diameter, water is flowing at a velocity of 12 m/s. The [L4][CO3] [10M]
tube surface temperature is maintained at 70 0C and the following water is heated from
the inlet temperature 15 0C to an outlet temperature of 45 0C. taking the physical
properties of water at its mean bulk temperature, Calculate the following:
i. The heat transfer coefficient from the tube surface to the water
ii. The heat transferred iii. The length of the tube
7 a) Mention the empirical correlation of free convection [L3][CO3] [4M]
b) A vertical cylinder 1.5m high and 180mm in diameter is maintained at 100 0C in an [L4][CO3] [6M]
atmosphere environment of 20 0C. Calculate heat loss by free convection from the
surface of the cylinder. Assume properties of air at mean temperature as ρ = 1.06
kg/m3,ν = 18.97 x 10-6 m2/s, cp = 1.004 kJ/kg0C and k = 0.1042kJ/mh0C
8 a) Differentiate between laminar and Turbulent flow. [L3][CO3] [4M]
b) A horizontal plate measuring 1.5 m x 1.1 m and at 215 0C, taking upward is placed [L4][CO3] [6M]
in still air at 25 0C. Calculate the heat loss by natural convection. The convective
film coefficient for free convection is given by the following empirical relation h =
3.05(Tf)1/4 W/m2 0C. where Tf is the mean film temperature in degree Kelvin
9 A cylinder body of 300 mm diameter and 1.6 m height is maintained at a constant [L4][CO3] [10M]
temperature of 36.5 0C. The surrounding temperature is 13.5 0C. Find out the amount
Course Code: 18ME0320 R18
of heat to be generated by the body per hour if ρ = 1.025 kg/m3,ν = 15.06 x 10-6 m2/s,
cp = 0.96 kJ/kg0C and k = 0.0892 kJ/mh0C and β=1/298 K-1. Assume
Nu=0.12(Gr.Pr)1/3.
10 Calculate the heat transfer from a 60 W in candescent bulb at 115 0C to ambient air at [L4][CO3] [10M]
25 0C. Assuming the bulb as a sphere of 50 mm diameter. Also, find the percentage of
power lost by free convection. The correlation is given by: Nu = 0.60 (Gr.Pr)1/4

UNIT –IV
PHASE CHANGE HEAT TRANSFER AND HEAT EXCHANGERS
1 a What are limitations of LMTD method [L1][CO4] [2M]
b Define LMTD of a heat exchanger [L1][CO4] [2M]
c Describe plate heat exchangers. [L2][CO4] [2M]
d Define Boiling and Condensation. [L1][CO4] [2M]
e Which of the arrangement of heat exchangers (HEX) is better, (i) parallel flow,(ii) [L2][CO4] [2M]
Counter flow. Explain the reasons
2 Explain briefly the various regimes of saturated pool boiling with diagram [L3][CO4] [10M]
3 a) Mention correlation in boiling with proper expression [L3][CO4] [5M]
b) Discuss the different types of processes for condensation of vapours on a solid [L3][CO4] [5M]
surface
4 Saturated steam at tsat = 90 0C (P= 70.14 kPa) condenses on the outer surface of a 1.5 [L4][CO4] [10M]
m long 2.5 m OD vertical tube maintained at a uniform temperature t∞ = 70 0C.
Assuming film condensation. Calculate
i). The local transfer coefficient at the bottom of the tube, and
ii). The average heat transfer coefficient over the entire length of the tube.
Properties of water of 80 0C, ρl = 974 kg/m3, kt = 0.668 W/mK, μl = 0.335x103 kg/m3,
hfg = 2309 kJ/kg, ρv<<ρl
5 a) What are the applications of boiling and condensation process? [L1][CO4] [4M]
b) A vertical tube of 60 mm outside diameter and 1.2 m long is exposed to steam at [L4][CO4] [6M]
atmospheric pressure. The outer surface of the tube is maintained at a temperature
of 50 0C by circulated cold water through the tube. Calculate the following
i). The rate of heat transfer to the coolant, and
ii). The rate of condensation of steam
6 a) Differentiate between the mechanism of film wise and drop wise condensation [L3][CO4] [5M]
b) How are heat exchangers classified based on direction of fluid motion. explain [L2][CO4] [5M]
with neat diagram
7 Derive the expression for Logarithmic Mean Temperature Difference (LMTD) in case [L3][CO4] [10M]
of parallel flow
8 Derive the expression for Logarithmic Mean Temperature Difference (LMTD) in case [L3][CO4] [10M]
of counter flow
9 The flow rate of hot and cold water streams running through a parallel flow heat [L4][CO4] [10M]
exchanger are 0.2 kg/s and 0.5 kg/s respectively. The inlet temperatures on the hot and
cold sides are 75 0C and 20 0C respectively. The exit temperature of hot water is 45
0
C. If the individual heat transfer coefficients on the both sides are 650 W/m2 0C,
calculate the area of heat exchanger.
10 a) Distinguish between Boiling and Condensation [L3][CO4] [4M]
b) In a certain double pipe heat exchanger hot water flow at a rate of 5000 kg/h and [L4][CO4] [6M]
gas cooled from 95 0C to 65 0C. At the same time 50000 kg/h of cooling water at
30 0C enters the heat exchanger. The flow conditions are that L4overall heat
transfer coefficient remains constant at 2270 W/m2 K. Determine the heat transfer
area required and the effectiveness, assuming two streams are in parallel flow.
Assume for the both the streams cp = 4.2 kJ/kg K
Course Code: 18ME0320 R18

UNIT –V
RADIATION AND MASS TRANSFER
1 a What is Block body? [L1][CO5] [2M]
b Define Mass transfer. [L1][CO6] [2M]
c State Stefan Boltzmann Law [L1][CO5] [2M]
d State Kirchhoff‟s Law [L1][CO5] [2M]
e Define Radiation? [L1][CO5] [2M]
2 a) What is black body ? How is differ from a gray body ? [L1][CO5] [6M]
b) Explain Stefan Boltzmann Law,Kirchhoff‟s Law [L1][CO5] [4M]
3 The effective temperature of the body having an area of 0.12 m2 is 527 oC. Calculate the [L4][CO5] [10M]
following
i) The total rate of energy emission
ii) The wave length of maximum monochromatic emissive power
4 a) Define the term absorptivity, reflectivity and transmittivity of radiation [L1][CO5] [4M]
b) ExplainPlank‟s Law, WiensDisplacement Law. [L2][CO5] [6M]
5 Explain the surface emissive properties [L2][CO5] [10M]
6 a) Explain the concept of black body [L1][CO5] [4M]
b) Assuming the sun to be a black body emitting radiation with maximum intensity [L4][CO5] [6M]
at λ = 0.49 µm, calculate the following
i. The surface temperature of the sun
ii. The heat flux at surface of the sun
7 Calculate the following for an industrial furnace in the form of black body and [L4][CO5] [10M]
emitting radiation at 2500 0C.
i. Monochromatic emissive power at 1.2 µm length
ii. Wave length at which the emission is maximum
iii. Maximum emissive power
iv. Total emissive power
v. Total emissive power of the furnace if the assumed as a real surface with
emissivity equal to 0.9.

8 a) Explain the modes of Mass transfer [L2][CO6] [6M]

b) What is Mass transfer coefficient? [L2][CO6] [4M]
9 Define Fick’s law. Explain briefly. [L1][CO6] [10M]
10 a) Explain correlation for mass transfer [L2][CO6] [6M]
b) List out the application of Mass Transfer [L1][CO6] [4M]

Preparedby:
1. P.VENKATARAMANA
AssociateProfessor/ME
2. K.SUDHAKAR
Associate Professor/ME
3. B.A.DEVAN
Assistant Professor/ME