Download SGBAU (Sant Gadge Baba Amravati university) B-Tech/BE (Bachelor of Technology) 5th Sem Chemical Engineering Heat Transfer Previous Question Paper
10153 : Heat Transfer : 5 CH 01
P. Pages :4 ' AW - 3145
Time : Three Hours Iggy??! Max. Marks : 80
Notes : Answer three question from Section A and three question from Section B.
I.
2. Assume suitable data wherever necessary.
3. Illustrate your answer necessary with the help of neat sketches.
4. Use of slide rule logarithmic tables, Steam tables, Moller's Chart, Drawing
instrument, Thermodynamic table for moist air, Psychometric Charts and
Refrigeration charts is permitted.
SECTION - A
l. a) A pipe 100 mm ID & 8 mm thickness is carrying a steam at 170?C. The convective heat 7
transfer coem. on the inner surface of pipe is 75 W / m2?C. The pipe is insulated by two
layers of insulation. The ?rst layer of insulation is 46 mm in thickness having thermal
conductivity of 1.4 W / m?C. The second layer of insulation is also 46 mm having thermal
conductivity 0.46 W / m?C . Ambient temperature ?? 33?C thermal conductivity of steam pipe
=46W/m"C. The convective heat transfer coe?i. from the outer surface of pipe
IZW/ m2?C . Calculate the heat loss per unit length of pipe. Also determine the interface
temperature.
b) De?ne the terms :
i) Economic thickness of insulation. 2
ii) Critical thickness of insulation. ' 2
iii) Extended surfaces. 3
OR
2. a) Derive expression for temperature distribution under one dimensional steady state heat 7
conduction for composite wall.
b) A steam pipe of outer diameter 120 mm is covered with two layers of lagging inside layer 7
45 mm thick (k =0.08W/m?C) & outside layer 30 mm thick (k = 0.12W / m?C ). The pipe
conveys steam at a pressure of 20 bar with 50?C super heat. From steam table temperature
of steam t] = 262.4?C. The outside temperature of lagging is 25?C. If the steam pipe is 30
m long determine ?
i) Heat lost per hour &
ii) Interface temperature of lagging.
3. a) Draw and discuss the temperature pro?le of parallel ?ow and countercurrem ?ow heat 6
exchanger.
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b)
C)
a)
b)
a)
b)
a)
b)
Explain the following :
i) Reynold's Number
ii) Prandtl Number
iii) Grashoff Number.
De?ne the term convection.
0R
Ethylene glycol is to be heated ?om 20?C to 54?C in a tube having 50 mm ID. The tube
wall is maintained at a constant temperature of 85?C. The flow velocity through the tube is
ZVn/sec. the physical properties 01' 13.0. at average temperature = 37?C are
p :1104kg/ m3. Cp : 24(10J/kgk
p. =0.0107N? s I m3, k : 0.255 w / mk.
pw =0.0029N ? S/ m2
Calculate the length ot?heat exchanger tube.
Explain Wilson plot with signi?cance.
What is mean by ?lm condensation? Obtain an expression for following equation.
1 _ 10.25
[R'PLWL 1v Lg-A
L H-L(TV' ? IS)
va. id for laminar ?ow in condcnsation ?lm.
hav = 0.943
The effectiveness of counter 110? heat exchanger is greater than parallel ?ow heat
exchanger. Justify.
OR
A vertical plate 500 mm high 8; maintained at 30?C is exposed to saturated steam at
utzr ospheric pressure calculate ?
i) rate of heat transfer &
ii) the condensate rate per hour per meter ofthe plate width for ?lm condensation.
Data 2
p=980.3kg/ m3. k : 66.4x10_2 w / m"C
p=434x10?6 kg/ms & ?.=2257k1?kg.
Calculate the heat transfer coef?cient for ?uid ?om'ng through a tube having 40 mm ID.
at a rate of 5000 kg/hr.
Data :
p =0.004N.s / m2. p 2 l.07g lcm3
sp.heat = 2.72kJ / kg.k
k 20.256W / m.k
Use Dittus ? Boeltcr equation.
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SECTION ? B
7. a) The ?ow rates of hot & cold water stream through a parallel ?ow heat exchanger are 0.2 6
kg/s & 0.5 kg/s respectively. The inlet temperature on the hot & cold sides are 75?C & 20?C
respectively. The exit temperature of hot water is 45?C. If the individual heat transfer
coef?cients on both sides are 650W / m2?C. Calculate the area of the heat exchanger.
b) A counter ?ow heat exchanger is employed to cool 0.55 kg/s (Cp : 2.45le kg?C) of oil 8
from I 15?C to 40?C by the use of water. The inlet and outlet temperatures of cooling water
are 15?C & 75?C respectively. Take U = [450W/ m2?C. Using NTU method, calculate the
following ?
i) the mass ?ow rate of water.
ii) the effectiveness of the heat exchanger.
iii) The surface area required.
0R
8. :1) Draw and discuss the working of plate type heat exchanger with the help of diagram. 9
Mention the industrial applications of it.
b) Discuss the different types of fouling in heat exchanger. 5
9. a) 10000 kg/hr of solution containing 5% solute is to be concentrated to 25% solute. Steam is 7
available at a temperature 135? C. Feed solution enters at 35? C. BPR of the solution is
5? C. Calculate -
1) W ater evaporated per hr.
2) Steam consumption per hr.
3) Steam economy
4) Heat Transfer area.
Data :
Sp. heat of water is 4180 J/kg k.
Latest heat of condensation = 2180 kJ/kg
Latent heat of vaporization = 2253 kJ/kg
U=2907W/m2k.
b) De?ne & Explain the term. 6
i) Capacity of Evaporator. 1
ii) 3 Economy of Evaporator.
iii) True Boiling point rise.
OR
10. a) Discuss the working and industrial applications of falling ?lm evaporator with ?gure. 8
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11.
12.
b) De?ne the phenomenon boiling and explain pool boiling curve with neat diagram.
a) De?ne Radiation and give an expression for Net radiation exchange between black bodies
s:parated by non - absorbing medium.
b) Explain the terms
i) Emissivity.
ii) Total Emissive power
iii) Grey body
OR
3) Discuss the following laws ofradlation.
i) Kirchho?'s Law
ii) Planck's Law.
b) C alculatc the following for an industrial fumace in the form of a black body and emitting
radiation at 3500? C.
i) Monochromatic emissivc power at 1.2 pm length.
ii,~ Wavelength at which the emissions is maximum.
iii) Maximum Emissivc- Power.
iv) Total Emissivc Po? cr.
v) Total Emissivc Poucr if it is assumed as a real surface with emissivity equal to 0.9.
*iriniiiitiridr
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This post was last modified on 10 February 2020