Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January Food-Technology 3rd Sem 78734 Thermodynamics Previous Question Paper
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech. (Food Technology) (Sem.?3)
THERMODYNAMICS
Subject Code : BTFT-217-19
M.Code : 78734
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
1.
Define a thermodynamic system.
2.
Draw a p-T (pressure-temperature) diagram for a pure substance.
3.
Does wet steam obey laws of perfect gases ?
4.
Explain clearly the difference between a non-flow and a steady flow process.
5.
Why only in constant pressure non-flow process, the enthalpy change is equal to heat
transfer?
6.
What do you mean by `Thermodynamic temperature'?
7.
What are the characteristics of entropy?
8.
What is the difference between an ideal and a perfect gas?
9.
What is Joule-Thomson coefficient?
10. Explain the importance of Maxwell relations in thermodynamics.
SECTION-B
11. Derive the following relations :
a
g
i) u a T
ii)
h g T
T
T
p
Where a = Helmholtz function (per unit mass), and
g = Gibbs function (per unit mass).
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12. Derive the relationship between the two principal specific heats and characteristic gas
constant for a perfect gas.
13. Prove that all reversible engines operating between the same heat reservoirs have the same
efficiency.
14. Determine the entropy change of 4kg of a perfect gas whose temperature varies from 127?C
to 227?C during a constant volume process. The specific heat varies linearly with absolute
temperature and is represented by the relation :
c = (0.48 + 0.0096 T) kJ / kg K.
15. Describe the process of formation of steam and give its graphical representation also.
SECTION-C
16. 0.45 kg of carbon monoxide (28) and 1 kg of air at 15?C are contained in a vessel of
volume 0.4 m3. Calculate the partial pressure of each constituent and the total pressure in
the vessel. The gravimetric analysis of air is to be taken as 23.3% oxygen (32) and 76.7%
nitrogen (28).
17. a) Prove that the rate of change of hat interchange per unit change of volume when gas is
n
pd
compressed or expanded is given by
1
J
b) For isothermal flow and non-flow steady processes, prove that
2
2
pd
.
dp
1
1
Also state the assumptions made.
18. Write short notes on the following :
i) Perpetual motion machine of second kind.
ii) Claperyon equation and its applications.
iii) Helmholtz and Gibbs function.
iv) Measurement of dryness fraction.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 26 June 2021