F G192179 Pages:2

Reg No.:_ Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SEVENTH SEMESTER B.TECH DEGREE EXAMINATION(R&S), DECEMBER 2019

Course Code: ME467
Course Name: Cryogenic Engineering

Max. Marks: 100 Duration: 3 Hours
PARTA
Answer any three full questions, each carries 10 marks. Marks
1 ஐ List four major historical developments in cryogenics since 1877. (2)

b) Determine the thermal conductivity of air at 250 K and 101.3 kPa if the mean (5)
free path of air at this condition is 49 nm, the gas constant for air is 287 J/kg K,

the specific heat ratio is 1.4 and the specific heat at constant volume is 716.5

J/kg K.
c) Discuss any three applications of cryogenics in space technology. (3)
2 9) Explain 1) Meissner effect ii) Fountain effect (4)

b) Explain the terms i) Transition temperature and 1) Critical current of (3)
superconductors.
c) Sketch and explain the variation of specific heat of liquid helium 4 at near (3)
absolute zero temperature.
3 Explain the Joule Thomson effect. Show the inversion curve of areal gas ona_ (10)
T-p diagram. Prove that an ideal gas will not experience a temperature change
upon isenthalpic expansion.
4 a) Prove that COP of an ideal Stirling cycle cryocooler is the same as that of 8 (5)
Carnot cycle.
b) With the help of a neat sketch, explain the magnetic cooling process. (5)
PART B
Answer any three full questions, each carries 10 marks.
5 9) With a neat schematic and T-s diagram, explain the working of a liquefaction (8)
system used for neon.
b) Explain why the simple Linde-Hampson system does not work for gases 8000 85 (2)
neon, hydrogen and helium.
6 With a neat sketch and T-s diagram explain the working of Simon helium (10)

liquefaction system.

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