Sr.

No.

Expt.

No.

Title Revision

No.

No. Of

Pages

01. - Table of Content - 01

02. - Revision Record Sheet - 01

03. - Controlled copy holders - 01

04. - General Instructions - 01

05. - List of Experiments -

01. To Study properties of Cryogenic fluids and its effects on materials

02. To compute the thermal conductivity at very low temperature

03. To compare different insulating materials

used in cryogenics applications

04. To compare different insulating materials

used in cryogenic applications based on Heat transferred through the insulation

05. To Study cryogenic storage vessels

06. To study various applications of cryogenic systems

07. To Study cryo-refrigeration system:

isothermal source system, isobaric source system

08. To Study working of magnetic refrigerator and thermal valves

09. To Study liquefaction system - ideal

liquefaction system, simple linde hampson, pre-cooled linde hampson and

dual pressure lnde hampson liquefaction system

10. Industrial Visit Report of SICART (Nitrogen Liquefier Plant)

11. Industrial Visit Report of INOX

06. _ Annexture-I: List of Equipments _ 01

Experiment No:1

Aim: To Study properties of Cryogenic fluids and its effects on

materials

Question

Q.1 Discuss the properties of Helium as cryogenic fluid?

Q.2 Explain following phenomenon for He II

1. Fountain effect 2.Roll-in-film 3.Second sound

Q.3 what is superconductivity? Explain meissner effect with neat sketch. Discuss

effects of superconductivity on properties of materials?

Q.4 Explain the variation in specific heat of Helium with cryogenic temperature

range and Lambda Point.

Q.5 Discuss the properties of hydrogen at low temperature.

Q.6 Explain the concept of ortho-hydrogen and para-hydrogen. Also Explain

difference between ortho-hydrogen and para-hydrogen.

Q.7 Explain the effect of temperature in cryogenic range of 0 to 250 K on Ultimate

and Yield strength of following materials. (i) S.S. 304 (ii) Carbon steel and (iii)

Teflon

Q.8 Define thermal conductivity of materials. Explain the effect of low

temperature on thermal conductivity of following materials. (i) Pure Copper (ii)

Titanium (iii) SS-304 (iv) Beryllium Copper

Experiment No:2

Aim: To compute the thermal conductivity at very low temperature

Question

1. kdT Integral Method

(1) Determine the heat transferred in a copper slab of uniform cross section

area of 1 cm2 and length of 0.1 m, when the end faces are maintained at

300 K and 80 K respectively. Compare the heat transferred by Kavg and kdT

methods.

Given values are

15000)(

300

2.4

1 dtTk ,

1600)(

80

2.4

2 dtTk ,

k300 = 78.5 W/mk and

k80 = 37.0 W/mK.

2 Determine the heat transferred in an Aluminum slab of uniform cross

sectional area 10 cm2 and length of 0.5 m, when the end faces are

maintained at 250 K and 80 K. Given Values are 51300)(

250

0

1 dtTk

and 16700)(

80

0

2 dtTk .

2. Apparent Thermal Conductivity

(1) Consider a spherical Liquid Helium Vessel shielded with Liquid Nitrogen

bath. The arrangement is shown in figure. Multilayer insulation made up of

24 layers per cm. is applied at each stage. Emissivity of aluminum shield is

0.05 and solid conductance of spacer is 0.0851 W/m2K. Calculate apparent

thermal conductivity of the MLI.

(2) Calculate the mean apparent thermal conductivity of a MLI for following

cases.

(A) Between 300 K and 20 K and (B) Between 20 K and 4 K

MLI is constructed of 30 layers per cm of aluminum foil having emissivity

0.05 and fiberglass paper. The solid conductance of the spaces material

may be assumed to be 0.09 W/m2K.

Experiment No:3

Aim: To compare different insulating materials used in cryogenics applications

Question

Q.1 why insulation is necessary for cryogenic vessels? List the types of cryogenic

insulations and write a note on power insulation.

Q.2 Describe the mechanism of insulation in case of each of the following and

state the modes of heat transfer against which they are not effectives (i) Opacified

powder (ii) evacuated powder and fibrous insulation. (iii) Expanded foam

insulations. Give their specifications.

Q.3 Write important properties to be considered for selection of insulation.

Q.4 Compare the following insulations with their advantages and disadvantages.

1. Expanded foam

2. Gas-filled powders & fibrous materials

3. Vacuum alone

4. Opacified powders

5. Evacuated powders & fibrous materials

6. Multilayer insulations.

Q.5 write a note on Multilayer Insulation.

Experiment No:4

Aim: To compare different insulating materials used in cryogenic applications based on Heat transferred through the insulation

Question

Q.1 Determine the time required to boil 1 litre of liquid at its normal boiling point

for (i) LH2 (ii) LO2 and (iii) LN2, if heat transfer rate to the flask is 4 watts.

(Hint: First find out mass of cryogen to boil, then total latent heat to be added to

cryogen and last time required using the heat transfer rate given.)

Q.2 A spherical Liquid Nitrogen vessel is as shown. The inner and outer radii are

1.2 m and 1.6 m respectively. Compute, compare and comment on the heat leak for

the following cases.

(a) If perlite having apparent thermal conductivity 26 mW/mk is used as insulation.

(b) If Vacuum is used as insulation. ( = 0.72)

(c) If Evacuated Fine Perlite having apparent thermal conductivity 0.95 mW/mk is

used as insulation.

(d) If 50/50 Cu Santocel having apparent thermal conductivity 0.33 mW/mk is

used as insulation.

(e) If polyurethane having apparent thermal conductivity 33 mW/mk is used as

insulation.

(f) If 0.006 mm Al foil + 0.15 mm Fiberglass MLI made up of (N/x) = 20 having

apparent thermal conductivity 37 W/mk is used as insulation.

(Hint: Use 1 2

2 1

4 aapk R R TQ

R R

for all cases other than case (b))

Also calculate quantity of liquid nitrogen in lit/day that would vaporize in each

case.

Q.3 Consider a spherical Liquid Helium Vessel shielded with Liquid Nitrogen

bath. The arrangement is shown in figure. Multilayer insulation made up of 24

layers per cm. is applied at each stage. Emissivity of aluminum shield is 0.05 and

solid conductance of spacer is 0.0851 W/m2K. Calculate the boil off/day of LN2

and LHe.

(Hint: First calculate kap of Inner MLI

then Q and then quantity of boil off per

day for LHe and similarly for LN2)

Experiment No:5

Aim: To Study cryogenic storage vessels

Question

Q.1 Explain with neat sketch the elements of a dewar vessel ?

Experiment No:6

Aim: To study various applications of cryogenic systems

Question

Q.1 Define cryogenics. Discuss the importance of cryogenics.

Q.2 Explain superconductivity and list its different applications? Explain any one

application in detail.

Q.3 Explain the applications of cryogenics in blood preservations and bio-cell

preservation.

Q.4 Discuss in detail about the applications of cryogenics in food preservations.

Q.5 Explain the applications of cryogenics in space simulation. Discuss in detail.

Experiment No:7

Aim: To Study cryo-refrigeration system: isothermal source system, isobaric source system

Question

Q.1 Explain Joule-Thomson effect to produce of low temperature

Q.2 Define Joule-Thomson coefficient. With usual notations derive the

expression for it.

Q.3 Derive the equation for COP in thermodynamically ideal isobaric

refrigeration system.

Q.4 Explain thermodynamically ideal isothermal source refrigeration cycle and

derive the equation for COP.

Q.5 Determine COP for an isobaric source refrigerator operating reversibly

between sink temperature of 300 K and minimum source temperature of 80 K

and maximum source temperature of 100 K. The working fluid is nitrogen

working as perfect gas having source pressure of 1 atm. What will be

percentage change in COP when the medium is assumed to be real gas?

Q.6 Determine ideal COP for an isobaric source refrigerator operating reversibly

between sink temperature of 300 K and minimum source temperature of 70 K

and maximum source temperature of 90 K. The working fluid is nitrogen

working as perfect gas having source pressure of 1.013 mPa. What will be %

change in COP when the medium is assumed as real gas?

Experiment No:8

Aim: To Study working of magnetic refrigerator and thermal valves

Question

Q.1 State and explain the principle of magnetic cooling.

Q.2 Explain construction and working of a typical Magnetic Refrigerator with

figure.

Experiment No:9

Aim: To Study liquefaction system - ideal liquefaction system, simple linde hampson, pre-cooled linde hampson and dual pressure lnde hampson liquefaction system Question

Q.1 Explain the importance of inversion curves in cryogenic liquefaction

systems.

Q.2 Explain thermodynamically ideal system for liquefaction of air and derive an

expression for finding liquid yield and work requirement.

Q.3 Explain Linde dual pressure system. What is the importance of intermediate

pressure flow rate ratio in above system?

Q.4 What modification in Claude system was carried out by Heylandt? Describe

the modified system with a neat figure.

Q.5 Explain cascade system for gas liquefaction.

Q.6 Determine ideal work requirement for liquefaction of oxygen gas at 101.3

kPa & 300 K. Also determine the heat rejected per unit mass of gas in ideal

isothermal compressor.

Q.7 Determine the refrigerating effect, COP and FOM for a simple Linde-

Hampson refrigerator operating from 300 K and 101.3 kPa to 10.13 MPa. The

overall efficiency of the compressor is 75 % and the heat exchanger

effectiveness is 0.960. The working fluid for the refrigerator is nitrogen.

Q.8 Determine the liquid yield, work requirement per unit mass compressed in

the high-pressure compressor, and work requirement per unit mass liquefied for

a Linde dual-pressure system operating with nitrogen as the working fluid

between 101.3 kPa and 300 K and 20.3 MPa. The intermediate pressure is 5.07

MPa and the intermediate-pressure flow rate is 0.80.