Download PTU B-Tech ME 2020 Dec 6th Sem 71186 Heat Transfer Question Paper

Download PTU (I.K.Gujral Punjab Technical University (IKGPTU)) B-Tech (Bachelor of Technology) Mechanical Engineering 2020 December 6th Sem 71186 Heat Transfer Previous Question Paper

Roll No.
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech. (ME) (2012 Onwards) (Sem.?6)
HEAT TRANSFER
Subject Code : BTME-602
M.Code : 71186
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
Write briefly :
1.
Define Thermal conductivity.
2.
What are the different assumptions applied while doing heat conduction analysis?
3.
In case of insulating an electric wire, should the outer radius of insulation be more or less
than the critical radius, briefly explain with reason.
4.
Why thin fins are preferred over a thick fin?
5.
Define the term NTU. What does it interpret?
6.
Define the term intensity of radiation.
7.
Define Grashoff Number. What are the forces associated with it?
8.
In which type of condensation heat transfer coefficient remains more and why?
9.
What is Newtonian heating of solids?
10. What is the limitation of Rayleigh's method of dimensional analysis?
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SECTION-B
11. What are the three dimensions in case of spherical coordinate system? How they are
obtained?
12. Derive the relation of temperature distribution and heat transfer for rectangular fin losing
heat at the tip.
13. Prove by dimensional analysis for natural convection that Nusselt no. is a function of
Grashoff no. and Prandtle no.
14. Explain different theories of nucleation.
15. State and explain Kirchoff's law.
SECTION-C
16. An electric wire with 2mm diameter is covered with 2.5mm thick layer of insulation with
k = 0.5 W/mK. Heat is dissipated to the atmosphere at 25?C with h=10W/m2K. The wire is
maintained at temperature of 120?C. Estimate the heat dissipation from the wire with and
without insulation. Calculate the thickness of insulation when the heat dissipation rate is
maximum, also maximum value of heat dissipation rate.
17. The A parallel flow, heat exchanger has hot and cold water streams running through it and
has the following data : mh = 10kg/min, mc = 25kg/min, Cph, = Cpc= 4.18 kJ/kg?C,
th1 = 70?C, th2 = 50?C, tc1 = 25?C. Heat transfer coefficients on both sides are 50 W/m2.
Calculate:
a) The area of heat exchanger
b) The exit temperatures of hot and cold fluids if hot water flow rate is doubled.
18. Write short notes on :
a) Hydrodynamic and thermal boundary layer
b) Variable thermal conductivity
NOTE : Disclosure of identity by writing mobile number or making passing request on any
page of Answer sheet will lead to UMC against the Student.
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