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Seat No.: Enrolment No.
GUJARAT TECHNOLOGICAL UNIVERSITY
BE SEM-VI Examnaton-No!"#e$-%&''
S()*e$t $o+e: ','&, #ate: &%"'%"%&''
S()*e$t Name: Heat an+ Ma Tran/er
Tme: '&.0& am -'.&& 1m Total mar2: 3&
Intr($ton:
'. Attem1t all 4(eton.
%. Ma2e (ta)le a(m1ton 56ere!er ne$ear7.
0. 89(re to t6e r96t n+$ate /(ll mar2.
.' ;a< What is the difference between the natural and forced
convection? &0
;)< Explain the following terms &=
1.Radiation
2.Thermal resistance
3.Thermal diffusivit!.Thermal conductivit
;$< " gas turbine blade made of stainless steel #$ %32
W&m'
() is *+ mm &3
long ,-++ mm2
cross sectional area and 12+ mm perimeter .The
temperature of the root of blade is -++'
( and it is exposed to the
combustion product of the fuel passing from turbine at 3+'
(./f the
film coefficient between the blade and the combustion gases is
3++
W&m2'(,
0etermine #1) The temperature at the middle of blade
#2)The rate of heat flow from the blade
.% ;a< 0erive general heat conduction euation in spherical
coordinates &3
;)< " furnace wall is made up of three laers of thic$ness 2-+
&3
mm,1++mm and 1-+mm with thermal conductivit of 1.4-,$ and
5.2
W&m'
( respectivel .The inside is exposed to gases at 12-+'
( with a
convection coefficient of 2- W&m2'( and the inside surface
is at
11++'
(,the outside surface is exposed to air at 2-'
( with convection
coefficient of
12 W&m2'(.0etermine
#1)The un$nown thermal conductivit $
#2)The overall heat transfer coefficient
#3)"ll 6urface temperaturesOR
;)< 0erive an expression for heat dissipation in Rectangular
7in of &3
uniform cross section which is insulated at tip .
.0 ;a< 0erive momentum euation for hdrodnamic boundar laer
over a &3
flat plate
;)< Enumerate the factors on which the rate of emission of
radiation b &0
bod depends.
;$< 0ifferentiate between pool boiling and forced convection
boiling &=
OR.0 ;a< 0efine 8usselt number and 9randtle number.
&=
;)< What is blac$ bod? :ow does it differ from gra bod? ;ive
&0
examples of each.
