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BARC 2021 ME: Heat Transfer Nuclear Quiz 3

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Question 1

A,B,C,D,E,F & G are the layers of different materials thorough which is heat is to be flow.
If the resistance value of different layers are 
Ra= 5k/w, Rb=Rc=Rd= 2k/w, Re= 3k/w, Rf= 1k/w, Rg= 1.5k/w


Then effective resistance value for the given circuit will be

Question 2

A square channel of side 25mm and length 2.6m carries water at a velocity of 4m/sec. The mean temperature of water along length of channel is 32 ºC while inner channel surface temperature is 75 ºC. Calculate heat transfer coefficient from channel wall to water, Use correlation: Nu= 0.025The thermophysical properties of water at 32 ºC: ƿ= 9957kg/, k= 0.6175W/m ºC, 𝝼=0.815×, Pr= 5.42

Question 3

A 50 cm diameter pipeline carries hot oil at 30oC and is exposed to a surrounding temperature of -20oC . A special 5cm thick power insulation surrounds the pipe and has a thermal conductivity of 7 × 10-3 W/m-oC, what will be the energy loss from the pipe per meter of length if the pipe is urrounded by a fluid having heat transfer coefficient h = 9 W/m2oC)

Question 4

The heat transfer ratio of fin with adiabatic tip to infinitely long fin under same conditions is:

Question 5

12mm diameter Steel balls are annealed by heating to 1150 K and then slowly cooling to 400K in an air environment for which T = 325 K and h=20 W/m2 K. If the properties of the steel are k = 40 W/m K, ρ= 7800 kg/m3 and cp = 600 J/kg-K, what will be the time required for the cooling process?

Question 6

Steam is condensing in a condenser at 100 by a fluid which enter at 30 and leaves at a higher temperature. The NTU of the heat exchanger is 3.2. Find the exit temperature of the fluid used for condensing steam in

Question 7

The expression for steady one-dimensional temperature variation for a shown geometry will be?

Question 8

Heat transfer by radiation mainly depends upon _____________.

Question 9

Let 220 W/m2 of total radiant energy is absorbed by a convex surface, 90 W/m2 is reflected and 40 W/m2 is transmitted through it. What is the value of absorptivity?

Question 10

When the temperature of a solid surface changes from 127 °C to 927 °C, the ratio of emissive power final to initial will be
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