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GATE 2021: Heat Transfer Rapid Mini Mock (App update required to attempt this test)

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Question 1

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

Question 2

Two very large parallel plates have emissivities  = 0.5 and  = 0.9. the plates are maintained at uniform temperatures of  = 600K and  = 400K. What will be the net rate of radiation heat transfer between the two surfaces per unit area of the plates?

Question 3

The profile of temperature w.r.t. radius for a cylinder is

Question 4

Which expression is correct for the effectiveness of heat exchanger

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

The hollow cylinder of internal and outer radius 100 mm and 50 mm respectively is under radial steady state heat conduction with no Internal heat generation. T(r1) = 150°C, T(r2) = 350°C, T (r = 80 mm) in °C is

Question 7

The maximum allowable surface temperature of an electrically heated vertical plate 15 cm high and 10 cm wide is 140°C . Calculate the maximum rate of heat dissipation(in W) from both sides of plate in an atmosphere of 20°C . Consider the flow as laminar. Take v = 21.09 × 10–6 m2/s. Pr = 0.692, k = 0.03 w/mk.

Question 8

A copper wire of radius 1.5 mm is exposed to a surrounding having heat transfer coefficient 5000 W/m2K & temperature 100o C. Find the value of current passing through wire to maintain centreline temperature of 1500 C. Assume specific resistance of copper 5 μΩ-cm & thermal conductivity of copper 387 W/mK.

Question 9

Consider the following statements regarding heat exchangers:

1) The maximum attainable temperature of fluid is equal to inlet temp of hot fluid

2) Counter flow heat exchanger is thermodynamically more efficient than parallel flow heat exchange

3) Counter flow heat exchange is thermodynamically less efficient than parallel flow heat exchanger

Which of the following statements is/are correct?

Question 10

Two long parallel surface each of emissivity 0.6 are maintained at different temperatures. It is desired to reduce 80% of this radiant heat transfer by inserting thin parallel shield of same emissivity on both sides. The number of space and surface resistance are respectively __________.

Question 11

Two parallel plates are at temperatures of 27°C and 527°C respectively. A radiation shield having emissivity equal to that of the plates is inserted between them. The temperature of the shield is__________ °C

Question 12

For laminar flow with free convection over the vertical plate, the heat transfer coefficient is given by


The value of k is (lc = characteristic length)

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