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GATE 2022 ME: Heat-Transfer Quiz - 1

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Question 1

If a foam insulation is added to a 4cm outer diameter pipe as shown in the figure, the critical radius of insulation (in cm) is __________ .

Question 2

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 3

Heat is generated steadily in a 3 cm diameter spherical ball. The ball is exposed to ambient air at 26oC with a heat transfer coefficient of 7.5 W/m2-oC. The ball is to be covered with a material of thermal conductivity 0.15 W/m-oC. If the ball surface temperature remains as constant, the thickness of the covering material that will maximize heat generation within the ball, is _________.

Question 4

A plane wall of 0.2m thickness and 25 W/m-K thermal conductivity is uniformly  generating heat within the slab. The slab is exposed to a fluid at 92oC & the convection heat transfer coefficient between the wall and the fluid is 500 W/m2-K. If the  uniform volumetric heat generation within the slab is 0.3 MW/m3, the maximum temperature in the wall is

Question 5

A wall of thickness 0.6 m has a normal area 1.5 m2 and is made up of material of thermal conductivity 0.4 W/mK. The temperature on the two sides are 8000 C and 1000 C. What is the thermal resistance of the wall?

Question 6

Determine the heat transfer through a plane of length 4 m, height 3 m and thickness 0.2 m. The temperatures of innner and outer surfaces are and respectively. Thermal conductivity of the wall is 0.5 W/mK.
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