Hollow Cylinder - Steady-State Heat Conduction - MCQs with Answers

Hollow Cylinder - Steady-State Heat Conduction - MCQs with Answers

Q1. What is the formula for the thermal resistance (R) of a hollow cylinder of internal radius Ri, outer radius Ro and the length l ? Thermal conductivity of the cylinder material is k. The heat flows from inner side to outer side.

a. R = ln (Ro / Ri) / 2πkl
b. R = ln (Ri / Ro) / 2πkl
c. R = (Ro + Ri) / 2πkl
d. R = (RoRi) / 2πkl

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Q2. A hollow cylinder of length of 1m, inner radius (Ri) 0.01m and outer radius (Ro) 0.05m has a thermal conductivity (k) 20 W/mK. The inside surface temperature is at 500K. What is the outside surface temperature of the cylinder when the rate of radial heat transfer is 3.13 kW?

a. 400 K
b. 360 K
c. 460 K
d. insufficient data

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Q3. As the radius increases in hollow cylinder the temperature

a. also increases
b. decreases
c. it depends upon the direction of heat flow
d. unpredictable

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Q4. For the composite cylinder as shown in figure, the thermal resistances of every layer from inside to outside of the cylinder are given as follows,

R1 = ln (r₁ / r_i) / 2πk₁l
R1 = ln (r_o / r₁) / 2πk₂l

What will be the total thermal resistance of the composite cylinder?



a. R = R1 + R2
b. R = R1R2 / (R1 + R2)
c. R = R1 / (R1 + R2)
d. R = R2 / (R1 + R2)

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