Critical Radius of Insulation for Hollow Sphere - MCQS with Answers

1. The critical radius of a hollow sphere having thermal conductivity k and ho as convecting heat transfer coefficient of outer fluid is given by

a. ho / k
b. k / ho
c. 2k / ho
d. ho / 2k

View Answer / Hide Answer

ANSWER: c. 2k / ho




2. At the critical radius of insulation of a hollow sphere, the heat transfer will be

a. minimum
b. maximum
c. does not change
d. unpredictable

View Answer / Hide Answer

ANSWER: b. maximum




3. A hollow sphere of internal diameter ID = 20 cm and outer diameter OD = 30 cm contains hot fluid. What should be the critical radius of insulation for maximum rate of heat transfer? Thermal conductivity k = 0.86 W/mK and convection heat transfer coefficient of outer fluid ho = 20 W/m2K.

a. 0.086 cm
b. 0.86 m
c. 8.6 mm
d. 8.6 cm

View Answer / Hide Answer

ANSWER: d. 8.6 cm


Post your comment

Related Content

Follow us

Related Topics
▲