McqMate
Sign In
Hamberger menu
McqMate
Sign in
Sign up
Home
Forum
Search
Ask a Question
Sign In
McqMate Copyright © 2025
→
Mechanical Engineering
→
Heat Transfer (HT)
→
The critical radius 'r' of insulation on...
Q.
The critical radius 'r' of insulation on a pipe is given by
A.
r = 2k/h
B.
r = k/h
C.
r = k/2h
D.
r = h/k
Answer» B. r = k/h
2.2k
0
Do you find this helpful?
11
View all MCQs in
Heat Transfer (HT)
Discussion
No comments yet
Login to comment
Related MCQs
A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2 .°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe)
The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface)
A sphere 15 cm in diameter is covered with 5 cm of insulation (k = 0.057 kcal/m-hr-?C). The inside and outside surface temperature of the insulation are 315?C and 80?C respectively. The heat loss per sq. m of the outside surface will be closer to
For a given ambient air temperature with increase in the thickness of insulation of a hot cylindrical pipe, the rate of heat loss from the surface would
A sphere of radius 'R1' is enclosed in a sphere of radius 'R2'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large.
A sphere of radius 40 cm is lagged to a radius of 50 cm. The temperatures of outer and inner surfaces are 66?C and 235?C respectively. Thermal conductivity of logging per cm thickness is 0.7 kcal/m-hr?C. The rate of heat leakage will be
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.