Heat Transfer
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.

10 minutes
20 minutes
40 minutes
5 minutes

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because

Total heat transfer area of all the effects is -less than that in a single effect evaporator system
Boiling point elevation in a single effect system is much higher than that in any effect in a multieffect system
Heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect system
Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Heat Transfer