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.

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.

20 minutes

5 minutes

10 minutes

40 minutes

20 minutes

5 minutes

10 minutes

40 minutes

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
Multiple effect evaporation is generally recommended, when the

Evaporation on small scale is to be done

Corrosive liquids are to be concentrated

Fuel is cheaply available

Large scale evaporation of liquor is needed

Evaporation on small scale is to be done

Corrosive liquids are to be concentrated

Fuel is cheaply available

Large scale evaporation of liquor is needed

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
Rate of heat transfer by vaporisation from pools of water is affected by the

All of these

Nature of heating surface and distribution of bubbles

Surface tension of water

Viscosity of water

All of these

Nature of heating surface and distribution of bubbles

Surface tension of water

Viscosity of water

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.

none of the listed here

transition

pool

film

none of the listed here

transition

pool

film

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are

(COP)R = (COP)HP = 2.5

(COP)R = (COP)HP = 0.6

(COP)R = 1.5; (COP)HP = 2.5

(COP)R = 2.5; (COP)HP = 1.5

(COP)R = (COP)HP = 2.5

(COP)R = (COP)HP = 0.6

(COP)R = 1.5; (COP)HP = 2.5

(COP)R = 2.5; (COP)HP = 1.5

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer
In a boiling curve, the peak heat flux is called the __________ point.

Burnout

Leidenfrost

Nusselt

Boiling

Burnout

Leidenfrost

Nusselt

Boiling

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer

Heat Transfer Multiple effect evaporation is generally recommended, when the

Heat Transfer Rate of heat transfer by vaporisation from pools of water is affected by the

Heat Transfer When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.

Heat Transfer In a boiling curve, the peak heat flux is called the __________ point.

Heat Transfer
Multiple effect evaporation is generally recommended, when the

Heat Transfer
Rate of heat transfer by vaporisation from pools of water is affected by the

Heat Transfer
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.

Heat Transfer
In a boiling curve, the peak heat flux is called the __________ point.