A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m².K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is

Heat Transfer
A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m².K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is

55.5

555

0.55

0.15

55.5

555

0.55

0.15

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Heat Transfer
A graph between __________ is called Wilson plot.

V0.8 Vs . U

1/v0.8 Vs . U

1/U Vs . 1/v0.8

1/U Vs . 1/V

V0.8 Vs . U

1/v0.8 Vs . U

1/U Vs . 1/v0.8

1/U Vs . 1/V

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Heat Transfer
Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.

transition

laminar

None of the listed here

highly turbulent

transition

laminar

None of the listed here

highly turbulent

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Heat Transfer
The advantage of backward feed multiple effect evaporators over forward feed units is that

Heat sensitive material can be handled

Equal heat transfer co-efficients exist in various effects

Most concentrated liquid is at highest temperature

There is no additional cost of pumping

Heat sensitive material can be handled

Equal heat transfer co-efficients exist in various effects

Most concentrated liquid is at highest temperature

There is no additional cost of pumping

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Heat Transfer
In sub-cooled boiling,

Temperature of the heating surface is less than the boiling point of the liquid

Very large vapour space is necessary

Temperature of the heating surface is more than the boiling point of the liquid

Bubbles from heating surface are absorbed by the mass of the liquid

Temperature of the heating surface is less than the boiling point of the liquid

Very large vapour space is necessary

Temperature of the heating surface is more than the boiling point of the liquid

Bubbles from heating surface are absorbed by the mass of the liquid

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Heat Transfer
Log mean temperature difference (LMTD) cannot be used, if

none of the listed here

heat transfer co-efficient over the entire heat exchanger is not constant

there exists an unsteady state

the heat capacity is not constant and there is a phase change.

none of the listed here

heat transfer co-efficient over the entire heat exchanger is not constant

there exists an unsteady state

the heat capacity is not constant and there is a phase change.

ANSWER DOWNLOAD EXAMIANS APP

Heat Transfer

Heat Transfer A graph between __________ is called Wilson plot.

Heat Transfer Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.

Heat Transfer The advantage of backward feed multiple effect evaporators over forward feed units is that

Heat Transfer In sub-cooled boiling,

Heat Transfer Log mean temperature difference (LMTD) cannot be used, if

Heat Transfer
A graph between __________ is called Wilson plot.

Heat Transfer
Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.

Heat Transfer
The advantage of backward feed multiple effect evaporators over forward feed units is that

Heat Transfer
In sub-cooled boiling,

Heat Transfer
Log mean temperature difference (LMTD) cannot be used, if