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.

10 minutes

20 minutes

40 minutes

5 minutes

10 minutes

20 minutes

40 minutes

5 minutes

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Heat Transfer
Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

45

50

37

32

45

50

37

32

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Heat Transfer
LMTD for counterflow and prallel flow heat exchanger will be the same, when the

Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid)

Outlent temperature of both the hot and cold fluid are same

None of these

Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid

Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid)

Outlent temperature of both the hot and cold fluid are same

None of these

Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid

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Heat Transfer
Which of the following is concerned with both heat and mass transfer ?

Nusselt number

Lewis relationship

Froude number

Kutateladze number

Nusselt number

Lewis relationship

Froude number

Kutateladze number

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Heat Transfer
In a multiple effect evaporator, the effect of boiling point elevation is to

reduce the economy

reduce the capacity

all of the listed here

increase the economy

reduce the economy

reduce the capacity

all of the listed here

increase the economy

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Heat Transfer
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.

Less than

Either more or less than (depending upon the fluid)

More than

Equal to

Less than

Either more or less than (depending upon the fluid)

More than

Equal to

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Heat Transfer

Heat Transfer Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Heat Transfer LMTD for counterflow and prallel flow heat exchanger will be the same, when the

Heat Transfer Which of the following is concerned with both heat and mass transfer ?

Heat Transfer In a multiple effect evaporator, the effect of boiling point elevation is to

Heat Transfer In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.

Heat Transfer
Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Heat Transfer
LMTD for counterflow and prallel flow heat exchanger will be the same, when the

Heat Transfer
Which of the following is concerned with both heat and mass transfer ?

Heat Transfer
In a multiple effect evaporator, the effect of boiling point elevation is to

Heat Transfer
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.