The thermal boundary layer at NPr > 1 ?

Byadmin March 2, 2019August 24, 2021

The thermal boundary layer at NPr > 1 ?

A. Is thicker than hydrodynamic boundary layer
B. Is thinner than hydrodynamic boundary layer
C. And the hydrodynamic boundary layers are identical
D. Disappears

Chemical Heat Transfer

Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the_________________?

Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the_________________?

A. Higher condensing film co-efficient is desired
B. Condensate is corrosive in nature
C. Lower pressure drop through the exchanger is desired
D. Temperature of the incoming vapor is very high

Read More Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the_________________?
Chemical 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_________________?

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_________________?

A. 555
B. 55.5
C. 0.55
D. 0.15

Read More 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_________________?
Chemical Heat Transfer

For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is______________?

For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is______________?

A. Nu = 0.023 Re0.8. Pr0.4
B. Nu = (π/2) Gz
C. Nu = (2/π) Gz
D. Nu = 2Gz0.5

Read More For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is______________?
Chemical Heat Transfer

_____________ heat exchanger is used for chilling oil to be dewaxed?

_____________ heat exchanger is used for chilling oil to be dewaxed?

A. U-tube
B. Double pipe
C. Fixed tube
D. Floating head

Read More _____________ heat exchanger is used for chilling oil to be dewaxed?
Chemical 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 ?

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. 5 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes

Read More 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 ?
Chemical Heat Transfer

A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

A. Yellow paint
B. White paint
C. Black paint
D. Grey paint

Read More A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

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