Month: March 2019

Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the_________________?

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Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the_________________?

A. Existence of thermal boundary layer
B. Temperature gradient produced due to density difference
C. Buoyancy of the bubbles produced at active nucleation site
D. None of these

For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

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For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

A. 1.26 h1
B. 0.794 h1
C. 0.574 h1
D. 1.741 h1

Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

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Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

A. 35.5
B. 43.75
C. 81.25
D. 48.25

For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________?

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For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________?

A. Decreases the pressure drop
B. Decreases the outlet temperature of cooling medium
C. Increases the overall heat transfer coefficient
D. None of these

Weep holes provided in the plates of a distillation column ____________________?

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Weep holes provided in the plates of a distillation column ____________________?

A. Facilitate draining out liquid from a tray when the unit is not in operation
B. Are normally located near the overflow weir so that any delivery of liquid during operation
follows approximately the same path as the overflow fluid
C. Must be large enough (usually 1/4″ to 5/8″ dia) to prevent plugging but should not deliver
excessive amount of fluid during operation
D. All A., B. and C.