HEAT TRANSFER QUIZ

Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?

Liquid density

Interfacial tension

Hot surface temperature

Liquid viscosity

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YOUR ANSWER : ?

In the equation Q = UAΔt; Δt is

Geometric mean temperature difference

Logarithmic mean temperature difference

Arithmetic mean temperature difference

The difference of average bulk temperatures of hot and cold fluids

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YOUR ANSWER : ?

Which of the following has the minimum absorptivity?

Iron plates

Refractory bricks

Aluminium foil

Coal dust

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Solid angle subtended by the finite surface at the radiating element is

called the angle of vision

expressed in terms of radians

proportional to the square of the distance between surfaces

called the view factor.

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YOUR ANSWER : ?

While the total emissivity of a perfect black body is unity, the same for a real body is

between 0 and 1

>1

1

0

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Which is the most suitable for the concentration of foamy & frothy liquors?

Open pan evaporator

None of these

Long tube vertical evaporator

Agitated film evaporator

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Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is

< 1

>1

0.1

L

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YOUR ANSWER : ?

The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is

Sherwood number

Nusselt number

Stanton number

Schmidt number

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Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second.

3 x l05

3 x l012

3 x l08

3 x l010

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Open pan evaporators are preferred to be used, when the solution to be concentrated is

Highly viscous

Salty

Corrosive

Scaling

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