HEAT TRANSFER QUIZ

Planck's distribution law is valid for __________ bodies

black

all of the listed here

white

coloured

TRUE ANSWER : ?
YOUR ANSWER : ?

With increase in temperature, the thermal conductivity of most liquids

Decreases

Increases

First increases upto a certain temperature and then becomes constant

Remains same

TRUE ANSWER : ?
YOUR ANSWER : ?

Heat transfer rate described by Fourier's law will decrease, if the __________ increases.

Thickness

Thermal conductivity

Temperature difference

Heat transfer area

TRUE ANSWER : ?
YOUR ANSWER : ?

If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

Increase by 216

Decrease by 22

Remain unchanged

Increase by 1.8 times

TRUE ANSWER : ?
YOUR ANSWER : ?

The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe )

K/h0

hi/K

2K/h0

2hi/K

TRUE ANSWER : ?
YOUR ANSWER : ?

In a shell and tube heat exchanger,

The temperature drop is inversely proportional to the resistance across which the drop occurs

The relationship is not generalised

The temperature drops in the two fluids and the wall are proportional to individual resistances

There is no relationship between temperature drop and resistance

TRUE ANSWER : ?
YOUR ANSWER : ?

Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)

0.3 D

0.2 D

0.5 D

0.4 D

TRUE ANSWER : ?
YOUR ANSWER : ?

The most conducive surface for dropwise condensation to occur is the __________ surface.

Coated

Smooth

Glazed & polished

Oily

TRUE ANSWER : ?
YOUR ANSWER : ?

The thermal boundary layer at NPr > 1

And the hydrodynamic boundary layer are identical

Is thinner than hydrodynamic boundary layer

Is thicker than hydrodynamic boundary layer

Disappears

TRUE ANSWER : ?
YOUR ANSWER : ?

In a backward feed multiple effect evaporator

Feed flows from low pressure to high pressure

None of these

Feed is introduced in the first effect

No pumps are required between successive effects

TRUE ANSWER : ?
YOUR ANSWER : ?