Heat Transfer MCQs

Question 1

The units of resistance to heat transfer is

Accepted Answer

W-1.m2.K

Answer

J.m-2.K-1

Answer

J.m-1.K-1

Answer

W.m-2.K-1

Question 2

A sphere of radius 'R1' is enclosed in a sphere of radius 'R2'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is

Accepted Answer

$$\frac{{{{	ext{R}}_2}}}{{{{	ext{R}}_1} + {{	ext{R}}_2}}}$$

Answer

0

Answer

1

Answer

$${\left( {\frac{{{{	ext{R}}_1}}}{{{{	ext{R}}_2}}}} ight)^2}$$

Question 3

For hot feed, forward feeding as compared to backward feeding results in __________ economy.

Accepted Answer

Increased

Answer

Decreased

Answer

No effect on

Answer

None of these

Question 4

Reynold's analogy states that

Accepted Answer

Nst α f

Answer

Nst α NRe

Answer

NNu α f

Answer

NRe α f

Question 5

A perfect black body is a perfect __________ of radiation.

Accepted Answer

Both A & B

Answer

Absorber

Answer

Emitter

Answer

Neither A nor B

Question 6

Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping

Accepted Answer

Both the tube sheets fixed

Answer

Both the tube sheets floating

Answer

The top tube sheet floating and bottom tube sheet fixed

Answer

The top tube sheet fixed and the bottom tube-sheet floating

Question 7

Pick out the wrong statement.

Accepted Answer

Duhring's plot is used for calculating the concentration of solution

Answer

The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system

Answer

Entering velocity of the liquid in the tubes of natural circulation evaporators is in the range of 0.3 to 0.9 metre/second

Answer

In a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

Question 8

Thermal diffusivity of a material

Accepted Answer

All of the above

Answer

Has the unit m2/sec

Answer

Is defined as $$\frac{{	ext{K}}}{{ho .{{	ext{C}}_{	ext{p}}}}}$$

Answer

Is the ratio of thermal conductivity to thermal capacity

Question 9

$$\frac{{{{	ext{C}}_{	ext{p}}}.\mu }}{{	ext{K}}}$$ is termed as the __________ number.

Accepted Answer

Prandtl

Answer

Grashoff

Answer

Nusselt

Answer

Stanton