Heat Transfer MCQs

Question 1

The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.

Accepted Answer

Temperature of the body

Answer

Wavelength of radiation

Answer

Nature of the body

Answer

None of these

Question 2

Heat flux, as defined in heat flow is analogous to __________ in electricity flow.

Accepted Answer

Current

Answer

Voltage

Answer

Resistance

Answer

None of these

Question 3

The film thickness for laminar film condensation on vertical surface __________ from top to bottom.

Accepted Answer

Cummulatively increases

Answer

Cummulatively decreases

Answer

Remains constant

Answer

And the surface conductance increase

Question 4

The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.

Accepted Answer

Sum

Answer

Average

Answer

Geometric mean

Answer

Product

Question 5

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then

Accepted Answer

hf < hd

Answer

hf = hd

Answer

hf > hd

Answer

hf could be greater or smaller than hd

Question 6

A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2.K. The Biot number is

Accepted Answer

0.025

Answer

5.6

Answer

3.5

Answer

0.0035

Question 7

A 2-4 heat exchanger involves

Accepted Answer

Both counter and parallel-flow of the fluids

Answer

Only counter-flow of fluids

Answer

Only parallel-flow of fluids

Answer

Smaller pressure drop compared to 1-2 exchanger

Question 8

A BTU/hr.ft2.°F is equal to

Accepted Answer

4.88 kcal/hr.m2.°C

Answer

1 kcal/hr.m2.°C

Answer

1 kcal/hr.m2.°K

Answer

None of these

Question 9

A dephlegmator is a

Accepted Answer

Partial condenser

Answer

Total condenser

Answer

Vacuum evaporator

Answer

Double pipe heat exchanger