Heat Transfer MCQs

Question 1

Steam is routed through the tube in case of a __________ evaporator.

Accepted Answer

Horizontal tube

Answer

Basket type

Answer

Short tube vertical

Answer

Long tube vertical

Question 2

In a shell and tube heat exchanger,

Accepted Answer

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

Answer

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

Answer

There is no relationship between temperature drop and resistance

Answer

The relationship is not generalised

Question 3

Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?

Accepted Answer

Density

Answer

Corrosiveness & fouling characteristics

Answer

Pressure

Answer

Viscosity

Question 4

Pick out the wrong statement.

Accepted Answer

Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

Answer

'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate'

Answer

In heat exchanger calculations (Δt)weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling

Answer

In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Question 5

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

Accepted Answer

Highly viscous

Answer

Scaling

Answer

Corrosive

Answer

Salty

Question 6

In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)

Accepted Answer

α = 1; ε = 1

Answer

α = 1; ε ≠ 1

Answer

α ≠ 1, ε = 1

Answer

α ≠ 1, ε ≠ 1

Question 7

Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be

Accepted Answer

0.45

Answer

0.35

Answer

0.55

Answer

0.85

Question 8

For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area

Accepted Answer

Passes through a maxima

Answer

Increases

Answer

Decreases

Answer

Remains constant

Question 9

Steam trap is used to

Accepted Answer

Remove water resulting from partial condensation of steam

Answer

Condense the steam flowing in the pipeline

Answer

Stop the supply of steam

Answer

None of these