Heat Transfer MCQs

Question 1

Unsteady state heat conduction occurs, when

Accepted Answer

Temperature distribution is dependent on time

Answer

Temperature distribution is independent of time

Answer

Heat flows in one direction only

Answer

Three dimensional heat flow is concerned

Question 2

To reduce the tube side pressure drop for the same flow rate, the heat exchanger recomended is

Accepted Answer

1-1 heat exchanger

Answer

1-2 heat exchanger

Answer

3-2 heat exchanger

Answer

2-4 heat exchanger

Question 3

In the free convection regime of pool boiling, the heat flux is proportional to

Accepted Answer

$$\Delta {{	ext{t}}^{\frac{5}{4}}}$$

Answer

$$\Delta {{	ext{t}}^{\frac{1}{2}}}$$

Answer

Δt2

Answer

Δt

Question 4

The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as

Accepted Answer

Ha = 2hL

Answer

Ha = 0.8hL

Answer

Ha = hL

Answer

Ha= 5hL

Question 5

For what value of Prandtl number, $${	ext{St}} = \frac{{	ext{f}}}{2}?$$

Accepted Answer

1

Answer

1.5

Answer

> 1

Answer

< 1

Question 6

Prandtl and Reynolds analogy are same, when Prandtl number is

Accepted Answer

1

Answer

0.5

Answer

> 2

Answer

1.5

Question 7

Calburn analogy is applicable for the value of Prandtl number from

Accepted Answer

0.6 to 120

Answer

0.001 to 1

Answer

0.5 to 5

Answer

120 to 400

Question 8

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

Accepted Answer

0.1

Answer

>1

Answer

< 1

Answer

L

Question 9

Conductance is given by (where, x = thickness, A = heat flow area, K = thermal conductivity.)

Accepted Answer

$$\frac{{{	ext{KA}}}}{{	ext{x}}}$$

Answer

$$\frac{{	ext{x}}}{{{	ext{KA}}}}$$

Answer

$$\frac{{	ext{K}}}{{{	ext{Ax}}}}$$

Answer

$$\frac{{	ext{A}}}{{{	ext{Kx}}}}$$