Heat Transfer MCQs

Question 1

Crystallisation of solids from a homogeneous solution is a/an __________ process.

Accepted Answer

Exothermic

Answer

Mildly endothermic

Answer

Highly endothermic

Answer

None of these

Question 2

Reynold's analogy states that (where, St = Stanton number, f = friction factor)

Accepted Answer

$${	ext{St}} = \frac{{	ext{f}}}{2}$$

Answer

$${	ext{St}} = \frac{{	ext{f}}}{4}$$

Answer

St = 4f

Answer

$${	ext{St}} = {{	ext{f}}^{\frac{1}{2}}}$$

Question 3

Which is the most suitable for the concentration of foamy & frothy liquors?

Accepted Answer

Long tube vertical evaporator

Answer

Agitated film evaporator

Answer

Open pan evaporator

Answer

None of these

Question 4

Pick out the wrong statement.

Accepted Answer

The maximum is the emissive power of a surface at a temperature T1 occurs at a wavelength of λ1. If the surface temperature is halved, the maximum in the emissive power would occur at a wavelength of 0.5 λ1

Answer

In process heat exchangers, saturated steam is preferred over the superheated steam

Answer

When a vertical plate is heated in infinite air environmental under natural convection conditions, the velocity profile in air, normal to the plate, exhibits a maximum

Answer

A body at 925 K emits an energy of 1.42 × 1011σW/m2 (σ is the Stefan-Boltzman constant) in the wavelength band between 3 μm to 4 μm. The fraction of this energy in the total energy emitted over the entire wavelength range is equal to emissivity

Question 5

Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water.

Accepted Answer

Boiling point (at the same pressure)

Answer

Viscosity

Answer

Density

Answer

Thermal conductivity

Question 6

Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is

Accepted Answer

Thin walled having the value of Ao Ai/< 2

Answer

Thick walled

Answer

Having the value of Ao/Ai > 2

Answer

Both B and C

Question 7

In Fourier's law, the proportionality constant is called the

Accepted Answer

Thermal conductivity

Answer

Heat transfer co-efficient

Answer

Thermal diffusivity

Answer

Stefan-Boltzman constant

Question 8

Which area is used in case of heat flow by conduction through a cylinder?

Accepted Answer

Logarithmic mean area

Answer

Arithmetic mean area

Answer

Geometric mean area

Answer

None of these

Question 9

__________ heat exchanger is used for chilling oil to be dewaxed.

Accepted Answer

Double pipe

Answer

U-tube

Answer

Fixed tube

Answer

Floating head