Heat Transfer (Chemical Perspective) – Multiple Choice Questions (MCQs)

1. 97. What is 'thermal diffusivity' (α)?

   • A. A measure of a material's ability to conduct thermal energy relative to its ability to store thermal energy
   • B. A measure of thermal conductivity
   • C. A measure of specific heat
   • D. A measure of density

2. 98. What is the 'Biot number' (Bi)?

   • A. A dimensionless number that compares the heat transfer resistance within a body to the heat transfer resistance at the surface of the body
   • B. A dimensionless number for fluid flow
   • C. A dimensionless number for mass transfer
   • D. A dimensionless number for radiation

3. 99. What is the 'Nusselt number' (Nu)?

   • A. A dimensionless number representing the ratio of convective to conductive heat transfer across a boundary
   • B. A dimensionless number for fluid flow
   • C. A dimensionless number for mass transfer
   • D. A dimensionless number for radiation

4. 100. What is the 'Prandtl number' (Pr)?

   • A. A dimensionless number that relates momentum diffusivity to thermal diffusivity
   • B. A dimensionless number for mass transfer
   • C. A dimensionless number for fluid flow
   • D. A dimensionless number for heat conduction

5. 101. What is the 'Grashof number' (Gr)?

   • A. A dimensionless number that characterizes natural convection heat transfer
   • B. A dimensionless number for forced convection
   • C. A dimensionless number for conduction
   • D. A dimensionless number for radiation

6. 102. What is the 'critical thickness of insulation'?

   • A. The insulation thickness at which the heat loss from a pipe or sphere is maximized
   • B. The insulation thickness at which heat loss is minimized
   • C. The minimum thickness of insulation required
   • D. The maximum thickness of insulation allowed

7. 103. What is 'transient heat conduction'?

   • A. Heat conduction where the temperature within the body changes with time
   • B. Heat conduction where temperature is constant
   • C. Heat conduction in a steady state
   • D. Heat conduction without any medium

8. 104. What is 'steady-state heat conduction'?

   • A. Heat conduction where the temperature distribution within the body does not change with time
   • B. Heat conduction where temperature changes with time
   • C. Heat conduction in an unsteady state
   • D. Heat conduction with fluid motion

9. 105. What is the 'thermal resistance' concept in heat transfer?

   • A. The opposition a material offers to the flow of heat
   • B. The rate of heat flow
   • C. The temperature difference
   • D. The area for heat transfer

10. 106. What is 'thermal contact resistance'?

    • A. Resistance to heat transfer at the interface between two solid surfaces due to imperfect contact
    • B. Resistance within a single material
    • C. Resistance due to fluid flow
    • D. Resistance due to radiation

11. 107. What is the 'log mean area' used for in heat conduction through thick-walled cylinders?

    • A. To calculate the effective heat transfer area
    • B. To calculate the volume of the cylinder
    • C. To calculate the density of the material
    • D. To calculate the mass of the cylinder

12. 108. What is 'counter-current flow' in a heat exchanger?

    • A. The hot and cold fluids flow in opposite directions
    • B. The hot and cold fluids flow in the same direction
    • C. The fluids flow perpendicular to each other
    • D. One fluid is stagnant