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

1. 121. What is the 'critical heat flux' (CHF) in boiling?

   • A. The maximum heat flux that can be achieved in nucleate boiling before film boiling occurs
   • B. The minimum heat flux for boiling
   • C. The heat flux at which boiling stops
   • D. The heat flux for condensation

2. 122. What is 'quenching'?

   • A. Rapid cooling of a material
   • B. Rapid heating of a material
   • C. Slowing down heat transfer
   • D. Insulating a material

3. 123. What is 'regenerator' heat exchanger?

   • A. A heat exchanger where the same flow passages are alternately heated by a hot fluid and then cooled by a cold fluid
   • B. A heat exchanger where fluids flow continuously
   • C. A heat exchanger for boiling
   • D. A heat exchanger for condensation

4. 124. What is the 'overall energy balance' for a heat exchanger at steady state?

   • A. Rate of heat gained by cold fluid = Rate of heat lost by hot fluid
   • B. Rate of heat gained by hot fluid = Rate of heat lost by cold fluid
   • C. Heat input = Heat output + Work done
   • D. Mass input = Mass output

5. 125. What is 'thermal expansion'?

   • A. The tendency of matter to change in volume in response to a change in temperature
   • B. The tendency of matter to change phase
   • C. The tendency of matter to conduct heat
   • D. The tendency of matter to resist heat flow

6. 126. What is 'thermal stress'?

   • A. Stress caused by temperature changes
   • B. Stress caused by external forces
   • C. Stress caused by fluid flow
   • D. Stress caused by chemical reactions

7. 127. What is the 'heat generation rate' for a volumetric heat source?

   • A. q''' (heat generated per unit volume)
   • B. Q (total heat generated)
   • C. q'' (heat flux)
   • D. k (thermal conductivity)

8. 128. What is 'heat pipe'?

   • A. A heat transfer device that uses phase change (evaporation and condensation) to transfer heat with very high effective thermal conductivity
   • B. A device for insulation
   • C. A device for mixing fluids
   • D. A device for generating heat

9. 129. What is 'thermal shock'?

   • A. Damage caused by rapid temperature changes
   • B. Damage caused by overheating
   • C. Damage caused by undercooling
   • D. Damage caused by chemical reactions

10. 130. What is 'quenching' process typically used for in metallurgy?

    • A. Rapid cooling to harden a material
    • B. Slow cooling to soften a material
    • C. Heating a material to high temperatures
    • D. Shaping a material

11. 131. What is a 'furnace' in chemical engineering?

    • A. An enclosed structure where materials are heated to very high temperatures
    • B. A device for cooling fluids
    • C. A device for mixing chemicals
    • D. A device for separating components

12. 132. What is 'radiation intensity'?

    • A. The rate at which radiation is emitted from a surface per unit area and per unit solid angle
    • B. The total energy emitted by radiation
    • C. The wavelength of radiation
    • D. The frequency of radiation