Heat And Mass Transfer Mcqs Questions MCQs


heat and mass transfer mcqs Questions

Total Questions : 652

Page 1 of 33 pages
Question 1. Unit of thermal diffusivity is
  1.     m²/hr
  2.     m²/hr °C
  3.     kcal/m² hr
  4.     kcal/m. hr °C
Answer: Option A
Explanation :
Question 2. Thermal conductivity of water _________ with rise in temperature.
  1.     Remain same
  2.     Decreases
  3.     Increases
  4.     May increase or decrease depending upon temperature
Answer: Option D
Explanation :
Question 3. The critical radius is the insulation radius at which the resistance to heat flow is
  1.     Maximum
  2.     Minimum
  3.     Zero
  4.     None of these
Answer: Option B
Explanation :
Question 4. The automobile radiator is a heat exchanger of
  1.     Parallel flow type
  2.     Counter flow type
  3.     Cross flow type
  4.     Regenerator type
Answer: Option C
Explanation :
Question 5. The process of heat transfer from one particle of the body to another is called conduction, when the particles of the body
  1.     Move actually
  2.     Do not move actually
  3.     Affect the intervening medium
  4.     Does not affect the intervening medium
Answer: Option B
Explanation :
Question 6. Log mean temperature difference in case of counter flow compared to parallel flow will be
  1.     Same
  2.     More
  3.     Less
  4.     Depends on other factors
Answer: Option B
Explanation :
Question 7. According to stefan's law, the total radiation from a black body per second per unit area is proportional to
  1.     Absolute temperature
  2.     T2
  3.     T5
  4.     T
Answer: Option D
Explanation :
Question 8. Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. it is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. the number of shields should be
  1.     One
  2.     Two
  3.     Three
  4.     Four
Answer: Option C
Explanation :
Question 9. Sensible heat is the heat required to
  1.     Change vapour into liquid
  2.     Change liquid into vapour
  3.     Increase the temperature of a liquid of vapour
  4.     Convert water into steam and superheat it
Answer: Option C
Explanation :
Question 10. The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as
  1.     Conduction
  2.     Free convection
  3.     Forced convection
  4.     Radiation
Answer: Option B
Explanation :
Question 11. In counter current flow heat exchanger, the logarithmic temperature difference between the fluids is ________ as compared to parallel flow heat exchanger.
  1.     Same
  2.     Less
  3.     Greater
  4.     None of these
Answer: Option C
Explanation :
Question 12. The concept of overall coefficient of heat transfer is used in case of heat transfer by
  1.     Conduction
  2.     Convection
  3.     Radiation
  4.     Conduction and convection
Answer: Option D
Explanation :
Question 13. In heat transfer, conductance equals conductivity (kcal/hr/sq.m/°c/cm) divided by
  1.     Hr (time)
  2.     Sq. m (area)
  3.     °C (temperature)
  4.     K.cal (heat)
Answer: Option D
Explanation :
Question 14. Unit of thermal diffusivity is
  1.     m²/hr
  2.     m²/hr °C
  3.     kcal/m² hr
  4.     kcal/m. hr °C
Answer: Option A
Explanation :
Question 15. The radiation emitted by a black body is known as
  1.     Black radiation
  2.     Full radiation
  3.     Total radiation
  4.     All of these
Answer: Option D
Explanation :
Question 16. All radiations in a black body are
  1.     Reflected
  2.     Refracted
  3.     Transmitted
  4.     Absorbed
Answer: Option D
Explanation :
Question 17. Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in
  1.     Electric heater
  2.     Steam condenser
  3.     Boiler
  4.     Refrigerator condenser coils
Answer: Option C
Explanation :
Question 18. When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body,
  1.     α = 1, ρ = 0 and τ = 0
  2.     α = 0, ρ = 1 and τ = 0
  3.     α = 0, ρ = 0 and τ = 1
  4.     α + ρ = 1 and τ = 0
Answer: Option C
Explanation :
Question 19. Which of the following statement is wrong?
  1.     The heat transfer in liquid and gases takes place according to convection
  2.     The amount of heat flow through a body is dependent upon the material of the body
  3.     The thermal conductivity of solid metals increases with rise in temperature
  4.     Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference
Answer: Option C
Explanation :
Question 20. Thermal conductivity of a material may be defined as the
  1.     Quantity of heat flowing in one second through one cm cube of material when opposite faces are maintained at a temperature difference of 1°C
  2.     Quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C
  3.     Heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
  4.     All of the above
Answer: Option D
Explanation :