Heat Transfer Radiation Chemical Engineering MCQ - Set 26 - ObjectiveBooks

Heat Transfer Radiation Chemical Engineering MCQ - Set 26

Practice Test: Question Set - 26

1. In which mode of heat transfer, the Biot number is important?
    (A) Transient heat conduction
    (B) Natural convection
    (C) Forced convection
    (D) Radiation

2. The actual temperature drop across the heating surface in an evaporator depends on the
    (A) Feed
    (B) Depth of liquid over heating surface
    (C) Pressure difference between steam chest and vapor space
    (D) All (a), (b) and (c)

3. A diathermanous substance __________ the thermal radiation completely.
    (A) Absorbs
    (B) Reflects
    (C) Transmits
    (D) None of these

4. Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
    (A) Surrounding temperature
    (B) Average temperature of the fin
    (C) Temperature of the fin end
    (D) Constant temperature equal to that of the base

5. Boiling point elevation of a solution of NaOH
    (A) Increases rapidly with temperature rise
    (B) Is almost independent of temperature
    (C) Is almost independent of pressure
    (D) Both (b) and (c)

6. Thermal conductivity of a conducting solid material depends upon its
    (A) Temperature
    (B) Porosity
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

7. Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.)
    (A) √d
    (B) d
    (C) d2
    (D) d1.5

8. Pick out the wrong statement.
    (A) Reciprocal of the resistance to heat flow is called thermal conductance
    (B) Unit of thermal conductance is W/°K
    (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A
    (D) None of these

9. Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the
    (A) Maximum resistance in the series
    (B) Sum of all resistances
    (C) Average of all resistances
    (D) Minimum resistance presents in the series

10. When vaporization takes place directly at the heating surface, it is called
    (A) Film boiling
    (B) Nucleate boiling
    (C) Vapor binding
    (D) None of these

11. Prandtl and Reynolds analogy are same, when Prandtl number is
    (A) 0.5
    (B) 1
    (C) > 2
    (D) 1.5

12. As per Kirchoff’s law, the ratio of the total radiating power to the absorptivity of a body depends on the
    (A) Temperature of the body only
    (B) Wavelength of monochromatic radiation
    (C) Both (a) and (b)
    (D) Nature of material of body

13. Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is
    (A) Thin walled having the value of Ao Ai/< 2
    (B) Thick walled
    (C) Having the value of Ao/Ai > 2
    (D) Both (b) and (c)

14. Fourier's law applies to the heat transfer by
    (A) Convection
    (B) Radiation
    (C) Conduction
    (D) All (a), (b) & (c)

15. jH factor for heat transfer is not a function of the __________ number.
    (A) Reynolds
    (B) Nusselt
    (C) Grashoff
    (D) Both (b) & (c)

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