MCQ on Radiation Heat Transfer - Set 19 - ObjectiveBooks
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MCQ on Radiation Heat Transfer - Set 19

Practice Test: Question Set - 19


1. In the equation Q = UAΔt; Δt is
    (A) Geometric mean temperature difference
    (B) Arithmetic mean temperature difference
    (C) Logarithmic mean temperature difference
    (D) The difference of average bulk temperatures of hot and cold fluids

2. Convective heat transfer, in which heat is transferred by movement of warmed matter is described by
    (A) Fourier's law
    (B) Newton's law of cooling
    (C) Fick's law
    (D) None of these

3. For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in
    (A) Increased economy
    (B) Decreased economy
    (C) Lower capacity
    (D) No effect on economy

4. Which of the following has the minimum absorptivity?
    (A) Aluminium foil
    (B) Coal dust
    (C) Refractory bricks
    (D) Iron plates

5. Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately
    (A) 32
    (B) 37
    (C) 45
    (D) 50

6. In a forward feed multiple effect, the pressure build up will be
    (A) Least at the inlet of the first effect
    (B) Least at the outlet of the last effect
    (C) Highest at the inlet of the last effect
    (D) Highest at the outlet of the last effect

7. Graetz number is given by
    (A) mCp/kL
    (B) kL/mCp
    (C) mCp/
    (D) /mCp

8. Thermal diffusivity is given by
    (A) k/ρCp
    (B) ρCp/k
    (C) µCp/a
    (D) µ/hCp

9. The rate of heat transfer is a product of overall heat transfer co-efficient, the difference in temperature and the
    (A) Heating volume
    (B) Heat transfer area
    (C) Nusselt number
    (D) None of these

10. Reynold's analogy states that
    (A) Nst α f
    (B) Nst α NRe
    (C) NNu α f
    (D) NRe α f

11. In case of a vertical tube evaporator, with increase in the liquor level, the
    (A) Capacity of the evaporator is decreased
    (B) Capacity of the evaporator is increased
    (C) True temperature drop increases
    (D) Both (b) and (c)

12. Which of the following has the minimum thermal conductivity?
    (A) Nitrogen
    (B) Steel
    (C) Carbon black
    (D) Tar

13. Low thermal conductivity of heat insulating materials is due to its
    (A) Dense structure
    (B) High proportion of air space
    (C) High specific heat
    (D) None of these

14. For an ideal black body
    (A) Absorptivity = 1
    (B) Reflectivity = 1
    (C) Emissivity = 0
    (D) Transmissivity = 1

15. In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always
    (A) < 1
    (B) > 1
    (C) 1
    (D) 

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