Practice Test: Question Set - 14
1. Planck's distribution law is valid for __________ bodies.
- (A) Black
- (B) White
- (C) Colored
- (D) All (a), (b) & (c)
2. Electro-magnetic spectrum range, which is important for radiation varies from __________ microns.
- (A) 1 to 100
- (B) 0.5 to 50
- (C) 10 to 100
- (D) 100 to 1000
3. In a shell and tube heat exchanger, square pitch compared to triangular pitch
- (A) Gives a higher shell side pressure drop
- (B) Gives a lower shell side pressure drop
- (C) Can pack more surface area into a shell of given diameter
- (D) None of these
4. A body cools down from 75°C to 70°C in 10 minutes. It will cool down from 70° C to 65° C in __________ minutes.
- (A) 10
- (B) > 10
- (C) < 10
- (D) Either (b) or (c), depends on the mass of the body
5. In a gas-liquid shell and tube heat exchanger, the
- (A) Presence of a non-condensable gas decreases the condensing film
co-efficient
- (B) Gases under high pressure are routed through the
tube side, because high pressure gases are corrosive in nature
- (C) Gases to be heated/cooled is normally routed through the shell side,
because the corrosion caused by the cooling water or steam condensate remain
localized to the tubes
- (D) All 'a', 'b' & 'c'
6. For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it
- (A) Occupies smaller space
- (B) Is more economical
- (C) Is easy to operate and maintain
- (D) All (a), (b) and (c)
7. Terminal point temperature differences between fluids in case of a heat exchanger is termed as
- (A) Approach
- (B) Log mean temperature difference
- (C) Arithmetic mean temperature difference
- (D) Geometric mean temperature difference
8. The Stefan-Boltzmann constant depends on the
- (A) Medium
- (B) Temperature
- (C) Surface
- (D) None of these
9. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when
- (A) CPA > CPB
- (B) CPA < CPB
- (C) kA < 0.5 kB
- (D) kA >2 kB
10. In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used
- (A) In low range of temperature differences
- (B) In high range of temperature differences
- (C) Because of its low cost
- (D) To prevent corrosion of the tube bundles
11. Overall heat transfer co-efficient of a particular tube is U1. If the same tube with some dirt deposited on either side has coefficient U2, then
- (A) U1 = U2
- (B) U2 > U1
- (C) U1 > U2
- (D) U1 = dirt factor - U2
12. In forced convection, the Nusselt number is a function of
- (A) Re and Pr
- (B) Re and Gr
- (C) Pr and Gr
- (D) Re and Sc
13. Maximum heat transfer rate is achieved in __________ flow.
- (A) Co-current
- (B) Counter-current
- (C) Turbulent
- (D) Laminar
14. Radiator of an automobile engine is a __________ type of heat exchanger.
- (A) Co-current
- (B) Cross-current
- (C) Counter-current
- (D) Direct contact
15. Temperature profile in steady state heat transfer is
- (A) Asymptotic
- (B) Hyperbolic
- (C) Parabolic
- (D) Linear
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