Chemical Heat Transfer Mcqs - Set 15

1)   Prandtl and Reynold’s analogies are identical for Prandtl number value of__________________?

a. 0
b. 0.5
c. 1
d. 5
Answer  Explanation 

ANSWER: 1

Explanation:
No explanation is available for this question!


2)   Baffles are provided in heat exchangers to increase the________________?

a. Fouling factor
b. Heat transfer area
c. Heat transfer co-efficient
d. Heat transfer rate
Answer  Explanation 

ANSWER: Heat transfer co-efficient

Explanation:
No explanation is available for this question!


3)   _______________ paint has the maximum absorption coefficient ?

a. Black
b. Yellow
c. White
d. Grey
Answer  Explanation 

ANSWER: Black

Explanation:
No explanation is available for this question!


4)   Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low___________________?

a. Hardness
b. Dissolved solids content
c. Suspended solids content
d. All A., B. and C.
Answer  Explanation 

ANSWER: All A., B. and C.

Explanation:
No explanation is available for this question!


5)   Crystallisation of solids from a homogeneous solution is a/an ______________ process?

a. Exothermic
b. Mildly endothermic
c. Highly endothermic
d. None of these
Answer  Explanation 

ANSWER: Exothermic

Explanation:
No explanation is available for this question!


6)   Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?

a. Aluminium foil
b. Refractory bricks
c. Iron plate
d. Coke breeze
Answer  Explanation 

ANSWER: Coke breeze

Explanation:
No explanation is available for this question!


7)   The energy radiated from a surface Q at absolute temperature T is related as__________________?

a. Q ∝ T2
b. Q ∝ T4
c. Q ∝ T3
d. None of these
Answer  Explanation 

ANSWER: Q ∝ T4

Explanation:
No explanation is available for this question!


8)   Removal of ______________ heat is involved in the condensation of a vapor under saturated conditions?

a. Super
b. Sensible
c. Latent
d. Both B. & C.
Answer  Explanation 

ANSWER: Sensible

Explanation:
No explanation is available for this question!


9)   The purpose of providing a ‘catchall’ in the vapor line of an evaporator is to__________________?

a. Create vacuum
b. Regulate the vapor flow
c. Vent the non-condensable gases
d. Arrest the entrained liquid
Answer  Explanation 

ANSWER: Arrest the entrained liquid

Explanation:
No explanation is available for this question!


10)   Thermal conductivities of most of the liquids _______________ with rise in temperature?

a. Increases
b. Decreases
c. Remains unchanged
d. May increase or decrease; depends on the liquid
Answer  Explanation 

ANSWER: Decreases

Explanation:
No explanation is available for this question!


11)   Evaporation of 1kg of water from a solution in a single effect evaporator requires about ________________ kg of steam?

a. 0.4 – 0.6
b. 1-1.3
c. 1.8-2
d. 2 – 2.4
Answer  Explanation 

ANSWER: 1-1.3

Explanation:
No explanation is available for this question!


12)   _____________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side?

a. Single pass, fixed tube sheet
b. U-tube
c. Three pass, fixed tube sheet
d. None of these
Answer  Explanation 

ANSWER: U-tube

Explanation:
No explanation is available for this question!


13)   Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by__________________?

a. Eddies current
b. Conduction
c. Convection
d. None of these
Answer  Explanation 

ANSWER: Conduction

Explanation:
No explanation is available for this question!


14)   For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then__________________?

a. hf = hd
b. hf > hd
c. hf < hd
d. hf could be greater or smaller than hd
Answer  Explanation 

ANSWER: hf < hd

Explanation:
No explanation is available for this question!


15)   Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?

a. Dittus-Boelter equation
b. Sieder-Tate equation
c. Nusselt equation
d. None of these
Answer  Explanation 

ANSWER: Sieder-Tate equation

Explanation:
No explanation is available for this question!


16)   Baffle spacing ____________________?

a. Is not the same as baffle pitch
b. Should be less than one fifth the diameter of the shell
c. Should be less than the inside diameter of the shell
d. None of these
Answer  Explanation 

ANSWER: Should be less than the inside diameter of the shell

Explanation:
No explanation is available for this question!


17)   Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around ______________ BTU?

a. 180
b. 970
c. 3.97
d. None of these
Answer  Explanation 

ANSWER: 180

Explanation:
No explanation is available for this question!


18)   In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell) ?

a. 0.25 D
b. 0.50 D
c. 0.75 D
d. None of these
Answer  Explanation 

ANSWER: 0.75 D

Explanation:
No explanation is available for this question!


19)   A 2-4 heat exchanger involves__________________?

a. Only counter-flow of fluids
b. Only parallel-flow of fluids
c. Both counter and parallel-flow of the fluids
d. Smaller pressure drop compared to 1-2 exchanger
Answer  Explanation 

ANSWER: Both counter and parallel-flow of the fluids

Explanation:
No explanation is available for this question!


20)   In a heat exchanger, one transfer unit means___________________?

a. A section of the exchanger in which change in temperature of one stream equals the average driving force in the section
b. The size of the exchanger in which heat transfer rate is 1 kcal/hr
c. Both A. and B.
d. None of these
Answer  Explanation 

ANSWER: A section of the exchanger in which change in temperature of one stream equals the average driving force in the section

Explanation:
No explanation is available for this question!


21)   jH factor for heat transfer is not a function of the _______________ number?

a. Reynolds
b. Nusselt
c. Grashoff
d. Both B. & C.
Answer  Explanation 

ANSWER: Both B. & C.

Explanation:
No explanation is available for this question!


22)   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.
Answer  Explanation 

ANSWER: Thin walled having the value of Ao Ai/< 2

Explanation:
No explanation is available for this question!


23)   Prandtl and Reynolds analogy are same, when Prandtl number is____________________?

a. 0.5
b. 1
c. > 2
d. 1.5
Answer  Explanation 

ANSWER: 1

Explanation:
No explanation is available for this question!


24)   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
Answer  Explanation 

ANSWER: Sum of all resistances

Explanation:
No explanation is available for this question!


25)   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
Answer  Explanation 

ANSWER: d2

Explanation:
No explanation is available for this question!


26)   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
Answer  Explanation 

ANSWER: Both B. and C

Explanation:
No explanation is available for this question!


27)   A diathermanous substance _______________ the thermal radiation completely?

a. Absorbs
b. Reflects
c. Transmits
d. None of these
Answer  Explanation 

ANSWER: Transmits

Explanation:
No explanation is available for this question!


28)   In which mode of heat transfer, the Biot number is important ?

a. Transient heat conduction
b. Natural convection
c. Forced convection
d. Radiation
Answer  Explanation 

ANSWER: Transient heat conduction

Explanation:
No explanation is available for this question!


29)   Among liquids, water has a comparatively high value of thermal conductivity, due to its__________________?

a. Low density
b. High viscosity
c. Partial ionisation
d. Dense structure
Answer  Explanation 

ANSWER: Partial ionisation

Explanation:
No explanation is available for this question!


30)   The statement that “maximum wavelength of radiation is inversely proportional to the temperature” is ______________ law?

a. Stefan-Boltzmann’s
b. Planck’s
c. Wien’s displacement
d. None of these
Answer  Explanation 

ANSWER: Wien’s displacement

Explanation:
No explanation is available for this question!