Online Chemical Engineering Test - Heat Transfer Test 2

Instruction:

  • This is a FREE online test. Beware of scammers who ask for money to attend this test.
  • Total number of questions: 20.
  • Time allotted: 30 minutes.
  • Each question carries 1 mark; there are no negative marks.
  • DO NOT refresh the page.
  • All the best!

Marks : 2/20


Total number of questions
20
Number of answered questions
0
Number of unanswered questions
20
Test Review : View answers and explanation for this test.

1.
Fourier's law applies to the heat transfer by
convection
radiation
conduction
all (a), (b) & (c)
Your Answer: Option
(Not Answered)
Correct Answer: Option

2.
With the increase of temperature, the Col-burn jH factor
increases.
decreases.
remains unchanged.
may increase or decrease ; depending on temperature.
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(Not Answered)
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3.
Pick out the wrong statement.
The controlling resistance in case of heating of air by condensing steam is in the air film.
The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature.
In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs.
Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature.
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(Not Answered)
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4.
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the
baffle spacing & shell diameter.
tube diameter & pitch.
viscosity, density & mass velocity of shell side fluid.
none of these.
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(Not Answered)
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5.
Film boiling is usually not desired in commercial equipments, because
the heat transfer rate is low in view of the large temperature drop.
it is difficult to maintain.
it is not economic.
none of these.
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(Not Answered)
Correct Answer: Option

6.
Pick out the wrong statement.
Heat transfer by radiation can not occur across an absolute volume.
In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles.
Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light.
The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same.
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(Not Answered)
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7.
A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
ellipse
straight line
parabola
circular arc
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(Not Answered)
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8.
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
α = 1; ε ≠ 1
α ≠ 1, ε = 1
α ≠ 1, ε ≠ 1
α = 1; ε = 1
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(Not Answered)
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9.
Choose the correct equation.
Nu = (Re) (Pr) (Gz)
Nu = (Re) (Pr) (St)
Nu = (Re)(Pr)
Nu = (Pr)(St)
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(Not Answered)
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10.
Electro-magnetic spectrum range, which is important for radiation varies from __________ microns.
1 to 100
0.5 to 50
10 to 100
100 to 1000
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(Not Answered)
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11.
The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is
2
1/2
4
1/4
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(Not Answered)
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12.
__________ paint has the minimum absorption co-efficient.
Black
White lead
Grey
Light cream
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(Not Answered)
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13.
Thermal conductivities of most of the liquids __________ with rise in temperature.
increases
decreases
remains unchanged
may increase or decrease; depends on the liquid
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14.
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the liquid is 1500 W/m2.°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be
15 min
22 min
44 min
51 min
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(Not Answered)
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15.
What is the emissivity of a black body ?
1
0.90
0.5
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(Not Answered)
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16.
Loss of heat from untagged steam pipe to the ambient air is by
conduction
convection
radiation
all (a), (b) & (c)
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(Not Answered)
Correct Answer: Option

17.
The unit of conductance in SI unit is
W/m
W/m2
W/°K
W/m°K
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(Not Answered)
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18.
In the free convection regime of pool boiling, the heat flux is proportional to
Δt1/2
Δt2
Δt5/4
Δt
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(Not Answered)
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19.
Low thermal conductivity of heat insulating materials is due to its
dense structure.
high proportion of air space.
high specific heat.
none of these.
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(Not Answered)
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20.
In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid
is inversely proportional to the resistance across which the drop occurs.
and the wall are proportional to individual resistances.
and the wall is not related.
none of these.
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(Not Answered)
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