Heat Transfer Questions and Answers – Lump System Analysis

This set of Heat Transfer Multiple Choice Questions & Answers (MCQs) focuses on “Lump System Analysis”.

1. According to lumped system analysis, solid possesses thermal conductivity that is
a) Infinitely large
b) Infinitely small
c) Moderate
d) 50% small
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2. The temperature and rate of heat conduction are undoubtedly dependent on
a) Time coordinates
b) Space coordinates
c) Mass coordinates
d) Both time and space coordinates
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3. Glass spheres of 2 mm radius and at 500 degree Celsius are to be cooled by exposing them to an air stream at 25 degree Celsius. Find the minimum time required for cooling to a temperature of 60 degree Celsius. Assume the following property values
Density = 2250 kg/m³
Specific heat = 850 J/kg K
Conductivity = 1.5 W/m K
a) 13.78 seconds
b) 14.78 seconds
c) 15.78 seconds
d) 16.78 seconds
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4. Which is true regarding lumped system analysis?
(i) Conductive resistance = 0
(ii) Convective resistance = 0
(iii) Thermal conductivity = 0
(iv) Thermal conductivity = infinity
Identify the correct statements
a) i and ii
b) i, ii and iv
c) i and iv
d) ii and iv
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5. Which of the following is an example of lump system analysis?
a) Heating or cooling of fine thermocouple wire due to change in ambient temperature
b) Heating of an ingot in an furnace
c) Cooling of bars
d) Cooling of metal billets in steel works
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6. What is the criterion for the applicability of lump system analysis?
a) Mean length
b) Normal length
c) Characteristics length
d) Mass no
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7. What is the value of characteristics length for cylinder?
a) R/5
b) R/4
c) R/3
d) R/2
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8. During heat treatment, cylindrical pieces of 25 mm diameter, 30 mm height and at 30 degree Celsius are placed in a furnace at 750 degree Celsius with convective coefficient 80 W/m² degree. Find the value of biot number if thermal conductivity is 40 W/m degree
a) 0.0082
b) 0.0072
c) 0.0062
d) 0.0052
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9. What is the value of characteristics length for sphere?
a) R/2
b) R/3
c) R/4
d) R/5
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10. What is the value of characteristics length for cube?
a) L/3
b) L/4
c) L/5
d) L/6
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Sanfoundry Global Education & Learning Series – Heat Transfer.

To practice all areas of Heat Transfer, here is complete set of 1000+ Multiple Choice Questions and Answers.

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