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For the following questions answer them individually
Provision of fins on a given heat transfer surface will be more if there are _____.
Fewer number of thin fins
Fewer number of thick fins
Large number of thick fins
Large number of thin fins
Which of the following would lead to a reduction in thermal resistance?
In conduction, reduction in the thickness of the material and an increase in the thermal conductivity.
In convection, stirring of the fluid and cleaning the heating surface
In radiation, increasing the temperature and reducing the emissivity
All options are correct
Inspite of large heat transfer coefficients in boiling liquids, fins are used advantageously when the entire surface is exposed to _____.
All modes of boiling
The parameter(s) responsible for loss of heat from a hot pipe surface in a room without fans would include _____.
Temperature of the surface and air in the room
Emissivity of the surface Question
Length and diameter of the pipe
The figure given below shows the variation of temperature across the thickness of materials with different thermal conductivities under steady states. Curve C will be the applicable when thermal conductivity of the material ____
increases with increase in temperature
decreases with increase in temperature
is very large
is constant at all temperatures
On a summer day, a scooter rider feels more comfortable while on the move than while at a stop light because _____.
An object in motion captures less solar radiation
Air is transparent to radiation and hence it is cooler than the body
More heat is lost by convection and radiation while in motion
Air has a low specific heat and hence it is cooler
In radiative heat transfer, a gray surface is one _____.
Which appears gray to the eye
Whose emissivity is independent of wavelength
Which has reflectivity equal to zero
Which appears equally bright from all directions
The property of a working substance, which increases or decreases according to the heat supplied or removed in a reversible manner, is called _____.
None of these
Triple point _____.
Occurs in a mixture of two or more gases
Is the point, where three phases exists together
Occurs in sublimation
Non quasistatic process is _____.
Free expansion of gas
Expansion of a gas in a cylinder under constant pressure
Rapid compression of a gas in a cylinder
Gradual compression of a gas in a cylinder
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