Related Questions

An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture?
A Cork
B Saw dust
C Sand
D Chemically prepared foam
Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity?
A CO2
B N2
C O2
D CO
A steam carraying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will
A Increase
B Decrease
C Remain unaffected
D May increase or decrease; depends on the thickness of each layer
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
A Decreases
B Increases
C Remains unchanged
D Increases exponentially
A steam pipe is to be lined with two layers of insulating materials of different thermal conductivities. For the minimum heat transfer,
A The better insulation must be put inside
B The better insulation must be put outside
C One could place either insulation on either side
D One should take into account the steam temperature before deciding as to which insulation is put where
A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place
A The better insulation material should be put just next to pipe (i.e., inside)
B The better insulating material should be put outside
C Either of the insulating material could be put on either side
D Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)
Which of the following insulating materials was suitable for low temperature applications?
A Asbestos paper
B Diatomaceous earth
C 80 percent magnesia
D Cork
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
A $$\frac{1}{{\text{k}}}$$
B k
C k2
D $$\frac{1}{{{{\text{k}}^2}}}$$
Which of the following commonly used condenser tube materials has the lowest thermal conductivity?
A Admirability brass
B Stainless steel
C Aluminium brass
D Titanium
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

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