Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 3 (Q.No. 13)
13.
With increase in temperature, the thermal conductivity of steel
Discussion:
3 comments Page 1 of 1.
Amit said:
8 years ago
Sequence of Decreasing Thermal Conductivity:
Pure Metal -Alloy -Liquid - Gases.
Pure Metal -Alloy -Liquid - Gases.
(1)
Akshay said:
8 years ago
The Answer should be A.
(1)
SONI said:
9 years ago
Thermal conductivity of any material is dependent on two things:
i. Motion of free electrons.
ii. Molecular vibrations.
For metals, the thermal conductivity is mainly a function of the motion of free electrons. As the temperature increases, the molecular vibrations increase (in turn decreasing the mean free path of molecules). So, they obstruct the flow of free electrons, thus reducing the conductivity.
In the case of non-metals, there are no free electrons. So, only the molecular vibrations are responsible for conduction of heat and hence for non-metals the conductivity increases with increase in temperature.
i. Motion of free electrons.
ii. Molecular vibrations.
For metals, the thermal conductivity is mainly a function of the motion of free electrons. As the temperature increases, the molecular vibrations increase (in turn decreasing the mean free path of molecules). So, they obstruct the flow of free electrons, thus reducing the conductivity.
In the case of non-metals, there are no free electrons. So, only the molecular vibrations are responsible for conduction of heat and hence for non-metals the conductivity increases with increase in temperature.
(2)
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