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Mechanical Engineering · Q134

Heat And Mass Transfer

Engineering and GATE · Mechanical Engineering · question 134

Q134

The thermal diffusivities for gases are generally

A.
More than those for liquids
Answer
B.
Less than those for liquids
C.
More than those for solids
D.
Dependent on the viscosity

Answer: Option A

Solution

Answer: Option A
Solution:
The thermal diffusivities for gases are generally More than those for liquids
the thermal conductivity of the liquid is more the gases thermal diffusivity also depends on density and heat capacity. Which is very small in terms of gases. That's why air has low thermal conductivity but relatively high thermal diffusivity that is 0.19 and water has 0.014.