Question

A desktop computer is to be cooled by a fan whose flow rate is 0.34 m3/min. Determine the mass flow rate of air through the fan at an elevation of 3400 m where the air density is 0.7 kg/m3. Also, if the average velocity of air is not to exceed 103 m/min, determine the diameter of the casing of the fan.

Answer 1

Answer:65 mm

Explanation:

Given

Flow rate $\dot{V}=0.34\ m^3/min$

density of air $\rho =0.7\ kg/m^3$

average velocity of air $v_{avg}=103\ m/min$

Mass flow rate is given by

$\dot{m}=\rho \times \dot{V}$

$\dot{m}=0.7\times 0.34$

$\dot{m}=0.238\ kg/min$

And Flow rate can be written as

$\dot{V}=A\cdot v_{avg}$

Where A =Area of cross-section

$0.34=\frac{\pi}{4}d^2\cdot v_{avg}$

$0.34=\frac{\pi}{4}\times d^2\times 103$

$d=0.0648\ m$

$d=64.8\approx 65\ mm$