Answer to Question #256385 in Mechanical Engineering for Gani

Question

One stage of a cascade impactor designed to operate at 1.0 ft/min at standard conditions has a cutoff diameter of 5 um. What will be the cutoff diameter for this stage if it is operated at 300°F, but flow is measured at 1.0 ft/min after the gas has cooled to standard conditions? 

Answer 1

initial speed = 1.0 ft/min

cutoff diameter = 5 um

T₂ = 300K

flow speed after cooling = 1.0 ft/min

Since the flow speed is not affected by cooling, only flow speed affects the cut off diameter

300 K = 5 um

273 K = ?

flow speed after cooling = $\dfrac{5×273}{300}$ = 4.8 um$.$