Question $2(6$ points$)$

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You are asked to design an electrostatic precipitator $($ESP$)$ tube to remove particles that are $1\mathrm{.}55m$ in diameter for $91\%$ efficiency. The flow rate is $0\mathrm{.}257\frac{m^3}{s},$ the collection field intensity is $102,000\frac{V}{m},$ the particle charge is $0\mathrm{.}325$ femtocoulombs $($fC$),$ and the gas temperature is $25C.$ The surface area of the ESP is nearly.

$7\mathrm{.}2m^2$

$5\mathrm{.}9m^2$

$4\mathrm{.}5m^2$

$8\mathrm{.}5m^2$