Powell $($Trans$.$ Inst. Chem. Eng. Lond., $13,175(1935)$; $18,36(1940)]$ evaporated water from the outside of cylinders into an airstream flowing parallel to the axes of the cylinders. The air temperature was $25\backslash$deg C$,$ and the total pressure standard atmospheric. The results are given by wl $23\mathrm{.}17$ x $10-\%($ul$)*$ Pu ~ Ba where w$=$ water evaporated, g$/$cm$?-$ s P$,=$ partial pressure of water in airstream, mmHg Py $=$ water$-$vapor pressure at surface temperature, mmHg u $=$ velocity of airstream, cm$/$s $?=$ length of cylinder, cm $($a$)$ Transform the equation into the form$\_$jp $=($Re$,),$ where Re$,$ is a Reynolds number based on the cylinder length. $($b$)$ Calculate the rate of sublimation from a cylinder of napthalene $0\mathrm{.}075$ m diam by $0\mathrm{.}60$ m long $(3$ in diam by $24$ in long$)$ into a stream of pure carbon dioxide at a velocity of $6$ m$/$s $(20$ ft$/$s$)$ at $1$ std atm, $100\backslash$deg C$.$ The vapor pressure of naphthalene at the surface temperature may be taken as $1330$ N$/$m$?(10$ mmHg$)$ and the diffusivity in carbon dioxide as $5\mathrm{.}15$ & $107$ m$/$s $(0\mathrm{.}0515$ cm$/$s$)$ at STP$.$ Express the results as kilograms naphthalene evaporated per hour. Ans.: $0\mathrm{.}386$ kg$/$h$.$