$2\mathrm{.}19$c$.$ Benzene evaporation on the outside surface of a single cylinder

Benzene is evaporating at $20k\frac{g}{h}$ over the surface of a porous $10-cm-$diameter cylinder. Dry air at $325K$ and $1$atm flows at right angle to the axis of the cylinder at a velocity of $2\frac{m}{s}.$ The liquid is at a temperature of $315K$ where it exerts a vapor pressure of $26\mathrm{.}7$kPa. Estimate the length of the cylinder. For benzene, $T_c=562\mathrm{.}2K,P_c=\frac{48\mathrm{.}9}{b}ar,M=78,V_c=259c\frac{m^3}{m}ol,$ and $Z_c=0\mathrm{.}271($Reid et al$.,1987).$

Answer: $1\mathrm{.}74m$