A tunnel drier is used for drying a filtered cake of amino acid crystals for $2$ hours using air at $28C.$ The dimensions of the drying cake are diameter $75cm$ and thickness $5mm.$

The original crystal solids contained $24\%($w$/$w$)$ of moisture measured on a wet basis. The critical moisture content of the crystals is $15\%$ wet basis and the density of completely dried material is $1380kg{m}^{-3}.$

The heat transfer coefficient for gas$-$phase heat transfer to the surface of the crystals is $34J{s}^{-1}{m}^{-2\text{@}}{C}^{-1}.$ For the final product, the temperature at the wet crystal surface is $24C$ and the crystal equilibrium moisture content is $7\mathrm{.}5\%,$ dry basis.

a$)$ What is the drying rate?

$[8\%]$

b$)$ What is the moisture content of the dried crystals?

$[7\%]$

$($Steam table is provided in the Appendix$)$I$\text{'}$m