Deying question

3. A sample of porous, manufactured sheet material was dried from hoth sides by cross-circulation drymg. Ihe sample aas 03 mi square and 6 mm thick, and the edges were sealed. The air velocity over the surface is 3m/s, its dry bulb temperatune was 52 d. and wet bulb temperature 21 . C. The solid lost moasture at a constant rate of 7.510kg/s until critical mousture content 15 o (wet basis) was reached In the fallang rate period, rate of evaporation fell linearly with moisture content until the sample was dry. The cquiliorium moisture is negligible. The dry meight of the sheet is 1.8kg. Eatent heat of vaporization of moisture is 2435kJ/kg density of gas 1.2kg/m. Assume heat transfer by conduction and radiation is negligible. Estimate the time of drying sheets of this material 0.6 by 1,2m by 12mm thick from both sides from 25 to 24 moisfure (wet basis) using air of dry bulb 66C of the same absolule huaidity (27 c wet balb temperature) at a linear velocity over the sheet of 5 mis. Assume no change in critical moisture content with the changed drying conditions