Apple slices dry in the falling-rate period from 65% to 10% dry-basis moisture. Equilibrium moisture is 2% dry basis and drying constant is $1/104\,\mathrm{min^{-1}}$. Find drying time in minutes, to two decimals.
The exponential falling-rate relation is $(M-M_e)/(M_0-M_e)=e^{-kt}$. Using consistent dry-basis percentages gives $e^{-t/104}=(10-2)/(65-2)=8/63$. Thus $t=104\ln(63/8)=214.62409$ min, rounded **214.62 min**. Equilibrium moisture must be subtracted from both moisture contents.
More Evaporation and Drying questions
GATE 2024 AG Q24– Which mechanisms explain the falling-rate drying period? Select all that apply.
GATE 2024 AG Q35– A single-effect evaporator concentrates9090 kg/hour herbal extract from 12% to 20% solids.…
GATE 2024 AG Q63– Mango pulp initially 25°C and 70% wet-basis moisture is dried to 10% wet basis using95°C…
GATE 2023 AG Q33– A fluidized carrot bed has minimum-fluidization height 1.20 m, diameter .60 m, carrot…
GATE 2022 AG Q32– A forward-feed triple-effect evaporator takes pineapple juice at 6.3 kg/s and produces 50%…
GATE 2022 AG Q33– An osmo-dehydrated fruit slice has 72% moisture on wet basis. Find moisture on dry basis…