Mass Transfer

291.It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).

1. 15 min
2. 51 min
3. 71 min
4. 94 min

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292.JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by

1. N_sh = 2
2. N_st = 2
3. N_sc = 2
4. None of these

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293.Laboratory determination of the diffusivity of vapor is done by _________ method.

1. Wetted wall column
2. Gilliland's
3. Winkelmann's
4. Wike's

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294.Langmuir equation is associated with

1. Leaching
2. Adsorption
3. Steam distillation
4. Multi-component absorption

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295.Large quantity of silica gel is normally dried in a _________ dryer.

1. Freeze
2. Through circulation
3. Rotary vacuum
4. Tray

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296.Large scale drying of sugar is done in a _________ dryer.

1. Spouted bed
2. Tray
3. Rotary
4. Truck

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297.Large scale drying of wheat is done in a _________ dryer.

1. Fluidised bed
2. Spouted bed
3. Tray
4. Vacuum rotary

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298.Large scale usage of flash distillation is practised in

1. Soap manufacturing
2. Ammonia synthesis plant
3. Polymerisation industry
4. Petroleum refining

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299.Leaching of coarse solid lumps is also termed as

1. Decoction
2. Dissolution
3. Percolation
4. Agitation and settling

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300.Leaching of coffee from coffee beans is done by

1. Hot water
2. Hexane
3. Lime water
4. Dilute H₂SO₄ (hot)

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