Mass Transfer
Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10⁻³ kg mole/m².s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m² .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is

5.6 x 10⁻⁴
8.5 x 10⁻⁴
5.6 x 10⁻³
8.5 x 10⁻³

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Mass Transfer
An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii)

Less number of trays are required
More number of trays are required but the residue composition remains unchanged
More number of trays are required and the residue composition is more dilute in methanol
Composition of the residue remains unchanged

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Mass Transfer
A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is

1500
2000
1000
2500

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