Question Paper: Mass Transfer Operation - 1 : Question Paper Dec 2015 - Chemical Engineering (Semester 5) | Mumbai University (MU)
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Mass Transfer Operation - 1 - Dec 2015

Chemical Engineering (Semester 5)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
1(a) Nickel carbonyl (B) is to be produced by passing Carbon monoxide (A) through a bed of nickel spheres. Find $$\dfrac{N_A}{N_A+N_B}$$
Ni+4CO = Ni(CO)4
(2 marks)
1(b) Derive the equation for adiabatic saturation temperature.(8 marks) 1(c) Estimate the diffusivity of benzene in toluene and toluene in benzene at 110°C. The physical properties are as follows :

 Component M Boiling point 0C VA at B.P. cm3/ mol μ at 110 0C Cp Benzene 78.11 80.1 86.5 0.24 Toluene 92.13 110.6 118.3 0.26
(10 marks) 2(a) The air pressure in a tyre reduces from 2 bars to 1.99 bars in five days. The volume of air in the tube=0.0253, the surface area 0.5m3 and wall thickness 0.01 metre. The solubility of air in rubber is 0.07 m3/m3. Estimate the diffusivity of air in rubber.(10 marks) 2(b) Derive relation between individual and overall mass transfer coefficient when
(i) Gas phase resistance is controlling
(ii) Liquid phase resistance is controlling
(10 marks)
3(a) An ammonia air mixture containing 2% by volume ammonia is to be scrubbed with water at 10°C in a tower packed with 1.27 cm Ranching rings. The water and gas rates are 1) 70 kg/hr m2 each, based on empty tower cross selection. Estimate the height of tower required if 98% of ammonia in the entering gas is to be absorbed. The tower operates at 1 atm pressure. The equilibrium relation is given by the following equation.
Ye =0.74x
Ye= mole fraction of ammonia in air
X= Mole fraction of ammonia in solution with water.
the height of transfer unit may be taken as equal to z meter.
(12 marks)
3(b) Compare packed tower with tray tower.(8 marks) 4(a) It is desired to dry a certain type of fibre board in sheets 0.131 meter by 0.162 meter by 0.071 meter from 58% to 5% moisture (wet basis) content. Initially from laboratory test data with this fibre board, the rate of dying at constant rate period wad found to be 8.9 kg/m2hr. The critical moisture content was 24.9% and the equilibrium moisture content was 1%. The fiber board is to be dried from one side only and has a bone-dry density of 210kg/m3. Determine the times required for drying. The falling rate may be assumed linear.(10 marks)

Write short note on :-

4(b)(i) Drum dryer(5 marks) 4(b)(ii) Tray dryer(5 marks) 5(a) Give classification of cooling tower. Explain mechanical draft cooling tower in detail.(10 marks) 5(b) Explain loading and flooding in packed column.(5 marks) 5(c) Write short note on welted wall column.(5 marks)

Write short note on any four.

6(a) Humid heat(5 marks) 6(b) Venture scrubber(5 marks) 6(c) Fisk's first law of diffusion(5 marks) 6(d) Diffusion through polymers(5 marks) 6(e) Absorption factor and striping factor.(5 marks)