Question Paper: Mechanical Utility Systems Question Paper - December 2016 - Mechanical Engineering (Semester 7) - Mumbai University (MU)
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## Mechanical Utility Systems - December 2016

### MU Mechanical Engineering (Semester 7)

Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

### Solve any four Q1 (a,b,c,d,e)

1(a) Difference between centrifugal compressor and axial compressor. 5 marks

1(b) Explain Screw pump with neat diagram 5 marks

1(c) Define following terms for reciprocating compressors.
1) Mechanical efficiency
2) Indicated power
3) Volumetric efficiency
4) Free Air Deliverry
5 marks

1(d) A single-acting. Single-cylinder reciprocating air compressor is compressing 20 kg/min of air from 110kPa, 30°C to 600 kPa and delivers. It to a receiver. Law of comparision is pV125=constant Mechanical efficiency is 80%. Find the power input to compressor, neglecting losses due to clearance, leakages and cooling. 5 marks

1(e) Write a note on leak detection in compressed air network 5 marks

2(a) Explain construction and working of single-stage, double-acting reciprocating air compressor with neat labelled diagram. 5 marks

2(b) A double-acting reciprocating pump. Running at 40 rpm, is discharging 1m 3 of water per minute The pump has a stoke of 400 mm. The diameter of piston is 200 mm. The delivery and suction head are 20 m and 5 m respectively. Find the slip of the pump and power required to drive the pump. 5 marks

3(a) Explain consruction and working of axial compressor with neat diagram. 5 marks

3(b) A single-stage centrifugal pump with impeller diameter of 30 cm rotates at 2000 rpm and lifts 3m 3 of water per second to a height of 30 m with an effciency of 75%. Find the number of stages and diameter of each impeller of a similar multistage pump to lift 5m 3 of water per second to a height of 200 m when rotating at 1500 rpm. 5 marks

4(a) What is cavitation? State the effects of cavitation and what precautions should be taken against cavitation. 5 marks

4(b) A two-stage, single-acting reciprocating air compressor takes in air 1 bar and 300 K. Air is discharged at 10 bar. The intermediate pressure is ideal for minimum work and perfect inter-cooling. The law of compression is pV -3 = constant The rate of discharge is 0.1 kg/s
Calculate
1) Power required to drive the compressor.
2) Saving in work in compression with single stage compression.
3) Isothermal efficiency
4) Heat transferred in intercooler Take R = 0.287 kJ/kg K and Cp = 1kJ/kg K.
5 marks

5(a) Write down the energy conservation opportunities in pumping system. 5 marks

5(b) An axial- flow compressor has a constant axial velocity of 150 m/s and 50% reaction The mean diameter of blade ring is 35 cm and speed is 15,000 rpm. The exit angle of blade is 27°. Calculate blade angle at inlet and work done per kg of air. 5 marks

5(c) The internal and external diameters of a centrifugal pump are 200 mm and 400 mm resp. The pump is running at 1200 rpm. The vane angles of the impeller at inlet and outlet are 20° and 30° resp. The water enters the impeller radially and velocity of flow is constant Determine the work done by he impeller per unit weight of water. 5 marks

### Write short note on following any four Q6.(a,b,c,d,e)

6(a) Trouble shooting in centrifugal pump 5 marks

6(b) Model testing of centrifugal pump. 5 marks

6(c) Diffuser system in centrifugal compressor 5 marks

6(d) Losses in axial compressor 5 marks

6(e) Applications of compressed air in industry 5 marks

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