D4817 Pages: 2

accelerationheads and the friction head, f = 0.02. Sketch the indicator diagram.
The suction and deliveryheads from atmosphere are 4 m and 16 m respectively.
a) What is an air vessel? Describeits functions. (4) b) Show that in a double acting pump
the work saved by fitting air vesselsis about (6) 39.2%.
PART C

Answer any three questions, each carries 10 marks
a) What is clearance ratio? Write the effect of clearance volume on the performance (4)
of an air compressor.

b) Derive the volumetric efficiency of a reciprocating compressor considering (6) clearance

10

11

12

13

14

volume.

A single acting reciprocating compressor has bore of 25cm and a stroke of 35cm. (10)
The compressor runs at 650rpm. The clearance volume is 4% of swept volume. The index
of expansion and compression is 1.3. The suction conditions are 0.95 bar and 25°C. The
delivery pressure is 6 bar. The atmospheric pressure and temperature are 1.013 bar and
20°C. Determine:

i) FAD ii) Volumetric efficiency iii) Indicated power input.

Derive the condition for minimum work required for a 2-stage reciprocating air (10)
compressor.

Explain the principle of operation, construction and working of a centrifugal (10)
compressor with necessary sketches.

A centrifugal compressor running at 1500rpm has internal and external diameters (10) of
the impellers are 250mm and 500mm respectively the air enters the impeller radially.
Determine the work done by the compressor per kg of air and degrees of reaction.

a) Explain the working of diffuser in a centrifugal compressor. (4) b) Explain the
working of roots blower. (6)

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