Applied Thermodynamics-I

1. With increase in clearance volume, the ideal work of compressing 1 kg of air [ ]

(a) increase (b) decrease (c) remains same (d) first increase and then decrease

2. In reciprocating air compressors the clearance ratio is given by [ ]

(a) total volume of cylinder/clearance volume

(b) swept volume of cylinder/clearance volume

(c) clearance volume/ swept volume of cylinder

(d) clearance volume/ total volume of cylinder

3. With suction pressure being atmospheric, increase in delivery pressure with fixed clearance Volume [ ]

(a) increase volumetric efficiency

(b) decrease volumetric efficiency

(c) does not change volumetric efficiency

(d) slightly increase volumetric efficiency

4. Mechanical efficiency of reciprocating air compression is expressed as [ ]

(a) B.P/I.P (b) I.P/B.P (c) F.P/B.P (d) F.P/I.P

5. for the same overall pressure ratio, the leakage of air past the piston for multi stage compression as compared to single stage compression is

(a) more (b) less (c) constant (d) may be or less

6. In reciprocating air compression the method of controlling the quantity of air delivery is done by [ ]

(a) throttle control (b) blow off control (c) clearance control (d) all of the above

7. The efficiency of vane type of air compression as compared to roots air compression for the same pressure ratio is [ ]

(a) more (b) less (c) constant (d) may be or less

8. In centrifugal air compression the pressure developed depends on [ ]

(a) impeller tip velocity (b) inlet temperature

(c) compression index (d) all of the above

9. In a centrifugal air compression the pressure ratio is increase by [ ]

(a) increase the speed of impeller keeping its diameter fixed

(b) increase the diameter of the impeller keeping its speed constant

(c) reduces inlet temperature, keeping impeller its speed constant

(d) all of the above

10. Slip factor is the ratio of [ ]

(a) actual whirl component / ideal whirl component

(b) ideal whirl component /actual whirl component

(c) actual friction factors / ideal friction factors

(d) ideal friction factors /actual friction factors

Answers

1) c 2) c 3) b 4) b 5) b

6) d 7) a 8) d 9) d 10) a