DieselShip's Online Content Library

Q5. In a single acting two-stage reciprocating air compressor with negligible clearance, 30 m³ of air per minute are compressed through an overall pressure ratio of 16:1.

The initial pressure and temperature are 1 bar and 27ºC respectively.

The pressure ratio in each stage is the same.

The polytropic index for each compression process is 1.35.

Inter-cooling is perfect and the mechanical efficiency of the compressor is 0.92.

(a) Sketch the process on a p-V diagram indicating the work saved by inter-cooling.

(b) Calculate EACH of the following:

(i) The power input to the compressor

(ii) The heat transfer in the inter-cooler

(iii) The heat transfer to the jacket cooling during compression.

Note: For air R = 0.287 kJ/kgK; C_v = 0.718 kJ/kg K