8/13/2019 Tutorial Examples in Reciprocating Compressors

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TUTORIAL EXAMPLES in RECIPROCATING COMPRESSORS

(SSL conditions: 15C ; 101.325 kPa)

1. A reciprocating air compressor induces 5.65 x 10-3m of air per cycle at SSL

conditions. If the delivery pressure is 620 kPa, calculate the work transfer per cycle ifthe compression and expansion processes are:-

(a) reversible polytropic, n = 1.2.

(b) reversible adiabatic. [1.210, 1.359 kJ]

Solution:Recips/recip comp 1.PDF

2. Air is to be compressed through a pressure ratio of 10:1 from SSL conditions.

Find the power required for a free air delivery (FAD) of 0.05 m /s.

Also find the rotational speed if the swept volume is 14.5 x 10-3m.

The clearance volume is 6 per cent of the swept volume, and n = 1.3 for compressionand expansion. [15.2 kW, 293 RPM]

Solution:Recips/recip comp 2.PDF

3. Air is compressed in a reciprocating compressor from SSL conditions to a pressureof 0.9 MPa in one stage. The polytropic index of compression and expansion is 1.3,

and the clearance volume is 4 per cent of the swept volume. Calculate the worktransfer per kg of air delivered and the heat transfer during compression andexpansion per kg of air delivered. [ 234.7 kJ/kg, -58.7 kJ/kg del., 12.1 kJ/kg del.]

Solution:Recips/recip comp 3.PDF

4. A single acting reciprocating compressor running at 240 RPM delivers 0.1 m/s FAD.Inlet conditions are SSL and the delivery pressure is 482 kPa. The clearance volume is5 per cent of the swept volume and the compression and re-expansion processes areconsidered reversible and governed by the law pV1.2= const. Calculate:

(a) the swept volume;

(b) the power required to drive the compressor if its mechanical efficiency is 85%;

(c) the maximum pressure against which the compressor could theoretically operate.[0.0288 m , 21.2 kW, 3.86 MPa]

Solution:Recips/recip comp 4.PDF

http://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_1.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_1.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_1.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_2.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_2.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_2.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_3.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_3.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_3.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_4.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_4.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_4.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_4.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_3.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_2.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_1.PDF

8/13/2019 Tutorial Examples in Reciprocating Compressors

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5. A single stage reciprocating air compressor is required to deliver 7 m /min FAD.The induction conditions are 95 kPa and 32 C. Delivery is at 0.7 MPa and the law forthe compression and expansion processes is: pV1.3= constant.

If the clearance volume is 5% of the swept volume, calculate the indicated power and

the volumetric efficiencybased on SSL conditions

. [31.8 kW; 72.4 %]

Solution:Recips/recip comp 5.PDF

6. A three stage reciprocating air compressor has a free air delivery of 2.83 m/minbased on SSL conditions. The induction pressure and temperature are 98 kPa and 32 Crespectively. Calculate the ideal minimum indicated power (stating the assumptionsrequired) for a delivery pressure of 7 MPa and an index of compression

n = 1.3. What are the interstage pressures? [25.6 kW, 407 & 1687 kPa]

Solution:Recips/recip comp 6.PDF

7. A four stage reciprocating compressor takes in air at 1 bar & 32 C and delivers it at112 bar. The index of compression for each stage is 1.28 and intercooling is used sothat the inlet temperature is the same for each stage. The pressure ratios are chosento give equal work per stage.

Determine the volume of air delivered (at SSL conditions) per kWh work input, andthe air delivery temperature. [6.23 m/kWh, 122 C]

Solution:Recips/recip comp 7.PDF

http://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_5.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_5.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_5.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_6.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_6.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_6.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_7.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_7.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_7.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_7.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_6.PDFhttp://www.tech.plym.ac.uk/sme/ther201/thermo1/Recips/comp_5.PDF