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UNIVERSITY OF CAPE TOWNDEPARTMENT OF MECHANICAL ENGINEERING

COMPRESSOR ANALYSIS EXPERIMENT

AIM:To examine aspects of a single-stage air-compressor.

1. To determine the instantaneous value of the (polytropic) coefficient of compressionfrom the slope of the pressure/volume (P/v) diagram, near the start, in the middle andat the end of the compression.2. To determine the indicated worUcycle of the compressor from the P/v diagram.Where:work/cycle = (m.e.p ) x (piston-area) x (stroke)

Whereo m.e.p. = mean effective pressure = average pressureo average pressure = area of diagram/length of the diagram (i.e. stroke of the

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TECHNICAL SPEGIFICATIONS:

Compressor:No of PistonsBoreStrokeClearance Volume

260 mm40 mm3 ml/piston

Transducer ConstantsIn order to obtain the PV diagram, the compressor has been fitted with two electronictransducers:. A pressure transducer with an output calibrated in bars (gauge pressure).

o A piston-stroke transducer. This is a capacitive transducer that requires the use of areactance converter to produce an output voltage relative to the position of the pistonin the cylinder. The limits ofthe output of this transducer represent the top_deadcentre position of the piston and the length is therefore equal to the stroke of theoiston.

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