A study of reciprocating compressor finger valve dynamics

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Virginia Tech

The main objective of this research effort was the construction of a finger valve dynamics model using simplified theory based on steady flow conditions. The analytical valve positions were then compared to experimental measurements from an Ingersoll Rand model 242 two-stage air compressor. Proximity probes were used to measure the valve position at two points on the exhaust valve at two different exhaust valve stop heights and at two points on the intake valve at one intake valve stop height in the lower exhaust valve stop height configuration only. A data acquisition system was configured to signal average and digitize the analog data from the sensors using a digital oscilloscope. The data was then sent to and stored in data acquisition computer for future comparisons to analytical results.

The comparisons of the analytical and experimental exhaust valve positions at both points and both valve stop heights were of good quality when the effects of oil stiction were taken into account. Also, the comparisons of the intake valve positions were of good quality after adjustments were made in the theoretical force on the valve calculation. The adjustments entailed accounting for flow-induced forces on the intake valve after piston reversal.

Overall the simplified model predicted the valve positions with sufficient quality to warrant the model's use as a design tool.