Experimental investigation on valve impact velocity and inclining motion of a reciprocating compressor

• The inclining angle of discharge valve becomes uncertain if pressure ratio is larger than 2.55.
• The inclining angle decreases with the increase in valve installation distance.
• The piston velocity and volume of compression chamber have a direct impact on impact velocity.

The working cycle of a reciprocating compressor results in the periodic impact of compressor valves. In order to find out the main cause for the excessive impact stress, this paper presents an experimental investigation on the valve dynamics especially the inclining angle and the impact velocity. The suction and discharge ring valves were redesigned and three displacement sensors were installed on top of the valve rings to measure the rings' instantaneous 3D motions, based on which the main factors that influenced the valve movements were identified by varying the valve installation position, clearance, working condition and the rotational speed. The inclining motion hardly happens as the valve is opening, while severe inclining motion takes place when the discharge valve is closing. When the pressure ratio is larger than 2.55, the inclining angle becomes uncertain because of the short time span of discharge process. The piston velocity and the volume of compression chamber at the valve opening moment have a direct impact on the maximum impact velocity. It displays a quick increase with the increase of pressure ratio and rotational speed while the valve installation position and the clearance have little influence on the maximum impact velocity. This experimental measuring method and results could provide useful information for both valve testing and optimization of valve reliability.