Acoustical Modeling of Reciprocating Compressors with Stepless Valve Unloaders
Capacity control of reciprocating compressors can be accomplished by a variety of techniques. Some common techniques include changing compressor speed, adjusting compressor cylinder head-end variable volume pockets, recycling slow and changing compressor cylinder operation from double acting to single acting. These compressor loading techniques are well understood from an acoustical simulation perspective. One shortcoming with these compressor control techniques is they do not offer a continuous range of capacity control with minimal wasted energy. Stepless valve unloaders are one solution to address this short-coming. Acoustical simulation of reciprocating compressors using stepless valve unloaders offers several challenges. This paper presents techniques for modeling systems with stepless valve unloaders. Results of an acoustic simulation are compared for systems with and without stepless valve unloaders.