Influence of Shell Volume on Pressure Pulsations in a Hermetic Reciprocating Compressor

摘要

In a hermetic reciprocating compressor the suction pressure pulsations affect compressor performance and noise.rnThe pressure pulsations are created due to the dynamic flow of refrigerant through the suction valve into the cylinderrnbore. One dimensional (1D) acoustic method, Finite Element Method (FEM) calculated impedance transfer matrixrnmethod, and Computational Fluid Dynamics (CFD) are three commonly used methods to calculate these pressurernpulsations. With CFD being used most often to solve this type of analysis; however CFD is often time consumingrnand requires significant computer resources. In order to solve the pressure pulsation analyses faster, the suctionrnplenum geometry is often simplified by reducing the model size. This simplification could lead to inaccuracies inrnpressure pulsation modeling. This paper will use the FEM calculated impedance transfer matrix method to analyze arnhermetic HVAC reciprocating compressor to show that geometry simplifications could result in poor predictions ofrnpressure pulsation. The FEM calculated impedance transfer matrix method was chosen due to its short solution timernand the inherent ability to compare similarities and differences in the plenum’s impedances between the fullrngeometry model and a simplified geometry model. This paper will specifically look at the influence of therncompressor shell volume on calculating suction pressure pulsations. In the compressor analyzed, the compressorrnshell volume influences the pressure pulsation at the compressor’s first harmonic speed. A pressure pulsation at thernfirst harmonic has the greatest influence on the compressor performance. This paper will compare measuredrnpressure pulsations to simulated pressure pulsations. The pressure pulsations are in good agreement when the fullrnmodel is analyzed but when simplifications are done to the model it fails to provide good agreement.