| A comprehensive computer model for a reciprocating compressor and its valves is described. The model is able to give the behavior of valve motions and cylinder performance. The objective is to develop and apply mathematical models for compressor applications.;Analytical methods for determining valve effective flow area and force area are presented. The methods can be applied to different types of valving systems including streamlined valves where the fluid does not change its direction a complete 90 degrees under the moving elements. Both normal and back flow mode's are developed. The agreement with the experimental data confirm the validity of the method.;A thermodynamic model for real gas properties is incorporated to extend the working fluid to a wide variety of mixtures of gases over a large range of pressures. An equation for mass flow rate through the valve is created which takes into account the properties of real gas.;A model for valve opening force is established to predict the cylinder over-pressure and valve opening impact. The importance of the correct gas force pattern is explained. A simple but practical model for valve oil stiction is implemented. The stiction delay is based on the combination of force, contact area and an empirical constant. The advanced algorithms of gas spring, gas pulsations and valve rebound are also applied to describe the valve motions. A valve leakage model is developed to permit adjustment of the predicted pressure variation with measured values.;To obtain useful information from the output reports, methods for calculating valve losses, compressor performance, horsepower and valve reliability analysis are presented.;The predicted pressure time histories and P-V diagrams are superimposed against a large amount of field data tested in different cylinders at several operating points. The agreement encourages the present program to be utilized for industrial purposes. |
