Two-Stage Natural Gas Reciprocating Compressor Simulation Based on AGA8 Equation of State

In this study, a two-stage natural gas reciprocating compressor is simulated based on ideal and real models. To this end, a zero-dimensional numerical method based on the crank angle is developed. For this simulation, control volumes including compressor cylinders, suction, and discharge chambers with equivalent mass and energy equations along with piston movement, valve dynamic, and mass flow rate through valve and orifice equations and heat transfer equation for heat-exchanger are investigated. For real gas model, the AGA8 equation of state has been used for computing thermodynamic properties. Simulated results compared and validated with the previous experimental results for air reciprocating compressor. Then, the developed model is used to predict compressor behavior and performance parameters. It suction and discharge pressure was considered 4.122 and 9.795 MPa respectively. Predicted results show that intermediate pressure for simulation based on real gas (4.015 MPa) is lower than ideal gas (4.093 MPa). Furthermore, the mass flow rate based on the real model (730.67 kg/h) is higher than the ideal model (710.3 kg/h). In addition, discharge gas temperature prediction with the ideal model is lower than the real model.