Simulation of a variable speed compressor with special attention to supercharging effects

A computer simulation model of a variable speed rolling piston rotary compressor, with a speed range from 1100 rpm up to 9000 rpm, was developed to study the performance of the compressor. The mathematical simulation includes (1) a thermodynamic model of the cylinder refrigerant gas based on the principles of conservation of energy and mass, (2) a heat transfer model to predict the transient and steady-state temperatures of the compressor system and the degree of suction gas heating, (3) a one-dimensional compressible unsteady flow model to study the supercharging effects and wire drawing loss due to the suction process dynamics, and (4) a linear gas pulsation model based on the Helmholtz resonator approach to investigate the pressure oscillations in the compressor discharge manifolds. The computer simulation model is capable of being used to predict all the mass flow losses, all the energy losses, the volumetric efficiency, the cylinder process thermodynamic efficiency, and the overall efficiency of the compressor under different speeds. The simulation results were compared to experimental data. A different mathematical model was developed to predict the refrigerant thermodynamic properties in the case of liquid and vapor two-phase refrigerant mixture being compressed in the compressor cylinder. The difference in tolerance to liquid refrigerant among compressors of different mechanisms was analyzed