Numerical simulation of piston leakage over hermetic reciprocating compressors behavior.

Abstract

Instantaneous flow leakage between piston and cylinder is numerically evaluated. Reynolds equation is solved to calculate the pressure leakage distribution through the piston in the compressor. Piston movement inside the cylinder is simulated from kinematic analysis of the connecting rod mechanical system and the respective force balances. An updated version of this model is here presented for different working range compressors and fluid refrigerants compressor chamber pressures distribution. The influence of flow leakage, clearance ratio, oil viscosity, friction losses and mechanical system force balances is also evaluated. The present model needs the instantaneous fluid pressure distribution inside compression chamber and compressor shell as boundary conditions, while, simplified correlations of mass flow leakage feeds the numerical simulation model of hermetic reciprocating compressors where the instantaneous pressure distribution is obtained. In that sense both numerical results are obtained.