The numerical simulation of the thermal and fluid-dynamic behaviour of reciprocating compressors presented at Purdue in 1994 [1] has been revised and improved. The modelization is based on the full integration of the governing equations (continuity, momentum and energy) in the whole domain of the compressor (compression chamber, manifolds, mufflers, connecting tubes, orifices, etc.). The one-dimensional and transient governing equations are discretized by means of an implicit control-volume formulation. These equations are numerically coupled using the segregated pressure-based algorithm SIMPLEC extended to compressible flow. In this paper attention has been focused on small hermetic reciprocating compressors commonly used in household refrigerators and freezers, air conditioners, etc. The present model makes possible the analysis of compressors whose piping system include parallel paths. A one degree of freedom valve motion model has been implemented. Other improvements have been carried out: the possibility of choosing between plenum and anechoic boundary conditions; the consideration of the compressibility effects at the valve ports; and the inclusion of an inertial term in the momentum equation applied to singularities. In order to validate the modelization a comparison between numerical and experimental results is presented.
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