Numerical Study of the The rmal and Fluid- Dynamic Behaviour of Reciprocating Compressors

Abstract

A numerical simulation of the thermal and fluid-dynamic behaviour of reciprocating compressors has been developed. The governing equations of the flow (continuity, momentum and energy) written in transient and one-dimensional form are integrated in the whole domain. The simulation covers a wide range of compressor types, open or hermetically sealed, which can include different elements in their suction and discharge ducts (mufflers, connecting tubes, orifices, etc), allowing the possibility of backflow. This formulation requires additional information about convective heat transfer coefficient, friction factor, and pressure drop through singularities (orifices, valves, sudden enlargements and contractions). The equations are discretized by means of an implicit control-volume formulation using an upwind scheme for the convective terms. The coupling between the governing equations is made by means of a pressure-based method taking into account the compressibility of the flow. In order to illustrate the possibilities of the software developed, some numerical results are presented for a hermetic compressor.