Parametric Study of Hermetic Reciprocating Compressor

A numerical simulation of the thermal and fluid-dynamic behaviour of hermetic reciprocating compressors has been developed by solving the one-dimensional and transient governing equations of the flow (continuity, momentum and energy) in the whole compressor domain. The governing equations are discretized using an implicit control-volume formulation. A SIMPLE-like algorithm, extended to compressible flows, has been used for velocity-pressure coupling, and a staggered grid is employed to compute the velocity field. This formulation requires empirical correlations for the gas-solid surface interaction (friction and heat transfer). The objective of this work is to present a parametric study of a conunercial hermetic reciprocating compressor based on the above numerical simulation. The influence of the following aspects on the volumetric efficiency, compression work and the coefficient of performance (COP) has been studied: i) valve geometry (valve stop, valve diameter) of both suction and discharge valves; ii) resonator influence iii) heat transfer phenomena between fluid flow and the motor-compressor unit; iv) angular velocity variations in a periodical cycle; v) characterization parameters of suction valve (damping coefficient, stiffness, mass).