A Numerical Methodology for the Analysis of Valve Dynamics

The work presents a numerical methodology to simulate the dynamic behavior of reed type valves of reciprocating compressors used in refrigeration. A one-degree of freedom model is adopted for the reed motion and a finite volume method is employed to obtain the flow field through the valve. The valve dynamics and the time dependent flow field are coupled and solved simultaneously. As a first step, the flow through the valve is assumed laminar, incompressible and isothermal. Due to the inclined valve motion a three-dimensional numerical model was developed to take into account the variation with time of the computation domain. Through a coordinate transformation a moving coordinate system was obtained; this new system was able to expand and compress according to the valve displacement. Results for the force acting on the reed were obtained for a prescribed periodic velocity for the piston. The resulting flow field through the valve reveals a complex flow pattern, and that is explored in the paper.