Geometric correlation of discharge coefficients for discharge valve system in rolling piston rotary compressor

Abstract

In this study, a geometric correlation for discharge coefficient of the discharge valve system of a rolling piston compressor was proposed to predict the discharge mass flow rate. A computational fluid dynamics simulation was conducted and verified with experimental data to derive the correlation of the discharge coefficient with variations in the valve lift, valve diameter, discharge port diameter, and upstream and downstream pressure ratio of a discharge port. The discharge coefficient was dominantly affected by the geometric parameters, whereas the pressure ratio was not a dominant factor. The derived correlation, which could be applied to a wide operational range for a discharge valve system, was adopted in a compressor simulation for a rolling piston rotary compressor. The simulation results showed good agreement with experimental data. The cooling capacity, input power, and energy efficiency ratio (EER) were predicted within 10 %, and the trends agreed well over wide operating ranges for the compression ratio and compressor speed.