Experimental Investigation, Model Validation and Analysis of Pressure-Volume Diagrams in a Two-phase Scroll Compressor

The present paper introduces an experimental investigation of an open-drive scroll compressor prototype working with two-phase refrigerant flows at the suction of the compressor. The experimental results are used to calibrate and validate a deterministic model, which allows performance analysis via pressure-volume diagrams. The design of the test bench dedicated to two-phase compression is first presented. The objective of this test bench is to assess the performance of the compressor working with a two-phase oil-refrigerant mixture under varying conditions such as inlet pressures, inlet vapor qualities, oil circulation ratios, pressure ratios and speeds. Inlet vapor qualities down to 25% have been experimentally tested. The investigated compressor is equipped with a dynamic pressure sensor, which enables partial measurement of the pressure in the compression and discharge chambers. The validation of the deterministic model is based on the mass flow rate and the power consumption, as well as on the pressure measurements. This validation shows good agreement, with average relative deviations of 3.19%, 1.84% and 1.92% for the power consumption, mass flow rate and mean internal pressure predictions, respectively. Finally, pressure-volume diagrams are analyzed to characterize efficiency losses associated with two-phase compression at different inlet qualities and pressure ratios. To this end, the isentropic efficiency is decomposed into several contributions, enabling the isolation of the indicated efficiency, which is analyzed using these diagrams.