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Oil sensible semi-empirical two-stage rotary CO2 compressor model: calibration using experimental data and reconciliation algorithms

Number: 0755

Author(s) : VEGA J., SACASAS D., LECLERCQ N., CUEVAS C., LEMORT V.

Summary

A condensing unit for CO2 supermarket refrigeration that includes a two-stage rolling piston compressor with vapor injection and inter-cooling is tested in a climatic chamber to characterize the compressor performance and calibrate a semi-empirical model. The energy balances across different control volumes deteriorated due to a possible malfunctioning Coriolis flow meter in the injection line, and the presence of oil in between the two compression stages. To determine the oil circulation ratio and check the problematic flow meter, a data reconciliation algorithm and an oil-solubility model have been included to determine the mixture properties. The semi-empirical compressor model is modified to account for oil in the mixture, is calibrated with the reconciled data, and then compared with a model that considers pure CO2. The model can predict the first-stage mass flow rate and the electric power input with an expected median absolute relative deviation of 5.01% and 4.18%, respectively. The new method also helped to improve the expected RMSE of the discharge temperature from 6.61 [K] to 2.35 [K]. However, the total compressor discharge mass flow rate computed error increases with the oil sensible model, suggesting that solubility and mixture density properties used should be revised for high-pressure conditions.

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Pages: 12

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Details

  • Original title: Oil sensible semi-empirical two-stage rotary CO2 compressor model: calibration using experimental data and reconciliation algorithms
  • Record ID : 30031830
  • Languages: English
  • Subject: Technology
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0755

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