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Experimental study and modelling of a two-stage compression R744 refrigeration system with vapour injection and intercooling.

Number: 2546

Author(s) : VEGA J., GENDEBIEN S., LEMORT V.

Summary

Current trends in CO2 supermarket refrigeration have leaned towards systems including parallel compression and ejectors. However, the possibilities that twostage compression system architectures can offer remain out of the main spotlight. In this work, a condensing unit for CO2 supermarket refrigeration is tested in a climatic chamber. The system includes a two-stage rolling piston compressor with vapor injection and intercooling. The condensing unit is tested in several operating conditions to characterize the system COP and overall behaviour of the system, with a special focus on the compressor performance assessment. The COP of the machine ranges from 3.6 to 1.3 for several testing conditions with an outlet gas cooler temperature varying from 24 to 40 [°C], at an evaporating temperature of 10 [°C]. The experimental results allow for calibrating a twostage rolling piston compressor semiempirical model. The parameters of this model are calibrated for the first time not only to predict the main mass flow rate and power consumption, but also discharge temperature and vapour injection mass flow rate. Results show that the semiempirical model can predict three key compressor variables satisfactorily: first stage suction mass flow rate, compressor electric consumption and total discharge mass flow. The model calculates these variables with an average absolute relative deviation of 6.2%, 10.2% and 4.4%. Discharge temperature absolute error averages 8.0 [K]. However, high errors are obtained for the prediction of the injection mass flow rate. This may be explained by possible illdefined thermodynamic states at the injection point that serve as model input. Lastly, the parameters identification procedure allows estimating the unknown second stage compression displacement volume by means of error minimization.

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  • Original title: Experimental study and modelling of a two-stage compression R744 refrigeration system with vapour injection and intercooling.
  • Record ID : 30030770
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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