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Experimental investigation of part-load performance of enhanced CO2 refrigeration systems.

Number: 0035

Author(s) : DOERFFEL C., BARTA R. B., HESSE U.

Summary

Due to climate change and growing legislative pressure, researchers in industry and academia alike are committing significant effort to developing and validating environmentally-friendly refrigeration solutions. One such solution is the application of the natural refrigerant CO2 in commercial refrigeration applications. However, due to its low critical temperature and high critical pressure, cycle enhancements are necessary to achieve a Coefficient of Performance (COP) that is competitive with that of hydrofluorocarbon (HFC) systems at warm ambient temperatures. To address this challenge and provide a meaningful comparison of different cycle enhancements and architectures, a direct comparison of different system CO2 system designs was performed on an advanced CO2 laboratory refrigeration system test stand at different operating conditions. Included in these enhancements are two types of expansion work recovery, namely an expander-compressor-unit (ECU) and an ejector. In order to characterize the system under realistic operating conditions, this work focuses specifically on the use of frequency inverters and cylinder deactivation as methods of capacity control to assess part-load conditions.
It was observed that the use of cylinder unloading in addition to frequency inverters could accommodate a further capacity reduction of approximately 50% with an accompanying reduction in Carnot-COP of less than 10%. The ECU was also able to continue to operate reliably at this reduced load, despite having a fixed volume ratio. The future work for this investigation entails further characterization of performance-enhancing measures at partial load conditions as well as design improvements to maximize system efficiency at both full- and part-load operating conditions.

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Pages: 8 p.

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Details

  • Original title: Experimental investigation of part-load performance of enhanced CO2 refrigeration systems.
  • Record ID : 30029669
  • Languages: English
  • Subject: Technology
  • Source: 15th IIR-Gustav Lorentzen Conference on Natural Refrigerants (GL2022). Proceedings. Trondheim, Norway, June 13-15th 2022.
  • Publication date: 2022/06/13
  • DOI: http://dx.doi.org/10.18462/iir.gl2022.0035
  • Document available for consultation in the library of the IIR headquarters only.

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