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Using good rack design and electrical step-up autotransformers to improve the stable operation and energy saving of multiple-compressor racks.

Number: pap. 0047

Author(s) : KITAP A.

Summary

Within the F-Gas Regulation (EU) No. 517/2014 and the related phase down of the HFOs, CO2 and NH3 are becoming increasingly important as refrigerants again. Refrigeration systems with these refrigerants are often controlled by intelligent frequency inverters. These frequency inverters can adapt the compressor capacity to the required refrigerating capacity at any time with a good design of the compressor rack. This is referred to as optimum control of the refrigeration system (good Control Factor) which also extends the lifetime of refrigeration compressors in a rack. However, when operating CO2 compressor systems, a problem can arise that at some refrigeration operating points, the maximum permissible current of the frequency-controlled compressor is reached at a frequency lower than the maximum permissible mechanical frequency. The result is that the compressors of the refrigeration system start more frequently, which reduces the controllability of the system (poorer Control Factor) and detracts from the overall energy balance of the refrigeration system. This paper shows how this problem can be mitigated with a small modification of the electrical circuit. With the help of step-up autotransformers (3 AC 400 V ? 3 AC 480 V), the maximum permissible mechanical frequency of the frequency-controlled, star-connected compressor can often be reached cost-effectively.

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Pages: 8

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Details

  • Original title: Using good rack design and electrical step-up autotransformers to improve the stable operation and energy saving of multiple-compressor racks.
  • Record ID : 30025719
  • Languages: English
  • Source: 8th Conference on Ammonia and CO2 Refrigeration Technology. Proceedings: Ohrid, North Macedonia, Avril 11-13, 2019.
  • Publication date: 2019/04/11
  • DOI: http://dx.doi.org/10.18462/iir.nh3-co2.2019.0047

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