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Evaluation of the potential performance of a Voorhees-modified R744 transcritical cycle.

Author(s) : CHESI A., FERRARA G., FERRARI L., et al.

Summary

Carbon dioxide is one of the best candidates to replace ozone-depleting refrigerants, due to its safety and environmental properties. Yet, due to its low critical temperature, it must be used in a transcritical cycle, yielding high compression and expansion losses and therefore a low COP. Parallel compression is often proposed as an improvement strategy for transcritical CO2 reverse cycles, in order to limit expansion losses and raise the COP. Moreover Voorhees has proposed a modification of the reciprocating compressor which would theoretically permit benefiting from the advantages of parallel compression without the need of a second compressor. The aim of this work is to analytically assess the performance of a Voorhees modified cycle, thoroughly considering the effects that partial admission, admission port position and gas re-expansion from clearance volume have on COP and cooling capacity at different temperature conditions. Moreover, a parameter is defined to quantify compressor irreversibility, according to what isentropic efficiency represent for standard single-stage compressors. The obtained performance are then compared to those of an optimised parallel compression cycle and to the single-stage transcritical cycle, in order to evaluate the opportunity of using such a technology and to find the conditions (temperatures and pressures) by which its potential advantages are most exploited.

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Details

  • Original title: Evaluation of the potential performance of a Voorhees-modified R744 transcritical cycle.
  • Record ID : 2011-0036
  • Languages: English
  • Subject: Regulation
  • Source: IIR/Eurotherm sustainable refrigeration and heat pump technology conference. Proceedings of the Eurotherm Seminar No. 88, Stockholm, Sweden, June 13-16, 2010.
  • Publication date: 2010/06/13

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