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. 2017 Feb 17:8:14476.
doi: 10.1038/ncomms14476.

Limited options for low-global-warming-potential refrigerants

Mark O McLinden  1 , J Steven Brown  2 , Riccardo Brignoli  3 , Andrei F Kazakov  1 , Piotr A Domanski  3
Affiliations

Limited options for low-global-warming-potential refrigerants

Mark O McLinden et al. Nat Commun. .

Abstract

Hydrofluorocarbons, currently used as refrigerants in air-conditioning systems, are potent greenhouse gases, and their contribution to climate change is projected to increase. Future use of the hydrofluorocarbons will be phased down and, thus replacement fluids must be found. Here we show that only a few pure fluids possess the combination of chemical, environmental, thermodynamic, and safety properties necessary for a refrigerant and that these fluids are at least slightly flammable. We search for replacements by applying screening criteria to a comprehensive chemical database. For the fluids passing the thermodynamic and environmental screens (critical temperature and global warming potential), we simulate performance in small air-conditioning systems, including optimization of the heat exchangers. We show that the efficiency-versus-capacity trade-off that exists in an ideal analysis disappears when a more realistic system is considered. The maximum efficiency occurs at a relatively high volumetric refrigeration capacity, but there are few fluids in this range.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Cycles simulated.
(a) Basic vapour compression cycle; (b) cycle with LL/SL-HX; (c) two-stage flash economizer cycle.
Figure 2
Figure 2. Results of ideal cycle analysis for low-global-warming-potential and current fluids.
This analysis shows the trade-off between the coefficient of performance (COP) and volumetric capacity. The majority of low-GWP fluids have low volumetric capacity relative to that of R-410A. The ‘Pareto front' line shows the thermodynamic limit of performance for fluids in the ideal vapour compression cycle, as discussed by Domanski et al..
Figure 3
Figure 3. Coefficient of performance and volumetric capacity of selected low-global-warming-potential fluids.
Results are shown for the basic vapour compression cycle; values are relative to those for R-410A and are calculated with the ‘optimized' cycle model.
Figure 4
Figure 4. Optimized coefficient of performance versus volumetric capacity for the liquid-line/suction-line heat exchanger and economizer cycles.
Values plotted are relative to those for R-410A in the basic cycle (COPR-410A=5.35 and Qvol,R-410A=6.93 MJ·m−3); (a) cycle with LL/SL-HX; (b) two-stage flash economizer cycle.
See this image and copyright information in PMC

References

    1. Velders G. J. M., Fahey D. W., Daniel J. S., McFarland M. & Andersen S. O. The large contribution of projected HFC emissions to future climate forcing. Proc. Natl Acad. Sci. 106, 10949–10954 (2009). - PMC - PubMed
    1. European Parliament. Regulation (EU) No. 517/2014 of the European Parliament and of the Council of 16 April 2014 on fluorinated greenhouse gases and repealing Regulation (EC) No. 842/2006. Official Journal of the European Union L150, 195–230 (2014).
    1. UNEP Ozone Secretariat. in Twenty-Eighth Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer (Kigali, Rwanda, 2016); document UNEP/OzL.Pro.28/CRP/10, United Nations Environment Programme, 2016.
    1. ANSI/ASHRAE Standard 34-2013 Designation and Safety Classification of Refrigerants (ASHRAE, 2013).
    1. ISO Standard 817:2014 Refrigerants—Designation and Safety Classification (International Organization for Standardization, 2014).

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