Thomas Leck, PhD DuPont Fluorochemicals 2010 NEXT ACR Tokyo International Exchange Center 17 Feb 2010 DEVELOPMENT AND EVALUATION OF HIGH PERFORMANCE, LOW GWP REFRIGERANTS FOR STATIONARY AC AND REFRIGERATION
2 Outline of Presentation General Overview of Refrigerant gases Discussion of ongoing changes due to better understanding of the needs of society and industry Observations on properties Flammability Reduced GWP Refrigerant Blends Cycle Model Analysis Air Conditioning Heat Pumps Medium Temperature Refrigeration Low Temperature Refrigeration Conclusions Statement on Stewardship of Refrigerants
Commercial Refrigerant Examples Many types necessary to meet diverse cooling needs 3 Refrigerant Primary Use Normal B.P. Comment CO2 Low Temp -78 ºC Low critical temperature. Requires expander for AC Ammonia Industrial Freezing Ice Making -33 ºC Toxic Mildly flammable Safety Measures HFC-134a HFC-410A HFC-404A General Refrigeration, Air Conditioning -26 ºC -51 ºC -46 ºC High Global Climate Impact Potential Isobutane Propane Domestic Refrigeration Industrial -12 ºC - 42 ºC Explosive Must limit charge size, or use industrial safety controls HCFC-123 Large Tonnage Centrifugal 28 ºC Mild Toxicity ODS
4 Commercial Refrigerants: Ever Changing Early years: Sulfur Dioxide, Ethyl Ether, Methyl Acetate, Hydrocarbons, Ammonia, CO2 Less Toxic, Less flammable: Halocarbons (R-12, R-22, R-11) ODP Halocarbons Replaced by non ozone depleting HFC R-134a, R-404A, R-410A HFC to be replaced by Lower Climate Impact Refrigerants: Hydrocarbons, Ammonia, CO2 Hydrofluoroolefins
Properties R-134a Boiling Point, T b -29ºC -26ºC Molecular Weight 114 102 Formula CF3CF=CH2 CH2FCF3 Global Warming Potential 4 1430 5 Pressure (MPa) 3.5 3 2.5 2 1.5 1 0.5 0 REFPROP Equation Of State available Vapor Pressure R-134a -40-20 0 20 40 60 80 100 Temperature, degrees C
6 - Excellent Environmental Properties Environmental Properties Established and Peer Reviewed ODP = 0; GWP 100 = 4 Atmospheric lifetime = 11 days Atmospheric chemistry measured Atmospheric breakdown products same as for 134a No high GWP breakdown products Good LCCP for Mobile AC Now accepted as global standard for car AC systems, to meet F-gas regulations Chemical Physics Letters 439 (2007) pp 18-22 450 (2008) pp 263-267
Flammability 7 LFL a UFL a (UFL- LFL) MIE HOC BV vol% vol% vol% mj kj/g cm/s Propane 2.2 10.0 7.8 0.25 46.3 46 R152a 3.9 16.9 13.0 0.38 16.5 23 R32 14.4 29.3 14.9 30-100 b 9.4 6.7 Ammonia 15.0 28.0 13.0 100-300 b 18.6 7.2 6.2 12.3 6.1 5,000-10.7 10,000 b a Flame limits measured at 21 o C, ASTM 681-01 b Tests run in 12 liter flask to minimize wall quenching effects c BV measured by AIST, Japan 1.5 c Mildly Flammable 2L
8 Thermal Stability AFTER TWO WEEKS @ 175 C /POE vs HFC-134a/POE Front View Side View HFC-134a HFC-134a No Detectable Fluoride nor Acid Generation Thermal Stability and POE Miscibility comparable to R-134a
Compatibility with Plastics % weight change after 2 wks @ 100ºC in vs HFC-134a 9 Polymer Immediately 0 Hrs after exposure 0 Hrs 24 Hrs after exposure 24 Hrs HFC-134a HFC-134a Polyester Resin 7.6 4.2 2.2 2.3 Nylon Resin 0.3-0.2-0.5-0.4 Epoxy Resin 0.1-0.1-0.3-0.1 Polyester PET 9.3 5.3 5.8 3.8 Polyester PBT 12.5 1.1 12.3 1.1 Polycarbonate 4.2 0.9 3.9 0.8 Polyimide 3.7 3.4 3.2 3.2 Polyethylene 1.3 1.7 1.1 1.3 PTFE 2.7 3.0 2.3 2.4 FEP 3.1 3.8 2.7 3.2 ETFE 6.0 4.9 4.8 4.2 Phenolic Resin -0.8-0.8-1.0-0.8 Acetal Resin 2.7 0.7 2.1 0.6 PET Film 0.8-1.0-1.3-2.1
10 Compatibility with Elastomers HNBR NBR Silicone Viton Hypalon % weight change after 2 wks @ 100ºC in vs HFC-134a Elastomer Immediately 0 Hrs after exposure 0 Hrs 24 24 Hrs after exposure 24 Hrs Neoprene WRT EPDM (Nordel) Butyl Rubber Terminal seal Buna S (SBR) Neoprene o-ring HFC-134a 2.6 15.2 14.1 3.6 10.6 4.1 2.2 2.7 47.4 3.2-0.4 2.4 5.2 5.8 3.5 2.0 5.0 4.8 2.1 20.0 2.7 3.0 HFC-134a 1.3 9.9 8.0 0.7-0.1 3.2 0.8 1.1 8.0 2.6-0.5 Overall: Comparable degree of interaction of polymers & elastomers with 1234yf and 134a 1.3 4.4 4.6 0.6-0.4 4.1 2.0 0.8 8.0 2.4 2.3
at AC Conditions Thermodynamic Cycle Model Results: 11 Evaporator Temp: 7 ºC Condenser Temp: 47 ºC Liquid Refrigerant Subcool : 12 K Suction Gas Superheat 3 K Suction Temperature 10 ºC Refrigerant GWP IPCC AR4 Flammable? COP Capacity kj/m 3 R-410A 2088 No 4.04 6225 R-22 1810 No 4.299 4300 R-407C 1774 No 4.225 4371 R-134a 1430 No 4.378 2816 4 Yes 4.267 2667 Can use mixtures to create higher performance, low GWP replacements
Formulation of Refrigerant Mixtures: Hierarchy of Desired Properties 12 Select Components with Desired Properties Refrigeration Performance Energy Efficiency (COP) Relates to Energy Usage Capacity Flammability at ASHRAE or ISO Conditions GWP Azeotropes or Blends with Similar Boiling Points Minimum Temperature Glide Work in Existing Equipment Designs Match Pressure Characteristics of Existing Refrigerant
R-32 1-3 G R-410A R-407C 4.8 G R-22 COP vs 410A 5-7 G 4 G 0 to +1% 0 G R-134a +3 to +6% +6 to +8% G = Glide, K Mildly Flammable Non Flammable
1-3 G R-32 R-410A R-407C R-22 5-7 G 0 G 4 G R-134a COP vs 410A 0 % +0.5 to +1.5% +2 to +3% +3 to +5% +5 to +6% G = Glide, K Mildly Flammable Non Flammable
R-32 1-3 G 5-6 G R-404A 5-7 G 0 G 4 G R-134a R-22 COP vs 404A -3 % -2 to 0% 0% +3 to +5% +7 to +8% G = Glide, K Mildly Flammable Non Flammable
R-32 1-3 G 5-6 G 5-7 G 0 G 4 G R-134a R-22 R-404A COP vs 404A -6% -4 to -3% -1 to 0% +2 to +4% +7% G = Glide, K Mildly Flammable Non Flammable
17 Conclusions: has been shown to be a safe, effective refrigerant for environmentally sustainable solutions for MAC applications. has excellent potential to replace R-134a for HVACR applications where mild flammability can be managed. is not a replacement for fluids like R-410A, R-404A We have developed reduced GWP blends with good capacity and COP that may be useful in R-134a, R-22, R-410A or R-404A applications There will be trade-offs of GWP, Flammability, Performance, and Glide. Regulatory certainty is essential since regulations will impact final product selection and timing. We recommend that regulatory structures not be based solely on a GWP cap, but instead consider energy efficiency, capacity and other performance related issues so that these options are available. Flammability issues must be assessed for safety codes in residential and commercial buildings before this new generation of refrigerants can be fully implemented.
18 Containment is Critical No refrigerant, while sealed in a cylinder, or in a system can cause environmental damage. Or cause fires, or cause other harm. Proper stewardship of the refrigerant is at least as important as the choice of refrigerant to be used. There is a need for enforceable protocols, or meaningful incentives for recovery, recycle, and end of life disposition of equipment and refrigerant gases. Our industry must do much better than it has in the past
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Auto industry has been moving forward decisively with HFO- 1234yf (Press Release Nov 10, 2009) 21
22 Flammable Refrigerant Regulations In Commercial Stationary Refrigeration and A/C Europe Stationary A/C - IEC 60335-2-40, pr EN 378-1-2007, ISO 5149-2006 - Maximum charge size based on LFL, room size, equipment location Stationary Refrigeration IEC 60335-2-89 limit of 150 gram unrestricted. Above 150 gram refer to EN 378 or ISO 5149 for charge size limits ISO 817 in progress will be classified A2L USA Stationary A/C and Refrigeration - ASHRAE Std 34 has final approval for 2L flammability classification ASHRAE Std 15 - greater than 3 kg requires a machine room. May work to revise for mild flammables (e.g. A2L) UL has application specific standards, and are starting some review of specific charge limits based on flammable properties (UL 1995, UL 471), considering 2L Japan Follow High Pressure Gas Law, but also consider ISO and IEC regulations Fire safety regulations are being reviewed and must be updated to acknowledge the lower risk associated with class 2L flammability
23 EN 60335-2-40 Residential A/C Standard Refrigerant Charge Size Guidelines Charge sizes Refrigerant LFL (kg/m3) m1 (kg) m2 (kg) m3 (kg) R32 0.306 1.22 8.0 39.8 R1234yf 0.289 1.16 7.5 37.6 R152a 0.130 0.52 3.4 16.9 Propane 0.038 0.15 1.0 4.9 charge size <m1 = no significant regulations m1< charge < m2 = charge size limitations based on room size m2< charge < m3 = need mechanical ventilation charge size > m3 = this standard does not apply; use local standards