DEVELOPMENT AND EVALUATION OF HIGH PERFORMANCE, LOW GWP REFRIGERANTS FOR STATIONARY AC AND REFRIGERATION

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1 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 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

3 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 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

5 Properties R-134a Boiling Point, T b -29ºC -26ºC Molecular Weight Formula CF3CF=CH2 CH2FCF3 Global Warming Potential Pressure (MPa) REFPROP Equation Of State available Vapor Pressure R-134a Temperature, degrees C

6 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 (2008) pp

7 Flammability 7 LFL a UFL a (UFL- LFL) MIE HOC BV vol% vol% vol% mj kj/g cm/s Propane R152a R b Ammonia b , ,000 b a Flame limits measured at 21 o C, ASTM 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 8 Thermal Stability AFTER TWO 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

9 Compatibility with Plastics % weight change after 2 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 Nylon Resin Epoxy Resin Polyester PET Polyester PBT Polycarbonate Polyimide Polyethylene PTFE FEP ETFE Phenolic Resin Acetal Resin PET Film

10 10 Compatibility with Elastomers HNBR NBR Silicone Viton Hypalon % weight change after 2 100ºC in vs HFC-134a Elastomer Immediately 0 Hrs after exposure 0 Hrs Hrs after exposure 24 Hrs Neoprene WRT EPDM (Nordel) Butyl Rubber Terminal seal Buna S (SBR) Neoprene o-ring HFC-134a HFC-134a Overall: Comparable degree of interaction of polymers & elastomers with 1234yf and 134a

11 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 R No R-407C 1774 No R-134a 1430 No Yes Can use mixtures to create higher performance, low GWP replacements

12 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

13 R 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

14 1-3 G R-32 R-410A R-407C R 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

15 R 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

16 R 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 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 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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21 Auto industry has been moving forward decisively with HFO- 1234yf (Press Release Nov 10, 2009) 21

22 22 Flammable Refrigerant Regulations In Commercial Stationary Refrigeration and A/C Europe Stationary A/C - IEC , pr EN , ISO Maximum charge size based on LFL, room size, equipment location Stationary Refrigeration IEC 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 23 EN Residential A/C Standard Refrigerant Charge Size Guidelines Charge sizes Refrigerant LFL (kg/m3) m1 (kg) m2 (kg) m3 (kg) R R1234yf R152a Propane 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