Low GWP Refrigerant Technology Update

Transcription

1 Low GWP Refrigerant Technology Update November 20, 2008 DuPont Fluoroproducts Barbara H. Minor Thomas J. Leck 2008 International Symposium on New Refrigerants and Environmental Technology, Kobe, Japan

2 2 Agenda Regulatory landscape HFO-1234yf properties HFO-1234yf automotive a/c industry update Low GWP options for stationary a/c and refrigeration

3 Regulatory Landscape Growing Pressure on HFCs Global increasing interest in a proposal for a global agreement on phasedown of HFCs to be managed under the Montreal Protocol. This would include caps and reduction-in-use outside Kyoto (HFCs currently in Kyoto basket of gases) Japan METI/NEDO promoting development of fluids with low GWP EU F-Gas regulation will be reviewed in Potential regulations on stationary under consideration US incoming president supports climate change legislation. Unknown whether HFCs will be regulated separately Climate Security Act (Boxer, Lieberman, Warner) proposes a separate cap for HFCs, apart from the main five-gas cap. Australia on fast track to put HFCs in trading basket with other Greenhouse Gases (GHGs) which will result in pressure to reduce their use 3

4 HFC regulation U.S. Comparison of GWP and Carbon Values 4 Refrigerant/Compound HFC-152a HFC-32 HFC-245fa HFC-134a HFC-4310mee HFC-125 HFC-227ea HFC-143a R-410A R-404A IPCC/AR4 GWP (Carbon est.$25/tonne CO 2 ) 124 ($3.10) 675 ($16.88) 1020 ($25.50) 1430 ($35.75) 1640 ($41.00) 3500 ($87.50) 3220 ($80.50) 4470 ($111.75) 2088 ($52.20) 3922 ($98.05) HFO-1234yf 4 ($0.10)

5 5 HFO-1234yf Leading Low GWP Option to Replace R-134a Jointly Developed by DuPont and Honeywell Excellent environmental properties Very low GWP of 4, Zero ODP, Favorable LCCP Atmospheric chemistry determined and published Low toxicity Low acute and chronic toxicity System performance very similar to R-134a Excellent COP and Capacity, no glide From both internal tests and auto OEM tests Thermally stable and compatible with R-134a components Potential for direct substitution of R-134a Mild flammability (manageable) Flammability properties significantly better than 152a; (MIE, burning velocity, etc) Potential for A2L ISO 817 classification versus A2 for 152a based on AIST data Minimal modifications for safety

6 HFO-1234yf Properties 6 HFO-1234yf 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 HFO-1234yf Temperature, degrees C

7 7 Automotive Update Auto OEMs continue strong support of HFO-1234yf as the leading MAC alternative Major milestones have been achieved through cooperative industry effort and open sharing of results Toxicity/Environmental testing (DP-HW) Risk assessments for flammability and health (SAE CRP-1234), JAMA, European Alliance) System performance/lccp evaluations (OEMs, SAE CRP-1234) Materials compatibility/durability testing (SAE CRP , JAMA, OEMs, Tier 1s and 2s) Registration (REACH, SNAP, ASHRAE, etc)

8 HFO-1234yf Toxicity Results Test HFO-1234yf 134a Acute Lethality No deaths 400,000 ppm No deaths 359,700 ppm 8 Cardiac sensitization NOEL > 120,000 ppm NOEL 50,000 ppm LOEL 75,000 ppm 13 week inhalation NOAEL 50,000 ppm NOAEL 50,000 ppm Developmental (Rat) NOAEL 50,000 ppm NOAEL 50,000 ppm Genetic Toxicity Not Mutagenic Not Mutagenic 13 week genomic (carcinogenicity) 2-yr carcinogenicity Environmental Tox Developmental (Rabbit) 1-Gen segment of 2-Gen Reproductive Not active (50,000 ppm) Not required NOEL > 83 mg/l (Pass) NOAEL 4,000 PPM, LOAEL 5,500 PPM Interim NOAEL 5,000 ppm (6-hours exposures) Not tested HFO-1234yf Has Low Toxicity Not carcinogenic NOEL > 100 mg/l (Pass) NOAEL 2,500 PPM LOAEL 10,000 NOAEL 50,000ppm (1-hour exposures)

9 9 HFO-1234yf Mild Flammability Properties (cm/s) Flammability Properties LFL a UFL a MIE BV c (vol%) (vol%) (vol%) (mj) Propane R152a R b 6.7 Ammonia b 7.2 HFO-1234yf c a Flame limits measured at 21 C, ASTM b Tests run in 12 litre flask to minimize wall quenching effects c Burning Velocity ISO 817 (HFO-1234yf BV measured by AIST, Japan) HFO- 1234yf a Propane R = F = 1 RF = Cst LFL RF2 = Flammability Index R LFL UFL UFL 1 LFL F Q M RF {( ( UFL LFL) LFL) / LFL} Qst Su RF Cst = Stoichiometric composition in air, vol.% Q = Heat of Combustion per one mole Qst = Heat of Combustion per one mole of the Stoichiometric mixture, kj/mol Su = Burning speed in Meters/Second M = Molecular weight

10 10 SAE CRP-1234 Auto A/C Risk Assessment Results Table 26. Risks of Injury or Fatality from Various Events Compared to Risks Associated with Leaks of HFO-1234yf Risk Risk of stroke Fatal accident in the home Fatal accident while climbing mountains (if mountaineer) Risk per year 2.7 x x x 10-4 Citation Rhys Williams, 2001 Wilson and Crouch, 1987 Wilson and Crouch, 1987 Risk of being injured as a pedestrian Fatal injury at work (all occupations) Injury from lightning strike Risk of being fatally injured in an elevator ride Risk of exposure to HFO-1234yf above health based limits resulting from a collision Risk of being injured by an HFO-1234yf ignition resulting from a collision 2.1 x x x x x x NSC, 2004 NSC, 2004 NWS, undated** McCann and Zalesky, 2006 CRP1234 Analysis CRP1234 Analysis *Risk cited is 1 in 10,000 over the next century # Injury sufficiently serious to require hospital visit. Based on number of injuries per year divided by total U.S. adult population. Total number of injuries requiring hospital visit per year divided by the total U.S. population. ** Total number of documented injuries from lightning strikes per year, divided by total U.S. population. & FTA risk multiplied by the number of estimated drivers in the U.S..

11 11 JAMA LCCP in a Compact Car SAE Phoenix, 2008

12 12 Air Conditioning Low GWP Options

13 HFO-1234yf at AC Conditions Thermodynamic Cycle Model Results: 13 Evaporator Temp: 7.2 ºC (45 ºF) Condenser Temp: 43.3 ºC (110 ºF) Liquid Refrigerant Subcool Temperature: 2.8º C (5º F) Suction Gas Superheated to 18.3 ºC (65º F) Refrigerant GWP Flammable? COP Capacity IPCC AR4 kj/m 3 R-410A 2088 No R No R-407C 1774 No HFO-1234yf 4 YES Can use mixtures to create better capacity, low GWP replacements

14 Formulation of Refrigerant Mixtures: Hierarchy of Desired Properties 14 Select Components with Desired Properties GWP Flammability at ASHRAE or ISO Conditions Refrigeration Performance Energy Efficiency (COP) Capacity Azeotropes or Blends with Similar Boiling Points Minimum Temperature Glide Work in Existing Equipment Designs Match Pressure Characteristics of Existing Refrigerant

15 15 Development of Blends Start with the Fundamentals! Understand the Physical and Chemical Factors Impacting mixture properties of Fluorocarbons Account for Non Ideal Behaviors e.g. Azeotropes Assumptions of Thermodynamic Ideality can lead to errors Measurements of Binary Pair Properties Validate Modeled Performance in Instrumented Laboratory Systems

16 Thermodynamic Model Input Parameters: HFCs form many non ideal mixtures Activity γ - function of liquid composition and of temperature. NRTL Models using γ predict liquid phase behavior Fugacity Φ - function of vapor composition, temperature, and pressure. Vapor Phase Properties modeled with Peng-Robinson EOS γ and Φ MUST BE MEASURED Ranges of Binary Pair VLE Measurements, Inclusion of γ and Φ,when measured at appropriate mixing ratios, enables accurate modeling Accurate Thermodynamic Refrigeration Cycle Models 16

17 17 Ideal Versus Non-Ideal Mixture Non-ideal Mixture Azeotrope Pressure Large Pressure Difference, Corresponding COP ~ 12% larger Ideal Mixture Mol Fraction HFO-1234yf

18 Representative Results of Thermodynamic Modeling AC Conditions Evaporator T: 7.2 C, Condenser T: 43.3 C 145% SubCooling 2.8 C, Superheat: 11 C, Comp Efficiency: 70 % * R-410A % Less glide: 0.5 to 4 C Capacity (% R22) 105% 85% Mildly Flammable Compositions R-22 * Non Flammable Compositions higher glide: 3.5 to 6.1 C 65% * HFO1234yf 75% reduction 50% reduction GWP = % reduction 45% GWP

19 19 COP (Rel. to R-410A) vs. GWP 1.2 R-407C COP rel to R-410A R-32 R-410A GWP

20 20 Commercial Refrigeration Low GWP Options

21 Thermo Modeling: Med Temp Refrig % Evap 0F (-17.8C) Cond 115F (46.1 C) Subcool 10 F (5.5C) SH 60F Flammability 2L, Glide 1-3 ºC 140.0% Cap vs 120.0% R404A R404A 100.0% 80.0% 90 % red n 60.0% R-22 Flammable, Glide 4-6 ºC 75 % Reduction vs 404A GWP % GWP GWP

22 22 Refrigeration Performance Cooling Performance Modeled for Commercial Reach-In Cooler R-134a, 4 ºC Box Temperature, 32 ºC / 90 ºF Ambient Baseline test condition Uses Suction Line Heat Exchanger For modeling we assumed 15 ºK condenser approach 6 ºK evaporator approach

23 23 Cycle Model Results: 4 ºC Box Temperature Evaporator at -2 ºC to achieve refrigerated compartment of 4 ºC Condensing temperature 15 K above ambient temperature Compressor efficiency : 70 % Return Gas to Compressor: 15 ºC Evaporator Condenser Disch Comp. Disch Cap rel. COP Refrig. T ºC T ºC kpa ratio T ºC to R-134a w/r R-134a R-134a yf % 98.35% R-134a yf % 97.61% R-134a yf % 95.32% R-134a yf % 92.80%

24 24 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 HFO-1234yf will be classified A2L USA Stationary A/C and Refrigeration - Japan ASHRAE Std 15 - greater than 3 kg requires a machine room. May work to revise for mild flammables (e.g. A2L) UL has a procedure for requesting addition of refrigerants to their standards and sets specific charge limits based on flammable properties (UL 1995, UL 471) No specific regulations, but must follow High Pressure Gas Law as done for R134a

25 25 EN Residential A/C Standard Refrigerant Charge Size Guidelines Charge sizes Refrigerant LFL (k g/m3) m1 (kg) m2 (kg) m3 (k g) R R12 34yf R15 2a Propan e 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

26 26 Conclusions: HFO-1234yf has been shown to be a safe, effective refrigerant for environmentally sustainable solutions for MAC applications Excellent Potential R-134a replacement for HVACR applications It is possible to develop reduced GWP blends with good capacity and COP There may be trade-offs of GWP, Flammability, Performance Solutions may be more like R-22/R407C than like R410A Flammability issues must be assessed for safety codes in residential and commercial buildings

27 THANK YOU! 27