HFO-1234yf Status and Path Forward

Transcription

1 HFO-1234yf Status and Path Forward November 26, 2009 Barbara H. Minor Mary E. Koban The 3rd European Workshop MOBILE AIR CONDITIONING, VEHICLE THERMAL SYSYEMS and AUXILIARIES Torino, Italy, November 2009

2 2 Agenda HFO-1234yf Update Environmental Safety CFD Modeling of Refrigerant Leakage Scenarios Commercialization Plan

3 3 HFO-1234yf has excellent environmental properties ODP = Year GWP = 4; (GWP 134a = 1430) Measurements completed & published Atmospheric lifetime = 11 days Atmospheric chemistry measured Atmospheric breakdown products are the same as for 134a No high GWP breakdown products (e.g. NO HFC-23 breakdown product) Good LCCP Published Papers Papadimitrou, V.C. et al, CF 3 CF=CH 2 and Z- CF 3 CF=CHF: Temperature dependent OH rate coefficients and global warming potentials, Phys. Chem. Chem. Phys. Vol 10 (2008) pp Hurley, M.D. et al, Atmospheric chemistry of CF 3 CF=CH 2 : Products and mechanisms of Cl atom and OH radical initiated oxidation, Chem. Phys. Lett. Vol 450 (2008) pp Nielsen, O.J. et al, Atmospheric Chemistry of CF 3 CF=CH 2 : Kinetics and mechanisms of gas phase reactions with Cl atoms, OH radicals and O 3, Chem. Phys. Lett. Vol 439 (2007) pp

4 SAE LCCP Analysis 4

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6 6 HFO-1234yf has the potential to be exempted from VOC regulation HFO-1234yf is unstable in the atmosphere with a lifetime of only about 11 days. HFO-1234yf has been determined to have 0.9 +/- 0.2 reactivity relative to ethane Maximum incremental reactivity (MIR) was 1.0 +/-0.1 If ethane is the standard, HFO-1234yf might be exempt from VOC regulation Reference: Wm. P. L. Carter, Center for Environmental Research and Technology, Univ of California

7 7 Toxicity testing is complete HFO-1234yf has low toxicity Test HFO-1234yf HFC-134a Acute Lethality LOEL> 400,000 ppm LOEL 567,000 ppm Cardiac sensitization NOEL > 120,000 ppm NOEL 50,000 ppm LOEL 75,000 ppm 4 week toxicity NOAEL 50,000 ppm NOAEL > 50,000 ppm 13 week toxicity NOAEL 50,000 ppm NOAEL 50,000 ppm Genetic Toxicity Ames slight activity in 2 strains Ames not active inactive in 3 others Chromosome Abberration not active Chromosome Abberration not active Micronucleus (mouse) not active Micronucleus (mouse) not active Subacute micronucleus (rat) not active Unscheduled DNA Synthesis not active Developmental Toxicity Rat NOAEL 50,000 ppm Rabbit NOAEL maternal 4,000 ppm fetal 7,500 ppm Reproductive toxicity 2-Gen NOAEL 15,000 ppm (6-hour exposures) Rat NOAEL maternal 30,000 ppm fetal 300,000 ppm Rabbit NOAEL maternal 2,500 ppm fetal 2,500 ppm NOAEL 50,000ppm (1-hour exp ~8,300ppm x 6hr exp))

8 8 Agenda HFO-1234yf Update Environmental Safety CFD Modeling of Refrigerant Leakage Scenarios Commercialization Plan

9 CFD Leakage Modeling 9 Understand size of potential flammable region under various leakage scenarios Results useful as input for risk assessments Three Scenarios evaluated 1. Leak from a point in open space (simulating potential leak vehicle sitting outdoors) 2. Leak from a point in bounded space (simulating potential leak in garage or mfr plant) 3. Leak from a point under an open car hood and impinging on a surface (in a service garage) CFD Model Output Determine refrigerant concentration at several distances (x,y and z directions) from the leak point during leak event. Determine size of refrigerant plume above lower flammability limit (LFL)

10 CFD MODEL DEVELOPMENT 10 Approaches 1 st CFD Model - Release was initially modeled with no bounding 2 nd & 3 rd CFD Model -Release modeled as bounded vapor release using methodology in referenced paper Reference Venetsanos, A. G., et al, An inter-comparison exercise on the capabilities of CFD models to predict the short and long term distribution and mixing of hydrogen in a garage, Presented at 2nd international conference on hydrogen safety, San Sebastian, Spain, September 11-13, 2007, Accepted for Publication in International Journal of Hydrogen Energy

11 CFD MODEL DEVELOPMENT- 11 Assumptions for all three scenarios 600 g total refrigerant leaked 12.4 g/s of HFO-1234yf total time of leak 48.4 secs Air exchange rate was zero, or low wind field (<0.5 m/sec) for unbounded leak Release Details HFO-1234yf will create a two phase leak when released under a severed line situation. The release plume was modeled as vapor phase, since initial modeling did not show large differences in shape of jet plume

12 HFO-1234yf Plume Release Diagrams 12 Two Two Phase Jet All Vapor Jet All Free Vapor Jet Jet February 2008 Process Safety and Fire Protection 24 February 2008 Process Safety and Fire Protection 23 Liquid and vapor combined release will have the shape above. HFO-1234yf will create a two phase release under a severed line situation. An all vapor release will have the shape above Plume is fully formed within 1/2 second of the start of the release. Modeled in both horizontal and parallel directions of the air flow

13 Diagram of Scenario - Unbounded leak 13 Leak source pointsevered A/C line Refrigerant plume Assumptions: Leak is not bounded by room/structure. Leak assumed to be in low wind field, so no dissipation of refrigerant by wind.

14 Plume Concentration Profile Unbounded Leak Length of plume above LFL is very small (about 15 cm) HFO-1234yf Conc. 14 Above 6.2 vol% 6.2 vol% 5.5vol% 5.0 vol% 4.5 vol% 4.0 vol% 3.5 vol% meters 3.0 vol% Results can vary based on hole size/shape and release direction versus air currents. 2.5 vol% 2.0 vol%

15 Diagram of Scenario - Bounded leak 15 Dimensions of a single bay garage (7 x 4 x 3 m). Leak source pointsevered A/C line Refrigerant plume Small holes at bottom of box keep pressure from building up - Assumed 600 g charge released in 48 seconds and zero air flow

16 Plume Profile Bounded Leak HFO-1234yf Conc. >10 vol% 10 vol% 6.3 vol% 4.0 vol% 2.5 vol% 1.6 vol% 16 Air Velocity >100 m/sec 100 m/sec 10 m/sec 1.0 m/sec 0.1 m/sec meters Below 0.1 m/s Shape of plume above LFL is very small (10 cm in x direction, 2 cm in z)

17 Diagram of Surface Impinging Scenario 17 Dimensions of a single bay garage (7 x 4 x 3 m) Surface that leak impinges upon Leak source severed A/C line Small holes at bottom of box keep pressure from building up Modeled three different distances of leak from impinging surface (0.1 m, 0.22 m and 0.85 m)

18 Plume Profile Bounded Leak Impinged on a Surface HFO-1234yf Concentration 18 Distance to surface = 0.1m 10 vol% 6.3 vol% 4.0 vol% 2.5 vol% 1.6 vol% Below 1.0 vol% Plume is continually dispersed by surface, almost no flammable zone available

19 Plume Profile Bounded Leak Impinged on a Surface Side View HFO-1234yf Conc. 19 >10 vol% 10 vol% 6.3 vol% 4.0 vol% 2.5 vol% 1.6 vol% meter Below 1.0 vol% Air Velocity >100 m/s 100 m/s 10 m/s 1.0 m/s 0.1 m/s meter Below 0.1 m/s Plume is continually dispersed by surface with almost no flammable zone formed (~ 2-4 cm around impact point)

20 20 CFD Modeling Summary Three leakage scenarios were evaluated In unbounded space (simulating potential leak vehicle sitting outdoors) In bounded space (simulating potential leak in garage or mfr plant) Under an open car hood and impinging on a surface (in a garage) In all cases, the size of the refrigerant plume above the LFL was very small (only a few centimeters) Results indicate low risk of HFO-1234yf ignition due to small flammable envelope

21 21 Agenda HFO-1234yf Update Environmental Safety CFD Modeling of Refrigerant Leakage Scenarios Commercialization Plan

22 Auto Industry Is Converging to HFO-1234yf 22

23 23 Auto OEMs are preparing to adopt HFO-1234yf Service Industry preparations on-going Recovery/Recycle/Recharging Equipment Service Shops: Modifications proposed for HFO-1234yf automotive air-conditioning service locations New 2009 US EPA Technician Certification Auto OEMs are conducting fleet testing Auto OEMs have issued Request for Quote (RFQ) for HFO-1234yf to refrigerant manufacturers Commercial negotiations are under way Anticipate transition in EU will focus on 2012 model year cars

24 DuPont is focused on commercialization of HFO- 1234yf 24 Maintain industry convergence to HFO-1234yf Continue to provide samples and support industry testing Provide assistance on OEM facility upgrades based on DuPont expertise in handling flammable gases Prepare and submit regulatory filings Develop manufacturing process Plan/design manufacturing facility Negotiate engineering/construction/ raw materials contracts Secure customer commitments for timing/qty of demand

25 25 Thank You!