DEVELOPMENT AND EVALUATION OF HIGH PERFORMANCE, LOW GWP

REFRIGERANTS FOR STATIONARY AC AND REFRIGERATION

Thomas Leck, PhDDuPont Fluorochemicals

2010 NEXT ACRTokyo International Exchange Center

17 Feb 2010

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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 HFO-1234yf 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

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Commercial Refrigerant ExamplesMany types necessary to meet diverse cooling needs

Mild Toxicity

ODS

28 ºCLarge Tonnage Centrifugal

HCFC-123

Explosive – Must limit charge size, or use industrial safety controls

-12 ºC

- 42 ºC

Domestic Refrigeration Industrial

Isobutane

Propane

High Global Climate Impact Potential

-26 ºC

-51 ºC

-46 ºC

General Refrigeration, Air Conditioning

HFC-134a

HFC-410A

HFC-404A

Toxic

Mildly flammable

Safety Measures

-33 ºCIndustrial Freezing

Ice Making

Ammonia

Low critical temperature. Requires expander for AC

-78 ºCLow TempCO2

CommentNormal B.P.

Primary UseRefrigerant

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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 HFCR-134a, R-404A, R-410A

• HFC to be replaced by Lower Climate Impact Refrigerants:Hydrocarbons, Ammonia, CO2

Hydrofluoroolefins – HFO-1234yf

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HFO-1234yf R-134aBoiling Point, Tb -29ºC -26ºCMolecular Weight 114 102Formula CF3CF=CH2 CH2FCF3Global Warming Potential 4 1430

REFPROP EquationOf State available

00.51

1.52

2.5

33.5

-40 -20 0 20 40 60 80 100

R-134a

HFO-1234yf

Pres

sure

(MPa

)HFO-1234yf Properties

Temperature, degrees C

Vapor Pressure

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HFO-1234yf - Excellent Environmental Properties

ODP = 0; GWP100 = 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

HFO-1234yf Environmental PropertiesEstablished and Peer Reviewed

Chemical Physics Letters

439 (2007) pp 18-22

450 (2008) pp 263-267

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HFO-1234yf Flammability

aFlame limits measured at 21 oC, ASTM 681-01bTests run in 12 liter flask to minimize wall quenching effects cHFO-1234yf BV measured by AIST, Japan

Mildly Flammable – “2L”

5,000-10,000b

100-300b

30-100b

0.38

0.25

MIE

mJ

1.5c10.76.112.36.2HFO-1234yf

7.218.613.028.015.0Ammonia

6.79.414.929.314.4R32

2316.513.016.93.9R152a

4646.37.810.02.2Propane

BV

cm/s

HOC

kJ/g(UFL- LFL)

vol%

UFLa

vol%

LFLa

vol%

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HFO-1234yf HFC-134a

HFO-1234yf Thermal Stability

HFC-134aHFO-1234yfNo Detectable Fluoride nor Acid Generation

Thermal Stability and POE Miscibility comparable to R-134a

HFO-1234yf/POE vs HFC-134a/POEAFTER TWO

WEEKS @ 175 °C

Front View Side View

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Compatibility with Plastics% weight change after 2 wks @ 100ºC in HFO-1234yf vs HFC-134a

-2.1-1.3-1.00.8PET Film0.62.10.72.7Acetal Resin-0.8-1.0-0.8-0.8Phenolic Resin4.24.84.96.0ETFE3.22.73.83.1FEP2.42.33.02.7PTFE1.31.11.71.3Polyethylene3.23.23.43.7Polyimide0.83.90.94.2Polycarbonate1.112.31.112.5Polyester PBT3.85.85.39.3Polyester PET-0.1-0.3-0.10.1Epoxy Resin-0.4-0.5-0.20.3Nylon Resin2.32.24.27.6Polyester Resin

HFO-1234yfHFC-134aHFO-1234yfHFC-134a

24 Hrs24 Hrs0 Hrs0 HrsPolymer Immediately after exposure 24 Hrs after exposure

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Compatibility with Elastomers

2.3-0.53.0-0.4Neoprene o-ring2.42.62.73.2Hypalon8.08.020.047.4Viton

0.81.12.12.7Buna S (SBR)

2.00.84.82.2Terminal seal

4.13.25.04.1Butyl Rubber

-0.4-0.12.010.6Silicone

0.60.73.53.6EPDM (Nordel)

4.68.05.814.1NBR

4.49.95.215.2HNBR

1.31.32.42.6Neoprene WRTHFO-1234yfHFC-134aHFO-1234yfHFC-134a

24 Hrs24 Hrs0 Hrs0 HrsElastomer Immediately after exposure 24 Hrs after exposure

% weight change after 2 wks @ 100ºC in HFO-1234yf vs HFC-134a

Overall: Comparable degree of interaction of polymers & elastomers with 1234yf and 134a

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HFO-1234yf at AC ConditionsThermodynamic Cycle Model Results:Evaporator Temp: 7 ºC Condenser Temp: 47 ºC

Liquid Refrigerant Subcool : 12 K

Suction Gas Superheat 3 K Suction Temperature 10 ºC

28164.378No1430R-134a

43714.225No1774R-407C

Capacity

kJ/m3

COPFlammable?

GWP

IPCC AR4

Refrigerant

26674.267Yes4HFO-1234yf

43004.299No1810R-22

62254.04No2088R-410A

Can use mixtures to create higher performance, low GWP replacements

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Formulation of Refrigerant Mixtures: Hierarchy of Desired Properties

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

COP vs 410A

0 to +1%+3 to +6%

+6 to +8%R-134a

R-410A

HFO-1234yf

Mildly Flammable Non FlammableG = Glide, K

R-22R-407C

R-32

0 G

4 G

1-3 G

5-7 G

4.8 G

R-134a

R-410A

HFO-1234yf

Mildly Flammable Non FlammableG = Glide, K

R-22R-407C

R-32

0 G

4 G

1-3 G

5-7 GCOP vs 410A

+0.5 to +1.5%+2 to +3%+3 to +5%+5 to +6%

0 %

R-134a

R-404A

HFO-1234yf

Mildly Flammable Non FlammableG = Glide, K

R-22

R-32

0 G4 G

COP vs 404A

-2 to 0%0%

+3 to +5%+7 to +8%

-3 %

1-3 G

5-7 G

5-6 G

R-134a

R-404A

HFO-1234yf

Mildly Flammable Non FlammableG = Glide, K

R-22

R-32

0 G

4 G

1-3 G

5-7 G

5-6 G

COP vs 404A

-4 to -3%-1 to 0%

+2 to +4%+7%

-6%

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Conclusions:• HFO-1234yf has been shown to be a safe, effective refrigerant for

environmentally sustainable solutions for MAC applications.• HFO-1234yf has excellent potential to replace R-134a for HVACR

applications where mild flammability can be managed. • HFO-1234yf 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.

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Containment is CriticalNo 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)

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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 – HFO-1234yf 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

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EN 60335-2-40 Residential A/C StandardRefrigerant Charge Size Guidelines

Charge sizesRefrigerant LFL (kg/m3) m1 (kg) m2 (kg) m3 (kg)

R32 0.306 1.22 8.0 39.8R1234yf 0.289 1.16 7.5 37.6R152a 0.130 0.52 3.4 16.9

Propane 0.038 0.15 1.0 4.9

charge size <m1 = no significant regulationsm1< charge < m2 = charge size lim ita tions based on room sizem2< charge < m3 = need mechanical ventilationcharge size > m3 = th is standard does not apply; use local standards