Evaluation of HFO-1234yf as a Potential Replacement for R-134ain Refrigeration Applications

Thomas J. LeckDuPont Fluorochemicals

Wilmington, Delaware

3rd IIR Conference on Thermophysical Propertiesand Transfer Processes of Refrigerants, Boulder, CO, 2009

2

HFO-1234yf : Introduction

R-134a HFO-1234yf

Formula CH2FCF3

102

ODP 0 0

GWP100 (AR-4) 1430 4

-26ºC

Molecular WeightCF3CF=CH2

114

-29ºCNormal Boiling Point

3

Suitability for Use as Refrigerant

Environmental

GWP, ODP

Thermophysical

Equation of State Modeling

Capacity, COP

Thermochemical

Thermal Stability

Material Compatibility

4

HFO-1234yf - Environmental Properties

ODP = 0 ; GWP100 = 4

Atmospheric lifetime = 11 days

Atmospheric chemistry determined• Atmospheric breakdown products are the same as for 134a

• No high GWP breakdown products

Good LCCP established for MAC

TEWI for Stationary AC&R looks good

HFO-1234yf Environmental PropertiesEstablished and Peer Reviewed

Chemical Physics Letters

439 (2007) pp 18-22

450 (2008) pp 263-267

5

REFPROP EquationOf State available

0

0.5

1

1.5

2

2.5

3

3.5

-40 -20 0 20 40 60 80 100

R-134a

HFO-1234yf

Vapo

r Pre

ssur

e (M

Pa)

Temperature, degrees C

Tevap=4.4 oC

Tcond=37.8 oC

Compression ratio:134a: 2.8

1234yf: 2.6

HFO-1234yf : Vapor Pressure

6

Martin-Hou Equation of State

General Form:

∑=

−

−++

+−

=5

2

/

)(ii

TTiii

bVeCTBA

bVRTP

Cκ

For this work the equation was carried to only five terms, whichgave sufficient accuracy. The coefficients are listed within the text of the paper, as are corollary equations and their coefficients.

7

Measured Data Requirements•Saturated vapor pressure•Liquid Density•Vapor phase PVT

• All Measured by C.P Kao at DuPont• accuracy of 0.5 % to 1 % relative

•Critical Point Data• Tc and ρc Data from Tanaka and Higashi (2008)• Pc from DuPont vapor pressure and Tanaka and Higashi Tc

•Ideal Gas Heat Capacity• From ab-initio molecular orbital calculations

8

Fitting of Data to Equation

Single Phase vapor region:

Lee Kessler Corresponding Equation of State (Huber, Ely)

Then modification of coefficients to fit to MH form (Yokozeki)

Ideal Gas Heat Capacity determined from ab-initio molecular orbital calculation, (Gaussian-03), with results correlated using polynomial equations necessary to establish saturated vapor enthalpy.

∑=

=5

0

0

i

iip TcC

9

Saturated Liquid Density Correlation

Saturated Liquid Density

∑=

=4

0i

iiCL Xdρρ , where

( ) 53/1/1 dTTX C −−=

10

Data Collection Overview

P-H Diagram

10

100

1000

-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Enthalpy

Pres

sure

Liquid RegionSaturated Liquid,Liquid density

Vapor RegionPVT DataIdeal Gas Heat Capacity

Two PhasesClausius ClapeyronCalculate ∆ H

MeasuredCritical Properties

11

Comparisons HFO-1234yf vs R-134a

Vapor Density Comparison - R-1234yf vs R-134a

0

50

100

150

200

250

300

-60 -10 40 90

Temperature C

Den

sity

kg

/m3

R-134a

R-1234yf

Latent Heat Comparison R-1234fy vs R-134a

0.000

50.000

100.000

150.000

200.000

250.000

-60 -10 40 90

Temperature C

late

nt

Hea

t kJ

/kg

R-134a

HFO-1234yf

Calculated Vapor Density Calculated Latent Heat

12

13

PH Diagram R-134a from MH EOS

14

Comparison of HFO-1234yf and HFC-134aP-H Diagram

10

100

1000

-30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Enthalpy [BTU/lb]

Pres

sure

[psi

a]

R134a1234yf

15

Commercial Freezer Model Comparison

Cycle Model for Retail Ice Cream Vending

Assumptions: Suction Line Heat Exchanger

Compressor Suction: 15 C

Evap Cond Cap Cap rel. COP rel.Refrig. T ºC T ºC kJ/m3 to R-134a COP to R-134aR-134a -12 35 1362.6 3.128 1234yf -12 35 1353.4 99.32% 3.064 97.95%R-134a -12 47 1210.3 2.29 1234yf -12 47 1167.15 96.43% 2.191 95.68%

Capacity and COP Compare Well to R-134a !

16

Tevap=4.4 oC; Tcond=37.8 oC; ∆Tsuph=0 oC; ∆Tsubc=0 oC

10

100

1000

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150Enthalpy [BTU/lb]

Pres

sure

[psi

a ]

R134a1234yf

Isentropic Compressor Enthalpy Rise: -20%Required Impeller Tip Speed: -10%

HFO-1234yf Thermodynamic Performance vs.. HFC-134a: I

17

10

100

1000

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150Enthalpy [BTU/lb]

Pres

sure

[psi

a ]

R134a1234yf

Net Refrigeration Effect: -23% Volumetric Capacity: -7%

HFO-1234yf Thermodynamic Performance vs.. HFC-134a: II

Tevap=4.4 oC; Tcond=37.8 oC; ∆Tsuph=0 oC; ∆Tsubc=0 oC

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

Polymer On Removal On Removal 24 Hrs later 24 Hrs laterHFC-134a HFO-1234yf HFC-134a HFO-1234yf

Polyester Resin

7.6 4.2 2.2 2.3

Nylon Resin 0.3 -0.2 -0.5 -0.4Epoxy Resin 0.1 -0.1 -0.3 -0.1Polyester PBT 12.5 1.1 12.3 1.1Polycarbonate 4.2 0.9 3.9 0.8Polyimid 3.7 3.4 3.2 3.2Polyethylene 1.3 1.7 1.1 1.3PTFE 2.7 3.0 2.3 2.4FEP 3.1 3.8 2.7 3.2ETFE 6.0 4.9 4.8 4.2Phenolic -0.8 -0.8 -1.0 -0.8Acetal 2.7 0.7 2.1 0.6PET Film 0.8 -1.0 -1.3 -2.1

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Elastomers: Exposure at 100 ºC for 14 days

Elastomer% weight change

linear swell

delta hardness

% weight change

linear swell

delta hardness

Neoprene WRT 2.4 0.4 0.3 2.6 1.3 0.7HNBR 5.2 1.5 -8.7 15.2 4.5 -7.3NBR 5.8 1.2 7.3 14.1 3.5 3.0

EPDM (Nordel) 3.5 0.7 1.7 3.6 0.5 0.3Silicone 2.0 0.0 1.7 10.6 2.3 0.3

Butyl Rubber 5.0 1.5 -2.3 4.1 0.8 0.3Buna S (SBR) 2.1 0.4 -9.7 2.7 0.4 -11.3

Viton 20.0 7.2 -20.3 47.4 15.1 -24.0Hypalon 2.7 0.9 -2.3 3.2 0.8 -3.3

neoprene o-ring 3.0 -2.5 1.0 -0.4 -2.2 1.0

Immediately After ExposureHFO-1234yf R-134a

Immediately After Exposure

RESULT: HFO-1234yf has similar effect on elastomers

20

HFO-1234yf Miscibility in Common Stationary AC&R Lubricants

Mineral Oil Non Miscible

Alkyl Benzene Non Miscible

Polyol Ester Miscible

Similar to HFC-134a

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Miscibility in ISO 120 POE: HFO-1234yf vs. R-134aBranched Acid POE Lubricant

Refrigerant: HFO 1234yf Temperature (C)Lubricant: ISO120 Branched Acid POE

% POE -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 905% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

10% M M M M M M M M M M M M M M M M M M M M M M M M M M M N N15% M M M M M M M M M M M M M M M M M M M M M M M M M M N N N20% M M M M M M M M M M M M M M M M M M M M M M M M M M N N N30% M M M M M M M M M M M M M M M M M M M M M M M M M M N N N60% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M70% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

Refrigerant: HFC-134aLubricant: ISO120 Branched Acid POE Temperature (C)

% POE -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 905% N N N M M M M M M M M M M M M M M M M M M M M M M M M M M

10% N N N N N N M M M M M M M M M M M M M M M M M M M M M M M15% N N N N N N N M M M M M M M M M M M M M M M M M M M M M M20% N N N N N N N M M M M M M M M M M M M M M M M M M M M M M30% N N N N N N N M M M M M M M M M M M M M M M M M M M M M M60% N M M M M M M M M M M M M M M M M M M M M M M M M M M M M70% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

HFO-1234yf has larger miscibility range

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Miscibility in ISO 68 POE: HFO-1234yf vs. R-134a68 cSt Mixed Acid POE

Refrigerant: HFO 1234yfLubricant: ISO 68 Mixed Acid POE Temperature (C)

% POE -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 905% M M M M M M M M M M M M M M M M M M M M M M M M M M M M N

10% N N N M M M M M M M M M M M M M M M M M M M M M M N N N N15% N N N N N M M M M M M M M M M M M M M M M M M M N N N N N20% N N N N N M M M M M M M M M M M M M M M M M M N N N N N N30% N N N N N M M M M M M M M M M M M M M M M M M N N N N N N60% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M70% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

Refrigerant: HFC-134aLubricant: ISO 68 Mixed Acid POE Temperature (C)

% POE -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 905% N N N N N N N M M M M M M M M M M M M M M M M M M M M M M

10% N N N N N N N N N N M M M M M M M M M M M M M M M M M M M15% N N N N N N N N N N N M M M M M M M M M M M M M M M M M N20% N N N N N N N N N N N N M M M M M M M M M M M M M M M M N30% N N N N N N N N N N N N M M M M M M M M M M M M M M M M N60% N N N N M M M M M M M M M M M M M M M M M M M M M M M M M70% M M M M M M M M M M M M M M M M M M M M M M M M M M M M M

HFO-1234yf has larger miscibility range

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HFO-1234yf Thermal Stability I

HFO-1234yf HFC-134a HFC-134aHFO-1234yf

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

WEEKS @ 175 °C

Front View Side View

No Detectable Fluoride nor Acid Generation

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HFO-1234yf Thermal Stability IINeat HFO-1234yf vs. Neat HFC-134a

After 2 wks @ 200 oC

HFO-1234yf HFC-134a

No Detectable Fluoride nor Acid Generation

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Summary and Conclusions:

•A Martin-Hou Equation of State Model has been Developed for HFO-1234yf and used to model a variety of refrigeration cycles.

•HFO-1234yf has good refrigeration properties, similar to R-134a

•It can be considered for use in a wide range of R-134a applications

•HFO-1234yf is compatible with motor and sealing materials

•HFO-1234yf has good miscibility in POE lubricants

•HFO-1234yf shows good thermal stability

26

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HFO-1234yf Flammability:

LFLa

(vol%)

UFLa

(vol%)(UFL- LFL)

(vol%)

MIE

(mJ)

BV

(cm/s)

Propane 2.2 10.0 7.8 0.25 46

R152a 3.9 16.9 13.0 0.38 23

R32 14.4 29.3 14.9 30-100b 6.7

Ammonia 15.0 28.0 13.0 100-300b 7.2

HFO-1234yf 6.2 12.3 6.1 5,000-10,000b

1.5c

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