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

Transcription

1 Evaluation of HFO-1234yf as a Potential Replacement for R-134a in Refrigeration Applications Thomas J. Leck DuPont Fluorochemicals Wilmington, Delaware 3rd IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants, Boulder, CO, 2009

2 2 HFO-1234yf : Introduction R-134a HFO-1234yf Formula CH 2 FCF 3 CF 3 CF=CH 2 Molecular Weight ODP 0 0 GWP 100 (AR-4) Normal Boiling Point -26ºC -29ºC

3 3 Suitability for Use as Refrigerant Environmental GWP, ODP Thermophysical Equation of State Modeling Capacity, COP Thermochemical Thermal Stability Material Compatibility

4 4 HFO-1234yf - Environmental Properties HFO-1234yf Environmental Properties Established and Peer Reviewed ODP = 0 ; GWP 100 = 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 Chemical Physics Letters 439 (2007) pp (2008) pp

5 5 HFO-1234yf : Vapor Pressure REFPROP Equation Of State R-134a available Compression ratio: 134a: yf: 2.6 Vapor Pressure (MPa) 2 HFO-1234yf T cond =37.8 o C 0 T evap =4.4 o C Temperature, degrees C

6 6 Martin-Hou Equation of State General Form: P = RT V b + 5 i= 2 A i + B T i ( V + C e i i b) κt / T C For this work the equation was carried to only five terms, which gave sufficient accuracy. The coefficients are listed within the text of the paper, as are corollary equations and their coefficients.

7 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 T c and ρ c Data from Tanaka and Higashi (2008) P c from DuPont vapor pressure and Tanaka and Higashi T c Ideal Gas Heat Capacity From ab-initio molecular orbital calculations

8 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 = i C p cit i= 0

9 9 Saturated Liquid Density Correlation Saturated Liquid Density ρ L ρ C = 4 i= 0 d i X i, where ( ) 1/ 1 T / T 3 d5 X = C

10 10 Data Collection Overview P-H Diagram 1000 Measured Critical Properties Pressure 100 Liquid Region Saturated Liquid, Liquid density Two Phases Clausius Clapeyron Calculate H Vapor Region PVT Data Ideal Gas Heat Capacity Enthalpy

11 11 Comparisons HFO-1234yf vs R-134a Calculated Vapor Density Calculated Latent Heat 300 Vapor Density Comparison - R-1234yf vs R-134a Latent Heat Comparison R-1234fy vs R-134a 250 R-134a R-134a HFO-1234yf Density kg/m R-1234yf latent Heat kj/kg Temperature C Temperature C

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13 PH Diagram R-134a from MH EOS 13

14 14 Comparison of HFO-1234yf and HFC-134a P-H Diagram 1000 Pressure [psia] 100 R134a 1234yf Enthalpy [BTU/lb]

15 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-134a R-134a yf % % R-134a yf % % Capacity and COP Compare Well to R-134a!

16 16 HFO-1234yf Thermodynamic Performance vs.. HFC-134a: I 1000 Isentropic Compressor Enthalpy Rise: -20% Required Impeller Tip Speed: -10% R134a 1234yf Pressure [psia] T evap =4.4 o C; T cond =37.8 o C; T suph =0 o C; T subc =0 o C Enthalpy [BTU/lb]

17 17 HFO-1234yf Thermodynamic Performance vs.. HFC-134a: II 1000 Net Refrigeration Effect: -23% Volumetric Capacity: -7% R134a 1234yf Pressure [psia] T evap =4.4 o C; T cond =37.8 o C; T suph =0 o C; T subc =0 o C Enthalpy [BTU/lb]

18 Compatibility with Plastics 18 % weight change after 2 100ºC in HFO-1234yf vs. HFC-134a Polymer On Removal On Removal 24 Hrs later 24 Hrs later Polyester Resin HFC-134a HFO-1234yf HFC-134a HFO-1234yf Nylon Resin Epoxy Resin Polyester PBT Polycarbonate Polyimid Polyethylene PTFE FEP ETFE Phenolic Acetal PET Film

19 19 Elastomers: Exposure at 100 ºC for 14 days Elastomer HFO-1234yf Immediately After Exposure % weight change linear swell delta hardness R-134a Immediately After Exposure % weight change linear swell delta hardness Neoprene WRT HNBR NBR EPDM (Nordel) Silicone Butyl Rubber Buna S (SBR) Viton Hypalon neoprene o-ring RESULT: HFO-1234yf has similar effect on elastomers

20 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

21 21 Miscibility in ISO 120 POE: HFO-1234yf vs. R-134a Branched Acid POE Lubricant Refrigerant: HFO 1234yf Temperature (C) Lubricant: ISO120 Branched Acid POE % POE % 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 N 15% 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 N 20% 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 N 30% 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 N 60% 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 70% 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-134a Lubricant: ISO120 Branched Acid POE Temperature (C) % POE % 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 M 15% 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 20% 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 30% 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 60% 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 M 70% 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

22 22 Miscibility in ISO 68 POE: HFO-1234yf vs. R-134a 68 cst Mixed Acid POE Refrigerant: HFO 1234yf Lubricant: ISO 68 Mixed Acid POE Temperature (C) % POE % 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 N 15% 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 N 20% 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 N 30% 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 N 60% 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 70% 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-134a Lubricant: ISO 68 Mixed Acid POE Temperature (C) % POE % 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 M 15% 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 N 20% 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 N 30% 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 N 60% 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 M 70% 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

23 23 HFO-1234yf Thermal Stability I AFTER TWO 175 C HFO-1234yf/POE vs. HFC-134a/POE Front View Side View HFO-1234yf HFC-134a HFO-1234yf HFC-134a No Detectable Fluoride nor Acid Generation

24 24 HFO-1234yf Thermal Stability II Neat HFO-1234yf vs. Neat HFC-134a After o C HFO-1234yf HFC-134a No Detectable Fluoride nor Acid Generation

25 25 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

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28 28 HFO-1234yf Flammability: LFL a UFL a (UFL- LFL) MIE BV (vol%) (vol%) (vol%) (mj) (cm/s) Propane R152a R b 6.7 Ammonia b 7.2 HFO-1234yf ,000-10,000 b 1.5 c a Flame limits measured at 21 o C, ASTM b Tests run in 12 liter flask to minimize wall quenching effects c HFO-1234yf BV measured by AIST, Japan Mildly Flammable