Rapid Measurements of Thermodynamic Properties for Alternative Refrigerants with Vibrating-Tube

Transcription

1 Rapid Measurements of Thermodynamic Properties for Alternative Refrigerants with Vibrating-Tube Densimeter Fifteenth Symposium on Thermophysical Properties Y. Kano : speaker M. Hasumoto Y. Kayukawa K. Watanabe June 7, 3 Boulder, CO, U.S.A Keio University, Yokohama, Japan

2 Table of Contents 1. Background. Measurement System 3. Experimental Results 4. Conclusions

3 Background -alternative refrigerants- 3 Growing a necessity of alternative refrigerants with zero ODP and low GWP CFCs HCFCs HFCs Hydrofluoroethers (HFEs( HFEs) Hydrocarbons (HCs( HCs) HFEs (developed by RITE) HCs characterized by characterized by Containing ether bond Natural refrigerants Zero ODP Zero ODP Low GWP (( 97) Vanishingly small GWP (( 3) Low- or non- flammability High- flammability

4 Background -previous works- 4 HFEs CF 3 OCH 3 (trifluoromethyl methyl ether) and CF 3 CF OCH 3 (pentafluoroethyl methyl ether) Widiatmo and Watanabe EoS A lack of PVT data HCs R-9(propane), R-6(nR 6(n-butane) and R-6a(isoR 6a(iso-butane) Miyamoto and Watanabe EoS Low-reliability due to old PVT data

5 Measurement System -experimental apparatus experimental apparatus- 5

6 Measurement System -densimeter principle- 6 Conventional model Resonance model m = m+ρv ρv k µ = m M m = m+ρv ρv k M m ρ = A( τ τ A = m V 1) Lower accuracy away from calibration points ρ = m (1 + µ )( τ A 1 µ ( τ τ 1) τ 1) Higher accuracy even away from calibration points

7 Measurement System - τ & µ calibration - 7 τ : dependent on τ 3.76 temperature measured under vacuum τ / ms µ = m /M : constant 3.64 Sep. 3, T / K determined by measuring density known fluids water iso-octane octane at K 11.3 kpa τ µ = { ρ ( τ τ ) ρ ( τ τ )} ( τ water water iso octane τ )( τ iso octane iso octane τ )( ρ water iso octane ρ iso octane ) µ =.3 ±.5

8 Measurement System - A calibration - 8 A = m /V : dependent on temperature and pressure A = 1 µ ( τ (1 + µ )( τ water water τ 1) ρ τ 1) water A( T, P) 3 = 1 i = j = T K aij 1 i ( P MPa) j water (reference fluid) uncertainty of EoS (IAPWS-95).1 % reproducibility of A(T,P) methanol.1 % uncertainty of EoS (IUPAC).1 % reproducibility of A(T,P).7 % 1(A exp -A cal )/A cal dev A % O water x methanol T, K

9 Measurement System -performance- 9 Uncertainties (ISO guideline) Uncertainties when coverage factor k = Pressure U= =.6 kpa +. % Temperature U= = 3 mk Density U= =.7 kgm % Mole fraction U= =.1 mol% Measurement range Pressure P / MPa 7 Temperature 4 T / K 38 Measurement efficiency Pure substance 1 - days Mixture - 3 days

10 Experimental Results -number of data- 1 substance purity composition phase measurement range No. of data mol% mol% T / K P / MPa - liquid CF 3 OCH vapor VLE liquid CF 3 CF OCH vapor VLE liquid R vapor VLE liquid R vapor VLE liquid R-6a vapor VLE /75. liquid R-9/6-5./5. liquid /5. liquid /75. liquid R-9/6a - 5./5. liquid /5. liquid /75. liquid R-6/6a - 5./5. liquid /5. liquid /33./33. liquid R-9/6/6a - 6././. liquid /6./. liquid VLE = vapor liquid equilibrium HFEs 534 points HCs 145 points Total 679 points

11 Experimental Results - HFEs - 11 Comparison with Widiatmo and Watanabe EoS (1) Systematic errors in lower temperatures (( 6 K)

12 Experimental Results - pure HCs - 1 Comparison with Miyamoto and Watanabe EoS () Increase of deviation in higher temperatures (( 3 K)

13 Experimental Results - HC mixtures - 13 R R-9/6/6a.75 R R-6a R-6/6a R-9/6 R-9/6a Measurements in wide range of compositions for R-9/6/6a system

14 Conclusions 14 Rapid-precise precise density measurement system was introduced. Low density uncertainty (.7 kgm %) Wide range of measurement (4 K-K 38 K, up to 7 MPa) Takes only a few days to complete whole measurement Large number of measurements were obtained for hydrofluoroethers and hydrocarbons. More than 5 measurements for hydrofluoroethers More than measurements for hydrocarbons The present experimental data will contribute to improvement of the existing EoS. Extension of the range of Widiatmo and Watanabe EoS for hydrofluoroethers Assessment of the reliability of Miyamoto and Watanabe EoS for hydrocarbons

15 Acknowledgements 15 Financial supports for the present study, the subsidy for Scientific Research Fund from to, Ministry of Education, Culture, Sports, Science and Technology, Japan the Research Institute of Innovative Technology for the Earth (RITE), Japan are greatly appreciated.