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Experimental Methods, Results and Discussion solvent and the control of the temperature of the entire system in order to avoid condensation of the vapor. Figure II.10. Experimental apparatus: Vi - Valves; PS - Pre-saturator; P - Vacuum gauge; M - Mercury Manometer; R - Mercury Reservoir The solvent is degassed thought successive melting/freezing cycles. The degassing cell, Vd, filled with pure solvent is connected to the solubility apparatus. Opening valve V1 the entire line is connected to a vacuum source, a RV3 high vacuum pump from Edwards, capable of reaching a vacuum of 0.08 mbar. The solvent is then degassed by successive melting/freezing cycles while vacuum pumping non-condensable gases. The degassing is considered complete when no pressure variation in two consecutive cycles is detected with the pressure gauge, P. Besides being an expeditious method, the quantity of solvent lost with this degassing method is minimum when compared with other degassing procedures. By turning upside down the degassing cell, the equilibrium cell is filled with the degassed solvent under its own vapor pressure. The pre-saturator is also filled with an amount of solvent enough to guarantee a correct saturation of the gas and the same degassing principle is used for its degasification. - 53 -
Experimental Methods, Results and Discussion After evacuating the system, the solute gas is introduced in the line through valve V3. Closing valves V2 and V5, the gas is forced to bubble slowly in the degassed solvent contained in the saturation chamber, PS to guarantee a complete saturation and the system is filled with the solvent-saturated gas to a total pressure close to 1 atm. When the mercury level in the manometer branches is equal, the system is isolated from the pre-saturator and allowed to equilibrate. It was found that the reproducibility of the measurements increases if the saturated gas is let to equilibrate for at least 10 hours. During this time, the equilibrium cell filled with the degassed solvent is closed to avoid solubilization of the gas into the solvent by diffusion. The equilibrium cell, Ve, is based on the design of Carnicer et al. (1979) and was previously calibrated with mercury, by measuring the mercury levels in the cell capillaries and the corresponding weight of mercury. A relation between mercury levels and the cell volume is obtained being the cell volume approximately 7 cm 3 . The dissolution process is initiated by turning the liquid circulation on, forcing the solvent up the right capillary arm and to circulate through the left capillary arm forming a very thin film. As the gas dissolves, the system pressure is maintained at initial pressure by allowing the mercury from the reservoir to displace the gas in the system. After 15 minutes more then 95% of the gas is already dissolved. For the studied fluorinated compounds, the equilibrium is reached in about ½ h. The system is considered to have reached equilibrium when no further gas is dissolved. The displacement of the mercury level is measured with a cathetometer with a precision of ± 0.01 mm. Direct reading of the mercury levels of mercury and solvent levels in the equilibrium cell are the only measurements required to calculate the volume of gas dissolved in a given volume of solvent. The entire apparatus is immersed in a Perspex isolated air bath capable of maintaining the temperature to within 0.1 K by means of a PID controller. The temperature is measured with a previously calibrated 25 Ω platinum resistance thermometer connected to a digital multimeter 34401A from Agilent for temperature values acquisition. - 54 -
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Ana Maria Antunes Dias Universidade
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o júri presidente Prof. Dr. Joaqui
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palavras-chave resumo perfluoroalca
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Contents Notation List of Tables Li
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Notation Abbreviations AAD EoS LCST
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List of Tables Table I.1 Average Bo
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Table III.6 Adjusted Binary Paramet
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Figure II.9 Comparison between corr
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Figure III.8 Temperature-density di
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Figure III.25 Vapor-phase mole frac
Page 21 and 22: I.1. Fluorine Properties General In
Page 23 and 24: Table I.2. Physicochemical Properti
Page 25 and 26: General Introduction order to compa
Page 27 and 28: General Introduction the numerous a
Page 29 and 30: General Introduction carbon dioxide
Page 31 and 32: General Introduction animals. That
Page 33 and 34: General Introduction Table I.3. Lit
Page 35 and 36: References General Introduction Ban
Page 37 and 38: General Introduction Hildebrand, J.
Page 39 and 40: General Introduction Rowinsky EK. N
Page 41 and 42: II. Part EXPERIMENTAL METHODS, RESU
Page 43 and 44: Experimental Methods, Results and D
Page 49 and 50: Table II.3. (continued) T K ρexp g
Page 51 and 52: ρ / g.cm-3 1.750 1.730 1.710 1.690
Page 55 and 56: I. 3. Vapour pressure I.3.1. Biblio
Page 57 and 58: I.3.2. Apparatus and Procedure Expe
Page 59 and 60: I.3.3. Experimental Results and Dis
Page 63 and 64: Table II.8. (continued) T K Pexp kP
Page 67 and 68: ΔH vap = TΔS vap 2⎛ d ln P ⎞
Page 69 and 70: I.4. Solubility at atmospheric pres
Page 71: Experimental Methods, Results and D
Page 79 and 80: x2 (T,P2) 7.0E-03 6.0E-03 5.0E-03 4
Page 81 and 82: L 2,1 0.70 0.60 0.50 0.40 0.30 285
Page 93 and 94: P / MPa 6 5 4 3 2 1 0 P / MPa 14 12
Page 95 and 96: II.6. Liquid - Liquid Equilibrium I
Page 101 and 102: 0 τ β Δ1 2Δ1 [ 1+ B τ + B τ +
Page 103 and 104: References Experimental Methods, Re
Page 111 and 112: III.1. Introduction Modeling Most c
Page 113 and 114: Modeling The pioneering work of Wer
Page 115 and 116: III.2. Soft-SAFT Model Modeling A S
Page 117 and 118: Modeling The equation of state is w
Page 119 and 120: Chain Term Modeling Originally Wert
Page 121 and 122: Modeling The model is easily extend
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( ) ( ) ∑∑∑ 3 2 2 2 2 qq 32π
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Modeling HRT is a promising theory,
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( ρ) ρ , 0 ≤ ρ ( ρ) 2 Modelin
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III.3. Application to Pure Compound
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Modeling From the optimised paramet
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T / K 400 350 300 250 200 150 100 5
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ln Pvap 1.0E+01 1.0E+00 1.0E-01 1.0
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Modeling Table III.2. Absolute Aver
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Modeling The correlation coefficien
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Pvap (MPa) 4.00 3.50 3.00 2.50 2.00
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Modeling The mixture parameters a a
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Modeling the assumptions made by th
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Modeling between oxygen and perfluo
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xSolute 5.5E-03 5.0E-03 4.5E-03 4.0
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Modeling previous work, dealing wit
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Modeling These results confirm that
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Modeling CO2 binary mixtures using
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Modeling average deviation (AAD) be
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P / MPa 14 12 10 8 6 4 2 0 0 0.2 0.
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Modeling Figures III.16, III.17 and
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Modeling calculations from the orig
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Table III.9. References for VLE exp
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P / MPa 20 18 16 14 12 10 8 6 4 2 0
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Modeling Finally, Figure III.24 pre
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III.4.4. VLE and LLE of Alkane and
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Modeling number of perfluro-n-alkan
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y C6F14 1.0 0.8 0.6 0.4 0.2 0.0 0.0
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P / MPa 0.08 0.07 0.06 0.05 0.04 0.
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P / MPa 0.12 0.10 0.08 0.06 0.04 0.
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Modeling approach based on the meth
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Modeling Blas, F. J.; Vega, L. F.,
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DIPPR, Thermophysical Properties Da
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Modeling Hildebrand, J. H.; Fisher,
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Modeling McCabe, C.; Jackson, SAFT-
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Modeling Poling, B.; Prauznitz, J.;
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Modeling Wertheim, M. S., Fluids wi
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