Aspen Physical Property System - Physical Property Models

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The expression for the activity coefficient can be derived from (7): The Debye-Hückel theory is based on the infinite dilution reference state for ionic species in the actual solvent media. For systems with water as the only solvent, the reference state is the infinite dilution aqueous solution. For mixed-solvent systems, the reference state for which the Debye-Hückel theory remains valid is the infinite dilution solution with the corresponding mixed-solvent composition. However, the molecular weight Ms, the mass density ds, and the dielectric constant �s for the single solvent need to be extended for mixed solvents; simple composition average mixing rules are adequate to calculate them as follows: Where: 100 2 Thermodynamic Property Models (8) (6a) (7a) (8a) (8b) (8c) (8d) xm = Mole fraction of the solvent m in the solution Mm = Molecular weight of the solvent m Vm l = Molar volume of the solvent mixture �m = Dielectric constant of the solvent m Vw * = Molar volume of water using the steam table xnws = Sum of the mole fractions of all non-water solvents. Vnws l = Liquid molar volume for the mixture of all nonwater solvents. It is calculated using the Rackett equation.
It should be understood that equations 6a-8a should be used only in equations 3, 4, and 7. Ms, ds, and �s were already assumed as constants when deriving equations 6 and 8 for mixed-solvent systems. Local Interaction Contribution The local interaction contribution is accounted for by the Non-Random Two Liquid theory. The basic assumption of the NRTL model is that the nonideal entropy of mixing is negligible compared to the heat of mixing: this is indeed the case for electrolyte systems. This model was adopted because of its algebraic simplicity and its applicability to mixtures that exhibit liquid phase splitting. The model does not require specific volume or area data. The effective local mole fractions Xji and Xii of species j and i, respectively, in the neighborhood of i are related by: Where: Xj = xjCj Gji �ji 2 Thermodynamic Property Models 101 = = (9) (Cj = zj for ions and Cj = unity for molecules) �ji = Nonrandomness factor gji and gii are energies of interaction between species j and i, and i and i, respectively. Both gij and �ij are inherently symmetric (gij = gji and �ij = �ji). Similarly, Where: Gji,ki �ji,ki = = �ji,ki = Nonrandomness factor Apparent Binary Systems (10) The derivations that follow are based on a simple system of one completely dissociated liquid electrolyte ca and one solvent B. They will be later extended
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Aspen Physical Property System Phys
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Contents Contents..................
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General Pure Component Solid Molar
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1 Introduction This manual describe
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Pure Component Temperature- Depende
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the Properties Parameters Pure-Comp
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2 Thermodynamic Property Models Thi
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Property Model Model Name Phase(s)P
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Property Model Model Name 2 Thermod
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Where: Parameter Name/Element 2 The
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critical temperature, the critical
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Where the ideal-gas contribution
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, where � For polar, associating
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Parameter Name/ Element 2 Thermodyn
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The denominator of equation 8 is gi
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V. V. De Leeuw and S. Watanasiri, "
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References M. Benedict, G. B. Webb,
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References L. Haar, J.S. Gallagher,
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Parameter Name/Element NTHDDH 0 †
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Gibbs free energy departure: The fo
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For a block copolymer, there is onl
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Copolymer PC-SAFT Dispersion Term T
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The association-site number of the
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Then I2(�) and I3(�) are comput
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A databank called PC-SAFT contains
Page 51 and 52: Parameter Name/Element PRKBV/1 k ij
Page 53 and 54: Predictive SRK (PSRK) This model us
Page 55 and 56: ka,ij kb,ij = = For best results, b
Page 57 and 58: J. Schwartzentruber and H. Renon, "
Page 59 and 60: Redlich-Kwong-Soave-MHV2 This equat
Page 61 and 62: ‡ RKUC0, RKUC1, and RKUC2 are tre
Page 63 and 64: Parameter Name/ Element SRKLIJ/3 l
Page 65 and 66: Parameter Name/ Element Symbol Defa
Page 67 and 68: Association Equilibria Every associ
Page 69 and 70: and respectively. For the reactions
Page 71 and 72: R. W. Long, J. H. Hildebrand, and W
Page 73 and 74: Where the L, M, and N are parameter
Page 75 and 76: Alpha function Model name First Opt
Page 77 and 78: mi = Computed by equation 6 Equatio
Page 79 and 80: Parameter Name/Element 2 Thermodyna
Page 81 and 82: standard RKS alpha function, except
Page 83 and 84: These mixing rules are discussed se
Page 85 and 86: Where both Ai* and Am are calculate
Page 87 and 88: Like Huron and Vidal, the limiting
Page 89 and 90: Model Type Wilson Local composition
Page 91 and 92: Therefore, the simplified Pitzer eq
Page 93 and 94: Parameter Name/Element Symbol Defau
Page 95 and 96: Where: �i 2 Thermodynamic Propert
Page 97 and 98: The electrolyte NRTL model uses the
Page 99 and 100: Parameter Symbol No. of Name Elemen
Page 101: with Where: xi = Mole fraction of c
Page 105 and 106: The reference Gibbs energy is deter
Page 107 and 108: Where: j and k can be any species (
Page 109 and 110: The pure component dielectric const
Page 111 and 112: 2 Thermodynamic Property Models 109
Page 113 and 114: �I *PDH = Pitzer-Debye-Hückel te
Page 115 and 116: Where: �i Vi = Activity coefficie
Page 117 and 118: Recommended cij Values for Differen
Page 119 and 120: Parameter Name/ Element 2 Thermodyn
Page 121 and 122: NRTL-SAC Reference States The NRTL-
Page 123 and 124: 2 Thermodynamic Property Models 121
Page 125 and 126: For an anionic component, we have M
Page 127 and 128: For a molecular segment, the activi
Page 129 and 130: Specifically, The long range intera
Page 131 and 132: where and are activity coefficients
Page 133 and 134: and Y+, are used to reflect the wid
Page 135 and 136: Parameter Name/ Element Symbol Defa
Page 137 and 138: Reference C.-C. Chen and Y. Song, "
Page 139 and 140: Parameter Name GMPTPS, GMPTP1, GMPT
Page 141 and 142: zi = Charge of ion i Subscripts c,
Page 143 and 144: For option code = 0 (default), the
Page 145 and 146: and for n-m electrolytes: 2 Thermod
Page 147 and 148: = 0.00979 Perform the necessary con
Page 149 and 150: Pitzer, K.S., J.R. Peterson, and L.
Page 151 and 152: A4,ij = gij / T + hij A5,ij = mij /
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Symmetric and Unsymmetric Electroly
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Parameter Symbol No. of Name Elemen
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Reference state for ionic component
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with 2 Thermodynamic Property Model
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G for these pairs is calculated the
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with 2 Thermodynamic Property Model
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2 Thermodynamic Property Models 163
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Activity Coefficient Basis for Henr
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Where is the liquid Gibbs free ener
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Ionic components 2 Thermodynamic Pr
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the pure fused salts. Applying Eq.
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�k is the activity coefficient of
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References U. Weidlich and J. Gmehl
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ti' = �ij 2 Thermodynamic Propert
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Wagner Interaction Parameter The Wa
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References G.M. Wilson, J. Am. Chem
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Extended Antoine Equation Parameter
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IK-CAPE Vapor Pressure Equation The
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Harlacher and Braun, "A Four-Parame
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Parameter Name/Element 2 Thermodyna
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General Pure Component Heat of Vapo
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IK-CAPE Heat of Vaporization Equati
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Where: xp = Mole fraction of pseudo
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Parameter Name/Element VLBROC/1 V i
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Where: Vm l,t = Liquid volume per n
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Debye-Hückel Volume The Debye-Hüc
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DIPPR DIPPR equation 105 is the def
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Rackett The Rackett equation is: Wh
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Rackett/Campbell-Thodos Mixture Liq
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Zm RA Zi *,RA Vcm 2 Thermodynamic P
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General Pure Component Solid Molar
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Liquid Volume Quadratic Mixing Rule
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If THRSWT/6 is This equation is use
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Parameter Symbol Default MDS Lower
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General Pure Component Ideal Gas He
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(Other DIPPR equations may sometime
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General Pure Component Solid Heat C
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Parameter Name/Element 2 Thermodyna
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The expression for the liquid mole
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� Entropy: � Heat capacity: �
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Parameter Name † /Element CPIXPn/
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Option Codes for Electrolyte NRTL E
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Parameter Name Applicable Component
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For subcritical components: Hm l -H
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The vapor enthalpy is calculated fr
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Where: 2 Thermodynamic Property Mod
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Correlation algorithms for ionic sp
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Model Model name Phase(s) Pure Mixt
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Model Type Aspen Liquid Mixture Vis
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(Other DIPPR equations may sometime
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�i = Viscosity of component i (N-
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Parameter Name/Element 3 Transport
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Where: The Stockmayer or Lennard-Jo
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Where: Vcij = �ij = 0 (in almost
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Where: Vcij = �ij = 0 (in almost
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Jones-Dole Electrolyte Correction T
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Letsou-Stiel The Letsou-Stiel model
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Where: The parameter is the mole fr
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Reference C.H. Twu, "Internally Con
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Vcij 3 Transport Property Models 27
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You must provide parameters for the
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Linear extrapolation of � *,l ver
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If TRNSWT/4 is This equation is use
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References R.C. Reid, J.M. Prausnit
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The mixture surface tension is then
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Where: �solv = Dielectric constan
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4 Nonconventional Solid Property Mo
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wij = Mass fraction of the jth cons
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The oxygen and organic sulfur conte
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Parameter Name/Element Symbol Defau
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The complete oxidation of carbon is
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Parameter Name/Element Symbol Defau
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The equation for �i dm is good fo
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5 Property Model Option Codes The f
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Model Name Option Code 5 Property M
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Model Name Option Code 5 Property M
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Soave-Redlich-Kwong Option Codes Th
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Model Name Option Code HLRELNRT and
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Model Name Option Code GLRELNRT, GL
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Index A activity coefficient models
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ideal gas/DIPPR heat capacity model
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S Sato-Riedel/DIPPR thermal conduct
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Aspen Physical Property System - Physical Property Models

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