Aspen Physical Property System - Physical Property Models

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106 2 Thermodynamic Property Models (41) (42) (43) (44) (45) (46) (47) (48) It should be understood that and remained constant in equation 37 when deriving the activity coefficients given by equations 38-40. Parameters The model adjustable parameters include: � Pure component dielectric constant coefficient of nonaqueous solvents � Born radius of ionic species � NRTL interaction parameters for molecule-molecule, molecule-electrolyte, and electrolyte-electrolyte pairs Note that for the electrolyte-electrolyte pair parameters, the two electrolytes must share either one common cation or one common anion. Each type of the electrolyte NRTL parameter consists of both the nonrandomness factor, �, and energy parameters, �.
The pure component dielectric constant coefficients of nonaqueous solvents and Born radius of ionic species are required only for mixed-solvent electrolyte systems. The temperature dependency relations of these parameters are given in Electrolyte NRTL Activity Coefficient Model. Heat of mixing is calculated from temperature derivatives of activity coefficients. Heat capacity is calculated from secondary temperature derivative of the activity coefficient. As a result, the temperature dependent parameters are critical for modeling enthalpy correctly. It is recommended that enthalpy data and heat capacity data be used to obtain these temperature dependency parameters. See also Electrolyte NRTL Enthalpy and Electrolyte NRTL Gibbs Energy. Obtaining Parameters In the absence of electrolytes, the electrolyte NRTL model reduces to the NRTL equation which is widely used for non-electrolyte systems. Therefore, molecule-molecule binary parameters can be obtained from binary nonelectrolyte systems. Electrolyte-molecule pair parameters can be obtained from data regression of apparent single electrolyte systems. Electrolyte-electrolyte pair parameters are required only for mixed electrolytes with a common ion. Electrolyte-electrolyte pair parameters can affect trace ionic activity precipitation. Electrolyte-electrolyte pair parameters can be obtained by regressing solubility data of multiple component electrolyte systems. When the electrolyte-molecule and electrolyte-electrolyte pair parameters are zero, the electrolyte NRTL model reduces to the Debye-Hückel limiting law. Calculation results with electrolyte-molecule and electrolyte-electrolyte pair parameters fixed to zero should be adequate for very dilute weak electrolyte systems; however, for concentrated systems, pair parameters are required for accurate representation. See Physical Property Data, Chapter 1, for the pair parameters available from the electrolyte NRTL model databank. The table contains pair parameters for some electrolytes in aqueous solution at 100�C. These values were obtained by using the Aspen Physical Property Data Regression System (DRS) to regress vapor pressure and mole fraction data at T=100�C with SYSOP15S (Handbook of Chemistry and Physics, 56th Edition, CRC Press, 1975, p. E-1). In running the DRS, standard deviations for the temperature (�C), vapor pressure (mmHg), and mole fractions were set at 0.2, 1.0, and 0.001, respectively. In addition, complete dissociation of the electrolyte was assumed for all cases. Option Codes for Electrolyte NRTL Activity Coefficient Model (GMENRTL) The electrolyte NRTL activity coefficient model (GMENRTL) has three option codes and the option codes can affect the performance of this model. 2 Thermodynamic Property Models 107
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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
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Parameter Name/Element PRKBV/1 k ij
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Predictive SRK (PSRK) This model us
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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 and 102: with Where: xi = Mole fraction of c
Page 103 and 104: It should be understood that equati
Page 105 and 106: The reference Gibbs energy is deter
Page 107: Where: j and k can be any species (
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 /
Page 153 and 154: Symmetric and Unsymmetric Electroly
Page 155 and 156: Parameter Symbol No. of Name Elemen
Page 157 and 158: 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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